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Sample records for surface geoelectrical studies

  1. Poorly studied phenomena in geoelectrics

    Directory of Open Access Journals (Sweden)

    В. С. Могилатов

    2016-12-01

    Full Text Available Undoubtedly, modern geoelectric technologies emerge in the result of the development of traditional approaches and techniques. However of more interest is the appearance of completely new technologies based on new effects and new models of interaction of geological medium and electromagnetic field. The author does not commit to indicate principally new directions, but only wants to discuss some poorly known facts from the theory and practice of geoelectrics. The outcome of this study could be considered attracting the attention of experts to non-traditional signals in geoelectrics. The reviewed phenomena of interest, not fully implemented in practice in the author’s opinion, are field split into two polarizations: transverse electric (the ТЕ-field and transverse magnetic (the ТМ-field, then some poorly known properties of ТМ-field, the role of bias currents, the anisotropy of horizontal resistances, the role of geomagnetic field in geoelectric sounding, the unique resolution of CSEM (Controlled Source Electro-Magnetic techniques at sea.

  2. Geo-electrical investigation of near surface conductive structures suitable for groundwater accumulation in a resistive crystalline basement environment: A case study of Isuada, southwestern Nigeria

    Science.gov (United States)

    Kayode, J. S.; Adelusi, A. O.; Nawawi, M. N. M.; Bawallah, M.; Olowolafe, T. S.

    2016-07-01

    This paper presents a geophysical surveying for groundwater identification in a resistive crystalline basement hard rock in Isuada area, Southwestern Nigeria. Very low frequency (VLF) electromagnetic and electrical resistivity geophysical techniques combined with well log were used to characterize the concealed near surface conductive structures suitable for groundwater accumulation. Prior to this work; little was known about the groundwater potential of this area. Qualitative and semi-quantitative interpretations of the data collected along eight traverses at 20 m spacing discovered conductive zones suspected to be fractures, faults, and cracks which were further mapped using Vertical Electrical Sounding (VES) technique. Forty VES stations were utilized using Schlumberger configurations with AB/2 varying from 1 to 100 m. Four layers i.e. the top soil, the weathered layer, the partially weathered/fractured basement and the fresh basement were delineated from the interpreted resistivity curves. The weathered layers constitute the major aquifer unit in the area and are characterized by moderately low resistivity values which ranged between about 52 Ωm and 270 Ωm while the thickness varied from 1 to 35 m. The depth to the basement and the permeable nature of the weathered layer obtained from both the borehole and the hand-dug wells was used to categorize the groundwater potential of the study area into high, medium and low ratings. The groundwater potential map revealed that about 45% of the study area falls within the low groundwater potential rating while about 10% constitutes the medium groundwater potential and the remaining 45% constitutes high groundwater potential. The low resistivity, thick overburden, and fractured bedrock constitute the aquifer units and the series of basement depressions identified from the geoelectric sections as potential conductive zones appropriate for groundwater development.

  3. Geoelectric Evaluation of Groundwater Potential: A Case Study of ...

    African Journals Online (AJOL)

    Michael Horsfall

    A total of seven vertical electrical sounding (VES) was carried out using the. Schlumberger ... From the geoelectric section, the area shows a vertical and lateral lithologic heterogeneity as a result of variation in depositional conditions which made ... Three main rivers drain the study area; the River. Owan, Onuan and Ule and ...

  4. Geoelectrical Monitoring for the characterisation of the near surface interflow in small alpine catchment areas during continuous rain

    Science.gov (United States)

    Ita, A.; Römer, A.; Markart, G.; Klebinder, K.; Bieber, G.; Kohl, B.

    2009-04-01

    In a pilot study the bandwidth of the near surface interflow and subsurface stormflow was investigated on a hill slope complex at the military training centre Lizum/Walchen (approx. 2000m above sea level) in Tyrol. High amounts of precipitation (about 250 mm) were applied within 2 days by use of a transportable spray irrigation installation. During the first day water from a creek was applied to the test site. On the following day the site was sprinkled with a salt tracer for an hour followed by creek water for the rest of the day. To characterise the runoff, different measurements techniques were used in the irrigation field. The subsurface runoff was registered in calibrated tanks. Changes in soil moisture were measured with buried TDR-waveguides - arranged in four profiles from 15 cm to 115 cm soil depth in maximum. In addition three geoelectrical profiles were measured. Two geoelectrical profiles were positioned orthogonal to the slope in the precipitation area, where one was reaching over the edge. The third profile was parallel to the slope overlapping with the second profile. Electrode distances were 0.25 cm and 0.50 cm respectively with 48 electrodes per profile. Geoelectrical measurements were done periodically before, during and after the rain simulation experiments. These have been carried out with the newly developed geoelectric instrument of the Geological survey of Austria, GEOMON4D. The advantage of the instrument is that it can measure a resistivity section at high speed and in an automated, meaning monitoring mode. Therefore, it is possible to register small and fast changes in the soil conductivity caused by a tracer. Summarising it can be said that the resistivity soundings give a detailed picture regarding the geological structure of the research area as well as explicit knowledge of how the near surface interflow spreads out in the subsurface. The geoelectric measurements deliver precise information about the behaviour of the salt tracer, its

  5. Geoelectric hazard assessment: the differences of geoelectric responses during magnetic storms within common physiographic zones

    Science.gov (United States)

    Cuttler, Stephen W.; Love, Jeffrey J.; Swidinsky, Andrei

    2018-01-01

    Geomagnetic field data obtained through the INTERMAGNET program are convolved with with magnetotelluric surface impedance from four EarthScope USArray sites to estimate the geoelectric variations throughout the duration of a magnetic storm. A duration of time from June 22, 2016, to June 25, 2016, is considered which encompasses a magnetic storm of moderate size recorded at the Brandon, Manitoba and Fredericksburg, Virginia magnetic observatories over 3 days. Two impedance sites were chosen in each case which represent different responses while being within close geographic proximity and within the same physiographic zone. This study produces estimated time series of the geoelectric field throughout the duration of a magnetic storm, providing an understanding of how the geoelectric field differs across small geographic distances within the same physiographic zone. This study shows that the geoelectric response of two sites within 200 km of one another can differ by up to two orders of magnitude (4484 mV/km at one site and 41 mV/km at another site 125 km away). This study demonstrates that the application of uniform 1-dimensional conductivity models of the subsurface to wide geographic regions is insufficient to predict the geoelectric hazard at a given site. This necessitates that an evaluation of the 3-dimensional conductivity distribution at a given location is necessary to produce a reliable estimation of how the geoelectric field evolves over the course of a magnetic storm.

  6. Groundwater potential prediction by using geoelectricity method a case study in Simpang Lima and around it

    Science.gov (United States)

    Rahmawati, D. R.; Supriyadi; Aryani, N. P.; Naufal, M. A.

    2018-03-01

    Water is an important natural resource, which is available both on surface as well as in recharge zone of weathered layer and in various other suitable water reservoir formations/structures below the surface. The study was conducted in Semarang City, Indonesian. Simpang Lima area were chosen since they have geology record of thick alluvium. The condition of Simpang Lima and around it which currently has developed into the main business area in Semarang City. This is marked by the presence like hotels, super market, that is more than one. This condition certainly requires a supply of water for various purposes that support economic efforts in the region. During this time the water needs are met by drilling wells and used as much as possible without taking into account the impact of water utilization. This study aims to determine the zones that have the potential existence of groundwater. The method used is Geoelectric method with Shlumberger configuration in 7 distributed spatial point. The results showed that there is a potential groundwater in eastern Pekunden, Erlanga, behind The Hotel Horizon, and Simpang Lima. Groundwater is found successively at an average depth of 15 meters under earth’s surface.

  7. The study of local sources of ULF geoelectric signals with steep fronts

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    Y. B. Chirkov

    2004-06-01

    Full Text Available The method for recognition and monitoring of ULF electrotelluric signals with steep fronts is presented. The method is based on the multicomponent measurements of the geoelectric field and recognition of the clusters of signals using the data of spatial-polarization filtering. This detects the local sources of the signals associated with the variation of mode of deformation of the medium. The method was applied to the study of geoelectric sources associated with aftershocks of the Racha-Djava earthquake. The field observations show with a fair degree of confidence that these signals are generated by a small number of local zones in the vicinity of the observer (at a range of tens-hundreds meters. The spatial distribution and the dynamic properties of the local sources are described. The analysis of observations leads to the conclusion that the dynamics of the local sources of ULF signals with steep fronts may be considered possible electrotelluric precursors of the earthquakes. Consideration is given to the feasibility of the well-known VAN method for earthquake prediction. The overall methodological aspects of the current studies of the electrotelluric precursors of the earthquakes are discussed.

  8. Joint application of Geoelectrical Resistivity and Ground Penetrating Radar techniques for the study of hyper-saturated zones. Case study in Egypt

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    Hany S. Mesbah

    2017-06-01

    Full Text Available This paper presents the results of the application of the Geoelectrical Resistivity Sounding (GRS and Ground Penetrating Radar (GPR for outlining and investigating of surface springing out (flow of groundwater to the base of an service building site, and determining the reason(s for the zone of maximum degree of saturation; in addition to provide stratigraphic information for this site. The studied economic building is constructed lower than the ground surface by about 7 m. A Vertical Electrical Sounding (VES survey was performed at 12 points around the studied building in order to investigate the vertical and lateral extent of the subsurface sequence, three VES's were conducted at each side of the building at discrete distances. And a total of 9 GPR profiles with 100- and 200-MHz antennae were conducted, with the objective of evaluating the depth and the degree of saturation of the subsurface layers. The qualitative and quantitative interpretation of the acquired VES's showed easily the levels of saturations close to and around the studied building. From the interpretation of GPR profiles, it was possible to locate and determine the saturated layers. The radar signals are penetrated and enabled the identification of the subsurface reflectors. The results of GPR and VES showed a good agreement and the integrated interpretations were supported by local geology. Finally, the new constructed geoelectrical resistivity cross-sections (in contoured-form, are easily clarifying the direction of groundwater flow toward the studied building.

  9. Joint application of Geoelectrical Resistivity and Ground Penetrating Radar techniques for the study of hyper-saturated zones. Case study in Egypt

    Science.gov (United States)

    Mesbah, Hany S.; Morsy, Essam A.; Soliman, Mamdouh M.; Kabeel, Khamis

    2017-06-01

    This paper presents the results of the application of the Geoelectrical Resistivity Sounding (GRS) and Ground Penetrating Radar (GPR) for outlining and investigating of surface springing out (flow) of groundwater to the base of an service building site, and determining the reason(s) for the zone of maximum degree of saturation; in addition to provide stratigraphic information for this site. The studied economic building is constructed lower than the ground surface by about 7 m. A Vertical Electrical Sounding (VES) survey was performed at 12 points around the studied building in order to investigate the vertical and lateral extent of the subsurface sequence, three VES's were conducted at each side of the building at discrete distances. And a total of 9 GPR profiles with 100- and 200-MHz antennae were conducted, with the objective of evaluating the depth and the degree of saturation of the subsurface layers. The qualitative and quantitative interpretation of the acquired VES's showed easily the levels of saturations close to and around the studied building. From the interpretation of GPR profiles, it was possible to locate and determine the saturated layers. The radar signals are penetrated and enabled the identification of the subsurface reflectors. The results of GPR and VES showed a good agreement and the integrated interpretations were supported by local geology. Finally, the new constructed geoelectrical resistivity cross-sections (in contoured-form), are easily clarifying the direction of groundwater flow toward the studied building.

  10. Surface-downhole and crosshole geoelectrics for monitoring of brine injection at the Ketzin CO2 storage site

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    Rippe, Dennis; Bergmann, Peter; Labitzke, Tim; Wagner, Florian; Schmidt-Hattenberger, Cornelia

    2016-04-01

    The Ketzin pilot site in Germany is the longest operating on-shore CO2 storage site in Europe. From June 2008 till August 2013, a total of ˜67,000 tonnes of CO2 were safely stored in a saline aquifer at depths of 630 m to 650 m. The storage site has now entered the abandonment phase, and continuation of the multi-disciplinary monitoring as part of the national project "CO2 post-injection monitoring and post-closure phase at the Ketzin pilot site" (COMPLETE) provides the unique chance to participate in the conclusion of the complete life cycle of a CO2 storage site. As part of the continuous evaluation of the functionality and integrity of the CO2 storage in Ketzin, from October 12, 2015 till January 6, 2015 a total of ˜2,900 tonnes of brine were successfully injected into the CO2 reservoir, hereby simulating in time-lapse the natural backflow of brine and the associated displacement of CO2. The main objectives of this brine injection experiment include investigation of how much of the CO2 in the pore space can be displaced by brine and if this displacement of CO2 during the brine injection differs from the displacement of formation fluid during the initial CO2 injection. Geophysical monitoring of the brine injection included continuous geoelectric measurements accompanied by monitoring of pressure and temperature conditions in the injection well and two adjacent observation wells. During the previous CO2 injection, the geoelectrical monitoring concept at the Ketzin pilot site consisted of permanent crosshole measurements and non-permanent large-scale surveys (Kiessling et al., 2010). Time-lapse geoelectrical tomographies derived from the weekly crosshole data at near-wellbore scale complemented by six surface-downhole surveys at a scale of 1.5 km showed a noticeable resistivity signature within the target storage zone, which was attributed to the CO2 plume (Schmidt-Hattenberger et al., 2011) and interpreted in terms of relative CO2 and brine saturations (Bergmann

  11. A Climatological Analysis of Geoelectric Field Variations

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    Balch, C. C.; Cilliers, P. J.; Viljanen, A.; Thomson, A. W. P.; Gaunt, T.; Lotz, S.

    2015-12-01

    Geomagnetic variations induce currents that flow along natural and artificial conducting pathways including critical infrastructure such as the electrical power grid. The level of induction is controlled by the geoelectric field at the Earth's surface, which may be calculated by convolving the geomagnetic variations with an earth-conductivity model. We carry out a long-term statistical analysis of calculated geoelectric field variations using about 30 years of geomagnetic observations from selected locations. We find two dominant classes of geoelectric field events: those that are driven by shock arrival at the Earth which produces a sudden impulse or sudden storm commencement, and those that are associated with geomagnetic storm activity. We provide a historical perspective on the distribution of the geoelectric field for these types of events and compare the geoelectric field with other measures of geomagnetic activity. We also demonstrate the sensitivity of these results to different conductivity models and to geomagnetic latitude.

  12. Geomagnetic and Geoelectric determination of Topography and ...

    African Journals Online (AJOL)

    Geomagnetic and geoelectric surveys were executed in a complex zone with the aim of determining the topography and estimated depth of constituent bedrock in the study area. The ground magnetic and geoelectric – Schlumberger's vertical electrical sounding – methods were applied for this study. The presence of a ...

  13. Application of Geoelectrical Resistivity Technique for Groundwater Explorationin Lower Ponnaiyar Sub-Watershed, Tamilnadu, India

    Science.gov (United States)

    Poongothai, S.; Sridhar, N.

    2017-07-01

    GeoelectricalResistivity survey was carried out in Lower Ponnaiyar Sub-watershed, to intercept the sub-surface lithology and groundwater prospective zones. Twenty Vertical Electrical Sounding (VES) of the Schlumberger configuration were performed with an AB/2 separation 100 m. The acquired geoelectric data were interpreted with curve matching and computer iteration using Inverse Slope software. The results showed the presence of six geoelectric layers comprising Alluvium, Sand, Silt, Clay, Clayey sand and Hard Rock. The investigations also revealed the range of resistivityvalues from - 40 to 400 Ωm, while the depth of aquifer ranged between 6 and 100 m. The prospective for theoccurrence of groundwater in the Lower Ponnaiyar watershed was categorized as high, good, moderate and low by interpreting the sub-surface geophysical studies. The groundwater recharge structures like percolation pond, check dam have to be constructed in the moderate and low zones of groundwater potential so as to augment the groundwater resources.

  14. The limiting factor relationship between geoelectric and hydraulic ...

    African Journals Online (AJOL)

    The objectives of study included the estimation of the aquifer hydraulic parameters of the Pleistocene aged alluvium Formation from both the geoelectric and pumping test datasets with a view to determining empirical and limiting factor relationships and groundwater conditions. 106 geoelectric sounding and seventeen ...

  15. Estimation of porosity and specific yield by application of geoelectrical method - A case study in western Iran

    Science.gov (United States)

    Taheri Tizro, A.; Voudouris, K.; Basami, Y.

    2012-08-01

    SummaryVertical Electric Soundings (VESs) with a Schlumberger electrode configuration were recorded in the Mahidashat plain, Kermanshah province, located in the western part of Iran, in order to estimate the hydraulic parameters of the aquifer system. The geological formations surrounding the plain are mainly cretaceous limestones and plagioclases with regular layering of Miocene age. The northwestern part of plain is composed of red marls of Eocene age. In order to ascertain the subsurface geological framework the general distribution of resistivity response of the geological formations was obtained. Geoelectrical sections along a number of lines have been prepared. Probable lithological patterns from these sections have been identified. In the present study, an attempt to estimate porosity and specific yield from resistivity data has been made for alluvial aquifers in Mahidashat plain. The results indicated that the porosity varies from 0.18 to 0.66 and the average specific yield is 0.15. The estimated data are compared with field real data and their credibility was calculated by using the paired t-test method.

  16. Geoelectrical and hydrochemical study for the assessment of seawater intrusion evolution in coastal aquifers of Oualidia, Morocco

    Science.gov (United States)

    Fadili, Ahmed; Najib, Saliha; Mehdi, Khalid; Riss, Joëlle; Malaurent, Philippe; Makan, Abdelhadi

    2017-11-01

    This study aims to assess the evolution of seawater intrusion between 1992 and 2011 periods in the coastal aquifers of Oualidia. To achieve this objective, the combination of geoelectrical and hydrochemical methods was adopted. Apparent resistivity maps, using 74 Vertical Electrical Sounding (VES) performed on 1992, allowed to distinguish two different zones. The conductive one, with apparent resistivity ranging between 4 and 86 Ω·m, is limited to 1 km with respect to the ocean. Meanwhile, the resistant one is much farther from the coastline. Besides, results of Electrical Resistivity Tomography (ERT) profiles performed during 2011 are in good agreement with those obtained by apparent resistivity maps. The ERT profiles show a conductive level characterized by low resistivity below 30 Ω·m assigned to seawater intrusion effect. Moreover, hydrochemical analysis, performed on 19 wells during three different periods, on June, December 2010 and May 2011, indicates that the most affected part with marine waters was at that time localized in the first kilometer from the ocean, with high amounts of Na+ and Cl- ions. Beyond this fringe, mineralization becomes very weak. Overall, the comparison of old VES with recent ERT coupled with hydrochemical results suggest no important evolution of the salt wedge since 1992.

  17. An Engineering Foundation Investigation using the Geoelectric ...

    African Journals Online (AJOL)

    The geoelectric method – Schlumberger vertical electrical sounding (VES) technique – was utilised in the geophysical investigation of an engineering site in Ode-Aye Southwestern Nigeria. The aim of the study was to determine the existence of competent and incompetent geologic layers and the depth at which they occur.

  18. Geoelectric Investigation for Groundwater Prospects in Ejeme ...

    African Journals Online (AJOL)

    Geoelectric investigation for groundwater prospects in Ejeme-Aniogor and environs, Aniocha- South Local Government Area of Delta State, Nigeria was carried out with a view to determining the near subsurface lithologies and depths; as well as thickness of the various aquiferous zones/units in the study area. Fourteen ...

  19. An Engineering Foundation Investigation using the Geoelectric ...

    African Journals Online (AJOL)

    Journal of the Nigerian Association of Mathematical Physics ... The aim of the study was to determine the existence of competent and incompetent geologic layers and the depth at which they occur. A total of twenty VES ... Three distinct geoelectric layers were observed- sand, loose sandstone and shale layers respectively.

  20. Geoelectric investigation to delineate groundwater potential and ...

    Indian Academy of Sciences (India)

    Geoelectric investigation to delineate groundwater potential and recharge zones in Suki river basin, ... future, investigation was carried out with the help of geophysical indicators. Vertical electrical sounding studies were conducted at 17 ..... This will aid in understanding the spatial variation of these parameters to demar-.

  1. Groundwater vulnerability assessment using hydrogeologic and geoelectric layer susceptibility indexing at Igbara Oke, Southwestern Nigeria

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    T.E. Oni

    2017-12-01

    Full Text Available Groundwater vulnerability assessment was carried out at Igbara Oke Southwestern Nigeria, with a view to classify the area into vulnerability zones, by applying the electrical resistivity method, using Schlumberger electrode arrays with maximum electrode separation (AB/2 of 65 m in (41 different locations for data acquisition. Geoelectric parameters (layer resistivity and thickness were determined from the interpreted data. The study area comprises four geoelectric layers (topsoil, lateritic layer, weathered/fractured layer and fresh basement. The geoelectric parameters of the overlying layers across the area were used to assess the vulnerability of the underlying aquifers to near-surface contaminants with the aid of vulnerability maps generated. Three models were compared by maps using geo-electrically derived models; longitudinal conductance, GOD (groundwater occurrence, overlying lithology and depth to the aquifer and GLSI (geoelectric layer susceptibility indexing. The total longitudinal conductance map shows the north central part of the study area as a weakly protected (0.1–0.19 area, while the northern and southern parts have poor protective capacity (<0.1; this is in agreement with the GOD method which shows the northern part of the study area as less vulnerable (0–0.1 while the southern part has low/moderate (0.1–0.3 vulnerability to contamination. The longitudinal conductance exaggerates the degree of susceptibility to contamination than the GOD and GLSI models. From the models, vulnerability to contamination can be considered higher at the southern part than the northern part and therefore, sources of contamination like septic tank, refuse dump should be cited far from groundwater development area. Keywords: Aquifer vulnerability, Longitudinal conductance, GOD and GLSI

  2. Subgrid geoelectric field specification for GIC modeling

    Science.gov (United States)

    Butala, M.; Grawe, M.; Kamalabadi, F.; Makela, J. J.

    2017-12-01

    Geomagnetically induced currents (GICs) result from surface geomagnetic field (ěc{B}) variation driven by space weather disturbances. For the most intense disturbances, the consequences can range from power grid instability to even widespread failure. Modeling GICs to assess vulnerability requires the specification of the surface geoelectric field (ěc{E}) at all spatial locations coincident with the electric power system. In this study, we investigate how to best reproduce ěc{E} given the available sparse, irregularly spaced magnetometer measurements of ěc{B} and suitable electromagnetic transfer functions (EMTFs) to transform the local ěc{B} to ěc{E}. The assessment is made against ground truth from publicly available ěc{E} measurements provided by the EarthScope magnetotelluric (MT) array, a set of 7 fixed and several transportable joint ěc{B} and ěc{E} sensors. The scope of this study spans several dimensions: geomagnetic disturbance intensity, spatial interpolation scheme, and EMTF type, i.e., 1-D models based on studies of local geology and 3-D models derived from the EarthScope MT data.

  3. Deep geoelectrical studies in the Finnmark and the Pechenga area by means of the `Khibiny' source

    Science.gov (United States)

    Zhamaletdinov, A. A.; Tokarev, A. D.; Vinogradov, Yu. A.; Asming, V. E.; Otchkur, N. A.; Ronning, J. S.; Lile, O. B.

    1993-12-01

    As part of the Soviet-Norwegian programme in geology and geophysics, an investigation of electroconductivity in the upper part of the Earth's crust was carried out in 1989-1991. The measurements were performed using an electrical dipole source, 'Khibiny', which is situated on the Kola Peninsula, close to the Norwegian border. A 26 kW car generator supplied square pulses with a peak to peak current of 100 A in the 'Khibiny' cable; at a frequency of 0.125 Hz. The distance between the source and the measuring points varied from 60 to 130 km. A stacking technique was applied to identify the weak electromagnetic signals. All the measurements were conducted using a six-component digital automatic station, ZAIS, produced at the Institute of Fundamental Physics of the USSR Academy of Science. As a result of the studies, several conductive current channels in the Pechenga structure on the Russian side of the border were traced into the Pasvik area in Norway. Detailed information on the deeper parts of the electroconductive structures in this area was obtained.

  4. Groundwater quality assessment using geoelectrical and geochemical approaches: case study of Abi area, southeastern Nigeria

    Science.gov (United States)

    Ebong, Ebong D.; Akpan, Anthony E.; Emeka, Chimezie N.; Urang, Job G.

    2017-09-01

    The electrical resistivity technique which involved the Schlumberger depth sounding method and geochemical analyses of water samples collected from boreholes was used to investigate the suitability of groundwater aquifers in Abi for drinking and irrigation purposes. Fifty randomly located electrical resistivity data were collected, modeled, and interpreted after calibration with lithologic logs. Ten borehole water samples were collected and analysed to determine anion, cation concentrations and some physical and chemical parameters, such as water colour, temperature, total dissolved solids, and electrical conductivity. The results show that the lithostratigraphy of the study area is composed of sands, sandstones (fractured, consolidated and loosed), siltstones, shales (compacted and fractured) of the Asu River Group, Eze-Aku Formation which comprises the aquifer units, and the Nkporo Shale Formation. The aquifer conduits are known to be rich in silicate minerals, and the groundwater samples in some locations show a significant amount of Ca2+, Mg2+, and Na+. These cations balanced the consumption of H+ during the hydrolytic alteration of silicate minerals. The geochemical analysis of groundwater samples revealed dominant calcium-magnesium-carbonate-bicarbonate water facies. Irrigation water quality parameters, such as sodium absorption ratio, percentage of sodium, and permeability index, were calculated based on the physico-chemical analyses. The groundwater quality was observed to be influenced by the interaction of some geologic processes but was classified to be good to excellent, indicating its suitability for domestic and irrigation purposes.

  5. Geoelectrical investigation for the assessment of groundwater conditions: a case study

    Directory of Open Access Journals (Sweden)

    M. Nakhaei

    2005-06-01

    Full Text Available An electrical resistivity survey involving Vertical Electrical Soundings (VES was carried out in the Shooro Basin in Southeast Iran in order to study groundwater conditions such as depth, thickness and aquifer boundaries. Vertical electrical soundings by Schlumberger array were conducted in this area. The resistivity Schlumberger soundings which have a maximum current electrode spacing (AB ranging from 200 m to 600 m were carried out at 207 positions in 19 profiles. Interpretation of these soundings indicates the presence of an alluvial aquifer. This aquifer is divided into eastern and western parts by the Shooro River, which comprises a variable thickness and resistivity of deposits. The average permeability coefficient and resistivity in the western part, especially southwest is higher than the eastern part of the aquifer. Therefore, it seems that Shooro River follows a fault zone in the region. The high resistivity of west part is due to the water quality and the existence of alluvial fan with coarse grain materials. Low aquifer resistivities in the east are associated with finer materials and also brackish water infiltration from the adjacent basin mainly in the central part of the aquifer. Furthermore, zones with high yield potential have been determined in this research based on the resistivity data.

  6. Geoelectrical mapping for improved performance of SUDS in clay tills

    DEFF Research Database (Denmark)

    Bockhorn, Britta; Møller, Ingelise; Klint, Knud Erik S.

    2015-01-01

    geological methods, including borehole soil sample descriptions, one excavation description and a near-surface spear auger-mapping project. The experiments returned a significant correlation of geoelectrical and spear auger-mapped surface sediments. Furthermore, a highly permeable oxidized fracture zone...

  7. Geoelectrical characterisation of basement aquifers: the case of Iberekodo, southwestern Nigeria

    Science.gov (United States)

    Aizebeokhai, Ahzegbobor P.; Oyeyemi, Kehinde D.

    2018-03-01

    Basement aquifers, which occur within the weathered and fractured zones of crystalline bedrocks, are important groundwater resources in tropical and subtropical regions. The development of basement aquifers is complex owing to their high spatial variability. Geophysical techniques are used to obtain information about the hydrologic characteristics of the weathered and fractured zones of the crystalline basement rocks, which relates to the occurrence of groundwater in the zones. The spatial distributions of these hydrologic characteristics are then used to map the spatial variability of the basement aquifers. Thus, knowledge of the spatial variability of basement aquifers is useful in siting wells and boreholes for optimal and perennial yield. Geoelectrical resistivity is one of the most widely used geophysical methods for assessing the spatial variability of the weathered and fractured zones in groundwater exploration efforts in basement complex terrains. The presented study focuses on combining vertical electrical sounding with two-dimensional (2D) geoelectrical resistivity imaging to characterise the weathered and fractured zones in a crystalline basement complex terrain in southwestern Nigeria. The basement aquifer was delineated, and the nature, extent and spatial variability of the delineated basement aquifer were assessed based on the spatial variability of the weathered and fractured zones. The study shows that a multiple-gradient array for 2D resistivity imaging is sensitive to vertical and near-surface stratigraphic features, which have hydrological implications. The integration of resistivity sounding with 2D geoelectrical resistivity imaging is efficient and enhances near-surface characterisation in basement complex terrain.

  8. Study Of Land Cover And Condition Catchment Area Groundwater Aquifer In Tanah Merah North Samarinda District Using Resistivity Geoelectric Sounding

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    Djayus

    2017-06-01

    Full Text Available Land cover is a biophysical cover that maintains land conditions in water balance. The purpose of this research is to know the condition of land cover water catchment groundwater aquifer and correlation. This research begins by collecting data on land cover soil type rainfall slopes and groundwaterinformation. Field activities include observation and data collection of land cover geological conditions community wells and geoelectric sounding. Land cover data is classified according to circumstances and conditions. Geoelectric sounding data was analyzed with IP2WIN software interpretation of lithologic variation of rocks and depth based on resistivity value. Plot the position of each lithology sounding with Surfer software obtained kontour rock field boundary and 3D model of the aquifer position.The results showed that the land cover consisted of vegetated areas forests 27221 Ha 4032 and agricultural land 18336 Ha 2716 non-vegetation area 9880 Ha 1464 constructed land Open land 116.33 Ha 17.23 and water body 4.35 Ha 0.64 The condition of land cover in this water catchment area has decreased 6838 Ha 1014 from the previous condition 34059 Ha 5046 to 27221 Ha 4032. Referring to Permenhut RI No. 32 in 2009 total score catchment area 33 including the somewhat critical condition. Groundwater aquifers based on 3D sounding geolistrik modeling consist of a free aquifer for shallow groundwater depth of water level between 2-30 m with thickness 2-65 m and a distorted aquifer for groundwaterin depth of water between 75-150 m With thickness 75-125 m depth of community well 10-45 m. The transfer of land into open pit mines resulted in the destruction of the balance and water system the decreasing decreasing the discharge of the well water of the community drill the failure and the lack of new water discharge of the new wells the loss of groundwaterin several dug wells landslides and mud floods on the farmland

  9. High frequency magnetotelluric and geoelectric researches in the Provita de Sus landslide area

    Science.gov (United States)

    Diacopolos, Constantin

    2010-05-01

    In the Provita de Sus area, high frequency magnetotelluric and geoelectric (Vertical Electric Soundings) measurements have been performed in order to delineate the landslide area. The high frequency magnetotelluric method uses the time variations of the natural electromagnetic field propagating inside the Earth and induces a secondary electromagnetic field, measured at the surface by special devices, in order to investigate the Earth's shallow electric conductivity structure. We performed these measurements aiming to point out the slide interface, as well as its the depth, and to establish the dip and strike of a relatively evident fault system from the studied area. The high frequency magnetotelluric data have been obtained in the frequency range 24 KHz - 1Hz by using a GMS 06 devices and the MAPROS software. For the geoelectric measurements we used the IntV3 resistivimeter, Schlumberger type array. This device version is designed for geophysical appliances allowing the soil resistivity measurements, under natural conditions of climate and land morphology. The field measurements led to a series of potential difference values expressed in micro V. The interpretation is based on the apparent resistivity resulting from the field measurements by using standard relation. The results highlight the usefulness of the geoelectric method for the landslide areas delineation, taking into account its user-friendliness, having all the technical facilities for measurement, processing and interpretation. The results are presented along two resistivity cross-sections, placed perpendicular and parallel to landslide surface.

  10. Spectral Characteristics of Induced Geoelectric Fields During Extreme Geomagnetic Conditions

    Science.gov (United States)

    Khanal, K.; Adhikari, B.

    2017-12-01

    The ground response to geomagnetic superstorms at high latitude region have been studied using wavelet analysis technique. Finnish Natural-Gas Pipeline is chosen as the site of study. Plane wave theory is used to estimate the geoelectric fields Ex and Ey using ground conductivity structure and the 10-sec sampled geomagnetic data as input. The validity of estimated data is also tested by using online Geoelectric Field Calculator Tool-CCMC-NASA. For all selected events, by using Morelet wavelet we have analysed the scalograms and global wavelet spectrum of the parameters and the results are compared with the prevailing S-Transform views in Geomagnetically Induced Current(GIC) studies. The induced geoelectric fields are found to possess spectral variability with different periodicities depending upon the storm phases. Further, We have used the modelled geoelectric field data to estimate Pipe to Soil Voltage at Mantsala by adopting the Distributed Source Transmission Line(DSTL) theory considering the analogy between pipeline and transmission lines. The pipeline corrosion hazard is then discussed in the light of spectral characteristics of induced geoelectric fields.

  11. The Geoelectrical Structure of Northwestern Anatolia, Turkey

    Science.gov (United States)

    Ulugergerli, E. U.; Seyitoğlu, G.; Başokur, A. T.; Kaya, C.; Dikmen, U.; Candansayar, M. E.

    2007-05-01

    The magnetotelluric method has been employed to generate a geoelectrical model that will reveal the rich geological pattern and dynamic character of western and northwestern Anatolia, Turkey. Magnetotelluric data were collected from 53 sites along a profile of 290 km from the Dardanelles to the Alaşehir Graben. Magnetotelluric data were in the range of 0.00055 Hz to 320 Hz. The models were obtained through 2-D joint inversion of transverse electric and transverse magnetic modes. Lateral changes in geoelectrical models are verified by using gravity and magnetic data. In addition, some of the seismological data presented here agree with proposed models that suggest a brittle-ductile structure boundary at a depth of 20 km. Generally speaking, a regional extensional regime caused reduction in the thickness of the crust and consequent uplift towards the south. The constructed model delineates the western part of the North Anatolian Fault Zone along the Biga Peninsula. The current patterns of volcanic activity on the Biga Peninsula and at Kula are related to conductive spots presented in the models. The border of the Gördes Basin, located between the Izmir - Ankara suture zone and the Menderes Massif, is also well delineated. The North Anatolian Fault Zone presents a pattern in which density and susceptibility anomalies attain relatively high values. Fillings covering most of the surface have lower density and susceptibility values than those of underlying structures.

  12. Smoothing of geoelectrical resistivity profiles in order to build a 3D model: A case study from an outcropping limestone block

    Science.gov (United States)

    Tóth, Krisztina; Kovács, Gábor

    2014-05-01

    Geoelectrical imaging is one of the most common survey methods in the field of shallow geophysics. In order to get information from the subsurface electric current is induced into the ground. In our summer camp organized by the Department of Geophysics and Space Sciences, Eötvös Loránd University we have carried out resistivity surveys to get more accurate information about the lithology of the Dorog basin located in the Transdanubian range, Middle Hungary. This study focused on the outcropping limestone block located next to the village Leányvár in the Dorog basin. The main aim of the research is the impoundment of the subsurface continuation of the limestone outcrop. Cable problems occurred during field survey therefore the dataset obtained by the measurement have become very noisy thus we had to gain smoothed data with the appropriate editing steps. The goal was to produce an optimized model to demonstrate the reality beneath the subsurface. In order to achieve better results from the noisy dataset we changed some parameters based on the description of the program. Whereas cable problems occurred we exterminated the bad datum points visually and statistically as well. Because of the noisiness we increased the value of the so called damping factor which is a variable parameter in the equation used by the inversion routine responsible for smoothing the data. The limitation of the range of model resistivity values based on our knowledge about geological environment was also necessary in order to avoid physically unrealistic results. The purpose of the modification was to obtain smoothed and more interpretable geoelectric profiles. The geological background combined with the explanation of the profiles gave us the approximate location of the block. In the final step of the research we created a 3D model with proper location and smoothed resistivity data included. This study was supported by the Hungarian Scientific Research Fund (OTKA NK83400) and was realized

  13. Extreme-event geoelectric hazard maps: Chapter 9

    Science.gov (United States)

    Love, Jeffrey J.; Bedrosian, Paul A.

    2018-01-01

    Maps of geoelectric amplitude covering about half the continental United States are presented that will be exceeded, on average, once per century in response to an extreme-intensity geomagnetic disturbance. These maps are constructed using an empirical parameterization of induction: convolving latitude-dependent statistical maps of extreme-value geomagnetic disturbances, obtained from decades of 1-minute magnetic observatory data, with local estimates of Earth-surface impedance obtained at discrete geographic sites from magnetotelluric surveys. Geoelectric amplitudes are estimated for geomagnetic waveforms having a 240-s (and 1200-s) sinusoidal period and amplitudes over 10 min (1 h) that exceed a once-per-century threshold. As a result of the combination of geographic differences in geomagnetic variation and Earth-surface impedance, once-per-century geoelectric amplitudes span more than two orders of magnitude and are a highly granular function of location. Specifically for north-south 240-s induction, once-per-century geoelectric amplitudes across large parts of the United States have a median value of 0.34 V/km; for east-west variation, they have a median value of 0.23 V/km. In Northern Minnesota, amplitudes exceed 14.00 V/km for north-south geomagnetic variation (23.34 V/km for east-west variation), while just over 100 km away, amplitudes are only 0.08 V/km (0.02 V/km). At some sites in the northern-central United States, once-per-century geoelectric amplitudes exceed the 2 V/km realized in Québec during the March 1989 storm.

  14. Hydrogeophysical Study Of The Groundwater Potential Of Ilara ...

    African Journals Online (AJOL)

    Geoelectric study of the groundwater potential of Ilara-Mokin in Ondo State Southwestern Nigeria was carried out using electrical resistivity (Vertical Electrical Sounding) method with the view to providing adequate information on the different sub-surface geoelectric layers, structural configuration of the concealed basement ...

  15. Geoelectrical Exploration For Groundwater In A Crystalline ...

    African Journals Online (AJOL)

    Results of the survey and the computer modeling identified a three to four layer geoelectric model. The geoelectric structure has been differentiated into possible lithological units of sandy clay, clay and sand. The fourth layer shows a high resistive unit which is indicative of fresh rock. The resistivity values and thicknesses of ...

  16. Investigation of relationships between geoelectric and Hydraulic ...

    African Journals Online (AJOL)

    Investigation of relationships between geoelectric and Hydraulic parameters in a quaternary alluvial aquifer in Yenagoa, Southern Nigeria. ... Ife Journal of Science ... Correlation of geoelectric and hydraulic parameters of the aquifer showed that the hydraulic conductivity (K) exhibited better correlation with the apparent ...

  17. Geoelectric Hazard Maps for the Mid-Atlantic United States: 100 Year Extreme Values and the 1989 Magnetic Storm

    Science.gov (United States)

    Love, Jeffrey J.; Lucas, Greg M.; Kelbert, Anna; Bedrosian, Paul A.

    2018-01-01

    Maps of extreme value geoelectric field amplitude are constructed for the Mid-Atlantic United States, a region with high population density and critically important power grid infrastructure. Geoelectric field time series for the years 1983-2014 are estimated by convolving Earth surface impedances obtained from 61 magnetotelluric survey sites across the Mid-Atlantic with historical 1 min (2 min Nyquist) measurements of geomagnetic variation obtained from a nearby observatory. Statistical models are fitted to the maximum geoelectric amplitudes occurring during magnetic storms, and extrapolations made to estimate threshold amplitudes only exceeded, on average, once per century. For the Mid-Atlantic region, 100 year geoelectric exceedance amplitudes have a range of almost 3 orders of magnitude (from 0.04 V/km at a site in southern Pennsylvania to 24.29 V/km at a site in central Virginia), and they have significant geographic granularity, all of which is due to site-to-site differences in magnetotelluric impedance. Maps of these 100 year exceedance amplitudes resemble those of the estimated geoelectric amplitudes attained during the March 1989 magnetic storm, and, in that sense, the March 1989 storm resembles what might be loosely called a "100 year" event. The geoelectric hazard maps reported here stand in stark contrast with the 100 year geoelectric benchmarks developed for the North American Electric Reliability Corporation.

  18. Estimating the Geoelectric Field Using Precomputed EMTFs: Effect of Magnetometer Cadence

    Science.gov (United States)

    Grawe, M.; Butala, M.; Makela, J. J.; Kamalabadi, F.

    2017-12-01

    Studies that make use of electromagnetic transfer functions (EMTFs) to calculate the surface electric field from a specified surface magnetic field often use historical magnetometer information for validation and comparison purposes. Depending on the data source, the magnetometer cadence is typically between 1 and 60 seconds. It is often implied that a 60 (and sometimes 10) second cadence is acceptable for purposes of geoelectric field calculation using a geophysical model. Here, we quantitatively assess this claim under different geological settings and using models of varying complexity (using uniform/1D/3D EMTFs) across several different space weather events. Conclusions are made about sampling rate sufficiency as a function of local geology and the spectral content of the surface magnetic field.

  19. An integrated geochemical and geoelectrical Investigation of an ...

    African Journals Online (AJOL)

    Ife Journal of Science ... Geochemical analysis of borehole soil samples for Total Petroleum Hydrocarbon (TPH), geoelectrical imaging and geotechnical sieve analysis were used to assess the ... Keywords: Geochemical Analysis, Geoelectric Imaging, Borehole Sampling, TPH Concentrations, Oil Spill, Contamination ...

  20. Geoelectric investigation of Awba earth dam embankment ...

    African Journals Online (AJOL)

    The dipole-dipole data were inverted into 2-D resistivity images using the DIPPRO™ 4.0 inversion software. The SP data were presented as a profile and interpreted qualitatively. Three geoelectric layers were delineated along the two traverses. These include the clay/sandy clay/laterite (cap rock) with layer resistivity and ...

  1. Geoelectric investigation of the aquifer characteristics and ...

    African Journals Online (AJOL)

    Subsurface geo-electrical survey using the electrical resistivity (VES) method and drillers logs were carried out in Kwale, Ndokwa West Local Government Area of Delta State in order to investigate the aquifer characteristics and ground water potential of the subsurface formations. Nineteen vertical electrical soundings were ...

  2. The impact of coronal mass ejection on the horizontal geomagnetic fields and the induced geoelectric fields

    Science.gov (United States)

    Falayi, E. O.; Adebesin, B. O.; Bolaji, O. S.

    2018-02-01

    This work investigates the influence of coronal mass ejection (CME) on the time derivatives of horizontal geomagnetic and geoelectric fields, proxy parameters for identifying GICs. 16 events were identified for the year 2003 from the CORONAS-PHOTON spacecraft. Five of the events (May 29, June 9, October 28, October 29, and November 4) were extensively discussed over four magnetic observatories, were analyzed using the time derivatives of the horizontal geomagnetic (dH/dt) and geoelectric (EH) fields obtained from data of the INTERMAGNET network. It was observed that energy distributions of the wavelet power spectrum of the horizontal geoelectric field are noticed at the nighttime on both 29 May and 9 June 2003 across the stations. Daytime and nighttime intensification of energy distribution of the wavelet power spectrum of the horizontal geoelectric field are observed on both 28 and 29 October 2003 due to strong westward electrojet. The 4 November 2003 event depicts daytime amplification of energy distributions of the wavelet power spectrum across the stations. The highest correlation magnitude is obtained in the event of 4 November 2003 between dH/dt and EH relationships during the intense solar flare of class X 17.4. We observed that the correlation magnitude between dH/dt and EH increases with increase in CME activity. We concluded that the response of the surface impedance model for different stations plays a key role in determining the surface electric field strength, due to large electric field changes at different stations.

  3. Geoelectrical monitoring of landslides: results from the sites of Laakirchen (Austria) and Rosano (Italy)

    Science.gov (United States)

    Guardiani, Carlotta; Amabile, Anna Sara; Jochum, Birgit; Ottowitz, David; Supper, Robert

    2017-04-01

    One of the main precursors for landslide activation/reactivation is intense and prolonged precipitation, with consequent pore water pressure rise due to infiltration of rainfall that seeps into the ground. Monitoring hydrological parameters such as precipitation, water content and pore pressure, in combination with displacement analysis for early warning purposes, is necessary to understand the triggering processes. Since the reduction over time of electrical resistivity corresponds to an increase of water content, electrical resistivity monitoring can help to interpret the modifications of slope saturation conditions after heavy rainfalls. In this study, we present the results of the ERT monitoring data from two landslide areas, Laakirchen (47.961692N, 13.809897E) and Rosano (44.662453N, 9.104703E). During March 2010, a shallow rotational landslide was triggered by snow melting and intense rainfall in Laakirchen, in the vicinity of a newly constructed house. Laakirchen landslide was monitored by geophysical/geotechnical measurements from September 2011 to June 2013. In December 2004, Rosano landslide reactivation affected rural buildings: slope deformations caused mainly damages to properties, infrastructures and lifelines. Rosano landslide has been defined as a composite landslide, with a general dynamic behavior that can be regarded as a slow earthflow. The installation of the monitoring system took place in July 2012 and the data acquisition lasted until April 2015. These sites are part of the geoelectrical monitoring network set up by the Geological Survey of Austria for testing the self-developed GEOMON4D geoelectrical system, in combination with complementary geotechnical monitoring sensors (rain gauge, automatic inclinometer, water pressure and water content sensors) to support the interpretation of the electrical response of the near surface (R. Supper et al., 2014). The measurements were funded by the TEMPEL project (Austrian Science Fund, TRP 175-N21

  4. Broadband Geoelectrical Signatures of Water-Ethanol Solutions in Ottawa Sand

    Science.gov (United States)

    Henderson, R.; Werkema, D. D.; Horton, R.; Lane, J. W.

    2009-12-01

    Ethanol has fast become the most widely used and distributed biofuel since its introduction as a fuel oxygenate to replace MTBE in gasoline and the emergence of “Flex Fuel” vehicles. Where ethanol is included in gasoline as a fuel oxygenate, subsurface releases have resulted in increased solubility and the transport of harmful BTEX compounds. In the case of "neat ethanol" (pure or slightly denatured) spills, large quantities of ethanol may initially reduce microbial populations, exacerbate pre-existing subsurface contamination in soil and groundwater, and potentially form explosive conditions through methanogenesis. There is a growing need for rapid assessment of subsurface releases to allow for quick remedial action following such releases. Surface and borehole geophysical measurements could provide rapid results to assess the extent of a release; however, little work has been done to understand the signature of ethanol in the subsurface. Here, we measure the broadband geoelectrical signature of various ethanol-water mixtures in a matrix of Ottawa sand to determine select geoelectrical parameters which may be applied in field scale studies. In the lower frequency range (Hz to kHz), resistivity and induced polarization parameters were measured and compared to the well known Cole-Cole model. At high frequencies (MHz to GHz), the dielectric constant of several ethanol-water solutions was measured. We use the empirical complex refractive index model (CRIM) to compare measured and predicted values of the dielectric constant. The low frequency electrical resistivity ranged from approximately 570 ohm-m (water in sand) to approximately 2300 ohm-m (pure ethanol in sand). The dielectric constant ranged from approximately 17.8 (water in sand) to 9.2 (pure ethanol in sand). Work is ongoing to determine induced polarization parameters. These initial results, however, suggest that geoelectrical field measurements would be useful to delineate an ethanol release in the

  5. Improving distribution efficiency of electrical network using geo-electrical options. A case study in a rural area of Assam (India)

    Energy Technology Data Exchange (ETDEWEB)

    Hazarika, S.; Hiloidhari, M.; Baruah, D.C. [Energy Conservation Laboratory, Department of Energy, Tezpur University, Tezpur, Assam (India)

    2012-11-15

    Reduction of electricity distribution loss is a major area of focus in India. This paper aims to investigate geo-electrical options to improve distribution efficiency of electrical network. Distribution efficiencies corresponding to several possible electrical network options are assessed using Geographical Information System (GIS) integrated electrical theory. An existing electrical distribution network of a rural area in Assam (India) is considered for the present investigation. Information related to characteristics of loads, features of conductors, and transformers of the existing network are used for this investigation. The line losses of the three existing transformers are estimated at about 36, 20, and 3 % of their respective connected loads. Longer distribution lines associated with higher loads are the causes of higher line losses. Using basic electrical theory and GIS tools, it is found that line losses can be reduced in the existing distribution system through management of distribution transformer and reconductoring. Two alternative locations for each of the three transformers are identified for optimal management of distribution transformers. Similarly, five different types of commercially available conductors are identified for possible reconductoring to reduce line loss. The economic viability of reconductoring of distribution lines are also assessed through an economic analysis. Net present values of total expenditure comprising purchase prices of conductor and cost attributed to line losses are estimated considering 30 years of useful life. The existing conductor has the worst economic merit, though it is the cheapest amongst all. A net saving of about USD 24,084 is possible through the best choice of distribution conductor for the village.

  6. Geoelectric monitoring of the Bagnaschino landslide (Italy)

    Science.gov (United States)

    Jochum, Birgit; Supper, Robert; Ottowitz, David; Pfeiler, Stefan; Kim, Jung-Ho; Lovisolo, Mario

    2013-04-01

    Landslides are one of the major natural threats to human lives, settlements and infrastructure. Permanent geoelectrical monitoring using the GEOMON4D instrumentation in combination with high resolution displacement monitoring by means of the DMS system was performed at an active landslide area in Italy (Bagnaschino). These sites are part of a geoelectrical monitoring network of the Geological Survey of Austria, which currently comprises six permanently monitored landslides in Europe. The Bagnaschino site represents a landslide/earthflow reactivated within an old landslide mass. The old landslide is situated on the slopes of the Val Casotto about 4 km SE of Torre Mondovì (NW Italy). Evident indications of deep-seated gravitational deformation suggest that the current slopes are in a condition of limit-equilibrium and are predisposed to slow instability, triggered most probably by rain and/or snow melting and river erosion at the foot. The recent landslide was activated during 1994 rainfall event. It covers an estimated area of 150,000 m² and comprises a displaced material of 1.2 million m³. It endangers a regional road and potential formation of a dam. For the purpose of early warning a DMS monitoring column with 60 m length was installed in October 2008. Total displacement recorded by DMS during the events between 2008 and 2010 was 600 mm. Subsequently, the GEOMON4D geoelectric monitoring system was installed there in 2010. Resistivity measurements are performed along a 224 m long profile, which is oriented parallel to the main movement direction. Its midpoint is next to the DMS station. One set of data comprising around 4000 gradient-type measurements is taken every 4 hours. For power supply a combination of a fuel cell and a solar panel is used. Within the observation interval one distinct displacement event was monitored. This event was accompanied by a decrease of electric resistivity. In addition to our standard analysis of resistivity data (e.g. time

  7. An Approach to Model Earth Conductivity Structures with Lateral Changes for Calculating Induced Currents and Geoelectric Fields during Geomagnetic Disturbances

    Directory of Open Access Journals (Sweden)

    Bo Dong

    2015-01-01

    Full Text Available During geomagnetic disturbances, the telluric currents which are driven by the induced electric fields will flow in conductive Earth. An approach to model the Earth conductivity structures with lateral conductivity changes for calculating geoelectric fields is presented in this paper. Numerical results, which are obtained by the Finite Element Method (FEM with a planar grid in two-dimensional modelling and a solid grid in three-dimensional modelling, are compared, and the flow of induced telluric currents in different conductivity regions is demonstrated. Then a three-dimensional conductivity structure is modelled and the induced currents in different depths and the geoelectric field at the Earth’s surface are shown. The geovoltages by integrating the geoelectric field along specific paths can be obtained, which are very important regarding calculations of geomagnetically induced currents (GIC in ground-based technical networks, such as power systems.

  8. Geoelectric structure estimated from magnetotelluric data from the ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 123; Issue 8. Geoelectric structure estimated from ... Geoelectric strike and resistivity structure of the crust have been estimated from 37 magnetotelluric (MT) data sites along a profile from Roorkee to Gangotri in Uttarakhand Himalaya. Impedance decomposition ...

  9. Geochemical and geo-electrical study of mud pools at the Mutnovsky volcano (South Kamchatka, Russia): Behavior of elements, structures of feeding channels and a model of origin

    International Nuclear Information System (INIS)

    Bessonova, E.P.; Bortnikova, S.B.; Gora, M.P.; Manstein, Yu.A.; Shevko, A.Ya.; Panin, G.L.; Manstein, A.K.

    2012-01-01

    This study presents data on the geochemical composition of boiling mud pools at the Mutnovsky volcano. The physicochemical characteristics of the pools and the concentrations of major, minor and trace elements in pool solutions vary widely. A comparison of the geochemical compositions of host rocks and solutions indicates that leaching from rocks is not the only source of chemicals in thermal solutions. Geophysical studies reveal the inner structure of thermal fields, which reflect the shapes of the underground reservoirs and feed channels. Using geophysical methods (electrical resistivity tomography and frequency domain investigations), it was shown that the vertical structure and complex geochemical zonation of the feed channels leads to a high contrast in the compositions of the mud solutions. These findings answer questions about the origin and composition of surface manifestations. To elucidate the mechanisms of solution formation, an attempt was made to describe the magmatic fluid evolution and the resulting mixing of waters by physical and mathematical models. The model illustrates fluid migration from a magma chamber to the surface. It is shown that the formation of brines corresponding to the mud pool composition is possible during secondary boiling.

  10. Quasi 3D Geoelectrical Imaging as a new application for permafrost investigations: Some methodological aspects

    Science.gov (United States)

    Bast, A.; Kneisel, C.

    2009-04-01

    The two-dimensional electrical resistivity tomography (ERT) application is a common tool to investigate periglacial environments and has evolved rapidly over the last years. The method has been often applied with great success in mountainous systems even though they are characterized by a complex heterogeonous and rough terrain. Despite the development of advanced instrumentation and commercial three-dimensional processing software, in general the two-dimensional approach is used. True three-dimensional measurements in high mountain environments are difficult to realize due to the rough and complex domain. However, up to now, an efficient three-dimensional geophysical mapping of the subsurface characteristics and lithology in alpine environments has not been possible. An auspicious approach is to sound the subsurface with two-dimensional measurements, each of them is routinely being interpreted with commercial software packages and then the results are merged to generate a quasi or pseudo three-dimensional geoelectrical image of the subsurface. Our study presents first results of two quasi 3D geoelectrical images, located in the Val Muragl glacier forefield, Upper Engadin, Swiss Alps. The site of the first model is in the lower part of the forefield the second in the upper part. They distinguish between the surface material: While the lower part is characterized by coarse blocky but although finer grained surface material, the upper site consists of much more finer grained substrate. At both sites a permanently geoelectrical monitoring survey-line is installed, as well as a borehole, which was drilled in summer of 2006 and extent to a depth of 8m below ground surface. Furthermore, miniature temperature logger, BTS (bottom temperature of snow cover) and seismic refraction data are available for the glacier forefield. Data acquisition has been undertaken with a multi-electrode Iris Syscal Junior Switch equipment, data processing with different commercial software

  11. Geomagnetic and geoelectrical prospection for buried archaeological remains on the Upper City of Amorium, a Byzantine city in midwestern Turkey

    International Nuclear Information System (INIS)

    Ekinci, Yunus Levent; Balkaya, Çağlayan; Şeren, Aysel; Kaya, Mehmet Ali; Lightfoot, Christopher Sherwin

    2014-01-01

    On the basis of geophysical imaging surveys, including geomagnetic and geoelectrical resistivity, possible archaeological remains and their spatial parameters (i.e., location, extension, depth and thickness) were explored to provide useful data for future excavations on the Upper City of the ancient Amorium site, which comprises a large prehistoric man-made mound. The surveys were performed very close to the main axis of the Basilica, and the derived geophysical traces indicated some subsurface structures that appear to confirm that more-substantial brick and masonry buildings lie near the present-day surface of the mound. Analyzing the local gradients by total horizontal derivatives of pseudogravity data enhanced the edges of the magnetic sources. Additionally, a profile curvature technique, which has rarely been applied to potential field data sets, dramatically improved the magnetic-source body edges and the lineaments that may be associated with buried archaeological remains. The depths of these possible anthropogenic remains were estimated by applying the Euler deconvolution technique to the geomagnetic data set. The Euler solutions on tentative indices indicated that the depths of the source bodies are not more than about 3 m. Moreover, geoelectrical resistivity depth slices produced from the results of two- and three-dimensional linearized least-squares inversion techniques revealed high-resistivity anomalies within a depth of about 3 m from the ground surface, which is in close agreement with those obtained by applying the Euler deconvolution technique to the magnetic data. Based on the existence of some archaeological remains in the vicinity of the surveyed area, these geophysical anomalies were thought to be the possible traces of the buried remains and were suggested as targets for excavations. This study also emphasized that the data-processing techniques applied in this investigation should be suitable for providing an insight into the layout of the

  12. The thermo-electric effect of magnetite and the mechanism of geo-electric abnormalities during earthquakes

    Directory of Open Access Journals (Sweden)

    Junfeng Shen

    2010-10-01

    Full Text Available The thermo-electric coefficients of twenty-six magnetite samples, formed either by magmatism or metamorphism, were tested by the thermo-electric instrument BHET –06. Results showed that the coefficient is of a constant value of about −0.05 mV/°C. It is emphasized that because every magnetite grain was tested randomly, the coefficient is independent of the crystallographic direction. This fact means the thermal voltage generated from a single magnetite crystal can be accumulated, and as a result a new thermo-electric field can arise when a gradient thermal field exists and is active within the earth’s crust. Because magnetite is widespread in the earth’s crust (generally appearing more in the middle-lower crust, there is more-than-random probability that the additional thermo-electric field can be generated when certain thermal conditions are fulfilled. We, therefore, used the thermo-electric effect of magnetite to study the mechanism responsible for the presence of abnormal geo-electric fields during earthquake formation and occurrence, because gradient thermal fields always exist before earthquakes. The possible presence of additional thermo-electric fields was calculated under theoretical seismological conditions, using the following calculation formula:E=−0.159(σ×ΔT×Φ×ρ2×[(h2−2x2cosα+3hxsinα]/ρ1(h2+x25/2. In the above formula, σ is thermo-electric coefficient of magnetite, ΔT is the temperature difference acting on it, Φ is a sectional area on a block of magnetite vertically perpendicular to the direction of the thermal current, ρ1 and ρ2 are the respective resistivities of magnetite and the crust, and h, α, and x, respectively, h is the depth of embedded magnetite block. α means the angle created by the horizontal line and ligature of the two poles of magnetite block, and x is the distance from observation point to projective center point of the magnetite block on earth surface. According to simulations

  13. Fast representation of dipole-dipole geoelectrical data with pseudosections for regional surveys

    Directory of Open Access Journals (Sweden)

    M. Giudici

    2000-06-01

    Full Text Available I propose a fast method for constructing pseudosections of apparent resistivity from geoelectrical data collected for deep studies with continuous polar dipole-dipole arrays. Once a vertical section is fixed, each value of apparent resistivity is assigned to a point on the section and finally pseudosections are obtained by interpolation. This allows the geophysicist to represent a large amount of data in a fast and simple way, to perform a qualitative interpretation and to facilitate the quantitative interpretation.

  14. Geoelectrical contribution for delineation the groundwater potential and subsurface structures on Tushka Area, Egypt

    Science.gov (United States)

    Abd El-Gawad, A. M. S.; Kotb, Adel D. M.; Hussien, Galal H. G.

    2017-12-01

    Tushka area represents the South East Western Desert, Egypt. its contain many drilled wells which have many problems during use, so the present study aims at identify the aquifer conditions and its relation with surface water and subsurface structure in addition to determine the aquifer thickness by using the basement relief from previous work, then assess the current situation of the drilled water wells. Geoelectrical data were measured, processed and interpreted in one, two and three dimensions using special Equipments and software. The interpretation results demonstrated that two types of groundwater aquifers (confined and unconfined) are present in the study area. The confined aquifer is located at the south of Khor Tushka and the unconfined aquifer is found in the north of Khor Tushka, where the last one is charged from Lake Nasser and Khor Tushka. The groundwater aquifers thicknesses are up to 440 m and the area is affected by normal faults of NW-SE and NE-SW trends. The study showed that there is no connection between the confined aquifer and the shallow overlaying aquifer. The confined aquifer is charged partially from the lake Nasser and Khor Tushka through specific areas under the capping layers of Nubian sandstone filled with hydrothermal solution and shale.

  15. Long Term Geoelectrical Monitoring of Deep-water Horizon Oil Spill in the Gulf Coast

    Science.gov (United States)

    Heenan, J. W.; Ntarlagiannis, D.; Slater, L. D.; Atekwana, E. A.; Ross, C.; Nolan, J. T.; Atekwana, E. A.

    2011-12-01

    In the aftermath of the catastrophic Deep-water Horizon (DWH) spill in the Gulf Coast, opportunities exist to study the evolution of fresh crude oil contamination in beach sediments and marshes. Grand Terre 1 Island, off the coast of Grand Isle in southern Louisiana, is an uninhabited barrier island, heavily impacted by the DWH spill, and ideal for undisturbed long term monitoring of crude oil degradation processes. A 10 channel Syscal-Pro resistivity / IP instrument (IRIS Instruments, France) is the heart of the fully autonomous geoelectrical monitoring system; the system, which is housed in a weatherproof container, relies solely on solar power, is controlled by an energy efficient PC and can be accessed remotely via web tools. The monitoring scheme involves collecting bi-daily resistivity measurements from surface and shallow boreholes, ranging from January 2011 to the present; environmental parameters, such as T, are continuously recorded at several depths. During regular field trips we perform larger scale geophysical surveys, and geochemical measurements (pH, DO, T, fluid C) to support the continuous geophysical monitoring. The contaminated layer on site is a visually distinctive layer of crude oil, isolated by cleaner sands above and below which is identified by a clear and obvious resistive anomaly in preliminary surveys. Early results show a decrease in average of the resistance values of each dataset over time. Further processing of the data yields a linearly shaped resistive anomaly, which coincides with the location of the oil layer. The changes in subsurface resistivity appear to be focused within this anomaly. Time filtering of the data by the time that they were collected, morning or evening, reveals a diurnal variation. While both time frames follow the same overall trend, the measurements in the morning are slightly more resistive than those in the evening. This indicates that there are environmental factors, such as temperature, that need to be

  16. Ancient volcanic rocks identification the Western part of Yogyakarta Southern mountains based on geoelectrical measurement

    International Nuclear Information System (INIS)

    Winarti; Hill Gendoet Hartono

    2015-01-01

    The study area is located between western part of Yogyakarta plains and Southern Mountains. The morphology and lithology along the Berbah-Imogiri show the existence of an ancient volcano. This is proven by outcrop of volcanic rock like lava, breccia and tuff. The aim of this study is to identify the existence of ancient volcanic rocks along Berbah-Imogiri based on geoelectrical data. The method used to perform measurements at four locations geoelectrical mapping with dipole-dipole configuration a long stretch of track for every 500 meters. Geoelectrical measurement results showed on track 1 in Source Kulon-Kalitirto, District Berbah, interpreted as volcanic rocks such as basalt lava and tuff. Tracks 2 in Pilang-Srimulyo, District Piyungan, interpreted as volcanic rocks of scoria breccia. Tracks 3 in Ngeblak-Bawuran, District Pleret, interpreted as lava and tuff. And track 4 on Guyangan-Wonolelo, District Pleret interpreted as form of tuff and lava. Volcanic rocks are generally having a high resistivity value > 300 Ωm. The content of water or mineralization tends to reduce the resistivity value of resistant volcanic rock. (author)

  17. Anomalous geoelectrical and geomagnetic signals observed at Southern Boso Peninsula, Japan

    Directory of Open Access Journals (Sweden)

    C. Yoshino

    2007-06-01

    Full Text Available Geoelectrical and geomagnetic fluctuations are considered the end product of several geophysical phenomena. In particular these signals measured in seismically active areas can be attributed to stress and strain changes associated with earthquakes. The complexity of this problem has suggested the development of advanced sophysticated methods to investigate the heterogeneous nature of these fluctuations. In this paper, we analyzed the time dynamics of short-term variability of geoelectrical potential differences and geomagnetic fields obsereved at Kiyosumi (KYS, Uchiura (UCU, and Fudago (FDG stations, located in the southern part of Boso Peninsula, one of the most seismically active areas in Japan. Anomalous changes in electric and magnetic fields are obeserved in mid-night on October 6, 2002. the anomalous signals observed on October 6, 2002 are different from those originated from the train and other cultural noises according to the investigation on preferred directions of geoelectric field. The investigation of simaltaneous geomagnetic field changes suggest that the source of the electromagnetic change might be generated by underground current because of the polarity pattern oberved at KYS, UCU and FDG. Therefore, electrokinetic assumption under the ground seems one of the possible solutions for the generation of anomalous signals. It is important to understand the ULF electromagnetic environment for the study on the preparation process of crustal activity and systematic understanding both electromagnetic and seismic phenomena.

  18. Application of geoelectrical profiling in the delineation of shallow periglacial structures on the Drohiczyn Plateau

    Directory of Open Access Journals (Sweden)

    Mieszkowski Radosław

    2014-12-01

    Full Text Available The paper describes the results of geoelectrical sounding application for delineation of periglacial structures in Wierzchuca Nagórna within the Drohiczyn Plateau (eastern Poland. The method records the variation of apparent resistivity of deposits along a selected horizontal direction. The survey utilizes a distinct geoelectrical contrast between a glacial till and structures composed of sand that have been recognized earlier in a gravel pit wall. The studies have been conducted in direct hinterland of the gravel pit. Rectangular and concentric arrays were applied in the survey. The results have been presented as graphs and resistance distribution maps. The obtained geological image is not complete, although it shows an oriented course of the largest lineaments and traces of a network with a small mesh size (1.5-2 m. The recognized pattern of structures points to harsh climatic conditions during their formation. General orientation of the structures corresponds to the basic elements of the contemporary landscape in the area (slope, valley axes. Geoelectrical sounding using the rectangular array gave better results than in the concentric array, whereas introduction of brine into the system did not enhance the resolution of the readings. The presented resistance distribution maps with a characteristic rhythm of variations may serve as a benchmark for recognizing periglacial structures in areas without exposures.

  19. Coupled Interpretation of Geoelectrical Surveying Results in Environmental Site Investigations

    Science.gov (United States)

    Skold, M.; Hubbard, S. S.; Karaoulis, M.; Revil, A.; Spycher, N.; Watson, D. B.; Wu, Y.

