WorldWideScience

Sample records for deposit formation dynamics

  1. Molecular dynamics simulation of the formation of sp3 hybridized bonds in hydrogenated diamondlike carbon deposition processes.

    Science.gov (United States)

    Murakami, Yasuo; Horiguchi, Seishi; Hamaguchi, Satoshi

    2010-04-01

    The formation process of sp3 hybridized carbon networks (i.e., diamondlike structures) in hydrogenated diamondlike carbon (DLC) films has been studied with the use of molecular-dynamics simulations. The processes simulated in this study are injections of hydrocarbon (CH3 and CH) beams into amorphous carbon (a-C) substrates. It has been shown that diamondlike sp3 structures are formed predominantly at a subsurface level when the beam energy is relatively high, as in the "subplantation" process for hydrogen-free DLC deposition. However, for hydrogenated DLC deposition, the presence of abundant hydrogen at subsurface levels, together with thermal spikes caused by energetic ion injections, substantially enhances the formation of carbon-to-carbon sp3 bonds. Therefore, the sp3 bond formation process for hydrogenated DLC films essentially differs from that for hydrogen-free DLC films.

  2. Formation Dynamics of CH3NH3PbI3 Perovskite Following Two-Step Layer Deposition.

    Science.gov (United States)

    Patel, Jay B; Milot, Rebecca L; Wright, Adam D; Herz, Laura M; Johnston, Michael B

    2016-01-07

    Hybrid metal-halide perovskites have emerged as a leading class of semiconductors for optoelectronic devices because of their desirable material properties and versatile fabrication methods. However, little is known about the chemical transformations that occur in the initial stages of perovskite crystal formation. Here we follow the real-time formation dynamics of MAPbI3 from a bilayer of lead iodide (PbI2) and methylammonium iodide (MAI) deposited through a two-step thermal evaporation process. By lowering the substrate temperature during deposition, we are able to initially inhibit intermixing of the two layers. We subsequently use infrared and visible light transmission, X-ray diffraction, and photoluminescence lifetime measurements to reveal the room-temperature transformations that occur in vacuum and ambient air, as MAI diffuses into the PbI2 lattice to form MAPbI3. In vacuum, the transformation to MAPbI3 is incomplete as unreacted MAI is retained in the film. However, exposure to moist air allows for conversion of the unreacted MAI to MAPbI3, demonstrating that moisture is essential in making MAI more mobile and thus aiding perovskite crystallization. These dynamic processes are reflected in the observed charge-carrier lifetimes, which strongly fluctuate during periods of large ion migration but steadily increase with improving crystallinity.

  3. Study of dynamics of diffusion and cluster formation of copper deposition on polyimide by optical second-harmonic generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.Y.; Shen, Y.R. (Department of Physics, University of California, Berkeley, California 94720 (United States)); Soane, D.S. (Department of Chemical Engineering, University of California, Berkeley, California 94720 (United States))

    1992-03-15

    We demonstrate that optical second-harmonic generation (SHG) can be successfully used for {ital in} {ital situ} study of metal/polymer interfaces. With this SHG technique, Cu cluster formation on polyimide by surface diffusion and Cu diffusion into polyimide have been investigated. The diffusion coefficients of Cu clusters into polyimide at various temperatures have been determined from the measured decay of SHG signal with time. The effects of temperature, cluster size, and surface modification on diffusion have also been examined. For {ital T} {lt} {ital T}{sub {ital g}}, the surface diffusion of Cu on polyimide to form clusters dominates over the diffusion into the bulk. The latter process becomes competitive with increasing temperature. When {ital T} {gt} {ital T}{sub {ital g}}, few large-size Cu clusters can be formed on the polyimide surface. Cu diffusion into polyimide bulk can be greatly impeded by either a monolayer of Ti or by Cu clusters implanted in polyimide beforehand. In this case, Cu can wet the modified surface and form an interface between Cu and polyimide with good adhesion.

  4. Deposit formation in hydrocarbon rocket fuels

    Science.gov (United States)

    Roback, R.; Szetela, E. J.; Spadaccini, L. J.

    1981-01-01

    An experimental program was conducted to study deposit formation in hydrocarbon fuels under flow conditions that exist in high-pressure, rocket engine cooling systems. A high pressure fuel coking test apparatus was designed and developed and was used to evaluate thermal decomposition (coking) limits and carbon deposition rates in heated copper tubes for two hydrocarbon rocket fuels, RP-1 and commercial-grade propane. Tests were also conducted using JP-7 and chemically-pure propane as being representative of more refined cuts of the baseline fuels. A parametric evaluation of fuel thermal stability was performed at pressures of 136 atm to 340 atm, bulk fuel velocities in the range 6 to 30 m/sec, and tube wall temperatures in the range 422 to 811 K. Results indicated that substantial deposit formation occurs with RP-1 fuel at wall temperatures between 600 and 800 K, with peak deposit formation occurring near 700 K. No improvements were obtained when deoxygenated JP-7 fuel was substituted for RP-1. The carbon deposition rates for the propane fuels were generally higher than those obtained for either of the kerosene fuels at any given wall temperature. There appeared to be little difference between commercial-grade and chemically-pure propane with regard to type and quantity of deposit. Results of tests conducted with RP-1 indicated that the rate of deposit formation increased slightly with pressure over the range 136 atm to 340 atm. Finally, lating the inside wall of the tubes with nickel was found to significantly reduce carbon deposition rates for RP-1 fuel.

  5. Theory of Cast Formation in Electrophoretic Deposition

    NARCIS (Netherlands)

    Biesheuvel, P. Maarten; Verweij, Henk

    1999-01-01

    The rate of cast formation in electrophoretic deposition is described by a combination of the equation of continuity for the suspension phase with expressions for the particle velocity and the movement of the cast-suspension boundary. The assumptions necessary to arrive at the well-known equations o

  6. On Biochemical Formation of Salt Deposits

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A water/salt system in an evaporative environment is both a physicochemical region and a biological one. All the parameters of the system, such as the salinity, temperature and CO2 partial pressure, are affected by halophilic bacteria. The system controls salt deposition but is modified by an accompanying ecological system; therefore it should be called a water/salt/biological system. Salt minerals result from accumulation of the remains of bacteria/algae, namely, bacteria/algae formation; whereas biological, biophysical and biochemical processes provide full evidence for organic involvement. Consequently, salt deposits should not be called purely chemical but biological/chemical ones. This new argument supplements and develops the traditional idea and helps perfect the mineralization theory of salts and even general deposits, thus giving guidance to prospecting for salt deposits.

  7. Liquefier Dynamics in Fused Deposition

    DEFF Research Database (Denmark)

    Bellini, Anna; Guceri, Selcuk; Bertoldi, Maurizio

    2004-01-01

    Layered manufacturing (LM) is an evolution of rapid prototyping (RP) technology whereby a part is built in layers. Fused deposition modeling (FDM) is a particular LM technique in which each section is fabricated through vector style deposition of building blocks, called roads, which...

  8. A depositional model for organic-rich Duvernay Formation mudstones

    Science.gov (United States)

    Knapp, Levi J.; McMillan, Julia M.; Harris, Nicholas B.

    2017-01-01

    The Upper Devonian Duvernay Formation of western Canada is an organic-rich shale formation now targeted as a hydrocarbon reservoir. We present a detailed sedimentological analysis of the Duvernay Formation in order to better understand organic-rich mudstone depositional processes and conditions and to characterize the vertical and lateral heterogeneity of mudstone lithofacies that affect petrophysical and geomechanical rock properties. Organic-rich mudstone facies of the Duvernay Formation were deposited in a dynamic depositional environment by a variety of sediment transport mechanisms, including suspension settling, turbidity currents, and bottom water currents in variably oxygenated bottom waters. Suspension settling dominated in distal relatively deep areas of the basin, but evidence for weak turbidity currents and bottom water currents was observed in the form of graded beds and thin grain-supported siltstone laminae. Organic enrichment primarily occurred in distal areas as a result of bottom water anoxia and low depositional rates of inorganic sediment. In deep water locations near platform margins, alternating silty-sandy contourite beds and organic-rich mudstone beds are present, the former interpreted to have been deposited and reworked by bottom water currents flowing parallel to slope. In shallower, more oxygenated settings, mudstone lithologies vary from calcareous to argillaceous. These sediments were deposited from suspension settling, turbidity currents, and bottom water currents, although primary sedimentary structures are often obscured by extensive bioturbation. Locally, organic enrichment in dysoxic rather than anoxic bottom waters was driven by a slightly increased sedimentation rate and possibly also by aggregation of sedimentary particles in the water column due to interaction between organic matter and clay minerals. Large variations observed in sediment composition, from siliceous to calcareous to argillaceous, reflect multiple biogenic

  9. Tidal current-induced formation——storm-induced change——tidal current-induced recovery——Interpretation of depositional dynamics of formation and evolution of radial sand ridges on the Yellow Sea seafloor

    Institute of Scientific and Technical Information of China (English)

    张长宽; 张东生; 张君伦; 王震

    1999-01-01

    The results of simulated tidal current field, wave field and storm-induced current field are employed to interpret the depositional dynamic mechanism of formation and evolution of the radial sand ridges on the Yellow Sea seafloor. The anticlockwise rotary tidal wave to the south of Shandong Peninsula meets the following progressive tidal wave from the South Yellow Sea, forming a radial current field outside Jianggang. This current field provides a necessary dynamic condition for the formation and existence of the radial sand ridges on the Yellow Sea seafloor. The results of simulated "old current field (holocene)" show that there existed a convergent-divergent tidal zone just outside the palaeo-Yangtze River estuary where a palaeo-underwater accumulation was developed. The calculated results from wave models indicate that the wave impact on the topography, under the condition of high water level and strong winds, is significant. The storm current induced by typhoons landing in the Yangtze River estuary

  10. Self-organization and nanostructure formation in chemical vapor deposition

    Science.gov (United States)

    Walgraef, Daniel

    2013-10-01

    When thin films are grown on a substrate by chemical vapor deposition, the evolution of the first deposited layers may be described, on mesoscopic scales, by dynamical models of the reaction-diffusion type. For monatomic layers, such models describe the evolution of atomic coverage due to the combined effect of reaction terms representing adsorption-desorption and chemical processes and nonlinear diffusion terms that are of the Cahn-Hilliard type. This combination may lead, below a critical temperature, to the instability of uniform deposited layers. This instability triggers the formation of nanostructures corresponding to regular spatial variations of substrate coverage. Patterns wavelengths and symmetries are selected by dynamical variables and not by variational arguments. According to the balance between reaction- and diffusion-induced nonlinearities, a succession of nanostructures including hexagonal arrays of dots, stripes, and localized structures of various types may be obtained. These structures may initiate different growth mechanisms, including Volmer-Weber and Frank-Van der Merwe types of growth. The relevance of this approach to the study of deposited layers of different species is discussed.

  11. Inkjet printing of aqueous rivulets: Formation, deposition, and applications

    Science.gov (United States)

    Bromberg, Vadim

    early-time dynamics during rivulet formation in determining the nature of subsequent particle convection and deposition. New flow and deposition phenomena have also been identified and leveraged to develop novel processes for deposition of micron-scale electrically conducting lines of silver nanoparticles. Low-temperature processing of printed silver nitrate lines with environmentally benign Ar plasma to improve electrical properties has also been investigated and will be discussed.

  12. Sediment dynamics and palaeo-environmental context at key stages in the Challenger cold-water coral mound formation: Clues from sediment deposits at the mound base

    Science.gov (United States)

    Huvenne, Veerle Ann Ida; Van Rooij, David; De Mol, Ben; Thierens, Mieke; O'Donnell, Rory; Foubert, Anneleen

    2009-12-01

    IODP Expedition 307, targeting the 160 m high Challenger Mound and its surroundings in the Porcupine Seabight, NE Atlantic, was the first occasion of scientific drilling of a cold-water coral carbonate mound. Such mound structures are found at several locations along the continental margin but are especially numerous off Ireland. All rooted on a common unconformity (RD1) and embedded in drift sediments, the mounds in the Porcupine Seabight remain enigmatic structures, and their initial trigger and formation mechanisms are still not entirely clear. This paper discusses the sedimentary environment during the initial stages of Challenger Mound, and at the start-up of the embedding sediment drift. The results are interpreted within the regional palaeo-environmental context. Based on detailed grain-size analyses and planktonic foraminifera assemblage counts, a 14-m interval overlying the regional base-of-mound unconformity RD1 is characterised at IODP Sites U1317 (on mound), U1316 (off mound), and U1318 (background site). Several sedimentary facies are identified and interpreted in relation to regional current dynamics. Using the foraminifera counts, existing age models for the initial stages of on-mound and off-mound sedimentation are refined. Sedimentation within the initial mound was characterised by a two-mode system, with the observed cyclicities related to glacial/interglacial stages. However, the contrast in environmental conditions between the stages was less extreme than observed in the most recent glacial/interglacial cycles, allowing continuous cold-water coral growth. This sustained presence of coral framework was the key factor for fast mound build-up, baffling sediments at periods of slack currents, and protecting them from renewed erosion during high-current events. The off-mound and background sedimentation consisted mainly of a succession of contourite beds, ranging from sandy contourites in the initial stages to muddy contourites higher up in the

  13. Dynamic Deposition of Nanocopper Film on the β-SiCp Surface by Magnetron Sputtering

    Directory of Open Access Journals (Sweden)

    Hu Ming

    2015-01-01

    Full Text Available The uniform nanocopper film was deposited on the surface of micron β-SiC particle by magnetron sputtering technology successfully. The surface morphology and phase constitution of the β-SiC particle with nanocopper film were analyzed and dynamic deposition behavior was investigated in detail. The concept of dynamic deposition was put forward to interpret formation mechanism of copper nanofilm on the surface of β-SiC particles.

  14. The dynamics of latifundia formation.

    Science.gov (United States)

    Chaves, Luis Fernando

    2013-01-01

    Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia.

  15. The dynamics of latifundia formation.

    Directory of Open Access Journals (Sweden)

    Luis Fernando Chaves

    Full Text Available Land tenure inequity is a major social problem in developing nations worldwide. In societies, where land is a commodity, inequities in land tenure are associated with gaps in income distribution, poverty and biodiversity loss. A common pattern of land tenure inequities through the history of civilization has been the formation of latifundia [Zhuāngyuán in chinese], i.e., a pattern where land ownership is concentrated by a small fraction of the whole population. Here, we use simple Markov chain models to study the dynamics of latifundia formation in a heterogeneous landscape where land can transition between forest, agriculture and recovering land. We systematically study the likelihood of latifundia formation under the assumption of pre-capitalist trade, where trade is based on the average utility of land parcels belonging to each individual landowner during a discrete time step. By restricting land trade to that under recovery, we found the likelihood of latifundia formation to increase with the size of the system, i.e., the amount of land and individuals in the society. We found that an increase of the transition rate for land use changes, i.e., how quickly land use changes, promotes more equitable patterns of land ownership. Disease introduction in the system, which reduced land profitability for infected individual landowners, promoted the formation of latifundia, with an increased likelihood for latifundia formation when there were heterogeneities in the susceptibility to infection. Finally, our model suggests that land ownership reforms need to guarantee an equitative distribution of land among individuals in a society to avoid the formation of latifundia.

  16. Deposit formation in hydrocarbon rocket fuels: Executive summary

    Science.gov (United States)

    Roback, R.; Szetela, E. J.; Spadaccini, L. J.

    1981-01-01

    An experimental program was conducted to study deposit formation in hydrocarbon fuels under flow conditions that exist in high-pressure, rocket engine cooling systems. A high pressure fuel coking test apparatus was designed and developed and was used to evaluate thermal decomposition (coking) limits and carbon deposition rates in heated copper tubes for two hydrocarbon rocket fuels, RP-1 and commercial-grade propane. Tests were also conducted using JP-7 and chemically-pure propane as being representative of more refined cuts of the baseline fuels. A parametric evaluation of fuel thermal stability was performed at pressures of 136 atm to 340 atm, bulk fuel velocities in the range 6 to 30 m/sec, and tube wall temperatures in the range 422 to 811K. In addition, the effect of the inside wall material on deposit formation was evaluated in selected tests which were conducted using nickel-plated tubes. The results of the tests indicated that substantial deposit formation occurs with RP-1 fuel at wall temperatures between 600 and 800K, with peak deposit formation occurring near 700K. No improvements were obtained when de-oxygenated JP-7 fuel was substituted for RP-1. The carbon deposition rates for the propane fuels were generally higher than those obtained for either of the kerosene fuels at any given wall temperature. There appeared to be little difference between commercial-grade and chemically-pure propane with regard to type and quantity of deposit. The results of tests conducted with RP-1 indicated that the rate of deposit formation increased slightly with pressure over the range 136 atm to 340 atm. Finally, plating the inside wall of the tubes with nickel was found to significantly reduce carbon deposition rates for RP-1 fuel.

  17. The characteristics of coignimbrite deposits and inferences for their formation

    Science.gov (United States)

    Engwell, S. L.; Eychenne, J.; Wulf, S.; De'Michieli Vitturi, M.

    2014-12-01

    Coignimbrite deposits form as fine-grained ash (traffic. To date, few coignimbrite deposits have been studied in detail, mainly due to their poor preservation potential, and difficulty distinguishing these deposits from Plinian deposits. As such, there is little in the published record regarding the physical characteristics of coignimbrite deposits. Deposits from Lago Grande di Monticchio, a maar lake 120 km east of the Campanian Volcanic Zone, Italy were analysed for this study. These lake sediments contain more than 340 distinct tephra layers, of which more than 300 are thought to have originated from the Campanian region. The physical characteristics of deposits from eruptions from within the past 50 kyrs are studied with particular emphasis placed on those with a known pyroclastic density current phase. Results show that in most cases, stratigraphy is comparable to proximal stratigraphy, and in the case of the Campanian Ignimbrite (Phlegrean Fields, 39.3 ka) and Monte Epomeo Green Tuff (Ischia, 55 ka) particularly, the coignimbrite contribution is easily identified. These coignimbrite deposits are composed of glass shards, with very small lithic and expanded pumice contents. Grainsize data from these coignimbrite events show remarkably similar characteristics, typically described by a very fine-grained mode (~50 microns), and poor sorting. This fine grain size implicates aggregation as the dominant process by which this ash is deposited. Similar trends are identified in the literature, for different types and scales of eruptions indicating the grainsize of these deposits is controlled by current dynamics rather than primary eruptive conditions at the vent. The results highlight the importance of lacustrine environments for deciphering eruption dynamics, specifically those from coignimbrite forming events. In addition, the distinct difference in grainsize trends between Plinian and coignimbrite events highlights the need to model coignimbrite events and ash

  18. Formation of metal oxides by cathodic arc deposition

    Energy Technology Data Exchange (ETDEWEB)

    Anders, S.; Anders, A.; Rubin, M.; Wang, Z.; Raoux, S.; Kong, F.; Brown, I.G.

    1995-03-01

    Metal oxide thin films are of interest for a number of applications. Cathodic arc deposition, an established, industrially applied technique for formation of nitrides (e.g. TiN), can also be used for metal oxide thin film formation. A cathodic arc plasma source with desired cathode material is operated in an oxygen atmosphere, and metal oxides of various stoichiometric composition can be formed on different substrates. We report here on a series of experiments on metal oxide formation by cathodic arc deposition for different applications. Black copper oxide has been deposited on ALS components to increase the radiative heat transfer between the parts. Various metal oxides such as tungsten oxide, niobium oxide, nickel oxide and vanadium oxide have been deposited on ITO glass to form electrochromic films for window applications. Tantalum oxide films are of interest for replacing polymer electrolytes. Optical waveguide structures can be formed by refractive index variation using oxide multilayers. We have synthesized multilayers of Al{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/AI{sub 2}O{sub 3}/Si as possible basic structures for passive optoelectronic integrated circuits, and Al{sub 2-x}Er{sub x}O{sub 3} thin films with a variable Er concentration which is a potential component layer for the production of active optoelectronic integrated devices such as amplifiers or lasers at a wavelength of 1.53 {mu}m. Aluminum and chromium oxide films have been deposited on a number of substrates to impart improved corrosion resistance at high temperature. Titanium sub-oxides which are electrically conductive and corrosion resistant and stable in a number of aggressive environments have been deposited on various substrates. These sub-oxides are of great interest for use in electrochemical cells.

  19. Study of nozzle deposit formation mechanism for direct injection gasoline engines; Chokufun gasoline engine yo nozzle no deposit seisei kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, M.; Saito, A. [Toyota Central Research and Development Labs., Inc., Aichi (Japan); Matsushita, S. [Toyota Motor Corp., Aichi (Japan); Shibata, H. [Nippon Soken, Inc., Tokyo (Japan); Niwa, Y. [Denso Corp., Aichi (Japan)

    1997-10-01

    Nozzles in fuel injectors for direct injection gasoline engines are exposed to high temperature combustion gases and soot. In such a rigorous environment, it is a fear that fuel flow rate changes in injectors by deposit formation on nozzles. Fundamental factors of nozzle deposit formation were investigated through injector bench tests and engine dynamometer tests. Deposit formation processes were observed by SEM through engine dynamometer tests. The investigation results reveal nozzle deposit formation mechanism and how to suppress the deposit. 4 refs., 8 figs., 3 tabs.

  20. Appropriate deposition parameters for formation of fcc Co-Ni alloy nanowires during electrochemical deposition process

    Science.gov (United States)

    Mukhtar, Aiman; Shahzad Khan, Babar; Mehmood, Tahir

    2016-12-01

    The effect of deposition potential on the crystal structure and composition of Co-Ni alloy nanowires is studied by XRD, FE-SEM and EDX. The alloy nanowires deposited at -3.2 V are metastable fcc phase Co-Ni. The alloy nanowires deposited at -1.8 V are hcp phase Co-Ni. The formation of the metastable fcc alloy nanowires can be attributed to smaller critical clusters formed at the high potential as the smaller critical clusters favor fcc structure because of the significant surface energy effect. The content of Co inside nanowires increases with increasing potential. This can be understood by the polarization curves of depositing Co and Ni nanowires, which show that the current density ratio of Ni to Co at low potential has larger value than that at high potential.

  1. Deposits of the Peruvian Pisco Formation compared to layered deposits on Mars

    Science.gov (United States)

    Sowe, M.; Bishop, J. L.; Gross, C.; Walter, S.

    2013-09-01

    Deposits of the Peruvian Pisco Formation are morphologically similar to the mounds of Juventae Chasma at the equatorial region on Mars (Fig. 1). By analyzing these deposits, we hope to gain information about the environmental conditions that prevailed during sediment deposition and erosion, hence conditions that might be applicable to the Martian layered and hydrated deposits. Mariner 9 data of the Martian mid-latitudes have already shown evidence of the wind-sculptured landforms that display the powerful prevailing eolian regime [1]. In addition, [2] reported on similarities between Martian erosional landforms and those of the rainless coastal desert of central Peru from the Paracas peninsula to the Rio Ica. As indicated by similar erosional patterns, hyper-arid conditions and unidirectional winds must have dominated at least after deposition of the sediments, which are intermixed volcaniclastic materials and evaporate minerals at both locations. Likewise, variations in composition are displayed by alternating layers of different competence. The Pisco formation bears yardangs on siltstones, sandstones and clays with volcaniclastic admixtures [3] whereas the presence of sulphate minerals and the omnipresent mafic mineralogy has been reported for the layered mounds of Juventae Chasma equally [4]. Likewise, a volcanic airfall deposition and lacustrine formation have been proposed for the sulphate-rich deposits of Juventae Chasma [5,6]. In order to find out about potential spectral similarities, we performed a detailed spectral analysis of the surface by using LANDSAT and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) VNIR/ SWIR data (visible to near-infrared and shortwave infrared region).

  2. Fibroblast-like synoviocytes induce calcium mineral formation and deposition.

    Science.gov (United States)

    Sun, Yubo; Mauerhan, David R; Franklin, Atiya M; Zinchenko, Natalia; Norton, Harry James; Hanley, Edward N; Gruber, Helen E

    2014-01-01

    Calcium crystals are present in the synovial fluid of 65%-100% patients with osteoarthritis (OA) and 20%-39% patients with rheumatoid arthritis (RA). This study sought to investigate the role of fibroblast-like synoviocytes (FLSs) in calcium mineral formation. We found that numerous genes classified in the biomineral formation process, including bone gamma-carboxyglutamate (gla) protein/osteocalcin, runt-related transcription factor 2, ankylosis progressive homolog, and parathyroid hormone-like hormone, were differentially expressed in the OA and RA FLSs. Calcium deposits were detected in FLSs cultured in regular medium in the presence of ATP and FLSs cultured in chondrogenesis medium in the absence of ATP. More calcium minerals were deposited in the cultures of OA FLSs than in the cultures of RA FLSs. Examination of the micromass stained with nonaqueous alcoholic eosin indicated the presence of birefringent crystals. Phosphocitrate inhibited the OA FLSs-mediated calcium mineral deposition. These findings together suggest that OA FLSs are not passive bystanders but are active players in the pathological calcification process occurring in OA and that potential calcification stimuli for OA FLSs-mediated calcium deposition include ATP and certain unidentified differentiation-inducing factor(s). The OA FLSs-mediated pathological calcification process is a valid target for the development of disease-modifying drug for OA therapy.

  3. Fibroblast-Like Synoviocytes Induce Calcium Mineral Formation and Deposition

    Directory of Open Access Journals (Sweden)

    Yubo Sun

    2014-01-01

    Full Text Available Calcium crystals are present in the synovial fluid of 65%–100% patients with osteoarthritis (OA and 20%–39% patients with rheumatoid arthritis (RA. This study sought to investigate the role of fibroblast-like synoviocytes (FLSs in calcium mineral formation. We found that numerous genes classified in the biomineral formation process, including bone gamma-carboxyglutamate (gla protein/osteocalcin, runt-related transcription factor 2, ankylosis progressive homolog, and parathyroid hormone-like hormone, were differentially expressed in the OA and RA FLSs. Calcium deposits were detected in FLSs cultured in regular medium in the presence of ATP and FLSs cultured in chondrogenesis medium in the absence of ATP. More calcium minerals were deposited in the cultures of OA FLSs than in the cultures of RA FLSs. Examination of the micromass stained with nonaqueous alcoholic eosin indicated the presence of birefringent crystals. Phosphocitrate inhibited the OA FLSs-mediated calcium mineral deposition. These findings together suggest that OA FLSs are not passive bystanders but are active players in the pathological calcification process occurring in OA and that potential calcification stimuli for OA FLSs-mediated calcium deposition include ATP and certain unidentified differentiation-inducing factor(s. The OA FLSs-mediated pathological calcification process is a valid target for the development of disease-modifying drug for OA therapy.

  4. Deposit formation and heat transfer in hydrocarbon rocket fuels

    Science.gov (United States)

    Giovanetti, A. J.; Spadaccini, L. J.; Szetela, E. J.

    1983-01-01

    An experimental research program was undertaken to investigate the thermal stability and heat transfer characteristics of several hydrocarbon fuels under conditions that simulate high-pressure, rocket engine cooling systems. The rates of carbon deposition in heated copper and nickel-plated copper tubes were determined for RP-1, propane, and natural gas using a continuous flow test apparatus which permitted independent variation and evaluation of the effect on deposit formation of wall temperature, fuel pressure, and fuel velocity. In addition, the effects of fuel additives and contaminants, cryogenic fuel temperatures, and extended duration testing with intermittent operation were examined. Parametric tests to map the thermal stability characteristics of RP-1, commercial-grade propane, and natural gas were conducted at pressures of 6.9 to 13.8 MPa, bulk fuel velocities of 30 to 90 m/s, and tube wall temperatures in the range of 230 to 810 K. Also, tests were run in which propane and natural gas fuels were chilled to 230 and 160 K, respectively. Corrosion of the copper tube surface was detected for all fuels tested. Plating the inside of the copper tubes with nickel reduced deposit formation and eliminated tube corrosion in most cases. The lowest rates of carbon deposition were obtained for natural gas, and the highest rates were obtained for propane. For all fuels tested, the forced-convection heat transfer film coefficients were satisfactorily correlated using a Nusselt-Reynolds-Prandtl number equation.

  5. Formation of carbon deposits from coal in an arc plasma

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.; Tian, Y.; Zhang, Y.; Zhu, S.; Lu, Y.; Zhang, Y.; Xie, K. [Taiyuan University of Technology, Taiyuan (China)

    2007-07-01

    The issue of deposited carbon (DC) on a reactor wall during the production of acetylene by the coal/arc plasma process is a potential obstacle for the industrialization process. The formation mechanism of DC is very difficult to reveal because the high complexity of coal and the volatile matter. Combining with quenching technique, the methane, liquid petroleum gas and benzene were employed as the model materials to roughly act as the light gas, chain and aromatic subcomponents of volatile matter, and then the reasonable formation mechanism of DC was subtly speculated accordingly.

  6. Multilayer Coating Formation at the Deposition from Plasma

    OpenAIRE

    Shanin, Sergei Aleksandrovich; Knyazeva, Anna Georgievna

    2016-01-01

    The numerical experiment was carried out for the process of the coating composition formation during deposition from plasma. The chemical reactions between elements are taken into account. The nonuniform composition of the coating is determined by various transfer processes, including diffusion under stress action. To find the stress field the equilibrium problem was solved numerically because all physical and mechanical properties depend on composition. Stress field has been also obtained no...

  7. Quantifying fat, oil, and grease deposit formation kinetics.

    Science.gov (United States)

    Iasmin, Mahbuba; Dean, Lisa O; Ducoste, Joel J

    2016-01-01

    Fat, oil, and grease (FOG) deposits formed in sanitary sewers are calcium-based saponified solids that are responsible for a significant number of nationwide sanitary sewer overflows (SSOs) across United States. In the current study, the kinetics of lab-based saponified solids were determined to understand the kinetics of FOG deposit formation in sewers for two types of fat (Canola and Beef Tallow) and two types of calcium sources (calcium chloride and calcium sulfate) under three pH (7 ± 0.5, 10 ± 0.5, and ≈14) and two temperature conditions (22 ± 0.5 and 45 ± 0.5 °C). The results of this study displayed quick reactions of a fraction of fats with calcium ions to form calcium based saponified solids. Results further showed that increased palmitic fatty acid content in source fats, the magnitude of the pH, and temperature significantly affect the FOG deposit formation and saponification rates. The experimental data of the kinetics were compared with two empirical models: a) Cotte saponification model and b) Foubert crystallization model and a mass-action based mechanistic model that included alkali driven hydrolysis of triglycerides. Results showed that the mass action based mechanistic model was able to predict changes in the rate of formation of saponified solids under the different experimental conditions compared to both empirical models. The mass-action based saponification model also revealed that the hydrolysis of Beef Tallow was slower compared to liquid Canola fat resulting in smaller quantities of saponified solids. This mechanistic saponification model, with its ability to track the saponified solids chemical precursors, may provide an initial framework to predict the spatial formation of FOG deposits in municipal sewers using system wide sewer collection modeling software.

  8. Extrasolar planets formation, detection and dynamics

    CERN Document Server

    Dvorak, Rudolf

    2008-01-01

    This latest, up-to-date resource for research on extrasolar planets covers formation, dynamics, atmospheres and detection. After a look at the formation of giant planets, the book goes on to discuss the formation and dynamics of planets in resonances, planets in double stars, atmospheres and habitable zones, detection via spectra and transits, and the history and prospects of ESPs as well as satellite projects.Edited by a renowned expert in solar system dynamics with chapters written by the leading experts in the method described -- from the US and Europe -- this is an ideal textbook for g

  9. Fat, oil and grease deposits in sewers: characterisation of deposits and formation mechanisms.

    Science.gov (United States)

    Williams, J B; Clarkson, C; Mant, C; Drinkwater, A; May, E

    2012-12-01

    Fat, oil and grease deposits (FOG) in sewers are a major problem and can cause sewer overflows, resulting in environmental damage and health risks. Often simplistically portrayed as cooling of fats, recent research has suggested that saponification may be involved in FOG formation. However there are still questions about the mechanisms effecting transformations in sewers and the role and source of metal cations involved in saponification. This study characterises FOG deposits from pumping stations, sewers and sewage works from different water hardness zones across the UK. The sites all had previous problems with FOG and most catchments contained catering and food preparation establishments. The FOG deposits were highly variable with moisture content ranging from 15 to 95% and oil content from 0 to 548 mg/g. Generally the pumping stations had lower moisture content and higher fat content, followed by the sewers then the sewage works. The water in contact with the FOG had high levels of oil (mean of about 800 mg/L) and this may indicate poor kitchen FOG management practices. FOG fatty acid profiles showed a transformation from unsaturated to saturated forms compared to typical cooking oils. This seems to relate to ageing in the sewer network or the mechanism of formation, as samples from pumping stations had higher proportions of C18:1 compared to C16. This may be due to microbial transformations by bacteria such as Clostridium sp. in a similar process to adipocere formation. There was an association between water hardness and increased Ca levels in FOG along with harder deposits and higher melting points. A link between FOG properties and water hardness has not been previously reported for field samples. This may also be due to microbial processes, such as biocalcification. By developing the understanding of these mechanisms it may be possible to more effectively control FOG deposits, especially when combined with promotion of behavioural change.

  10. Influence of deposit architecture on intrastratal deformation, slope deposits of the Tres Pasos Formation, Chile

    Science.gov (United States)

    Auchter, Neal C.; Romans, Brian W.; Hubbard, Stephen M.

    2016-07-01

    Slope sediments on passive and active margins deform and fail across a broad range of scales ranging from loading and sediment remobilization near the sediment-water interface to submarine landslides and mass movements that incorporate significant volumes of slope deposits. Deformational styles are characterized by updip extension and downdip compressional features that occur above a detachment surface. Conditions for failure and deformation include the presence of weak layer(s) that serve as a detachment surface, competency contrasts that allow for detachment and downslope movement, deformation above a detachment surface, and a triggering mechanism(s) that initiates failure. Slope failure processes and products are well documented at scales resolvable by seismic-reflection surveys and in instances of extensive downslope failure, but the processes and products associated with intermediate-scale slope deformation are poorly understood. Intrastratal deformation is defined as stratigraphically isolated zones of deformation bounded above and below by concordant and undeformed strata. In this study, outcrop examples of intrastratal deformation from the Upper Cretaceous Tres Pasos Formation are used to elucidate the influence of depositional architecture on slope deformation. The facies distribution associated with compensational stacking of lobe deposits is shown to have a first-order control on the location and style of deformation. Detachment planes that form in mudstone deposits associated with lobe fringe and interlobe deposits are spatially limited and deformation is restricted to interbedded sandstone and mudstone associated with off-axial lobe positions. Downslope translation was arrested by stratigraphic buttresses associated with more sandstone-prone axial deposits. Emplacement of a regionally extensive mass transport deposit is interpreted as the triggering mechanism for contemporaneous intrastratal deformation of > 60 m of underlying stratigraphy. A vertical

  11. Dynamic formation control for autonomous underwater vehicles

    Institute of Scientific and Technical Information of China (English)

    燕雪峰; 古锋; 宋琛; 胡晓琳; 潘毅

    2014-01-01

    Path planning and formation structure forming are two of the most important problems for autonomous underwater vehicles (AUVs) to collaborate with each other. In this work, a dynamic formation model was proposed, in which several algorithms were developed for the complex underwater environment. Dimension changeable particle swarm algorithm was used to find an optimized path by dynamically adjusting the number and the distribution of the path nodes. Position relationship based obstacle avoidance algorithm was designed to detour along the edges of obstacles. Virtual potential point based formation-keeping algorithm was employed by incorporating dynamic strategies which were decided by the current states of the formation. The virtual potential point was used to keep the formation structure when the AUV or the formation was deviated. Simulation results show that an optimal path can be dynamically planned with fewer path nodes and smaller fitness, even with a concave obstacle. It has been also proven that different formation-keeping strategies can be adaptively selected and the formation can change its structure in a narrow area and restore back after passing the obstacle.

  12. Nanoparticle formation and thin film deposition in aniline containing plasmas

    Science.gov (United States)

    Pattyn, Cedric; Dias, Ana; Hussain, Shahzad; Strunskus, Thomas; Stefanovic, Ilija; Boulmer-Leborgne, Chantal; Lecas, Thomas; Kovacevic, Eva; Berndt, Johannes

    2016-09-01

    This contribution deals with plasma based polymerization processes in mixtures of argon and aniline. The investigations are performed in a capacitively coupled RF discharge (in pulsed and continuous mode) and concern both the observed formation of nanoparticles in the plasma volume and the deposition of films. The latter process was used for the deposition of ultra-thin layers on different kind of nanocarbon materials (nanotubes and free standing graphene). The analysis of the plasma and the plasma chemistry (by means of mass spectroscopy and in-situ FTIR spectroscopy) is accompanied by several ex-situ diagnostics of the obtained materials which include NEXAFS and XPS measurements as well as Raman spectroscopy and electron microscopy. The decisive point of the investigations concern the preservation of the original monomer structure during the plasma polymerization processes and the stability of the thin films on the different substrates.

  13. Study of nickel silicide formation by physical vapor deposition techniques

    Science.gov (United States)

    Pancharatnam, Shanti

    Metal silicides are used as contacts to the highly n-doped emitter in photovoltaic devices. Thin films of nickel silicide (NiSi) are of particular interest for Si-based solar cells, as they form at lower temperature and consume less silicon. However, interfacial oxide limits the reduction in sheet resistance. Hence, different diffusion barriers were investigated with regard to optimizing the conductivity and thermal stability. The formation of NiSi, and if it can be doped to have good contact with the n-side of a p-n junction were studied. Reduction of the interfacial oxide by the interfacial Ti layer to allow the formation of NiSi was observed. Silicon was treated in dilute hydrofluoric acid for removing the surface oxide layer. Ni and a Ti diffusion barrier were deposited on Si by physical vapor deposition (PVD) methods - electron beam evaporation and sputtering. The annealing temperature and time were varied to observe the stability of the deposited film. The films were then etched to observe the retention of the silicide. Characterization was done using scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and Rutherford back scattering (RBS). Sheet resistance was measured using the four-point probe technique. Annealing temperatures from 300°C showed films began to agglomerate indicating some diffusion between Ni and Si in the Ti layer, also supported by the compositional analysis in the Auger spectra. Films obtained by evaporation and sputtering were of high quality in terms of coverage over substrate area and uniformity. Thicknesses of Ni and Ti were optimized to 20 nm and 10 nm respectively. Resistivity was low at these thicknesses, and reduced by about half post annealing at 300°C for 8 hours. Thus a low resistivity contact was obtained at optimized thicknesses of the metal layers. It was also shown that some silicide formation occurs at temperatures starting from 300°C and can thus be used to make good silicide contacts.

  14. Diagenesis, provenance and depositional environments of the Bunter Sandstone Formation

    DEFF Research Database (Denmark)

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    The Bunter Sandstone Formation in the northern North German Basin has large geothermal potential with high porosity and permeability (generally >15% and >100 mD, respectively) and with pore fluid temperatures that are adequate for geothermal energy production (c. 55–60˚C). A combined investigation...... of diagenesis, provenance and depositional environments is used to identify the reservoir rocks that possess the best quality. This is accomplished by integrating various methods including: seismic reflection data, sedimentological description of cores, mineral quantification by point counting, measurement...

  15. Formation of Cu/Pd bimetallic crystals by electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, A.E. [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Departamento de Ingenieria Quimica, Universidad Nacional del Sur, Avda. Alem 1253, 8000 Bahia Blanca (Argentina); Salinas, D.R., E-mail: dsalinas@uns.edu.a [Instituto de Ingenieria Electroquimica y Corrosion (INIEC), Departamento de Ingenieria Quimica, Universidad Nacional del Sur, Avda. Alem 1253, 8000 Bahia Blanca (Argentina)

    2010-04-15

    The early stages of the palladium electrodeposition process onto a vitreous carbon (VC) substrate as well as the deposition of Cu on such Pd/VC modified surface were investigated using classical electrochemical techniques, atomic force microscopy (AFM) and scanning electron microscopy (SEM). Within the potential range considered the kinetics of the Pd electrodeposition from a PdCl{sub 2} acid solution can be described by a model involving progressive nucleation on active sites and diffusion-controlled 3D growth. The nucleation rate constant, A{sub 0}, and the number of active sites of the substrate, N{sub 0}, were determined from the analysis of potentiostatic current transients on the basis of an existing theoretical model. The AFM images corroborated the progressive nucleation mechanism showing irregular palladium crystals randomly distributed over the VC surface, with different sizes and 3D morphological characteristics. The electrodeposition of Cu was carried out onto the characterized Pd/VC modified surface from a Cu{sup 2+} containing solution using a well defined polarization routine. The SEM/EDX images confirmed the formation of Cu/Pd bimetallic crystals uniformly distributed on the VC surface and the in situ AFM images obtained during this process corroborated that Cu formed a core-shell structure with the Pd crystals. Nevertheless, the subsequent anodic stripping produced only a partial dissolution of the Cu deposits, and therefore, the formation of a Cu/Pd alloy could be inferred.

  16. Ash formation, deposition, corrosion, and erosion in conventional boilers

    Energy Technology Data Exchange (ETDEWEB)

    Benson, S.A.; Jones, M.L. [Univ. of North Dakota, Grand Forks, ND (United States)

    1995-12-01

    The inorganic components (ash-forming species) associated with coals significantly affect boiler design, efficiency of operation, and lifetimes of boiler parts. During combustion in conventional pulverized fuel boilers, the inorganic components are transformed into inorganic gases, liquids, and solids. This partitioning depends upon the association of the inorganic components in the coal and combustion conditions. The inorganic components are associated as mineral grains and as organically associated elements, and these associations of inorganic components in the fuel directly influence their fate upon combustion. Combustion conditions, such as temperature and atmosphere, influence the volatility and the interaction of inorganic components during combustion and gas cooling, which influences the state and size composition distribution of the particulate and condensed ash species. The intermediate species are transported with the bulk gas flow through the combustion systems, during which time the gases and entrained ash are cooled. Deposition, corrosion, and erosion occur when the ash intermediate species are transported to the heat-transfer surface, react with the surface, accumulate, sinter, and develop strength. Research over the past decade has significantly advanced understanding of ash formation, deposition, corrosion, and erosion mechanisms. Many of the advances in understanding and predicting ash-related issues can be attributed to advanced analytical methods to determine the inorganic composition of fuels and the resulting ash materials. These new analytical techniques have been the key to elucidation of the mechanisms of ash formation and deposition. This information has been used to develop algorithms and computer models to predict the effects of ash on combustion system performance.

  17. Aerosol dynamics within and above forest in relation to turbulent transport and dry deposition

    DEFF Research Database (Denmark)

    Rannik, Üllar; Zhou, Luxi; Zhou, Putian;

    2016-01-01

    of 10 days in May 2013 to a pine forest site in southern Finland. The period was characterized by frequent new particle formation events and simultaneous intensive aerosol transformation. The aim of the study was to analyze and quantify the role of aerosol and ABL dynamics in the vertical transport...... of aerosols. It was of particular interest to what extent the fluxes above the canopy deviate from the particle dry deposition on the canopy foliage due to the above-mentioned processes. The model simulations revealed that the particle concentration change due to aerosol dynamics frequently exceeded...... the effect of particle deposition by even an order of magnitude or more. The impact was, however, strongly dependent on particle size and time. In spite of the fact that the timescale of turbulent transfer inside the canopy is much smaller than the timescales of aerosol dynamics and dry deposition, leading...

  18. Dynamics of sheet nacre formation in bivalves.

    Science.gov (United States)

    Rousseau, Marthe; Meibom, Anders; Gèze, Marc; Bourrat, Xavier; Angellier, Martine; Lopez, Evelyne

    2009-03-01

    Formation of nacre (mother-of-pearl) is a biomineralization process of fundamental scientific as well as industrial importance. However, the dynamics of the formation process is still not understood. Here, we use scanning electron microscopy and high spatial resolution ion microprobe depth-profiling to image the full three-dimensional distribution of organic materials around individual tablets in the top-most layer of forming nacre in bivalves. Nacre formation proceeds by lateral, symmetric growth of individual tablets mediated by a growth-ring rich in organics, in which aragonite crystallizes from amorphous precursors. The pivotal role in nacre formation played by the growth-ring structure documented in this study adds further complexity to a highly dynamical biomineralization process.

  19. Dynamic Scaling of Lipofuscin Deposition in Aging Cells

    Science.gov (United States)

    Family, Fereydoon; Mazzitello, K. I.; Arizmendi, C. M.; Grossniklaus, H. E.

    2011-07-01

    Lipofuscin is a membrane-bound cellular waste that can be neither degraded nor ejected from the cell but can only be diluted through cell division and subsequent growth. The fate of postmitotic (non-dividing) cells such as neurons, cardiac myocytes, skeletal muscle fibers, and retinal pigment epithelial cells (RPE) is to accumulate lipofuscin, which as an "aging pigment" has been considered a reliable biomarker for the age of cells. Environmental stress can accelerate the accumulation of lipofuscin. For example, accumulation in brain cells appears to be an important issue connected with heavy consumption of alcohol. Lipofuscin is made of free-radical-damaged protein and fat, whose abnormal accumulation is related to a range of disorders including Type IV mucolipidosis (ML4), Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease, Parkinson disease, and age-related macular degeneration (AMD) which is the leading cause of blindness beyond the age of 50 years. The study of lipofuscin formation and growth is important, because of their association with cellular aging. We introduce a model of non-equilibrium cluster growth and aggregation that we have developed for studying the formation and growth of lipofuscin. As an example of lipofuscin deposit in a given kind of postmitotic cell, we study the kinetics of lipofuscin growth in a RPE cell. Our results agree with a linear growth of the number of lipofuscin granules with age. We apply the dynamic scaling approach to our model and find excellent data collapse for the cluster size distribution. An unusual feature of our model is that while small particles are removed from the cell the larger ones become fixed and grow by aggregation.

  20. Dynamical heterogeneity in a vapor-deposited polymer glass

    Science.gov (United States)

    Zhang, Wengang; Douglas, Jack F.; Starr, Francis W.

    2017-05-01

    Recently, there has been great interest in "ultrastable" glasses formed via vapor deposition, both because of emerging engineering applications of these materials (e.g., active layers in light-emitting diodes and photovoltaics) and, theoretically, as materials for probing the equilibrium properties of glassy materials below their glass transition, based on the conjecture that these materials are equivalent to glassy materials aged over astronomical time scales. We use molecular dynamics simulations to examine the properties of ultrastable vapor-deposited and ordinary polymer glasses. Based on the difference in the energy of the deposited and ordinary films, we estimate the effective cooling rate for the vapor deposited films to be 1 to 3 orders of magnitude larger than that of the ordinary film, depending on the deposition temperature. Similarly, we find an increase in the average segmental relaxation time of the vapor-deposited film compared to the ordinary glass. On the other hand, the normal mode spectrum is essentially identical for the vapor-deposited and the ordinary glass film, suggesting that the high-frequency dynamics should be similar. In short, the segmental relaxation dynamics of the polymer vapor-deposited glass are consistent with those of an ordinary polymer glass with a somewhat slower effective cooling rate. Of course, one would expect a larger effect on dynamics approaching the experimental glass transition, where the cooling rates are much slower than accessible in simulation. To more precisely probe the relationship between the dynamics of these glasses, we examine dynamical heterogeneity within the film. Due to the substantial mobility gradient in the glassy films, we find that it is crucial to distinguish the dynamics of the middle part of the film from those of the entire film. Considering the film as a whole, the average dynamical heterogeneity is dominated by the mobility gradient, and as a consequence the heterogeneity is nearly

  1. Advanced optical modelling of dynamically deposited silicon nitride layers

    Science.gov (United States)

    Borojevic, N.; Hameiri, Z.; Winderbaum, S.

    2016-07-01

    Dynamic deposition of silicon nitrides using in-line plasma enhanced chemical vapor deposition systems results in non-uniform structure of the dielectric layer. Appropriate analysis of such layers requires the optical characterization to be performed as a function of the layer's depth. This work presents a method to characterize dynamically deposited silicon nitride layers. The method is based on the fitting of experimental spectroscopic ellipsometry data via grading of Tauc-Lorentz optical parameters through the depth of the layer. When compared with the standard Tauc-Lorentz fitting procedure, used in previous studies, the improved method is demonstrating better quality fits to the experimental data and revealing more accurate optical properties of the dielectric layers. The most significant advantage of the method is the ability to extract the depth profile of the optical properties along the direction of the layer normal. This is enabling a better understanding of layers deposited using dynamic plasma enhanced chemical vapor deposition systems frequently used in the photovoltaic industry.

  2. A review: Fly ash and deposit formation in PF fired biomass boilers

    DEFF Research Database (Denmark)

    Jensen, Peter Arendt; Jappe Frandsen, Flemming; Wu, Hao

    2016-01-01

    to the commercialization of the suspension biomass firing technology a range of research studies have improved our understanding of the formation of fly ash and the impact on deposit formation and corrosion in such boilers. In this paper a review of the present knowledge with respect to ash and deposit formation...

  3. The dynamics of group formation among leeches

    Directory of Open Access Journals (Sweden)

    Giacomo eBisson

    2012-05-01

    Full Text Available Leeches exploring a new environment continuously meet each other and merge in temporary groups. After 2-3 hours, leeches become attracted to each other eventually forming a large and stable group. When their number is reduced, leeches remain solitary, behaving independently. Group formation is facilitated by body injection of serotonin (5-HT and the level of endogenous 5-HT is elevated in leeches forming a large group. In contrast, intravenous injection of 5-HT antagonists prevented injected leeches from joining a large group of conspecifics. When sensilla near the head were ablated or the supraesophageal ganglion disconnected, leeches remained solitary, but explored the environment swimming and crawling. These results suggest that group formation is initiated by a release of 5-HT triggered by sensilla stimulation and its dynamics can be explained by the establishment of a reinforcement dynamics, as observed during human group formation. As 5-HT affects social interactions also in humans, group formation in leeches and humans share a similar dynamics and hormonal control.

  4. PECULIAR FEATURES PERTAINING TO SOIL DEPOSIT FORMATION IN THE MESOPOTAMIA ZONE OF IRAQ

    Directory of Open Access Journals (Sweden)

    A. Al-Robai Ali

    2013-01-01

    Full Text Available The paper considers geological conditions for sedimentary mantle formation. In the geological past limestone deposits and sedimentation rock mass from fragmentary materials brought by water flows were formed in the southern part of the stretched geosyncline which had been submerged by shallow sea. By lapse of time deposits were transferred into sandstone, siltstone and mudstone that represented the bottom part of rock mass. Continental conditions were established as a result of orogenic process which took place nearly 30–50 million years ago. Erosional activity of wind and flowing waters was observed on the surface for a long period of time.The top part of soil rock mass is represented by alluvial deposits of the rivers Tigris and Euphrates. During the process of sediment deposition more full-flowing Tigris caused more complicated dynamics of water channels  including meandering and changeability of inter-bedding.Engineering and geological investigations have been carried out with the purpose to study structure of soil rock mass in various regions of the country (Al-Diwaniya, Khidr, Al-Nasiriya and Khila. Specific drill columns have been selected on the basis of analysis of soil rock masses.  Theses drill columns may serve for further selection of rational types of foundations (shallow foundation, piles foundation or creation of artificial foundations (cementing, armoring etc.. 

  5. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    Directory of Open Access Journals (Sweden)

    J. Lauros

    2010-08-01

    Full Text Available We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical profile of particle number distribution does not correspond to observations. Instead organic induced nucleation leads to good agreement confirming the relevance of the aerosol formation mechanism including organic compounds emitted by biosphere.

    Simulation of aerosol concentration inside the atmospheric boundary layer during nucleation days shows highly dynamical picture, where particle formation is coupled with chemistry and turbulent transport. We have demonstrated suitability of our turbulent mixing scheme in reproducing most important characteristics of particle dynamics inside the atmospheric boundary layer. Deposition and particle flux simulations show that deposition affects noticeably only the smallest particles at the lowest part of the atmospheric boundary layer.

  6. Modern sedimentary environments and dynamic depositional systems in the southern Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Based on analyses of more than 600 surface sediment samples together with large amounts of previous sedimentologic and hydrologic data, the characteristics of modern sedimentary environments and dynamic depositional systems in the southern Yellow Sea (SYS) are expounded, and the controversial formation mechanism of muddy sediments is also discussed. The southern Yellow Sea shelf can be divided into low-energy sedimentary environment and high-energy sedimentary environment; the low- energy sedimentary environment can be further divided into cyclonic and anticyclonic ones, and the high-energy environment is subdivided into high-energy depositional and eroded environments. In the shelf low-energy environments, there developed muddy depositional system. In the central part of the southern Yellow Sea, there deposited the cold eddy sediments under the actions of a meso-scale cyclonic eddy (cold eddy), and in the southeast of the southern Yellow Sea, an anticyclonic eddy muddy depositional system (warm eddy sediment) was formed. These two types of sediments showed evident differences in grain size, sedimentation rate, sediment thickness and mineralogical characteristics. The high-energy environments were covered with sandy sediments on seabed; they appeared mainly in the west, south and northeast of the southern Yellow Sea. In the high-energy eroded environment, large amounts of sandstone gravels were distributed on seabed. In the high-energy depositional environment, the originally deposited fine materials (including clay and fine silt) were gradually re-suspended and then transported to a low-energy area to deposit again. In this paper, the sedimentation model of cyclonic and anticyclonic types of muddy sediments is established, and a systematic interpretation for the formation cause of muddy depositional systems in the southern Yellow Sea is given.

  7. Environment of deposition of Clear Fork Formation: Yoakum County, Texas

    Energy Technology Data Exchange (ETDEWEB)

    Moore, B.K.

    1987-05-01

    The Clear Fork Formation is Permian (Leonardian) in age and constitutes a major oil-bearing unit in the Permian basin of west Texas. In Yoakum County, west Texas, the upper Clear Fork carbonates record a subtidal upward-shoaling sequence of deposition. A small bryozoan-algal patch reef is situated within these carbonates near the southern edge of the North Basin platform. The reef is completely dolomitized, but paramorphic replacement has facilitated a study of the paleoecology, lateral variations, and community succession within this buildup. Build-ups of this type are scarcely known in strata of Permian age. The reef was apparently founded on a coquina horizon at the base of the buildup. The reef apparently had a low-relief, dome-shaped morphology. The trapping and binding of sediment by bryozoa appear to have been the main constructional process. A significant role was also played by encrusting forams and the early precipitation of submarine cements, both of which added rigidity to the structure. The reef also contains a low-diversity community of other invertebrates. Algal constituents predominate at the basinward edge of the buildup. The reef was formed entirely subaqueously on a broad, relatively shallow tropical marine carbonate shelf environment. An understanding of the lithofacies distribution and paragenesis within this sequence will provide information on porosity variations and the nature and distribution of permeability barriers. Such information is useful in reservoir modeling studies and for secondary recovery techniques in shelf-edge carbonate reservoirs of this type.

  8. Molecular dynamics simulation of gold cluster growth during sputter deposition

    Science.gov (United States)

    Abraham, J. W.; Strunskus, T.; Faupel, F.; Bonitz, M.

    2016-05-01

    We present a molecular dynamics simulation scheme that we apply to study the time evolution of the self-organized growth process of metal cluster assemblies formed by sputter-deposited gold atoms on a planar surface. The simulation model incorporates the characteristics of the plasma-assisted deposition process and allows for an investigation over a wide range of deposition parameters. It is used to obtain data for the cluster properties which can directly be compared with recently published experimental data for gold on polystyrene [M. Schwartzkopf et al., ACS Appl. Mater. Interfaces 7, 13547 (2015)]. While good agreement is found between the two, the simulations additionally provide valuable time-dependent real-space data of the surface morphology, some of whose details are hidden in the reciprocal-space scattering images that were used for the experimental analysis.

  9. Mechanisms of fat, oil and grease (FOG) deposit formation in sewer lines.

    Science.gov (United States)

    He, Xia; de los Reyes, Francis L; Leming, Michael L; Dean, Lisa O; Lappi, Simon E; Ducoste, Joel J

    2013-09-01

    FOG deposits in sewer systems have recently been shown to be metallic salts of fatty acids. However, the fate and transport of FOG deposit reactant constituents and the complex interactions during the FOG deposit formation process are still largely unknown. In this study, batch tests were performed to elucidate the mechanisms of FOG deposit formation that lead to sanitary sewer overflows (SSOs). We report the first formation of FOG deposits on a concrete surface under laboratory conditions that mimic the formation of deposits in sewer systems. Results showed that calcium, the dominant metal in FOG deposits, can be released from concrete surfaces under low pH conditions and contribute to the formation process. Small amounts of additional oil to grease interceptor effluent substantially facilitated the air/water or pipe surface/water interfacial reaction between free fatty acids and calcium to produce surface FOG deposits. Tests of different fatty acids revealed that more viscous FOG deposit solids were formed on concrete surfaces, and concrete corrosion was accelerated, in the presence of unsaturated FFAs versus saturated FFAs. Based on all the data, a comprehensive model was proposed for the mechanisms of FOG deposit formation in sewer systems.

  10. Probe Measurements of Ash Deposit Formation Rate and Shedding in a Biomass Suspension-Fired boiler

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming;

    The aim of this study was to investigate ash deposit formation rate, heat uptake reduction and deposit removal by using advanced online ash deposition and sootblowing probes in a 350 MWth suspension-fired boiler, utilizing wood and straw pellets as fuel. The influence of fuel type (straw share...

  11. Spacecraft formation flying: Dynamics, control and navigation

    Science.gov (United States)

    Alfriend, Kyle Terry; Vadali, Srinivas Rao; Gurfil, Pini; How, Jonathan; Breger, Louis S.

    2009-12-01

    Space agencies are now realizing that much of what has previously been achieved using hugely complex and costly single platform projects - large unmanned and manned satellites (including the present International Space Station) - can be replaced by a number of smaller satellites networked together. The key challenge of this approach, namely ensuring the proper formation flying of multiple craft, is the topic of this second volume in Elsevier's Astrodynamics Series, Spacecraft Formation Flying: Dynamics, control and navigation. In this unique text, authors Alfriend et al. provide a coherent discussion of spacecraft relative motion, both in the unperturbed and perturbed settings, explain the main control approaches for regulating relative satellite dynamics, using both impulsive and continuous maneuvers, and present the main constituents required for relative navigation. The early chapters provide a foundation upon which later discussions are built, making this a complete, standalone offering. Intended for graduate students, professors and academic researchers in the fields of aerospace and mechanical engineering, mathematics, astronomy and astrophysics, Spacecraft Formation Flying is a technical yet accessible, forward-thinking guide to this critical area of astrodynamics.

  12. The dynamics of travertine terrace formation

    CERN Document Server

    Hammer, O; Jamtveit, B; Dysthe, Dag K.; Hammer, Oyvind; Jamtveit, Bjorn

    2006-01-01

    Travertine (limestone) terraces are common in caves, springs and rivers worldwide, and represent one of the most striking examples of geological pattern formation on the Earth's surface. The terraces form over a wide range of scales, from millimeters to tens of meters. Their origin has been poorly understood, but most likely involves a coupling between the precipitation rate and hydrodynamics. Microbial activity may also play a role. Here we present a minimal model based on shallow water flow and an empirical positive correlation between the flow velocity and precipitation rate. The resulting selforganizing pattern formation process displays rich and unusual dynamics, consistent with field observations. Terraces coarsen with time, fold into lobes and migrate downstream with differential rates, resulting in striking patterns. This model, in which topography grows rather than erodes in response to rapid flow, produces patterns that are completely different from those generated by flow driven erosion.

  13. Dynamics of gradient formation by intracellular shuttling

    Energy Technology Data Exchange (ETDEWEB)

    Berezhkovskii, Alexander M. [Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Bethesda, Maryland 20892 (United States); Shvartsman, Stanislav Y. [Department of Chemical and Biological Engineering and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544 (United States)

    2015-08-21

    A number of important cellular functions rely on the formation of intracellular protein concentration gradients. Experimental studies discovered a number of mechanisms for the formation of such gradients. One of the mechanisms relies on the intracellular shuttling of a protein that interconverts between the two states with different diffusivities, under the action of two enzymes, one of which is localized to the plasma membrane, whereas the second is uniformly distributed in the cytoplasm. Recent work reported an analytical solution for the steady state gradient in this mechanism, obtained in the framework of a one-dimensional reaction-diffusion model. Here, we study the dynamics in this model and derive analytical expressions for the Laplace transforms of the time-dependent concentration profiles in terms of elementary transcendental functions. Inverting these transforms numerically, one can obtain time-dependent concentration profiles of the two forms of the protein.

  14. Dynamics of gradient formation by intracellular shuttling

    Science.gov (United States)

    Berezhkovskii, Alexander M.; Shvartsman, Stanislav Y.

    2015-08-01

    A number of important cellular functions rely on the formation of intracellular protein concentration gradients. Experimental studies discovered a number of mechanisms for the formation of such gradients. One of the mechanisms relies on the intracellular shuttling of a protein that interconverts between the two states with different diffusivities, under the action of two enzymes, one of which is localized to the plasma membrane, whereas the second is uniformly distributed in the cytoplasm. Recent work reported an analytical solution for the steady state gradient in this mechanism, obtained in the framework of a one-dimensional reaction-diffusion model. Here, we study the dynamics in this model and derive analytical expressions for the Laplace transforms of the time-dependent concentration profiles in terms of elementary transcendental functions. Inverting these transforms numerically, one can obtain time-dependent concentration profiles of the two forms of the protein.

  15. Dynamical Models of Terrestrial Planet Formation

    CERN Document Server

    Lunine, Jonathan I; Raymond, Sean N; Morbidelli, Alessandro; Quinn, Thomas; Graps, Amara

    2009-01-01

    We review the problem of the formation of terrestrial planets, with particular emphasis on the interaction of dynamical and geochemical models. The lifetime of gas around stars in the process of formation is limited to a few million years based on astronomical observations, while isotopic dating of meteorites and the Earth-Moon system suggest that perhaps 50-100 million years were required for the assembly of the Earth. Therefore, much of the growth of the terrestrial planets in our own system is presumed to have taken place under largely gas-free conditions, and the physics of terrestrial planet formation is dominated by gravitational interactions and collisions. The earliest phase of terrestrial-planet formation involve the growth of km-sized or larger planetesimals from dust grains, followed by the accumulations of these planetesimals into ~100 lunar- to Mars-mass bodies that are initially gravitationally isolated from one-another in a swarm of smaller planetesimals, but eventually grow to the point of sig...

  16. Pore Scale Dynamics of Microemulsion Formation.

    Science.gov (United States)

    Unsal, Evren; Broens, Marc; Armstrong, Ryan T

    2016-07-19

    Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

  17. In situ measurements of oxygen dynamics in unsaturated archaeological deposits

    DEFF Research Database (Denmark)

    Matthiesen, Henning; Hollesen, Jørgen; Dunlop, Rory

    2015-01-01

    Oxygen is a key parameter in the degradation of archaeological material, but little is known of its dynamics in situ. In this study, 10 optical oxygen sensors placed in a 2 m deep test pit in the cultural deposits at Bryggen in Bergen have monitored oxygen concentrations every half hour for more ...... of the soil exceeds 10–15% vol, while oxygen dissolved in infiltrating rainwater is of less importance for the supply of oxygen in the unsaturated zone.......Oxygen is a key parameter in the degradation of archaeological material, but little is known of its dynamics in situ. In this study, 10 optical oxygen sensors placed in a 2 m deep test pit in the cultural deposits at Bryggen in Bergen have monitored oxygen concentrations every half hour for more...... than a year. It is shown that there is a significant spatial and temporal variation in the oxygen concentration, which is correlated to measured soil characteristics, precipitation, soil water content and degradation of organic material. In these deposits oxygen typically occurs when the air content...

  18. Deposit Formation during Coal-Straw Co-Combustion in a Utility PF-Boiler

    DEFF Research Database (Denmark)

    Andersen, Karin Hedebo

    1998-01-01

    observed, but can not represent the mature deposits satisfactorily. The chemical composition of the mature deposits indicate, that sulphate based consolidation is of importance in the deposit maturation.The chemical elements of primary interest in coal-straw co-combustion are K and Cl, which are both...... introduced with the straw was bonded as K-Al-silicate during combustion, and the remaining available K formed K2SO4, which could participate in deposit formation and consolidation. No significant participation of K was seen in the coal ash deposits, whereas K was a large contributor the up- and downstream.......In conclusion, this study has provided new knowledge on the effects of coal-straw co-combustion on fouling deposit formation in a full-scale PF-boiler, including an experimental and thermodynamic evaluation of the behaviour of elements originating from the straw in deposits and fly ash, and the limits...

  19. Ash Deposit Formation and Deposit Properties. A Comprehensive Summary of Research Conducted at Sandia's Combustion Research Facility

    Energy Technology Data Exchange (ETDEWEB)

    Larry L. Baxter

    2000-08-01

    This report summarizes experimental and theoretical work performed at Sandia's Combustion Research Facility over the past eight years on the fate of inorganic material during coal combustion. This work has been done under four broad categories: coal characterization, fly ash formation, ash deposition, and deposit property development. The objective was to provide sufficient understanding of these four areas to be able to predict coal behavior in current and advanced conversion systems. This work has led to new characterization techniques for fuels that provide, for the first time, systematic and species specific information regarding the inorganic material. The transformations of inorganic material during combustion can be described in terms of the net effects of the transformations of these individual species. Deposit formation mechanisms provide a framework for predicting deposition rates for abroad range of particle sizes. Predictions based on these rates many times are quite accurate although there are important exceptions. A rigorous framework for evaluating deposit has been established. Substantial data have been obtained with which to exercise this framework, but this portion of the work is less mature than is any other. Accurate prediction of deposit properties as functions of fuel properties, boiler design, and boiler operating conditions represents the single most critical area where additional research is needed.

  20. Deposit formation in a full-scale pulverized wood-fired power plant with and without coal fly ash addition

    DEFF Research Database (Denmark)

    Wu, Hao; Shafique Bashir, Muhammad; Jensen, Peter Arendt

    2013-01-01

    temperatures of ~1300oC and ~800oC, respectively. It was found that during pulverized wood combustion, the deposit formation at the hightemperature location was characterized by a slow and continuous growth of deposits followed by the shedding of a large layer of deposits, while the deposit formation...

  1. Event Normalization Through Dynamic Log Format Detection

    Institute of Scientific and Technical Information of China (English)

    Christoph Meinel

    2014-01-01

    The analytical and monitoring capabilities of central event re-positories, such as log servers and intrusion detection sys-tems, are limited by the amount of structured information ex-tracted from the events they receive. Diverse networks and ap-plications log their events in many different formats, and this makes it difficult to identify the type of logs being received by the central repository. The way events are logged by IT systems is problematic for developers of host-based intrusion-detection systems (specifically, host-based systems), develop-ers of security-information systems, and developers of event-management systems. These problems preclude the develop-ment of more accurate, intrusive security solutions that obtain results from data included in the logs being processed. We propose a new method for dynamically normalizing events into a unified super-event that is loosely based on the Common Event Expression standard developed by Mitre Corporation. We explain how our solution can normalize seemingly unrelat-ed events into a single, unified format.

  2. Effect of oils and structural materials on the formation of high-temperature deposits

    Energy Technology Data Exchange (ETDEWEB)

    Gutenev, B.S.; Poroikov, N.P.; Bakunin, V.N.

    1987-01-01

    The objective of the study was to establish a relationship between the amount of deposits formed on the hot surfaces of gas turbine engine components, oil composition, and the nature of the structural materials in contact with the oil. A method and a test apparatus are described which make it possible to evaluate the effect of various structural materials on the formation of deposits. It is shown that copper, lead, and brass have a particularly strong catalytic effect on the formation of high-temperature deposits in the presence of oils. Various synthetic oils are evaluated with respect to their tendency to form deposits, and the mechanisms responsible for the formation of high-temperature deposits are briefly examined. 7 references.

  3. Quantifying fat, oil, and grease deposit formation kinetics

    Science.gov (United States)

    Fat, oil, and grease (FOG) deposits formed in sanitary sewers are calcium-based saponified solids that are responsible for a significant number of nationwide sanitary sewer overflows (SSOs) across United States. In the current study, the kinetics of lab-based saponified solids were determined to un...

  4. Droplet sizes, dynamics and deposition in vertical annular flow

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, J C.B.; Dukler, A E

    1985-10-01

    The role of droplets in vertical upwards annular flow is investigated, focusing on the droplet size distributions, dynamics, and deposition phenomena. An experimental program was performed based on a new laser optical technique developed in these laboratories and implemented here for annular flow. This permitted the simultaneous measurement of droplet size, axial and radial velocity. The dependence of droplet size distributions on flow conditions is analyzed. The Upper-Log Normal function proves to be a good model for the size distribution. The mechanism controlling the maximum stable drop size was found to result from the interaction of the pressure fluctuations of the turbulent flow of the gas core with the droplet. The average axial droplet velocity showed a weak dependence on gas rates. This can be explained once the droplet size distribution and droplet size-velocity relationship are analyzed simultaneously. The surprising result from the droplet conditional analysis is that larger droplet travel faster than smaller ones. This dependence cannot be explained if the drag curves used do not take into account the high levels of turbulence present in the gas core in annular flow. If these are considered, then interesting new situations of multiplicity and stability of droplet terminal velocities are encountered. Also, the observed size-velocity relationship can be explained. A droplet deposition is formulated based on the particle inertia control. This permitted the calculation of rates of drop deposition directly from the droplet size and velocities data.

  5. Computational fluid dynamics analysis of aerosol deposition in pebble beds

    Science.gov (United States)

    Mkhosi, Margaret Msongi

    2007-12-01

    The Pebble Bed Modular Reactor is a high temperature gas cooled reactor which uses helium gas as a coolant. The reactor uses spherical graphite pebbles as fuel. The fuel design is inherently resistant to the release of the radioactive material up to high temperatures; therefore, the plant can withstand a broad spectrum of accidents with limited release of radionuclides to the environment. Despite safety features of the concepts, these reactors still contain large inventories of radioactive materials. The transport of most of the radioactive materials in an accident occurs in the form of aerosol particles. In this dissertation, the limits of applicability of existing computational fluid dynamics code FLUENT to the prediction of aerosol transport have been explored. The code was run using the Reynolds Averaged Navier-Stokes turbulence models to determine the effects of different turbulence models on the prediction of aerosol particle deposition. Analyses were performed for up to three unit cells in the orthorhombic configuration. For low flow conditions representing natural circulation driven flow, the laminar flow model was used and the results were compared with existing experimental data for packed beds. The results compares well with experimental data in the low flow regime. For conditions corresponding to normal operating of the reactor, analyses were performed using the standard k-ɛ turbulence model. From the inertial deposition results, a correlation that can be used to estimate the deposition of aerosol particles within pebble beds given inlet flow conditions has been developed. These results were converted into a dimensionless form as a function of a modified Stokes number. Based on results obtained in the laminar regime and for individual pebbles, the correlation developed for the inertial impaction component of deposition is believed to be credible. The form of the correlation developed also allows these results to be applied to pebble beds of different

  6. Ash Deposit Formation and Removal in a Straw and Wood Suspension-Fired Boiler

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming

    Utilization of biomass on large suspension-fired boilers is a potentially efficient method to reduce net CO2 emissions and reduce the consumption of fossil fuels. However, ash deposit formation on heat transfer surfaces may cuase operational problems and in severe cases lead to boiler stop...... and manual cleaning. Most studies on ash deposition and removal has been done on biomass grate boilers, while only limited data is available from biomass suspension-firing. The aim of this study was to investigate deposit mass uptake, heat uptake reduction, deposit characteristics, and deposit removal...... scale experimental studies conducted by CHEC indicated that there was not a big difference regarding final deposit mass uptake during straw suspension-firing and combustion on grate. The shedding (deposit removal) events were investigated when the nearby plant sootblower was shutdown. It was identified...

  7. Supercritical fluid molecular spray film deposition and powder formation

    Science.gov (United States)

    Smith, Richard D.

