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Sample records for surface conditions halfway

  1. Northern Youth Abroad Finding a place at home, halfway around the ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-03-09

    Mar 9, 2011 ... Northern Youth Abroad Finding a place at home, halfway around the ... Past volunteer sites have included game reserves, an orphan care ... The Government of Nunavut has a mandate to employ 80% Inuit in its public service.

  2. Pattern of disability among persons who availed half-way home-care services for psychosocial rehabilitation

    Directory of Open Access Journals (Sweden)

    M Ranganathan

    2012-01-01

    Full Text Available Background: There is dearth of studies related to pattern of disability among persons who availed psychosocial rehabilitation services in India. We studied the pattern of disability among persons who availed half-way home-care services for psychosocial rehabilitation. Materials and Methods: Out of 130 case files of discharged patients, 50 files were randomly selected for data collection. Indian Disability Evaluation and Assessment Schedule was used to assess the pattern of disability in the sample. Results: The study revealed that only one-third (35% of the residents had disability in self-care, 41% in communication and understanding and 47% in interpersonal relationship. Overall, majority (76% of the respondents had moderate level of psychiatric disability at the time of discharge from half-way home. There was no significant relationship between gender and type of psychiatric illness with the level of disability. The overall disability correlated positively with the duration of illness (rs=0.39. Conclusion: Three-fourth of the residents who availed half-way home-care services had moderate level of disability.

  3. The dipoles reach the half-way mark

    CERN Multimedia

    2006-01-01

    With the positioning of the 616th magnet, installation of the LHC dipoles has reached the half-way mark. Only half the dipoles remain to be installed! The 616th dipole out of a total of 1232 was installed at 3 a.m on Wednesday 12 July. Night and day, the tunnel is the setting for a never-ending series of carefully choreographed installation operations. At a rate of around twenty per week, there has been a steady underground flow of dipole magnets, each measuring 15 metres in length and weighing 34 tonnes. 'In order to recover the accumulated delays, installation is proceeding three times faster than planned', confides Claude Hauviller, who is supervising LHC installation. Four dipoles can be transported underground at the same time. It is a real challenge, which the 65-man team responsible for this difficult task faces on a daily basis. This is because there is very little space in the tunnel and there are no passing places for the magnet transport vehicles. The room for manoeuvre can sometimes be measured ...

  4. Sedimentation History Of Halfway Creek Marsh, Upper Mississippi River National Wildlife And Fish Refuge, Wisconsin, 1846-2006. Scientific Investigations Report 2007–5209

    Science.gov (United States)

    The history of overbank sedimentation in the vicinity of Halfway Creek Marsh near La Crosse, Wisconsin, was examined during 2005-06 by the U.S. Geological Survey and University of Wisconsin-Madison as part of a broader study of sediment and nutrient loadings to the Upper Mississi...

  5. The street school Srikandi as an empowerment model of humane education for the street girls of non halfway house in Surabaya

    Science.gov (United States)

    Setyowati, RRN; Yani, MT; Imron, A.

    2018-01-01

    The street children have not had a solid emotional mental, however they must deal into the life of street that harsh, competitive and tend to affect negatively for their personality development. Their where abouts on the street is not motivated by family economic factor only, but it is also influenced by the disharmony of role and function of family rules and social environment influences. The street children empowerment that had been conducted by the halfway house does not run effectively. This research was aimed to identify problems faced by the street girls, to describe the efforts to overcome the problems faced by the street girls, and also developing the empowerment model for the street girls in Surabaya who do not stay in the halfway house. This research used qualitative method. The problems are often experienced by the street girls, for instance violence. Besides, imitative behavior arises as a respond towards behavior that happened to them. The parents also play role in the process of social control. The empowerment model that is designed is the educational empowerment through revitalization of family rules. Moreover, life skills education has to be strengthened to improve the welfare standard of living.

  6. Samen kom je er wel. Een afstudeerartikel over het Skejby halfway house: een huis waar delinquenten en studenten onder één dak wonen

    Directory of Open Access Journals (Sweden)

    Eline Broker

    2016-03-01

    Full Text Available Together you will get there. A graduation article on the Skejby halfway house: a house where delinquents and students live togetherThe Skejby house is unique and produces remarkable results. The recidivism percentage among its’ delinquent inhabitants is over 20% lower than in the halfway houses where only prisoners reside. The aim of Skejby is to ease the transition between imprisonment and reentry in society. The experiment, in which students and prisoners live together, originates from the idea that behavioral transformation is realized most effectively within a socially engaged group. The principal of collective responsibility is dominant in Skejby, resulting in a feeling of belonging to a group among the delinquents. In this group, the students serve as prosocial role models. Consequently, the standards and values that are picked up in prison are reshaped into much needed skills that are required for living a “regular” life in society. In contrast to the reintegration program in Skejby, the Dutch reintegration program mainly consists of one-to-one consultations between the delinquent and the probation officer. The reintegration thus does not take place in a group to which the delinquent can relate, while it is precisely this unique communal feeling of belonging that induces behavioral change in the prisoners. SAMENVATTING Samen kom je er wel. Een afstudeerartikel over het Skejby halfway house: een huis waar delinquenten en studenten onder één dak wonenHet Skejby house is uniek in zijn soort en boekt opmerkelijke resultaten: het recidivepercentage ligt ruim 20% lager dan bij halfway huizen waar alleen delinquenten wonen. Skejby heeft als doel om de overgang tussen gevangenis en samenleving zo klein mogelijk te maken. Het experiment, waarbij studenten en delinquenten samen wonen, komt voort uit het idee dat gedragsverandering het best bewerkstelligt wordt binnen een sociaal verbonden groep. In Skejby heerst het principe van

  7. Effect of surface wettability caused by radiation induced surface activation on leidenfrost condition

    International Nuclear Information System (INIS)

    Takamasa, T.; Hazuku, T.; Tamura, N.; Okamoto, K.; Mishima, K.; Furuya, M.

    2003-01-01

    Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high-wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. From this basis, we investigated surface wettability and Leidenfrost condition using metal oxides irradiated by γ-rays. In our previous study, contact angle, an indicator of macroscopic wettability, of a water droplet on metal oxide at room temperature was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on metal oxide pieces of titanium, Zircaloy No. 4, SUS-304, and copper was improved significantly by the Radiation Induced Surface Activation (RISA) phenomenon. To delineate the effect of Radiation Induced Surface Activation (RISA) on heat transferring phenomena, the Leidenfrost condition and quenching of metal oxides irradiated by γ-rays were investigated. In the Leidenfrost experiment, when the temperature of the heating surface reached the wetting limit temperature, water-solid contact vanished because a stable vapor film existed between the droplet and the metal surface; i.e., a Leidenfrost condition obtained. The wetting limit temperature increased with integrated irradiation dose. After irradiation, the wet length and the duration of contact increased, and the contact angle decreased. In the quenching test, high surface wettability, or a highly hydrophilic condition, of a simulated fuel rod made of SUS was achieved, and the quenching velocities were increased up to 20-30% after 300 kGy 60Co γ-ray irradiation

  8. Effect of surface wettability caused by radiation induced surface activation on leidenfrost condition

    Energy Technology Data Exchange (ETDEWEB)

    Takamasa, T.; Hazuku, T.; Tamura, N.; Okamoto, K. [Tokyo Univ., Tokyo (Japan); Mishima, K. [Kyoto Univ., Kyoto (Japan); Furuya, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

    2003-07-01

    Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high-wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. From this basis, we investigated surface wettability and Leidenfrost condition using metal oxides irradiated by {gamma}-rays. In our previous study, contact angle, an indicator of macroscopic wettability, of a water droplet on metal oxide at room temperature was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on metal oxide pieces of titanium, Zircaloy No. 4, SUS-304, and copper was improved significantly by the Radiation Induced Surface Activation (RISA) phenomenon. To delineate the effect of Radiation Induced Surface Activation (RISA) on heat transferring phenomena, the Leidenfrost condition and quenching of metal oxides irradiated by {gamma}-rays were investigated. In the Leidenfrost experiment, when the temperature of the heating surface reached the wetting limit temperature, water-solid contact vanished because a stable vapor film existed between the droplet and the metal surface; i.e., a Leidenfrost condition obtained. The wetting limit temperature increased with integrated irradiation dose. After irradiation, the wet length and the duration of contact increased, and the contact angle decreased. In the quenching test, high surface wettability, or a highly hydrophilic condition, of a simulated fuel rod made of SUS was achieved, and the quenching velocities were increased up to 20-30% after 300 kGy 60Co {gamma}-ray irradiation.

  9. Effect of surface conditions on blast wave propagation

    International Nuclear Information System (INIS)

    Song, Seung Ho; Li, Yi Bao; Lee, Chang Hoon; Choi, Jung Il

    2016-01-01

    We performed numerical simulations of blast wave propagations on surfaces by solving axisymmetric two-dimensional Euler equations. Assuming the initial stage of fireball at the breakaway point after an explosion, we investigated the effect of surface conditions considering surface convex or concave elements and thermal conditions on blast wave propagations near the ground surface. Parametric studies were performed by varying the geometrical factors of the surface element as well as thermal layer characteristics. We found that the peak overpressure near the ground zero was increased due to the surface elements, while modulations of the blast wave propagations were limited within a region for the surface elements. Because of the thermal layer, the precursor was formed in the propagations, which led to the attenuation of the peak overpressure on the ground surface

  10. Surface free energy for systems with integrable boundary conditions

    International Nuclear Information System (INIS)

    Goehmann, Frank; Bortz, Michael; Frahm, Holger

    2005-01-01

    The surface free energy is the difference between the free energies for a system with open boundary conditions and the same system with periodic boundary conditions. We use the quantum transfer matrix formalism to express the surface free energy in the thermodynamic limit of systems with integrable boundary conditions as a matrix element of certain projection operators. Specializing to the XXZ spin-1/2 chain we introduce a novel 'finite temperature boundary operator' which characterizes the thermodynamical properties of surfaces related to integrable boundary conditions

  11. Effect of multipactor conditioning on technical electrode surfaces

    International Nuclear Information System (INIS)

    Graves, T. P.; Spektor, R.; Stout, P.

    2009-01-01

    Historically, multipactor conditioning has been utilized to remove surface contaminants from rf electrodes by electron-stimulated gas desorption, and such conditioning has been shown to reduce multipactor susceptibility. Multipactor threshold improvements are due to increasing E 1 , the minimum energy for the secondary electron coefficient, δ>1, such that resonant electrons are incapable of producing discharge-sustaining secondary emission. Using an rf amplitude sweep technique, the evolution of the multipactor threshold is measured as a function of multipactor conditioning time for a series of technical electrode surfaces. Results show over +3 dB of threshold improvement in copper and gold electrodes, while the aluminum threshold actually decreases with conditioning exposure. Additionally, these conditioning results indicate the possible voltage region for transient-mode multipaction (TMM), which can cause significant risk to rf systems such as space satellite components for which in-situ conditioning is generally not possible. Experimental results and supporting Monte Carlo particle tracking simulation results are presented.