    2011-12-01

    Geoelectric methods are sensitive to material properties which can be used to investigate subsurficial processes at contaminated sites. Electrical resistivity tomography (ERT) measures the electrical resistivity distribution in the ground; the self-potential (SP) method is based on source current densities resulting from ground water flow; and induced polarization (IP) responds to geochemical interactions between mineral surfaces and pore fluids. Ground water flow patterns and contaminant migration may be better understood if the results of these survey methods are interpreted jointly rather than separately. The purpose of this project is to jointly interpret results of geophysical surveying and laboratory characterization of soil and ground water samples to assess ground water flow patterns and contaminant migration at a site within the Oak Ridge National Laboratory. Historical disposal of liquid waste containing nitric acid and uranium in unlined ponds has resulted in contamination of soil and ground water. ERT, SP, and IP surveying was performed downgradient of the source area and the geophysical behavior of sediment and ground water samples was investigated in the laboratory. Measured electrical conductivity and self-potential anomalies coincided with elevated nitrate and uranium concentrations indicating preferential flow from the source area. The self-potential response can be related to ground water flow either by calculating the excess of charge in the diffuse layer surrounding mineral surfaces or by the streaming potential coupling coefficient. Geochemical reactions between pore water and minerals and their surfaces were modeled using the contaminant transport software TOUGHREACT. Surface complexation modeling using the Gouy-Chapman diffuse double layer was used to simulate charge density-surface potential relationship. Laboratory measurements of the streaming potential coupling coefficient of sediment samples at various pH and salt concentrations were

  20. A geoelectrical survey above an Antarctic ice shelf

    Directory of Open Access Journals (Sweden)

    M. Pavan

    1998-06-01

    Full Text Available A geoelectrical survey was performed on the Hells Gate ice shelf (Victoria Land-Antarctic within the framework of an integrated geophysical and glaciological research program. The resistivity profiles show a similar trend, with resistivity values ranging from about 25000 W · m to 500000 W · m. These results have been interpreted as the effect of a sharp transition from "marine ice" to "continental" ice an interpretation that is consistent with the results of surface mapping. Interpreting the Vertical Electrical Soundings (VES is a complex process. In fact, the alternating layers of ice with different compositions and salt content generate great uncertainty relative to the corresponding electric stratigraphies. To solve these problems of equivalency, all the available constraints were used including the drilling thickness, seismic reflection profiles as well as radar profiles. The results were used to provide what is mainly a qualitative overview that is coherent with the glaciological hypotheses relative to the evolution and structure proposed by some researchers for this ice shelf.

  1. Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Day-Lewis, Frederick David [US Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John W. [US Geological Survey, Storrs, CT (United States)

    2014-11-25

    Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3

  2. Geoelectric study in attempt to detect of deformation around slice gate in the embankment; Hiteiko eizoho wo mochiita himon shuhen no yurumi ryoiki no suitei

    Energy Technology Data Exchange (ETDEWEB)

    Natori, T.; Nakayama, Y. [Hokkaido Sapporo Public Works Office, Sapporo (Japan); Hashimoto, Y.; Matsuo, J. [OYO Corp., Tokyo (Japan)

    1997-10-22

    For the river structures, such as slice gates and slice pipes, constructed on the weak ground, structures often come out due to forced settlement of embankment, which results in the formation of cavity and loose ground. These deformations can cause disasters due to leakage by water channel and fracture of bank. It is significant to detect and grasp these situations in early stage. In this study, resistivity imaging was conducted around slice gate in several times, to estimate the loose region based on the difference in the obtained resistivity data. Resistivity was measured in two times with a certain interval using the same line. The loose region around the slice gate was estimated from the change of saturation condition and the saturation line by considering the difference. Even in the case when judgment was hard by a single measurement, it was possible to estimate the loose region based on the difference from multiple measurements. 3 refs., 6 figs.

  3. A study of building the hydrogeological apparent model with geoelectrical measurements for the Chia-Nan Coastal Plain of SW Taiwan

    Science.gov (United States)

    Chang, P. Y.; Tsai, J. P.; Chang, L. C.

    2016-12-01

    In the study we used the resistivity measurements collected in the Chia-Nan coastal plain of SW Taiwan to establish a three-dimensional (3D) hydrogeological apparent model. The resistivity measurements include data from half-Schlumberger surveys conducted during the year of 1990-2000 across the entire area and from the recent two-dimensional resistivity surveys for characterizing the recharge zone boundaries. Core records from monitoring wells in the area were used for the training data to help determining the resistivity ranges of the gavel, sand, and muddy sediments in the coastal plain. These resistivity measurements were inverted and converted into 1-D data form and interpolated for rendering a three dimensional resistivity volume that represents the general resistivity distribution in the coastal-plain systems. In addition we used water resistivity data from the observation wells to calculating the formation factors (FI) and to render the FI model. We then compared the FIs with indexed core records near some of the resistivity surveys sites, and concluded the range of the FIs for different materials in a statistical sense. Lastly we transfer the FI model into the gravel-sand-clay apparent model with the classification criteria from previous petrophysical analysis. Because there are more resistivity measurements than the limited geological boreholes, the apparent model is better to represent the detailed sedimentary structures than the traditional over-simplified conceptual models.

  4. Mirror reactor surface study

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A. L.; Damm, C. C.; Futch, A. H.; Hiskes, J. R.; Meisenheimer, R. G.; Moir, R. W.; Simonen, T. C.; Stallard, B. W.; Taylor, C. E.

    1976-09-01

    A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included.

  5. Mirror reactor surface study

    International Nuclear Information System (INIS)

    Hunt, A.L.; Damm, C.C.; Futch, A.H.; Hiskes, J.R.; Meisenheimer, R.G.; Moir, R.W.; Simonen, T.C.; Stallard, B.W.; Taylor, C.E.

    1976-01-01

    A general survey is presented of surface-related phenomena associated with the following mirror reactor elements: plasma first wall, ion sources, neutral beams, director converters, vacuum systems, and plasma diagnostics. A discussion of surface phenomena in possible abnormal reactor operation is included. Several studies which appear to merit immediate attention and which are essential to the development of mirror reactors are abstracted from the list of recommended areas for surface work. The appendix contains a discussion of the fundamentals of particle/surface interactions. The interactions surveyed are backscattering, thermal desorption, sputtering, diffusion, particle ranges in solids, and surface spectroscopic methods. A bibliography lists references in a number of categories pertinent to mirror reactors. Several complete published and unpublished reports on surface aspects of current mirror plasma experiments and reactor developments are also included

  6. Some Results of Geoelectrical Sounding for Aquifer Determination ...

    African Journals Online (AJOL)

    Three (3) vertical electrical sounding located at Agbor, Issele-Mkpitime and Ogwashi-Uku were conducted using the Schlumberger electrode configuration while the true depths and resistivity values were also determined by curve matching and iterative processing techniques. Five geoelectrical layers charactrerized Agbor ...

  7. Geoelectrical Imaging for Shallow Site Investigation at Ekiugbo in ...

    African Journals Online (AJOL)

    ADOWIE PERE

    ABSTRACT A geoelectrical imaging survey was conducted at Ekiugbo in Uhunmwode Local Government Area of ... Using linear approximations, it can be ... oldest and most commonly used geophysical methods and measures the variation of electrical resistivity in the subsurface (Dahlin, 2001). The ERT technique.

  8. Geo-Electric and Hydrogeochemical Mapping of Quaternary ...

    African Journals Online (AJOL)

    Michael Horsfall

    Geo-Electric and Hydrogeochemical Mapping of Quaternary Deposits at Orerokpe in the Western Niger Delta .... An Ertec model GPS instrument was used to position the wells as well as determine the approximate elevation of each well head. A contouring computer package was employed in generating the depth to water ...

  9. Temporal geoelectric behaviour of dyke aquifers in northern Deccan ...

    Indian Academy of Sciences (India)

    Longitudinal geoelectrical sections along these dykes demonstrated carrier as well as barrier stretches which identified potential .... static water levels in all the wells vary from 6–12 m bgl during pre-monsoon, whereas the water lev- ..... Jarvis A, Reuter H I, Nelson A and Guevara E 2006. Hole-filled seamless SRTM data V3; ...

  10. Statistical Analysis of Geo-electric Imaging and Geotechnical Test ...

    Indian Academy of Sciences (India)

    12

    assessment of influencing factors is important. Here, we present a multiple regression analyses of both geoelectric (Electrical Resistivity. Tomography, ERT, Induced Polarization Imaging, IPI) and geotechnical site investigations. (Standard Penetration Test, SPT) for two profiles at a construction site for CGEWHO Complex.

  11. Anomaly effects of arrays for 3d geoelectrical resistivity imaging ...

    African Journals Online (AJOL)

    user

    The effectiveness of using a net of orthogonal or parallel sets of two-dimensional (2D) profiles for three- dimensional (3D) geoelectrical resistivity imaging has been evaluated. A series of 2D apparent resistivity data were generated over two synthetic models which represent geological or environmental conditions for a ...

  12. Geoelectric structure estimated from magnetotelluric data from the ...

    Indian Academy of Sciences (India)

    Geoelectric strike and resistivity structure of the crust have been estimated from 37 magnetotelluric (MT) data sites along a profile from Roorkee to Gangotri in Uttarakhand Himalaya. Impedance decomposition schemes based on Bahr's, Groom Bailey and Phase tensor were implemented in a MATLAB code for the average ...

  13. Geoelectric characterization of Aquifer types in the basement ...

    African Journals Online (AJOL)

    Geoelectric characterization of Aquifer types in the basement complex terrain of parts of Osun state,Nigeria. S Bayode, JS Ojo, MO Olorunfemi. Abstract. No Abstract. Global Journal of Pure and Applied Sciences Vol. 12(3) 2006: 377-385. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT ...

  14. Anomaly effects of arrays for 3d geoelectrical resistivity imaging ...

    African Journals Online (AJOL)

    The effectiveness of using a net of orthogonal or parallel sets of two-dimensional (2D) profiles for threedimensional (3D) geoelectrical resistivity imaging has been evaluated. A series of 2D apparent resistivity data were generated over two synthetic models which represent geological or environmental conditions for a typical ...

  15. Permanent geoelectrical and temperature monitoring in the permafrost region Magnetköpfl, Salzburg

    Science.gov (United States)

    Ottowitz, D.; Jochum, B.; Supper, R.; Keuschnig, M.; Hartmeyer, I.

    2012-04-01

    Changes of climate parameters due to global warming generate increased permafrost warming and deglaciation in alpine regions. In the area of interest scientists observe increasing rock instability due to the disappearance of the permafrost inside the Magnetköpfl, a peak below the Kitzsteinhorn (3203 m a.m.s.l), as well as the decrease of glacier hight followed by a lack of counterpressure at the flanks of the slope. As a result, slabs of rock fall onto the year-round ski slope during the warmer season. Geoelectric measurements are an adequate method to measure permafrost, since the underground electric resistivity is highly dependent on temperature. The GEOMON4D, an autonomous geoelectric monitoring system, developed by the Geological Survey of Austria, equipped with 80 electrodes and powered by a fuel cell, was installed for testing reasons in the year 2007 on Sonnblick and 2010 on Mölltaler Glacier. In 2011 the system was moved to the Magnetköpfl. The results of the active site show, that the resistivities are much higher than at the Mölltaler Glacier, which was about 200 m lower and contained no permafrost. Although the GEOMON4D is adapted for very high subsurface electrical resistivities with a constant current source we still approach the 10 V at the input channel with an injected current in the range of µA. Resistivity ranges at the Magnetköpfl from 104-108 Ohmm. By the end of December we covered the interesting period of the freezing process by measuring increased resistivity in the first 3 m below surface. Since the soil temperature is highly dependent on various parameters (e.g. location, slope angle, lithology) it is necessary to have on site soil temperatures for a more reliable interpretation of the resistivity data. The geoelectric measurements are accompanied by various soil temperature sensors in several depths on and around the Magnetköpfl. The recording of the soil temperature is conducted in the framework of the MOREXPERT project by the

  16. Tracing of the defunct Canopic Nile branch using geoelectrical resistivity data around Itay El-Baroud area, Nile Delta, Egypt

    Science.gov (United States)

    El-Qady, G.; Shaaban, H.; El-Said, A.; Ghazala, H.; El-Shahat, A.

    2011-03-01

    Around the Nile Delta Branches, ancient settlements had been created and left their remains to be good witness for the paleoenvironment during the Holocene time. Therefore, tracing of the defunct Canopic branch and its distributaries as well as associated environments are of great importance. Using a Schlumberger electrode configuration, well-distributed 44 vertical electrical resistivity soundings were acquired. The 1D modelling technique was applied to estimate the depth and the apparent resistivity of the interpreted geoelectrical units. Then 2D inversion was applied for the same data set using the ABIC least-squares inversion scheme. The geoelectrical cross-sections and slice maps discriminate the Upper Quaternary sequence into three geoelectrical units. The Holocene Nile mud is represented by two units: the agricultural root zone (unit 1) that is underlain by relatively thick water-saturated mud (unit 2). The Upper Pleistocene sandy aquifer is represented by irregular surface (unit 3). Two generations of defunct channels were traced out. The older channels are characterized by low sinuosity compared with younger channels. This is probably attributed to river activity due to relatively low sea level and much higher Nile discharge. The system of younger channels is characterized by broad meanders, probably as a consequence of sea-level rise and decreased gradient since the Middle Holocene.

  17. Regional 3-D Modeling of Ground Geoelectric Field for the Northeast United States due to Realistic Geomagnetic Disturbances

    Science.gov (United States)

    Ivannikova, E.; Kruglyakov, M.; Kuvshinov, A. V.; Rastaetter, L.; Pulkkinen, A. A.; Ngwira, C. M.

    2017-12-01

    During extreme space weather events electric currents in the Earth's magnetosphere and ionosphere experience large variations, which leads to dramatic intensification of the fluctuating magnetic field at the surface of the Earth. According to Faraday's law of induction, the fluctuating geomagnetic field in turn induces electric field that generates harmful currents (so-called "geomagnetically induced currents"; GICs) in grounded technological systems. Understanding (via modeling) of the spatio-temporal evolution of the geoelectric field during enhanced geomagnetic activity is a key consideration in estimating the hazard to technological systems from space weather. We present the results of ground geoelectric field modeling for the Northeast United States, which is performed with the use of our novel numerical tool based on integral equation approach. The tool exploits realistic regional three-dimensional (3-D) models of the Earth's electrical conductivity and realistic global models of the spatio-temporal evolution of the magnetospheric and ionospheric current systems responsible for geomagnetic disturbances. We also explore in detail the manifestation of the coastal effect (anomalous intensification of the geoelectric field near the coasts) in this region.

  18. Tracing of the defunct Canopic Nile branch using geoelectrical resistivity data around Itay El-Baroud area, Nile Delta, Egypt

    International Nuclear Information System (INIS)

    El-Qady, G; Shaaban, H; El-Said, A; Ghazala, H; El-Shahat, A

    2011-01-01

    Around the Nile Delta Branches, ancient settlements had been created and left their remains to be good witness for the paleoenvironment during the Holocene time. Therefore, tracing of the defunct Canopic branch and its distributaries as well as associated environments are of great importance. Using a Schlumberger electrode configuration, well-distributed 44 vertical electrical resistivity soundings were acquired. The 1D modelling technique was applied to estimate the depth and the apparent resistivity of the interpreted geoelectrical units. Then 2D inversion was applied for the same data set using the ABIC least-squares inversion scheme. The geoelectrical cross-sections and slice maps discriminate the Upper Quaternary sequence into three geoelectrical units. The Holocene Nile mud is represented by two units: the agricultural root zone (unit 1) that is underlain by relatively thick water-saturated mud (unit 2). The Upper Pleistocene sandy aquifer is represented by irregular surface (unit 3). Two generations of defunct channels were traced out. The older channels are characterized by low sinuosity compared with younger channels. This is probably attributed to river activity due to relatively low sea level and much higher Nile discharge. The system of younger channels is characterized by broad meanders, probably as a consequence of sea-level rise and decreased gradient since the Middle Holocene

  19. Iron ore deposits model using geoelectrical resistivity method with dipole-dipole array

    Directory of Open Access Journals (Sweden)

    Octova Adree

    2017-01-01

    Full Text Available Mining industry is an industry with very high risk (losses. In order that mining activities can be run well, then the potential of the Earth’s resources must be known for sure. one of the Earth’s resources of high economic value is the iron ore. Iron ore is rarely found in a free state in nature, it is usually associated with other minerals and exposed randomly. With these properties, iron ore needs to be modeled before doing mining activities in order to avoid large losses. Iron ore deposits can be modeled with geoelectrical resistivity method. Dipole-dipole array will produce good imaging both vertically and laterally. From the measurement results of geoelectrical resistivity with dipole-dipole array will be obtained the value of measuring the current and potential difference. This value will generate into 2D and 3D model of the cross section of the iron ore deposits. One of the areas in West Sumatra has the potential for iron ore. Five lines were applied in this area. The result of cross section got the iron minerals associated with quartzite at 30 meters depth below the surface.

  20. Meteorite Impact "Earthquake" Features (Rock Liquefaction, Surface Wave Deformations, Seismites) from Ground Penetrating Radar (GPR) and Geoelectric Complex Resistivity/Induced Polarization (IP) Measurements, Chiemgau (Alpine Foreland, Southeast Germany)

    Science.gov (United States)

    Ernstson, K.; Poßekel, J.

    2017-12-01

    Densely spaced GPR and complex resistivity measurements on a 30,000 square meters site in a region of enigmatic sinkhole occurrences in unconsolidated Quaternary sediments have featured unexpected and highlighting results from both a meteorite impact research and an engineering geology point of view. The GPR measurements and a complex resistivity/IP electrical imaging revealed extended subrosion depressions related with a uniformly but in various degrees of intensity deformed loamy and gravelly ground down to at least 10 m depth. Two principle observations could be made from both the GPR high-resolution measurements and the more integrating resistivity and IP soundings with both petrophysical evidences in good complement. Subrosion can be shown to be the result of prominent sandy-gravelly intrusions and extrusions typical of rock liquefaction processes well known to occur during strong earthquakes. Funnel-shaped structures with diameters up to 25 m near the surface and reaching down to the floating ground water level at 10 m depth were measured. GPR radargrams could trace prominent gravelly-material transport bottom-up within the funnels. Seen in both GPR tomography and resistivity/IP sections more or less the whole investigated area is overprinted by wavy deformations of the unconsolidated sediments with wavelengths of the order of 5 - 10 m and amplitudes up to half a meter, likewise down to 10 m depth. Substantial earthquakes are not known in this region. Hence, the observed heavy underground disorder is considered the result of the prominent earthquake shattering that must have occurred during the Holocene (Bronze Age/Celtic era) Chiemgau meteorite impact event that produced a 60 km x 30 km sized crater strewn field directly hosting the investigated site. Depending on depth and size of floating aquifers local concentrations of rock liquefaction and seismic surface waves (probably LOVE waves) to produce the wavy deformations could develop, when the big

  1. Geoelectrical Monitoring of Ammonium Sorption Processes in a Biochar Filtration System

    Science.gov (United States)

    Wang, S. L.; Osei, C.; Rabinovich, A.; Ntarlagiannis, D.; Rouff, A.

    2017-12-01

    With the rise of modern agriculture, nutrient pollution has become an increasingly important environmental concern. A common problem is excess nitrogen which agricultural livestock farms often generate in the form of ammonium (NH4+). This highly soluble ion is easily transported through runoff and leaching, leading to water supply contamination and soil fertility decline. Biochar is the carbon-rich product of thermal decomposition of biomass in an oxygen-free environment. It is primarily used as a soil enhancer with other applications currently under research. Biochar's unique characteristics such as high surface area, high sorption capacity and long term biological and chemical stability make it a prime candidate for environmental applications such as contaminant regulation and waste effluent treatment. The spectral induced polarization (SIP) method is an established geoelectrical method that has been increasingly used in environmental investigations. SIP is unique among geophysical methods because it is sensitive not only to the bulk properties of the medium under investigation but also to the interfacial properties (e.g., mineral-fluid). The unique properties that make biochar attractive for environmental use are associated with surface properties (e.g., surface area, surface charge, presence of functional groups) that are expected to have a profound effect on SIP signals. This study presents early results on the use of the SIP method to monitor ammonium recycling of swine wastewater in a biochar filtration system. SIP measurements were taken continuously as biochar-packed columns were first injected with an ammonium wastewater solution (sorption phase) and then an ammonium-free solution (desorption phase). Geochemical monitoring showed that outflow ammonium concentration decreased during the sorption phase and increased during the desorption phase. The collected SIP data appear to be in agreement with the geochemical monitoring, providing a temporally

  2. Geoelectric structure estimated from magnetotelluric data from the ...

    Indian Academy of Sciences (India)

    In the period band from 1 to 100 s average geoelectric strike in the southern end of the profile (Indo-Gangetic Plains) is N79°W, which is slightly rotated to the north in the Lesser Himalayan region and becomes N68°W whereas it is N81°W in the Higher Himalayan region. However, average strike is stabilized to N77°W for ...

  3. Computational Modeling of Geoelectrical Soundings using PML-FDTD

    OpenAIRE

    Ribeiro, Luísa F.; Novo, Marcela S.

    2017-01-01

    Abstract The Finite-Difference Time-Domain (FDTD) method was applied in order to analyze the transient responses of geoelectrical soundings that use circular electric dipole (CED) as source over stratified formations. The model was developed in cylindrical coordinates and a perfectly matched layer (PML) was incorporated to the domain to absorb wave reflections at computational grid boundaries. Numeric results are validated with analytic solutions. Comparisons between the transient response of...

  4. Geoelectric investigation for the delineation of aquiferous zone in a ...

    African Journals Online (AJOL)

    The result of the resistivity survey showed that Akure urban consists of three to five geoelectric layers of varying thickness and resistivities. The thickness of the layers ranges from 0.5 m to about 90.0 m while the layer resistivities range from about 20 Ohm-m to 20,000 Ohm-m and above. The depth to aquifer ranges from 1.9 ...

  5. Combination of photogrammetric and geoelectric methods to assess 3d structures associated to natural hazards

    Science.gov (United States)

    Fargier, Yannick; Dore, Ludovic; Antoine, Raphael; Palma Lopes, Sérgio; Fauchard, Cyrille

    2016-04-01

    production of a complete 3D mesh of the previous surface model to operate some forward modelization of the geo-electrical problem. To solve the inverse problem and obtain a 3D resistivity distribution we use a double grid method associated with a regularized Gauss-Newton inversion scheme. We applied this procedure to a synthetic case to demonstrate the impact of the geometry on the inversion result. This study shows that geometrical information in between electrodes are necessary to reconstruct finely the "true model". Finally, we apply the methodology to a real underground quarry pillar, implying one photogrammetric survey and three ERI surveys. The results show that the procedure can greatly improve the reconstruction and avoid some artifacts due to strong geometry variations.

  6. CO2 degassing in the Hartoušov mofette area, western Eger Rift, imaged by CO2 mapping and geoelectrical and gravity surveys

    Czech Academy of Sciences Publication Activity Database

    Nickschick, T.; Kämpf, H.; Flechsig, C.; Mrlina, Jan; Heinicke, J.

    2015-01-01

    Roč. 104, č. 8 (2015), s. 2107-2129 ISSN 1437-3254 R&D Projects: GA MŠk LM2010008 Institutional support: RVO:67985530 Keywords : Eger Rift * Cheb Basin * magmatic CO2 * CO2 gas flux studies * geoelectrics * gravity Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.133, year: 2015

  7. Geoelectrical Surveys for Characterization of the Coastal Saltwater Intrusion in Metapontum Forest Reserve (Southern Italy

    Directory of Open Access Journals (Sweden)

    Antonio Satriani

    2012-01-01

    Full Text Available A geoelectrical survey was carried out in the Metapontum Forest Reserve located along the Ionian coast of the Basilicata region (Southern Italy. In this work we used the method of two-dimensional electrical resistivity tomography for obtaining high-resolution electrical images in the investigated site. In particular, three electrical resistivity tomography, all orthogonal to the coastline, in the investigated area were carried out. To complete and integrate the geophysical data, soil and groundwater samplings, seventeen and five, respectively, were analyzed using chemical physical techniques. Geoelectrical survey, supported by laboratory analysis of soil and water samples have revealed the presence of a process of saltwater in coastal Forest Reserve of Metapontum, which have caused the decline of the existing pine forest with the consequent erosion and desertification problems. The results have disclosed the way to identify and discriminate large areas affected by intensive soil salinization and high resolution electrical images of the subsurface electrical resistivity plays a key role in delineating the saltwater intrusion front in coastal areas. Furthermore, our integrated study represents a contribution to the future programs for the protection, planning, and management of the terrestrial and marine resources in this coastal area.

  8. Influence of spatial variations of the geoelectric field on geomagnetically induced currents

    Directory of Open Access Journals (Sweden)

    Viljanen Ari

    2017-01-01

    Full Text Available The geoelectric field driving geomagnetically induced currents (GIC has complex spatial variations. It follows that different patterns of the field vectors in a given area having the same regional mean can produce very different GIC. In this study, we consider a few power grid models and calculate GIC due to a modelled geoelectric field with a regional mean magnitude of 1 V/km. Altogether 8035 snapshots of the electric field are included. We also assume two different ground conductivity models, of which the simpler one consists of two layers across the whole region, and another model has four different two-layer blocks. As a measure of GIC, we use the sum of currents at all substations of the power grid. We also consider the distribution of GIC at a single site. For a given grid, differences between the two ground conductivity models are small. When comparing different power grid models, the sum of GIC varies relatively more for a grid with a small number of substations and transmission lines. When the area and the number of substations increase, the relative difference between the smallest and largest GIC sum decreases. In all cases, assuming a spatially uniform electric field leads to a reasonable estimation of the GIC magnitudes, but it does not produce the largest GIC sum. For a single substation, there is a large variety of GIC values due to different electric field configurations.

  9. Applying inversion techniques to derive source currents and geoelectric fields for geomagnetically induced current calculations

    Directory of Open Access Journals (Sweden)

    J. S. de Villiers

    2014-10-01

    Full Text Available This research focuses on the inversion of geomagnetic variation field measurement to obtain source currents in the ionosphere. During a geomagnetic disturbance, the ionospheric currents create magnetic field variations that induce geoelectric fields, which drive geomagnetically induced currents (GIC in power systems. These GIC may disturb the operation of power systems and cause damage to grounded power transformers. The geoelectric fields at any location of interest can be determined from the source currents in the ionosphere through a solution of the forward problem. Line currents running east–west along given surface position are postulated to exist at a certain height above the Earth's surface. This physical arrangement results in the fields on the ground having the magnetic north and down components, and the electric east component. Ionospheric currents are modelled by inverting Fourier integrals (over the wavenumber of elementary geomagnetic fields using the Levenberg–Marquardt technique. The output parameters of the inversion model are the current strength, height and surface position of the ionospheric current system. A ground conductivity structure with five layers from Quebec, Canada, based on the Layered-Earth model is used to obtain the complex skin depth at a given angular frequency. This paper presents preliminary and inversion results based on these structures and simulated geomagnetic fields. The results show some interesting features in the frequency domain. Model parameters obtained through inversion are within 2% of simulated values. This technique has applications for modelling the currents of electrojets at the equator and auroral regions, as well as currents in the magnetosphere.

  10. investigation of relationships between geoelectric and hydraulic ...

    African Journals Online (AJOL)

    Timothy Ademakinwa

    In an attempt to establish empirical electric-hydraulic relationships for the purpose of analyzing surface ... flow and electrical current, are though different in ..... transmissivity and electric transverse resistance for shallow aquifers and deep reservoirs from surface and well-log measurements. Hydrology. Earth Systems.

  11. Progress in Geo-Electrical Methods for Hydrogeological Mapping?

    DEFF Research Database (Denmark)

    Schrøder, Niels

    2014-01-01

    In most of the 20th century the geo-electrical methods were primarily used for groundwater exploration and the application of the methods were normally followed by a borehole, and a moment of truth. In this process the use of DC (direct current) soundings have been developed to a high grade of ex....... The test area was earlier mapped by DC-soundings, so it is possible to test the methods against each other. It is concluded that well performed DC-soundings with a Schlumberger configuration still provide the best base for hydrogeological mapping...

  12. Surface tritium contamination studies

    International Nuclear Information System (INIS)

    Sienkiewicz, C.J.

    1986-01-01

    Glovebox wipe surveys were conducted to correlate surface tritium contamination with atmospheric tritium levels. Surface contamination was examined as a function of tritium concentration and limited to the HT/T 2 form. The previously predicted relationship between atmospheric HTO concentration and cleanup times was examined in order to predict a model for atmospheric detritiation of stainless steel enclosures. 2 figures, 2 tables

  13. Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Tim; Binley, Andrew; Lane, John

    2014-01-16

    Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3

  14. First geoelectric investigations within a sealing construction in the Asse

    International Nuclear Information System (INIS)

    Yaramanci, U.; Flach, D.

    1989-09-01

    Within a sealing construction project extensive geoelectrical DC-measurements have been carried out underground in the rock salt of the Asse. The investigations are already in progress before the building of the dam galleries and the dam itself and the insertion of brine, respectively. Thus they also serve as reference measurements for the variations of the conductivity structure of the investigated area during the different phases of the project. A fully automatic computer controlled measuring system has been developed and an extensive electrode network was installed in boreholes. Both the system and the netwerk have proved to be adequate. In principle and in practice the feasibility of the geoelectrical DC-method for both measurements in rock salt and for exploration has been indicated. On the average, the resistivity is 0.5 10 6 Ωm with relatively small variations of ±20%. In essence, the investigated area is homogeneous except for the local structure of a conductive inclusion, probably of a sulphate inclusion. (orig.) [de

  15. Geoelectric field estimation and power-line integration using a 3D electrical conductivity model of the United States

    Science.gov (United States)

    Kelbert, A.; Balch, C. C.; Lucas, G.; Rigler, E. J.

    2017-12-01

    Estimation of ground-level geoelectric fields has been identified by the electrical power industry as a key capability in assessment and mitigation of the impacts of space weather on electrical power infrastructure. One approach to estimation of ground-level geoelectric fields in the United States is to employ the best available three-dimensional Earth conductivity models (Meqbel et al., 2014; Yang et al., 2015; Murphy & Egbert, 2017 and others). These models are the results of regional magnetotelluric inversions based on NSF's Earthscope USArray impedances (Schultz et al., 2006-2018). The work on the 3D conductivity models is ongoing as new USArray data are obtained, and new methods for improved magnetotelluric inversion are developed. Here, we describe the initial USGS compilation of 3D electrical conductivity models for the United States. We analyze the high-resolution gridded Earth impedances obtained in selected regions of the United States, and discuss the effects of impedance grid resolution on the electric fields integrated along power lines, which serve as a proxy for geomagnetically induced current (GIC) amplitude. Our approach also allows us to analyze the effects of magnetotelluric distortion due to the small-scale near-surface anomalies on the GIC proxy. This analysis feeds into the development of operational Geoelectric Field Maps at NOAA's Space Weather Prediction Center (SWPC), a system for near real-time (no more than a several mins data latency) estimation of spatially variable ground-level geoelectric fields. A preliminary experimental capability is now available to the public at SWPC's website (http://www.swpc.noaa.gov). The deployment of these maps represents a significant advance in the specification of space weather hazards compared to what was previously available, i.e. global geomagnetic indices, providing the electrical power industry with a tool to assess regional space weather hazards in near real-time. An emphasis will also be made to

  16. Gravimetric water distribution assessment from geoelectrical methods (ERT and EMI) in municipal solid waste landfill.

    Science.gov (United States)

    Dumont, Gaël; Pilawski, Tamara; Dzaomuho-Lenieregue, Phidias; Hiligsmann, Serge; Delvigne, Frank; Thonart, Philippe; Robert, Tanguy; Nguyen, Frédéric; Hermans, Thomas

    2016-09-01

    The gravimetric water content of the waste material is a key parameter in waste biodegradation. Previous studies suggest a correlation between changes in water content and modification of electrical resistivity. This study, based on field work in Mont-Saint-Guibert landfill (Belgium), aimed, on one hand, at characterizing the relationship between gravimetric water content and electrical resistivity and on the other hand, at assessing geoelectrical methods as tools to characterize the gravimetric water distribution in a landfill. Using excavated waste samples obtained after drilling, we investigated the influences of the temperature, the liquid phase conductivity, the compaction and the water content on the electrical resistivity. Our results demonstrate that Archie's law and Campbell's law accurately describe these relationships in municipal solid waste (MSW). Next, we conducted a geophysical survey in situ using two techniques: borehole electromagnetics (EM) and electrical resistivity tomography (ERT). First, in order to validate the use of EM, EM values obtained in situ were compared to electrical resistivity of excavated waste samples from corresponding depths. The petrophysical laws were used to account for the change of environmental parameters (temperature and compaction). A rather good correlation was obtained between direct measurement on waste samples and borehole electromagnetic data. Second, ERT and EM were used to acquire a spatial distribution of the electrical resistivity. Then, using the petrophysical laws, this information was used to estimate the water content distribution. In summary, our results demonstrate that geoelectrical methods represent a pertinent approach to characterize spatial distribution of water content in municipal landfills when properly interpreted using ground truth data. These methods might therefore prove to be valuable tools in waste biodegradation optimization projects. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Geoelectrical and hydrogeochemical characterisation of the ...

    African Journals Online (AJOL)

    All the analysed chemical elements had concentrations that were within the WHO permissible levels with the exception of very few boreholes showing relatively high nitrate and total iron concentrations. The study concluded that the study area was characterized by both the weathered layer and partly weathered/fractured ...

  18. Geoelectric investigation to delineate groundwater potential and ...

    Indian Academy of Sciences (India)

    2014), and geothermal explo- rations (El-Qady et al. 2000; Majumdar et al. 2000;. Kumar et al. 2011). Several researchers have carried out systematic hydrogeological and geophysical studies in the. Deccan trap region (Bose and Ramakrishna 1978;. Singhal 1997; Pawar et al. 2009; Rai et al. 2011;. Ratnakumari et al.

  19. Georadar and geoelectricity method to identify the determine zone of sliding landslide

    Science.gov (United States)

    Dalimunthe, Y. K.; Hamid, A.

    2018-01-01

    The aim of this research is to determine the contrast between the sliding plane by observing the parameters of rock types, fractures, and faults that could potentially land slides in Bandar Baru, Lampung Barat, Indonesia by both methods of georadar and geoelectricity. This research uses radar reflection profiling configuration for georadar and dipole-dipole configuration for geoelectricity. For georadar data processing has been done with Reflexwave software and for geoelectricity, data processing has been done with Earthimager 2DINV software to interpret subsurface section. Results of research by both methods of georadar and geoelectricity shows the area of contact between the sand stone with resistivity value of 200–1449 Ωm and clay stone with a resistivity value of 32–100 Ωm at the limit depth of 9 m as a potential zone of sliding landslides where the physical properties of clay stone easily derail massive material on it.

  20. Geoelectrical parameter-based multivariate regression borehole yield model for predicting aquifer yield in managing groundwater resource sustainability

    Directory of Open Access Journals (Sweden)

    Kehinde Anthony Mogaji

    2016-07-01

    Full Text Available This study developed a GIS-based multivariate regression (MVR yield rate prediction model of groundwater resource sustainability in the hard-rock geology terrain of southwestern Nigeria. This model can economically manage the aquifer yield rate potential predictions that are often overlooked in groundwater resources development. The proposed model relates the borehole yield rate inventory of the area to geoelectrically derived parameters. Three sets of borehole yield rate conditioning geoelectrically derived parameters—aquifer unit resistivity (ρ, aquifer unit thickness (D and coefficient of anisotropy (λ—were determined from the acquired and interpreted geophysical data. The extracted borehole yield rate values and the geoelectrically derived parameter values were regressed to develop the MVR relationship model by applying linear regression and GIS techniques. The sensitivity analysis results of the MVR model evaluated at P ⩽ 0.05 for the predictors ρ, D and λ provided values of 2.68 × 10−05, 2 × 10−02 and 2.09 × 10−06, respectively. The accuracy and predictive power tests conducted on the MVR model using the Theil inequality coefficient measurement approach, coupled with the sensitivity analysis results, confirmed the model yield rate estimation and prediction capability. The MVR borehole yield prediction model estimates were processed in a GIS environment to model an aquifer yield potential prediction map of the area. The information on the prediction map can serve as a scientific basis for predicting aquifer yield potential rates relevant in groundwater resources sustainability management. The developed MVR borehole yield rate prediction mode provides a good alternative to other methods used for this purpose.

  1. Evaluation of soil corrosivity and aquifer protective capacity using geoelectrical investigation in Bwari basement complex area, Abuja

    Science.gov (United States)

    Adeniji, A. E.; Omonona, O. V.; Obiora, D. N.; Chukudebelu, J. U.

    2014-04-01

    Bwari is one of the six municipal area councils of the Federal Capital Territory (FCT), Abuja with its attendant growing population and infrastructural developments. Groundwater is the main source of water supply in the area, and urbanization and industrialization are the predominant contributors of contaminants to the hydrological systems. In order to guarantee a continuous supply of potable water, there is a need to investigate the vulnerability of the aquifers to contaminants emanating from domestic and industrial wastes. A total of 20 vertical electrical soundings using Schlumberger electrode array with a maximum half current electrodes separation of 300 m was employed. The results show that the area is characterized by 3-6 geoelectric subsurface layers. The measured overburden thickness ranges from 1.0 to 24.3 m, with a mean value of 7.4 m. The resistivity and longitudinal conductance of the overburden units range from 18 to 11,908 Ωm and 0.047 to 0.875 mhos, respectively. Areas considered as high corrosivity are the central parts with ρ good (0.7-4.49 mhos), moderate (0.2-0.69 mhos), weak (0.1-0.19 mhos), and poor (good protective capacity serve as sealing potential for the underlying hydrogeological system in the area. This study is aimed at delineating zones that are very prone to groundwater contamination from surface contaminants and subsurface soils that are corrosive to utility pipes buried underground. Hence the findings of this work will constitute part of the tools for groundwater development and management and structural/infrastructural development planning of the area.

  2. A deep geoelectrical survey in the Southern Central Alps

    Directory of Open Access Journals (Sweden)

    G. Nuttini

    1994-06-01

    Full Text Available A deep geoelectrical survey was carried out on the Southern Central AIps, to the north of Bergamo, by means of the “continuous polar dipole-dipole” electrode array. Among the 6 profiles executed, 4 revealed the existence of a substratum with very high resistivity values (15 000-40 000 ohm.m and a flat not very deep upper boundary; its thickness exceeds the maximum expIoration depths of the soundings (1 to 6 km. On the grounds of general considerations and resistivity field data set, it is possible to infer that the high values should be ascribed to endogenous rather than to sedimentary rocks. A problem arises since these geophysical results are not in agreement with some geological models.

  3. Observatory geoelectric fields induced in a two-layer lithosphere during magnetic storms

    Science.gov (United States)

    Love, Jeffrey J.; Swidinsky, Andrei

    2015-01-01

    We report on the development and validation of an algorithm for estimating geoelectric fields induced in the lithosphere beneath an observatory during a magnetic storm. To accommodate induction in three-dimensional lithospheric electrical conductivity, we analyze a simple nine-parameter model: two horizontal layers, each with uniform electrical conductivity properties given by independent distortion tensors. With Laplace transformation of the induction equations into the complex frequency domain, we obtain a transfer function describing induction of observatory geoelectric fields having frequency-dependent polarization. Upon inverse transformation back to the time domain, the convolution of the corresponding impulse-response function with a geomagnetic time series yields an estimated geoelectric time series. We obtain an optimized set of conductivity parameters using 1-s resolution geomagnetic and geoelectric field data collected at the Kakioka, Japan, observatory for five different intense magnetic storms, including the October 2003 Halloween storm; our estimated geoelectric field accounts for 93% of that measured during the Halloween storm. This work demonstrates the need for detailed modeling of the Earth’s lithospheric conductivity structure and the utility of co-located geomagnetic and geoelectric monitoring.

  4. A New GIS based Application of Sequential Technique to Prospect Karstic Groundwater using Remotely Sensed and Geoelectrical Methods in Karstified Tepal Area, Shahrood, Iran

    Directory of Open Access Journals (Sweden)

    Fereydoun Sharifi

    2015-06-01

    Full Text Available In this research, recognition of karstic water-bearing zones using the management of exploration data in Kal-Qorno valley, situated in the Tepal area of Shahrood, has been considered. For this purpose, the sequential exploration method was conducted using geological evidences and applying remote sensing and geoelectrical resistivity methods in two major phases including the regional and local scales. Thus, geological structures and lithological units in regional scale have been investigated for groundwater potential. In this regard, suitable potential maps have been provided in the geographical information system (GIS environment, using fuzzy data-driven and knowledge-driven methods. To obtain the final karstic water potential model, the prepared maps were combined using fuzzy ‘AND’ operator. In the local scale, geoelectrical surveys were conducted in the recognized high potential zones. Consequently, the results of geological investigations, analysis of lineaments extracted from satellite imagery and geoelectrical resistivity data modeling and interpretation were integrated to decide on the position of high yield extraction wells. As a result, karstic water zones in the study area were identified, and based on that, two suitable drilling locations to access and extract karstic groundwater in the study area have been suggested.

  5. Ventilation test at Mont Terri. Geoelectric monitoring of the opalinus clay desaturation. Phase 2

    International Nuclear Information System (INIS)

    Wieczorek, Klaus; Zhang, Chun-Liang; Rothfuchs, Tilmann

    2008-04-01

    Between December 2001 and May 2004, a ventilation experiment (VE) was performed in the Mont Terri Underground Research Laboratory (URL) and co-financed by the Commission of the European Communities. The objective was to investigate the desaturation of consolidated clay formations in consequence of the ventilation of underground openings of a repository in such a formation. The results of the geoelectric measurements performed in the second phase of the Mont Terri ventilation test can be summarized as follows: Geoelectric tomography has been found suitable for monitoring ventilation-induced saturation changes in the Opalinus clay. During ventilation with dry air a desaturation down to below 50% could be detected in both desaturation cycles. The desaturated zone extends less than 0.5 m into the rock around the microtunnel. During the second resaturation phase, ventilation with humid air led to quick resaturation at the tunnel surface, while resaturation of the rock mass took months. The still ongoing third resaturation phase seems to imply that resaturation of the rock mass may take years with no air circulation in the tunnel. The laboratory investigations on the Opalinus clay included the determination of water retention capacity, swelling pressure, free swelling/shrinking strains induced by moisture changes, and response of normal and large hollow clay samples to the ventilation of the central boreholes at different air humidity values. The Opalinus clay has a high water absorption capacity. The amount of water uptake in unconstraint conditions is much higher than the water content in the naturally confined state, indicating that the pore water in the natural clay rock is predominantly bound on clay minerals. The swelling pressure induced by wetting with vapour is very close to the major lithostatic stress at the sampling location. Water uptake from vapour causes a large free expansion of up to 12% over 8 months and even a breakdown along bedding planes. Release of

  6. Geoelectric Exploration of the Purísima-Rumicruz District, Jujuy Province, Argentina

    Directory of Open Access Journals (Sweden)

    Luciano López

    2012-01-01

    Full Text Available Purísima-Rumicruz district consists of several polymetallic veins, rich in copper and lead. The veins have a breccia texture and are located in shear bands, with locally high concentrations of sulfides in a carbonatic gangue. The host rock of the veins consists of a black shale sequence with thin levels of fine sands, with a low degree of metamorphism, and corresponds to the Acoite formation (Lower Ordovician. The depositional environment was an open clastic platform where storm processes prevailed. An exploratory program using induced polarization and resistivity with the dipole-dipole method was carried out with the objective of establishing geoelectric anomalies in depth, which would permit the identification of exploratory targets. The group of veins was divided into three sectors: Purísima, El Brechón, and La Nueva. Low-resistivity values correspond to faulty zones, some of which are related to surface veins. The presence of diagenetic pyrite in the shales of Acoite formation considerably increases background chargeability (induced polarization values. However, small chargeability anomalies associated to low-resistivity values represent exploratory targets for the Purísima-Rumicruz district.

  7. Geoelectrical characterization of a site with hydrocarbon contamination caused by pipeline leakage

    Energy Technology Data Exchange (ETDEWEB)

    Delgado-Rodriguez, Omar; Shevnin, Vladimir; Ochoa-Valdes, Jesus [Instituto Mexicano del Petroleo, Mexico, D.F. (Mexico); Ryjov, Albert [Moscow State Geological Prospecting Academy, Moscow (Russian Federation)

    2006-01-15

    Vertical Electrical Sounding (VES) method is used extensively in environmental impact studies including hydrocarbon contamination. In this work, the results of the geoelectrical characterization of a contaminated site caused by pipeline leakage are presented. Geoelectrical study was performed with multi-electrode technology and 2D profile data interpretation. VES results from six parallel profiles were presented in resistivity sections and maps. Layered model of the site was found including aquifer and aquitard layers. Although the contamination grade of the site is low, we found two contaminated zones into sandy aquifer. Aquifer and aquitard were characterized by its resistivity, clay content, porosity and cation exchange capacity values. Recalculation of resistivity data into petrophysical sections and maps was performed by an inversion algorithm taking into account pore water salinity. Petrophysical parameters for uncontaminated areas estimated from resistivity are close to real values; meanwhile, in contaminated zones petrophysical parameters have anomalous values. Similar effects of contamination influence on petrophysical parameters were found in laboratory by resistivity measurements made at clean and contaminated sand samplers. [Spanish] El metodo Sondeo Electrico Vertical (SEV) es ampliamente utilizado en estudios de impacto ambiental incluyendo el caso de contaminacion por hidrocarburos. En este trabajo se presentan los resultados de la caracterizacion geoelectrica de un sitio contaminado por hidrocarburos relacionado con una fuga en linea de ducto. El estudio geoelectrico fue realizado utilizando el metodo SEV en la variante de tomografia, realizandose una interpretacion 2D de los datos observados. Seis perfiles paralelos de SEV fueron medidos y presentados sus resultados en secciones y mapas. Se determino un modelo estratificado que incluye acuitardo y acuifero. Aunque el grado de contaminacion en este sitio es bajo fue posible localizar dos zonas

  8. Final Report: Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Day-Lewis, Fred [U.S. Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John [U.S. Geological Survey, Storrs, CT (United States)

    2014-03-20

    Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3

  9. First-Principles Propagation of Geoelectric Fields from Ionosphere to Ground using LANLGeoRad

    Science.gov (United States)

    Jeffery, C. A.; Woodroffe, J. R.; Henderson, M. G.

    2017-12-01

    A notable deficiency in the current SW forecasting chain is the propagation of geoelectric fields from ionosphere to ground using Biot-Savart integrals, which ignore the localized complexity of lithospheric electrical conductivity and the relatively high conductivity of ocean water compared to the lithosphere. Three-dimensional models of Earth conductivity with mesoscale spatial resolution are being developed, but a new approach is needed to incorporate this information into the SW forecast chain. We present initial results from a first-principles geoelectric propagation model call LANLGeoRad, which solves Maxwell's equations on an unstructured geodesic grid. Challenges associated with the disparate response times of millisecond electromagnetic propagation and 10-second geomagnetic fluctuations are highlighted, and a novel rescaling of the ionosphere/ground system is presented that renders this geoelectric system computationally tractable.

  10. Monitoring of In-Situ Remediation By Time Lapse 3D Geo-Electric Measurements

    Science.gov (United States)

    Kanli, A. I.; Tildy, P.; Neducza, B.; Nagy, P.; Hegymegi, C.

    2017-12-01

    Injection of chemical oxidant solution to degrade the subsurface contaminants can be used for hydrocarbon contamination remediation. In this study, we developed a non-destructive measurement strategy to monitor oxidative in-situ remediation processes. The difficulties of the presented study originate from the small volume of conductive solution that can be used due to environmental considerations. Due to the effect of conductive groundwater and the high clay content of the targeted layer and the small volume of conductive solution that can be used due to environmental considerations, a site specific synthetic modelling is necessary for measurement design involving the results of preliminary 2D ERT measurements, electrical conductivity measurements of different active agents and expected resistivity changes calculated by soil resistivity modelling. Because of chemical biodegradation, the results of soil resistivity modelling have suggested that the reagent have complex effects on contaminated soils. As a result the plume of resistivity changes caused by the injected agent was determined showing strong fracturing effect because of the high pressure of injection. 3D time-lapse geo-electric measurements were proven to provide a usable monitoring tool for in-situ remediation as a result of our sophisticated tests and synthetic modelling.

  11. Geoelectric investigation of a site for a proposed airport in Ebonyi ...

    African Journals Online (AJOL)

    A geoelectric investigation, involving 1-D Vertical Electrical Sounding (VES) with the Schlumberger array and 2- D Electrical Imaging with the dipole-dipole array, was carried out at a site proposed for an airport in Ebonyi State. This was with a view to generating near and subsurface images required for the assessment of ...

  12. Geomorphological and Geoelectric Techniques for Kwoi's Multiple Tremor Assessment

    Science.gov (United States)

    Dikedi, P. N.

    2017-12-01

    This work epicentres on geomorphological and geoelectric techniques for multiple tremor assessment in Kwoi, Nigeria. Earth tremor occurrences have been noted by Akpan and Yakubu (2010) within the last 70 years, in nine regions in Nigeria; on September 11,12,20,22, 23 and 24, 2016, additional earth tremors rocked the village of Kwoi eleven times. Houses cracked and collapsed, a rock split and slid and smoke evolved at N9027''5.909''', E800'44.951'', from an altitude of 798m. By employing the Ohmega Meter and Schlumberger configuration, four VES points are sounded for subsurface structure characterisation. Thereafter, a cylindrical steel ring is hammered into the ground at the first point (VES 1) and earth samples are scooped from this location; this procedure is repeated for other points (VES 2, 3 and 4). Winresist, Geo-earth, and Surfer version 12.0.626 software are employed to generate geo-sections, lithology, resistivity profile, Iso resistivity and Isopach maps, of the region. Outcome of results reveal some lithological formations of lateritic topsoil, fractured basement and fresh basement; additionally, results reveal 206.6m, 90.7m, 73.2m and 99.4m fractured basement thicknesses for four points. Scooped samples are transferred to the specimen stage of a Scanning Electron Microscope (SEM). SEM images show rounded inter-granular boundaries—the granular structures act like micro-wheels making the upper crustal mass susceptible to movement at the slightest vibration. Collapsed buildings are sited around VES1 location; samples from VES 1 are the most well fragmented sample owing to multiple microfractures—this result explains why VES 1 has the thickest fractured basement. Abrupt frictional sliding occurs between networks of fault lines; there is a likelihood that friction is most intense at the rock slide site on N9027'21.516'' and E800'44.9993'', VES 1 at N9027'5.819'' and E8005'3.1120'' and smoke sites—holo-centres are suspected below these locations. The

  13. Geoelectric Evaluation of Groundwater Potential: A Case Study of ...

    African Journals Online (AJOL)

    A d.c resistivity investigation for groundwater was carried out in Sabongida-Ora and its environs of Owan West Local Government of Edo State. A total of seven vertical electrical sounding (VES) was carried out using the Schlumberger configuration with a maximum current electrode spacing ranging from 500- 650m.

  14. Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters Final Report to the Subsurface Biogeochemical Research Program

    Energy Technology Data Exchange (ETDEWEB)

    Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Timothy; Binley, Andrew; Lane, John

    2014-03-10

    . In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Our study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3-part research plan involving (1) development of computer codes and techniques to estimate mass-transfer parameters from time-lapse electrical data; (2) bench-scale experiments on synthetic materials and materials from cores from the Hanford 300 Area; and (3) field demonstration experiments at the DOE’s Hanford 300 Area.

  15. Geoelectrical assessment of polluted zone by sewage effluent in University of Ibadan campus southwestern Nigeria.

    Science.gov (United States)

    Olaojo, Abayomi Adesola; Oladunjoye, Michael Adeyinka; Sanuade, Oluseun Adetola

    2017-12-15

    Sewage effluent was discharged through leaking sewer into the agricultural training farms, University of Ibadan which is used for cultivation of vegetables and cereals, thus constituting threat to human health. This study examined the reliability of the electrical resistivity technique in delineating sewage polluted zones and possible pathways into the groundwater network. The area investigated is underlain by banded gneisses. Ten resistivity Wenner-imaging lines (N-S) were established and inverted section generated using RES2DINV. Thirty VES stations were occupied using Schlumberger array, the current electrode spacing (AB/2) expanded from 1 to 75 m and data analysed using WinResist. 2-D inverted section depicted the top soil and clay unit. Resistivity in the top soil (36-70 Ω-m) showed a decrease of 57 to 78% while the clayey unit (6-18 Ω-m) showed a reduction of 63 to 88% relative to the control units. Plunge in resistivity within the top soil and clay units suggests the presence of pollutants. VES-derived geoelectric section recorded three varying sequences, with a fall in resistivity in the top soil (22-58 Ω-m) and the clay unit (6-15 Ω-m) compared with the reference layers having 233 and 34 Ω-m, respectively; the fractured sections in some parts of the bedrock could serve as a conduit for the seepage of the pollutants into the groundwater system. Drop in resistivity suggests the presence of pollutants within the top soil and clay units. These techniques have helped in mapping out unnatural zones around the farm.

  16. Geo-electrical characterization of the excavation disturbed zone (EDZ) in the experimental platform of Tournemire

    International Nuclear Information System (INIS)

    Okay, G.; Cosenza, P.; Ghorbani, A.; Cabrera, J.; Camerlynck, C.; Florsch, N.; Revil, A.

    2010-01-01

    Document available in extended abstract form only. The French Institute for Radiation protection and Nuclear Safety (IRSN) has selected the experimental Tournemire site (Aveyron, France) to study the confinement properties of the argillaceous media and damages induced by galleries' excavation. Electrical resistivity and induced polarization tomography have been performed to address in the field the capabilities of electrical methods for characterizing the EDZ. Four geo-electrical surveys were performed in three different galleries of the Tournemire's URL: the eastern gallery excavated in 1996 (GE-96), the eastern gallery excavated in 2003 (GE-03) and finally the northern gallery excavated in 2008 (GN-08). The geo-electrical surveys consisted in 2D longitudinal and circular profiles including 48 and 43 electrodes (separation of 20 cm) respectively. Non-polarizing Cu/CuSO 4 electrodes (9 mm in diameter) were used and installed in micro-drillings filled with wet bentonite. Measurements were carried out with a Syscal Pro device (IRIS instruments). Measured apparent resistivity and chargeability values were inverted with Res2Dinv software. The results obtained from the first survey in June 2008 in GE-96 confirmed that electrical methods were able to localize the non saturated and fractured zones around the gallery. Additional measurements were carried out in the same gallery with the same experimental procedure for a dry atmosphere period, i.e. in February 2009. The results of this second survey indicated a more important desaturation of argillite around fractures (characterized by higher electrical resistivity values) enhanced by the initial shallow fractures in connection with a drier atmosphere. Moreover, inverted Induced Polarization (IP) data have shown a strong spatial correlation between important chargeability anomalies and calcite-filled tectonic fractures. However, neo-formed fractures (with no filling), associated with a mechanical damage, didn

  17. Geoelectrical imaging of groundwater salinization in the Okavango Delta, Botswana

    Science.gov (United States)

    Bauer, Peter; Supper, Robert; Zimmermann, Stephanie; Kinzelbach, Wolfgang

    2006-10-01

    Soil and groundwater salinization is a major problem in aquatic systems throughout the semi-arid and arid regions. An interesting example of a natural terminal evaporative system is the Okavango Delta, a large inland Delta in Botswana. The system accumulates about 300,000 tons of dissolved solids per year. The majority of the accumulated solutes are deposited on small islands in the wetland. In the centre of the islands, the shallow groundwater is therefore highly saline and displays total dissolved solid (TDS) concentrations around 30 g/l. Fresh groundwater underlying the superficial brines gives rise to a hydrodynamically unstable situation with dense brine perched on less dense fresh water. Instabilities (density fingers) can potentially occur and effectively transport the superficial brines into deeper aquifer units. Electrical resistivity tomography (ERT) was used in this study to directly map the salinity distribution in the subsurface below two different islands in the Okavango Delta. Surface arrays as well as borehole-to-surface layouts were used. Due to differences in the regional hydrologic setting, a density finger could be observed on one island, whereas on the other, the high salinity anomaly was confined to the surface layer. To our knowledge, this is the first time that fingering instabilities were observed under field conditions in natural aquifers.

  18. Mapping localised freshwater anomalies in the brackish paleo-lake sediments of the Machile–Zambezi Basin with transient electromagnetic sounding, geoelectrical imaging and induced polarisation

    DEFF Research Database (Denmark)

    Chongo, Mkhuzo; Christiansen, Anders Vest; Fiandaca, Gianluca

    2015-01-01

    A recent airborne TEM survey in the Machile–Zambezi Basin of south western Zambia revealed high electrical resistivity anomalies (around 100 Ωm) in a low electrical resistivity (below 13 Ωm) background. The near surface (0–40 m depth range) electrical resistivity distribution of these anomalies...... appeared to be coincident with superficial features related to surface water such as alluvial fans and flood plains. This paper describes the application of transient electromagnetic soundings (TEM) and continuous vertical electrical sounding (CVES) using geo-electrics and time domain induced polarisation...... thins out and deteriorates in water quality further inland. It is postulated that the freshwater lens originated as a result of interaction between the Zambezi River and the salty aquifer in a setting in which evapotranspiration is the net climatic stress. Similar high electrical resistivity bodies were...

  19. Fluctuation dynamics in geoelectrical data: an investigation by using multifractal detrended fluctuation analysis

    International Nuclear Information System (INIS)

    Telesca, Luciano; Colangelo, Gerardo; Lapenna, Vincenzo; Macchiato, Maria

    2004-01-01

    We analyzed fluctuations in the time dynamics of nonstationary geoelectrical data, recorded in a seismic area of southern Italy, by means of the multifractal detrended fluctuation analysis (MF-DFA). The multifractal character of the signal depends mostly on the different long-range properties for small and large fluctuations. The time variation of indices, denoting the departure from monofractal behaviour, reveals an enhancement of the multifractality of the signal prior seismic occurrences

  20. Magnetic and geoelectrical surveying in the Roman age town Porolissum (NW Romania)

    Science.gov (United States)

    Petrovszki, J.

    2009-04-01

    We present the results of magnetic and geoelectrical surveys carried out in a Roman age town Porolissum (NW Romania). Porolissum was the capital of the province Dacia Porolissensis in the 2nd and 3rd centuries, and it had 20000 inhabitants. After the Romans left Dacia the town was deserted. The buildings in the town were built from dacite mined in nearby quarries. The dacite has large magnetic susceptibility and large electric resistivity compared to the soil, which allows the detection of the ruins by magnetic and geoelectrical measurements. We made magnetic surveying using GSM-19 Overhauser magnetometers in the fortress, the town and the cemetery. We were able to map streets, foundations of different buildings: houses, sanctuaries, and in the cemetery roads, graves and graveyards. In those places where the interpretation of the results of the magnetic surveys was not clear, geoelectrical measurements were made to clarify the presence of dacite. The geophysical surveys help to reconstruct the structure of the archeological objects, and on large scale the structure of the town. Based upon our results, the archeologists dug more trenches, which confirmed the interpretation of geophysical measurements.

  1. Geoelectrical Data Inversion by Clustering Techniques of Fuzzy Logic to Estimate the Subsurface Layer Model

    Directory of Open Access Journals (Sweden)

    A. Stanley Raj

    2015-01-01

    Full Text Available Soft computing based geoelectrical data inversion differs from conventional computing in fixing the uncertainty problems. It is tractable, robust, efficient, and inexpensive. In this paper, fuzzy logic clustering methods are used in the inversion of geoelectrical resistivity data. In order to characterize the subsurface features of the earth one should rely on the true field oriented data validation. This paper supports the field data obtained from the published results and also plays a crucial role in making an interdisciplinary approach to solve complex problems. Three clustering algorithms of fuzzy logic, namely, fuzzy C-means clustering, fuzzy K-means clustering, and fuzzy subtractive clustering, were analyzed with the help of fuzzy inference system (FIS training on synthetic data. Here in this approach, graphical user interface (GUI was developed with the integration of three algorithms and the input data (AB/2 and apparent resistivity, while importing will process each algorithm and interpret the layer model parameters (true resistivity and depth. A complete overview on the three above said algorithms is presented in the text. It is understood from the results that fuzzy logic subtractive clustering algorithm gives more reliable results and shows efficacy of soft computing tools in the inversion of geoelectrical resistivity data.

  2. Nonlinear optical techniques for surface studies

    International Nuclear Information System (INIS)

    Shen, Y.R.

    1981-09-01

    Recent effort in developing nonlinear optical techniques for surface studies is reviewed. Emphasis is on monolayer detection of adsorbed molecules on surfaces. It is shown that surface coherent antiStokes Raman scattering (CARS) with picosecond pulses has the sensitivity of detecting submonolayer of molecules. On the other hand, second harmonic or sum-frequency generation is also sensitive enough to detect molecular monolayers. Surface-enhanced nonlinear optical effects on some rough metal surfaces have been observed. This facilitates the detection of molecular monolayers on such surfaces, and makes the study of molecular adsorption at a liquid-metal interface feasible. Advantages and disadvantages of the nonlinear optical techniques for surface studies are discussed

  3. Application of geoelectric and electromagnetic methods for the detection of failing zones and brine rising zones in the vicinity of a potential CO2-storage site

    Science.gov (United States)

    Herd, Rainer; Krause, Yvonne; Schafrik, Wlad

    2013-04-01

    Within the framework of the project "brine - CO2 storage in eastern Brandenburg" geophysical investigations are conducted by the German Research Center for Geoscience (GFZ), Potsdam and the Brandenburg University of Technology (BTU), Cottbus on different scales in order to investigate underground situations and evaluate methods suitable for a salinization early warning system. The research of BTU is focused on the distribution of underground structures up to a maximum depth of 200m. Of prevalent interest are the detection capabilities for near surface failing zones which might serve as favored pathways for brine migration and the status-quo of the freshwater-saltwater boundary. Geophysical investigations with the frequency domain electromagnetic (FDEM) and direct current (DC) geoelectric methods are qualified for the identification and monitoring of brine displacement as the measuring parameter is the resistivity/conductivity of the subsurface. In eastern Brandenburg the Oligocene Rupelian clay represents the barrier horizon separating the freshwater and saline aquifers. Due to postglacial processes this layer is locally reduced or totally eroded and might enhance upward brine migration during pressure increase. The areas of investigation were selected by known high fluid conductivity values (hydro chemical indication) and the potential presence of quaternary erosion channels in the Rupelian clay (geological indication). The geophysical results yield a vertical and horizontal resistivity/conductivity distribution. The interpretation is done by lithology profiles of nearby boreholes and correlation with fluid conductivities in groundwater wells. The results of FDEM and DC on coincident profiles are generally in accordance and show that both methods are suitable with DC geoelectrics supplementing a higher resolution close to the surface (max. 80m depth) and the electromagnetics adding coarser/less detailed conductivity information of the deeper underground (down to

  4. Surface Acoustic Wave Transducer Study.

    Science.gov (United States)

    1978-05-01

    ment. — ISO Lir — ~.1 L ~~~~~~~~ ~ ~~~ L~~~I&jr ~~ —- — — —--- - - - - t - s’ rlr ~~T I O , 4 ) F ~ H I ’ ~~,! ~WI.ft ?).s. ~~~~MEPORT DOCUMENTAT I...multiplying the norma l stress components thus ensuring that the normal stress is zero at x 2 = 0. For the present , an open-circuit elec trical...boundary condition is assumed so that the norma l D-uield is zero at the surface. This is taken .5 into account in a similar manner with a step-function

  5. Surface study of liquid 3He using surface state electrons

    International Nuclear Information System (INIS)

    Shirahama, K.; Ito, S.; Suto, H.; Kono, K.

    1995-01-01

    We have measured the mobility of surface state electrons (SSE) on liquid 3 He, μ 3 , aiming to study the elementary surface excitations of the Fermi liquid. A gradual increase of μ 3 below 300 mK is attributed to the scattering of electrons by ripplons. Ripplons do exist in 3 He down to 100 mK. We observe an abrupt decrease of μ 3 , due to the transition to the Wigner solid (WS). The dependences of the WS conductivity and mobility on temperature and magnetic field differ from the SSE behavior on liquid 4 He

  6. Surface studies of plasma processed Nb samples

    International Nuclear Information System (INIS)

    Tyagi, Puneet V.; Doleans, Marc; Hannah, Brian S.; Afanador, Ralph; Stewart, Stephen; Mammosser, John; Howell, Matthew P; Saunders, Jeffrey W; Degraff, Brian D; Kim, Sang-Ho

    2015-01-01

    Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma-processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO 2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV.

  7. Surface studies of plasma processed Nb samples

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, Puneet V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Doleans, Marc [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Hannah, Brian S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Afanador, Ralph [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Stewart, Stephen [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Mammosser, John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Howell, Matthew P [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Saunders, Jeffrey W [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Degraff, Brian D [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS); Kim, Sang-Ho [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)

    2015-01-01

    Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma-processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV.

  8. Combining geoelectrical and advanced lysimeter methods to characterize heterogeneous flow and transport under unsaturated transient conditions

    Science.gov (United States)

    Wehrer, M.; Skowronski, J.; Binley, A. M.; Slater, L. D.

    2013-12-01

    Our ability to predict flow and transport processes in the unsaturated critical zone is considerably limited by two characteristics: heterogeneity of flow and transience of boundary conditions. The causes of heterogeneous - or preferential - flow and transport are fairly well understood, yet the characterization and quantification of such processes in natural profiles remains challenging. This is due to current methods of observation, such as staining and isotope tracers, being unable to observe multiple events on the same profile and offering limited spatial information. In our study we demonstrate an approach to characterize preferential flow and transport processes applying a combination of geoelectrical methods and advanced lysimeter techniques. On an agricultural soil profile, which was transferred undisturbed into a lysimeter container, we applied systematically varied input flow boundary conditions, resembling natural precipitation events. We simultaneously measured the breakthrough of a conservative tracer. Flow and transport in the soil column were observed using electrical resistivity tomography (ERT), tensiometers, water content probes and a multicompartment suction plate (MSP). These techniques allowed a direct ground-truthing of soil moisture and pore fluid resistivity changes estimated noninvasively using ERT. We were able to image both the advancing infiltration front and the advancing tracer front using time lapse ERT. Water content changes associated with the advancing infiltration front dominated over pore fluid conductivity changes during short term precipitation events. Conversely, long term displacement of the solute front was monitored during periods of constant water content in between infiltration events. We observed preferential flow phenomena through ERT and through the MSP, which agreed in general terms. The preferential flow fraction was observed to be independent of precipitation rate. This suggests the presence of a fingering process

  9. Permafrost at its limits: The most easterly evidence of existing permafrost in the European Alps as indicated by ground temperature and geoelectrical measurements

    Science.gov (United States)

    Kellerer-Pirklbauer, A.; Kühnast, B.