    1986-01-01

    Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. Upon expansion and supersonic interaction with background gases in the low pressure region, any clusters of solvent are broken up and the solvent is vaporized and pumped away. Solute concentration in the solution is varied primarily by varying solution pressure to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solvent clustering and solute nucleation are controlled by manipulating the rate of expansion of the solution and the pressure of the lower pressure region. Solution and low pressure region temperatures are also controlled.

  8. Tectonophysics of hydrothermal ore formation: an example of the Antei Mo-U deposit, Transbaikalia

    Science.gov (United States)

    Petrov, V. A.; Rebetsky, Yu. L.; Poluektov, V. V.; Burmistrov, A. A.

    2015-07-01

    The Antei deposit of the southeastern Transbaikalian region is one of the largest uranium mines in Russia. It is hosted by the Late Paleozoic granitic basement of the Streltsovskaya caldera and was formed as a result of Late Mesozoic tectonothermal activity. Vein and stockwork-disseminated molybdenum-uranium mineralization at this deposit is controlled by zones of intense hydrothermal alteration, cataclasis, brecciation, and intense fracturing along steeply dipping faults, which acted as conduits for mineralizing fluids and hosts to the ore bodies. The upper edge of the ore-bearing zone is located at a depth of 400 m, and its lower edge was intersected at a depth of 1300 m from the day surface. The conditions of ore localization were determined using structural-geological and petrophysical studies coupled with numerical modeling of the effects of gravitational body forces at purely elastic and postcritical elastoplastic deformational stages. The dynamics of the tectonic stress field in the rock massif was reconstructed using the results of mapping of morphogenetic and kinematic characteristics of fault and fracture systems, as well as data on petrography and mineralogy of rocks and vein-filling material. It was shown that the fault framework of the deposit was formed in four tectonic stages, three of which took place in the geologic past and one of which reflects recent geologic history. Each tectonic stage was characterized by different parameters of the tectonic stress-strain field, fault kinematics, and conditions of mineral formation. The following types of metasomatic rocks are recognized within the deposit: high-temperature K-feldspar rocks and albitites (formed during the Late Paleozoic as the primary structural elements of a granitic massif) and Late Mesozoic low-temperature preore (hydromicatized rocks), synore (hematite, albite, chlorite, and quartz) and postore (kaolinite-smectite) rocks. The following petrophysical parameters were determined for all

  9. Post-deposition dynamics of multiple cluster aggregation on liquid surfaces

    Institute of Scientific and Technical Information of China (English)

    Wu Feng-Min; Xu You-Sheng; Ye Gao-Xiang; Wu Zi-Qin

    2005-01-01

    A comprehensive simulation model-deposition, diffusion, rotation and aggregation-is presented to demonstrate the post-deposition phenomena of multiple cluster growth on liquid surfaces, such as post-deposition nucleation, postdeposition growth and post-deposition coalescence. Emphasis is placed on the relaxations of monomer density, dimer density and cluster density as well as combined cluster-plus-monomer density with time after deposition ending. It isshown that post-deposition coalescence largely takes place after deposition due to the large mobility of clusters on liquid surfaces, while the post-deposition nucleation is only possible before the saturation cluster density is reached at the end of the deposition. The deposition flux and the moment of deposition ending play important roles in the post-deposition dynamics.

  10. Preliminary protein corona formation stabilizes gold nanoparticles and improves deposition efficiency

    Science.gov (United States)

    Luby, Alexandra O.; Breitner, Emily K.; Comfort, Kristen K.

    2016-08-01

    Due to their advantageous characteristics, gold nanoparticles (AuNPs) are being increasingly utilized in a vast array of biomedical applications. However, the efficacy of these procedures are highly dependent upon strong interactions between AuNPs and the surrounding environment. While the field of nanotechnology has grown exponentially, there is still much to be discovered with regards to the complex interactions between NPs and biological systems. One area of particular interest is the generation of a protein corona, which instantaneously forms when NPs encounter a protein-rich environment. Currently, the corona is viewed as an obstacle and has been identified as the cause for loss of application efficiency in physiological systems. To date, however, no study has explored if the protein corona could be designed and advantageously utilized to improve both NP behavior and application efficacy. Therefore, we sought to identify if the formation of a preliminary protein corona could modify both AuNP characteristics and association with the HaCaT cell model. In this study, a corona comprised solely of epidermal growth factor (EGF) was successfully formed around 10-nm AuNPs. These EGF-AuNPs demonstrated augmented particle stability, a modified corona composition, and increased deposition over stock AuNPs, while remaining biocompatible. Analysis of AuNP dosimetry was repeated under dynamic conditions, with lateral flow significantly disrupting deposition and the nano-cellular interface. Taken together, this study demonstrated the plausibility and potential of utilizing the protein corona as a means to influence NP behavior; however, fluid dynamics remains a major challenge to progressing NP dosimetry.

  11. Influence of oils and materials of construction on formation of high-temperature deposits

    Energy Technology Data Exchange (ETDEWEB)

    Gutenev, B.S.; Poroikov, N.P.; Bakunin, V.N.

    1988-01-01

    A correlation was established between the quantity of deposits formed on the hot surfaces of gas turbine engines and the oil composition and material composition and corrosion behavior for those engine parts in contact with the oil. A test stand was designed for determining the effect of engine materials on deposit formation. Test results established that the strongest catalytic effects on the process of high-temperature deposit formation derive from copper, lead, and brass components. The metals were tested in a range of synthetic lubricating oils. Data were compared on interactions of the oils with a steel surface and were ranked in order of decreasing tendency to form deposits. Maximum working temperatures for the oils were determined. The effects of oil additives on deposition were also assessed.

  12. Influence of Deposit Formation on Corrosion at a Straw Fired boiler

    DEFF Research Database (Denmark)

    Hansen, Lone Aslaug; Michelsen, Hanne Philbert; Frandsen, Flemming;

    2000-01-01

    Straw-fired boilers generally experience severe problems with deposit formation and are expected to suffer from severe superheater corrosion at high steam temperatures due to the large alkali and chlorine content in straw. In this study, deposits collected (1) on air-cooled probes and (2) directly...... at the existing heat transfer surfaces of a straw-fired boiler have been examined. Deposits collected on air-cooled probes were found to consist of an inner layer of KCl and an outer layer of sintered fly ash. Ash deposits formed on the heat transfer surfaces all had a characteristic layered structure......, with a dense layer of K2SO4 present adjacent to the metal surface. It is argued that the K2SO4 layer present adjacent to the metal surface may lead to reduced corrosion rates at this boiler. A discussion of the deposit structure, the K2SO4 layer formation mechanism, and the influence of the inner layer...

  13. Role of CO2 in the formation of gold deposits.

    Science.gov (United States)

    Phillips, G N; Evans, K A

    2004-06-24

    Much of global gold production has come from deposits with uneconomic concentrations of base metals, such as copper, lead and zinc. These 'gold-only' deposits are thought to have formed from hot, aqueous fluids rich in carbon dioxide, but only minor significance has been attached to the role of the CO2 in the process of gold transport. This is because chemical bonding between gold ions and CO2 species is not strong, and so it is unlikely that CO2 has a direct role in gold transport. An alternative indirect role for CO2 as a weak acid that buffers pH has also appeared unlikely, because previously inferred pH values for such gold-bearing fluids are variable. Here we show that such calculated pH values are unlikely to record conditions of gold transport, and propose that CO2 may play a critical role during gold transport by buffering the fluid in a pH range where elevated gold concentration can be maintained by complexation with reduced sulphur. Our conclusions, which are supported by geochemical modelling, may provide a platform for new gold exploration methods.

  14. Formation of aluminum films on silicon by ion beam deposition: A comparison with ionized cluster beam deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zuhr, R.A.; Haynes, T.E.; Galloway, M.D. (Oak Ridge National Lab., TN (USA)); Tanaka, S.; Yamada, A.; Yamada, I. (Kyoto Univ. (Japan). Ion Beam Engineering Lab.)

    1990-01-01

    The direct ion beam deposition (IBD) technique has been used to study the formation of oriented aluminum films on single crystal silicon substrates. In the IBD process, thin film growth is accomplished by decelerating a magnetically-analyzed ion beam to low energies (10--200 eV) for direct deposition onto the substrate under UHV conditions. The energy of the incident ions can be selected to provide the desired growth conditions, and the mass analysis ensures good beam purity. The aluminum on silicon system is one which has been studied extensively by ionized cluster beam (ICB) deposition. In this work, we have studied the formation of such films by IBD with emphasis on the effects of ion energy, substrate temperature, and surface cleanliness. Oriented films have been grown on Si(111) at temperatures from 40{degree} to 300{degree}C and with ion energies from 30 to 120 eV per ion. Completed films were analyzed by ion scattering, x-ray diffraction, scanning electron microscopy, and optical microscopy. Results achieved for thin films grown by IBD are compared with results for similar films grown by ICB deposition. 15 refs., 3 figs.

  15. Mesoscopic Modeling of Thrombus Formation and Growth: Platelet Deposition in Complex Geometries

    Science.gov (United States)

    Yazdani, Alireza; Karniadakis, George

    2014-11-01

    Haemodynamics and blood rheology are important contributing factors to thrombus formation at a vulnerable vessel wall, and adhesion of platelets to a vascular surface, particularly in regions of flow stagnation, recirculation and reattachment is significantly important in formation of thrombi. For example, haemodynamic micro-environment can have effects on thrombosis inside the atherosclerotic plaques and aneurysms. To study these effects, we have developed and validated a model for platelet aggregation in blood flow using Dissipative Particle Dynamics (DPD) method. In this model platelets are considered as single DPD particles interacting with each other via Morse potential once activated. We assign an activation delay time to each platelet such that they remain passive during that time. We investigate the effect of different geometries on platelet aggregation by considering arterial stenosis at different levels of occlusion, and aneurysms of different shapes and sizes. The results show a marked increase in platelet aggregation within the boundaries of deceleration zone by increasing the degree of stenosis. Further, we observe enhanced platelet margination and wall deposition in the presence of red blood cells.

  16. Compartmentalization of ER-Bound Chaperone Confines Protein Deposit Formation to the Aging Yeast Cell.

    Science.gov (United States)

    Saarikangas, Juha; Caudron, Fabrice; Prasad, Rupali; Moreno, David F; Bolognesi, Alessio; Aldea, Martí; Barral, Yves

    2017-03-20

    In order to produce rejuvenated daughters, dividing budding yeast cells confine aging factors, including protein aggregates, to the aging mother cell. The asymmetric inheritance of these protein deposits is mediated by organelle and cytoskeletal attachment and by cell geometry. Yet it remains unclear how deposit formation is restricted to the aging lineage. Here, we show that selective membrane anchoring and the compartmentalization of the endoplasmic reticulum (ER) membrane confine protein deposit formation to aging cells during division. Supporting the idea that the age-dependent deposit forms through coalescence of smaller aggregates, two deposits rapidly merged when placed in the same cell by cell-cell fusion. The deposits localized to the ER membrane, primarily to the nuclear envelope (NE). Strikingly, weakening the diffusion barriers that separate the ER membrane into mother and bud compartments caused premature formation of deposits in the daughter cells. Detachment of the Hsp40 protein Ydj1 from the ER membrane elicited a similar phenotype, suggesting that the diffusion barriers and farnesylated Ydj1 functioned together to confine protein deposit formation to mother cells during division. Accordingly, fluorescence correlation spectroscopy measurements in dividing cells indicated that a slow-diffusing, possibly client-bound Ydj1 fraction was asymmetrically enriched in the mother compartment. This asymmetric distribution depended on Ydj1 farnesylation and intact diffusion barriers. Taking these findings together, we propose that ER-anchored Ydj1 binds deposit precursors and prevents them from spreading into daughter cells during division by subjecting them to the ER diffusion barriers. This ensures that the coalescence of precursors into a single deposit is restricted to the aging lineage.

  17. Mars Environmental Chamber for Dynamic Dust Deposition and Statics Analysis

    Science.gov (United States)

    Moeller, L. E.; Tuller, M.; Islam, M. R.; Baker, L.; Kuhlman, K.

    2004-01-01

    Recent observations of the 2001 dust storms encircling Mars confirm predictions of environmental challenges for exploration. Martian dust has been found to completely mantle the Martian surface over thousands of square kilometers and the opacity of airborne dust has been shown to be capable of modifying atmospheric temperature, radiative transfer and albedo. Planetary dust cycling dynamics are suggested to be a key factor in the evolution of the Martian surface. Long-term robotic and manned exploration of Mars will be confronted by dust deposition in periods of atmospheric calm and violent wind storms. Aeolian dust deposition recorded during the Mars Pathfinder mission was estimated to fall at rates of 20-45 microns per Earth year. Although many tools of exploration will be challenged by coating, adhesion, abrasion and possible chemical reaction of deposited, wind blown and actively disturbed Martian dust, solar cells are thought to be of primary concern. Recent modeling work of power output by gallium arsenide/germanium solar cells was validated by the Pathfinder Lander data and showed power output decreases of 0.1 to 0.5% per Martian day. A major determinant for the optimal positioning angle of solar panels employed in future missions is the angle of repose of the settling dust particles that is dependent on a variety of physical and chemical properties of the particles, the panel surface, and the environmental conditions on the Mars surface. While the effects of many of these factors are well understood qualitatively, quantitative analyses, especially under physical and chemical conditions prevailing on the Mars surface are lacking.

  18. Diagenesis, provenance and depositional environments of the Bunter Sandstone Formation

    DEFF Research Database (Denmark)

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    The Bunter Sandstone Formation in the northern North German Basin has large geothermal potential with high porosity and permeability (generally >15% and >100 mD, respectively) and with pore fluid temperatures that are adequate for geothermal energy production (c. 55–60˚C). A combined investigatio...

  19. Fundamental studies of the mechanisms of slag deposit formation: Studies on initiation, growth and sintering in the formation of utility boiler deposits: Topical technical report

    Energy Technology Data Exchange (ETDEWEB)

    Tangsathitkulchai, M.; Austin, L.G.

    1986-03-01

    Three laboratory-scale devices were utilized to investigate the mechanisms of the initiation, growth and sintering process involved in the formation of boiler deposits. Sticking apparatus investigations were conducted to study deposit initiation by comparing the adhesion behavior of the ash drops on four types of steel-based heat exchanger materials under the conditions found in a utility boiler and an entrained slagging gasifier. In addition, the adhesion behavior of the ash drops on a reduced steel surface were investigated. All the ash drops studied in this investigation were produced from bituminous coals.

  20. Combustion Chamber Deposits and PAH Formation in SI Engines Fueled by Producer Gas from Biomass Gasification

    DEFF Research Database (Denmark)

    Ahrenfeldt, Jesper; Henriksen, Ulrik Birk; Schramm, Jesper

    2003-01-01

    Investigations were made concerning the formation of combustion chamber deposits (CCD) in SI gas engines fueled by producer gas. The main objective was to determine and characterise CCD and PAH formation caused by the presence of the light tar compounds phenol and guaiacol in producer gas from an...

  1. Dolomitization of Carbonate Periplatform Deposit,Machari Formation (Middle to Late Cambrian),Korea

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The petrography, the geochemistry and the burial history all constrain the origin and modification history of dolomites in an ancient periplatform carbonate slope deposit,the Machari Formation (late Miclclle to early Late Cambrian),Korea. The formation is mainly composed of rhythmic bedding. laminated to bedded lime mudstone alternating with argillaceous lime mudstone. The rhythmic bedding is a product of the deposition of offshore periplatform ooze and hemipelagic clay on a periplatform slope. This formation also shows minor and intermittent influx of other lithofacies including the bioclastic-peloidal packstone, peloidal wackestone, and intraclasts deposited as turbidites. Five types of dolomite occur in the Machari Formation, whose occurrence.texture and geochemistry provide an insight into origin and modification history.

  2. Study of the various factors influencing deposit formation and operation of gasoline engine injection systems

    Science.gov (United States)

    Stepien, Z.

    2016-09-01

    Generally, ethanol fuel emits less pollutants than gasoline, it is completely renewable product and has the potential to reduce greenhouse gases emission but, at the same time can present a multitude of technical challenges to engine operation conditions including creation of very adverse engine deposits. These deposits increasing fuel consumption and cause higher exhaust emissions as well as poor performance in drivability. This paper describes results of research and determination the various factors influencing injector deposits build-up of ethanol-gasoline blends operated engine. The relationship between ethanol-gasoline fuel blends composition, their treatment, engine construction as well as its operation conditions and fuel injectors deposit formation has been investigated. Simulation studies of the deposit formation endanger proper functioning of fuel injection system were carried out at dynamometer engine testing. As a result various, important factors influencing the deposit creation process and speed formation were determined. The ability to control of injector deposits by multifunctional detergent-dispersant additives package fit for ethanol-gasoline blends requirements was also investigated.

  3. Deposit formation during coal-straw co-combustion in a utility PF-boiler

    Energy Technology Data Exchange (ETDEWEB)

    Hedebo Andersen, K.

    1998-08-01

    This work was based on experimental results from a two-year, full scale demonstration programme at the Strudstrup Power Station, Unit 1 (MKS1), owned by Midtkraft Energy Company. Primarily the results from the deposition trials, but also related experimental data, were used in the evaluation. Based upon the visual analyses of the upstream deposits it was found that the deposit amount and tenacity increased with increased exposure time, increased straw share, increased flue gas temperature and increased load (part to full load) during experiments with COCERR coal. The downstream deposits were in all cases powdery deposits, which could easily be removed. When utilising USILI2 coal with higher content of Fe and S than COCERR, the main effect was observed for coal combustion, where both deposit amount and tenacity increased compared to COCERR. From these results, the formation of possibly problematic upstream fouling deposits during coal-straw co-combustion is expected to occur primarily in the first pass. Based on the SEM analyses, the upstream probe deposits collected from the two hottest measuring positions were found to show different structural characteristics at 0 and 20% straw share. Without straw addition, a porous deposit with Fe-based fingerformation with a well-defined structural build-up was formed. At 20% straw share, a porous deposit without Fe-based fingerformation was formed, where large and small particles were deposited in a more random manner. No significant effect could be found in the deposition probe samples for an increase in probe metal temperature from 540 deg. C to 620 deg. C. The importance of deposit shedding was recognised from the experimental data, particularly for the upstream deposits at high flue gas temperatures, 20% straw share and 100% load. The probe deposits were in all cases smaller than those collected from the superheaters during outages after co-combustion at 10 and 20% straw share. However, at 10% straw share, the probe

  4. Boundedness of Formation Configuration for Nonlinear Three-body Dynamics

    Institute of Scientific and Technical Information of China (English)

    LI Peng; SONG Yongduan

    2011-01-01

    The configuration boundedness of the three-body model dynamics is studied for Sun-Earth formation flying missions. The three-body formation flying model is built up with considering the lunar gravitational acceleration and solar radiation pressure. Because traditional linearized dynamics based method has relatively lower accuracy, a modified nonlinear formation configuration analysis method is proposed in this paper. Comparative studies are carried out from three aspects, i.e., natural formation configuration with arbitrary departure time, initialization time and formation configuration boundedness, and specific initialization time for bounded formation configuration. Simulations demonstrate the differences between the two schemes,and indicate that the nonlinear dynamic method reduces the error caused by the model linearization and disturbance approximation, and thus provides higher accuracy for boundedness analysis, which is of value to initial parameters selection for natural three-body formation flying.

  5. Dynamics of lane formation in driven binary complex plasmas

    NARCIS (Netherlands)

    Sutterlin, K. R.; Wysocki, A.; Ivlev, A. V.; Rath, C.; Thomas, H. M.; Rubin-Zuzic, M.; W. J. Goedheer,; Fortov, V. E.; Lipaev, A. M.; Molotkov, V. I.; Petrov, O. F.; Morfill, G. E.; Lowen, H.

    2009-01-01

    The dynamical onset of lane formation is studied in experiments with binary complex plasmas under microgravity conditions. Small microparticles are driven and penetrate into a cloud of big particles, revealing a strong tendency towards lane formation. The observed time-resolved lane-formation proces

  6. Altered callose deposition during embryo sac formation of multi-pistil mutant (mp1) in Medicago sativa.

    Science.gov (United States)

    Zhou, H C; Jin, L; Li, J; Wang, X J

    2016-06-03

    Whether callose deposition is the cause or result of ovule sterility in Medicago sativa remains controversial, because it is unclear when and where changes in callose deposition and dissolution occur during fertile and sterile embryo sac formation. Here, alfalfa spontaneous multi-pistil mutant (mp1) and wild-type plants were used to compare the dynamics of callose deposition during embryo sac formation using microscopy. The results showed that both mutant and wild-type plants experienced megasporogenesis and megagametogenesis, and there was no significant difference during megasporogenesis. In contrast to the wild-type plants, in which the mature embryo sac was observed after three continuous cycles of mitosis, functional megaspores of mutant plants developed abnormally after the second round of mitosis, leading to degeneration of synergid, central, and antipodal cells. Callose deposition in both mutant and wild-type plants was first observed in the walls of megasporocytes, and then in the megaspore tetrad walls. After meiosis, the callose wall began to degrade as the functional megaspore underwent mitosis, and almost no callose was observed in the mature embryo sac in wild-type plants. However, callose deposition was observed in mp1 plants around the synergid, and increased with the development of the embryo sac, and was mainly deposited at the micropylar end. Our results indicate that synergid, central, and antipodal cells, which are surrounded by callose, may degrade owing to lack of nutrition. Callose accumulation around the synergid and at the micropylar end may hinder signals required for the pollen tube to enter the embryo sac, leading to abortion.

  7. Dependence of ion-induced Pd-silicide formation on nuclear energy deposition density

    Energy Technology Data Exchange (ETDEWEB)

    Horino, Yuji; Matsunami, Noriaki; Itoh, Noriaki

    1986-05-01

    Pd/sub 2/Si formation at the Pd-Si interface induced by irradiation with ions having a wide range of nuclear energy of deposition density has been investigated. It is found that the thickness of the silicide layer formed by irradiation is proportional to the ion fluence for irradiation with ions having low energy-deposition densities, while it is proportional to the square root of the fluence for irradiation with ions having energy-deposition densities. The results indicate that Pd/sub 2/Si formation is reaction limited when the energy-deposition density at the interface is low and is diffusion limited when it is high. The results are compared with the phenomenological theory developed by Horino et al. and it is shown that such a dependence of the limiting processes on the energy depositon density is induced when the diffusion is thermally activated while the reaction at the interface is radiation-enhanced.

  8. Formation of PbTe nanofilms by electrochemical atomic layer deposition (ALD)

    Energy Technology Data Exchange (ETDEWEB)

    Banga, Dhego O.; Vaidyanathan, Raman; Xuehai, Liang [Department of Chemistry, University of Georgia, Athens, GA 30602-2556 (United States); Stickney, John L. [Department of Chemistry, University of Georgia, Athens, GA 30602-2556 (United States)], E-mail: Stickney@chem.uga.edu; Cox, Stephen; Happeck, Uwe [Department of Physics and Astronomy, University of Georgia, Athens, GA 30602-2556 (United States)

    2008-10-01

    This article describes optimization of a cycle for the deposition of lead telluride (PbTe) nanofilms using electrochemical atomic layer deposition (ALD). PbTe is of interest for the formation of thermoelectric device structures. Deposits were formed using an ALD cycle on Au substrates, one atomic layer at a time, from separate solutions, containing Pb{sup 2+} or HTeO{sub 2}{sup +} ions. Single atomic layers were formed using surface limited reactions, referred to as underpotential deposition (UPD), so the deposition cycle consisted of alternating UPD of Te and Pb. The Pb deposition potential was maintained at -0.35 V throughout the 100 cycle-runs, while the Te deposition potential was ramped up from -0.55 V to -0.40 V over the first 20 cycles and then held constant for the remaining ALD cycles. Coulometry for the reduction of both Te and Pb indicated coverages near one monolayer, each cycle. Electron probe microanalysis (EPMA) indicated a uniform and stoichiometric deposit, with a Te/Pb ratio of 1.01. X-ray diffraction measurement showed that the thin films had the rock salt structure, with a preferential (2 0 0) orientation for the as formed deposits. No annealing was used. Infrared reflection absorption measurements of PbTe films formed with 50, 65, and 100 cycles indicated strong quantum confinement.

  9. Nanoparticle layer deposition for highly controlled multilayer formation based on high-coverage monolayers of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yue; Williams, Mackenzie G.; Miller, Timothy J.; Teplyakov, Andrew V., E-mail: andrewt@udel.edu

    2016-01-01

    This paper establishes a strategy for chemical deposition of functionalized nanoparticles onto solid substrates in a layer-by-layer process based on self-limiting surface chemical reactions leading to complete monolayer formation within the multilayer system without any additional intermediate layers — nanoparticle layer deposition (NPLD). This approach is fundamentally different from previously established traditional layer-by-layer deposition techniques and is conceptually more similar to well-known atomic and molecular layer deposition processes. The NPLD approach uses efficient chemical functionalization of the solid substrate material and complementary functionalization of nanoparticles to produce a nearly 100% coverage of these nanoparticles with the use of “click chemistry”. Following this initial deposition, a second complete monolayer of nanoparticles is deposited using a copper-catalyzed “click reaction” with the azide-terminated silica nanoparticles of a different size. This layer-by-layer growth is demonstrated to produce stable covalently-bound multilayers of nearly perfect structure over macroscopic solid substrates. The formation of stable covalent bonds is confirmed spectroscopically and the stability of the multilayers produced is tested by sonication in a variety of common solvents. The 1-, 2- and 3-layer structures are interrogated by electron microscopy and atomic force microscopy and the thickness of the multilayers formed is fully consistent with that expected for highly efficient monolayer formation with each cycle of growth. This approach can be extended to include a variety of materials deposited in a predesigned sequence on different substrates with a highly conformal filling. - Highlights: • We investigate the formation of high-coverage monolayers of nanoparticles. • We use “click chemistry” to form these monolayers. • We form multiple layers based on the same strategy. • We confirm the formation of covalent bonds

  10. Tsunami characteristics and formation potential of sandy tsunami deposit in Sanriku Coast: implications from numerical modeling

    Science.gov (United States)

    Sugawara, D.; Haraguchi, T.; Takahashi, T.

    2013-12-01

    Geological investigation of paleotsunami deposit is crucial for knowing the history and magnitude of tsunami events in the past. Among various kinds of grain sizes, sandy tsunami deposit has been best investigated by previous studies, because of its potential for identification in the sedimentary column. Many sandy tsunami deposits have been found from coastal plains, which have sandy beach and low-lying wetlands. However, sandy tsunami deposits in narrow valleys at rocky ria coast have rarely been found. It may be presumed that formation potential of sandy tsunami layer in the rocky coasts is generally lower than coastal plains, because of the absence of sandy beach, tsunami run-up on steeper slope and stronger return flow. In this presentation, characteristics of the 2011 Tohoku-oki earthquake tsunami in Sanriku Coast, a continuous rocky ria coast located in the northeast Japan, is investigated based on numerical modeling. In addition, the formation potential of sandy tsunami deposit is also investigated based on numerical modeling of sediment transport. Preliminary result of tsunami hydrodynamics showed that the waveform and amplification of the tsunami are clearly affected by the local bathymetry, which is associated with submerged topography formed during the last glacial stage. Although the tsunami height in the offshore of each bay is around 8.0 m, the tsunami height at the bay head was increased in different way. The amplification factor at the bay head was typically 2.0 among most of V-shaped narrow embayments; meanwhile the amplification factor is much lower than 1.0 at some cases. The preliminary result of the modeling of sediment transport predicted huge amount of sediments may be suspended into the water column, given that sandy deposit is available there. Massive erosion and deposition of sea bottom sediments may commonly take place in the bays. However, formation of onshore tsunami deposit differs from each other. Whether the suspended sediments

  11. Hydroxyapatite formation on biomedical Ti–Ta–Zr alloys by magnetron sputtering and electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Ju [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Jeong, Yong-Hoon [Biomechanics and Tissue Engineering Laboratory, Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials, Research Center of Nano-Interface Activation for Biomaterials, and Research Center for Oral Disease Regulation of the Aged, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Brantley, William A. [Division of Prosthodontics and Restorative Science, College of Dentistry, The Ohio State University, Columbus, OH (United States)

    2014-12-01

    The purpose of this study was to investigate hydroxyapatite formation on Ti-25Ta-xZr titanium alloys resulting from radio-frequency magnetron sputtering and electrochemical deposition. Electrochemical deposition of hydroxyapatite (HA) was first carried out using a cyclic voltammetry (CV) method at 80 °C in 5 mM Ca (NO{sub 3}){sub 2} + 3 mM NH{sub 4}H{sub 2}PO{sub 4}. Then a physical vapor deposition (PVD) coating was obtained by a radio-frequency (RF) magnetron sputtering technique. The microstructures, phase transformations, and morphologies of the hydroxyapatite films deposited on the titanium alloys were analyzed by optical microscopy (OM), X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDS) and field-emission scanning electron microscopy (FE-SEM). The morphologies of electrochemically deposited HA showed plate-like shapes on the titanium alloys, and the morphologies of the RF-sputtered HA coating had the appearance droplet particles on the plate-like precipitates that had formed by electrochemical deposition. For the RF-sputtered HA coatings, the Ca/P ratio was increased, compared to that for the electrochemically deposited HA surface. Moreover, the RF-sputtered HA coating, consisting of agglomerated droplet particles on the electrochemically deposited HA surface, had better wettability compared to the bulk titanium alloy surface. - Highlights: • Hydroxyapatite (HA) was deposited on Ti–Ta–Zr alloys by radio-frequency (RF) magnetron sputtering and a cyclic voltammetry. • The morphologies of the RF-sputtered HA coating on electrochemical deposits presented plate-like shapes with a droplet particle. • The Ca/P ratio for RF-sputtered HA coatings was greater than that for electrochemical deposited HA coatings. • The RF-sputtered and electrochemical HA coatings had superior wettability compared to the electrochemically deposited coatings.

  12. Thermodynamics and dynamics of the formation of spherical lipidic vesicles

    CERN Document Server

    Zapata, E Hernandez; Santamaría-Holek, I

    2009-01-01

    We propose a free energy expression accounting for the formation of spherical vesicles from planar lipidic membranes and derive a Fokker-Planck equation for the probability distribution describing the dynamics of vesicle formation. We found that formation may occur as an activated process for small membranes and as a transport process for sufficiently large membranes. We give explicit expressions for the transition rates and the characteristic time of vesicle formation in terms of the relevant physical parameters.

  13. Fundamental study of ash formation and deposition: Effect of reducing stoichiometry

    Energy Technology Data Exchange (ETDEWEB)

    Helble, J.J.; Bool, L.E.; Kang, S.G. [and others

    1995-11-01

    This project is designed to examine the effects of combustion stoichiometry on the fundamental aspects of ash formation and ash deposit initiation. Emphasis is being placed on reducing stoichiometries associated with low-NOx combustion, although a range of oxidant/fuel ratios are being considered. Previous work has demonstrated that ash formation depends strongly upon coal mineralogy, including mineral type, size, amount, and the presence of organically associated inorganic species. Combustion temperature and the oxidation state of iron also play a significant role. As these latter items will vary with changes in stoichiometry, research to determine the net effect on deposition is required.

  14. Kinetics of Hydrocarbon formation in a- C:H Film deposition plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Cal, E. de la; Tabares, F. L.

    1993-07-01

    The formation of C2 and Cp hydrocarbons during the PACVD of a-C:H films from admixtures of methane with H2 and He has been investigated by mass spectrometry under several deposition condition. The time evolution of the observed species indicates that the formation mechanisms of ethylene and acetylene are sensitive to the conditions of the wall during the growing of the film. Acetylene are sensitive to the conditions of the wall during the growing of the film. Acetylene formation was found to be directly related to the formation of the film on top of the carburized metal. (Author) 12 refs.

  15. Mineral-organic formations in Berezitovy deposit (the Amur region, Russia)

    Science.gov (United States)

    Vakh, E. A.; Vakh, A. S.; Petukhov, V. I.; Nikulina, T. V.; Tarasenko, I. A.

    2016-03-01

    The article examines the structure and composition of mineral-organic formations within the hypergenesis zone of Berezitovy deposit (the Amur region). The detailed study has shown that these recent formations are represented by algae identified as Trentepohlia jolithus (Linnaeus) Wallroth. The process of macro and micro element accumulation in these formations is likely to have a complex sediment-chemogenic-organogenic nature and results from the flow of the suspended and dissolved substances formed within the hypergenesis zone of sulphide ores. It is also assumed that some elements accumulated in the formations were previously absorbed by algae from the mineralized water environment.

  16. Formation of iron deposits during combustion of coals with varying iron-containing minerals

    Energy Technology Data Exchange (ETDEWEB)

    Alekhnovich, A.N.; Gladkov, V.E. (Vsesoyuznyii Teplotekhnicheskii Institut (USSR). Ural' skii Filial)

    1989-08-01

    Describes an investigation into microstructure and chemical composition of particles in the heavy fraction of ash and iron deposits produced during combustion of coals containing pyrite and siderite. Results show that the structural state of iron deposits varies considerably with different types of coal and in different temperature zones in the boiler duct, and that their formation is the result of adherence of particles with different aggregate states and chemical composition. Interaction between iron deposits and silica results in the formation of firelight (FeSiO{sub 4}) with a melting point of 1200 C. Depending on the ratio, the interaction of a sulfide melt with a firelight melt results in the formation of immiscible liquids, the release of SiO{sub 2} and the formation of silicate and metallic liquid surfaces with unique properties of wettability, and the formation of eutectic compositions (no more than 65% FeS, 35% FeO, 3% SiO{sub 2}) which set at 910-1000 C depending on the FeO and FeS content. Addition of silica increased sticking properties of products of pyrite conversion. In the absence of pyrite, the formation of immiscible liquids with different melting points may result from the reduction of the products of the dissociation of siderite to metallic iron and the formation of a metallic melt with carbon with a melting point of at least 1140 C. 10 refs.

  17. Lahars in Java: Initiations, Dynamics, Hazard Assessment And Deposition Processes

    Directory of Open Access Journals (Sweden)

    Franck Lavigne

    2016-05-01

    Full Text Available Lahar has been applied as a general term for rapidly flowing, high-concentration, poorly sorted sediment-laden mixtures of rock debris and water (other than normal streamflow from a volcano. Lahars are one of the most destructive phenomena associated with composite volcanoes, which are dominant in Java Island. Resulting deposits of lahar are poorly sorted, massive, made up of clasts (chiefly of volcanic composition, that generally include a mud-poor matrix. The aim of this research is threefold: to discuss the initiation of lahars occurrences, their dynamics, to assess the hazard and to analyse the deposition. Lahars are either a direct result of eruptive activity or not temporally related to eruptions. Syn-eruptive lahars may result from the transformation on pyroclastic flows or debris avalanches which transform to aqueous flows (e.g. at Papandayan in November 2002; They may be also generated through lake outburst or breaching (e.g. at Kelut in 1909 or 1966, and through removal of pyroclastic debris by subsequent heavy rainstorms. Post-eruptive lahar occurs during several years after an eruption. At Merapi, lahars are commonly rain-triggered by rainfalls having an average intensity of about 40 mm in 2 hours. Most occur during the rainy season from November to April. Non-eruptive lahars are flows generated without eruptive activity, particularly in the case of a debris avalanche or a lake outburst (e.g., Kelut. A lahar may include one or more discrete flow processes and encompass a variety of rheological flow types and flow transformations. As such, lahars encompass a continuum between debris flows and hyperconcentrated flows, as observed at Merapi, Kelut and Semeru volcanoes. Debris flows, with water contents ranging from 10 to no more than about 25% weight, are non-newtonian fluids that move as fairly coherent masses in what is thought to be predominantly laminar fashion. However, the relative importance of laminar versus turbulent regime is

  18. Geochemical Features and Formation of the Auriferous Cherts in the Mojiang Gold Deposit, Yunnan

    Institute of Scientific and Technical Information of China (English)

    应汉龙; 蔡新平; 刘秉光

    2001-01-01

    Auriferous cherts in the Middle Carboniferous Jinchang Formation are the dominant host rocks of auriferous quartz veins and mixed orebodies comprised of gold-bearing quartz veins and cherts in the Mojiang gold deposit. The rocks exhibit sedimentary texture and structure and are composed of hot-water deposited minerals.The FeO, Fe2O3, Au and Ag contents of the auriferous cherts are high; the Cr, Ni and Cotonrents are also high but significantly vari able; MnO/TiO2 and TFe/TiO2 ratios are relatively high. As viewed from a few diagrams that distinguish different chert formations, the auriferous cherts are in or near the range of hot-wa ter deposited cherts. Because the correlation coefficients between Au contents and those of CrNi of the rocks are negative, a great Au amount in the cherts might not be brought about by later hydrothermal alterations. The rare-earth elements, O and Si isotopic compositions of the auriferous cherts demonstrate that the cherts belong to hot-water deposited rocks. The later hydrothermal alterations made the petrochemical compositions of the cherts deviate from the characteristics of hot-water deposition. In general, the geological and geochemical features of the auriferous cherts demonstrate that the rocks were formed by hot water deposition.

  19. Factors controlling deposits in recovery boilers -particle formation and deposition; Soodakattilan likaantuminen ja siihen vaikuttavien tekijoeiden hallinta. Hiukkasten muodostuminen ja depositio

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E.I.; Mikkanen, P.; Tapper, U.; Ylaetalo, S.; Jaervinen, R. [VTT Chemical Technology, Espoo (Finland); Jokiniemi, J.K.; Pyykoenen, J.; Eskola, A. [VTT Energy, Espoo (Finland)

    1997-10-01

    In this project the aim is to find critical factors controlling the deposit formation in the recovery boilers. Focus is on particle formation, growth and deposition. During year 1995 the aerosol particle formation was studied by an experimental study within the recovery boiler furnace and by a sensitivity study with the ABC (Aerosol Behaviour in Combustion) computer code. During year 1996 the experimental studies on the aerosol particle formation continued within the furnace and the deposition mechanisms for carry over particles were included in the ABC code and sensitivity studies of the deposition were carried out. The experimental study confirmed the fact that the particles are already formed in the recovery boiler furnace. The particle formation is initiated in the boundary layer of the burning droplet or char bed, where metals are vaporised and oxidised to form tiny seed particles

  20. Impact of Macro-economic Factors on Deposit Formation by Ukrainian Population

    Directory of Open Access Journals (Sweden)

    Shevaldina Valentyna H.

    2014-01-01

    Full Text Available The goal of the article is detection of interconnections between the common economic processes and formation of bank deposits by population. The article builds a correlation and regression model of complex assessment of interconnection between macro-economic factors, savings behaviour of population and level of deposits of population in banks for two hour horizons: short-term, which is characterised with deployment of crisis phenomena both in global economy and in Ukrainian economy and the medium-term one. The article characterises the most significant common macro-economic factors. In the result of the study the article establishes that Ukrainian population is oriented at short-term horizon when forming savings due to the uncertainty in future. In the medium-term prospective, savings of the population are formed basically under influence of macro-economic factors, while formation of deposits by Ukrainian population is mostly influenced by socio-psychological factors.

  1. Mechanism of the formation of metal nanoclusters during pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Pushkin, M.A. [Moscow Engineering Physics Institute, 31 Kashirskoe chausse, 115409 Moscow (Russian Federation); Lebid' ko, V.V. [Moscow Engineering Physics Institute, 31 Kashirskoe chausse, 115409 Moscow (Russian Federation); Borman, V.D. [Moscow Engineering Physics Institute, 31 Kashirskoe chausse, 115409 Moscow (Russian Federation); Tronin, V.N. [Moscow Engineering Physics Institute, 31 Kashirskoe chausse, 115409 Moscow (Russian Federation); Troyan, V.I. [Moscow Engineering Physics Institute, 31 Kashirskoe chausse, 115409 Moscow (Russian Federation); Smurov, I. [Ecole Nationale d' Ingenieurs de Saint Etienne, 58 rue Jean Parot, 42023 St-Etienne (France)]. E-mail: smurov@enise.fr

    2006-04-30

    The geometrical structure of Au, Ni, Co and Cr nanoclusters self-assembled on NaCl and HOPG surfaces under pulsed laser deposition (PLD) has been experimentally investigated. The PLD technique is characterized by an extremely high instantaneous deposition rate. Unlike for the thermal evaporation (TE) process, formation of fractal nanoclusters under PLD conditions has been observed with scanning tunneling microscopy (STM). The driving mechanism for this phenomenon occurring at high deposition rate is thought to be the evolution of the initial interacting-adatom states in a system far from thermodynamic equilibrium. The obtained results can be explained by proposing a new mechanism of condensed phase formation under the conditions of strong deviation from thermodynamic equilibrium.

  2. Adsorption of Thiourea and Formation of Nickel-thiourea Complexes at Initial Stage of Nickel Deposition

    Institute of Scientific and Technical Information of China (English)

    HU Guang-hui; WU Hui-huang; YANG Fang-zu; LIU Xin-yu

    2004-01-01

    The effect of thiourea(TU) on the nickel deposition process was analyzed by means of linear-sweep voltammetry. Raman spectroscopy and infrared reflectance spectroscopy were used to investigate the adsorption of TU and the formation of nickel-TU complexes on copper surface. The experimental results indicate that the nucleation and the preceding conversion step are involved in the deposition of nickel on copper electrodes. TU makes the onset nucleation potential negative due to the formation of nickel-TU complexes, which can accelerate the nickel deposition. Moreover, the S atom in the TU molecule adsorbed on copper surface facilitates the coordination of TU to Ni2+. Meanwhile, TU might be adsorbed at a flatter orientation if no Ni2+ is on the surface, while at a perpendicular orientation when Ni2+ is coadsorbed.

  3. Thin Film Formation of Gallium Nitride Using Plasma-Sputter Deposition Technique

    Directory of Open Access Journals (Sweden)

    R. Flauta

    2003-06-01

    Full Text Available The formation of gallium nitride (GaN thin film using plasma-sputter deposition technique has beenconfirmed. The GaN film deposited on a glass substrate at an optimum plasma condition has shown x-raydiffraction (XRD peaks at angles corresponding to that of (002 and (101 reflections of GaN. The remainingmaterial on the sputtering target exhibited XRD reflections corresponding to that of bulk GaN powder. Toimprove the system’s base pressure, a new UHV compatible system is being developed to minimize theimpurities in residual gases during deposition. The sputtering target configuration was altered to allow themonitoring of target temperature using a molybdenum (Mo holder, which is more stable against Gaamalgam formation than stainless steel.

  4. The Kongsberg silver deposits, Norway: Ag-Hg-Sb mineralization and constraints for the formation of the deposits

    Science.gov (United States)

    Kotková, Jana; Kullerud, Kåre; Šrein, Vladimír; Drábek, Milan; Škoda, Radek

    2017-07-01

    The Kongsberg silver district has been investigated by microscopy and electron microprobe analysis, focusing primarily on the Ag-Hg-Sb mineralization within the context of the updated mineral paragenesis. The earliest mineralization stage is represented by sulfides, including acanthite, and sulfosalts. Native silver formed initially through breakdown of early Ag-bearing phases and later through influx of additional Ag-bearing fluids and silver remobilization. The first two generations of native silver were separated in time by the formation of Ni-Co-Fe sulfarsenides and the monoarsenide niccolite along rims of silver crystals. The presence of As-free sulfosalts and the absence of di- and tri-arsenides suggest a lower arsenic/sulfur activity ratio for the Kongsberg deposits compared to other five-element deposits. Native silver shows binary Ag-Hg and Ag-Sb solid solutions, in contrast to the ternary Ag-Hg-Sb compositions typical for other deposits of similar type. Antimonial silver together with allargentum, dyscrasite, and pyrargyrite was documented exclusively from the northern area of the district. Elsewhere, the only Sb-bearing minerals are polybasite and tetrahedrite/freibergite. Hg-rich silver (up to 21 wt% Hg) has been documented only in the central-western area. Myrmekite of freibergite and chalcopyrite reflects exsolution from an original Ag-poor tetrahedrite upon cooling, while myrmekite of pyrite and silver, forming through breakdown of low-temperature phases (argentopyrite or lenaite) upon heating, characterizes the Kongsberg silver district. Based on the stabilities of minerals and mineral assemblages, the formation of the silver mineralization can be constrained to temperatures between 180 and 250 °C.

  5. The roles of organic matter in the formation of uranium deposits in sedimentary rocks

    Science.gov (United States)

    Spirakis, C.S.

    1996-01-01

    Because reduced uranium species have a much smaller solubility than oxidized uranium species and because of the strong association of organic matter (a powerful reductant) with many uranium ores, reduction has long been considered to be the precipitation mechanism for many types of uranium deposits. Organic matter may also be involved in the alterations in and around tabular uranium deposits, including dolomite precipitation, formation of silicified layers, iron-titanium oxide destruction, dissolution of quartz grains, and precipitation of clay minerals. The diagenetic processes that produced these alterations also consumed organic matter. Consequently, those tabular deposits that underwent the more advanced stages of diagenesis, including methanogenesis and organic acid generation, display the greatest range of alterations and contain the smallest amount of organic matter. Because of certain similarities between tabular uranium deposits and Precambrian unconformity-related deposits, some of the same processes might have been involved in the genesis of Precambrian unconformity-related deposits. Hydrologic studies place important constraints on genetic models of various types of uranium deposits. In roll-front deposits, oxidized waters carried uranium to reductants (organic matter and pyrite derived from sulfate reduction by organic matter). After these reductants were oxidized at any point in the host sandstone, uranium minerals were reoxidized and transported further down the flow path to react with additional reductants. In this manner, the uranium ore migrated through the sandstone at a rate slower than the mineralizing ground water. In the case of tabular uranium deposits, the recharge of surface water into the ground water during flooding of lakes carried soluble humic material to the water table or to an interface where humate precipitated in tabular layers. These humate layers then established the chemical conditions for mineralization and related

  6. Dynamics of Perceived Parenting and Identity Formation in Late Adolescence

    Science.gov (United States)

    Beyers, Wim; Goossens, Luc

    2008-01-01

    Identity formation is a dynamic process of person-context interactions, and part of this context are parents, even in late adolescence. Several theories on parent-adolescent relationships share the idea that parents influence the process of identity formation. However, up to now, empirical evidence, particularly longitudinal evidence for this link…

  7. A dynamical system of deposit and loan volumes based on the Lotka-Volterra model

    Science.gov (United States)

    Sumarti, N.; Nurfitriyana, R.; Nurwenda, W.

    2014-02-01

    In this research, we proposed a dynamical system of deposit and loan volumes of a bank using a predator-prey paradigm, where the predator is loan volumes, and the prey is deposit volumes. The existence of loan depends on the existence of deposit because the bank will allocate the loan volume from a portion of the deposit volume. The dynamical systems have been constructed are a simple model, a model with Michaelis-Menten Response and a model with the Reserve Requirement. Equilibria of the systems are analysed whether they are stable or unstable based on their linearised system.

  8. Minerogenic System of Magnesian Nonmetallic Deposits in Early Proterozoic Mg-rich Carbonate Formations in Eastern Liaoning Province

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the early Proterozoic the Liryu Formation and Dashiqiao Formation of eastern Liaoning province, China, there are distributed Mg-rich carbonate rock formations, in which large to superlarge deposits of boron, magnesite, talc, Xiuyan jade etc. occur. The formation of these magnesian nonmetallic deposits was related to early Proterozoic evaporates; then these deposits underwent reworking of regional metamorphism and hydrothermal metasomatism during the Lüliang orogeny and tectono-magmatism during the Indosinian-Yanshanian. Among other things, the Mg-rich carbonates formations, minerogenetic structures and ore-forming fluids played a controlling role in the formation of the mineral deposits. The refore, it can be concluded that the mineral deposits are products of combined processes of the coupling of ore source field, fluid field, thermal field (energy field) and stress field under certain time-space conditions in the early Proterozoic and the late-stage superimposed reworking of tectono-magmatism.

  9. Domanik deposits in Volga-Ural basin: Structure and formation conditions

    Science.gov (United States)

    Zavialova, Anna; Chupahina, Vitaliya; Stupakova, Antonina; Suslova, Anna

    2017-04-01

    The high-carbon Domanic deposits within a Mukhano-Erohovsky trough in Volga-Ural Basin was analyzed from materials of the well cores in the region. Detailed macroscopic description of the cores was provided based on samples and thin sections. In this way, the composition, structure, conditions of sedimentation of high-carbon formation, reservoir properties of rocks, and their distributions in the sections were identified. It was concluded that the Volga-Ural basin is a pre-Ural foreland basin where Domanic siliceous carbonate shale formation formed during the peak of Late Devonian transgression. Domanic rich organic formation of Upper Devonian - Lower Carboniferous age is represented by clay-siliceous-carbonate and clean calcareous and siliceous rocks. These rocks formed in a calm sea basin with environments of shallow shelf, intrashelf depressions and their slopes. The most organic-rich deposits were accumulated in the central parts of the depression uncompensated by sediments.

  10. Quasi-satellite dynamics in formation flight

    CERN Document Server

    Mikkola, Seppo

    2016-01-01

    The quasi-satellite (QS) phenomenon makes two celestial bodies to fly near each other (Mikkola et al. 2006) and that effect can be used also to make artificial satellites move in tandem. We consider formation flight of two or three satellites in low eccentricity near Earth orbits. With the help of weak ion thrusters it is possible to accomplish tandem flight. With ion thrusters it is also possible to mimic many kinds of mutual force laws between the satellites. We found that both a constant repulsive force or an attractive force that decreases with the distance are able to preserve the formation in which the eccentricities cause the actual relative motion and the weak thrusters keep the mean longitude difference small. Initial values are important for the formation flight but very exact adjustment of orbital elements is not important. Simplicity is one of our goals in this study and this result is achieved at least in the way that, when constant force thrusters are used, the satellites only need to detect the...

  11. Formation conditions of high-grade gold-silver ore of epithermal Tikhoe deposit, Russian Northeast

    Science.gov (United States)

    Volkov, A. V.; Kolova, E. E.; Savva, N. E.; Sidorov, A. A.; Prokof'ev, V. Yu.; Ali, A. A.

    2016-09-01

    The Tikhoe epithermal deposit is located in the Okhotsk-Chukotka volcanic belt (OChVB) 250 km northeast of Magadan. Like other deposits belonging to the Ivan'insky volcanic-plutonic depression (VTD), the Tikhoe deposit is characterized by high-grade Au-Ag ore with an average Au grade of 23.13 gpt Au and Au/Ag ratio varying from 1: 1 to 1: 10. The detailed explored Tikhoe-1 orebody is accompanied by a thick (20 m) aureole of argillic alteration. Pyrite is predominant among ore minerals; galena, arsenopyrite, sphalerite, Ag sulfosalts, fahlore, electrum, and küstelite are less abundant. The ore is characterized by abundant Sebearing minerals. Cu-As geochemical specialization is noted for silver minerals. Elevated Se and Fe molar fractions of the main ore minerals are caused by their formation in the near-surface argillic alteration zone. The veins and veinlets of the Tikhoe-1 ore zone formed stepwise at a temperature of 230 to 105°C from Nachloride solution enriched in Mg and Ca cations with increasing salinity. The parameters of the ore-forming fluid correspond to those of epithermal low-sulfidation deposits and assume the formation of high-grade ore under a screening unit of volcanic rocks. In general, the composition of the ore-forming fluid fits the mineralogy and geochemistry of ore at this deposit. The similarity of the ore composition and parameters of the ore-forming fluid between the Tikhoe and Julietta deposits is noteworthy. Meanwhile, differences are mainly related to the lower temperature and fluid salinity at the Julietta deposit with respect to the Tikhoe deposit. The fluid at the Julietta deposit is depleted in most components compared with that at the Tikhoe deposit except for Sb, Cd, and Ag. The results testify to a different erosion level at the deposits as derivatives of the same ore-forming system. The large scale of the latter allows us to predict the discovery of new high-grade objects, including hidden mineralization, which is not exposed at

  12. Formation of a Hydrothermal Kaolinite Deposit from Rhyolitic Tuff in Jiangxi, China

    Institute of Scientific and Technical Information of China (English)

    Ye Yuan; Guanghai Shi; Mengchu Yang; Yinuo Wu; Zhaochong Zhang; Anjie Huang; Jiajing Zhang

    2014-01-01

    The Longmen kaolinite deposit is one of the largest hydrothermal clay deposits of Ganxi volcanic basin (northern Wuyi Mountain area, China). The pristine host rocks are rhyolitic crystal-vitric tuff and minor lapilli tuff from the Late Jurassic Ehuling Formation. The ore consists of kaolin-group minerals (kaolinite, dickite), pyrophyllite with minor quartz, sericite, pyrite, etc.. From the host rocks to the transition zones (altered rocks) then to the vein ores, contents of SiO2 and TFe2O3 decrease, whereas Al2O3 and LOI increase, consistent with the contents increase of kaolin minerals and pyrophyllite in the samples. The total REE abundances of the ores are much lower than that of the host and altered rocks, Rb, Nb, Nd, Zr, Ti and Y are significantly depleted. Apparent zoning features of bulk geochemistry and mineral component reflect that the kaolinite deposit occurred at the expense of the host rock by ascending hydrothermal fluids with distinct removal of SiO2, TFe2O3, Na2O, K2O. According to the mineral assemblage, the formation temperature of this deposit falls within the range of 270-350 ℃. With regard to the industrial applications, the kaolinized ores are suitable for use in ceramics and gemologic materials crafted for seal stones. Moreover, in mineralogical terms, this deposit is also proved to be an excellent example for studying channeled hydrothermal alterations of rhyolitic tuff.

  13. Coarse grain deposit feature of Guantao formation in western depression Shuyi area of Liaohe basin

    Institute of Scientific and Technical Information of China (English)

    GUO Jian-hua; LIU Chen-sheng; ZHU Mei-heng

    2005-01-01

    The extensive distribution of coarse-grained clastic rock of Guantao formation in Shuyi area of Liaohe basin was considered as a result of fluvial deposit. According to the comprehensive analysis of seism data, well log, core observation and experimental data, this kind of clastic rock is composed of pebblestone-cobblestone, microconglomerate, sand conglomerate, medium-coarse grained sandstone and fine-sandstone. According to the clast composition, sedimentary texture, structure and rock type, 3 kinds of sediment facies can be recognized ie the mixed accumulation-conglomerate dominated debris flow, pebblestone-cobblestone dominated gradient flow and sandstone dominated braided stream. Vertically, the bottom gradient current deposit and top braided stream deposit form fining-upward sediment sequence, and the debris flow deposit distributes in them at random. The sedimentary feature of coarse grain clastic of Guantao formation in Shuyi area is accordant with proximal wet alluvial fan deposited in wet climate at foreland and this kind of alluvial fan is different from the traditional one.

  14. Dynamics of optically excited tungsten and silicon for ripples formation

    Science.gov (United States)

    Zhang, Hao; Li, Chen; Colombier, Jean-Philippe; Cheng, Guanghua; Stoian, Razvan

    2015-03-01

    We measured the dielectric constant of optically excited silicon and tungsten using a dual-angle femtosecond reflectivity pump-probe technique. The energy deposition in the formation of laser-induced periodic surface structures (LIPSS) is then investigated by simulating the laser pulse interaction with an initially random distributed rough surface using 3D-Finite Difference Time Domain (FDTD) method, with the measured dielectric constant as a material input. We found in the FDTD simulation periodic energy deposition patterns both perpendicular and parallel to the laser polarization. The origin of them are discussed for originally plasmonic and non-plasmonic material.

  15. Formation of fine sediment deposit from a flash flood river in the Mediterranean Sea

    Science.gov (United States)

    Grifoll, Manel; Gracia, Vicenç; Aretxabaleta, Alfredo L.; Guillén, Jorge; Espino, Manuel; Warner, John C.

    2014-01-01

    We identify the mechanisms controlling fine deposits on the inner-shelf in front of the Besòs River, in the northwestern Mediterranean Sea. This river is characterized by a flash flood regime discharging large amounts of water (more than 20 times the mean water discharge) and sediment in very short periods lasting from hours to few days. Numerical model output was compared with bottom sediment observations and used to characterize the multiple spatial and temporal scales involved in offshore sediment deposit formation. A high-resolution (50 m grid size) coupled hydrodynamic-wave-sediment transport model was applied to the initial stages of the sediment dispersal after a storm-related flood event. After the flood, sediment accumulation was predominantly confined to an area near the coastline as a result of preferential deposition during the final stage of the storm. Subsequent reworking occurred due to wave-induced bottom shear stress that resuspended fine materials, with seaward flow exporting them toward the midshelf. Wave characteristics, sediment availability, and shelf circulation determined the transport after the reworking and the final sediment deposition location. One year simulations of the regional area revealed a prevalent southwestward average flow with increased intensity downstream. The circulation pattern was consistent with the observed fine deposit depocenter being shifted southward from the river mouth. At the southern edge, bathymetry controlled the fine deposition by inducing near-bottom flow convergence enhancing bottom shear stress. According to the short-term and long-term analyses, a seasonal pattern in the fine deposit formation is expected.

  16. Singular deposit formation in PWR due to electrokinetic phenomena - application to SG clogging

    Energy Technology Data Exchange (ETDEWEB)

    Guillodo, M.; Muller, T.; Barale, M.; Foucault, M. [AREVA NP SAS, Technical Centre (France); Clinard, M.-H.; Brun, C.; Chahma, F. [AREVA NP SAS, Chemistry and Radiochemistry Group (France); Corredera, G.; De Bouvier, O. [Electricite de France, Centre d' Expertise de I' inspection dans les domaines de la Realisation et de l' Exploitation (France)

    2009-07-01

    The deposits which cause clogging of the 'foils' of the tube support plates (TSP) in Steam Generators (SG) of PWR present two characteristics which put forward that the mechanism at the origin of their formation is different from the mechanism that drives the formation of homogeneous deposits leading to the fouling of the free spans of SG tubes. Clogging occurs near the leading edge of the TSP and the deposits appear as diaphragms localized between both TSP and SG tubing materials, while the major part of the tube/TSP interstice presents little or no significant clogging. This type of deposit seems rather comparable to the ones which were reproduced in Lab tests to explain the flow rate instabilities observed on a French unit during hot shutdown in the 90's. The deposits which cause TSP clogging are owed to a discontinuity of the streaming currents in the vicinity of a surface singularity (orifices, scratches ...) which, in very low conductivity environment, produce local potential variations and/or current loop in the metallic pipe material due to electrokinetic effects. Deposits can be built by two mechanisms which may or not coexist: (i) accumulation of particles stabilized by an electrostatic attraction due to the local variation of electrokinetic potential, and (ii) crystalline growth of magnetite produced by the oxidation of ferrous ions on the anodic branch of a current loop. Lab investigations carried out by AREVA NP Technical Centre since the end of the 90's showed that this type of deposit occurs when the redox potential is higher than a critical value, and can be gradually dissolved when the potential becomes lower than this value which depends on the 'Material - Chemistry' couple. Special emphasis will be given in this paper to the TSP clogging of SG in PWR secondary coolant dealing particularly with the potential strong effect of electrokinetic phenomena in low conductive environment and in high temperature conditions

  17. Hamiltonian Dynamics of Protein Filament Formation.

    Science.gov (United States)

    Michaels, Thomas C T; Cohen, Samuel I A; Vendruscolo, Michele; Dobson, Christopher M; Knowles, Tuomas P J

    2016-01-22

    We establish the Hamiltonian structure of the rate equations describing the formation of protein filaments. We then show that this formalism provides a unified view of the behavior of a range of biological self-assembling systems as diverse as actin, prions, and amyloidogenic polypeptides. We further demonstrate that the time-translation symmetry of the resulting Hamiltonian leads to previously unsuggested conservation laws that connect the number and mass concentrations of fibrils and allow linear growth phenomena to be equated with autocatalytic growth processes. We finally show how these results reveal simple rate laws that provide the basis for interpreting experimental data in terms of specific mechanisms controlling the proliferation of fibrils.

  18. The influence of nanoparticle aggregation on formation of ZrO{sub 2} electrolyte thin films by electrophoretic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kalinina, E.G., E-mail: kalinina@iep.uran.ru [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 106 Amundsen Street, 620016 Ekaterinburg (Russian Federation); Ural Federal University, 19 Mira Street, 620002 Ekaterinburg (Russian Federation); Efimov, A.A. [Moscow Institute of Physics and Technology, 9 Institutskii per., 141700 Dolgoprudny, Moscow Region (Russian Federation); Safronov, A.P. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 106 Amundsen Street, 620016 Ekaterinburg (Russian Federation); Ural Federal University, 19 Mira Street, 620002 Ekaterinburg (Russian Federation)

    2016-08-01

    The paper presents the results of the studies of electrically stabilized nonaqueous suspensions of ZrO{sub 2} stabilized by Y{sub 2}O{sub 3} (YSZ) nanoparticles with an average diameter of 11 nm for the formation of green films of electrolyte for solid oxide fuel cells. Nanoparticles were de-aggregated to different degrees, which were provided by the ultrasonic treatment and the centrifugation, and monitored by the dynamic light scattering. YSZ green thin films were obtained by the electrophoretic deposition (EPD) on dense lanthanum strontium manganite cathodes using suspensions with the average diameter of aggregates: 107; 66; 53 nm. To investigate the possibilities of EPD we used the model drying of the same suspensions cast upon the same substrates. It was shown that the structure and the morphology of the green films obtained by EPD was different compared to the films prepared by the model drying of the suspension. The drying of the stable suspension resulted in the formation of loose aggregates on the surface. The efficient packing of electrically stabilized particles was prevented by the forces of electrostatic repulsion between them. In the case of EPD the electrocoagulation of particles near the cathode takes place with the formation of dense aggregates. As a result, uncharged spherical aggregates with an average size of about 100–200 nm settle on the surface of the cathode and pack into a uniform dense coating suitable for the subsequent sintering of a gas-tight coating for the solid YSZ electrolyte. - Highlights: • Impact of nanoparticle aggregation on the electrophoretic deposition is studied. • Sedimentation of stabilized particles results in formation of loose aggregates. • The formation of dense layer is facilitated by electrocoagulation of particles.

  19. Linking sulfate and phyllosilicate formation at Mawrth Vallis: Weathering in ancient low-latitude ice deposits

    Science.gov (United States)

    Niles, P. B.; Michalski, J.

    2009-12-01

    system leaching of rocks in the uppermost part of the stratigraphic section to form Al-rich clay minerals, and alteration of the materials to Fe/Mg-rich clay minerals in the deeper section, where groundwater saturation persisted and/or reducing conditions prevailed. While the ages of the phyllosilicate deposits and sulfate deposits are generally considered to be different, this model suggests that the age of the alteration events that formed the sulfate minerals and the phyllosilicate deposits would be equivalent. It is because of later episodes of physical reworking that the age of the sulfate-rich sedimentary rocks would appear to be younger. Therefore, this model may provide a consistent explanation for the formation of sulfate-rich and phyllosilicate-rich sediments early in Mars’ history.

  20. Spectral characteristics of banded iron formations in Singhbhum craton, eastern India: Implications for hematite deposits on Mars

    OpenAIRE

    Singh, Mahima; Singhal, Jayant; K.arun Prasad; Rajesh, V.J.; Ray, Dwijesh; Sahoo, Priyadarshi

    2016-01-01

    Banded iron formations (BIFs) are major rock units having hematite layers intermittent with silica rich layers and formed by sedimentary processes during late Archean to mid Proterozoic time. In terrestrial environment, hematite deposits are mainly found associated with banded iron formations. The BIFs in Lake Superior (Canada) and Carajas (Brazil) have been studied by planetary scientists to trace the evolution of hematite deposits on Mars. Hematite deposits are extensively identified in Mer...

  1. Formation of β-FeSi 2 thin films by partially ionized vapor deposition

    Science.gov (United States)

    Harada, Noriyuki; Takai, Hiroshi

    2003-05-01

    The partially ionized vapor deposition (PIVD) is proposed as a new method to realize low temperature formation of β-FeSi 2 thin films. In this method, Fe is evaporated by E-gun and a few percents of Fe atoms are ionized. We have investigated influences of the ion content and the accelerating voltage of Fe ions on the structural properties of β-FeSi 2 films deposited on Si substrates. It was confirmed that β-FeSi 2 can be formed on Si(1 0 0) substrate by PIVD even at substrate temperature as low as 350, while FeSi by the conventional vacuum deposition. It was concluded that the influence of Fe ions on preferential orientation of β-FeSi 2 depends strongly on the content and the acceleration energy of ions.

  2. Depositional Architecture of Late Cambrian-Early Ordovician Siliciclastic Barik Formation; Al Huqf Area, Oman

    Science.gov (United States)

    Abbasi, Iftikhar Ahmed

    2017-04-01

    Early Paleozoic siliciclastics sediments of the Haima Supergroup are subdivided into a number of formations and members based on lithological characteristics of various rock sequences. One of the distinct sandstone sequence, the Barik Formation (Late Cambrian-Early Ordovician) of the Andam Group is a major deep gas reservoir in central Oman. The sandstone bodies are prospective reservoir rocks while thick shale and clay interbeds act as effective seal. Part of the Barik Formation (lower and middle part) is exposed in isolated outcrops in Al Huqf area as interbedded multistoried sandstone, and green and red shale. The sandstone bodies are up to 2 meters thick and can be traced laterally for 300 m to over 1 km. Most of sandstone bodies show both lateral and vertical stacking. Two types of sandstone lithofacies are identified on the basis of field characteristics; a plane-bedded sandstone lithofacies capping thick red and green color shale beds, and a cross-bedded sandstone lithofacies overlying the plane-bedded sandstone defining coarsening upward sequences. The plane-bedded sandstone at places contains Cruziana ichnofacies and bivalve fragments indicating deposition by shoreface processes. Thick cross-bedded sandstone is interpreted to be deposited by the fluvial dominated deltaic processes. Load-casts, climbing ripples and flaser-bedding in siltstone and red shale indicate influence of tidal processes at times during the deposition of the formation. This paper summarizes results of a study carried out in Al Huqf area outcrops to analyze the characteristics of the sandstone-body geometry, internal architecture, provenance and diagenetic changes in the lower and middle part of the formation. The study shows build-up of a delta complex and its progradation over a broad, low-angle shelf where fluvial processes operate beside shoreface processes in a vegetation free setting. Keywords: Andam Group, Barik Formation, Ordovician sandstone, Al Huqf, Central Oman,

  3. Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.

  4. GRAVITY-FLOW DEPOSITS IN THE TOARCIAN PERBLA FORMATION (SLOVENIAN BASIN, NW SLOVENIA

    Directory of Open Access Journals (Sweden)

    BOSTJAN ROZIC

    2011-07-01

    Full Text Available The Perbla Formation represents typical Toarcian clay-rich pelagic sediment of the southern Tethyan passive continental margin. It was deposited in the Slovenian Basin, located in present-day western Slovenia. During the Early Jurassic the basin was surrounded by the Dinaric (Friuli Carbonate Platform to the south and by the Julian Carbonate Platform to the north. Today, the transitional areas between the platforms and basin are not preserved due to intense Cainozoic thrusting and erosion, with the only record of the evolution of these areas stored in gravity-flow deposits of the Perbla Formation. Coarser turbidites were deposited on the margins of the basin, with other types of gravity-flow deposits, observed mainly in the central part of the basin. These intercalations reflect regionally recognized events that characterized the sedimentary evolution of western Slovenia at the end of the Early Jurassic. Slumps that occasionally developed into debris-flows reflect uneven sea-bottom palaeotopography that originated during a pre- to early-Toarcian phase of accelerated subsidence. The early Toarcian transgression caused drowning of the adjacent carbonate platforms, an event reflected in the composition of coarser turbidites which consist almost exclusively of echinoderm fragments and thin-shelled bivalves. These turbidites originated from drowned platform margins and/or slopes and were subsequently redeposited in proximal parts of the basin. 

  5. Formation Mechanism and Stability Assessment of the Colluvial Deposit Slope in Zuoyituo

    Institute of Scientific and Technical Information of China (English)

    Jian Wenxing; Zhang Yihu; Yin Hongmei

    2004-01-01

    The basic features of the colluvial deposit slope in Zuoyituo such as geological conditions, dimensions, slip surfaces and groundwater conditions are described concisely in this paper. The formation mechanism of the slope is discussed. It is considered that the formation of the colluvial deposit slope in Zuoyituo has undergone accumulation, slip, load, deformation and failure. The effects of rainfall on slope stability are categorized systematically based on existing methodology, and ways to determine the effects quantitatively are presented. The remained slip force method is improved by the addition of quantitative relations to the existing formulae and programs. The parameters of the colluvial deposit slope are determined through experimentation and the method of back-analysis. The safety factors of the slope are calculated with the improved remained slip force method and the Sarma method. The results show that rainfall and water level in the Yangtze River have a significant effect on the stability of the colluvial deposit slope in Zuoyituo. The hazards caused by the instability of the slope are assessed, and prevention methods are put forward.

  6. Complexity of gold nanoparticle formation disclosed by dynamics study

    DEFF Research Database (Denmark)

    Engelbrekt, Christian; Jensen, Palle Skovhus; Sørensen, Karsten

    2013-01-01

    Although chemically synthesized gold nanoparticles (AuNPs) from gold salt (HAuCl4) are among the most studied nanomaterials, understanding the formation mechanisms is a challenge mainly due to limited dynamics information. A range of in situ methods with down to millisecond (ms) time resolution...... have been employed in the present report to monitor time-dependent physical and chemical properties in aqueous solution during the chemical synthesis. Chemical synthesis of AuNPs is a reduction process accompanied by release of ions and protons, and formation of solid particles. Dynamic information......]- to form Au atoms during the early stage of the synthesis process. pH- and conductivity-dynamics point further clearly to formation of coating layers on AuNPs and adsorbate exchange between MES and starch. © 2013 American Chemical Society....

  7. Kinetics of Hydrocarbon formation in a-C:H film deposition plasmas

    Energy Technology Data Exchange (ETDEWEB)

    De la Cal, E.; Tabares, F.L.

    1993-07-01

    The formation of C{sub 2} and C{sub 3} hydrocarbons during the PACVD of a-C-H films from admixtures of methane with H{sub 2} and He has been investigated by mass espectrometry under several deposition condition. The time evolution of the observed species indicates that the formation mechanism of ethylene and acetylene are sensitive to the conditions of the wall during the growing of the film. Acetylene are sensitive to the conditions of the wall during the growing of the carburized metal. (Author)

  8. Small scale analogs of the Cayley Formation and Descarts Mountains in impact associated deposits, part C

    Science.gov (United States)

    Head, J. W.

    1972-01-01

    The exploration of the Cayley Formation and material of the Descartes Mountains and an understanding of the origin and evolution of these units were primary objectives of the Apollo 16 lunar mission. This section examines several areas associated with impact crater deposits that show small-scale features similar in morphology to the regional characteristics of the Cayley and Descartes units shown in the Apollo 16 photography.

  9. Nitrogen Deposition Effects on Soil Carbon Dynamics in Temperate Forests

    DEFF Research Database (Denmark)

    Ginzburg Ozeri, Shimon

    Soils contain the largest fraction of terrestrial carbon (C). Understanding the factors regulating the decomposition and storage of soil organic matter (SOM) is essential for predictions of the C sink strength of the terrestrial environment in the light of global change. Elevated long-term nitrogen...... (N) deposition into forest ecosystems has been increasing globally and was hypothesized to raise soil organic C (SOC) stocks by increasing forest productivity and by reducing SOM decomposition. Yet, these effects of N deposition on forest SOC stocks are uncertain and largely based on observations...... edges were used to study the effects of varying N deposition load on SOC stocks and fluxes as well as on the temperature sensitivity of SOM respiration. In a third study, the effects of 20 years of continuous experimental N addition (35 kg N ha-1 year-1) on soil C budget were investigated. Our general...

  10. Nitrogen Deposition Effects on Soil Carbon Dynamics in Temperate Forests

    DEFF Research Database (Denmark)

    Ginzburg Ozeri, Shimon

    (N) deposition into forest ecosystems has been increasing globally and was hypothesized to raise soil organic C (SOC) stocks by increasing forest productivity and by reducing SOM decomposition. Yet, these effects of N deposition on forest SOC stocks are uncertain and largely based on observations...... hypotheses were that elevated N deposition will: i) increase SOC stocks owing to positive effect of N on litterfall C inputs combined with negative effect on SOM decomposition regardless of negative effects on belowground C inputs by roots and associated mycorrhiza; ii) reduce the temperature sensitivity......Soils contain the largest fraction of terrestrial carbon (C). Understanding the factors regulating the decomposition and storage of soil organic matter (SOM) is essential for predictions of the C sink strength of the terrestrial environment in the light of global change. Elevated long-term nitrogen...