  12. Alcoholic fermentation under oenological conditions. Use of a combination of data analysis and neural networks to predict sluggish and stuck fermentations

    Energy Technology Data Exchange (ETDEWEB)

    Insa, G. [Inst. National de la Recherche Agronomique, Inst. des Produits de la Vigne, Lab. de Microbiologie et Technologie des Fermentations, 34 - Montpellier (France); Sablayrolles, J.M. [Inst. National de la Recherche Agronomique, Inst. des Produits de la Vigne, Lab. de Microbiologie et Technologie des Fermentations, 34 - Montpellier (France); Douzal, V. [Centre National du Machinisme Agricole du Genie Rural des Eaux et Forets, 92 - Antony (France)

    1995-09-01

    The possibility of predicting sluggish fermentations under oenological conditions was investigated by studying 117 musts of different French grape varieties using an automatic device for fermentation monitoring. The objective was to detect sluggish or stuck fermentations at the halfway point of fermentation. Seventy nine percent of fermentations were correctly predicted by combining data analysis and neural networks. (orig.)

  13. Well Conditioned Formulations for Open Surface Scattering

    National Research Council Canada - National Science Library

    Ottusch, John J; Visher, John L

    2008-01-01

    .... This report describes an analytical preconditioner method for the EFIE on open surface PEC targets that converts the EFIE to a well conditioned, second-kind integral equation. We present theory and the results from a numerical implementation. We also discuss a 2d extension of the Poincare-Bertrand identity could be used to develop an explicitly second-kind integral equation for open surface scattering problems.

  14. Spectroscopic study of cystine adsorption on pyrite surface: From vacuum to solution conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Arenillas, M.; Mateo-Marti, E., E-mail: mateome@cab.inta-csic.es

    2015-09-08

    Highlights: • Successful adsorption of cystine on pyrite surface under several conditions. • Detailed XPS spectroscopic characterization of cystine adsorption on pyrite surface. • Spectroscopy evidence, oxidation and anoxic conditions adjust molecular adsorption. • Molecular chemistry on pyrite is driven depending on the surrounding conditions. • The cystine/pyrite(100) model is in good agreement with Wächtershäuser’s theory. - Abstract: We characterized the adsorption of cystine molecules on pyrite surface via X-ray photoelectron spectroscopy. Anoxic conditions were simulated under ultra-high-vacuum conditions. In contrast, to simulate oxidation conditions, the molecules were adsorbed on pyrite surface from solution. A novel comparative analysis revealed remarkable differences with respect to molecular adsorption and surface chemistry induced by environmental conditions. Molecular adsorption under anoxic conditions was observed to be more favorable, concentrating a large number of molecules on the surface and two different chemical species. In contrast, the presence of oxygen induced an autocatalytic oxidation process on the pyrite surface, which facilitated water binding on pyrite surface and partially blocked molecular adsorption. Pyrite is a highly reactive surface and contains two crucial types of surface functional groups that drive molecular chemistry on the surface depending on the surrounding conditions. Therefore, the system explored in this study holds interesting implications for supporting catalyzed prebiotic chemistry reactions.

  15. Spectroscopic study of cystine adsorption on pyrite surface: From vacuum to solution conditions

    International Nuclear Information System (INIS)

    Sanchez-Arenillas, M.; Mateo-Marti, E.

    2015-01-01

    Highlights: • Successful adsorption of cystine on pyrite surface under several conditions. • Detailed XPS spectroscopic characterization of cystine adsorption on pyrite surface. • Spectroscopy evidence, oxidation and anoxic conditions adjust molecular adsorption. • Molecular chemistry on pyrite is driven depending on the surrounding conditions. • The cystine/pyrite(100) model is in good agreement with Wächtershäuser’s theory. - Abstract: We characterized the adsorption of cystine molecules on pyrite surface via X-ray photoelectron spectroscopy. Anoxic conditions were simulated under ultra-high-vacuum conditions. In contrast, to simulate oxidation conditions, the molecules were adsorbed on pyrite surface from solution. A novel comparative analysis revealed remarkable differences with respect to molecular adsorption and surface chemistry induced by environmental conditions. Molecular adsorption under anoxic conditions was observed to be more favorable, concentrating a large number of molecules on the surface and two different chemical species. In contrast, the presence of oxygen induced an autocatalytic oxidation process on the pyrite surface, which facilitated water binding on pyrite surface and partially blocked molecular adsorption. Pyrite is a highly reactive surface and contains two crucial types of surface functional groups that drive molecular chemistry on the surface depending on the surrounding conditions. Therefore, the system explored in this study holds interesting implications for supporting catalyzed prebiotic chemistry reactions

  16. Paragenetic evolution of reservoir facies, Middle Triassic Halfway Formation, PeeJay Field, northeastern British Columbia: controls on reservoir quality

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, M. L. [Alberta Univ., Dept. of Earth and Atmospheric Sciences, Edmonton, AB (Canada); Moslow, T. F. [Ulster Petroleum Ltd., Calgary, AB (Canada)

    1998-09-01

    Because of the obvious importance of reservoir quality to reservoir performance, diagenetic controls on reservoir quality of Middle Triassic reservoir facies are investigated by comparing two reservoir lithofacies. The implications of porosity structure on the efficiency of primary and secondary hydrocarbon recovery are also assessed. Halfway reservoir facies are composed of bioclastic grainstones (lithofacies G) and litharenites/sublitharenites (lithofacies H), both of which are interpreted as tidal inlet fills. Although paragenetic evolution was similar for the two reservoir facies, subtle differences in reservoir quality are discernible. These are controlled by sedimentary structures, porosity type, grain constituents, and degree of cementation. Reservoir quality in lithofacies G is a function of connectivity of the pore network. In lithofacies H, secondary granular porosity creates a more homogeneous interconnected pore system, wide pore throats and low aspect ratios. The high porosity and low permeability values of the bioclastic grainstones are suspected to cause inefficient flushing of hydrocarbons during waterflooding. However, it is suggested that recovery may be enhanced by induced hydraulic fracturing and acidization of lower permeability calcareous cemented zones. 52 refs., 15 figs.

  17. Statistical optimization of cultural conditions by response surface ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-08-04

    Aug 4, 2009 ... Full Length Research Paper. Statistical optimization of cultural conditions by response surface methodology for phenol degradation by a novel ... Phenol is a hydrocarbon compound that is highly toxic, ... Microorganism.

  18. LEP Dismantling Reaches Half-Way Stage

    CERN Multimedia

    2001-01-01

    LEP's last superconducting module leaves its home port... Just seven months into the operation, LEP dismantling is forging ahead. Two of the eight arcs which form the tunnel have already been emptied and the last of the accelerator's radiofrequency (RF) cavities has just been raised to the surface. The 160 people working on LEP dismantling have reason to feel pleased with their progress. All of the accelerator's 72 superconducting RF modules have already been brought to the surface, with the last one being extracted on 2nd May. This represents an important step in the dismantling process, as head of the project, John Poole, explains. 'This was the most delicate part of the project, because the modules are very big and they could only come out at one place', he says. The shaft at point 1.8 through which the RF cavity modules pass is 18 metres in diameter, while each module is 11.5 metres long. Some modules had to travel more than 10 kilometres to reach the shaft. ... is lifted up the PM 1.8 shaft, after a m...

  19. Characteristics of modified martensitic stainless steel surfaces under tribocorrosion conditions

    International Nuclear Information System (INIS)

    Rozing, Goran; Marusic, Vlatko; Alar, Vesna

    2017-01-01

    Stainless steel samples were tested in the laboratory and under real conditions of tribocorrosion wear. Electrochemical tests were also carried out to verify the corrosion resistance of modified steel surfaces. Metallographic analysis and hardness testing were conducted on stainless steel samples X20Cr13 and X17CrNi16 2. The possibilities of applications of modified surfaces of the selected steels were investigated by testing the samples under real wear conditions. The results have shown that the induction hardened and subsequently nitrided martensitic steels achieved an average wear resistance of up to three orders of magnitude higher as compared to the delivered condition.

  20. Characteristics of modified martensitic stainless steel surfaces under tribocorrosion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Rozing, Goran [Osijek Univ. (Croatia). Chair of Mechanical Engineering; Marusic, Vlatko [Osijek Univ. (Croatia). Dept. of Engineering Materials; Alar, Vesna [Zagreb Univ. (Croatia). Dept. Materials

    2017-04-01

    Stainless steel samples were tested in the laboratory and under real conditions of tribocorrosion wear. Electrochemical tests were also carried out to verify the corrosion resistance of modified steel surfaces. Metallographic analysis and hardness testing were conducted on stainless steel samples X20Cr13 and X17CrNi16 2. The possibilities of applications of modified surfaces of the selected steels were investigated by testing the samples under real wear conditions. The results have shown that the induction hardened and subsequently nitrided martensitic steels achieved an average wear resistance of up to three orders of magnitude higher as compared to the delivered condition.

  1. Assimilation and High Resolution Forecasts of Surface and Near Surface Conditions for the 2010 Vancouver Winter Olympic and Paralympic Games

    Science.gov (United States)

    Bernier, Natacha B.; Bélair, Stéphane; Bilodeau, Bernard; Tong, Linying

    2014-01-01

    A dynamical model was experimentally implemented to provide high resolution forecasts at points of interests in the 2010 Vancouver Olympics and Paralympics Region. In a first experiment, GEM-Surf, the near surface and land surface modeling system, is driven by operational atmospheric forecasts and used to refine the surface forecasts according to local surface conditions such as elevation and vegetation type. In this simple form, temperature and snow depth forecasts are improved mainly as a result of the better representation of real elevation. In a second experiment, screen level observations and operational atmospheric forecasts are blended to drive a continuous cycle of near surface and land surface hindcasts. Hindcasts of the previous day conditions are then regarded as today's optimized initial conditions. Hence, in this experiment, given observations are available, observation driven hindcasts continuously ensure that daily forecasts are issued from improved initial conditions. GEM-Surf forecasts obtained from improved short-range hindcasts produced using these better conditions result in improved snow depth forecasts. In a third experiment, assimilation of snow depth data is applied to further optimize GEM-Surf's initial conditions, in addition to the use of blended observations and forecasts for forcing. Results show that snow depth and summer temperature forecasts are further improved by the addition of snow depth data assimilation.

  2. Using semi-variogram analysis for providing spatially distributed information on soil surface condition for land surface modeling

    Science.gov (United States)

    Croft, Holly; Anderson, Karen; Kuhn, Nikolaus J.

    2010-05-01

    The ability to quantitatively and spatially assess soil surface roughness is important in geomorphology and land degradation studies. Soils can experience rapid structural degradation in response to land cover changes, resulting in increased susceptibility to erosion and a loss of Soil Organic Matter (SOM). Changes in soil surface condition can also alter sediment detachment, transport and deposition processes, infiltration rates and surface runoff characteristics. Deriving spatially distributed quantitative information on soil surface condition for inclusion in hydrological and soil erosion models is therefore paramount. However, due to the time and resources involved in using traditional field sampling techniques, there is a lack of spatially distributed information on soil surface condition. Laser techniques can provide data for a rapid three dimensional representation of the soil surface at a fine spatial resolution. This provides the ability to capture changes at the soil surface associated with aggregate breakdown, flow routing, erosion and sediment re-distribution. Semi-variogram analysis of the laser data can be used to represent spatial dependence within the dataset; providing information about the spatial character of soil surface structure. This experiment details the ability of semi-variogram analysis to spatially describe changes in soil surface condition. Soil for three soil types (silt, silt loam and silty clay) was sieved to produce aggregates between 1 mm and 16 mm in size and placed evenly in sample trays (25 x 20 x 2 cm). Soil samples for each soil type were exposed to five different durations of artificial rainfall, to produce progressively structurally degraded soil states. A calibrated laser profiling instrument was used to measure surface roughness over a central 10 x 10 cm plot of each soil state, at 2 mm sample spacing. The laser data were analysed within a geostatistical framework, where semi-variogram analysis quantitatively represented

  3. Regularity conditions of the field on a toroidal magnetic surface

    International Nuclear Information System (INIS)

    Bouligand, M.