    2009-04-01

    Mountain permafrost is a widespread phenomenon in alpine regions in the European Alps. For instance, some 2000 km² or 4% of the Austrian Alps are underlain by permafrost. Up to recent times most research on permafrost issues in Austria focused on the central and highest section of the Austrian Alps. By contrast, knowledge concerning marginal permafrost zones is fairly limited. To increase knowledge about the easternmost limit of permafrost in the European Alps, a research project focusing on the Seckauer Tauern Mountains (14°30'E to 15°00'E) and particularly on the Hochreichart area was initiated in 2004 by the first author. Since then, different methods have been applied such as e.g. geomorphic mapping, numerical permafrost modelling, multi-annual BTS measurements (since 2004) or continuous ground surface and near ground surface temperature measurements by miniature temperature data loggers/MTDs (since 2004). In order to verify the temperature data and to extend the spatial knowledge about permafrost distribution beyond point information, a geoelectrical survey was carried out at the end of August 2008 by applying the electrical resistivity tomography (ERT) method along a 120 m long profile covering the upper part of the rooting zone of a (more-or-less) relict rock glacier and the talus slope above. For this survey the two-dimensional (2D) electrical surveys was performed using the Wenner-Alfa configuration with 2.5 m spacing and an LGM-Lippmann 4-Punkt light hp resistivity-meter. The ERT results indicate an active layer of 2 to 4 m underlain by a permafrost body along 3/4 of the entire profile with resistivity values between 50 to 100 kOhm.m and extending to a depth of 10 to 15 m. The permafrost body is substantially thicker at the lower part of the profile (rock glacier; first 50 m of profile) compared to most of the upper part (talus slope). Focusing on the talus slope, the permafrost body is thickest on the central section of the profile (~5-6 m thickness

  10. Geo-Electrical Investigation for Groundwater Potential of Ihievbe ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2017-12-10

    Dec 10, 2017 ... magnetic, electromagnetic etc. Of all these methods, electrical resistivity method has been ... resistivity below the earth surface since the electrical resistivity of most rocks is dependent on the amount ... field curve which was eventually initially interpreted by partial curve matching to give an estimate of the.

  11. geo-electrical exploration for groundwater within the premises of ...

    African Journals Online (AJOL)

    2.2. Principle and Method. Electrical resistivity survey is usually designed to measure the electrical resistivity variation of the subsurface materials by making measurements at the earth surface. The common electrode arrays suitable for YES work are the Wenner and the Schlumberger arrays. Jn the Schlumberger array the.

  12. Geo-electrical investigation of Leachate Impact on Groundwater: A ...

    African Journals Online (AJOL)

    The results revealed the aquifer is characterized by low resistivity response generally below 4.5 ohm-m depicting possible contamination of the underlying aquifer from Oke-Odo landfill. The surface of the waste landfill is characterized by differential decomposition of waste as zones of advanced decomposition and fresh ...

  13. Lunar Surface Reactor Shielding Study

    International Nuclear Information System (INIS)

    Kang, Shawn; McAlpine, William; Lipinski, Ronald

    2006-01-01

    A nuclear reactor system could provide power to support long term human exploration of the moon. Such a system would require shielding to protect astronauts from its emitted radiations. Shielding studies have been performed for a Gas Cooled Reactor system because it is considered to be the most suitable nuclear reactor system available for lunar exploration, based on its tolerance of oxidizing lunar regolith and its good conversion efficiency. The goals of the shielding studies were to determine a material shielding configuration that reduces the dose (rem) to the required level in order to protect astronauts, and to estimate the mass of regolith that would provide an equivalent protective effect if it were used as the shielding material. All calculations were performed using MCNPX, a Monte Carlo transport code. Lithium hydride must be kept between 600 K and 700 K to prevent excessive swelling from large amounts of gamma or neutron irradiation. The issue is that radiation damage causes separation of the lithium and the hydrogen, resulting in lithium metal and hydrogen gas. The proposed design uses a layer of B4C to reduce the combined neutron and gamma dose to below 0.5Grads before the LiH is introduced. Below 0.5Grads the swelling in LiH is small (less than about 1%) for all temperatures. This approach causes the shield to be heavier than if the B4C were replaced by LiH, but it makes the shield much more robust and reliable

  14. Geo-Electrical Exploration for Groundwater within the Premises of University of Ilorin Teaching Hospital, Ilorin, Kwara State, Nigeria

    Directory of Open Access Journals (Sweden)

    A. K. Olawuyi

    2012-12-01

    Full Text Available Schlumberger Vertical Electrical Soundings for groundwater search within the premises of University of Ilorin Teaching Hospital (UITH situated along Ilorin- Jebba road in Kwara State, were carried out with a view to establishing the different subsurface geoelectric layers, the aquifer units and their hydrogeologic properties. Data were collected from 12 VES stations over an area of about 500 m x 650 m. From the quantitative interpretation of the data collected, using the usual method of curve matching with the Orellana-Mooney Master curves and 1-D forward modeling with WinResist 1.0 version software, four Hthologic units were identified. These include: the topsoil, the lateritic layer, the weathered layer/fractured layer and the fresh basement. The weathered and fractured basement constitutes the main aquifer units. The 2-D resistivity structure has elicited 2 lobes of low resistivity which constitutes the prospective zone for water in the area. The first lobe exists below stations 3 and 4 at about 5-15 m depth, with resistivity between 80- 147 ohm-m and over 300m wide, while the other lobe of low resistivity which also signifies a possible borehole location exists below stations 7,8 and 9 at a depth of about 2-14 m, with resistivity between 141-200 ohm-m and over 550 m wide. The study concluded that the area investigated contains two lobes of low resistivity which could be explored for water supply.

  15. [Comperative study of implant surface characteristics].

    Science.gov (United States)

    Katona, Bernadett; Daróczi, Lajos; Jenei, Attila; Bakó, József; Hegedus, Csaba

    2013-12-01

    The osseointegration between the implant and its' bone environment is very important. The implants shall meet the following requirements: biocompatibility, rigidity, resistance against corrosion and technical producibility. In our present study surface morphology and material characteristics of different implants (Denti Bone Level, Denti Zirconium C, Bionika CorticaL, Straumann SLA, Straumann SLA Active, Dentsply Ankylos and Biotech Kontact implant) were investigated with scanning electron microscopy and energy-dispersive X-ray spectroscopy. The possible surface alterations caused by the manufacturing technology were also investigated. During grit-blasting the implants' surface is blasted with hard ceramic particles (titanium oxide, alumina, calcium phosphate). Properties of blasting material are critical because the osseointegration of dental implants should not be hampered. The physical and chemical features of blasting particles could importantly affect the produced surfaces of implants. Titanium surfaces with micro pits are created after immersion in mixtures of strong acids. On surfaces after dual acid-etching procedures the crosslinking between fibrin and osteogenetic cells could be enhanced therefore bone formation could be directly facilitated on the surface of the implant. Nowadays there are a number of surface modification techniques available. These can be used as a single method or in combination with each other. The effect of the two most commonly used surface modifications (acid-etching and grit-blasting) on different implants are demonstrated in our investigation.

  16. Identification of subsurface layer with Wenner-Schlumberger arrays configuration geoelectrical method

    Science.gov (United States)

    Jamaluddin; Prasetyawati Umar, Emi

    2018-02-01

    One of measurement methods to investigate the condition of the subsurface is by using geoelectric method. This research uses wenner-Schlumberger arrays configuration geoelectrical method which is mapping resistivity that is commonly known as profiling (2D) in order to identify the lateral and vertical anomaly of material resistivity. 2D resistivity cross section is obtained from the result of data- processing on software Res2Dinv. The data were obtained along 70 m using Wenner-Schlumberger configuration with 5 m spaced electrode. The approximated value of resistivity obtained from the data processing ranged from 1000-1548 Ωm and with the iteration error 87.9%. Based on the geological map of Ujung Pandang sheet, the location of the research is an alluvium and coastal precipitation area with grain in forms of gravel, sand, clay, mud, and coral limestone. Thus, by observing and analyzing the variety of the resistivity cross-section from the inversion data, there are areas (a) showing resistivity values ranged from 0.1-0.2 Ωm which is estimated to be salt water intrusion based on the resistivity table of Earth materials, and region (b) which is a mixture of sand and clay material with the range of resistivity values between 1-1000 μm.

  17. Parametric time series analysis of geoelectrical signals: an application to earthquake forecasting in Southern Italy

    Directory of Open Access Journals (Sweden)

    V. Tramutoli

    1996-06-01

    Full Text Available An autoregressive model was selected to describe geoelectrical time series. An objective technique was subsequently applied to analyze and discriminate values above (below an a priorifixed threshold possibly related to seismic events. A complete check of the model and the main guidelines to estimate the occurrence probability of extreme events are reported. A first application of the proposed technique is discussed through the analysis of the experimental data recorded by an automatic station located in Tito, a small town on the Apennine chain in Southern Italy. This region was hit by the November 1980 Irpinia-Basilicata earthquake and it is one of most active areas of the Mediterranean region. After a preliminary filtering procedure to reduce the influence of external parameters (i.e. the meteo-climatic effects, it was demonstrated that the geoelectrical residual time series are well described by means of a second order autoregressive model. Our findings outline a statistical methodology to evaluate the efficiency of electrical seismic precursors.

  18. Electrochemical, surface analytical and quantum chemical studies ...

    Indian Academy of Sciences (India)

    The present study describes the inhibition of aluminium in 1N HNO3 with different concentrations of 1,2,4-triazole precursors ATD, BATD and DBATD using gravimetric method, potentiodynamic polarization studies (Tafel), electrochemical impedance spectroscopy (EIS), adsorption studies, surface morphological studies and ...

  19. A geo-electric and gravimetric survey in the delta of the rivers Fluvia and Muga (Gerona), Spain

    NARCIS (Netherlands)

    Geirnaert, W.

    1976-01-01

    In the delta of the rivers Fluvia and Muga, the Quaternary is hydrogeologically the most important deposit. It is underlain by Pliocene marls and clays. From geo-electrical soundings and bore-hole data a map with depth contours of the Quaternary-Pliocene boundary plane was constructed. Near the

  20. Surface studies of titania related nanostructures

    Science.gov (United States)

    Papageorgiou, Anthoula Chrysa

    In this thesis, surface sensitive techniques have been employed to investigate the surface chemistry of TiC>2. A bottom-up approach was used to grow ultra-thin films of rutile TiO2(110) on Ni(110). The surface structure of this system was probed using scanning tunnelling microscopy (STM) and low energy electron diffraction (LEED), whereas the electronic structure was characterised with soft X-ray photoelectron spectroscopy (SXPS). SXPS was also used to investigate the reactivity of this system towards water. While optimising the conditions for the growth of the desired titania phase, the growth of other structures commonly found in reduced native TiC>2 crystals were apparent from STM and LEED observations. The formation of 1x2 reconstructed TiO2(110) and crystallographic shear planes are reported. These phases are assigned by comparison with previous studies of analogous phases on the native rutile TiC>2(110) surface. STM was also used to monitor chemical reactions on native TiO2(110) surfaces. The reaction of surface bridging hydroxyl groups with molecular oxygen at room temperature was imaged directly. After exposure to O2, nearly all bridging hydroxyl groups are consumed, and new, mobile adsorbates appear with a range of apparent heights. With the support of calculations performed by Hofer's group in the University of Liverpool and Fisher's group in UCL, the adsorbates left on the surface after the reaction are assigned to neutral and charged oxygen adatoms as well as terminal hydroxyls. Finally, the surface local density of states of TiO2(110) were measured using scanning tunnelling spectroscopy. Energetically localised states are found at sample biases of +0.2 V, 0.7 V and 1.9 V. Additionally, a surface state at 1.9 V is localised spatially at two adjacent titanium five-fold atoms near to the positions of surface oxygen vacancies.

  1. The application of geoelectrical attributes based on crossed square array resistivity sounding data at 'Pudarske Kolibe' site in eastern Serbia

    Directory of Open Access Journals (Sweden)

    Sretenović Branislav B.

    2014-01-01

    Full Text Available Most of modern geophysical investigations routinely utilize seismic exploration method. 3D seismic and multiple seismic attributes enable the most complete definition of the local geological setting. This paper deals with utilization of crossed-square geoelectrical sounding method, which can be used for a 3D interpretation of resistivity sounding data as well as for defining additional geoelectrical attributes. With crossed-square array, we get a directional independent measurement and multiple geoelectrical attributes (ρm, ρx, n, θ and ξ. A more complete approach towards better interpretation is achieved with maps of five attributes: geometric mean apparent resistivity (ρm, average apparent resistivity (ρx apparent anisotropy coefficient (n, azimuth of the plane beddings (θ and a ratio of deviation from homogeneous anisotropic subsurface model (ξ. Multiple geoelectrical attribute maps correspond to depth of investigation of the array, like time and depth slices in seismic method. Horizontal resolution and the depth of investigation are controlled by the size and position of the array. Vertical resolution is, however, limited just like for the usage of any other electrode array in geoelectrical sounding. Combination of depth maps and profile maps enables a 3D interpretation similar to 3D cubes in seismic and recent software enables 3D modelling. The measurements using crossed square array were conducted at site 'Pudarske kolibe' in Eastern Serbia. The goal was to determine and separate 3D calcarinte bodies created in the depositional process, but also the eventual existence of electrical anisotropy in fluvial and shallow see water sediments. Results of investigations revealed the existence of electrical anisotropy with apparent anisotropy coefficient (n up to the value of 2 and, on the other hand, successfully delineated calcarenite bodies embedded in sedimentary formations present at investigated site.

  2. Analysis of ERT data of geoelectrical permafrost monitoring on Hoher Sonnblick (Austrian Central Alps)

    Science.gov (United States)

    Pfeiler, Stefan; Schöner, Wolfgang; Reisenhofer, Stefan; Ottowitz, David; Jochum, Birgit; Kim, Jung-Ho; Hoyer, Stefan; Supper, Robert; Heinrich, Georg

    2016-04-01

    In the Alps infrastructure facilities such as roads, routes or buildings are affected by the changes of permafrost, which often cause enormous reparation costs. Investigation on degradation of Alpine Permafrost in the last decade has increased, however, the understanding of the permafrost changes inducing its atmospheric forcing processes is still insufficient. Within the project ATMOperm the application of the geoelectrical method to estimate thawing layer thickness for mountain permafrost is investigated near the highest meteorological observatory of Austria on the Hoher Sonnblick. Therefore, it is necessary to further optimize the transformation of ERT data to thermal changes in the subsurface. Based on an innovative time lapse inversion routine for ERT data (Kim J.-H. et al 2013) a newly developed data analysis software tool developed by Kim Jung-Ho (KIGAM) in cooperation with the Geophysics group of the Geological Survey of Austria allows the statistical analysis of the entire sample set of each and every data point measured by the geoelectrical monitoring instrument. This gives on the one hand of course an enhanced opportunity to separate between „good" and „bad" data points in order to assess the quality of measurements. On the other hand, the results of the statistical analysis define the impact of every single data point on the inversion routine. The interpretation of the inversion results will be supplemented by temperature logs from selected boreholes along the ERT profile as well as climatic parameters. KIM J.-H., SUPPER R., TSOURLOS P. and YI M.-J.: Four-dimensional inversion of resistivity monitoring data through Lp norm minimizations. - Geophysical Journal International, 195(3), 1640-1656, 2013. Doi: 10.1093/gji/ggt324. (No OA) Acknowledgments: The geoelectrical monitoring on Hoher Sonnblick has been installed and is operated in the frame of the project ATMOperm (Atmosphere - permafrost relationship in the Austrian Alps - atmospheric extreme

  3. Geo-electrical investigation for groundwater potential of Ihievbe ...

    African Journals Online (AJOL)

    This study was carried out within Ihiebe Ogben community in Akoko Edo LGA, Nigeria to investigate the ground water potential of the Basement Complex rocks using Vertical Electrical Sounding (VES) that deploys Schlumberger Array configuration. Evaluation of hydrogeological parameters shows fractured/ weathered ...

  4. Geoelectric Investigation of Subsurface Structure of Academic Area ...

    African Journals Online (AJOL)

    Apparent Resistivity and Self Potential data were acquired from the study area using vertical electrical sounding technique about square grid of 100m size within the academic area of Old Campus of Bayero University, Kano, Nigeria. The area is located between Latitude 11059'00.7"N to 11058'49.2" N and Longitude ...

  5. Geo-Electrical Investigation for Groundwater Potential of Ihievbe ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2017-12-10

    Dec 10, 2017 ... ABSTRACT: This study was carried out within Ihiebe Ogben community in Akoko Edo LGA, Nigeria to investigate the ground water potential of the Basement Complex rocks using Vertical Electrical Sounding (VES) that deploys Schlumberger Array configuration. Evaluation of hydrogeological parameters ...

  6. A novel and generalized approach in the inversion of geoelectrical ...

    Indian Academy of Sciences (India)

    Corresponding author. e-mail: stanleyraj 84@yahoo.co.in. The non-linear apparent resistivity problem in the subsurface study of the earth takes into account the ... viz., resistivity and thickness (Kosinky and Kelly. 1981; Sri Niwas and Singhal 1981; Mazac et al. 1985; Yadav and Abolfazli 1998; Louis et al. 2002;. Batte et al.

  7. Aquifer Vulnerability Investigation Using Geoelectric Method in Parts ...

    African Journals Online (AJOL)

    The topsoil has resistivity values ranging from 43 to 1067Ωm and thickness varying from 0.8 to 1.6 m. ... The low value of the protective capacity makes the aquifer in the study area vulnerable to contamination especially hydrocarbon in the ... comprise several oil producing communities such as. Amukpe, Adagbrasa, etc, that ...

  8. A novel and generalized approach in the inversion of geoelectrical ...

    Indian Academy of Sciences (India)

    So a powerful tool is necessary to estimate the parameters. Several researches ... tool can be used. This research paper projects a novel and generalized approach for any case study- related problem and overwhelms the confined field area application. ..... controls the network to travel in the path of con- verging the results.

  9. Surface diffusion studies by optical diffraction techniques

    International Nuclear Information System (INIS)

    Xiao, X.D.

    1992-11-01

    The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect

  10. Groundwater resources evaluation in calcareous limestone using geoelectrical and VLF-EM surveys (El Salloum Basin, Egypt)

    Science.gov (United States)

    Zarif, Fardous; Slater, Lee; Mabrouk, Mohamed; Youssef, Ahmed; Al-Temamy, Ayman; Mousa, Salah; Farag, Karam; Robinson, Judy

    2018-01-01

    Understanding and developing groundwater resources in arid regions such as El Salloum basin, along the northwestern coast of Egypt, remains a challenging issue. One-dimensional (1D) electrical sounding (ES), two-dimensional (2D) electrical resistivity imaging (ERI), and very low frequency electromagnetic (VLF-EM) measurements were used to investigate the hydrogeological framework of El Salloum basin with the aim of determining the potential for extraction of potable water. 1D resistivity sounding models were used to delineate geoelectric sections and water-bearing layers. 2D ERI highlighted decreases in resistivity with depth, attributed to clay-rich limestone combined with seawater intrusion towards the coast. A depth of investigation (DOI) index was used to constrain the information content of the images at depths up to 100 m. The VLF-EM survey identified likely faults/fractured zones across the study area. A combined analysis of the datasets of the 1D ES, 2D ERI, and VLF-EM methods identified potential zones of groundwater, the extent of seawater intrusion, and major hydrogeological structures (fracture zones) in El Salloum basin. The equivalent geologic layers suggest that the main aquifer in the basin is the fractured chalky limestone middle Miocene) south of the coastal plain of the study area. Sites likely to provide significant volumes of potable water were identified based on relatively high resistivity and thickness of laterally extensive layers. The most promising locations for drilling productive wells are in the south and southeastern parts of the region, where the potential for potable groundwater increases substantially.

  11. MAPPING SUBSURFACE FORMATIONS ON THE EASTERN RED SEA COAST IN JORDAN USING GEOELECTRICAL TECHNIQUES: GEOLOGICAL AND HYDROGEOLOGICAL IMPLICATIONS

    Directory of Open Access Journals (Sweden)

    Batayneh Awni T.

    2007-12-01

    Full Text Available During 2006, geoelectrical measurements using the vertical electrical sounding (VES method were conducted on the eastern Red Sea coast in Jordan, using the SYSCAL-R2 resistivity instrument.
    The objectives of the study were (i to evaluate the possibility of mapping of Quaternary sediments medium in areas where little is known about the subsurface geology and to infer shallow geological
    structure from the electrical interpretation, and (ii to identify formations that may present fresh aquifer waters, and subsequently to estimate the relationship between groundwater resources and geological structures. Data collected at 47 locations were interpreted first with curve matching techniques, using theoretically calculated master curves, in conjunction with the auxiliary curves. The initial earth
    models were second checked and reinterpreted using a 1-D inversion program (i.e., RESIX-IP in order to obtain final earth models. The final layer parameters (thicknesses and resistivities were then
    pieced together along survey lines to make electrical cross sections. Resistivity measurements show a dominant trend of decreasing resistivity (thus increasing salinity with depth and westward toward
    the Red Sea. Accordingly, three zones with different resistivity values were detected, corresponding to three different bearing formations: (i a water-bearing formation in the west containing Red Sea saltwater; (ii a transition zone of clay and clayey sand thick formation; (iii stratas saturated with fresh groundwater in the east disturbed by the presence of clay and clayey sand horizons. Deep borehole (131 m drilled in the northwestern part of the study area for groundwater investigation, has
    confirmed the findings of the resistivity survey.

  12. Study Paths, Riemann Surfaces, and Strebel Differentials

    Science.gov (United States)

    Buser, Peter; Semmler, Klaus-Dieter

    2017-01-01

    These pages aim to explain and interpret why the late Mika Seppälä, a conformal geometer, proposed to model student study behaviour using concepts from conformal geometry, such as Riemann surfaces and Strebel differentials. Over many years Mika Seppälä taught online calculus courses to students at Florida State University in the United States, as…

  13. Surface and Interface Studies with Radioactive Ions

    CERN Multimedia

    Weber, A

    2002-01-01

    Investigations on the atomic scale of magnetic surfaces and magnetic multilayers were performed by Perturbed Angular Correlation (PAC) spectroscopy. The unique combination of the Booster ISOLDE facility equipped with a UHV beamline and the UHV chamber ASPIC (Apparatus for Surface Physics and Interfaces at CERN) is ideally suited for such microscopic studies. Main advantages are the choice of problem-oriented radioactive probes and the purity of mass-separated beams. The following results were obtained: $\\,$i) Magnetic hyperfine fields (B$_{hf}$) of Se on Fe, Co, Ni surfaces were determined. The results prompted a theoretical study on the B$_{hf}$ values of the 4sp-elements in adatom position on Ni and Fe, confirming our results and predicting unexpected behaviour for the other elements. $\\,$ii) Exemplarily we have determined B$_{hf}$ values of $^{111}$Cd at many different adsorption sites on Ni surfaces. We found a strong dependence on the coordination number of the probes. With decreasing coordination nu...

  14. Investigating the temporal fluctuations in geoelectrical and geochemical signals Jointly measured in a seismic area of Southern Apennine chain (Italy

    Directory of Open Access Journals (Sweden)

    S. Piscitelli

    2001-06-01

    Full Text Available We analyse geoelectrical and geochemical time series jointly measured by means of a multiparametric automatic station close to an anomalous fluid emission in Val d'Agri (Basilicata, Southern Italy. In the investigated are some destructive seismic events occurred in past and recent years. We analysed the temporal fluctuations of the signals by spectral tools. We detected scaling behaviours in the power spectra of the time series recorded, that are typical fingerprints of fractional Brownian motions. The estimated values of the spectral indices reveal the presence of antipersistent behaviour in the time dynamics of all geoelectrical and geochemical data recorded. This work intends to improve our knowledge of the inner time dynamics of geophysical non-seismometric parameters.

  15. Assessing the geo-electric characteristics of Basement Complex rocks and its implication for groundwater prospecting in Ilorin Metropolis, Nigeria

    Directory of Open Access Journals (Sweden)

    I. P. Ifabiyi

    2016-12-01

    Full Text Available In Basement Complex rocks where rainfall is seasonal, water provision in dry season depends on regolith aquifer. For effective exploitation of groundwater resources, it is reasonable that geophysical investigation be conducted before development of well. In many instances, geophysical surveys may be expensive or nonexistent. Hence, there is a need for spatial analysis which might advise water engineers within such environments. Vertical Electrical Soundings (VES data of 53 locations conducted with ABEM SAS-1000 terrameter using Schlumberger electrode configuration were obtained from the hydrogeology Department of Kwara state Ministry of Water Resources and Lower Niger River Basin and Rural Development Authority, Ilorin. VES locational coordinates were recorded using handheld GPS device. Sound curves were evaluated by partial curve matching approach and computer iteration using WinResist. The results depict six geo-electric regional successions, namely: top soil, lateritic clay, weathered basement, fairly-hard basement, thin fractured and hard basement. The geo-electric succession identified was plotted in Surfer 12 environment, using kriging interpolation method to show spatial distribution pattern of this zone. The spatial pattern is expected to give an insight to the nature of spatial variability of geo-electric layers and assist drillers as well as water resources policy makers in their operations.

  16. Study Paths, Riemann Surfaces And Strebel Differentials

    OpenAIRE

    Buser, Peter; Semmler, Klaus-Dieter

    2017-01-01

    These pages aim to explain and interpret why the late Mika Seppälä, a conformal geometer, proposed to model student study behaviour using concepts from conformal geometry, such as Riemann surfaces and Strebel differentials. Over many years Mika Seppälä taught online calculus courses to students at Florida State University in the United States, as well as students at the University of Helsinki in Finland. Based on the click log data of his students in both populations, he monitored this course...

  17. Study of Planar Surface Wave Excited Plasma

    Science.gov (United States)

    Tian, Caizhong

    2008-10-01

    The need for plasma processing has increased as miniaturization in semiconductor manufacturing goes ahead. In these processes, a large-diameter plasma source is required with respect to 300mm wafer size. A Radial Line Slot Antenna (RLSA) driven surface-wave-sustained plasma is a potential best candidate to various applications with respect to damage free process. Many researches focus on the control of plasma density and electron temperature in RLSA technique. However, the plasma stability and uniformity control are less implemented in the practice. In recent years, we study sheath formation and plasma behavior at the interface, where the surface wave propagate, by using electromagnetic particle-in-cell simulation techniques. The simulations include the effects of ionization, and allow us to study the buildup of plasma density associated with ionization in the presence of the large fields of the RF-enhanced sheath. Our results show both the mechanism of plasma generation and heating at the plasma dielectric interface and the strong effect on geometric design of dielectric. Various scenarios are of interest, and help us to design an optimal RLSA driven plasma source, where the plasma stability and uniformity are firmly sustained under the various process conditions. Plasma diagnosis is carried out to reveal the more essential difference in plasma behavior between our RLSA and a custom inductively coupled plasma (ICP) source.

  18. A KINEMATIC STUDY OF FINSWIMMING AT SURFACE

    Directory of Open Access Journals (Sweden)

    Pier-Giorgio Zanone

    2004-06-01

    Full Text Available Finswimming is a sport of speed practiced on the surface or underwater, in which performance is based on whole-body oscillations. The present study investigated the undulatory motion performed by finswimmers at the surface. This study aiming to analyze the influence of the interaction of gender, practice level, and race distance on selected kinematic parameters. Six elite and six novices finswimmers equipped with joints markers (wrist, elbow, shoulder, hip, knee, and ankle were recorded in the sagittal plane. The position of these anatomical marks was digitized at 50 Hz. An automated motion analysis software yielded velocity, vertical amplitude, frequency, and angular position. Results showed that stroke frequency decreased whereas the mean amplitude of all joints increased with increasing race distance (p < 0.01. Mean joint amplitude for the upper limbs (wrist, elbow and shoulder was smaller for experts than for novices. Whereas that of the ankle was larger, so that the oscillation amplitude increased from shoulder to ankle. Elite male finswimmers were pitching more acutely than female. Moreover, elite male finswimmers showed a smaller knee bending than novices and than elite females (p < 0.01. This indicated that elite male finswimmers attempt to reduce drag forces thanks to a weak knee bending and a low upper limbs pitch. To sum up, gender, expertise, and race distance affect the performance and its kinematics in terms frontal drag. Expertise in finswimming requires taking advantage of the mechanical constraints pertaining to hydrodynamic constraints in order to optimize performance

  19. Application of geoelectric methods for man-caused gas deposit mapping and monitoring

    Science.gov (United States)

    Yakymchuk, M. A.; Levashov, S. P.; Korchagin, I. N.; Syniuk, B. B.

    2009-04-01

    The rather new application of original geoelectric methods of forming of short-pulsed electromagnetic field (FSPEF) and vertical electric-resonance sounding (VERS) (FSPEF-VERS technology) (Levashov et al., 2003; 2004) is discussed. In 2008 the FSPEF-VERS methods were used for ascertaining the reasons of serious man-caused accident on gas field. The emission of water with gas has occurred near an operational well on one gas field. The assumption was discussed, that some part of gas from producing horizons has got into the upper horizons, in aquiferous stratum layers. It promoted creation of superfluous pressure in aquiferous stratums which has led to accident on the field. Operative geophysical investigations within an accident site were carried out by FSPEF and VERS geoelectric methods on 07.10.08 and 13.10.08 on the first stage. The primary goal of executed works was detection and mapping of gas penetration zones in aquiferous stratums of cross-section upper part, and also the determination of bedding depths and a total area of distribution of gas in upper aquiferous stratums. The anomalous zone were revealed and mapped by FSPEF survey. It is caused by raised migration of water in upper horizons of a cross-section. The depths of anomalous polarized layers (APL) of "gas" and „aquiferous stratum" type were defined by VERS method. The VERS data are presented by sounding diagram's and columns, by vertical cross-sections lengthways and transversely of gas penetration zones, by map of thicknesses of man-caused gas "deposit". The perforation on depths of 450 and 310 m was spent in a producing borehole on the first day investigation data. Gas discharges were received from 450 and 310 m depths. Three degassing boreholes have been drilled on 08.11.08 working day. Depths of wells are about 340 m. Gas inflows were received from 330 m depth. Drilling of fourth well was conducted. The anomalous zone area has decreased twice in comparison with two previous surveys. So, the

  20. Geoelectric monitoring of bentonite barrier resaturation in the Aespoeprototype repository. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Wieczorek, Klaus; Komischke, Michael; Miehe, Ruediger; Moog, Helge

    2014-10-15

    In 1994, SKB started constructing the ''Prototype Repository'', a full-scale replica of a part of a future KBS-3 repository in crystalline rock, at the AespoeHard Rock Laboratory. Six emplacement boreholes were planned and constructed in two tunnel sections until end of 1999. The international EC co-funded Prototype Repository project was started in 2000 (contract FIKW-CT-2000-00055). The project partners were SKB (Sweden), POSIVA (Finland), ENRESA (Spain), GRS (Germany), BGR (Germany), UWC (UK), and JNC (Japan). Between 2000 and 2003 the complete Prototype Repository was equipped and instrumented, and monitoring was started. In February 2004 the EC funding expired. The Prototype Repository project was continued with national funding of the project partners. In 2011, dismantling of Section II was started in a three-year project. Backfill, buffer and canisters as well as part of the instrumentation were retrieved, and numerous laboratory investigations on buffer and backfill samples were performed. GRS' part in the Prototype Repository was the monitoring of backfill and buffer resaturation using geoelectric tomography. The measurements were completed in 2013.

  1. Geoelectrical characterization of carbonate and silicate porous media in the presence of supercritical CO2-water flow

    Science.gov (United States)

    Abidoye, Luqman Kolawole; Das, Diganta Bhusan

    2015-10-01

    The relative permittivity (εr) and the electrical conductivity (σ) of porous media are known to be functions of water saturation (S). As such, their measurements can be useful in effective characterisations and monitoring of geological carbon sequestration using geoelectrical measurement techniques. In this work, the effects of pressure, temperature and salt concentration on bulk εr-S and σ-S relationships were investigated for carbonate (limestone) and silicate porous media (both unconsolidated domains) under dynamic and quasi-static supercritical CO2 (scCO2)-brine/water flow. In the silica sand sample, the bulk εr (εb) for scCO2-water decreases as the temperature increases. On the contrary, slight increase was seen in the εb with temperature in the carbonate sample for the scCO2-water system. These trends are more conspicuous at high water saturation. The εb-S curves for the scCO2-water flow in the silica sand also show clear dependency on the domain pressure, where εb increases as the domain pressure increases. Furthermore, the bulk σ (σb), at any particular saturation for the scCO2-brine system rises as the temperature increases with more significant increase found at very high water saturation. Both εb and σb values are found to be greater in the limestone than silica sand porous samples for similar porosity values. Based on different injection rates investigated, we do not find significant dynamic effects in the εb-S and σb-S relationships for the scCO2-brine/water system. As such, geoelectrical characteristics can be taken as reliable in the monitoring of two-phase flow system in the porous media. It can be inferred from the results that the geoelectrical techniques are highly dependent on water saturation. This dependence is more conspicuous at higher water saturation. Different mathematical models examined show their reliability at different water saturation ranges. The polynomial fit developed in this work takes into consideration the fluid

  2. Numerical modelling of CO2 migration in saline reservoirs using geoelectric and seismic techniques - first results

    Science.gov (United States)

    Hagrey, S. A. Al; Strahser, M. H. P.; Rabbel, W.

    2009-04-01

    The research project "CO2 MoPa" (modelling and parameterisation of CO2 storage in deep saline formations for dimensions and risk analysis) has been initiated in 2008 by partners from different disciplines (e.g. geology, hydrogeology, geochemistry, geophysics, geomechanics, hydraulic engineering and law). It deals with the parameterisation of virtual subsurface storage sites to characterise rock properties, with high pressure-temperature experiments to determine in situ hydro-petrophysical and mechanical parameters, and with modelling of processes related to CCS in deep saline reservoirs. One objective is the estimation of the sensitivity and the resolution of reflection seismic and geoelectrical time-lapse measurements in order to determine the underground distribution of CO2. Compared with seismic, electric resistivity tomography (ERT) has lower resolution, but its permanent installation and continuous monitoring can make it an economical alternative or complement. Seismic and ERT (in boreholes) applications to quantify changes of intrinsic aquifers properties with time are justified by the velocity and resistivity decrease related to CO2 injection. Our numerical 2D/3D modelling reveals the capability of the techniques to map CO2 plumes and changes as a function of thickness, concentration, receiver/electrode configuration, aspect ratio and modelling and inversion constraint parameters. Depending on these factors, some configurations are favoured due to their better spatial resolution and lower artefacts. Acknowledgements This work has been carried out in the framework of "CO2 MoPa" research project funded by the Federal German Ministry of Education and Research (BMBF) and a consortium of energy companies (E.ON Energy, EnBW AG, RWE Dea AG, Stadtwerke Kiel AG, Vattenfall Europe Technology Research GmbH and Wintershall Holding AG).

  3. Study the Postbuckling of Hexagonal Piezoelectric Nanowires with Surface Effect

    Directory of Open Access Journals (Sweden)

    O. Rahmani

    2014-04-01

    Full Text Available Piezoelectric nanobeams having circular, rectangular and hexagonal cross-sections are synthesized and used in various Nano structures; however, piezoelectric nanobeams with hexagonal cross-sections have not been studied in detail. In particular, the physical mechanisms of the surface effect and the role of surface stress, surface elasticity and surface piezoelectricity have not been discussed thoroughly. The present study investigated post-buckling behavior of piezoelectric nanobeams by examining surface effects. The energy method was applied to post-buckling of hexagonal nanobeams and the critical buckling voltage and amplitude are derived analytically from bulk and surface material properties and geometric factors.

  4. Target studies for surface muon production

    Directory of Open Access Journals (Sweden)

    F. Berg

    2016-02-01

    Full Text Available Meson factories are powerful drivers of diverse physics programs. With beam powers already in the MW-regime attention has to be turned to target and beam line design to further significantly increase surface muon rates available for experiments. For this reason we have explored the possibility of using a neutron spallation target as a source of surface muons by performing detailed Geant4 simulations with pion production cross sections based on a parametrization of existing data. While the spallation target outperforms standard targets in the backward direction by more than a factor 7 it is not more efficient than standard targets viewed under 90°. Not surprisingly, the geometry of the target plays a large role in the generation of surface muons. Through careful optimization, a gain in surface muon rate of between 30% and 60% over the standard “box-like” target used at the Paul Scherrer Institute could be achieved by employing a rotated slab target. An additional 10% gain could also be possible by utilizing novel target materials such as, e.g., boron carbide.

  5. Synchrotron x-ray diffraction study of liquid surfaces

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Pershan, P.S.

    1983-01-01

    A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented.......A spectrometer for X-ray diffraction and refraction studies of horizontal, free surfaces of liquids is described. As an illustration smetic-A layering at the surface of a liquid crystal is presented....

  6. Application of 2-D geoelectrical resistivity tomography for mountain permafrost detection in sporadic permafrost environments: Experiences from Eastern Austria

    Science.gov (United States)

    Kellerer-Pirklbauer, Andreas

    2015-04-01

    Mountain permafrost covers some 2000 km² of the Austrian Alps which is less than 2.5% of the national territory. Delineating the altitudinal lower limit of permafrost in the mountains of Austria is difficult due the complex topography, the rather sparseness of field verification data and the lack of long-term permafrost monitoring data. Such monitoring data should cover different slope aspects, different elevations, different substrates and different mountain regions of Austria. In this study it was attempted to delineate the lower limit of permafrost at two study sites in the Tauern Range, Austria, applying two-dimensional geoelectrical resistivity tomography (ERT). In addition, multi-annual ground temperature data collected by miniature temperature datalogger (MDT) were used to validate the results. At the study site Hochreichart (maximum elevation 2416 m asl), located in the Seckauer Tauern Range, 14 ERT profiles (lengths 48-196 m; electrode spacing 2, 2.5 or 4 m) were measured at elevations between 1805 and 2416 m asl. Measurements were carried out at two cirques (Reichart, Schöneben) and at the summit plateau of Hochreichart. Results at this site indicate that permafrost lenses are detectable at elevations down to c.1900 m asl at radiation-sheltered sites. Furthermore, at the summit plateau permafrost only occurs as rather small lenses. The ERT-based permafrost pattern is generally confirmed by the MTD data with negative mean annual ground temperature values at only a few monitoring sites. However, the possibility of air-filled cavities causing higher resistive zones faking permafrost existence cannot be excluded because coarse-grained sediments (i.e. relict rock glaciers and autochthonous block fields) are widespread at this study site. At the second study site Kögele Cirque (maximum elevation 3030 m asl) located in the Schober Mountains 12 ERT profiles (lengths 48 m; electrode spacing 2 m) were measured at elevations between 2631 and 2740 m asl. Spatially

  7. Reduction Of Geomagnetic Effects (Periods T < 1000 s) From Geomagnetic And Geoelectrical Potential Difference Data

    Science.gov (United States)

    Harada, M.; Hattori, K.; Takahashi, I.; Hayakawa, M.; Nagao, T.; Uyeda, S.

    2004-12-01

    variations at the site provide only regional and local variations and earthquake-related phenomena are included. Generally, ISTF approaches were based on the conventional Fourier transform, but we use the wavelet transform due to existence of transient changes. In this paper, the proposed method has been applied to the data observed at the sites in Boso Peninsula, Japan and we use geomagnetic data observed at Kakioka Magnetic Observatory, Japan Meteorological Agency, as the remote reference data. We applied the proposed method to the geomagnetic and geoelectrical potential data to evaluate the elimination of global geomagnetic changes and their inductive fields in the frequency range of 0.001 to 1 Hz. The obtained performance is found to be quite good and changes associated with geomagnetic pulsations are effectively eliminated.

  8. Geoelectrical properties of peat in a northern peatland: Implications for peat basin formation, vegetation patterning, pool formation, and carbon gas evaluation

    Science.gov (United States)

    Comas, Xavier

    2005-11-01

    Peatlands are unique ecosystems that represent major terrestrial stores of soil carbon. Peatlands are important sources of atmospheric methane but their response to global warming still presents major uncertainties. A better understanding of the geoelectrical properties of peat and the in-situ formation of surficial features in peatlands can improve the current knowledge of the hydrology, nutrient dynamics, stratigraphy, and biogenic gas accumulation in peatlands. Geophysical techniques and hydrological measurements at the laboratory scale are used to examine the low-frequency properties of peat. At the field scale, geophysical and hydrological data are combined to investigate peat basin formation, vegetation and pool patterning, and biogenic gas accumulations in the central unit of Caribou Bog, a peatland in central Maine. In Chapter 2, hydraulic conductivity measurements demonstrate the effect of pore dilation in peat samples, invalidating Archie's Law. An empirical model relating the resistivity and induced polarization (IP) measurements to fluid conductivity in peat is developed, and shows potential to predict pore fluid conductivity and changes in vertical hydraulic conductivity in peatlands. In Chapter 3, resistivity and surface ground penetrating radar (GPR) data suggest that underlying stratigraphy exerts a primary control on vegetation and pool patterning, and present unique evidence of the convergence of a raised bog originated in two separated basins into a single bog A conceptual model for basin formation and peatland development in Caribou Bog is presented. In Chapter 4, surface GPR and terrain conductivity (EM31) surveys combined with direct core sampling indicate correlation between the location of open pools and elevated mineral soil surfaces (interpreted as esker deposits). A conceptual model based on a beaded esker system containing multiple ridges is developed to explain the formation of pools in Caribou Bog. In Chapter 5, areas of EM wave

  9. Theoretical studies of potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Harding, L.B. [Argonne National Laboratory, IL (United States)

    1993-12-01

    The goal of this program is to calculate accurate potential energy surfaces (PES) for both reactive and nonreactive systems. To do this the electronic Schrodinger equation must be solved. Our approach to this problem starts with multiconfiguration self-consistent field (MCSCF) reference wavefunctions. These reference wavefunctions are designed to be sufficiently flexible to accurately describe changes in electronic structure over a broad range of geometries. Electron correlation effects are included via multireference, singles and doubles configuration interaction (MRSDCI) calculations. With this approach, the authors are able to provide useful predictions of the energetics for a broad range of systems.

  10. Penyelidikan Zona Akuifer dengan Survei Pendugaan Geolistrik Metode Schlumberger Studi Kasus Daerah Kecamatan Kaliwungu dan Sekitarnya, Kabupaten Kendal, Jawa Tengah

    OpenAIRE

    Nasution, Enda Mora

    2013-01-01

    Morphological differences research area affect to subsurface conditions. To determine subsurface conditions and hydrogeological conditions of the study area, then conducted research with geoelectric method.Geoelectric is a geophysical method used to determine geological subsurface conditions based on the variation of the resistivity of the rock types. Research area is located in Kaliwungu, Kendal Regency, Central Java. This area consisted by Damar Formation (QTd) and Alluvium Deposits (Qal). ...

  11. Surface areas of fractally rough particles studied by scattering

    International Nuclear Information System (INIS)

    Hurd, A.J.; Schaefer, D.W.; Smith, D.M.; Ross, S.B.; Le Mehaute, A.; Spooner, S.

    1989-01-01

    The small-angle scattering from fractally rough surfaces has the potential to give information on the surface area at a given resolution. By use of quantitative neutron and x-ray scattering, a direct comparison of surface areas of fractally rough powders was made between scattering and adsorption techniques. This study supports a recently proposed correction to the theory for scattering from fractal surfaces. In addition, the scattering data provide an independent calibration of molecular adsorbate areas

  12. A magnetotelluric study of the sensitivity of an area to seismoelectric signals

    Directory of Open Access Journals (Sweden)

    G. Balasis

    2005-01-01

    Full Text Available During recent years, efforts at better understanding the physical properties of precursory ultra-low frequency pre-seismic electric signals (SES have been intensified. Experiments show that SES cannot be observed at all points of the Earth's surface but only at certain so-called sensitive sites. Moreover, a sensitive site is capable of collecting SES from only a restricted number of seismic areas (selectivity effect. Therefore the installation of a permanent station appropriate for SES collection should necessarily be preceded by a pilot study over a broad area and for a long duration. In short, a number of temporary stations are installed and, after the occurrence of several significant earthquakes (EQs from a given seismic area, the most appropriate (if any of these temporary stations, in the sense that they happen to collect SES, can be selected as permanent. Such a long experiment constitutes a serious disadvantage in identifying a site as SES sensitive. However, the SES sensitivity of a site should be related to the geoelectric structure of the area that hosts the site as well as the regional geoelectric structure between the station and the seismic focal area. Thus, knowledge of the local and regional geoelectric structure can dramatically reduce the time involved in identifying SES sites. In this paper the magnetotelluric method is used to investigate the conductivity structure of an area where a permanent SES station is in operation. Although general conclusions cannot be drawn, the area surrounding an SES site near Ioannina, Greece is characterized by: (1 major faults in the vicinity; (2 highly resistive structure flanked by abrupt conductivity contrasts associated with large-scale geologic contacts, and (3 local inhomogeneities in conductivity structure. The above results are consistent with the fact that electric field amplitudes from remotely-generated signals should be appreciably stronger at such sites when compared to neighboring

  13. A magnetotelluric study of the sensitivity of an area to seismoelectric signals

    Science.gov (United States)

    Balasis, G.; Bedrosian, P.A.; Eftaxias, K.

    2005-01-01

    During recent years, efforts at better understanding the physical properties of precursory ultra-low frequency pre-seismic electric signals (SES) have been intensified. Experiments show that SES cannot be observed at all points of the Earth's surface but only at certain so-called sensitive sites. Moreover, a sensitive site is capable of collecting SES from only a restricted number of seismic areas (selectivity effect). Tberefore the installation of a permanent station appropriate for SES collection should necessarily be preceded by a pilot study over a broad area and for a long duration. In short, a number of temporary stations are installed and, after the occurrence of several significant earthquakes (EQs) from a given seismic area, the most appropriate (if any) of these temporary stations, in the sense that they happen to collect SES, can be selected as permanent. Such a long experiment constitutes a serious disadvantage in identifying a site as SES sensitive. However, the SES sensitivity of a site should be related to the geoelectric structure of the area that hosts the site as well as the regional geoelectric structure between the station and the seismic focal area. Thus, knowledge of the local and regional geoelectric structure can dramatically reduce the time involved in identifying SES sites. hi this paper the magnetotelluric method is used to investigate the conductivity structure of an area where a permanent SES station is in operation. Although general conclusions cannot be drawn, the area surrounding an SES site near Ioannina, Greece is characterized by: (1) major faults in the vicinity; (2) highly resistive structure flanked by abrupt conductivity contrasts associated with large-scale geologic contacts, and (3) local inhomogeneities in conductivity structure. The above results are consistent with the fact that electric field amplitudes from remotely-generated signals should be appreciably stronger at such sites when compared to neighboring sites

  14. Study of environmental degradation of silver surface

    Energy Technology Data Exchange (ETDEWEB)

    Aguas, H.; Silva, R.J.C.; Viegas, M.; Pereira, L.; Fortunato, E.; Martins, R. [Materials Science Department, CENIMAT/I3N, FCT-UNL, Campus de Caparica (Portugal)

    2008-05-15

    To evaluate the evolution of a dark film formation on silver surface objects, several coupons were catalogued and place inside a museum, located in an urban area. The changes on these samples were measured by spectroscopic ellipsometry, in periods of months. This technique allows the reduction of the coupons exposure time, in several months, due to its high sensitivity to surface modifications, with acceptable results for the evaluation of its degradation. The thicknesses of the degradation layers and the optical properties of silver oxide, chloride and sulphide reference samples were determined using a mixture of Tauc-Lorentz and Drude models. The composition of the silver corrosion layer was determined by fitting the layer using a Bruggeman Effective Medium Approximation (BEMA) of the three products plus voids. It was found that the thickness of the layer depends in the placement of the coupons, namely, inside or outside displayers. The average film thickness after 6 months was of 180 Aa and 280 Aa, inside and outside the displayers, respectively. The main compounds found in the layers were the silver chlorides and sulphides, which composition changed with the thickness of the layer, and the exposition time. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Surface studies of oil-seal degradation

    Science.gov (United States)

    Smith, G. C.; Park, D.; Titchener, K. J.; Davies, R. E.; West, R. H.

    1995-11-01

    Fluoroelastomers are frequently used as engine oil-seal materials. Under certain test conditions specific fluoroelastomers may show degradation of mechanical properties. A range of fluoroelastomers of different chemical composition have been aged in simple oil/additive blends and in oil formulations equivalent to commercial blends. These were then examined using XPS, SEM/EPMA and XRD to elucidate the physical and chemical changes associated with degradation. The interaction is shown to proceed through amine catalysed post-curing of the constituent polymers. These reactions promote defluorination, embrittlement and cracking of elastomers with a consequent decline in tensile properties as fracture failure mechanisms dominate performance. Degradation of these materials was found, even in the most extreme case, to be limited to the near-surface region of the samples, to a depth of less than approximately 50 μm. Degradation was reduced in elastomers with a higher fluorine level, higher terpolymer content, and a greater extent of cross-linking.

  16. Lunar surface structural concepts and construction studies

    Science.gov (United States)

    Mikulas, Martin

    The topics are presented in viewgraph form and include the following: lunar surface structures construction research areas; lunar crane related disciplines; shortcomings of typical mobile crane in lunar base applications; candidate crane cable suspension systems; NIST six-cable suspension crane; numerical example of natural frequency; the incorporation of two new features for improved performance of the counter-balanced actively-controlled lunar crane; lunar crane pendulum mechanics; simulation results; 1/6 scale lunar crane testbed using GE robot for global manipulation; basic deployable truss approaches; bi-pantograph elevator platform; comparison of elevator platforms; perspective of bi-pantograph beam; bi-pantograph synchronously deployable tower/beam; lunar module off-loading concept; module off-loader concept packaged; starburst deployable precision reflector; 3-ring reflector deployment scheme; cross-section of packaged starburst reflector; and focal point and thickness packaging considerations.

  17. Oxidation of clean silicon surfaces studied by four-point probe surface conductance measurements

    DEFF Research Database (Denmark)

    Petersen, Christian Leth; Grey, Francois; Aono, M.

    1997-01-01

    We have investigated how the conductance of Si(100)-(2 x 1) and Si(111)-(7 x 7) surfaces change during exposure to molecular oxygen. A monotonic decrease in conductance is seen as the (100) surfaces oxidizes. In contract to a prior study, we propose that this change is caused by a decrease in sur...

  18. Self-organization of decaying surface corrugations: a numerical study.

    Science.gov (United States)

    Bonito, Andrea; Nochetto, Ricardo H; Quah, John; Margetis, Dionisios

    2009-05-01

    We study numerically the interplay of surface topography and kinetics in the relaxation of crystal surface corrugations below roughening in two independent space dimensions. The kinetic processes are isotropic diffusion of adatoms across terraces and attachment-detachment of atoms at steps. We simulate the corresponding anisotropic partial differential equation for the surface height via the finite element method. The numerical results show a sharp transition from initially biperiodic surface profiles to one-dimensional surface morphologies. This transition is found to be enhanced by an applied electric field. Our predictions demonstrate the dramatic influence on morphological relaxation of geometry-induced asymmetries in the adatom fluxes transverse and parallel to step edges.

  19. Surface study of fusion research in universities linkage organization

    International Nuclear Information System (INIS)

    Miyahara, Akira.

    1980-04-01

    The surface studies for nuclear fusion research consist of the studies on the surface process and the surface damage. The problems with the surface study are different at different research stages. The plasma-wall interaction in the ignition stage is mainly concerned with heating. The impurity control becomes important in the breakeven stage. In the longer burn experiment, the problems of plasma contamination and ash accumulation are serious, and the blistering is also a problem. From the reactor aspect, the reduction of life of wall due to the irradiation of high fluence must be considered. The surface damage due to plasma disruption is a very big problem. The activities concerning the surface studies in university-linked organizations are the surface characterization for fusion reactor materials by low energy ion scattering spectroscopy, the high power ion irradiation test for CTR first wall, data compilation on plasma-wall interaction, the studies of sputtering process and surface coating, and the study on hydrogen isotope permeation through metals for fusion reactors. Other activities such as the sample characterization at many universities using the SUS 304 samples from the same lot, and the collaboration works on JIPP-T-2 plasma wall experiments are introduced. Concerning the surface study, US-Japan or international collaboration are strongly expected. (Kato, T.)

  20. Joint interpretation of geoelectrical and soil-gas measurements for monitoring CO2 releases at a natural analogue

    DEFF Research Database (Denmark)

    Sauer, U.; Watanabe, N.; Singh, Ashok

    2014-01-01

    and flux measurements, self-potential (SP) and geoelectrical surveys) showed that the combination of geophysical methods with soil-gas analysis for mesoscale monitoring of the shallow subsurface above geologic CO2 storages can be a valuable tool for mapping and monitoring potential CO2 spread......The development and validation of hierarchic monitoring concepts is essential for detecting and assessing possible leakages from storage formations, especially for carbon capture and storage (CCS) applications. Joint interpretation of various techniques (such as carbon dioxide (CO2) concentration...... suggest that the occurrence of gas discharge is much more localized around restricted areas, often controlled by local permeability contrasts. Hence, our results show that a proposed monitoring concept should integrate SP, time-lapse ERT, meteorological parameters and soil-gas measurements to provide...

  1. Digital geospatial presentation of geoelectrical and geotechnical data for the lower American River and flood plain, east Sacramento, California

    Science.gov (United States)

    Ball, Lyndsay B.; Burton, Bethany L.; Powers, Michael H.; Asch, Theodore H.

    2015-01-01

    To characterize the extent and thickness of lithologic units that may have differing scour potential, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, has performed several geoelectrical surveys of the lower American River channel and flood plain between Cal Expo and the Rio Americano High School in east Sacramento, California. Additional geotechnical data have been collected by the U.S. Army Corps of Engineers and its contractors. Data resulting from these surveys have been compiled into similar database formats and converted to uniform geospatial datums and projections. These data have been visualized in a digital three-dimensional framework project that can be viewed using freely available software. These data facilitate a comprehensive analysis of the resistivity structure underlying the lower American River corridor and assist in levee system management.

  2. Study on Surface Permeability of Concrete under Immersion

    OpenAIRE

    Liu, Jun; Xing, Feng; Dong, Biqin; Ma, Hongyan; Pan, Dong

    2014-01-01

    In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured af...

  3. Conceptual design studies for surface infrastructure

    Science.gov (United States)

    Bufkin, Ann L.; Jones, William R., II

    1986-01-01

    The utimate design of a manned Mars base will be the result of considerable engineering analysis and many trade studies to optimize the configuration. Many options and scenarios are available and all need to be considered at this time. Initial base elements, two base configuration concepts, internal space architectural concerns, and two base set-up scenarios are discussed. There are many variables as well as many unknowns to be reckoned with before people set foot on the red planet.

  4. The use of geoelectrics in the study of a shallow quaternary alluvial ...

    African Journals Online (AJOL)

    The hydraulic conductivity (K = 41.3m/day) value measured in a reference borehole was combined with the normalized electrical conductivity (σ1) from a nearby vertical electrical sounding data. The resulting relation was interpreted with Dar Zarrouk parameters to infer the transmissivity variations at other vertical electrical ...

  5. Applying TM-polarization geoelectric exploration for study of low-contrast three-dimensional targets

    Science.gov (United States)

    Zlobinskiy, Arkadiy; Mogilatov, Vladimir; Shishmarev, Roman

    2018-03-01

    With using new field and theoretical data, it has been shown that applying the electromagnetic field of transverse magnetic (TM) polarization will give new opportunities for electrical prospecting by the method of transient processes. Only applying a pure field of the TM polarization permits poor three-dimensional objects (required metalliferous deposits) to be revealed in a host horizontally-layered medium. This position has good theoretical grounds. There is given the description of the transient electromagnetic method, that uses only the TM polarization field. The pure TM mode is excited by a special source, which is termed as a circular electric dipole (CED). The results of three-dimensional simulation (by the method of finite elements) are discussed for three real geological situations for which applying electromagnetic fields of transverse electric (TE) and transverse magnetic (TM) polarizations are compared. It has been shown that applying the TE mode gives no positive results, while applying the TM polarization field permits the problem to be tackled. Finally, the results of field works are offered, which showed inefficiency of application of the classical TEM method, whereas in contrast, applying the field of TM polarization makes it easy to identify the target.

  6. the use of geoelectrics in the study of a shallow quaternary alluvial ...

    African Journals Online (AJOL)

    PROF EKWUEME

    iterative interpretation using a 1-D inversion technique software .... The Kσ1 constant has been calculated at borehole 2 by using the K value from the pumping test and the σ value from the nearby ... transmissivity values are expected to vary from site to site depending on the change in the normalized transverse resistance.

  7. Study on hydrophilicity of polymer surfaces improved by plasma treatment

    International Nuclear Information System (INIS)

    Lai Jiangnan; Sunderland, Bob; Xue Jianming; Yan, Sha; Zhao Weijiang; Folkard, Melvyn; Michael, Barry D.; Wang Yugang

    2006-01-01

    Surface properties of polycarbonate (PC), polypropylene (PP), polyethylene terephthalate (PET) samples treated by microwave-induced argon plasma have been studied with contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scanned electron microscopy (SEM). It is found that plasma treatment modified the surfaces both in composition and roughness. Modification of composition makes polymer surfaces tend to be highly hydrophilic, which mainly depended on the increase of ratio of oxygen-containing group as same as other papers reported. And this experiment further revealed that C=O bond is Key factor to the improvement of the hydrophilicity of polymer surfaces. Our SEM observation on PET shown that the roughness of the surface has also been improved in micron scale and it has influence on the surface hydrophilicity

  8. CF3+ etching silicon surface: A molecular dynamics study

    NARCIS (Netherlands)

    Zhao, C.; Lu, X.; He, P.; Zhang, P.; Sun, W.; Zhang, Jingwei; Chen, F.; Gou, F.

    2012-01-01

    In this study, a molecular dynamics simulation method has been employed to investigate CF3 + ions, bombarding Si surface with the energy of 100, 200, 300 and 400 eV and an incident angle of 45 degrees with respect to the normal. The simulation results show that when CF3+ ions approach the Si surface

  9. Surface oxidation of cobalt nanoparticles studied by Mossbauer spectroscopy

    DEFF Research Database (Denmark)

    Bødker, Franz; Mørup, Steen; Charles, S.W.

    1999-01-01

    The surface oxide formed on cobalt nanoparticles has been studied by Mossbauer emission spectroscopy. Exposure of the cobalt particles to oxygen at room temperature was found to result in the formation of a relatively well-ordered surface oxide with Mossbauer parameters similar to those of CoO....

  10. Geoelectrical Response of a Hyporheic Zone within a Fractured Sedimentary Bedrock Riverbed

    Science.gov (United States)

    Steelman, C. M.; Kennedy, C. S.; Capes, D. C.; Parker, B. L.

    2015-12-01

    Fractured sedimentary bedrock aquifers represent an important source of water for many communities around the world. Although the effective porosities of these aquifers are extremely low relative to their unconsolidated counterparts, the existence of dense networks of interconnected fractures, dissolution-enhanced conduits or karst features can result in productive, yet heterogeneous and anisotropic, flow systems. Fluid-filled fractures remain connected to the porous matrix through advective-diffusive processes. This dual porosity concept is routinely applied to groundwater resource and contaminant transport studies; however, they have only recently been examined in shallow hyporheic environments, where groundwater and surface water influence one another through water and solute exchange across a streambed. Needless to say, there remains a gap in our conceptual understanding of hyporheic zones along rivers where water flowing through high-permeability fracture networks variably interacts with porewater residing in the low-permeability matrix. It is hypothesized that bedrock rivers will possess some measure of a hyporheic zone, albeit one that is governed by a vertical/horizontal fracture network but remains connected to the porous matrix. Hydrogeophysical methods provide a non-invasive means of assessing the scale and variability of critical zone dynamics. Here, we focus on the capacity of surface electrical resistivity for the detection and monitoring of a seasonally variable hyporheic zone at a field station located along the Eramosa River near Guelph, Ontario, Canada. Unlike conventional hydrogeological methods which potentially bias conduction in the fractures, surface resistivity is sensitive to the bulk electrical conductivity of the formation, making it more suited for detection of matrix conditions. Electrical resistivity data was collected along two 50 m profiles along a pool-riffle sequence on a daily to weekly interval from July 2014 to July 2015 and

  11. Optimized Model Surfaces for Advanced Atomic Force Microscopy Studies of Surface Nanobubbles.

    Science.gov (United States)

    Song, Bo; Zhou, Yi; Schönherr, Holger

    2016-11-01

    The formation of self-assembled monolayers (SAMs) of binary mixtures of 16-mercaptohexadecanoic acid (MHDA) and 1-octadecanethiol (ODT) on ultraflat template-stripped gold (TSG) surfaces was systematically investigated to clarify the assembly behavior, composition, and degree of possible phase segregation in light of atomic force microscopy (AFM) studies of surface nanobubbles on these substrates. The data for SAMs on TSG were compared to those obtained by adsorption on rough evaporated gold, as reported in a previous study. Quartz crystal microbalance and surface plasmon resonance data acquired in situ on TSG indicate that similar to SAM formation on conventional evaporated gold substrates ODT and MHDA form monolayers and bilayers, respectively. The second layer on MHDA, whose formation is attributed to hydrogen bonding, can be easily removed by adequate rinsing with water. The favorable agreement of the grazing incidence reflection Fourier transform infrared (GIR FTIR) spectroscopy and contact angle data analyzed with the Israelachvili-Gee model suggests that the binary SAMs do not segregate laterally. This conclusion is fully validated by high-resolution friction force AFM observations down to a length scale of 8-10 nm, which is much smaller than the typical observed surface nanobubble radii. Finally, correspondingly functionalized TSG substrates are shown to be valuable supports for studying surface nanobubbles by AFM in water and for addressing the relation between surface functionality and nanobubble formation and properties.

  12. Microscopic Study of Surface Microtopographic Characteristics of Dental Implants

    Science.gov (United States)

    Sezin, M.; Croharé, L.; Ibañez, J.C.

    2016-01-01

    Objective: To determine and compare the micro topographic characteristics of dental implants submitted to different surface treatments, using scanning electron microscopy (SEM). Materials and Methods: Implants were divided into 7 groups of 3 specimens each, according to the surface treatment used: group 1: Osseotite, BIOMET 3i; group 2: SLA surface, Institut Straumann AG; group 3: Oxalife surface, Tree-Oss implant; group 4: B&W implant surface; group 5: Q-implant surface; group 6: ML implant surface; group 7: RBM surface, Rosterdent implant. The surfaces were examined under SEM (Carl Zeiss FE-SEM-SIGMA). Image Proplus software was used to determine the number and mean diameter of pores per area unit (mm). The data obtained were analyzed with the Mann-Whitney test. A confocal laser microscope (LEXT-OLS4100 Olympus) was used to conduct the comparative study of surface roughness (Ra). Data were analyzed using Tukey's HSD test. Results: The largest average pore diameter calculated in microns was found in group 5 (3.45 µm+/-1.91) while the smallest in group 7 (1.47µm+/-1.29). Significant differences were observed among each one of the groups studied (p<0.05). The largest number of pores/mm2 was found in group 2 (229343) and the smallest number in group 4 (10937). Group 2 showed significant differences regarding the other groups (p<0.05). The greatest roughness (Ra) was observed in group 2 (0.975µm+/-0.115) and the smallest in group 4 (0.304µm+/-0.063). Group 2 was significantly different from the other groups (p<0.05). Conclusion: The micro topography observed in the different groups presented dissimilar and specific features, depending on the chemical treatment used for the surfaces.. PMID:27335615

  13. Sum-frequency spectroscopic studies: I. Surface melting of ice, II. Surface alignment of polymers

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Xing [Univ. of California, Berkeley, CA (United States)

    2000-01-01

    Surface vibrational spectroscopy via infrared-visible sum-frequency generation (SFG) has been established as a useful tool to study the structures of different kinds of surfaces and interfaces. This technique was used to study the (0001) face of hexagonal ice (Ih). SFG spectra in the O-H stretch frequency range were obtained at various sample temperatures. For the vapor(air)/ice interface, the degree of orientational order of the dangling OH bonds at the surface was measured as a function of temperature. Disordering sets in around 200 K and increases dramatically with temperature, which is strong evidence of surface melting of ice. For the other ice interfaces (silica/OTS/ice and silica/ice), a similar temperature dependence of the hydrogen bonded OH stretch peak was observed; the free OH stretch mode, however, appears to be different from that of the vapor (air)/ice interface due to interactions at the interfaces. The technique was also used to measure the orientational distributions of the polymer chains on a rubbed polyvinyl alcohol surface. Results show that the polymer chains at the surface appear to be well aligned by rubbing, and the adsorbed liquid crystal molecules are aligned, in turn, by the surface polymer chains. A strong correlation exists between the orientational distributions of the polymer chains and the liquid crystal molecules, indicating that the surface-induced bulk alignment of a liquid crystal film by rubbed polymer surfaces is via an orientational epitaxy-like mechanism. This thesis also contains studies on some related issues that are crucial to the above applications. An experiment was designed to measure SFG spectra in both reflection and transmission. The result confirms that SFG in reflection is generally dominated by the surface contribution. Another issue is the motional effect due to fast orientational motion of molecules at a surface or interface. Calculations show that the effect is significant if the molecular orientation varies

  14. Estimation of subsurface hydrological parameters around Akwuke, Enugu, Nigeria using surface resistivity measurements

    International Nuclear Information System (INIS)

    Utom, Ahamefula U; Odoh, Benard I; Egboka, Boniface C E; Egboka, Nkechi E; Okeke, Harold C

    2013-01-01

    As few boreholes may be available and carrying out pumping tests can be expensive and time consuming, relationships between aquifer characteristics and the electrical parameters of different geoelectric layers exist. Data from 19 vertical electrical soundings (VESs; 13 of these selected for evaluation) was recorded with a Schlumberger electrode configuration in the area around Akwuke, Enugu, Nigeria. The data was interpreted by computer iterative modelling with curve matching for calibration purposes. Geoelectric cross-sections along a number of lines were prepared to ascertain the overall distribution of the resistivity responses of the subsurface lithology. Identified probable shallow aquifer resistivity, thickness and depth values are in the range of 28–527 Ωm, 2.1–22.5 m and 3.1–28.3 m respectively. As our aquifer system consists of fine-grained, clay–silty sand materials, a modification of the Archie equations (Waxman–Smits model) was adopted to determine the true formation factor using the relationship between the apparent formation factor and the pore water resistivity. This representation of the effects of a separate conducting path due to the presence of clay particles in the aquifer materials was used in making reliable estimations of aquifer properties. The average hydraulic conductivity of 8.96 × 10 −4 m s −1 transmissivity ranging between 1.88 × 10 −3 and 2.02 × 10 −3 m 2 s −1 estimated from surface resistivity measurements correlated well with the available field data. Results of the study also showed a direct relationship between aquifer transmissivity and modified transverse resistance (R 2 = 0.85). (paper)

  15. Platelet adhesion studies on dipyridamole coated polyurethane surfaces

    Directory of Open Access Journals (Sweden)

    Aldenhoff Y. B.J.