  11. Effect of impurity deposition layer formation on D retention in LHD plasma exposed W

    Directory of Open Access Journals (Sweden)

    Y. Oya

    2016-12-01

    Full Text Available Effect of carbon based mixed-material deposition layer formation on hydrogen isotope retention was studied. The tungsten (W samples were placed at four different positions, namely PI (sputtering erosion dominated area, DP (deposition dominated area, HL (higher heat load area, and ER (erosion dominated area during 2013 plasma experimental campaign in Large Helical Device (LHD at National Institute for Fusion Science (NIFS, Japan and were exposed to ∼ 4000 shots of hydrogen plasma in a 2013 plasma experimental campaign. Most of the sample surface except for ER was covered by a mixed-material deposition layer formed by plasma experimental campaign, which consisted of carbon, but some metal impurities were contained. For ER sample, He bubbles were formed due to long term He discharge cleaning and He plasma experiments during the plasma experimental campaign. The additional 1keV D2+ implantation was performed to evaluated the D retention enhancement by plasma exposure. It was found that both of H and D retentions were clearly increased. In particular, the H retention was controlled by the thickness of the carbon-dominated mixed-material deposition layer, indicating most of the H was trapped by this mixed-material deposition layer. It is concluded that the accumulation of low-Z mixed-material layer on the surface of the first wall is one of key issues for the determination of hydrogen isotope retention in first wall.

  12. Depositional, diagenetic and stratigraphic aspects of microfacies from Riachuelo Formation, Albian, Sergipe Basin, Brazil

    Directory of Open Access Journals (Sweden)

    Caio Vinícius Gabrig Turbay

    2013-12-01

    Full Text Available The rocks of the Riachuelo Formation, Sergipe Basin, Brazil, represent an example of carbonate sedimentation related to the drift phase during the opening of the South Atlantic Ocean. The Carapeba and Brejo quarries exhibit the best onshore outcrops of the drift carbonate section along the Brazilian continental edge. Field studies and microfacies analysis of the outcropped sedimentary section showed six sedimentary deposits related to the physiography of a carbonate shelf. Proximal mixed deposits are represented by the rich-terrigenous dolostone. Levels with alternate layers of fine grained sandstones and siltstones are here related to distal facies of submarine fans deposits. Mudstones with miliolids and textularids represent a lagoonal environment in a semi-restricted middle shelf. Packstones, grainstones and occasionally wackestones with oncoids, intraclasts and peloids represent sedimentary deposits related to the back of shallow sandy bars and environments at the interface with the lagoon. Grainstones whit ooliths, oncoids, intraclasts and bioclasts, with trough cross-bedding, represent a shallower shoreface environment over the shallow carbonate back on outer shelf. Cements and other post- depositional features suggest four different diagenetic environments: a marine phreatic diagenetic environment with active water circulation; b marine phreatic diagenetic environment with stagnant water; c freshwater phreatic diagenetic environment; d burial diagenetic environment. The sedimentary succession is formed by shallowing upward cycles overlain by a possible transgressive surface, which may indicate the passage of a lowstand to a transgressive system tract.

  13. Gas Price Formation, Structure and Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Davoust, R.

    2008-07-01

    Our study, focused on gas prices in importing economies, describes wholesale prices and retail prices, their evolution for the last one or two decades, the economic mechanisms of price formation. While an international market for oil has developed thanks to moderate storage and transportation charges, these costs are much higher in the case of natural gas, which involves that this energy is still traded inside continental markets. There are three regional gas markets around the world: North America (the United States, importing mainly from Canada and Mexico), Europe (importing mainly from Russia, Algeria and Norway) and Asia (Japan, Korea, Taiwan, China and India, importing mainly from Indonesia, Malaysia and Australia). A market for gas has also developed in South America, but it will not be covered by our paper. In Europe and the US, due to large domestic resources and strong grids, natural gas is purchased mostly through pipelines. In Northeast Asia, there is a lack of such infrastructures, so imported gas takes mainly the form of Liquefied Natural Gas (LNG), shipped on maritime tankers. Currently, the LNG market is divided into two zones: the Atlantic Basin (Europe and US) and the Pacific Basin (Asia and the Western Coast of America). For the past few years, the Middle East and Africa have tended to be crucial suppliers for both LNG zones. Gas price formation varies deeply between regional markets, depending on several structural factors (regulation, contracting practises, existence of a spot market, liquidity, share of imports). Empirically, the degree of market opening (which corresponds to the seniority in the liberalization process) seems to be the primary determinant of pricing patterns. North America has the most liberalized and well-performing natural gas industry in the world. Gas pricing is highly competitive and is based on supply/demand balances. Spot and futures markets are developed. The British gas sector is also deregulated and thus follows a

  14. Formation of polygonal fault systems as a result of hydrodynamical instabilities in clay-rich deposits.

    Science.gov (United States)

    Lopez, Teodolina; Antoine, Raphael; Rabinowicz, Michel; Baratoux, David; Darrozes, José; Kurita, Kei; D'Uston, Lionel

    2015-04-01

    Fine grained deposits as chalks and clays are characterised by the development of polygonal fault systems [1]. For the clay-rich deposits, two different environments are associated with their formation. First, on continents, dewatering leads to the development of polygonal desiccation cracks which have a centimetric to metric size [2]. Polygonal faults are also observed in sub-marine sedimentary deposits and here, can reach hectometric to kilometric size [3]. Since the giant polygons develop on basins with no clear evidences of tectonic stresses, the fracturing is attributed to stresses due to horizontal density variations generated during the basin subsidence. Several models have been proposed to explain the formation of the giant polygons and the two main hypotheses are the syneresis (spontaneous horizontal contraction) proposed by [4] and the low coefficient of friction of clay proposed by [5]. However, new understandings in the clay rheology and in the hydrodynamical instabilities, controlling the development of compaction in unconsolidated and consolidated clay deposits, permit us to propose an alternative hypothesis. We consider that the development of giant polygons results from the superposition of hydrodynamical instabilities leading to the formation of (i) mm-size agglomerates of clay particles while the deposit is unconsolidated [6], followed after by the consolidation of this layer, then (ii) hectometric to kilometric compaction spheres develop [7] and (iii) finally ends with the occurrence of hydrothermal and plastic convections. We show that the crucial conditions for the development of hectometric to kilometric size polygonal fault systems are: 1) the high permeability of the clay-rich deposit composed of mm-size agglomerates and 2) the dramatic increase of the strength of the clay as the deposit consolidates. [1] Dewhurst et al., (1999), Mar. Petr. Geol., 16 (8), 793-810. [2] Weinberger (1999), J. Struct. Geol., 21, 379-386. [3] Andresen and Huuse

  15. The Whangaehu Formation: Debris-avalanche and lahar deposits from ancestral Ruapehu volcano, New Zealand

    Science.gov (United States)

    Keigler, Rébecca; Thouret, Jean-Claude; Hodgson, Katherine A.; Neall, Vincent E.; Lecointre, Jérôme A.; Procter, Jonathan N.; Cronin, Shane J.

    2011-10-01

    In the North Island of New Zealand, the andesitic Tongariro Volcanic Centre encompasses the Tongariro complex, the Mt. Ngauruhoe cone, and the country's largest stratovolcano, Mt. Ruapehu. This volcano is surrounded by an equally large volume of Late Quaternary volcaniclastic deposits, forming a circular 'ring plain'. In the southern portions of the ring plain, the Whangaehu Formation provides a critical record of the early Ruapehu activity because such deposits are not preserved on the present Mt. Ruapehu cone. We re-interpret the previously described Whangaehu Formation deposits and their emplacement mechanisms, providing new data to support this through the analysis of key stratigraphic sections, sedimentary structures and features, grain-size distributions, lithologic components, and SEM studies of volcaniclastic material. The Formation in the middle course of the Whangaehu River Valley comprises three principal stratigraphic units representing an estimated volume of c. 1 km 3. The Lower Member comprises a coarse, clast-supported, ungraded, megaclast-rich breccia, with oblique to sub-horizontal fractures indicating that shearing occurred at its base. The Lower Member also contains rip-up clasts from the underlying Tertiary siltstones. An indurated and sheared clast mixture of angular to subangular cobbles and pebbles supports large boulders at the base of the breccias, with fracturing concentrated near the base of this stratum. Pockets of shattered clasts representing monolithological domains, and boulders showing jigsaw fractures indicate collision effects during transportation from source. The breccia is interpreted as a debris-avalanche deposit resulting from a collapse of the southern flank of Ruapehu some time between 180 ka and 45 ka. The Middle Member suggests fluvial reworking of the debris-avalanche deposit interspersed with post-collapse lahar deposits on the ancestral Ruapehu ring plain. The Upper Member reflects an aggradation phase on the southern

  16. Time scales of porphyry Cu deposit formation: insights from titanium diffusion in quartz

    Science.gov (United States)

    Mercer, Celestine N.; Reed, Mark H.; Mercer, Cameron M.

    2015-01-01

    Porphyry dikes and hydrothermal veins from the porphyry Cu-Mo deposit at Butte, Montana, contain multiple generations of quartz that are distinct in scanning electron microscope-cathodoluminescence (SEM-CL) images and in Ti concentrations. A comparison of microprobe trace element profiles and maps to SEM-CL images shows that the concentration of Ti in quartz correlates positively with CL brightness but Al, K, and Fe do not. After calibrating CL brightness in relation to Ti concentration, we use the brightness gradient between different quartz generations as a proxy for Ti gradients that we model to determine time scales of quartz formation and cooling. Model results indicate that time scales of porphyry magma residence are ~1,000s of years and time scales from porphyry quartz phenocryst rim formation to porphyry dike injection and cooling are ~10s of years. Time scales for the formation and cooling of various generations of hydrothermal vein quartz range from 10s to 10,000s of years. These time scales are considerably shorter than the ~0.6 m.y. overall time frame for each porphyry-style mineralization pulse determined from isotopic studies at Butte, Montana. Simple heat conduction models provide a temporal reference point to compare chemical diffusion time scales, and we find that they support short dike and vein formation time scales. We interpret these relatively short time scales to indicate that the Butte porphyry deposit formed by short-lived episodes of hydrofracturing, dike injection, and vein formation, each with discrete thermal pulses, which repeated over the ~3 m.y. generation of the deposit.

  17. Laser energy deposition and its dynamic uniformity for direct-drive capsules

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yan; Wu, SiZhong; Zheng, WuDi [Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)

    2015-04-15

    The total laser energy deposition of multi-laser-beam irradiation is not only associated with the dynamic behavior of capsule but also the time-dependent angular distribution of the energy deposition of each beam around its axis. The dynamic behavior of laser energy deposition does not linearly respond to the dynamic behavior of laser irradiation. The laser energy deposition uniformity determines the symmetry of implosion. The dynamic behavior of laser energy deposition non-uniformity in OMEGA for laser with square beam shape intensity profile is investigated. In the case of smaller laser spot, the initial non-uniformity caused by laser beam overlap is very high. The shell asymmetry caused by the high initial laser irradiation non-uniformity is estimated by the extent of distortion of shock front which is not as severe as expected before the shock driven by main pulse arrives. This suggests that the large initial non-uniformity due to smaller laser spot is one of the elements that seed disturbance before the main pulse. The rms of laser energy deposition during the main pulse remains above 2%. Since the intensity of main driving pulse usually is several times higher than that of picket pulses, the non-uniformity in main pulse period may jeopardize the symmetrical implosion. When dynamic behavior of capsule is considered, the influence of beam pointing error, the target positioning error, and beam-to-beam power unbalance is quite different for the case of static capsule.

  18. Molecular dynamical modelling of endohedral fullerenes formation in plasma

    Science.gov (United States)

    Fedorov, A. S.; Kovaleva, E. A.; Lubkova, T. A.; Popov, Z. I.; Kuzubov, A. A.; Visotin, M. A.; Irle, S.

    2016-02-01

    The initial stages of fullerene and endohedral metallofullerene (EMF) synthesis in carbon-helium plasma at 1500 K and 2500 K have been simulated with quantum chemical molecular dynamics (MD) based on density-functional tight-binding (DFTB). The cases of formation of large (>100 atoms) sp2-carbon clusters with scandium atoms inside were observed. These clusters are considered as precursors of fullerenes or EMFs, and thus it is shown that formation of EMFs can be explained within the framework of "shrinking hot giant" mechanism. Also, the dependence of formation rates on plasma parameters, including temperature, buffer gas and metal atoms concentrations, has been studied.

  19. New evidence of deposition under cold climate for the Xieshuihe Formation of the Nanhua System in northwestern Hunan, China

    Institute of Scientific and Technical Information of China (English)

    FENG Lianjun; CHU Xuelei; ZHANG Qirui; ZHANG Tonggang; LI He; JIANG Neng

    2004-01-01

    Yangjiaping section is located in Hupingshan Town, Shimen County, Hunan Province. The section has been intensively studied since 1980. However, The paleoclimate during the deposition of the Xieshuihe Formation remains controversial. Based on chemical analysis of sedimentary clastic rocks of the unit, the resulting CIA (the chemical index of alteration) values of the Xieshuihe Formation are similar to those of the overlying Gucheng Formation (also called the Dongshanfeng Formation). It indicates that the sedimentary rocks of the Xieshuihe Formation and Gucheng Formation underwent the similar degrees of chemical weathering before deposition. Therefore, the Xieshuihe Formation was also likely to be deposited under a cold climatic condition, which probably belongs to a part of the record of glaciations.

  20. Comparison of conversion and deposit formation of ethanol and butane under SOFC conditions

    Science.gov (United States)

    Gupta, Gaurav K.; Dean, Anthony M.; Ahn, Kipyung; Gorte, Raymond J.

    This paper explores the gas-phase kinetics of butane and ethanol conversion as well as the propensity for molecular-weight growth and deposit formation in the non-catalytic regions of a solid oxide fuel cell (SOFC). Experiments are done where the fuel flows through a quartz reactor heated by a furnace. The primary observables are the extent of fuel conversion and the amount of deposit formed on a YSZ disk placed at the end of the furnace. Experiments are performed at 700, 750 and 800 ° C. The residence times in the hot zone varied from 2 to 4 s. Ethanol is more reactive than butane, and almost all the ethanol is reacted at 750 ° C whereas butane is completely reacted at 800 ° C. Deposit formation is much larger for butane. These results are compared to predictions of a detailed kinetic model. Model predictions for the extent of fuel conversion and molecular-weight growth are in good agreement with the data for both fuels. Butane is predicted to be converted to the lighter hydrocarbons methane, ethylene, propylene and ethane. Hydrogen is also a significant product, especially at higher temperatures. For ethanol, the product distribution is different with lower amounts of hydrocarbons while substantial quantities of water, ethylene, CO and H 2 are predicted. In ethanol pyrolysis there is no significant production of species with more than two carbon atoms, whereas propylene production is significant in butane pyrolysis. Modeling results suggest this is a major reason for increased deposit formation with butane. Equilibrium calculations demonstrate that both the butane and ethanol systems are far removed from equilibrium.

  1. Depositional environment and organic geochemistry of the Upper Permian Ravenfjeld Formation source rock in East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, F.G.; Piasecki, S.; Stemmerik, L. (Geologoical Survey of Greenland, Copenhagen (Denmark)); Telnaes, N. (Norsk Hydro Research Center, Bergen (Norway))

    1993-09-01

    The Upper Permian Ravnefjeld Formation in East Greenland is composed of shales that laterally pass into carbonate buildups and platforms of the Wegener Halvo Formation. The Ravnefjeld Formation is subdivided into five units that can be traced throughout the Upper Permian depositional basin. Two of the units are laminated and organic rich and were deposited under anoxic conditions. They are considered good to excellent source rocks for liquid hydrocarbons with initial average TOC (total organic carbon) values between 4 and 5% and HI (hydrogen index) between 300 and 400. The cumulative source rocks are separated and enclosed by three units of bioturbated siltstone with a TOC of less than 0.5% and an HI of less than 100. These siltstones were deposited under relatively oxic conditions. The organic geochemistry of the source rocks is typical for marine source rocks with some features normally associated with carbonate/evaporite environments [low Pr/Ph (pristane/phytane), low CPI (carbon preference index), distribution of tricyclic and pentacyclic terpanes]. The establishment of anoxic conditions and subsequent source rock deposition was controlled by eustatic sea level changes. The subenvironment (paleogeographic setting, influx of carbonate material, water depth, salinity) has some influence on a number of bulk parameters [TOC-HI relations, TOC-TS (total sulfur) relations] and, in particular, biomarker parameters such as Pr/Ph and terpane ratios. All the basal shales or shales in the vicinity of carbonate buildups of platforms are characterized by low Pr/Ph, high C[sub 23] tricyclic terpanes, and high C[sub 35] and C[sub 33] hopanes. 52 refs., 20 figs., 3 tabs.

  2. Molecular dynamics simulation of fabrication of Cu mono-component metallic glass by physical vapor deposition on Zr substrate

    CERN Document Server

    Yu, Yang; Cui, Fenping

    2016-01-01

    In this work, the single-component Cu metallic glass was fabricated by the physical vapor deposition on the Zr (0001) crystal substrate at 100 K using the classical molecular dynamic simulation. The same deposition process was performed on the Cu (1 0 0) and Ni (1 0 0) crystal substrate for comparison, only the Cu crystal deposited layer with the fcc structure can be obtained. When depositing the Cu atoms on the Zr substrate at 300 K, the crystal structure was formed, which indicates that except the suitable substrate, low temperature is also a key factor for the amorphous structure formation. The Cu liquid quenching from 2000 K to 100 K were also simulated with the cooling rate 1012 K/s to form the Cu glass film in this work. The Cu metallic glass from the two different processes (physical vapor deposition and rapid thermal quenching from liquid) revealed the same radial distribution function and X-ray diffraction pattern, but the different microstructure from the coordination number and Voronoi tessellation...

  3. New Re-Os Isotopic Constrains on the Formation of the Metalliferous Deposits of the Lower Cambrian Niutitang Formation

    Institute of Scientific and Technical Information of China (English)

    Yong Fu; Lin Dong; Chao Li; Wenjun Qu; Haoxiang Pei; Wenlang Qiao; Bing Shen

    2016-01-01

    ABSTRACT:The Terreneuvian Epoch (541–521 Ma)is also an important period for metallogenesis in South China, as was represented by the widespread occurrences of Ni-Mo polymetallic layers on the antecedent shallow platform margin and the V-enriched black shales in deeper slope-basin settings. In this study, we have measured Re-Os isochron ages of Ni-Mo polymetallic layers (Songlin, Niuchang, Sancha, Chuanpengwan), V-rich black shales (Bahuang), and non-metalliferous black shales (Shuidong) in the basal Niutitang Formation in Guizhou and Hunan province, South China. The Ni-Mo polymetal-lic layers and V-enriched black shales have similar Re-Os isochron ages, suggesting concurrent deposi-tion of these two types of metalliferous ores. This suggestion is consistent with the traditional strati-graphic correlation by using the nodular phosphorite bed directly underlying these metalliferous layers as a stratigraphic marker. Furthermore, the metalliferous ores and non-metalliferous black shales have similar initial 187Os/188Os ratios of 0.8–0.9, arguing for a dominant seawater origin with minor contri-bution of hydrothermal activity. Furthermore, Re-Os isotopic data also imply that Ni-Mo and V ore might have derived from the same source. We suggest that the spatial distribution of metalliferous ores can be explained by the development of non-sulfidic anoxic-suboxic wedge (NSASW) in the slope-basin and sulfidic wedge in the previous platform margin. Upwelling of deep water first transects the mildly reduced, organic rich NSASW, in which V (V) is reduced to V (IV), and is preferentially removed from seawater by organometallic complex formation. As a result, V-rich black shale deposits in the slope-basin of Yangtze Platform. Further movement of deep water into the sulfidic platform margin results in Ni-Mo polymetallic layer formation.

  4. Dynamical formation of cataclysmic variables in globular clusters

    Science.gov (United States)

    Hong, Jongsuk; Vesperini, Enrico; Belloni, Diogo; Giersz, Mirek

    2017-01-01

    The formation and evolution of X-ray sources in globular clusters is likely to be affected by the cluster internal dynamics and the stellar interactions in the cluster dense environment. Several observational studies have revealed a correlation between the number of X-ray sources and the stellar encounter rate, and provided evidence of the role of dynamics in the formation of X-ray binaries. We have performed a survey of Monte Carlo simulations aimed at exploring the connection between the dynamics and formation of cataclysmic variables (CVs) and the origin of the observed correlation between the number of these objects, Ncv, and the stellar encounter rate, Γ. The results of our simulations show a correlation between Ncv and Γ, as found in observational data, illustrate the essential role played by the dynamics, and shed light on the dynamical history behind this correlation. CVs in our simulations are more centrally concentrated than single stars with masses close to those of turn-off stars, although this trend is stronger for CVs formed from primordial binaries undergoing exchange encounters, which include a population of more massive CVs absent in the group of CVs formed from binaries not suffering any component exchange.

  5. Dynamical Formation of Cataclysmic Variables in Globular Clusters

    CERN Document Server

    Hong, Jongsuk; Belloni, Diogo; Giersz, Mirek

    2016-01-01

    The formation and evolution of X-ray sources in globular clusters is likely to be affected by the cluster internal dynamics and the stellar interactions in the cluster dense environment.Several observational studies have revealed a correlation between the number of X-ray sources and the stellar encounter rate and provided evidence of the role of dynamics in the formation of X-ray binaries. We have performed a survey of Monte-Carlo simulations aimed at exploring the connection between the dynamics and formation of cataclysmic variables (CVs) and the origin of the observed correlation between the number of these objects, $N_{\\rm cv}$, and the stellar encounter rate, $\\Gamma$.The results of our simulations show a correlation between $N_{\\rm cv}$ and $\\Gamma$ as found in observational data, illustrate the essential role played by dynamics, and shed light on the dynamical history behind this correlation. CVs in our simulations are more centrally concentrated than single stars with masses close to those of turn-off...

  6. Rapidly-deposited polydopamine coating via high temperature and vigorous stirring: formation, characterization and biofunctional evaluation.

    Directory of Open Access Journals (Sweden)

    Ping Zhou

    Full Text Available Polydopamine (PDA coating provides a promising approach for immobilization of biomolecules onto almost all kinds of solid substrates. However, the deposition kinetics of PDA coating as a function of temperature and reaction method is not well elucidated. Since dopamine self-polymerization usually takes a long time, therefore, rapid-formation of PDA film becomes imperative for surface modification of biomaterials and medical devices. In the present study, a practical method for preparation of rapidly-deposited PDA coating was developed using a uniquely designed device, and the kinetics of dopamine self-polymerization was investigated by QCM sensor system. It was found that high temperature and vigorous stirring could dramatically speed up the formation of PDA film on QCM chip surface. Surface characterization, BSA binding study, cell viability assay and antibacterial test demonstrates that the polydopamine coating after polymerization for 30 min by our approach exhibits similar properties to those of 24 h counterpart. The method has a great potential for rapid-deposition of polydopamine films to modify biomaterial surfaces.

  7. Rapidly-deposited polydopamine coating via high temperature and vigorous stirring: formation, characterization and biofunctional evaluation.

    Science.gov (United States)

    Zhou, Ping; Deng, Yi; Lyu, Beier; Zhang, Ranran; Zhang, Hai; Ma, Hongwei; Lyu, Yalin; Wei, Shicheng

    2014-01-01

    Polydopamine (PDA) coating provides a promising approach for immobilization of biomolecules onto almost all kinds of solid substrates. However, the deposition kinetics of PDA coating as a function of temperature and reaction method is not well elucidated. Since dopamine self-polymerization usually takes a long time, therefore, rapid-formation of PDA film becomes imperative for surface modification of biomaterials and medical devices. In the present study, a practical method for preparation of rapidly-deposited PDA coating was developed using a uniquely designed device, and the kinetics of dopamine self-polymerization was investigated by QCM sensor system. It was found that high temperature and vigorous stirring could dramatically speed up the formation of PDA film on QCM chip surface. Surface characterization, BSA binding study, cell viability assay and antibacterial test demonstrates that the polydopamine coating after polymerization for 30 min by our approach exhibits similar properties to those of 24 h counterpart. The method has a great potential for rapid-deposition of polydopamine films to modify biomaterial surfaces.

  8. Rapidly-Deposited Polydopamine Coating via High Temperature and Vigorous Stirring: Formation, Characterization and Biofunctional Evaluation

    Science.gov (United States)

    Zhou, Ping; Deng, Yi; Lyu, Beier; Zhang, Ranran; Zhang, Hai; Ma, Hongwei; Lyu, Yalin; Wei, Shicheng

    2014-01-01

    Polydopamine (PDA) coating provides a promising approach for immobilization of biomolecules onto almost all kinds of solid substrates. However, the deposition kinetics of PDA coating as a function of temperature and reaction method is not well elucidated. Since dopamine self-polymerization usually takes a long time, therefore, rapid-formation of PDA film becomes imperative for surface modification of biomaterials and medical devices. In the present study, a practical method for preparation of rapidly-deposited PDA coating was developed using a uniquely designed device, and the kinetics of dopamine self-polymerization was investigated by QCM sensor system. It was found that high temperature and vigorous stirring could dramatically speed up the formation of PDA film on QCM chip surface. Surface characterization, BSA binding study, cell viability assay and antibacterial test demonstrates that the polydopamine coating after polymerization for 30 min by our approach exhibits similar properties to those of 24 h counterpart. The method has a great potential for rapid-deposition of polydopamine films to modify biomaterial surfaces. PMID:25415328

  9. Mineral deposit formation in Phanerozoic sedimentary basins of north-east Africa: the contribution of weathering

    Science.gov (United States)

    Germann, Klaus; Schwarz, Torsten; Wipki, Mario

    1994-12-01

    The intra- and epicontinental basins in north-east Africa (Egypt, Sudan) bear ample evidence of weathering processes repeatedly having contributed to the formation of mineral deposits throughout the Phanerozoic. The relict primary weathering mantle of Pan-African basement rocks consists of kaolinitic saprolite, laterite (in places bauxitic) and iron oxide crust. On the continent, the reaccumulation of eroded weathering-derived clay minerals (mainly kaolinite) occurred predominantly in fluvio-lacustrine environments, and floodplain and coastal plain deposits. Iron oxides, delivered from ferricretes, accumulated as oolitic ironstones in continental and marine sediments. Elements leached from weathering profiles accumulated in continental basins forming silcrete and alunite or in the marine environment contributing to the formation of attapulgite/saprolite and phosphorites. The Early Paleozoic Tawiga bauxitic laterite of northern Sudan gives a unique testimony of high latitude lateritic weathering under global greenhouse conditions. It formed in close spatial and temporal vicinity to the Late Ordovician glaciation in north Africa. The record of weathering products is essentially complete for the Late Cretaceous/Early Tertiary. From the continental sources in the south to the marine sinks in the north, an almost complete line of lateritic and laterite-derived deposits of bauxitic kaolin, kaolin, iron oxides and phosphates is well documented.

  10. Memory formation: from network structure to neural dynamics.

    Science.gov (United States)

    Feldt, Sarah; Wang, Jane X; Hetrick, Vaughn L; Berke, Joshua D; Zochowski, Michal

    2010-05-13

    Understanding the neural correlates of brain function is an extremely challenging task, since any cognitive process is distributed over a complex and evolving network of neurons that comprise the brain. In order to quantify observed changes in neuronal dynamics during hippocampal memory formation, we present metrics designed to detect directional interactions and the formation of functional neuronal ensembles. We apply these metrics to both experimental and model-derived data in an attempt to link anatomical network changes with observed changes in neuronal dynamics during hippocampal memory formation processes. We show that the developed model provides a consistent explanation of the anatomical network modifications that underlie the activity changes observed in the experimental data.

  11. Molecular Dynamics Simulation of Amyloid Beta Dimer Formation

    CERN Document Server

    Urbanc, B; Ding, F; Sammond, D; Khare, S; Buldyrev, S V; Stanley, H E; Dokholyan, N V

    2004-01-01

    Recent experiments with amyloid-beta (Abeta) peptide suggest that formation of toxic oligomers may be an important contribution to the onset of Alzheimer's disease. The toxicity of Abeta oligomers depends on their structure, which is governed by assembly dynamics. Due to limitations of current experimental techniques, a detailed knowledge of oligomer structure at the atomic level is missing. We introduce a molecular dynamics approach to study Abeta dimer formation: (1) we use discrete molecular dynamics simulations of a coarse-grained model to identify a variety of dimer conformations, and (2) we employ all-atom molecular mechanics simulations to estimate the thermodynamic stability of all dimer conformations. Our simulations of a coarse-grained Abeta peptide model predicts ten different planar beta-strand dimer conformations. We then estimate the free energies of all dimer conformations in all-atom molecular mechanics simulations with explicit water. We compare the free energies of Abeta(1-42) and Abeta(1-40...

  12. Magnesium–Gold Alloy Formation by Underpotential Deposition of Magnesium onto Gold from Nitrate Melts

    Directory of Open Access Journals (Sweden)

    Vesna S. Cvetković

    2017-03-01

    Full Text Available Magnesium underpotential deposition on gold electrodes from magnesium nitrate –ammonium nitrate melts has been investigated. Linear sweep voltammetry and potential step were used as electrochemical techniques. Scanning electron microscopy (SEM, energy dispersive spectrometry (EDS and X-ray diffraction (XRD were used for characterization of obtained electrode surfaces. It was observed that reduction processes of nitrate, nitrite and traces of water (when present, in the Mg underpotential range studied, proceeded simultaneously with magnesium underpotential deposition. There was no clear evidence of Mg/Au alloy formation induced by Mg UPD from the melt made from eutectic mixture [Mg(NO32·6H2O + NH4NO3·XH2O]. However, EDS and XRD analysis showed magnesium present in the gold substrate and four different Mg/Au alloys being formed as a result of magnesium underpotential deposition and interdiffusion between Mg deposit and Au substrate from the melt made of a nonaqueous [Mg(NO32 + NH4NO3] eutectic mixture at 460 K.

  13. Formation of Strata—bound Ore Deposits in China:Studies on Fluid Inclusions

    Institute of Scientific and Technical Information of China (English)

    卢焕章; 刘从强

    1990-01-01

    Fluid inclusion studies were made on the basis of the geological data on the strata-bound ore de-posits of China including those of Pb,Zn,Au,Ag,Sb,U,Hg,W,quartz-crystal and sparry-calcite.An attempt was made to approach the model of formation for each type of ore depos-its by considering the material sources,the migration of fluids and the conditions of mineralization.It is found that ore-forming fluids (especially H2O)originate as heated underground water reacts with the wallrocks and dissolves Na+,Ca2+,K+,Cl+,HCl- and Mg2+ .The ore fluids are mainly of NaCl-Ca-HCO3-H2O system with salinities ranging from 4to 14wt.%.NaCl equivalent and densities ranging from 0.9 to 1.0g/cm3.It may be concluded that the deposits were formed at temperatures ranging from 150 to 250℃ under pressures from 300 to 1000 bars.Ore deposition may have been controlled by temperature and pressure or by the mixing among different fluids.

  14. Satellite formation flying relative dynamics, formation design, fuel optimal maneuvers and formation maintenance

    CERN Document Server

    Wang, Danwei; Poh, Eng Kee

    2017-01-01

    This book systematically describes the concepts and principles for multi-satellite relative motion, passive and near passive formation designs, trajectory planning and control for fuel optimal formation maneuvers, and formation flying maintenance control design. As such, it provides a sound foundation for researchers and engineers in this field to develop further theories and pursue their implementations. Though satellite formation flying is widely considered to be a major advance in space technology, there are few systematic treatments of the topic in the literature. Addressing that gap, the book offers a valuable resource for academics, researchers, postgraduate students and practitioners in the field of satellite science and engineering.

  15. Chemical models for martian weathering profiles: Insights into formation of layered phyllosilicate and sulfate deposits

    Science.gov (United States)

    Zolotov, Mikhail Yu.; Mironenko, Mikhail V.

    2016-09-01

    Numerical chemical models for water-basalt interaction have been used to constrain the formation of stratified mineralogical sequences of Noachian clay-bearing rocks exposed in the Mawrth Vallis region and in other places on cratered martian highlands. The numerical approaches are based on calculations of water-rock type chemical equilibria and models which include rates of mineral dissolution. Results show that the observed clay-bearing sequences could have formed through downward percolation and neutralization of acidic H2SO4-HCl solutions. A formation of weathering profiles by slightly acidic fluids equilibrated with current atmospheric CO2 requires large volumes of water and is inconsistent with observations. Weathering by solutions equilibrated with putative dense CO2 atmospheres leads to consumption of CO2 to abundant carbonates which are not observed in clay stratigraphies. Weathering by H2SO4-HCl solutions leads to formation of amorphous silica, Al-rich clays, ferric oxides/oxyhydroxides, and minor titanium oxide and alunite at the top of weathering profiles. Mg-Fe phyllosilicates, Ca sulfates, zeolites, and minor carbonates precipitate from neutral and alkaline solutions at depth. Acidic weathering causes leaching of Na, Mg, and Ca from upper layers and accumulation of Mg-Na-Ca sulfate-chloride solutions at depth. Neutral MgSO4 type solutions dominate in middle parts of weathering profiles and could occur in deeper layers owing to incomplete alteration of Ca minerals and a limited trapping of Ca to sulfates. Although salts are not abundant in the Noachian geological formations, the results suggest the formation of Noachian salty solutions and their accumulation at depth. A partial freezing and migration of alteration solutions could have separated sulfate-rich compositions from low-temperature chloride brines and contributed to the observed diversity of salt deposits. A Hesperian remobilization and release of subsurface MgSO4 type solutions into newly

  16. Depositional and erosional dynamics of emergent sandbars: a case study of the Platte River, Eastern Nebraska.

    Science.gov (United States)

    Alexander, J. S.; Murr, M. L.; McElroy, B. J.

    2016-12-01

    Macroform sandbars (sandbars) are ubiquitous depositional features of sandy, braided rives. Sandbars formed during annual floods stall and emerge during flow recession, splitting flow, and producing the characteristic braiding pattern. Emergent sandbars are crucial components of riverine ecosystems, forming the foundation of the floodplain/braidplain, providing nesting, brooding, and foraging habitat for migratory and endemic animals, and shallow water aquatic habitat along their periphery. In the United States, substantial resources are being expended to recover and expand so-called emergent sandbar habitat (ESH) in large rivers of the Great Plains, where the natural extent and dynamism of ESH has been degraded due to construction of main-channel dams, navigation channels, and/or disruption of the natural hydrologic and sediment regimes. These programs are ultimately aimed at recovery and protection of populations of Federal and State-listed migratory bird species. Despite the importance of ESH, relatively little empirical information describing the natural temporal and spatial dynamics of sandbar geometries, erosion rates, and depositional controls is available for integrating into ecological and river management models. From 2011 to 2014, we monitored the geometry and fate of large emergent sandbars along 160 km of the sandy, braided Platte River in eastern Nebraska, a segment which retains a mostly natural sediment and hydrologic regime. We show that important descriptors of ESH quality, such as sandbar height, scale linearly with increases in flow stage, but the difference in elevation between sandbar height and formative stage also increases with increasing flow stage. Thus, the flood-hazard of natural sandbars may be much higher than current theory suggests. Our monitoring data indicates that emergent sandbars tend to erode within a year after deposition, and that the rate of erosion scales linearly with discharge. Finally, in agreement with previous work

  17. The conjunction of factors that lead to formation of giant gold provinces and deposits in non-arc settings

    Directory of Open Access Journals (Sweden)

    David I. Groves

    2016-05-01

    In contrast to their province scale similarities, the different giant gold deposit styles show contrasting critical controls at the district to deposit scale. For orogenic gold deposits, the giants appear to have formed by conjunction of a greater number of parameters to those that control smaller deposits, with resultant geometrical and lithostratigraphic complexity as a guide to their location. There are few giant IRGS due to their inferior fluid-flux systems relative to orogenic gold deposits, and those few giants are essentially preservational exceptions. Many Carlin-type deposits are giants due to the exceptional conjunction of both structural and lithological parameters that caused reactive and permeable rocks, enriched in syngenetic gold, to be located below an impermeable cap along antiformal “trends”. Hydrocarbons probably played an important role in concentrating metal. The supergiant Post-Betze deposit has additional ore zones in strain heterogeneities surrounding the pre-gold Goldstrike stock. All unequivocal IOCG deposits are giant or near-giant deposits in terms of gold-equivalent resources, partly due to economic factors for this relatively poorly understood, low Cu-Au grade deposit type. The supergiant Olympic Dam deposit, the most shallowly formed deposit among the larger IOCGs, probably owes its origin to eruption of volatile-rich hybrid magma at surface, with formation of a large maar and intense and widespread brecciation, alteration and Cu-Au-U deposition in a huge rock volume.

  18. Using modern ferruginous habitats to interpret Precambrian banded iron formation deposition

    Science.gov (United States)

    Koeksoy, Elif; Halama, Maximilian; Konhauser, Kurt O.; Kappler, Andreas

    2016-07-01

    Early Earth processes are typically identified through the study of mineralogical, elemental and isotopic features in the rock record, including Precambrian banded iron formations (BIF). However, post-depositional processes often obscure the primary geochemical signals, making the use of BIF as proxies for paleo-seawater and the paleo-biosphere potentially imprecise. Thus, alternative approaches are required to complement the information gained from the rock record in order to fully understand the distinctive biogeochemical processes on ancient Earth. Simulating these conditions in the laboratory is one approach, but this approach can never fully replicate the complexity of a natural environment. Therefore, finding modern environments with a unique set of geochemical and microbiological characteristics to use as analogues for BIF depositional environments can provide invaluable information. In this review, we provide an overview of the chemical, physical and biological parameters of modern, ferruginous lakes that have been used as analogue BIF environments.

  19. THE ROLE OF CRYOGENIC PROCESSES IN THE FORMATION OF LOESS DEPOSITS

    Directory of Open Access Journals (Sweden)

    Vyacheslav N. Konishchev

    2015-01-01

    Full Text Available The paper describes a new approach to the analysis of the genetic nature of mineral substances in loess deposits. In permafrost under the influence of multiple alternate freezing and thawing in dispersed deposits, quartz particles accumulate the 0.05-0.01 mm fraction, while feldspars are crushed to a coarse fraction of 0.1-0.05 mm. In dispersed sediments formed in temperate and warm climatic zones, the granulometric spectrum of quartz and feldspar has the opposite pattern. The proposed methodology is based on a differential analysis of the distribution of these minerals by the granulometric spectrum. We have proposed two criteria - the coefficient of cryogenic contrast (CCC and the coefficient of distribution of heavy minerals, which allow determination of the degree of participation of cryogenic processes in the formation of loess sediments and processes of aeolian or water sedimentation.

  20. Investigation of droplet formation in pulsed Nd:YAG laser deposition of metals and silicon

    Energy Technology Data Exchange (ETDEWEB)

    Siew, Wee-Ong; Lee, Wai-Keat; Wong, Hin-Yong; Tou, Teck-Yong [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Yong, Thian-Khok [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Universiti Tunku Abdul Rahman, Faculty of Engineering and Science, Kuala Lumpur (Malaysia); Yap, Seong-Shan [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor (Malaysia); Norwegian University of Science and Technology, Institute of Physics, Trondheim (Norway)

    2010-12-15

    In the process of pulsed laser deposition of nickel (Ni) and ruthenium (Ru) thin films, the occurrence of phase explosion in ablation was found to affect the deposition rate and enhance the optical emissions from the plasma plume. Faster thin-film growth rates coincide with the onset of phase explosion as a result of superheating and/or sub-surface boiling which also increased the particulates found on the thin-film surface. These particulates were predominantly droplets which may not be round but flattened and also debris for the case of silicon (Si) ablation. The droplets from Ni and Ru thin films were compared in terms of size distribution and number density for different laser fluences. The origins of these particulates were correlated to the bubble and ripple formations on the targets while the transfer to the thin film surface was attributed to the laser-induced ejection from the targets. (orig.)

  1. Shock Dynamics in Stellar Outbursts. I. Shock Formation

    Science.gov (United States)

    Ro, Stephen; Matzner, Christopher D.

    2017-05-01

    Wave-driven outflows and non-disruptive explosions have been implicated in pre-supernova outbursts, supernova impostors, luminous blue variable eruptions, and some narrow-line and superluminous supernovae. To model these events, we investigate the dynamics of stars set in motion by strong acoustic pulses and wave trains, focusing on nonlinear wave propagation, shock formation, and an early phase of the development of a weak shock. We identify the shock formation radius, showing that a heuristic estimate based on crossing characteristics matches an exact expansion around the wave front and verifying both with numerical experiments. Our general analytical condition for shock formation applies to one-dimensional motions within any static environment, including both eruptions and implosions. We also consider the early phase of shock energy dissipation. We find that waves of super-Eddington acoustic luminosity always create shocks, rather than damping by radiative diffusion. Therefore, shock formation is integral to super-Eddington outbursts.

  2. Stratigraphy and depositional environments of the upper Pleistocene Chemehuevi Formation along the lower Colorado River

    Science.gov (United States)

    Malmon, Daniel V.; Howard, Keith A.; House, P. Kyle; Lundstrom, Scott C.; Pearthree, Philip A.; Sarna-Wojcicki, Andrei M.; Wan, Elmira; Wahl, David B.

    2011-01-01

    The Chemehuevi Formation forms a conspicuous, widespread, and correlative set of nonmarine sediments lining the valleys of the Colorado River and several of its larger tributaries in the Basin and Range geologic province. These sediments have been examined by geologists since J. S. Newberry visited the region in 1857 and are widely cited in the geologic literature; however their origin remains unresolved and their stratigraphic context has been confused by inconsistent nomenclature and by conflicting interpretations of their origin. This is one of the most prominent stratigraphic units along the river below the Grand Canyon, and the formation records an important event or set of events in the history of the Colorado River. Here we summarize what is known about these deposits throughout their range, present new stratigraphic, sedimentologic, topographic, and tephrochronologic data, and formally define them as a lithostratigraphic unit. The Chemehuevi Formation consists primarily of a bluff-forming mud facies, consisting of gypsum-bearing, horizontally bedded sand, silt, and clay, and a slope-forming sand facies containing poorly bedded, well sorted, quartz rich sand and scattered gravel. The sedimentary characteristics and fossil assemblages of the two facies types suggest that they were deposited in flood plain and channel environments, respectively. In addition to these two primary facies, we identify three other mappable facies in the formation: a thick-bedded rhythmite facies, now drowned by Lake Mead; a valley-margin facies containing abundant locally derived sediment; and several tributary facies consisting of mixed fluvial and lacustrine deposits in the lower parts of major tributary valleys. Observations from the subsurface and at outcrops near the elevation of the modern flood plain suggest that the formation also contains a regional basal gravel member. Surveys of numerous outcrops using high-precision GPS demonstrate that although the sand facies commonly

  3. Sea ice dynamics influence halogen deposition to Svalbard

    Directory of Open Access Journals (Sweden)

    A. Spolaor

    2013-10-01

    Full Text Available Sea ice is an important parameter in the climate system and its changes impact upon the polar albedo and atmospheric and oceanic circulation. Iodine (I and bromine (Br have been measured in a shallow firn core drilled at the summit of the Holtedahlfonna glacier (Northwest Spitsbergen, Svalbard. Changing I concentrations can be linked to the March–May maximum sea ice extension. Bromine enrichment, indexed to the Br / Na sea water mass ratio, appears to be influenced by changes in the seasonal sea ice area. I is emitted from marine biota and so the retreat of March–May sea ice coincides with enlargement of the open-ocean surface which enhances marine primary production and consequent I emission. The observed Br enrichment could be explained by greater Br emissions during the Br explosions that have been observed to occur mainly above first year sea ice during the early springtime. In this work we present the first comparison between halogens in surface snow and Arctic sea ice extension. Although further investigation is required to characterize potential depositional and post-depositional processes, these preliminary findings suggest that I and Br can be linked to variability in the spring maximum sea ice extension and seasonal sea ice surface area.

  4. Sea ice dynamics influence halogen deposition to Svalbard

    Directory of Open Access Journals (Sweden)

    A. Spolaor

    2013-03-01

    Full Text Available Sea ice is an important parameter in the climate system and its changes impact upon the polar albedo and the atmospheric and oceanic circulation. Iodine (I and bromine (Br have been measured in a shallow ice core drilled at the summit of the Holtedahlfonna glacier (Northwest Spitsbergen, Svalbard. Changing I concentrations can be linked to the spring maximum sea ice extension. Bromine enrichment, indexed to the Br/Na sea water mass ratio, appears to be influenced by changes in the seasonal sea ice area. I is emitted from marine biota and so the retreat of spring sea ice coincides with enlargement of the open ocean surface which enhances marine primary production and consequent I emission. The observed Br enrichment can be explained by greater Br emissions during the Br explosion that have been observed to occur above first year sea ice during the early springtime. In this work we present the first comparison between halogens in surface snow and Arctic sea ice extension. Although further investigation is required to characterize potential depositional and post-depositional processes, these preliminary findings suggest that I and Br can be linked to variability in the spring maximum sea ice extension and seasonal sea ice surface area.

  5. Formation of a deposit on workpiece surface in polishing nonmetallic materials

    Science.gov (United States)

    Filatov, Yu. D.; Monteil, G.; Sidorko, V. I.; Filatov, O. Y.

    2013-05-01

    During the last decades in the theory of machining nonmetallic materials some serious advances have been achieved in the field of applying fundamental scientific approaches to the grinding and polishing technologies for high-quality precision surfaces of electronic components, optical systems, and decorative articles made of natural and synthetic stone [1-9]. These achievements include a cluster model of material removal in polishing dielectric workpieces [1-3, 6-7] and a physical-statistical model of formation of debris (wear) particles and removal thereof from a workpiece surface [8-10]. The aforesaid models made it possible to calculate, without recourse to Preston's linear law, the removal rate in polishing nonmetallic materials and the wear intensity for bound-abrasive tools. Equally important for the investigation of the workpiece surface generation mechanism and formation of debris particles are the kinetic functions of surface roughness and reflectance of glass and quartz workpiece surfaces, which have been established directly in the course of polishing. During the in situ inspection of a workpiece surface by laser ellipsometry [11] and reflectometry [12] it was found out that the periodic change of the light reflection coefficient of a workpiece surface being polished is attributed to the formation of fragments of a deposit consisting of work material particles (debris particles) and tool wear particles [13, 14]. The subsequent studies of the mechanism of interaction between the debris particles and wear particles in the tool-workpiece contact zone, which were carried out based on classical concepts [15, 16], yielded some unexpected results. It was demonstrated that electrically charged debris and wear particles, which are located in the coolant-filled gap between a tool and a workpiece, move by closed circular trajectories enclosed in spheres measuring less than one fifth of the gap thickness. This implies that the probability of the debris and wear

  6. Self-organized formation of metal-carbon nanostructures by hyperthermal ion deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hannstein, I.K.

    2006-04-26

    The quasi-simultaneous deposition of mass-selected hyperthermal carbon and metal ions results in a variety of interesting film morphologies, depending on the metal used and the deposition conditions. The observed features are of the order of a few nanometres and are therefore interesting for future potential applications in the various fields of nanotechnology. The present study focuses on the structural analysis of amorphous carbon films containing either copper, silver, gold, or iron using amongst others Rutherford Backscattering Spectroscopy, High Resolution Transmission Electron Microscopy, and Energy Dispersive X-Ray Spectroscopy. The film morphologies found are as follows: copper-containing films consist of copper nanoclusters with sizes ranging from about 3 to 9 nm uniformly distributed throughout the amorphous carbon matrix. The cluster size hereby rises with the copper content of the films. The silver containing films decompose into a pure amorphous carbon film with silver agglomerates at the surface. Both, the gold- and the iron-containing films show a multilayer structure of metal-rich layers with higher cluster density separated by metal-depleted amorphous carbon layers. The layer distances are of the order of up to 15 nm in the case of gold-carbon films and 7 nm in the case of iron-carbon films. The formation of theses different structures cannot be treated in the context of conventional self-organization mechanisms basing upon thermal diffusion and equilibrium thermodynamics. Instead, an ion-induced atomic transport, sputtering effects, and the stability of small metal clusters were taken into account in order to model the structure formation processes. A similar multilayer morphology was recently also reported in the literature for metal-carbon films grown by magnetron sputtering techniques. In order to investigate, whether the mechanisms are the same as in the case of the ion beam deposited films described above, first experiments were conducted

  7. Exploration and development of the fluvial deposits in the Potrerillos Formation, Cuyana Basin, Mendoza, Argentina

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, C.; Agraz, P. [YPF, S.A., Av. San Martin, Mendoza (Argentina)

    1996-08-01

    In the Barrancas area are located the oil fields related to structures developed in the Oriental axis of the Cuyana Basin. The anticlinal axis of the Barraticas oil field has a NNW-SSE strike and dips toward North. The Oriental flank is abruptly bounded by faulting whilst the Occidental one is gently dipping. The Barrancas oil field was developed between the 1940s and 1960s, having both Early Jurassic conglomerates of the Barrancas Formation and Triassic fluvial braided deposits from Las Cabras Formation as the main targets. The review of new plays within the Triassic fluvial cycles belonging to the Potrerillos Formation was encouraged by the success obtained in the recovery of important volumes of oil from the overlying Formations. The application of a sequence stratigraphy approach to the fluvial settings combined with petrophysics data from outcrop studies and a 3D seismic interpretation allowed a new play concept to be conceived. This new play concept will have application in zones far away from the study area, where Potrerillos Formation has exploration interest. A team integrate by geologists, geophysicists, and engineers has produced new opportunities on mature oil fields with up to 300 drilled wells.

  8. Geochemistry and Depositional Setting of Fort Munro Formation, Middle and Lower Indus Basins, Pakistan

    Institute of Scientific and Technical Information of China (English)

    Shahid Naseem; Shamim Ahmed Sheikh; Erum Bashir; Khaula Shirin

    2005-01-01

    Fort Munro Formation represents the products of the Upper Cretaceous (Maastrichtian) in the middle and lower Indus basins. The formation is exposed in the Rakhi Nala (Sulaiman Range), Bara Nala (Lakhi Range) and Naka Pabni (Southern Pab Range) areas. Major and trace elemental geochemistry and petrographic studies of the formation have been carried out to understand the facies trends in the middle and lower Indus basins. A high amount of acid-insoluble fraction, Ca/Mg and Mg vs. Ca/Sr ratio reveal that the formation was deposited in a shallow marine regressive environment. High amounts of clastic reflect abundant influx of terrigenous materials from the east (Indian craton) and west (Bibai volcanic). High Sr content indicates that aragonite was the precursor mineral, which was transformed into stable low-Mg calcite during diagenesis. Enrichment of Cu and Zn contents in the samples of the formation implies the influence of volcanic activity and that they were incorporated into the calcite lattice in the late phase.

  9. Energy deposition dynamics of femtosecond pulses in water

    CERN Document Server

    Minardi, Stefano; Gopal, Amrutha; Tamošauskas, Gintaras; Milián, Carles; Couairon, Arnaud; Pertsch, Thomas; Dubietis, Audrius

    2014-01-01

    We exploit inverse Raman scattering and solvated electron absorption to perform a quantitative characterization of the energy loss and ionization dynamics in water with tightly focused near-infrared femtosecond pulses. A comparison between experimental data and numerical simulations suggests that the ionization energy of water is 8 eV, rather than the commonly used value of 6.5 eV.

  10. Manual for Dynamic Modelling of Soil Response to Atmospheric Deposition

    NARCIS (Netherlands)

    Posch MB; Hettelingh J-P; Slootweg J; LED; UNECE Working Group on Effects; ICP M&M Coordination Center for Effects

    2003-01-01

    The objective of this manual is to inform the network of National Focal Centers (NFCs) about the requirements of methodologies for the dynamic modelling of geochemical processes in soils in particular. This information is necessary to support European air quality policies with knowledge on time dela

  11. Dimer and String Formation during Low Temperature Silicon Deposition on Si(100)

    DEFF Research Database (Denmark)

    Smith, A. P.; Jonsson, Hannes

    1996-01-01

    We present theoretical results based on density functional theory and kinetic Monte Carlo simulations of silicon deposition and address observations made in recently reported low temperature scanning tunneling microscopy studies. A mechanism is presented which explains dimer formation on top...... of the substrate's dimer rows at 160 K and up to room temperature, while between-row dimers and longer strings of adatoms (''diluted dimer rows'') form at higher temperature. A crossover occurs at around room temperature between two different mechanisms for adatom diffusion in our model....

  12. Ash formation, transformations and deposition during fluidized bed combustion and gasification

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E.; Lind, T.; Kurkela, J.; Latva-Somppi, J.; Lyyraenen, J.; Valmari, T. [VTT Chemical Technology, Espoo (Finland). Aerosol Technology Group

    1998-12-31

    In this work, ash formation and transformations as well as bed agglomeration and fly ash deposition onto the heat exchanger tubes during fluidised bed combustion and gasification were studied using experimental methods and chemical equilibrium calculations. The fuels were coal and pulp and paper mill sludges as well as different wood-based waste materials. The volatilized heavy metal behaviour during pressurized combustion and gasification was studied using chemical equilibrium calculations. The classification of trace elements into four groups presented in this report matched well with the former studies. The release of ash-forming compounds during pyrolysis was studied experimentally in a heated grid reactor. Very small fractions of Si, Al, Fe, Ca, Mg, Na, and K were released from the biomass fuels, peat, and coals during pyrolysis at 900 deg C. Bottom ash during combustion of biomass fuels was found to be formed from bed material and ash-forming compounds. Ash-forming compounds were found to adhere to the bed material by two mechanisms: (i) by deposition of the non-volatile ash compounds as particles onto the bed particle surface, and (ii) by chemical reactions of the volatile ash compounds, e.g., K and Pb, with the bed particles. The size distributions of the fly ash particles were bimodal. The fine mode particles (Dp < 1 {mu}m) were formed by nucleation of the volatilised refractory oxides, e.g., SiO{sub 2}. The nucleated particles grew further by coagulation and condensation of the volatile ash compounds. The coarse fly ash fraction (Dp > 1 {mu}m) was formed from the non-volatile ash compounds, e.g., Ca and Si. The coarse mode particles were agglomerated and irregular in shape. During sludge combustion, the fly ash was mostly in the supermicron size range. This is beneficial for conventional flue gas cleaning devices that are most effective in this particle size. This is especially true for paper mill sludges, producing negligible concentrations of submicron

  13. Perspective: network-guided pattern formation of neural dynamics.

    Science.gov (United States)

    Hütt, Marc-Thorsten; Kaiser, Marcus; Hilgetag, Claus C

    2014-10-05

    The understanding of neural activity patterns is fundamentally linked to an understanding of how the brain's network architecture shapes dynamical processes. Established approaches rely mostly on deviations of a given network from certain classes of random graphs. Hypotheses about the supposed role of prominent topological features (for instance, the roles of modularity, network motifs or hierarchical network organization) are derived from these deviations. An alternative strategy could be to study deviations of network architectures from regular graphs (rings and lattices) and consider the implications of such deviations for self-organized dynamic patterns on the network. Following this strategy, we draw on the theory of spatio-temporal pattern formation and propose a novel perspective for analysing dynamics on networks, by evaluating how the self-organized dynamics are confined by network architecture to a small set of permissible collective states. In particular, we discuss the role of prominent topological features of brain connectivity, such as hubs, modules and hierarchy, in shaping activity patterns. We illustrate the notion of network-guided pattern formation with numerical simulations and outline how it can facilitate the understanding of neural dynamics. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  14. Dynamics of formation of ferromanganese nodules in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Ghosh, A.K.

    stream_size 27400 stream_content_type text/plain stream_name J_Asian_Earth_Sci_37_394a.pdf.txt stream_source_info J_Asian_Earth_Sci_37_394a.pdf.txt Content-Encoding UTF-8 Content-Type text/plain; charset=UTF-8 Author..., and the model should bring about a predictive estimate of other nodule bearing areas in the world oceans. Key Words: Ferromanganese nodules, Indian Ocean Nodule Field, influencing parameters, Nodule formation and dynamics, Model of nodule formation...

  15. Formation and post-formation dynamics of bacterial biofilm streamers as highly viscous liquid jets

    CERN Document Server

    Das, Siddhartha

    2013-01-01

    It has been recently reported that in presence of low Reynolds number (Re<<1) transport, preformed bacterial biofilms, several hours after their formation, may degenerate in form of filamentous structures, known as streamers. In this letter, we explain that such streamers form as the highly viscous liquid states of the intrinsically viscoelastic biofilms. Such "viscous liquid" state can be hypothesized by noting that the time of appearance of the streamers is substantially larger than the viscoelastic relaxation time scale of the biofilms, and this appearance is explained by the inability of a viscous liquid to withstand an external shear. Further, by identifying the post formation dynamics of the streamers as that of a viscous liquid jet in a surrounding flow field, we can interpret several unexplained issues associated with the post-formation dynamics of streamers, such as the clogging of the flow passage or the exponential time growth of streamer dimensions.

  16. The Shublik Formation and adjacent strata in northeastern Alaska description, minor elements, depositional environments and diagenesis

    Science.gov (United States)

    Tourtelot, Harry Allison; Tailleur, Irvin L.

    1971-01-01

    occurrence of silver and 300 ppm lead in gouge along a shear plane may be the result of metals introduced from an extraneous source. The deposits reflect a marine environment that deepened somewhat following deposition of the Sadlerochit Formation and then shoaled during deposition of the upper limestone-siltstone unit. This apparently resulted from a moderate transgression and regression of the sea with respect to a northwest-trending line between Barrow and the Brooks Range at the International Boundary. Nearer shore facies appear eastward. The phosphate in nodules, fossil molds and oolites, appears to have formed diagenetically within the uncompacted sediment.

  17. Dynamic Trap Formation and Elimination in Colloidal Quantum Dots

    KAUST Repository

    Voznyy, O.

    2013-03-21

    Using first-principles simulations on PbS and CdSe colloidal quantum dots, we find that surface defects form in response to electronic doping and charging of the nanoparticles. We show that electronic trap states in nanocrystals are dynamic entities, in contrast with the conventional picture wherein traps are viewed as stable electronic states that can be filled or emptied, but not created or destroyed. These traps arise from the formation or breaking of atomic dimers at the nanoparticle surface. The dimers\\' energy levels can reside within the bandgap, in which case a trap is formed. Fortunately, we are also able to identify a number of shallow-electron-affinity cations that stabilize the surface, working to counter dynamic trap formation and allowing for trap-free doping. © 2013 American Chemical Society.

  18. Ice Formation on Kaolinite: Insights from Molecular Dynamics Simulations

    CERN Document Server

    Sosso, Gabriele C; Zen, Andrea; Pedevilla, Philipp; Michaelides, Angelos

    2016-01-01

    The formation of ice affects many aspects of our everyday life as well as technologies such as cryotherapy and cryopreservation. Foreign substances almost always aid water freezing through heterogeneous ice nucleation, but the molecular details of this process remain largely unknown. In fact, insight into the microscopic mechanism of ice formation on different substrates is difficult to obtain even via state-of-the-art experimental techniques. At the same time, atomistic simulations of heterogeneous ice nucleation frequently face extraordinary challenges due to the complexity of the water-substrate interaction and the long timescales that characterize nucleation events. Here, we have investigated several aspects of molecular dynamics simulations of heterogeneous ice nucleation considering as a prototypical ice nucleating material the clay mineral kaolinite, which is of relevance in atmospheric science. We show via seeded molecular dynamics simulations that ice nucleation on the hydroxylated (001) face of kaol...

  19. Depositional environments of Laborcita Formation (Wolfcampian), northern Sacramento Mountains, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Fly, S.H. III

    1986-03-01

    Depositional environments that change dramatically over short lateral distances are represented by exposures of the Laborcita Formation. A siliclastic source area lay to the east and southeast, in the Pedernal Mountains. To the west, a shallow marine sea filled the orogrande basin. Alternating cycles of marine and nonmarine sedimentation resulted from fan-delta lobe shifting and eustatic sea level movements. In clear-water areas not affected by fan-deltaic sedimentation, deposits become increasingly calcareous. Various carbonate facies resulted from organisms adapting to changing environmental conditions. Mud-cracked algal mats, digitate algal stromatolites, and small phylloid red algal mounds and rhodoliths indicate deposition in shallow-water subtidal to supratidal settings. Large buildups (20 m thick) of phylloid green algae associated with abundant submarine cement occurred in a position near the edge of the narrow shelf. Widespread skeletal detritus beds overlie and extend hundreds of meters away from the massive buildups. Influx of terrigenous mud and silt in advance of a prograding fan-delta system terminated growth of the buildups. The next transgression is represented by a carbonate grainstone exhibiting characteristics of shallow-water marine, storm-dominated shelf bars. The shelf bars migrated in a northwest-southeast direction.

  20. Process of Energetic Carbon Atom Deposition on Si (001) Substrate by Molecular Dynamics Simulation

    Institute of Scientific and Technical Information of China (English)

    于威; 滕晓云; 李晓苇; 傅广生

    2002-01-01

    The process of energetic C atom deposition on Si (001)-(2×1) is studied by the molecular dynamics method using the semi-empirical many-bond Tersoff potential. It is found that the incident energy of the carbon atom has an important effect on the collision process and its diffusion process on the substrate. Most of the incident energy of the carbon atom is transferred to the substrate atoms within the initial two vibration periods of substrate atoms and its value increases with the incident energy. The spreading distance and penetration depth of the incident atom increasing with the incident energy are also identified. The simulated results imply that an important effect of energy of incident carbon on the film growth at Iow substrate temperature provides activation energy for silicon carbide formation through the vibration enhancement of local substrate atoms. In addition, suppressing carbon atom inhomogeneous collection and dispensing with the silicon diffusion process may be effectively promoted by the spreading and penetration of the energetic carbon atom in the silicon substrate.

  1. Paleoceanographic and tectonic controls on deposition of the Monterey formation and related siliceous rocks in California

    Science.gov (United States)

    Barron, J.A.

    1986-01-01

    The timing of paleoceanographic and tectonic events that shaped the deposition of the Monterey Formation of California and related siliceous rocks has been determined by application of a refined biochronology. The base of the Monterey at 17.5 Ma coincides with rising global sea level and a switch in biogenous silica deposition from the Caribbean and low-latitude North Atlantic to the North Pacific. Major polar cooling, which began at 15 Ma, postdates the base of the Monterey by more than 2 Ma and cannot be invoked to cause the deposition of diatomaceous sediments occurring in the lowermost Monterey. Later polar cooling in the early late Miocene, however, apparently caused increased upwelling and deposition of purer diatomites in the upper Monterey. The top of the Monterey at about 6 Ma coincides with a major sea level drop and is commonly marked by an unconformity. Equivalent unconformities are widespread around the rim of the North Pacific and typically separate more pelagic sediments from overlying sediments with a greater terrigenous component. Above the Monterey, diatoms persist in California sediments to 4.5-4.0 m.y., where their decline coincides with increased deposition of diatoms in the Antarctic. Carbon isotope records in the Pacific and Indian Oceans record storage of 12C in the Monterey Formation and equivalent organic-rich sediments around the rim of the North Pacific. A +1.0??? excursion in ?? 13C beginning at 17.5 Ma coincides with rising sea level and probably reflects storage of organic material in Monterey-like marginal reservoirs. A reverse -1.0??? shift at 6.2 Ma closely approximates the top of the Monterey and may represent erosion of these marginal reservoirs and reintroduction of stored organic carbon into the ocean-atmosphere system. Initiation of transform faulting and extension in the California margin in the latest Oligocene and early Miocene caused the subsidence of basins which later received Monterey sediments. A major tectonic event

  2. Nanoparticles dynamics on a surface: fractal pattern formation and fragmentation

    DEFF Research Database (Denmark)

    Dick, Veronika V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2010-01-01

    In this paper we review our recent results on the formation and the post-growth relaxation processes of nanofractals on surface. For this study we developed a method which describes the internal dynamics of particles in a fractal and accounts for their diffusion and detachment. We demonstrate...... that these kinetic processes determine the final shape of the islands on surface after post-growth relaxation. We consider different scenarios of fractal relaxation and analyze the time evolution of the island's morphology....

  3. Track-etched membrane: dynamics of pore formation

    Science.gov (United States)

    Ferain, E.; Legras, R.

    1994-02-01

    The dynamics of pore formation during etching of heavy ion (Ar 9+ - 4.5 MeV/amu) irradiated bisphenol-A polycarbonate (PC) and polyethylene terephthalate (PET) films is determined by a conductivity cell. This work presents the theoretical basis of this method and describes the experimental procedure. The obtained results allow the determination of the track ( Vt) and bulk ( Vg) etch rates, and an estimate of the damage zone diameter in PC before etching.

  4. Nanoparticles dynamics on a surface: fractal pattern formation and fragmentation

    DEFF Research Database (Denmark)

    Dick, Veronika V.; Solov'yov, Ilia; Solov'yov, Andrey V.

    2010-01-01

    In this paper we review our recent results on the formation and the post-growth relaxation processes of nanofractals on surface. For this study we developed a method which describes the internal dynamics of particles in a fractal and accounts for their diffusion and detachment. We demonstrate...... that these kinetic processes determine the final shape of the islands on surface after post-growth relaxation. We consider different scenarios of fractal relaxation and analyze the time evolution of the island's morphology....

  5. Pleistocene glacio-lacustrine deltaic deposits of the Scarborough Formation, Ontario, Canada

    Science.gov (United States)

    Kelly, R. I.; Martini, I. P.

    1986-04-01

    The late Pleistocene Scarborough Formation of the Lake Ontario Basin represents a lacustrine-deltaic sequence strongly affected by a nearby glacier. It shows gradual upward coarsening and thickening of layers from varve-like, clay-rich rhythmites at the base to channelized cross-bedded sands at the top. Thick, lensing, "massive" layers (Cm) of silty sand are found interstratified with thin layers of silt and clay in the lower and middle parts of the sequence. These "massive" layers were probably formed by subaqueous gravity flows of material in part derived directly from a glacier. Absence of pebbles and of other features such as glacial silt-pellets suggests dispersal away from the foot of the glacier rather than deposition under floating ice. Varve-like rhythmites, pollen and insect fauna indicate subarctic to arctic climatic conditions at the time of sediment deposition. The large amount of sand in the upper part of the formation is best explained as derived from active outwash fans. Similar fans were formed during the last deglaciation in southern Ontario and can be observed on the landscape.

  6. Simulation of geochemical processes responsible for the formation of the Zhezqazghan deposit

    Science.gov (United States)

    Ryzhenko, B. N.; Cherkasova, E. V.

    2014-05-01

    Physicochemical computer simulation of water-rock systems at a temperature of 25-150°C and under a pressure of up to 600 bar has been carried out for quantitative description of the mineralization formation conditions at sandstone- and shale-hosted copper deposits. The simulation is based on geological and geochemical information concerning the Zhezqazghan deposit and considers (i) a source of ore matter, (ii) composition of the fluid that transfers ore matter to the ore formation zone, and (iii) factors of ore concentration. It has been shown that extraction of copper from minerals of rocks and its accumulation in aqueous solution are optimal at a high mass ratio of rock to water (R/W > 10), Eh of +200 to -100 mV, and an obligatory content of chloride ions in the aqueous phase. The averaged ore-bearing fluid Cl95SO44//Ca50(Na + K)30Mg19 (eq %), pH ˜ 4, mineralization of up to 400 g/L, is formed by the interaction of red sandstone beds with a sedimentogenic brine (a product of metamorphism of seawater in carbonate rocks enriched in organic matter). The ore concentration proceeds in the course of cooling from 150 to 50°C during filtration of ore-bearing fluid through red sandstone beds in the rock-water system thermodynamically opened with respect to the reductive components.

  7. Electrochemical Investigation on the Formation of Cu Nanowires by Electroless Deposition

    Directory of Open Access Journals (Sweden)

    Felizco Jenichi Clairvaux E.

    2015-01-01

    Full Text Available The growth of copper (Cu nanowires by electroless deposition in aqueous solution at 60-80 °C was studied from an electrochemical perspective using in situ mixed potential measurements and potential-pH diagrams. Scanning Electron Microscopy (SEM showed that thick and short nanowires were obtained at high temperatures, while long and thin nanowires result from low reaction temperatures. In situ mixed potential measurements reveal that Cu(II reduction is more favored at higher reaction temperatures, hastening the reduction reaction. The fast reaction leads to a high concentration of Cu atoms in the solution. As a result, Cu deposition occurs rapidly, such that they attached on both sides and ends of the primary Cu nanowires. This results to the formation of thick and short structures. On the other hand, thin and long nanowires are obtained due to the slow reduction reaction, which gives the Cu atoms more time to orderly attach in a wire-like formation.

  8. Early Cambrian wave-formed shoreline deposits: the Hardeberga Formation, Bornholm, Denmark

    Science.gov (United States)

    Clemmensen, Lars B.; Glad, Aslaug C.; Pedersen, Gunver K.

    2017-09-01

    During the early Cambrian, the Danish island Bornholm was situated on the northern edge of the continent Baltica with palaeolatitudes of about 35°S. An early Cambrian (Terreneuvian) transgression inundated large areas of Baltica including Bornholm creating shallow marine and coastline environments. During this period, wave-formed shoreline sediments (the Vik Member, Hardeberga Formation) were deposited on Bornholm and are presently exposed at Strøby quarry. The sediments consist of fine- and medium-grained quartz-cemented arenites in association with a few silt-rich mudstones. The presence of well-preserved subaqueous dunes and wave ripples indicates deposition in a wave-dominated upper shoreface (littoral zone) environment, and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and/or changing meteorological conditions. Discoidal structures (medusoids) are present in the quarry, but due to the relative poor preservation of their fine-scale structures it is difficult to determine if the discoids represent true medusae imprints or inorganic structures. The preservation of the shallow-water bedforms as well as the possible medusae imprints is related to either the formation of thin mud layers, formed during a period of calm water when winds blew offshore for a longer period, or to the growth of bacterial mats. The orientation of the wave-formed bedforms indicates a local palaeoshoreline trending NE-SW and facing a large ocean to the north.

  9. Early Cambrian wave-formed shoreline deposits: the Hardeberga Formation, Bornholm, Denmark

    Science.gov (United States)

    Clemmensen, Lars B.; Glad, Aslaug C.; Pedersen, Gunver K.

    2016-09-01

    During the early Cambrian, the Danish island Bornholm was situated on the northern edge of the continent Baltica with palaeolatitudes of about 35°S. An early Cambrian (Terreneuvian) transgression inundated large areas of Baltica including Bornholm creating shallow marine and coastline environments. During this period, wave-formed shoreline sediments (the Vik Member, Hardeberga Formation) were deposited on Bornholm and are presently exposed at Strøby quarry. The sediments consist of fine- and medium-grained quartz-cemented arenites in association with a few silt-rich mudstones. The presence of well-preserved subaqueous dunes and wave ripples indicates deposition in a wave-dominated upper shoreface (littoral zone) environment, and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and/or changing meteorological conditions. Discoidal structures (medusoids) are present in the quarry, but due to the relative poor preservation of their fine-scale structures it is difficult to determine if the discoids represent true medusae imprints or inorganic structures. The preservation of the shallow-water bedforms as well as the possible medusae imprints is related to either the formation of thin mud layers, formed during a period of calm water when winds blew offshore for a longer period, or to the growth of bacterial mats. The orientation of the wave-formed bedforms indicates a local palaeoshoreline trending NE-SW and facing a large ocean to the north.

  10. Quantum dot formation and dynamic scaling behavior of SnO2 nanocrystals induced by pulsed delivery

    Science.gov (United States)

    Chen, Z. W.; Lai, J. K. L.; Shek, C. H.