    1985-06-01

    We show that a field B vector which is derived from an analytic canonical potential on an ordinary toroidal surface is regular on this surface when the potential satisfies an elliptic equation (owing to the conservative field) subject to certain conditions of regularity of its coefficients [fr

  4. Repairability of Compomers with Different Methods of Surface Conditioning

    Directory of Open Access Journals (Sweden)

    P.Samimi

    2005-06-01

    Full Text Available Statement of Problem: Considering the cost and amount of time and also the quantity of tooth loss in the process of cavity preparation, repair of the restoration instead of itsreplacement would be much more efficient.Purpose: The aim of this study was to determine the effect of different methods of surface conditioning on the shear bond strength of repaired compomers.Materials and Methods: Sixty blocks of compomer were prepared in acrylic molds and then they were randomly divided into five groups of 12. Group I (control groupreceived no treatment. The remaining samples were immersed in 37 ºC distilled water for one week, then the surfaces were roughened with a coarse diamond bur. Samples ineach group were prepared by different surface treatment and conditioning: In group II specimens were conditioned with 35% phosphoric acid for 20s. Specimens in group III were etched with 10% polyacrylic acid for 20s. In group IV 1.23% acidulated phosphatefluoride was applied for 30s, and compomer surfaces were sandblasted with 50μm Al2O3 powder in group V. After the initial preparations, all groups were treated with silane and resin before bonding of the second mix of compomer. Shear forces were applied with a universal testing machine at a cross-head speed of 5mm/min. The data were analyzed using one-way ANOVA and Duncan's multiple range tests.Results: The mean shear bond strengths and standard deviations (in parentheses for groups I to V were 31.56(10.86, 20.02(5.49, 17.74(7.34, 19.31(4.31 and 27.7(6.33MPa, respectively. The mean bond strengths for Groups I and V were significantly higher than that of the other groups (P<0.05.Conclusion: The results showed that among the surface treatments used in this study,sandblasting with alumina could be the best surface preparation method for repairing compomer restorations.

  5. Osteogenic potential of laser modified and conditioned titanium zirconium surfaces

    Directory of Open Access Journals (Sweden)

    P David Charles

    2016-01-01

    Full Text Available Statement of Problem: The osseointegration of dental implant is related to their composition and surface treatment. Titanium zirconium (TiZr has been introduced as an alternative to the commercially pure titanium and its alloys as dental implant material, which is attributed to its superior mechanical and biological properties. Surface treatments of TiZr have been introduced to enhance their osseointegration ability; however, reliable, easy to use surface modification technique has not been established. Purpose: The purpose of this study was to evaluate and compare the effect of neodymium-doped yttrium aluminum garnet (Nd-YAG laser surface treatment of TiZr implant alloy on their osteogenic potential. Materials and Methods: Twenty disc-shaped samples of 5 mm diameter and 2 mm height were milled from the TiZr alloy ingot. The polished discs were ultrasonically cleaned in distilled water. Ten samples each were randomly selected as Group A control samples and Group B consisted of Nd-YAG laser surface etched and conditioned test samples. These were evaluated for cellular response. Cellular adhesion and proliferation were quantified, and the results were statistically analyzed using nonparametric analysis. Cellular morphology was observed using electron and epiflurosence microscopy. Results: Nd-YAG laser surface modified and conditioned TiZr samples increased the osteogenic potential. Conclusion: Nd-YAG laser surface modification of TiZr, improves the cellular activity, surface roughness, and wettability, thereby increasing the osteogenic potential.

  6. Characterizing Pavement Surface Distress Conditions with Hyper-Spatial Resolution Natural Color Aerial Photography

    Directory of Open Access Journals (Sweden)

    Su Zhang

    2016-05-01

    Full Text Available Roadway pavement surface distress information is critical for effective pavement asset management, and subsequently, transportation management agencies at all levels (i.e., federal, state, and local dedicate a large amount of time and money to routinely evaluate pavement surface distress conditions as the core of their asset management programs. However, currently adopted ground-based evaluation methods for pavement surface conditions have many disadvantages, like being time-consuming and expensive. Aircraft-based evaluation methods, although getting more attention, have not been used for any operational evaluation programs yet because the acquired images lack the spatial resolution to resolve finer scale pavement surface distresses. Hyper-spatial resolution natural color aerial photography (HSR-AP provides a potential method for collecting pavement surface distress information that can supplement or substitute for currently adopted evaluation methods. Using roadway pavement sections located in the State of New Mexico as an example, this research explored the utility of aerial triangulation (AT technique and HSR-AP acquired from a low-altitude and low-cost small-unmanned aircraft system (S-UAS, in this case a tethered helium weather balloon, to permit characterization of detailed pavement surface distress conditions. The Wilcoxon Signed Rank test, Mann-Whitney U test, and visual comparison were used to compare detailed pavement surface distress rates measured from HSR-AP derived products (orthophotos and digital surface models generated from AT with reference distress rates manually collected on the ground using standard protocols. The results reveal that S-UAS based hyper-spatial resolution imaging and AT techniques can provide detailed and reliable primary observations suitable for characterizing detailed pavement surface distress conditions comparable to the ground-based manual measurement, which lays the foundation for the future application

  7. Materials surface modification by plasma bombardment under simultaneous erosion and redeposition conditions

    International Nuclear Information System (INIS)

    Hirooka, Y.; Goebel, D.M.; Conn, R.W.

    1986-07-01

    The first in-depth investigation of surface modification of materials by continuous, high-flux argon plasma bombardment under simultaneous erosion and redeposition conditions have been carried out for copper and 304 stainless steel using the PISCES facility. The plasma bombardment conditions are: incident ion flux range from 10 17 to 10 19 ions sec -1 cm -2 , total ion fluence is controlled between 10 19 and 10 22 ions cm -2 , electron temperature range from 5 to 15 eV, and plasma density range from 10 11 to 10 13 cm -3 . The incident ion energy is 100 eV. The sample temperature is between 300 and 700K. Under redeposition dominated conditions, the material erosion rate due to the plasma bombardment is significantly smaller (by a factor up to 10) than that can be expected from the classical ion beam sputtering yield data. It is found that surface morphologies of redeposited materials strongly depend on the plasma bombardment condition. The effect of impurities on surface morphology is elucidated in detail. First-order modelings are implemented to interpret the reduced erosion rate and the surface evolution. Also, fusion related surface properties of redeposited materials such as hydrogen reemission and plasma driven permeation have been characterized

  8. Nanoparticle growth and surface chemistry changes in cell-conditioned culture medium.

    Science.gov (United States)

    Kendall, Michaela; Hodges, Nikolas J; Whitwell, Harry; Tyrrell, Jess; Cangul, Hakan

    2015-02-05

    When biomolecules attach to engineered nanoparticle (ENP) surfaces, they confer the particles with a new biological identity. Physical format may also radically alter, changing ENP stability and agglomeration state within seconds. In order to measure which biomolecules are associated with early ENP growth, we studied ENPs in conditioned medium from A549 cell culture, using dynamic light scattering (DLS) and linear trap quadrupole electron transfer dissociation mass spectrometry. Two types of 100 nm polystyrene particles (one uncoated and one with an amine functionalized surface) were used to measure the influence of surface type. In identically prepared conditioned medium, agglomeration was visible in all samples after 1 h, but was variable, indicating inter-sample variability in secretion rates and extracellular medium conditions. In samples conditioned for 1 h or more, ENP agglomeration rates varied significantly. Agglomerate size measured by DLS was well correlated with surface sequestered peptide number for uncoated but not for amine coated polystyrene ENPs. Amine-coated ENPs grew much faster and into larger agglomerates associated with fewer sequestered peptides, but including significant sequestered lactose dehydrogenase. We conclude that interference with extracellular peptide balance and oxidoreductase activity via sequestration is worthy of further study, as increased oxidative stress via this new mechanism may be important for cell toxicity. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  9. Testing of newly developed functional surfaces under pure sliding conditions

    DEFF Research Database (Denmark)

    Godi, Alessandro; Mohaghegh, Kamran; Grønbæk, J.

    2013-01-01

    the surfaces in an industrial context. In this paper, a number of experimental tests were performed using a novel test rig, called axial sliding test, simulating the contact of surfaces under pure sliding conditions. The aim of the experiments is to evaluate the frictional behavior of a new typology...... of textured surfaces, the so-called multifunctional surfaces, characterized by a plateau area able to bear loads and a deterministic pattern of lubricant pockets. Six surface typologies, namely three multifunctional and three machined using classical processes, were chosen to slide against a mirror....... The results comparison showed clearly how employing multifunctional surfaces can reduce friction forces up to 50 % at high normal loads compared to regularly ground or turned surfaces. Friction coefficients approximately equal to 0.12 were found for classically machined surfaces, whereas the values were 0...

  10. Wear Behavior of Medium Carbon Steel with Biomimetic Surface Under Starved Lubricated Conditions

    Science.gov (United States)

    Zhang, Zhihui; Shao, Feixian; Liang, Yunhong; Lin, Pengyu; Tong, Xin; Ren, Luquan

    2017-07-01

    Friction and wear under starved lubrication condition are both key life-related factors for mechanical performance of many structural parts. In this paper, different surface morphologies on medium carbon steel were fabricated using laser, inspired by the surface coupling effect of biological system. The friction and sliding wear behaviors of biomimetic specimens (characterized by convex and concave units on the specimen surface) were studied under starved lubrication condition. The stress distribution on different sliding surfaces under sliding friction was studied using finite element method. The results showed that the tribological performance of studied surfaces under starved lubrication condition depended not only on the surface morphology but also on the structure of biomimetic units below surface (subsurface structure). The friction coefficient of biomimetic surface was effectively reduced by the concave unit depth, while the refined microstructure with higher hardness led to the much better wear resistance. In addition to lubricant reserving and wear debris trapping effect derived from the surface concave morphology, it was believed that the well-formed subsurface structure of biomimetic units could carry much heavy loads against tribopair, which enhanced the function of surface topography and resulted in complementary lubrication in the wear contact area. The uniform stress distribution on the entire biomimetic surface also played an important role in stabilizing the friction coefficient and reducing the wear cracks.