    2003-06-01

    Full Text Available Surface modification of polyurethanes (PUs by covalent attachment of dipyridamole (Persantinregistered is known to reduce adherence of blood platelets upon exposure to human platelet rich plasma (PRP. This effect was investigated in further detail. First platelet adhesion under static conditions was studied with four different biomaterial surfaces: untreated PU, PU immobilised with conjugate molecule 1, PU immobilised with conjugate molecule 2, and PU immobilised with conjugate molecule 3. In PU immobilised with 1 dipyridamole is directly linked to the surface, in PU immobilised with 2 there is a short hydrophilic spacer chain in between the surface and the dipyridamole, while conjugate molecule 3 is merely the spacer chain. Scanning electron microscopy (SEM was used to characterise platelet adhesion from human PRP under static conditions, and fluorescence imaging microscopy was used to study platelet adhesion from whole blood under flow. SEM experiments encompassed both density measurements and analysis of the morphology of adherent platelets. In the static experiments the surface immobilised with 2 showed the lowest platelet adherence. No difference between the three modified surfaces emerged from the flow experiments. The surfaces were also incubated with washed blood platelets and labeled with Oregon-Green Annexin V. No capture of Oregon-Green Annexin V was seen, implying that the adhered platelets did not expose any phosphatidyl serine at their exteriour surface.

  16. Ti and Zr surfaces studied by molecular dynamics

    International Nuclear Information System (INIS)

    Pascuet, Maria I.; Passianot, Roberto C.; Monti, Ana M.

    2003-01-01

    The interaction between point defects technique and the (0001), (1-210), (10-10) surfaces in Ti and Zr is studied by the molecular dynamics technique. Both of metals are in the hexagonal structure and within a temperature range of 100 to 900 K. The atomic interactions are modeled by EAM-type many-body potentials, that were used previously in static simulations. New migration mechanisms are unraveled and others are verified with respect to those already proposed in the static studies. Also included is an analysis of the vacancy stability in the sub-surface layers of the prismatic surfaces. (author)

  17. Theoretical study of fractal growth and stability on surface

    DEFF Research Database (Denmark)

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

    2009-01-01

    We perform a theoretical study of the fractal growing process on surface by using the deposition, diffusion, aggregation method. We present a detailed analysis of the post-growth processes occurring in a nanofractal 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 are responsible for the formation of the final shape of the islands on surface after the post-growth relaxation....

  18. Liquid surface dynamics: a quantum-resolved scattering study

    Science.gov (United States)

    Kenyon, A. J.; McCaffery, A. J.; Quintella, C. M.; Zidan, M. D.

    1992-02-01

    Results are presented from a preliminary study of molecular scattering from liquid surfaces. Cold iodine molecules have been scattered off the surface of a methylated poly-siloxane oil and liquid gallium. Energy transfer at the liquid surface has been probed via the laser-induced fluorescence spectrum of the scattered molecules from which the vibrational and rotational state populations are accessible. We have been able to follow energy transfer via two separate channels; impulsive scattering and trapping-desorption, and have made a brief study of changes in the degree of vibrational and rotational accommodation at and around the melting point of gallium.

  19. Studies of nanosecond pulse surface ionization wave discharges over solid and liquid dielectric surfaces

    International Nuclear Information System (INIS)

    Petrishchev, Vitaly; Leonov, Sergey; Adamovich, Igor V

    2014-01-01

    Surface ionization wave discharges generated by high-voltage nanosecond pulses, propagating over a planar quartz surface and over liquid surfaces (distilled water and 1-butanol) have been studied in a rectangular cross section test cell. The discharge was initiated using a custom-made, alternating polarity, high-voltage nanosecond pulse plasma generator, operated at a pulse repetition rate of 100–500 Hz, with a pulse peak voltage and current of 10–15 kV and 7–20 A, respectively, a pulse FWHM of ∼100 ns, and a coupled pulse energy of 2–9 mJ/pulse. Wave speed was measured using a capacitive probe. ICCD camera images demonstrated that the ionization wave propagated predominantly over the quartz wall or over the liquid surface adjacent to the grounded waveguide placed along the bottom wall of the test cell. Under all experimental conditions tested, the surface plasma ‘sheet’ was diffuse and fairly uniform, both for positive and negative polarities. The parameters of ionization wave discharge propagating over distilled water and 1-butanol surfaces were close to those of the discharge over a quartz wall. No perturbation of the liquid surface by the discharge was detected. In most cases, the positive polarity surface ionization wave propagated at a higher speed and over a longer distance compared to the negative polarity wave. For all three sets of experiments (surface ionization wave discharge over quartz, water and 1-butanol), wave speed and travel distance decreased with pressure. Diffuse, highly reproducible surface ionization wave discharge was also observed over the liquid butanol–saturated butanol vapor interface, as well as over the distilled water–saturated water vapor interface, without buffer gas flow. No significant difference was detected between surface ionization discharges sustained using single-polarity (positive or negative), or alternating polarity high-voltage pulses. Plasma emission images yielded preliminary evidence of charge

  20. Deposition of latex colloids at rough mineral surfaces: an analogue study using nanopatterned surfaces.

    Science.gov (United States)

    Krishna Darbha, Gopala; Fischer, Cornelius; Michler, Alex; Luetzenkirchen, Johannes; Schäfer, Thorsten; Heberling, Frank; Schild, Dieter

    2012-04-24

    Deposition of latex colloids on a structured silicon surface was investigated. The surface with well-defined roughness and topography pattern served as an analogue for rough mineral surfaces with half-pores in the submicrometer size. The silicon topography consists of a regular pit pattern (pit diameter = 400 nm, pit spacing = 400 nm, pit depth = 100 nm). Effects of hydrodynamics and colloidal interactions in transport and deposition dynamics of a colloidal suspension were investigated in a parallel plate flow chamber. The experiments were conducted at pH ∼ 5.5 under both favorable and unfavorable adsorption conditions using carboxylate functionalized colloids to study the impact of surface topography on particle retention. Vertical scanning interferometry (VSI) was applied for both surface topography characterization and the quantification of colloidal retention over large fields of view. The influence of particle diameter variation (d = 0.3-2 μm) on retention of monodisperse as well as polydisperse suspensions was studied as a function of flow velocity. Despite electrostatically unfavorable conditions, at all flow velocities, an increased retention of colloids was observed at the rough surface compared to a smooth surface without surface pattern. The impact of surface roughness on retention was found to be more significant for smaller colloids (d = 0.3, 0.43 vs. 1, 2 μm). From smooth to rough surfaces, the deposition rate of 0.3 and 0.43 μm colloids increased by a factor of ∼2.7 compared to a factor of 1.2 or 1.8 for 1 and 2 μm colloids, respectively. For a substrate herein, with constant surface topography, the ratio between substrate roughness and radius of colloid, Rq/rc, determined the deposition efficiency. As Rq/rc increased, particle-substrate overall DLVO interaction energy decreased. Larger colloids (1 and 2 μm) beyond a critical velocity (7 × 10(-5) and 3 × 10(-6) m/s) (when drag force exceeds adhesion force) tend to detach from the surface

  1. X-ray scattering studies of surfaces and interfaces

    International Nuclear Information System (INIS)

    Sanyal, M.K.

    1998-01-01

    Here we shall briefly review the basics and some applications of x-ray specular reflectivity and diffuse scattering techniques. These x-ray scattering techniques are uniquely suited to study of the structure of surfaces and interfaces at atomic resolutions as they are nondestructive and can probe even interfaces which are buried. The study of structure of surfaces and interfaces is not only required in understanding physics in reduced dimensions but is also essential in developing technologically important materials

  2. A Study on 3-Dimensional Surface Measurement using Confocal Principle

    International Nuclear Information System (INIS)

    Kang, Young June; Song, Dae Ho; You, Weon Jae

    2001-01-01

    In modern industry, the accuracy and the sulfate-finish requirements for machined parts have been becoming ever more stringent. In addition, the measurement and understanding of surface topography is rapidly attracting the attention of the physicist and chemist as well as the engineer. Optical measuring method is used in vibration measurement, crack and defect detection with the advent of opto-mechatronics, and it is expected to play an important role in surface topography. In this study, the principle of confocal microscope is described, and the advanced 3-D surface measuring system that has better performance than the traditional confocal microscope is developed. Suitable fixtures arc developed and integrated with the computer system for generating 3-D surface and form data. Software for data acquisition and analysis of various parameters in surface geometrical features has been developed

  3. Geoelectrical characterization with 1D VES/TDEM joint inversion in Urupês-SP region, Paraná Basin: Applications to hydrogeology

    Science.gov (United States)

    Leite, David Nakamura; Bortolozo, Cassiano Antonio; Porsani, Jorge Luís; Couto, Marco Antonio; Campaña, Julian David Realpe; dos Santos, Fernando Acácio Monteiro; Rangel, Rodrigo Corrêa; Hamada, Luiz Rodrigo; Sifontes, Rimary Valera; Serejo de Oliveira, Gabriela; Stangari, Marcelo César

    2018-04-01

    Although Brazil is well known by the large rivers and the Amazon Rain Forest most cities do not have access to sufficient quantities of surface water to supply the population. Because of this 61% of Brazilian population (IBGE, 2003) depends on groundwater resources. In order to help the conscious exploration of this resource in Urupês city (São Paulo State) which is characterized by problems of lack of water, this research applied the transient electromagnetic method (TDEM) and Vertical Electrical Sounding (VES) for the geoelectrical characterization of the interest region. So, the objective of this work was increase the hydrogeological basis for groundwater exploitation of Bauru sedimentary aquifer and Serra Geral fractured aquifer (Paraná Basin). A total of 23 TDEM and 15 VES soundings were conducted during the years of 2009, 2011 and 2012. In addition, 10 pairs of VES/TDEM soundings were acquired with coincident centers to be able to perform the joint inversion. The joint inversion technique is a promising tool, which enables to get the best of both methods, where the VES add the shallow information and TDEM the deeper one. In this work, the individual and joint inversions were performed using the "Curupira" software. After data process and inversion, the results were interpreted based on geological well information provided by the Department of Water and Electrical Power (DAEE) and the Brazilian Geological Survey (CPRM) which enabled to estimate favorable places to exploitation of water in Bauru and Serra Geral aquifers. For the Bauru aquifer, the results suggest areas where thickness exceeds 100 m. In these areas, the resistivity calculated was about 20 Ω·m. Therefore, the sediments have been interpreted as saturated sandy clay. In the basalt layer of Serra Geral Formation, the suggested locations present resistivity values <100 Ω·m at 200 m depth. The indicated places in sedimentary aquifer and the locations in the fractured aquifer will may show

  4. Structural and vibrational studies of clean and chemisorbed metal surfaces

    International Nuclear Information System (INIS)

    Jiang, Qing-Tang.

    1992-01-01

    Using Medium Energy Ion Scattering, we have studied the structural and vibrational properties of a number of clean and chemisorbed metal surfaces. The work presented in this thesis is mainly of a fundamental nature. However, it is believed that an atomistic understanding of the forces that affect surface structural and vibrational properties can have a beneficial impact on a large number of areas of applied nature. We find that the surface structure of Cu(001) follows the common trend for metal surfaces, where a small oscillatory relaxation exists beginning with a slight contraction in the top layer. In addition, the surface vibrational amplitude is enhanced (as s usually the case) by ∼80%. A detailed analysis of our data shows an unexpected anisotropy of the vibrational amplitude, such that the out-of-plane vibrational amplitude is 30% smaller than the in-plane vibrational amplitude. The unexpected results may imply a large tensile stress on Cu(001). Upon adsorption of 1/4 of a monolayer of S, a p(2 x 2)-S/Cu(001) surface is created. This submonolayer amount of S atoms makes the surface bulk-like, in which the anisotropy of the surface vibrations is removed and the first interlayer contraction is lifted. By comparing our model to earlier contradictory results on this controversial system. We find excellent agreement with a recent LEED study. The presence of 0.1 monolayer of Ca atoms on the Au(113) surface induces a drastic atomic rearrangements, in which half of the top layer Au atoms are missing and a (1 x 2) symmetry results. In addition, the first interlayer spacing of Au(113) is significantly reduced. Our results are discussed in terms of the energy balance between competing surface electronic charge densities

  5. Chloride ion-dependent surface-enhanced Raman scattering study of biotin on the silver surface

    International Nuclear Information System (INIS)

    Liu Fangfang; Gu Huaimin; Yuan Xiaojuan; Dong Xiao; Lin Yue

    2011-01-01

    In the present paper, the surface enhanced Raman scattering (SERS) technique was employed to study the SERS spectra of biotin molecules formed on the silver surface. The adsorption geometries of biotin molecules on the silver surface were analyzed based on the SERS data. It can be found that most vibration modes show a Raman shift in silver sol after the addition of sodium chloride solution. In addition, The Raman signals of biotin become weaker and weaker with the increase of the concentration of sodium chloride. This may be due to that the interaction between chloride ions and silver particles is stronger than the interaction between biotin molecules and silver particles. When the concentration of sodium chloride in silver colloid is higher than 0.05mol/L, superfluous chloride ions may form an absorption layer so that biotin can not be adsorbed on silver surface directly. The changes in intensity and profile shape in the SERS spectra suggest different adsorption behavior and surface-coverage of biotin on silver surface. The SERS spectra of biotin suggest that the contribution of the charge transfer mechanism to SERS may be dominant.

  6. Surface science study of selective ethylene epoxidation catalyzed by the Ag(110) surface: Structural sensitivity

    International Nuclear Information System (INIS)

    Campbell, C.T.

    1984-01-01

    The selective oxidation of ethylene to ethylene epoxide (C 2 H 4 +1/2O 2 →C 2 H 4 O) over Ag is the simplest example of kinetically controlled, selective heterogeneous catalysis. We have studied the steady-state kinetics and selectivity of this reaction for the first time on a clean, well-characterized Ag(110) surface by using a special apparatus which allows rapid (approx.20 s) transfer between a high-pressure catalytic microreactor and an ultrahigh vacuum surface analysis (AES, XPS, LEED, TDS) chamber. The effects of temperature and reactant pressures upon the rate and selectivity are virtually identical on Ag(110) and supported, high surface area Ag catalysts. The absolute specific rate (per Ag surface atom) is, however, some 100-fold higher for Ag(110) than for high surface area catalysts. This is related to the well-known structural sensitivity of this reaction. It is postulated that a small percentage of (110) planes (or [110]-like sites) are responsible for most of the catalytic activity of high surface area catalysts. The high activity of the (110) plane is attributed to its high sticking probability for dissociative oxygen adsorption, since the rate of ethylene epoxidation is shown in a related work [Ref. 1: C. T. Campbell and M. T. Paffett, Surf. Sci. (in press)] to be proportional to the coverage of atomically adsorbed oxygen at constant temperature and ethylene pressure

  7. Glass transition near the free surface studied by synchrotron radiation

    International Nuclear Information System (INIS)

    Sikorski, M.

    2008-06-01

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-μm length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  8. Glass transition near the free surface studied by synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Sikorski, M.

    2008-06-15

    A comprehensive picture of the glass transition near the liquid/vapor interface of the model organic glass former dibutyl phthalate is presented in this work. Several surface-sensitive techniques using x-ray synchrotron radiation were applied to investigate the static and dynamic aspects of the formation of the glassy state from the supercooled liquid. The amorphous nature of dibutyl phthalate close to the free surface was confirmed by grazing incidence X-ray diffraction studies. Results from X-ray reflectivity measurements indicate a uniform electron density distribution close to the interface excluding the possibility of surface freezing down to 175 K. Dynamics on sub-{mu}m length-scales at the surface was studied with coherent synchrotron radiation via x-ray photon correlation spectroscopy. From the analysis of the dispersion relation of the surface modes, viscoelastic properties of the dibutyl phthalate are deduced. The Kelvin-Voigt model of viscoelastic media was found to describe well the properties of the liquid/vapor interface below room temperature. The data show that the viscosity at the interface matches the values reported for bulk dibutyl phthalate. The scaled relaxation rate at the surface agrees with the bulk data above 210 K. Upon approaching the glass transition temperature the free surface was observed to relax considerably faster close to the liquid/vapor interface than in bulk. The concept of higher relaxation rate at the free surface is also supported by the results of the quasielastic nuclear forward scattering experiment, during which dynamics on molecular length scales around the calorimetric glass transition temperature is studied. The data were analyzed using mode-coupling theory of the glass transition and the model of the liquid(glass)/vapor interface, predicting inhomogeneous dynamics near the surface. The quasielastic nuclear forward scattering data can be explained when the molecular mobility is assumed to decrease with the increasing

  9. An overview of surface radiance and biology studies in FIFE

    Science.gov (United States)

    Blad, B. L.; Schimel, D. S.

    1992-01-01

    The use of satellite data to study and to understand energy and mass exchanges between the land surface and the atmosphere requires information about various biological processes and how various reflected or emitted spectral radiances are influenced by or manifested in these processes. To obtain such information, studies were conducted by the First ISLSCP Field Experiment (FIFE) surface radiances and biology (SRB) group using surface, near-surface, helicopter, and aircraft measurements. The two primary objectives of this group were to relate radiative fluxes to biophysical parameters and physiological processes and to assess how various management treatments affect important biological processes. This overview paper summarizes the results obtained by various SRB teams working in nine different areas: (1) measurements of bidirectional reflectance and estimation of hemispherical albedo; (2) evaluation of spatial and seasonal variability reflectance and vegetation indices; (3) determination of surface and radiational factors and their effects on vegetation indices and photosynthetically active radiation relationships; (4) use of surface temperatures to estimate sensible heat flux; (5) controls over photosynthesis and respiration at small scales; (6) soil surface CO2 fluxes and grassland carbon budget; (7) landscape variations in controls over gas exchange and energy partitioning; (8) radiometric response of prairie to management and topography; and (9) determination of nitrogen gas exchanges in a tallgrass prairie.

  10. Science synergism study for EOS on evolution of desert surfaces

    Science.gov (United States)

    Farr, Tom G.

    1987-01-01

    The effectiveness of EOS data as a basis for the study of desert surfaces' evolution is presently evaluated for both long and short term geomorphic evolution. Attention is given to the usefulness of such sensor systems planned for EOS as MODIS for regional vegetation distribution/variability monitoring, HIRIS for visible-near IR observations, TIMS for lithological identification, HMMR and SSMI for soil characteristics, LASA for atmospheric profiles, SAR for surface roughness, ALT for two-dimensional topography, ACR for the calibration of imaging sensors, and ERBE for climate modeling and regional surface albedo variation determinations.

  11. Surface science studies on titania for solar fuel applications

    Science.gov (United States)

    Hadsell, Courtney Sara Mathews

    Titanium dioxide (titania) is a well-studied material for various applications including but not limited to, paint, sunscreen, pharmaceuticals and solar cell applications (photocatalysis.) It can be found in three main crystal forms; rutile, anatase, and brookite and this work will focus on the anatase form which has been heavily studied for its potential in dye sensitized solar cells (DSSCs.) I propose that aqueous and photo dye stability can be improved by taking special care to the exposed surface of anatase. Additionally, the theoretical maximum open circuit voltage of a DSSC is dependent upon which surface is exposed to the electrolyte. Previous works in this area have not been rigorous with respect to the surface and morphology of titania being used. Standard synthesis techniques of anatase lead to a crystal that generally has 94% of the titania (101) surface exposed, and the other 6% is the higher energy (001) surface. The (101) surface has 5 & 6-fold coordinated titania whereas the (001) surface only has 5-fold (under) coordinated titania. This under-coordination leads to enhanced reactivity of the (001) surface which has been demonstrated by dissassociative adsorption of water, and catalysis applications. Much theoretical work has focused on the minority (001) surface because up until recently synthesizing anatase with enhanced exposure of the (001) surface has been difficult. The initial materials for this study will be multilayer titania nanotubes (TiNTs) and nanosheets (TiNS) which have been previously characterized by my predecessor. The TiNTs and TiNS have 100% exposed (001)-like surface. Both of these materials show enhanced stability of phosphonated dye binding as compared to the current standard of anatase nanoparticles (NPs) however, due to their limited thermal stability the potential of incorporating the TiNTs and TiNSs into devices has been eliminated in this study. To overcome the device limitations I will synthesis a novel titania nanotile

  12. Theoretical studies of mutual diffusivities and surface properties in ...

    Indian Academy of Sciences (India)

    properties, thus underlining the importance of thermodynamic studies for liquid binary alloys. In this study, the transport and surface properties of Cd–Ga liquid alloys are determined from energetics and derivatives from experimental thermodynamic data. Cd–Ga alloys have been studied by many authors [14–16]. The alloy ...

  13. Surface chemistry of methanol on different ZnO surfaces studied by vibrational spectroscopy.

    Science.gov (United States)

    Jin, Lanying; Wang, Yuemin

    2017-05-24

    The adsorption and reactions of CH 3 OH on nonpolar mixed-terminated ZnO(101[combining macron]0), polar O-ZnO(0001[combining macron]) and Zn-ZnO(0001) surfaces have been studied systematically using high-resolution electron energy loss spectroscopy (HREELS) in conjunction with temperature programmed desorption (TPD). For all three ZnO surfaces, exposure to methanol at room temperature leads to (partially) dissociative adsorption resulting in the formation of hydroxyl and methoxy species. Upon heating to higher temperatures, the dissociated and intact methanol species on ZnO(101[combining macron]0) predominantly undergo molecular desorption releasing CH 3 OH at 370 and 440 K. The Zn-O dimer vacancies are responsible for the decomposition of a small fraction of methanol yielding H 2 , CH 2 O and CO at 540 and 565 K. The interaction of methanol with polar O-ZnO and Zn-ZnO surfaces is dominated by thermal decomposition of CH 3 OH to produce CH 2 O, H 2 , CO, CO 2 and H 2 O at elevated temperatures. The high chemical reactivity of both polar surfaces is related to the high abundance of different types of surface defects formed via massive restructuring. Importantly, the reconstructed Zn-ZnO surface exhibits high selectivity for hydrogen production at 520 K, which was not observed for the polar O-ZnO surface. The HREELS data revealed that this low-temperature hydrogen evolution on Zn-ZnO results from methoxy oxidation to a formate species occurring at O-terminated step-edge sites.

  14. Effect of surface structure on catalytic reactions: A sum frequency generation surface vibrational spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    McCrea, Keith Ryan [Univ. of California, Berkeley, CA (United States)

    2001-01-01

    In the results discussed above, it is clear that Sum Frequency Generation (SFG) is a unique tool that allows the detection of vibrational spectra of adsorbed molecules present on single crystal surfaces under catalytic reaction conditions. Not only is it possible to detect active surface intermediates, it is also possible to detect spectator species which are not responsible for the measured turnover rates. By correlating high-pressure SFG spectra under reaction conditions and gas chromatography (GC) kinetic data, it is possible to determine which species are important under reaction intermediates. Because of the flexibility of this technique for studying surface intermediates, it is possible to determine how the structures of single crystal surfaces affect the observed rates of catalytic reactions. As an example of a structure insensitive reaction, ethylene hydrogenation was explored on both Pt(111) and Pt(100). The rates were determined to be essentially the same. It was observed that both ethylidyne and di-σ bonded ethylene were present on the surface under reaction conditions on both crystals, although in different concentrations. This result shows that these two species are not responsible for the measured turnover rate, as it would be expected that one of the two crystals would be more active than the other, since the concentration of the surface intermediate would be different on the two crystals. The most likely active intermediates are weakly adsorbed molecules such as π-bonded ethylene and ethyl. These species are not easily detected because their concentration lies at the detection limit of SFG. The SFG spectra and GC data essentially show that ethylene hydrogenation is structure insensitive for Pt(111) and Pt(100). SFG has proven to be a unique and excellent technique for studying adsorbed species on single crystal surfaces under high-pressure catalytic reactions. Coupled with kinetic data obtained from gas chromatography measurements, it can give

  15. Polymer Adsorption on Graphite and CVD Graphene Surfaces Studied by Surface-Specific Vibrational Spectroscopy.

    Science.gov (United States)

    Su, Yudan; Han, Hui-Ling; Cai, Qun; Wu, Qiong; Xie, Mingxiu; Chen, Daoyong; Geng, Baisong; Zhang, Yuanbo; Wang, Feng; Shen, Y R; Tian, Chuanshan

    2015-10-14

    Sum-frequency vibrational spectroscopy was employed to probe polymer contaminants on chemical vapor deposition (CVD) graphene and to study alkane and polyethylene (PE) adsorption on graphite. In comparing the spectra from the two surfaces, it was found that the contaminants on CVD graphene must be long-chain alkane or PE-like molecules. PE adsorption from solution on the honeycomb surface results in a self-assembled ordered monolayer with the C-C skeleton plane perpendicular to the surface and an adsorption free energy of ∼42 kJ/mol for PE(H(CH2CH2)nH) with n ≈ 60. Such large adsorption energy is responsible for the easy contamination of CVD graphene by impurity in the polymer during standard transfer processes. Contamination can be minimized with the use of purified polymers free of PE-like impurities.

  16. Atomic structure of the SbCu surface alloy: A surface X-ray diffraction study

    DEFF Research Database (Denmark)

    Meunier, I.; Gay, J.M.; Lapena, L.

    1999-01-01

    The dissolution at 400 degrees C of an antimony layer deposited at room temperature on a Cu(111) substrate leads to a surface alloy with a p(root 3x root 3)R 30 degrees x 30 degrees superstructure and a Sb composition of 1/3.We present here a structural study of this Sb-Cu compound by surface X......-ray diffraction (SXRD). The best agreement is obtained for a Cu,Sb surface layer with Sb atoms substituting 1/3 of the Cu atoms, over an essentially unperturbed Cu(111) plane. The largest relaxation is undergone by the Sb atoms which rise by 0.32+0.02 Angstrom over the mean plane of its Cu neighbours....... No substantial in-plane relaxations were observed. (C) 1999 Elsevier Science B.V. All rights reserved....

  17. Sputtering of rough surfaces: a 3D simulation study

    Science.gov (United States)

    von Toussaint, U.; Mutzke, A.; Manhard, A.

    2017-12-01

    The lifetime of plasma-facing components is critical for future magnetic confinement fusion power plants. A key process limiting the lifetime of the first-wall is sputtering by energetic ions. To provide a consistent modeling of the sputtering process of realistic geometries, the SDTrimSP-code has been extended to enable the processing of analytic as well as measured arbitrary 3D surface morphologies. The code has been applied to study the effect of varying the impact angle of ions on rough surfaces on the sputter yield as well as the influence of the aspect ratio of surface structures on the 2D distribution of the local sputtering yields. Depending on the surface morphologies reductions of the effective sputter yields to less than 25% have been observed in the simulation results.

  18. Study on Surface Permeability of Concrete under Immersion.

    Science.gov (United States)

    Liu, Jun; Xing, Feng; Dong, Biqin; Ma, Hongyan; Pan, Dong

    2014-01-28

    In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured after 30-day immersion. The early increase in surface permeability should be mainly attributed to the leaching of calcium hydroxide, while the later decrease to the refinement of pore structure due to hydration. The two effects work simultaneously and compete throughout the immersion period. The proposed mechanisms get support from microscopic measurements and observations.

  19. Study of Huizhou architecture component point cloud in surface reconstruction

    Science.gov (United States)

    Zhang, Runmei; Wang, Guangyin; Ma, Jixiang; Wu, Yulu; Zhang, Guangbin

    2017-06-01

    Surface reconfiguration softwares have many problems such as complicated operation on point cloud data, too many interaction definitions, and too stringent requirements for inputing data. Thus, it has not been widely popularized so far. This paper selects the unique Huizhou Architecture chuandou wooden beam framework as the research object, and presents a complete set of implementation in data acquisition from point, point cloud preprocessing and finally implemented surface reconstruction. Firstly, preprocessing the acquired point cloud data, including segmentation and filtering. Secondly, the surface’s normals are deduced directly from the point cloud dataset. Finally, the surface reconstruction is studied by using Greedy Projection Triangulation Algorithm. Comparing the reconstructed model with the three-dimensional surface reconstruction softwares, the results show that the proposed scheme is more smooth, time efficient and portable.

  20. Study of Magnetohydrodynamic Surface Waves on Liquid Gallium

    International Nuclear Information System (INIS)

    Hantao Ji; William Fox; David Pace; Rappaport, H.L.

    2004-01-01

    Magnetohydrodynamic (MHD) surface waves on liquid gallium are studied theoretically and experimentally in the small magnetic Reynolds number limit. A linear dispersion relation is derived when a horizontal magnetic field and a horizontal electric current is imposed. No wave damping is found in the shallow liquid limit while waves always damp in the deep liquid limit with a magnetic field parallel to the propagation direction. When the magnetic field is weak, waves are weakly damped and the real part of the dispersion is unaffected, while in the opposite limit waves are strongly damped with shortened wavelengths. In a table-top experiment, planar MHD surface waves on liquid gallium are studied in detail in the regime of weak magnetic field and deep liquid. A non-invasive diagnostic accurately measures surface waves at multiple locations by reflecting an array of lasers off the surface onto a screen, which is recorded by an Intensified-CCD camera. The measured dispersion relation is consistent with the linear theory with a reduced surface tension likely due to surface oxidation. In excellent agreement with linear theory, it is observed that surface waves are damped only when a horizontal magnetic field is imposed parallel to the propagation direction. No damping is observed under a perpendicular magnetic field. The existence of strong wave damping even without magnetic field suggests the importance of the surface oxide layer. Implications to the liquid metal wall concept in fusion reactors, especially on the wave damping and a Rayleigh-Taylor instability when the Lorentz force is used to support liquid metal layer against gravity, are discussed

  1. Studies on Prevalence and Risk Factors for Hepatitis B Surface ...

    African Journals Online (AJOL)

    Studies on Prevalence and Risk Factors for Hepatitis B Surface Antigen among Secondary School Students in North-central, Nigeria. ... high among the studied population. This suggests that public awareness on the virus be accorded urgent attention, while vaccination programme should be improved in the community.

  2. Use of surface electromyography in phonation studies: an integrative review

    Science.gov (United States)

    Balata, Patricia Maria Mendes; Silva, Hilton Justino da; Moraes, Kyvia Juliana Rocha de; Pernambuco, Leandro de Araújo; Moraes, Sílvia Regina Arruda de

    2013-01-01

    Summary Introduction: Surface electromyography has been used to assess the extrinsic laryngeal muscles during chewing and swallowing, but there have been few studies assessing these muscles during phonation. Objective: To investigate the current state of knowledge regarding the use of surface electromyography for evaluation of the electrical activity of the extrinsic muscles of the larynx during phonation by means of an integrative review. Method: We searched for articles and other papers in the PubMed, Medline/Bireme, and Scielo databases that were published between 1980 and 2012, by using the following descriptors: surface electromyography and voice, surface electromyography and phonation, and surface electromyography and dysphonia. The articles were selectedon the basis ofinclusion and exclusion criteria. Data Synthesis: This was carried out with a cross critical matrix. We selected 27 papers,i.e., 24 articles and 3 theses. The studies differed methodologically with regards to sample size and investigation techniques, making it difficult to compare them, but showed differences in electrical activity between the studied groups (dysphonicsubjects, non-dysphonicsubjects, singers, and others). Conclusion: Electromyography has clinical applicability when technical precautions with respect to application and analysis are obeyed. However, it is necessary to adopt a universal system of assessment tasks and related measurement techniques to allow comparisons between studies. PMID:25992030

  3. Modeling Geoelectric Fields and Geomagnetically Induced Currents Around New Zealand to Explore GIC in the South Island's Electrical Transmission Network

    Science.gov (United States)

    Divett, T.; Ingham, M.; Beggan, C. D.; Richardson, G. S.; Rodger, C. J.; Thomson, A. W. P.; Dalzell, M.

    2017-10-01

    Transformers in New Zealand's South Island electrical transmission network have been impacted by geomagnetically induced currents (GIC) during geomagnetic storms. We explore the impact of GIC on this network by developing a thin-sheet conductance (TSC) model for the region, a geoelectric field model, and a GIC network model. (The TSC is composed of a thin-sheet conductance map with underlying layered resistivity structure.) Using modeling approaches that have been successfully used in the United Kingdom and Ireland, we applied a thin-sheet model to calculate the electric field as a function of magnetic field and ground conductance. We developed a TSC model based on magnetotelluric surveys, geology, and bathymetry, modified to account for offshore sediments. Using this representation, the thin sheet model gave good agreement with measured impedance vectors. Driven by a spatially uniform magnetic field variation, the thin-sheet model results in electric fields dominated by the ocean-land boundary with effects due to the deep ocean and steep terrain. There is a strong tendency for the electric field to align northwest-southeast, irrespective of the direction of the magnetic field. Applying this electric field to a GIC network model, we show that modeled GIC are dominated by northwest-southeast transmission lines rather than east-west lines usually assumed to dominate.

  4. An experimental study on decontamination by surface condition

    International Nuclear Information System (INIS)

    Lee, Young Hae

    1974-01-01

    Surface decontamination is one of the very important problem to be completely solved in the isotope laboratory where there is always the possibility of radioactive contamination, i.e., on the floors, walls, working tables and benches etc., Isotope laboratories require surface covering of material which can be easily and effectively decontaminated. These experiment were done to find an effective decontamination procedure for kind of surfaces which usually are found in radioisotope laboratories and the best type of surface material, that is, one which is easily decontaminated from the point of view of radiation health and safely. This study is presented to guide radioisotope laboratories in Korea which may need to renovate existing unsafe facilities. In some contaminated facilities entirely new installations may be required. Twelve types of surface material are used for study in this experiment. These include 10 cm square of stainless steel, aluminum, ceramic and mosaic tiles, glass, acrylic, formica board, asphalt tile and coated wood with 4 kinds of paints. Stepwise decontamination was performed with various decontamination procedures following a spill of I 1 31 on the center of the surface material being tested. Twelve different decontamination procedures were tested. These included wet wiping with water and detergent, or dry wiping, or removing with gummed paper. Additional chemical procedures used 10% solution of hydrochloric acid, or surface acid, or ammonium citrate, or potassium iodide, or acetone or carbon tetrachloride. The final testing method was abrasion of the test surfaces. Brief analysis of experimental results on the decontaminability on the tested surface showed: 1. Metallic surfaces such as stainless steel or aluminum, or glass, or a piece of ceramic tile or acrylic are recommended as the surface materials for isotope laboratories because these are easily decontaminated by wet wiping only. 2. Formica board, asphalt tile and wood are not easily

  5. Metastability in plyometric training on unstable surfaces: a pilot study

    Science.gov (United States)

    2014-01-01

    Background In the past, plyometric training (PT) has been predominantly performed on stable surfaces. The purpose of this pilot study was to examine effects of a 7-week lower body PT on stable vs. unstable surfaces. This type of exercise condition may be denoted as metastable equilibrium. Methods Thirty-three physically active male sport science students (age: 24.1 ± 3.8 years) were randomly assigned to a PT group (n = 13) exercising on stable (STAB) and a PT group (n = 20) on unstable surfaces (INST). Both groups trained countermovement jumps, drop jumps, and practiced a hurdle jump course. In addition, high bar squats were performed. Physical fitness tests on stable surfaces (hexagonal obstacle test, countermovement jump, hurdle drop jump, left-right hop, dynamic and static balance tests, and leg extension strength) were used to examine the training effects. Results Significant main effects of time (ANOVA) were found for the countermovement jump, hurdle drop jump, hexagonal test, dynamic balance, and leg extension strength. A significant interaction of time and training mode was detected for the countermovement jump in favor of the INST group. No significant improvements were evident for either group in the left-right hop and in the static balance test. Conclusions These results show that lower body PT on unstable surfaces is a safe and efficient way to improve physical performance on stable surfaces. PMID:25089202

  6. Numerical study of droplet impact and rebound on superhydrophobic surface

    Science.gov (United States)

    Cai, Xuan; Wu, Yanchen; Woerner, Martin; Frohnapfel, Bettina

    2017-11-01

    Droplet impact and rebound on superhydrophobic surface is an important process in many applications; among them are developing self-cleaning or anti-icing materials and limiting liquid film formation of Diesel Exhaust Fluid (DEF) in exhaust gas pipe. In the latter field, rebound of DEF droplet from wall is desired as an effective mean for avoiding or reducing unwanted solid deposition. Our goal is to numerically study influence of surface wettability on DEF droplet impact and rebound behavior. A phase-field method is chosen, which was implemented in OpenFOAM by us and validated for wetting-related interfacial flow problems. In the present contribution we first numerically reproduce relevant experimental studies in literature, to validate the code for droplet impact and rebound problem. There we study droplet-surface contact time, maximum/instantaneous spreading factor and droplet shape evolution. Our numerical results show good agreement with experimental data. Next we investigate for DEF droplets the effects of diameter, impact velocity and surface wettability on rebound behavior and jumping height. Based on Weber number and equilibrium contact angle, two regimes are identified. We show that surface wettability is a deciding factor for achieving rebound event. This work is supported by Foundation ``Friedrich-und-Elisabeth Boysen Stiftung fuer Forschung und Innovation'' (BOY-127-TP1).

  7. Environmental assessment on karstic formations for implantation of a terrestrial pipeline: case study of the Cacimbas-Catu gas pipeline; Avaliacao ambiental para implantacao de dutos terretres em terrenos carsticos: estudo de caso Gasoduto Cacimbas-Catu

    Energy Technology Data Exchange (ETDEWEB)

    Hurtado, Shanty Navarro; Oliveira, Wilson Jose de; Braun, Oscar [PETROBRAS, Rio de Janeiro, RJ (Brazil)] (and others)

    2008-07-01

    This work concerns in the development of a study on mapping and detection of structures and geological and geotechnical features associated with karstic relief and its implications in terms of ground stability to support the pipeline as well as from the point of view of cavities / caves conservation, potentially impacted by this activity. The limited mobility of track, carried by the existing restrictions, make the route of the Cacimbas-Catu pipeline pass through the cities of Itapebi (BA), Belomonte (BA), Mascote (BA) e Camaca (BA), where the local geology is characterized by rocks of Rio Pardo Group, dating from the Superior proterozoic (lower sequence predominantly carbonatic and upper sequence predominantly terrigenous). The study included a survey of secondary data, a field survey confirming karstic features, a 2D and subsequently 3D tomography survey, and a drilling survey to direct research at points of geo-electrical anomalies. The work did not identify underground cavities on the Cacimbas-Catu pipeline route. Even taking the studies presented geo-electric anomalies the direct investigation did not confirm the presence of voids in sub-surface, which enables the implementation of pipelines in this place, however the presence of electric anomalies with high resistivity indicate geotechnical areas where special care should be taken in relation to the stability of the ground. (author)

  8. Recent advances in study of uranium surface chemistry in China

    International Nuclear Information System (INIS)

    Luo, Lizhu; Lai, Xinchun; Wang, Xiaolin

    2014-01-01

    Uranium is very important in nuclear energy industry; however, uranium and its alloys corrode seriously in various atmospheres because of their chemical reactivities. In China, continuous investigations focused on surface chemistry have been carried out for a thorough understanding of uranium in order to provide technical support for its engineering applications. Oxidation kinetics of uranium and its alloys in oxidizing atmospheres are in good agreement with those in the literature. In addition to the traditional techniques, non-traditional methods have been applied for oxidation kinetics of uranium, and it has been verified that spectroscopic ellipsometry and X-ray diffraction are effective and nondestructive tools for in situ kinetic studies. The inhibition efficiency of oxidizing gas impurities on uranium hydrogenation is found to follow the order CO 2 > CO > O 2 , and the broadening of XPS shoulders with temperature in depth profile of hydrogenated uranium surface is discussed, which is not mentioned in the literature. Significant progress on surface chemistry of alloyed uranium (U-Nb and U-Ti) in hydrogen atmosphere is reported, and it is revealed that the hydrating nucleation and subsequent growth of alloyed uranium are closely connected with the surface states, underlying metal matrix, and it is microstructure-dependent. In this review, the recent advances in uranium surface chemistry in China, published so far mostly in Chinese language, are briefly summarized. Suggestions for further study are made. (orig.)

  9. Scanning tunneling microscopy study of GaAs(001) surfaces

    Science.gov (United States)

    Xue, Qi-Kun; Hashizume, T.; Sakurai, T.

    1999-03-01

    While GaAs(001) is the most commonly used substrate in fabrication of wireless and opto-electronic devices based on III-V compound semiconductors by molecular beam epitaxy (MBE), metallorganic chemical vapor deposition (MOCVD) and related techniques, its surface structure have been disputed since the beginning of development of the techniques. Invention of scanning tunneling microscopy (STM) has revolutionized the approach of surface/interface investigation, contributing greatly in the atomistic understanding of the GaAs surface phases. This paper reviews the STM studies of principal reconstructions, from As-rich c(4×4), 2×4, 2×6 to Ga-rich 4×2 and 4×6, found on the GaAs (001) surface. These studies, together with advanced theoretical efforts, have helped us to establish a unified structural model for various reconstructions, with which we can now explain most of the observations and long-standing controversies in atomic structures and surface stoichiometries.

  10. Localization of optical excitations on random surfaces: SNOM studies

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    Localization of optical excitations on nanostructured metal surfaces and fractal colloid silver aggregates are studied by using a scanning near-field optical microscope (SNOM). The SNOM images obtained in both configurations exhibit spatially localized (within 150 to 250 nm) light intensity...

  11. Laboratory Study of Dispersion of Buoyant Surface Plumes

    DEFF Research Database (Denmark)

    Petersen, Ole; Larsen, Torben

    1990-01-01

    A laboratory a study on surface dispersion of buoyant plumes in open channel turbulence in made, where the buoyancy is due to both salinity and heat. The measured parameters are the downstream derivative of a plume width and height, which are integral-characteristics of the distributions of density...

  12. THE STUDY OF THERMAL EFFECT ON THE SURFACE ...

    African Journals Online (AJOL)

    Gamma alumina is a good material for catalyst support and its surface properties is of great importance. In this study the gamma-alumina (γ-Al2O3) synthesized to be used as catalyst support for zeolite catalyst was obtained by calcination of ammonium alum an intermediate product prepared from kaolin which was sourced ...

  13. Studies on groundwater recharge through surface drains | Singh ...

    African Journals Online (AJOL)

    Studies on groundwater recharge through surface drains. ... The model gives volume of water recharged for various rainfall events under different antecedent moisture conditions for both free flow and detained flow conditions. The value of recharge rate computed by using the model for a particular depth of flow in the drain ...

  14. A Study of Horizontal Sea Surface Temperature Variability.

    Science.gov (United States)

    1981-12-01

    INTRODUCTION A. BACKGROUND The study of ocean characteristics has long been of interest to men of the sea. Early mariners were the first to discover that...Surface Temperature, J. Phys. Oceanogr., 11, 864-870. Federov, K.N., 1978: The Thermohaline Finestructure of the Ocean, Pergamon Press. Fieux, M., S

  15. Environmental impact assessment for surface coal mine - a case study

    International Nuclear Information System (INIS)

    Sen, P.; Chakraborty, K.

    1994-01-01

    Surface coal mines being the largest contributor to the national coal production, the study of environmental impacts due to this becomes mandatory as it will help in proper planning and safe operations of the mine in an environmentally compatible manner. Within the scope of this paper, a model for preparation of comprehensive environmental impact assessment (EIA) by utilising a new evaluation methodology leading to determination of Environmental Quality Designation an index has been developed and this model has been validated by using data from a running surface coal mine in Wardha Valley Coalfield. Based on this exercise, the overall impact of the surface coal mine under consideration on environment indicates a medium level and accordingly the control measures have to be planned. Thus repair to the environment has to be made a concurrent activity with mining i.e. to say we have to design with nature not against it

  16. STUDY OF SURFACE PHENOMENA IN MATERIALS OF PROSTHETIC RESTORATION

    Directory of Open Access Journals (Sweden)

    Mihaela-Păpuşa Vasiliu

    2012-12-01

    Full Text Available As a direct consequence of their application domain – the oral cavity – dental materials are subjected to the corosive action of saliva, being surrounded by microorganisms, fluids and alimentary rests, which modify their surface characteristics. Concerns on the quality of the dental materials explain the numeorus interdisciplinary studies, characterized by a close relation among various scientific domains (physics, chemistry, biology, science of biomaterials, techniques also applied in clinical stomatology. Analysis of the saliva–dental materials interface made use of ceramic surfaces, composites and artificial saliva, permitting to determine the main surface parameters of the materials of prosthetic restoration, calculated with some physical models, starting from measurements of the contact angle: surface energy, its polar and dispersive components, surface rugosity, adhesion mechanic work. All composites showed low values of the adhesion mechanic work, the conclusion being that they are much more hydrophobic than the ceramic materials. Such a property is especially important from an aesthetic perspective, as the hydrophobic materials have a better colour stability in time.

  17. Surface chemical study on the covalent attachment of hydroxypropyltrimethyl ammonium chloride chitosan to titanium surfaces

    Science.gov (United States)

    Xu, Xiaofen; Wang, Ling; Guo, Shengrong; Lei, Lei; Tang, Tingting

    2011-10-01

    An anti-microbial and bioactive coating could not only reduce the probability of infection related to titanium implants but also support the growth of surrounding osteogenic cells. Our previous study has showed that hydroxypropyltrimethyl ammonium chloride chitosan (HACC) with a DS (degrees of substitution) of 18% had improved solubility and significantly higher antibacterial activities against three bacteria which were usually associated with infections in orthopaedics. In the current study, HACC with a DS of 18% coating was bonded to titanium surface by a three-step process. The titanium surface after each individual reaction step was analyzed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection (ATR) of Fourier-transformed infrared (FT-IR) spectroscopy. The XPS results demonstrated that there were great changes in the atomic ratios of C/Ti, O/Ti, and N/Ti after each reaction step. The XPS high resolution and corresponding devolution spectra of carbon, oxygen, nitrogen, and titanium were also in good coordination with the anticipated reaction steps. Additionally, the absorption bands around 3365 cm -1 (-OH vibration), 1664 cm -1 (Amide I), 1165 cm -1 ( νas, C-O-C bridge), and the broad absorption bands between 958 cm -1 and 1155 cm -1 (skeletal vibrations involving the C-O stretching of saccharide structure of HACC) verified that HACC was successfully attached to titanium surface.

  18. Surface chemical study on the covalent attachment of hydroxypropyltrimethyl ammonium chloride chitosan to titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xu Xiaofen; Wang Ling [School of Pharmacy, Shanghai Jiao Tong University, 800 Dong-chuan Road, Shanghai 200240 (China); Guo Shengrong, E-mail: srguo@sjtu.edu.cn [School of Pharmacy, Shanghai Jiao Tong University, 800 Dong-chuan Road, Shanghai 200240 (China); Lei Lei [School of Pharmacy, Shanghai Jiao Tong University, 800 Dong-chuan Road, Shanghai 200240 (China); Tang Tingting, E-mail: tingtingtang@hotmail.com [Shanghai Key Laboratory of Orthopedic Implant, Department of Orthopedic Surgery, Shanghai Ninth People' s Hospital, Shanghai Jiaotong University School of Medicine (China)

    2011-10-01

    An anti-microbial and bioactive coating could not only reduce the probability of infection related to titanium implants but also support the growth of surrounding osteogenic cells. Our previous study has showed that hydroxypropyltrimethyl ammonium chloride chitosan (HACC) with a DS (degrees of substitution) of 18% had improved solubility and significantly higher antibacterial activities against three bacteria which were usually associated with infections in orthopaedics. In the current study, HACC with a DS of 18% coating was bonded to titanium surface by a three-step process. The titanium surface after each individual reaction step was analyzed by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection (ATR) of Fourier-transformed infrared (FT-IR) spectroscopy. The XPS results demonstrated that there were great changes in the atomic ratios of C/Ti, O/Ti, and N/Ti after each reaction step. The XPS high resolution and corresponding devolution spectra of carbon, oxygen, nitrogen, and titanium were also in good coordination with the anticipated reaction steps. Additionally, the absorption bands around 3365 cm{sup -1} (-OH vibration), 1664 cm{sup -1} (Amide I), 1165 cm{sup -1} ({nu}{sub as}, C-O-C bridge), and the broad absorption bands between 958 cm{sup -1} and 1155 cm{sup -1} (skeletal vibrations involving the C-O stretching of saccharide structure of HACC) verified that HACC was successfully attached to titanium surface.

  19. First-principles study of water on Cu (110) surface

    Science.gov (United States)

    Ren, Jun; Meng, Sheng

    2009-03-01

    The persistent demand for cheaper and high efficient catalysts in industrial chemical synthesis, such as ammonia, and in novel energy applications, hydrogen generation and purification in fuel cells motivated us to study the fundamental interaction involved in water-Cu system, with an intension to examine Cu as a possible competitive candidate for cheaper catalysts. Water structure and dissociation kinetics on a model open metal surface: Cu (110), have been investigated in detail based on first-principles electronic structure calculations. We revealed that in both monomer and overlayer forms, water adsorbs molecularly, with a high tendency for diffusion and/or desorption rather than dissociation on clean surfaces at low temperature. With the increase of the water coverage on the Cu (110) surface, the H-bond pattern lowers the dissociation barrier efficiently. More importantly, if the water molecule is dissociated, the hydrogen atoms can diffuse freely along the [110] direction, which is very useful in the hydrogen collection. In addition, we extended to study water on other noble metal (110) surfaces. The result confirms that Cu (110) is the borderline between intact and dissociative adsorption, differing in energy by only 0.08 eV. This may lead to promising applications in hydrogen generation and fuel cells.

  20. Defective pyrite (100) surface: An ab initio study

    International Nuclear Information System (INIS)

    Stirling, Andras; Bernasconi, Marco; Parrinello, Michele

    2007-01-01

    The structural and electronic properties of sulfur monomeric defects at the FeS 2 (100) surface have been studied by periodic density-functional calculations. We have shown that for a monomeric sulfur bound to an originally fivefold coordinated surface Fe site, the defect core features a triplet electronic ground state with unpaired spins localized on the exposed Fe-S unit. At this site, the iron and sulfur ions have oxidation states +4 and -2, respectively. This defect can be seen as produced via heterolytic bond breaking of the S-S sulfur dimer followed by a Fe-S redox reaction. The calculated sulfur 2p core-level shifts of the monomeric defects are in good agreement with experimental photoemission spectra, which allow a compelling assignment of the different spectroscopic features. The effect of water on the stability of the defective surface has also been studied, and it has been shown that the triplet state is stable against the wetting of the surface. The most important implications of the presence of the monomeric sulfur defect on the reactivity are also discussed

  1. Surface science studies of model fuel cell electrocatalysts

    Science.gov (United States)

    Marković, N. M.; Ross, P. N.

    2002-04-01

    The purpose of this review is to discuss progress in the understanding of electrocatalytic reactions through the study of model systems with surface spectroscopies. Pure metal single crystals and well-characterized bulk alloys have been used quite successfully as models for real (commercial) electrocatalysts. Given the sheer volume of all work in electrocatalysis that is on fuel cell reactions, we will focus on electrocatalysts for fuel cells. Since Pt is the model fuel cell electrocatalyst, we will focus entirely on studies of pure Pt and Pt bimetallic alloys. The electrode reactions discussed include hydrogen oxidation/evolution, oxygen reduction, and the electrooxidation of carbon monoxide, formic acid, and methanol. Surface spectroscopies emphasized are FTIR, STM/AFM and surface X-ray scattering (SXS). The discussion focuses on the relation between the energetics of adsorption of intermediates and the reaction pathway and kinetics, and how the energetics and kinetics relate to the extrinsic properties of the model system, e.g. surface structure and/or composition. Finally, we conclude by discussing the limitations that are reached by using pure metal single crystals and well-characterized bulk alloys as models for real catalysts, and suggest some directions for developing more realistic systems.

  2. Nuclear stimulated desorption as a potential tool for surface study

    International Nuclear Information System (INIS)

    Nir, Dror.

    1993-03-01

    The described research work constitutes a base for an experimental method to be implemented in the study of solid surfaces. Nuclear Stimulated Desorption (NSD) is a new mode of experimentation in thin film and surface physics. It Is based on the interplay between nuclear phenomena (reactions and spontaneous decays), and atomic - scale induced effects on surfaces and very thin films. One may distinguish between two generically different relationships between the two. First, the dynamics of the nuclear reaction -primarily the recoil of the nucleus - may effect the position of the atom or molecule containing it. Second, the nuclear reaction (or decay) may serve as an analytical indicator of the whereabouts of the atom, or molecule, in question. In nuclear stimulated desorption, both thee aspects combine in an essential way. Namely, one employs a series of two consecutive decays (normally weak decays or isomeric transition) . The first of these decays causes the nucleus to desorb from a surface onto which it had been placed; the second serves to determine the position of the daughter and thereby the characteristics of the primary desorption . The essential feature in NSD is that it occurs almost exclusively from the outermost surface layer. This is because we choose to work with nuclei whose recoil energy Is of the same order of magnitude of the binding energy of the atom to the surface . Furthermore, the desorption probability and its angular (and temporal) characteristics, depend on the features (topology, morphology) of its immediate neighborhood. This work describes experiments which were designed to give relevant, phenomenological information about the outgoing flux of the radioactive daughters (for specifically chosen nuclear species) , and in particular the magnitude of the flux, its time dependence and its charged state. In addition. the basic phenomena itself is being distinguished from competing processes (thermal desorption, in particular). We will now

  3. Automated surface quality inspection with ARGOS: a case study

    Science.gov (United States)

    Kiefhaber, Daniel; Etzold, Fabian; Warken, Arno F.; Asfour, Jean-Michel

    2017-06-01

    The commercial availability of automated inspection systems for optical surfaces specified according to ISO 10110-7 promises unsupervised and automated quality control with reproducible results. In this study, the classification results of the ARGOS inspection system are compared to the decisions by well-trained inspectors based on manual-visual inspection. Both are found to agree in 93.6% of the studied cases. Exemplary cases with differing results are studied, and shown to be partly caused by shortcomings of the ISO 10110-7 standard, which was written for the industry standard manual-visual inspection. Applying it to high resolution images of the whole surface of objective machine vision systems brings with it a few challenges which are discussed.

  4. Blastocyst cryopreservation using solid surface vitrification: A preliminary study

    Directory of Open Access Journals (Sweden)

    Mohan S Kamath

    2011-01-01

    Full Text Available Objective: The objective was to evaluate the effectiveness of a blastocyst cryopreservation program using solid surface vitrification. Setting: This study took place in a university teaching hospital. Study Design: Retrospective observational study. Materials and Methods: Women undergoing frozen embryo transfer cycles over a 4-year period between 2006 and 2010 were studied. The cryopreservation policy followed was a vitrification protocol performed at the blastocyst stage, using a solid surface (nonimmersion method. The post-thaw survival rate, implantation rate, clinical pregnancy rate, live birth rate, and neonatal outcome were recorded. Results: Eighty-one women underwent 86 frozen embryo transfer cycles. Of the 240 blastocysts warmed, 204 survived giving a cryosurvival rate of 85% (204/240. The clinical pregnancy, implantation, miscarriage, ongoing pregnancy, and live birth rates per transfer were 47%, 29%, 12%, 16%, and 23% respectively. Of the 20 live births, there were 16 singletons and 4 twins. Eleven boys and 13 girls were delivered with no major or minor abnormality detected. Conclusion(s: The blastocyst vitrification protocol using the solid surface method is effective with results comparable to fresh blastocyst transfers. While retaining the rapid cooling effect, the nonimmersion technique eliminates the risk of contamination and disease transmission. Larger studies with long-term follow-up data would further confirm the efficacy and safety of this method of vitrification.

  5. Estimates of the relative specific yield of aquifers from geo-electrical ...

    African Journals Online (AJOL)

    This paper discusses a method of estimating aquifer specific yield based on surface resistivity sounding measurements supplemented with data on water conductivity. The practical aim of the method is to suggest a parallel low cost method of estimating aquifer properties. The starting point is the Archie's law, which relates ...

  6. Nonlinear optical and optoelectronic studies of topological insulator surfaces

    Science.gov (United States)

    McIver, James W.

    Since their experimental discovery in 2008, topological insulators have been catapulted to the forefront of condensed matter physics research owing to their potential to realize both exciting new technologies as well as novel electronic phases that are inaccessible in any other material class. Their exotic properties arise from a rare quantum organization of its electrons called "topological order,'' which evades the conventional broken symmetry based-classification scheme used to categorize nearly every other state of ordered matter. Instead, topologically ordered phases are classified by topological invariants, which characterize the phase of an electron's wavefunction as it moves through momentum space. When a topologically ordered phase is interfaced with an ordinary phase, such as the vacuum, a novel metallic state appears at their shared boundary. In topological insulators, this results in the formation of a two-dimensional metallic state that spans all of its surfaces. The surface state electronic spectrum is characterized by a single linearly dispersing and helically spin-polarized Dirac cone that is robust against disorder. The helical nature of the surface Dirac cone is highly novel because the Dirac electrons carry a net magnetic moment and are capable of transporting 100% spin-polarized electrical currents, which are the long-sought electronic properties needed for many spin-based electronic applications. However, owing to the small bulk band gap and intrinsic electronic doping inherent to these materials, isolating the surface electronic response from the bulk has proven to be a major experimental obstacle. In this thesis, we demonstrate the means by which light can be used to isolate and study the surface electronic response of topological insulators using optoelectronic and nonlinear optical techniques. In chapter 1, we overview the physics of topological order and topological insulators. In chapter 2, we show how polarized light can be used to

  7. He-atom surface scattering apparatus for studies of crystalline surface dynamics. Progress report, May 1, 1985-April 30, 1986

    International Nuclear Information System (INIS)

    1986-01-01

    The primary goal of this grant is the construction of a state-of-the-art He atom-crystal surface scattering apparatus which will be capable of measuring both elastic and inelastic scattering of He atoms from crystal surfaces of metals, semiconductors and insulators. First, the apparatus will be constructed and characterized, after which a program of studies on the surface dynamics of a variety of crystal surfaces will be started. 6 refs., 2 figs

  8. Immobilizing live Escherichia coli for AFM studies of surface dynamics

    International Nuclear Information System (INIS)

    Lonergan, N.E.; Britt, L.D.; Sullivan, C.J.

    2014-01-01

    Atomic force microscopy (AFM) is a probe-based technique that permits high resolution imaging of live bacterial cells. However, stably immobilizing cells to withstand the probe-based lateral forces remains an obstacle in AFM mediated studies, especially those of live, rod shaped bacteria in nutrient media. Consequently, AFM has been under-utilized in the research of bacterial surface dynamics. The aim of the current study was to immobilize a less adherent Escherichia coli strain in a method that both facilitates AFM imaging in nutrient broth and preserves overall cell viability. Immobilization reagents and buffers were systematically evaluated and the cell membrane integrity was monitored in all sample preparations. As expected, the biocompatible gelatin coated surfaces facilitated stable cell attachment in lower ionic strength buffers, yet poorly immobilized cells in higher ionic strength buffers. In comparison, poly-L-lysine surfaces bound cells in both low and high ionic strength buffers. The benefit of the poly-L-lysine binding capacity was offset by the compromised membrane integrity exhibited by cells on poly-L-lysine surfaces. However, the addition of divalent cations and glucose to the immobilization buffer was found to mitigate this unfavorable effect. Ultimately, immobilization of E. coli cells on poly-L-lysine surfaces in a lower ionic strength buffer supplemented with Mg 2+ and Ca 2+ was determined to provide optimal cell attachment without compromising the overall cell viability. Cells immobilized in this method were stably imaged in media through multiple division cycles. Furthermore, permeability assays indicated that E. coli cells recover from the hypoosmotic stress caused by immobilization in low ionic strength buffers. Taken together, this data suggests that stable immobilization of viable cells on poly-L-lysine surfaces can be accomplished in lower ionic strength buffers that are supplemented with divalent cations for membrane stabilization while

  9. Numerical study on condensation heat transfer of trapezoid grooved surfaces

    Directory of Open Access Journals (Sweden)

    Baojin Qi

    2016-05-01

    Full Text Available This article presents a numerical analysis and experimental study on condensation heat transfer and fluid flow for filmwise condensation on trapezoid grooved surfaces. First, a physical model was properly simplified based on some reasonable assumptions. Then, the coupled non-linear governing equations for the mass transfer, fluid flow, and two-dimensional thermal conduction were developed. The relationship between z-coordinate and heat transfer was obtained by solving the equations numerically. The influences of groove length and basic angle were discussed. The calculation results showed that the heat flux decreased with increase in groove length, and the decline range also decreased gradually. The calculation results also suggested that the heat flux through groove with α = 60° was lower than the groove with α = 75° at the top of the groove, while the opposite conclusion was obtained at the low parts. The distributions of wall temperature and heat flux on trapezoid groove were also studied systematically. The distribution of surface temperature and heat flux presents obvious lateral inhomogeneity, and the maximum wall temperature and heat flux were both obtained in region II. The thermal resistance of groove with α = 60° was lower but the liquid-discharged ability was better than that of groove with α = 75°. In order to validate the feasibility and reliability of the present analyses and to further investigate the heat transfer performance of trapezoid grooved surfaces, experiments were carried out with three condensing plates including two trapezoid grooved surfaces in different physical dimensions and one smooth surface. The experimental data obtained under various schooling were compared with the calculations, and the experimental results for different condensing plates are all in good agreement with the numerical model, with a maximum deviation less than 15%. Moreover, the trapezoid grooves can enhance the

  10. Experimental study of liquid drop impact onto a powder surface

    KAUST Repository

    Marston, Jeremy

    2010-11-01

    The initial dynamics of liquid drop impact onto powder surfaces is studied experimentally using high-speed photography. For a range of bed packing fractions, φ, liquid physical properties and impact velocities, ui, we observe a variety of phenomena that can be representative of a hydrophobic surface, a rough surface or a porous medium. The solids packing fraction in the bed, 0.38≤φ≤0.65, and the impact Weber number, 3.5≤We=ρDui 2/φ≤750, (where ρ, D and φ are the drop density, diameter and surface tension respectively) are shown to be the critical parameters governing the outcome of an impact. For high packing fractions, φ≳0.5, we show that the observed spreading, rebound and splashing can be broadly characterised in terms of the Weber number while for looser packing fractions, φ≲0.5, we observe powder ejectas and provide a qualitative description of the granule nucleation at the centre of the impact sites. © 2010 Elsevier B.V.

  11. STUDY OF SURFACE PHENOMENA IN MATERIALS OF PROSTHETIC RESTORATION

    OpenAIRE

    Mihaela-Păpuşa Vasiliu; Carmen Stadoleanu; Daniela Ivona Tomiţa; Cristina-Mihaela Stanilă; S.-C. Jalbă; Nicoleta Dumitraşcu

    2012-01-01

    As a direct consequence of their application domain – the oral cavity – dental materials are subjected to the corosive action of saliva, being surrounded by microorganisms, fluids and alimentary rests, which modify their surface characteristics. Concerns on the quality of the dental materials explain the numeorus interdisciplinary studies, characterized by a close relation among various scientific domains (physics, chemistry, biology, science of biomaterials), techniqu...

  12. Tribological approach to study polishing of road surface under traffic

    OpenAIRE

    KANE, Malal; DO, Minh Tan

    2007-01-01

    The polishing phenomenon of road pavements under the vehicle traffic constitutes the main mechanism inherent to the loss of skid resistance over time. A better understanding of this phenomenon would allow an improvement of road safety. This study comprises a review of laboratory test and a model simulating the polishing of road surfaces. The laboratory test uses a polishing machine so called 'Wehner-Schulze' which can reproduce the evolution of the road texture from specimens taken directly f...

  13. Methods to study microbial adhesion on abiotic surfaces

    Directory of Open Access Journals (Sweden)

    Ana Meireles

    2015-09-01

    Full Text Available Microbial biofilms are a matrix of cells and exopolymeric substances attached to a wet and solid surface and are commonly associated to several problems, such as biofouling and corrosion in industries and infectious diseases in urinary catheters and prosthesis. However, these cells may have several benefits in distinct applications, such as wastewater treatment processes, microbial fuel cells for energy production and biosensors. As microbial adhesion is a key step on biofilm formation, it is very important to understand and characterize microbial adhesion to a surface. This study presents an overview of predictive and experimental methods used for the study of bacterial adhesion. Evaluation of surface physicochemical properties have a limited capacity in describing the complex adhesion process. Regarding the experimental methods, there is no standard method or platform available for the study of microbial adhesion and a wide variety of methods, such as colony forming units counting and microscopy techniques, can be applied for quantification and characterization of the adhesion process.

  14. Hand surface area as a percentage of body surface area in Asian children: a pilot study.

    Science.gov (United States)

    Choi, Hyuk; Park, Man Sik; Lee, Heung-Man

    2011-09-01

    The hand surface area (HSA) of one hand has been estimated as 1% of the body surface area (BSA). This does change with the patient's age, gender, and body mass index (BMI). There are many HSA studies done on adult populations, but fewer done on children. Our hypothesis in this study is that the general HSA equation for Caucasian adults cannot be applied as accurately to children and Asian people. HSA was defined as the area of the palm without fingers in this study. Children are in a stage of growth. If a child's hand growth ratio is not the same as that of an adult, the result of HSA/BSA calculation could be different. We undertook this study to determine whether or not there were any differences in HSA/BSA among Korean children (7-18 years) and adults (20-60 years), and compared our results with western data. A total of 186 boys aged between 7 and 18 years, were recruited for this study; their HSA was measured, directly. A total of 186 adults aged between 20 and 60 years were selected as well. BSA was calculated only for volunteers in subjects who HSA had been measured. From these results, HSA/BSA was calculated. HSA/BSA ratio of Korean boys was 0.69±0.05%, which was less than 1%. It is suggested that the ratio of the western data may not be applicable to Asian children, particularly, Korean children. HSA/BSA ratio can be applied in administration of drug doses and estimation of the area of burns. Copyright © 2011 Elsevier Ltd and ISBI. All rights reserved.

  15. Monochromator on a synchrotron undulator source for liquid surface studies

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Freund, A.K.

    1992-01-01

    For liquid surface studies a monochromatic beam of relative bandwidth between 0.1% and 1% at a variable angle in the vertical plane between 0-degrees and 10-degrees is needed. The beam should be like a sheet some tens of mu-m thick and some mm wide, and as intense as possible. We discuss a monoch......For liquid surface studies a monochromatic beam of relative bandwidth between 0.1% and 1% at a variable angle in the vertical plane between 0-degrees and 10-degrees is needed. The beam should be like a sheet some tens of mu-m thick and some mm wide, and as intense as possible. We discuss......% of the useful x rays, in full agreement with diffraction theory including secondary extinction. Heat load experiments reported elsewhere in this conference prove that Be crystals can withstand high beam power density and that the thermal deformation is small compared to the mosaic spread. The results...... of the flux calculations are most encouraging: a gain of order 10(3) to 10(4) can be expected as compared to existing liquid surface spectrometers....