    2006-01-01

    Quantum dot formation and dynamic scaling behavior of SnO2 nanocrystals in coalescence regime for growth by pulsed-laser deposition is explored experimentally and theoretically, and the same is compared with that for continuous vapor deposition such as molecular-beam epitaxy. Using high-resolution transmission electron microscopy, unusual quantum dots of SnO2 nanocrystals are studied. We present kinetic Monte-Carlo simulations for pulsed-laser deposition in the submonolayer regime and give a description of the island distance versus pulse intensity. We found that the scaling exponent for pulsed-laser deposition is 1.28±0.03, which is significantly lower as compared to that for molecular-beam epitaxy (1.62±0.03). Theoretical simulations reveal that this attractive difference can be pursued to the large fraction of multiple droplet coalescence under pulsed vapor delivery.

  11. Ice formation on kaolinite: Insights from molecular dynamics simulations

    Science.gov (United States)

    Sosso, Gabriele C.; Tribello, Gareth A.; Zen, Andrea; Pedevilla, Philipp; Michaelides, Angelos

    2016-12-01

    The formation of ice affects many aspects of our everyday life as well as important technologies such as cryotherapy and cryopreservation. Foreign substances almost always aid water freezing through heterogeneous ice nucleation, but the molecular details of this process remain largely unknown. In fact, insight into the microscopic mechanism of ice formation on different substrates is difficult to obtain even if state-of-the-art experimental techniques are used. At the same time, atomistic simulations of heterogeneous ice nucleation frequently face extraordinary challenges due to the complexity of the water-substrate interaction and the long time scales that characterize nucleation events. Here, we have investigated several aspects of molecular dynamics simulations of heterogeneous ice nucleation considering as a prototypical ice nucleating material the clay mineral kaolinite, which is of relevance in atmospheric science. We show via seeded molecular dynamics simulations that ice nucleation on the hydroxylated (001) face of kaolinite proceeds exclusively via the formation of the hexagonal ice polytype. The critical nucleus size is two times smaller than that obtained for homogeneous nucleation at the same supercooling. Previous findings suggested that the flexibility of the kaolinite surface can alter the time scale for ice nucleation within molecular dynamics simulations. However, we here demonstrate that equally flexible (or non flexible) kaolinite surfaces can lead to very different outcomes in terms of ice formation, according to whether or not the surface relaxation of the clay is taken into account. We show that very small structural changes upon relaxation dramatically alter the ability of kaolinite to provide a template for the formation of a hexagonal overlayer of water molecules at the water-kaolinite interface, and that this relaxation therefore determines the nucleation ability of this mineral.

  12. The formation of Palæoproterozoic banded iron formations and their associated Fe and Mn deposits, with reference to the Griqualand West deposits, South Africa

    Science.gov (United States)

    Klemm, Dietrich D.

    2000-01-01

    This paper models the physico-chemical conditions of a Neoarchæan to Palæoproterozoic marine basin in which the sedimentary sequence of BIF, Fe and Mn ores of the Lake Superior-type formed. The model is based on Eh-pH diagram stability fields for Fe, silica and Mn solubilities (taken from the literature) and on field observations of the lithological sequences. BIF formation took place in epicontinental marine basins with free access to the ocean. The main Fe source for BIF formation was ocean enriched with about 6-10 ppm ferrous Fe of hydrothermal geochemical affinity. Land-derived Fe influxes into the BIF-forming basins certainly contributed, but the lack of clastic sedimentation precludes estimation of element budgets. The main silica source for formation of chert layers is sea water. If silica was precipitated by evaporation, the silica concentration of the BIF-forming sea must have been close to saturation (15-20 ppm). Biogenic silica concentration from a possible silica undersaturated sea may not be excluded. These inferred BIF-forming conditions fit the global occurrence of Lake Superior-type BIF in general, whereas special sedimentary environments were probably responsible for the formation of highly enriched laminated Fe ore at the Maremane Dome and in the Sishen-Kathu mining district in Griqualand West, and for the FeMn ores in the Kalahari field. Formation of laminated Fe ore in the Maremane Dome and in the Sishen-Kathu areas were restricted to local deeps within the BIF basins, caused by karst collapse in the underlying Campbellrand dolomites. In such deeps, increased pH values relative to the normal BIF-forming sea caused sufficiently increased silica solubility, resulting in the almost exclusive sedimentation of colloidal Fe precipitates. In the Kalahari field, the BIF sedimentation pile became silica-depleted when approaching the Mn layers. This was genetically controlled by the increased pH of sea water and increased silica solubility. Under

  13. Responses of Carbon Dynamics to Nitrogen Deposition in Typical Freshwater Wetland of Sanjiang Plain

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2014-01-01

    Full Text Available The effects of nitrogen deposition (N-deposition on the carbon dynamics in typical Calamagrostis angustifolia wetland of Sanjiang Plain were studied by a pot-culture experiment during two continuous plant growing seasons. Elevated atmospheric N-deposition caused significant increases in the aboveground net primary production and root biomass; moreover, a preferential partition of carbon to root was also observed. Different soil carbon fractions gained due to elevated N-deposition and their response intensities followed the sequence of labile carbon > dissolved organic carbon > microbial biomass carbon, and the interaction between N-deposition and flooded condition facilitated the release of different carbon fractions. Positive correlations were found between CO2 and CH4 fluxes and liable carbon contents with N-deposition, and flooded condition also tended to facilitate CH4 fluxes and to inhibit the CO2 fluxes with N-deposition. The increases in soil carbon fractions occurring in the nitrogen treatments were significantly correlated with increases in root, aboveground parts, total biomass, and their carbon uptake. Our results suggested that N-deposition could enhance the contents of active carbon fractions in soil system and carbon accumulation in plant of the freshwater wetlands.

  14. Sodium sulphate deposits of Neogene age: the Kirmir Formation, Beypazari Basin, Turkey

    Science.gov (United States)

    Ortí, Federico; Gündogan, Ibrahim; Helvaci, Cahit

    2002-01-01

    The Evaporite Member of the Kirmir Formation was deposited in shallow lacustrine environments during the upper Miocene. The most soluble minerals of this member can be currently observed in the Çayirhan mine. The Evaporite Member, which is composed of secondary gypsum at outcrop, can be subdivided into a bedded lower unit and a massive upper unit. In the bedded lower unit, most of the gypsum throughout the basin can be identified as having been transformed from glauberite. In the glauberite layers of the Çayirhan mine, some glauberite textures ('clear glauberite') suggest a primary, subaqueous, free precipitation on a depositional floor. More common, however, are the glauberite textures indicating an interstitial growth within a clayey-magnesitic matrix. In the thenardite layers accompanying the glauberite in the Çayirhan mine, some disruption structures can be assigned to synsedimentary dissolution. These structures together with the textures of the thenardite suggest that the original sodium sulphate was mirabilite, thenardite being a secondary phase, which formed during early to moderate burial diagenesis. The massive upper unit, in which evidence of sodium-bearing minerals is absent, is characterized by laminated to banded gypsum and nodular gypsum in the marginal areas of the evaporitic basin, whereas thick, clast-supported gypsum breccias prevail in the northern, deeper part of the basin. The brecciation of these calcium sulphate layers occurred as a result of synsedimentary, gravitative slumping under tectonic control. Although the sulphur isotopic values (δ 34S) of the sulphates of the Kirmir Formation suggest a marine-derived brine supply, the oxygen isotopic values (δ 18O) and the strontium ratios ( 87Sr/ 86Sr) do not support such a supply. The origin of the mother brines, the glauberite genesis, the depositional model of the sodium sulphates, and the salinity evolution are discussed.

  15. Deposition of rheomorphic ignimbrite D (Mogán Formation), Gran Canaria, Canary Islands, Spain

    Science.gov (United States)

    Kobberger, Gustav; Schmincke, Hans-Ulrich

    Rheomorphic ignimbrite D (13.4Ma, Upper Mogán Formation on Gran Canaria), a multiple flow-single cooling unit, is divided into four major structural zones that differ in fabric and finite strain of deformed pyroclasts. Their structural characteristics indicate contrasting deformation mechanisms during rheomorphic flow. The zones are: (a) a basal zone (vitrophyre) with pure uniaxial flattening perpendicular to the foliation; (b) an overlying shear zone characterized by asymmetric fabrics and a significantly higher finite strain, with an ellipsoid geometry similar to stretched oblate bodies; (c) a central zone with a finite strain geometry similar to that of the underlying shear zone but without evidence of a rotational strain component; and (d) a slightly deformed to non-deformed top zone where the almost random orientation of subspherical pyroclasts suggests preservation of original, syn-depositional clast shapes. Rheomorphic flow in D is the result of syn- to post-depositional remobilization of a hot pyroclastic flow as shown by kinematic modeling based on: (a) the overall vertical structural zonation suggested by finite strain and fabric analysis; (b) the relation of shear sense to topography; (c) the interrelationship of the calculated vertical cooling progression at the base of the flow (formation of vitrophyre) and the related vertical changes in strain geometry; (d) the complex lithification history; and (e) the consequent mechanisms of deformational flow. Rheomorphic flow was caused by load pressure due to an increase in the vertical accumulation of pyroclastic material on a slope of generally 6-8°. We suggest that every level of newly deposited pyroclastic flow material of D first passed through a welding process that was dominated by compaction (pure flattening) before rheomorphic deformation started.

  16. Modeling of droplet dynamic and thermal behaviour during spray deposition

    Indian Academy of Sciences (India)

    N S Mahesh; Johnson Mendonca; M K Muralidhara; B K Muralidhara; C Ramachandra

    2003-04-01

    Mathematical modeling of supersonic gas atomization for spray forming has been investigated. Influence of the droplet dynamic and thermal behaviour on the resultant microstructure has been studied. Analytical models have been constructed taking into account the higher Reynolds number owing to supersonic gas flow. The impact velocity profiles of the droplets lend credence to the evolution of equiaxed grain morphology through dendrite fragmentation. The thermal history profile along with the fraction solid plot could yield optimized standoff distance to obtain a mushy droplet. A comparison of secondary dendrite arm spacing obtained from the mathematical model showed good agreement with experimental observations.

  17. Energy deposition dynamics of femtosecond pulses in water

    Energy Technology Data Exchange (ETDEWEB)

    Minardi, Stefano, E-mail: stefano@stefanominardi.eu; Pertsch, Thomas [Institute of Applied Physics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Milián, Carles; Couairon, Arnaud [Centre de Physique Théorique, CNRS, École Polytechnique, F-91128 Palaiseau (France); Majus, Donatas; Tamošauskas, Gintaras; Dubietis, Audrius [Department of Quantum Electronics, Vilnius University, Sauletekio 9, bldg. 3, LT-10222 Vilnius (Lithuania); Gopal, Amrutha [Institute of Optics and Quantum Electronics, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2014-12-01

    We exploit inverse Raman scattering and solvated electron absorption to perform a quantitative characterization of the energy loss and ionization dynamics in water with tightly focused near-infrared femtosecond pulses. A comparison between experimental data and numerical simulations suggests that the ionization energy of water is 8 eV, rather than the commonly used value of 6.5 eV. We also introduce an equation for the Raman gain valid for ultra-short pulses that validates our experimental procedure.

  18. Oligomer formation within secondary organic aerosol: equilibrium and dynamic considerations

    Directory of Open Access Journals (Sweden)

    E. R. Trump

    2013-09-01

    Full Text Available We present a model based on the volatility basis set to consider the potential influence of oligomer content on volatility-driven SOA yields. The implications for aerosol evaporation studies, including dilution, chamber thermo-equilibration, and thermodenuder studies are also considered. A simplified description of oligomer formation reproduces essentially all of the broad classes of equilibrium and dynamical observations related to SOA formation and evaporation: significant oligomer content may be consistent with mass yields that increase with organic aerosol mass concentration; reversible oligomerization can explain the hysteresis between the rate of SOA formation and its evaporation rate upon dilution; and the model is consistent with both chamber thermo-equilibration studies and thermodenuder studies of SOA evaporation.

  19. A Dynamical Study of the Formation of Peculiar Galaxies

    Science.gov (United States)

    Chatterjee, T. K.

    1990-11-01

    RESUMEN. Un estudlo de la formaci6n de diferentes tipos de galaxias peculiares (interactuantes) es conducido en base de la dina'mioa de la colisi6n lievando a su formaci6n usando la aproximaci6n impulsiva. Los resultados indican la existencia de una relaci6n caracteristica en base del camblo de la energia interna durante la colisi6n, cual determina el tipo de la galaxia peculiar formado. La relacion es analisada y valores criticos del camblo de Ia energia interna, ilevando a la interacci6n entre galaxias de varias intensidades y la formaci6n consecuente de varios tipos de sistemas peculiares es discutido. ABSTRACT. A study of the formation of different types of peculiar (interacting) galaxies is conducted based on the dynamics of the collision leading to their formation, using the impulsive approximation. Results indicate the existance of a characteristic relationship, based on the internal energy changes during the collision, governing the type of peculiar galaxy formed. The relationship is analysed and critical values of internal energy changes, leading to galaxy interaction of varying intensities and consequent formation of different types of peculiar galaxies is discussed. Key words: GALAXIES-DYNAMICS -- GALAXIES-FORMATION

  20. The formation and dynamical evolution of young star clusters

    CERN Document Server

    Fujii, Michiko

    2015-01-01

    Recent observations have revealed a variety of young star clusters, including embedded systems, young massive clusters, and associations. We study the formation and dynamical evolution of these clusters using a combination of simulations and theoretical models. Our simulations start with a turbulent molecular cloud that collapses under its own gravity. The stars are assumed to form in the densest regions in the collapsing cloud after an initial free-fall times of the molecular cloud. The dynamical evolution of these stellar distributions are continued by means of direct $N$-body simulations. The molecular clouds typical for the Milky Way Galaxy tend to form embedded clusters which evolve to resemble open clusters. The associations were initially considerably more clumpy, but lost their irregularity in about a dynamical time scale due to the relaxation process. The densest molecular clouds, which are absent in the Milky Way but are typical in starburst galaxies, form massive young star clusters. They indeed ar...

  1. Dynamically Multivalued Self-Organisation and Probabilistic Structure Formation Processes

    CERN Document Server

    Kirilyuk, A P

    2004-01-01

    The unreduced, universally nonperturbative analysis of arbitrary many-body interaction process reveals the irreducible, purely dynamic source of randomness. It leads to the universal definition of real system complexity (physics/9806002), where the internally chaotic self-organisation emerges as a limiting case of complex interaction dynamics (physics/0211071). It extends also the concept of "self-organised criticality" and corresponds to formation of distinct enough (but always internally chaotic) structures occurring if the system is far from characteristic frequency resonances. Transition to the opposite limiting regime of multivalued interaction dynamics, that of uniform (global) chaos, takes place around the main frequency resonance(s), which provides the absolutely universal criterion of global chaos onset, applicable to any kind of system, as well as the new, extended interpretation of the phenomenon of resonance itself. As a result, one obtains the causally complete description of world structure emer...

  2. Evidence for microbial activity in the formation of carbonate-hosted Zn-Pb deposits

    Science.gov (United States)

    Kucha, H.; Raith, J.

    2009-04-01

    *Kucha H **Raith J *University of Mining and Metallurgy, Faculty of Geology, Geophysics and Environmental Protection, Mickiewicza 30, PL-30-059 Krakow, Poland. ** University of Leoben, Department of Applied Geosciences and Geophysics, A-8700 Leoben, Peter Tunner Str. 5, Austria Evidence for microbial activity in the formation of carbonate-hosted Zn-Pb deposits To date evaluation of bacterial processes in the formation of carbonate-hosted Zn-Pb deposits is largely based on sulphur isotope evidence. However, during a past few years, textural criteria, have been established, which support the bacterial origin of many of these deposits. This has received a strong support from micro-, and nano-textures of naturally growing bacterial films in a flooded tunnel within carbonates that host the Piquette Zn-Pb deposit (Druschel et al., 2002). Bacterial textures, micro- and nano textures found in carbonate-hosted Zn-Pb deposits are: i)wavy bacterial films up to a few mm thick to up to a few cm long composed of peloids, ii)semimassive agglomeration of peloids in the carbonate matrix, and iii)solitary peloids dispersed in the carbonate matrix. Peloids are usually composed of a distinct 50-90um core most often made up of Zn-bearing calcite surrounded by 30-60um thick dentate rim composed of ZnS. Etching of Zn-carbonate cores reveals 1 - 2um ZnS filaments, and numerous 15 to 90nm large ZnS nano-spheres (Kucha et al., 2005). In massive ore composite Zn-calcite - sphalerite peloids are entirely replaced by zinc sulphide, and form peloids ghosts within banded sulphide layers. Bacterially derived micro- and nano-textures have been observed in the following carbonate-hosted Zn-Pb deposits: 1)Irish-type Zn-Pb deposits. In the Navan deposit the basic sulphur is isotopically light bacteriogenic S (Fallick at al., 2001). This is corroborated by semimassive agglomerations of composite peloids (Zn-calcite-ZnS corona or ZnS core-melnikovite corona). Etching of Zn-calcite core reveals globular

  3. STUDY OF DYNAMIC MECHANICAL PROPERTIES OF FUSED DEPOSITION MODELLING PROCESSED ULTEM MATERIAL

    OpenAIRE

    Adhiyamaan Arivazhagan; Ammar Saleem; S. H. Masood; Mostafa Nikzad; K. A. JAGADEESH

    2014-01-01

    Fused Deposition Modelling (FDM), a renowned Rapid Prototyping (RP) process, has been successfully implemented in several industries to fabricate concept models and prototypes for rapid manufacturing. This study furnishes terse notes about the material damping properties of FDM made ULTEM samples considering the effect of FDM process parameters. Dynamic Mechanical Analysis (DMA) is carried out using DMA 2980 equipment to study the dynamic response of the FDM material subjected to single canti...

  4. Three-dimensional computational fluid dynamics simulations of particle deposition in the tracheobronchial tree.

    Science.gov (United States)

    Isaacs, Kristin K; Schlesinger, R B; Martonen, Ted B

    2006-01-01

    Simulation of the dynamics and disposition of inhaled particles within human lungs is an invaluable tool in both the development of inhaled pharmacologic drugs and the risk assessment of environmental particulate matter (PM). The goal of the present focused study was to assess the utility of three-dimensional computational fluid dynamics (CFD) models in studying the local deposition patterns of PM in respiratory airways. CFD models were validated using data from published experimental studies in human lung casts. The ability of CFD to appropriately simulate trends in deposition patterns due to changing ventilatory conditions was specifically addressed. CFD simulations of airflow and particle motion were performed in a model of the trachea and main bronchi using Fluent Inc.'s FIDAP CFD software. Particle diameters of 8 microm were considered for input flow rates of 15 and 60 L/min. CFD was able to reproduce the observed spatial heterogeneities of deposition within the modeled bifurcations, and correctly predicted the "hot-spots" of particle deposition on carinal ridges. The CFD methods also predicted observed differences in deposition for high-versus-low flow rates. CFD models may provide an efficient means of studying the complex effects of airway geometry, particle characteristics, and ventilatory parameters on particle deposition and therefore aid in the design of human subject experiments.

  5. LDA and molecular dynamics determination of Ag deposition onto (1 0 0) surfaces in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mazzone, A.M

    2003-03-20

    This study analyzes the effects of the surface morphology on the deposition of Ag onto Si using LDA and isothermal molecular dynamics. The (1 0 0) silicon surface has either a bulk termination or the dimerization pattern experimentally observed. Small clusters representing a section of these surfaces have been used in LDA calculations to find preferred adsorption sites. Isothermal molecular dynamics describe the motions of the diffusing adatoms in a temperature range from T=10 to 1000 K. Both calculations indicate that Ag and Si do not mix and the deposited structure is formed by linear chains located in the trench between surface atoms. However, MD calculations show that, due to the relaxation of the surface and to thermal lattice vibrations, the stable state of the deposited atoms may considerably differ from the one calculated from LDA. This result has both a practical and a methodological significance.

  6. Factors controlling alkali salt deposition in recovery boilers - particle formation and deposition; Soodakattilan likaantuminen ja siihen vaikuttavien tekijoeiden hallinta - hiukkasten muodostuminen ja depositio

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, E.I.; Mikkanen, P.; Ylaetalo, S. [VTT Chemistry, Espoo (Finland); Jokiniemi, J.K.; Lyyraenen, J.; Pyykoenen, J.; Saastamoinen, J. [VTT Energy, Espoo (Finland)

    1996-12-01

    In this project, the aim was to find out those critical factors that control the deposit formation in the recovery boilers. We focus on the particle formation, growth and deposition as well as the single black liquor particle combustion behaviour. The final goal is the development of the predictive model to be used to describe deposit growth and subsequent behaviour as well as the dependence of deposition on black liquor characteristics and boiler operation conditions. During year 1995 an experimental study on the aerosol particle formation within the recovery boiler furnace and a sensitivity study with the Aerosol Behaviour in Combustion (ABC) code were carried out. The experimental study confirmed the fact that the particles are already formed in the recovery boiler furnace. The particle formation is initiated in the boundary layer of the burning droplet or smelt bed, where metals are vaporised and oxidised to form tiny seed particles. Trace amounts of metals were measured in all particle sizes and the sensitivity study with the ABC model gave further evidence of the seed formation was necessary primary step in the particle formation. At the furnace outlet the sintration ratio and the sulfation ratio of the particles were dependent on the furnace temperature and the residence time in the furnace. At ESP inlet three types of particles were observed (1) fine particles with the major mass mode at about 1-2 {mu}m, (2) large agglomerates in sizes larger than 8 {mu}m, and (3) spherical particles about 2-4 {mu}m in size. The fine particles were formed from vapours and the large agglomerates were formed from fine particles agglomerated on heat exchanger surfaces and re-entrained back to flue gas flow. The large agglomerates also contain vapours that have directly condensed to surfaces. The large spherical particles contain silicon and pass the process almost unchanged. (Abstract Truncated)

  7. Ice Formation via Deposition Mode Nucleation on Bare and Alcohol-covered Graphite Surfaces

    CERN Document Server

    Kong, Xiangrui; Thomson, Erik S; Pettersson, Jan B C

    2013-01-01

    Deposition of water on aerosol particles contributes to ice cloud formation in the atmosphere with implications for the water cycle and climate on Earth. The heterogeneous ice nucleation process is influenced by physico-chemical properties of the substrate, but the mechanisms remain incompletely understood. Here, we report on ice formation on bare and alcohol-covered graphite at temperatures from 175 to 213 K, probed by elastic helium and light scattering. Water has a low wettability on bare and butanol-covered graphite resulting in the growth of rough ice surfaces. In contrast, pre-adsorbed methanol provides hydrophilic surface sites and results in the formation of smooth crystalline ice; an effect that is pronounced also for sub-monolayer methanol coverages. The alcohols primarily reside at the ice surface and at the ice-graphite interface with a minor fraction being incorporated into the growing ice structures. Methanol has no observable effect on gas/solid water vapor exchange whereas butanol acts as a tr...

  8. The Dynamics of Coalition Formation on Complex Networks

    Science.gov (United States)

    Auer, S.; Heitzig, J.; Kornek, U.; Schöll, E.; Kurths, J.

    2015-08-01

    Complex networks describe the structure of many socio-economic systems. However, in studies of decision-making processes the evolution of the underlying social relations are disregarded. In this report, we aim to understand the formation of self-organizing domains of cooperation (“coalitions”) on an acquaintance network. We include both the network’s influence on the formation of coalitions and vice versa how the network adapts to the current coalition structure, thus forming a social feedback loop. We increase complexity from simple opinion adaptation processes studied in earlier research to more complex decision-making determined by costs and benefits, and from bilateral to multilateral cooperation. We show how phase transitions emerge from such coevolutionary dynamics, which can be interpreted as processes of great transformations. If the network adaptation rate is high, the social dynamics prevent the formation of a grand coalition and therefore full cooperation. We find some empirical support for our main results: Our model develops a bimodal coalition size distribution over time similar to those found in social structures. Our detection and distinguishing of phase transitions may be exemplary for other models of socio-economic systems with low agent numbers and therefore strong finite-size effects.

  9. Zinc oxide Chemical Bath Deposition on Functionalized organic thin films: Formation of nanorods, nanorockets and nanoflowers

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhiwei; Walker, Amy V., E-mail: amy.walker@utdallas.edu

    2016-05-01

    Controlling the morphology of nanostructured materials is critical for their use in technological applications including in sensing, electronics and energy harvesting. In this paper we investigate the reaction pathways involved and their dependence on reactant concentrations in the formation of ZnO nanomaterials on –COOH terminated self-assembled monolayers using a simple chemical bath deposition process which employs zinc acetate, which acts as the Zn source, and ethylenediamine, which acts as both the O source and a complexing agent for Zn{sup 2+}. At a deposition temperature of 318 K (45 °C) our data shows that the concentration of Zn{sup 2+} as well as the deposition bath pH, which is controlled by the ethylenediamine concentration, is critical in determining the ZnO morphology. Above 0.01 M zinc acetate at low bath pH (~ 7.7–8.5), nanorods and nanorockets are observed to form. The nanorods exhibit a clear interface in the middle indicating that they are composed of two crystals. At lower zinc acetate concentrations over a wide pH range (~ 8.0–10.5) nanoflowers form. The nanorockets and nanoflowers grow via a modified La Mer mechanism in which there are multiple nucleation and crystallization steps. The initial nuclei are sphelurites (nanoflowers) or nanocrystallites (nanorockets). Since the reagent concentrations limit the reaction, for these initial precursor crystallites to increase in size, it is required dissolution and re-precipitation must occur. Thus at later times nanorockets or nanoflowers develop. - Highlights: • Nanorods, nanorockets and nanoflowers form depending on the reaction conditions. • Nanorods grow slowly suggesting low supersaturation conditions are needed. • Nanoflowers and nanorockets form via multiple nucleation and precipitation steps.

  10. The layered subsurface - periglacial slope deposits as crucial elements for soil formation and variability

    Science.gov (United States)

    Völkel, Jörg; Huber, Juliane

    2014-05-01

    Still most concepts of soil formation, weathering production rates and weathering front ideas are dealing with a monolayered near-surface underground and subsoil. At best a line is given on so-called moved regolith. In fact the subsurface is often characterized by stratified and multilayered slope deposits with thicknesses exceeding 1 m. These stratified slope sediments play a significant role in the nature of the physical and chemical properties as well as on soil forming processes. Examples are given for sediment sourced chemical elements and common clay minerals, and the significance of slope sediments as both barriers and pathways for interflow that moves through the stratified sediments. The stratified subsurface is often datable by numeric age techniques (OSL) showing up how sediment features contradict weathering effects and meaning e.g. for soil genesis. In the mid latitudes, geomorphic and sedimentologic evidence supports a periglacial origin, involving solifluction, for the origin of these slope deposits. The study areas are situated within the Colorado Front Range, U.S. and the Bavarian Forest, Germany. The projects are currently financed and supported by the German Science Foundation DFG. Literature: Völkel, J., Huber, J. & Leopold, M. (2011): Significance of slope sediments layering on physical characteristics and interflow within the Critical Zone… - Applied Geochemistry 26: 143-145.

  11. Physicochemical Conditions during the Formation of Dalingkou Ag—Pb—Zn Deposit,Zhejiang Province

    Institute of Scientific and Technical Information of China (English)

    魏元柏; 陈武

    1993-01-01

    On the basis of mineral paragenesis and the chemistry and homogenization temperatures of fluid inclusions,the physicochemical parameters were calculated for the formation of the Dalingkou Ag-Pb-Zu deposit in Zhejiang.From the early to the late stage of mineralization the ore-forming temperature veriation was found to be 298.5 ℃→267.0℃→217.6℃→167.3℃,with a corresponding pH change of 3.0-5.8→6.1→6.7→5.0→7.3.The pressure changed from 403.8to 128.5atm,and logfS2-9.9→-11.2→-44.2;and logf CO2 around -1.55.In conjunction with geological observations.the deposit is considered to be of meso-epithermal origin,i.e.,it was formed after continental volcanic-subvolcanic activity.The major factors affecting ore precipitation are the decreasing temperature and the increasing pH of ore-forming solutions.

  12. A Study on Reactive Spray Deposition Technology Processing Parameters in the Context of Pt Nanoparticle Formation

    Science.gov (United States)

    Roller, Justin M.; Maric, Radenka

    2015-12-01

    Catalytic materials are complex systems in which achieving the desired properties (i.e., activity, selectivity and stability) depends on exploiting the many degrees of freedom in surface and bulk composition, geometry, and defects. Flame aerosol synthesis is a process for producing nanoparticles with ample processing parameter space to tune the desired properties. Flame dynamics inside the reactor are determined by the input process variables such as solubility of precursor in the fuel; solvent boiling point; reactant flow rate and concentration; flow rates of air, fuel and the carrier gas; and the burner geometry. In this study, the processing parameters for reactive spray deposition technology, a flame-based synthesis method, are systematically evaluated to understand the residence times, reactant mixing, and temperature profiles of flames used in the synthesis of Pt nanoparticles. This provides a framework for further study and modeling. The flame temperature and length are also studied as a function of O2 and fuel flow rates.

  13. Dominant formation of the microsized carbon coils by a short time SF6 flow incorporation during the initial deposition stage.

    Science.gov (United States)

    Jeon, Young-Chul; Yi, Soung Soo; Kim, Sung-Hoon

    2013-08-01

    By SF6 gas incorporation for relatively short time during the initial deposition stage, carbon coils could be formed on nickel catalyst layer-deposited silicon oxide substrate using C2H2 and H2 as source gases under thermal chemical vapor deposition system. The characteristics (formation density and morphology) of as-grown carbon coils were investigated as a function of SF6 flow injection time. 5-min SF6 flow injection time is appropriate to produce the dominant microsized geometry for carbon coils without the appearance of the nanosized carbon coils. The geometry for the microsized carbon coils follows a typical double-helix structure and the shape of the rings constituting the coils is a flat-type. Fluorine's intrinsic etching characteristics for the nanosized carbon coils during the initial deposition stage seems to be the cause for the dominant formation of the microsized carbon coils in the case of 5-min SF6 flow injection time.

  14. Pattern formation and coexistence domains for a nonlocal population dynamics

    CERN Document Server

    da Cunha, J A R; Oliveira, F A

    2011-01-01

    In this communication we propose a most general equation to study pattern formation for one-species population and their limit domains in systems of length L. To accomplish this we include non-locality in the growth and competition terms where the integral kernels are now depend on characteristic length parameters alpha and beta. Therefore, we derived a parameter space (alpha,beta) where it is possible to analyze a coexistence curve alpha*=alpha*(\\beta) which delimits domains for the existence (or not) of pattern formation in population dynamics systems. We show that this curve has an analogy with coexistence curve in classical thermodynamics and critical phenomena physics. We have successfully compared this model with experimental data for diffusion of Escherichia coli populations.

  15. Finite size effects in the dynamics of opinion formation

    CERN Document Server

    Toral, R; Tessone, Claudio J.; Toral, Raul

    2006-01-01

    For some models of relevance in the social sciences we review some examples in which system size plays an important role in the final outcome of the dynamics. We discuss the conditions under which changes of behavior can appear only when the number of agents in the model takes a finite value. Those changes of behavior can be related to the apparent phase transitions that appear in some physical models. We show examples in the Galam's model of opinion transmission and the Axelrod's model of culture formation stressing the role that the network of interactions has on the main results of both models. Finally, we present the phenomenon of system-size stochastic resonance by which a forcing signal (identified as an advertising agent) is optimally amplified by a population of the right (intermediate) size. Our work stresses the role that the system size has in the dynamics of social systems and the inappropriateness of taking the thermodynamic limit for these systems.

  16. The Origin of the Terra Meridiani Sediments: Volatile Transport and the Formation of Sulfate Bearing Layered Deposits on Mars

    Science.gov (United States)

    Niles, P.B.

    2008-01-01

    The chemistry, sedimentology, and geology of the Meridiani sedimentary deposits are best explained by eolian reworking of the sublimation residue of a large scale ice/dust deposit. This large ice deposit was located in close proximity to Terra Meridiani and incorporated large amounts of dust, sand, and SO2 aerosols generated by impacts and volcanism during early martian history. Sulfate formation and chemical weathering of the initial igneous material is hypothesized to have occurred inside of the ice when the darker mineral grains were heated by solar radiant energy. This created conditions in which small films of liquid water were created in and around the mineral grains. This water dissolved the SO2 and reacted with the mineral grains forming an acidic environment under low water/rock conditions. Subsequent sublimation of this ice deposit left behind large amounts of weathered sublimation residue which became the source material for the eolian process that deposited the Terra Meridiani deposit. The following features of the Meridiani sediments are best explained by this model: The large scale of the deposit, its mineralogic similarity across large distances, the cation-conservative nature of the weathering processes, the presence of acidic groundwaters on a basaltic planet, the accumulation of a thick sedimentary sequence outside of a topographic basin, and the low water/rock ratio needed to explain the presence of very soluble minerals and elements in the deposit. Remote sensing studies have linked the Meridiani deposits to a number of other martian surface features through mineralogic similarities, geomorphic similarities, and regional associations. These include layered deposits in Arabia Terra, interior layered deposits in the Valles Marineris system, southern Elysium/Aeolis, Amazonis Planitia, and the Hellas basin, Aram Chaos, Aureum Chaos, and Ioni Chaos. The common properties shared by these deposits suggest that all of these deposits share a common

  17. Building better oscillators using nonlinear dynamics and pattern formation

    Indian Academy of Sciences (India)

    M C Cross; Eyal Kenig; John-Mark A Allen

    2015-03-01

    Frequency and time references play an essential role in modern technology and in living systems. The precision of self-sustained oscillations is limited by the effects of noise, which becomes evermore important as the sizes of the devices become smaller. In this paper, we review our recent theoretical results on using nonlinear dynamics and pattern formation to reduce the effects of noise and improve the frequency precision of oscillators, with particular reference to ongoing experiments on oscillators based on nanomechanical resonators. We discuss using resonator nonlinearity, novel oscillator architectures and the synchronization of arrays of oscillators, to improve the frequency precision.

  18. Nonlinear dynamic theory for photorefractive phase hologram formation

    Science.gov (United States)

    Kim, D. M.; Shah, R. R.; Rabson, T. A.; Tittle, F. K.

    1976-01-01

    A nonlinear dynamic theory is developed for the formation of photorefractive volume phase holograms. A feedback mechanism existing between the photogenerated field and free-electron density, treated explicitly, yields the growth and saturation of the space-charge field in a time scale characterized by the coupling strength between them. The expression for the field reduces in the short-time limit to previous theories and approaches in the long-time limit the internal or photovoltaic field. Additionally, the phase of the space charge field is shown to be time-dependent.

  19. Dynamic Cell Formation based on Multi-objective Optimization Model

    Directory of Open Access Journals (Sweden)

    Guozhu Jia

    2013-08-01

    Full Text Available In this paper, a multi-objective model is proposed to address the dynamic cellular manufacturing (DCM formation problem. This model considers four conflicting objectives: relocation cost, machine utilization, material handling cost and maintenance cost. The model also considers the situation that some machines could be shared by more than one cell at the same period. A genetic algorithm is applied to get the solution of this mathematical model. Three numerical examples are simulated to evaluate the validity of this model.  

  20. Mechanical compaction directly modulates the dynamics of bile canaliculi formation.

    Science.gov (United States)

    Wang, Yan; Toh, Yi-Chin; Li, Qiushi; Nugraha, Bramasta; Zheng, Baixue; Lu, Thong Beng; Gao, Yi; Ng, Mary Mah Lee; Yu, Hanry

    2013-02-01

    Homeostatic pressure-driven compaction is a ubiquitous mechanical force in multicellular organisms and is proposed to be important in the maintenance of multicellular tissue integrity and function. Previous cell-free biochemical models have demonstrated that there are cross-talks between compaction forces and tissue structural functions, such as cell-cell adhesion. However, its involvement in physiological tissue function has yet to be directly demonstrated. Here, we use the bile canaliculus (BC) as a physiological example of a multicellular functional structure in the liver, and employ a novel 3D microfluidic hepatocyte culture system to provide an unprecedented opportunity to experimentally modulate the compaction states of primary hepatocyte aggregates in a 3D physiological-mimicking environment. Mechanical compaction alters the physical attributes of the hepatocyte aggregates, including cell shape, cell packing density and cell-cell contact area, but does not impair the hepatocytes' remodeling and functional capabilities. Characterization of structural and functional polarity shows that BC formation in compact hepatocyte aggregates is accelerated to as early as 12 hours post-seeding; whereas non-compact control requires 48 hours for functional BC formation. Further dynamic immunofluorescence imaging and gene expression profiling reveal that compaction accelerated BC formation is accompanied by changes in actin cytoskeleton remodeling dynamics and transcriptional levels of hepatic nuclear factor 4α and Annexin A2. Our report not only provides a novel strategy of modeling BC formation for in vitro hepatology research, but also shows a first instance that homeostatic pressure-driven compaction force is directly coupled to the higher-order multicellular functions.

  1. Dynamics of particle loading in deep-bed filter. Transport, deposition and reentrainment

    Directory of Open Access Journals (Sweden)

    Przekop Rafał

    2016-09-01

    Full Text Available Deep bed filtration is an effective method of submicron and micron particle removal from the fluid stream. There is an extensive body of literature regarding particle deposition in filters, often using the classical continuum approach. However, the approach is not convenient for studying the influence of particle deposition on filter performance (filtration efficiency, pressure drop when non-steady state boundary conditions have to be introduced. For the purposes of this work the lattice-Boltzmann model describes fluid dynamics, while the solid particle motion is modeled by the Brownian dynamics. For aggregates the effect of their structure on displacement is taken into account. The possibility of particles rebound from the surface of collector or reentrainment of deposits to fluid stream is calculated by energy balanced oscillatory model derived from adhesion theory. The results show the evolution of filtration efficiency and pressure drop of filters with different internal structure described by the size of pores. The size of resuspended aggregates and volume distribution of deposits in filter were also analyzed. The model enables prediction of dynamic filter behavior. It can be a very useful tool for designing filter structures which optimize maximum lifetime with the acceptable values of filtration efficiency and pressure drop.

  2. Redox-Controled Preservation of Mediterranean Sapropel S1 deposits during Formation and Interruption

    Science.gov (United States)

    De Lange, Gert J.; Filippidi, Amalia; Goudeau, Marie-Louise; Hennekam, Rick

    2016-04-01

    Organic-rich units (sapropels) occur in Mediterraneran sediments in a repetitive, climate-controled way. Their deposition is thought to be precession-related and to be associated with humid climate conditions. The last humid period from 11 - 5 kyr 14C ago, occurred simultaneous with a sustained circum-Mediterranean wet period and vegetated Sahara. Within that period, the most recent sapropel (S1) formed synchronously between 9.8 and 5.7 14C ky BP at all water depths greater than a few hundred metres. As a consequence of increased fresh water (monsoon) input, surface waters had a reduced salinity and concomitantly the deep (> 1.8 km) eastern Mediterranean Sea was devoid of oxygen during 4,000 years of S1 formation. This has resulted in a differential basin-wide preservation of S1sediments determined by water depth, as a result of different ventilation/climate-related redox conditions above and below 1.8 km. The end of this period is marked by a basin-wide high sedimentary manganese-oxide peak that represents an abrupt re-ventilation of the deep-water at 5.7 kyr. The sustaining oxic conditions thereafter have resulted in a downward progressing oxidation-front that is not only characterized by the degradation of most organic matter over its active pathway, but also by the built-up of manganese oxide. The latter has resulted in a secondary diagenetic Mn-peak below the first, upper, ventilation Mn-peak. Apart from the major re-ventilation event at the end of sapropel S1 formation, also other, short-term ventilation events appear to have occurred during its formation, notably during the 8.2 ka event. This potentially basin-wide event is particularly noticeable at relatively shallow near-coastal sites of high sedimentation rates. It marks a brief episode of not only re-oxygenated deep water thus reduced preservation, but also decreased primary productivity thus nutrient supply. This 8.2 cal ka BP interruption event is thought to be related to enhanced deep water formation

  3. Formation of Metal Nano- and Micropatterns on Self-Assembled Monolayers by Pulsed Laser Deposition Through Nanostencils and Electroless Deposition

    NARCIS (Netherlands)

    Speets, Emiel A.; Riele, te Paul; Boogaart, van den Marc A.F.; Doeswijk, Lianne M.; Ravoo, Bart Jan; Rijnders, Guus; Brugger, Jürgen; Reinhoudt, David N.; Blank, Dave H.A.

    2006-01-01

    Patterns of noble-metal structures on top of self-assembled monolayers (SAMs) on Au and SiO2 substrates have been prepared following two approaches. The first approach consists of pulsed laser deposition (PLD) of Pt, Pd, Au, or Cu through nano- and microstencils. In the second approach, noble-metal

  4. Dynamic order reduction of thin-film deposition kinetics models: A reaction factorization approach

    Energy Technology Data Exchange (ETDEWEB)

    Adomaitis, Raymond A., E-mail: adomaiti@umd.edu [Department of Chemical and Biomolecular Engineering, Institute for Systems Research, University of Maryland, College Park, Maryland 20742 (United States)

    2016-01-15

    A set of numerical tools for the analysis and dynamic dimension reduction of chemical vapor and atomic layer deposition (ALD) surface reaction models is developed in this work. The approach is based on a two-step process where in the first, the chemical species surface balance dynamic equations are factored to effectively decouple the (nonlinear) reaction rates, a process that eliminates redundant dynamic modes and that identifies conserved quantities. If successful, the second phase is implemented to factor out redundant dynamic modes when species relatively minor in concentration are omitted; if unsuccessful, the technique points to potential model structural problems. An alumina ALD process is used for an example consisting of 19 reactions and 23 surface and gas-phase species. Using the approach developed, the model is reduced by nineteen modes to a four-dimensional dynamic system without any knowledge of the reaction rate values. Results are interpreted in the context of potential model validation studies.

  5. Strain and structure in nano Ag films deposited on Au: Molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zientarski, Tomasz, E-mail: martom@dyzio.umcs.lublin.pl [Department for the Modelling of Physico-Chemical Processes, Maria Curie-Skłodowska University, ul. Gliniana 33, 20-614 Lublin (Poland); Chocyk, Dariusz [Department of Applied Physics, Lublin University of Technology, ul. Nadbystrzycka 38, 20-618 Lublin (Poland)

    2014-07-01

    Molecular dynamics simulations are applied to analyze the stress and structure of nano Ag thin films deposited on the Au substrate. The interactions in the system are described by the embedded atom method. The kinematical theory of scattering is employed to identify the structure obtained from simulations data. Results shows that the silver layers are adjusted to the crystalline lattice of the gold buffer layers, and during the deposition process only compressive stress is observed. In all the cases the distribution of stress does not depend on temperature.

  6. Formation of magnesite and siderite deposits in the Southern Urals—evidence of inclusion fluid chemistry

    Science.gov (United States)

    Prochaska, W.; Krupenin, M.

    2013-02-01

    World-class deposits of magnesite and siderite occur in Riphean strata of the Southern Urals, Russia. Field evidence, inclusion fluid chemistry, and stable isotope data presented in this study clearly proof that the replacement and precipitation processes leading to the formation of the epigenetic dolomite, magnesite and hydrothermal siderite were genetically related to evaporitic fluids affecting already lithified rocks. There is, however, a systematic succession of events leading to the formation of magnesite in a first stage. After burial and diagenesis the same brines were modified to hot and reducing hydrothermal fluids and were the source for the formation of hydrothermal siderite. The magnesites of the Satka Formation as well as the magnesites and the siderites of the Bakal Formation exhibit low Na/Br (106 to 222) and Cl/Br (162 to 280) ratios plotting on the seawater evaporation trend, indicating that the fluids acquired their salinity by evaporation processes of seawater. Temperature calculations based on cation exchange thermometers indicate a formation temperature of the magnesites of ~ 130 °C. Considering the fractionation at this temperature stable isotope evidence shows that the magnesite forming brines had δ18OSMOW values of ~ +1 ‰ thus indicating a seawater origin of the original fluid. Furthermore it proves that these fluids were not yet affected by appreciable fluid-rock interaction, which again implies magnesite formation in relatively high crustal levels. In contrast to the magnesites, the siderite mineralization was caused by hydrothermal fluids that underwent more intense reactions with their host rocks in deeper crustal levels compared to the magnesite. The values of 87Sr /86Sr in the siderites are substantially higher compared to the host rock slates. They also exceed the 87Sr /86Sr ratios of the magnesites and the host rock limestones indicating these slates as the source of iron as a consequence of water-rock interaction. The siderites

  7. Laser ablation source for formation and deposition of size-selected metal clusters.

    Science.gov (United States)

    Vucković, S; Svanqvist, M; Popok, V N

    2008-07-01

    This work describes construction of a source and optimisation of its parameters for production of cluster ion beams using material ablation by the second harmonic of a Nd:YAG laser (532 nm). The influence of different source parameters such as carrier gas pressure, laser power, delay time between gas, and laser pulses as well as nozzle configuration on the cluster formation are studied. For the current experiments the laser ablation cluster source was optimized for production of Con+ cluster ions. Clusters with n up to 150 atoms are registered by a time-of-flight mass spectrometer. Deposition of size-selected Co50+ clusters with kinetic energies in the interval of 250-4850 eV/cluster on highly ordered pyrolytic graphite is studied. At the highest impact energies the clusters are implanted. Craters and well-like structures can be seen by scanning tunneling microscopy at impact spots. A decrease in cluster kinetic energy leads to formation of bumplike structures which probably represent damaged graphite areas with incorporated Co atoms. Further decrease in the cluster impact energy to the level of 450-250 eV/cluster creates condition for so-called cluster pinning when the cluster constituents are intact but the energy transferred to the graphite is still enough to produce radiation defects to which the cluster is bound.

  8. Molecular dynamics study of the primary ferrofluid aggregate formation

    Energy Technology Data Exchange (ETDEWEB)

    Tanygin, B.M., E-mail: b.m.tanygin@gmail.com [Radiophysics Department, Taras Shevchenko Kyiv National University, 4G, Acad. Glushkov Ave., Kyiv UA-03127 (Ukraine); Kovalenko, V.F.; Petrychuk, M.V.; Dzyan, S.A. [Radiophysics Department, Taras Shevchenko Kyiv National University, 4G, Acad. Glushkov Ave., Kyiv UA-03127 (Ukraine)

    2012-11-15

    Investigations of the phase transitions and self-organization in the magnetic aggregates are of the fundamental and applied interest. The long-range ordering structures described in the Tomanek's systematization (M. Yoon, and D. Tomanek, 2010 ) are not yet obtained in the direct molecular dynamics simulations. The resulted structures usually are the linear chains or circles, or, else, amorphous (liquid) formations. In the present work, it was shown, that the thermodynamically equilibrium primary ferrofluid aggregate has either the long-range ordered or liquid phase. Due to the unknown steric layer force and other model idealizations, the clear experimental verification of the real equilibrium phase is still required. The predicted long-range ordered (crystallized) phase produces the faceting shape of the primary ferrofluid aggregate, which can be recognized experimentally. The medical (antiviral) application of the crystallized aggregates has been suggested. Dynamic formation of all observed ferrofluid nanostructures conforms to the Tomanek's systematization. - Highlights: Black-Right-Pointing-Pointer Primary ferrofluid aggregate has either the long-range ordered or liquid phase. Black-Right-Pointing-Pointer Simulation of ferrofluid nanostructures conforms to the Tomanek's systematization. Black-Right-Pointing-Pointer Long-range ordered phase produces the faceting shape. Black-Right-Pointing-Pointer The medical (antiviral) application is possible.

  9. The Formation and Dynamics of Super-Earth Planets

    CERN Document Server

    Haghighipour, Nader

    2013-01-01

    Super-Earths, objects slightly larger than Earth and slightly smaller than Uranus, have found a special place in exoplanetary science. As a new class of planetary bodies, these objects have challenged models of planet formation at both ends of the spectrum and have triggered a great deal of research on the composition and interior dynamics of rocky planets in connection to their masses and radii. Being relatively easier to detect than an Earth-sized planet at 1 AU around a G star, super-Earths have become the focus of worldwide observational campaigns to search for habitable planets. With a range of masses that allows these objects to retain moderate atmospheres and perhaps even plate tectonics, super-Earths may be habitable if they maintain long-term orbits in the habitable zones of their host stars. Given that in the past two years a few such potentially habitable super-Earths have in fact been discovered, it is necessary to develop a deep understanding of the formation and dynamical evolution of these obje...

  10. Dynamics of exciplex formation in rare gas media

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-Lorenzo, German, E-mail: grojas37@gmail.com [Departamento de Fisica General y Matematicas, Instituto Superior de Tecnologias y Ciencias Aplicadas, La Habana (Cuba)] [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rubayo-Soneira, Jesus [Departamento de Fisica General y Matematicas, Instituto Superior de Tecnologias y Ciencias Aplicadas, La Habana (Cuba); Alberti, Sebastian Fernandez [Centro de Estudios e Investigaciones, Universidad Nacional de Quilmes, Roque Saenz Pena 180, Bernal B1876BXD (Argentina)

    2009-07-30

    A hopping-surface algorithm has been used to simulate the dynamics induced in rare gas matrices due to the photoexcitation ({sup 1}S{sub 0} {yields} {sup 3}P{sub 1}) of atomic mercury embedded in them. Especially, the study of the dynamics of an exciplex formation in a model system consisting of solid xenon doped with atomic mercury. The process starts upon the photoexcitation of the Hg atom to its {sup 3}P{sub 1} electronic excited state. Diatomics-in-Molecule approach has been used for constructing the adiabatic potential surfaces. In all trajectories we show that a triatomic Xe-Hg{sup *}-Xe complex is formed, but in two conformations: bent and linear. The mechanisms leading to the formation of one or the other are identified. Mainly, are noted the thermal fluctuations of the Hg impurity and the shape of the potential surfaces. Furthermore, we show that non-radiative intrastate relaxation occurs via a conical intersection between the excited state surfaces. The simulated spectra are in very good agreement with the experimental data.

  11. Araçatuba Formation: palustrine deposits from the initial sedimentation phase of the Bauru Basin

    Directory of Open Access Journals (Sweden)

    Luiz A. Fernandes

    2003-06-01

    Full Text Available The Bauru Basin (Upper Cretaceous accumulated an essentially sandy continental sedimentary sequence. In a first desertic phase the basaltic substratum was covered by a widespread and homogeneous aeolian sand unit with minor loess intercalations. The substratum relief favored the formation of an endorheic drainage system under semi-arid climate, a process that started the development of the Araçatuba Paleoswamp. The palustrine deposits (Araçatuba Formation comprise siltstone and tipically greenish gray narrow tabular strata of sandstone cemented by carbonate. Moulds and gypsite and dolomite pseudomorphs were identified. The moulds seem to be genetically associated with desiccation cracks, root marks and climbing ripple lamination levels, that, on the whole, indicate calm shallow saline waters undergoing phases of subaerial exposition. At the boundaries of the study area, sand units may exhibit sigmoidal features and convolute bedding structure, which is characteristic of marginal deltaic deposits. The Araçatuba Formation is enclosed in and later overlaid by the aeolian deposits of the Vale do Rio do Peixe Formation.A Bacia Bauru (Cretáceo Superior, acumulou uma seqüência sedimentar continental essencialmente arenosa. Numa fase inicial desértica, o seu substrato basáltico foi soterrado por extensa e monótona cobertura de areias eólicas com intercalações subordinadas de depósitos de loesse. O relevo original do substrato favoreceu a formação de uma drenagem regional endorrêica, sob clima semi-árido, propiciando assim condições de formação do Paleopantanal Araçatuba. Os depósitos paludiais (Formação Araçatuba constituem estratos tabulares de siltitos e arenitos de cor cinza claro esverdeado típica, eventualmente cimentados por carbonato de cálcio. Moldes e pseudomorfos de cristais de gipsita e dolomita foram identificados na unidade. Aparentemente, estão associados com gretas de ressecação, marcas de raízes e

  12. Computational fluid dynamics modeling of Bacillus anthracis spore deposition in rabbit and human respiratory airways

    Energy Technology Data Exchange (ETDEWEB)

    Kabilan, S.; Suffield, S. R.; Recknagle, K. P.; Jacob, R. E.; Einstein, D. R.; Kuprat, A. P.; Carson, J. P.; Colby, S. M.; Saunders, J. H.; Hines, S. A.; Teeguarden, J. G.; Straub, T. M.; Moe, M.; Taft, S. C.; Corley, R. A.

    2016-09-01

    Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived respectively from computed tomography (CT) and µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation–exhalation breathing conditions using average species-specific minute volumes. Two different exposure scenarios were modeled in the rabbit based upon experimental inhalation studies. For comparison, human simulations were conducted at the highest exposure concentration used during the rabbit experimental exposures. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the nasal sinus compared to the human at the same air concentration of anthrax spores. In contrast, higher spore deposition was predicted in the lower conducting airways of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology for deposition.

  13. Depositional environments and sequence stratigraphy of the Bahram Formation (middleelate Devonian) in north of Kerman, south-central Iran

    Institute of Scientific and Technical Information of China (English)

    Afshin Hashmie; Ali Rostamnejad; Fariba Nikbakht; Mansour Ghorbanie; Peyman Rezaie; Hossien Gholamalian

    2016-01-01

    This study is focused on sedimentary environments, facies distribution, and sequence stratigraphy. The facies and sequence stratigraphic analyses of the Bahram Formation (middleelate Devonian) in south-central Iran are based on two measured stratigraphic sections in the southern Tabas block. The Bah-ram Formation overlies red sandstones Padeha Formation in sections Hutk and Sardar and is overlain by Carboniferous carbonate deposits of Hutk Formation paraconformably, with a thickness of 354 and 386 m respectively. Mixed siliciclastic and carbonate sediments are present in this succession. The field observations and laboratory studies were used to identify 14 micro/petrofacies, which can be grouped into 5 depositional environments: shore, tidal flat, lagoon, shoal and shallow open marine. A mixed carbonate-detrital shallow shelf is suggested for the depositional environment of the Bahram Formation which deepens to the east (Sardar section) and thins in southern locations (Hutk section). Three 3rd-order cyclic siliciclastic and carbonate sequences in the Bahram Formation and one sequence shared with the overlying joint with Hutk Formation are identified, on the basis of shallowing upward patterns in the micro/pertofacies.

  14. CALCAREOUS PLANKTON BIOSTRATIGRAPHY AND AGE OF THE MIDDLE MIOCENE DEPOSITS OF LONGANO FORMATION (EASTERN MATESE MOUNTAINS, SOUTHERN APENNINES

    Directory of Open Access Journals (Sweden)

    FABRIZIO LIRER

    2005-03-01

    Full Text Available The integrated calcareous plankton biostratigraphy (planktonic foraminifera and calcareous nannofossils and an accurate fieldwork, allowed us the reconstruction of the sedimentary evolution of the Longano Formation (Orbulina Marls. In particular the correlation between the bioevents recognised in the Orbulina Marls sequence and those recorded in astronomically calibrated Middle Miocene sections, offered the possibility to date the passage from the shallow-water Cusano Formation to the deep-water deposits of the Longano Formation at about 13.21 Ma and the successive onset of terrigenous deposits of the Pietraroia Formation at 10.54 Ma. In addition, an high resolution study of the terrigenous sequence, showed that this sedimentary event is not abrupt but it is characterised by a progressive increase, bed by bed, of the siliciclastic fraction up to the deposition of the sandstones. The recognition in all the studied sections of the base of the first Acme (AB1 of Paragloborotalia siakensis dated at 13.21 Ma, just above the phosphate-rich interval (this interval marks the transition between Cusano and Longano Formations, proved that the transgression which led to the deposition of the Orbulina Marls was synchronous in all the south-eastern Matese Mountains. 

  15. Dynamics of biofilm formation during anaerobic digestion of organic waste.

    Science.gov (United States)

    Langer, Susanne; Schropp, Daniel; Bengelsdorf, Frank R; Othman, Maazuza; Kazda, Marian

    2014-10-01

    Biofilm-based reactors are effectively used for wastewater treatment but are not common in biogas production. This study investigated biofilm dynamics on biofilm carriers incubated in batch biogas reactors at high and low organic loading rates for sludge from meat industry dissolved air flotation units. Biofilm formation and dynamics were studied using various microscopic techniques. Resulting micrographs were analysed for total cell numbers, thickness of biofilms, biofilm-covered surface area, and the area covered by extracellular polymeric substances (EPS). Cell numbers within biofilms (10(11) cells ml(-1)) were up to one order of magnitude higher compared to the numbers of cells in the fluid reactor content. Further, biofilm formation and structure mainly correlated with the numbers of microorganisms present in the fluid reactor content and the organic loading. At high organic loading (45 kg VS m(-3)), the thickness of the continuous biofilm layer ranged from 5 to 160 μm with an average of 51 μm and a median of 26 μm. Conversely, at lower organic loading (15 kg VS m(-3)), only microcolonies were detectable. Those microcolonies increased in their frequency of occurrence during ongoing fermentation. Independently from the organic loading rate, biofilms were embedded completely in EPS within seven days. The maturation and maintenance of biofilms changed during the batch fermentation due to decreasing substrate availability. Concomitant, detachment of microorganisms within biofilms was observed simultaneously with the decrease of biogas formation. This study demonstrates that biofilms of high cell densities can enhance digestion of organic waste and have positive effects on biogas production.

  16. Accessing the Impact of Sea-Salt Emissions on Aerosol Chemical Formation and Deposition Over Pearl River Delta, China

    Science.gov (United States)

    Fan, Q.; Wang, X.; Liu, Y.; Wu, D.; Chan, P. W.; Fan, S.; Feng, Y.

    2015-12-01

    Sea-salt aerosol (SSA) emissions have a significant impact on aerosol pollution and haze formation in the coastal areas. In this study, Models-3/CMAQ modeling system was utilized to access the impact of SSA emissions on aerosol chemical formation and deposition over Pearl River Delta (PRD), China in July 2006. More SSAs were transported inland from the open-ocean under the southeast wind in summertime. Two experiments (with and without SSA emissions in the CMAQ model) were set up to compare the modeling results with each other. The results showed that the increase of sulfate concentrations were more attributable to the primary emissions of coarse SO42- particles in SSA, while the increase of nitrate concentrations were more attributable to secondary chemical formations, known as the mechanisms of chloride depletion in SSA. In the coastal areas, 17.62 % of SO42-, 26.6% of NO3- and 38.2% of PM10 were attributed to SSA emissions, while those portions were less than 1% in the inland areas. The increases of PM10 and its components due to SSA emissions resulted in higher deposition fluxes over PRD, particularly in the coastal areas, except for the wet deposition of nitrate. Nitrate was more sensitive to SSA emissions in chemical formations than sulfate and dry deposition of aerosol was also more sensitive than that for wet deposition. Process analysis of sulfate and nitrate was applied to find out the difference of physical and chemical mechanisms between Guangzhou (the inland areas) and Zhuhai (the coastal areas). The negative contributions of dry deposition process to both sulfate and nitrate concentrations increased if SSA emissions were taken into account in the model, especially for Zhuhai. The negative contributions of cloud process also increased due to cloud scavenging and wet deposition process. In the coastal area, the gas-to-particle conversions became more active with high contributions of aerosol process to nitrate concentrations.

  17. Dynamic Modeling for the Design and Cyclic Operation of an Atomic Layer Deposition (ALD Reactor

    Directory of Open Access Journals (Sweden)

    Curtisha D. Travis

    2013-08-01

    Full Text Available A laboratory-scale atomic layer deposition (ALD reactor system model is derived for alumina deposition using trimethylaluminum and water as precursors. Model components describing the precursor thermophysical properties, reactor-scale gas-phase dynamics and surface reaction kinetics derived from absolute reaction rate theory are integrated to simulate the complete reactor system. Limit-cycle solutions defining continuous cyclic ALD reactor operation are computed with a fixed point algorithm based on collocation discretization in time, resulting in an unambiguous definition of film growth-per-cycle (gpc. A key finding of this study is that unintended chemical vapor deposition conditions can mask regions of operation that would otherwise correspond to ideal saturating ALD operation. The use of the simulator for assisting in process design decisions is presented.

  18. Kinetics of SiHCl3 chemical vapor deposition and fluid dynamic simulations.

    Science.gov (United States)

    Cavallotti, Carlo; Masi, Maurizio

    2011-09-01

    Though most of the current silicon photovoltaic technology relies on trichlorosilane (SiHCl3) as a precursor gas to deposit Si, only a few studies have been devoted to the investigation of its gas phase and surface kinetics. In the present work we propose a new kinetic mechanism apt to describe the gas phase and surface chemistry active during the deposition of Si from SiHCl3. Kinetic constants of key reactions were either taken from the literature or determined through ab initio calculations. The capability of the mechanism to reproduce experimental data was tested through the implementation of the kinetic scheme in a fluid dynamic model and in the simulation of both deposition and etching of Si in horizontal reactors. The results of the simulations show that the reactivity of HCl is of key importance in order to control the Si deposition rate. When HCl reaches a critical concentration in the gas phase it starts etching the Si surface, so that the net deposition rate is the net sum of the adsorption rate of the gas phase precursors and the etching rate due to HCl. In these conditions the possibility to further deposit Si is directly related to the rate of consumption of HCl through its reaction with SiHCl3 to give SiCl4. The proposed reaction mechanism was implemented in a 3D fluid dynamic model of a simple Siemens reactor. The simulation results indicate that the proposed interpretation of the growth process applies also to this class of reactors, which operate in what can be defined as a mixed kinetic-transport controlled regime.

  19. Experimental techniques to determine salt formation and deposition in supercritical water oxidation reactors

    Energy Technology Data Exchange (ETDEWEB)

    Chan, J.P.C.; LaJeunesse, C.A.; Rice, S.F.

    1994-08-01

    Supercritical Water Oxidation (SCWO) is an emerging technology for destroying aqueous organic waste. Feed material, containing organic waste at concentrations typically less than 10 wt % in water, is pressurized and heated to conditions above water`s critical point where the ability of water to dissolve hydrocarbons and other organic chemicals is greatly enhanced. An oxidizer, is then added to the feed. Given adequate residence time and reaction temperature, the SCWO process rapidly produces innocuous combustion products. Organic carbon and nitrogen in the feed emerge as CO{sub 2} and N{sub 2}; metals, heteroatoms, and halides appear in the effluent as inorganic salts and acids. The oxidation of organic material containing heteroatoms, such as sulfur or phosphorous, forms acid anions. In the presence of metal ions, salts are formed and precipitate out of the supercritical fluid. In a tubular configured reactor, these salts agglomerate, adhere to the reactor wall, and eventually interfere by causing a flow restriction in the reactor leading to an increase in pressure. This rapid precipitation is due to an extreme drop in salt solubility that occurs as the feed stream becomes supercritical. To design a system that can accommodate the formation of these salts, it is important to understand the deposition process quantitatively. A phenomenological model is developed in this paper to predict the time that reactor pressure begins to rise as a function of the fluid axial temperature profile and effective solubility curve. The experimental techniques used to generate effective solubility curves for one salt of interest, Na{sub 2}SO{sub 4}, are described, and data is generated for comparison. Good correlation between the model and experiment is shown. An operational technique is also discussed that allows the deposited salt to be redissolved in a single phase and removed from the affected portion of the reactor. This technique is demonstrated experimentally.

  20. Reaction path and crystallograpy of cobalt silicide formation on silicon(001) by reaction deposition epitaxy

    Science.gov (United States)

    Lim, Chong Wee

    CaF2-structure CoSi2 layers were formed on Si(001) by reactive deposition epitaxy (RDE) and compared with CoSi2 layers obtained by conventional solid phase growth (SPG). In the case of RDE, CoSi 2 formation occurred during Co deposition at elevated temperature while for SPG, Co was deposited at 25°C and silicidation took place during subsequent annealing. My results demonstrate that RDE CoSi2 layers are epitaxial with a cube-on-cube relationship, 001CoSi2 ‖001Si and 100CoSi2 ‖100 Si . In contrast, SPG films are polycrystalline with a mixed 111/002/022/112 orientation. I attribute the striking difference to rapid Co diffusion during RDE for which the high Co/Si reactivity gives rise to a flux-limited reaction resulting in the direct formation of the disilicide phase. Initial formation of CoSi2(001) follows the Volmer-Weber mode with two families of island shapes: inverse pyramids and platelets. The rectangular-based pyramidal islands extend along orthogonal directions, bounded by four {111} CoSi2/Si interfaces, and grow with a cube-on-cube orientation with respect to Si(001). Platelet-shaped islands are bounded across their long directions by {111} twin planes and their narrow directions by 511CoSi2 ‖111Si interfaces. The top and bottom surfaces are {22¯1}, with 22¯1 CoSi2‖001 Si , and {1¯1¯1}, with 1¯1¯ 1CoSi2‖ 11¯1Si , respectively. The early stages of film growth (tCo ≤ 13 A) are dominated by the twinned platelets due to a combination of higher nucleation rates and rapid elongation along preferred directions. However, at tCo ≥ 13 A, island coalescence becomes significant as orthogonal platelets intersect and block elongation along fast growth directions. Further island growth becomes dominated by the untwinned islands. I show that high-flux low-energy Ar+ ion irradiation during RDE growth dramatically increases the area fraction of untwinned regions from 0.17 in films grown under standard magnetically balanced conditions in which the ratio

  1. Local natural electric fields - the electrochemical factor of formation of placers and the criterion of prospectings of oil and gas deposits on the Arctic shelf

    Science.gov (United States)

    Kholmiansky, Mikhail; Anokhin, Vladimir; Kholmianskaia, Galina

    2014-05-01

    On the basis litologo-facial, geo- and hydrochemical characteristics of a cross-section lito - and shelf hydrospheres, the estimation of structural features modern and paleostatic local electric fields and their influence on transportation of the suspended mineral material is made. The formula of dynamic carrying over of the ore material which is in a subcolloidal condition under the influence of natural electric field of a shelf is deduced. On a structure of a friable cover and its features on G.I. Teodorovicha's method position of oxidation-reduction border, sign Eh was reconstructed. On the basis of the established dependence between Eh and local substatic electric field of a shelf it was reconstructed paleostatic a field and its influence on the weighed mineral particles was estimated. Influence of local electric field on lithodynamic moving of ore minerals is estimated for a shelf of the Arctic seas of Russia. On the basis of this estimation and data on structure of a friable cover the map of influence of local electric field on sedimentation and transportation of ore minerals for water area of the East Arctic seas of Russia is constructed. For Laptev seas and East-Siberian the areas in which limits local electric field promoted are revealed and promotes formation Holocene placers of an ilmenite, a cassiterite and gold. For Chukchi and the Bering Seas such estimation is made for all friable cover. hydrocarbonic deposits located on water area of the Arctic shelf of the Russian Federation, initiate occurrence of jet auras of dispersion of heavy metals in ground deposits and in a layer of the sea water, blocking these deposits. Intensity of auras and their spatial position is caused by a geological structure of deposits of breeds containing them, lithodynamic and oceanologic factors. On the basis of the theoretical representations developed by M.A.Holmjansky and O.F.Putikova (Holmjansky, Putikov, 2000, 2006, 2008) application of electrochemical updating of

  2. The formation of Luoboling porphyry Cu-Mo deposit: Constraints from zircon and apatite

    Science.gov (United States)

    Li, Cong-ying; Hao, Xi-luo; Liu, Ji-qiang; Ling, Ming-xing; Ding, Xing; Zhang, Hong; Sun, Wei-dong

    2017-02-01

    The Luobuling porphyry Cu-Mo deposit belongs to the Late Cretaceous Zijinshan Cu-Au-Mo mineralization field in southeastern China. Due to intensive hydrothermal alteration and weathering, it is very difficult to collect fresh whole rock samples for geochemical and isotopic studies in Luobuling. Zircon and apatite are accessory minerals that are resistant to hydrothermal alterations. In this study, we compared the trace element and isotope compositions of zircon and apatite from ore-bearing and barren samples to understand the formation of the Luoboling Cu-Mo deposit. Zircon U-Pb LA-ICP-MS dating shows that the Luoboling porphyries formed at 100 Ma (100.3 ± 1.2 Ma, 100.6 ± 1.5 Ma and 98.6 ± 1.2 Ma), which belongs to the late stage mineralization of the Zijinshan mineralization field. Zhongliao porphyritic granodiorite has the same age as the deposit (99.5 ± 1.6 Ma). The age of barren Sifang granodiorite is slightly older (109.7 ± 0.8 Ma). All these zircon grains have high Ce4+/Ce3+ ratios, indicating high oxygen fugacities. The ore-bearing samples show variable εHf(t) of - 7.3 to 0.2, suggesting either heterogeneous sources or mixing of two different magmas. Interestingly, the Hf isotope composition of barren samples is systematically higher (εHf(t) of - 3.6 to 5.5), implying a lower contribution of crustal materials. The OH mole percent of apatite grains from barren samples (LBL22-03 and SF09-05) is 0.5, which is higher than that of apatite from the ore-bearing samples (LBL20-01 LBL20-02 and LBL22-02), indicating lower F, Cl contents or higher water contents in the magma. In apatite from the ore-bearing samples, Sr is high, indicating the absence of plagioclase crystallization. In contrast, barren samples have varied and lower Sr, indicating that apatite crystallization was accompanied by plagioclase. These patterns were controlled by water contents because the crystallization of plagioclase is suppressed by high water contents in magmas. It also suggests

  3. PSEUDOBULGE FORMATION AS A DYNAMICAL RATHER THAN A SECULAR PROCESS

    Energy Technology Data Exchange (ETDEWEB)

    Guedes, Javiera; Mayer, Lucio; Carollo, Marcella [Institute for Astronomy, ETH Zuerich, Wolgang-Pauli-Strasse 27, 8093 Zurich (Switzerland); Madau, Piero [Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States)

    2013-07-20

    We investigate the formation and evolution of the pseudobulge in 'Eris', a high-resolution N-body + smoothed particle hydrodynamic cosmological simulation that successfully reproduces a Milky-Way-like massive late-type spiral in an cold dark matter universe. At the present epoch, Eris has a virial mass M{sub vir} {approx_equal} 8 Multiplication-Sign 10{sup 11} M{sub Sun }, a photometric stellar mass M{sub *} = 3.2 Multiplication-Sign 10{sup 10} M{sub Sun }, a bulge-to-total ratio B/T = 0.26, and a weak nuclear bar. We find that the bulk of the pseudobulge forms quickly at high redshift via a combination of non-axisymmetric disk instabilities and tidal interactions or mergers, both occurring on dynamical timescales, not through slow secular processes at lower redshift. Its subsequent evolution is not strictly secular either, and is closely intertwined with the evolution of the stellar bar. In fact, the structure that we recognize as a pseudobulge today evolved from a stellar bar that formed at high redshift due to tidal interactions with satellites, was destroyed by minor mergers at z {approx} 3, re-formed shortly after, and weakened again following a steady gas inflow at z {approx}< 1. The gradual dissolution of the bar ensued at z {approx} 1 and continues until the present without increasing the stellar velocity dispersion in the inner regions. In this scenario, the pseudobulge is not a separate component from the inner disk in terms of formation path; rather, it is the first step in the inside-out formation of the baryonic disk, in agreement with the fact that pseudobulges of massive spiral galaxies typically have a dominant old stellar population. If our simulations do indeed reproduce the formation mechanisms of massive spirals, then the progenitors of late-type galaxies should have strong bars and small photometric pseudobulges at high redshift.

  4. DYNAMICS AND THEIR DETERMINANTS IN HOUSEHOLD DEPOSITS IN LEI. CASE OF ROMANIA AFTER THE FINANCIAL CRISIS OF 2008

    Directory of Open Access Journals (Sweden)

    Zaharia Marian

    2015-12-01

    Full Text Available In the article are examined on the one hand the dynamics of household deposits as the important component of saving behaviour and on the other hand the most important determinants of household deposits behaviour. The paper was structured in 4 sections. The first section represents a short overview of the related literature. Source data and methodological aspects are described in section 2. The dynamics of the population's deposits, is discussed in section 3, while section 4 explains the results obtained from the analysis carried out. The results of this study confirm the direct and influence of the variable like the exchange rate on the household deposits.