  11. Mucosal detail at CT virtual reality: surface versus volume rendering.

    Science.gov (United States)

    Hopper, K D; Iyriboz, A T; Wise, S W; Neuman, J D; Mauger, D T; Kasales, C J

    2000-02-01

    To evaluate computed tomographic virtual reality with volumetric versus surface rendering. Virtual reality images were reconstructed for 27 normal or pathologic colonic, gastric, or bronchial structures in four ways: the transition zone (a) reconstructed separately from the wall by using volume rendering; (b) with attenuation equal to air; (c) with attenuation equal to wall (soft tissue); (d) with attenuation halfway between air and wall. The four reconstructed images were randomized. Four experienced imagers blinded to the reconstruction graded them from best to worst with predetermined criteria. All readers rated images with the transition zone as a separate structure as overwhelmingly superior (P Virtual reality is best with volume rendering, with the transition zone (mucosa) between the wall and air reconstructed as a separate structure.

  12. 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...

  13. Surface layer conditions of the atmosphere over western Bay of Bengal during Monex

    Digital Repository Service at National Institute of Oceanography (India)

    Anto, A.F.; Rao, L.V.G.; Somayajulu, Y.K.

    Based on surface meteorological data and wave data collected from 2 stations in the western Bay of Bengal in July 1979, surface layer (SL) conditions of the atmosphere for different situations of surface circulations and the associated sea surface...

  14. Skating on thin ice: surface chemistry under interstellar conditions

    Science.gov (United States)

    Fraser, H.; van Dishoeck, E.; Tielens, X.

    Solid CO2 has been observed towards both active star forming regions and quiescent clouds (Gerakines et. al. (1999)). The high abundance of CO2 in the solid phase, and its low abundance in the gas phase, support the idea that CO2 is almost exclusively formed in the solid state. Several possible formation mechanisms have been postulated (Ruffle &Herbst (2001): Charnley &Kaufman (2000)), and the detection of CO2 towards quiescent sources such as Elias 16 (Whittet et. al. (1998)) clearly suggests that CO2 can be produced in the absence of UV or electron mediated processes. The most likely route is via the surface reactions between O atoms, or OH radicals, and CO. The tools of modern surface- science offer us the potential to determine many of the physical and chemical attributes of icy interstellar grain mantles under highly controlled conditions, that closely mimic interstellar environments. The Leiden Surface Reaction Simulation Device ( urfreside) combines UHV (UltraS High Vacuum) surface science techniques with an atomic beam to study chemical reactions occurring on the SURFACE and in the BULK of interstellar ice grain mimics. By simultaneously combining two or more surface analysis techniques, the chemical kinetics, reaction mechanisms and activation energies can be determined directly. The experiment is aimed at identifying the key barrierless reactions and desorption pathways on and in H2 O and CO ices under interstellar conditions. The results from traditional HV (high vacuum) and UHV studies of the CO + O and CO + OH reactions will be presented in this paper. Charnley, S.B., & Kaufman, M.J., 2000, ApJ, 529, L111 Gerakines, P.A., 1999, ApJ, 522, 357 Ruffle, D.P., & Herbst, E., 2001, MNRAS, 324, 1054 Whittet, D.C.B., et.al., 1998, ApJ, 498, L159

  15. Boundary conditions for free surface inlet and outlet problems

    KAUST Repository

    Taroni, M.; Breward, C. J. W.; Howell, P. D.; Oliver, J. M.

    2012-01-01

    We investigate and compare the boundary conditions that are to be applied to free-surface problems involving inlet and outlets of Newtonian fluid, typically found in coating processes. The flux of fluid is a priori known at an inlet, but unknown

  16. Tectonic controls on preservation of Middle Triassic Halfway reservoir facies, Peejay Field, northeastern British Columbia: a new hydrocarbon exploration model

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, M. L. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Geological Sciences; Moslow, T. F. [Calgary Univ., AB (Canada). Dept. of Geology and Geophysics

    1997-12-01

    The Peejay Field in northeastern British Columbia was chosen as the site of a detailed study to establish the paleogeography, geological history and genesis of reservoir facies of Middle Triassic strata. A total of 132 cores and well logs from 345 wells were examined to establish the depositional model, to identify the origin of all reservoir facies and to construct an exploration model to improve the prediction of reservoir facies. Results show that the Middle Triassic Halfway Formation of northeastern British Columbia is comprised of at least four west-southwest prograding paleoshorelines. The Lithofacies Succession One quartz-arenites paleoshore faces have less porosity and permeability and are laterally discontinuous. For these reasons shoreface facies have minimal reservoir quality. The tidal inlet fill successions were found to have the greatest observed porosity, permeability and lateral continuity in the Peejay Field. The geometry and orientation of these tidal inlet fill deposits are controlled by tectonic processes. It was suggested that the success of hydrocarbon exploration in this structurally complex area of northeastern British Columbia and west-central Alberta depends on further stratigraphic and sedimentological examination of Middle Triassic strata on a regional scale to obtain a complete understanding of the geological history of the area. 39 refs., 13 refs.

  17. Surface Acoustic Wave (SAW Resonators for Monitoring Conditioning Film Formation

    Directory of Open Access Journals (Sweden)

    Siegfried Hohmann

    2015-05-01

    Full Text Available We propose surface acoustic wave (SAW resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum albumin (HSA and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM sensor measurements, which confirmed the suitability of the SAW resonators for this application.

  18. Groundwater infiltration, surface water inflow and sewerage exfiltration considering hydrodynamic conditions in sewer systems.

    Science.gov (United States)

    Karpf, Christian; Hoeft, Stefan; Scheffer, Claudia; Fuchs, Lothar; Krebs, Peter

    2011-01-01

    Sewer systems are closely interlinked with groundwater and surface water. Due to leaks and regular openings in the sewer system (e.g. combined sewer overflow structures with sometimes reverse pressure conditions), groundwater infiltration and surface water inflow as well as exfiltration of sewage take place and cannot be avoided. In the paper a new hydrodynamic sewer network modelling approach will be presented, which includes--besides precipitation--hydrographs of groundwater and surface water as essential boundary conditions. The concept of the modelling approach and the models to describe the infiltration, inflow and exfiltration fluxes are described. The model application to the sewerage system of the City of Dresden during a flood event with complex conditions shows that the processes of infiltration, exfiltration and surface water inflows can be described with a higher reliability and accuracy, showing that surface water inflow causes a pronounced system reaction. Further, according to the simulation results, a high sensitivity of exfiltration rates on the in-sewer water levels and a relatively low influence of the dynamic conditions on the infiltration rates were found.

  19. A New Rig for Testing Textured Surfaces in Pure Sliding Conditions

    DEFF Research Database (Denmark)

    Godi, Alessandro; Grønbæk, J.; Mohaghegh, Kamran

    2013-01-01

    machineries are necessary: a press to provide the normal pressure and a tensile machine to perform the axial movements. The test is calibrated so that the correspondence between the normal pressure and the container advancement is found. Preliminary tests are carried out involving a multifunctional and a fine......Throughout the years, it has become more and more important to find new methods for reducing friction and wear occurrence in machine elements. A possible solution is found in texturing the surfaces under tribological contact, as demonstrated by the development and spread of plateau-honed surface...... for cylinder liners. To prove the efficacy of a particular textured surface, it is paramount to perform experimental tests under controlled laboratory conditions. In this paper, a new test rig simulating pure sliding conditions is presented, dubbed axial sliding test. It presents four major components: a rod...

  20. Modified hot-conditioning of PHT system surfaces of PHWRs

    Energy Technology Data Exchange (ETDEWEB)

    Venkateswaran, G [Bhabha Atomic Research Centre, Trombay, Bombay (India)

    1997-02-01

    The increased awareness on the importance of controlling activity transport and radiation buildup on out-of-core surfaces of water cooled nuclear reactors is leading to a host of measures both from chemistry as well as engineering sides being undertaken. Passivation of the surfaces of structural materials is one such. Pressurised Heavy Water Reactors of CANDU design use large surface area of carbon steel alloy in the Primary Heat Transport System. Hot-conditioning of the PHT system with deoxygenated light water at temperatures {approx_equal} 473 - 523 K during commissioning stage is done to form a protective magnetite film on the surfaces of carbon steel essentially to guard this material from corrosion during the intervening period between initial commissioning and first fuel loading and achieving nuclear heat. However, a need is felt to improve the quality of this magnetite film and control the crud release so that the twin objectives of controlling the corrosion of carbon steel and reducing a possible deposition of corrosion products on surfaces of fuel clad could be achieved. Laboratory static autoclave investigations have been carried out on the formation of protective magnetite film on carbon steel at 473 K, pH 10 (pH at 298 K) deoxygenated aqueous solutions of chelants like HEDTA, DTPA, NTA apart from EDTA. Additionally, influence of AVT chemicals like hydrazine, cyclohexylamine, morpholine and additives like glucose, boric acid has been studied. The data have been compared with the standard procedure of hot-conditioning namely with simple LiOH. It is found that chelants increase the base metal loss but the oxide formed is more protective than the one formed under simple LiOH treatment. The efficiency of passivation is greatly enhanced by hydrazine and boric acid while it is adversely affected by glucose. AVT chemicals acts as effective corrosion inhibitors. (author). 14 refs, 2 figs, 4 tabs.

  1. Modified hot-conditioning of PHT system surfaces of PHWRs

    International Nuclear Information System (INIS)

    Venkateswaran, G.

    1997-01-01

    The increased awareness on the importance of controlling activity transport and radiation buildup on out-of-core surfaces of water cooled nuclear reactors is leading to a host of measures both from chemistry as well as engineering sides being undertaken. Passivation of the surfaces of structural materials is one such. Pressurised Heavy Water Reactors of CANDU design use large surface area of carbon steel alloy in the Primary Heat Transport System. Hot-conditioning of the PHT system with deoxygenated light water at temperatures ≅ 473 - 523 K during commissioning stage is done to form a protective magnetite film on the surfaces of carbon steel essentially to guard this material from corrosion during the intervening period between initial commissioning and first fuel loading and achieving nuclear heat. However, a need is felt to improve the quality of this magnetite film and control the crud release so that the twin objectives of controlling the corrosion of carbon steel and reducing a possible deposition of corrosion products on surfaces of fuel clad could be achieved. Laboratory static autoclave investigations have been carried out on the formation of protective magnetite film on carbon steel at 473 K, pH 10 (pH at 298 K) deoxygenated aqueous solutions of chelants like HEDTA, DTPA, NTA apart from EDTA. Additionally, influence of AVT chemicals like hydrazine, cyclohexylamine, morpholine and additives like glucose, boric acid has been studied. The data have been compared with the standard procedure of hot-conditioning namely with simple LiOH. It is found that chelants increase the base metal loss but the oxide formed is more protective than the one formed under simple LiOH treatment. The efficiency of passivation is greatly enhanced by hydrazine and boric acid while it is adversely affected by glucose. AVT chemicals acts as effective corrosion inhibitors. (author). 14 refs, 2 figs, 4 tabs

  2. Interactions of hydroxyapatite surfaces: conditioning films of human whole saliva.

    Science.gov (United States)

    Cárdenas, Marité; Valle-Delgado, Juan José; Hamit, Jildiz; Rutland, Mark W; Arnebrant, Thomas

    2008-07-15

    Hydroxyapatite is a very interesting material given that it is the main component in tooth enamel and because of its uses in bone implant applications. Therefore, not only the characterization of its surface is of high relevance but also designing reliable methods to study the interfacial properties of films adsorbed onto it. In this paper we apply the colloidal probe atomic force microscopy method to investigate the surface properties of commercially available hydroxyapatite surfaces (both microscopic particles and macroscopic discs) in terms of interfacial and frictional forces. In this way, we find that hydroxyapatite surfaces at physiological relevant conditions are slightly negatively charged. The surfaces were then exposed to human whole saliva, and the surface properties were re-evaluated. A thick film was formed that was very resistant to mechanical stress. The frictional measurements demonstrated that the film was indeed highly lubricating, supporting the argument that this system may prove to be a relevant model for evaluating dental and implant systems.