  16. Study of surface an atmospheric pollution in radioiodine from Hospitals

    International Nuclear Information System (INIS)

    Gomez Palacios, M.; Cuetos Menendez, A.

    1999-01-01

    In hospitals environment, the radioactive iodine surface contamination is one of the most important incident from the point of view of radiation protection. Among this kind of incidents we can consider vomit or urine spillage from ''131 I therapy or spillage of liquids contaminated with ''125 I from RIA laboratories. We have studied the dynamic of the contamination flow from the contaminated surface to the indoor air, using total activity in the spill, indoor air renewal rate, and resuspension rate as parameters. We describe a method to estimate the resuspension rate, assuming that this parameter is usually unknown, and its results for the following cases: urine or water, on paper-covered or uncovered plastic surface. By using the experimental results, we have studied the indoor air contamination evolution with time, as a function of both initial activity, and indoor air renewal rate. The maximum value of indoor air contamination is not dependent on the initial activity value. The resuspension process is slower in the case of urine spillage that in watery leakage. The use of porous paper may establish the difference between keeping and indoor air contamination below derived air concentration limit (CDAC), or clearly above DAC for may days. The indoor air contamination dependence from the air renewal rate, shows the convenience of high air renewal rate in places where contamination from ''131 I therapy were possible, and how although this factor is not so critical, it should be taken into account in RIA laboratories. (Author) 6 refs

  17. DFT study of water adsorption on lignite molecule surface.

    Science.gov (United States)

    Gao, Zhengyang; Ding, Yi; Yang, Weijie; Han, Wentao

    2017-01-01

    High moisture content is a main characteristic of low-rank coal, such as lignite. Numerous oxygen containing functional groups in lignite make it represent some special properties, and these functional groups affect the adsorption mechanisms of water molecules on lignite surface. This study reports some typical water · · · lignite conformations, along with a detailed analysis of the geometry, electrostatic potential distribution, reduced density gradient of interaction, and interaction energy decomposition. The results show that water molecules tend to aggregate around functional groups, and hydrogen bonds play a dominant role in the interaction. The adsorption energy of water cluster on lignite surface is larger than that of isolated water molecule, a good linear relationship between the interaction distance and adsorption energy of layers has been found. Since water is a polar molecule, the local minima and maxima of electrostatic potential in conformations increase along with more water adsorbing on lignite surface. Reduced density gradient analysis shows that H-bonds, van der Waals interaction, and a little steric make up the interaction between water cluster and lignite molecule. In these studied conformations which mainly are H-bond complexes, electrostatic and exchange repulsion play a dominant role, whereas polarization and dispersion make relatively small contribution to the interaction. Attractive and repulsive interaction both affect the stability of water · · · lignite conformations.

  18. Thermal desorption study of physical forces at the PTFE surface

    Science.gov (United States)

    Wheeler, D. R.; Pepper, S. V.

    1987-01-01

    Thermal desorption spectroscopy (TDS) of the polytetrafluoroethylene (PTFE) surface was successfully employed to study the possible role of physical forces in the enhancement of metal-PTFE adhesion by radiation. The thermal desorption spectra were analyzed without assumptions to yield the activation energy for desorption over a range of xenon coverage from less than 0.1 monolayer to more than 100 monolayers. For multilayer coverage, the desorption is zero-order with an activation energy equal to the sublimation energy of xenon. For submonolayer coverages, the order for desorption from the unirradiated PTFE surface is 0.73 and the activation energy for desorption is between 3.32 and 3.36 kcal/mol; less than the xenon sublimation energy. The effect of irradiation is to increase the activation energy for desorption to as high as 4 kcal/mol at low coverage.

  19. The studies of scale surface produced on outer diffusion layers

    Directory of Open Access Journals (Sweden)

    J. Augustyn-Pieniążek

    2011-04-01

    Full Text Available In this study at attempt was made to examine the scale formed on ferritic-austenitic duplex type steel subjected to previous thermochemical treatment. The treatment consisted in diffusion aluminising in a metallising mixture composed of Fe-Al powder. As an activator, ammonium chloride (NH4Cl added in an amount of 2 wt.% was used. Then, both the base material and samples with the diffusiondeposited surface layers were oxidised at 1000°C in the air. Thus formed scales were identified by light microscopy, SEM and X-ray phase analysis. The aim of the oxidation tests carried out under isothermal conditions was to compare the scale morphology when obtained on untreated substrate material and on the surface layers rich in aluminium.

  20. Hazards and operability study for the surface moisture monitoring system

    International Nuclear Information System (INIS)

    Board, B.D.

    1996-01-01

    The Hanford Nuclear Reservation Tank Farms' underground waste tanks have been used to store liquid radioactive waste from defense materials production since the 1940's. Waste in certain of the tanks may contain material in the form of ferrocyanide or various organic compounds which could potentially be susceptible to condensed phase chemical reactions. Because of the presence of oxidizing materials (nitrate compounds) and heat sources (radioactive decay and chemical reactions), the ferrocyanide or organic material could potentially fuel a propagating exothermic reaction with undesirable consequences. Analysis and experiments indicate that the reaction propagation and/or initiation may be prevented by the presence of sufficient moisture in the waste. Because the reaction would probably be initiated at the surface of the waste, evidence of sufficient moisture concentration would help provide evidence that the tank waste can continue to be safely stored. The Surface Moisture Measurement System (SMMS) was developed to collect data on the surface moisture in the waste by inserting two types of probes (singly) into a waste tank-a neutron probe and an electromagnetic inductance (EMI) probe. The sensor probes will be placed on the surface of the waste utilizing a moveable deployment arm to lower them through an available riser. The movement of the SMMS within the tank will be monitored by a camera lowered through an adjacent riser. The SMMS equipment is the subject of this study. Hazards and Operability Analysis (HAZOP) is a systematic technique for assessing potential hazards and/or operability problems for a new activity. It utilizes a multidiscipline team of knowledgeable individuals in a systematic brainstorming effort. The results of this study will be used as input to an Unreviewed Safety Question determination

  1. Electron spectroscopy studies of surface In-Ag alloy formation on the tungsten surface

    International Nuclear Information System (INIS)

    Bukaluk, A.; Trzcinski, M.; Okulewicz, K.

    2008-01-01

    XPS and UPS investigations of ultrathin films of In/Ag and Ag/In, deposited onto the W(1 1 0) surface in the ultrahigh vacuum conditions have been performed. Indium and silver films were formed by 'in-situ' evaporation on W(1 1 0) substrate. XPS and UPS studies have been performed by means of SCIENTA ESCA200 instrument. The changes of In4d core-level and Ag4d valence band emissions with increasing Ag and In coverage were monitored to observe the energy shift and shape of the spin-orbit doublet of In4d and Ag4d lines in the Ag/In/W and In/Ag/W systems. UPS (HeI and HeII) measurements were supported by XPS AlK α measurements of In3d and W4p levels, as well as by investigations of Ag3d levels. XPS and UPS data allowed to evaluate the coverage and make conclusions concerning intermixing and surface alloying in the In/Ag/W and Ag/In/W systems. W(1 1 0) substrate can be cleaned after each deposition by thermal desorption and no alloying in the In/W and Ag/W systems is observed

  2. Photoelectron diffraction studies of small adsorbates on single crystal surfaces

    International Nuclear Information System (INIS)

    Pascal, Mathieu

    2002-01-01

    The structural determination of small molecules adsorbed on single crystal surfaces has been investigated using scanned energy mode photoelectron diffraction (PhD). The experimental PhD data were compared to theoretical models using a simulation program based on multiple scattering calculations. Three adsorption systems have been examined on Ag(110), Cu(110) and Cu(111) crystals. The structure of the (2x1)-O adsorption phase on Ag(110) revealed that the O atoms occupied the long bridge site and are almost co-planar with the top layer of Ag atoms. The best agreement between multiple scattering theory and experiment has been obtained for a missing-row (or equivalently an 'added- row') reconstruction. Alternative buckled-row and unreconstructed surface models can be excluded. The adsorption of the benzoate species on Cu(110) has been found to occur via the carboxylate group. The molecules occupy short bridge sites with the O atoms being slightly displaced from atop sites and are aligned along the close-packed azimuth. The tilt of the molecule with respect to the surface and the degree to which the surface is relaxed have also been investigated. The adsorption of methyl on Cu(111) was studied using either azomethane or methyl iodide to prepare the surface layers. At saturation coverage the preferred adsorption site is the fcc threefold hollow site, whereas at half saturation coverage ∼ 30 % of the methyl species occupy the hop threefold hollow sites. Best agreement between theory and experiment corresponded to a methyl group adsorbed with C 3v symmetry. The height of the C above the surface in a pure methyl layer was 1.66 ± 0.02 A, but was reduced to 1.62 ± 0.02 A in the presence of co-adsorbed iodine, suggesting that iodine increases the strength of adsorption. Iodine was also found to occupy the fee threefold hollow sites with a Cu-l bondlength of 2.61 ± 0.02 A. (author)

  3. Study of surface tension and surface properties of binary alcohol/n-alkyl acetate mixtures.

    Science.gov (United States)

    Rafati, Amir Abbas; Ghasemian, Ensieh

    2008-12-15

    The Butler equation is employed to describe quantitatively the nature, properties, and compositions of surface layers in binary liquid mixtures. Bulk mole fraction, surface molar area, and surface tension of pure components are necessary inputs for this equation. In addition, the UNIFAC group contribution method is applied to account for the nonideality of the bulk liquid as well as that of the surface layer. The average relative error obtained from the comparison of experimental and calculated surface tension values for 12 binary systems is less than 1%. Therefore, the model has good accuracy in comparison with other predictive equations. In addition to finding more information about the surface structure of binary mixtures, surface mole fraction was calculated using relative Gibbs adsorption values and an extended Langmuir model (EL). The obtained results show a good consistency between two models employed, i.e., the Gibbs adsorption model and EL model, based on the UNIFAC method.

  4. Theoretical studies of potential energy surfaces and computational methods

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, R. [Argonne National Laboratory, IL (United States)

    1993-12-01

    This project involves the development, implementation, and application of theoretical methods for the calculation and characterization of potential energy surfaces involving molecular species that occur in hydrocarbon combustion. These potential energy surfaces require an accurate and balanced treatment of reactants, intermediates, and products. This difficult challenge is met with general multiconfiguration self-consistent-field (MCSCF) and multireference single- and double-excitation configuration interaction (MRSDCI) methods. In contrast to the more common single-reference electronic structure methods, this approach is capable of describing accurately molecular systems that are highly distorted away from their equilibrium geometries, including reactant, fragment, and transition-state geometries, and of describing regions of the potential surface that are associated with electronic wave functions of widely varying nature. The MCSCF reference wave functions are designed to be sufficiently flexible to describe qualitatively the changes in the electronic structure over the broad range of geometries of interest. The necessary mixing of ionic, covalent, and Rydberg contributions, along with the appropriate treatment of the different electron-spin components (e.g. closed shell, high-spin open-shell, low-spin open shell, radical, diradical, etc.) of the wave functions, are treated correctly at this level. Further treatment of electron correlation effects is included using large scale multireference CI wave functions, particularly including the single and double excitations relative to the MCSCF reference space. This leads to the most flexible and accurate large-scale MRSDCI wave functions that have been used to date in global PES studies.

  5. Study of dopamine reactivity on platinum single crystal electrode surfaces

    International Nuclear Information System (INIS)

    Chumillas, Sara; Figueiredo, Marta C.; Climent, Víctor; Feliu, Juan M.

    2013-01-01

    Dopamine is the biological molecule responsible, among other functions, of the heart beat and blood pressure regulation. Its loss, in the human body, can result in serious diseases such as Parkinson's, schizophrenia or depression. Structurally, this molecule belongs to the group of catecholamines, together with epinephrine (adrenaline) and norepinephrine (noradrenaline). The hydroquinone moiety of the molecule can be easily oxidized to quinone, rendering the electrochemical methods a convenient approach for the development of dopamine biosensors. The reactivity of similar aromatic molecules, such as catechol and hydroquinone, at well-ordered platinum surfaces, has recently been investigated in our group. In this paper, we extend these studies to the structurally related molecule dopamine. The study has been performed in neutral pH, since this is closer to the natural conditions for these molecules in biological media. Cyclic voltammetry and in situ infra-red spectroscopy have been combined to extract information about the behavior of this molecule on well-defined platinum surfaces. Dopamine appears to be electrochemically active and reveals interesting adsorption phenomena at low potentials (0.15–0.25 V vs RHE), sensitive to the single crystal orientation. The adsorption of dopamine on these surfaces is very strong, taking place at much lower potentials than the electron transfer from solution species. Specifically, the voltammetry of Pt(1 1 1) and Pt(1 0 0) in dopamine solutions shows an oxidation peak at potentials close to the onset of hydrogen evolution, which is related to the desorption of hydrogen and the adsorption of dopamine. On the other hand, adsorption on Pt(1 1 0) is irreversible and the surface appears totally blocked. Spectroscopic results indicate that dopamine is adsorbed flat on the surface. At potentials higher than 0.6 V vs RHE the three basal planes show a common redox process. The initial formation of the quinone moiety is followed by a

  6. Use of Radiotracers to Study Surface Water Processes

    International Nuclear Information System (INIS)

    2015-03-01

    This publication represents a sound knowledge base for the conduct of radiotracer studies in the environment, with papers on radiotracer methodology, radiation protection and regulation, data analysis and modelling. Environmental case histories from five Member States - Australia, Brazil, France, the Republic of Korea and Sweden - provide information on conducting studies involving he use of radioactive tracers. These case histories are not meant as guidelines for preparing a field study but can rather serve as examples of the type, caution and extent of work involved in environmental studies using radiotracers. This publication can provide guidance for conducting potential future training events in the use of radioactive traces in the environment and can serve as a key reference to all concerned directly with surface water processes

  7. Theoretical study of the surface resistivity of (111) surfaces of NixPt1-x(111) alloys

    International Nuclear Information System (INIS)

    Rous, P. J.

    2001-01-01

    A layer-Korringa - Kohn - Rostoker calculation is used to study the compositional dependence of the surface resistivity of the (111) surface of Ni x Pt 1-x (111) alloys. The compositional disorder in the bulk and at the surface is described by the coherent potential approximation. If it is assumed that the atomic planes near the (111) surface Ni x Pt 1-x have the same composition as the bulk layers, then a weak Nordheim effect is observed in the compositional dependence of the surface resistivity. However, we show that surface segregation in Ni x Pt 1-x (111) causes an inverse Nordheim dependence in the actual surface resistivity as the bulk composition is varied. [copyright] 2001 American Institute of Physics

  8. Feasibility of using a seismic surface wave method to study seasonal and weather effects on shallow surface soils

    Science.gov (United States)

    The objective of this paper is to study the feasibility of using a seismic surface wave method to investigate seasonal and weather effects on shallow surface soils. In the study, temporal variations of subsurface soil properties were measured and monitored by using a combination of a new seismic su...

  9. Organic synthesis - applications in enzymatic studies, catalysis and surface modification

    DEFF Research Database (Denmark)

    Viart, Helene Marie-France

    as liposomes and the enzymatic activity was studied. Hydrolysis (or absence of hydrolysis) was monitored by MALDI-TOF-MS. The results observedin these experiments are compared to MD predictions and confirm them. The second chapter deals with surface functionalization of liposomes. The copper mediated [3......: a C3symmetric phosphine oxide has been synthesised, which we intend to test, after reduction to the phosphin, as a ligand in organometallic catalysed reactions. The ultimate goal is to obtain enantioselectivity, introduced by the organization of aryl substituents around phosphorous in our ligand....

  10. Swallowing in patients with Parkinson's disease: a surface electromyography study.

    Science.gov (United States)

    Ws Coriolano, Maria das Graças; R Belo, Luciana; Carneiro, Danielle; G Asano, Amdore; Al Oliveira, Paulo José; da Silva, Douglas Monteiro; G Lins, Otávio

    2012-12-01

    Our goal was to study deglutition of Parkinson's disease (PD) patients and normal controls (NC) using surface electromyography (sEMG). The study included 15 patients with idiopathic PD and 15 age-matched normal controls. Surface electromyography was collected over the suprahyoid muscle group. Conditions were the following: swallow at once 10 and 20 ml of water and 5 and 10 ml of yogurt of firm consistency, and freely drink 100 ml of water. During swallowing, durations of sEMG were significantly longer in PD patients than in normal controls but no significant differences of amplitudes were found. Eighty percent of the PD patients and 20 % of the NC needed more than one swallow to consume 20 ml of water, while 70 % of the PD patients and none of the NC needed more than one swallow to consume 5 ml of yogurt. PD patients took significantly more time and needed significantly more swallows to drink 100 ml of water than normal controls. We conclude that sEMG might be a simple and useful tool to study and monitor deglutition in PD patients.

  11. Studies of drag on the nanocomposite superhydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Brassard, Jean-Denis [Anti-icing Materials International Laboratory (AMIL), Université du Québec à Chicoutimi, 555 Boulevard de l‘Université, Chicoutimi, Québec, Canada G7H 2B1 (Canada); Centre Universitaire de Recherche sur l’Aluminium (CURAL), Université du Québec à Chicoutimi, 555 Boulevard de l‘Université, Chicoutimi, Québec, Canada G7H 2B1 (Canada); Sarkar, D.K., E-mail: dsarkar@uqac.ca [Centre Universitaire de Recherche sur l’Aluminium (CURAL), Université du Québec à Chicoutimi, 555 Boulevard de l‘Université, Chicoutimi, Québec, Canada G7H 2B1 (Canada); Perron, Jean [Anti-icing Materials International Laboratory (AMIL), Université du Québec à Chicoutimi, 555 Boulevard de l‘Université, Chicoutimi, Québec, Canada G7H 2B1 (Canada)

    2015-01-01

    Graphical abstract: - Highlights: • The nanocomposite thin films of stearic acid (SA)-functionalized ZnO nanoparticles incorporated in epoxy polymer matrix have been achieved. • SA-functionalization of ZnO nanoparticles in the thin films was confirmed by XRD and FTIR. • The measured rms roughness of the thin film is found to be 12 ± 1 μm with the adhesion of 5B on glass. • The wetting property shows that the surface of the film is superhydrophobic with the CA of 156 ± 4° and CAH of 4 ± 2°. • The drag reduction on the surface of superhydrophobic glass sphere is 16% lower than as-received glass sphere. - Abstract: The nanocomposite thin films of stearic acid (SA)-functionalized ZnO nanoparticles incorporated in epoxy polymer matrix have been achieved. The X-ray diffraction (XRD) studies show the formation of zinc stearate on ZnO nanoparticles as the confirmation of SA-functionalization of ZnO nanoparticles in the thin films. Morphological analyses reveal the presence of micro-holes with the presence of irregular nanoparticles. The measured root mean square (rms) roughness of the thin film is found to be 12 ± 1 μm with the adhesion of 5B on both glass and aluminum substrates. The wetting property shows that the surface of the film is superhydrophobic with the contact angle of water of 156 ± 4° having contact angle hysteresis (CAH) of 4 ± 2°. The average terminal velocity in the water of the as-received glass spheres and superhydrophobic spheres were found to be 0.66 ± 0.01 m/s and 0.72 ± 0.01 m/s respectively. Consequently, the calculated average coefficients of the surface drag of the as-received glass sphere and superhydrophobic glass sphere were 2.30 ± 0.01 and 1.93 ± 0.03, respectively. Hence, the drag reduction on the surface of superhydrophobic glass sphere is found to be approximately 16% lower than as-received glass sphere.

  12. Studies of drag on the nanocomposite superhydrophobic surfaces

    International Nuclear Information System (INIS)

    Brassard, Jean-Denis; Sarkar, D.K.; Perron, Jean

    2015-01-01

    Graphical abstract: - Highlights: • The nanocomposite thin films of stearic acid (SA)-functionalized ZnO nanoparticles incorporated in epoxy polymer matrix have been achieved. • SA-functionalization of ZnO nanoparticles in the thin films was confirmed by XRD and FTIR. • The measured rms roughness of the thin film is found to be 12 ± 1 μm with the adhesion of 5B on glass. • The wetting property shows that the surface of the film is superhydrophobic with the CA of 156 ± 4° and CAH of 4 ± 2°. • The drag reduction on the surface of superhydrophobic glass sphere is 16% lower than as-received glass sphere. - Abstract: The nanocomposite thin films of stearic acid (SA)-functionalized ZnO nanoparticles incorporated in epoxy polymer matrix have been achieved. The X-ray diffraction (XRD) studies show the formation of zinc stearate on ZnO nanoparticles as the confirmation of SA-functionalization of ZnO nanoparticles in the thin films. Morphological analyses reveal the presence of micro-holes with the presence of irregular nanoparticles. The measured root mean square (rms) roughness of the thin film is found to be 12 ± 1 μm with the adhesion of 5B on both glass and aluminum substrates. The wetting property shows that the surface of the film is superhydrophobic with the contact angle of water of 156 ± 4° having contact angle hysteresis (CAH) of 4 ± 2°. The average terminal velocity in the water of the as-received glass spheres and superhydrophobic spheres were found to be 0.66 ± 0.01 m/s and 0.72 ± 0.01 m/s respectively. Consequently, the calculated average coefficients of the surface drag of the as-received glass sphere and superhydrophobic glass sphere were 2.30 ± 0.01 and 1.93 ± 0.03, respectively. Hence, the drag reduction on the surface of superhydrophobic glass sphere is found to be approximately 16% lower than as-received glass sphere

  13. Zinc surface complexes on birnessite: A density functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kideok D.; Refson, Keith; Sposito, Garrison

    2009-01-05

    Biogeochemical cycling of zinc is strongly influenced by sorption on birnessite minerals (layer-type MnO2), which are found in diverse terrestrial and aquatic environments. Zinc has been observed to form both tetrahedral (Zn{sup IV}) and octahedral (Zn{sup VI}) triple-corner-sharing surface complexes (TCS) at Mn(IV) vacancy sites in hexagonal birnessite. The octahedral complex is expected to be similar to that of Zn in the Mn oxide mineral, chalcophanite (ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O), but the reason for the occurrence of the four-coordinate Zn surface species remains unclear. We address this issue computationally using spin-polarized Density Functional Theory (DFT) to examine the Zn{sub IV}-TCS and Zn{sup VI}-TCS species. Structural parameters obtained by DFT geometry optimization were in excellent agreement with available experimental data on Zn-birnessites. Total energy, magnetic moments, and electron-overlap populations obtained by DFT for isolated Zn{sup IV}-TCS revealed that this species is stable in birnessite without a need for Mn(III) substitution in the octahedral sheet and that it is more effective in reducing undersaturation of surface O at a Mn vacancy than is Zn{sub VI}-TCS. Comparison between geometry-optimized ZnMn{sub 3}O{sub 7} {center_dot} 3H{sub 2}O (chalcophanite) and the hypothetical monohydrate mineral, ZnMn{sub 3}O{sub 7} {center_dot} H{sub 2}O, which contains only tetrahedral Zn, showed that the hydration state of Zn significantly affects birnessite structural stability. Finally, our study also revealed that, relative to their positions in an ideal vacancy-free MnO{sub 2}, Mn nearest to Zn in a TCS surface complex move toward the vacancy by 0.08-0.11 {angstrom}, while surface O bordering the vacancy move away from it by 0.16-0.21 {angstrom}, in agreement with recent X-ray absorption spectroscopic analyses.

  14. Oynophagia in patients after dental extraction: surface electromyography study

    Directory of Open Access Journals (Sweden)

    Nahlieli Oded

    2006-10-01

    Full Text Available Abstract Objectives Surface electromyographic (sEMG studies were performed on 40 adult patients following extraction of lower third and second molars to research the approach and limitations of sEMG evaluation of their odynophagia complaints. Methods Parameters evaluated during swallowing and drinking include the timing, number of swallows per 100 cc of water, and range (amplitude of EMG activity of m. masseter, infrahyoid and submental-submandibular group. The above mentioned variables (mean + standard deviation were measured for the group of dental patients (n = 40 and control group of healthy adults (n = 40. Results The duration of swallows and drinking in all tests showed increase in dental patients' group, in which this tendency is statistically significant. There was no statistically significant difference between male and female adults' duration and amplitude of muscle activity during continuous drinking in both groups (p = 0.05. The mean of electric activity (in μV of m. masseter was significantly lower in the dental patients' group in comparison with control group. The electric activity of submental-submandimular and infrahyoid muscle groups was the same in both groups. Conclusion Surface EMG of swallowing is a simple and reliable noninvasive method for evaluation of odynophagia/dysphagia complaints following dental extraction with low level of discomfort of the examination. The surface EMG studies prove that dysphagia following dental extraction and molar surgery has oral origin, does not affect pharingeal segment and submental-submandibular muscle group. This type of dysphagia has clear EMG signs: increased duration of single swallow, longer drinking time, low range of electric activity of m. masseter, normal range of activity of submental-submandibular muscle group, and the "dry swalow" aftereffect. The data can be used for evaluation of complaints and symptoms, as well as for comparison purposes in pre- and postoperative stages and

  15. STUDY OF SURFACE MODIFIED POLYMERS IN THE MODIFICATION OF NANOMATERIALS

    Directory of Open Access Journals (Sweden)

    G. V. Popov

    2014-01-01

    Full Text Available The comparative study of change of surface tension of solutions of some commercial rubbers before and after thermal ageing technique du-Nui, analyzed the features of change of surface tension of solutions of various rubbers in the presence of a mixture of fullerenes. Calculations of the Gibbs energy and the analysis of the obtained data to predict the behavior of polymer systems when changes are made to mix of fullerenes in a wide concentration range. When comparing the results of changes in Gibbs energy and the surface tension in fluids rubbers shown that mentioned above in solutions of elastomers aged, than the control. This fact confirms the initial chapeau of physic-chemical interactions of molecules fullerenes by segments of the Kuna and end groups of the polymer chains, as it is known that when thermal-oxidative degradation of rubbers, respectively the number of segments of the Kuna and branched loose ends of macromolecules that are free to react with fullerenes in solution, free from spatial constraints. A comparative analysis of the interaction of rubbers with different chemical composition with double branches has shown that it is easier to just react and has minimum energy polibutadien interaction that has to do with lack of branching and no radicals in its structure and in the backbone chain. The maximum energy of interaction with Fullerenes have SBS rubber because it has large styrene blocks in the main polymer chain that causes the spatial constraints to direct contact with fullerene molecules, you can assume that the interaction is only low-molecular fraction of Fullerenes mixture, possessing the necessary dimensions. As a result of the study shows that the application of the method of separation ring (Du-Nui allows you to predict the properties of rubber with modified nanomaterial’s with minimal labor costs.

  16. Studies on the treatment of surface water using rajma seeds

    Science.gov (United States)

    Merlin, S. Babitha; Abirami, M.; Kumar, R. Suresh

    2018-03-01

    Indiscriminate disposal of wastewater with suspended solids have led to higher amount of pollution to the natural water bodies. Turbidity removal becomes an essential part in the water treatment when surface water is used for drinking purpose, this can be achieved by means of coagulation process. Coagulation process is the dosing of a coagulant in water, resulting in the destabilization of negatively charged particles. Commercial coagulants which were widely used can synthesize by-products in turn may pollute the environment and deteriorate the ecosystem at a slow rate. So, now-a-days natural coagulants are used as a potential substitute because it's biodegradable, ecofriendly and non-toxic. In this study, the turbid surface water samples were treated using powdered seeds of Rajma (natural coagulant) followed by variations in dosage, settling time and pH were also studied. From the results obtained, it was found that the Rajma seeds powder achieved 48.80% efficiency for 0.5 g/l of optimum dose at pH 6 for 20 min settling time respectively.

  17. A molecular surface science study of the structure of adsorbates on surfaces: Importance to lubrication

    International Nuclear Information System (INIS)

    Mate, C.M.

    1986-09-01

    The interaction and bonding of atoms and molecules on metal surfaces is explored under ultra-high vacuum conditions using a variety of surface science techniques: high resolution electron energy loss spectroscopy (HREELS), low energy electron diffraction (LEED), thermal desorption spectroscopy (TDS), Auger electron spectroscopy (AES), work function measurements, and second harmonic generation (SHG). 164 refs., 51 figs., 3 tabs

  18. Surface-ionization field mass-spectrometry studies of nonequilibrium surface ionization

    International Nuclear Information System (INIS)

    Blashenkov, Nikolai M; Lavrent'ev, Gennadii Ya

    2007-01-01

    The ionization of polyatomic molecules on tungsten and tungsten oxide surfaces is considered for quasiequilibrium or essentially nonequilibrium conditions (in the latter case, the term nonequilibrium surface ionization is used for adsorbate ionization). Heterogeneous reactions are supposed to proceed through monomolecular decay of polyatomic molecules or fragments of multimolecular complexes. The nonequilibrium nature of these reactions is established. The dependences of the current density of disordered ions on the surface temperature, electric field strength, and ionized particle energy distribution are obtained in analytical form. Heterogeneous dissociation energies, the ionization potentials of radicals, and the magnitude of reaction departure from equilibrium are determined from experimental data, as are energy exchange times between reaction products and surfaces, the number of molecules in molecular complexes, and the number of effective degrees of freedom in molecules and complexes. In collecting the data a new technique relying on surface-ionization field mass-spectrometry was applied. (instruments and methods of investigation)

  19. Sea Surface Scanner: An advanced catamaran to study the sea surface

    Science.gov (United States)

    Wurl, O.; Mustaffa, N. I. H.; Ribas Ribas, M.

    2016-02-01

    The Sea Surface Scanner is a remote-controlled catamaran with the capability to sample the sea-surface microlayer in high resolution. The catamaran is equipped with a suite of sensors to scan the sea surface on chemical, biological and physical parameters. Parameters include UV absorption, fluorescence spectra, chlorophyll-a, photosynthetic efficiency, chromophoric dissolved organic matter (CDOM), dissolved oxygen, pH, temperature, and salinity. A further feature is a capability to collect remotely discrete water samples for detailed lab analysis. We present the first high-resolution (< 30 sec) data on the sea surface microlayer. We discuss the variability of biochemical properties of the sea surface and its implication on air-sea interaction.

  20. Overview of surface study of fusion research in universities linkage organization, (2)

    International Nuclear Information System (INIS)

    Miyahara, Akira; Kamada, Kohji; Yamashina, Toshiro.

    1981-02-01

    Overview of surface material developments for fusion devices in university linkage organization has been described. Including subjects are surface properties investigations, surface diagnostics, coating technologies tritium related surface problems and permeation studies. Because surface material investigations are wide spread subjects, necessities of problem definitions from plasma physics side were recognized. (author)

  1. Study of engineering surfaces using laser-scattering techniques

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    tour the surfaces on to which they are deposited. Silver, gold, and copper films, in partic- ular, tend to be slightly lumpy, adding additional fractions of ...... This introduces some surface modifications due to recovery of the surface, or solidification of the melt region etc. On-line measurements are feasible. However, the results.

  2. Chemical treatment of zinc surface and its corrosion inhibition studies

    Indian Academy of Sciences (India)

    WINTEC

    elements are capable of forming thin film or molecular layers on the metal surface (Abdel Aal et al 1983; Lakhan. Jha et al 1991; Maja et al 1993; Rajappa and .... solution at 298 K. The surface contained small cavities, which are distributed over the entire surface and a needle- like deposit (corrosion product) was observed.

  3. Acoustic techniques for studying soil-surface seals and crusts

    Science.gov (United States)

    The impact of raindrops on a soil surface during a rainstorm may cause soil-surface sealing and upon drying, soil crusting. Soil-surface sealing is a result of the clogging of interaggregate pores by smaller suspended particles in the water and by structural deformation of the soil fabric, which red...

  4. Observational study of surface wind along a sloping surface over mountainous terrain during winter

    Science.gov (United States)

    Lee, Young-Hee; Lee, Gyuwon; Joo, Sangwon; Ahn, Kwang-Deuk

    2018-03-01

    The 2018 Winter Olympic and Paralympic Games will be held in Pyeongchang, Korea, during February and March. We examined the near surface winds and wind gusts along the sloping surface at two outdoor venues in Pyeongchang during February and March using surface wind data. The outdoor venues are located in a complex, mountainous terrain, and hence the near-surface winds form intricate patterns due to the interplay between large-scale and locally forced winds. During February and March, the dominant wind at the ridge level is westerly; however, a significant wind direction change is observed along the sloping surface at the venues. The winds on the sloping surface are also influenced by thermal forcing, showing increased upslope flow during daytime. When neutral air flows over the hill, the windward and leeward flows show a significantly different behavior. A higher correlation of the wind speed between upper- and lower-level stations is shown in the windward region compared with the leeward region. The strong synoptic wind, small width of the ridge, and steep leeward ridge slope angle provide favorable conditions for flow separation at the leeward foot of the ridge. The gust factor increases with decreasing surface elevation and is larger during daytime than nighttime. A significantly large gust factor is also observed in the leeward region.

  5. A study on the surface roughness of a thin HSQ coating on a fine milled surface

    DEFF Research Database (Denmark)

    Mohaghegh, Kamran; Hansen, Hans Nørgaard; Pranov, Henrik

    2014-01-01

    The paper discusses a novel application of a thin layer coating on a metallic machined surface with particular attention to roughness of the coating compared to the original surface before coating. The coating is a nominally 1 μm film of Hydrogen Silsesquioxane (HSQ) which is commonly used...... in the semiconductor industry in the manufacture of integrated circuits. The work piece is a fine peripheral-milled tool steel surface which is widely used in industrial applications. Roughness improvement after the application of HSQ coating is reported....

  6. An AES Study of the Room Temperature Surface Conditioning of Technological Metal Surfaces by Electron Irradiation

    OpenAIRE

    Scheuerlein, C; Hilleret, Noël; Taborelli, M; Brown, A; Baker, M A

    2002-01-01

    The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis resu...

  7. Facial recognition and laser surface scan: a pilot study

    DEFF Research Database (Denmark)

    Lynnerup, Niels; Clausen, Maja-Lisa; Kristoffersen, Agnethe May

    2009-01-01

    that the discriminatory value was 86.7%. We also tested the surface scanner in terms of reliability in establishing point measures on skulls, and compared with physical measurements performed by calipers. The variation was on average 1 mm for five cranial measures. We suggest how surface scanning might be applied...... software (MIMICS and Photoshop) the surface scans were matched with the photographs in blind trials. The matches were graded as: a good fit; possible fit; and no fit. All the surface scans and photos were matched correctly, although one surface scan could be matched with two angled photographs, meaning...

  8. Study on superhydrophobic surfaces of octanol grafted electrospun silica nanofibers

    International Nuclear Information System (INIS)

    Meng, Long-Yue; Han, Shunyu; Jiang, Nanzhe; Meng, Wan

    2014-01-01

    In this work, superhydrophobic surfaces were successfully prepared by grafting of octanol on the surface of electrospun silica nanofibers (SNFs). The chemical compositions and microstructures of the prepared SNFs surfaces were investigated by using N 2 full isotherms, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and contact angle measurements. The results indicate that the surface of SNFs changed from being superhydrophilic to superhydrophobic by octanol surface grafting. The contact angle of the octanol-grafted SNFs was close to 150.2° because their surface was modified by –(CH 2 ) 6 –CH 3 groups. The 3D network of SNFs networks and the low surface energy of the alkyl side chains played important roles in creating the superhydrophobic surface of the SNFs. - Highlights: • Superhydrophobic surface was prepared from electrospinning SNFs and by grafting octanol on their surface. • The surface of SNFs changed from superhydrophilic to superhydrophobic. • The CA of MSNFs became 150.2° because of interactions between grafted octyl groups

  9. Study on superhydrophobic surfaces of octanol grafted electrospun silica nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Long-Yue [Key Laboratory of Natural Resources of Changbai Mountain and Functional Molecules, Yanbian University, Yanji 133002 (China); Department of Chemical Engineering, College of Engineering, Yanbian University, 977 Gongyuan Road, Yanji 133002 (China); Han, Shunyu; Jiang, Nanzhe [Department of Chemical Engineering, College of Engineering, Yanbian University, 977 Gongyuan Road, Yanji 133002 (China); Meng, Wan, E-mail: mengw@ybu.edu.cn [Department of Chemical Engineering, College of Engineering, Yanbian University, 977 Gongyuan Road, Yanji 133002 (China)

    2014-12-15

    In this work, superhydrophobic surfaces were successfully prepared by grafting of octanol on the surface of electrospun silica nanofibers (SNFs). The chemical compositions and microstructures of the prepared SNFs surfaces were investigated by using N{sub 2} full isotherms, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and contact angle measurements. The results indicate that the surface of SNFs changed from being superhydrophilic to superhydrophobic by octanol surface grafting. The contact angle of the octanol-grafted SNFs was close to 150.2° because their surface was modified by –(CH{sub 2}){sub 6}–CH{sub 3} groups. The 3D network of SNFs networks and the low surface energy of the alkyl side chains played important roles in creating the superhydrophobic surface of the SNFs. - Highlights: • Superhydrophobic surface was prepared from electrospinning SNFs and by grafting octanol on their surface. • The surface of SNFs changed from superhydrophilic to superhydrophobic. • The CA of MSNFs became 150.2° because of interactions between grafted octyl groups.

  10. An AES Study of the Room Temperature Surface Conditioning of Technological Metal Surfaces by Electron Irradiation

    CERN Document Server

    Scheuerlein, C; Taborelli, M; Brown, A; Baker, M A

    2002-01-01

    The modifications to technological copper and niobium surfaces induced by 2.5 keV electron irradiation have been investigated in the context of the conditioning process occurring in particle accelerator ultra high vacuum systems. Changes in the elemental surface composition have been found using Scanning Auger Microscopy (SAM) by monitoring the carbon, oxygen and metal Auger peak intensities as a function of electron irradiation in the dose range 10-6 to 10-2 C mm-2. The surface analysis results are compared with electron dose dependent secondary electron and electron stimulated desorption yield measurements. Initially the electron irradiation causes a surface cleaning through electron stimulated desorption, in particular of hydrogen. During this period both the electron stimulated desorption and secondary electron yield decrease as a function of electron dose. When the electron dose exceeds 10-4 C mm-2 electron stimulated desorption yields are reduced by several orders of magnitude and the electron beam indu...

  11. Surface-Tethered Iterative Carbohydrate Synthesis (STICS): A spacer study

    Science.gov (United States)

    Ganesh, N. Vijaya; Fujikawa, Kohki; Tan, Yih Horng; Nigudkar, Swati S.

    2013-01-01

    Comparative study of STICS using HPLC-assisted experimental set-up clearly demonstrated benefits of using longer spacer-anchoring systems. The use of mixed self-assembled monolayers helps to provide the required space for glycosylation reaction around the immobilized glycosyl acceptor. Both extension of the spacer length and using mixed self-assembled monolayers help to promote reaction and the beneficial effects may include moving the glycosyl acceptor further out into solution and providing additional conformational flexibility. It is possible that surface-immobilized glycosyl acceptors with a longer spacer (C8-O-C8)-lipoic acid have a higher tendency to mimic a solution-phase reaction environment than that of acceptors with shorter spacers. PMID:23822088

  12. In vitro study of proteins surface activity by tritium probe

    International Nuclear Information System (INIS)

    Chernysheva, M.G.; Badun, G.A.

    2010-01-01

    A new technique for in vitro studies of biomacromolecules interactions, their adsorption at aqueous/organic liquid interfaces and distribution in the bulk of liquid/liquid systems was developed. The method includes (1) tritium labeling of biomolecules by tritium thermal activation method and (2) scintillation phase step with organic phase, which can be concerned as a model of cellular membrane. Two globular proteins lysozyme and human serum albumin tested. We have determined the conditions of tritium labeling when labeled by-products can be easy separated by means of dialysis and size-exclusion chromatography. Scintillation phase experiments were conducted for three types of organic liquids. Thus, the influences of the nature of organic phase on proteins adsorption and its distribution in the bulk of aqueous/organic liquid system were determined. It was found that proteins possess high surface activity at aqueous/organic liquid interface. Furthermore, values of hydrophobicity of globular proteins were found by the experiment. (author)

  13. Linear predictability: A sea surface height case study

    Science.gov (United States)

    Sonnewald, Maike; Wunsch, Carl; Heimbach, Patrick

    2017-04-01

    A benchmark of linear predictive skill of global sea surface height (SSH or η) is presented, complementing more complicated studies of η predictive skill. Twenty years of the ECCOv4 state estimate (1992-2012) are used, fitting ARMA(n,m) models where the order is chosen by the Akaike and Bayesian Information Criteria (AIC and BIC). The prediction on the basis of monthly detrended data shows skill generally of the order of a few months, with isolated regions of twelve months or more. With the trend, the predictive skill increases, particularly in the south Pacific. Annually averaged data are also used, although the time-series are too short to assess the variability. Including a linear trend as part of the signal results in some enhanced predictability.

  14. Theoretical Study of Sodium-Water Surface Reaction Mechanism

    Science.gov (United States)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR).

  15. Theoretical study of sodium-water surface reaction mechanism

    International Nuclear Information System (INIS)

    Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro

    2012-01-01

    Computational study of the sodium-water reaction at the gas (water) - liquid (sodium) interface has been carried out using the ab initio (first-principle) method. A possible reaction channel has been identified for the stepwise OH bond dissociations of a single water molecule. The energetics including the binding energy of a water molecule on the sodium surface, the activation energies of the bond cleavages, and the reaction energies, have been evaluated, and the rate constants of the first and second OH bond-breakings have been compared. It was found that the estimated rate constant of the former was much larger than the latter. The results are the basis for constructing the chemical reaction model used in a multi-dimensional sodium-water reaction code, SERAPHIM, being developed by Japan Atomic Energy Agency (JAEA) toward the safety assessment of the steam generator (SG) in a sodium-cooled fast reactor (SFR). (author)

  16. The effect of surface sealant application and accelerated aging on posterior restorative surfaces: An SEM and AFM study.

    Science.gov (United States)

    Tekçe, Neslihan; Pala, Kanşad; Tuncer, Safa; Demirci, Mustafa

    2017-03-31

    The purpose of this study was to evaluate the effect of surface sealant application and 10,000 thermocycles on the surface roughness and microhardness of different resin composite systems. A micro-hybrid (G Aenial Posterior), a nano-hybrid (Clearfil Majesty Posterior), a nano-fill (Filtek Ultimate Universal Restorative, Enamel Shade), and a bulk-fill resin composite (Filtek Bulk Fill Posterior Restorative) were used for the study. Specimens were evaluated at 24 h, after application of the surface sealant Fortify Plus, and after thermocycling. Data were analyzed using two-way repeated measures of analysis of variance (ANOVA) and a posthoc Bonferroni test (pRestorative increased significantly after surface sealant application. However, neither surface sealant application nor thermocycling had a significant effect on composite microhardness values except Filtek Ultimate Universal Restorative (p>0.05).

  17. Critical assessment of Pt surface energy - An atomistic study

    Science.gov (United States)

    Kim, Jin-Soo; Seol, Donghyuk; Lee, Byeong-Joo

    2018-04-01

    Despite the fact that surface energy is a fundamental quantity in understanding surface structure of nanoparticle, the results of experimental measurements and theoretical calculations for the surface energy of pure Pt show a wide range of scattering. It is necessary to further ensure the surface energy of Pt to find the equilibrium shape and atomic configuration in Pt bimetallic nanoparticles accurately. In this article, we critically assess and optimize the Pt surface energy using a semi-empirical atomistic approach based on the second nearest-neighbor modified embedded-atom method interatomic potential. That is, the interatomic potential of pure Pt was adjusted in a way that the surface segregation tendency in a wide range of Pt binary alloys is reproduced in accordance with experimental information. The final optimized Pt surface energy (mJ/m2) is 2036 for (100) surface, 2106 for (110) surface, and 1502 for (111) surface. The potential can be utilized to find the equilibrium shape and atomic configuration of Pt bimetallic nanoparticles more accurately.

  18. Visualizing geoelectric – Hydrogeological parameters of Fadak farm at Najaf Ashraf by using 2D spa

    Directory of Open Access Journals (Sweden)

    Wadhah Mahmood Shakir Al-Khafaji

    2016-12-01

    Full Text Available A geophysical survey achieved to produce an electrical resistivity grid data of 23 Schlumberger Vertical Electrical Sounding (VES points distributed across the area of Fadak farm at Najaf Ashraf province in Iraq. The current research deals with the application of six interpolation methods used to delineate subsurface groundwater aquifer properties. One example of such features is the delineation of high and low groundwater hydraulic conductivity (K. Such methods could be useful in predicting high (K zones and predicting groundwater flowing directions within the studied aquifer. Interpolation methods were helpful in predicting some aquifer hydrogeological and structural characteristics. The results produced some important conclusions for any future groundwater investment.

  19. SELMA: a mission to study lunar environment and surface interaction

    Science.gov (United States)

    Barabash, Stas; Futaana, Yoshifumi

    2017-04-01

    SELMA (Surface, Environment, and Lunar Magnetic Anomalies) proposed for the ESA M5 mission opportunity is a mission to study how the Moon environment and surface interact. SELMA addresses four overarching science questions: (1) What is the origin of water on the Moon? (2) How do the "volatile cycles" on the Moon work? (3) How do the lunar mini-magnetospheres work? (4) What is the influence of dust on the lunar environment and surface? SELMA uses a unique combination of remote sensing via UV, IR, and energetic neutral atoms and local measurements of plasma, fields, waves, exospheric gasses, and dust. It will also conduct an impact experiment to investigate volatile content in the soil of the permanently shadowed area of the Shakleton crater. SELMA carries an impact probe to sound the Reiner-Gamma mini-magnetosphere and its interaction with the lunar regolith from the SELMA orbit down to the surface. The SELMA science objectives include: - Establish the role of the solar wind and exosphere in the formation of the water bearing materials; - Determine the water content in the regolith of the permanently shadowed region and its isotope composition; - Establish variability, sources and sinks of the lunar exosphere and its relations to impact events; - Investigate a mini-magnetosphere interaction with the solar wind; - Investigate the long-term effects of mini-magnetospheres on the local surface; - Investigate how the impact events affect the lunar dust environments; - Investigate how the plasma effects result in lofting the lunar dust; SELMA is a flexible and short (15 months) mission including the following elements SELMA orbiter, SELMA Impact Probe for Magnetic Anomalies (SIP-MA), passive Impactor, and Relaying CubeSat (RCS). SELMA is placed on quasi-frozen polar orbit 30 km x 200 km with the pericenter over the South Pole. Approximately 9 months after the launch SELMA releases SIP-MA to sound the Reiner-Gamma magnetic anomaly with very high time resolution 10 sec

  20. An implementation of differential evolution algorithm for inversion of geoelectrical data

    Science.gov (United States)

    Balkaya, Çağlayan

    2013-11-01

    Differential evolution (DE), a population-based evolutionary algorithm (EA) has been implemented to invert self-potential (SP) and vertical electrical sounding (VES) data sets. The algorithm uses three operators including mutation, crossover and selection similar to genetic algorithm (GA). Mutation is the most important operator for the success of DE. Three commonly used mutation strategies including DE/best/1 (strategy 1), DE/rand/1 (strategy 2) and DE/rand-to-best/1 (strategy 3) were applied together with a binomial type crossover. Evolution cycle of DE was realized without boundary constraints. For the test studies performed with SP data, in addition to both noise-free and noisy synthetic data sets two field data sets observed over the sulfide ore body in the Malachite mine (Colorado) and over the ore bodies in the Neem-Ka Thana cooper belt (India) were considered. VES test studies were carried out using synthetically produced resistivity data representing a three-layered earth model and a field data set example from Gökçeada (Turkey), which displays a seawater infiltration problem. Mutation strategies mentioned above were also extensively tested on both synthetic and field data sets in consideration. Of these, strategy 1 was found to be the most effective strategy for the parameter estimation by providing less computational cost together with a good accuracy. The solutions obtained by DE for the synthetic cases of SP were quite consistent with particle swarm optimization (PSO) which is a more widely used population-based optimization algorithm than DE in geophysics. Estimated parameters of SP and VES data were also compared with those obtained from Metropolis-Hastings (M-H) sampling algorithm based on simulated annealing (SA) without cooling to clarify uncertainties in the solutions. Comparison to the M-H algorithm shows that DE performs a fast approximate posterior sampling for the case of low-dimensional inverse geophysical problems.

  1. Surface study of mixtures containing cyclic ethers and isomeric chlorobutanes

    International Nuclear Information System (INIS)

    Royo, F.M.; Villares, A.; Martin, S.; Giner, B.; Lafuente, C.

    2007-01-01

    Experimental surface tensions and the corresponding surface tensions deviations for the mixtures containing 1,3-dioxolane or 1,4-dioxane and 1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane or 2-chloro-2-methylpropane, measured with a drop volume tensiometer, are reported at the temperatures of 298.15 K and 313.15 K. The excess surface concentrations of isomeric chlorobutanes are also evaluated using a monolayer model

  2. Characterization of focused seepage through an earthfill dam using geoelectrical methods.

    Science.gov (United States)

    Ikard, S J; Revil, A; Schmutz, M; Karaoulis, M; Jardani, A; Mooney, M

    2014-01-01

    Resistivity and self-potential tomography can be used to investigate anomalous seepage inside heterogeneous earthen dams. The self-potential (SP) signals provide a unique signature to groundwater flow because the source current density responsible for the SP signals is proportional to the Darcy velocity. The distribution of the SP signals is also influenced by the distribution of the resistivity; therefore, resistivity and SP need to be used in concert to elucidate groundwater flow pathways. In this study, a survey is conducted at a small earthen dam in Colorado where anomalous seepage is observed on the downstream face at the dam toe. The data reveal SP and direct current resistivity anomalies that are used to delineate three anomalous seepage zones within the dam and to estimate the source of the localized seepage discharge. The SP data are inverted in two dimensions using the resistivity distribution to determine the distribution of the Darcy velocity responsible for the observed seepage. The inverted Darcy velocity agrees with an estimation of the Darcy velocity from the hydraulic conductivity obtained from a slug test and the observed head gradient. © 2013, National Ground Water Association.

  3. The use of the multiple-gradient array for geoelectrical resistivity and induced polarization imaging

    Science.gov (United States)

    Aizebeokhai, Ahzegbobor P.; Oyeyemi, Kehinde D.

    2014-12-01

    The use of most conventional electrode configurations in electrical resistivity survey is often time consuming and labour intensive, especially when using manual data acquisition systems. Often, data acquisition teams tend to reduce data density so as to speed up field operation thereby reducing the survey cost; but this could significantly degrade the quality and resolution of the inverse models. In the present work, the potential of using the multiple-gradient array, a non-conventional electrode configuration, for practical cost effective and rapid subsurface resistivity and induced polarization mapping was evaluated. The array was used to conduct 2D resistivity and time-domain induced polarization imaging along two traverses in a study site at Ota, southwestern Nigeria. The subsurface was characterised and the main aquifer delineated using the inverse resistivity and chargeability images obtained. The performance of the multiple-gradient array was evaluated by correlating the 2D resistivity and chargeability images with those of the conventional Wenner array as well as the result of some soundings conducted along the same traverses using Schlumberger array. The multiple-gradient array has been found to have the advantage of measurement logistics and improved image resolution over the Wenner array.

  4. Geoelectrical image of the subsurface for CO2 geological storage in the Changhua site, Taiwan

    Science.gov (United States)

    Chiang, C. W.; Chiao, C. H.; Yang, M. W.; Yu, C. W.; Yang, C. H.; Chen, C. C.

    2016-12-01

    Global warming has recently become an important worldwide issue. Reduction of carbon dioxide (CO2) emission is recommended by Intergovernmental Panel on Climate Change, which geological storage is one of possible way to reduce the CO2 issue. The Taichung Power Plant is a coal-fired power plant operated by the Taiwan Power Company in Taichung, Taiwan, which is the largest coal-fired power station in the world. The power plant emits approximately 40 million tons annually which is also the world's largest CO2 emitter. Geophysical techniques are presented as the most useful tool to characterize the reservoir. The electrical resistivity tool was carried out applying audio-magnetotelluric (AMT) method, which could provide the depth resolution for evaluating the subsurface. A first survey of 20 AMT soundings was acquired to study the viability of the method to characterize the subsurface. Stations were deployed at approximately 500 m intervals and the data were recorded in the frequency range of 104-100 Hz. The dimensionality analysis proved the validity of the 1-D or 2-D assumption. The visualized model shows a layered electrical resistivity structure from shallow to depth of 3000 m. The preliminary result corresponds to seismic reflection and geological investigations that suggests a simple geological structure without complex geological processes in the area. It could be a suitable site for geological storage.

  5. Surface X-ray studies of catalytic clean technologies.

    Science.gov (United States)

    Lee, Adam F; Prabhakaran, Vinod; Wilson, Karen

    2010-06-14

    The rational design of new heterogeneous catalysts for clean chemical technologies can be accelerated by molecular level insight into surface chemical processes. In situ methodologies, able to provide time-resolved and/or pressure dependent information on the evolution of reacting adsorbed layers over catalytically relevant surfaces, are therefore of especial interest. Here we discuss recent applications of surface X-ray techniques to surface-catalysed oxidations, (de)hydrogenations, C-C coupling, dehalogenation and associated catalyst restructuring, and explore how these may help to shape future sustainable chemistry.

  6. X-Ray Studies of Phase Transitions on Surfaces

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage

    1984-01-01

    The density variation across the surface from vapor to liquid in liquid crystal materials has been measured in the isotropic, nematic and smectic A phases by specular reflection of X rays with grazing angles from θc to θB (total reflection angle and Bragg angle for smectic A layering, respectively......) using synchroton X-rays in HASYLAB, Hamburg. Crystalline surface structures may be deduced from X-ray diffraction, utilizing the evanescent beam occuring for grazing angles less than θc to obtain surface sensitivity. Results from the reconstruction of Au(110) surface are reviewed....

  7. A climatological study of rural surface ozone in central Greece

    Directory of Open Access Journals (Sweden)

    P. D. Kalabokas

    2004-01-01

    Full Text Available Recent studies show that surface ozone levels at rural sites in Greece are generally high when compared with rural ozone measurements at northern European sites. The area of SE Europe, including Greece, is not very well monitored regarding rural ozone in comparison to central and northern Europe. In order to have the best possible picture of the rural surface ozone climatology in the area, based on the available data-sets of long-term continuous monitoring stations, the 10-year measurement records (1987-1996 of the Athens peripheral station of Liossia, (12 km N of the city center and the urban background station of Geoponiki (3 km W as well as the 4-year record (1996-1999 of the rural station of Aliartos (100 km NW of Athens, are analyzed in this paper. The data for Liossia and Geoponiki stations are screened for cases of strong airflow from rural areas (N-NE winds stronger than 5 m/s. The variation characteristics of the average rural ozone afternoon levels (12:00-18:00, with the best vertical atmospheric mixing, are mainly examined since these measurements are expected to be representative of the broader area. In all three stations there is a characteristic seasonal variation of rural ozone concentrations with lowest winter afternoon values at about 50 μg/m3 in December-January and average summer afternoon values at about 120 μg/m3 in July-August, indicating that high summer values are observed all over the area. The rural summer afternoon ozone values are very well correlated between the three stations, implying spatial homogeneity all over the area but also temporal homogeneity, since during the 13-year period 1987-1999 the rural afternoon ozone levels remained almost constant around the value of 120 μg/m3.

  8. Scanning tunneling microscopy studies of glucose oxidase on gold surface

    International Nuclear Information System (INIS)

    Losic, D.; Shapter, J.G.; Gooding, J.J.

    2002-01-01

    Full text: Three immobilization methods have been used for scanning tunneling microscopy (STM) studies of glucose oxidase (GOD) on gold. They are based on a) physical adsorption from solution, b) microcontact printing and c) covalent bonding onto self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA). The STM images are used to provide information about the organization of individual GOD molecules and more densely packed monolayers of GOD on electrode surfaces, thus providing information of the role of interfacial structure on biosensor performance. The use of atomically flat gold substrates enables easy distinction of deposited enzyme features from the flat gold substrate. Microcontact printing is found to be a more reliable method than adsorption from solution for preparing individual GOD molecules on the gold surface STM images of printed samples reveal two different shapes of native GOD molecules. One is a butterfly shape with dimensions of 10 ± 1 nm x 6 ± 1 nm, assigned to the lying position of molecule while the second is an approximately spherical shape with dimensions of 6.5 ± 1 nm x 5 ± 1nm assigned to a standing position. Isolated clusters of 5 to 6 GOD molecules are also observed. With monolayer coverage, GOD molecules exhibit a tendency to organize themselves into a two dimensional array with adequate sample stability to obtain high-resolution STM images. Within these two-dimensional arrays are clearly seen repeating clusters of five to six enzyme molecules in a unit STM imaging of GOD monolayers covalently immobilized onto SAM (MPA) are considerably more difficult than when the enzyme is adsorbed directly onto the metal. Cluster structures are observed both high and low coverage despite the fact that native GOD is a negatively charged molecule. Copyright (2002) Australian Society for Electron Microscopy Inc

  9. In vitro studies on the cytotoxic potential of surface sealants.

    Science.gov (United States)

    Zingler, S; Matthei, B; Kohl, A; Saure, D; Ludwig, B; Diercke, K; Lux, C J; Erber, R

    2015-01-01

    The objective of this in vitro study was an initial screening of the cytotoxic potential of widely used smooth enamel surface sealants. A total of 20 products were allocated to four groups based on their chemical composition: (1) filled resin-based sealants, (2) unfilled resin-based sealants, (3) a resin-modified, glass ionomer-based sealant, and (4) silicone-based sealants. All materials were applied to human enamel slices both in accordance with manufacturers' instructions and in additional experiments applying 50% undercuring and 50% overcuring. An agar overlay assay was then used to test the specimens following ISO 10933. The cytotoxic potential of each material was interpreted based on a reaction index that summarized the decolorization and lysis scores obtained. The cytotoxic potential decreased as follows: unfilled resin-based sealants > filled resin-based sealants > resin-modified, glass ionomer-based sealant > silicone-based sealants. In 75% of the resin-based products, deliberate undercuring was associated with more extensive decolorization zones, leading to higher rates of cytotoxic potential in two of those products. Overcuring, by contrast, was associated with a tendency for smaller decolorization zones in 50% of the resin-based products. Surface sealants derived from resin monomers exhibited cytotoxic potential in the agar overlay assay. There is also evidence of a possible association with curing, as undercuring can increase the cytotoxic potential, whereas normal curing (as per manufacturers' instructions) or overcuring may help minimize such effects. More research into the biological implications of these materials is needed, especially with regard to their potential impact on the adjacent gingiva.

  10. Comparison study of intraoperative surface acquisition methods for surgical navigation.

    Science.gov (United States)

    Simpson, Amber L; Burgner, Jessica; Glisson, Courtenay L; Herrell, S Duke; Ma, Burton; Pheiffer, Thomas S; Webster, Robert J; Miga, Michael I

    2013-04-01

    Soft-tissue image-guided interventions often require the digitization of organ surfaces for providing correspondence from medical images to the physical patient in the operating room. In this paper, the effect of several inexpensive surface acquisition techniques on target registration error and surface registration error (SRE) for soft tissue is investigated. A systematic approach is provided to compare image-to-physical registrations using three different methods of organ spatial digitization: 1) a tracked laser-range scanner (LRS), 2) a tracked pointer, and 3) a tracked conoscopic holography sensor (called a conoprobe). For each digitization method, surfaces of phantoms and biological tissues were acquired and registered to CT image volume counterparts. A comparison among these alignments demonstrated that registration errors were statistically smaller with the conoprobe than the tracked pointer and LRS (pconoscopic holography) of digitizing surfaces for clinical usage. The tracked conoscopic holography device outperforms LRS acquisitions with respect to registration accuracy.

  11. Contribution of geophysical studies on detection of the Petrified Frost Qattamiya, Cairo

    Directory of Open Access Journals (Sweden)

    Sultan Awad Sultan Araffa

    2017-03-01

    Full Text Available Different geophysical tools such as resistivity, seismic refraction, and magnetic survey have been applied to delineate the subsurface stratigraphy and structural elements, which controlled the distribution and origin of the Petrified wood in Qattamiya, Cairo, Egypt. Land magnetic survey was carried out in the study area through two stages, the first stage includes all area by measuring 11,674 stations and the second stage was carried out in the detailed area that was located at the southeastern part of the all area including 9441 stations. All measurements have been corrected for diurnal variation and reduced to the north magnetic pole. The results of magnetic interpretation indicated that the area dissected by different structural elements trend toward NE–SW, NW–SE, N–S and E–W directions. Twenty-eight samples have been collected from the detailed area to analyze for magnetic susceptibility values. Four electrical resistivity tomography (ERT profiles were measured by using dipole–dipole configuration to estimate the vertical and lateral variation of the subsurface sequence. Results of quantitative interpretation of the ERT data indicate that the subsurface sequence consists of different geoelectric units; the first unit is characterized by high resistivity values upto 1000 ohm m corresponding to sand, gravel and Petrified wood at the surface and extends to a depth of a few meters. The second geoelectric unit is corresponding to sandy clay which exhibits moderate resistivity (few hundred ohm m values with thickness ranging from 6 to10 m. The third geoelectric unit is characterized by very low resistivity corresponding to clay of depth ranging from 10 to 30 m overlaying the fourth unit which reached to a depth ranging from 30 to 56 m and characterized by very high resistivity (8000 ohm m corresponding to limestone. Three shallow seismic refraction spreads of geophone spacing 7.5 m were measured to investigate the subsurface

  12. Sputter deposited bioceramic coatings: surface characterisation and initial protein adsorption studies using surface-MALDI-MS

    DEFF Research Database (Denmark)

    Boyd, A. R.; Burke, G. A.; Duffy, H.

    2011-01-01

    Protein adsorption onto calcium phosphate (Ca–P) bioceramics utilised in hard tissue implant applications has been highlighted as one of the key events that influences the subsequent biological response, in vivo. This work reports on the use of surface-matrix assisted laser desorption ionisation ...

  13. HYDROGEOLOGICAL SIGNIFICANCE OF GEOELECTRIC ...

    African Journals Online (AJOL)

    ... basement complex rock and the sedimentary rock of Abeokuta formation. Thus for Ijebu-ode and its environs, a thorough geophysical survey is required before citing a borehole to guide against failure or dry hole. KEY WORDS: Aquifer, Coarse sand, Resistivity, Compacted Clay, Borehole. Global Jnl Geological Sciences.

  14. Surface Projection of Interosseous Foramen of the Leg: Cadaver Study

    Directory of Open Access Journals (Sweden)

    Eric Arguello

    2016-01-01

    Full Text Available Purpose. This study was conducted to identify the surface projection of the interosseous foramen and associated structures of the proximal leg using the average clinician’s thumb width as a quick measurement to assist in differential diagnosis and treatment. Methods. Twelve cadavers (5 males and 7 females, age range = 51–91 years, and mean age = 76.9 were dissected for analysis. Location and size of interosseous foramen, location of anterior tibial artery, location of deep fibular nerve, and corresponding arterial branches were measured and converted into thumb widths. Results. Mean thumb width measured among the cadavers was 17.94±3.9 mm. The interosseous foramen measured was approximately 1 thumb width vertically (18.47±3.0 mm and 1/2 thumb width horizontally (7.32±2.1 mm and was located approximately 1 thumb width distally to the tibial tuberosity (20.81±6.8 mm and 2 thumb widths (37.47±4.7 mm lateral to the tibial ridge. The anterior tibial artery and deep fibular nerve converged approximately 4 thumb widths (74.31±14.8 mm inferior to the tibial tuberosity and 2 thumb widths (33.46±4.9 mm lateral to the tibial ridge. Conclusion. Clinicians may identify anatomical structures of the proximal leg with palpation using the thumb width for measurement.

  15. Study the Relationship between Pavement Surface Distress and Roughness Data

    Directory of Open Access Journals (Sweden)

    Mubaraki Muhammad

    2016-01-01

    Full Text Available In this paper, pavement sections from the highway connected Jeddah to Jazan were selected and analyzed to investigate the relationship between International Roughness Index (IRI and pavement damage including; cracking, rutting, and raveling. The Ministry of Transport (MOT of Saudi Arabia has been collecting pavement condition data using the Road Surface Tester (RST vehicle. The MOT measures Roughness, Rutting (RUT, Cracking (CRA, raveling (RAV. Roughness measurements are calculated in terms of the International Roughness Index (IRI. The IRI is calculated over equally spaced intervals along the road profile. Roughness measurements are performed at speed between at 80 kilometers per hour. Thus RST vehicle has been used to evaluate highways across the country. The paper shows three relationships including; cracking (CRA verses roughness (IRI, rutting (RUT verses IRI, and raveling (RAV verses IRI. Also, the paper developed two models namely; model relates IRI to the three distress under study, and model relates IRI to ride quality. The results of the analysis claim at 95% confidence that a significant relationship exist between IRI and cracking, and raveling. It’s also shown that rutting did not show significant relationship to IRI values. That’s leads to conclude that the distresses types: cracking and raveling may possibly be described as ride quality distresses at different level of significant. Rutting distress described as non-ride quality type’s distresses.

  16. Friction surfacing for enhanced surface protection of marine engineering components: erosion-corrosion study

    Science.gov (United States)

    Rajakumar, S.; Balasubramanian, V.; Balakrishnan, M.

    2016-08-01

    Good mechanical properties combined with outstanding corrosion-resistance properties of cast nickel-aluminum bronze (NAB) alloy lead to be a specific material for many marine applications, including ship propellers. However, the erosion-corrosion resistance of cast-NAB alloy is not as good as wrought NAB alloy. Hence, in this investigation, an attempt has been made to improve the erosion-corrosion resistance of cast NAB alloy by depositing wrought (extruded) NAB alloy applying the friction surfacing (FS) technique. Erosion-corrosion tests were carried out in slurries composed of sand particles of 3.5% NaCl solution. Silica sand having a nominal size range of 250-355 μm is used as an erodent. Specimens were tested at 30° and 90° impingement angles. It is observed that the erosion and erosion-corrosion resistance of friction surfaced NAB alloy exhibited an improvement as compared to cast NAB alloy. Scanning electron microscope (SEM) analysis showed that the erosion tracks developed on the cast NAB alloy were wider and deeper than those formed on the friction surfaced extruded NAB alloy.