  5. Simulated Dynamics of Underpotential Deposition of Cu with Sulfate on Au(111)

    OpenAIRE

    Brown, Gregory; Rikvold, Per Arne; Novotny, M. A.; Wieckowski, Andrzej

    1997-01-01

    Numerical studies of lattice-gas models are well suited to describe multi-adsorbate systems. One example is the underpotential deposition of Cu on Au(111) in the presence of sulfuric acid. Preliminary results from dynamic Monte Carlo simulations of the evolution of the adsorbed layer during potential-step experiments across phase transitions are presented for this particular system. The simulated current profiles reproduce a strong asymmetry seen in recent experiments. Examination of the micr...

  6. Sedimentological characteristics and depositional processes of sediment gravity flows in rift basins: The Palaeogene Dongying and Shahejie formations, Bohai Bay Basin, China

    Science.gov (United States)

    Liu, Lei; Chen, Hongde; Zhong, Yijiang; Wang, Jun; Xu, Changgui; Chen, Anqing; Du, Xiaofeng

    2017-10-01

    Sediment gravity flow deposits are common, particularly in sandy formations, but their origin has been a matter of debate and there is no consensus about the classification of such deposits. However, sediment gravity flow sandstones are economically important and have the potential to meet a growing demand in oil and gas exploration, so there is a drive to better understand them. This study focuses on sediment gravity flow deposits identified from well cores in Palaeogene deposits from the Liaodong Bay Depression in Bohai Bay Basin, China. We classify the sediment gravity flow deposits into eight lithofacies using lithological characteristics, grain size, and sedimentary structures, and interpret the associated depositional processes. Based on the scale, spatial distribution, and contact relationships of sediment gravity flow deposits, we defined six types of lithofacies associations (LAs) that reflect transformation processes and depositional morphology: LA1 (unconfined proximal breccia deposits), LA2 (confined channel deposits), LA3 (braided-channel lobe deposits), LA4 (unconfined lobe deposits), LA5 (distal sheet deposits), and LA6 (non-channelized sheet deposits). Finally, we established three depositional models that reflect the sedimentological characteristics and depositional processes of sediment gravity flow deposits: (1) slope-apron gravel-rich depositional model, which involves cohesive debris flows deposited as LA1 and dilute turbidity currents deposited as LA5; (2) non-channelized surge-like turbidity current depositional model, which mainly comprises sandy slumping, suspended load dominated turbidity currents, and dilute turbidity currents deposited as LA5 and LA6; and (3) channelized subaqueous-fan depositional model, which consists of non-cohesive bedload dominated turbidity currents, suspended load dominated turbidity currents, and dilute turbidity currents deposited as LA2-LA5, originating from sustained extrabasinal turbidity currents

  7. Computational Fluid Dynamics Modeling of Bacillus anthracis Spore Deposition in Rabbit and Human Respiratory Airways

    Energy Technology Data Exchange (ETDEWEB)

    Kabilan, Senthil; Suffield, Sarah R.; Recknagle, Kurtis P.; Jacob, Rick E.; Einstein, Daniel R.; Kuprat, Andrew P.; Carson, James P.; Colby, Sean M.; Saunders, James H.; Hines, Stephanie; Teeguarden, Justin G.; Straub, Tim M.; Moe, M.; Taft, Sarah; Corley, Richard A.

    2016-09-30

    Three-dimensional computational fluid dynamics and Lagrangian particle deposition models were developed to compare the deposition of aerosolized Bacillus anthracis spores in the respiratory airways of a human with that of the rabbit, a species commonly used in the study of anthrax disease. The respiratory airway geometries for each species were derived from computed tomography (CT) or µCT images. Both models encompassed airways that extended from the external nose to the lung with a total of 272 outlets in the human model and 2878 outlets in the rabbit model. All simulations of spore deposition were conducted under transient, inhalation-exhalation breathing conditions using average species-specific minute volumes. The highest exposure concentration was modeled in the rabbit based upon prior acute inhalation studies. For comparison, human simulation was also conducted at the same concentration. Results demonstrated that regional spore deposition patterns were sensitive to airway geometry and ventilation profiles. Due to the complex airway geometries in the rabbit nose, higher spore deposition efficiency was predicted in the upper conducting airways compared to the human at the same air concentration of anthrax spores. As a result, higher particle deposition was predicted in the conducting airways and deep lung of the human compared to the rabbit lung due to differences in airway branching pattern. This information can be used to refine published and ongoing biokinetic models of inhalation anthrax spore exposures, which currently estimate deposited spore concentrations based solely upon exposure concentrations and inhaled doses that do not factor in species-specific anatomy and physiology.

  8. Nitrogen and Carbon Dynamics Across Trophic Levels Along an Atmospheric Nitrogen Deposition Gradient

    Science.gov (United States)

    Wissinger, B. D.; Bell, M. D.; Newingham, B. A.

    2011-12-01

    Atmospheric nitrogen deposition has altered soil biogeochemical processes and plant communities across the United States. Prior investigations have demonstrated these alterations; however, little is known about the effects of elevated nitrogen on higher trophic levels. Building upon previous research that revealed an atmospheric nitrogen deposition gradient from the San Bernardino Mountains through Joshua Tree National Park in California, we investigated atmospheric nitrogen and its effects on soils, plants, and harvester ants. We measured nitrogen and carbon concentrations, along with carbon and nitrogen stable isotopes, across trophic levels at eighteen urban and unpopulated sites along the deposition gradient. Carbon and nitrogen attributes were determined in atmospheric nitric acid, soil, Larrea tridentata and Ambrosia dumosa leaves, seeds from selected plant species, and ants. We predicted carbon and nitrogen ratios and isotopes to change in areas with higher nitrogen deposition and vary along the deposition gradient. Nitrogen (p=0.02) and carbon (p=0.05) concentrations, as well as C:N ratios (p=<0.001), significantly differed in Messor pergandei individuals among sites; however, no correlation was found between these carbon and nitrogen attributes and the nitrogen deposition gradient (%N r2=0.02, %C r2=0.007, C:N r2=0.02). The δ15N and δ13C values of the ants, leaf tissues, and seeds measured across the gradient follow similar patterns with r2 values all below 0.20. Our results suggest the current and previous rates of nitrogen deposition in this area are not enough to modify nitrogen and carbon concentrations and isotope values. Compensatory nitrogen cycling processes in the soil may reduce the effects of increased nitrogen on plants and thus higher trophic levels. Nitrogen and carbon dynamics across trophic levels might change after longer ecosystem exposure to elevated nitrogen; however, other abiotic and biotic factors are likely driving current

  9. Ore Zoning and Dynamics of Ore—Forming Processes of Yinshan Polymetallic Deposit in Dexing,Jiangxi

    Institute of Scientific and Technical Information of China (English)

    张德会; 於崇文; 等

    1997-01-01

    The Yinshan deposit,one of the large-scale Cu-Pb-Zn-Au-Ag polymetallic deposits,may be named a middle-low temperature subvolcanic hydrothermal deposit and referred to as the "transitional deposit"linking mineralization of the epithermal and porphyry coppertypes.In this paper,the characteristics and structures of ore zoning are briefly described.On the basis of the dynamics of ore-forming processes and applying computer numerical simulation technique,the mechanism of ore zoning is discussed and a concealed igneous body controlling ore deposition at depth of the Yinshan mine is predicted.

  10. Depositional evolution of a reef-dominated Upper Permian carbonate platform, Wegener Halvoe Formation, Karstryggen area, East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Stemmrik, L.

    1996-12-31

    The Wegener Halvoe Formation carbonate platform in the Karstryggen area consists of three third order depositional sequences that formed in response to three Kazanian sea level cycles. Pinning point curves for the sub-aerial exposure surfaces separating the depositional sequences quantify the amplitude of the relative sea level fluctuations in the range of 70-140 m. The Karstryggen platform developed on top of a karstified older Permian carbonate platform and pre-depositional relief was locally exceeding 70 m. The pre-depositional relief influenced deposition in all three sequences. Algal-cement buildups formed over karst pinnacles and merged during time to form a N-S trending barrier dissected by deep fluvially modified karst channels. Peritidal carbonates formed behind the barrier whereas off platform sedimentation was dominated by thin transgressive siliciclastics overlain by shallow marine algal-foraminifer grain-stones in the first two sequences. During the last sea level cycle pro-grading oolitic grain-stones formed basin-wards of the algal-cement buildups. Transgressive systems tracts are thin and often dominated by condensed siliciclastic units in off platform areas and palaeolows. Over palaeotopographic highs it consists of aggrading algal cement-stones. High-stand deposits are limited to palaeotopographic elevated areas and consist of algal cementstones along the basin margin and shallow sub-tidal to inter-tidal carbonates and evaporites in the platform area. Outside these areas carbonate deposition took place during falling sea level, and during deposition of the first two sequences thin laterally extensive units of shallow marine grain-stones were deposited directly on top of deeper marine siliciclastics. During the final sea level fall, thick pro-grading units of oolitic grain-stones were deposited. (au) Appendix no. 3. 28 refs.

  11. Subduction of the Nazca Ridge and the Inca Plateau: Insights into the formation of ore deposits in Peru [rapid communication

    Science.gov (United States)

    Rosenbaum, Gideon; Giles, David; Saxon, Mark; Betts, Peter G.; Weinberg, Roberto F.; Duboz, Cecile

    2005-10-01

    A large number of ore deposits that formed in the Peruvian Andes during the Miocene (15-5 Ma) are related to the subduction of the Nazca plate beneath the South American plate. Here we show that the spatial and temporal distribution of these deposits correspond with the arrival of relatively buoyant topographic anomalies, namely the Nazca Ridge in central Peru and the now-consumed Inca Plateau in northern Peru, at the subduction zone. Plate reconstruction shows a rapid metallogenic response to the arrival of the topographic anomalies at the subduction trench. This is indicated by clusters of ore deposits situated within the proximity of the laterally migrating zones of ridge subduction. It is accordingly suggested that tectonic changes associated with impingement of the aseismic ridge into the subduction zone may trigger the formation of ore deposits in metallogenically fertile suprasubduction environments.

  12. In Situ Formation and Dynamical Evolution of Hot Jupiter Systems

    Science.gov (United States)

    Batygin, Konstantin; Bodenheimer, Peter H.; Laughlin, Gregory P.

    2016-10-01

    Hot Jupiters, giant extrasolar planets with orbital periods shorter than ˜10 days, have long been thought to form at large radial distances, only to subsequently experience long-range inward migration. Here, we offer the contrasting view that a substantial fraction of the hot Jupiter population formed in situ via the core-accretion process. We show that under conditions appropriate to the inner regions of protoplanetary disks, rapid gas accretion can be initiated by super-Earth-type planets, comprising 10-20 Earth masses of refractory material. An in situ formation scenario leads to testable consequences, including the expectation that hot Jupiters should frequently be accompanied by additional low-mass planets with periods shorter than ˜100 days. Our calculations further demonstrate that dynamical interactions during the early stages of planetary systems’ lifetimes should increase the inclinations of such companions, rendering transits rare. High-precision radial velocity monitoring provides the best prospect for their detection.

  13. In Situ Formation and Dynamical Evolution of Hot Jupiter Systems

    CERN Document Server

    Batygin, Konstantin; Laughlin, Gregory P

    2015-01-01

    Hot Jupiters, giant extrasolar planets with orbital periods shorter than ~10 days, have long been thought to form at large radial distances, only to subsequently experience long-range inward migration. Here, we propose that in contrast with this picture, a substantial fraction of the hot Jupiter population formed in situ via the core accretion process. We show that under conditions appropriate to the inner regions of protoplanetary disks, rapid gas accretion can be initiated by Super-Earth type planets, comprising 10-20 Earth masses of refractory composition material. An in situ formation scenario leads to testable consequences, including the expectation that hot Jupiters should frequently be accompanied by additional low-mass planets with periods shorter than ~100 days. Our calculations further demonstrate that dynamical interactions during the early stages of planetary systems' lifetimes should increase the inclinations of such companions, rendering transits rare. High-precision radial velocity monitoring p...

  14. Spectral characteristics of banded iron formations in Singhbhum craton, eastern India: Implications for hematite deposits on Mars

    Directory of Open Access Journals (Sweden)

    Mahima Singh

    2016-11-01

    Full Text Available Banded iron formations (BIFs are major rock units having hematite layers intermittent with silica rich layers and formed by sedimentary processes during late Archean to mid Proterozoic time. In terrestrial environment, hematite deposits are mainly found associated with banded iron formations. The BIFs in Lake Superior (Canada and Carajas (Brazil have been studied by planetary scientists to trace the evolution of hematite deposits on Mars. Hematite deposits are extensively identified in Meridiani region on Mars. Many hypotheses have been proposed to decipher the mechanism for the formation of these deposits. On the basis of geomorphological and mineralogical studies, aqueous environment of deposition is found to be the most supportive mechanism for its secondary iron rich deposits. In the present study, we examined the spectral characteristics of banded iron formations of Joda and Daitari located in Singhbhum craton in eastern India to check its potentiality as an analog to the aqueous/marine environment on Mars. The prominent banding feature of banded iron formations is in the range of few millimeters to few centimeters in thickness. Fe rich bands are darker (gray in color compared to the light reddish jaspilitic chert bands. Thin quartz veins (<4 mm are occasionally observed in the hand-specimens of banded iron formations. Spectral investigations have been conducted in VIS/NIR region of electromagnetic spectrum in the laboratory conditions. Optimum absorption bands identified include 0.65, 0.86, 1.4 and 1.9 μm, in which 0.56 and 0.86 μm absorption bands are due to ferric iron and 1.4 and 1.9 μm bands are due to OH/H2O. To validate the mineralogical results obtained from VIS/NIR spectral radiometry, laser Raman and Fourier transform infrared spectroscopic techniques were utilized and the results were found to be similar. Goethite-hematite association in banded iron formation in Singhbhum craton suggests dehydration activity, which has

  15. Spectral characteristics of banded iron formations in Singhbhum craton, eastern India:Implications for hematite deposits on Mars

    Institute of Scientific and Technical Information of China (English)

    Mahima Singh; Jayant Singhal; K. Arun Prasad; V.J. Rajesh; Dwijesh Ray; Priyadarshi Sahoo

    2016-01-01

    Banded iron formations (BIFs) are major rock units having hematite layers intermittent with silica rich layers and formed by sedimentary processes during late Archean to mid Proterozoic time. In terrestrial environment, hematite deposits are mainly found associated with banded iron formations. The BIFs in Lake Superior (Canada) and Carajas (Brazil) have been studied by planetary scientists to trace the evo-lution of hematite deposits on Mars. Hematite deposits are extensively identified in Meridiani region on Mars. Many hypotheses have been proposed to decipher the mechanism for the formation of these deposits. On the basis of geomorphological and mineralogical studies, aqueous environment of deposi-tion is found to be the most supportive mechanism for its secondary iron rich deposits. In the present study, we examined the spectral characteristics of banded iron formations of Joda and Daitari located in Singhbhum craton in eastern India to check its potentiality as an analog to the aqueous/marine envi-ronment on Mars. The prominent banding feature of banded iron formations is in the range of few millimeters to few centimeters in thickness. Fe rich bands are darker (gray) in color compared to the light reddish jaspilitic chert bands. Thin quartz veins (<4 mm) are occasionally observed in the hand-specimens of banded iron formations. Spectral investigations have been conducted in VIS/NIR region of electromagnetic spectrum in the laboratory conditions. Optimum absorption bands identified include 0.65, 0.86, 1.4 and 1.9 mm, in which 0.56 and 0.86 mm absorption bands are due to ferric iron and 1.4 and 1.9 mm bands are due to OH/H2O. To validate the mineralogical results obtained from VIS/NIR spectral radiometry, laser Raman and Fourier transform infrared spectroscopic techniques were utilized and the results were found to be similar. Goethite-hematite association in banded iron formation in Singhbhum craton suggests dehydration activity, which has altered the primary

  16. Dynamical complexity in the perception-based network formation model

    Science.gov (United States)

    Jo, Hang-Hyun; Moon, Eunyoung

    2016-12-01

    Many link formation mechanisms for the evolution of social networks have been successful to reproduce various empirical findings in social networks. However, they have largely ignored the fact that individuals make decisions on whether to create links to other individuals based on cost and benefit of linking, and the fact that individuals may use perception of the network in their decision making. In this paper, we study the evolution of social networks in terms of perception-based strategic link formation. Here each individual has her own perception of the actual network, and uses it to decide whether to create a link to another individual. An individual with the least perception accuracy can benefit from updating her perception using that of the most accurate individual via a new link. This benefit is compared to the cost of linking in decision making. Once a new link is created, it affects the accuracies of other individuals' perceptions, leading to a further evolution of the actual network. As for initial actual networks, we consider both homogeneous and heterogeneous cases. The homogeneous initial actual network is modeled by Erdős-Rényi (ER) random networks, while we take a star network for the heterogeneous case. In any cases, individual perceptions of the actual network are modeled by ER random networks with controllable linking probability. Then the stable link density of the actual network is found to show discontinuous transitions or jumps according to the cost of linking. As the number of jumps is the consequence of the dynamical complexity, we discuss the effect of initial conditions on the number of jumps to find that the dynamical complexity strongly depends on how much individuals initially overestimate or underestimate the link density of the actual network. For the heterogeneous case, the role of the highly connected individual as an information spreader is also discussed.

  17. Effect of temperature on deposition layer formation in HBr/N2/fluorocarbon-based plasma

    Science.gov (United States)

    Iwase, Taku; Yokogawa, Kenetsu; Mori, Masahito

    2017-06-01

    The effects of wafer temperature on etching rate and surface composition were investigated to clarify the surface reaction mechanism under HBr/N2/fluorocarbon-based gas plasma for developing a process for three-dimensional NAND flash devices. The etching rates of both polycrystalline silicon (poly-Si) and SiO2 were found to increase at a wafer temperature of 20 °C as compared with those at 60 °C. Comparing the gas combination of fluorocarbon/N2 and HBr/N2 mixtures, the temperature dependence of SiO2 etching rates was considered to relevant to the sticking probability of fluorocarbon polymers. To determine the cause of the temperature dependence of the poly-Si etching rate, surface composition was evaluated by thermal-desorption-spectroscopy and laser-sputtered-neutral-mass-spectrometry analyses. Ammonium bromide was confirmed in the deposition film at a wafer temperature of 20 °C. The observed increase in poly-Si etching rate at lower temperatures was possibly caused by increased amounts of nitrogen, hydrogen, and bromine fixed to the surface with the formation of ammonium bromide.

  18. Formation and Transport of Atomic Hydrogen in Hot-Filament Chemical Vapor Deposition Reactors

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In this paper we focus on diamond film hot-filament chemical vapor deposition reactors where the only reactant ishydrogen so as to study the formation and transport of hydrogen atoms. Analysis of dimensionless numbers forheat and mass transfer reveals that thermal conduction and diffusion are the dominant mechanisms for gas-phaseheat and mass transfer, respectively. A simplified model has been established to simulate gas-phase temperature andH concentration distributions between the filament and the substrate. Examination of the relative importance ofhomogeneous and heterogeneous production of H atoms indicates that filament-surface decomposition of molecularhydrogen is the dominant source of H and gas-phase reaction plays a negligible role. The filament-surface dissociationrates of H2 for various filament temperatures were calculated to match H-atom concentrations observed in the liter-ature or derived from power consumption by filaments. Arrhenius plots of the filament-surface hydrogen dissociationrates suggest that dissociation of H2 at refractory filament surface is a catalytic process, which has a rather lowereffective activation energy than homogeneous thermal dissociation. Atomic hydrogen, acting as an important heattransfer medium to heat the substrate, can freely diffuse from the filament to the substrate without recombination.

  19. Molecular Dynamics Simulations of CO2 Formation in Interstellar Ices

    CERN Document Server

    Arasa, Carina; van Dishoeck, Ewine F; Kroes, Geert-Jan

    2013-01-01

    CO2 ice is one of the most abundant components in ice-coated interstellar ices besides H2O and CO, but the most favorable path to CO2 ice is still unclear. Molecular dynamics calculations on the ultraviolet photodissociation of different kinds of CO-H2O ice systems have been performed at 10 K in order to demonstrate that the reaction between CO and an OH molecule resulting from H2O photodissociation through the first excited state is a possible route to form CO2 ice. However, our calculations, which take into account different ice surface models, suggest that there is another product with a higher formation probability ((3.00+-0.07)x10-2), which is the HOCO complex, whereas the formation of CO2 has a probability of only (3.6+-0.7)x10-4. The initial location of the CO is key to obtain reaction and form CO2: the CO needs to be located deep into the ice. The HOCO complex becomes trapped in the cold ice surface in the trans-HOCO minimum because it quickly loses its internal energy to the surrounding ice, preventi...

  20. Phase separation like dynamics during Myxococcus xanthus fruiting body formation

    Science.gov (United States)

    Liu, Guannan; Thutupalli, Shashi; Wigbers, Manon; Shaevitz, Joshua

    2015-03-01

    Collective motion exists in many living organisms as an advantageous strategy to help the entire group with predation, forage, and survival. However, the principles of self-organization underlying such collective motions remain unclear. During various developmental stages of the soil-dwelling bacterium, Myxococcus xanthus, different types of collective motions are observed. In particular, when starved, M. xanthus cells eventually aggregate together to form 3-dimensional structures (fruiting bodies), inside which cells sporulate in response to the stress. We study the fruiting body formation process as an out of equilibrium phase separation process. As local cell density increases, the dynamics of the aggregation M. xanthus cells switch from a spatio-temporally random process, resembling nucleation and growth, to an emergent pattern formation process similar to a spinodal decomposition. By employing high-resolution microscopy and a video analysis system, we are able to track the motion of single cells within motile collective groups, while separately tuning local cell density, cell velocity and reversal frequency, probing the multi-dimensional phase space of M. xanthus development.

  1. A dynamic model for tumour growth and metastasis formation.

    Science.gov (United States)

    Haustein, Volker; Schumacher, Udo

    2012-07-05

    A simple and fast computational model to describe the dynamics of tumour growth and metastasis formation is presented. The model is based on the calculation of successive generations of tumour cells and enables one to describe biologically important entities like tumour volume, time point of 1st metastatic growth or number of metastatic colonies at a given time. The model entirely relies on the chronology of these successive events of the metastatic cascade. The simulation calculations were performed for two embedded growth models to describe the Gompertzian like growth behaviour of tumours. The initial training of the models was carried out using an analytical solution for the size distribution of metastases of a hepatocellular carcinoma. We then show the applicability of our models to clinical data from the Munich Cancer Registry. Growth and dissemination characteristics of metastatic cells originating from cells in the primary breast cancer can be modelled thus showing its ability to perform systematic analyses relevant for clinical breast cancer research and treatment. In particular, our calculations show that generally metastases formation has already been initiated before the primary can be detected clinically.

  2. Gravity effects on thick brane formation from scalar field dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Andrianov, Alexander A. [Saint-Petersburg State University, V.A. Fock Department of Theoretical Physics, St. Petersburg (Russian Federation); Universitat de Barcelona, Institut de Ciencies del Cosmos, Barcelona (Spain); Andrianov, Vladimir A.; Novikov, Oleg O. [Saint-Petersburg State University, V.A. Fock Department of Theoretical Physics, St. Petersburg (Russian Federation)

    2013-12-15

    The formation of a thick brane in five-dimensional space-time is investigated when warp geometries of AdS{sub 5} type are induced by scalar matter dynamics and triggered by a thin-brane defect. The scalar matter is taken to consist of two fields with O(2) symmetric self-interaction and with manifest O(2) symmetry breaking by terms quadratic in fields. One of them serves as a thick brane formation mode around a kink background and another one is of a Higgs-field type which may develop a classical background as well. Scalar matter interacts with gravity in the minimal form and gravity effects on (quasi)localized scalar fluctuations are calculated with usage of gauge invariant variables suitable for perturbation expansion. The calculations are performed in the vicinity of the critical point of spontaneous breaking of the combined parity symmetry where a non-trivial v.e.v. of the Higgs-type scalar field is generated. The non-perturbative discontinuous gravitational effects in the mass spectrum of light localized scalar states are studied in the presence of a thin-brane defect. The thin brane with negative tension happens to be the most curious case when the singular barriers form a potential well with two infinitely tall walls and the discrete spectrum of localized states arises completely isolated from the bulk. (orig.)

  3. Star formation in isolated AMIGA galaxies: dynamical influence of bars

    CERN Document Server

    Verley, S; Verdes-Montenegro, L; Bergond, G; Leon, S

    2007-01-01

    Star formation depends strongly both on the local environment of galaxies, and on the internal dynamics of the interstellar medium. To disentangle the two effects, we obtained, in the framework of the AMIGA project, Ha and Gunn r photometric data for more than 200 spiral galaxies lying in very low-density regions of the local Universe. We characterise the Ha emission, tracing current star formation, of the 45 largest and less inclined galaxies observed for which we estimate the torques between the gas and the bulk of the optical matter. We could subsequently study the Ha morphological aspect of these isolated spiral galaxies. Using Fourier analysis, we focus on the modes of the spiral arms and also on the strength of the bars, computing the torques between the gas and newly formed stars (Ha) and the bulk of the optical matter (Gunn r). We interpret the various bar/spiral morphologies observed in terms of the secular evolution experienced by galaxies in isolation. We also classify the different spatial distrib...

  4. Response of sulphur dynamics in European catchments to decreasing sulphate deposition

    Directory of Open Access Journals (Sweden)

    A. Prechtel

    2001-01-01

    Full Text Available Following the decline in sulphur deposition in Europe, sulphate dynamics of catchments and the reversibility of anthropogenic acidification of soils and freshwaters became of major interest. Long-term trends in sulphate concentrations and fluxes in precipitation/throughfall and freshwaters of 20 European catchments were analysed to evaluate catchment response to decreasing sulphate deposition. Sulphate deposition in the catchments studied declined by 38-82% during the last decade. Sulphate concentrations in all freshwaters decreased significantly, but acidification reversal was clearly delayed in the German streams. In Scandinavian streams and Czech/Slovakian lakes sulphate concentrations responded quickly to decreased input. Sulphate fluxes in run-off showed no clear trend in Germany and Italy but decreased in Scandinavia, the Czech Republic and Slovakia. The decrease, however, was less than the decline in input fluxes. While long-term sulphate output fluxes from catchments were generally correlated to input fluxes, most catchments started a net release of sulphate during the early 1990s. Release of stored sulphate leads to a delay of acidification reversal and can be caused by four major processes. Desorption and excess mineralisation were regarded as the most important for the catchments investigated, while oxidation and weathering were of lesser importance for the long-term release of sulphate. Input from weathering has to be considered for the Italian catchments. Sulphate fluxes in German catchments, with deeply weathered soils and high soil storage capacity, responded more slowly to decreased deposition than catchments in Scandinavia and the Czech Republic/Slovakia, which have thin soils and relatively small sulphate storage. For predictions of acidification reversal, soil characteristics, sulphur pools and their dynamics have to be evaluated in future research. Keywords: acidification reversal, sulphur, sulphate release, Europe

  5. The conjunction of factors that lead to formation of giant gold provinces and deposits in non-arc settings

    Institute of Scientific and Technical Information of China (English)

    David I. Groves; Richard J. Goldfarb; M. Santosh

    2016-01-01

    -flux systems relative to orogenic gold deposits, and those few giants are essentially preservational exceptions. Many Carlin-type deposits are giants due to the exceptional conjunction of both structural and lithological parameters that caused reactive and permeable rocks, enriched in syngenetic gold, to be located below an impermeable cap along antiformal “trends”. Hy-drocarbons probably played an important role in concentrating metal. The supergiant Post-Betze deposit has additional ore zones in strain heterogeneities surrounding the pre-gold Goldstrike stock. All un-equivocal IOCG deposits are giant or near-giant deposits in terms of gold-equivalent resources, partly due to economic factors for this relatively poorly understood, low Cu-Au grade deposit type. The supergiant Olympic Dam deposit, the most shallowly formed deposit among the larger IOCGs, probably owes its origin to eruption of volatile-rich hybrid magma at surface, with formation of a large maar and intense and widespread brecciation, alteration and Cu-Au-U deposition in a huge rock volume.

  6. Dynamics of alliance formation and the egalitarian revolution.

    Directory of Open Access Journals (Sweden)

    Sergey Gavrilets

    Full Text Available BACKGROUND: Arguably the most influential force in human history is the formation of social coalitions and alliances (i.e., long-lasting coalitions and their impact on individual power. Understanding the dynamics of alliance formation and its consequences for biological, social, and cultural evolution is a formidable theoretical challenge. In most great ape species, coalitions occur at individual and group levels and among both kin and non-kin. Nonetheless, ape societies remain essentially hierarchical, and coalitions rarely weaken social inequality. In contrast, human hunter-gatherers show a remarkable tendency to egalitarianism, and human coalitions and alliances occur not only among individuals and groups, but also among groups of groups. These observations suggest that the evolutionary dynamics of human coalitions can only be understood in the context of social networks and cognitive evolution. METHODOLOGY/PRINCIPAL FINDINGS: Here, we develop a stochastic model describing the emergence of networks of allies resulting from within-group competition for status or mates between individuals utilizing dyadic information. The model shows that alliances often emerge in a phase transition-like fashion if the group size, awareness, aggressiveness, and persuasiveness of individuals are large and the decay rate of individual affinities is small. With cultural inheritance of social networks, a single leveling alliance including all group members can emerge in several generations. CONCLUSIONS/SIGNIFICANCE: We propose a simple and flexible theoretical approach for studying the dynamics of alliance emergence applicable where game-theoretic methods are not practical. Our approach is both scalable and expandable. It is scalable in that it can be generalized to larger groups, or groups of groups. It is expandable in that it allows for inclusion of additional factors such as behavioral, genetic, social, and cultural features. Our results suggest that a rapid

  7. A Study on the Geological—Geochemical Dynamics of Hydrothermal Ore Deposition as Exemplified by the Muping—Rushan Gold Deposit Belt,Eastern Shandong,China

    Institute of Scientific and Technical Information of China (English)

    赵伦山; 高太忠; 等

    1996-01-01

    This paper presents a method of establishing a hydrothermal ore-forming reaction system.On the basis of the study of four typical hydrothermal deposits,the following conclusions concerning geochemical dynamic controlling during hydrothermal mineralization have been sions concerning geochemical dynaamic controlling during hydrothermal mineralization have been drawn:(1)The regional tectonic activities control the concentration and dispersion of elements in the ore-forming process in terms of their effects on the thermodynamic nature and conditions of the ore-forming reaction system.(2)During hydrothermal mineralization the activites of ore-bearing faults can be divideb into two stages:the brittle splitting stage and the brittle-tough tensing stage,which would create characteristically different geodynamic conditions for the geochemical thermodynamic ore-forming system.(3)The hydrothermal ore-forming reaaction system is an open dynamic system.At the brittle splitting stage the system was so strongly supersaturated and unequilibrated as to speed up and enhance the crystallization and differentiation of ore-forming fluids.And at the brittle-tough tensing stage,the ore-forming system was in a weak supersaturated state;with decreasing temperature and pressure the crystallization of oreforming material would show down,and it can be regarded as an equilibrated state.(4)In the lates stages of hydrothermal evolution,gold would be concentrated in the residual ore-forming solution.The pulsating fracture activite in this stage led to the crush of pyrite ore and it was then filled with gold-enriched solution,forming high-grage“fissure”gold ore.This ore-forming process could be called the coupling mechanism of ore formation.

  8. Formation of fouling deposits on a carbon steel surface from Colombian heavy crude oil under preheating conditions

    Science.gov (United States)

    Muñoz Pinto, D. A.; Cuervo Camargo, S. M.; Orozco Parra, M.; Laverde, D.; García Vergara, S.; Blanco Pinzon, C.

    2016-02-01

    Fouling in heat exchangers is produced by the deposition of undesired materials on metal surfaces. As fouling progresses, pressure drop and heat transfer resistance is observed and therefore the overall thermal efficiency of the equipment diminishes. Fouling is mainly caused by the deposition of suspended particles, such as those from chemical reactions, crystallization of certain salts, and some corrosion processes. In order to understand the formation of fouling deposits from Colombian heavy oil (API≈12.3) on carbon steel SA 516 Gr 70, a batch stirred tank reactor was used. The reactor was operated at a constant pressure of 340psi while varying the temperature and reaction times. To evaluate the formation of deposits on the metal surfaces, the steel samples were characterized by gravimetric analysis and Scanning Electron Microscopy (SEM). On the exposed surfaces, the results revealed an increase in the total mass derived from the deposition of salt compounds, iron oxides and alkaline metals. In general, fouling was modulated by both the temperature and the reaction time, but under the experimental conditions, the temperature seems to be the predominant variable that controls and accelerates fouling.

  9. Formation of the Martian Polar Layered Terrains: Quantifying Polar Water Ice and Dust Surface Deposition during Current and Past Orbital Epochs with the NASA Ames GCM

    Science.gov (United States)

    Emmett, Jeremy; Murphy, Jim

    2016-10-01

    Structural and compositional variability in the layering sequences comprising Mars' polar layered terrains (PLT's) is likely explained by orbital-forced climatic variations in the sedimentary cycles of water ice and dust from which they formed [1]. The PLT's therefore contain a direct, extensive record of the recent climate history of Mars encoded in their structure and stratigraphy, but deciphering this record requires understanding the depositional history of their dust and water ice constituents. 3D Mars atmosphere modeling enables direct simulation of atmospheric dynamics, aerosol transport and quantification of surface accumulation for a range of past and present orbital configurations. By quantifying the net yearly polar deposition rates of water ice and dust under Mars' current and past orbital configurations characteristic of the last several millions of years, and integrating these into the present with a time-stepping model, the formation history of the north and south PLT's will be investigated, further constraining their age and composition, and, if reproducible, revealing the processes responsible for prominent features and stratigraphy observed within the deposits. Simulating the formation of the deposits by quantifying net deposition rates during past orbital epochs and integrating these into the present, effectively 'rebuilding' the terrains, could aid in understanding deeper stratigraphic trends, correlating between geographically-separated deposits, explaining the presence and shapes of large-scale polar features, and correlating stratigraphy with geological time. Quantification of the magnitude and geographical distribution of surface aerosol accumulation will build on the work of previous GCM-based investigations [3]. Construction and analysis of hypothetical stratigraphic sequences in the PLT's will draw from previous climate-controlled stratigraphy methodologies [2,4], but will utilize GCM-derived net deposition rates to model orbital

  10. DYNAMICS OF CHANGES IN VEGETATION OF A MODEL EXPERIMENT ON COAL COMBUSTION WASTE DEPOSITS

    Directory of Open Access Journals (Sweden)

    Kazimierz H. Dyguś

    2014-11-01

    Full Text Available The paper contains the evaluation of the reclamation efficiencyon coal combustion waste deposits fertilized with composts and sewage sludge. Based on multiannual studies, the dynamics of changes in vegetation in the performed experiment have been shown. The firstphase of the experiment concerning the reclamation efficiencyof the employed fertilizers was carried out from 2006 to 2007. The second phase was carried out between 2011 and 2012. In order to show a broader spectrum of dynamics of changes in vegetation, the floristicobservation was repeated in 2013 and this paper is the presentation of its outcome. Based on the observation (2011–2013 and its results it was found that apart from plants cultivated in experimental containers also a self-sown florahas had a significantcontribution in shap-ing the vegetation cover. The results of floristic and ecological research have proven that composts and sewage sludge constitute a favorable environment for the development of spontaneous vegetation cover on coal combustion waste deposits. Based on the evaluation of the vegetation cover level in particular models it was shown that models with Complex composts (kC and Radiowo ones (kRa as well as the model with sewage sludge have pre-sented the highest reclamation efficienc. The lowest efficiencyhas been shown in models with ZUSOK composts (kZ and the plant ones (kr. The conclusions have highlighted the share of ecological, systematic and syntaxonomic plant groups in the process of reclamation of combustion waste deposits.

  11. The causes of milk deposit formation on the walls of the heat exchangers during the heat treatment of milk

    Directory of Open Access Journals (Sweden)

    Bojan Matijević

    2006-03-01

    Full Text Available The results of research on finding the causes and preventing the formation of milk deposit are described in this paper.During the heat treatment of milk, an unwanted phenomenon occurs; the formation of milk deposit on heating surfaces of heat exchangers. This phenomenon causes the decrease of heat transfer coefficient as well as the pressure drop, it restricts the flow of milk, and causes additional production costs and increases production loss.The formation of milk deposit is a result of complex processes caused by thermal treatment of proteins and mineral substances in milk. Factors which cause milk deposit are: pH - value, the amount of proteins and mineral substances in milk, dissolved gases in milk, characteristics of heating surface, the difference in temperatures of milk and heating surfaces, and the regime of milk circulation. The chemical composition of milk can not be influenced, but the standards of heat treatment in order to minimise this phenomenon can, and that is precisely the topic of the latest researches.

  12. Fluid dynamics and deposit patterns in evaporating sessile drop containing microparticles: substrate heating and wettability effects

    Science.gov (United States)

    Patil, Nagesh D.; Bhardwaj, Rajneesh; Sharma, Atul

    2016-11-01

    The evaporation of sessile water drops containing colloidal microparticles is investigated on non-heated and heated hydrophilic and hydrophobic substrates. Time-varying drop shapes and temperatures of liquid-gas interface are recorded using high-speed and infrared camera, respectively. In heated case, infrared-thermography shows larger temperature gradient across the liquid-gas interface and recorded motion of the particles confirm Marangoni flow from the contact line to apex inside the drop. On non-heated hydrophilic substrates, a ring-like pattern forms, as reported extensively in the literature; while on heated hydrophilic substrates, a thin ring with an inner-deposit forms. On non-heated hydrophobic substrates, the contact line depins to form inner-deposit without ring; while on heated hydrophobic substrates, the contact line pins to form inner-deposit with thin ring. This pinning transition occurs due to the particles self-pinning in a stagnation region developed by the Marangoni flow near the contact line. This work gives fundamental insights on the thermal and wettability effects on internal fluid dynamics of the evaporating sessile drop and associated deposit shape, with applications in ink-jet printing and biosensors. PhD Scholar.

  13. Molecular dynamics simulation of the deposition process of hydrogenated diamond-like carbon (DLC) films

    Institute of Scientific and Technical Information of China (English)

    ZHANG YuJun; DONG GuangNeng; MAO JunHong; XIE YouBai

    2008-01-01

    The deposition process of hydrogenated diamond-like carbon (DLC) film greatly affects its frictional properties. In this study, CH3 radicals are selected as source species to deposit hydrogenated DLC films for molecular dynamics simulation. The growth and structural properties of hydrogenated DLC films are investigated and elucidated in detail. By comparison and statistical analysis, the authors find that the ratio of carbon to hydrogen in the films generally shows a monotonously increasing trend with the increase of impact energy. Carbon atoms are more reactive during deposition and more liable to bond with substrate atoms than hydrogen atoms. In addition, there exists a peak value of the number of hydrogen atoms deposited in hydrogenated DLC films. The trends of the variation are opposite on the two sides of this peak point, and itbecomes stable when impact energy is greater than 80 eV. The average relative density also indicates a rising trend along with the increment of impact energy, while it does not reach the saturation value until impact energy comes to 50 eV. The hydrogen content in source species is a key factor to determine the hydrogen content in hydrogenated DLC films. When the hydrogen content in source species is high, the hydrogen content in hydrogenated DLC films is accordingly high.

  14. Mechanistic Model for Ash Deposit Formation in Biomass Suspension Firing. Part 1: Model Verification by Use of Entrained Flow Reactor Experiments

    DEFF Research Database (Denmark)

    Hansen, Stine Broholm; Jensen, Peter Arendt; Jappe Frandsen, Flemming

    2017-01-01

    Two models for deposit formation in suspension firing of biomass have been developed. Both models describe deposit buildup by diffusion and subsequent condensation of vapors, thermophoresis of aerosols, convective diffusion of small particles, impaction of large particles, and reaction. The models...... used to describe the deposit formation rates and deposit chemistry observed in a series of entrained flow reactor (EFR) experiments using straw and wood as fuels. It was found that model #1 was not able to describe the observed influence of temperature on the deposit buildup rates, predicting a much...

  15. Formation and Characterization of Europium Bisphthalocyanine Organic Nanowires by Electrochemical Deposition

    Institute of Scientific and Technical Information of China (English)

    Han Bo ZHOU; Hong Zheng CHEN; Lei CAO; Yu RONG; Jin Zhi SUN; Mang WANG

    2004-01-01

    Europium bisphthalocyanine (EuPc2) nanowires were prepared by electrochemical deposition method. Scanning electron microscopy (SEM) images show the evolution of the morphologies of nanowires obtained under different deposition time (Td). The optical properties of europium bisphthalocyanine films were studied by UV-Vis absorption spectra. The morphology of EuPc2 nanowires could be controlled by changing deposition conditions, which provides a useful method to make organic nanowires.

  16. Biological Dynamics Markup Language (BDML): an open format for representing quantitative biological dynamics data.

    Science.gov (United States)

    Kyoda, Koji; Tohsato, Yukako; Ho, Kenneth H L; Onami, Shuichi

    2015-04-01

    Recent progress in live-cell imaging and modeling techniques has resulted in generation of a large amount of quantitative data (from experimental measurements and computer simulations) on spatiotemporal dynamics of biological objects such as molecules, cells and organisms. Although many research groups have independently dedicated their efforts to developing software tools for visualizing and analyzing these data, these tools are often not compatible with each other because of different data formats. We developed an open unified format, Biological Dynamics Markup Language (BDML; current version: 0.2), which provides a basic framework for representing quantitative biological dynamics data for objects ranging from molecules to cells to organisms. BDML is based on Extensible Markup Language (XML). Its advantages are machine and human readability and extensibility. BDML will improve the efficiency of development and evaluation of software tools for data visualization and analysis. A specification and a schema file for BDML are freely available online at http://ssbd.qbic.riken.jp/bdml/. Supplementary data are available at Bioinformatics online. © The Author 2014. Published by Oxford University Press.

  17. Microfabric analysis of Mn-carbonate laminae deposition and Mn-sulfide formation in the Gotland Deep, Baltic Sea

    Science.gov (United States)

    Burke, Ian T.; Kemp, Alan E. S.

    2002-05-01

    The manganese carbonate deposits of the anoxic Littorina sediments of the Gotland Deep have been commonly related to the periodic renewal of deep water by inflowing saline water from the North Sea. The use of scanning electron microscopy-based techniques allows identification of small-scale sedimentary and geochemical features associated with Mn-carbonate laminae, which has significant implications for models of Mn-carbonate formation. Varves occurring in the Littorina sequence contain up to four laminae that may be placed in a seasonal cycle, and kutnahorite laminae occur within varves only as a winter-early spring deposit. This kutnahorite laminae seasonality is in agreement with the seasonal distribution of major Baltic inflow events recorded in historical records, and a direct causal link between inflows and kutnahorite deposition is implied. Benthic foraminifera tests are found to be heavily encrusted in kutnahorite, implying that benthic recolonization during oxidation events occurs concurrently with kutnahorite formation. The relatively common occurrence of small (50 to 100 μm) hexagonal γ-Mn-sulfide pseudomorphs, associated with 13% of kutnahorite laminae studied, is reported in Gotland Deep sediments for the first time. Although Mn-sulfide crystals are not usually preserved in the sediment, the discovery of Mn-sulfide pseudomorphs suggests that initial formation of Mn-sulfide in the Gotland Deep may occur much more commonly during the process of kutnahorite formation than previous reports of Mn-sulfide occurrence have implied.

  18. Star Formation and Cloud Dynamics in the Galactic Bar Region

    Science.gov (United States)

    Tolls, Volker

    The Inner Galaxy (IG) that is the Galactic Bar Region (GBR) and the Central Molecular Zone (CMZ) including the Galactic Center (GC) are, despite being the sites of dramatic processes and unique sources, still only incompletely understood. Detailed new datasets from the Herschel Space Observatory can be systematically combined with older archival material to enable a new and more complete analysis of the region, its large-scale dynamics, its unusual giant molecular clouds, and the likely influences of its bar and its supermassive black hole. Such a study is both timely and important: the region has affected the structure and evolution of the galaxy; its individual sources are opportunities to examine star formation (for example) under extreme conditions; the processes feeding the CMZ and, subsequently, its black hole are important; and not least, it is a nearby template for the inner regions of other galaxies. The Herschel Space Observatory has provided us with exciting new datasets including full FIR photometric maps and highand low-resolution far-infrared/submillimeter spectra of key sources and lines of the locations of dynamical importance. All these datasets are publicly available from the Herschel Science Archive. Our experienced team has already developed preliminary models, and we propose a thorough investigation to combine the Herschel datasets with Spitzer and WISE datasets. We will supplement them with ground-based observations in cases when it will improve the results. We will then analyze the data and use the results to refine the models and improve our understanding of this key region. Our specific goal is to characterize and model the 3 giant high-velocity molecular cloud clumps in the Galaxy Bar Region (GBR) in detail and to combine the conclusions to produce an improved model of the IG. We have seven tasks: (1) identify all smaller scale gas and dust cores using archival Herschel FIR photometric observations and obtain their physical characteristics

  19. Dynamics of Drop Formation in an Electric Field.

    Science.gov (United States)

    Notz; Basaran

    1999-05-01

    The effect of an electric field on the formation of a drop of an inviscid, perfectly conducting liquid from a capillary which protrudes from the top plate of a parallel-plate capacitor into a surrounding dynamically inactive, insulating gas is studied computationally. This free boundary problem which is comprised of the surface Bernoulli equation for the transient drop shape and the Laplace equation for the velocity potential inside the drop and the electrostatic potential outside the drop is solved by a method of lines incorporating the finite element method for spatial discretization. The finite element algorithm employed relies on judicious use of remeshing and element addition to a two-region adaptive mesh to accommodate large domain deformations, and allows the computations to proceed until the thickness of the neck connecting an about to form drop to the rest of the liquid in the capillary is less than 0.1% of the capillary radius. The accuracy of the computations is demonstrated by showing that in the absence of an electric field predictions made with the new algorithm are in excellent agreement with boundary integral calculations (Schulkes, R. M. S. M. J. Fluid Mech. 278, 83 (1994)) and experimental measurements on water drops (Zhang, X., and Basaran, O. A. Phys. Fluids 7(6), 1184 (1995)). In the presence of an electric field, the algorithm predicts that as the strength of the applied field increases, the mode of drop formation changes from simple dripping to jetting to so-called microdripping, in accordance with experimental observations (Cloupeau, M., and Prunet-Foch, B. J. Aerosol Sci. 25(6), 1021 (1994); Zhang, X., and Basaran, O. A. J. Fluid Mech. 326, 239 (1996)). Computational predictions of the primary drop volume and drop length at breakup are reported over a wide range of values of the ratios of electrical, gravitational, and inertial forces to surface tension force. In contrast to previously mentioned cases where both the flow rate in the tube

  20. Violent Relaxation, Dynamical Instabilities and the Formation of Elliptical Galaxies

    Science.gov (United States)

    Aguilar, L. A.

    1990-11-01

    RESUMEN: El problema de la formaci6n de galaxias elfpticas por medjo de colapso gravitacional sin disipaci6n de energfa es estudiado usando un gran numero de simulaciones numericas. Se muestra que este tipo de colapsos, partiendo de condiciones iniciales frfas donde la energfa cinetica inicial representa s6lo un 5%, 0 , de a potencial inicial, produce sistemas relajados de forma triaxial muy similares a las galaxias elfpticas reales en sus formas y perfiles de densidad en proyecci6i . La forina triaxial resulta de la acci6n de una inestabilidad dinamica que aparece en sistemas 'inicos dominados por movimientos radiales, mientras que el perfil de densidad final Cs debido al llamado relajamiento violento que tiende a producir una distribuci6n en espacio fase unica. Estos dos fen6menos tienden a borrar los detalles particulares sobre las condiciones iniciales y dan lugar a una evoluci6n convergente hacia sistemas realistas, esto innecesario el uso de condiciones iniciales especiales (excepto por Ia condici6i de que estas deben ser frfas). Las condiciones iniciales frfas producen los movimientos radiales y fluctuaciones de la energfa potencial requeridos por ambos fen6menos. ABSTRACT: The problem of formation of elliptical galaxies via dissipationless collapse is studied using a large set of numerical simulations. It is shown that dissipationless collapses from cold initial conditions, where the total initial kinetic energy is less than 5% ofthe initial potential energy, lead to relaxed triaxial systems ery similar to real elliptical galaxies ii projected shape and density profiles. The triaxial shape is due to the of a dynamical instability that appears on systems dominated by radial orbits, while final density profile is due to violent relaxation that tends to produce a unique distribution iii space. These two phenomena erase memory of the initial prodtice a convergent evolution toward realistic systems, thus making unnecessary use o[special initial conditions (other

  1. A dynamical model on deposit and loan of banking: A bifurcation analysis

    Science.gov (United States)

    Sumarti, Novriana; Hasmi, Abrari Noor

    2015-09-01

    A dynamical model, which is one of sophisticated techniques using mathematical equations, can determine the observed state, for example bank profits, for all future times based on the current state. It will also show small changes in the state of the system create either small or big changes in the future depending on the model. In this research we develop a dynamical system of the form: d/D d t =f (D ,L ,rD,rL,r ), d/L d t =g (D ,L ,rD,rL,r ), Here D and rD are the volume of deposit and its rate, L and rL are the volume of loan and its rate, and r is the interbank market rate. There are parameters required in this model which give connections between two variables or between two derivative functions. In this paper we simulate the model for several parameters values. We do bifurcation analysis on the dynamics of the system in order to identify the appropriate parameters that control the stability behaviour of the system. The result shows that the system will have a limit cycle for small value of interest rate of loan, so the deposit and loan volumes are fluctuating and oscillating extremely. If the interest rate of loan is too high, the loan volume will be decreasing and vanish and the system will converge to its carrying capacity.

  2. Patterns of nutrient dynamics in Adirondack lakes recovering from acid deposition.

    Science.gov (United States)

    Gerson, Jacqueline R; Driscoll, Charles T; Roy, Karen M

    2016-09-01

    With decreases in acid deposition, nitrogen : phosphorus (N:P) ratios in lakes are anticipated to decline, decreasing P limitation of phytoplankton and potentially changing current food web dynamics. This effect could be particularly pronounced in the Adirondack Mountains of New York State, a historic hotspot for effects of acid deposition. In this study, we evaluate spatial patterns of nutrient dynamics in Adirondack lakes and use these to infer potential future temporal trends. We calculated Mann-Kendall tau correlations among total phosphorus (TP), chlorophyll a, dissolved organic carbon (DOC), acid neutralizing capacity (ANC), and nitrate (NO3(-) ) concentrations in 52 Adirondack Long Term Monitoring (ALTM) program lakes using samples collected monthly during 2008-2012. We evaluated the hypothesis that decreased atmospheric N and S deposition will decrease P limitation in freshwater ecosystems historically impacted by acidification. We also compared these patterns among lake watershed characteristics (i.e., seepage or lacking a surface outlet, chain drainage, headwater drainage, thin glacial till, medium glacial till). We found that correlations (P lakes. Differentiations among watershed till depth were also important in determining correlations due to water interaction with surficial geology. Additionally, we found low NO3(-) :TP (N:P mass) values in seepage lakes (2.0 in winter, 1.9 in summer) compared to chain drainage lakes (169.4 in winter, 49.5 in summer) and headwater drainage lakes (97.0 in winter, 10.9 in summer), implying a high likelihood of future shifts in limitation patterns for seepage lakes. With increasing DOC and decreasing NO3(-) concentrations coinciding with decreases in acid deposition, there is reason to expect changes in nutrient dynamics in Adirondack lakes. Seepage lakes may become N-limited, while drainage lakes may become less P-limited, both resulting in increased productivity. Long-term measurements of TP and chlorophyll a from

  3. Benthic biofilm structure controls the deposition-resuspension dynamics of fine clay particles

    Science.gov (United States)

    Hunter, W. R.; Roche, K. R.; Drummond, J. D.; Boano, F.; Packman, A. I.; Battin, T. J.

    2015-12-01

    In fluvial ecosystems the alternation of deposition and resuspension of particles represents an important pathway for the downstream translocation of microbes and organic matter. Such particles can originate from algae and microbes, the spontaneous auto-aggregation of organic macromolecules (e.g., "river sown"), terrestrial detritus (traditionally classified as "particulate organic matter"), and erosive mineral and organo-mineral particles. The transport and retention of particles in headwater streams is associated with biofilms, which are surface-attached microbial communities. Whilst biofilm-particle interactions have been studied in bulk, a mechanistic understanding of these processes is lacking. Parallel macroscale/microscale observations are required to unravel the complex feedbacks between biofilm structure, coverage and the dynamics of deposition and resuspension. We used recirculating flume mesocosms to test how changes in biofilm structure affected the deposition and resuspension of clay-sized (< 10 μm) particles. Biofilms were grown in replicate 3-m-long recirculating flumes over variable lengths of time (0, 14, 21, 28, and 35) days. Fixed doses of fluorescent clay-sized particles were introduced to each flume and their deposition was traced over 30 minutes. A flood event was then simulated via a step increase in flowrate to quantify particle resuspension. 3D Optical Coherence Tomography was used to determine roughness, areal coverage and height of biofilms in each flume. From these measurements we characterised particle deposition and resuspension rates, using continuous time random walk modelling techniques, which we then tested as responses to changes in biofilm coverage and structure under both base-flow and flood-flow scenarios. Our results suggest that biofilm structural complexity is a primary control upon the retention and downstream transport of fine particles in stream mesocosms.

  4. Long term deposit formation in aviation turbine fuel at elevated temperature

    Science.gov (United States)

    Giovanetti, A. J.; Szetela, E. J.

    1986-01-01

    An experimental characterization is conducted for the relationships between deposit mass, operating time, and temperature, in coking associated with aviation fuels under conditions simulating those typical of turbine engine fuel systems. Jet A and Suntech A fuels were tested in stainless steel tubing heated to 420-750 K, over test durations of between 3 and 730 hr and at fuel velocities of 0.07-1.3 m/sec. Deposit rates are noted to be a strong function of tube temperature; for a given set of test conditions, deposition rates for Suntech A exceed those of Jet A by a factor of 10. Deposition rates increased markedly with test duration for both fuels. The heated tube data obtained are used to develop a global chemical kinetic model for fuel oxidation and carbon deposition.

  5. Formation of Jarosite in the Marwrth Vallis Region of Mars by Weathering Within Paleo-Ice Deposits

    Science.gov (United States)

    Michalski, J. R.; Niles, Paul B.

    2011-01-01

    Here we report new detections of jarosite in the Mawrth Vallis region of Mars. These newly recognized deposits expand the known occurrences of sulfates [1-2] in the region and further expand the already considerable geologic-mineralogic diversity of the Mawrth Vallis area [3-6]. The occurrence of sulfates such as jarosite in geologic contact with thick deposits of phyllosilicates in the Mawrth Vallis area is a relatively rare case on Mars where the enigmatic transition from an early phyllosilicateforming era to a younger sulfate-forming era [7] can be explored. We propose an ice-weathering model which can potentially explain the formation of jarosite-silicakaolinite within acidic ice deposits.

  6. Pseudobulge Formation as a Dynamical Rather than a Secular Process

    CERN Document Server

    Guedes, Javiera; Carollo, Marcella; Madau, Piero

    2012-01-01

    We investigate the formation and evolution of the pseudobulge in "Eris", a high-resolution N-body + smoothed particle hydrodynamics (SPH) cosmological simulation that successfully reproduces a Milky Way-like massive late-type spiral in a cold dark matter (LCDM) universe. At the present epoch, Eris has a virial mass Mvir=8x10^11 Msun, a photometric stellar mass M*=3.2x10^10 Msun, a bulge-to-total ratio B/T = 0.26, and a weak nuclear bar. We find that the bulk of the pseudobulge forms quickly at high redshift via a combination of non-axisymmetric disk instabilities and tidal interactions or mergers both occurring on dynamical timescales, not through slow secular processes at lower redshift. Its subsequent evolution is not strictly secular either, and is closely intertwined with the evolution of the stellar bar. In fact, the structure that we recognize as a pseudobulge today evolves from a stellar bar that formed at high redshift, was destroyed by minor mergers at z~3, reformed shortly after, and weakened again ...

  7. The dynamics of Bax channel formation: influence of ionic strength.

    Science.gov (United States)

    Ganesan, Vidyaramanan; Walsh, Timothy; Chang, Kai-Ti; Colombini, Marco

    2012-08-08

    Mitochondrial outer membrane permeabilization (MOMP) is a complex multistep process. Studies of MOMP in vivo are limited by the stochastic variability of MOMP between cells and rapid completion of IMS protein release within single cells. In vitro models have provided useful insights into MOMP. We have investigated the dynamics of Bax-mediated MOMP in isolated mitochondria using ionic strength as a tool to control the rate of MOMP. We find that Bax can induce both transient permeabilization, detected by protein release, and more substantial long-lasting permeabilization, measured by the rate of oxidation of added cytochrome c. We found that higher ionic strength causes Bax to form small channels quickly but the expansion of these early channels is impeded. This inhibitory effect of ionic strength is independent of tBid. Channels formed under low ionic strength are not destabilized by raising the ionic strength. Increase in ionic strength also increases the ability of Bcl-xL to inhibit Bax-mediated MOMP. Ionic strength does not affect Bax insertion into mitochondria. Thus, ionic strength influences the assembly of Bax molecules already in membrane into channels. Ionic strength can be used as an effective biophysical tool to study Bax-mediated channel formation.

  8. Extracellular matrix proteins and the dynamics of dentin formation.

    Science.gov (United States)

    Butler, William T; Brunn, Jan C; Qin, Chunlin; McKee, Marc D

    2002-01-01

    Dentinogenesis involves controlled reactions that result in conversion of unmineralized predentin to dentin when apatite crystals are formed. This process is dynamic: Maturation events occur within predentin beginning at the proximal layer and progressing to the predentin-dentin (PD) border. One type of controlled reaction is the proteolytic processing of dentin sialophosphoprotein (DSPP) to dentin sialoprotein (DSP) and dentin phosphoprotein (DPP), by cleavage of at least three highly conserved peptide bonds. We postulate that this processing event represents an activation step, resulting in release of DPP, which is active in its effects on formation and growth of apatite crystals. Dentin matrix protein 1 (DPM1), present as a processed fragment (57-kD protein) in bone, is seen in dentin on sodium dodecyl sulfate polyacrylamide gel electrophoresis as one intact protein of 150-200 kD. Anti-57-kD antibodies elicit immunoreactivity in bone, dentin, and cellular cementum. In bone, the reactivity is associated with osteocytes and their cell processes. Similarly, dentin shows reactivity in odontoblasts, predentin, and the odontoblast processes. In summary, the processing of large sialic acid-rich proteins into smaller fragments may be an important part of the controlled conversion of predentin to dentin and osteoid to bone.

  9. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    DEFF Research Database (Denmark)

    Lauros, J.; Sogachev, Andrey; Smolander, S.

    2011-01-01

    We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the simulated...

  10. Particle concentration and flux dynamics in the atmospheric boundary layer as the indicator of formation mechanism

    DEFF Research Database (Denmark)

    Lauros, J.; Sogachev, Andrey; Smolander, S.

    2010-01-01

    We carried out column model simulations to study particle fluxes and deposition and to evaluate different particle formation mechanisms at a boreal forest site in Finland. We show that kinetic nucleation of sulphuric acid cannot be responsible for new particle formation alone as the vertical...

  11. Low temperature aging mechanism identification and lithium deposition in a large format lithium iron phosphate battery for different charge profiles

    Science.gov (United States)

    Ouyang, Minggao; Chu, Zhengyu; Lu, Languang; Li, Jianqiu; Han, Xuebing; Feng, Xuning; Liu, Guangming

    2015-07-01

    Charging procedures at low temperatures severely shorten the cycle life of lithium ion batteries due to lithium deposition on the negative electrode. In this paper, cycle life tests are conducted to reveal the influence of the charging current rate and the cut-off voltage limit on the aging mechanisms of a large format LiFePO4 battery at a low temperature (-10 °C). The capacity degradation rates accelerate rapidly after the charging current reaches 0.25 C or the cut-off voltage reaches 3.55 V. Therefore the scheduled current and voltage during low-temperature charging should be reconsidered to avoid capacity degradation. Lithium deposition contributes to low-temperature aging mechanisms, as something needle-like which might be deposited lithium is observed on the surface of the negative electrode after disassembling the aged battery cell. To confirm our explanation, incremental capacity analysis (ICA) is performed to identify the characteristics of the lithium deposition induced battery aging mechanisms. Furthermore, the aging mechanism is quantified using a mechanistic model, whose parameters are estimated with the particle swarm optimization algorithm (PSO). The loss of reversible lithium originating from secondary SEI formation and dead lithium is confirmed as the cause of the aging.

  12. Renal Light Chain Deposition Associated with the Formation of Intracellular Crystalline Inclusion Bodies in Podocytes: A Rare Case Report.

    Science.gov (United States)

    Wang, Yuan-da; Dong, Zhe-yi; Zhang, Xue-guang; Zhang, Wei; Yin, Zhong; Qiu, Qiang; Chen, Xiang-mei

    2016-01-01

    We herein report the case of an elderly woman with bone pain and proteinuria as the main clinical manifestations. The patient was diagnosed with the IgG κ type of multiple myeloma. Her renal pathology consisted of widespread κ light chain protein deposition associated with the formation of large quantities of rod-like crystals in podocytes. This phenomenon is very rare. We explored the significance of this crystal formation via a detailed and descriptive analysis and also performed a literature review, thus providing data to increase the available information about this type of disease.

  13. Origin of ferricretes in fluvial-marine deposits of the Lower Cenomanian Bahariya Formation, Bahariya Oasis, Western Desert, Egypt

    Science.gov (United States)

    Tanner, Lawrence H.; Khalifa, Mohamed A.

    2010-03-01

    The type section of the Lower Cenomanian Bahariya Formation at Gebel El-Dist (Bahariya Oasis, Western Desert), Egypt, comprises claystones, mudstones, siltstones and sandstones deposited in fluvial-deltaic coastal plain, lagoonal, estuarine and shallow marine environments. The formation is characterized by an abundance of ferruginous sandstones that locally weather to form prominent iron crusts. These centimeter to decimeter-scale ferruginous horizons display a continuum of features ranging from unaltered sandstone with a pervasive ferruginous matrix to distinct ironstone beds with massive, nodular, vesicular and pisolitic textures. Ferruginous sandstone typically occurs at the tops of sandstone beds, or bracketing the base and top of beds, in the fining-upward cycles of deltaic plain deposits in the lower part of the formation and on a low-energy fluvial floodplain in the middle of the formation. Indurated ironstone beds occur mainly as the caps of coarsening-upward cycles of prograding shoreface sediments through much of the formation. We interpret the ironstone crusts as ferricretes, formed by iron accumulation that resulted from the oxidation and precipitation of soluble iron or colloids transported in the sediment load or by groundwater. This accumulation possibly took place at the water table or possibly below the water table at the fresh water/saline water interface. However, base-level fall and subsequent subaerial exposure of the sediments resulted in reworking and pedogenic modification of some of the iron-impregnated horizons.

  14. Formation of palladium nanofilms using electrochemical atomic layer deposition (E-ALD) with chloride complexation.

    Science.gov (United States)

    Sheridan, Leah B; Gebregziabiher, Daniel K; Stickney, John L; Robinson, David B

    2013-02-05

    Pd thin films were formed by electrochemical atomic layer deposition (E-ALD) using surface-limited redox replacement (SLRR) of Cu underpotential deposits (UPD) on polycrystalline Au substrates. An automated electrochemical flow deposition system was used to deposit Pd atomic layers using a sequence of steps referred to as a cycle. The initial step was Cu UPD, followed by its exchange for Pd ions at open circuit, and finishing with a blank rinse to complete the cycle. Deposits were formed with up to 75 cycles and displayed proportional deposit thicknesses. Previous reports by this group indicated excess Pd deposition at the flow cell ingress, from electron probe microanalysis (EPMA). Those results suggested that the SLRR mechanism did not involve direct transfer between a Cu(UPD) atom and a Pd(2+) ion that would take its position. Instead, it was proposed that electrons are transferred through the metallic surface to reduce Pd(2+) ions near the surface where their activity is highest. It was proposed that if the cell was filled completely before a significant fraction of the Cu(UPD) atoms had been oxidized then the deposit would be homogeneous. Previous work with EDTA indicated that the hypothesis had merit, but it proved to be very sensitive to the EDTA concentration. In the present study, chloride was used to complex Pd(2+) ions, forming PdCl(4)(2-), to slow the exchange rate. Both complexing agents led to a decrease in the rate of replacement, producing more homogeneous films. Although the use of EDTA improved the homogeneity, it also decreased the deposit thickness by a factor of 3 compared to the thickness obtained via the use of chloride.

  15. Towards a CFD-based mechanistic deposit formation model for straw-fired boilers

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen; Rosendahl, Lasse Aistrup; Baxter, L.L.

    2006-01-01

    in the reminder of the paper. The growth of deposits on furnace walls and super heater tubes is treated including the impact on heat transfer rates determined by the CFD code. Based on the commercial CFD code FLUENTe, the overall model is fully implemented through the User Defined Functions. The model...... is configured entirely through a graphical user interface integrated in the standard FLUENTe interface. The model considers fine and coarse mode ash deposition and sticking mechanisms for the complete deposit growth, as well as an influence on the local boundary conditions for heat transfer due to thermal...

  16. Effect of variable frequency electromagnetic field on deposit formation in installations with geothermal water in Sijarinjska spa (Serbia

    Directory of Open Access Journals (Sweden)

    Stojiljković Dragan T.

    2011-01-01

    Full Text Available In this paper we have examined the effect of variable frequency electromagnetic field generated with a homemade device on deposit formation in installations with geothermal water from Sijarinjska Spa. The frequency alteration of the electromagnetic field in time was made by means of the sinusoidal and saw-tooth function. In laboratory conditions, with the flow of geothermal water at 0.015 l/s and temperature of 60 °C for 6 hours through a zig-zag glass pipe, a multiple decrease of total deposit has been achieved. By applying the saw-tooth and sinusoidal function, the decrease in contents of calcium and deposit has been achieved by 8 and 6 times, respectively. A device was also used on geothermal water installation in Sijarinjska Spa (Serbia, with the water flow through a 1'' diameter non-magnetic prochrome pipe at 0.15 l/s and temperature of 75 °C in a ten-day period. A significant decrease in total deposit and calcium in the deposit has also been achieved.

  17. CFD modeling of particle dispersion and deposition coupled with particle dynamical models in a ventilated room

    Science.gov (United States)

    Xu, Guangping; Wang, Jiasong

    2017-10-01

    Two dynamical models, the traditional method of moments coupled model (MCM) and Taylor-series expansion method of moments coupled model (TECM) for particle dispersion distribution and gravitation deposition are developed in three-dimensional ventilated environments. The turbulent airflow field is modeled with the renormalization group (RNG) k-ε turbulence model. The particle number concentration distribution in a ventilated room is obtained by solving the population balance equation coupled with the airflow field. The coupled dynamical models are validated using experimental data. A good agreement between the numerical and experimental results can be achieved. Both models have a similar characteristic for the spatial distribution of particle concentration. Relative to the MCM model, the TECM model presents a more close result to the experimental data. The vortex structure existed in the air flow makes a relative large concentration difference at the center region and results in a spatial non-uniformity of concentration field. With larger inlet velocity, the mixing level of particles in the room is more uniform. In general, the new dynamical models coupled with computational fluid dynamics (CFD) in the current study provide a reasonable and accurate method for the temporal and spatial evolution of particles effected by the deposition and dispersion behaviors. In addition, two ventilation modes with different inlet velocities are proceeded to study the effect on the particle evolution. The results show that with the ceiling ventilation mode (CVM), the particles can be better mixed and the concentration level is also higher. On the contrast, with the side ceiling ventilation mode (SVM), the particle concentration has an obvious stratified distribution with a relative lower level and it makes a much better environment condition to the human exposure.

  18. Star Formation in the LMC: Gravitational Instability and Dynamical Triggering

    CERN Document Server

    Chu, Y H; Yang, C C

    2007-01-01

    Evidence for triggered star formation is difficult to establish because energy feedback from massive stars tend to erase the interstellar conditions that led to the star formation. Young stellar objects (YSOs) mark sites of {\\it current} star formation whose ambient conditions have not been significantly altered. Spitzer observations of the Large Magellanic Cloud (LMC) effectively reveal massive YSOs. The inventory of massive YSOs, in conjunction with surveys of interstellar medium, allows us to examine the conditions for star formation: spontaneous or triggered. We examine the relationship between star formation and gravitational instability on a global scale, and we present evidence of triggered star formation on local scales in the LMC.

  19. Sputter-deposited Mg-Al-O thin films: linking molecular dynamics simulations to experiments

    Energy Technology Data Exchange (ETDEWEB)

    Georgieva, V; Bogaerts, A [PLASMANT Research Group, Department of Chemistry, University of Antwerp, Universiteitsplein 1, 2610 Antwerp (Belgium); Saraiva, M; Depla, D [Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, B-9000 Gent (Belgium); Jehanathan, N; Lebelev, O I, E-mail: violeta.georgieva@ua.ac.b [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, B2020 Antwerpen (Belgium)

    2009-03-21

    Using a molecular dynamics model the crystallinity of Mg{sub x}Al{sub y}O{sub z} thin films with a variation in the stoichiometry of the thin film is studied at operating conditions similar to the experimental operating conditions of a dual magnetron sputter deposition system. The films are deposited on a crystalline or amorphous substrate. The Mg metal content in the film ranged from 100% (i.e. MgO film) to 0% (i.e. Al{sub 2}O{sub 3} film). The radial distribution function and density of the films are calculated. The results are compared with x-ray diffraction and transmission electron microscopy analyses of experimentally deposited thin films by the dual magnetron reactive sputtering process. Both simulation and experimental results show that the structure of the Mg-Al-O film varies from crystalline to amorphous when the Mg concentration decreases. It seems that the crystalline Mg-Al-O films have a MgO structure with Al atoms in between.

  20. The Dynamic Scaling Study of Vapor Deposition Polymerization: A Monte Carlo Approach

    CERN Document Server

    Tangirala, Sairam; Zhao, Y -P; 10.1103/PhysRevE.81.011605

    2010-01-01

    The morphological scaling properties of linear polymer films grown by vapor deposition polymerization (VDP) are studied by 1+1D Monte Carlo simulations. The model implements the basic processes of random angle ballistic deposition ($F$), free-monomer diffusion ($D$) and monomer adsorption along with the dynamical processes of polymer chain initiation, extension, and merger. The ratio $G=D/F$ is found to have a strong influence on the polymer film morphology. Spatial and temporal behavior of kinetic roughening has been extensively studied using finite-length scaling and height-height correlations $H(r,t)$. The scaling analysis has been performed within the no-overhang approximation and the scaling behaviors at local and global length scales were found to be very different. The global and local scaling exponents for morphological evolution have been evaluated for varying free-monomer diffusion by growing the films at $G$ = $10$, $10^2$, $10^3$, and $10^4$ and fixing the deposition flux $F$. With an increase in ...

  1. Apatite formation behaviour during metasomatism in the Bathtub Intrusion (Babbitt deposit, Duluth Complex, USA)

    Science.gov (United States)

    Raič, Sara; Mogessie, Aberra; Krenn, Kurt; Hauzenberger, Christoph A.; Tropper, Peter

    2016-04-01

    The mineralized troctolitic Bathtub intrusion (Duluth Complex, NE-Minnesota) is known for its famous Cu-Ni-Sulfide±PGM Babbitt deposit, where platinum group minerals (PGMs) are either hosted by primary magmatic sulfides (base metal sulfides) or associated with hydrothermally altered portions. This secondary generation of PGMs is present in alteration patches and suggests the involvement of hydrothermal fluids in the mobilization of platinum-group elements (PGEs). Accessory fluorapatite in these samples reveals besides H2O- and CO2-rich primary fluid inclusions, textural and compositional variations that also record magmatic and metasomatic events. Based on detailed back-scattered electron imaging (BSE) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICPMS), a primary magmatic origin is reflected by homogeneous or zoned grains, where zoning patterns are either concentric or oscillatory, with respect to LREE. Late magmatic to hydrothermal processes are indicated by grains with bright LREE-enriched rims or conversion textures with REE-enriched patches in the interior of the apatite. A metasomatic formation of monazite from apatite is documented by the presence of monazite inclusions in apatite and newly grown monazite at altered apatite rims. They formed by the release of REEs from the apatite during a fluid-induced alteration, based on the coupled substitution Ca2+ + P5+ = REE3+ + Si4+ (Rønsbo 1989; Rønsbo 2008). Samples with monazite inclusions in apatite further display occurrences of PGMs associated with hydrothermal alteration patches (chlorite + amphibole). The presence of H2O- and CO2-rich fluid inclusions in apatite, the metasomatically induced monazite growth, as well as the occurrence of PGMs in hydrothermally alteration zones, also suggest the involvement of aqueous chloride complexes in a H2O dominated fluid in the transportation of LREE and redistribution of the second generation of PGEs. Rønsbo, J.G. (1989): Coupled substitutions

  2. Formation and Dynamical Evolution of the Asteroid Belt

    Science.gov (United States)

    Bottke, William F.