  3. Influence of surface conditions in nucleate boiling--the concept of bubble flux density

    International Nuclear Information System (INIS)

    Shoukri, M.; Judd, R.L.

    1978-01-01

    A study of the influence of surface conditions in nucleate pool boiling is presented. The surface conditions are represented by the number and distribution of the active nucleation sites as well as the size and size distribution of the cavities that constitute the nucleation sites. The heat transfer rate during nucleate boiling is shown to be influenced by the surface condition through its effect on the number and distribution of the active nucleation sites as well as the frequency of bubble departure from each of these different size cavities. The concept of bubble flux density, which is a function of both the active site density and frequency of bubble departure, is introduced. A method of evaluating the bubble flux density is proposed and a uniform correlation between the boiling heat flux and the bubble flux density is found to exist for a particular solid-liquid combination irrespective of the surface finish within the region of isolated bubbles

  4. Cooling the vertical surface by conditionally single pulses

    Science.gov (United States)

    Karpov, Pavel; Nazarov, Alexander; Serov, Anatoly; Terekhov, Victor

    2017-10-01

    You Sprays with periodic supply of the droplet phase have great opportunities to control the heat exchange processes. Varying pulse duration and frequency of their repetition, we can achieve the optimal conditions of evaporative cooling with minimization of the liquid flow rate. The paper presents experimental data on studying local heat transfer on a large subcooled surface, obtained on the original setup with multinozzle controlled system of impact irrigation by the gas-droplet flow. A contribution to intensification of the spray parameters (flow rate, pulse duration, repetition frequency) per a growth of integral heat transfer was studied. Data on instantaneous distribution of the heat flux value helped us to describe the processes occurring on the studied surface. These data could describe the regime of "island" film cooling.

  5. Optimal condition for fabricating superhydrophobic Aluminum surfaces with controlled anodizing processes

    Science.gov (United States)

    Saffari, Hamid; Sohrabi, Beheshteh; Noori, Mohammad Reza; Bahrami, Hamid Reza Talesh

    2018-03-01

    A single step anodizing process is used to produce micro-nano structures on Aluminum (1050) substrates with sulfuric acid as electrolyte. Therefore, surface energy of the anodized layer is reduced using stearic acid modification. Undoubtedly, effects of different parameters including anodizing time, electrical current, and type and concentration of electrolyte on the final contact angle are systemically studied and optimized. Results show that anodizing current of 0.41 A, electrolyte (sulfuric acid) concentration of 15 wt.% and anodizing time of 90 min are optimal conditions which give contact angle as high as 159.2° and sliding angle lower than 5°. Moreover, the study reveals that adding oxalic acid to the sulfuric acid cannot enhance superhydrophobicity of the samples. Also, scanning electron microscopy images of samples show that irregular (bird's nest) structures present on the surface instead of high-ordered honeycomb structures expecting from normal anodizing process. Additionally, X-ray diffraction analysis of the samples shows that only amorphous structures present on the surface. The Brunauer-Emmett-Teller (BET) specific surface area of the anodized layer is 2.55 m2 g-1 in optimal condition. Ultimately, the surface keeps its hydrophobicity in air and deionized water (DIW) after one week and 12 weeks, respectively.

  6. Control of first-wall surface conditions in the 2XIIB Magnetic Mirror Plasma Confinement experiment

    International Nuclear Information System (INIS)

    Simonen, T.C.; Bulmer, R.H.; Coensgen, F.H.

    1976-01-01

    The control of first-wall surface conditions in the 2XIIB Magnetic Mirror Plasma Confinement experiment is described. Before each plasma shot, the first wall is covered with a freshly gettered titanium surface. Up to 5 MW of neutral beam power has been injected into 2XIIB, resulting in first-wall bombardment fluxes of 10 17 atoms . cm -2 . s -1 of 13-keV mean energy deuterium atoms for several ms. The background gas flux is measured with a calibrated, 11-channel, fast-atom detector. Background gas levels are found to depend on surface conditions, injected beam current, and beam pulse duration. For our best operating conditions, an efective reflex coefficient of 0.3 can be inferred from the measurements. Experiments with long-duration and high-current beam injection are limited by charge exchange; however, experiments with shorter beam duration are not limited by first-wall surface conditions. It is concluded that surface effects will be reduced further with smoother walls. (Auth.)

  7. Ions, metabolites, and cells: Water as a reporter of surface conditions during bacterial growth

    Science.gov (United States)

    Jarisz, Tasha A.; Lane, Sarah; Gozdzialski, Lea; Hore, Dennis K.

    2018-06-01

    Surface-specific nonlinear vibrational spectroscopy, combined with bulk solution measurements and imaging, is used to study the surface conditions during the growth of E. coli. As a result of the silica high surface charge density, the water structure at the silica-aqueous interface is known to be especially sensitive to pH and ionic strength, and surface concentration profiles develop that can be appreciably different from the bulk solution conditions. We illustrate that, in the presence of growing cells, a unique surface micro-environment is established as a result of metabolites accumulating on the silica surface. Even in the subsequent absence of the cells, this surface layer works to reduce the interfacial ionic strength as revealed by the enhanced signal from surface water molecules. In the presence of growing cells, an additional boost in surface water signal is attributed to a local pH that is higher than that of the bulk solution.

  8. Cooling the vertical surface by conditionally single pulses

    Directory of Open Access Journals (Sweden)

    Karpov Pavel

    2017-01-01

    Full Text Available You Sprays with periodic supply of the droplet phase have great opportunities to control the heat exchange processes. Varying pulse duration and frequency of their repetition, we can achieve the optimal conditions of evaporative cooling with minimization of the liquid flow rate. The paper presents experimental data on studying local heat transfer on a large subcooled surface, obtained on the original setup with multinozzle controlled system of impact irrigation by the gas-droplet flow. A contribution to intensification of the spray parameters (flow rate, pulse duration, repetition frequency per a growth of integral heat transfer was studied. Data on instantaneous distribution of the heat flux value helped us to describe the processes occurring on the studied surface. These data could describe the regime of “island” film cooling.

  9. Influence of surface condition on the corrosion resistance of copper alloy condenser tubes in sea water

    Energy Technology Data Exchange (ETDEWEB)

    Sato, S; Nagata, K; Yamauchi, S

    1979-07-01

    Investigation was made on the influence of various surface conditions of aluminum brass tube. The corrosion behavior of aluminum brass tube, with nine kinds of surface conditions, was studied in stagnant 0.1N NaHCo/sub 3/ solution and flowing sea water (natural, Fe/sup + +/ containing and S/sup - -/ containing water). Surface treatments investigated contained bright annealing, special annealing to form carbon film, hot oxidizing and pickling. Anodic polarization measurements in 0.1N NaHCO/sub 3/ solution showed that the oxidized surface was superior and that the pickled surface was inferior. However, relation between these characteristics and corrosion resistance in sea water has not been established. Electrochemical characteristics in flowing sea water were dependent on the surface conditions in the very beginning of immersion time; nobler corrosion potential for the surface with carbon film, higher polarization resistance for the bright annealed and the oxidized surface, and faster decrease of polarization resistance in S/sup - -/ containing sea water for the pickled surface. However, these differences disappeared in the immersion time of only 2 to 7 days. It was revealed, by the statistical analysis on the corrosion depth in corrosion test in flowing sea water and in jet impingement test, that the corrosion behavior was not influenced by surface conditions, but was significantly influenced by quality of sea water and sponge ball cleaning. Sulfide ion of 0.05 ppm caused severe pitting corrosion, and sponge ball cleaning of 5 chances a week caused erosion corrosion. From above results, it was concluded that surface conditions of aluminum brass were not important to sea water corrosion, and that quality of sea water and operating condition such as sponge ball cleaning were more significant.

  10. Stepping towards new parameterizations for non-canonical atmospheric surface-layer conditions

    Science.gov (United States)

    Calaf, M.; Margairaz, F.; Pardyjak, E.

    2017-12-01

    Representing land-atmosphere exchange processes as a lower boundary condition remains a challenge. This is partially a result of the fact that land-surface heterogeneity exists at all spatial scales and its variability does not "average" out with decreasing scales. Such variability need not rapidly blend away from the boundary thereby impacting the near-surface region of the atmosphere. Traditionally, momentum and energy fluxes linking the land surface to the flow in NWP models have been parameterized using atmospheric surface layer (ASL) similarity theory. There is ample evidence that such representation is acceptable for stationary and planar-homogeneous flows in the absence of subsidence. However, heterogeneity remains a ubiquitous feature eliciting appreciable deviations when using ASL similarity theory, especially in scalars such moisture and air temperature whose blending is less efficient when compared to momentum. The focus of this project is to quantify the effect of surface thermal heterogeneity with scales Ο(1/10) the height of the atmospheric boundary layer and characterized by uniform roughness. Such near-canonical cases describe inhomogeneous scalar transport in an otherwise planar homogeneous flow when thermal stratification is weak or absent. In this work we present a large-eddy simulation study that characterizes the effect of surface thermal heterogeneities on the atmospheric flow using the concept of dispersive fluxes. Results illustrate a regime in which the flow is mostly driven by the surface thermal heterogeneities, in which the contribution of the dispersive fluxes can account for up to 40% of the total sensible heat flux. Results also illustrate an alternative regime in which the effect of the surface thermal heterogeneities is quickly blended, and the dispersive fluxes provide instead a quantification of the flow spatial heterogeneities produced by coherent turbulent structures result of the surface shear stress. A threshold flow

  11. Conditions of rib design for polycarbonate resin with high glossy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Seong Won [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

    2013-10-15

    Much attention has been being given to the importance of product surfaces in the field of plastic parts, as industrial design has become one of the key elements of product success. These plastic parts incorporate rib-like geometries on the non-appearance surfaces of plastic in order to increase the stiffness of rigidity of the section, but they often cause appearance problems of the product's surface overall by making a sink mark on that surface. The thickness, height and draft-angle of the rib are generally known as major parameters influencing the sink mark on the appearance surface. Therefore, designers of plastic parts must determine the variables of reinforcing ribs. The goal of this study is to find the optimum design variables in the mixing conditions of the thickness, the height and the draft angle of reinforcing ribs so that designers of plastic parts can easily determine the conditions of the reinforcing ribs as the part's section thickness varies within an objective limit in polycarbonate plastic resin and a high glossy surface that are widely applied in the creation of plastic products. We investigated the actual depths of sink marks on the surface of a specimen that was manufactured with an injection mold specifically for this study. Response surface methodology with the Box-Behnken design was used to analyze the regression curve of real depths with combinations of the thickness, height and draft angle of the ribs. The result shows that the most influential factor to increase the shrinkage is the thickness of ribs and that the optimum value of the rib thickness is a range from multiple of 0.25 to 0.34 of the section thickness. Also, the rib height and rib draft angle are not major factors that can change the sink amount.