  17. RF surface resistance study of non-evaporable getter coatings

    Energy Technology Data Exchange (ETDEWEB)

    Malyshev, Oleg B., E-mail: oleg.malyshev@stfc.ac.uk [ASTeC, STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Gurran, Lewis [ASTeC, STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Engineering, Lancaster University, Cockcroft Institute, Lancaster (United Kingdom); Goudket, Philippe; Marinov, Kiril [ASTeC, STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Wilde, Stuart [ASTeC, STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Loughborough University, Loughborough (United Kingdom); Valizadeh, Reza [ASTeC, STFC Daresbury Laboratory, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Cockcroft Institute, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Burt, Graeme [Cockcroft Institute, Daresbury, Warrington, WA4 4AD Cheshire (United Kingdom); Engineering, Lancaster University, Cockcroft Institute, Lancaster (United Kingdom)

    2017-02-01

    In many particle accelerators the beam parameters could be affected by the beam pipe wakefield impedance. It is vital to understand how the wakefield impedance might vary due to various coatings on the surface of the vacuum chamber, and this can be derived from surface resistance measurements. The bulk conductivity of two types of NEG films (dense and columnar) is determined. This is achieved by measuring the surface resistance of NEG-coated samples using an RF test cavity and fitting the experimental data to a standard theoretical model. The conductivity values obtained are then used to compare resistive wall wakefield effects in beam pipes coated with either of the two types of film. - Highlights: • The surface resistance two types of non-evaporable getter film was measured. • The bulk conductivity of two types of NEG films (dense and columnar) was determined. • The obtained conductivity values were applied for various RF frequencies.

  18. TANK FARM INTERIM SURFACE BARRIER MATERIALS AND RUNOFF ALTERNATIVES STUDY

    Energy Technology Data Exchange (ETDEWEB)

    HOLM MJ

    2009-06-25

    This report identifies candidate materials and concepts for interim surface barriers in the single-shell tank farms. An analysis of these materials for application to the TY tank farm is also provided.

  19. Tank Farm Interim Surface Barrier Materials And Runoff Alternatives Study

    International Nuclear Information System (INIS)

    Holm, M.J.

    2009-01-01

    This report identifies candidate materials and concepts for interim surface barriers in the single-shell tank farms. An analysis of these materials for application to the TY tank farm is also provided.

  20. Mining-induced surface damage and the study of countermeasures

    International Nuclear Information System (INIS)

    Cui Jixian

    1994-01-01

    Coal constitutes China's major energy resource. The majority of the coal is produced from underground mining operations. Surface subsidence may amount to 80% of the thickness of the seam mined, while the subsided volume is around 60% of the mined volume underground. An area of 20 hectares of land will be affected with each 1 million tons of coal mined, thereby causing severe surface damage. Following a description of the characteristics of surface damages due to underground mining disturbance, this paper elaborates on the damage prediction method, standards applied for evaluating the damages experienced by surface buildings, land reclamation methods in subsided area, measures for reinforcing and protecting buildings in mining-affected areas, and performance of antideformation buildings

  1. Studies on polyurethane adhesives and surface modification of hydrophobic substrates

    Science.gov (United States)

    Krishnamoorthy, Jayaraman

    studies involved making functionalized, thickness-controlled, wettability-controlled multilayers on hydrophobic substrates and the adsorption of carboxylic acid-terminated poly(styrene-b-isoprene) on alumina/silica substrates. Poly(vinyl alcohol) has been shown to adsorb onto hydrophobic surfaces irreversibly due to hydrophobic interactions. This thin semicrystalline coating is chemically modified using acid chlorides, butyl isocyanate and butanal to form thicker and hydrophobic coatings. The products of the modification reactions allow adsorption of a subsequent layer of poly(vinyl alcohol) that could subsequently be hydrophobized. This 2-step (adsorption/chemical modification) allows layer-by-layer deposition to prepare coatings with thickness, chemical structure and wettability control on any hydrophobic surface. Research on adsorption characteristics of carboxylic acid-terminated poly(styrene-b-isoprene) involved syntheses of block copolymers with the functional group present at specific ends. Comparative adsorption studies for carboxylic acid-terminated and hydrogen-terminated block copolymers was carried out on alumina and silica substrates.

  2. Fundamental Studies of Diamond Growth and Surface Reactions

    Science.gov (United States)

    1994-07-01

    deposition ( PACVD ) have been observed as a function of growth temperature, substrate identity and surface condition. Our highest microwave PACVD growth...The rate of growth of PACVD diamond films is intimately tied to the availability of low energy growth sites. Such low energy sites will be associated...oriented diamond film. m Fig. I Scanning electron micrograph of a random polycrystalline diamond film surface grown at 1000°C by micro- wave PACVD

  3. Central motor control failure in fibromyalgia: a surface electromyography study.

    Science.gov (United States)

    Casale, Roberto; Sarzi-Puttini, Piercarlo; Atzeni, Fabiola; Gazzoni, Marco; Buskila, Dan; Rainoldi, Alberto

    2009-07-01

    Fibromyalgia (FM) is characterised by diffuse musculoskeletal pain and stiffness at multiple sites, tender points in characteristic locations, and the frequent presence of symptoms such as fatigue. The aim of this study was to assess whether the myoelectrical manifestations of fatigue in patients affected by FM are central or peripheral in origin. Eight female patients aged 55.6 +/- 13.6 years (FM group) and eight healthy female volunteers aged 50.3 +/- 9.3 years (MCG) were studied by means of non-invasive surface electromyography (s-EMG) involving a linear array of 16 electrodes placed on the skin overlying the biceps brachii muscle, with muscle fatigue being evoked by means of voluntary and involuntary (electrically elicited) contractions. Maximal voluntary contractions (MVCs), motor unit action potential conduction velocity distributions (mean +/- SD and skewness), and the mean power frequency of the spectrum (MNF) were estimated in order to assess whether there were any significant differences between the two groups and contraction types. The motor pattern of recruitment during voluntary contractions was altered in the FM patients, who also showed fewer myoelectrical manifestations of fatigue (normalised conduction velocity rate of changes: -0.074 +/- 0.052%/s in FM vs -0.196 +/- 0.133%/s in MCG; normalised MNF rate of changes: -0.29 +/- 0.16%/s in FM vs -0.66 +/- 0.34%/s in MCG). Mean conduction velocity distribution and skewnesses values were higher (p fatigue in FM is the electrophysiological expression of muscle remodelling in terms of the prevalence of slow conducting fatigue-resistant type I fibres. As the only between-group differences concerned voluntary contractions, they are probably more related to central motor control failure than muscle membrane alterations, which suggests pathological muscle fibre remodelling related to altered suprasegmental control.

  4. Central motor control failure in fibromyalgia: a surface electromyography study

    Science.gov (United States)

    Casale, Roberto; Sarzi-Puttini, Piercarlo; Atzeni, Fabiola; Gazzoni, Marco; Buskila, Dan; Rainoldi, Alberto

    2009-01-01

    Background Fibromyalgia (FM) is characterised by diffuse musculoskeletal pain and stiffness at multiple sites, tender points in characteristic locations, and the frequent presence of symptoms such as fatigue. The aim of this study was to assess whether the myoelectrical manifestations of fatigue in patients affected by FM are central or peripheral in origin. Methods Eight female patients aged 55.6 ± 13.6 years (FM group) and eight healthy female volunteers aged 50.3 ± 9.3 years (MCG) were studied by means of non-invasive surface electromyography (s-EMG) involving a linear array of 16 electrodes placed on the skin overlying the biceps brachii muscle, with muscle fatigue being evoked by means of voluntary and involuntary (electrically elicited) contractions. Maximal voluntary contractions (MVCs), motor unit action potential conduction velocity distributions (mean ± SD and skewness), and the mean power frequency of the spectrum (MNF) were estimated in order to assess whether there were any significant differences between the two groups and contraction types. Results The motor pattern of recruitment during voluntary contractions was altered in the FM patients, who also showed fewer myoelectrical manifestations of fatigue (normalised conduction velocity rate of changes: -0.074 ± 0.052%/s in FM vs -0.196 ± 0.133%/s in MCG; normalised MNF rate of changes: -0.29 ± 0.16%/s in FM vs -0.66 ± 0.34%/s in MCG). Mean conduction velocity distribution and skewnesses values were higher (p fatigue in FM is the electrophysiological expression of muscle remodelling in terms of the prevalence of slow conducting fatigue-resistant type I fibres. As the only between-group differences concerned voluntary contractions, they are probably more related to central motor control failure than muscle membrane alterations, which suggests pathological muscle fibre remodelling related to altered suprasegmental control. PMID:19570214

  5. Central motor control failure in fibromyalgia: a surface electromyography study

    Directory of Open Access Journals (Sweden)

    Buskila Dan

    2009-07-01

    Full Text Available Abstract Background Fibromyalgia (FM is characterised by diffuse musculoskeletal pain and stiffness at multiple sites, tender points in characteristic locations, and the frequent presence of symptoms such as fatigue. The aim of this study was to assess whether the myoelectrical manifestations of fatigue in patients affected by FM are central or peripheral in origin. Methods Eight female patients aged 55.6 ± 13.6 years (FM group and eight healthy female volunteers aged 50.3 ± 9.3 years (MCG were studied by means of non-invasive surface electromyography (s-EMG involving a linear array of 16 electrodes placed on the skin overlying the biceps brachii muscle, with muscle fatigue being evoked by means of voluntary and involuntary (electrically elicited contractions. Maximal voluntary contractions (MVCs, motor unit action potential conduction velocity distributions (mean ± SD and skewness, and the mean power frequency of the spectrum (MNF were estimated in order to assess whether there were any significant differences between the two groups and contraction types. Results The motor pattern of recruitment during voluntary contractions was altered in the FM patients, who also showed fewer myoelectrical manifestations of fatigue (normalised conduction velocity rate of changes: -0.074 ± 0.052%/s in FM vs -0.196 ± 0.133%/s in MCG; normalised MNF rate of changes: -0.29 ± 0.16%/s in FM vs -0.66 ± 0.34%/s in MCG. Mean conduction velocity distribution and skewnesses values were higher (p Conclusion The apparent paradox of fewer myoelectrical manifestations of fatigue in FM is the electrophysiological expression of muscle remodelling in terms of the prevalence of slow conducting fatigue-resistant type I fibres. As the only between-group differences concerned voluntary contractions, they are probably more related to central motor control failure than muscle membrane alterations, which suggests pathological muscle fibre remodelling related to altered

  6. Studies of surface adsorption on LiAlO2

    International Nuclear Information System (INIS)

    Fischer, A.K.; Johnson, C.E.; McDaniel, J.A.

    1986-01-01

    Computational and experimental approaches are being taken to understanding surface adsorption/desorption effects on tritium inventory and release. The computational survey integrates a thermodynamic treatment of surface adsorption and bulk phase effects such as solubility and gas phase composition. The system T 2 O:T 2 :LiAlO 2 was examined. The calculations indicate that surface adsorption can be expected to contribute most to tritium inventory under the conditions of lower temperatures and higher oxygen activities. Higher temperature and lower oxygen activity favor lower surface inventory. In the experimental work, a high temperature gas chromatograph was constructed in order to measure the H 2 O:H 2 surface adsorption isotherms and the solubility of hydroxide in LiAlO 2 . Preliminary data indicate that at 478 K approximately 15% of the surface is coverred for a partial pressure of H 2 O of approximately 52 Pa. Calculated values can be obtained that are in reasonable agreement with this. (orig.)

  7. Structure of the Si(1 1 3) surface studied by surface X-ray diffraction

    International Nuclear Information System (INIS)

    Mizuno, Yoshihito; Akimoto, Koichi; Aoyama, Tomohiro; Suzuki, Hidetoshi; Nakahara, Hitoshi; Ichimiya, Ayahiko; Sumitani, Kazushi; Takahashi, Toshio; Zhang Xiaowei; Sugiyama, Hiroshi; Kawata, Hiroshi

    2004-01-01

    We carried out a grazing incidence X-ray diffraction analysis of the Si(1 1 3) 3 x 1 surface using synchrotron radiation. We compared the experimental structure factors obtained from the integrated intensities of the fractional-order reflections with the calculated structure factors of the dimerized structure model of Ranke. By minimizing the R-factor, we determined the position and the size of the pentagon in the 3 x 1 dimerized structure model of Ranke. In addition, we found that a model with randomly distributed interstitial atoms at the center of the pentagon gives a smaller R-factor value

  8. Experimental study on source efficiencies for estimating surface contamination level

    International Nuclear Information System (INIS)

    Ichiji, Takeshi; Ogino, Haruyuki

    2008-01-01

    Source efficiency was measured experimentally for various materials, such as metals, nonmetals, flooring materials, sheet materials and other materials, contaminated by alpha and beta emitter radioactive nuclides. Five nuclides, 147 Pm, 60 Co, 137 Cs, 204 Tl and 90 Sr- 90 Y, were used as the beta emitters, and one nuclide 241 Am was used as the alpha emitter. The test samples were prepared by placing drops of the radioactive standardized solutions uniformly on the various materials using an automatic quantitative dispenser system from Musashi Engineering, Inc. After placing drops of the radioactive standardized solutions, the test materials were allowed to dry for more than 12 hours in a draft chamber with a hood. The radioactivity of each test material was about 30 Bq. Beta rays or alpha rays from the test materials were measured with a 2-pi gas flow proportional counter from Aloka Co., Ltd. The source efficiencies of the metals, nonmetals and sheet materials were higher than 0.5 in the case of contamination by the 137 Cs, 204 Tl and 90 Sr- 90 Y radioactive standardized solutions, higher than 0.4 in the case of contamination by the 60 Co radioactive standardized solution, and higher than 0.25 in the case of contamination by the alpha emitter the 241 Am radioactive standardized solution. These values were higher than those given in Japanese Industrial Standards (JIS) documents. In contrast, the source efficiencies of some permeable materials were lower than those given in JIS documents, because source efficiency varies depending on whether the materials or radioactive sources are wet or dry. This study provides basic data on source efficiency, which is useful for estimating the surface contamination level of materials. (author)

  9. Argonne-Utah studies of 224Ra endosteal surface dosimetry

    International Nuclear Information System (INIS)

    Schlenker, R.A.; Smith, J.M.

    1985-01-01

    The activities of 212 Pb relative to 224 Ra and of 222 Rn relative to 226 Ra were measured in bone surface deposits 24 h after injection of radium into beagles. The fractional retention of 220 Rn atoms was measured in vitro with hydrated and dehydrated bone samples to determine the effect of water content on the escape of radon from bone surfaces. The experimental data suggest that substantial 224 Ra daughter-product disequilibrium exists in bone surface deposits. Estimates for the lower and upper limits on the fractional retention of 220 Rn in vivo are 0.05 and 0.25, respectively. The average bone surface activity of 212 Pb relative to 224 Ra ranged from 0.34 to 0.71 for four dogs, with the majority of the values toward the lower end of the range. Only a small portion of the deposited 212 Pb came from lead in the injection solution despite near equilibrium between 224 Ra and its daughters at the time of injection. The retention data indicate that the endosteal tissue dose rate in the dogs at one day was actually one-third to about one-half that which would be calculated assuming equilibrium of 224 Ra daughter products in bone surface deposits. 11 references, 2 figures, 7 tables

  10. Argonne-Utah studies of 224Ra endosteal surface dosimetry

    International Nuclear Information System (INIS)

    Schlenker, R.A.; Smith, J.M.

    1984-01-01

    The activities of 212 Pb relative to 224 Ra and of 222 Rn relative to 226 Ra were measured in bone surface deposits 24 h after radium injection into beagles. The fractional retention of 220 Rn atoms was measured in vitro with hydrated and dehydrated bone samples to determine the effect of water content on the escape of radon from bone surfaces. The experimental data suggest that substantial 224 Ra daughter product disequilibrium exists in bone surface deposits. Estimates for the lower and upper limits on the fractional retention of 220 Rn in vivo are 0.05 and 0.25, respectively. The average bone surface activity of 212 Pb relative to 224 Ra ranged from 0.34 to 0.71 for four dogs, with the majority of the values toward the low end of the range. Only a small portion of the deposited 212 Pb came from lead in the injection solution despite near equilibrium between 224 Ra and its daughters at the time of injection. The retention data indicate that the endosteal tissue dose rate in the dogs at one day was actually one-third to about one-half that which would be calculated assuming equilibrium of 224 Ra daughter products in bone surface deposits. 11 references, 2 figures, 7 tables

  11. Studies of dental root surface caries. 2: The role of cementum in root surface caries.

    Science.gov (United States)

    McIntyre, J M; Featherstone, J D; Fu, J

    2000-06-01

    Artificial caries lesions were produced in roots of teeth using an acetate buffer system, when the layer of cementum was either normal in thickness, excessively thickened by hypercementosis, or had been removed completely. The rates of lesion progression were measured in each case using polarized light microscopy to measure lesion depth. Analysis of calcium (Ca) and phosphorus (P) loss during the demineralizing process was carried out. The removal of cementum was found to significantly increase the initial rate of penetration of the lesion into the root, although this rate progressively reduced to a level consistent with that found in normal roots after seven days of demineralization. The overall depth remained consistently greater than that observed in normal roots, or when lesions were produced entirely within hyperplastic cementum. Chemical analysis also showed removal of cementum resulted in an initial doubling of the Ca and P lost from the root surface. Prior direct exposure of segments of normal roots to the oral environment was found not to significantly alter the rate of artificial lesion progression, in comparison with that in the originally protected segment of the root surface. It was concluded that an intact cementum layer has the intrinsic ability to protect the underlying dentine of exposed tooth roots against acidic demineralization and that prior exposure to the oral environment does not significantly alter this ability.

  12. Chlorination of zirconium (0001) surface: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Kim, E. [Univ. of Nevada, Las Vegas, NV (United States). Department of Physics and Astronomy; Weck, Philippe F [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Poineau, F. [Univ. of Nevada, Las Vegas, NV (United States). Department of Chemistry; Paviet, P. [Dept. of Energy (DOE), Washington DC (United States)

    2016-12-13

    The mechanisms and energetics of Zr(0001) surface chlorination by dissociative adsorption of gaseous Cl2, and associated speciation and surface degradation processes, have been investigated within the framework of density functional theory. Chlorination of Zr(0001) is predicted to be exothermic by 3 eV/Cl for dissociative adsorption of a single Cl2 molecule, followed by exothermic chlorination to 1ML and 2 ML under Cl-rich conditions, with respective energy gains of 1.93 and 2.79 eV/Cl. Calculations also show that exfoliation of the top Cl-Zr-Cl sandwich layers is exothermic and most energetically favorable, and can thus be considered as a leading mechanism for Zr(0001) surface dissolution. Finally, consistent with experimental findings, formation of ZrCl4 molecular products is also found to be dominant during Zr(0001) chlorination.

  13. Chlorination of zirconium (0001) surface: A first-principles study.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eunja [Univ. of Nevada, Las Vegas, NV (United States). Dept. of Physics and Astronomy; Weck, Philippe F [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Borjas, Rosendo [Univ. of Nevada, Las Vegas, NV (United States). Dept. of Chemistry; Poineau, Frederic [Univ. of Nevada, Las Vegas, NV (United States). Dept. of Chemistry

    2017-01-01

    Here, the mechanisms and energetics of Zr(0001) surface chlorination by dissociative adsorption of gaseous Cl2, and associated speciation and surface degradation processes, have been investigated within the framework of density functional theory. Chlorination of Zr(0001) is predicted to be exothermic by ~3 eV/Cl for dissociative adsorption of a single Cl2 molecule, followed by exothermic chlorination to 1ML and 2 ML under Cl-rich conditions, with respective energy gains of 1.93 and 2.79 eV/Cl. Calculations also show that exfoliation of the top Cl-Zr-Cl sandwich layers is exothermic and most energetically favorable, and can thus be considered as a leading mechanism for Zr(0001) surface dissolution. Consistent with experimental findings, formation of ZrCl4 molecular products is also found to be dominant during Zr(0001) chlorination.

  14. A scanning electron microscope study of olivine crystal surfaces

    Science.gov (United States)

    Olsen, E. J.; Grossman, L.

    1974-01-01

    SEM photographs were taken of euhedral olivine grains from the Murchison C2 chondrite and several terrestrial and lunar occurrences. In general, the crystal faces of the meteorite grains are rough and uneven, with irregular growth patterns. They are very similar to crystal faces on terrestrial olivine grains that formed by sublimation from a vapor phase. They are very different from the relatively smooth and featureless surfaces of magmatic olivine crystals that precipitated from igneous melts. Qualitatively, the surface morphology of the crystal supports the contention that many euhedral crystals of olivine in C2 meteorites condensed from a gas phase.

  15. Surface modification for interaction study with bacteria and preosteoblast cells

    Science.gov (United States)

    Song, Qing

    Surface modification plays a pivotal role in bioengineering. Polymer coatings can provide biocompatibility and biofunctionalities to biomaterials through surface modification. In this dissertation, initiated chemical vapor deposition (iCVD) was utilized to coat two-dimensional (2D) and three-dimensional (3D) substrates with differently charged polyelectrolytes in order to generate antimicrobial and osteocompatible biomaterials. ICVD is a modified CVD technique that enables surface modification in an all-dry condition without substrate damage and solvent contamination. The free-radical polymerization allows the vinyl polymers to conformally coat on various micro- and nano-structured substrates and maintains the delicate structure of the functional groups. The vapor deposition of polycations provided antimicrobial activity to planar and porous substrates through destroying the negatively charged bacterial membrane and brought about high contact-killing efficiency (99.99%) against Gram-positive Bacillus subtilis and Gram-negative Escherichia coli. Additionally, the polyampholytes synthesized by iCVD exhibited excellent antifouling performance against the adhesion of Gram-positive Listeria innocua and Gram-negative E. coli in phosphate buffered saline (PBS). Their antifouling activities were attributed to the electrostatic interaction and hydration layers that served as physical and energetic barriers to prevent bacterial adhesion. The contact-killing and antifouling polymers synthesized by iCVD can be applied to surface modification of food processing equipment and medical devices with the aim of reducing foodborne diseases and medical infections. Moreover, the charged polyelectrolyte modified 2D polystyrene surfaces displayed good osteocompatibility and enhanced osteogenesis of preosteoblast cells than the un-modified polystyrene surface. In order to promote osteoinduction of hydroxyapatite (HA) scaffolds, bioinspired polymer-controlled mineralization was conducted

  16. Surface Characterization for Land-Atmosphere Studies of CLASIC

    Science.gov (United States)

    Jackson, T. J.; Kustas, W.; Torn, M. S.; Meyers, T.; Prueger, J.; Fischer, M. L.; Avissar, R.; Yueh, S.; Anderson, M.; Miller, M.

    2006-12-01

    The Cloud and Land Surface Interaction Campaign will focus on interactions between the land surface, convective boundary layer, and cumulus clouds. It will take place in the Southern Great Plains (SGP) area of the U.S, specifically within the US DOE ARM Climate Research Facility. The intensive observing period will be June of 2007, which typically covers the winter wheat harvest in the region. This region has been the focus of several related experiments that include SGP97, SGP99, and SMEX03. For the land surface, some of the specific science questions include 1) how do spatial variations in land cover along this trajectory modulate the cloud structure and the low-level water vapor budget, 2) what are the relationships between land surface characteristics (i.e., soil texture, vegetation type and fractional cover) and states (particularly soil moisture and surface temperature) and the resulting impact of the surface energy balance on boundary layer and cloud structure and dynamics and aerosol loading; and 3) what is the interplay between cumulus cloud development and surface energy balance partitioning between latent and sensible heat, and implications for the carbon flux? Most of these objectives will require flux and state measurements throughout the dominant land covers and distributed over the geographic domain. These observations would allow determining the level of up- scaling/aggregation required in order to understand the impact of landscape changes affecting energy balance/flux partitioning and impact on cloud/atmospheric dynamics. Specific contributions that are planned to be added to CLASIC include continuous tower-based monitoring of surface fluxes for key land cover types prior to, during, and post-IOP, replicate towers to quantify flux variance within each land cover, boundary layer properties and fluxes from a helicopter-based system, airplane- and satellite-based flux products throughout the region, aircraft- and tower-based concentration data for

  17. CSEM IMAGING OF THE NEAR SURFACE DYNAMICS AND ITS IMPACT FOR FOUNDATION STABILITY AT QUARTER 27, 15th OF MAY CITY, HELWAN, EGYPT

    Directory of Open Access Journals (Sweden)

    El Hemali Ibrahim A.

    2010-06-01

    Full Text Available In the present work, we involve the Control Source Electromagnetic (CSEM Technique to image the dynamic migration center of the near surface fractures, fissures, and cracks in a new dwelling area at 15th of May city close to Cairo. This area forms the center of the zonal weakness of the subsoil, which in turn, interact with the weight center of the construction leading to catastrophiccollapses.The control source electromagnetic technique has been developed recently to monitor the migration of the weakness center represented as the accumulative fissures and cracks in thenear surface. Three composite profiles of wide and planshet mesh data have been collected in 2008. This survey has been followed by performing two profiles in 2010; one of these profiles has been repeated to observe the situation changes, and the second profile has been measured between the other two profiles of2008. The last profile had been performed to study the mutual relation between the measurements of the two cycles. The objectives of the whole process are to validate the capability of the technique to pick the minor changes of the weakness center, consequently, study its relation to the weight center of the adjacent construction to produce a recommended procedure to minimizethe destruction resources at the site of investigation.The measured data has been interpreted and represented in graphs showing the distribution of the heterogeneity of the geoelectric parameters in the subsoil, furthermore, in a series of geoelectric cross section representing the applied frequencies used during the survey. The study concludes that (1 the center of the cracked zone is moving upward closer to the surface of the ground and heaver, (2 the water content is moving downward producing soil dryness at the shallow depths, and (3 the site became more stable in 2010 than 2008, however, the destruction resources remain warning with collapse events. Furthermore, the situation reflects

  18. nigeria

    African Journals Online (AJOL)

    Rose

    Geoelectric study of the groundwater potential of Ilara-Mokin in Ondo State Southwestern Nigeria was carried out using electrical resistivity (Vertical Electrical Sounding) method with the view to providing adequate information on the different sub-surface geoelectric layers, structural configuration of the concealed basement ...

  19. Surface and impurity studies in ORMAK and ISX

    Energy Technology Data Exchange (ETDEWEB)

    Colchin, R.J.; Clausing, R.E.; Emerson, L.C.; Heatherly, L.; Isler, R.C.

    1977-02-01

    The ORMAK vacuum liner is constructed of stainless steel overcoated with a thin platinum diffusion barrier and a final layer of gold. Gold was selected as the vacuum surface because it is chemically inert to the adsorption of common gases. However, gold surfaces do adsorb hydrocarbons, and carbon (along with oxygen) was the principal plasma contaminant during the first two years of ORMAK operation. Upon switching discharge-cleaning gases from hydrogen to oxygen, carbon levels dropped until carbon is no longer a significant contaminant; residual hydrocarbons can now be controlled either by hydrogen or by oxygen discharge cleaning. The principal measured plasma contaminant in ORMAK is now oxygen. Samples taken from the ORMAK liner and analyzed by Auger electron spectroscopy reveal the presence of iron and oxygen. There is evidence from a SXAPS (Soft X-ray Appearance Potential Spectroscopy) probe of iron and chromium diffusion from the stainless steel through the gold surface in spite of the platinum diffusion barrier. The iron and chromium provide surface oxidation sites, and SXAPS analysis shows that these metals exist as oxides.

  20. Impedance spectroscopy studies of surface engineered TiO2 ...

    Indian Academy of Sciences (India)

    Administrator

    earlier work where various functionalized aromatic orga- nophosphates were used, here different organophosphate ligand molecules containing linear, aromatic and extended aromatic chemical groups were employed. Figure 1 shows the chemical structures of organophosphate ligands that were examined as filler surface ...

  1. Surface Passivation Studies on n+pp+ Bifacial Solar Cell

    Directory of Open Access Journals (Sweden)

    Suhaila Sepeai

    2012-01-01

    Full Text Available Bifacial solar cell is a specially designed solar cell for the production of electricity from both sides of the solar cell. It is an active field of research to make photovoltaics (PV more competitive by increasing its efficiency and lowering its costs. We developed an n+pp+ structure for the bifacial solar cell. The fabrication used phosphorus-oxy-trichloride (POCl3 diffusion to form the emitter and Al diffusion using conventional screen printing to produce the back surface field (BSF. The n+pp+ bifacial solar cell was a sandwiched structure of antireflective coatings on both sides, Argentum (Ag as a front contact and Argentum/Aluminum (Ag/Al as a back contact. This paper reports the solar cell performance with different surface passivation or antireflecting coatings (ARC. Silicon nitride (SiN deposited by Plasma-Enhanced Chemical Vapor Deposition (PECVD, thermally grown silicon dioxide (SiO2, PECVD-SiO2, and SiO2/SiN stack were used as ARC. The efficiency obtained for the best bifacial solar cell having SiN as the ARC is 8.32% for front surface illumination and 3.21% for back surface illumination.

  2. Spectroscopic Study of the Surface Oxidation of Mechanically Activated Sulphides

    Czech Academy of Sciences Publication Activity Database

    Godočíková, E.; Baláž, P.; Bastl, Zdeněk; Brabec, Libor

    2002-01-01

    Roč. 200, č. 1 (2002), s. 36-47 ISSN 0169-4332 Institutional research plan: CEZ:AV0Z4040901 Keywords : mechanical activation * surface oxidation * sulphide minerals Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.295, year: 2002

  3. Experimental study of gas entrainment from surface swirl

    Energy Technology Data Exchange (ETDEWEB)

    Moudjed, B., E-mail: brahim.moudjed@cea.fr; Excoffon, J.; Riva, R.; Rossi, L., E-mail: lionel.rossi@cea.fr

    2016-12-15

    Gas entrainment from surface swirls is characterized using water experiments. A free surface shear flow is generated in an open channel flow. A suction nozzle is set at the bottom of the test section to induce a downward flow and provoke gas entrainment. An important originality of these experiments is the possibility to change the inlet condition so as to generate different turbulent shear flows. This is done by adding obstacles of different sizes and shapes at the end of a flat plate separating the inlet flow from a “stagnant” water area. Velocity fields and profiles, measured with the PIV technique, are provided both to describe the inlet conditions corresponding to various geometries and flow rates, and to characterize the temporal average shear flow generated within the centre part of the channel. Gas entrainment mappings are established from direct observations of the different flow configurations. These new results show that the threshold for the suction velocities required to entrain gas are similar for the configurations with small obstacles and the flat plate configuration triggering a standard shear flow. Increasing the size of the obstacles promotes gas entrainment and reduces the threshold values of the suction velocity to trigger gas entrainment. Shadowgraphy with image processing is used to present new results characterizing the geometrical properties of surface swirls and the quantity of gas entrained. Inlet configurations with obstacles generate larger surface swirls which move upstream from the suction nozzle centre whereas they are situated downstream with the flat plate configuration. Moreover, dimensionless power laws are found to be good approximations for the surface swirl width and the quantity of gas entrained. In addition to provide new insights about gas entrainment in analytical configurations relevant to Sodium cooled fast nuclear reactor, these results should provide different test cases for the validation of MCFD codes.

  4. Biological characterization of implant surfaces - in vitro study

    Directory of Open Access Journals (Sweden)

    Priscilla Barbosa Ferreira Soares

    Full Text Available AbstractObjectiveEvaluate the biological performance of titanium alloys grade IV under different surface treatments: sandblasting and double etching (Experimental surface 1; Exp1, NEODENT; surface with wettability increase (Experimental surface 2; Exp2, NEODENT on response of preliminary differentiation and cell maturation.Material and methodImmortalized osteoblast cells were plated on Exp1 and Exp2 titanium discs. The polystyrene plate surface without disc was used as control group (C. Cell viability was assessed by measuring mitochondrial activity (MTT at 4 and 24 h (n = 5, cell attachment was performed using trypan blue exclusion within 4 hours (n = 5, serum total protein and alkaline phosphatase normalization was performed at 4, 7 and 14 days (n = 5. Data were analyzed using one-way ANOVA and Tukey test.ResultThe values of cell viability were: 4h: C– 0.32±0.01A; Exp1– 0.34±0.08A; Exp2– 0.29±0.03A. 24h: C– 0.43±0.02A; Exp1– 0.39±0.01A; Exp2– 0.37±0.03A. The cell adhesion counting was: C– 85±10A; Exp1- 35±5B; Exp2– 20±2B. The amounts of serum total protein were 4d: C– 40±2B; Exp1– 120±10A; Exp2– 130±20A. 7d: C– 38±2B; Exp1– 75±4A; Exp2– 70±6A. 14 d: C– 100±3A; Exp1– 130±5A; Exp2– 137±9A. The values of alkaline phosphatase normalization were: 4d: C– 2.0±0.1C; Exp1– 5.1±0.8B; Exp2– 9.8±2.0A. 7d: C– 1.0±0.01C; Exp1– 5.3±0.5A; Exp2– 3.0±0.3B. 14 d: C– 4.1±0.3A; Exp1– 4.4±0.8A; Exp2– 2.2±0.2B. Different letters related to statistical differences.ConclusionThe surfaces tested exhibit different behavior at dosage of alkaline phosphatase normalization showing that the Exp2 is more associated with induction of cell differentiation process and that Exp1 is more related to the mineralization process.

  5. SURFACE FLOODS IN COIMBRA: simple and dual-drainage studies

    Science.gov (United States)

    Leitão, J. P.; Simões, N. E.; Pina, R.; Marques, A. Sá; Maksimović, Č.; Gonçalves, Gil

    2009-09-01

    Surface water flooding occurs due to extreme rainfall and the inability of the sewer system to drain all runoff. As a consequence, a considerable volume of water is carried out over the surface through preferential flow paths and can eventually accumulate in natural (or man-made) ponds. This can cause minor material losses but also major incidents with obvious consequences in economic activities and the normal people's life. Unfortunately, due to predicted climate changes and increase of urbanisation levels, the urban flooding phenomenon has been reported more often. The Portuguese city of Coimbra is a medium size city that has suffered several river floods in the past. However, after the construction of hydraulic control structures, the number of fluvial flood events was greatly reduced. In the 1990s two new problems started. On one hand, houses started to be built on flood plain areas; on the other hand, some areas experienced a boom in the degree of urbanisation. This created flood problems of a different type dislocating the flood areas from the traditional flood areas along the river to new areas that did not reported flood in history. The catchment studied has a total area of approximately 1.5 km2 and discharges in the Coselhas brook The catchment can be divided in three regions with different characteristics: (i) the "Lower City" which is a low-lying area with 0.4 km2 and with a combined sewer system; (ii) the "Upper City" which is a considerably hilly area, highly urbanized and with an area of approximately 0.2 km2; and (iii) the remaining area which is also highly urbanized, with an area of 0.9 km2, where the main flood problems are generated. The sewer system is 34.8 km long; 29 km are of the combined type, and only 1.2 km is exclusive for storm water. The time of concentration of the catchment is estimated to be 45 min. On the 9 June 2006, an extreme rainfall event caused severe flooding in the city. After the rainfall had stopped, water continued to

  6. Studies on electronic structure of GaN(0001) surface

    CERN Document Server

    Xie Chang Kun; Xu Fa Qiang; Deng Rui; Liu Feng; Yibulaxin, K

    2002-01-01

    An electronic structure investigation on GaN(0001) is reported. The authors employ a full-potential linearized augmented plane-wave (FPLAPW) approach to calculate the partial density of state, which is in agreement with previous experimental results. The effects of the Ga3d semi-core levels on the electronic structure of GaN are discussed. The valence-electronic structure of the wurtzite GaN(0001) surface is investigated using synchrotron radiation excited angle-resolved photoemission spectroscopy. The bulk bands dispersion along GAMMA A direction in the Brillouin zones is measured using normal-emission spectra by changing photon-energy. The band structure derived from authors' experimental data is compared well with the results of authors' FPLAPW calculation. Furthermore, off-normal emission spectra are also measured along the GAMMA K and GAMMA M directions. Two surface states are identified, and their dispersions are characterized

  7. Synthesis long life storage studies surface storage of vitrified wastes

    International Nuclear Information System (INIS)

    Beziat, A.; Breton, E.; Ranc, G.; Gaillard, J.P.; Lagrave, H.; Hollender, F.; Jourdain, F.; Piault, E.; Garnier, J.; Lamare, V.; Duret, B.; Helie, M.; Ferry, C.; Mijuin, D.; Gagnier, E.

    2004-01-01

    This document is realized in the framework of the axis 3 of the law of 1991 on the radioactive wastes management. It justifies the choices concerning long time surface storage installation of vitrified wastes, called high activity wastes. The long time of the installation would reach 300 years at the maximum. These wastes represent 1 % at the maximum, of radioactive wastes in France but 95 % of the whole radioactivity. Three main objectives were followed: provide a permanent containment of radionuclides; give the possibility of wastes containers retrieval at all the time; minimize the maintenance and the control. The results allow to conclude that the long time surface storage of high activity wastes is feasible. (A.L.B.)

  8. DOUBLE CURVED SURFACE (DCS) - Case study in reinforced concrete

    DEFF Research Database (Denmark)

    Esteves, Luis Pedro; Henriques, Goncalo

    2007-01-01

    properties as deformability under compression, water tightness and finish on concrete prefabrication was analysed. This enabled high flexibility of architectural forms and textures, integrated in structural elements. Limitations were found on the mould reuse for several elements.......This paper deals with digital integration between design and fabrication in order to construct a complex double-curved concrete surface. This research focused on practical application of CNC technology to polyurethane (EPS), as an alternative to concrete formwork. The influence of specific EPS...

  9. Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

    NARCIS (Netherlands)

    van Angelen, J.H.|info:eu-repo/dai/nl/325922470; Lenaerts, J.T.M.|info:eu-repo/dai/nl/314850163; Lhermitte, S.; Fettweis, X.; Kuipers Munneke, P.|info:eu-repo/dai/nl/304831891; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van Meijgaard, E.; Smeets, C.J.P.P.|info:eu-repo/dai/nl/191522236

    2012-01-01

    We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover,

  10. Study of the processes of adsorption of amine-containing surface-active substance on the surface of Aluminum powder

    Directory of Open Access Journals (Sweden)

    Antonina Dyuryagina

    2012-03-01

    Full Text Available Equilibrium characteristics of adsorption on a surface of a pigment depending on concentration factors and temperature of the dispersive environment are defined. Kinetic laws of superficial activity of binary, threefold homogeneous and heterogeneous modeling systems are studied. The estimation of mechanisms of process of adsorption is carried out.

  11. Spectral studies of Lanthanide interactions with membrane surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Karukstis, K.K.; Kao, M.Y.; Savin, D.A.; Bittker, R.A.; Kaphengst, K.J.; Emetarom, C.M.; Naito, N.R.; Takamoto, D.Y. [Harvey Mudd College, Claremont, CA (United States)

    1995-03-23

    We have monitored the interactions of the series of trivalent lanthanide cations with the thylakoid membrane surface of spinach chloroplasts using two complementary spectral techniques. Measurements of the fluorescence emission of the extrinsic probe 2-p-toluidinonaphthalene-6-sulfonate (TNS) and the absorbance of the intrinsic chromophore chlorophyll provide two sensitive means of characterizing the dependence of the cation-membrane interaction on the nature of the cation. In these systems, added lanthanide cations adsorb onto the membrane surface to neutralize exposed segments of membrane-embedded protein complexes. The lanthanide-induced charge neutralization increases the proximity of added TNS anion to the membrane surface as evidenced by variations in the TNS fluorescence level and wavelength of maximum emission. Our results reveal a strong dependence of TNS fluorescence parameters on both lanthanide size and total orbital angular momentum L value. Lanthanides with greater charge density (small size and/or low L value) enhance the TNS fluorescence level to a greater extent. A possible origin for the lanthanide-dependent TNS fluorescence levels is suggested in terms of a heterogeneity in the number and type of TNS binding sites. The data are consistent with the proposal that larger lanthanides with smaller enthalpies of hydration induce more significant membrane appression. 59 refs., 9 figs., 2 tabs.

  12. DETERMINATION OF IMPORTANCE EVALUATION FOR THE SURFACE EXPLORATORY STUDIES FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    C.J. Byrne

    2000-07-25

    This DIE applies to the surface facilities component of the Yucca Mountain Site Characterization Project (W) ESF. The ESF complex-including surface and subsurface accommodations--encompasses an area that is approximately six miles wide and nine miles long (approximately 30,000 acres total) (United States Department of Energy [DOE] 1997, p. 9.04). It is located on federally withdrawn lands, near the southwest border of the Nevada Test Site (NTS) in southern Nevada (DOE 1997, p. 9.04). Site characterization activities are conducted within the subsurface ESF to obtain the information necessary to determine whether the Yucca Mountain Site is suitable as a geologic repository for spent nuclear fuel and high-level radioactive waste. Most ESF surface facilities are located within the Conceptual Controlled Area Boundary (CCAB) (DOE 1997, p. 9.04), with the exception of the southeastern most portions of the H-Road and the Water Supply System. Various SBT activities are also conducted throughout the Yucca Mountain region as a part of the overall site-characterization effort. In general, the DIE for SBT Activities (Civilian Radioactive Waste Management System [CRWMS] Management and Operating Contractor [M&O] 1998a) evaluates activities associated with SBT. Potential test-to-test interference and waste isolation impacts associated with SBT activities are also evaluated in CRWMS M&O (1998a).

  13. DETERMINATION OF IMPORTANCE EVALUATION FOR THE SURFACE EXPLORATORY STUDIES FACILITY

    International Nuclear Information System (INIS)

    C.J. Byrne

    2000-01-01

    This DIE applies to the surface facilities component of the Yucca Mountain Site Characterization Project (W) ESF. The ESF complex-including surface and subsurface accommodations--encompasses an area that is approximately six miles wide and nine miles long (approximately 30,000 acres total) (United States Department of Energy [DOE] 1997, p. 9.04). It is located on federally withdrawn lands, near the southwest border of the Nevada Test Site (NTS) in southern Nevada (DOE 1997, p. 9.04). Site characterization activities are conducted within the subsurface ESF to obtain the information necessary to determine whether the Yucca Mountain Site is suitable as a geologic repository for spent nuclear fuel and high-level radioactive waste. Most ESF surface facilities are located within the Conceptual Controlled Area Boundary (CCAB) (DOE 1997, p. 9.04), with the exception of the southeastern most portions of the H-Road and the Water Supply System. Various SBT activities are also conducted throughout the Yucca Mountain region as a part of the overall site-characterization effort. In general, the DIE for SBT Activities (Civilian Radioactive Waste Management System [CRWMS] Management and Operating Contractor [M andO] 1998a) evaluates activities associated with SBT. Potential test-to-test interference and waste isolation impacts associated with SBT activities are also evaluated in CRWMS M andO (1998a)

  14. Study on the Light Scattering from Random Rough Surfaces by Kirrhoff Approximation

    Directory of Open Access Journals (Sweden)

    Keding Yan

    2014-07-01

    Full Text Available In order to study the space distribution characteristics of light scattering from random rough surfaces, the linear filtering method is used to generate a series of Gaussian randomly rough surfaces, and the Kirchhoff Approximation is used to calculate the scattered light intensity distribution from random metal and dielectric rough surfaces. The three characteristics of the scattered light intensity distribution peak, the intensity distribution width and the position of peak are reviewed. Numerical calculation results show that significant differences between scattering characteristics of metal surfaces and the dielectric surfaces exist. The light scattering characteristics are jointly influenced by the slope distribution and reflectance of surface element. The scattered light intensity distribution is affected by common influence of surface local slope distribution and surface local reflectivity. The results can provide a basis theory for the research to lidar target surface scattering characteristics.

  15. DFT studies of hydrocarbon combustion on metal surfaces.

    Science.gov (United States)

    Arya, Mina; Mirzaei, Ali Akbar; Davarpanah, Abdol Mahmood; Barakati, Seyed Masoud; Atashi, Hossein; Mohsenzadeh, Abas; Bolton, Kim

    2018-02-02

    Catalytic combustion of hydrocarbons is an important technology to produce energy. Compared to conventional flame combustion, the catalyst enables this process to operate at lower temperatures; hence, reducing the energy required for efficient combustion. The reaction and activation energies of direct combustion of hydrocarbons (CH → C + H) on a series of metal surfaces were investigated using density functional theory (DFT). The data obtained for the Ag, Au, Al, Cu, Rh, Pt, and Pd surfaces were used to investigate the validity of the Brønsted-Evans-Polanyi (BEP) and transition state scaling (TSS) relations for this reaction on these surfaces. These relations were found to be valid (R 2  = 0.94 for the BEP correlation and R 2  = 1.0 for the TSS correlation) and were therefore used to estimate the energetics of the combustion reaction on Ni, Co, and Fe surfaces. It was found that the estimated transition state and activation energies (E TS  = -69.70 eV and E a  = 1.20 eV for Ni, E TS  = -87.93 eV and E a  = 1.08 eV for Co and E TS  = -92.45 eV and E a  = 0.83 eV for Fe) are in agreement with those obtained by DFT calculations (E TS  = -69.98 eV and E a  = 1.23 eV for Ni, E TS  = -87.88 eV and E a  = 1.08 eV for Co and E TS  = -92.57 eV and E a  = 0.79 eV for Fe). Therefore, these relations can be used to predict energetics of this reaction on these surfaces without doing the time consuming transition state calculations. Also, the calculations show that the activation barrier for CH dissociation decreases in the order Ag ˃ Au ˃ Al ˃ Cu ˃ Pt ˃ Pd ˃ Ni > Co > Rh > Fe.

  16. A Study on the Relationships among Surface Variables to Adjust the Height of Surface Temperature for Data Assimilation.

    Science.gov (United States)

    Kang, J. H.; Song, H. J.; Han, H. J.; Ha, J. H.

    2016-12-01

    The observation processing system, KPOP (KIAPS - Korea Institute of Atmospheric Prediction Systems - Package for Observation Processing) have developed to provide optimal observations to the data assimilation system for the KIAPS Integrated Model (KIM). Currently, the KPOP has capable of processing almost all of observations for the KMA (Korea Meteorological Administration) operational global data assimilation system. The height adjustment of SURFACE observations are essential for the quality control due to the difference in height between observation station and model topography. For the SURFACE observation, it is usual to adjust the height using lapse rate or hypsometric equation, which decides values mainly depending on the difference of height. We have a question of whether the height can be properly adjusted following to the linear or exponential relationship solely with regard to the difference of height, with disregard the atmospheric conditions. In this study, firstly we analyse the change of surface variables such as temperature (T2m), pressure (Psfc), humidity (RH2m and Q2m), and wind components (U and V) according to the height difference. Additionally, we look further into the relationships among surface variables . The difference of pressure shows a strong linear relationship with difference of height. But the difference of temperature according to the height shows a significant correlation with difference of relative humidity than with the height difference. A development of reliable model for the height-adjustment of surface temperature is being undertaken based on the preliminary results.

  17. Surface plasmon enhanced interfacial electron transfer and resonance Raman, surface-enhanced resonance Raman studies of cytochrome C mutants

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Junwei [Iowa State Univ., Ames, IA (United States)

    1999-11-08

    Surface plasmon resonance was utilized to enhance the electron transfer at silver/solution interfaces. Photoelectrochemical reductions of nitrite, nitrate, and CO2 were studied on electrochemically roughened silver electrode surfaces. The dependence of the photocurrent on photon energy, applied potential and concentration of nitrite demonstrates that the photoelectrochemical reduction proceeds via photoemission process followed by the capture of hydrated electrons. The excitation of plasmon resonances in nanosized metal structures resulted in the enhancement of the photoemission process. In the case of photoelectrocatalytic reduction of CO2, large photoelectrocatalytic effect for the reduction of CO2 was observed in the presence of surface adsorbed methylviologen, which functions as a mediator for the photoexcited electron transfer from silver metal to CO2 in solution. Photoinduced reduction of microperoxidase-11 adsorbed on roughened silver electrode was also observed and attributed to the direct photoejection of free electrons of silver metal. Surface plasmon assisted electron transfer at nanostructured silver particle surfaces was further determined by EPR method.

  18. Study of sea surface temperature distribution, in Angra dos Reis Nuclear Plant region - Mission Angra 01

    International Nuclear Information System (INIS)

    Stevenson, M.R.; Steffen, C.A.; Villagra, H.M.I.

    1982-03-01

    A study of spectral and temporal variations of sea surface temperature, using data obtained from level of satellite, aircraft and surface, with the purpose of evaluate and plot the small scale variations of sea surface temperature, due to thermal discharge from a nuclear the results of the first mission called Angra 1. (maps). (C.G.C.)

  19. Study on the GaAs(110) surface using emitted atom spectrometry

    International Nuclear Information System (INIS)

    Gayone, J.E.; Sanchez, E.A.; Grizzi, O.; Universidad Nacional de Cuyo, Mendoza

    1998-01-01

    The facilities implemented at Bariloche for the ion scattering spectrometry is described, and recent examples of the technique application to determine the atomic structure and the composition of metallic and semiconductor surfaces, pure and with different adsorbates. The surface analysis technique using emitted atom spectrometry is discussed. The sensitivity to the GaAs(110) surface atomic relaxation is presented, and the kinetic of hydrogen adsorption by the mentioned surface is studied

  20. Final state effects in photoemission studies of Fermi surfaces

    International Nuclear Information System (INIS)

    Kurtz, Richard L; Browne, Dana A; Mankey, Gary J

    2007-01-01

    Photoelectron spectroscopy is one of the most important methods for extracting information about the Fermi surface (FS) of materials. An electron photoexcited from the FS is emitted from the crystal conserving the parallel momentum, k parallel , while the perpendicular momentum k perpendicular is reduced due to the surface potential barrier. A simple interpretation of the process assumes the final state is free-electron-like allowing one to 'map' the detected photoelectron back to its initial k momentum. There are multiple final state effects that can complicate the interpretation of photoelectron data and these effects are reviewed here. These can involve both energy and k broadening, which can give rise to shadow or ghost FS contours, scattering and final state diffraction effects that modify intensities, and matrix element effects which reflect the symmetries of the states involved and can be highly dependent on photon polarization. These matrix elements result in contours of photoelectron intensity that follow the dispersion in k-space of the initial state, the FS, and the final state. Locations where intensities go to zero due to matrix element and symmetry effects can result in gaps where FS contours 'disappear'. Recognition that these effects can play a significant role in determining the measured angular distributions is crucial in developing an informed model of where the FS contours actually lie in relation to measured intensity contours

  1. Transcription of Small Surface Structures in Injection Moulding - An Experimental Study

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf; Kjær, Erik Michael

    2000-01-01

    The ability to replicate the surface roughness from mold wall to the plastic part in injection moldning has many functional and cosmetic important implications from medical use to designer products. Generally the understanding of surface transcription i.e the the replication of the surface...... structure from the mould to plastic part, also relates to micro injection moulding and moulding of parts with specific micro structures on the surface such as optical parts. The present study concerns transcription of surface roughness as a function of process parameters. The study is carried out...

  2. Transcription of Small Surface Structures in Injection Molding - an Experimental Study

    DEFF Research Database (Denmark)

    Arlø, Uffe Rolf; Kjær, Erik Michael

    2001-01-01

    The ability to replicate the surface roughness from mold wall to the plastic part in injection moldning has many functional and cosmetic important implications from medical use to designer products. Generally the understanding of surface transcription i.e the the replication of the surface...... structure from the mould to plastic part, also relates to micro injection moulding and moulding of parts with specific micro structures on the surface such as optical parts. The present study concerns transcription of surface roughness as a function of process parameters. The study is carried out...

  3. Characterization Investigation Study: Volume 3, Radiological survey of surface soils

    Energy Technology Data Exchange (ETDEWEB)

    Solow, A.J.; Phoenix, D.R.

    1987-12-01

    The Feed Materials Production Center was constructed to produce high purity uranium metal for use at various Department of Energy facilities. The waste products from these operations include general uncontaminated scrap and refuse, contaminated and uncontaminated metal scrap, waste oils, low-level radioactive waste, co-contaminated wastes, mixed waste, toxic waste, sludges from water treatment, and fly ash from the steam plant. This material is estimated to total more than 350,000 cubic meters. Other wastes stored in this area include laboratory chemicals and other combustible materials in the burn pit; fine waste stream sediments in the clear well; fly ash and waste oils in the two fly ash areas; lime-alum sludges and boiler plant blowdown in the lime sludge ponds; and nonradioactive sanitary waste, construction rubble, and asbestos in the sanitary landfill. A systematic survey of the surface soils throughout the Waste Storage Area, associated on-site drainages, and the fly ash piles was conducted using a Field Instrument for Detecting Low-Energy Radiation (FIDLER). Uranium is the most prevalent radioactive element in surface soil; U-238 is the principal radionuclide, ranging from 2.2 to 1790 pCi/g in the general Waste Storage Area. The maximum values for the next highest activity concentrations in the same area were 972 pCi/g for Th-230 and 298 pCi/g for U-234. Elevated activity concentrations of Th-230 were found along the K-65 slurry line, the maximum at 3010 pCi/g. U-238 had the highest value of 761 pCi/g in the drainage just south of pit no. 5. The upper fly ash area had the highest radionuclide activity concentrations in the surface soils with the maximum values for U-238 at 8600 pCi/g, U-235 at 2190 pCi/g, U-234 at 11,400 pCi/g, Tc-99 at 594 pCi/g, Ra-226 at 279 pCi/g, and Th-230 at 164 pCi/g.

  4. Study on the energy performance of glazing surfaces

    Directory of Open Access Journals (Sweden)

    Ligia MOGA

    2014-12-01

    Full Text Available A proper thermal design of the building envelope represents an important factor for the energy economics. Glazing surfaces represent one of the important elements in the hygrothermal design activity of a building envelope. The window’s thermal performance has also a strong influence on the thermal performance of the opaque area of the wall. This fact imposed the research of the real interaction, of cooperation and of mutual influences of the characteristics between the two components of the wall of the building envelope, respectively the opaque and the glazing area. Optimal constructive details for the opaque and glazing area of the wall need to be properly designed in order to achieve the required thermal and energy performances imposed for new types of buildings, e.g. passive houses, zero energy buildings.

  5. Photoelectron spectroscopy: a strategy for the study of reactions at solid surfaces

    Science.gov (United States)

    Au, C. T.; Carley, A. F.; Roberts, M. W.

    The development of X-ray photoelectron spectroscopy for the study of the nature of chemisorbed species and the mechanisms of surface reactions is described. The methodology of data analysis and the establishment of data banks which enable photoelectron spectra to be assigned to specific surface species is discussed by reference to examples from recent studies. Although in the first instance the primary aim was to establish a qualitative logic in a well defined area of surface chemistry, this was then developed quantitatively and extended to studies of the mechanism of surface catalysed reactions. Emphasis is given here to the activation of molecules at metal surfaces either by surface modification or through chemical specificity which is associated with coadsorbed molecules. As illustration we discuss the activation of O-H and N-H bonds by `oxygen' resulting in reaction pathways being followed which would not have been predicted on the basis of the known reactivities of the individual molecules. The examples chosen also illustrate the severe limitations of mechanistic studies in surface chemistry based (a) on the study of the individual reactants separately; (b) on a post-mortem type of analysis of the surface and (c) on just a gaseous product analysis. An important concept that has emerged is the dual role of surface `oxygen'. It may either act as a promoter in activating an otherwise unreactive adsorbate molecule, or it may form an unreactive oxide overlayer. Parallel studies of metal oxides per se provide information on the defect nature of both oxide overlayers at metal surfaces and also bulk oxide surfaces. Close similarities are shown to exist between the `oxygen' activation of molecules at metal surfaces and the catalytic reactivity of defective bulk oxides. A common theme is that the dominant mechanism involves hydrogen abstraction by oxygen adatoms, which are assigned as O-(s) both at metal surfaces (by XPS) and at bulk oxide surfaces (by E.P.R. and XPS).

  6. Numerical study of surface water waves generated by mass movement

    Energy Technology Data Exchange (ETDEWEB)

    Ghozlani, Belgacem; Hafsia, Zouhaier; Maalel, Khlifa, E-mail: ghozlanib@yahoo.fr [Ecole Nationale d' Ingenieurs de Tunis, Laboratoire de Modelisation en ' Hydraulique et Environnement, BP 37, Le Belvedere, 1002 Tunis (Tunisia)

    2013-10-01

    In this paper waves generated by two-dimensional mass movement are simulated using a numerical model based on the full hydrodynamic coupling between rigid-body motion and ambient fluid flow. This approach has the capability to represent the dynamics of the moving rigid body, which avoids the need to prescribe the body velocity based on the data measurements. This model is implemented in the CFX code and uses the Reynolds average Navier-Stokes equations solver coupled to the recently developed immersed solid technique. The latter technique allows us to follow implicitly the motion of the solid block based on the rigid body solver. The volume-of-fluid method is used to track the free surface locations. The accuracy of the present model is firstly examined against the simple physical case of a freely falling rigid body into water reproducing Scott Russell's solitary waves. More complex and realistic simulations of aerial and submarine mass-movement, simulated by a rigid wedge sliding into water along a 45 Degree-Sign slope, are then performed. Simulated results of the aerial mass movement show the complex flow patterns in terms of the velocity fields and free surface profiles. Results are in good agreement with the available experimental data. In addition, the physical processes associated with the generation of water wave by two-dimensional submarine mass-movement are explored. The effects of the initial submergence and specific gravity on the slide mass kinematics and maximum wave amplitude are investigated. The terminal velocity and initial acceleration of the slide mass are well predicted when compared to experimental results. It is found that the initial submergence did not have a significant effect on the initial acceleration of the slide block centre of mass. However, it depends nonlinearly on the specific gravity. The maximum wave amplitude and the time at which it occurred are also presented as a function of the initial submergence and specific gravity

  7. An ab initio study of plutonium oxides surfaces; Etude ab initio des surfaces d'oxydes de Pu

    Energy Technology Data Exchange (ETDEWEB)

    Jomard, G.; Bottin, F.; Amadon, B

    2007-07-01

    By means of first-principles calculations, we have studied the atomic structure as well as the thermodynamic stability of various plutonium dioxide surfaces in function of their environment (in terms of oxygen partial pressure and temperature). All these simulations have been performed with the ABINIT code. It is well known that DFT fails to describe correctly plutonium-based materials since 5f electrons in such systems are strongly correlated. In order to go beyond DFT, we have treated PuO{sub 2} and {beta}-Pu{sub 2}O{sub 3} in a DFT+U framework. We show that the couple of parameters (U,J) that works well for pure Pu is also well designed for describing ground state (GS) properties of these two oxides. The major improvement with respect with DFT is that we are able to predict an insulating GS in agreement with experiments. The presence of a gap in the DOS (Density of States) of plutonium oxides should play a significant role in the predicted surface reactivity. However, performing DFT+U calculations on surfaces of plutonium oxide from scratch was too ambitious. That is why we decided, as a first step, to study the stability of the (100), (110) and (111) surfaces of PuO{sub 2} in a DFT-GGA framework. For each of these orientations, we considered various terminations. These ab initio results have been introduced in a thermodynamic model which allows us to predict the relative stability of the different terminations as a function of temperature and oxygen partial pressure (p{sub O{sub 2}}). We conclude that at room temperature and for p{sub O{sub 2}}{approx}10 atm., the polar O{sub 2}-(100) termination is favoured. The stabilization of such a polar stoichiometric surface is surprising and should be confirmed by DFT+U calculations before any final conclusion. (authors)

  8. Near-Surface Fault Structures of the Seulimuem Segment Based on Electrical Resistivity Model

    Science.gov (United States)

    Ismail, Nazli; Yanis, Muhammad; Idris, Syafrizal; Abdullah, Faisal; Hanafiah, Bukhari

    2017-05-01

    The Great Sumatran Fault (GSF) system is arc-parallel strike-slip fault system along the volcanic front related to the oblique subduction of the oceanic Indo-Australian plate. Large earthquakes along the southern GSF since 1892 have been reported, but the Seulimuem segment at the northernmost Sumatran has not produced large earthquakes in the past 100 years. The 200-km-long segment is considered to be a seismic gap. Detailed geological study of the fault and thus its surface trace locations, late Quaternary slip rate, and rupture history are urgently needed for earthquake disaster mitigation in the future. However, finding a suitable area for paleoseismic trenching is an obstacle when the fault traces are not clearly shown on the surface. We have conducted geoelectrical measurement in Lamtamot area of Aceh Besar District in order to locate the fault line for paleoseismic excavation. Apparent resistivity data were collected along 40 m profile parallel to the planned trenching site. The 2D electrical resistivity model provided evidence of some resistivity anomalies by high lateral contrast. This anomaly almost coincides with the topographic scarp which is modified by agriculture on the surface at the northern part of Lamtamot. The steep dipping electrical contrast may correspond to a fault. However, the model does not resolve well evidences from minor faults that can be related to the presence of surface ruptures. A near fault paleoseismic investigation requires trenching across the fault in order to detect and analyze the geological record of the past large earthquakes along the Seulimuem segment.

  9. Study on Surface Heat Budget of Various Pavements for Urban Heat Island Mitigation

    Directory of Open Access Journals (Sweden)

    Hideki Takebayashi

    2012-01-01

    Full Text Available The surface heat budgets of various pavement surfaces are studied with the aim of mitigating the urban heat island effect. In this study, the thermal characteristics of pavements are examined using data from observations. The net radiation, surface temperature, temperature under the surface, conduction heat flux, and core weight for each experimental surface are recorded, together with the weather conditions at the time of observation. The latent heat flux is estimated from the observed weight of the cores. The surface heat budget under the same weather conditions is examined, and the sensible heat flux from each target surface is calculated. The parameters that influence the surface heat budget, for example, solar reflectance (albedo, evaporative efficiency, heat conductivity, and heat capacity, are examined. On a typical summer day, the maximum reduction in the sensible heat flux from that on a normal asphalt surface is about 150 W/m2 for an asphalt surface with water-retaining material and about 100 W/m2 for a cement concrete surface with water-retaining material, depending on the albedo of each surface.

  10. Microbial Observatory (ISS-MO): Indoor microbiome study of the International Space Station surfaces

    Data.gov (United States)

    National Aeronautics and Space Administration — Presented here is the environmental microbiome study of the International Space Station surfaces. The environmental samples were collected with the polyester wipes...

  11. Solid state cesium ion guns for surface studies

    International Nuclear Information System (INIS)

    Souzis, A.E.; Carr, W.E.; Kim, S.I.; Seidl, M.

    1990-01-01

    Three cesium ion guns covering the energy range of 5--5000 V are described. These guns use a novel source of cesium ions that combine the advantages of porous metal ionizers with those of aluminosilicate emitters. Cesium ions are chemically stored in a solid electrolyte pellet and are thermionically emitted from a porous thin film of tungsten at the surface. Cesium supply to the emitting surface is controlled by applying a bias across the pellet. A total charge of 10.0 C can be extracted, corresponding to greater than 2000 h of lifetime with an extraction current of 1.0 μA. This source is compact, stable, and easy to use, and produces a beam with >99.5% purity. It requires none of the differential pumping or associated hardware necessary in designs using cesium vapor and porous tungsten ionizers. It has been used in ultrahigh-vacuum (UHV) experiments at pressures of -10 Torr with no significant gas load. Three different types of extraction optics are used depending on the energy range desired. For low-energy deposition, a simple space-charge-limited planar diode with a perveance of 1x10 -7 A/V 3/2 is used. Current densities of 10.0 μA/cm 2 at the exit aperture for energies ≤20 V are typical. This type of source provides an alternative to vapor deposition with the advantage of precise flux calibration by integration of the ion current. For energies from 50 to 500 V and typical beam radii of 0.5 to 0.2 mm, a high perveance Pierce-type ion gun is used. This gun was designed with a perveance of 1x10 -9 A/V 3/2 and produces a beam with an effective temperature of 0.35 eV. For the energy range of 0.5 to 5 keV, the Pierce gun is used in conjunction with two Einzel lenses, enabling a large range of imaging ratios to be obtained. Beam radii of 60 to 300 μm are typical for beam currents of 50 nA to 1.0 μA

  12. Study on the surface oxidation resistance of uranium metal in the atmosphere of carbon monoxide

    International Nuclear Information System (INIS)

    Wang Xiaolin; Fu Yibei; Xie Renshou

    1999-01-01

    The surface reactions of different layers on uranium metal with carbon monoxide at 25, 80 and 200 degree C are studied by X-ray photoelectron spectroscopy (XPS). The experimental results show that the carbon monoxide is adsorbed on the surface oxide layer of uranium and interacted each other. The content of oxygen in the surface oxide and O/U ratio are decreased with increasing the exposure of carbon monoxide to the surface layer. The effect of reduction on the metal surface is more obviously with a higher temperature and increasing of layer thickness. The investigation indicates the uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide

  13. Study on Alternative Cargo Launch Options from the Lunar Surface

    Energy Technology Data Exchange (ETDEWEB)

    Cheryl A. Blomberg; Zamir A. Zulkefli; Spencer W. Rich; Steven D. Howe

    2013-07-01

    In the future, there will be a need for constant cargo launches from Earth to Mars in order to build, and then sustain, a Martian base. Currently, chemical rockets are used for space launches. These are expensive and heavy due to the amount of necessary propellant. Nuclear thermal rockets (NTRs) are the next step in rocket design. Another alternative is to create a launcher on the lunar surface that uses magnetic levitation to launch cargo to Mars in order to minimize the amount of necessary propellant per mission. This paper investigates using nuclear power for six different cargo launching alternatives, as well as the orbital mechanics involved in launching cargo to a Martian base from the moon. Each alternative is compared to the other alternative launchers, as well as compared to using an NTR instead. This comparison is done on the basis of mass that must be shipped from Earth, the amount of necessary propellant, and the number of equivalent NTR launches. Of the options, a lunar coil launcher had a ship mass that is 12.7% less than the next best option and 17 NTR equivalent launches, making it the best of the presented six options.

  14. Response Predicting LTCC Firing Shrinkage: A Response Surface Analysis Study

    Energy Technology Data Exchange (ETDEWEB)

    Girardi, Michael; Barner, Gregg; Lopez, Cristie; Duncan, Brent; Zawicki, Larry

    2009-02-25

    The Low Temperature Cofired Ceramic (LTCC) technology is used in a variety of applications including military/space electronics, wireless communication, MEMS, medical and automotive electronics. The use of LTCC is growing due to the low cost of investment, short development time, good electrical and mechanical properties, high reliability, and flexibility in design integration (3 dimensional (3D) microstructures with cavities are possible)). The dimensional accuracy of the resulting x/y shrinkage of LTCC substrates is responsible for component assembly problems with the tolerance effect that increases in relation to the substrate size. Response Surface Analysis was used to predict product shrinkage based on specific process inputs (metal loading, layer count, lamination pressure, and tape thickness) with the ultimate goal to optimize manufacturing outputs (NC files, stencils, and screens) in achieving the final product design the first time. Three (3) regression models were developed for the DuPont 951 tape system with DuPont 5734 gold metallization based on green tape thickness.