    2015-08-01

    Asteroids are critical to our desire to unravel the origin of the Solar System because they supply unique, relatively pristine snapshots of the environment in which the Earth formed and evolved. This is due to the fact that, although the asteroids and Earth have followed very different evolutionary pathways, they all formed from the same set of physical processes and share a common ancestry. The asteroid belt presents a particular challenge to understanding terrestrial planet formation because of its small mass. Models of the protoplanetary disk suggest the region between 2-3 AU should contain roughly 3 Earth masses, while less than 0.001 of an Earth mass is actually found there.A long-standing explanation for the asteroid belt's small mass is that it is due to the gravitational influence of Jupiter and Saturn. Some have suggested protoplanets grew there before they were dynamically removed from the asteroid belt by resonances with the gas giants. This left the asteroid belt dynamically excited (which is observed) and heavily depleted in mass. More recently, however, detailed models have shown that this process produces an asteroid belt that is inconsistent with observations.Two recent models propose new ways to match asteroid belt constraints. The first, the so-called ‘Grand Tack’ scenario, uses the results of hydrodynamic simulations to show that Jupiter (and Saturn) migrated both inward and outward across the asteroid belt while interacting with the protoplanetary gas disk. The Grand Tack not only reproduces the mass and mixture of spectral types in the asteroid belt, but it also truncates the planetesimal disk from which the terrestrial planets form, potentially explaining why Mars is less massive than Earth. In a second scenario, planetesimals that form directly from cm- to meter-sized objects, known as “pebbles”, are rapidly converted to 100 to 1000 km asteroid-like object that subsequently grow by accreting even more pebbles. Pebble accretion models

  3. Mechanistic Model for Ash Deposit Formation in Biomass Suspension-Fired Boilers. Part 2: Model Verification by Use of Full Scale Tests

    DEFF Research Database (Denmark)

    Hansen, Stine Broholm; Jensen, Peter Arendt; Jappe Frandsen, Flemming

    2017-01-01

    describes particle sticking or rebound by a combination of the description of (visco)elsatic particles impacting a solid surface and particle capture by a viscous surface. The model is used to predict deposit formation rates measured during tests conducted with probes in full-scale suspension-fired biomass...... of some physical parameters related to the description of surface capture are suggested. Based on these examinations of the model ability to describe observed deposit formation rates, the proposed model can be regarded as a promising tool for description of deposit formation in full-scale biomass......A model for deposit formation in suspension firing of biomass has been developed. The model describes deposit build-up by diffusion and subsequent condensation of vapors, thermoforesis of aerosols, convective diffusion of small particles, impaction of large particles and reaction. The model...

  4. Stratigraphy, age, and depositional setting of the Miocene Barstow Formation at Harvard Hill, central Mojave Desert, California

    Science.gov (United States)

    Leslie, Shannon R.; Miller, David M.; Wooden, Joseph L.; Vazquez, Jorge A.

    2010-01-01

    New detailed geologic mapping and geochronology of the Barstow Formation at Harvard Hill, 30 km east of Barstow, CA, help to constrain Miocene paleogeography and tectonics of the central Mojave Desert. A northern strand of the Quaternary ENE-striking, sinistral Manix fault divides the Barstow Formation at Harvard Hill into two distinct lithologic assemblages. Strata north of the fault consist of: a green rhyolitic tuff, informally named the Shamrock tuff; lacustrine sandstone; partially silicified thin-bedded to massive limestone; and alluvial sandstone to pebble conglomerate. Strata south of the fault consist of: lacustrine siltstone and sandstone; a rhyolitic tuff dated at 19.1 Ma (U-Pb); rock-avalanche breccia deposits; partially silicified well-bedded to massive limestone; and alluvial sandstone and conglomerate. Our U-Pb zircon dating of the Shamrock tuff by SHRIMP-RG yields a peak probability age of 18.7 ± 0.1 Ma. Distinctive outcrop characteristics, mineralogy, remanent magnetization, and zircon geochemistry (Th/U) suggest that the Shamrock tuff represents a lacustrine facies of the regionally extensive Peach Spring Tuff (PST). Here we compare zircon age and geochemical analyses from the Shamrock tuff with those of the PST at Stoddard Wash and provide new insight into the age of zircon crystallization in the PST rhyolite. Results of our field studies show that Miocene strata at Harvard Hill mostly accumulated in a lacustrine environment, although depositional environments varied from a relatively deep lake to a very shallow lake or even onshore setting. Rock-avalanche breccias and alluvial deposits near the base of the exposed section indicate proximity to a steep basin margin and detrital studies suggest a southern source for coarse-grained deposits; therefore, we may infer a southern basin-margin setting at Harvard Hill during the early Miocene. Our geochronology demonstrates that deposition of the Barstow Formation at Harvard Hill extended from before

  5. Dental calculus: recent insights into occurrence, formation, prevention, removal and oral health effects of supragingival and subgingival deposits.

    Science.gov (United States)

    White, D J

    1997-10-01

    Dental calculus, both supra- and subgingival occurs in the majority of adults worldwide. Dental calculus is calcified dental plaque, composed primarily of calcium phosphate mineral salts deposited between and within remnants of formerly viable microorganisms. A viable dental plaque covers mineralized calculus deposits. Levels of calculus and location of formation are population specific and are affected by oral hygiene habits, access to professional care, diet, age, ethnic origin, time since last dental cleaning, systemic disease and the use of prescription medications. In populations that practice regular oral hygiene and with access to regular professional care, supragingival dental calculus formation is restricted to tooth surfaces adjacent to the salivary ducts. Levels of supragingival calculus in these populations is minor and the calculus has little if any impact on oral-health. Subgingival calculus formation in these populations occurs coincident with periodontal disease (although the calculus itself appears to have little impact on attachment loss), the latter being correlated with dental plaque. In populations that do not practice regular hygiene and that do not have access to professional care, supragingival calculus occurs throughout the dentition and the extent of calculus formation can be extreme. In these populations, supragingival calculus is associated with the promotion of gingival recession. Subgingival calculus, in "low hygiene" populations, is extensive and is directly correlated with enhanced periodontal attachment loss. Despite extensive research, a complete understanding of the etiologic significance of subgingival calculus to periodontal disease remains elusive, due to inability to clearly differentiate effects of calculus versus "plaque on calculus". As a result, we are not entirely sure whether subgingival calculus is the cause or result of periodontal inflammation. Research suggests that subgingival calculus, at a minimum, may expand the

  6. Computational fluid dynamics modeling of transport and deposition of pesticides in an aircraft cabin.

    Science.gov (United States)

    Isukapalli, Sastry S; Mazumdar, Sagnik; George, Pradeep; Wei, Binnian; Jones, Byron; Weisel, Clifford P

    2013-04-01

    Spraying of pesticides in aircraft cabins is required by some countries as part of a disinsection process to kill insects that pose a public health threat. However, public health concerns remain regarding exposures of cabin crew and passengers to pesticides in aircraft cabins. While large scale field measurements of pesticide residues and air concentrations in aircraft cabins scenarios are expensive and time consuming, Computational Fluid Dynamics (CFD) models provide an effective alternative for characterizing concentration distributions and exposures. This study involved CFD modeling of a twin-aisle 11 row cabin mockup with heated manikins, mimicking a part of a fully occupied Boeing 767 cabin. The model was applied to study the flow and deposition of pesticides under representative scenarios with different spraying patterns (sideways and overhead) and cabin air exchange rates (low and high). Corresponding spraying experiments were conducted in the cabin mockup, and pesticide deposition samples were collected at the manikin's lap and seat top for a limited set of five seats. The CFD model performed well for scenarios corresponding to high air exchange rates, captured the concentration profiles for middle seats under low air exchange rates, and underestimated the concentrations at window seats under low air exchange rates. Additionally, both the CFD and experimental measurements showed no major variation in deposition characteristics between sideways and overhead spraying. The CFD model can estimate concentration fields and deposition profiles at very high resolutions, which can be used for characterizing the overall variability in air concentrations and surface loadings. Additionally, these model results can also provide a realistic range of surface and air concentrations of pesticides in the cabin that can be used to estimate potential exposures of cabin crew and passengers to these pesticides.

  7. Lithofacies, depositional environments, regional biostratigraphy and age of the Chitarwata Formation in the Bugti Hills, Balochistan, Pakistan

    Science.gov (United States)

    Métais, Grégoire; Antoine, Pierre-Olivier; Baqri, S. R. Hassan; Crochet, Jean-Yves; De Franceschi, Dario; Marivaux, Laurent; Welcomme, Jean-Loup

    2009-02-01

    The Oligocene-early Miocene Chitarwata Formation records a critical interval of terrestrial sedimentation that predates the Siwalik deposits on the Potwar Plateau of north-central Pakistan. This Oligocene-early Miocene time interval has long been considered as lacking in the entire Indo-Pakistan region. The Chitarwata Formation is widely exposed in the Sulaiman Range, but has never been described in detail in the Sulaiman Lobe, where the famous fossiliferous strata called 'Bugti Bone Beds' have been known for over a century and half. The Chitarwata Formation represents coastal-delta at the base, and plain and fluvial environments at the top. Lithofacies and sedimentary structures of the Chitarwata Formation in the Bugti area are described in detail, and show a clearly distinct lithologic pattern, different from that reported from the Zinda Pir area. The Chitarwata Formation also records an important transition in the evolution of the drainage systems in the area during the late Paleogene and early Neogene. This transition from the west-flowing paleo-Indus fluvial system to the development of the ancestral Indus drainage system may explain the numerous hiatuses that characterize the Chitarwata Formation. The abundance of fossil mammals from the Chitarwata and overlying Vihowa formation in the Bugti Hills provides critical biochronologic information that sheds new light on biostratigraphic correlation with the Zinda Pir area and for the entire Sulaiman Range.

  8. Boron isotope systematics of tourmaline formation in the Sullivan Pb-Zn-Ag deposit, British Columbia, Canada

    Science.gov (United States)

    Jiang, S.-Y.; Palmer, M.R.; Slack, J.F.; Shaw, D.R.

    1999-01-01

    We report here the results of 54 boron isotope analyses of tourmaline associated with the giant Sullivan Pb-Zn-Ag deposit in southeastern British Columbia, Canada. The ??11B values range from -11.1 to -2.9???, which is almost as great as the range found worldwide in tourmalines from 33 massive sulfide deposits and tourmalinites in dominantly clastic metasedimentary terranes. The major control on the overall ??11B values of the Sullivan tourmalinites is the boron source. Potential controls over the large range of the data also include: (1) differences in formation temperatures of the tourmalinites, (2) different stages of tourmaline formation, (3) variations in the proportions of dissolved boron incorporated into the tourmaline (Rayleigh fractionation), (4) seawater entrainment, and (5) post-depositional metamorphism. The boron isotope data at Sullivan are consistent with boron derivation from leaching of footwall clastic sediments. However, the great abundance of tourmaline in the Sullivan deposit suggests that the local clastic sediments were not the sole source of boron, and we argue that non-marine evaporites, buried deep below the orebody, are the most viable source of this additional boron. It is likely that some of the variation in tourmaline ??11B values reflect mixing of boron from these two sources. Comparison of the potential effects of these controls with geologic and other geochemical evidence suggests that major causes for the wide range of ??11B values measured at Sullivan are seawater entrainment and Rayleigh fractionation, although in places, post-depositional alteration and thermal metamorphism were important in determining ??11B values of some of the recrystallized tourmalinites.

  9. Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Structural controls on hydrothermal alteration and ore mineralization

    Science.gov (United States)

    Berger, B.R.; Henley, R.W.

    2011-01-01

    High-sulfidation copper-gold lode deposits such as Chinkuashih, Taiwan, Lepanto, Philippines, and Goldfield, Nevada, formed within 1500. m of the paleosurface in volcanic terranes. All underwent an early stage of extensive advanced argillic silica-alunite alteration followed by an abrupt change to spatially much more restricted stages of fracture-controlled sulfide-sulfosalt mineral assemblages and gold-silver mineralization. The alteration as well as ore mineralization stages of these deposits were controlled by the dynamics and history of syn-hydrothermal faulting. At the Sulfate Stage, aggressive advanced argillic alteration and silicification were consequent on the in situ formation of acidic condensate from magmatic vapor as it expanded through secondary fracture networks alongside active faults. The reduction of permeability at this stage due to alteration decreased fluid flow to the surface, and progressively developed a barrier between magmatic-vapor expansion constrained by the active faults and peripheral hydrothermal activity dominated by hot-water flow. In conjunction with the increased rock strength resulting from alteration, subsequent fault-slip inversion in response to an increase in compressional stress generated new, highly permeable fractures localized by the embrittled, altered rock. The new fractures focused magmatic-vapor expansion with much lower heat loss so that condensation occurred. Sulfide Stage sulfosalt, sulfide, and gold-silver deposition then resulted from destabilization of vapor phase metal species due to vapor decompression through the new fracture array. The switch from sulfate to sulfide assemblages is, therefore, a logical consequence of changes in structural permeability due to the coupling of alteration and fracture dynamics rather than to changes in the chemistry of the fluid phase at its magmatic source. ?? 2010.

  10. A deltaic-sediment gravity flow depositional system in the Upper Triassic Yanchang Formation, Southwest Ordos Basin, China

    Science.gov (United States)

    Gao, Yi; Jiang, Zaixing; Liu, Shengqian

    2017-04-01

    The Ordos Basin, located in central China, is a large-scale residual Mesozoic intracratonic down-warped basin. It is the second largest and the most productive oil-gas-bearing basin in China. The Upper Triassic Yanchang Formation is characterized by fluvial-lacustrine facies. It can be subdivided into 10 stratigraphic sublayers (Ch1-Ch10 from top to bottom), and the Ch81 interval is an important oil-gas reservoir in this basin. For a long time, sandstones in this interval are interpreted to be deposited in a shallow water braided delta sedimentary system in the southwest of the basin. During deposition of this interval, the water is quite shallow, and there are no sediment gravity flow deposits. In this research, based mainly on core observation and description, as well as well logging and seismic data, we proposed that sediment gravity flow deposits are well-developed in the study area in the southwestern Ordos Basin. Four lithofacies assemblages have been recognized: (i) thick-bedded sandstone with abundant lamination structures as channelized sandy deposits in braided delta; (ii) thick-bedded chaotically contorted sandstone as sandy slump; (iii) thick-bedded structureless sandstone with floating mudstone clasts as sandy debrite, or with spaced planar lamination as high-density turbidite; (iv) thin-bedded ripple cross-laminated sandstone as low-density turbidite. On the basis of core evidence of a sedimentary cross-section along flow direction with six cored wells, the most possible trigger of sediment gravity flow is delta-front collapsing. Through downslope transportation, one type of gravity flow can transform to another type. Deltaic channelized sandstones are dominant in the proximal area. Sandy slumps are dominant in the middle area, which is formed by collapsing of deltaic deposits and transform to high density turbidite and sandy debrite in the distal area. Few low-density turbidite is shown. With additional geochemical evidence, it can be confidently

  11. Uplift and submarine formation of some Melanesian porphyry copper deposits: Stable isotope evidence

    Science.gov (United States)

    Chivas, A.R.; O'Neil, J.R.; Katchan, G.

    1984-01-01

    Hydrogen and oxygen isotope analyses of sericites and kaolinites from four young porphyry copper deposits (Ok Tedi (1.2 Ma) and Yandera (6.5 Ma), Papua New Guinea; Koloula (1.5 Ma), Solomon Islands; and Waisoi (ocean water. For Ok Tedi, the non-magmatic component was a meteoric water with an isotopic composition different from that of the present meteoric water in the region. The isotopic signature of the former meteoric water is consistent with a surface elevation of 200 m a.s.l. or less at the time of mineralization. The deposit was later exposed and supergene kaolinitization commenced at approximately 1200 m a.s.l. Uplift and erosion has continued to the present at which time the elevation of the exposed deposit is 1800 m a.s.l. This rate of uplift is consistent with that known from other geological evidence. If the rate of uplift were approximately constant during the last 1.2 Ma, the age of supergene enrichment can be dated at approximately 0.4 Ma B.P. Similarly, influx of meteoric water at Yandera occurred when the ground surface above the deposit was at an elevation of approximately 600 m a.s.l. The deposit's present elevation is 1600 m a.s.l. In this case a total uplift of approximately 2.2 km is indicated, with removal of 1.2 km of overburden by erosion. ?? 1984.

  12. Depositional conditions for the Kuna Formation, Red Dog Zn-PB-Ag-Barite District, Alaska, inferred from isotopic and chemical proxies

    Science.gov (United States)

    Johnson, Craig A.; Dumoulin, Julie A.; Burruss, Robert A.; Slack, John F.

    2015-01-01

    Water column redox conditions, degree of restriction of the depositional basin, and other paleoenvironmental parameters have been determined for the Mississippian Kuna Formation of northwestern Alaska from stratigraphic profiles of Mo, Fe/Al, and S isotopes in pyrite, C isotopes in organic matter, and N isotopes in bulk rock. This unit is important because it hosts the Red Dog and Anarraaq Zn-Pb-Ag ± barite deposits, which together constitute one of the largest zinc resources in the world. The isotopic and chemical proxies record a deep basin environment that became isolated from the open ocean, became increasingly reducing, and ultimately became euxinic. The basin was ventilated briefly and then became isolated again just prior to its demise as a discrete depocenter with the transition to the overlying Siksikpuk Formation. Ventilation corresponded approximately to the initiation of bedded barite deposition in the district, whereas the demise of the basin corresponded approximately to the formation of the massive sulfide deposits. The changes in basin circulation during deposition of the upper Kuna Formation may have had multiple immediate causes, but the underlying driver was probably extensional tectonic activity that also facilitated fluid flow beneath the basin floor. Although the formation of sediment-hosted sulfide deposits is generally favored by highly reducing conditions, the Zn-Pb deposits of the Red Dog district are not found in the major euxinic facies of the Kuna basin, nor did they form during the main period of euxinia. Rather, the deposits occur where strata were permeable to migrating fluids and where excess H2S was available beyond what was produced in situ by decomposition of local sedimentary organic matter. The known deposits formed mainly by replacement of calcareous strata that gained H2S from nearby highly carbonaceous beds (Anarraaq deposit) or by fracturing and vein formation in strata that produced excess H2S by reductive dissolution of

  13. Palaeontology of the upper Turonian paralic deposits of the Sainte-Mondane Formation, Aquitaine Basin, France

    Energy Technology Data Exchange (ETDEWEB)

    Neraudenau, D.; Saint Martin, S.; Battern, D.J.; Colin, J.P.; Daviero-Gomez, V.; Girard, V.; Gomez, B.; Nohra, Y.A.; Polette, F.; Platel, J.P.; Saint Martin, J.P.; Vullo, R.

    2016-07-01

    The upper Turonian lignite deposits of Sainte-Mondane, Dordogne (Aquitaine Basin, SW France), consist of clays bearing translucent, orange to red, amber micrograins. The amber exhibits different types of microbial inclusions. The clays contain several conifers including the genera Brachyphyllum, Frenelopsis and Glenrosa, and a few leaf fragments of eudicot angiosperms. Among the plant meso-fossils the occurrence of Costatheca, Spermatites and abundant, diverse, megaspores, including species of Ariadnaesporites, Bacutriletes, Echitriletes, Erlansonisporites, Maexisporites, Minerisporites and Verrutriletes, is noteworthy. Pollen grains of the Normapolles group are important components of the palynomorph assemblage. The clays were deposited in a calm, estuarine or lagoonal, muddy environment. The overlying lignitic sands contain large fossil wood pieces of the conifer Agathoxylon, small solitary corals, fragmentary oysters and pectinids, echinoid spines, a few teeth of marine selachians and bony fishes, but no amber is present. These sands were deposited in a high-energy coastal marine environment. (Author)

  14. The role of bitumen in strata-bound copper deposit formation in the Copiapo area, Northern Chile

    Science.gov (United States)

    Cisternas, M. Eugenia; Hermosilla, Juan

    2006-07-01

    In northern Chile, between 27 and 33°S, there are numerous deposits where residual petroleum is associated with Cu-(Ag) mineralisation (the most famous being El Soldado). All of these deposits are hosted by Lower Cretaceous volcanic or volcanoclastic facies along the axis of a former backarc basin. This close relationship suggests that the generation, migration and emplacement of hydrocarbons in the Cretaceous volcanic units is a regional process, associated with the evolution of the Cretaceous backarc basin and points to the importance of pyrobitumen as an exploration tool for similar Cu-(Ag) deposits. The present work analyses four small strata-bound copper deposits located along a north-south belt approximately 10 km east of Copiapó in northern Chile. These deposits are typically hosted by pyrobitumen-rich andesitic volcanic to volcanoclastic rocks intercalated with the marine carbonate Pabellón Formation, the youngest formation within the Chañarcillo Group. The strong genetic and spatial relationships between the pyrobitumen-rich lavas and the mineral deposits allow us to define this volcanic belt as the Ocoita-Pabellón Metallotect. Two hydrothermal events can be distinguished based on the mineralogical, textural, fluid inclusion and isotope data of ore and gangue and on the optical properties of residual petroleum. During the early event, petroleum was mobilised from the source rocks into the primary and secondary porosity of the lavas by Fe-rich hydrothermal fluids, which precipitated pyrite as an early sulphide phase. The second event is characterised by Cu-rich hydrothermal fluids, which induced three successive sub-stages of Cu-sulphide precipitation. The hydrothermal fluids chemically and thermally altered the first-stage bitumen, transforming it into pyrobitumen. The present work documents similarities between the Ocoita-Pabellón Metallotect and the El Soldado ore deposit and emphasises important differences. In the El Soldado host rocks, a

  15. Connectivity estimation between turbiditic channels and overbank deposits from the modelling of an outcrop analogue (Pab Formation, Maastrichitan, Pakistan).

    Science.gov (United States)

    Eschard, R.; Deschamps, R.; Doligez, B.; Lerat, O.

    2012-04-01

    Conceptual models showing the sedimentary architecture of the turbidite depositional systems and their evolution trough time, such as those published by E. Mutti and his school, were first established in the outcrop. At the reservoir scale, the field development of turbidite reservoirs now requires detailed reservoir models finely describing the distribution of the heterogeneity which may influence the reservoir dynamic behaviour during production. Information derived from quantified outcrop models can then be used to better constrain the reservoir models in the subsurface. Outcrops models first focused on the heterogeneity distribution within the channel conduits, emphasizing the diversity of the channel architecture regarding to the complexity of the depositional processes. The facies architecture of turbiditic overbank deposits laterally to the channels are even less understood than within the channels. If the general geometry of levees can be easily seen on seismic, their facies, and the sand/shale ratio close to the channel border, are poorly known as overflow deposits are rarely drilled in the subsurface, and crevasse lobes are below seismic resolution. The conceptual models of the overbank distribution at the reservoir scale must then rely on outcrops models. The questions on which we would like to focus are the followings: 1) What kind of facies model can we expect in the overbank deposits laterally to the channel conduits? 2) Do these facies constitute reservoir bodies with a significant volume? 3) Is there any heterogeneity between the channel conduits and the levees which may reduce their connectivity 4) Can overbank deposits, such as crevasses or spill over lobes, insure connectivity between two channel conduits and homogenise the pressure regime during the reservoir production? The relationship between channels and overbank are well exposed in the Pab mountain range outcrops, in Pakistan. In this paper, we propose to characterize the relationships

  16. EFFECT OF RESIDUAL STRESS ON THE MARTENSITIC TRANS- FORMATION OF SPUTTER-DEPOSITED SMA THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    L. Wang; D. Xu; B.C. Cai

    2002-01-01

    TiNi thin films were sputter-deposited on circular single-crystal silicon substrates un-der various sputtering parameters. The crystal structure and residual stress of the as-deposited films were determined by X-ray diffraction and substrate-curvature method.The phenomenon of stress-suppressed martensitic transformation was observed. It isconsidered that the residual stresses in SMA thin films based on circular substratesact as balanced biaxial tensile stresses. The status of equilibrant delays the align-ment of self-accommodated variants and the volume shrinkage during the martensitictransformation.

  17. Magnetron sputtering cluster apparatus for formation and deposition of size-selected metal nanoparticles

    DEFF Research Database (Denmark)

    Hanif, Muhammad; Popok, Vladimir

    2015-01-01

    The experimental setup utilizing a DC magnetron sputtering source for production of metal clusters, their size (mass) selection and following deposition in high vacuum is described. The source is capable to form clusters of various metals, for example, copper, silver, gold etc. Cluster size...... selection is achieved using an electrostatic quadrupole mass selector. The deposited silver clusters are studied using atomic force microscopy. The height distributions show typical relative standard size deviation of 9-13% for given sizes in the range between 5-23 nm. Thus, the apparatus demonstrates good...

  18. CONCENTRIC TUBE-FOULING RIG FOR INVESTIGATION OF FOULING DEPOSIT FORMATION FROM PASTEURISER OF VISCOUS FOOD LIQUID

    Directory of Open Access Journals (Sweden)

    N. I. KHALID

    2013-02-01

    Full Text Available This paper reports the work on developing concentric tube-fouling rig, a new fouling deposit monitoring device. This device can detect and quantify the level of fouling deposit formation. It can also functioning as sampler for fouling deposit study, which can be attached at any food processing equipment. The design is initiated with conceptual design. The rig is designed with inner diameter of 7 cm and with tube length of 37 cm. A spiral insert with 34.5 cm length and with 5.4 cm diameter is fitted inside the tube to ensure the fluid flows around the tube. In this work, the rig is attached to the lab-scale concentric tube-pasteurizer to test its effectiveness and to collect a fouling sample after pasteurization of pink guava puree. Temperature changes are recorded during the pasteurization and the data is used to plot the heat transfer profile. Thickness of the fouling deposit is also measured. The trends for thickness, heat resistance profile and heat transfer profile for concentric tube-fouling rig matched the trends obtained from lab-scale concentric tube-pasteurizer very well. The findings from this work have shown a good potential of this rig however there is a limitation with spiral insert, which is discussed in this paper.

  19. Rotational Brownian Dynamics simulations of clathrin cage formation

    Energy Technology Data Exchange (ETDEWEB)

    Ilie, Ioana M.; Briels, Wim J. [Computational BioPhysics, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Otter, Wouter K. den, E-mail: w.k.denotter@utwente.nl [Computational BioPhysics, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Multi Scale Mechanics, Faculty of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands)

    2014-08-14

    The self-assembly of nearly rigid proteins into ordered aggregates is well suited for modeling by the patchy particle approach. Patchy particles are traditionally simulated using Monte Carlo methods, to study the phase diagram, while Brownian Dynamics simulations would reveal insights into the assembly dynamics. However, Brownian Dynamics of rotating anisotropic particles gives rise to a number of complications not encountered in translational Brownian Dynamics. We thoroughly test the Rotational Brownian Dynamics scheme proposed by Naess and Elsgaeter [Macromol. Theory Simul. 13, 419 (2004); Naess and Elsgaeter Macromol. Theory Simul. 14, 300 (2005)], confirming its validity. We then apply the algorithm to simulate a patchy particle model of clathrin, a three-legged protein involved in vesicle production from lipid membranes during endocytosis. Using this algorithm we recover time scales for cage assembly comparable to those from experiments. We also briefly discuss the undulatory dynamics of the polyhedral cage.

  20. Rotational Brownian dynamics simulations of clathrin cage formation.

    Science.gov (United States)

    Ilie, Ioana M; den Otter, Wouter K; Briels, Wim J

    2014-08-14

    The self-assembly of nearly rigid proteins into ordered aggregates is well suited for modeling by the patchy particle approach. Patchy particles are traditionally simulated using Monte Carlo methods, to study the phase diagram, while Brownian Dynamics simulations would reveal insights into the assembly dynamics. However, Brownian Dynamics of rotating anisotropic particles gives rise to a number of complications not encountered in translational Brownian Dynamics. We thoroughly test the Rotational Brownian Dynamics scheme proposed by Naess and Elsgaeter [Macromol. Theory Simul. 13, 419 (2004); Naess and Elsgaeter Macromol. Theory Simul. 14, 300 (2005)], confirming its validity. We then apply the algorithm to simulate a patchy particle model of clathrin, a three-legged protein involved in vesicle production from lipid membranes during endocytosis. Using this algorithm we recover time scales for cage assembly comparable to those from experiments. We also briefly discuss the undulatory dynamics of the polyhedral cage.

  1. GVE-Based Dynamics and Control for Formation Flying Spacecraft

    Science.gov (United States)

    Breger, Louis; How, Jonathan P.

    2004-01-01

    Formation flying is an enabling technology for many future space missions. This paper presents extensions to the equations of relative motion expressed in Keplerian orbital elements, including new initialization techniques for general formation configurations. A new linear time-varying form of the equations of relative motion is developed from Gauss Variational Equations and used in a model predictive controller. The linearizing assumptions for these equations are shown to be consistent with typical formation flying scenarios. Several linear, convex initialization techniques are presented, as well as a general, decentralized method for coordinating a tetrahedral formation using differential orbital elements. Control methods are validated using a commercial numerical propagator.

  2. Oman metamorphic sole formation reveals early subduction dynamics

    Science.gov (United States)

    Soret, Mathieu; Agard, Philippe; Dubacq, Benoît; Plunder, Alexis; Ildefonse, Benoît; Yamato, Philippe; Prigent, Cécile

    2016-04-01

    Metamorphic soles correspond to m to ~500m thick tectonic slices welded beneath most of the large-scale ophiolites. They typically show a steep inverted metamorphic structure where the pressure and temperature conditions of crystallization increase upward (from 500±100°C at 0.5±0.2 GPa to 800±100°C at 1.0±0.2 GPa), with isograds subparallel to the contact with the overlying ophiolitic peridotite. The proportion of mafic rocks in metamorphic soles also increases from the bottom (meta-sediments rich) to the top (approaching the ophiolite peridotites). These soles are interpreted as the result of heat transfer from the incipient mantle wedge toward the nascent slab (associated with large-scale fluid transfer and possible shear heating) during the first My of intra-oceanic subduction (as indicated by radiometric ages). Metamorphic soles provide therefore major constraints on early subduction dynamics (i.e., thermal structure, fluid migration and rheology along the nascent slab interface). We present a detailed structural and petrological study of the metamorphic sole from 4 major cross-sections along the Oman ophiolite. We show precise pressure-temperature estimates obtained by pseudosection modelling and EBSD measurements performed on both the garnet-bearing and garnet-free high-grade sole. Results allow quantification of the micro-scale deformation and highlight differences in pressure-temperature-deformation conditions between the 4 different locations, showing that the inverted metamorphic gradient through the sole is not continuous in all locations. Based on these new constraints, we suggest a new tectonic-petrological model for the formation of metamorphic soles below ophiolites. This model involves the stacking of several homogeneous slivers of oceanic crust leading to the present-day structure of the sole. In this view, these thrusts are the result of rheological contrasts between the sole and the peridotite as the plate interface progressively cools down

  3. STUDY OF DYNAMIC MECHANICAL PROPERTIES OF FUSED DEPOSITION MODELLING PROCESSED ULTEM MATERIAL

    Directory of Open Access Journals (Sweden)

    Adhiyamaan Arivazhagan

    2014-01-01

    Full Text Available Fused Deposition Modelling (FDM, a renowned Rapid Prototyping (RP process, has been successfully implemented in several industries to fabricate concept models and prototypes for rapid manufacturing. This study furnishes terse notes about the material damping properties of FDM made ULTEM samples considering the effect of FDM process parameters. Dynamic Mechanical Analysis (DMA is carried out using DMA 2980 equipment to study the dynamic response of the FDM material subjected to single cantilever loading under periodic stress. Three FDM process parameters namely Build Style, Raster Width and Raster Angle were contemplated. ULTEM parts are fabricated using solid normal build style and three values each of raster width and raster angle. DMA is performed with temperature sweep at three different fixed frequencies of 1, 50 and 100 Hz. Results were obtained for dynamic properties such as Maximum Storage Modulus, Maximum Loss Modulus, Maximum Tan Delta and Maximum Complex Viscosity. The present work discusses the effect of increasing the frequencies and temperature on FDM made ULTEM samples using different FDM process parameters.

  4. Reworking Intensity—A Key Factor Leading to the Formation of Superlarge Gold Deposits in Greenstone Belts and Metamorphosed Microclastic Rocks in China

    Institute of Scientific and Technical Information of China (English)

    王秀璋; 陆德复; 等

    1999-01-01

    The greenstone belt and metamorphosed microclastic rock-type superlarge gold deposits in China are hosted in metamorphic rocks and later intrusive bodies.Sedimentation.regional metamorphism and mineralization contributed a lot to the formation of the deposits,so did remelting magmatic process to some deposits,but the deposits were finally formed by reworking processes.The key factor leading to the formation of superlarge gold deposits is the reworking intensity,which for superlarge gold deposits is reflected by the large-scale reworked source rocks and even ore materials of various sources,strongly oxidized ore-forming fluids with a long and repeated active history and stable geothermal heat current.The factor which decides the reworking intensity is the network consisting of structures of different classes.

  5. Formation of tilted clusters in the electrochemical deposition of copper on n-gas(001)

    DEFF Research Database (Denmark)

    Smilgies, D.M.; Feidenhans'l, Robert Krarup; Scherb, G.

    1996-01-01

    Using in-situ synchrotron X-ray diffraction, we have studied the epitaxial properties of Cu clusters electrochemically deposited on n-GaAs(001) substrates. The Cu clusters have (001) base planes and their [100] directions are aligned with the [110] directions of the GaAs(001) surface unit cell, b...

  6. Lithofacies, depositional environments, and regional stratigraphy of the lower Eocene Ghazij Formation, Balochistan, Pakistan

    Science.gov (United States)

    Johnson, Edward A.; Warwick, P.D.; Roberts, S.B.; Khan, I.H.

    1999-01-01

    A regional stratigraphic investigation of one of the most important coal-bearing lithostratigraphic units in Pakistan, the report includes sedimentologic observations taken from outcrops and measured sections, information derived from petrographic and paleontologic analyses, depositional interpretations, and descriptions of regional trends.

  7. Biomimetic formation of titania thin films: effect of amino acids on the deposition process.

    Science.gov (United States)

    Durupthy, Olivier; Jeurgens, Lars P H; Bill, Joachim

    2011-05-01

    Different types of amino acids have been used as additives to control the aqueous deposition of titanium dioxide thin films on single-crystal Si wafers. Thin titania films can be obtained through a chemical bath deposition (CBD) process using TiCl₄ as a precursor in an aqueous solution at temperatures below 100 °C. The addition of amino acids to the deposition solution was shown to reduce the thickness and roughness of the films and to increase their density. These protein building blocks were employed to modify the deposition rate as well as the size of aggregates that form the film. The thickness, crystallinity, morphology and composition of the grown films were characterized by a variety of techniques, including XRD, XPS, AFM and SEM. The consequences of the type of the amino acid additive (and its concentration in the solution) on the microstructural evolutions of the deposed films are thus revealed and discussed on the basis of the organic-inorganic interactions in solution and at the film surface.

  8. Facies distribution, depositional environment, and petrophysical features of the Sharawra Formation, Old Qusaiba Village, Central Saudi Arabia

    Science.gov (United States)

    Abbas, Muhammad Asif; Kaminski, Michael; Umran Dogan, A.

    2016-04-01

    The Silurian Sharawra Formation has great importance as it rests over the richest source rock of the Qusaiba Formation in central Saudi Arabia. The Sharawra Formation has four members including Jarish, Khanafriyah, Nayyal, and Zubliyat. The formation mainly consists of sandstone and siltstone with subordinate shale sequences. The lack of published research on this formation requires fundamental studies that can lay the foundation for future research. Three outcrops were selected from the Old Qusaiba Village in Central Saudi Arabia for field observations, petrographical and petrophysical study. Thin section study has been aided by quantitative mineralogical characterization using scanning electron microscopy - energy dispersive spectroscopy and powder x-ray diffraction (XRD) for both minerals, cements, and clay minerals (detrital and authigenic). The outcrops were logged in detail and nine different lithofacies have been identified. The thin section study has revealed the Sharawra Formation to be mainly subarkosic, while the mica content increases near to its contact with the Qusaiba Formation. The XRD data has also revealed a prominent change in mineralogy with inclusion of minerals like phlogopite and microcline with depths. Field observations delineated a prominent thinning of strata as lithofacies correlation clearly shows the thinning of strata in the southwestern direction. The absence of outcrop exposures further supports the idea of southwestern thinning of strata. This is mainly attributed to local erosion and the presence of thicker shale interbeds in the southeastern section, which was probably subjected to more intense erosion than the northwestern one. The Sharawra Formation rests conformably over the thick transgressive shale sequence, deposited during the post glacial depositional cycle. The lowermost massive sandstone bed of the Sharawra Formation represents the beginning of the regressive period. The shale interbeds in the lower part are evidence of

  9. Dynamic implications of ridges on a debris avalanche deposit at Tutupaca volcano (southern Peru)

    Science.gov (United States)

    Valderrama, Patricio; Roche, Olivier; Samaniego, Pablo; van Wyk de Vries, Benjamin; Bernard, Karine; Mariño, Jersy

    2016-02-01

    Catastrophic volcanic landslides can involve different parts of a volcano that can be incorporated into any resulting debris avalanche. The different material properties may influence the mechanical behaviour and, hence, the emplacement mechanisms of the different avalanche units. We present data from a coupled hydrothermal- and magmatic-related volcanic landslide at Tutupaca volcano (Peru). Around ad 1802, the hydrothermal system under Tutupaca's growing dacite dome failed, creating a debris avalanche that triggered a large explosive eruption. A typical debris avalanche hummocky unit is found, formed out of rock from the dome foot and the underlying hydrothermally altered lavas. It is covered by a more widespread and remarkable deposit that contains remnants of the hot dome core and the inner hydrothermal material. This deposit has ridges 20-500-m long, 10-30-m wide and 1-5-m high, regularly spaced and that fan slightly outward. Cross sections exposed within the ridges reveal coarser cores and finer troughs, suggesting grain size segregation during emplacement. Ridge morphology and granulometry are consistent with fingering known to occur in granular flows. The ridges are also associated with large blocks that have evidence of differential movement compared with the rest of the flowing mass. The presence of both ridged and hummocky deposits in the same event shows that, as different lithologies combine and collapse sequentially, materials with different mechanical properties can coexist in one landslide, leading to contrasting emplacement dynamics. The different structures thus highlight the complexity of such hazardous volcanic events and show the difficulty we face with modelling them.

  10. Dynamic Characterization of Dendrite Deposition and Growth in Li-Surface by Electrochemical Impedance Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Maya, R; Rosas, O; Saunders, J; Castaneda, H

    2015-01-13

    The evolution of dendrite formation is characterized by DC and AC electrochemical techniques. Interfacial mechanisms for lithium deposition are described and quantified by electrochemical impedance spectroscopy (EIS) between a lithium electrode and a graphite electrode. The initiation and growth of dendrites in the lithium surface due to the cathodic polarization conditions following anodic dissolution emulate long term cycling process occurring in the lithium electrodes. The dendrite initiation at the lithium/organic electrolyte interface is proposed to be performed through a combination of layering and interfacial reactions during different cathodic conditions. The growth is proposed to be performed by surface geometrical deposition. In this work, we use EIS in galvanostatic mode to assess the initiation and growth stages of dendrites by the accumulation of precipitates formed under different current conditions. The lithium/organic solvent experimental system using frequency domain techniques is validated by the theoretical approach using a deterministic model that accounts for the faradaic processes at the interface assuming a coverage fraction of the electrodic surface affected by the dendritic growth. (C) 2015 The Electrochemical Society. All rights reserved.

  11. Dry Deposition, Surface Production and Dynamics of Aerosols in the Marine Boundary Layer

    DEFF Research Database (Denmark)

    Fairall, C.W.; Larsen, Søren Ejling

    1984-01-01

    A model of downward aerosol panicle flux characterized by dry deposition velocity, Vd, due to Slinn and Slinn (1980) is generalized to the case of nonzero surface concentration (absorbing surface with a surface source). A more general expression for the flux at some reference height is developed...... which includes Vd and an effective surface source strength, Si, which is a function of the true surface source strength, Si, and the particle transport properties below the reference height. The general expression for the surface flux is incorporated into a dynamic mixed layer model of the type...... developed by Davidson et al. (1983). This three layer model (diffusion sublayer, turbulent surface layer and mixed layer) is applied to an open ocean marine regime where boundary layer advection is ignored. The aerosol concentration in the boundary layer is considered to consist of sea salt particles...

  12. Research on framework for formation control of multiple underwater robots in a dynamic environment

    Institute of Scientific and Technical Information of China (English)

    MENG Xian-song; XU Hong-gen; ZHANG Ming-jun

    2004-01-01

    In this paper a practical framework is proposed to keep formation control of multiple underwater robots in a dynamic environment. The approach is a viable solution to solve formation problem. The approach allows online planning of the formation paths using a Dijkstra's search algorithm based on the current sensor data. The formation is allowed to be dynamically changed in order to avoid obstacles in the environment. A controller is designed to keep the robots in their planned trajectories. It is shown that the approach is effec In this paper a practical framework is proposed to keep formation control of multiple underwater robots in a dynamic environment. The approach is a viable solution to solve formation problem.

  13. Investigation into the Formation and Adhesion of Cyclopentane Hydrates on Mechanically Robust Vapor-Deposited Polymeric Coatings.

    Science.gov (United States)

    Sojoudi, Hossein; Walsh, Matthew R; Gleason, Karen K; McKinley, Gareth H

    2015-06-09

    Blockage of pipelines by formation and accumulation of clathrate hydrates of natural gases (also called gas hydrates) can compromise project safety and economics in oil and gas operations, particularly at high pressures and low temperatures such as those found in subsea or arctic environments. Cyclopentane (CyC5) hydrate has attracted interest as a model system for studying natural gas hydrates, because CyC5, like typical natural gas hydrate formers, is almost fully immiscible in water; and thus CyC5 hydrate formation is governed not only by thermodynamic phase considerations but also kinetic factors such as the hydrocarbon/water interfacial area, as well as mass and heat transfer constraints, as for natural gas hydrates. We present a macroscale investigation of the formation and adhesion strength of CyC5 hydrate deposits on bilayer polymer coatings with a range of wettabilities. The polymeric bilayer coatings are developed using initiated chemical vapor deposition (iCVD) of a mechanically robust and densely cross-linked polymeric base layer (polydivinylbenzene or pDVB) that is capped with a covalently attached thin hydrate-phobic fluorine-rich top layer (poly(perfluorodecyl acrylate) or pPFDA). The CyC5 hydrates are formed from CyC5-in-water emulsions, and differential scanning calorimetry (DSC) is used to confirm the thermal dissociation properties of the solid hydrate deposits. We also investigate the adhesion of the CyC5 hydrate deposits on bare and bilayer polymer-coated silicon and steel substrates. Goniometric measurements with drops of CyC5-in-water emulsions on the coated steel substrates exhibit advancing contact angles of 148.3 ± 4.5° and receding contact angles of 142.5 ± 9.8°, indicating the strongly emulsion-repelling nature of the iCVD coatings. The adhesion strength of the CyC5 hydrate deposits is reduced from 220 ± 45 kPa on rough steel substrates to 20 ± 17 kPa on the polymer-coated steel substrates. The measured strength of CyC5 hydrate

  14. Simultaneous coastal measurements of ozone deposition fluxes and iodine-mediated particle emission fluxes with subsequent CCN formation

    Directory of Open Access Journals (Sweden)

    J. D. Whitehead

    2010-01-01

    Full Text Available Here we present the first observations of simultaneous ozone deposition fluxes and ultrafine particle emission fluxes over an extensive infra-littoral zone. Fluxes were measured by the eddy covariance technique at the Station Biologique de Roscoff, on the coast of Brittany, north-west France. This site overlooks a very wide (3 km littoral zone controlled by very deep tides (9.6 m exposing extensive macroalgae beds available for significant iodine mediated photochemical production of ultrafine particles. The aspect at the Station Biologique de Roscoff provides an extensive and relatively flat, uniform fetch within which micrometeorological techniques may be utilized to study links between ozone deposition to macroalgae (and sea water and ultrafine particle production.

    Ozone deposition to seawater at high tide was significantly slower (vd[O3]=0.302±0.095 mm s−1 than low tidal deposition. A statistically significant difference in the deposition velocities to macroalgae at low tide was observed between night time (vd[O3]=1.00±0.10 mm s−1 and daytime (vd[O3]=2.05±0.16 mm s−1 when ultrafine particle formation results in apparent particle emission. Very high emission fluxes of ultrafine particles were observed during daytime periods at low tides ranging from 50 000 particles cm−2 s−1 to greater than 200 000 particles cm−2 s−1 during some of the lowest tides. These emission fluxes exhibited a significant relationship with particle number concentrations comparable with previous observations at another location. Apparent particle growth rates were estimated to be in the range 17–150 nm h−1 for particles in the size range 3–10 nm. Under certain conditions, particle growth may be inferred to continue to greater than 120 nm over tens

  15. Sedimentary facies and sequential architecture of tide-influenced alluvial deposits : an example from the middle Eocene Capella formation, South-Central Pyrenees, Spain

    NARCIS (Netherlands)

    Cuevas Gozalo, M.C

    1989-01-01

    The sediments investigated consist of a thick sequence of clastic deposits of middle Eocene age, the Capella Formation. At the time of deposition the sedimentary basin was tectonically active. Tectonic influence in the sedimentary sequence is recognized from angular unconformities, synsedimentary fa

  16. Formation of protective deposits by anti-erosive toothpastes-A microscopic study on enamel with artificial defects.

    Science.gov (United States)

    Bradna, Pavel; Vrbova, Radka; Fialova, Vlasta; Housova, Devana; Gojisova, Eva

    2016-09-01

    This study investigated formation of protective deposits on the enamel surface after application of several anti-erosive toothpastes with different active ingredients. NaF-containing Sensodyne Pronamel, SnCl2 /F-based Elmex Erosion Protection and calcium phosphate-based BioRepair Plus Sensitivity Control, SensiShield and Enamel Care toothpastes with claimed anti-erosive properties were tested. Artificial saliva and Elmex Erosion Protection mouth rinse served as control groups. The toothpastes were applied 30 times by a toothbrush for 2 min per day, mouth rinse for 30 s on polished enamel of thirty five human molars (n = 5) with series of five rhomboid-shaped indents of various length prepared by a Knoop indentor. After 15 and 30 applications, the shape of the indents and surface morphology was characterised using light and scanning electron microscopy. At the end of treatment, the samples were exposed to 0.2 wt. % citric acid (pH 3.30) to test resistance of the treated enamel to erosion. Pronounced differences were observed between protective properties of the toothpastes. While Sensodyne Pronamel and BioRepair Plus Sensitivity Control did not produce any protective deposits, Enamel Care formed a compact layer of deposits which protected the enamel surface against erosion. With Elmex Erosion Protection and SensiShield fractured indent edges and scratches on the treated enamel suggested that their abrasive properties prevailed over ability of active ingredients to form deposits. These results revealed that toothpastes with strong potential to form acid-resistant deposits on the enamel surface and of low abrasivity should be used for effective prevention of enamel erosion. SCANNING 38:380-388, 2016. © 2015 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  17. Stratigraphy, correlation, depositional setting, and geophysical characteristics of the Oligocene Snowshoe Mountain Tuff and Creede Formation in two cored boreholes

    Science.gov (United States)

    Larsen, Daniel; Nelson, Philip H.

    2000-01-01

    Core descriptions and geophysical logs from two boreholes (CCM-1 and CCM-2) in the Oligocene Snowshoe Mountain Tuff and Creede Formation, south-central Colorado, are used to interpret sedimentary and volcanic facies associations and their physical properties. The seven facies association include a mixed sequence of intracaldera ash-flow tuffs and breccias, alluvial and lake margin deposits, and tuffaceous lake beds. These deposits represent volcanic units related to caldera collapse and emplacement of the Snowshoe Mountain Tuff, and sediments and pyroclastic material deposited in the newly formed caldera basin, Early sedimentation is interpreted to have been rapid, and to have occurred in volcaniclastic fan environments at CCM-1 and in a variery of volcaniclastic fan, braided stream shallow lacustrine, and mudflat environments at CCM-2. After an initial period of lake-level rise, suspension settling, turbidite, and debris-flow sedimentation occurred in lacustrine slope and basin environments below wave base. Carbonate sedimentation was initially sporadic, but more continuous in the latter part of the recorded lake history (after the H fallout tuff). Sublacustrine-fan deposition occurred at CCM-1 after a pronounced lake-level fall and subsequent rise that preceded the H tuff. Variations in density, neutron, gamma-ray, sonic, and electrical properties of deposits penetrated oin the two holes reflect variations in lithology, porosity, and alteration. Trends in the geophysical properties of the lacustrine strata are linked to downhole changes in authigenic mineralology and a decrease in porosity interpreted to have resulted primarily from diagenesis. Lithological and geophysical characteristics provide a basis for correlation of the cores; however, mineralogical methods of correlation are hampered by the degree of diagenesis and alteration.

  18. The rudist buildup depositional model, reservoir architecture and development strategy of the cretaceous Sarvak formation of Southwest Iran

    Directory of Open Access Journals (Sweden)

    Yang Du

    2015-03-01

    Full Text Available This paper studies the lithofacies, sedimentary facies, depositional models and reservoir architecture of the rudist-bearing Sar-3 zone of Cretaceous Sarvak in the Southwest of Iran by utilizing coring, thin section, XRD data of five coring wells and 3D seismic data. Research results include the following: According to lithofacies features and their association, the rudist-mound and tidal flat are the main microfacies in the Sar-3 depositional time. By investigating the regional tectonic setting and seismic interpretation, a depositional model was built for the Sar-3 zone, which highlights four key points: 1 The distribution of the rudist-buildup is controlled by the paleo-high. 2 The build-up outside of the wide colonize stage but reached the wave-base level in a short time by regression and formation uplift, and was destroyed by the high energy current, then forming the moundy allochthonous deposition after being dispersed and redeposited. 3 The tidal flat develops widely in the upper Sar-3, and the deposition thickness depends on the paleo-structure. The tidal channel develops in the valley and fringe of the Paleo-structure. 4 The exposure within the leaching effect by the meteoric water of the top of Sar-3 is the main controlling factor of the reservoir vertical architecture. The Sar-3 zone featured as the dualistic architecture consists of two regions: the lower is the rudist reef limestone reservoir and the upper is the tidal condense limestone interlayer. The thickness of each is controlled by the paleo-structure. The Paleo-high zone is the preferential development zone. Based on reservoir characteristics of the different zones, a targeted development strategy has been proposed. Keeping the trajectory in the middle of the oil-layer in the paleo-high, and in the paleo-low, make the trajectory crossing the oil-zone and then keep it in the lower.

  19. The role of phase separation for self-organized surface pattern formation by ion beam erosion and metal atom co-deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hofsaess, H.; Zhang, K.; Pape, A.; Bobes, O.; Broetzmann, M. [Georg-August University Goettingen, II. Institute of Physics, Goettingen (Germany)

    2013-05-15

    We investigate the ripple pattern formation on Si surfaces at room temperature during normal incidence ion beam erosion under simultaneous deposition of different metallic co-deposited surfactant atoms. The co-deposition of small amounts of metallic atoms, in particular Fe and Mo, is known to have a tremendous impact on the evolution of nanoscale surface patterns on Si. In previous work on ion erosion of Si during co-deposition of Fe atoms, we proposed that chemical interactions between Fe and Si atoms of the steady-state mixed Fe{sub x} Si surface layer formed during ion beam erosion is a dominant driving force for self-organized pattern formation. In particular, we provided experimental evidence for the formation of amorphous iron disilicide. To confirm and generalize such chemical effects on the pattern formation, in particular the tendency for phase separation, we have now irradiated Si surfaces with normal incidence 5 keV Xe ions under simultaneous gracing incidence co-deposition of Fe, Ni, Cu, Mo, W, Pt, and Au surfactant atoms. The selected metals in the two groups (Fe, Ni, Cu) and (W, Pt, Au) are very similar regarding their collision cascade behavior, but strongly differ regarding their tendency to silicide formation. We find pronounced ripple pattern formation only for those co deposited metals (Fe, Mo, Ni, W, and Pt), which are prone to the formation of mono and disilicides. In contrast, for Cu and Au co-deposition the surface remains very flat, even after irradiation at high ion fluence. Because of the very different behavior of Cu compared to Fe, Ni and Au compared to W, Pt, phase separation toward amorphous metal silicide phases is seen as the relevant process for the pattern formation on Si in the case of Fe, Mo, Ni, W, and Pt co-deposition. (orig.)

  20. Dynamic Transition and Pattern Formation in Taylor Problem

    Institute of Scientific and Technical Information of China (English)

    Tian MA; Shouhong WANG

    2010-01-01

    The main objective of this article is to study both dynamic and structural transitions of the Taylor-Couette flow,by using the dynamic transition theory and geometric theory of incompressible flows developed recently by the authors.In particular,it is shown that as the Taylor number crosses the critical number,the system undergoes either a continuous or a jump dynamic transition,dictated by the sign of a computable,nondimensional parameter R.In addition,it is also shown that the new transition states have the Taylor vortex type of flow structure,which is structurally stable.

  1. Anomalous approach to thermodynamic equilibrium: Structure formation of molecules after vapor deposition

    Science.gov (United States)

    Jana, Pritam Kumar; Wang, Can; Jack, Robert L.; Chi, Lifeng; Heuer, Andreas

    2015-11-01

    We describe experiments and computer simulations of molecular deposition on a substrate in which the molecules (substituted adenine derivatives) self-assemble into ordered structures. The resulting structures depend strongly on the deposition rate (flux). In particular, there are two competing surface morphologies (α and β ), which differ by their topology (interdigitated vs lamellar structure). Experimentally, the α phase dominates at both low and high flux, with the β phase being most important in the intermediate regime. A similar nonmonotonic behavior is observed on varying the substrate temperature. To understand these effects from a theoretical perspective, a lattice model is devised which reproduces qualitatively the topological features of both phases. Via extensive Monte Carlo studies we can, on the one hand, reproduce the experimental results and, on the other hand, obtain a microscopic understanding of the mechanisms behind this anomalous behavior. The results are discussed in terms of an interplay between kinetic trapping and temporal exploration of configuration space.

  2. Saharan dust deposition in the Carpathian Basin and its possible effects on interglacial soil formation

    Science.gov (United States)

    Varga, György; Cserháti, Csaba; Kovács, János; Szalai, Zoltán

    2016-09-01

    Several hundred tons of windblown dust material are lifted into the atmosphere and are transported every year from Saharan dust source areas towards Europe having an important climatic and other environmental effect also on distant areas. According to the systematic observations of modern Saharan dust events, it can be stated that dust deflated from North African source areas is a significant constituent of the atmosphere of the Carpathian Basin and Saharan dust deposition events are identifiable several times in a year. Dust episodes are connected to distinct meteorological situations, which are also the determining factors of the different kinds of depositional mechanisms. By using the adjusted values of dust deposition simulations of numerical models, the annual Saharan dust flux can be set into the range of 3.2-5.4 g/m2/y. Based on the results of past mass accumulation rates calculated from stratigraphic and sedimentary data of loess-paleosol sequences, the relative contribution of Saharan dust to interglacial paleosol material was quantified. According to these calculations, North African exotic dust material can represent 20-30% of clay and fine silt-sized soil components of interglacial paleosols in the Carpathian Basin. The syngenetic contribution of external aeolian dust material is capable to modify physicochemical properties of soils and hereby the paleoclimatic interpretation of these pedogene stratigraphic units.

  3. The Formation of Nanocrystalline Diamond Coating on WC Deposited by Microwave Assisted Plasma CVD

    Science.gov (United States)

    Toff, M. R. M.; Hamzah, E.; Purniawan, A.

    2010-03-01

    Diamond is one form of carbon structure. The extreme hardness and high chemical resistant of diamond coatings determined that many works on this area relate to coated materials for tribological applications in biomedicine, as mechanical seals or cutting tools for hard machining operations. In the work, nanocrystalline diamond (NCD) coated tungsten carbide (WC) have been deposited by microwave assisted plasma chemical vapor deposition (MAPCVD) from CH4/H2 mixtures. Morphology of NCD was investigated by using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The quality of NCD is defined as ratio between diamond and non diamond and also full width at half maximum (FWHM) was determined using Raman spectra. The result found that the NCD structure can be deposited on WC surface using CH4/H2 gas mixture with grain size ˜20 nm to 100 nm. Increase %CH4 concentration due to increase the nucleation of NCD whereas decrease the quality of diamond. Based on Raman spectra, the quality of NCD is in the range ˜98.82-99.01% and 99.56-99.75% for NCD and microcrystalline (MCD), respectively. In addition, FWHM of NCD is high than MCD in the range of 8.664-62.24 cm-1 and 4.24-5.05 cm-1 for NCD and MCD respectively that indicate the crystallineity of NCD is smaller than MCD.

  4. Understanding of amount and dynamics of radioactive cesium deposited on trees in Fukushima

    Energy Technology Data Exchange (ETDEWEB)

    Endo, Izuki; Ohte, Nobuhito; Iseda, Kohei; Tanoi, Keitaro; Hirose, Atsushi; Kobayashi, Natsuko I. [The University of Tokyo, 113-8657, 1-1-1 Yayoi Bunkyo-ku, Tokyo (Japan); Ishii, Nobuyoshi [National Institute of Radiological Sciences, 263-8555, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba (Japan); Ohashi, Mizue [University of Hyogo, 670-0092, 1-1-12 Shinzaike-Honcho, Himeji, Hyogo (Japan)

    2014-07-01

    The accident of Fukushima Daiichi nuclear power plant after the earthquake and Tsunami in March 11, 2011 caused large amount of radioactive cesium ({sup 134}Cs, {sup 137}Cs) deposition onto the forest in the surrounding areas. River water from the forest area is used for food production and also for drinking water in these regions. In order to predict how radioactive Cs diffuse and discharge from the forest catchments, it is important to understand the amount and dynamics of radioactive Cs deposited on the trees. In this report, we show our preliminary results of {sup 137}Cs deposition in forest. Study was conducted in the forest at the upstream of Kami-Oguni River catchment, northern part of Fukushima Prefecture. Three plots (2 deciduous stands and 1 Japanese cedar (Cryptomeria japonica) plantation) were set in the forest. Quercus serrata and C. japonica, a representative of deciduous and evergreen tree species in this region, were chosen from each plot. Sample trees were logged in October 2012. Stem samples were collected every 2 m from above the ground to tree top and separated into bark, sapwood and heartwood. Litter traps were set in each plot and collected every month. Leaf litter was classified among species. Also, soil samples were collected in the cylinder of 5 cm in diameter and maximum 30 cm in depth from the forest floor every month. {sup 137}Cs concentration of all samples were measured by germanium semiconductor detector or NaI(Tl) scintillation counter. Deposited {sup 137}Cs was attached strongly on the bark of Q. serrata at high concentration (9-18 kBq/kg) but there were no clear relationship with tree height. In C. japonica, {sup 137}Cs concentration was about half times lower than that of Q. serrata at 0-10 m part of the tree. {sup 137}Cs concentration in wood of C. japonica was higher than Q. serrata. {sup 137}Cs concentration of sapwood was as high as that of heartwood in C. japonica, but in Q. serrata, {sup 137}Cs concentration in sapwood was

  5. The Eocene Rusayl Formation, Oman, carbonaceous rocks in calcareous shelf sediments: Environment of deposition, alteration and hydrocarbon potential

    Energy Technology Data Exchange (ETDEWEB)

    Dill, H.G.; Wehner, H.; Kus, J. [Federal Institute for Geosciences and Natural Resources, P.O. Box 510163, D-30631 Hannover (Germany); Botz, R. [University Kiel, Geological-Paleontological Department, Olshausenstrasse 40-60, D-24118 Kiel (Germany); Berner, Z.; Stueben, D. [Technical University Karlsruhe, Institute for Mineralogy and Geochemistry, Fritz-Haber-Weg 2, D-76131 Karlsruhe (Germany); Al-Sayigh, A. [Sultan Qaboos University, Geological Dept. PO Box 36, Al-Khod (Oman)

    2007-10-01

    Paralic carbonaceous series intercalated among calcareous shelf sediments have seldom been investigated. During the early Eocene, calcareous and siliciclastic sediments were deposited on a wide shelf in front of low-reliefed hinterland in the Al Khawd region in NE Oman. The siliciclastic-calcareous sediments originated from strongly reworked debris of the Arabic Shield. The underlying Semail Ophiolite did not act as a direct source of debris but provided some heat to increase the maturity of carbonaceous rocks and modify the isotope signal of the calcareous minerals in the Rusayl Formation. A multidisciplinary approach involving sedimentology, mineralogy, chemistry, coal petrography and paleontology resulted in the establishment of nine stratigraphic lithofacies units and provides the reader with a full picture from deposition of the mixed carbonaceous-calcareous-siliciclastic rocks to the most recent stages of post-depositional alteration of the Paleogene formations. The calcareous Jafnayn Formation (lithofacies unit I) developed in a subtidal to intertidal regime, influenced episodically by storms. Deepening of the calcareous shelf towards younger series was ground to a halt by paleosols developing on a disconformity (lithofacies unit II) and heralding the onset of the Rusayl Formation. The stratigraphic lithofacies units III and IV reflect mangrove swamps which from time to time were flooded through washover fans from the open sea. The presence of Spinozonocolpites and the taxon Avicennia, which today belong to a coastal marsh vegetational community, furnish palynological evidence to the idea of extensive mangrove swamps in the Rusayl Formation [El Beialy, S.Y., 1998. Stratigraphic and palaeonenvironmental significance of Eocene palynomorphs from the Rusayl Shale Formation, Al Khawd, northern Oman. Review of Palaeobotany and Palynology 102, 249-258]. During the upper Rusayl Formation (lithofacies units V through VII) algal mats episodically flooded by marine

  6. Dynamics of Surfactants Spreading on Gel-like Materials: Cracking and Pattern Formation

    CERN Document Server

    Spandagos, Constantine; Matar, Omar

    2010-01-01

    We study the dynamics of surfactants spreading on gels, paying particular attention to the pattern formation accompanying the flow. The latter results from gel-cracking, promoted by Marangoni stresses, and resemble starbursts.

  7. Depositional Environment of the Batuasih Formation on the Basis of Foraminifera Content: A Case Study in Sukabumi Region, West Java Province, Indonesia

    Directory of Open Access Journals (Sweden)

    M. Hendrizan

    2014-06-01

    Full Text Available DOI: 10.17014/ijog.v7i2.139The research was carried out on the sediments of the Batuasih Formation cropping out at Batuasih Village, Cibatu River, Padaarang Sukabumi. Data obtained from field observation, as well as foraminifera and sedimentology analyses conducted in the laboratory, were used to interpret its depositional environment. The investigation was focused on planktonic and benthic foraminiferal assemblages for depositional environment interpretation that might not be used by previous researchers. The Batuasih Formation is composed of black shaly claystone, where the lower part is rich in clay ball, and limestone intercalations in the upper part of the formation. In Cibatu Section, no clay balls is recognized in the lower part, but intercalations of limestone still occur. However, a contrast difference is found in Padaarang section, where green claystone interbeds with fine-grained sandstone. The Batuasih Formation conformably overlies the Walat Formation containing conglomerate. Foraminifera fossil found in the Batuasih Formation consists of bad preserved black benthic and planktonic foraminifera, more abundant towards the lower part of formation. Based on foraminifera assemblage comprising genus Uvigerina, Cibicides, Elphidium, Operculina, Bulimina, Bolivina, Eponides, and Neoconorbina, supported by sedimentology data, the Batuasih Formation was deposited in a shallow to deep marine environtment, during Early Oligocene (P19 time. Upwards to be the Rajamandala Formation, the depositional environment tends to be shallower gradually.

  8. Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone—Hosted Gold Deposit and Discovery of Melt Inclusions

    Institute of Scientific and Technical Information of China (English)

    李兆麟; 翟伟; 等

    2002-01-01

    The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated falut mylonite zone of the Sinian-Silurian metamorphic rock series.In this study there have been discovered melt inclusions,fluid-melt inclusions and organic inclusions in ore-bearing ruartz veins of the ore deposit and mylonite for the first time.The homogenization temperatures of the various types of inclusions are 160℃,180-350℃,530℃and 870℃ for organic inclusions,liquid inclsions two-phase immiscible liquid inclusions and melt inclusion,respectively,Ore fluid is categoriezed as the neutral to basic K+-Ca2+-Mg2+-Na+-SO42--HCO3-Cl- system.The contents of trace gases follow a descending order of H2O>CO2>CH4>(orCO>C2H2>C2H6>O2>N2.The concentrations of K+,Ca2+,SO42-,HCO3-,Cl-,H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in from different levels of the gold deposit.This is significant for deep ore prospecting in the region.Daughter minerals in melt inclusions were analyzed using SEM.Quartz,orthoclase,wollastonite and other silicate minerals were identified.They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins.Sedimentary metamophic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism,which possess melt-soulution characteristics.Ore formation is related to the multi-stage forming process of silicate melt and fluid.

  9. Study on the Physical and Chemical Conditions of Ore Formation of Hetai Ductile Shear Zone-Hosted Gold Deposit and Discovery of Melt Inclusions

    Institute of Scientific and Technical Information of China (English)

    李兆麟; 翟伟; 李文; 石贵勇; 文拥军

    2002-01-01

    The Hetai ductile shear zone-hosted gold deposit occurs in the deep-seated fault mylonite zone of the Sinian-Silurian metamorphic rock series. In this study there have been discovered melt inclusions, fluid-melt inclusions and organic inclusions in ore-bearing quartz veins of the ore deposit and mylonite for the first time. The homogenization temperatures of the various types of inclusions are 160℃, 180 - 350℃, 530℃ and 870℃ for organic inclusions, liquid inclusions, two-phase immiscible liquid inclusions and melt inclusions, respectively. Ore fluid is categorized as the neutral to basic K+ -Ca2+ -Mg2+ -Na+ - SO2- 4-HCO3-Cl- system. The contents of trace gases follow a descending order of H2O>CO2>CH4>(or < ) H2>CO>C2H2>C2I-I6>O2>N2.The concentrations of K , Ca2 + ,SO2-4,HCO3-,Cl- H2O and C2H2 in fluid inclusions are related to the contents of gold and the Au/Ag ratios in ores from different levels of the gold deposit. This is significant for deep ore prospecting in the region. Daughter minerals in melt inclusions were analyzed using SEM. Quartz, orthoclase, wollastonite and other silicate minerals were identified. They were formed in different mineral assemblages.This analysis further proves the existence of melt inclusions in ore veins. Sedimentary metamorphic rocks could form silicate melts during metamorphic anatexis and dynamic metamorphism, which possess melt-solution characteristics. Ore formation is related to the multi-stage forming process of silicate melt and fluid.

  10. Depositional conditions of the coal-bearing Hirka Formation beneath late Miocene explosive volcanic products in NW central Anatolia, Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Sener, M. [Nigde University, Nigde (Turkey). Dept. of Geology

    2007-04-15

    This work focuses on the relationship between the coal deposition and explosive volcanism of the Miocene basin, NW central Anatolia, Turkey. The coal-bearing Hirka Formation was deposited over the Galatian Andesitic Complex and/or massive lagoonal environments during the Miocene. The investigated lignite is a high ash (from 32 to 58%) and sulphur (from 1.43 to 3.03%) lignite which is petrographically characterised by a high humunite content. The mineral matter of the studied lignite samples is made up of mainly clay minerals (illite-smectite and kaolinite), plagioclase and quartz in Bolu coal field, clay minerals (illite-smectite, smectite and illite), quartz, calcite, plagioclase and gypsum in Seben coal field, quartz, K-feldspar, plagioclase and clay minerals (kaolinite and illite) in Kibriscik, and dolomite, quartz, clinoptilolite, opal CT and gypsum in Camhdere coal field. The differences in these four types of lignite with specific mineralogical patterns may be due to the explosive volcanic events and depositional conditions which changed from one coal field to the others. There is a zonation from SW to SE in the studied area for zeolites. Carbonate minerals are commonly calcite in Seben and Kibriscik coal fields. In Bolu, coal samples are devoid of calcite and dolomite. These analyses show that there is an increase in the amount of Mg and a decrease in the amount of Na from the northwestern part to the southern part in the study area.

  11. Facies characteristics of the basal part of the Talchir Formation, Talchir Basin, India – depositional history revisited

    Indian Academy of Sciences (India)

    Prabir Dasgupta; Rishiraj Sahoo

    2007-02-01

    The lowest unit of the Talchir Formation of Talchir Basin, Orissa, was described by pioneer workers as the 'basal oulder bed'. In an attempt to explain the co-existence of gravel and clay, materials of contrasting hydraulic properties, a probable situation resembling the effects of the action of ground-ice enabled boulders to be carried down by sluggish currents resulting in an intermixture of large boulders and fine mud was conceived. Misinterpretation of this conclusion led to a general tendency to describe the 'basal boulder bed' as 'glacial tillite'. However, the unit described as 'basal boulder bed is actually represented by a matrix rich conglomerate with pockets of normally graded silty clay. The present study reveals that the depositional imprints preserved in this part of the sedimentary succession indicate emplacement of successive debris flows generated through remobilization of pre-existing unconsolidated sediments. Small pockets of fine-grained turbidites presumably deposited from the entrained turbidity currents associated with the debris flows suggest the composite character of the debris flow deposit.

  12. A study on the genetic relations between Permian Longtan Formation coal series strata and Carlin-type gold deposits, southwestern Guizhou Province, China

    Institute of Scientific and Technical Information of China (English)

    NIE Aiguo; MEI Shiquan; GUAN Daiyun; WU Pan; ZHANG Zhuru

    2008-01-01

    A large number of the Carlin-type gold deposits occur in the Longtan Formation in southwestern Guizhou Province. The Longtan Formation contains abundant basalt, tuff and siliceous rocks. All rocks of the Longtan Formation are enriched in gold, which were deposited in a limited platform environment in the transition zone from marine to continental. The process of sedimentation was accompanied by the eruption of Emeishan basalt and hydrothermal deposition controlled by co-sedimentary submarine deep faults in the west, which led to the formation of a peculiar gold-bearing formation with coal series strata. This formation controlled the occurrence of the Carlin-type gold deposits in southwestern Guizhou Province. In response to the remobilization of the Emei mantle plume during the Yanshanian period, As, Au and other ore-forming materials were continuously extracted by deeply circulating waters from the Emeishan basalt and coal seams, thereafter forming ore-forming hydrothermal solutions.When these elements were transported in the coal seams, large amounts of As, Au and other elements were enriched in pyrite within the coal seams, thus forming high-As coal and Carlin-type gold deposits in the Longtan Formation coal series strata.

  13. Dynamic behavior of a social model for opinion formation

    Science.gov (United States)

    Bordogna, Clelia M.; Albano, Ezequiel V.