  12. Conditions of rib design for polycarbonate resin with high glossy surfaces

    International Nuclear Information System (INIS)

    Jeong, Seong Won

    2013-01-01

    Much attention has been being given to the importance of product surfaces in the field of plastic parts, as industrial design has become one of the key elements of product success. These plastic parts incorporate rib-like geometries on the non-appearance surfaces of plastic in order to increase the stiffness of rigidity of the section, but they often cause appearance problems of the product's surface overall by making a sink mark on that surface. The thickness, height and draft-angle of the rib are generally known as major parameters influencing the sink mark on the appearance surface. Therefore, designers of plastic parts must determine the variables of reinforcing ribs. The goal of this study is to find the optimum design variables in the mixing conditions of the thickness, the height and the draft angle of reinforcing ribs so that designers of plastic parts can easily determine the conditions of the reinforcing ribs as the part's section thickness varies within an objective limit in polycarbonate plastic resin and a high glossy surface that are widely applied in the creation of plastic products. We investigated the actual depths of sink marks on the surface of a specimen that was manufactured with an injection mold specifically for this study. Response surface methodology with the Box-Behnken design was used to analyze the regression curve of real depths with combinations of the thickness, height and draft angle of the ribs. The result shows that the most influential factor to increase the shrinkage is the thickness of ribs and that the optimum value of the rib thickness is a range from multiple of 0.25 to 0.34 of the section thickness. Also, the rib height and rib draft angle are not major factors that can change the sink amount.

  13. Condition Assessment for Wastewater Pipes: Method for Assessing Cracking and Surface Damage of Concrete Pipes

    OpenAIRE

    Hauge, Petter

    2013-01-01

    The objective of the Master Thesis has been to provide an improved method for condition assessment, which will give a better correlation between Condition class and actual Condition of concrete pipes with cracking and/or surface damages. Additionally improvement of the characterization of cracking (SR) and surface (KO) damages was a sub goal.Based on the findings described in my Thesis and my Specialization Project (Hauge 2012), I recommend that the Norwegian condition assessment method based...

  14. TBA biodegradation in surface-water sediments under aerobic and anaerobic conditions.

    Science.gov (United States)

    Bradley, Paul M; Landmeyer, James E; Chapelle, Francis H

    2002-10-01

    The potential for [U-14C] TBA biodegradation was examined in laboratory microcosms under a range of terminal electron accepting conditions. TBA mineralization to CO2 was substantial in surface-water sediments under oxic, denitrifying, or Mn(IV)-reducing conditions and statistically significant but low under SO4-reducing conditions. Thus, anaerobic TBA biodegradation may be a significant natural attenuation mechanism for TBA in the environment, and stimulation of in situ TBA bioremediation by addition of suitable terminal electron acceptors may be feasible. No degradation of [U-14C] TBA was observed under methanogenic or Fe(III)-reducing conditions.

  15. Adherence of platelets to in situ albumin-binding surfaces under flow conditions: role of surface-adsorbed albumin

    International Nuclear Information System (INIS)

    Guha Thakurta, Sanjukta; Miller, Robert; Subramanian, Anuradha

    2012-01-01

    Surfaces that preferentially bind human serum albumin (HSA) were generated by grafting albumin-binding linear peptide (LP1) onto silicon surfaces. The research aim was to evaluate the adsorption pattern of proteins and the adhesion of platelets from platelet-poor plasma and platelet-rich plasma, respectively, by albumin-binding surfaces under physiological shear rate (96 and 319 s −1 ) conditions. Bound proteins were quantified using enzyme-linked immunosorbent assays (ELISAs) and two-dimensional gel electrophoresis. A ratio of ∼1000:100:1 of adsorbed HSA, human immunoglobulin (HIgG) and human fibrinogen (HFib) was noted, respectively, on LP1-functionalized surfaces, and a ratio of ∼5:2:1 of the same was noted on control surfaces, as confirmed by ELISAs. The surface-adsorbed von Willebrand factor was undetectable by sensitive ELISAs. The amount of adhered platelets correlated with the ratio of adsorbed HSA/HFib. Platelet morphology was more rounded on LP1-functionalized surfaces when compared to control surfaces. The platelet adhesion response on albumin-binding surfaces can be explained by the reduction in the co-adsorption of other plasma proteins in a surface environment where there is an excess of albumin molecules, coupled with restrictions in the conformational transitions of other surface-adsorbed proteins into hemostatically active forms. (paper)

  16. Effects of surface condition on aqueous corrosion and environmental embrittlement of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, R.L.; Buchanan, R.A. [Univ. of Tennessee, Knoxville, TN (United States)

    1996-08-01

    Effects of retained high-temperature surface oxides, produced during thermomechanical processing and/or heat treatment, on the aqueous-corrosion and environmental-embrittlement characteristics of Fe{sub 3}Al-based iron aluminides (FA-84, FA-129 and FAL-Mo), a FeAl-based iron aluminide (FA-385), and a disordered low-aluminum Fe-Al alloy (FAPY) were evaluated. All tests were conducted at room temperature in a mild acid-chloride solution. In cyclic-anodic-polarization testing for aqueous-corrosion behavior, the surface conditions examined were: as-received (i.e., with the retained high-temperature oxides), mechanically cleaned and chemically cleaned. For all materials, the polarization tests showed the critical pitting potentials to be significantly lower in the as-received condition than in the mechanically-cleaned and chemically-cleaned conditions. These results indicate detrimental effects of the retained high-temperature oxides in terms of increased susceptibilities to localized corrosion. In 200-hour U-bend stress-corrosion-cracking tests for environmental-embrittlement behavior, conducted at open-circuit corrosion potentials and at a hydrogen-charging potential of {minus}1500 mV (SHE), the above materials (except FA-385) were examined with retained oxides and with mechanically cleaned surfaces. At the open-circuit corrosion potentials, none of the materials in either surface condition underwent cracking. At the hydrogen-charging potential, none of the materials with retained oxides underwent cracking, but FA-84, FA-129 and FAL-Mo in the mechanically cleaned condition did undergo cracking. These results suggest beneficial effects of the retained high-temperature oxides in terms of increased resistance to environmental hydrogen embrittlement.

  17. Critical review: Copper runoff from outdoor copper surfaces at atmospheric conditions.

    Science.gov (United States)

    Hedberg, Yolanda S; Hedberg, Jonas F; Herting, Gunilla; Goidanich, Sara; Odnevall Wallinder, Inger

    2014-01-01

    This review on copper runoff dispersed from unsheltered naturally patinated copper used for roofing and facades summarizes and discusses influencing factors, available literature, and predictive models, and the importance of fate and speciation for environmental risk assessment. Copper runoff from outdoor surfaces is predominantly governed by electrochemical and chemical reactions and is highly dependent on given exposure conditions (size, inclination, geometry, degree of sheltering, and orientation), surface parameters (age, patina composition, and thickness), and site-specific environmental conditions (gaseous pollutants, chlorides, rainfall characteristics (amount, intensity, pH), wind direction, temperature, time of wetness, season). The corrosion rate cannot be used to assess the runoff rate. The extent of released copper varies largely between different rain events and is related to dry and wet periods, dry deposition prior to the rain event and prevailing rain and patina characteristics. Interpretation and use of copper runoff data for environmental risk assessment and management need therefore to consider site-specific factors and focus on average data of long-term studies (several years). Risk assessments require furthermore that changes in copper speciation, bioavailability aspects, and potential irreversible retention on solid surfaces are considered, factors that determine the environmental fate of copper runoff from outdoor surfaces.

  18. Evaluation of Surface Characteristics and Shear Bond Strength of Metal Brackets Bonded to Two Different Porcelain Systems (Feldspathic/IPS-Empress-2 treated with Different Surface Conditioning Methods

    Directory of Open Access Journals (Sweden)

    Amal S Nair

    2012-01-01

    Conclusion: Surface conditioning with Co-Jet sand which produced silicatization resulted in a favorable bond strength in both feldspathic and IPS-Empress-2 ceramic surfaces. It was shown that it produced the least surface roughness among all the other surface conditioning groups.

  19. Influence of Surface Properties and Impact Conditions on Adhesion of Insect Residues

    Science.gov (United States)

    Wohl, Christopher J.; Smith, Joseph G.; Connell, John W.; Siochi, Emilie J.; Doss, Jereme R.; Shanahan, Michelle H.; Penner, Ronald K.

    2015-01-01

    Insect residues can cause premature transition to turbulent flow on laminar flow airfoils. Engineered surfaces that mitigate the adhesion of insect residues provide, therefore, a route to more efficient aerodynamics and reduced fuel burn rates. Areal coverage and heights of residues depend not only on surface properties, but also on impact conditions. We report high speed photography of fruit fly impacts at different angles of inclination on a rigid aluminum surface, optical microscopy and profilometry, and contact angle goniometry to support the design of engineered surfaces. For the polyurethane and epoxy coatings studied, some of which exhibited superhydrophobicity, it was determined that impact angle and surface compositions play critical roles in the efficacy of these surfaces to reduce insect residue adhesion.

  20. Long-term changes in the surface conditions of PLT

    International Nuclear Information System (INIS)

    Cohen, S.A.; Dylla, H.F.; Rossnagel, S.M.; Picraux, S.T.; Borders, J.A.; Magee, C.W.

    1977-01-01

    Long-term changes in the surface conditions of the PLT vacuum vessel wall have been monitored by the periodic analysis of a variety of sample substrates (stainless steel, alumina, silicon), exposed to PLT discharges for periods of up to several months and subsequently removed for analysis by Auger electron spectroscopy (AES), photoelectron spectroscopy, ion backscattering, nuclear reaction analysis, secondary ion mass spectroscopy, and scanning electron microscopy

  1. Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets

    NARCIS (Netherlands)

    Nergiz, I.; Schmage, P.; Herrmann, W.; Ozcan, M.; Nergiz, [No Value

    2004-01-01

    The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-µm) or rough (125-µm) diamond bur, sandblasting (50-µm or 110-µm aluminum oxide [Al2O3]), and silica coating (30-µm silica). Fifty

  2. Surface reactivity of colloidal corrosion product and alloys in PWR conditions

    International Nuclear Information System (INIS)

    Lefevre, Gregory; Leclercq, Stephanie; Cabanas, Bruna-Martin; Delaunay, Sophie; Mansour, Carine; Berger, Gilles

    2012-09-01

    The corrosion of metallic components of water circuits of Pressurized Water Reactors generates colloidal particles. These particles are transported in the circuits, they sorb dissolved species and they can deposit on alloys in given parts of the circuits. Sorption and deposition generate several technical drawbacks in both primary and secondary circuits. According to the DLVO theory, adhesion between two surfaces is controlled by electrostatic and Van der Waals forces. The latter are always attractive and does not depends on solution chemistry. On the contrary, electrostatic forces are connected to the surface charge and depend strongly on the chemical properties of the solids and on the chemistry of the solution. Depending on the relative charge of the surfaces, these forces are attractive or repulsive and can have a major effect on the deposition behavior of particles. According to the surface complexation theory, the surface charge of metallic oxides results from sorption or desorption of protons, leading to positive or negative surface sites, and thus, strongly depends on the solution pH. Dissolved species can sorb on the surface, depending on the ionic charge of these species and on the surface charge. Thus, the knowledge of the surface charge of corrosion particles and alloys, their affinity towards several ions as protons, nickel, cobalt, sulfate, or borate ions has been shown to be useful to predict the transport of the contamination in the primary circuit, or to understand the accumulation of impurities in the steam generator in the secondary circuit. At room temperature, these data can be easily measured, or found in literature. In PWR conditions (high temperature, high pressure), most of the usual protocols and commercial instruments cannot be used. For several years, collaboration between EDF R and D and CNRS has been developed to get information about the surface reactivity of iron oxides, ferrites, and alloys in such conditions. Some of the results

  3. 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...