  15. Evaluation of surface roughness of the bracket slot floor—a 3D perspective study

    Directory of Open Access Journals (Sweden)

    Chetankumar O. Agarwal

    2016-01-01

    Full Text Available Abstract Background An important constituent of an orthodontic appliance is orthodontic brackets. It is either the bracket or the archwire that slides through the bracket slot, during sliding mechanics. Overcoming the friction between the two surfaces demands an important consideration in an appliance design. The present study investigated the surface roughness of four different commercially available stainless steel brackets. Methods All tests were carried out to analyse quantitatively the morphological surface of the bracket slot floor with the help of scanning electron microscope (SEM machine and to qualitatively analyse the average surface roughness (Sa of the bracket slot floor with the help of a three-dimensional (3D non-contact optical surface profilometer machine. Results The SEM microphotographs were evaluated with the help of visual analogue scale, the surface roughness for group A = 0—very rough surface, group C = 1—rough surface, group B = 2—smooth surface, and group D = 3—very smooth surface. Surface roughness evaluation with the 3D non-contact optical surface profilometer machine was highest for group A, followed by group C, group B and group D. Groups B and D provided smooth surface roughness; however, group D had the very smooth surface with values 0.74 and 0.75 for mesial and distal slots, respectively. Conclusions Evaluation of surface roughness of the bracket slot floor with both SEM and profilometer machine led to the conclusion that the average surface roughness was highest for group A, followed by group C, group B and group D.

  16. Multiple sectioning and perforation techniques for TEM sub-surface studies

    International Nuclear Information System (INIS)

    Lee, E.H.; Rowcliffe, A.F.

    1978-01-01

    Techniques for preparing multiple electron transparent regions at several depth levels below the surface of a metal disk specimen are described. These techniques are relatively rapid and find application in many areas involving surface studies. Examples are shown of multiple thin areas produced at intervals of approximately 200 nm below the original surface of a stainless steel bombarded with 4 MeV Ni +2 ions for void swelling studies

  17. Structural sensitivity studies of ethylene hydrogenation on platinum and rhodium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Quinlan, M.A. [California Univ., Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States)

    1996-01-01

    The catalytic hydrogenation of ethylene and hydrogen on the well characterized surfaces of the noble metals platinum and rhodium has been studied for the purposes of determining the relative activity of these two substrates as well as the degree of structure sensitivity. The Pt(111) and the Rh(755) single crystal surfaces,as well as Pt and Rh foils, were employed as substrates to study the effect of surface step structure on reactivity. In addition, vibrational spectroscopy studies were performed for ethylene adsorption on the stepped Rh(755) surface. The catalytic reaction were obtained using a combined ultrahigh vacuum chamber coupled with an atmospheric pressure reaction chamber that functioned as a batch reactor. Samples could be prepared using standard surface science techniques and characterized for surface composition and geometry using Auger Electron Spectroscopy and Low Energy Electron Diffraction. A comparison of the reactivity of Rh(111) with the results from this study on Rh(755) allows a direct determination of the effect of step structure on ethylene hydrogenation activity. Structure sensitivity is expected to exhibit orders of magnitude differences in rate as surface orientation is varied. In this case, no significant differences were found, confirming the structure insensitivity of this reaction over this metal. The turnover frequency of the Rh(111) surface, 5 {times} 10{sup 1} s{sup {minus}1}, is in relatively good agreement with the turnover frequency of 9 {times} 10{sup 1} s{sup {minus}1} measured for the Rh(755) surface. Rate measurements made on the Pt(111) surface and the Pt foil are in excellent agreement, both measuring 3 {times} 10{sup 2} s{sup minus}1. Likewise, it is concluded that no strong structure sensitivity for the platinum surfaces exists. High Resolution Electron Energy Loss Spectroscopy studies of adsorbed ethylene on the Rh(755) surface compare favorably with the ethylidyne spectra obtained on the Rh(111) and Rh(100) surfaces.

  18. Surface studies of nitrogen implanted TiO2

    International Nuclear Information System (INIS)

    Batzill, Matthias; Morales, Erie H.; Diebold, Ulrike

    2007-01-01

    Rutile TiO 2 (1 1 0) single crystals have been doped by nitrogen-ion implantation. The change in the valence band and in the core level peak shapes are characterized by photoemission spectroscopy. Surface morphologies are characterized by scanning tunneling microscopy. N-dopants are observed to be in a 3- charge state and to substitute for O-anions in the TiO 2 lattice for N-concentrations up to ∼5% of the anions. The higher valency of the N-dopants compared to the host O-anions is proposed to be compensated by the formation of O-vacancies and/or Ti-interstitials. Two chemically shifted components arise in the Ti-2p core level upon N-doping. These components, shifted by 0.9 eV and 2.1 eV, are assigned to Ti-bound to N-ligands and possibly due to O-vacancies in the lattice. The Ti-3d band gap state observed in UPS is initially suppressed upon room temperature N-implantation and recovers a similar intensity as for undoped TiO 2 samples upon annealing. This indicates that electrons left behind upon creation of O-vacancies are filling the N-2p level rather than Ti-3d states. The filled N-2p state is found at the top of the TiO 2 valence band and is believed to be responsible for the band gap narrowing of N-doped TiO 2 that shifts the photoactivity of TiO 2 into the visible spectrum

  19. Downscaling Satellite Land Surface Temperatures in Urban Regions for Surface Energy Balance Study and Heat Index Development

    Science.gov (United States)

    Norouzi, H.; Bah, A.; Prakash, S.; Nouri, N.; Blake, R.

    2017-12-01

    A great percentage of the world's population reside in urban areas that are exposed to the threats of global and regional climate changes and associated extreme weather events. Among them, urban heat islands have significant health and economic impacts due to higher thermal gradients of impermeable surfaces in urban regions compared to their surrounding rural areas. Therefore, accurate characterization of the surface energy balance in urban regions are required to predict these extreme events. High spatial resolution Land surface temperature (LST) in the scale of street level in the cities can provide wealth of information to study surface energy balance and eventually providing a reliable heat index. In this study, we estimate high-resolution LST maps using combination of LandSat 8 and infrared based satellite products such as Moderate Resolution Imaging Spectroradiometer (MODIS) and newly launched Geostationary Operational Environmental Satellite-R Series (GOES-R). Landsat 8 provides higher spatial resolution (30 m) estimates of skin temperature every 16 days. However, MODIS and GOES-R have lower spatial resolution (1km and 4km respectively) with much higher temporal resolution. Several statistical downscaling methods were investigated to provide high spatiotemporal LST maps in urban regions. The results reveal that statistical methods such as Principal Component Analysis (PCA) can provide reliable estimations of LST downscaling with 2K accuracy. Other methods also were tried including aggregating (up-scaling) the high-resolution data to a coarse one to examine the limitations and to build the model. Additionally, we deployed flux towers over distinct materials such as concrete, asphalt, and rooftops in New York City to monitor the sensible and latent heat fluxes through eddy covariance method. To account for the incoming and outgoing radiation, a 4-component radiometer is used that can observe both incoming and outgoing longwave and shortwave radiation. This

  20. [Terahertz-band study on surface enhanced Raman scattering of nanoparticle].

    Science.gov (United States)

    Wu, Yu-Deng; Ren, Guang-Jun; Hao, Yun; Yao, Jian-Quan

    2013-05-01

    Study on surface-enhanced Raman scattering in the terahertz-band proved in that the terahertz-band Raman enhancement also exists. By studing principles of electromagnetic enhancement of surface-enhanced Raman scattering, using the finite difference time-domain method, the electromagnetic enhancement of surface enhanced Raman scattering of nano-particles irradiated by terahertz-wave was simulated, and the enhancement effect of terahertz waves was analyzed. Simulation experiments show that using finite-difference time-domain method could obtain effectively accurate simulation result of nano-particle scattering, proving that for terahertz waves, surface-enhanced effects on the surface of the nano-particle also exist. The results for surface enhanced Raman scattering extended from the visible and infrared to terahertz-band, and provide a basis for application of the combination of surface-enhanced Raman scattering and terahertz-wave.

  1. Inherent wettability of different rock surfaces at nanoscale: a theoretical study

    Science.gov (United States)

    Chang, Xiao; Xue, Qingzhong; Li, Xiaofang; Zhang, Jianqiang; Zhu, Lei; He, Daliang; Zheng, Haixia; Lu, Shuangfang; Liu, Zilong

    2018-03-01

    Investigating the inherent wettability of rock surfaces at nanoscale is of great importance in ore floatation and oil recovery field. Using molecular dynamics simulations, we systematically study the wetting behavior of water on different rock surfaces (silica, calcite, gypsum, halite and graphite) at nanoscale. It is demonstrated that the inherent rock wettability follows the order of gypsum > calcite > halite > silica > graphite. Remarkably, we also manifest that the polarity of oil molecules can affect the water contact angles on silica surface. For example, the water contact angles on silica surface in hexane, dodecane, thiophene and toluene are 58 ± 2°, 63 ± 3°, 90 ± 1°, 118 ± 1°, respectively. Furthermore, we investigate the wetting behavior of water on heterogeneous rock surfaces and find that water molecules can move from hydrophobic surface to hydrophilic surface.

  2. Observation on Surface Change of Fragile Glass: Temperature - Time Dependence Studied by X-Ray Reflectivity

    International Nuclear Information System (INIS)

    Kikkawa, Hiroyuki; Kitahara, Amane; Takahashi, Isao

    2004-01-01

    The structural change of a fragile glass surface close to the glass transition temperature Tg is studied by using X-ray reflectivity. Measurements were performed on surfaces of maltitol, which is a typical polyalcohol fragile glass with Tg = 320K. Upon both heating and cooling, we find the following features which are also noticed in silicate glass surfaces: (i) On heating, the surface morphology indicates a variation at temperatures below Tg; (ii) A drastic increase in surface roughness occurs at a temperature about 333K on heating, which is 13K higher than Tg; (iii) During the cooling of the sample, formation of a low-density surface layer (3nm at 293K) is observed. Prior to the crystallization, nm - μm sized domains were grown at the surface, which might not be reported for other glasses

  3. Collisions of ideal gas molecules with a rough/fractal surface. A computational study.

    Science.gov (United States)

    Panczyk, Tomasz

    2007-02-01

    The frequency of collisions of ideal gas molecules (argon) with a rough surface has been studied. The rough/fractal surface was created using random deposition technique. By applying various depositions, the roughness of the surface was controlled and, as a measure of the irregularity, the fractal dimensions of the surfaces were determined. The surfaces were next immersed in argon (under pressures 2 x 10(3) to 2 x 10(5) Pa) and the numbers of collisions with these surfaces were counted. The calculations were carried out using a simplified molecular dynamics simulation technique (only hard core repulsions were assumed). As a result, it was stated that the frequency of collisions is a linear function of pressure for all fractal dimensions studied (D = 2, ..., 2.5). The frequency per unit pressure is quite complex function of the fractal dimension; however, the changes of that frequency with the fractal dimension are not strong. It was found that the frequency of collisions is controlled by the number of weakly folded sites on the surfaces and there is some mapping between the shape of adsorption energy distribution functions and this number of weakly folded sites. The results for the rough/fractal surfaces were compared with the prediction given by the Langmuir-Hertz equation (valid for smooth surface), generally the departure from the Langmuir-Hertz equation is not higher than 48% for the studied systems (i.e. for the surfaces created using the random deposition technique).

  4. Properties and cleanability of new and traditional surface materials in cattle barns - a field study

    Directory of Open Access Journals (Sweden)

    R. KUISMA

    2008-12-01

    Full Text Available In this study surface properties and cleanability of new and traditional surface materials in cattle barns were examined in a field test. The concrete and plastic-coated samples were placed on a walking path on the floor and on a feeding table in a cattle barn. The surfaces were characterized using colorimetric and gloss measurements and determination of topography. In most cases, the colour of the surfaces placed on the floor darkened during the one year study period, whereas the colour changes of the samples placed on the feeding table did not show a similar trend. However, in both locations the plastic-coated surfaces were generally the easiest to clean, and the highest colour changes indicating soil residues were detected on the uncoated and silane-impregnated concrete surfaces. The difference between the locations was also seen in the gloss values, which increased in the samples placed on the floor during the one-year test period but varied considerably between the different materials on the surfaces placed on the feeding table. This field study confirmed the observation from earlier laboratory studies that plastic coatings improved the cleanability of concrete cattle barn surfaces. Silane impregnation was not functionally competitive with the plastic coatings. In general, the cleanability results were in accordance with the results of previous laboratory experiments but the field study provided practical information about the behaviour of the surface materials examined.;

  5. Conformation of bovine submaxillary mucin layers on hydrophobic surface as studied by biomolecular probes

    DEFF Research Database (Denmark)

    Pakkanen, Kirsi I.; Madsen, Jan Busk; Lee, Seunghwan

    2015-01-01

    non-linear responses with increasing surface concentration. The results from this study support the conventional amphiphilic, triblock model of BSM in the adsorption onto hydrophobic surface from aqueous solution.The biomolecular probe-based approaches employed in this study, however, provided further...

  6. Studies on a surface acoustic wave (SAW) dosimeter sensor for organophosphorous nerve agents

    NARCIS (Netherlands)

    Nieuwenhuizen, M.S.; Harteveld, J.L.N.

    1997-01-01

    As a follow-up of previous work on a Surface Acoustic Wave (SAW) sensor for nerve agents, irreversible response effects have been studied in more detail. Surface analytical studies indicated that degradation products are responsible for the effects observed. In addition it was tried to explore these

  7. Study of plasma formation in CW CO2 laser beam-metal surface interaction

    Science.gov (United States)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

    1994-04-01

    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  8. Experimental study on soluble chemical transfer to surface runoff from soil.

    Science.gov (United States)

    Tong, Juxiu; Yang, Jinzhong; Hu, Bill X; Sun, Huaiwei

    2016-10-01

    Prevention of chemical transfer from soil to surface runoff, under condition of irrigation and subsurface drainage, would improve surface water quality. In this paper, a series of laboratory experiments were conducted to assess the effects of various soil and hydraulic factors on chemical transfer from soil to surface runoff. The factors include maximum depth of ponding water on soil surface, initial volumetric water content of soil, depth of soil with low porosity, type or texture of soil and condition of drainage. In the experiments, two soils, sand and loam, mixed with different quantities of soluble KCl were filled in the sandboxes and prepared under different initial saturated conditions. Simulated rainfall induced surface runoff are operated in the soils, and various ponding water depths on soil surface are simulated. Flow rates and KCl concentration of surface runoff are measured during the experiments. The following conclusions are made from the study results: (1) KCl concentration in surface runoff water would decrease with the increase of the maximum depth of ponding water on soil surface; (2) KCl concentration in surface runoff water would increase with the increase of initial volumetric water content in the soil; (3) smaller depth of soil with less porosity or deeper depth of soil with larger porosity leads to less KCl transfer to surface runoff; (4) the soil with finer texture, such as loam, could keep more fertilizer in soil, which will result in more KCl concentration in surface runoff; and (5) good subsurface drainage condition will increase the infiltration and drainage rates during rainfall event and will decrease KCl concentration in surface runoff. Therefore, it is necessary to reuse drained fertile water effectively during rainfall, without polluting groundwater. These study results should be considered in agriculture management to reduce soluble chemical transfer from soil to surface runoff for reducing non-point sources pollution.

  9. Collaborative Research: Fundamental studies of plasma control using surface embedded electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Raja, Laxminarayan L. [Univ. of Texas, Austin, TX (United States); PanneerChelvam, PremKumar [Univ. of Texas, Austin, TX (United States); Levko, Dimtry [Univ. of Texas, Austin, TX (United States)

    2016-02-26

    The proposed study will investigate the effect of active electron injection of from electrode surfaces To the best of our knowledge, no such a study has ever been attempted even though it could lead to the formation of whole new classes of plasma based devices and systems. We are motivated by recent articles and simple theory which gives strong reason to believe that embedded electronic devices can be used to exert control over the SEE coefficient of semiconductor surfaces (and maybe other surface types as well). Furthermore, the research will explore how such sub-surface electronic devices can best be used to exert control over an associated plasma.

  10. Ammonia synthesis over a Ru(0001) surface studied by density functional calculations

    DEFF Research Database (Denmark)

    Logadottir, Ashildur; Nørskov, Jens Kehlet

    2003-01-01

    In this paper we present DFT studies of all the elementary steps in the synthesis of ammonia from gaseous hydrogen and nitrogen over a ruthenium crystal. The stability and configurations of intermediates in the ammonia synthesis over a Ru(0001) surface have been investigated, both over a flat...... surface and over a stepped surface. The calculations show that the step sites on the surface are much more reactive than the terrace sites. The DFT results are then used to study the mechanism of promotion by alkalies over the Ru(0001) and to determine the rate-determining step in the synthesis of ammonia...

  11. Road failure caused by landslide in north Ethiopia: A case study from Dedebit - Adi-Remets road segment

    Science.gov (United States)

    Fisseha, Shimeles; Mewa, Getnet

    2016-06-01

    Landslide represents one of the main constraints for the development of road infrastructures in many parts of Ethiopia. While rugged topography, intra-sedimentary clay horizons, thick talus deposits at the foot of hills and wide spread tectonic fissures and faults account for the prominent inducing factors, heavy monsoon rainfall is the most common triggering factor for the majority of road failures caused by landslides. We present the results of geoelectrical investigation of a landslide that caused a severe damage to the Dedebit-Adi-Remets segment of the recently built highway that transects the high relief and mountainous region of Tigray, northern Ethiopia. Vertical Electrical Sounding (VES) measurements were taken at twelve points, systematically distributed to cover the affected area. The resulting geo-electric sections revealed that the shallow subsurface is composed of four distinct geo-electric layers. The corresponding major lithological successions, from top to bottom, are: unconsolidated conglomeratic layer, moist silty clay, moderately weathered and fractured basaltic rock and a possibly saturated portion of the basalt. Major discontinuities, indications of structural weak zones, have also been inferred based on abrupt vertical shift in geo-electrical layer boundaries between neighboring soundings. Based on the main findings, the road failure in the study area appears to be caused by a downslope movement of the subgrade composed of top unconsolidated sediment soaked with water from heavy rain. The location of the probable slip plane could be the inclined interface between the conductive clayey soil and the underlying resistive weathered basalt.

  12. Experimental study of curvature effects on jet impingement heat transfer on concave surfaces

    Directory of Open Access Journals (Sweden)

    Ying Zhou

    2017-04-01

    Full Text Available Experimental study of the local and average heat transfer characteristics of a single round jet impinging on the concave surfaces was conducted in this work to gain in-depth knowledge of the curvature effects. The experiments were conducted by employing a piccolo tube with one single jet hole over a wide range of parameters: jet Reynolds number from 27000 to 130000, relative nozzle to surface distance from 3.3 to 30, and relative surface curvature from 0.005 to 0.030. Experimental results indicate that the surface curvature has opposite effects on heat transfer characteristics. On one hand, an increase of relative nozzle to surface distance (increasing jet diameter in fact enhances the average heat transfer around the surface for the same curved surface. On the other hand, the average Nusselt number decreases as relative nozzle to surface distance increases for a fixed jet diameter. Finally, experimental data-based correlations of the average Nusselt number over the curved surface were obtained with consideration of surface curvature effect. This work contributes to a better understanding of the curvature effects on heat transfer of a round jet impingement on concave surfaces, which is of high importance to the design of the aircraft anti-icing system.

  13. Experimental study of water droplets on over-heated nano/microstructured zirconium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seol Ha [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Ahn, Ho Seon [Division of Mechanical System Engineering, Incheon National University, 406-772 (Korea, Republic of); Kim, Joonwon [Department of Mechanical Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Kim, Moo Hwan [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of); Park, Hyun Sun, E-mail: hejsunny@postech.ac.kr [Division of Advanced Nuclear Engineering, POSTECH, Pohang 790-784 (Korea, Republic of)

    2014-10-15

    Highlights: • Heat transfer performance of a droplet on a modified zirconium surface is evaluated. • Modified (nano/micro-) surfaces enhanced heat transfer rate and Leidenfrost point. • A highly wettable condition of the modified surface contributes the enhancement. • Nano-scaled modification indicates the higher performance of droplet cooling. • Investigation via visualization of the droplet support the heat transfer experimental data. - Abstract: In this study, we observed the behavior of water droplets near the Leidenfrost point (LFP) on zirconium alloy surfaces with anodizing treatment and investigated the droplet cooling performance. The anodized zirconium surface, which consists of bundles of nanotubes (∼10–100 nm) or micro-mountain-like structures, improved the wetting characteristics of the surface. A deionized water droplet (6 μL) was dropped onto test surfaces heated to temperatures ranging from 250 °C to the LFP. The droplet dynamics were investigated through high-speed visualization, and the cooling performance was discussed in terms of the droplet evaporation time. The modified surface provided vigorous, intensive nucleate boiling in comparison with a clean, bare surface. Additionally, we observed that the structured surface had a delayed LFP due to the high wetting condition induced by strong capillary wicking forces on the structured surface.

  14. Parameterization of rain induced surface roughness and its validation study using a third generation wave model

    Science.gov (United States)

    Rajesh Kumar, R.; Prasad Kumar, B.; Bala Subrahamanyam, D.

    2009-09-01

    The effect of raindrops striking water surface and their role in modifying the prevailing sea-surface roughness is investigated. The work presents a new theoretical formulation developed to study rain-induced stress on sea-surface based on dimensional analysis. Rain parameters include drop size, rain intensity and rain duration. The influences of these rain parameters on young and mature waves were studied separately under varying wind speeds, rain intensity and rain duration. Contrary to popular belief that rain only attenuates surface waves, this study also points out rain duration under certain condition can contribute to wave growth at high wind speeds. Strong winds in conjunction with high rain intensity enhance the horizontal stress component on the sea-surface, leading to wave growth. Previous studies based on laboratory experiments and dimensional analysis do not account for rain duration when attempting to parameterize sea-surface roughness. This study signifies the importance of rain duration as an important parameter modifying sea-surface roughness. Qualitative as well quantitative support for the developed formulation is established through critical validation with reports of several researchers and satellite measurements for an extreme cyclonic event in the Indian Ocean. Based on skill assessment, it is suggested that the present formulation is superior to prior studies. Numerical experiments and validation performed by incorporating in state-of-art WAM wave model show the importance of treating rain-induced surface roughness as an essential pre-requisite for ocean wave modeling studies.

  15. Major Successes of Theory-and-Experiment-Combined Studies in Surface Chemistry and Heterogeneous Catalysis.

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, Gabor A.; Li, Yimin

    2009-11-21

    Experimental discoveries followed by theoretical interpretations that pave the way of further advances by experimentalists is a developing pattern in modern surface chemistry and catalysis. The revolution of modern surface science started with the development of surface-sensitive techniques such as LEED, XPS, AES, ISS and SIMS, in which the close collaboration between experimentalists and theorists led to the quantitative determination of surface structure and composition. The experimental discovery of the chemical activity of surface defects and the trends in the reactivity of transitional metals followed by the explanations from the theoretical studies led to the molecular level understanding of active sites in catalysis. The molecular level knowledge, in turn, provided a guide for experiments to search for new generation of catalysts. These and many other examples of successes in experiment-and-theory-combined studies demonstrate the importance of the collaboration between experimentalists and theorists in the development of modern surface science.

  16. The surface of 1-euro coins studied by X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Gou, F.; Gleeson, M.A.; Villette, J.; Kleyn, S.E.F.; Kleyn, A.W.

    2004-01-01

    The two alloy surfaces (pill and ring) that are present on 1-euro coins have been studied by X-ray photoelectron spectroscopy (XPS). Comparison is made between coins from general circulation and coin surfaces that have been subjected to a variety of cleaning and oxidation treatments. The concentrations and possible oxidation states of the metals (nickel, copper and zinc) at the surface were derived from analysis of the 2p 3/2 core levels. The surface atomic ratios measured for the pill and the ring parts of the euro coins were compared to the official bulk ratios. This study shows a clear nickel enrichment of both pill and ring surfaces. Nickel at surface seems to be present mainly in hydroxide form although the chloride form cannot be excluded. A small concentration of zinc was present on the surface of the pill, even though it is not present in the bulk alloy. Evidence of both nickel and zinc surface enrichment is observed for the ring. No surface enrichment is observed for the atomically clean or oxidized alloy surfaces over a 60-h time scale

  17. Study of land surface temperature and spectral emissivity using multi ...

    Indian Academy of Sciences (India)

    LST) and spectral emissivities over a hard rock terrain using multi-sensor satellite data. The study area, of about 6000 km2, is a part of Singhbhum–Orissa craton situated in the eastern part of India. TIR data from ASTER, MODIS and Landsat ...

  18. Study of the local structure of binary surfaces by electron diffraction (XPS, LEED)

    OpenAIRE

    Gereová, Katarína

    2006-01-01

    Study of local structure of binary surface with usage of ultra-thin film of cerium deposited on a Pd (111) single-crystal surface is presented. X-ray photoelectron spectroscopy and diffraction (XPS, XPD), angle resolved UV photoemission spectroscopy (ARUPS) and low energy electron diffraction (LEED) was used for our investigations. LEED and X-ray excited photoemission intensities results represent a surface-geometrical structure. As well, mapping of ultra-violet photoelectron intensities as a...

  19. Infrared Surface-Plasmon-Resonance -- a novel biophysical tool for studying living cell

    OpenAIRE

    Golosovsky, M.; Lirtsman, V.; Yashunsky, V.; Davidov, D.; Aroeti, B.

    2009-01-01

    We discuss the Surface-Plasmon-Resonance (SPR) technique based on Fourier -Transform - InfraRed (FTIR) spectrometry. We explore the potential of the infrared surface plasmon resonance technique for biological studies in aqueous solutions and compare it to the conventional surface plasmon technique operating in the visible range. We demonstrate that the sensitivity of the SPR technique in the infrared range is not lower and in fact is even higher. We show several examples of applying FTIR-SPR ...

  20. First principles study of dissolved oxygen water adsorption on Fe (001 surfaces

    Directory of Open Access Journals (Sweden)

    Dong ZHANG

    2018-02-01

    Full Text Available In order to study the mechanism of dissolved oxygen content on the surface corrosion behavior of Fe-based heat transfer, the first principle is used to study the adsorption of O2 monomolecular, H2O monolayer and dissolved oxygen system on Fe-based heat transfer surface. The GGA/PBE approximation is used to calculate the adsorption energy, state density and population change during the adsorption process. Calculations prove that when the dissolved oxygen is adsorbed on the Fe-based surface, the water molecule tends to adsorb at the top sites, and the oxygen molecule tends to adsorb at Griffiths. When the H2O molecule adsorbs and interacts on the Fe (001 surface, the charge distribution of the interfacial double electric layer changes to cause the Fe atoms to lose electrons, resulting in the change of the surface potential. When the O2 molecule adsorbs on the Fe (001 crystal surfaces, the electrons on the Fe (001 surface are lost and the surface potential increases. O2 molecule and the surface of the Fe atoms are prone to electron transfer, in which O atom's 2p orbit for the adsorption of O2 molecule on Fe (001 crystal surface play a major role. With the increase of the proportion of O2 molecule in the dissolved oxygen water, the absolute value of the adsorption energy increases, and the interaction of the Fe-based heat transfer surface is stronger. This study explores the influence law of different dissolved oxygen on the Fe base heat exchange surface corrosion, and the base metal corrosion mechanism for experimental study provides a theoretical reference.

  1. Plaque formation on surface modified dental implants. An in vitro study.

    Science.gov (United States)

    Grössner-Schreiber, B; Griepentrog, M; Haustein, I; Müller, W D; Lange, K P; Briedigkeit, H; Göbel, U B

    2001-12-01

    Bacterial adhesion on titanium implant surfaces has a strong influence on healing and long-term outcome of dental implants. Parameters like surface roughness and chemical composition of the implant surface were found to have a significant impact on plaque formation. The purpose of this study was to evaluate the influence of two physical hard coatings on bacterial adhesion in comparison with control surfaces of equivalent roughness. Two members of the oral microflora, Streptococcus mutans and Streptococcus sanguis were used. Commercially pure titanium discs were modified using four different surface treatments: physical vapour deposition (PVD) with either titanium nitride (TiN) or zirconium nitride (ZrN), thermal oxidation and structuring with laser radiation. Polished titanium surfaces were used as controls. Surface topography was examined by SEM and estimation of surface roughness was done using a contact stylus profilometer. Contact angle measurements were carried out to calculate surface energy. Titanium discs were incubated in the respective bacterial cell suspension for one hour and single colonies formed by adhering bacteria were counted by fluorescence microscopy. Contact angle measurements showed no significant differences between the surface modifications. The surface roughness (Ra) of all surfaces examined was between 0.14 and 1.00 microm. A significant reduction of the number of adherent bacteria was observed on inherently stable titanium hard materials such as TiN and ZrN and thermically oxidated titanium surfaces compared to polished titanium. In conclusion, physical modification of titanium implant surfaces such as coating with TiN or ZrN may reduce bacterial adherence and hence improve clinical results.

  2. Analytic study of a rolling sphere on a rough surface

    Directory of Open Access Journals (Sweden)

    Olivia A. Florea

    2016-11-01

    Full Text Available In this paper it is realized an analytic study of the rolling’s sphere on a rough horizontal plane under the action of its own gravity. The necessities of integration of the system of dynamical equations of motion lead us to find a reference system where the motion equations should be transformed into simpler expressions and which, in the presence of some significant hypothesis to permit the application of some original methods of analytical integration. In technical applications, the bodies may have a free rolling motion or a motion constrained by geometrical relations in assemblies of parts and machine parts. This study involves a lot of investigations in the field of tribology and of applied dynamics accompanied by experiments. Multiple recordings of several trajectories of the sphere, as well as their treatment of images, also followed by statistical processing experimental data allowed highlighting a very good agreement between the theoretical findings and experimental results.

  3. Duoplasmatron with the Wien filter for study on solid surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pivovarov, A.L.; Chenakin, S.P.; Cherepin, V.T.; Zaporozhets, I.A. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)

    A compact system consisting of a cold cathode duoplasmatron and the Wien filter as a mass-separator has been described. The system operation when leak in of Ar, He, O/sub 2/ and H/sub 2/ depending on ion energy and gas pressure is studied. The possibility to obtain mono-, two-charge and polyatom ions of working gas is shown, mass evolution of the Wien filter is approximately 20, transmission -0.3.

  4. Neuromuscular functions in sportsmen and fibromyalgia patients : a surface EMG study in static and dynamic conditions

    NARCIS (Netherlands)

    Klaver-Krol, E.G.

    2012-01-01

    This thesis presents two studies, one involving sportsmen (sprinters versus endurance athletes) and one fibromyalgia patients (patients versus healthy controls). The studies have investigated muscular functions using a non-invasive method: surface electromyography (sEMG). In the sportsmen,

  5. Sea surface temperature variability over North Indian Ocean - A study of two contrasting monsoon seasons

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Sathyendranath, S.; Viswambharan, N.K.; Rao, L.V.G.

    Using the satellite derived sea surface temperature (SST) data for 1979 (bad monsoon) and 1983 (good monsoon), the SST variability for two contrasting monsoon seasons is studied. The study indicates that large negative anomalies off the Somali...

  6. Contribution of hydrochemical and geoelectrical approaches to investigate salinization process and seawater intrusion in the coastal aquifers of Chaouia, Morocco.

    Science.gov (United States)

    Najib, Saliha; Fadili, Ahmed; Mehdi, Khalid; Riss, Joëlle; Makan, Abdelhadi

    2017-03-01

    This study aims to identify groundwater salinization origin and to determine seawater intrusion extension toward the inland in Chaouia, Morocco. To reach these objectives, firstly, 46 groundwater samples were analyzed for major chemical elements during January 2012 and, secondly, 10 electrical resistivity tomography (ERT) profiles were performed perpendicularly to the coastal fringe. Statistical analysis provided the distinction between three Clusters reflecting different hydrochemical processes. Cluster I and Cluster II-a showed a high water electrical conductivity (EC) (from 2.3 to 11.2mS/cm) with the dominance of Na + (668mg/L on average) and Cl - (1735mg/L on average) ions as a consequence of seawater intrusion. However, Cluster II-b presented low ECs (from 0.5 to 1.7mS/cm) and Ca 2+ (99.6mg/L on average) and HCO 3 2- (235.2mg/L on average) ions dominance. Water chemistry in these wells was controlled by water-rock interaction, cation exchange, and anthropogenic activities. The Hydrochemical Facies Evolution Diagram highlighted the succession of different water facies developed between intrusion and freshening phases. The formation of Na-HCO 3 facies, which characterizes the last facies of freshening phase, followed the succession of Na-Cl, MixNa-MixCl, MixCa-MixCl, MixCa-MixHCO 3 , and Na-HCO 3 . In contrast, Na-Cl facies formation, which characterizes the last facies of intrusion phase, followed the evolution of Ca-HCO 3 , Ca-MixHCO 3 , Ca-MixCl, MixCa-MixCl, MixCa-Cl, and Na-Cl. Moreover, the obtained ERT results allowed determining the extent of different hydrochemical facies and provided more details about seawater intrusion extension. The conductive level assigned to seawater contamination showed a resistivity less than 36Ω.m, which remains limited to 3000m from the ocean, where Na-Cl water type dominates. The seawater intrusion depth varied between 5 and 40m from the surface. Overall, this original study in Chaouia region demonstrated the effectiveness

  7. Computational Study of Droplet Trains Impacting a Smooth Solid Surface

    Science.gov (United States)

    Markt, David, Jr.; Pathak, Ashish; Raessi, Mehdi; Lee, Seong-Young; Zhao, Emma

    2017-11-01

    The study of droplet impingement is vital to understanding the fluid dynamics of fuel injection in modern internal combustion engines. One widely accepted model was proposed by Yarin and Weiss (JFM, 1995), developed from experiments of single trains of ethanol droplets impacting a substrate. The model predicts the onset of splashing and the mass ejected upon splashing. In this study, using an in-house 3D multiphase flow solver, the experiments of Yarin and Weiss were computationally simulated. The experimentally observed splashing threshold was captured by the simulations, thus validating the solver's ability to accurately simulate the splashing dynamics. Then, we performed simulations of cases with multiple droplet trains, which have high relevance to dense fuel sprays, where droplets impact within the spreading diameters of their neighboring droplets, leading to changes in splashing dynamics due to interactions of spreading films. For both single and multi-train simulations the amount of splashed mass was calculated as a function of time, allowing a quantitative comparison between the two cases. Furthermore, using a passive scalar the amount of splashed mass per impinging droplet was also calculated. This work is supported by the Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) and the Department of Defense, Tank and Automotive Research, Development, and Engineering Center (TARDEC), under Award Number DE-EE0007292.

  8. A Summary of NASA Architecture Studies Utilizing Fission Surface Power Technology

    Science.gov (United States)

    Mason, Lee S.; Poston, David I.

    2011-01-01

    Beginning with the Exploration Systems Architecture Study in 2005, NASA has conducted various mission architecture studies to evaluate implementation options for the U.S. Space Policy. Several of the studies examined the use of Fission Surface Power (FSP) systems for human missions to the lunar and Martian surface. This paper summarizes the FSP concepts developed under four different NASA-sponsored architecture studies: Lunar Architecture Team, Mars Architecture Team, Lunar Surface Systems/Constellation Architecture Team, and International Architecture Working Group-Power Function Team.

  9. Beam waist position study for surface modification of polymethyl-methacrylate with femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Caballero-Lucas, F.; Florian, C.; Fernández-Pradas, J.M., E-mail: jmfernandez@ub.edu; Morenza, J.L.; Serra, P.

    2016-06-30

    Highlights: • Surface modification of PMMA with femtosecond laser pulses. • Z-scan reflectance and transmittance study for controlling the sample surface position in the laser beam waist. • Surface modifications with dimensions in the nanometric scale with a 1027 nm wavelength laser. • Extended range of some microns for placing the sample and precise determination of the beam waist position. - Abstract: Femtosecond lasers are versatile tools to process transparent materials. This optical property poses an issue for surface modification. In this case, laser radiation would not be absorbed at the surface unless the beam is just focused there. Otherwise, absorption would take place in the bulk leaving the surface unperturbed. Therefore, strategies to position the material surface at the laser beam waist with high accuracy are essential. We investigated and compared two options to achieve this aim: the use of reflectance data and transmittance measurements across the sample, both obtained during z-scans with pulses from a 1027 nm wavelength laser and 450 fs pulse duration. As the material enters the beam waist region, a reflectance peak is detected while a transmittance drop is observed. With these observations, it is possible to control the position of the sample surface with respect to the beam waist with high resolution and attain pure surface modification. In the case of polymethyl-methacrylate (PMMA), this resolution is 0.6 μm. The results prove that these methods are feasible for submicrometric processing of the surface.

  10. Experimental study on surface properties of the PMMA used in high power spark gaps

    Science.gov (United States)

    Han, Ruoyu; Wu, Jiawei; Ding, Weidong; Liu, Yunfei; Gou, Yang

    2017-10-01

    This paper studies the surface properties of the Polymethylmethacrylate (PMMA) insulator samples used in high power spark gaps. Experiments on surface morphology, surface profile, surface chemical composition and surface leakage current were performed. Metal particles ejected in tangent direction of discharge spots were researched on the sample surface. Three kinds of distinct bands were found on the surface after 1500 shots: colorless and transparent sinking band, black band, and grey powdered coating band. The thickness of the coating band was tens of microns and the maximum radial erosion rate was about 10 μm/C. Surface content analysis indicated that the powdered coating was a mixture of decomposed insulator material and electrode material oxides. In addition, leakage current significantly depended on water content in the chamber and presented an U-shape curve distribution along the insulator surface, in keeping with the amount of powdered coating due to shock waves. Possible reasons of the surface property changes were discussed. Electroconductive oxides of low valence states of Cu and W produced by the reactions between electrode materials and arc plasmas were considered to be the cause of dielectric performance degradation.

  11. DFT study on the interaction of TiO2 (001) surface with HCHO molecules

    Science.gov (United States)

    Wu, Guofei; Zhao, Cuihua; Guo, Changqing; Chen, Jianhua; Zhang, Yibing; Li, Yuqiong

    2018-01-01

    The interactions of formaldehyde (HCHO) molecule with TiO2 (001) surface were studied using density functional theory calculations. HCHO molecules are dissociated by the cleavage of Csbnd H bonds after adsorption on TiO2 surface. The strong interactions between HCHO melecules and TiO2 surface are largely attributed to the bonding of hydrogen of HCHO and oxygen of TiO2 surface, which is mainly from the hybridization of the H 1s, O 2p and O 2s. The newly formed Hsbnd O bonds cause the structure changes of TiO2 surface, and lead to the cleavage of Osbnd Ti bond of TiO2 surface. The Csbnd O bond that the dissociated remains of HCHO and newly formed Hsbnd O bond can be oxidized to form carbon dioxide and water in subsequent action by oxygen from the atomosphere. The charges transfer from HCHO to TiO2 surface, and the sum amount of the charges transferred from four HCHO molecules to TiO2 surface is bigger than that from one HCHO molecule to TiO2 surface due to the combined interaction of four HCHO molecules with TiO2 surface.

  12. Design Methodology And Performance Studies Of A Flexible Electrotextile Surface

    Directory of Open Access Journals (Sweden)

    Kayacan Ozan

    2015-09-01

    Full Text Available ‘The smart textiles’ concept has to develop products based not only on design, fashion and comfort but also in terms of functions. The novel electro-textiles in the market open up new trends in smart and interactive gadgets. ‘Easy to care and durability’ properties are among the most important features of these products. On the other hand, wearable electronic knitwear has been gaining the attention of both researchers and industrial sectors. Combining knitting technology with electronics may become a dominant trend in the future because of the wide application possibilities. This research is concerned primarily with the design methodology of knitted fabrics containing electrically conductive textiles and especially in-use performance studies. The structural characteristics of the fabrics have been evaluated to enhance the performance properties.

  13. Study on surface geochemistry and microbiology for hydrocarbon exploration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-01

    The test results of the experimental device for extraction of dissolved gases from water show that the device can be utilized for the gas geochemistry of water. The device is capable of determining hydrocarbon gases in water to the concentration of less than 5 x 10{sup -4} ml/l of water. According to the results of microbiological studies, the plate count technique can be a useful supplementary method for hydrocarbon exploration. This is based on the facts that the average survival rate to hydrocarbons (pentane, hexane) for heterotrophs is higher in the area known as containing considerable hydrocarbon gases than other areas in the Pohang region. However, it is still necessary to develop techniques to treat the bacteria with gaseous hydrocarbons. (author). 2 figs., 41 tabs.

  14. XPS study on the surface reaction of uranium metal with carbon monoxide at 200 degree C

    International Nuclear Information System (INIS)

    Wang Xiaoling; Fu Yibei; Xie Renshou; Huang Ruiliang

    1996-12-01

    The surface reaction of uranium metal with carbon monoxide at 200 degree C has been studied by X-ray photoelectron spectroscopy (XPS). The carbon monoxide adsorption on the surface oxide layer resulted in U4f peak shifting to the lower binding energy and the content of oxygen in the oxide is decreased. O/U radio decreases with increasing the exposure of carbon monoxide to the surface layer. The investigation indicated the surface layer of uranium metal was further reduced in the atmosphere of carbon monoxide at high temperature. (3 refs., 5 figs.)

  15. Atomic scale studies of interface formation between oxides and III-V semiconductor surfaces

    OpenAIRE

    Clemens, Jonathon Boyd

    2010-01-01

    The surface reconstructions of InAs(0 0 1)-(4 x 2) and In₀.₅₃Ga₀.₄₇As(0 0 1)-(4 x 2) were investigated at 300 K and 80 K. At 300 K, the surfaces reconstruct to form the group III rich [beta]3'(4 x 2) reconstructions and at 80 K, the surfaces reconstruct to form the [beta]3'(4 x 4) reconstruction. A novel hybridization scheme is required for these reconstructions. Oxidation of the InAs(0 0 1)-(4 x 2) surface by O₂ was studied and it was determined that this occurs via an autocatalytic process,...

  16. Optical properties and surface morphology studies of palladium contacts on mercuric iodide single crystals

    Energy Technology Data Exchange (ETDEWEB)

    George, M.A.; Azoulay, M.; Burger, A.; Biao, Y.; Silberman, E. [Fisk Univ., Nashville, TN (United States). Dept. of Physics; Nason, D. [EG and G Energy Measurements, Inc., Goleta, CA (United States). Santa Barbara Operations

    1993-05-01

    Palladium is chemically suitable for electric contacts on mercuric iodide detectors for photon and nuclear radiation detection, so the understanding of palladium contacts is important for fundamental and practical scientific purposes. A study has been conducted on the surface morphology of evaporated contacts using Atomic Force Microscopy (AFM) and optical transmission and reflection. Evaporated palladium coatings are typically nonuniform and may deposit selectively on mercuric iodide surface defects. Reflection measurements show that coating thickness and surface treatment affect intensity, position and shape of a reflected peak characteristic of the mercuric iodide structure. Results indicate that the band gap energy in the surface of the mercuric iodide is lowered by palladium contacts.

  17. Assessment of the wastewater effect on the shallow subsurface soil at Farafra Oasis, Egypt, by using geoelectrical and geochemical data analysis

    Directory of Open Access Journals (Sweden)

    Mahmoud Ismail Ismail Mohamaden

    2016-12-01

    The second layer reveals moderate electrical resistivity values (17–98 Ω m. It is extended from the surface layer to the end of the investigated section and represents the Sandstone (upper aquifer in the study area.

  18. A computational chemical study of penetration and displacement of water films near mineral surfaces

    Directory of Open Access Journals (Sweden)

    Larter Steve R

    2001-08-01

    Full Text Available A series of molecular dynamics simulations have been performed on organic–water mixtures near mineral surfaces. These simulations show that, in contrast to apolar compounds, small polar organic compounds such as phenols can penetrate through thin water films to adsorb on these mineral surfaces. Furthermore, additional simulations involving demixing of an organic–water mixture near a surfactant-covered mineral surface demonstrate that even low concentrations of adsorbed polar compounds can induce major changes in mineral surface wettability, allowing sorption of apolar molecules. This strongly supports a two-stage adsorption mechanism for organic solutes, involving initial migration of small polar organic molecules to the mineral surface followed by water film displacement due to co-adsorption of the more apolar organic compounds, thus converting an initial water-wet mineral system to an organic-covered surface. This has profound implications for studies of petroleum reservoir diagenesis and wettability changes.

  19. Influence of graphite particles on surface roughness and chip formation studies in turning metal matrix composites

    Directory of Open Access Journals (Sweden)

    S. Basavarajappa

    2013-01-01

    Full Text Available This study presents an experimental investigation on surface roughness and chip formation in turning of Al 2219/15SiCp and Al 2219/15SiCp-3Gr (hybrid composites. Experiments were conducted with different cutting conditions using carbide, coated carbide and polycrystalline diamond (PCD tools. The results reveal that the surface roughness values are less for coated carbide tools compared to carbide and are minimum for PCD tools. The incorporation of graphite in Al 2219/15SiCp composite increases the surface roughness. This is due to smearing and removal of softer and amorphus graphite particles on the surface of the specimen, creates pits on the machined surface which increases the surface roughness values. The graphitic composite produced discontinuous chips leads to easy machining. PCD tool performs better than carbide and coated carbide tools.

  20. Studies of the surface of titanium dioxide. IV. The hydrogen-deuterium equilibration reaction

    International Nuclear Information System (INIS)

    Iwaki, T.; Katsuta, K.; Miura, M.

    1981-01-01

    The interaction of hydrogen with the surface of titanium dioxide has been studied in connection with the hydrogen-reduction mechanism of titanium dioxide, by means of such measurements as weight decrease, magnetic susceptibility, hydrogen uptake, and electrical conductance. It was postulated in the previous study that the rate-determining step of the hydrogen-reduction reaction may be the formation of surface hydroxyl groups, followed by the rapid removal of water molecules from the surface. In this study, the interactions between hydrogen and the surface of titanium dioxide were investigated by measuring the hydrogen-deuterium equilibration reaction, H 2 + D 2 = 2HD, at temperatures above 200 0 C on both surfaces before and after hydrogen reduction to compare the differences in the reactivities

  1. Design, development and applications of novel techniques for studying surface mechanical properties

    Science.gov (United States)

    Miyoshi, Kazuhisa

    1989-01-01

    Research is reviewed for the adhesion, friction, and micromechanical properties of materials and examples of the results presented. The ceramic and metallic materials studied include silicon carbide, aluminum oxide, and iron-base amorphous alloys. The design and operation of a torsion balance adapted for study of adhesion from the Cavendish balance are discussed first. The pull-off force (adhesion) and shear force (friction) required to break the interfacial junctions between contacting surfaces of the materials were examined at various temperatures in a vacuum. The surface chemistry of the materials was analyzed by X-ray photoelectron spectroscopy. Properties and environmental conditions of the surface regions which affect adhesion and friction-such as surface segregation, composition, crystal structure, surface chemistry, and temperature were also studied.

  2. Surface Plasma Arc by Radio-Frequency Control Study (SPARCS)

    International Nuclear Information System (INIS)

    Ruzic, David N.

    2013-01-01

    This paper is to summarize the work carried out between April 2012 and April 2013 for development of an experimental device to simulate interactions of o-normal detrimental events in a tokamak and ICRF antenna. The work was mainly focused on development of a pulsed plasma source using theta pinch and coaxial plasma gun. This device, once completed, will have a possible application as a test stand for high voltage breakdown of an ICRF antenna in extreme events in a tokamak such as edge-localized modes or disruption. Currently, DEVeX does not produce plasma with high temperature enough to requirement for an ELM simulator. However, theta pinch is a good way to produce high temperature ions. The unique characteristic of plasma heating by a theta pinch is advantageous for an ELM simulator due to its effective ion heating. The objective of the proposed work, therefore, is to build a test facility using the existing theta pinch facility in addition to a coaxial plasma gun. It is expected to produce a similar pulsed-plasma heat load to the extreme events in tokamaks and to be applied for studying interactions of hot plasma and ICRF antennas

  3. Experimental Study on Momentum Transfer of Surface Texture in Taylor-Couette Flow

    Science.gov (United States)

    Xue, Yabo; Yao, Zhenqiang; Cheng, De

    2017-05-01

    The behavior of Taylor-Couette (TC) flow has been extensively studied. However, no suitable torque prediction models exist for high-capacity fluid machinery. The Eckhardt-Grossmann-Lohse (EGL) theory, derived based on the Navier-Stokes equations, is proposed to model torque behavior. This theory suggests that surfaces are the significant energy transfer interfaces between cylinders and annular flow. This study mainly focuses on the effects of surface texture on momentum transfer behavior through global torque measurement. First, a power-law torque behavior model is built to reveal the relationship between dimensionless torque and the Taylor number based on the EGL theory. Second, TC flow apparatus is designed and built based on the CNC machine tool to verify the torque behavior model. Third, four surface texture films are tested to check the effects of surface texture on momentum transfer. A stereo microscope and three-dimensional topography instrument are employed to analyze surface morphology. Global torque behavior is measured by rotating a multi component dynamometer, and the effects of surface texture on the annular flow behavior are observed via images obtained using a high-speed camera. Finally, torque behaviors under four different surface conditions are fitted and compared. The experimental results indicate that surface textures have a remarkable influence on torque behavior, and that the peak roughness of surface texture enhances the momentum transfer by strengthening the fluctuation in the TC flow.

  4. Quantitative study of Xanthosoma violaceum leaf surfaces using RIMAPS and variogram techniques.

    Science.gov (United States)

    Favret, Eduardo A; Fuentes, Néstor O; Molina, Ana M

    2006-08-01

    Two new imaging techniques (rotated image with maximum averaged power spectrum (RIMAPS) and variogram) are presented for the study and description of leaf surfaces. Xanthosoma violaceum was analyzed to illustrate the characteristics of both techniques. Both techniques produce a quantitative description of leaf surface topography. RIMAPS combines digitized images rotation with Fourier transform, and it is used to detect patterns orientation and characteristics of surface topography. Variogram relates the mathematical variance of a surface with the area of the sample window observed. It gives the typical scale lengths of the surface patterns. RIMAPS detects the morphological variations of the surface topography pattern between fresh and dried (herbarium) samples of the leaf. The variogram method finds the characteristic dimensions of the leaf microstructure, i.e., cell length, papillae diameter, etc., showing that there are not significant differences between dry and fresh samples. The results obtained show the robustness of RIMAPS and variogram analyses to detect, distinguish, and characterize leaf surfaces, as well as give scale lengths. Both techniques are tools for the biologist to study variations of the leaf surface when different patterns are present. The use of RIMAPS and variogram opens a wide spectrum of possibilities by providing a systematic, quantitative description of the leaf surface topography.

  5. Characterization and flip angle calibration of 13C surface coils for hyperpolarization studies

    DEFF Research Database (Denmark)

    Hansen, Rie Beck; Gutte, Henrik; Larsen, Majbrit M E

    The aim of the present work is to address the challenge of optimal The aim of the present work is to address the challenge of optimal flflip angle calibration of ip angle calibration of C surface coils in C surface coils in hyperpolarization studies. To this end, we characterize the spatial pro h...

  6. External surface adsorption on silicalite-1 zeolite studied by molecular simulation

    NARCIS (Netherlands)

    Garcia-Perez, E.; Schnell, S.K.; Castillo, J.M.; Calero, S.; Kjelstrup, S.; Dubbeldam, D.; Vlugt, T.J.H.

    2011-01-01

    We have studied the adsorption of ethane, propane, and their mixtures on the external surface of silicalite-1 zeolite by molecular simulation using a classical force field. The ideal adsorbed solution theory (IAST) was successfully used to describe mixture adsorption, both on the external surface

  7. An in vitro study of the effect of design of repair surface on the ...

    African Journals Online (AJOL)

    Once denture fractures, we would want the joint surface strength to be as good as original. Purpose: The purpose of this study was to determine the effect of different repair surface design on the transverse strength of repaired acrylic denture resin. Materials and Methods: Sixty specimens of heat‑cured acrylic resin of ...

  8. Ion effects in the adsorption of carboxylate on oxide surfaces, studied with quartz crystal microbalance

    NARCIS (Netherlands)

    Wang, Lei; Sîretanu, Igor; Duits, Michael H.G.; Cohen Stuart, Martinus Abraham; Mugele, Friedrich Gunther

    2016-01-01

    We chose water-soluble sodium hexanoate as a model organic molecule to study the role of salt ions (Ca2+, Na+, Cl−) in the adsorption of carboxylates to mineral surfaces (silica, alumina, gibbsite) of variable surface charge and chemistry. Quartz crystal microbalance (QCM-D) measurements reveal a

  9. The effect of surface structure on Ag atom adsorption over CuO(111) surfaces: A first principles study

    Science.gov (United States)

    Hu, Riming; Zhou, Xiaolong; Yu, Jie

    2017-12-01

    The interactions of Ag atom with different types of CuO(111) surface, including the perfect, oxygen-vacancy and precovered oxygen surfaces, have been systematically investigated using density functional theory (DFT) calculations to examine the effect of surface structures on Ag atom adsorption. The calculated results indicate that the Cu1-Cu1 bridge site and the oxygen-vacancy site are the active centres for atomic Ag adsorption on the perfect surface and the oxygen-vacancy surface respectively, while atomic Ag preferentially adsorbs at the Op site on the precovered oxygen surface. The activity of the CuO(111) surface for atomic Ag adsorption can be improved both on the perfect and oxygen-vacancy surfaces, while the activity of the CuO(111) surface for atomic Ag adsorption will be suppressed on precovered oxygen surfaces. Furthermore, the adsorption of NO on different CuO(111) surfaces with Ag adsorption was investigated, and the calculation results show that the adsorption of NO on an Ag-loaded CuO(111) surface is greater than that on the pure CuO(111) surface.

  10. Bone healing at implants with different surface configurations: an experimental study in dogs.

    Science.gov (United States)

    Beolchini, Marco; Lang, Niklaus P; Gómez Moreno, Gerardo; Iezzi, Giovanna; Botticelli, Daniele; Calvo Guirado, José Luis

    2016-02-01

    To study osseointegration of implants with surface modifications by the use of fluoroboric acid and/or H2 O2 installed in conventional sites or sites with circumferential marginal defects. Four implants with different surfaces were used. One basic surface (ZirTi(®)) was sandblasted with zirconium microspheres and acid etched additionally with hydrofluoric acid. A second surface was treated with fluoroboric acid instead of hydrofluoric acid. The remainder of the other two surfaces was additionally treated with H2O2. The edentulous mandibles of 6 foxhound dogs were used to randomly install 8.5-mm-long implants with the different surfaces and to study the histological healing after 1 and 3 months. To study osteoconductivity, additional four recipient sites were prepared with the coronal region being widened so that a 4 mm deep and 0.85 mm wide marginal defect resulted after the placement of the four implants with different surfaces. No filler material or membranes were used, and a fully submerged healing was allowed for 3 months. At the conventional sites, new bone formation ranged between 68.5% and 74.9% after 1 month. After 3 months, bone-to-implant contact ranged from 72.6% at the ZirTi(®) surface to 84.1% at the fluoroboric acid-treated implants, the difference being statistically significant. At the sites with marginal defects, bone formation ranged from 0.77 mm at the surface treated with fluoroboric acid and H2O2 , to 1.93 mm at the surface treated with fluoroboric acid alone. Fluoroboric acid treatment alone of titanium implant surfaces resulted in improved osseointegration and osteoconductivity after 3 months. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Electron microscopy studies of zirconia-alumina nanolaminates and nickel oxide surfaces

    Science.gov (United States)

    Schofield, Marvin Allan

    Understanding the atomic scale properties and behavior of materials systems offers exciting potential for the development of fresh and innovative technological applications to impact the world in which we live. The basic materials physics problem addressed in this dissertation involves separate studies of the effects owing to the existence of surfaces present in two types of oxide systems: that of polycrystalline zirconia in zirconia-alumina multilayer films, and that of single-crystal NiO. The first surface science problem involved study of nanometer-sized zirconia crystallites. Due to the small crystallite size, energetics occurring at the surface of crystallites affected properties of the bulk material including its crystallographic phase. High resolution transmission electron microscopy was used to characterize zirconia crystallites within sputter-deposited films containing a range of zirconia layer thickness, i.e. zirconia crystallite size, and crystallographic phase identification of individual crystallites was made directly from digital high resolution images. Information about the growth behavior of zirconia crystallites was inferred from the observed phase and morphology of crystallites as a function of zirconia layer thickness, i.e. growth time. The capabilities for rapid phase identification of individual crystallites allowed for in situ experimentation into the crystallographic phase transformation behavior of the zirconia nanocrystallites, and for a comparison of that behavior to be made against reported behavior of systems containing much larger, micron-sized zirconia crystals. The second surface science problem involved study of surfaces of single-crystal NiO, specifically, the polar-(111) surface. The NiO(111) surface, when the surface atoms are in their bulk-terminated positions, has an infinite surface energy. Studies were carried out to examine by what mechanisms the polar surface of NiO overcomes this large surface energy. Transmission electron

  12. Adsorption Study of a Water Molecule on Vacancy-Defected Nonpolar CdS Surfaces

    Science.gov (United States)

    2017-01-01

    A detailed understanding of the water–semiconductor interface is of major importance for elucidating the molecular interactions at the photocatalyst’s surface. Here, we studied the effect of vacancy defects on the adsorption of a water molecule on the (101̅0) and (112̅0) CdS surfaces, using spin-polarized density functional theory. We observed that the local spin polarization did not persist for most of the cationic vacancies on the surfaces, unlike in bulk, owing to surface reconstructions caused by displaced S atoms. This result suggests that cationic vacancies on these surfaces may not be the leading cause of the experimentally observed magnetism in CdS nanostructures. The surface vacancies are predominantly nonmagnetic except for one case, where a magnetic cationic vacancy is relatively stable due to constraints posed by the (101̅0) surface geometry. At this particular magnetic defect site, we found a very strong interaction with the H2O molecule leading to a case of chemisorption, where the local spin polarization vanishes concurrently. At the same defect site, adsorption of an O2 molecule was also simulated, and the results were found to be consistent with experimental electron paramagnetic resonance findings for powdered CdS. The anion vacancies on these surfaces were always found to be nonmagnetic and did not affect the water adsorption at these surfaces. PMID:28539988

  13. Theoretical study of adsorption of nitrogen-containing environmental contaminants on kaolinite surfaces.

    Science.gov (United States)

    Scott, Andrea Michalkova; Burns, Elizabeth A; Hill, Frances C

    2014-08-01

    The adsorption of nitrogen-containing compounds (NCCs) including 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4-dinitroanisole (DNAN), and 3-nitro-1,2,4-triazol-5-one (NTO) on kaolinite surfaces was investigated. The M06-2X and M06-2X-D3 density functionals were applied with the cluster approximation. Several different positions of NCCs relative to the adsorption sites of kaolinite were examined, including NCCs in perpendicular and parallel orientation toward both surface models of kaolinite. The binding between the target molecules and kaolinite surfaces was analyzed and bond energies were calculated applying the atoms in molecules (AIM) method. All NCCs were found to prefer a parallel orientation toward both kaolinite surfaces, and were bound more strongly to the octahedral than to the tetrahedral site. TNT exhibited the strongest interaction with the octahedral surface and DNAN with the tetrahedral surface of kaolinite. Hydrogen bonding was shown to be the dominant non-covalent interaction for NCCs interacting with the octahedral surface of kaolinite with a small stabilizing effect of dispersion interactions. In the case of adsorption on the tetrahedral surface, kaolonite-NCC binding was shown to be governed by the balance between hydrogen bonds and dispersion forces. The presence of water as a solvent leads to a significant decrease in the adsorption strength for all studied NCCs interacting with both kaolinite surfaces.

  14. Surface Characterization and Cell Adhesion of Different Zirconia Treatments: An in vitro Study.

    Science.gov (United States)

    Nassif, Wadih; Rifai, Mohamad

    2018-02-01

    The aim of this study was to characterize the surface of zirconia subjected to different treatments and evaluate its effect on cell adhesion and proliferation. A total of 80 zirconia disks were divided into four groups (n = 20) according to the surface treatments used: group I: as-sintered (AS), no surface treatment applied; group II: abrasion treatment applied using Rocatec (ROC; 3M ESPE) system with silica-coated alumina powder of grit size 110 μm; group III: erbium, chromium:yttrium, scandium, gallium, garnet (Er, Cr:YSGG) laser (LAS; BIOLASE) was used at a frequency of 20 Hz and output power of 3 W; and group IV: specimens were subjected to the selective infiltration etching (SIE) technique. Surface characterization was evaluated for the different groups (roughness, hardness, and morphology), and cell behavior (adhesion and proliferation) was tested (a = 0.05). The ROC group reported a significant increase in surface roughness (2.201 ± 0.352) and Vickers hardness (1758 ± 16.6) compared with the other surface treatments. The SIE surface-treated group reported a significantly higher number of cells (64.5 ± 2.6 and 53.5 ± 2.2 respectively) compared with the other surface-treated groups. The SIE is a promising surface treatment for zirconia that significantly enhances cell adhesion and osseointegration. The SIE treatment of zirconia implants may help in a faster and better osseointegration.

  15. Comparative study of binding constants from Love wave surface acoustic wave and surface plasmon resonance biosensors using kinetic analysis.

    Science.gov (United States)

    Lee, Sangdae; Kim, Yong-Il; Kim, Ki-Bok

    2013-11-01

    Biosensors are used in a variety of fields for early diagnosis of diseases, measurement of toxic contaminants, quick detection of pathogens, and separation of specific proteins or DNA. In this study, we fabricated and evaluated the capability of a high sensitivity Love wave surface acoustic wave (SAW) biosensor. The experimental setup was composed of the fabricated 155-MHz Love wave SAW biosensor, a signal measurement system, a liquid flow system, and a temperature-control system. Subsequently, we measured the lower limit of detection (LOD) of the 155-MHz Love wave SAW biosensor, and calculated the association and dissociation constants between protein G and anti-mouse IgG using kinetic analysis. We compared these results with those obtained using a commercial surface plasmon resonance (SPR) biosensor. We found that the LOD of the SAW biosensor for anti-mouse IgG and mouse IgG was 0.5 and 1 microg/ml, respectively, and the resultant equilibrium association and dissociation constants were similar to the corresponding values obtaining using the commercial SPR biosensor. Thus, we conclude that the fabricated 155-MHz Love wave SAW biosensor exhibited the high sensitivity of the commercial SPR biosensor and was able to analyze the binding properties of the ligand and receptor by kinetic analysis similarly to the commercial SPR biosensor.

  16. Contact angle studies on PDMS surfaces fouled by bovine serum albumin

    CSIR Research Space (South Africa)

    Windvoel, VT

    2010-01-01

    Full Text Available proteins. This is a limitation to microfluidic applications that require hydrophobic surfaces where proteins are involved. This study determines the change in wetting of PDMS after fouling by a protein, bovine serum albumin (BSA), by measuring contact...

  17. Infrared spectroscopic study of radiation-induced adsorption of n-hexane on a beryllium surface

    Science.gov (United States)

    Gadzhieva, N. N.

    2017-07-01

    Radiation-stimulated adsorption on a beryllium surface is studied by IR reflection-absorption spectroscopy. It is found that γ-irradiation at room temperature leads to the appearance of n-hexane adsorption centers on a beryllium surface according to molecular and dissociation mechanisms. The kinetics of n-hexane adsorption in a Be- n-hexane system is studied; activated dissociative chemisorption accompanied by formation of beryllium alkyls and surface hydrides is observed at absorbed doses 15 kGy ≤ Vγ ≤ 35 kGy. A possible mechanism of this process is suggested.

  18. Archaeogeophysical Studies in Ancient Tios, Zonguldak-Caycuma-Filyos, Turkey

    Science.gov (United States)

    Ahmet Yuksel, Fethi; Hoskan, Nihan; Sumer Atasoy, Yusuf

    2010-05-01

    Ancient Tios is located in the Filyos township of the Caycuma District of Zonguldak on the western Black Sea region, Turkey. The ancient city was probably founded by Milesians in the 7th cent. B.C. The region was inhabited through the centuries by Persians, Romans, Genoese and all the way to the Ottoman times. About the archaeological history of the city , we have relatively limited knowledge both in ancient records and in contemporary archaeological research. In the Roman period coastal defensive walls, acquaduct, theatre, defensive tower and the port with its breakwater are the only visible remains of the city. The acropolis of the ancient city is located immediately to the east of the present Filyos township on a hill. The original architectural form of the defensive wall located in the acropolis will be revealed after research to its foundation completed. A partially destroyed stone building is another remaining ruin in the acropolis .The Roman period theatre of Tios is located in the north of the road leading into Filyos. Built on a sloping land, local stones were used in its construction. Mostly ruined its original stones have been used later in other buildings. Only a few of the arches of the aquaduct, located to the north of the theatre, are still standing. There are the remains of another structure which could have been a defensive tower located in 200 meters to the west of the theatre. GPR measurements display the exact location of any sub-surface structures. To the west of the acropolis and within the ancient port, there are the under water remains of a breakwater. The local sandstones, quarries were studied archaeogeologically as they provided the main building materials. Since there has been no archaeological research done on the site until the 2006 season, archaeogeopysical data are reveal additional information about ancient Tios. Surface survey and georadar, magnetic and geoelectric studies have been done and after that, excavations were started

  19. High-resolution x-ray scatter and reflectivity study of sputtered IR surfaces

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Abdali, S.; Hornstrup, Allan

    1993-01-01

    In recent years there has been an increased interest in the possible use of Ir as the reflecting surface in X-ray telescope programs. An X-ray study of such surfaces produced by sputtering of Ir on highly polished Zerodur flats is presented here. The study was performed using Fe K(alpha) 1 (6...... result shows that an Ir coating can be produced with nominal bulk density....

  20. Structural study, by surface differential diffraction of neutrons, of the surface of a nickel powder covered with deuterium

    Science.gov (United States)

    Beaufils, J. P.

    1993-01-01

    The analysis of the data of a neutron surface differential diffraction experiment, using H positions determined in the literature whenever available, supports the following model: Grains of the studied nickel powder are limited by (20 ± 10)% of (111) faces and 80% of (110) faces. The (110) faces expose (111) and (1¯11) facets because of anisotropic roughening. A new interpretation of the streaks observed in LEED patterns and a discussion of the coverage provides additional arguments in favour of the roughening. On the facets of the rough faces, the D atoms are displaced from the position they would have on a genuine (111) face. They are no longer on a C3 axis. The Ni atoms of the rough faces suffer an average displacement of 0.015 ± 0.015 nm in the [110] outward direction. The shortest NiD distance on the rough face is equal to 0.19 ± 0.015 nm.

  1. Studying groundwater and surface water interactions using airborne remote sensing in Heihe River basin, northwest China

    Directory of Open Access Journals (Sweden)

    C. Liu

    2015-05-01

    Full Text Available Managing surface water and groundwater as a unified system is important for water resource exploitation and aquatic ecosystem conservation. The unified approach to water management needs accurate characterization of surface water and groundwater interactions. Temperature is a natural tracer for identifying surface water and groundwater interactions, and the use of remote sensing techniques facilitates basin-scale temperature measurement. This study focuses on the Heihe River basin, the second largest inland river basin in the arid and semi-arid northwest of China where surface water and groundwater undergoes dynamic exchanges. The spatially continuous river-surface temperature of the midstream section of the Heihe River was obtained by using an airborne pushbroom hyperspectral thermal sensor system. By using the hot spot analysis toolkit in the ArcGIS software, abnormally cold water zones were identified as indicators of the spatial pattern of groundwater discharge to the river.