    2007-12-01

    The dynamic behavior of a social group influenced by both a strong leader and the mass media, which is modeled according to the social impact theory, is studied under two situations: (i) The strong leader changes his/her state of opinion periodically while the mass media are not considered. In this case, the leader is capable of driving the group between a dynamically ordered state with a weak leader-group coupling (high-frequency regime) and a dynamically disordered state where the group follows the opinion of the leader (low-frequency regime). (ii) The mass-media change periodically their message and have to compete with a strong leader that keeps his/her state of opinion unchanged. In this case, the mass media require an amplitude threshold in order to overcome the influence of the leader and drive the system into a dynamically disordered state. The dynamic behavior characteristic of the studied social opinion model shares many features of physical systems that are relevant in the fields of statistical mechanics and condensed matter.

  14. Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

    Science.gov (United States)

    Henley, R.W.; Berger, B.R.

    2011-01-01

    Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite-dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500. m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial 'Sulfate' Stage of advanced argillic wallrock alteration ?? alunite commonly with intense silicification followed by a 'Sulfide' Stage - a succession of discrete sulfide-sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 ??C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, 'condensation' of Cu-As-S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 ??C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays

  15. Growth, intermixing, and surface phase formation for zinc tin oxide nanolaminates produced by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hägglund, Carl, E-mail: carl.hagglund@angstrom.uu.se [Department of Chemical Engineering, Stanford University, Stanford, California 94305 and Department of Engineering Sciences, Division of Solid State Electronics, Uppsala University, 75121 Uppsala (Sweden); Grehl, Thomas; Brongersma, Hidde H. [ION-TOF GmbH, Heisenbergstraße 15, 48149 Münster (Germany); Tanskanen, Jukka T.; Mullings, Marja N.; Mackus, Adriaan J. M.; MacIsaac, Callisto; Bent, Stacey Francine, E-mail: sbent@stanford.edu [Department of Chemical Engineering, Stanford University, Stanford, California 94305 (United States); Yee, Ye Sheng [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Clemens, Bruce M. [Department of Material Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-03-15

    A broad and expanding range of materials can be produced by atomic layer deposition at relatively low temperatures, including both oxides and metals. For many applications of interest, however, it is desirable to grow more tailored and complex materials such as semiconductors with a certain doping, mixed oxides, and metallic alloys. How well such mixed materials can be accomplished with atomic layer deposition requires knowledge of the conditions under which the resulting films will be mixed, solid solutions, or laminated. The growth and lamination of zinc oxide and tin oxide is studied here by means of the extremely surface sensitive technique of low energy ion scattering, combined with bulk composition and thickness determination, and x-ray diffraction. At the low temperatures used for deposition (150 °C), there is little evidence for atomic scale mixing even with the smallest possible bilayer period, and instead a morphology with small ZnO inclusions in a SnO{sub x} matrix is deduced. Postannealing of such laminates above 400 °C however produces a stable surface phase with a 30% increased density. From the surface stoichiometry, this is likely the inverted spinel of zinc stannate, Zn{sub 2}SnO{sub 4}. Annealing to 800 °C results in films containing crystalline Zn{sub 2}SnO{sub 4}, or multilayered films of crystalline ZnO, Zn{sub 2}SnO{sub 4}, and SnO{sub 2} phases, depending on the bilayer period.

  16. Spontaneous oscillations and pattern formation during chemical vapor deposition of metastable InN.

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, F.; Munkholm, A.; Wang, R.-V.; Streiffer, S. K.; Thompson, C.; Fuoss, P. H.; Latifi, K.; Elder, K. R.; Stephenson, G. B.; Philips Lumileds Lighting Co.; Northern Illinois Univ.; Oakland Univ.; Ohio Univ.; Intel Corp.

    2008-01-01

    We report observations of self-sustaining spatiotemporal chemical oscillations during metal-organic chemical vapor deposition of InN onto GaN. Under constant supply of vapor precursors trimethylindium and NH{sub 3}, the condensed-phase cycles between crystalline islands of InN and elemental In droplets. Propagating fronts between regions of InN and In occur with linear, circular, and spiral geometries. The results are described by a model in which the nitrogen activity produced by surface-catalyzed NH{sub 3} decomposition varies with the exposed surface areas of GaN, InN, and In.

  17. An Investigation on the Formation of Carbon Nanotubes by Two-Stage Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    M. S. Shamsudin

    2012-01-01

    Full Text Available High density of carbon nanotubes (CNTs has been synthesized from agricultural hydrocarbon: camphor oil using a one-hour synthesis time and a titanium dioxide sol gel catalyst. The pyrolysis temperature is studied in the range of 700–900°C at increments of 50°C. The synthesis process is done using a custom-made two-stage catalytic chemical vapor deposition apparatus. The CNT characteristics are investigated by field emission scanning electron microscopy and micro-Raman spectroscopy. The experimental results showed that structural properties of CNT are highly dependent on pyrolysis temperature changes.

  18. Ice Formation via Deposition Mode Nucleation Onto Dust Particulates: The University of Toronto Continuous Flow Diffusion Chamber

    Science.gov (United States)

    Kanji, Z. A.; Abbatt, J. P.; Cotton, R.; Demott, P.; Jones, H.; Möhler, O.; Stetzer, O.

    2008-12-01

    Laboratory studies are described whereby the heterogeneous ice nucleating ability of various dust samples were studied, for particles suspended in a newly built thermal gradient continuous flow diffusion chamber (TG-CFDC). Ice formation is observed using an optical particle counter (OPC) and the relative humidity (RH) and temperature conditions of the flow system are validated by observing homogenous freezing of H2SO4 aerosols. At the Fourth International Ice Nucleation Workshop (ICIS 07) in Karslruhe, Germany this system was used to investigate ice nucleation primarily in the vapor deposition mode, for Arizona Test Dust (ATD), Israeli Desert Dust (ID), Canary Island Dust (CID), Saharan Dust (SD), Graphite Spark Soot, Snomax® (dead bacteria) and live bacteria. The aerosol size was in the submicron range with an approximate cut off of 700 nm and a mode of 350 nm. Temperatures for nucleation were varied from 265 - 230 K. The dust aerosols were generally found to be more efficient than soot. At warmer temperatures (263 K) the bacteria were found to be active in the deposition mode which was not the case for dusts. Among the various dust types at 248 K, the CID was more efficient than ATD at nucleating ice when efficiency is based on lowest onset RH conditions for ice formation in our chamber. We also present preliminary results for the effect of total surface area versus size of aerosols on ice nucleation using ATD as a surrogate for naturally occurring mineral dust.

  19. A Broad Dynamical Model for Pattern Formation by Lateral Inhibition

    CERN Document Server

    Arcak, Murat

    2012-01-01

    Many patterning events in multi-cellular organisms rely on cell-to-cell contact signaling, such as the Notch pathway in metazoans. A particularly interesting phenomenon in this form of communication is lateral inhibition where a cell that adopts a particular fate inhibits its immediate neighbors from doing the same. Dynamical models are of great interest for understanding the circuit topologies involved in lateral inhibition and for predicting the associated patterns. Several simplified models have been employed for Notch signalling pathways in the literature. The objective of this paper is to present an abstract dynamical model that captures the essential features of lateral inhibition and to demonstrate with dynamical systems techniques that these features indeed lead to patterning.

  20. Dynamics and gravitational wave signature of collapsar formation.

    Science.gov (United States)

    Ott, C D; Reisswig, C; Schnetter, E; O'Connor, E; Sperhake, U; Löffler, F; Diener, P; Abdikamalov, E; Hawke, I; Burrows, A

    2011-04-22

    We perform 3+1 general relativistic simulations of rotating core collapse in the context of the collapsar model for long gamma-ray bursts. We employ a realistic progenitor, rotation based on results of stellar evolution calculations, and a simplified equation of state. Our simulations track self-consistently collapse, bounce, the postbounce phase, black hole formation, and the subsequent early hyperaccretion phase. We extract gravitational waves from the spacetime curvature and identify a unique gravitational wave signature associated with the early phase of collapsar formation.

  1. A Deterministic Model for Analyzing the Dynamics of Ant System Algorithm and Performance Amelioration through a New Pheromone Deposition Approach

    CERN Document Server

    Acharya, Ayan; Konar, Amit; Janarthanan, Ramadoss

    2008-01-01

    Ant Colony Optimization (ACO) is a metaheuristic for solving difficult discrete optimization problems. This paper presents a deterministic model based on differential equation to analyze the dynamics of basic Ant System algorithm. Traditionally, the deposition of pheromone on different parts of the tour of a particular ant is always kept unvarying. Thus the pheromone concentration remains uniform throughout the entire path of an ant. This article introduces an exponentially increasing pheromone deposition approach by artificial ants to improve the performance of basic Ant System algorithm. The idea here is to introduce an additional attracting force to guide the ants towards destination more easily by constructing an artificial potential field identified by increasing pheromone concentration towards the goal. Apart from carrying out analysis of Ant System dynamics with both traditional and the newly proposed deposition rules, the paper presents an exhaustive set of experiments performed to find out suitable p...

  2. The effects of colloidal SiO2 and inhibitor on the solid deposit formation in geothermal water of low hardness

    Directory of Open Access Journals (Sweden)

    Stanković Novica J.

    2011-01-01

    Full Text Available Low solubility of SiO2 and its occurrence in geothermal waters in the form of ionic, colloidal and suspended state are the main cause of the solid deposit occurrence. Certain chemical types of silica, under the influence of Fe2+, Al3+, F−, OH- ions and other micro-constituents, and due to significantly decreased solubility of SiO2, stimulate nucleation, particle growth and solid deposit formation. The aim of this paper is to inhibit the process of nucleation and solid deposit formation by adding originally designed inhibitor in the form of an emulsion, when the total concentration of the present and added colloidal SiO2 is beyond the solubility limit (120 mg/dm3. By turbidimetric, SEM, EDS and XRD analysis, the processes of solid deposit formation were investigated in Vranjska Banja (Serbia spa geothermal water source (water hardness of 4ºdH, and theoretical and practical conclusions were made.

  3. Zintl layer formation during perovskite atomic layer deposition on Ge (001)

    Science.gov (United States)

    Hu, Shen; Lin, Edward L.; Hamze, Ali K.; Posadas, Agham; Wu, HsinWei; Smith, David J.; Demkov, Alexander A.; Ekerdt, John G.

    2017-02-01

    Using in situ X-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and density functional theory, we analyzed the surface core level shifts and surface structure during the initial growth of ABO3 perovskites on Ge (001) by atomic layer deposition, where A = Ba, Sr and B = Ti, Hf, Zr. We find that the initial dosing of the barium- or strontium-bis(triisopropylcyclopentadienyl) precursors on a clean Ge surface produces a surface phase that has the same chemical and structural properties as the 0.5-monolayer Ba Zintl layer formed when depositing Ba by molecular beam epitaxy. Similar binding energy shifts are found for Ba, Sr, and Ge when using either chemical or elemental metal sources. The observed germanium surface core level shifts are consistent with the flattening of the initially tilted Ge surface dimers using both molecular and atomic metal sources. Similar binding energy shifts and changes in dimer tilting with alkaline earth metal adsorption are found with density functional theory calculations. High angle angular dark field scanning transmission microscopy images of BaTiO3, SrZrO3, SrHfO3, and SrHf0.55Ti0.45O3 reveal the location of the Ba (or Sr) atomic columns between the Ge dimers. The results imply that the organic ligands dissociate from the precursor after precursor adsorption on the Ge surface, producing the same Zintl template critical for perovskite growth on Group IV semiconductors during molecular beam epitaxy.

  4. Dynamical Formation of the GW150914 Binary Black Hole

    CERN Document Server

    Rodriguez, Carl L; Chatterjee, Sourav; Kalogera, Vicky; Rasio, Frederic A

    2016-01-01

    We explore the possibility that GW150914, the binary black hole merger recently detected by Advanced LIGO, was formed by gravitational interactions in the core of a dense star cluster. Using models of globular clusters with detailed $N$-body dynamics and stellar evolution, we show that a typical cluster with a mass of $3\\times10^5M_{\\odot}$ to $6\\times10^5M_{\\odot}$ is optimal for forming GW150914-like binary black holes that will merge in the local universe. We identify the most likely dynamical processes for forming GW150914 in such a cluster, and we show that the detection of GW150914 is consistent with the masses and merger rates expected for binary black hole mergers from globular clusters. Our results show that dynamical processes provide a significant and well-understood pathway for forming binary black hole mergers in the local universe. Understanding the contribution of dynamics to the binary black hole merger problem is a critical step in unlocking the full potential of gravitational-wave astronomy.

  5. Rotational Brownian Dynamics simulations of clathrin cage formation

    NARCIS (Netherlands)

    Ilie, I.M.; Otter, den W.K.; Briels, W.J.

    2014-01-01

    The self-assembly of nearly rigid proteins into ordered aggregates is well suited for modeling by the patchy particle approach. Patchy particles are traditionally simulated using Monte Carlo methods, to study the phase diagram, while Brownian Dynamics simulations would reveal insights into the assem

  6. Rotational Brownian Dynamics simulations of clathrin cage formation

    NARCIS (Netherlands)

    Ilie, Ioana Mariuca; den Otter, Wouter K.; Briels, Willem J.

    2014-01-01

    The self-assembly of nearly rigid proteins into ordered aggregates is well suited for modeling by the patchy particle approach. Patchy particles are traditionally simulated using Monte Carlo methods, to study the phase diagram, while Brownian Dynamics simulations would reveal insights into the

  7. Flexible Virtual Structure Consideration in Dynamic Modeling of Mobile Robots Formation

    Science.gov (United States)

    El Kamel, A. Essghaier; Beji, L.; Lerbet, J.; Abichou, A.

    2009-03-01

    In cooperative mobile robotics, we look for formation keeping and maintenance of a geometric configuration during movement. As a solution to these problems, the concept of a virtual structure is considered. Based on this idea, we have developed an efficient flexible virtual structure, describing the dynamic model of n vehicles in formation and where the whole formation is kept dependant. Notes that, for 2D and 3D space navigation, only a rigid virtual structure was proposed in the literature. Further, the problem was limited to a kinematic behavior of the structure. Hence, the flexible virtual structure in dynamic modeling of mobile robots formation presented in this paper, gives more capabilities to the formation to avoid obstacles in hostile environment while keeping formation and avoiding inter-agent collision.

  8. A demographic approach to firm dynamics: formation of new firms and survival of old ones

    NARCIS (Netherlands)

    Nijkamp, P.; Geenhuizen, van M.

    1995-01-01

    This paper introduces a new approach to firm dynamics, named demography of firms. It is the study of demographic events in a population of firms. Thepaper argues that withina demographic approach, attention should be paid to a broad range of firm dynamics, including both new firm formation and survi

  9. Effects of texture on salt precipitation dynamics and deposition patterns in drying porous media

    Science.gov (United States)

    Norouzi Rad, Mansoureh; Shokri, Nima

    2015-04-01

    Understanding the physics of water evaporation from saline porous media is important in many natural and engineering applications such as durability of building materials and preservation of monuments, CO2 sequestration and water quality. Also excess of salt accumulation in soil may result in soil salinization which is a global problem adversely affecting vegetation, plant growth and crop production. Thus it is important to understand the parameters affecting salt transport and precipitation in porous media. We applied X-ray micro-tomography to investigate the dynamics of salt precipitation during evaporation from porous media as influenced by the particle and pore sizes. The packed beds were saturated with NaCl solution of 3 Molal and the time-lapse X-ray imaging was continued for one day. The results show that the presence of preferential evaporation sites (associated with fine pores) on the surface of the sand columns influences significantly the patterns and dynamics of NaCl precipitation (Norouzi Rad et al., 2013; Norouzi Rad and Shokri, 2014). They confirm the formation of an increasingly thick and discrete salt crust with increasing grain size in the sand column due to the presence of fewer fine pores (preferential precipitation sites) at the surface compared to the sand packs with finer grains. Fewer fine pores on the surface also results in shorter stage-1 precipitation for the columns with larger grain sizes. A simple model for the evolution of salt crust thickness based on this principle shows a good agreement with our experiments. Our results provide new insights regarding the physics of salt precipitation and its complex dynamics in porous media during evaporation. References Norouzi Rad, M., Shokri, N., Sahimi, M. (2013), Pore-Scale Dynamics of Salt Precipitation in Drying Porous Media, Phys. Rev. E, 88, 032404. Norouzi Rad, M., Shokri, N. (2014), Effects of grain angularity on NaCl precipitation in porous media during evaporation, Water Resour. Res

  10. Depositional environment and source potential of Jurassic coal-bearing sediments (Gresten Formation, Hoflein gas/condensate field, Austria)

    Energy Technology Data Exchange (ETDEWEB)

    Sachsenhofer, R.F.; Bechtel, A.; Kuffner, T.; Rainer, T.; Gratzer, R.; Sauer, R.; Sperl, H. [Mount University of Leoben, Leoben (Austria)

    2006-05-15

    Coal-bearing Jurassic sediments (Gresten Formation; Lower Quartzarenite Member) are discussed as source rocks for gas and minor oil in the basement of the Alpine-Carpathian frontal zone (e.g. Hoflein gas/condensate field). Core material has therefore been analysed to characterize depositional environment and source potential of the Lower Quartzarenite Member (LQM). Geochemical data from the Hoflein condensate are used to establish a Source-condensate correlation. The LQM was deposited in a flood basin with transitions to a delta-plain environment. Coal originated in frequently flooded mires and evolved within an oxygenated and acidic environment. It is inferred from geochemical data that organic matter from aquatic macrophytes and gymnosperms contributed to coal formation. Wildfires were abundant and oxidation of plant remains occurred frequently. This resulted in the formation of dull coal with very high inertinite contents. Bituminous shales were formed in deeper waters under dysoxic conditions. Apart from abundant algae and micro-organisms, it is concluded that there was an increased contribution of higher land plants relative to macrophytes to the biomass of the shales. Despite high inertinite contents, coal within the LQM has a significant oil potential. Bituminous shales contain a Type III-II kerogen. According to pyrolysis-gas chromatography data, coal and shale generate a high wax paraffinic oil. The organic matter is immature to marginal mature (0.55% Rr). Bituminous shales are considered a potential source for the Hoflein condensate. Coal may be the source for gas and minor oil in the Klement Field, but is not the source for the condensate.

  11. Formation and physical properties of YBCO thick films grown by using the electrophoretic deposition method

    CERN Document Server

    Kim, U J; Kim, Y C; Han, S K; Kang, K Y

    1999-01-01

    Thick films of the YBa sub 2 Cu sub 3 O subgamma sub - subdelta (YBCO) superconductor were prepared by using the electrophoretic deposition technique and a flexible wire as the substrate. The transition temperature of the wires was 91 K, the intragranular magnetic critical current density J sub c sub g sup m sup a sup g was about 10 sup 5 A/cm sup 2 at 77 K in a weak field, and the transport J sub c sup t sup r sup a sup n sup s was about 365 A/cm sup 2 at 77 K. We calculated the intergranular magnetic critical current J sub c sub J sup m sup a sup g and the activation energy from the AC-susceptibility measurements, and their values were about 444 A/cm sup 2 at 77 K and 2.02 eV, respectively.

  12. Dynamics of fingering convection II: The formation of thermohaline staircases

    CERN Document Server

    Stellmach, S; Garaud, P; Brummell, N; Radko, T

    2010-01-01

    Regions of the ocean's thermocline unstable to salt fingering are often observed to host thermohaline staircases, stacks of deep well-mixed convective layers separated by thin stably-stratified interfaces. Decades after their discovery, however, their origin remains controversial. In this paper we use 3D direct numerical simulations to shed light on the problem. We study the evolution of an analogous double-diffusive system, starting from an initial statistically homogeneous fingering state and find that it spontaneously transforms into a layered state. By analysing our results in the light of the mean-field theory developed in Paper I, a clear picture of the sequence of events resulting in the staircase formation emerges. A collective instability of homogeneous fingering convection first excites a field of gravity waves, with a well-defined vertical wavelength. However, the waves saturate early through regular but localized breaking events, and are not directly responsible for the formation of the staircase....

  13. Opinion Formation and the Collective Dynamics of Risk Perception

    CERN Document Server

    Moussaid, Mehdi

    2014-01-01

    The formation of collective opinion is a complex phenomenon that results from the combined effects of mass media exposure and social influence between individuals. The present work introduces a model of opinion formation specifically designed to address risk judgments, such as attitudes towards climate change, terrorist threats, or children vaccination. The model assumes that people collect risk information from the media environment and exchange them locally with other individuals. Even though individuals are initially exposed to the same sample of information, the model predicts the emergence of opinion polarization and clustering. In particular, numerical simulations highlight two crucial factors that determine the collective outcome: the propensity of individuals to search for independent information, and the strength of social influence. This work provides a quantitative framework to anticipate and manage how the public responds to a given risk, and could help understanding the systemic amplification of ...

  14. Dynamic Model Visualizing the Process of Viral Plaque Formation

    Directory of Open Access Journals (Sweden)

    Boriana Marintcheva

    2012-09-01

    Full Text Available In Microbiology and Virology courses, viral plaques are often presented to students as the way one can visualize viruses/bacteriophages. While students generally grasp the idea that counting plaques is essentially the same as counting viruses in their sample (assuming that one virus entering the cell is sufficient for productive infection, the process of plaque formation itself remains largely obscure. Many students fail to appreciate that viral plaques are actually a “laboratory-made” phenomenon allowing us to observe and study the growth of lytic viruses. The latter often presents a challenge for the interpretation of experimental data related to viral growth and drug discovery using plaque reduction assay. The hands-on model described here creates an opportunity for students to experience the process of viral plaque formation while engaging multiple senses and creating a lasting impression.  

  15. Trajectory Dynamics of Gas Molecules and Galaxy Formation

    CERN Document Server

    Llanos, Pedro J; Hintz, Gerald R

    2013-01-01

    The probability distribution of the velocity of gas molecules in a closed container is described by the kinetic theory of gases. When molecules collide or impact the walls of a container, they exchange energy and momentum in accordance with Newton's laws of motion. Between collisions, the trajectory of individual molecules is a straight line, neglecting gravity. During the formation of a galaxy, the stars are constrained to a region of space and exchange energy and momentum in a manner similar to molecules. In this paper, an exact model of an ideal gas is derived and analyzed to determine the probability distribution of the molecular velocities, which are then compared with the probability distribution of velocities associated with stars during galaxy formation.

  16. Departures from Axisymmetric Balance Dynamics during Secondary Eyewall Formation

    Science.gov (United States)

    2014-10-01

    arguments, based mostly on linearized Ekman theory, to propose a feedback mechanism for secondary eye- wall formation that involves a local enhancement of...the radial vorticity gradient, frictional updraft, and con- vection. The hypothesized feedback, based primarily on linear Ekman balance reasoning, has...largely to a vertical column within an annular region about 15 km wide, centered around 40 km and sloping outward. The mean heating rate maximum exhibits a

  17. On the Interface Formation Model for Dynamic Triple Lines

    CERN Document Server

    Bothe, Dieter

    2015-01-01

    This paper revisits the theory of Y. Shikhmurzaev on forming interfaces as a continuum thermodynamical model for dynamic triple lines. We start with the derivation of the balances for mass, momentum, energy and entropy in a three-phase fluid system with full interfacial physics, including a brief review of the relevant transport theorems on interfaces and triple lines. Employing the entropy principle in the form given in [Bothe & Dreyer, Acta Mechanica, doi:10.1007/s00707-014-1275-1] but extended to this more general case, we arrive at the entropy production and perform a linear closure, except for a nonlinear closure for the sorption processes. Specialized to the isothermal case, we obtain a thermodynamically consistent mathematical model for dynamic triple lines and show that the total available energy is a strict Lyapunov function for this system.

  18. Formation and evolution dynamics of bipolarons in conjugated polymers.

    Science.gov (United States)

    Di, B; Meng, Y; Wang, Y D; Liu, X J; An, Z

    2011-02-10

    Combining the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model and the extended Hubbard model (EHM), we analyze the scattering and combination in conjugated polymers of two polarons with the same charges and parallel or antiparallel spins using a nonadiabatic evolution method. Results show that collisions between the two same charge polarons with parallel spin are essentially elastic due to strong Pauli repulsion, whereas the two same charge polarons with antiparallel spins can combine into a singlet bipolaronic state. The dynamics of bipolarons on two coupled polymer chains and at the interface of a polymer/polymer heterojunction are discussed in detail. This knowledge will serve to understand the dynamics of the system when many polarons are created in the system, e.g., by electroluminescence.

  19. NGC6240: Merger-Induced Star Formation & Gas Dynamics

    CERN Document Server

    Engel, H; Genzel, R; Tacconi, L J; Hicks, E K S; Sturm, E; Naab, T; Johansson, P H; Karl, S J; Max, C E; Medling, A; van der Werf, P P

    2010-01-01

    We present spatially resolved integral field spectroscopic K-band data at a resolution of 0.13" (60pc) and interferometric CO(2-1) line observations of the prototypical merging system NGC6240. Despite the clear rotational signature, the stellar kinematics in the two nuclei are dominated by dispersion. We use Jeans modelling to derive the masses and the mass-to-light ratios of the nuclei. Combining the luminosities with the spatially resolved Br-gamma equivalent width shows that only 1/3 of the K-band continuum from the nuclei is associated with the most recent star forming episode; and that less than 30% of the system's bolometric luminosity and only 9% of its stellar mass is due to this starburst. The star formation properties, calculated from typical merger star formation histories, demonstrate the impact of different assumptions about the star formation history. The properties of the nuclei, and the existence of a prominent old stellar population, indicate that the nuclei are remnants of the progenitor gal...

  20. Langevin dynamics for the chiral transition and DCC formation

    Energy Technology Data Exchange (ETDEWEB)

    Kroff, Daniel; Fraga, Eduardo S. [Universidade Federal do Rio de Janeiro (IF/UFRJ), RJ (Brazil). Inst. de Fisica

    2011-07-01

    Full text: The theory of the strong interactions allows for the formation of metastable exotic configurations of the vacuum. Such metastable states can, in principle, be produced in high-energy heavy ion collisions taking place in accelerators like the LHC and in cosmic rays in the atmosphere. In this work, we consider disoriented chiral condensates (DCC), treating them through an effective field theory - the linear-sigma model couple to quarks - and consider possible consequences for ultra-energetic cosmic ray observations performed by the Pierre Auger observatory. After a high-energy collision, the state of the system can be chirally rotated from its true vacuum orientation. Later, this disoriented state (DCC) will relax into the ordinary vacuum configuration, emitting pions. This leads to an asymmetry between charged and neutral pions. This is especially interesting in the context of cosmic rays, where the primary collision in the atmosphere presents favorable conditions for the formation of DCCs. Such exotics might be related to the Centauro and Anti-Centauro events observed by Lattes and collaborators in high-energy cosmic rays experiments. We consider the possibility of DCC formation during a first-order chiral transition, studying the order parameter evolution in a Langevin description. We analyse the DCC influence on the typical time scales of transition and also calculate the pion production rate. (author)

  1. Perspective: network-guided pattern formation of neural dynamics

    OpenAIRE

    Hütt, Marc-Thorsten; Kaiser, Marcus; Claus C Hilgetag

    2014-01-01

    The understanding of neural activity patterns is fundamentally linked to an understanding of how the brain's network architecture shapes dynamical processes. Established approaches rely mostly on deviations of a given network from certain classes of random graphs. Hypotheses about the supposed role of prominent topological features (for instance, the roles of modularity, network motifs or hierarchical network organization) are derived from these deviations. An alternative strategy could be to...

  2. The Dynamics of Bax Channel Formation: Influence of Ionic Strength

    OpenAIRE

    Ganesan, Vidyaramanan; Walsh, Timothy; Chang, Kai-Ti; Colombini, Marco

    2012-01-01

    Mitochondrial outer membrane permeabilization (MOMP) is a complex multistep process. Studies of MOMP in vivo are limited by the stochastic variability of MOMP between cells and rapid completion of IMS protein release within single cells. In vitro models have provided useful insights into MOMP. We have investigated the dynamics of Bax-mediated MOMP in isolated mitochondria using ionic strength as a tool to control the rate of MOMP. We find that Bax can induce both transient permeabilization, d...

  3. Facies analysis and depositional environments of the OligoceneeMiocene Asmari Formation, Zagros Basin, Iran

    Institute of Scientific and Technical Information of China (English)

    Mohammad Sahraeyan; Mohammad Bahrami; Solmaz Arzaghi

    2014-01-01

    The Asmari Formation (a giant hydrocarbon reservoir) is a thick carbonate sequence of the Oligocenee Miocene in the Zagros Basin, southwest of Iran. This formation is exposed at Tang-e-Lendeh in the Fars interior zone with a thickness of 190 m comprising medium and thick to massive bedded carbonates. The age of the Asmari Formation in the study area is the late Oligocene (Chattian)eearly Miocene (Burdigalian). Ten microfacies are defined, characterizing a gradual shallowing upward trend;the related environments are as follows:open marine (MF 8e10), restricted lagoon (MF 6e7), shoal (MF 3e5), lagoon (MF 2), and tidal flat (MF 1). Based on the environmental interpretations, a homoclinal ramp consisting of inner and middle parts prevails. MF 3e7 are characterized by the occurrence of large and small porcelaneous benthic foraminifera representing a shallow-water setting of an inner ramp, influenced by wave and tidal pro-cesses. MF 8e10, with large particles of coral and algae, represent a deeper fair weather wave base of a middle ramp setting.

  4. Applying a new understanding of supergene REE deposit formation to global exploration initiatives for environmentally sustainable resources

    Science.gov (United States)

    Hardy, Liam; Smith, Martin; Hood, Leo; Heller, Shaun; Faltyn, Rowan; Blum, Astrid; Bamberger, Axel

    2017-04-01

    Two new models have recently been proposed for the formation of REE ion-adsorption deposits and it is likely that they are both active in their related study profiles described in the Ambohimirahavavy Complex in Madagascar (Marquis et al, 2016) and the Serra de Monchique (SDM) complex in Portugal (Hardy et al, 2016). These are two separate environments presenting two different soil systems in terms of flora, protolith and structure. In the latosol profiles of SDM the natural sweating cycle of eucalyptus trees is proposed as the main geochemical cycling control for some 40% of Fe and 30% of Y, which have been observed migrating up and down profile seasonally between upper horizons and the rooting depths of these intensively farmed trees. If, through their natural cycle, eucalyptus trees in SDM are capable of concentrating depleted protolithic Y contents of 4-10ppm to some 140-160ppm in their enriched 150-200cm deep E horizons in only the 40 years since they were introduced to the region (Jenkins, 1979), then what potential deposits and concentrations may lay underneath older plantations across Brazil, Chile, China and most importantly, Australia, where these trees naturally cover some 16% of the entire continent. Eucalyptus is mostly farmed as pulp for paper mills and has lost its market value with the demand for paper decreasing, as the demand for REEs increases, ironically driven by the demand for the accessible technology to replace paper (EPA, 2012). Not only might there be great resources below these forests, but the removal of the aggressive intrusive species would be welcomed across Southern Europe and South America where they have limited market value and have destroyed local ecosystems and water supplies (Brito, 1999), where local people are actively seeking an alternative use of their lands. References: Brito, J. G. (1999). Management strategies for conservation of the lizard Lacerta schreiberi in Portugal. Biological conservation, 311-319. EPA. (2012

  5. Microtubule Dynamicity Is More Important than Stability in Memory Formation: an In Vivo Study.

    Science.gov (United States)

    Atarod, Deyhim; Eskandari-Sedighi, Ghazaleh; Pazhoohi, Farid; Karimian, Seyed Morteza; Khajeloo, Mojtaba; Riazi, Gholam Hossein

    2015-06-01

    It has been shown that microtubule (MT) activity and dynamics can have huge impacts on synaptic plasticity and memory formation. This is mainly due to various functions of MTs in neurons; MTs are involved in dendritic spine formation, axonal transportation, neuronal polarity, and receptor trafficking. Recent studies from our group and other labs have suggested the possible role of brain MT dynamicity and activity in memory; however, there is a need for more detailed studies regarding this aspect. In this study, we have tried to evaluate the importance of microtubule dynamicity rather than stability in memory formation in vivo. In order to investigate the role of MT stability in memory formation, we treated mice with paclitaxel-a classic microtubule-stabilizing agent. We then studied the behavior of treated animals using Morris water maze (MWM) test. To measure the effect of injected paclitaxel on MT polymerization kinetics, we conducted polymerization assays on brain extracts of the same paclitaxel-treated animals. Our results show that paclitaxel treatment affects animals' memory in a negative way and treated animals behave poorly in MWM compared to control group. In addition, our kinetics studies show that MT stability is significantly increased in brain extracts from paclitaxel-treated mice, but MT dynamics is reduced. Thus, we suggest that dynamicity is a very important feature of MT protein structures, and regarding memory formation, dynamicity is more important than stability and high activity.

  6. Seeking the mantle contribution for the formation of giant ore deposits: Contemporaneous alkaline lamproites and carbonatites in the Kalmakyr and Muruntau ore districts, Tienshan, Uzbekistan

    Science.gov (United States)

    Seltmann, Reimar; Choulet, Flavien

    2014-05-01

    The decline in discoveries of ore deposits contrasted by the rising demand for e-tech metals requires the global mining industry to continuously seek innovation in exploration. Unravelling the source of metals is among the crucial questions in exploration targeting and geologists have often had to recourse to indirect determinations based on the nature of the magma conveying the metals. The relative contributions of mantle and crust in metallogenic processes and the origin of the magmas from either shallow or deep mantle are not fully understood in the current models of ore genesis. To help to resolve this dilemma, research must establish the link between anorogenic (within-plate) and orogenic processes by using a holistic approach featuring crustal processes, mantle dynamics and crust-mantle interactions that may contribute to the magma fertilization. To achieve this, our study focuses on indicators for the involvement of deep-mantle intrusions (lamproites, lamprophyres, etc.), which have the potential to encapsulate pristine samples of the mantle (xenoliths) during magma ascent [1,2]. The Tienshan belt hosting many giant ore deposits is quite exemplary for understanding mantle-crust interactions and identifying the nature of mantle contribution to ore systems. Sr-Nd-Hf-Pb isotope systematics on granitoids [3] showed a variation of crustal to mixed signatures, indicating involvement of both older crustal sources and mantle-derived material, but the mantle source is not clearly assessed. As objects for our case study in Uzbekistan we choose the Kalmakyr Cu-Au porphyry deposit (~ 315 Ma; Chatkal-Kurama continental arc of Middle Tienshan) and the Muruntau orogenic Au deposit (~290 Ma, Turkestan-Alai / Kyzylkum accretionary complex of South Tienshan) to investigate the impact of associated alkaline magmas on the ore-bearing intrusions and mineralization. Field observations and geochronological data shed light on the spatial and temporal relationships between the

  7. Filamentous Biopolymers on Surfaces: Atomic Force Microscopy Images Compared with Brownian Dynamics Simulation of Filament Deposition

    Science.gov (United States)

    Mücke, Norbert; Klenin, Konstantin; Kirmse, Robert; Bussiek, Malte; Herrmann, Harald; Hafner, Mathias; Langowski, Jörg

    2009-01-01

    Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarly on the interaction strength between the filament and the support: i) For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii) For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a ‘trapping’ mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these ‘ideal’ adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica (‘ideal’ trapping) and on glass (‘ideal’ equilibrated) with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions. PMID:19888472

  8. Filamentous biopolymers on surfaces: atomic force microscopy images compared with Brownian dynamics simulation of filament deposition.

    Directory of Open Access Journals (Sweden)

    Norbert Mücke

    Full Text Available Nanomechanical properties of filamentous biopolymers, such as the persistence length, may be determined from two-dimensional images of molecules immobilized on surfaces. For a single filament in solution, two principal adsorption scenarios are possible. Both scenarios depend primarily on the interaction strength between the filament and the support: i For interactions in the range of the thermal energy, the filament can freely equilibrate on the surface during adsorption; ii For interactions much stronger than the thermal energy, the filament will be captured by the surface without having equilibrated. Such a 'trapping' mechanism leads to more condensed filament images and hence to a smaller value for the apparent persistence length. To understand the capture mechanism in more detail we have performed Brownian dynamics simulations of relatively short filaments by taking the two extreme scenarios into account. We then compared these 'ideal' adsorption scenarios with observed images of immobilized vimentin intermediate filaments on different surfaces. We found a good agreement between the contours of the deposited vimentin filaments on mica ('ideal' trapping and on glass ('ideal' equilibrated with our simulations. Based on these data, we have developed a strategy to reliably extract the persistence length of short worm-like chain fragments or network forming filaments with unknown polymer-surface interactions.

  9. Dynamic Scaling and Island Growth Kinetics in Pulsed Laser Deposition of SrTiO3

    Science.gov (United States)

    Eres, Gyula; Tischler, J. Z.; Rouleau, C. M.; Lee, Ho Nyung; Christen, H. M.; Zschack, P.; Larson, B. C.

    2016-11-01

    We use real-time diffuse surface x-ray diffraction to probe the evolution of island size distributions and its effects on surface smoothing in pulsed laser deposition (PLD) of SrTiO3 . We show that the island size evolution obeys dynamic scaling and two distinct regimes of island growth kinetics. Our data show that PLD film growth can persist without roughening despite thermally driven Ostwald ripening, the main mechanism for surface smoothing, being shut down. The absence of roughening is concomitant with decreasing island density, contradicting the prevailing view that increasing island density is the key to surface smoothing in PLD. We also report a previously unobserved crossover from diffusion-limited to attachment-limited island growth that reveals the influence of nonequilibrium atomic level surface transport processes on the growth modes in PLD. We show by direct measurements that attachment-limited island growth is the dominant process in PLD that creates step flowlike behavior or quasistep flow as PLD "self-organizes" local step flow on a length scale consistent with the substrate temperature and PLD parameters.

  10. Dynamics of formation of the Exclusion Zone near hydrophilic surfaces

    Science.gov (United States)

    De Ninno, Antonella

    2017-01-01

    EZ water is unable to host solutes, what provides the root of the name Exclusion Zone, and its formation law points towards a diffusive process. These peculiarities have attracted the interest of scientists because it challenges all the theories which have tried to describe the structure of liquid water. The mixture of H-bond stable and H-bond distorted structures envisaged by very recent experimental findings, cannot account for the long-lived hexagonal configuration observed near the Nafion surface. A theoretical account for the phenomenology of H-bond is provided which looks able to explain many among the most striking feature of this water.

  11. Molecular dynamics study of growth and interface structure during aluminum deposition on Ni(1 0 0) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Hassani, A., E-mail: a.hassani.uh1@gmail.com [Univ Hassan 1" e" r, Laboratory of Radiation and Matter, Faculty of Science and Technology, 26000 Settat (Morocco); Univ Hassan 1" e" r, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco); Makan, A. [Laboratory of Water and Environment, Faculty of Science, Univ. Chouaib Doukkali, 24000 El Jadida (Morocco); Sbiaai, K., E-mail: ksbiaai@gmail.com [Univ Hassan 1" e" r, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco); Tabyaoui, A. [Univ Hassan 1" e" r, Laboratory of Radiation and Matter, Faculty of Science and Technology, 26000 Settat (Morocco); Hasnaoui, A. [Univ Hassan 1" e" r, Laboratory LS3M, Faculté Polydisciplinaire of Khouribga, 26000 Settat (Morocco)

    2015-09-15

    Highlights: • Aluminum thin film growth on Ni(1 0 0) substrate was investigated. • Molecular dynamics simulation based on EAM interaction potential was considered. • Hexagonal and fourfold structures coexisted in the first layer. • Interface mismatch was revealed by wavy effect occurring in both lateral directions. • Film growth followed a layer-by-layer mode only in the first three deposited layers. - Abstract: We investigate aluminum thin film growth on Ni(1 0 0) substrate by means of molecular dynamics simulation. Embedded Atom Method interaction potential is considered. The simulation is performed at 300 K using an incident energy of 1 eV. The substrate-grown film interface shows the coexistence of hexagonal and fourfold structures in the first layer during the initial stage of deposition. As the deposition proceeds, the hexagonal geometry transforms to fourfold one which becomes dominant toward the end of deposition. The coverage of this layer exceeded 100%. Moreover, the deposited Al atoms with fourfold geometry adopt the lattice parameter of Ni as the thickness of deposited film increases. The interface mismatch investigation revealed that the roughness is dictated by how the Al(1 1 1) fits to the Ni(1 0 0) substrate, which may be reflected by a wavy effect occurring in both lateral directions. Furthermore, the film grows by a layer-by-layer mode with a coverage rate greater than 66.7% in the first three layers, while it follows an island mode with a coverage rate lower than the previous value (66.7%) beyond the third layer. Overall, a detailed analysis of each layer growth has established a relationship between the number of deposited atoms and the coverage rate of each layer.

  12. Depositional Settings of the basal López de Bertodano Formation, Maastrichtian, Antarctica

    Directory of Open Access Journals (Sweden)

    E.B. Olivero

    2007-12-01

    Full Text Available In Snow Hill and Seymour islands the lower Maastrichtian, basal part of the L ópez de Bertodano Formation, rests on a high relief, erosive surface elaborated in the underlying Snow Hill Island Formation. Mudstone-dominated beds with inclined heterolithic stratification dominate the basal strata of the López de Bertodano Formation. They consist of rhythmical alternations of friable sandy- and clayeymudstone couplets, with ripple cross lamination, mud drapes, and flaser bedding. They are characterized by a marked lenticular geometry, reflecting the filling of tide-influenced channels of various scales and paleogeographic positions within a tide-dominated embayment or estuary. Major, sand-rich channel fills, up to 50-m thick, bounded by erosive surfaces probably represent inlets, located on a more central position in the estuary. Minor channel fills, 1- to 3-m thick, associated with offlapping packages with inclined heterolithic stratification probably represent the lateral accretion of point bars adjacent to migrating tidal channels in the upper estuary. Both types of channel fills bear relatively abundant marine fauna, are intensively bioturbated, and are interpreted as a network of subtidal channels. In southwestern Snow Hill Island, the minor offlapping packages have scarce marine fossils and bear aligned depressions interpreted as poor preserved dinosaur footprints. They represent the lateral accretion of point bars adjacent to intertidal creeks, probably located on the fringes of a mud-dominated estuary or embayment. The basal unconformity was produced by subaerial erosion; hence the inferred estuarine settings are consistent with the beginning of a new transgressive sedimentary cycle.

  13. Adaptive RBFNN Formation Control of Multi-mobile Robots with Actuator Dynamics

    Directory of Open Access Journals (Sweden)

    Li Yan-dong

    2013-04-01

    Full Text Available We study the problem of formation control and trajectory tracking for multiple nonholonomic mobile robots with actuator and formation dynamics. An adaptive neural-network (NN control strategy that integrated kinematic controller with input voltages controller of actuator was proposed. A control law was designed by backstepping technique based on separation-bearing formation control structure of leader-follower. The radial basis function neural network (RBFNN was adopted to achieve on-line estimation for the dynamics nonlinear uncertain part for follower and leader robots. The adaptive robust controller was adopted to compensate modeling errors of NN. This strategy not only overcomed all kinds of uncertainties of mobile robots, but also ensured the desired trajectory tracking of robot formation in the case of maintaining formation. The stability and convergence of the control system were proved by using the Lyapunov theory. The simulation results showed the effectiveness of this proposed method.

  14. Monitoring structural dynamics of in situ spray-deposited zinc oxide films for application in dye-sensitized solar cells.

    Science.gov (United States)

    Sarkar, Kuhu; Braden, Erik V; Pogorzalek, Stefan; Yu, Shun; Roth, Stephan V; Müller-Buschbaum, Peter

    2014-08-01

    The spray-deposition technique is an effective and scalable method to deposit zinc oxide nanostructures, which are used as active layers for dye-sensitized solar cells (DSSCs) in the present study. The dynamics of structural evolution are studied with grazing incidence small-angle X-ray scattering during in situ spraying. Nanostructured films obtained through multiple spray shots provide suitable structural length scales, morphologies, and film thicknesses; this leads to reasonable performance in a DSSC with the highest short-circuit current density reported so far.

  15. Dynamics of polymer film formation during spin coating

    Energy Technology Data Exchange (ETDEWEB)

    Mouhamad, Y.; Clarke, N.; Jones, R. A. L.; Geoghegan, M., E-mail: geoghegan@sheffield.ac.uk [Department of Physics and Astronomy, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Mokarian-Tabari, P. [Materials Research Group, Department of Chemistry and the Tyndall National Institute, University College Cork, Cork (Ireland)

    2014-09-28

    Standard models explaining the spin coating of polymer solutions generally fail to describe the early stages of film formation, when hydrodynamic forces control the solution behavior. Using in situ light scattering alongside theoretical and semi-empirical models, it is shown that inertial forces (which initially cause a vertical gradient in the radial solvent velocity within the film) play a significant role in the rate of thinning of the solution. The development of thickness as a function of time of a solute-free liquid (toluene) and a blend of polystyrene and poly(methyl methacrylate) cast from toluene were fitted to different models as a function of toluene partial pressure. In the case of the formation of the polymer blend film, a concentration-dependent (Huggins) viscosity formula was used to account for changes in viscosity during spin coating. A semi-empirical model is introduced, which permits calculation of the solvent evaporation rate and the temporal evolution of the solute volume fraction and solution viscosity.

  16. Phase separation dynamics during Myxococcus xanthus fruiting body formation

    Science.gov (United States)

    Liu, Guannan; Bahar, Fatmagul; Patch, Adam; Thutupalli, Shashi; Yllanes, David; Marchetti, M. Cristina; Welch, Roy; Shaevitz, Joshua

    Many living systems take advantage of collective behavior for group survival. We use the soil-dwelling bacterium Myxococcus xanthus as a model to study out-of-equilibrium phase separation during fruiting body formation. M. xanthus cells have the ability to glide on solid surfaces and reverse their direction periodically. When starved, M. xanthus cells aggregate together and form structures called fruiting bodies, inside of which cells sporulate to survive stressful conditions. We show that at high cell density the formation of fruiting bodies is a phase separation process. From experimental data that combines single-cell tracking, population-scale imaging, mutants, and drug applications, we construct the phase diagram of M. xanthus in the space of Péclet number and cell density. When wild type cells are starved, we find that they actively increase their Péclet number by modulating gliding speed and reversal frequency which induces a phase separation from a gas-like state to an aggregated fruiting body state.

  17. The radiocesium dynamics in the Fukushima forests at the late stage after deposition

    Science.gov (United States)

    Yoschenko, Vasyl; Takase, Tsugiko; Nanba, Kenji; Konoplev, Alexei; Onda, Yuichi

    2017-04-01

    Forests cover about 2/3 of the territory of Areas 2 and 3 in the Fukushima prefecture. This territory was heavily contaminated with radiocesium released from the Fukushima Dai-Ichi Nuclear Power Plant in March 2011. The extensive decontamination measures aimed to prepare the return of population have been scheduled and are being implemented at the agricultural and residential lands at this territory. However, these measures will be not applied in the large scale in the Fukushima forests. The current radiocesium levels in wood at this territory exceed the Japanese standards for wood; thus, after return of population, the Fukushima forests may remain excluded from the economical use. Understanding of the further dynamics of radiocesium in the forest ecosystems is necessary for elaboration of the strategy concerning the radioactive contaminated Fukushima forests. In March 2011 radiocesium was intercepted by the tree canopies and then, at the early stage after the accident, was effectively transported to the soil surface with precipitation and litterfall, and partly translocated to wood forming the current levels. The general trend was the decrease of the radiocesium inventory in the aboveground forest biomass. After redistribution in the root-inhabited soil layer radiocesium became available for uptake into the trees through the roots. From the Chernobyl experience, the further levels of radiocesium in the forest ecosystem compartments at the late stage may increase or decrease depending on the intensities of the root uptake and removal fluxes. In the Fukushima forests, the stage of the root uptake has begun recently, and the parameters of the root uptake have not been studied well for the varieties of species, forest types and soil conditions. Our study is aimed to monitoring and modelling of the radiocesium redistribution in the Fukushima forests after the removal of its initial deposition from the tree canopies. The study has been performed since May 2014 at

  18. CONSENSUS FORMATION OF TWO-LEVEL OPINION DYNAMICS

    Institute of Scientific and Technical Information of China (English)

    Yilun SHANG

    2014-01-01

    Opinion dynamics have received significant attention in recent years. This pa-per proposes a bounded confidence opinion model for a group of agents with two different confidence levels. Each agent in the population is endowed with a confidence interval around her opinion with radius αd or (1-α)d, where α ∈ (0, 1/2] represents the differentiation of confidence levels. We analytically derived the critical confidence bound dc =1/(4α) for the two-level opinion dynamics on Z. A single opinion cluster is formed with probability 1 above this critical value regardless of the ratio p of agents with high/low confidence. Extensive numerical simulations are performed to illustrate our theoretical results. Noticed is a clear impact of p on the collective behavior: more agents with high confidence lead to harder agreement. It is also experimentally revealed that the sharpness of the threshold dc increases with αbut does not depend on p.

  19. Depositional Environment of Fine-Grained Sedimentary Rocks of the Sinamar Formation, Muara Bungo, Jambi

    Directory of Open Access Journals (Sweden)

    M. Heri Hermiyanto Zajuli

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i1.153The research area is situated in the northwestern side of South Sumatra Basin, which is a part of Muara Bungo Regency, Jambi Province. The Oligocene Sinamar Formation consists of shale, claystone, mudstone, sandstone, conglomeratic sandstone, and coal-seam intercalations. This research was focused on fine sedimentary rock of Sinamar Formation, such as shale, claystone, and mudstone. Primary data were collected from SNM boreholes which have depths varying from 75 m up to 200 m, and outcrops that were analyzed by organic petrographic method, gas chromatography-mass spectrometry (GC-MS of normal alkanes including isoprenoids, and sterane. The dominant maceral group is exinite, composed of alginite (3.4 - 18%, and resinite (1.6 - 5.6%, while vitrinite maceral consists of tellocolinite 0.4 - 0.6%, desmocollinite 0.4%, and vitrodetrinite 8.4 - 16.6%. Organic petrography and biomarker analyses show that organic materials of shales were derived from high plants and algae especially Botrycoccus species. Botrycoccus and fresh water fish fossil, found in the shale indicate a lacustrine environment.

  20. Depositional conditions of the coal-bearing Hirka Formation beneath Late Miocene explosive volcanic products in NW central Anatolia, Turkey

    Indian Academy of Sciences (India)

    Mehmet Şener

    2007-04-01

    This work focuses on the relationship between the coal deposition and explosive volcanism of the Miocene basin, NW central Anatolia, Turkey. The coal-bearing Hirka Formation was deposited over the Galatian Andesitic Complex and/or massive lagoonal environments during the Miocene. The investigated lignite is a high ash (from 32 to 58%) and sulphur (from 1.43 to 3.03%) lignite which is petrographically characterised by a high humunite content. The mineral matter of the studied lignite samples is made up of mainly clay minerals (illite–smectite and kaolinite), plagioclase and quartz in Bolu coal field, clay minerals (illite–smectite, smectite and illite), quartz, calcite, plagioclase and gypsum in Seben coal field, quartz, K-feldspar, plagioclase and clay minerals (kaolinite and illite) in Kıbrıscık, and dolomite, quartz, clinoptilolite, opal CT and gypsum in C¸ amlıdere coal field. The differences in these four types of lignite with specific mineralogical patterns may be due to the explosive volcanic events and depositional conditions which changed from one coal field to the others. There is a zonation from SW to SE in the studied area for zeolites such as Opal CT+smectite-clinoptilolite-analcime-K-feldspar. Carbonate minerals are commonly calcite in Seben and Kıbrıscık coal fields. In Bolu, coal samples are devoid of calcite and dolomite. These analyses show that there is an increase in the amount of Mg and a decrease in the amount of Na from the northwestern part to the southern part in the study area.

  1. Centralized Dynamics and Control of Novel Orbiting Formations of Tethered Spacecraft

    Science.gov (United States)

    Quadrelli, Marco B.; Hadaegh, Fred Y.

    acting as leader of the tethered formation. An application of this problem arises when a distributed sensor array formed by a chain of tethered data-gathering vehicles is being commanded to reconfigure from a remote location by the formation leader. Another application is in radar mapping where multiple free-flying vehicles synthesize multiple apertures with the main tethered vehicle for increased coverage. In this way, a centralized control architecture distributes the information flow among the members of the sensor array. Defining an orbiting formation as an ensemble of orbiting spacecraft performing a cooperative task, we point out that, until now, only spacecraft modeled as rigid bodies have been analyzed in the literature of orbiting formations and constellations. After the formation is in place, one may identify what is known as the virtual truss, i.e. the connection between the elements of the formation, which provides structural rigidity on account of the information flow between them. Our problem is different than conventional formation dynamics problems in that the presence of a tethered spacecraft within the formation demands an investigation of the dynamics coupling between spacecraft caused by tether viscoelasticity. The dynamics model takes into account the orbital and spacecraft dynamics of each vehicle. The control architecture features a separated spacecraft, which has visibility to the entire group of tethered vehicles. This vehicle is the leader of the formation, and ensures that the spacecraft on the tether remain connected and move according to a pre-specified program. The control system design consists of a proportional-derivative feedback plus acceleration feedforward. This ensures that modeling errors are compensated appropriately, and that the commanded slew is tracked accurately. The leader is also where the centralized estimator is located. This estimator continuously updates the state of the formation and estimates inter

  2. Characteristic Features of the Formation of a Combined Magnetron-Laser Plasma in the Processes of Deposition of Film Coatings

    Science.gov (United States)

    Burmakov, A. P.; Kuleshov, V. N.; Prokopchik, K. Yu.

    2016-09-01

    A block diagram of a facility for combined magnetron-laser deposition of coatings and of the systems of controlling and managing this process is considered. The results of analysis of the influence of the gas medium and of laser radiation parameters on the emission-optical properties of laser plasma are considered. The influence of the laser plasma on the electric characteristics of a magnetron discharge is analyzed. The formation of the laser plasma-initiated pulse arc discharge has been established and the influence of the laser radiation parameters on the electric characteristics of this discharge has been determined. The emission optical spectra of the magnetron discharge plasma and of erosion laser plasma are compared separately and in combination.

  3. Formation of Hierarchical CuO Nanostructures on Copper Foil by Chemical Bath Deposition for Applications in Superhydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Felizco Jenichi Clairvaux

    2016-01-01

    Full Text Available Hierarchical CuO nanostructures (urchin-like and grassy island structure were successfully synthesized by a simple chemical bath deposition method at low temperature of 70°C in a short reaction time of 1h. XRD analysis revealed the presence of pure crystalline monoclinic CuO. Morphological analysis revealed the formation of spherical structures composed of numerous hair-like structures. The pH of the solution was also investigated to have a great effect on the morphology of the CuO nanostructures. At lower pH, the structures tend to form urchin-like structures; while at higher pH, the structures tend to form grass-like islands. A growth mechanism was also proposed in this paper. Lastly, wettability test proved the stable superhydrophobic property of the CuO nanostructured thin film surface.

  4. Exploring Pore Formation of Atomic Layer Deposited Overlayers by In Situ Small- and Wide-Angle X-ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tao; Karwal, Saurabh; Aoun, Bachir; Zhao, Haiyan; Ren, Yang; Canlas, Christian; Elam, Jeffrey W.; Winans, Randall E.

    2016-10-11

    In this work, we explore the pore structure of overcoated materials by in situ synchrotron small- and wide-angle X-ray scattering (SAXS)/(WAXS). Thin films of aluminum oxide (Al2O3) and titanium dioxide (TiO2) with thicknesses of 4.9 and 2.5 nm, respectively, are prepared by atomic layer deposition (ALD) on non-porous nanoparticles. In situ X-ray measurements reveal that porosity is induced in the ALD films by annealing the samples at high temperature. Moreover, this pore formation can be attributed to densification resulting from an amorphous to crystalline phase transition of the ALD films as confirmed by high resolution X-ray diffraction (XRD) and pair distribution function (PDF). Simultaneous SAXS/WAXS results not only show that the porosity is formed by this phase transition but also that the pore size increases with temperature.

  5. Distributed Consensus-Based Robust Adaptive Formation Control for Nonholonomic Mobile Robots with Partial Known Dynamics

    Directory of Open Access Journals (Sweden)

    Zhaoxia Peng

    2014-01-01

    Full Text Available This paper investigates the distributed consensus-based robust adaptive formation control for nonholonomic mobile robots with partially known dynamics. Firstly, multirobot formation control problem has been converted into a state consensus problem. Secondly, the practical control strategies, which incorporate the distributed kinematic controllers and the robust adaptive torque controllers, are designed for solving the formation control problem. Thirdly, the specified reference trajectory for the geometric centroid of the formation is assumed as the trajectory of a virtual leader, whose information is available to only a subset of the followers. Finally, numerical results are provided to illustrate the effectiveness of the proposed control approaches.

  6. Facies analysis and paleoenvironmental interpretation of Piacenzian carbonate deposits from the Guitar Formation of Car Nicobar Island, India

    Directory of Open Access Journals (Sweden)

    Amit K. Ghosh

    2013-11-01

    Full Text Available Facies characterization of Piacenzian (late Pliocene carbonate sediments of the Guitar Formation in Car Nicobar Island, India and the subsequent integration of paleoecological data have been applied to interpret the paleoenvironment of the coralline algal-reef deposits. Thin-section analysis reveals that Amphiroa, Corallina and Jania are the dominant geniculate corallines, while Lithothamnion, Mesophyllum, Phymatolithon, Lithophyllum, Spongites and Lithoporella are the major non-geniculate corallines contributing to the sedimentary facies. Numerous small and larger benthic foraminifera also dominate the biogenic assemblages. Corals, barnacle shells, echinoid spines, fragments of bryozoans, mollusks and ostracodes are the subordinate constituents. Grainstones dominate the studied facies while packstones and boundstones (with wackestone elements are the sub-lithofacies showing a fair representation. Six carbonate facies presenting a complete reef complex have been distinguished that were deposited in shallow intertidal, back-reef shelf/lagoon, reef and deeper fore-reef shelf settings. Evidences of coralline algal and benthic foraminiferal assemblages, taphonomic signatures of abrasion and fragmentation, grain size, angularity and encrustation indicate a shallow to relatively deeper bathymetric horizon of approximately 10–60 m that corresponds to a regime of high to moderate hydrodynamic conditions.

  7. Iliac artery mural thrombus formation. Effect of antiplatelet therapy on 111In-platelet deposition in baboons

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, S.R.; Paxton, L.D.; Harker, L.A.

    1986-09-01

    To measure the rate, extent, and time course of arterial mural thrombus formation in vivo and to assess the effects of antiplatelet therapy in that setting, we have studied autologous /sup 111/In-platelet deposition induced by experimental iliac artery aneurysms in baboons. Scintillation camera imaging analyses were performed at 1, 24, 48, and 72 hours after implantation of the device. Correction for tissue attenuation was determined by using a small, comparably located /sup 111/In source implanted at the time of surgery. In five animals, /sup 111/In-platelet activity accumulated progressively after device implantation, reaching a maximum after the third day. Repeat image analysis carried out 2 weeks after the surgical procedure also showed progressive accumulation of /sup 111/In-platelets over 3 days but at markedly reduced amounts as compared with the initial study. In five additional animals, treatment with a combination of aspirin and dipyridamole begun 1 hour after surgical implantation reduced /sup 111/In-platelet deposition to negligible levels by the third day. Although platelet survival time was shortened and platelet turnover was reciprocally increased in all operated animals, platelet survival and turnover were not affected by antiplatelet therapy. We conclude that, in contrast to platelet survival and turnover measurements, /sup 111/In-platelet imaging is a reliable and sensitive method for localizing and quantifying focal arterial thrombi and for assessing the effects of antiplatelet therapy.

  8. Dynamics of cluster formation in driven magnetic colloids dispersed on a monolayer.

    Science.gov (United States)

    Jäger, Sebastian; Stark, Holger; Klapp, Sabine H L

    2013-05-15

    We report computer simulation results on the cluster formation of dipolar colloidal particles driven by a rotating external field in a quasi-two-dimensional setup. We focus on the interplay between permanent dipolar and hydrodynamic interactions and its influence on the dynamic behavior of the particles. This includes their individual as well as their collective motion. To investigate these characteristics, we employ Brownian dynamics simulations of a finite system with and without hydrodynamic interactions. Our results indicate that hydrodynamic interactions have a profound impact on the dynamic behavior of the clusters and the dynamics of the clustering process.

  9. A generic model of pattern formation in Mississippi Valley-Type deposits based on analytical findings

    Science.gov (United States)

    Kelka, Ulrich; Veveakis, Manolis; Beaudoin, Nicolas; Poulet, Thomas; Koehn, Daniel; Regenauer-Lieb, Klaus; Chung, Peter; Berndt, Jasper

    2016-04-01

    Rhythmically banded dolomites (zebra dolomite) are found worldwide, and are frequently associated with mineralization of the Mississippi Valley-Type (MVT). These rocks consist of dark fine grained and impurity-rich layers alternating with light coarse grained and virtually impurity-free layers. The texture of the light layers is similar to the one of tectonic syntaxial veins where crystals grow towards a median line. We present petrographic and chemical analysis of zebra dolomite samples from the San Vicente mine, Central Peru. The applied methods are petrographic microscopy, SEM, EBSD, EMP and LA-ICP-MS. The findings influence the development of a generic model of pattern formation. We found the density and the distribution of second-phase material to be one striking feature. The impurities are accumulated in the dark layers, which show an even higher density of second-phase material than the surrounding impurity-rich dolomite. With CL, it was possible to detect a luminescent structure in the center of the light bands which seems to be present independent of the thickness and spacing of the respective layers. This structure was analysed in more detail with EMP. We further found that the dolomite crystals in the dark and light layers are chemically similar but show a variation in some trace elements. Based on the analytical findings, we put forward a mathematical model of zebra dolomite formation based on Cnoidal waves. We believe that the light coarse grained layers represent hydromechanical instabilities arising during the diagenetic compaction of a fluid saturated, impurity-rich dolomite. Our approach is based on the extension of the classical compaction bands theory to a viscose, non-linear rheology. In the model, the spacing between two light coarse grained layers is linked to the compaction length during the pattern formation. With the formulation of a 1D steady-state solution we can relate the genesis of the structure to physical parameter, such as

  10. Social Influence and the Collective Dynamics of Opinion Formation

    CERN Document Server

    Moussaid, Mehdi; Analytis, Pantelis P; Neth, Hansjoerg

    2013-01-01

    Social influence is the process by which individuals adapt their opinion, revise their beliefs, or change their behavior as a result of social interactions with other people. In our strongly interconnected society, social influence plays a prominent role in many self-organized phenomena such as herding in cultural markets, the spread of ideas and innovations, and the amplification of fears during epidemics. Yet, the mechanisms of opinion formation remain poorly understood, and existing physics-based models lack systematic empirical validation. Here, we report two controlled experiments showing how participants answering factual questions revise their initial judgments after being exposed to the opinion and confidence level of others. Based on the observation of 59 experimental subjects exposed to peer-opinion for 15 different items, we draw an influence map that describes the strength of peer influence during interactions. A simple process model derived from our observations demonstrates how opinions in a gro...

  11. Vesicles and vesicle gels - structure and dynamics of formation

    CERN Document Server

    Gradzielski, M

    2003-01-01

    Vesicles constitute an interesting morphology formed by self-aggregating amphiphilic molecules. They exhibit a rich structural variety and are of interest both from a fundamental point of view (for studying closed bilayer systems) and from a practical point of view (whenever one is interested in the encapsulation of active molecules). In many circumstances vesicular structures have to be formed by external forces, but of great interest are amphiphilic systems, where they form spontaneously. Here the question arises of whether this means that they are also thermodynamically stable structures, which at least in some systems appears to be the case. If such vesicles are well defined in size, it is possible to pack them densely and thereby form vesicle gels that possess highly elastic properties even for relatively low volume fractions of amphiphile. Conditions for the formation and the microstructure of such vesicle gels have been studied in some detail for the case of unilamellar vesicles. Another important and ...

  12. Dynamic approaches of mixed species biofilm formation using modern technologies.

    Science.gov (United States)

    Doiron, Kim; Linossier, Isabelle; Fay, Fabienne; Yong, Julius; Abd Wahid, Effendy; Hadjiev, Dimitre; Bourgougnon, Nathalie

    2012-07-01

    Bacteria and diatoms exist in sessile communities and develop as biofilm on all surfaces in aqueous environments. The interaction between these microorganisms in biofilm was investigated with a bacterial genus Pseudoalteromonas sp. (strain 3J6) and two benthic diatoms Amphora coffeaeformis and Cylindrotheca closterium. Each biofilm was grown for 22 days. Images from the confocal microscopy show a difference of adhesion between Pseudoalteromonas 3J6 and diatoms. Indeed, a stronger adhesion is found with C. closterium suggesting cohabitation between Pseudoalteromonas 3J6 and C. closterium compared at an adaptation for bacteria and A. coffeaeformis. The cellular attachment and the growth evolution in biofilm formation depend on each species of diatoms in the biofilm. Behaviour of microalgae in presence of bacteria demonstrates the complexity of the marine biofilm.

  13. Analysis of CaCO3 deposit formation and degradation during the molt cycle of the terrestrial isopod Porcellio scaber (Crustacea, Isopoda).

    Science.gov (United States)

    Fabritius, Helge; Ziegler, Andreas

    2003-05-01

    Terrestrial isopods store cuticular calcium in large sternal deposits composed of an amorphous CaCO(3) compound. A large part of the deposits consists of numerous small spherules that increase the exposed surface to facilitate resorption of CaCO(3) during cuticle mineralization. It is not known how these spherules are formed and how they are dissolved. This paper presents for the first time an analysis of ultrastructural changes occurring in the sternal CaCO(3) deposits of a terrestrial isopod during their formation and degradation. Our results indicate that formation of the spherules takes place in a specialized aggregation zone, in which 10- to 30-nm-thick granules form agglomerations that then increase in size to form spherules that reveal a concentric growth pattern. Degradation of the deposits occurs in a manner that exposes a maximum of surface area on all levels of their structural organization.

  14. Geology and formation of titaniferous placer deposits in Upper Jogaz Valley area, Fanuj, Sistan and Baluchestan province, Iran

    Directory of Open Access Journals (Sweden)

    Seyed Javad Moghaddasi

    2015-10-01

    Full Text Available Introduction The Fanuj titaniferous placer deposits are located 35 km northwest of the Fanuj, Sistan and Baluchestan province (1 . The studied area comprises a (2 small part of the late Cretaceous Fanuj-Maskutan (Rameshk ophiolite complex (Arshadi and Mahdavi, 1987. Reconnaissance and comprehensive exploration programs in the Fanuj district (East of the 1:100000 Fanuj quadrangle map,Yazdi, 2010 revealed that the Upper Jogaz Valley area has the highest concentration of titaniferous placer deposits. In this study, geology and formation of the titaniferous placer deposits in Upper Jogaz Valley area are discussed. Materials and Methods (3 Forty samples were collected from surface and drainage sediments to evaluate the potential for titaniferous placers. Mineralogical studies indicated the high Ti (ilmenite bearing areas, which led to detailed exploration by 29 shallow drill holes and 9 trenches. A total of 61 sub-surface samples were collected for heavy mineral studies and ore grade determination. The exploration studies suggest that the the Upper Jogaz Valley area in the Fanuj district has a high potential for titaniferous placer deposits. Extensive exposures of black sands in the sreambeds of this area suggested detailed sampling, so that 12 holes were drilled (2-3 m depthfrom which 26 samples were collected, and five trenches were excavated to 2-4 m depth (4. The distribution of drill holes and trenches were plotted with “Logplot” software for further interpretation. Twenty-two samples from these drill holes were analyzed for TiO2. Results The reconnaissance and comprehensive exploration in Fanuj district shows that the Upper Jogaz Valley area has the highest concentration of titaniferous placer deposits. The general geology of the region and petrology and mineralogy of collected samples suggest that the source rock of the Upper Jogaz Valley titaniferous placers is the hornblende- and olivine-gabbro unit of the Fanuj-Ramesh ophiolites. The Ti

  15. Formation of multilayered structures in the layer by layer deposition of colloid particles.

    Science.gov (United States)

    Adamczyk, Zbigniew; Weroński, Paweł; Barbasz, Jakub

    2008-01-01

    Theoretical calculations of particle film formation in the layer by layer (LbL) self-assembling processes have been performed according to the generalized random sequential adsorption (RSA) scheme. The first (precursor) layer was generated using the standard RSA scheme pertinent to homogeneous surface. Formation of the consecutive layers (up to twenty) was simulated for two kinds of particles of equal size. The interaction of two particles of different kind resulted in irreversible and localized adsorption upon contact, whereas particles of the same kind were assumed to interact via the hard potential (no adsorption possible). Using this algorithm particle coverage (2D density) and volume fraction (3D density) were calculated as well as the film thickness as a function of the number of layers. Additionally, the structure of the film was quantitatively characterized in terms of the 2D and 3D pair correlation functions. The simulations revealed that particle concentration distribution in the film was more uniform for low precursor layer density than for higher density, where well-defined layers of closely packed particles appeared. It was also predicted theoretically that the averaged value of particle volume fraction in the uniform film region was rho(LbL)=0.42, which is very close to the maximum packing density equal to 0.382 predicted from the 3D RSA model. On the other hand, the roughness of the film was the lowest at the highest precursor layer density. It was shown that for low precursor layer density the film thickness increased with the number of layers in a nonlinear way. However, for high precursor layer density, the film thickness increased linearly with the number of layers and the average layer thickness was close to the hexagonal layer thickness equal to 1.73a p. It was concluded that our theoretical results can be effectively exploited for interpretation of the LbL processes involving colloid particles and polyelectrolytes.

  16. Dynamics of altered surface layer formation on dissolving silicates

    Science.gov (United States)

    Daval, Damien; Bernard, Sylvain; Rémusat, Laurent; Wild, Bastien; Guyot, François; Micha, Jean Sébastien; Rieutord, François; Magnin, Valérie; Fernandez-Martinez, Alejandro

    2017-07-01

    The extrapolation of mineral dissolution kinetics experiments to geological timescales has frequently been challenged by the observation that mineral dissolution rates decrease with time. In the present study, we report a detailed investigation of the early stages of wollastonite dissolution kinetics, linking time-resolved measurements of wollastonite dissolution rate as a function of crystallographic orientation to the evolution of physicochemical properties (i.e., diffusivity, density, and thickness) of amorphous silica-rich layers (ASSLs) that developed on each surface. Batch dissolution experiments conducted at room temperature and at far-from-equilibrium conditions revealed that the initial (i.e., ASSL-free) dissolution rate of wollastonite (R(hkl)) based on Ca release observe the following trend: R(010) ≈R(100) >R(101) >R(001) . A gradual decrease of the dissolution rate of some faces by up to one order of magnitude resulted in a modification of this trend after two days: R(010) ≫R(100) ⩾R(101) ≈R(001) . In parallel, the diffusivity of ASSLs developed on each face was estimated based on the measurement of the concentration profile of a conservative tracer (methylene blue) across the ASSL using nanoSIMS. The apparent diffusion coefficients of methylene blue as a function of the crystallographic orientation (Dapp(hkl)) observe the following trend: Dapp(010) ⩾Dapp(100) >Dapp(101) ≫Dapp(001) , and decreases as a function of time for the (1 0 0) and (1 0 1) faces. Finally, the density of ASSL was estimated based on the modeling of X-ray reflectivity patterns acquired as a function of time. The density of ASSLs developed on the (0 1 0) faces remains low and constant, whereas it increases for the ASSLs developed on the (0 0 1) faces. On the whole, our results suggest that the impact of the formation of ASSLs on the wollastonite dissolution rate is anisotropic: while some crystal faces are weakly affected by the formation of non-passivating ASSLs (e

  17. The Role Of The Biological Productivity Of The Forests Of The Carpathian National Nature Park In The Formation The Region's Carbon-Deposit Potential

    OpenAIRE

    Victoria Bokoch; R. Vasylyshyn

    2013-01-01

    The amount of phytomass and deposited carbon in forests of the Carpathian NNP and their contribution to the carbon budget of the region have been defined. Adapted and implemented methodology for calculating bioproductivity of tree stands by components of phytomass and depositing carbon was to find out their multifactorial dependencies on mensurational characteristics of stands, which are specified in the State forest inventory data. As the depending variable in modeling the dynamics of phytom...