  4. Conditions for mould growth on typical interior surfaces

    DEFF Research Database (Denmark)

    Møller, Eva B.; Andersen, Birgitte; Rode, Carsten

    2017-01-01

    Prediction of the risk for mould growth is an important parameter for the analysis and design of the hygrothermal performance of building constructions. However, in practice the mould growth does not always follow the predicted behavior described by the mould growth models. This is often explained...... by uncertainty in the real conditions of exposure. In this study, laboratory experiments were designed to determine mould growth at controlled transient climate compared to growth at constant climate. The experiment included three building materials with four different surface treatments. The samples were...

  5. Two new techniques for the remote evaluation of reactor steel condition - microscopic removal and surface examination

    International Nuclear Information System (INIS)

    Clayton, R.

    Much reactor inspection work involves an assessment of the condition of structural steel. This paper reviews two different techniques which provide information for such an assessment. The first - micro-sample removal (for the measurement of surface oxide thickness and chemical composition) - requires contact with the steel surface, whereas the second - a 'teach and learn' photographic technique (in which a special photogrammatic camera is used to obtain high-quality close-up photographs, to assess surface condition and corrosion growth) can obtain surface information on inaccessible components. (author)

  6. Modal analysis and cut-off conditions of multichannel surface-acoustic-waveguide structures.

    Science.gov (United States)

    Griffel, G; Golan, G; Ruschin, S; Seidman, A; Croitoru, N

    1988-01-01

    Multichannel guides for surface acoustic waves can improve the efficiency of SAW (surface acoustic-wave) devices significantly. Focusing, steering, and modulating the propagating acoustical modes can be achieved similarly to optical waveguided devices. A general formulation is presented for the analysis of the lateral waveguiding properties of Rayleigh modes in surfaces loaded with deposited strips of different materials. General expressions are obtained for the number of modes and cutoff conditions in these structures. As examples of applications, a simple directional coupler and an electrically controlled coupler are proposed.

  7. Surface condition effects on tritium permeation through the first wall of a water-cooled ceramic breeder blanket

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, H.-S. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei (China); Xu, Y.-P.; Liu, H.-D. [Science Island Branch of Graduate School, University of Science and Technology of China, P.O. Box 1126, Hefei (China); Liu, F.; Li, X.-C.; Zhao, M.-Z.; Qi, Q.; Ding, F. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei (China); Luo, G.-N., E-mail: gnluo@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei (China); Science Island Branch of Graduate School, University of Science and Technology of China, P.O. Box 1126, Hefei (China); Hefei Center for Physical Science and Technology, P.O. Box 1126, Hefei (China); Hefei Science Center of Chinese Academy of Science, P.O. Box 1126, Hefei (China)

    2016-11-01

    Highlights: • We investigate surface effects on T transport through the first wall. • We solve transport equations with various surface conditions. • The RAFMs walls w/and w/o W exhibit different T permeation behavior. • Diffusion in W has been found to be the rate-limiting step. - Abstract: Plasma-driven permeation of tritium (T) through the first wall of a water-cooled ceramic breeder (WCCB) blanket may raise safety and other issues. In the present work, surface effects on T transport through the first wall of a WCCB blanket have been investigated by theoretical calculation. Two types of wall structures, i.e., reduced activation ferritic/martensitic steels (RAFMs) walls with and without tungsten (W) armor, have been analyzed. Surface recombination is assumed to be the boundary condition for both the plasma-facing side and the coolant side. It has been found that surface conditions at both sides can affect T permeation flux and inventory. For the first wall using W as armor material, T permeation is not sensitive to the plasma-facing surface conditions. Contamination of the surfaces will lead to higher T inventory inside the first wall.

  8. Lunar and planetary surface conditions advances in space science and technology

    CERN Document Server

    Weil, Nicholas A

    1965-01-01

    Lunar and Planetary Surface Conditions considers the inferential knowledge concerning the surfaces of the Moon and the planetary companions in the Solar System. The information presented in this four-chapter book is based on remote observations and measurements from the vantage point of Earth and on the results obtained from accelerated space program of the United States and U.S.S.R. Chapter 1 presents the prevalent hypotheses on the origin and age of the Solar System, followed by a brief description of the methods and feasibility of information acquisition concerning lunar and planetary data,

  9. Influence of surface conditions on fatigue strength through the numerical simulation of microstructure

    International Nuclear Information System (INIS)

    Le Pecheur, A.; Clavel, M.; Rey, C.; Bompard, P.; Le Pecheur, A.; Curtit, F.; Stephan, J.M.

    2010-01-01

    A thermal fatigue test (INTHERPOL) was developed by EDF in order to study the initiation of cracks. These tests are carried out on tubular specimens under various thermal loadings and surface finish qualities in order to give an account of these parameters on crack initiation. The main topic of this study is to test the sensitivity of different fatigue criteria to surface conditions using a micro/macro modelling approach. Therefore a 304L polycrystalline aggregate, used for cyclic plasticity based FE modelling, have been considered as a Representative Volume Element located at the surface and subsurface of the test tube. This aggregate has been cyclically strained according to the results issued from FE simulation of INTHERPOL thermal fatigue experiment. Different surface parameters have been numerically simulated: effects of local microstructure and of grains orientation, effects of machining: metallurgical prehardening, residual stress gradient, and surface roughness. Three different fatigue criteria (Manson Coffin, Fatemi Socie and dissipated energy types), previously fitted at a macro-scale for thermal fatigue of 304L, have been computed at a meso scale, in order to show the surface 'hot spots' features and test the sensitivity of these three criteria to different surface conditions. Results show that grain orientation and neighbouring play an important role on the location of hot spots, and also that the positive effect of pre-straining and the negative effect of roughness on fatigue life are not all similarly predicted by these different fatigue criteria. (authors)

  10. Generation of synthetic surface electromyography signals under fatigue conditions for varying force inputs using feedback control algorithm.

    Science.gov (United States)

    Venugopal, G; Deepak, P; Ghosh, Diptasree M; Ramakrishnan, S

    2017-11-01

    Surface electromyography is a non-invasive technique used for recording the electrical activity of neuromuscular systems. These signals are random, complex and multi-component. There are several techniques to extract information about the force exerted by muscles during any activity. This work attempts to generate surface electromyography signals for various magnitudes of force under isometric non-fatigue and fatigue conditions using a feedback model. The model is based on existing current distribution, volume conductor relations, the feedback control algorithm for rate coding and generation of firing pattern. The result shows that synthetic surface electromyography signals are highly complex in both non-fatigue and fatigue conditions. Furthermore, surface electromyography signals have higher amplitude and lower frequency under fatigue condition. This model can be used to study the influence of various signal parameters under fatigue and non-fatigue conditions.

  11. Adhesion of resin composites to biomaterials in dentistry : an evaluation of surface conditioning methods

    NARCIS (Netherlands)

    Özcan, Mutlu

    2003-01-01

    Since previous investigations revealed that most clinical failures in adhesively luted ceramic restorations initiate from the cementation or internal surfaces, the study presented in Chapter II evaluated the effect of three different surface conditioning methods on the bond strength of a Bis-GMA

  12. Surface studies of niobium chemically polished under conditions for superconducting radio frequency (SRF) cavity production

    Science.gov (United States)

    Tian, Hui; Reece, Charles E.; Kelley, Michael J.; Wang, Shancai; Plucinski, Lukasz; Smith, Kevin E.; Nowell, Matthew M.

    2006-11-01

    The performance of niobium superconducting radiofrequency (SRF) accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially as influenced by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant datasets. We found that the predominant general surface orientation is (1 0 0), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3-1.4 times that resulting from static solution. The standard deviation of the roughness measurements is ±30% and that of the surface composition is ±5%.

  13. Surface studies of niobium chemically polished under conditions for superconducting radio frequency (SRF) cavity production

    Energy Technology Data Exchange (ETDEWEB)

    Tian Hui [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States); Kelley, Michael J. [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States)]. E-mail: mkelley@jlab.org; Wang Shancai [Department of Physics, Boston University (United States); Plucinski, Lukasz [Department of Physics, Boston University (United States); Smith, Kevin E. [Department of Physics, Boston University (United States); Nowell, Matthew M. [EDAX TSL (United States)

    2006-11-30

    The performance of niobium superconducting radiofrequency (SRF) accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially as influenced by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant datasets. We found that the predominant general surface orientation is (1 0 0), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3-1.4 times that resulting from static solution. The standard deviation of the roughness measurements is {+-}30% and that of the surface composition is {+-}5%.

  14. Surface Studies of Niobium Chemically Polished Under Conditions for Superconducting Radio Frequency (SRF) Cavity Production

    Energy Technology Data Exchange (ETDEWEB)

    Tian,H.; Reece, C.; Kelley, M.; Wang, S.; Plucinski, L.; Smith, K.; Nowell, M.

    2006-01-01

    The performance of niobium superconducting radiofrequency (SRF) accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially as influenced by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant datasets. We found that the predominant general surface orientation is (1 0 0), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3-1.4 times that resulting from static solution. The standard deviation of the roughness measurements is {+-}30% and that of the surface composition is {+-}5%.

  15. Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions

    Science.gov (United States)

    Magee, N. B.; Miller, A.; Amaral, M.; Cumiskey, A.

    2014-11-01

    Here we show high-magnification images of hexagonal ice crystals acquired by environmental scanning electron microscopy (ESEM). Most ice crystals were grown and sublimated in the water vapor environment of an FEI-Quanta-200 ESEM, but crystals grown in a laboratory diffusion chamber were also transferred intact and imaged via ESEM. All of these images display prominent mesoscopic topography including linear striations, ridges, islands, steps, peaks, pits, and crevasses; the roughness is not observed to be confined to prism facets. The observations represent the most highly magnified images of ice surfaces yet reported and expand the range of conditions in which rough surface features are known to be conspicuous. Microscale surface topography is seen to be ubiquitously present at temperatures ranging from -10 °C to -40 °C, in supersaturated and subsaturated conditions, on all crystal facets, and irrespective of substrate. Despite the constant presence of surface roughness, the patterns of roughness are observed to be dramatically different between growing and sublimating crystals, and transferred crystals also display qualitatively different patterns of roughness. Crystals are also demonstrated to sometimes exhibit inhibited growth in moderately supersaturated conditions following exposure to near-equilibrium conditions, a phenomenon interpreted as evidence of 2-D nucleation. New knowledge about the characteristics of these features could affect the fundamental understanding of ice surfaces and their physical parameterization in the context of satellite retrievals and cloud modeling. Links to supplemental videos of ice growth and sublimation are provided.