  2. A Computational Study of Richtmyer-Meshkov Instability with Surface Tension

    Science.gov (United States)

    Francois, Marianne; Velechovsky, Jan; Jibben, Zach; Masser, Thomas; LANL Collaboration

    2017-11-01

    We have added the capability to model surface tension in our adaptive mesh refinement compressible flow solver, xRage. Our surface tension capability employs the continuum surface force to model surface tension and the height function method to compute curvatures. We have verified our model implementation for the static and oscillating droplets test cases and the linear regime of the Rayleigh-Taylor instability. With this newly added capability, we have performed a numerical study of the effects of surface tension on single-mode and multi-mode Richtmyer-Meshkov instability. This work was performed under the auspices of the National Nuclear Security Administration of the U.S. Department of Energy at Los Alamos National Laboratory under Contract No. DE-AC52 - 06NA25396.

  3. Study on the surface constitute properties of high-speed end milling aluminum alloy

    Science.gov (United States)

    Huang, Xiaoming; Li, Hongwei; Yumeng, Ma

    2017-09-01

    The physical and mechanical properties of the metal surface will change after the metal cutting processing. The comprehensive study of the influence of machining parameters on surface constitute properties are necessary. A high-speed milling experiment by means of orthogonal method with four factors was conducted for aluminum alloy7050-T7451. The surface constitutive properties of the Al-Alloy surface were measured using SSM-B4000TM stress-strain microprobe system. Based on all the load-depth curves obtained, the characteristics parameters such as strain hardening exponent n and yield strength σy of the milling surface are calculated. The effect of cutting speed, feed rate, and width and depth of cut on n and σy was investigated using the ANOVA techniques. The affecting degree of milling parameters on n and σy was v>fz> ap < ae. The influence of milling parameters on n and σ y was described and discussed.

  4. Experimental Study on the Tensile Strength and Linear Expansion Coefficient of Air Tunnel Terrazzo Surface

    Directory of Open Access Journals (Sweden)

    Boping Li

    2015-01-01

    Full Text Available At present, studies on the surface tension of air tunnel terrazzo under wind load and how regularly it is affected by temperature are relatively less, and the measured results of the thermal expansion coefficient of terrazzo have not yet been given. In this paper, based on the top terrazzo surface structure of the inner wall of the wind tunnel, the tensile performance tests of terrazzo surface layer are conducted, while the thermal expansion coefficient of the six terrazzo test blocks were tested. The tests and analysis show that the construction of terrazzo surface, based on the proposed construction process, can effectively guarantee the reliable cement performance for the binding layer between mortar and concrete base layer, terrazzo surface layer and the cement mortar layer. And the thermal expansion coefficient of terrazzo can be valued at 1.06e-5/ºC.

  5. A Study of Atmospheric Plasma Treatment on Surface Energetics of Carbon Fibers

    International Nuclear Information System (INIS)

    Park, Soo Jin; Chang, Yong Hwan; Moon, Cheol Whan; Suh, Dong Hack; Im, Seung Soon; Kim, Yeong Cheol

    2010-01-01

    In this study, the atmospheric plasma treatment with He/O 2 was conducted to modify the surface chemistry of carbon fibers. The effects of plasma treatment parameters on the surface energetics of carbon fibers were experimentally investigated with respect to gas flow ratio, power intensity, and treatment time. Surface characteristics of the carbon fibers were determined by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Fourier transform infrared (FT-IR), Zeta-potential, and contact angle measurements. The results indicated that oxygen plasma treatment led to a large amount of reactive functional groups onto the fiber surface, and these groups can form together as physical intermolecular bonding to improve the surface wettability with a hydrophilic polymer matrix

  6. Site competition on metal surfaces: an electron spectroscopic study of sequential adsorption on W(110)

    International Nuclear Information System (INIS)

    Steinkilberg, M.; Menzel, D.

    1977-01-01

    Using UPS and XPS, the sequential adsorption of hydrogen + carbon monoxide, and of hydrogen + oxygen, on W(110) has been studied at room temperature. Adsorption of CO on a H-covered surface is rapid and leads to total displacement of hydrogen. The resulting CO layer however, is different from that formed on the clean surface under identical conditions, in that it consists of a higher percentage of virgin CO, while considerably more β-CO forms on the clean surface. Oxygen does not adsorb on a H-covered surface, nor displace hydrogen. It is concluded that hydrogen most probably occupies the same sites utilized by dissociative adsorption of CO and oxygen, while virgin CO can also occupy different sites; its adsorption can thus lead to interactional weakening of the H-surface bond. (Auth.)

  7. First-principles study of the surface properties of U-Mo system

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Zhi-Gang; Liang, Linyun; Yacout, Abdellatif M.

    2018-02-01

    U-Mo alloys are promising fuels for future high-performance research reactors with low enriched uranium. Surface properties, such as surface energy, are important inputs for mesoscale simulations (e.g., phase field method) of fission gas bubble behaviors in irradiated nuclear fuels. The lack of surface energies of U-Mo alloys prevents an accurate modeling of the morphology of gas bubbles and gas bubble-induced fuel swelling. To this end, we study the surface properties of U-Mo system, including bcc Mo, alpha-U, gamma-U, and gamma U-Mo alloys. All surfaces up to a maximum Miller index of three and two are calculated for cubic Mo and gamma-U and non-cubic alpha-U, respectively. The equilibrium crystal shapes of bcc Mo, alpha-U and gamma-U are constructed using the calculated surface energies. The dominant surface orientations and the area fraction of each facet are determined from the constructed equilibrium crystal shape. The disordered gamma U-Mo alloys are simulated using the Special Quasirandom Structure method. The (1 1 0) and (1 0 0) surface energies of gamma U-7Mo and U-10Mo alloys are predicted to lie between those of gamma-U and bcc Mo, following a linear combination of the two constituents' surface energies. To better compare with future measurements of surface energies, the area fraction weighted surface energies of alpha-U, gamma-U and gamma U-7Mo and U-10Mo alloys are also predicted. (C) 2017 Published by Elsevier B.V.

  8. TiO2 Surface Coating of Mn-Zn Dopped Ferrites Study

    DEFF Research Database (Denmark)

    Solný, Tomáš; Ptacek, Petr; Másilko, Jiří

    2016-01-01

    This study deals with TiO2 coating of powder Mn-Zn ferrite in order to recieve photocatalytic layer on the top of these particles, forming core-shell catalyst. Powder catalysts are of great advance over the world due to the high surface area, considering the kinetics proceeds through heterogenous...... phase boundary catalysis. However their withdrawal from cleaning systems often requires energetically and economically demanding processes such as filtration and ultrafiltration. Since the ferrite is magnetic, the advantage of such formed core-shell photocatalyst is easibility of removing from...... photocatalytic decomposition system using external magnetic field. In this study the surface coating is performed, using Ti alkoxides mixtures with nanosized TiO2 particles and C and Au coating to form film layer of TiO2 on the surface of ferrite. XRD, SEM – EDS analyses are employed to study surface coating....

  9. Experimental Study of Reciprocating Friction between Rape Stalk and Bionic Nonsmooth Surface Units

    Directory of Open Access Journals (Sweden)

    Zheng Ma

    2015-01-01

    Full Text Available Background. China is the largest producer of rape oilseed in the world; however, the mechanization level of rape harvest is relatively low, because rape materials easily adhere to the cleaning screens of combine harvesters, resulting in significant cleaning losses. Previous studies have shown that bionic nonsmooth surface cleaning screens restrain the adhesion of rape materials, but the underlying mechanisms remain unclear. Objective. The reciprocating friction between rape stalk and bionic nonsmooth metal surface was examined. Methods. The short-time Fourier transform method was used to discriminate the stable phase of friction signals and the stick-lag distance was defined to analyze the stable reciprocating friction in a phase diagram. Results. The reciprocating friction between rape stalk and metal surface is a typical stick-slip friction, and the bionic nonsmooth metal surfaces with concave or convex units reduced friction force with increasing reciprocating frequency. The results also showed that the stick-lag distance of convex surface increased with reciprocating frequency, which indicated that convex surface reduces friction force more efficiently. Conclusions. We suggest that bionic nonsmooth surface cleaning screens, especially with convex units, restrain the adhesion of rape materials more efficiently compared to the smooth surface cleaning screens.

  10. Molecular dynamics study of room temperature ionic liquids with water at mica surface

    Directory of Open Access Journals (Sweden)

    Huanhuan Zhang

    2018-04-01

    Full Text Available Water in room temperature ionic liquids (RTILs could impose significant effects on their interfacial properties at a charged surface. Although the interfaces between RTILs and mica surfaces exhibit rich microstructure, the influence of water content on such interfaces is little understood, in particular, considering the fact that RTILs are always associated with water due to their hygroscopicity. In this work, we studied how different types of RTILs and different amounts of water molecules affect the RTIL-mica interfaces, especially the water distribution at mica surfaces, using molecular dynamics (MD simulation. MD results showed that (1 there is more water and a thicker water layer adsorbed on the mica surface as the water content increases, and correspondingly the average location of K+ ions is farther from mica surface; (2 more water accumulated at the interface with the hydrophobic [Emim][TFSI] than in case of the hydrophilic [Emim][BF4] due to the respective RTIL hydrophobicity and ion size. A similar trend was also observed in the hydrogen bonds formed between water molecules. Moreover, the 2D number density map of adsorbed water revealed that the high-density areas of water seem to be related to K+ ions and silicon/aluminum atoms on mica surface. These results are of great importance to understand the effects of hydrophobicity/hydrophicility of RTIL and water on the interfacial microstructure at electrified surfaces. Keywords: Room temperature ionic liquids, Hydrophobicity/hydrophicility, Water content, Electrical double layer, Mica surface

  11. Preparation of well-defined samples of AlPdMn quasicrystals for surface studies

    Science.gov (United States)

    Jenks, C. J.; Delaney, D. W.; Bloomer, T. E.; Chang, S.-L.; Lograsso, T. A.; Shen, Z.; Zhang, C.-M.; Thiel, P. A.

    1996-12-01

    We have developed a method for preparing single-grain, quasicrystalline AlPdMn samples for surface studies in ultrahigh vacuum. The main issues of concern are phase purity, the quality of the surface structure, and the surface, and the surface composition. Phase purity is enhanced by annealing the sample in ultra-pure Ar in a sealed quartz ampoule for several days before polishing. Polishing with colloidal silica allows secondary phases to be detected readily with an optical microscope. As a final precaution, phase purity can be checked sensitively with scanning Auger microscopy. After this stage, the sample can be cleaned in ultrahigh vacuum with ion bombardment. Annealing is required after bombardment to restore surface structure and to obtain a low-energy electron diffraction (LEED) pattern of an oriented sample. However, both ion bombardment and heating to temperatures above 870 K in vacuum, produce Pd-rich surfaces. As a final step, for the five-fold surface, we recommend heating briefly to 1050-1100 K and then annealing at 870 K for several hours. This produces both an excellent LEED pattern, and a surface composition close to that of the bulk.

  12. Stepwise dehydrogenation of ammonia on Fcc-Co surfaces: A DFT study

    International Nuclear Information System (INIS)

    Ma, F.F.; Ma, S.H.; Jiao, Z.Y.; Dai, X.Q.

    2017-01-01

    Highlights: • On Co surfaces, oxygen atom not only strengthens ammonia-substrate interaction but also facilitates ammonia dissociation on the Co surfaces. • Pre-adsorbed O atom significantly promotes the stepwise dehydrogenation of ammonia on Co(110), giving rise to N atom strongly binding with the surface. • The dissociation of NH appears to be the rate-determining step on O-covered Co(111) and Co(100) surfaces. • The species N and NH produced in ammonia dehydrogenation are likely responsible for cobalt catalyst deactivation in the excess of oxygen atom. - Abstract: The stepwise dehydrogenation of ammonia on clean and O-covered Co surfaces have been studied by performing density functional theory (DFT) calculations. It is found that the interaction of species NH x (x = 0–3) with the Co surfaces become stronger with its further dehydrogenation, and oxygen atom not only strengthens ammonia-substrate interaction but also facilitates ammonia dissociation. Specifically, pre-adsorbed O atom significantly promotes the stepwise dehydrogenation of ammonia on Co(110), giving rise to N atom strongly binding with the surface. In contrast, the dissociation of NH appears to be the rate-determining step on O-covered Co(111) and Co(100) surfaces, due to the high energy barriers. And present results demonstrate that the species N and NH produced in ammonia dehydrogenation are likely responsible for cobalt catalyst deactivation in the excess of oxygen atom.

  13. Root surface smoothness or roughness following open debridement. An in vivo study.

    Science.gov (United States)

    Schlageter, L; Rateitschak-Plüss, E M; Schwarz, J P

    1996-05-01

    Consensus has not been reached on the desired characteristics of the root surface following cleaning. It is also not clear what degree of roughness or smoothness results from use of different instruments. In the present human clinical study, various instruments for root surface cleaning were evaluated. 18 teeth destined for extraction for periodontal reasons were utilized. After reflection of soft tissue flaps, the 72 root surface aspects of the 18 teeth were uniformally treated with one of the following instruments: Gracey curette (GC), piezo ultrasonic scaler (PUS), Perioplaner curette (PPC), sonic scaler (SS), 75 microns diamond (75 D) and 15 microns diamond (15.D). The degree of roughness of each surface was measured after extraction. A planimetry apparatus was used to establish the average surface roughness (Ra) and the mean depth of the roughness profile (Rz). It was demonstrated that hand- and machine-driven curettes as well as very fine rotating diamonds created the smoothest root surfaces, while "vibrating" instruments such as sonic and ultrasonic scalers, as well as coarse diamonds, tended to roughen the root surface. Whether the root surface should be rough or smooth in order to enhance tissue healing remains an open question.

  14. In vitro study of Streptococcus mutans adhesion on composite resin coated with three surface sealants

    Directory of Open Access Journals (Sweden)

    Da Hye Kim

    2017-02-01

    Full Text Available Objectives Although the coating of surface sealants to dental composite resin may potentially reduce bacterial adhesion, there seems to be little information regarding this issue. This preliminary in vitro study investigated the adhesion of Streptococcus mutans (S. mutans on the dental composite resins coated with three commercial surface sealants. Materials and Methods Composite resin (Filtek Z250 discs (8 mm in diameter, 1 mm in thickness were fabricated in a mold covered with a Mylar strip (control. In group PoGo, the surfaces were polished with PoGo. In groups PS, OG, and FP, the surfaces polished with PoGo were coated with the corresponding surface sealants (PermaSeal, PS; OptiGuard, OG; Fortify Plus, FP. The surfaces of the materials and S. mutans cells were characterized by various methods. S. mutans adhesion to the surfaces was quantitatively evaluated using flow cytometry (n = 9. Results Group OG achieved the lowest water contact angle among all groups tested (p 0.05 or significantly lower (group OG, p < 0.001 bacterial adhesion when compared with the control group. Conclusions The application of the surface sealants significantly reduced S. mutans adhesion to the composite resin polished with the PoGo.

  15. In situ diffraction studies of electrode surface structure during gold electrodeposition

    International Nuclear Information System (INIS)

    Magnussen, O.M.; Krug, K.; Ayyad, A.H.; Stettner, J.

    2008-01-01

    Surface X-ray scattering (SXS) in transmission geometry provides a valuable tool for in situ structural studies of electrochemical interfaces under reaction conditions, as illustrated here for homoepitaxial electrodeposition on Au(1 0 0) and Au(1 1 1) electrodes. Employing diffusion-limited deposition conditions to separate the effects of potential and deposition rate, a mutual interaction between the interface structure and the growth behavior is found. Time-dependent SXS measurements during Au(1 0 0) homoepitaxy show with decreasing potential transitions from step flow to layer-by-layer growth, then to multilayer growth, and finally back to layer-by-layer growth. This complex growth behavior can be explained within the framework of kinetic growth theory by the effect of potential, Cl adsorbates and the Au surface structure, specifically the presence of the surface reconstruction, on the Au surface mobility. Conversely, the electrodeposition process influences the structure of the reconstructed Au surface, as illustrated for Au(1 1 1), where a significant deposition-induced compression of the Au surface layer as compared to Au(1 1 1) surfaces under ultrahigh vacuum conditions or in Au-free electrolyte is found. This compression increases towards more negative potentials, which may be explained by a release of potential-induced surface stress

  16. Stability of underpotentially deposited Ag layers on a Au(111) surface studied by surface X-ray scattering

    OpenAIRE

    Kondo, Toshihiro; Takakusagi, Satoru; Uosaki, Kohei

    2009-01-01

    Stability of underpotentially deposited (upd) Ag layers on Au(111) surface was investigated by surface X-ray scattering (SXS). While the complete pseudomorphic Ag bilayer on Au(111) surface obtained by upd at 10 mV (vs. Ag/Ag+) was maintained its structure even after the circuit was disconnected and the surface was exposed to ambient atmosphere, the pseudomorphic Ag monolayer obtained by upd at 50 mV was converted to a partial bilayer with the coverage of 0.66 ML and 0.46 ML for the 1st and 2...

  17. Surface Pourbaix diagrams and oxygen reduction activity of Pt, Ag and Ni(111) surfaces studied by DFT

    DEFF Research Database (Denmark)

    Hansen, Heine Anton; Rossmeisl, Jan; Nørskov, Jens Kehlet

    2008-01-01

    The electrochemical most stable surface structures is investigated as function of pH and potential for Pt, Ag and Ni based on DFT calculations and constructed surface Pourbaix diagrams. It is also explained why metals such as Ag and Ni may be used successfully in alkaline fuel cells but not in ac......The electrochemical most stable surface structures is investigated as function of pH and potential for Pt, Ag and Ni based on DFT calculations and constructed surface Pourbaix diagrams. It is also explained why metals such as Ag and Ni may be used successfully in alkaline fuel cells...

  18. Detecting urbanization effects on surface and subsurface thermal environment--a case study of Osaka.

    Science.gov (United States)

    Huang, Shaopeng; Taniguchi, Makoto; Yamano, Makoto; Wang, Chung-ho

    2009-04-15

    Tremendous efforts have been devoted to improve our understanding of the anthropogenic effects on the atmospheric temperature change. In comparison, little has been done in the study of the human impacts on the subsurface thermal environment. The objective of this study is to analyze surface air temperature records and borehole subsurface temperature records for a better understanding of the urban heat island effects across the ground surface. The annual surface air temperature time series from six meteorological stations and six deep borehole temperature profiles of high qualities show that Osaka has been undergoing excess warming since late 19th century. The mean warming rate in Osaka surface air temperature is about 2.0 degrees C/100a over the period from 1883 to 2006, at least half of which can be attributed to the urban heat island effects. However, this surface air temperature warming is not as strong as the ground warming recorded in the subsurface temperature profiles. The surface temperature anomaly from the Osaka meteorological record can only account for part of the temperature anomaly recorded in the borehole temperature profiles. Surface air temperature is conventionally measured around 1.5 m above the ground; whereas borehole temperatures are measured from rocks in the subsurface. Heat conduction in the subsurface is much less efficient than the heat convection of the air above the ground surface. Therefore, the anthropogenic thermal impacts on the subsurface can be more persistent and profound than the impacts on the atmosphere. This study suggests that the surface air temperature records alone might underestimate the full extent of urban heat island effects on the subsurface environment.

  19. AFM stochastic analysis of surface twisted nanograin chains of iron oxide: a kinetic study

    International Nuclear Information System (INIS)

    Akhavan, O; Azimirad, R

    2009-01-01

    We have studied the stochastic parameters of surface iron oxide nanograin chains, 97 nm in diameter and 2.4 μm in length, prepared at different annealing temperatures, using atomic force microscopy (AFM) spectral analysis. In this regard, the roughness of the thin films including self-assembled twisted nanograin chains has been analysed and characterized using the height-height correlation function, the roughness exponent as well as the power spectrum density of the AFM profiles and their gradient, for the different annealing temperatures. The tip convolution effect on the stochastic parameters under study has also been investigated. The kinetics of the formation of nanograins on the film surface has been obtained using the AFM spectral analysis of the profiles and their gradient. The activation energy needed for the formation of surface nanograin chains was found to be 0.55 eV. It has been shown that the tip-surface interaction affects mainly the diffusion parameters obtained by using the surface roughness analysis of the profiles, while use of the surface roughness analysis of the gradient of the profiles results in a nearly independent tip convolution effect on the diffusion parameters. Hence, this work also provides a method for calculating the required activation energy for the formation of self-assembled nanostructures affecting the roughness of a surface.

  20. DNA adsorption and desorption on mica surface studied by atomic force microscopy

    International Nuclear Information System (INIS)

    Sun Lanlan; Zhao Dongxu; Zhang Yue; Xu Fugang; Li Zhuang

    2011-01-01

    The adsorption of DNA molecules on mica surface and the following desorption of DNA molecules at ethanol-mica interface were studied using atomic force microscopy. By changing DNA concentration, different morphologies on mica surface have been observed. A very uniform and orderly monolayer of DNA molecules was constructed on the mica surface with a DNA concentration of 30 ng/μL. When the samples were immersed into ethanol for about 15 min, various desorption degree of DNA from mica (0-99%) was achieved. It was found that with the increase of DNA concentration, the desorption degree of DNA from the mica at ethanol-mica interface decreased. And when the uniform and orderly DNA monolayers were formed on the mica surface, almost no DNA molecule desorbed from the mica surface in this process. The results indicated that the uniform and orderly DNA monolayer is one of the most stable DNA structures formed on the mica surface. In addition, we have studied the structure change of DNA molecules after desorbed from the mica surface with atomic force microscopy, and found that the desorption might be ascribed to the ethanol-induced DNA condensation.

  1. Study on the early surface films formed on Mg-Y molten alloy in different atmospheres

    Directory of Open Access Journals (Sweden)

    A.R. Mirak

    2015-09-01

    Full Text Available In the present study, the non-isothermal early stages of surface oxidation of liquid Mg-1%Y alloy during casting were studied under UPH argon, dry air, and air mixed with protective fluorine-bearing gases. The chemistry and morphology of the surface films were characterized by SEM and EDX analyses. The results indicate a layer of smooth and tightly coherent oxidation film composed of MgO and Y2O3 formed on the molten Mg-Y alloy surface with 40–60 nm thickness under dry air. A dendritic/cellular microstructure is clearly visible with Y-rich second phases gathered in surface of the melt and precipitated along the grain/cell boundaries under all gas conditions. Under fluorine-bearing gas mixtures, the surface film was a mixed oxide and fluoride and more even; a flat and folded morphology can be seen under SF6 with oxide as dominated phase and under 1, 1, 1, 2-tetra-fluoroethane, a smooth and compact surface film uniformly covering the inner surface of the bubble with equal oxide and fluoride thickness, which results in a film without any major defects. MgF2 phase appears to be the key characteristic of a good protective film.

  2. Overview on geophysical monitoring at the Ketzin CO2 storage site (Germany) using seismic and geoelectric methods (Invited)

    Science.gov (United States)

    Bergmann, P.; Ivandic, M.; Ivanova, A.; Juhlin, C.; Lueth, S.; Schmidt-Hattenberger, C.

    2013-12-01

    At Ketzin, a town close to Berlin, the first European onshore pilot scale project was initiated in 2004. After baseline characterization and drilling, CO2 injection was commenced in June 2008. As of August 2013, ~67 kilotons have been injected. Using one injection well, the CO2 is injected in a super-critical state into sandstones of the Stuttgart Formation, a saline aquifer at 620 m to 650 m depth. The depth of the Ketzin reservoir and injected mass of CO2 are not representative for CCS activities at an industrial scale. However, due to the relatively small amount of CO2 injected, combined with a complex storage reservoir, the site poses qualified conditions for testing of monitoring approaches. Consequently, a wide range of geophysical methods are in operation at the Ketzin site. Asides from well logging, both seismic methods and electric resistivity tomography (ERT) are being extensively applied. The applied survey setups comprise surface measurements, borehole measurements, and combined surface-downhole measurements. So far, the most comprehensive view onto the CO2 migration in the Ketzin reservoir is provided by two repeat 3D seismic surveys acquired in 2009 and 2012. They revealed a time-lapse seismic signal from the reservoir which indicates that the CO2 has progressively expanded to distances of 400-600 m away from the injection well by 2012. The apparent westward component of the plume migration observed in the 2009 data, is confirmed by a more pronounced westward component in the 2012 data. Consistent with the seismic monitoring, an increase in electrical resistivity around the injector was mapped by means of repeated surface-downhole ERT which indicates the presence of the injected CO2. These ERT surveys consist of current injections at the surface and voltage registration at the storage reservoir by means of a permanent electrode array that is installed in three wells (injector plus two monitoring wells). The imaged resistivity increase is consistent

  3. Infrared studies of gold nanochains on the Si(557) stepped surface

    Energy Technology Data Exchange (ETDEWEB)

    Vu Hoang, Chung; Klevenz, Markus; Lovrincic, Robert; Skibbe, Olaf; Neubrech, Frank; Pucci, Annemarie [Kirchhoff-Institut fuer Physik der Universitaet Heidelberg (Germany)

    2008-07-01

    Gold nanochains on Si(557) will be fabricated under ultra high vacuum conditions. The terraces of the stepped surface serve as one-dimensional diffusion channels, which leads to the formation of parallel monoatomic chains. Due to the appearance of metallic chains an anisotropic change of the conductivity of the substrate surface can be expected. The chain growth process and conductivity dependence versus gold composition will be investigated in-situ by using transmittance infrared spectroscopy (IRS) with light polarized parallel and perpendicular to the chains, respectively. IRS is a well-established method to observe conductivity changes on surfaces. The temperature dependent behaviour of gold chains will be studied as well.

  4. Electron energy-loss spectroscopic study of the surface of ceria abrasives

    International Nuclear Information System (INIS)

    Gilliss, Shelley R.; Bentley, James; Carter, C. Barry

    2005-01-01

    Surfaces of ceria (CeO 2 ) particles have been studied by electron energy-loss spectroscopy in a field-emission gun scanning transmission electron microscope. All the ceria particles analyzed contained Ce 3+ at the surface. Rare-earth impurities such as La were enriched at the surface and were observed for particles ranging from tens to hundreds of nanometers in size. Fluorine in the abrasives corresponded to a lower average cerium valence. Time series investigations indicate that fluorine substitutes on the oxygen sub-lattice and is charge-balanced by some cerium changing from Ce 4+ to Ce 3+

  5. Electron energy-loss spectroscopic study of the surface of ceria abrasives

    Energy Technology Data Exchange (ETDEWEB)

    Gilliss, Shelley R. [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue S.E., 151 Amundson Hall, Minneapolis, MN 55455 0132 (United States); Bentley, James [Oak Ridge National Laboratory, Metals and Ceramics Division, P.O. Box 2008, Oak Ridge, TN 37831 6024 (United States); Carter, C. Barry [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue S.E., 151 Amundson Hall, Minneapolis, MN 55455 0132 (United States)]. E-mail: carter@cems.umn.edu

    2005-02-28

    Surfaces of ceria (CeO{sub 2}) particles have been studied by electron energy-loss spectroscopy in a field-emission gun scanning transmission electron microscope. All the ceria particles analyzed contained Ce{sup 3+} at the surface. Rare-earth impurities such as La were enriched at the surface and were observed for particles ranging from tens to hundreds of nanometers in size. Fluorine in the abrasives corresponded to a lower average cerium valence. Time series investigations indicate that fluorine substitutes on the oxygen sub-lattice and is charge-balanced by some cerium changing from Ce{sup 4+} to Ce{sup 3+}.

  6. Comparative study on two different seal surface structure for reactor pressure vessel sealing behavior

    International Nuclear Information System (INIS)

    Chen Jun; Xiong Guangming; Deng Xiaoyun

    2014-01-01

    The seal surface structure is very important to reactor pressure vessel (RPV) sealing behavior. In this paper, two 3-D RPV sealing analysis finite models have been established with different seal surface structures, in order to study the influence of two structures. The separation of RPV upper and lower flanges, bolt loads and etc. are obtained, which are used to evaluate the sealing behavior of the RPV. Meanwhile, the comparative analysis of safety margin of two seal surface structural had been done, which provides the theoretical basis for RPV seal structure design optimization. (authors)

  7. What Happened when a Superhydrophobic Surface was Immersed in Water? A Study by Optical Transmission Microscopy

    DEFF Research Database (Denmark)

    Søgaard, Emil; Andersen, Nis Korsgaard; Smistrup, Kristian

    2014-01-01

    Here we present a simple and fast optical transmission microscopy study on the wetting transitions on hierarchical polymer surfaces immersed in water. We analyze the influence of immersion time and the liquid pressure on wetting states of individual micro-cavities on these surfaces, as well...... repellent properties of the two materials to a difference in the wetting of their nanostructures. The experimental observations indicate that both the diffusion of gas molecules in water, and the geometry of nanostructures influence the sustainability of superhydrophobicity of surfaces under water...

  8. DNA self-assembly on graphene surface studied by SERS mapping

    DEFF Research Database (Denmark)

    Botti, Sabina; Rufoloni, Alessandro; Laurenzi, Susanna

    2016-01-01

    The self-assembly of double-stranded DNA (dsDNA) segments on two variations of graphene surfaces having nano-platelets with different lateral sizes and thicknesses was investigated using surface enhanced Raman spectroscopy (SERS) and electrical impedance spectroscopy (EIS) techniques. Due...... nano-platelets. Results from the EIS analysis supported the SERS findings and confirmed that SERS mapping is a reliable method for a rapid monitoring of the procedures used to interface DNA with graphene surfaces. The present study, linking DNA anchoring morphology to the conductive properties of nano...

  9. Water adsorption on amorphous silica surfaces: a Car-Parrinello simulation study

    International Nuclear Information System (INIS)

    Mischler, Claus; Horbach, Juergen; Kob, Walter; Binder, Kurt

    2005-01-01

    A combination of classical molecular dynamics (MD) and ab initio Car-Parrinello molecular dynamics (CPMD) simulations is used to investigate the adsorption of water on a free amorphous silica surface. From the classical MD, SiO 2 configurations with a free surface are generated which are then used as starting configurations for the CPMD. We study the reaction of a water molecule with a two-membered ring at the temperature T = 300 K. We show that the result of this reaction is the formation of two silanol groups on the surface. The activation energy of the reaction is estimated and it is shown that the reaction is exothermic

  10. Study on the influence of carbon monoxide to the surface oxide layer of uranium metal

    International Nuclear Information System (INIS)

    Wang Xiaolin; Duan Rongliang; Fu Yibei; Xie Renshou; Zuo Changming; Zhao Chunpei; Chen Hong

    1997-01-01

    The influence of carbon monoxide to the surface oxide layer of uranium metal has been studied by X-ray photoelectron spectroscopy (XPS) and gas chromatography (GC). Carbon monoxide adsorption on the oxide layer resulted in U4f peak shifting to the lower binding energy. The content of oxygen in the oxide is decreased and the atomic ratio (O/U) is decreased by 7.2%. The amount of carbon dioxide in the atmosphere after the surface reaction is increased by 11.0%. The investigation indicates that the surface layer can prevent the further oxidation uranium metal in the atmosphere of carbon monoxide

  11. Manipulating a Co adatom on a stepped Cu surface by an STM tip: A theoretical study

    International Nuclear Information System (INIS)

    Liu, L.; Huang, R.Z.; Sun, Y.S.N.; Du, C.C.; Zhang, R.J.; Zheng, Y.X.; Wu, Y.X.

    2014-01-01

    A successful atomic manipulation may be influenced by many factors such as bias voltage, tip structure and manipulation modes et al. Here, performing atomic-scale simulations with ab initio based many-body potentials, we have studied the vertical and lateral manipulation of a single Co adatom on metallic Cu surfaces using STM tips at zero bias voltage. A suitable scheme for manipulating the Co adatom on a Cu(5 5 4) surface is proposed. The optimum tip height for a successful lateral manipulation is determined and the reliability of the lateral manipulation of the adatom on the stepped surface is assessed

  12. Study on surface modification of M2 steel induced by Cu ions and Al ions implantation

    International Nuclear Information System (INIS)

    Wang Chao; Liu Zhengmin

    2001-01-01

    Changes of surface hardness and wear resistances in M2 type steel implanted by Cu Al ions were reported. The dependence of surface strengthening on ion species and dose was studied by X-ray diffraction (XRD) and Rutherford Backscattering Spectroscopy (RBS) for microhardness and wear resistances measurement. It is shown that both hardness and wear resistance increases apparently after ion implantation. XRD analysis indicates that different phases formed after Al Cu ions implanted. It is also suggested that Cu, Al ions have different role in surface strengthening

  13. Can Any Surface Species On Meteoritic Nanodiamonds Survive The Extraction Procedure: Simulation Study

    Science.gov (United States)

    Koscheev, A. P.; Serzhantov, A. E.; Merchel, S.; Ott, U.; Guillois, O.; Reynaud, C.

    Information on the surface chemistry of interstellar diamond nanograins found in me- teorites is important for at least two reasons: 1) Diamond surface species may be responsible for some of the IR features observed in emission spectra of some circum- stellar objects; 2) Some surface chemical features acquired during the long journey of the diamonds from the stellar source region to the laboratory may have survived and carry a signature of chemical processes in the interstellar medium. It is well known that the severe acidic treatment used to extract nanodiamonds from meteorites modi- fies some of their surface IR active chemical features. However, some relation between the surface chemistry of nanodiamonds before and after treatment (memory effect) could not be excluded. The existence of such a relation hardly can be established using meteoritic diamond grains because of their uncertain initial properties. To overcome this problem we used ultradispersed detonation diamonds (UDD) with different initial surface chemistry as analogs of meteoritic ones. Five different samples of UDD were treated by the same chemical procedure used to separate meteoritic diamonds. The surface species both before and after treatment were studied by complementary meth- ods of IR spectroscopy and thermodesorption mass spectrometry. Our results strongly indicate that, even though the chemical extraction procedure affects the surface chem- istry of UDD, some surface features can either survive partially (CHx-groups) or vary in a manner controlled by the initial state (CO-groups). If this is also true in the case of meteoritic nanodiamonds, our observations may open a way to reproduce to some extent the real surface chemistry of presolar diamonds from data on chemically sepa- rated meteoritic diamonds. The work was supported in part by Russian Foundation for Basic Research (Grant #01-05-65416), DFG and the Department of Foreign Affairs of France.

  14. Dental implant surfaces after insertion in bone: an in vitro study in four commercial implant systems.

    Science.gov (United States)

    Deppe, Herbert; Wolff, Carolina; Bauer, Florian; Ruthenberg, Ricarda; Sculean, Anton; Mücke, Thomas

    2017-10-24

    Primary healing of dental implants is influenced by their surface morphology. However, little is known about any alterations in morphology during their insertion. Therefore, the aim of this study was to evaluate the surface morphology of four different implant systems, following their insertion in porcine jaw bones. Four fresh porcine mandible specimens were used. Six new implants of four systems (Ankylos® 4.5 × 14 mm, Frialit Synchro® 4.5 × 15 mm, NobelReplace ® Tapered Groovy RP 4.3 × 13 mm, Straumann SLA® Bone Level 3.3 × 14 mm) were inserted, whereas one implant of each system served as a control. After their removal, implants were cleaned in an ultrasonic bath. All 28 implants were examined quantitatively by 3D confocal microscopy for surface characteristics. In the evaluated zones, implants of the Ankylos, Frialit, and Straumann systems showed mostly a reduction of the mean surface roughness Sa, the maximal surface roughness Sz, and the developed surface area ratio Sdr; Nobel implants showed an increase in these parameters. With respect to all three parameters Sa, Sz, and Sdr, statistical analysis revealed that differences between the four systems were highly significant in the apical region of implants. Controls showed no morphologic alterations. The insertion process had an impact on the surface of all four implant systems. Anodized implant surface modification seems to result in more alterations compared with subtractive surface modifications. Therefore, surgical planning should take into consideration the choice of surface treatment because the characteristics of the implants may be modified during the installation process. The given information is of value for daily implantation practice and the course of osseointegration.

  15. Protein arrangement on modified diamond-like carbon surfaces – An ARXPS study

    International Nuclear Information System (INIS)

    Oosterbeek, Reece N.; Seal, Christopher K.; Hyland, Margaret M.

    2014-01-01

    Highlights: • DLC coatings were modified by Ar + ion sputtering and laser graphitisation. • The surface properties of the coatings were measured, and it was found that the above methods increased sp 2 content and altered surface energy. • ARXPS was used to observe protein arrangement on the surface. • Polar CO/CN groups were seen to be segregated towards the interface, indicating they play an important role in bonding. • This segregation increased with increasing polar surface energy, indicating an increased net attraction between polar groups. - Abstract: Understanding the nature of the interface between a biomaterial implant and the biological fluid is an essential step towards creating improved implant materials. This study examined a diamond-like carbon coating biomaterial, the surface energy of which was modified by Ar + ion sputtering and laser graphitisation. The arrangement of proteins was analysed by angle resolved X-ray photoelectron spectroscopy, and the effects of the polar component of surface energy on this arrangement were observed. It was seen that polar groups (such as CN, CO) are more attracted to the coating surface due to the stronger polar interactions. This results in a segregation of these groups to the DLC–protein interface; at increasing takeoff angle (further from to DLC–protein interface) fewer of these polar groups are seen. Correspondingly, groups that interact mainly by dispersive forces (CC, CH) were found to increase in intensity as takeoff angle increased, indicating they are segregated away from the DLC–protein interface. The magnitude of the segregation was seen to increase with increasing polar surface energy, this was attributed to an increased net attraction between the solid surface and polar groups at higher polar surface energy (γ S p )

  16. Protein arrangement on modified diamond-like carbon surfaces – An ARXPS study

    Energy Technology Data Exchange (ETDEWEB)

    Oosterbeek, Reece N., E-mail: reece.oosterbeek@auckland.ac.nz [Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019 (New Zealand); Seal, Christopher K. [Light Metals Research Centre, The University of Auckland, Private Bag 92019 (New Zealand); Hyland, Margaret M. [Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019 (New Zealand)

    2014-12-01

    Highlights: • DLC coatings were modified by Ar{sup +} ion sputtering and laser graphitisation. • The surface properties of the coatings were measured, and it was found that the above methods increased sp{sup 2} content and altered surface energy. • ARXPS was used to observe protein arrangement on the surface. • Polar CO/CN groups were seen to be segregated towards the interface, indicating they play an important role in bonding. • This segregation increased with increasing polar surface energy, indicating an increased net attraction between polar groups. - Abstract: Understanding the nature of the interface between a biomaterial implant and the biological fluid is an essential step towards creating improved implant materials. This study examined a diamond-like carbon coating biomaterial, the surface energy of which was modified by Ar{sup +} ion sputtering and laser graphitisation. The arrangement of proteins was analysed by angle resolved X-ray photoelectron spectroscopy, and the effects of the polar component of surface energy on this arrangement were observed. It was seen that polar groups (such as CN, CO) are more attracted to the coating surface due to the stronger polar interactions. This results in a segregation of these groups to the DLC–protein interface; at increasing takeoff angle (further from to DLC–protein interface) fewer of these polar groups are seen. Correspondingly, groups that interact mainly by dispersive forces (CC, CH) were found to increase in intensity as takeoff angle increased, indicating they are segregated away from the DLC–protein interface. The magnitude of the segregation was seen to increase with increasing polar surface energy, this was attributed to an increased net attraction between the solid surface and polar groups at higher polar surface energy (γ{sub S}{sup p})

  17. Study of GaSb and AlSb surface superstructures based on the (100) planes

    International Nuclear Information System (INIS)

    Lubyshev, D.I.; Gonzalez-Borrero, P.P.; Marega Junior, E.; La Scala Junior, N.; Basmaji, P

    1995-01-01

    Full text. Surface superstructure (SS) on semiconductor surfaces determines properties like Schottky barrier heights, vacancy densities and surface adatom migration length at the molecular beam epitaxy (MBE). In this work we have studied the evolution of surface structures as function of the substrate temperature on the (100) Al Sb and Ga Sb by RHEED analysis. Atomic smooth surfaces were produced by MBE on the (100) Ga As substrates. As the temperature of the Sb-rich surfaces of Al Sb and Ga Sb increases from the room temperature, it is observed that the surface superstructure is changed to the (4 x 2)metal stabilized one. On the Ga Sb (100) surfaces were observed the following number of SS: the (2 x 5)Sb-stabilized, (1 x 3) and (2 x 4)Ga stabilized SS. The phase transition from the (2 x 5)Sb-stabilized SS to (1 x 3) ones goes through unusual changing of superstructure strike positions. This can be explained considering the SS rotation during the phase transition relatively to the bulk lattice. The strike intensities for different azimuths of the (2 x 5)SS are altered in a factor 2, indicating a lower SS ordering across the domain axe (x2). On the Al Sb surfaces the following SS sequence were detected: at low temperature there is a superposition of the (6 x 1) and (2 x 1) SS, at higher temperatures (3 x 1), (3 x 3) and (2 x 4)Al-stabilized structures. We have supposed that the low temperature SS (6 x 1)+(2 x 1) have more than one monolayer coverage by Sb. We have also observed form the first time evidences of mixed surface superstructures (6 x 1)+(2 x 1) and SS (3 x 3). (author)

  18. Er:YAG laser scaling of diseased root surfaces: a histologic study.

    Science.gov (United States)

    Crespi, Roberto; Barone, Antonio; Covani, Ugo

    2006-02-01

    The aim of the present study was to observe the effects of an erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser when used to treat periodontally involved root surfaces. Forty teeth affected by severe periodontal disease and scheduled for extraction were divided into two groups: in group A (control), 20 teeth were treated by hand instrumentation, and in group B (test), 20 teeth were treated by Er:YAG laser. In group A (teeth treated by curets), the root cementum layer was completely removed, but many deep scratches on the dentin layer were also observed. In group B, the laser-treated root surfaces, there was no cracking or carbonization, and the bacterial flora was completely eliminated, leaving a rough and uniform surface. Results of the present study showed that clinical use of an Er:YAG laser in vivo achieves plaque and calculus removal, providing a rough surface morphology.

  19. Chemical stability and surface stoichiometry of vanadium oxide phases studied by reactive molecular dynamics simulations

    Science.gov (United States)

    Jeon, Byoungseon; Ko, Changhyun; van Duin, Adri C. T.; Ramanathan, Shriram

    2012-02-01

    Compositional stability of various vanadium oxides and oxide growth on vanadium surfaces have been studied using reactive molecular dynamics simulation methods. Vanadium dioxide (VO2), sesquioxide (V2O3), pentoxide (V2O5), and hexavanadium tridecaoxide (V6O13) are studied in bulk crystalline and thin film structures, investigating charge distribution and pair distribution functions of particle interactions. The stability is estimated to be pentoxide, hexavanadium tridecaoxide, sesquioxide, and dioxide respectively in decreasing order in thin film structures. We then analyze oxide growth kinetics on vanadium (100) and (110) surfaces. The oxidation rate, stoichiometry, charge distribution, and the effect of surface orientation on kinetic phenomena are noted. In the early stages of surface oxidation of our simulation configurations, sesquioxide is found to be the dominant component. The modeling and simulation results are compared with experiments where available.

  20. Adsorption of Ti on LiAlH4 surfaces studied by band structure calculations

    International Nuclear Information System (INIS)

    Loevvik, O.M.

    2004-01-01

    LiAlH 4 is a potential light-weight hydrogen storage material if hydrogenation can be made reversible. In NaAlH 4 this may be done by adding small amounts of Ti, but the same effect has not yet been observed in LiAlH 4 . To understand these mechanisms, detailed studies of the materials with and without the additive are necessary. In this study, two-dimensional slabs representing the open (0 1 0) and densely packed (1 0 1) surfaces of LiAlH 4 have been used to model adsorption of titanium atoms on those surfaces. The results show that the Ti atom tends to move below the surface towards interstitial sites rather than binding to a Li ion or AlH 4 complex at the surface

  1. Structure and reactivity of heterogeneous surfaces and study of the geometry of surface complexes. Progress report, January 1, 1984-December 31, 1984

    International Nuclear Information System (INIS)

    Landman, U.

    1984-01-01

    Since the beginning of this project, our group has been involved in theoretical studies of surface phenomena and processes, aimed toward increasing our understanding of fundamental processes which govern the properties of material surfaces. Our studies cover a wide spectrum of surface phenomena: surface reactivity, surface crystallography, electronic and vibrational structure, dynamical processes, phase transformations and phase change, the properties of interfaces and investigations of material processing and novel materials preparation techniques. In these investigations we develop and employ analytical and novel numerical, simulation, methods for the study of complex surface phenomena. Our recent surface molecular dynamics studies and simulations of laser annealing phenomena opened new avenues for the investigation of the microscopic dynamics and evolution of equilibrium and non-equilibrium processes at surfaces and interfaces. Our current studies of metallic glasses using a new langrangian formulation which includes all components of the total energy (density dependent electron gas, single particle and pair interactions) of the system, represents a novel approach for theoretical studies of this important class of systems

  2. Study on the state of a surface of compounds of vanadium with light elements

    International Nuclear Information System (INIS)

    Povstugar, V.I.; Mikhajlova, S.S.; Trapeznikov, V.A.

    1976-01-01

    Roentgenoelectron study of powderlike compounds of vanadium with light elements (C, N, O, S) was carried out. The study was made in the temperature range of 70-500 deg C. The results were obtained in an electron magnetic spectrometer. Spectra of inner levels O 1S and V 2p and valance bands are presented. The experimental results can be employed for the study of synthesis problems of the given class of compounds. Due to high surface activity the study of catalytic properties of finely dispersed vanadium compounds by roentgenoelectron spectroscopy method gives much information about surface processes

  3. Inflammatory response to titanium surfaces with fibrinogen and catalase coatings: an in vitro study.

    Science.gov (United States)

    Göransson, A; Gretzer, C; Tengvall, P; Wennerberg, A

    2007-03-01

    The aim of the present study was to evaluate the possibility to modulate the early inflammatory response in vitro by coating titanium surfaces with candidate proinflammatory (fibrinogen coated turned titanium "Fib") and antiinflammatory proteins (catalase on top of fibrinogen coated turned titanium "Cat"). Additionally, turned titanium surfaces (Ti) were used as controls. The discs were incubated with human mononuclear cells. Adhered cells were investigated with respect to number, viability, differentiation (acute marker 27E10 vs. chronic marker RM3/1), and cytokine production (TNF-alpha and IL-10), after 24 and 72 h. The results indicated that it is possible to modulate the inflammatory response with protein coatings. However, the strongest inflammatory response, indicated by increased number of adhered cells and release of pro and antiinflammatory mediators, was induced by Cat. Furthermore, the cytokine production on this surface was not sensitive to LPS stimulation. Differentiation measured as the expression of the chronic cell surface marker, dominated after 72 h for all surface modifications and Cat displayed an increased number compared to the others. A decrease in the total number of adhered cells and amounts of TNF-alpha were observed on all surfaces over time. The cell viability was, in general, high for all tested surfaces. In conclusion, the study proved it possible to influence the early inflammatory response in vitro by immobilizing protein coatings to titanium surfaces. However, the catalase surface demonstrated the strongest inflammatory response, and the possibility to selectively use the potent antiinflammatory capacity of catalase needs to be further evaluated.

  4. Experimental studies of photon-surface interaction dynamics in the alkali halides

    International Nuclear Information System (INIS)

    Haglund, R.F. Jr.; Tolk, N.H.

    1986-01-01

    We describe recent measurements which have provided, in unprecedented detail, insights into the electronic mechanisms through which energy carried into a material by photon irradiation is absorbed, localized and rechanneled to produce desorption, surface modification, erosion and damage. The specific object of these studies has been desorption induced by electronic transition in alkali halide crystals, with particular emphasis on the dynamics of changes in the surface and near-surface regions. In our experiments, the irradiating ultraviolet photons are provided by a synchrotron storage ring, and the dynamical information about desorption products is obtained from optical measurements of the quantum states, yields and velocity distributions of neutral ground-state and excited-state atoms ejected from the surface of the irradiating material. These studies have shown that the dominant exit channels in photon-induced particle emission are those producing ground-state and excited-state neutral atoms. Using dynamical information about these desorbing neutral species, obtained, for example, by laser-induced fluorescence and laser Doppler spectroscopy, we are generating an increasingly comprehensive picture of the dynamics of electronic energy flow into and out of pure crystalline surfaces in these prototypical dielectrics. We are also beginning to be able to relate desorption dynamics to specific materials properties, and to discriminate between pure surface and near-surface effects in these materials. Applications of these techniques to the problem of photon-induced surface damage and to analysis of surface dynamics in dielectric materials are discussed, and the relationships between these nearly ideal model materials and the non-crystalline, covalently bonded materials more typical of real optical elements are pointed out. 19 refs., 13 figs

  5. A comparative study of frictional resistance and surface roughness between orthodontic bracket and arch wire

    OpenAIRE

    Kazuro, SATOH; Masaru, ISHIGAME; Yukiko, NAKAMURA; Kazushi, OGASAWARA; Shigeru, TANAKA; Hiroyuki, MIURA; Department of Orthodontics, School of Dentistry, Iwate Medical University; Department of Orthodontics, School of Dentistry, Iwate Medical University; Department of Orthodontics, School of Dentistry, Iwate Medical University; Department of Orthodontics, School of Dentistry, Iwate Medical University; Department of Orthodontics, School of Dentistry, Iwate Medical University; Department of Orthodontics, School of Dentistry, Iwate Medical University

    2003-01-01

    The frictional resistance between an orthodontic bracket and arch wire is closely related to the efficiency of tooth movement in sliding mechanics. Frictional resistance may arise from the materials, geometrical configuration between the orthodontic bracket and arch wire, ligation system and its force, wire stiffness, direction and degree of orthodontic force, and surface roughness of bracket and wire. This study examined the relationship between the frictional resistance and surface roughnes...

  6. Conventional and acoustic surface plasmons on noble metal surfaces: a time-dependent density functional theory study

    DEFF Research Database (Denmark)

    Yan, Jun; Jacobsen, Karsten W.; Thygesen, Kristian S.

    2012-01-01

    First-principles calculations of the conventional and acoustic surface plasmons (CSPs and ASPs) on the (111) surfaces of Cu, Ag, and Au are presented. The effect of s-d interband transitions on both types of plasmons is investigated by comparing results from the local density approximation...

  7. Adhesion of bubbles and drops to solid surfaces, and anisotropic surface tensions studied by capillary meniscus dynamometry

    NARCIS (Netherlands)

    Danov, Krassimir D.; Stanimirova, Rumyana D.; Kralchevsky, Peter A.; Marinova, Krastanka G.; Stoyanov, Simeon D.; Blijdenstein, Theodorus B.J.; Cox, Andrew R.; Pelan, Eddie G.

    2016-01-01

    Here, we review the principle and applications of two recently developed methods: the capillary meniscus dynamometry (CMD) for measuring the surface tension of bubbles/drops, and the capillary bridge dynamometry (CBD) for quantifying the bubble/drop adhesion to solid surfaces. Both methods are

  8. SURFACE SITES AND MOBILITIES OF IN ATOMS ON A STEPPED CU(100) SURFACE STUDIED AT LOW COVERAGE

    NARCIS (Netherlands)

    BREEMAN, M; DORENBOS, G; BOERMA, DO

    The various surface sites of In atoms deposited to a coverage of 0.013 monolayer (ML) onto a stepped Cu(100) surface were determined with low-energy ion scattering (LEIS) as a function of deposition temperature. From the fractions of In atoms occupying different sites, observed in the temperature

  9. Adhesion and friction of polymer surfaces studied using scanning probe microscopy

    Science.gov (United States)

    Moon, Seung-Ho

    2003-10-01

    Scanning Probe Microscopy has been utilized to investigate the nanomechanical and nanorheological properties at the surface of polymers and polymer blends. To study the surface behavior in detail, it is critical that the SPM instrument have sufficient flexibility. A temperature stage and environmental chamber have been implemented and measurement automation has been achieved using a high-speed data acquisition system controlled by LabView(TM). Finally, new measurement protocols, "X-modulation" and "Force-Distance with X-modulation", have been developed. First measurements using those techniques have been performed for the study of aged model pressure sensitive adhesives. It has been found that the magnitude of the lateral force is so sensitive to adhesion force that X-modulation can identify qualitative differences in the strength of surface stickiness. Variations in surface adhesiveness with humidity are more obvious when the tackifier is present. A large lateral force and strongly reduced stiffness, measured using F-d with X-modulation, have been observed at high humidity for the homogeneous, hydrophilic surface of the adhesive loaded with 60wt% tackifier. These observations are consistent with a model that envisions a tackifier-enriched region near the surface. A large creep effect has also been observed for this sample, and the creep effect is magnified with temperature. These results are consistent with the hypothesis that at a hydrophilic adhesive surface water molecules may strongly alter the surface-tip interactions or modify the mechanical properties of the material nearest the surface. By changing the Z-loading velocity, dynamic adhesion behavior has been investigated. The mechanism of adhesive failure have been elucidated by comparing the velocity dependence of pull-off force and lateral force. Since this dynamic measurement is sensitive to the material composition at the surface, it has been utilized to study the surface segregation of one component at

  10. [Clinical and microbiological study regarding surface antibacterial properties of bioactive dental materials].

    Science.gov (United States)

    Târcă, T; Bădescu, Aida; Topoliceanu, C; Lăcătuşu, St

    2010-01-01

    In the new era of dentistry the coronal restoration materials must possess "bio-active" features represented by fluor ions release, chemical adhesion and antibacterial agents. Our study aims to determine the surface antibacterial properties of glassionomer cements and compomers. The study group included 64 patients with high cariogenic risk with 80 teeth with acute and chronic dental caries affecting proximal and occlusal dental surfaces. The teeth with cariogenic lesions were restored with zinc-oxide-eugenol (n=20), glassionomer cement GC Fuji Triage (n=20), glassionomer cement modified with resins Fuji II LC (n=20), compomer Dyract (n=20). DENTOCULT SM test (Orion Diagnostica, Finland) was used for bacterial analyses. The samples from bacterial biofilm were collected from the restorated dental surfaces (study group) and intact enamel surfaces (control group). The recorded data were processed using non-parametrical statistical tests. The lowest mean value of bacterial indices was recorded for glassionomer cement Fuji Triage (0.4), and Fuji II LC (1.2), material with highest surface antibacterial properties. The highest value (1.5) was recorded for compomer Dyract. The Kruskal-Wallis test proves the significant statistical differences between the three bioactive materials. The materials with bioactive features have the ability to inhibate the growth of Streptococcus mutans in bacterial biofilm to the surfaces of coronal restoration.

  11. Scanning Tunneling Microscopy Studies of Surface Structures of Icosahedral Al-Cu-Fe Quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Tanhong [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    Three papers are included in this dissertation. The first paper: ''Structural aspects of the fivefold quasicrystalline Al-Cu-Fe surface from STM and dynamical LEED studies'', is in press with ''Surface Science''. The second paper: ''An STM study of the atomic structure of the icosahedral Al-Cu-Fe fivefold surface'' is submitted to ''Physical Review B, Rapid Communication''. The third paper: ''Pseudomorphic starfish: arrangement of extrinsic metal atoms on a quasicrystalline substrate'' is submitted to ''Nature''. Following the third paper are general conclusions and appendices that document the published paper ''Structural aspects of the three-fold surface of icosahedral Al-Pd-Mn'' (appearing in volume 461, issue 1-3 of ''Surface Science'' on page L521-L527, 2000), the design as well as the specifications of the aluminum evaporator used in the aluminum deposition study in this dissertation, an extended discussion of the aluminum deposition on the quasicrystalline surface, and the STM database.

  12. Experimental studies of the stress state of the surface layer of detailat treatment with submerged jets

    Directory of Open Access Journals (Sweden)

    Олександр Олександрович Анділахай

    2015-03-01

    Full Text Available In the instrument and electrical industry was the use of the method of abrasive machining submerged jet, which is the most promising method for abrasive blasting of small parts of low stiffness. This method eliminates the main drawback сhip plants - abrasion channel nozzles or injection nozzles, but the state of the surface layer of machined parts are poorly understood and to make maximum use of the potential to provide the required quality parameters. The study of the state of the surfaces of parts resulting from abrasive blasting traditional methods, dedicated work, which define quality indicators: microhardness depth residual stress, as well as their nature (compressive, tensile. However, known from the literature values correspond to the conditions of surface treatment of parts in a fixed state with an abrasive material through the feed nozzle, and therefore the dynamics of the interaction of a single abrasive grain and significantly different parts. The process in question, and different modes of processing characteristics of the abrasive grains. In the paper, a series of experimental studies designed to assess the state of machined surfaces of parts as a result of abrasion submerged jets. It is established that during the treatment the non-oriented disorderly traces overlay the abrasive grains on the treated surface, thereby forming a tight skin layer thickness of 4 - 5 micrometers. Processed surface gets cold working, as evidenced by the study of microhardness before and after abrasive machining in a free state submerged jets

  13. Near Surface Stoichiometry in UO2: A Density Functional Theory Study

    Directory of Open Access Journals (Sweden)

    Jianguo Yu

    2015-01-01

    Full Text Available The mechanisms of oxygen stoichiometry variation in UO2 at different temperature and oxygen partial pressure are important for understanding the dynamics of microstructure in these crystals. However, very limited experimental studies have been performed to understand the atomic structure of UO2 near surface and defect effects of near surface on stoichiometry in which the system can exchange atoms with the external reservoir. In this study, the near (110 surface relaxation and stoichiometry in UO2 have been studied with density functional theory (DFT calculations. On the basis of the point-defect model (PDM, a general expression for the near surface stoichiometric variation is derived by using DFT total-energy calculations and atomistic thermodynamics, in an attempt to pin down the mechanisms of oxygen exchange between the gas environment and defected UO2. By using the derived expression, it is observed that, under poor oxygen conditions, the stoichiometry of near surface is switched from hyperstoichiometric at 300 K with a depth around 3 nm to near-stoichiometric at 1000 K and hypostoichiometric at 2000 K. Furthermore, at very poor oxygen concentrations and high temperatures, our results also suggest that the bulk of the UO2 prefers to be hypostoichiometric, although the surface is near-stoichiometric.

  14. U-Zr alloy: XPS and TEM study of surface passivation

    Science.gov (United States)

    Paukov, M.; Tkach, I.; Huber, F.; Gouder, T.; Cieslar, M.; Drozdenko, D.; Minarik, P.; Havela, L.

    2018-05-01

    Surface reactivity of Uranium metal is an important factor limiting its practical applications. Bcc alloys of U with various transition metals are much less reactive than pure Uranium. So as to specify the mechanism of surface protection, we have been studying the U-20 at.% Zr alloy by photoelectron spectroscopy and transmission electron microscopy. The surface was studied in as-obtained state, in various stages of surface cleaning, and during an isochronal annealing cycle. The analysis based on U-4f, Zr-3p, and O-1 s spectra shows that a Zr-rich phase segregates at the surface at temperatures exceeding 550 K, which provides a self-assembled coating. The comparison of oxygen exposure of the stoichiometric and coated surfaces shows that the coating is efficiently preventing the oxidation of uranium even at elevated temperatures. The coating can be associated with the UZr2+x phase. TEM study indicated that the coating is about 20 nm thick. For the clean state, the U-4f core-level lines of the bcc alloy are practically identical to those of α-U, revealing similar delocalization of the 5f electronic states.

  15. Comprehensive study of flow and heat transfer at the surface of circular cooling fin

    Science.gov (United States)

    Mityakov, V. Yu; Grekov, M. A.; Gusakov, A. A.; Sapozhnikov, S. Z.; Seroshtanov, V. V.; Bashkatov, A. V.; Dymkin, A. N.; Pavlov, A. V.; Milto, O. A.; Kalmykov, K. S.

    2017-11-01

    For the first time is proposed to combine heat flux measurements with thermal imaging and PIV (particle image velocimetry) for a comprehensive study of flow and heat transfer at the surface of the circular cooling fin. The investigated hollow fin is heated from within with saturated water steam; meanwhile the isothermal external surface simulates one of the perfect fin. Flow and heat transfer at the surface of the solid fin of the same size and shape, made of titanium alloy is investigated in the same regimes. Gradient Heat Flux Sensors (GHFS) were installed at different places of the fin surface. Velocity field around a cylinder, temperature field at the surface of the fin and heat flux for each rated time were obtained. Comprehensive method including heat flux measurement, PIV and thermal imaging allow to study flow and heat transfer at the surface of the fin in real time regime. The possibility to study flow and heat transfer for non-isothermal fins is shown; it is allow to improve traditional calculation of the cooling fins.

  16. Study on the Effectiveness of Infiltration Wells to Reduce Excess Surface Run Off In ITB

    Directory of Open Access Journals (Sweden)

    Mardiah Afifah Muhsinatu

    2018-01-01

    Full Text Available Institut Teknologi Bandung (ITB, Ganesha Campus, Indonesia, has an area of 28.86 hectares. The campus is located in Bandung. Starting from 2012, new buildings were constructed within the area, reducing the area of permeable surface significantly. In the past few years, there were several excess run off incidents in the campus. The insufficient area of permeable surface as well as the inadequate capacity of the drainage system contributes to the excess surface run off. The drainage system has only two outlets. Moreover, in some areas, the drainage systems are disconnected. Thus, most the surface run off are stored within the drainage system. The purpose of this study is to evaluate the effectiveness of infiltration wells for reducing the local excess run off in ITB. Precipitation data and drained service area are used to estimate the design discharge from each building in ITB. In order to avoid the excess surface run off of certain locations in ITB, then the infiltration wells are proposed to balance the area of impermeable surface. The effectiveness of the infiltration wells are evaluated by assessing their number to their contribution in reducing the excess surface runs off.

  17. Study on the influence of helical milling parameters on surface roughness of titanium alloy

    Directory of Open Access Journals (Sweden)

    Chunhui JI

    2015-06-01

    Full Text Available As a new technology, helical milling has been widely used in hole-making of titanium alloy, and the surface roughness is an important indicator for evaluating the quality of titanium alloy hole. In this paper, the helical milling experiments are carried out to study the effect of machining parameters on the surface roughness with the model established in Matlab. It is proved that the model can well predict the influence of the helical milling parameters on surface roughness. With screw pitch increasing, the surface roughness of titanium hole firstly decreases and then increases in the range of 0.15~0.25 mm/rev. However, the surface roughness increases gradually at first and then decreases with the increasing of the feed per tooth in the range of 0.03~0.05 mm/tooth. Similarly, with the increasing of spindle speed, the surface roughness firstly increases, then decreases, and again gradually increases smoothly in the range of 2 500~3 500 r/min. The results in the work can provide experimental basis for optimizing cutting parameters and decreasing surface roughness in helical milling process.

  18. The nucleus of Comet Borrelly: A study of morphology and surface brightness

    Science.gov (United States)

    Oberst, J.; Howington-Kraus, E.; Kirk, R.; Soderblom, L.; Buratti, B.; Hicks, M.; Nelson, R.; Britt, D.

    2004-01-01

    Stereo images obtained during the DS1 flyby were analyzed to derive a topographic model for the nucleus of Comet 19P/Borrelly for morphologic and photometric studies. The elongated nucleus has an overall concave shape, resembling a peanut, with the lower end tilted towards the camera. The bimodal character of surface-slopes and curvatures support the idea that the nucleus is a gravitational aggregate, consisting of two fragments in contact. Our photometric modeling suggests that topographic shading effects on Borrelly's surface are very minor (the given resolution of the terrain model. Instead, albedo effects are thought to dominate Borrelly's large variations in surface brightness. With 90% of the visible surface having single scattering albedos between 0.008 and 0.024, Borrelly is confirmed to be among the darkest of the known Solar System objects. Photometrically corrected images emphasize that the nucleus has distinct, contiguous terrains covered with either bright or dark, smooth or mottled materials. Also, mapping of the changes in surface brightness with phase angle suggests that terrain roughness at subpixel scale is not uniform over the nucleus. High surface roughness is noted in particular near the transition between the upper and lower end of the nucleus, as well as near the presumed source region of Borrelly's main jets. Borrelly's surface is complex and characterized by distinct types of materials that have different compositional and/or physical properties. ?? 2003 Elsevier Inc. All rights reserved.

  19. Semiautomatic construction of isobase surfaces: A case study from the central Western Carpathians

    Science.gov (United States)

    Jedlička, Karel; Sládek, Ján; Šilhavý, Jakub

    2015-05-01

    This article describes a method for semiautomated construction of isobase surfaces in the environment of a Geomorphological Information System (GmIS). The motivation to automate the process is that the manual construction of isobase surfaces involves several decision procedures, and also a lot of manual vectorization which can be time-consuming if the area of interest is large. A (semi-)automated process of isobase surface construction could accelerate the process of morphostructural analysis. Therefore, the contribution focuses on design, development and testing of such a method. The developed tools were compared to an expert driven construction of isobase surfaces. The automatically constructed data layers were compared to the layers that were constructed manually in the southwest part of the study area (Turčianska kotlina basin (Western Carpathians) and surrounding area in Slovakia). Three different statistical methods were used (correlation, linear regression and DTM volume difference checking). All three methods proved very high similarity of automatically created isobase surfaces to expert driven isobase surfaces creation. The results show that the method of semiautomated creation can be used in morphostructure analysis and save the time needed for manual isobase surface creation. The method's technological background is based on the ESRI platform. The original desktop solution has been developed for use on a client/server architecture that is able to present the capabilities of GmIS to a wider geomorphological audience.

  20. Optical properties study of silicone polymer PDMS substrate surfaces modified by plasma treatment

    Science.gov (United States)

    Zahid, A.; Dai, B.; Hong, R.; Zhang, D.

    2017-10-01

    In this study, PDMS (polydimethylsiloxane) substrates with a half-plain, half-rough surface were prepared on a plain and rough fused silica glass substrate using a molding technique. The molded PDMS surface morphology was changed into a half-smooth and half-rough surface after peeling. The modified PDMS surfaces’ optical properties were inspected with and without treatment. The treatment is exposed by oxygen plasma (15 W) for 3 min in a vacuum, down to a pressure of six torr, using a vacuum pump. An atomic force microscope (AMF) and interferometer (white light) indicated that the plasma O2 treatment increased the formation of the plain surface and decreased the formation of the rough surface. The optical properties via a spectrophotometer (lambda) show the resonance from 300 nm to 1200 nm on the rough surface, which is considered to be a faithful reproduction for transmittance and reflectance. The Raman spectra and FDTD simulation results are in excellent agreement; not to be confused with metal local surface plasmon resonances (LSPRs). The Raman spectra peaks and hotspot are the results of the PDMS Si-O backbone. The PDMS substrate presented the diversity of the optical properties, which makes the substrate complementary to various optical applications.