  18. Cenomanian-Turonian Bentonites of the Boquillas Formation, Texas, USA: keys to understanding Carbonate Shelf deposition in a Greenhouse Climate

    Science.gov (United States)

    Bergman, Steve; Eldrett, James; Ma, Chao; Minisini, Daniel; Macaulay, Calum; Ozkan, Aysen; Kelly, Amy

    2016-04-01

    The Boquillas Formation (Fm.) (equivalent to the Eagle Ford Group) was deposited at the Southern end of the Cretaceous Western Interior Seaway (KWIS) and the northwestern margin of the Gulf of Mexico Carbonate Shelf (passive margin) in a starved retroarc foreland basin setting during part of the Cenomanian and Turonian Stages (CT; 97-90 Ma). The Boquillas Fm. includes several Oceanic Anoxic Events (OAE) marked by global Carbon Isotope Excursions (CIE) and trace metal anomalies. Here we provide a robust zircon U/Pb geochronologic framework used to accurately interpret and predict variability in facies distribution. The Boquillas Fm. consists of a succession of cyclic marlstone and limestone beds and over 300 bentonites deposited in a distal, restricted, suboxic setting mostly below storm wave base. Bentonites are generally homogenous clay-rich layers 1-10 cm thick (average 5 cm, up to 1 m) showing sharp contacts and strong yellow-orange mineral fluorescence under UV light. In addition to detailed logging of roadcuts, two research wells drilled behind outcrops, Shell IONA-1 and Shell INNES-1, recovered >330 m of continuous core from the Austin Chalk at surface through the Boquillas and Buda Limestone Fm. The bentonites form ~5% of the 60-111 m thick Boquillas Fm. intervals and are interpreted as distal pyroclastic fall deposits from large volume (>10-100 km3) Plinian eruptions from calderas associated with the subduction-related Western North American Cordilleran magmatic arc. Some of the Boquillas Fm. bentonites can be correlated using cores, petrophysical logs, geochemistry, and biostratigraphy for more than 1000 km to the north within the Western Interior Seaway at the CT global stratotype (GSSP) section at Pueblo, CO as well as many other sections in the KWIS. This contribution integrates new high-precision zircon U/Pb TIMs age data (2σ as low as 0.05 Myr) from both core and outcrop samples with independent proxies derived from sedimentology, biostratigraphy

  19. Three air quality studies: Great Lakes ozone formation and nitrogen dry deposition; and Tucson aerosol chemical characterization

    Science.gov (United States)

    Foley, Theresa

    The Clean Air Act of 1970 was promulgated after thousands of lives were lost in four catastrophic air pollution events. It authorized the establishment of National Ambient Air Quality Standards or (NAAQS) for six pollutants that are harmful to human health and welfare: carbon monoxide, lead, nitrogen dioxide, particulate matter, ozone and sulfur dioxide. The Clean Air Act also led to the establishment of the United Stated Environmental Protection Agency (US EPA) to set and enforce regulations. The first paper in this dissertation studies ozone in the Lake Michigan region (Foley, T., Betterton, E.A., Jacko, R., Hillery, J., 2011. Lake Michigan air quality: The 1994-2003 LADCO Aircraft Project (LAP). Atmospheric Environment 45, 3192-3202.) The Chicago-Milwaukee-Gary metropolitan area has been unable to meet the ozone NAAQS since the Clean Air Act was implemented. The Lake Michigan Air Directors' Consortium (LADCO) hypothesized that land breezes transport ozone precursor compounds over the lake, where a large air/water temperature difference creates a shallow conduction layer, which is an efficient reaction chamber for ozone formation. In the afternoon, lake breezes and prevailing synoptic winds then transport ozone back over the land. To further evaluate this hypothesis, LADCO sponsored the 1994-2003 LADCO Aircraft Project (LAP) to measure the air quality over Lake Michigan and the surrounding areas. This study has found that the LAP data supports this hypothesis of ozone formation, which has strong implications for ozone control strategies in the Lake Michigan region. The second paper is this dissertation (Foley, T., Betterton, E.A., Wolf, A.M.A., 2012. Ambient PM10 and metal concentrations measured in the Sunnyside Unified School District, Tucson, Arizona. Journal of the Arizona-Nevada Academy of Science, 43, 67-76) evaluated the airborne concentrations of PM10 (particulate matter with an aerodynamic diameter of 10 microns or less) and eight metalloids and metals

  20. Thaumasite formation in hydraulic mortars by atmospheric SO2 deposition

    Directory of Open Access Journals (Sweden)

    Blanco-Varela, M. T.

    2001-12-01

    Full Text Available Sulphation of mortars and concretes is a function of diverse environmental factors (SO2 aerosol, temperature, etc as well as some material characteristics. One of the phases that could be formed as consequence of the sulphation of the hydraulic binder is thaumasite. In this paper different hydraulic mortars have been exposed to laboratory exposure chambers in order to reproduce thaumasite formation due to atmospheric SO2. Under the laboratory exposure conditions, thaumasite was formed in hydraulic lime mortars, and mortars elaborated with ordinary Portland cement as well as mineralized white portland cement. However, thaumasite was not formed in mortars made of lime and pozzolan. The first product formed as a result of the SO2-mortar interaction was gypsum. Gypsum reacted with calcite and C-S-H gel, present in the samples, giving place to thaumasite. Low temperature promotes thaumasite formation.

    La sulfatación de morteros y hormigones depende de las condiciones ambientales (SO2 aerosol, temperatura, etc., así como de las características del material. Una de las fases que se puede formar como consecuencia de la sulfatación de los ligantes hidráulicos es la taumasita. En este trabajo se han expuesto diferentes morteros hidráulicos en cámaras de laboratorio con el fin de reproducir la formación de taumasita por efecto del SO2 atmosférico. Bajo las condiciones de laboratorio se formó taumasita en los morteros de cal hidráulica y en los morteros fabricados con cemento portland y cemento blanco mineralizado. Sin embargo, cuando el ligante utilizado en los morteros fue cal y puzolana, no se formó taumasita. El yeso fue el primer producto formado en la interacción entre los morteros y el SO2. A continuación, este yeso reaccionó con la calcita y el gel C-S-H dando lugar a la formación de taumasita. Las bajas temperaturas favorecieron la formación de taumasita.

  1. Dynamical Evidence for a Late Formation of Saturn's Moons

    CERN Document Server

    Ćuk, Matija; Nesvorný, David

    2016-01-01

    We explore the past evolution of Saturn's moons using direct numerical integrations. We find that the past Tethys-Dione 3:2 orbital resonance predicted in standard models likely did not occur, implying that the system is less evolved than previously thought. On the other hand, the orbital inclinations of Tethys, Dione and Rhea suggest that the system did cross the Dione-Rhea 5:3 resonance, which is closely followed by a Tethys-Dione secular resonance. A clear implication is that either the moons are significantly younger than the planet, or that their tidal evolution must be extremely slow (Q > 80,000). As an extremely slow-evolving system is incompatible with intense tidal heating of Enceladus, we conclude that the moons interior to Titan are not primordial, and we present a plausible scenario for the system's recent formation. We propose that the mid-sized moons re-accreted from a disk about 100 Myr ago, during which time Titan acquired its significant orbital eccentricity. We speculate that this disk has f...

  2. Traction force dynamics predict gap formation in activated endothelium.

    Science.gov (United States)

    Valent, Erik T; van Nieuw Amerongen, Geerten P; van Hinsbergh, Victor W M; Hordijk, Peter L

    2016-09-10

    In many pathological conditions the endothelium becomes activated and dysfunctional, resulting in hyperpermeability and plasma leakage. No specific therapies are available yet to control endothelial barrier function, which is regulated by inter-endothelial junctions and the generation of acto-myosin-based contractile forces in the context of cell-cell and cell-matrix interactions. However, the spatiotemporal distribution and stimulus-induced reorganization of these integral forces remain largely unknown. Traction force microscopy of human endothelial monolayers was used to visualize contractile forces in resting cells and during thrombin-induced hyperpermeability. Simultaneously, information about endothelial monolayer integrity, adherens junctions and cytoskeletal proteins (F-actin) were captured. This revealed a heterogeneous distribution of traction forces, with nuclear areas showing lower and cell-cell junctions higher traction forces than the whole-monolayer average. Moreover, junctional forces were asymmetrically distributed among neighboring cells. Force vector orientation analysis showed a good correlation with the alignment of F-actin and revealed contractile forces in newly formed filopodia and lamellipodia-like protrusions within the monolayer. Finally, unstable areas, showing high force fluctuations within the monolayer were prone to form inter-endothelial gaps upon stimulation with thrombin. To conclude, contractile traction forces are heterogeneously distributed within endothelial monolayers and force instability, rather than force magnitude, predicts the stimulus-induced formation of intercellular gaps. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Dynamic star formation in the massive DR21 filament

    CERN Document Server

    Schneider, N; Bontemps, S; Motte, F; Simon, R; Hennebelle, P; Federrath, C; Klessen, R

    2010-01-01

    The formation of massive stars is a highly complex process in which it is not clear whether the star-forming gas is in global gravitational collapse or in an equilibrium state, supported by turbulence. By studying one of the most massive and dense star-forming regions in the Galaxy at a distance of less than 3 kpc, the filament containing the well-known sources DR21 and DR21(OH), we expect to find observational signatures that allow to discriminate between the two views. We use molecular line data from our 13CO 1-0, CS 2-1, and N2H+ 1-0 survey of the Cygnus X region obtained with the FCRAO and high-angular resolution observations of CO, CS, HCO+, N2H+, and H2CO, obtained with the IRAM 30m telescope. We observe a complex velocity field and velocity dispersion in the DR21 filament in which regions of highest column-density, i.e. dense cores, have a lower velocity dispersion than the surrounding gas and velocity gradients that are not (only) due to rotation. Infall signatures in optically thick line profiles of ...

  4. Dynamical Formation of Close Binary Systems in Globular Clusters

    CERN Document Server

    Pooley, D; Anderson, S F; Baumgardt, H; Filippenko, A V; Gaensler, B M; Homer, L; Hut, P; Kaspi, V M; Margon, B; McMillan, S; Zwart, S P; Van der Klis, M; Verbunt, F

    2003-01-01

    We know from observations that globular clusters are very efficient catalysts in forming unusual short-period binary systems or their offspring, such as low-mass X-ray binaries (LMXBs; neutron stars accreting matter from low-mass stellar companions), cataclysmic variables (CVs; white dwarfs accreting matter from stellar companions), and millisecond pulsars (MSPs; rotating neutron stars with spin periods of a few ms). Although there has been little direct evidence, the overabundance of these objects in globular clusters has been attributed by numerous authors to the high densities in the cores, which leads to an increase in the formation rate of exotic binary systems through close stellar encounters. Many such close binary systems emit X-radiation at low luminosities (L_x < 10^{34} erg/s) and are being found in large numbers through observations with the Chandra X-ray Observatory. Here we present conclusive observational evidence for a link between the number of close binaries observed in X-rays in a globul...

  5. Variscan metagranitoids in the central Tauern Window (Eastern Alps, Austria) and their role in the formation of the Felbertal scheelite deposit

    Science.gov (United States)

    Kozlik, Michael; Raith, Johann G.

    2017-05-01

    The W mineralised Early Carboniferous orthogneisses (K1 and K3 orthogneiss) in the Felbertal scheelite deposit represent a chemically evolved metagranitoid series. Some of its characteristics are high concentrations of F (Window (;Zentralgneis;), the metaluminous dark-coloured K1-K3 orthogneiss shows some geochemical similarities with the peraluminous Felbertauern augengneiss, one of the regional orthogneisses exposed near the W deposit. Elevated concentrations of Nb (processes were a pre-requisite for the development of highly specialised W-rich granitic melts and formation of the world-class Felbertal scheelite deposit.

  6. Dynamics and structure formation in thin polymer melt films

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, Ralf [Max-Planck-Institut for Dynamics and Self-Organization, Bunsenstrasse 10, 37073 Goettingen (Germany); Herminghaus, Stephan [Max-Planck-Institut for Dynamics and Self-Organization, Bunsenstrasse 10, 37073 Goettingen (Germany); Neto, Chiara [Department of Applied Mathematics, Australian National University, Canberra ACT 0200 (Australia); Schlagowski, Stefan [Department of Applied Physics, University of Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany); Podzimek, Daniel [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany); Konrad, Renate [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany); Mantz, Hubert [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany); Jacobs, Karin [Experimental Physics, Saarland University, 66041 Saarbruecken (Germany)

    2005-03-09

    The stability of thin liquid coatings plays a fundamental role in everyday life. We studied the stability conditions of thin (3 to 300 nm) liquid polymer films on various substrates. The key role is played by the effective interface potential {phi} of the system air/film/substrate, which determines the dewetting scenario in case the film is not stable. We describe in this study how to distinguish a spinodal dewetting scenario from heterogeneous and homogeneous dewetting by analysing the emerging structures of the film surface by e.g. Minkowski measures. We also include line tension studies of tiny droplets, showing that the long-range part of {phi} does affect the drop profile, but only very close to the three phase boundary line. The dynamic properties of the films are characterized via various experimental methods: the form of the dewetting front, for example, was recorded by scanning probe microscopy and gives insight into the boundary condition between the liquid and the substrate. We further report experiments probing the viscosity and the glass transition temperature of nm-thick films using e.g. ellipsometry. Here we find that even short-chained polymer melts exhibit a significant reduction of the glass transition temperature as the film thickness is reduced below 100 nm.

  7. Formation of patterned arrays of Au nanoparticles on SiC surface by template confined dewetting of normal and oblique deposited nanoscale films

    Energy Technology Data Exchange (ETDEWEB)

    Ruffino, F., E-mail: francesco.ruffino@ct.infn.it; Grimaldi, M.G.

    2013-06-01

    We report on the formation of patterned arrays of Au nanoparticles (NPs) on 6H SiC surface. To this end, we exploit the thermal-induced dewetting properties of a template confined deposited nanoscale Au film. In this approach, the Au surface pattern order, on the SiC substrate, is established by a template confined deposition using a micrometric template. Then, a dewetting process of the patterned Au film is induced by thermal processes. We compare the results, about the patterns formation, obtained for normal and oblique deposited Au films. We show that the normal and oblique depositions, through the same template, originate different patterns of the Au film. As a consequence of these different starting patterns, after the thermal processes, different patterns for the arrays of NPs originating from the dewetting mechanisms are obtained. For each fixed deposition angle α, the pattern evolution is analyzed, by scanning electron microscopy, as a function of the annealing time at 1173 K (900 °C). From these analyses, quantitative evaluations on the NPs size evolution are drawn. - Highlights: • Micrometric template-confined nanoscale gold films are deposited on silicon carbide. • The dewetting process of template-confined gold films on silicon carbide is studied. • Comparison of dewetting process of normal and oblique deposited gold films is drawn. • Patterned arrays of gold nanoparticles on silicon carbide surface are produced.

  8. Build-up dynamics of heavy metals deposited on impermeable urban surfaces.

    Science.gov (United States)

    Wicke, D; Cochrane, T A; O'Sullivan, A

    2012-12-30

    A method using thin boards (3 cm thick, 0.56 m(2)) comprising different paving materials typically used in urban environments (2 asphalt types and concrete) was employed to specifically investigate air-borne deposition dynamics of TSS, zinc, copper and lead. Boards were exposed at an urban car park near vehicular traffic to determine the rate of contaminant build-up over a 13-day dry period. Concentration profiles from simulated rainfall wash-off were used to determine contaminant yields at different antecedent dry days. Maximum contaminant yields after 13 days of exposure were 2.7 kg ha(-1) for TSS, 35 g ha(-1) zinc, 2.3 g ha(-1) copper and 0.4 g ha(-1) lead. Accumulation of all contaminants increased over the first week and levelled off thereafter, supporting theoretical assumptions that contaminant accumulation on impervious surfaces asymptotically approaches a maximum. Comparison of different surface types showed approximately four times higher zinc concentrations in runoff from asphalt surfaces and two times higher TSS concentrations in runoff from concrete, which is attributed to different physical and chemical compositions of the pavement types. Contaminant build-up and wash-off behaviours were modelled using exponential and saturation functions commonly applied in the US EPA's Stormwater Management Model (SWMM) showing good correlation between measured and modelled concentrations. Maximum build-up, half-saturation time, build-up rate constants and wash-off coefficients, necessary for stormwater contaminant modelling, were determined for the four contaminants studied. These parameters are required to model contaminant concentrations in urban runoff assisting in stormwater management decisions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Deconvolution effect of near-fault earthquake ground motions on stochastic dynamic response of tunnel-soil deposit interaction systems

    Directory of Open Access Journals (Sweden)

    K. Hacıefendioğlu

    2012-04-01

    Full Text Available The deconvolution effect of the near-fault earthquake ground motions on the stochastic dynamic response of tunnel-soil deposit interaction systems are investigated by using the finite element method. Two different earthquake input mechanisms are used to consider the deconvolution effects in the analyses: the standard rigid-base input and the deconvolved-base-rock input model. The Bolu tunnel in Turkey is chosen as a numerical example. As near-fault ground motions, 1999 Kocaeli earthquake ground motion is selected. The interface finite elements are used between tunnel and soil deposit. The mean of maximum values of quasi-static, dynamic and total responses obtained from the two input models are compared with each other.

  10. Study on the effect of film formation process and deposition rate on the orientation of the CsI:Tl thin film

    Science.gov (United States)

    Tan, Xiaochuan; Liu, Shuang; Xie, Yijun; Guo, Lina; Ma, Shijun; Wang, Tianyu; Liu, Yong; Zhong, Zhiyong

    2017-10-01

    Although many new scintillation materials are developed, CsI:Tl is still prevailing because of its high scintillation efficiency. In this work, CsI:Tl thin films were fabricated by vacuum thermal evaporative deposition method and their morphology properties and growth orientation were observed by SEM and XRD. Photoluminescent spectra were used to measure the luminescent properties of the CsI:Tl thin film. The results show us the film formation process of CsI:Tl thin film and analyze the effect of film formation process and the deposition rate on the orientation of the CsI:Tl thin film.

  11. Dynamics of the current filament formation and its steady-state characteristics in chalcogenide based PCM

    Science.gov (United States)

    Bogoslovskiy, Nikita; Tsendin, Konstantin

    2017-03-01

    In the phase-change memory (PCM) crystallization occurs in the high-current filament which forms during switching to the conductive state. In the present paper we conduct a numerical modeling of the current filament formation dynamics in thin chalcogenide films using an electronic-thermal model based on negative-U centers tunnel ionization and Joule heating. The key role of inhomogeneities in the filament formation process is shown. Steady-state filament parameters were obtained from the analysis of the stationary heat conduction equation. The filament formation dynamics and the steady-state filament radius and temperature could be controlled by material parameters and contact resistance. Consequently it is possible to control the size of the region wherein crystallization occurs. A good agreement with numerous experimental data leads to the conclusion that thermal effects play a significant role in CGS conduction and high-current filament formation while switching.

  12. Process Dynamics and Fractal Analysis of New Phase Formation in Thermal Processes

    Institute of Scientific and Technical Information of China (English)

    Wang J; Shen Z.W; Shen Z. Q

    2001-01-01

    Boiling and fouling are taken as typical examples of new phase formation process to be analyzed and discussed in this paper. The process dynamics of nucleate boiling is analyzed and its mechanism is discussed from the view point of self-organization. Fouling, which is a more complicated phenomenon of new phase formation, involves series of underlying processes. The morphology and fractal analysis of fouling on low-energy surface and that with fouling inhibitors are studied and discussed. It is suggested that considering the process dynamics, fractal analysis and self-organization, a new avenue of research should be found.

  13. Molecular dynamics simulation about porous thin-film growth in secondary deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen Huawei [School of Mechanical Engineering and Automation, Beihang University, No. 37 Xuyuan Road, Haidian District, Beijing (China) and Mechanical Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, NSW 2522 (Australia)]. E-mail: chen_hua_wei@yahoo.com; Tieu, A. Kiet [Mechanical Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, NSW 2522 (Australia); Liu Qiang [School of Mechanical Engineering and Automation, Beihang University, No. 37 Xuyuan Road, Haidian District, Beijing (China); Hagiwara, Ichiro [Department of Mechanical Sciences and Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo (Japan); Lu Cheng [Mechanical Materials and Mechatronic Engineering, University of Wollongong, Northfields Avenue, NSW 2522 (Australia)

    2007-07-15

    The thin film growth has been confirmed to be assembled by an enormous number of clusters in experiments of CVD. Sequence of clusters' depositions proceeds to form the thin film at short time as gas fluids through surface of substrate. In order to grow condensed thin film using series of cluster deposition, the effect of initial velocity, substrate temperature and density of clusters on property of deposited thin film, especially appearance of nanoscale pores inside thin film must be investigated. In this simulation, three different cluster sizes of 203, 653, 1563 atoms with different velocities (0, 10, 100, 1000 and 3000 m/s) were deposited on a Cu(0 0 1) substrate whose temperatures were set between 300 and 1000 K. Four clusters and one cluster were used in primary deposition and secondary deposition, respectively. We have clarified that adhesion between clusters and substrate is greatly influenced by initial velocity. As a result, the exfoliation pattern of deposited thin film is dependent on initial velocity and different between them. One borderline dividing whole region into porous region and nonporous region are obtained to show the effect of growth conditions on appearance of nanoscale pores inside thin film. Moreover, we have also shown that the likelihood of porous thin film is dependent on the point of impact of a cluster relative to previously deposited clusters.

  14. Seasonal dynamics of phloem formation in Silver fir and Norway spruce as affected by drought

    OpenAIRE

    Gričar, Jožica; Čufar, Katarina

    2015-01-01

    The dynamics of phloem growth ring formation in silver fir (Abies alba Mill.) and Norway spruce (Picea abies Karst.) at different sites in Slovenia during the droughty growing season of 2003 was studied. We also determined the timing of cambial activity, xylem and phloem formation, and counted the number of cells in the completed phloem and xylem growth rings. Light microscopy of cross-sections revealed that cambial activity started on the phloem and xylem side simultaneously at all 3 plots. ...

  15. Dynamic Star Formation in the Massive DR21 Filament

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, N.; /Saclay; Csengeri, T.; /Saclay; Bontemps, S.; /OASU, Floirac; Motte, F.; /Saclay; Simon, R.; /Cologne U.; Hennebelle, P.; /Paris Observ.; Federrath, C.; /ZAH, Heidelberg; Klessen, R.; /ZAH, Heidelberg /KIPAC, Menlo Park

    2010-08-25

    The formation of massive stars is a highly complex process in which it is unclear whether the star-forming gas is in global gravitational collapse or an equilibrium state supported by turbulence and/or magnetic fields. By studying one of the most massive and dense star-forming regions in the Galaxy at a distance of less than 3 kpc, i.e. the filament containing the well-known sources DR21 and DR21(OH), we attempt to obtain observational evidence to help us to discriminate between these two views. We use molecular line data from our {sup 13}CO 1 {yields} 0, CS 2 {yields} 1, and N{sub 2}H{sup +} 1 {yields} 0 survey of the Cygnus X region obtained with the FCRAO and CO, CS, HCO{sup +}, N{sub 2}H{sup +}, and H{sub 2}CO data obtained with the IRAM 30m telescope. We observe a complex velocity field and velocity dispersion in the DR21 filament in which regions of the highest column-density, i.e., dense cores, have a lower velocity dispersion than the surrounding gas and velocity gradients that are not (only) due to rotation. Infall signatures in optically thick line profiles of HCO{sup +} and {sup 12}CO are observed along and across the whole DR21 filament. By modelling the observed spectra, we obtain a typical infall speed of {approx}0.6 km s{sup -1} and mass accretion rates of the order of a few 10{sup -3} M{sub {circle_dot}} yr{sup -1} for the two main clumps constituting the filament. These massive clumps (4900 and 3300 M{sub {circle_dot}} at densities of around 10{sup 5} cm{sup -3} within 1 pc diameter) are both gravitationally contracting. The more massive of the clumps, DR21(OH), is connected to a sub-filament, apparently 'falling' onto the clump. This filament runs parallel to the magnetic field. Conclusions. All observed kinematic features in the DR21 filament (velocity field, velocity dispersion, and infall), its filamentary morphology, and the existence of (a) sub-filament(s) can be explained if the DR21 filament was formed by the convergence of flows

  16. Effect of Dynamic Surface Tension on Droplet Formation of Surfactant Solution Injected from a Capillary Tube

    OpenAIRE

    山本, 剛宏; 加藤, 有樹; 山下, 敦史; Takehiro, YAMAMOTO; Yuki, Kato; Atsushi, Yamashita; 阪大院工; Osaka University

    2008-01-01

    Effects of dynamic surface tension on the droplet formation of surfactant solutions were studied. Aqueous solutions of CTAB at several surfactant concentrations were used as test fluids. A droplet formed when a surfactant solution was injected from a capillary tube was investigated and the relation between the droplet diameter and the injection velocity was measured. The diameter increased with increasing the velocity at relatively low velocities because the dynamic tension also increased. Ho...

  17. Aquifer composition and the tendency toward scale-deposit formation during reverse osmosis desalination - Examples from saline ground water in New Mexico, USA

    Science.gov (United States)

    Huff, G.F.

    2006-01-01

    Desalination is expected to make a substantial contribution to water supply in the United States by 2020. Currently, reverse osmosis is one of the most cost effective and widely used desalination technologies. The tendency to form scale deposits during reverse osmosis is an important factor in determining the suitability of input waters for use in desalination. The tendency toward scale formation of samples of saline ground water from selected geologic units in New Mexico was assessed using simulated evaporation. All saline water samples showed a strong tendency to form CaCO3 scale deposits. Saline ground water samples from the Yeso Formation and the San Andres Limestone showed relatively stronger tendencies to form CaSO4 2H2O scale deposits and relatively weaker tendencies to form SiO2(a) scale deposits than saline ground water samples from the Rio Grande alluvium. Tendencies toward scale formation in saline ground water samples from the Dockum Group were highly variable. The tendencies toward scale formation of saline waters from the Yeso Formation, San Andres Limestone, and Rio Grande alluvium appear to correlate with the mineralogical composition of the geologic units, suggesting that scale-forming tendencies are governed by aquifer composition and water-rock interaction. ?? 2006 Elsevier B.V. All rights reserved.

  18. A Model Study of Inclusions Deposition, Macroscopic Transport, and Dynamic Removal at Steel-Slag Interface for Different Tundish Designs

    Science.gov (United States)

    Chen, Chao; Ni, Peiyuan; Jonsson, Lage Tord Ingemar; Tilliander, Anders; Cheng, Guoguang; Jönsson, Pär Göran

    2016-06-01

    This paper presents computational fluid dynamics (CFD) simulation results of inclusions macroscopic transport as well as dynamic removal in tundishes. A novel treatment was implemented using the deposition velocity calculated by a revised unified Eulerian deposition model to replace the widely used Stokes rising velocity in the boundary conditions for inclusions removal at the steel-slag interface in tundishes. In this study, the dynamic removal for different size groups of inclusions at different steel-slag interfaces (smooth or rough) with different absorption conditions at the interface (partially or fully absorbed) in two tundish designs was studied. The results showed that the dynamic removal ratios were higher for larger inclusions than for smaller inclusions. Besides, the dynamic removal ratio was higher for rough interfaces than for smooth interfaces. On the other hand, regarding the cases when inclusions are partially or fully absorbed at a smooth steel-slag interface, the removal ratio values are proportional to the absorption proportion of inclusions at the steel-slag interface. Furthermore, the removal of inclusions in two tundish designs, i.e., with and without a weir and a dam were compared. Specifically, the tundish with a weir and a dam exhibited a better performance with respect to the removal of bigger inclusions (radii of 5, 7, and 9 μm) than that of the case without weir and dam. That was found to be due to the strong paralleling flow near the middle part of the top surface. However, the tundish without weir and dam showed a higher removal ratio of smaller inclusions (radius of 1 μm). The reason could be the presence of a paralleling flow near the inlet zone, where the inclusions deposition velocities were much higher than in other parts.

  19. FORMATION OF GOLD-BEARING HYDROFRACTURING BRECCIA BODIES IN TECTONIC LENSES: A CASE STUDY ON SHUANGWANG GOLD DEPOSIT, SHAANXI, CHINA

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Macro-microscopic tectonic analysis and lithologic features show that the gold-bearing breccia bodies in the Shuangwang gold deposit, for hydrofracturing of the deep-sourced and alkali-rich fluids in the Devonian sodic rock series, are identified as hydrofracturing breccia bodies. Since the Indosinian,intracontinental collisional orogenesis results in multiple fracturings and magmatic emplacements in the Qinling area. Deep-sourced fluids resulting from deep fractures and granitoid magmatic intrusion are of a supercritical nature. Joint action between the fluid-rock system and structures leads to hydroffacturing and ore formation of the gold deposit.Firstly, the progressive coaxial compression caused the competent sodic rock series and the incompetent pelitic rock series to be deformed and partitioned. Lens-like weak-strain domains are hence formed and distributed at the approximate equidistance zones and the linear strong-strain zones,respectively. Subsequently, the progressive non-coaxial shearing and right-lateral and high-angle oblique thrusting lead to the most developed fracture system in the core of the weak-strain domain to turn from compression to extension and to link up with the deep fracture systems. The periodical huge pressure decline in the pumping center causes the deep-sourced confined fluids to develop periodic tectonic pumping, hydrofracturing and precipitation-healing in the sodic rock series. The gold-bearing hydrofracturing breccia bodies are hence ultimately formed at near-equidistance tectonic lenses. On the basis of the above model, the predicted concealed gold-bearing hydrofracturing breccia bodies have been preliminarily validated by latest drillings.

  20. Thermally induced formation of metastable nanocomposites in amorphous Cr-Zr-O thin films deposited using reactive ion beam sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Rafaja, David, E-mail: rafaja@ww.tu-freiberg.de [Institute of Materials Science, Freiberg University of Technology, D-09599 Freiberg (Germany); Wüstefeld, Christina [Institute of Materials Science, Freiberg University of Technology, D-09599 Freiberg (Germany); Abrasonis, Gintautas [Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Braeunig, Stefan [Institute of Materials Science, Freiberg University of Technology, D-09599 Freiberg (Germany); Baehtz, Carsten [Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Hanzig, Florian; Dopita, Milan [Institute of Materials Science, Freiberg University of Technology, D-09599 Freiberg (Germany); Krause, Matthias [Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Gemming, Sibylle [Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany); Institute of Physics, Technische Universität Chemnitz, D-09126 Chemnitz (Germany)

    2016-08-01

    Successive crystallization of amorphous Cr-Zr-O thin films, formation of the (Cr,Zr){sub 2}O{sub 3}/(Zr,Cr)O{sub 2} nanocomposites and the thermally induced changes in the hexagonal crystal structure of metastable (Cr,Zr){sub 2}O{sub 3} were investigated by means of in situ high-temperature synchrotron diffraction experiments up to 1100 °C. The thin films were deposited at room temperature by using reactive ion beam sputtering, and contained 3–15 at.% Zr. At low Zr concentrations, chromium-rich (Cr,Zr){sub 2}O{sub 3} crystallized first, while the crystallization of zirconium-rich (Zr,Cr)O{sub 2} was retarded. Increasing amount of zirconium shifted the onset of crystallization in both phases to higher temperatures. For 3 at.% of zirconium in amorphous Cr-Zr-O, (Cr,Zr){sub 2}O{sub 3} crystallized at 600 °C. At 8 at.% Zr in the films, the crystallization of (Cr,Zr){sub 2}O{sub 3} started at 700 °C. At 15 at.% Zr, the Cr-Zr-O films remained amorphous up to the annealing temperature of 1000 °C. Metastable hexagonal (Cr,Zr){sub 2}O{sub 3} accommodated up to ~ 3 at.% Zr. Excess of zirconium formed tetragonal zirconia, which was stabilized by chromium. - Highlights: • Amorphous Cr-Zr-O thin films were deposited using reactive ion beam sputtering. • After annealing in vacuum, metastable (Cr,Zr){sub 2}O{sub 3}/(Zr,Cr)O{sub 2} nanocomposites form. • The crystallization temperature depends strongly on the Zr concentration. • Metastable hexagonal (Cr,Zr){sub 2}O{sub 3} accommodates up to 3.2 at.% of zirconium. • Zirconium oxide crystallizes in tetragonal form, as it is stabilized by chromium.

  1. Geology of the Lower Cretaceous Travis Peak Formation, East Texas. Depositional history, diagenesis, structure, and reservoir-engineering implications. Topical report, November 1982-February 1990

    Energy Technology Data Exchange (ETDEWEB)

    Dutton, S.P.; Laubach, S.E.; Tye, R.S.; Baumgardner, R.W.; Herrington, K.L.

    1990-06-01

    The report summarizes stratigraphic, petrographic, and structural studies of the Lower Cretaceous Travis Peak Formation, a low-permeability gas sandstone in East Texas, and presents reservoir engineering implications. Depositional systems in this region were interpreted from logs and cores and include (1) a braided- to meandering-fluvial system that forms the majority of the Travis Peak section; (2) deltaic deposits interbedded with the distal part of the fluvial system; (3) paralic deposits that overlie and interfinger with the deltaic and fluvial deposits near the top of the Travis Peak; and (4) shelf deposits present at the downdip extent of the formation. Petrographic studies indicate the sandstones are quartzarenites and subarkoses. Cementation by quartz, dolomite, ankerite, illite, chlorite, and reservoir bitumen have reduced porosity to less than 8 percent and permeability to less than 0.1 md throughout most of the formation. Structurally deeper sandstones are more intensely quartz cemented than are shallower sandstones and contain abundant, open natural fractures. Borehole breakouts and drilling-induced fractures in core can be used to predict horizontal stress directions and the direction of hydraulic fracture propagation. Hydraulic fractures propagate in directions subparallel to the east-northeast strike of the natural fractures; thus, hydraulically induced fractures may not intersect many natural fractures.

  2. Designing a Robust Nonlinear Dynamic Inversion Controller for Spacecraft Formation Flying

    Directory of Open Access Journals (Sweden)

    Inseok Yang

    2014-01-01

    Full Text Available The robust nonlinear dynamic inversion (RNDI control technique is proposed to keep the relative position of spacecrafts while formation flying. The proposed RNDI control method is based on nonlinear dynamic inversion (NDI. NDI is nonlinear control method that replaces the original dynamics into the user-selected desired dynamics. Because NDI removes nonlinearities in the model by inverting the original dynamics directly, it also eliminates the need of designing suitable controllers for each equilibrium point; that is, NDI works as self-scheduled controller. Removing the original model also provides advantages of ease to satisfy the specific requirements by simply handling desired dynamics. Therefore, NDI is simple and has many similarities to classical control. In real applications, however, it is difficult to achieve perfect cancellation of the original dynamics due to uncertainties that lead to performance degradation and even make the system unstable. This paper proposes robustness assurance method for NDI. The proposed RNDI is designed by combining NDI and sliding mode control (SMC. SMC is inherently robust using high-speed switching inputs. This paper verifies similarities of NDI and SMC, firstly. And then RNDI control method is proposed. The performance of the proposed method is evaluated by simulations applied to spacecraft formation flying problem.

  3. Characterizing and Exploring the Formation Mechanism of Salt Deposition by Reusing Advanced-softened, Silica-rich, Oilfield-produced Water (ASOW) in Superheated Steam Pipeline

    Science.gov (United States)

    Dong, Bin; Xu, Ying; Lin, Senmin; Dai, Xiaohu

    2015-11-01

    To dispose of large volumes of oilfield-produced water, an environmentally friendly method that reuses advanced-softened, silica-rich, oilfield-produced water (ASOW) as feedwater was implemented via a 10-month pilot-scale test in oilfield. However, salt deposition detrimental to the efficiency and security of steam injection system was generated in superheated steam pipeline. To evaluate the method, the characteristics and formation mechanism of the deposition were explored. The silicon content and total hardness of the ASOW were 272.20 mg/L and 0.018 mg/L, respectively. Morphology and composition of the deposition were determined by scanning electron microscope-energy dispersive spectrometry (SEM-EDS), inductively coupled plasma-mass spectroscopy (ICP-MS), X-ray diffraction (XRD), laser Raman spectroscopy (LRS) and X-ray photoelectron spectroscopy (XPS). Na2Si2O5, Na2CO3 and trace silanes were identified in the deposition. In addition, the solubility of the deposition was about 99%, suggesting that it is very different from traditional scaling. The results of a simulation experiment and thermal analysis system (TGA and TG-FTIR) proved that Na2CO3 and Si(OH)4 (gas) are involved in the formation of Na2Si2O5, which is ascribed mainly to the temperature difference between the superheated steam and the pipe wall. These findings provide an important reference for improving the reuse of ASOW and reducing its deposition.

  4. BIOGENIC INFLUENCES ON THE FORMATION AND LONG-TERM DYNAMICS OF COHESIVE SEDIMENTS

    Institute of Scientific and Technical Information of China (English)

    Joern V. PROCHNOW; C. SCHWEIM; Juergen KOENGETER

    2001-01-01

    Biogenic stabilization processes that result in the formation of biofilms and interparticle-networks can significantly alter the transport characteristics of finegrained sediment layers. The increase in the threshold of sediment motion can amount to up to several hundred percent. While planctic organisms are involved in the formation of depositing flocs and the early stages of consolidation, the secondary consolidation is controlled by microbial breakdown processes, leading to changes in the mechanical properties of cohesive sediments. While the primary stage of consolidation is completed in days, the secondary processes can last for decades. A preliminary series of erosion tests in an annular flume revealed demonstrated the biogenic impact in the early stages of sediment formation. Surrogate materials were used to simulate the governing properties of natural soft sediments.

  5. Micro- and nanobands in late Archean and Palaeoproterozoic banded-iron formations as possible mineral records of annual and diurnal depositions

    Science.gov (United States)

    Li, Yi-Liang

    2014-04-01

    The microbands in Precambrian banded-iron formations (BIFs) have been conjectured to record annual or even diurnal depositions. However, these bands have rarely been observed in high resolution at their true (micro) scale. Here, I suggest that nanobands of fine-grained hematite represent possible diurnal depositions and that microbands of chert/jasper represent possible annual depositions in three sets of BIFs: 2460-Myr BIFs from the Kuruman Iron Formation, Transvaal Supergroup of South Africa; 2480-Myr BIFs from the Dales Gorge Member of the Brockman Iron Formation, Western Australia; and 2728-Myr BIFs from the Hunter Mine Group, Abitibi Greenstone Belt, Canada. Observations made using scanning electron microscopy indicate that hematite and chert were syngenetic, and that there was a hiatus between their precipitation and the genesis of the remainder of the minerals containing structural Fe(II). Spindle-like grains of hematite, monocrystals of magnetite, and ferro-dolomite formed microbands of ∼30-70 μm in thickness, which appear cyclically in the matrix of the chert. Neither the band-bound magnetite and dolomite nor the linear formations of the hematite spindles represent annual depositions due to their diagenetic features. The thinnest microbands (∼3-∼12 μm) were observed in the chert and jasper, and indicate depositional rates of 6.6-22.2 m/Myr in the BIFs. These rates are consistent with the integrated deposition rates calculated by geochronologic methods for the BIFs, if annual deposition is assumed. The ∼26-nm nanobands observed only in hematite grains reflect an annual deposition of ∼18.6 μm, or ∼18.6 m/Myr, which is also consistent with the depositional rate calculated by geochronologic methods. It is tentatively suggested that these ∼26-nm nanobands were formed from the diurnal precipitation of Fe(III) resulting from the circadian metabolism of Fe(II)-oxidizing or oxygen-evolving photosynthetic microorganisms, which slowed down the rise

  6. Influence of acid deposition on regeneration dynamics along a disturbance intensity gradient

    Science.gov (United States)

    Sarah E. Stehn; Christopher R. Webster; Michael A. Jenkins; Shibu. Jose

    2010-01-01

    Now considered one of the most threatened vegetation communities in North America, spruce-fir forests of the southern Appalachians have been devastated by the combined impacts of the exotic balsam woolly adelgid (Adelges piceae, BWA) and chronic acid deposition.

  7. Dust formation and dynamic in magnetized and non-magnetized microwave discharge

    Science.gov (United States)

    Ouaras, Karim; Lombardi, Guillaume; Hassouni, Khaled

    2016-09-01

    Dusty plasmas studies are conducted for several decades to answer to various issues from microelectronic, nanotechnology, astrophysics and thermonuclear fusion devices. These studies are usually conducted in RF discharges at low pressure in which the major physics concerning dust formation mechanisms and dynamic is now well known. In our case, we focus on dust formation and dynamic in (i) microwave plasma under typical pressure conditions of RF discharges (50 Pa) and (ii) in magnetized (ECR: Electron Cyclotron Resonance) microwave plasma under very low pressure condition (0.1 to 1 Pa). The aim of this study is not only for fundamental purpose but also for respond to some issues concerning dust in fusion devices. Thus, we investigate the dust formation mechanisms and dynamic using laser extinction method and laser light scattering imaging coupling with SEM imaging in hydrocarbon plasma and with PVD system with using tungsten target (according to fusion device). We observed that dust formation occurs even if the very low pressure conditions are generally not suitable for nucleation growth in gas phase (the influence of the magnetic field will be discussed). We will also discuss about the particular dust dynamic behavior in microwave discharge in comparison with RF discharge.

  8. Formation Control of Mobile Agents with Second-order Nonlinear Dynamics in Unknown Environments Containing Obstacles

    NARCIS (Netherlands)

    Huang, Jie; Cao, Ming; Zhou, Ning

    2016-01-01

    This paper investigates the formation control problem of multiple mobile agents with second-order nonlinear dynamics in complex environments containing multiple obstacles. By employing the null-space-based behavioral (NSB) control architecture, a novel fast terminal sliding mode based adaptive contr

  9. Phase 1 user instruction manual. A geological formation - drill string dynamic interaction finite element program (GEODYN)

    Energy Technology Data Exchange (ETDEWEB)

    Tinianow, M.A.; Rotelli, R.L. Jr.; Baird, J.A.

    1984-06-01

    User instructions for the GEODYN Interactive Finite Element Computer Program are presented. The program is capable of performing the analysis of the three-dimensional transient dynamic response of a Polycrystalline Diamond Compact Bit - Bit Sub arising from the intermittent contact of the bit with the downhole rock formations. The program accommodates non-linear, time dependent, loading and boundary conditions.

  10. Transient Substrate-Induced Catalyst Formation in a Dynamic Molecular Network

    NARCIS (Netherlands)

    Fanlo-Virgos, Hugo; Alba, Andrea-Nekane R.; Hamieh, Saleh; Colomb-Delsuc, Mathieu; Otto, Sijbren

    2014-01-01

    In biology enzyme concentrations are continuously regulated, yet for synthetic catalytic systems such regulatory mechanisms are underdeveloped. We now report how a substrate of a chemical reaction induces the formation of its own catalyst from a dynamic molecular network. After complete conversion

  11. Dynamic controls on erosion and deposition on debris-flow fans.

    OpenAIRE

    Schürch, P.; Densmore, A. L.; Rosser, N.J.; B. W. McArdell

    2011-01-01

    Debris flows are among the most hazardous and unpredictable of surface processes in mountainous areas. This is partly because debris-flow erosion and deposition are poorly understood, resulting in major uncertainties in flow behavior, channel stability, and sequential effects of multiple flows. Here we apply terrestrial laser scanning and flow hydrograph analysis to quantify erosion and deposition in a series of debris flows at Illgraben, Switzerland. We identify flow depth as an important co...

  12. Isotopically heavy carbon in C21 to C25 regular isoprenoids in halite-rich deposits from the Sdm Formation, Dead Sea, Israel

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Grice, K.; Schouten, S.; Nissenbaum, A.; Charrach, J.

    1998-01-01

    A series of Miocene/Pliocene halite deposits (with extremely low organic carbon contents) from the Sdom Formation (Dead Sea Basin, Israel) have been studied. Distributions and contents of biomarkers have been determined using GC MS and irm-GCMS analyses, respectively. The hydrocarbon fractions cons

  13. Formation of PdHg by reaction of palladium thin film contacts deposited onto mercuric iodide ({alpha}-HgI{sub 2}) radiation detector crystals

    Energy Technology Data Exchange (ETDEWEB)

    Medlin, D.L. [Sandia National Labs., Livermore, CA (United States); Van Scyoc, J.M. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Gilbert, T.S. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Schlesinger, T.E. [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering; Boehme, D. [Sandia National Labs., Livermore, CA (United States); Schieber, M. [Sandia National Labs., Livermore, CA (United States); Natarajan, M. [TN Technologies, Inc., Round Rock, TX (United States); James, R.B. [Sandia National Labs., Livermore, CA (United States)

    1996-10-01

    The microstructure and phase distribution of palladium thin films sputter deposited onto {alpha}-HgI{sub 2} for use as electrical contacts in radiation detectors are investigated using electron microscopy. Our results show a limited reaction to form palladium mercuride (PdHg). It is shown that the formation of PdHg via several reaction pathways is thermodynamically feasible. (orig.).

  14. Investigation of the deposit formation in pipelines connecting liquefaction reactors; 1t/d PSU ni okeru ekika hanno tokan fuchakubutsu no seisei yoin ni kansuru ichikosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Y.; Nogami, Y.; Inokuchi, K. [Mitsui SRC Development Co. Ltd., Tokyo (Japan); Mochizuki, M.; Imada, K. [Nippon Steel Corp., Tokyo (Japan)

    1996-10-28

    The liquefaction reaction system of an NEDOL process coal liquefaction 1t/d PSU was opened and checked to investigate the cause of the rise of differential pressure between liquefaction reactors of the PSU. The liquefaction test at a coal concentration of 50 wt% using Tanito Harum coal was conducted, and it was found that the differential pressure between reactors was on the increase. By the two-phase flow pressure loss method, deposition thickness of deposit in pipelines was estimated at 4.4mm at the time of end operation, which agreed with a measuring value obtained from a {gamma} ray. The rise of differential pressure was caused by deposit formation in pipelines connecting reactors. The main component of the deposit is calcite (CaCO3 60-70%) and is the same as the usual one. It is also the same type as the deposit on the reactor wall. Ca in coal ash is concerned with this. To withdraw solid matters deposited in the reactor, there are installed pipelines for the withdrawal at the reactor bottom. The solid matters are regularly purged by reverse gas for prevention of clogging. As the frequency of purge increases, the deposit at the reactor bottom decreases, but the deposit attaches strongly to pipelines connecting reactors. It is presumed that this deposit is what Ca to be discharged out of the system as a form of deposition solid matter naturally in the Ca balance precipitated as calcite in the pipeline connecting the reactor. 3 refs., 5 figs., 4 tabs.

  15. Physicochemical Conditions of the Formation of Beryl and Aquamarin in Mufushan Granopegmatite Deposit,Hunan Province,China

    Institute of Scientific and Technical Information of China (English)

    李兆麟; 牛贺才; 等

    1994-01-01

    The formation of the Mufushan granopegmatite was closely related to the Late Yenshanian multiphase and multistage magmatic activities,More than one generation of beryl and aquamarine occur in different types of pegmatite in the granites.The presence of melt and melt-fluid inclusions strongly indicates a melt-solution character of the pegmatitic magma.Forming temperatures of the different generations of beryl in a Na+-K+,Ca2+-CO32--Cl--SO42- solution ranges from 990℃to 200℃.Aquamarine was formed at 720-180℃.The contents of alkali metals(Na++K+)in th ore-formming solution of aquamarine are lower than those in the beryl,but the contents of alkali earths(Ca) and salinity are higher,The granite was generated by remelting of the basement formation(meta-sedimentary rocks of the Lengjiaxi Group)which also served as the source of ore-forming material.Beryllium in the pegmatite was transported mainly in the form of Na[Be(CO3)2],with part of it being complexed with Cl- and SO42-.During the generation and evolution of the pegmatite,equilibrium might have been reached in the solid-melt-fluid or solid-fluid system.The intergranular solutions may have reacted with the early crystallized minerals,resulting in potash-feldsparization,albitization and muscovitization during which the ore-forming elements were mobilized and transported in favour of ore deposition.

  16. The multiscale simulation of metal organic chemical vapor deposition growth dynamics of GaInP thin film

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    As a Group III–V compound, GaInP is a high-efficiency luminous material. Metal organic chemical vapor deposition (MOCVD) technology is a very efficient way to uniformly grow multi-chip, multilayer and large-area thin film. By combining the computational fluid dynamics (CFD) and the kinetic Monte Carlo (KMC) methods with virtual reality (VR) technology, this paper presents a multiscale simulation of fluid dynamics, thermodynamics, and molecular dynamics to study the growth process of GaInP thin film in a vertical MOCVD reactor. The results of visualization truly and intuitively not only display the distributional properties of the gas’ thermal and flow fields in a MOCVD reactor but also display the process of GaInP thin film growth in a MOCVD reactor. The simulation thus provides us with a fundamental guideline for optimizing GaInP MOCVD growth.

  17. The Romulus Cosmological Simulations: A Physical Approach to the Formation, Dynamics and Accretion Models of SMBHs

    CERN Document Server

    Tremmel, Michael; Governato, Fabio; Volonteri, Marta; Quinn, Tom; Pontzen, Andrew; Anderson, Lauren

    2016-01-01

    We present a novel implementation of supermassive black hole (SMBH) formation, dynamics, and accretion in the massively parallel tree+SPH code, ChaNGa. This approach improves the modeling of SMBHs in fully cosmological simulations, allowing for a more detailed analysis of SMBH-galaxy co-evolution throughout cosmic time. Our scheme includes novel, physically motivated models for SMBH formation, dynamics and sinking timescales within galaxies, and SMBH accretion of rotationally supported gas. The sub-grid parameters that regulate star formation (SF) and feedback from SMBHs and SNe are optimized against a comprehensive set of z = 0 galaxy scaling relations using a novel, multi-dimensional parameter search. We have incorporated our new SMBH implementation and parameter optimization onto a new set of high resolution, large-scale cosmological simulations called Romulus. We present initial results from our flagship simulation, Romulus25, showing that our SMBH model results in SF efficiency, SMBH masses, and global c...

  18. Formation dynamics of FeN thin films on Cu(100)

    KAUST Repository

    Heryadi, Dodi

    2012-01-01

    To investigate the structural and magnetic properties of thin films of FeN we have performed ab initio molecular dynamics simulations of their formation on Cu(100) substrates. The iron nitride layers exhibit a p4gm(2 × 2) reconstruction and order ferromagnetically in agreement with experiment. We establish the dynamics and time scale of the film formation as a function of the film thickness. The process is split in two phases: formation of almost flat FeN layers and optimization of the distance to the substrate. Our calculated magnetic moments are 1.67 μ B, 2.14 μ B, and 2.21 μ B for one, two, and three monolayers of iron nitride. © 2011 Elsevier B.V. All rights reserved.

  19. Formation of the Wiesloch Mississippi Valley-type Zn-Pb-Ag deposit in the extensional setting of the Upper Rhinegraben, SW Germany

    Science.gov (United States)

    Pfaff, Katharina; Hildebrandt, Ludwig H.; Leach, David L.; Jacob, Dorrit E.; Markl, Gregor

    2010-01-01

    The Mississippi Valley-type (MVT) Zn-Pb-Ag deposit in the Wiesloch area, Southwest Germany, is controlled by graben-related faults of the Upper Rhinegraben. Mineralization occurs as vein fillings and irregular replacement ore bodies consisting of sphalerite, banded sphalerite, galena, pyrite, sulfosalts (jordanite and geocronite), barite, and calcite in the Middle Triassic carbonate host rock. Combining paragenetic information, fluid inclusion investigations, stable isotope and mineral chemistry with thermodynamic modeling, we have derived a model for the formation of the Wiesloch deposit. This model involves fluid mixing between ascending hot brines (originating in the crystalline basement) with sedimentary formation waters. The ascending brines originally had a near-neutral pH (around 6) and intermediate oxidation state, reflecting equilibrium with granites and gneisses in the basement. During fluid ascent and cooling, the pH of the brine shifted towards more acidic (around 4) and the oxidation state increased to conditions above the hematite-magnetite buffer. These chemical characteristics contrast strongly with those of the pore and fracture fluid residing in the limestone aquifer, which had a pH between 8 and 9 in equilibrium with calcite and was rather reduced due to the presence of organic matter in the limestone. Mixing between these two fluids resulted in a strong decrease in the solubility of silver-bearing sphalerite and galena, and calcite. Besides Wiesloch, several Pb-Zn deposits are known along the Upper Rhinegraben, including hydrothermal vein-type deposits like Badenweiler and the Michael mine near Lahr. They all share the same fluid origin and formation process and only differ in details of their host rock and fluid cooling paths. The mechanism of fluid mixing also seems to be responsible for the formation of other MVT deposits in Europe (e.g., Reocin, Northern Spain; Treves, Southern France; and Cracow-Silesia, Poland), which show notable

  20. DYNAMICAL FORMATION OF CAVITY FOR COMPOSED THERMAL HYPERELASTIC SPHERES IN NON-UNIFORM TEMPERATURE FIELDS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Dynamical formation and growth of cavity in a sphere composed of two incompressible thermal-hyperelastic Gent-Thomas materials were discussed under the case of a non-uniform temperature field and the surface dead loading. The mathematical model was first presented based on the dynamical theory of finite deformations. An exact differential relation between the void radius and surface load was obtained by using the variable transformation method. By numerical computation, critical loads and cavitation growth curves were obtained for different temperatures. The influence of the temperature and material parameters of the composed sphere on the void formation and growth was considered and compared with those for static analysis. The results show that the cavity occurs suddenly with a finite radius and its evolvement with time displays a non-linear periodic vibration and that the critical load decreases with the increase of temperature and also the dynamical critical load is lower than the static critical load under the same conditions.

  1. Dynamic WTA optimization model of air defense operation of warships' formation

    Institute of Scientific and Technical Information of China (English)

    Li Jinjun; Cong Rong; Xiong Jiguang

    2006-01-01

    WTA (weapon-target allocation) of air defense operation is a very complicated problem and current models focus on static and restricted WTA problem mostly. Based on the dynamic characteristics of air defense operational command and decision of warships' formation, a dynamic WTA model is established. Simulation results show that switch fire and repetition fire of anti-air weapon systems affect the result of the air defense operation remarkably and the dynamic model is more satisfying than static ones. Related results are gained based on the analysis of the simulation results and the results are accordant with the intuitionistic tactical judgment. The model is some reference for the research of air defense C3I system of warships' formation.

  2. Quick and inexpensive paraffin-embedding method for dynamic bone formation analyses

    Science.gov (United States)

    Porter, Amy; Irwin, Regina; Miller, Josselyn; Horan, Daniel J.; Robling, Alexander G.; McCabe, Laura R.

    2017-01-01

    We have developed a straightforward method that uses paraffin-embedded bone for undemineralized thin sectioning, which is amenable to subsequent dynamic bone formation measurements. Bone has stiffer material properties than paraffin, and therefore has hereforto usually been embedded in plastic blocks, cured and sectioned with a tungsten carbide knife to obtain mineralized bone sections for dynamic bone formation measures. This process is expensive and requires special equipment, experienced personnel, and time for the plastic to penetrate the bone and cure. Our method utilizes a novel way to prepare mineralized bone that increases its compliance so that it can be embedded and easily section in paraffin blocks. The approach is simple, quick, and costs less than 10% of the price for plastic embedded bone sections. While not effective for static bone measures, this method allows dynamic bone analyses to be readily performed in laboratories worldwide which might not otherwise have access to traditional (plastic) equipment and expertise. PMID:28198415

  3. Complex dynamics of osteoclast formation and death in long-term cultures.

    Directory of Open Access Journals (Sweden)

    Timur Akchurin

    Full Text Available BACKGROUND: Osteoclasts, cells responsible for bone resorption, contribute to the development of degenerative, metabolic and neoplastic bone diseases, which are often characterized by persistent changes in bone microenvironment. We aimed to investigate the dynamics of osteoclast formation and death in cultures that considerably exceeded the length of standard protocol and to design a mathematical model describing osteoclastogenesis. METHODOLOGY/PRINCIPAL FINDINGS: RAW 264.7 monocytic cells fuse to form multinucleated osteoclasts upon treatment with pro-resorptive cytokine RANKL. We have found that in long-term experiments (15-26 days, the dynamics of changes in osteoclast numbers was remarkably complex and qualitatively variable in different experiments. Whereas 19 of 46 experiments exhibited single peak of osteoclast formation, in 27 experiments we observed development of successive waves of osteoclast formation and death. Periodic changes in osteoclast numbers were confirmed in long-term cultures of mouse bone marrow cells treated with M-CSF and RANKL. Because the dynamics of changes in osteoclast numbers was found to be largely independent of monocytes, a two-species model of ordinary differential equations describing the changes in osteoclasts and monocytes was ineffective in recapitulating the oscillations in osteoclast numbers. Following experimental observation that medium collected from mature osteoclasts inhibited osteoclastogenesis in fresh cultures, we introduced a third variable, factor f, to describe osteoclast-derived inhibitor. This model allowed us to simulate the oscillatory changes in osteoclasts, which were coupled to oscillatory changes in the factor f, whereas monocytes changed exponentially. Importantly, to achieve the experimentally observed oscillations with increasing amplitude, we also had to assume that osteoclast presence stimulates osteoclast formation. CONCLUSIONS/SIGNIFICANCE: This study identifies the critical

  4. Submicrometer Hollow Bioglass Cones Deposited by Radio Frequency Magnetron Sputtering: Formation Mechanism, Properties, and Prospective Biomedical Applications.

    Science.gov (United States)

    Popa, A C; Stan, G E; Besleaga, C; Ion, L; Maraloiu, V A; Tulyaganov, D U; Ferreira, J M F

    2016-02-01

    This work reports on the unprecedented magnetron sputtering deposition of submicrometric hollow cones of bioactive glass at low temperature in the absence of any template or catalyst. The influence of sputtering conditions on the formation and development of bioglass cones was studied. It was shown that larger populations of well-developed cones could be achieved by increasing the argon sputtering pressure. A mechanism describing the growth of bioglass hollow cones is presented, offering the links for process control and reproducibility of the cone features. The composition, structure, and morphology of the as-synthesized hollow cones were investigated by energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), grazing incidence geometry X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)-selected area electron diffraction (SAED). The in vitro biological performance, assessed by degradation tests (ISO 10993-14) and cytocompatibility assays (ISO 10993-5) in endothelial cell cultures, was excellent. This allied with resorbability and the unique morphological features make the submicrometer hollow cones interesting candidate material devices for focal transitory permeabilization of the blood-brain barrier in the treatment of carcinoma and neurodegenerative disorders.

  5. Characterization of heterolithic deposits using electrofacies analysis in the tide-dominated Lower Jurassic Cook Formation (Gullfaks Field, offshore Norway)

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R. [Imperial College of Science, Technology and Medicine, London (United Kingdom). T.H. Huxley School of Environment, Earth Sciences and Engineering; Johnson, H.D.

    2001-08-01

    A range of heterolithic facies, comprising thinly interbedded (millimetre-decimetre scale) sandstones and mudstones, characterizes the heterogeneous Lower Jurassic Cook Formation, including the productive Cook-3 reservoir in the Gullfaks Field. These heterolithic facies were deposited in a tide-dominated estuarine to deltaic setting and show up as massive 'shaly-sands' on conventional wireline logs. This makes the recognition and discrimination of different heterolithic facies types virtually impossible, which severely limits detailed reservoir geological and petrophysical predictions. This problem has been addressed by undertaking a high resolution electrofacies analysis using core facies as a 'training set' and applying this, through multivariate statistical techniques, to the interpretation of the conventional logs. An electrofacies database was created comprising five genetically linked rock types (ranging from lenticular-wavy bedding, through flaser bedding and into clean/massive sandstones). This electrofacies scheme was validated with reference to c. 125 m of cored section from five wells using gamma-ray, density and neutron logs. Multivariate statistical techniques have enabled probabilistic discrimination of the different types of heterolithic facies down to intervals of only 0.25 to 0.5 m thick, which is considerably greater than could be achieved using conventional well-log evaluation techniques alone. (author)

  6. A combined molecular dynamics and kinetic Monte Carlo calculation to study sputter erosion and beam assisted deposition

    CERN Document Server

    Betz, G

    2002-01-01

    To extend the time scale in molecular dynamics (MD) calculations of sputtering and ion assisted deposition we have coupled our MD calculations to a kinetic Monte Carlo (KMC) calculation. In this way we have studied surface erosion of Cu(1 0 0) under 200-600 eV Cu ion bombardment and growth of Cu on Cu(1 0 0) for deposition at thermal energies up to energies of 100 eV per atom. Target temperatures were varied from 100 to 400 K. The coupling of the MD calculation to a KMC calculation allows us to extend our calculations from a few ps, a time scale typical for MD, to times of up to seconds until the next Cu particle will impinge/be deposited on the crystal surface of about 100 nm sup 2 in size. The latter value of 1 s is quite realistic for a typical experimental sputter erosion or deposition experiment. In such a calculation thermal diffusion processes at the surface and annealing of the surface after energetic ion bombardment can be taken into account. To achieve homo-epitaxial growth of a film the results cle...

  7. Formation Dynamics and Quantitative Prediction of Hydrocarbons of the Superpressure System in the Dongying Sag

    Institute of Scientific and Technical Information of China (English)

    SUI Fenggui; HAO Xuefeng; LIU Qing; ZHUO Qingong; ZHANG Shouchun

    2008-01-01

    Based on the theory of formation dynamics of oil/gas pools, the Dongying sag can be divided into three dynamic systems regarding the accumulation of oil and gas: the superpressure closed system,the semi-closed system and the normal pressure open system. Based on the analysis of genesis of superpressure in the superpressure closed system and the rule of hydrocarbon expulsion,it is found that hydrocarbon generation is related to superpressure, which is the main driving factor of hydrocarbon migration. Micro fractures formed by superpressure are the main channels for hydrocarbon migration. There are three dynamic patterns for hydrocarbon expulsion: free water drainage, hydrocarbon accumulation and drainage through micro fissures. In the superpressure closed system, the oil-driving-water process and oil/gas accumulation were completed in lithologic traps by way of such two dynamic patterns as episodic evolution of superpressure systems and episodic pressure release of faults. The oil-bearing capacity of lithologic traps is intimately related to reservoir-forming dynamic force. Quantitative evaluation of dynamic conditions for pool formation can effectively predict the oil-bearing capability of traps.

  8. Basin-Scale Sand Deposition in the Upper Triassic Xujiahe Formation of the Sichuan Basin, Southwest China: Sedimentary Framework and Conceptual Model

    Institute of Scientific and Technical Information of China (English)

    Xiucheng Tan; Qingsong Xia; Jingshan Chen; Ling Li; Hong Liu; Bing Luo; Jiwen Xia; Jiajing Yang

    2013-01-01

    The Upper Triassic Xujiahe(须家河) Formation in the Sichuan (四川) Basin,Southwes China is distinctive for the basin-scale sand deposition.This relatively rare sedimentary phenomenon has not been well interpreted.Here we addressed this issue by discussing sedimentary framework and conceptual model.Analysis of sedimentary setting implied that the basin received transgression during the deposition.It had multiple provenance supplies and river networks,as being surrounded by oldlands in multiple directions including the north,east and south.Thus,the basin was generally characterized by coastal and widely open and shallow lacustrine deposition during the Late Triassic Xujiahe period.This is similar to the modern well-known Poyang(鄱阳) Lake.Therefore,we investigated the framework and conceptual model of the Sichuan Basin during the Xujiahe period with an analogue to the Poyang Lake.Results show that the conceptual model of the deposition can be divided into transgressive and regressive stages.The first,third and fifth members of the formation are in transgressive stage and the deposits are dominated by shore and shallow lacustrine mud.In contrast,the deposition is mainly of braided river channel sand deposits during the regressive stage,mainly including the second,fourth and sixth members of the formation.The sand deposited in almost the entire basin because of the lateral migration and forward moving of the cross networks of the braided rivers.The multiple alternations of short and rapid transgression and relatively long regression are beneficial to the basin-scale sand deposition.Thus,the main channel of the braided river and its extensional areas are favorable for the development of hydrocarbon reservoir.This provides practical significance to the reservoir evaluation and exploration.In addition,the results also justify the relatively distinctive sedimentary phenomenon in the study area and may also have implications for understanding the large

  9. Dynamics of the formation of laser-induced periodic surface structures (LIPSS) upon femtosecond two-color double-pulse irradiation of metals, semiconductors, and dielectrics

    Science.gov (United States)

    Höhm, S.; Herzlieb, M.; Rosenfeld, A.; Krüger, J.; Bonse, J.

    2016-06-01

    In order to address the dynamics and physical mechanisms of LIPSS formation for three different classes of materials (metals, semiconductors, and dielectrics), two-color double-fs-pulse experiments were performed on Titanium, Silicon and Fused Silica. For that purpose a Mach-Zehnder interferometer generated polarization controlled (parallel or cross-polarized) double-pulse sequences at 400 nm and 800 nm wavelength, with inter-pulse delays up to a few picoseconds. Multiple of these two-color double-pulse sequences were collinearly focused by a spherical mirror to the sample surfaces. The fluence of each individual pulse (400 nm and 800 nm) was always kept below its respective ablation threshold and only the joint action of both pulses lead to the formation of LIPSS. Their resulting characteristics (periods, areas) were analyzed by scanning electron microscopy. The periods along with the LIPSS orientation allow a clear identification of the pulse which dominates the energy coupling to the material. For strong absorbing materials (Silicon, Titanium), a wavelength-dependent plasmonic mechanism can explain the delay-dependence of the LIPSS. In contrast, for dielectrics (Fused Silica) the first pulse always dominates the energy deposition and LIPSS orientation, supporting a non-plasmonic formation scenario. For all materials, these two-color experiments confirm the importance of the ultrafast energy deposition stage for LIPSS formation.

  10. Dynamics of Semantic and Word-Formation Subsystems of the Russian Language: Historical Dynamics of the Word Family

    Directory of Open Access Journals (Sweden)

    Olga Ivanovna Dmitrieva

    2015-09-01

    Full Text Available The article provides comprehensive justification of the principles and methods of the synchronic and diachronic research of word-formation subsystems of the Russian language. The authors also study the ways of analyzing historical dynamics of word family as the main macro-unit of word-formation system. In the field of analysis there is a family of words with the stem 'ход-' (the meaning of 'motion', word-formation of which is investigated in different periods of the Russian literary language. Significance of motion-verbs in the process of forming a language picture of the world determined the character and the structure of this word family as one of the biggest in the history of the Russian language. In the article a structural and semantic dynamics of the word family 'ход-' is depicted. The results of the study show that in the ancient period the prefixes of verbal derivatives were formed, which became the apex-branched derivational paradigms existing in modern Russian. The old Russian period of language development is characterized by the appearance of words with connotative meaning (with suffixes -ishk-, -ichn-, as well as the words with possessive semantics (with suffixes –ev-, -sk-. In this period the verbs with the postfix -cz also supplement the analyzed word family. The period of formation of the National Russian language was marked by the loss of a large number of abstract nouns and the appearance of neologisms from some old Russian abstract nouns. The studied family in the modern Russian language is characterized by the following processes: the appearance of terms, the active semantic derivation, the weakening of word-formation variability, the semantic differentiation of duplicate units, the development of subsystem of words with connotative meanings, and the preservation of derivatives in all functional styles.

  11. Formation and dynamics of van der Waals molecules in buffer-gas traps

    CERN Document Server

    Brahms, Nathan; Zhang, Peng; Kłos, Jacek; Forrey, Robert C; Au, Yat Shan; Sadeghpour, H R; Dalgarno, A; Doyle, John M; Walker, Thad G

    2011-01-01

    We show that weakly bound He-containing van der Waals molecules can be produced and magnetically trapped in buffer-gas cooling experiments, and provide a general model for the formation and dynamics of these molecules. Our analysis shows that, at typical experimental parameters, thermodynamics favors the formation of van der Waals complexes composed of a helium atom bound to most open-shell atoms and molecules, and that complex formation occurs quickly enough to ensure chemical equilibrium. For molecular pairs composed of a He atom and an S-state atom, the molecular spin is stable during formation, dissociation, and collisions, and thus these molecules can be magnetically trapped. Collisional spin relaxations are too slow to affect trap lifetimes. However, helium-3-containing complexes can change spin due to adiabatic crossings between trapped and untrapped Zeeman states, mediated by the anisotropic hyperfine interaction, causing trap loss. We provide a detailed model for Ag3He molecules, using ab initio calc...

  12. An unusually energetic basaltic phreatomagmatic eruption: Using deposit characteristics to constrain dilute pyroclastic density current dynamics

    Science.gov (United States)

    Brand, Brittany D.; Clarke, Amanda B.

    2012-10-01

    Multiple, highly erosive base surges of the Table Rock Complex tuff ring (TRC2), Oregon, produced dune-bedded deposits with crest to crest bedform wavelengths up to 200 m, which are amongst the largest ever recognized in the deposits of pyroclastic density currents. Here we use bedform wavelength, surmounted obstacles, and a large chute-and-pool feature to estimate near-source velocities (118-233 m s- 1), lower-bound velocities at radial distances of 1.6, 2 and 4.7 km from source (34, 29 and 20 m s- 1, respectively), and corresponding column collapse heights (up to 2.8 km). This paper represents one of the few studies that attempt to quantify flow characteristics, such as emplacement velocities at different distances from source, eruption column collapse height, and eruptive energy, based on deposit characteristics.

  13. Population synthesis of planet formation using a torque formula with dynamic effects

    CERN Document Server

    Sasaki, Takanori

    2016-01-01

    Population synthesis studies into planet formation have suggested that distributions consistent with observations can only be reproduced if the actual Type I migration timescale is at least an order of magnitude longer than that deduced from linear theories. Although past studies considered the effect of the Type I migration of protoplanetary embryos, in most cases they used a conventional formula based on static torques in isothermal disks, and employed a reduction factor to account for uncertainty in the mechanism details. However, in addition to static torques, a migrating planet experiences dynamic torques that are proportional to the migration rate. These dynamic torques can impact on planet migration and predicted planetary populations. In this study, we derived a new torque formula for Type I migration by taking into account dynamic corrections. This formula was used to perform population synthesis simulations with and without the effect of dynamic torques. In many cases, inward migration was slowed si...

  14. Molecular dynamics in computational materials sciences: From the study of nanostructure formation to the design of fluorescent dyes

    Science.gov (United States)

    Irle, Stephan

    2016-12-01

    On overview is given over the use of approximate density functional theory as basis for performing direct molecular dynamics simulations on ground and excited states. In the case of nanostructure formation, we discuss the relationship between fullerene, nanotube, and graphene formation. In the case of fluorescent molecules, we elucidate the importance of excited state dynamics for fluorescent properties.

  15. Role of hydrodynamic factors in controlling the formation and location of unconformity-related uranium deposits: insights from reactive-flow modeling

    Science.gov (United States)

    Aghbelagh, Yousef Beiraghdar; Yang, Jianwen

    2017-03-01

    The role of hydrodynamic factors in controlling the formation and location of unconformity-related uranium (URU) deposits in sedimentary basins during tectonically quiet periods is investigated. A number of reactive-flow modeling experiments at the deposit scale were carried out by assigning different dip angles and directions to a fault and various permeabilities to hydrostratigraphic units). The results show that the fault dip angle and direction, and permeability of the hydrostratigraphic units govern the convection pattern, temperature distribution, and uranium mineralization. A vertical fault results in uranium mineralization at the bottom of the fault within the basement, while a dipping fault leads to precipitation of uraninite below the unconformity either away from or along the plane of the fault, depending on the fault permeability. A more permeable fault causes uraninite precipitates along the fault plane, whereas a less permeable one gives rise to the precipitation of uraninite away from it. No economic ore mineralization can form when either very low or very high permeabilities are assigned to the sandstone or basement suggesting that these units seem to have an optimal window of permeability for the formation of uranium deposits. Physicochemical parameters also exert an additional control in both the location and grade of URU deposits. These results indicate that the difference in size and grade of different URU deposits may result from variation in fluid flow pattern and physicochemical conditions, caused by the change in structural features and hydraulic properties of the stratigraphic units involved.

  16. Source dynamics of radiocesium-contaminated particulate matter deposited in an agricultural water reservoir