  16. Effects of electromagnetic field and lubricate condition on the surface quality of magnesium alloy billet during LFEC processing

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The microstructures of the magnesium billets could be improved markedly by low-frequency electro-magnetic casting (LFEC) processing. In fact, the low-frequency electromagnetic field (LFEF) also has favorite effect on the surface quality of billet. However, few public reports on the surface quality of LFEC magnesium billets could be found. Therefore, a new crystallizer with a metal internal sleeve to-gether with a kind of lubricant was designed aiming at lowing surface turning quantity, and the effects of casting velocity, electromagnetic condition and lubrication on the surface quality of magnesium billets were investigated. The results indicate that LFEF together with the lubricate condition would be responsible for the surface quality of the billets, and the high surface quality billets could be achieved by optimizing the casting conditions.

  17. A modified surface-resistance approach for representing bare-soil evaporation: wind tunnel experiments under various atmospheric conditions

    International Nuclear Information System (INIS)

    Yamanaka, T.; Takeda, A.; Sugita, F.

    1997-01-01

    A physically based (i.e., nonempirical) representation of surface-moisture availability is proposed, and its applicability is investigated. This method is based on the surface-resistance approaches, and it uses the depth of evaporating surface rather than the water content of the surface soil as the determining factor of surface-moisture availability. A simple energy-balance model including this representation is developed and tested against wind tunnel experiments under various atmospheric conditions. This model can estimate not only the latent heat flux but also the depth of the evaporating surface simultaneously by solving the inverse problem of energy balance at both the soil surface and the evaporating surface. It was found that the depth of the evaporating surface and the latent heat flux estimated by the model agreed well with those observed. The agreements were commonly found out under different atmospheric conditions. The only limitation of this representation is that it is not valid under conditions of drastic change in the radiation input, owing to the influence of transient phase transition of water in the dry surface layer. The main advantage of the approach proposed is that it can determine the surface moisture availability on the basis of the basic properties of soils instead of empirical fitting, although further investigations on its practical use are needed

  18. Direct numerical simulation of turbulent flows over superhydrophobic surfaces with gas pockets using linearized boundary conditions

    Science.gov (United States)

    Seo, Jongmin; Bose, Sanjeeb; Garcia-Mayoral, Ricardo; Mani, Ali

    2012-11-01

    Superhydrophobic surfaces are shown to be effective for surface drag reduction under laminar regime by both experiments and simulations (see for example, Ou and Rothstein, Phys. Fluids 17:103606, 2005). However, such drag reduction for fully developed turbulent flow maintaining the Cassie-Baxter state remains an open problem due to high shear rates and flow unsteadiness of turbulent boundary layer. Our work aims to develop an understanding of mechanisms leading to interface breaking and loss of gas pockets due to interactions with turbulent boundary layers. We take advantage of direct numerical simulation of turbulence with slip and no-slip patterned boundary conditions mimicking the superhydrophobic surface. In addition, we capture the dynamics of gas-water interface, by deriving a proper linearized boundary condition taking into account the surface tension of the interface and kinematic matching of interface deformation and normal velocity conditions on the wall. We will show results from our simulations predicting the dynamical behavior of gas pocket interfaces over a wide range of dimensionless surface tensions. Supported by the Office of Naval Research and the Kwanjeong Educational Scholarship Foundation.

  19. The effects of surface condition on abdominal muscle activity during single-legged hold exercise.

    Science.gov (United States)

    Ha, Sung-min; Oh, Jae-seop; Jeon, In-cheol; Kwon, Oh-yun

    2015-02-01

    To treat low-back pain, various spinal stability exercises are commonly used to improve trunk muscle function and strength. Because human movement for normal daily activity occurs in multi-dimensions, the importance of exercise in multi-dimensions or on unstable surfaces has been emphasized. Recently, a motorized rotating platform (MRP) for facilitating multi-dimensions dynamic movement was introduced for clinical use. However, the abdominal muscle activity with this device has not been reported. The purpose of this study was to compare the abdominal muscle activity (rectus abdominis, external and internal oblique muscles) during an active single-leg-hold (SLH) exercise on a floor (stable surface), foam roll, and motorized rotating platform (MRP). Thirteen healthy male subjects participated in this study. Using electromyography, the abdominal muscle activity was measured while the subjects performed SLH exercises on floor (stable surface), foam roll, and MRP. There were significant differences in the abdominal muscle activities among conditions (P.05) (Fig. 2). After the Bonferroni correction, however, no significant differences among conditions remained, except for differences in both side IO muscle activity between the floor and foam roll conditions (padjexercises on a foam roll and MRP is more effective increased activities of both side of RA and IO, and Rt. EO compared to floor condition. However, there were no significant differences in abdominal muscles activity in the multiple comparison between conditions (mean difference were smaller than the standard deviation in the abdominal muscle activities) (padj>0.017), except for differences in both side IO muscle activity between the floor (stable surface) and foam roll (padj<0.017) (effect size: 0.79/0.62 (non-supporting/supporting leg) for foam-roll versus floor). Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Study on conditional probability of surface rupture: effect of fault dip and width of seismogenic layer

    Science.gov (United States)

    Inoue, N.

    2017-12-01

    The conditional probability of surface ruptures is affected by various factors, such as shallow material properties, process of earthquakes, ground motions and so on. Toda (2013) pointed out difference of the conditional probability of strike and reverse fault by considering the fault dip and width of seismogenic layer. This study evaluated conditional probability of surface rupture based on following procedures. Fault geometry was determined from the randomly generated magnitude based on The Headquarters for Earthquake Research Promotion (2017) method. If the defined fault plane was not saturated in the assumed width of the seismogenic layer, the fault plane depth was randomly provided within the seismogenic layer. The logistic analysis was performed to two data sets: surface displacement calculated by dislocation methods (Wang et al., 2003) from the defined source fault, the depth of top of the defined source fault. The estimated conditional probability from surface displacement indicated higher probability of reverse faults than that of strike faults, and this result coincides to previous similar studies (i.e. Kagawa et al., 2004; Kataoka and Kusakabe, 2005). On the contrary, the probability estimated from the depth of the source fault indicated higher probability of thrust faults than that of strike and reverse faults, and this trend is similar to the conditional probability of PFDHA results (Youngs et al., 2003; Moss and Ross, 2011). The probability of combined simulated results of thrust and reverse also shows low probability. The worldwide compiled reverse fault data include low fault dip angle earthquake. On the other hand, in the case of Japanese reverse fault, there is possibility that the conditional probability of reverse faults with less low dip angle earthquake shows low probability and indicates similar probability of strike fault (i.e. Takao et al., 2013). In the future, numerical simulation by considering failure condition of surface by the source

  1. Evaluation of Haney-Type Surface Thermal Boundary Conditions Using a Coupled Atmosphere and Ocean Model

    National Research Council Canada - National Science Library

    Chu, Peter C; Chen, Yuchun; Lu, Shihua

    2001-01-01

    ... (Russell et al,, 1995) was used to verify the validity of Haney-type surface thermal boundary condition, which linearly connects net downward surface heat flux Q to air / sea temperature difference DeltaT by a relaxation coefficient K...

  2. Boundary conditions for free surface inlet and outlet problems

    KAUST Repository

    Taroni, M.

    2012-08-10

    We investigate and compare the boundary conditions that are to be applied to free-surface problems involving inlet and outlets of Newtonian fluid, typically found in coating processes. The flux of fluid is a priori known at an inlet, but unknown at an outlet, where it is governed by the local behaviour near the film-forming meniscus. In the limit of vanishing capillary number Ca it is well known that the flux scales with Ca 2/3, but this classical result is non-uniform as the contact angle approaches π. By examining this limit we find a solution that is uniformly valid for all contact angles. Furthermore, by considering the far-field behaviour of the free surface we show that there exists a critical capillary number above which the problem at an inlet becomes over-determined. The implications of this result for the modelling of coating flows are discussed. © 2012 Cambridge University Press.

  3. Optimizing pentacene thin-film transistor performance: Temperature and surface condition induced layer growth modification.

    Science.gov (United States)

    Lassnig, R; Hollerer, M; Striedinger, B; Fian, A; Stadlober, B; Winkler, A

    2015-11-01

    In this work we present in situ electrical and surface analytical, as well as ex situ atomic force microscopy (AFM) studies on temperature and surface condition induced pentacene layer growth modifications, leading to the selection of optimized deposition conditions and entailing performance improvements. We prepared p ++ -silicon/silicon dioxide bottom-gate, gold bottom-contact transistor samples and evaluated the pentacene layer growth for three different surface conditions (sputtered, sputtered + carbon and unsputtered + carbon) at sample temperatures during deposition of 200 K, 300 K and 350 K. The AFM investigations focused on the gold contacts, the silicon dioxide channel region and the highly critical transition area. Evaluations of coverage dependent saturation mobilities, threshold voltages and corresponding AFM analysis were able to confirm that the first 3-4 full monolayers contribute to the majority of charge transport within the channel region. At high temperatures and on sputtered surfaces uniform layer formation in the contact-channel transition area is limited by dewetting, leading to the formation of trenches and the partial development of double layer islands within the channel region instead of full wetting layers. By combining the advantages of an initial high temperature deposition (well-ordered islands in the channel) and a subsequent low temperature deposition (continuous film formation for low contact resistance) we were able to prepare very thin (8 ML) pentacene transistors of comparably high mobility.

  4. Degradation of atrazine and isoproturon in surface and sub-surface soil materials undergoing different moisture and aeration conditions.

    Science.gov (United States)

    Issa, Salah; Wood, Martin

    2005-02-01

    The influence of different moisture and aeration conditions on the degradation of atrazine and isoproturon was investigated in environmental samples aseptically collected from surface and sub-surface zones of agricultural land. The materials were maintained at two moisture contents corresponding to just above field capacity or 90% of field capacity. Another two groups of samples were adjusted with water to above field capacity, and, at zero time, exposed to drying-rewetting cycles. Atrazine was more persistent (t(1/2) = 22-35 days) than isoproturon (t(1/2) = 5-17 days) in samples maintained at constant moisture conditions. The rate of degradation for both herbicides was higher in samples maintained at a moisture content of 90% of field capacity than in samples with higher moisture contents. The reduction in moisture content in samples undergoing desiccation from above field capacity to much lower than field capacity enhanced the degradation of isoproturon (t(1/2) = 9-12 days) but reduced the rate of atrazine degradation (t(1/2) = 23-35 days). This demonstrates the variability between different micro-organisms in their susceptibility to desiccation. Under anaerobic conditions generated in anaerobic jars, atrazine degraded much more rapidly than isoproturon in materials taken from three soil profiles (0-250 cm depth). It is suggested that some specific micro-organisms are able to survive and degrade herbicide under severe conditions of desiccation. Copyright (c) 2005 Society of Chemical Industry.

  5. Surface deposition of iodine on some agricultural plants in laboratory conditions

    International Nuclear Information System (INIS)

    Stano, V.

    1990-01-01

    The surface (primary) deposition of nuclides on the above-ground parts of plants was studied. Iodine retention coefficients were measured in laboratory conditions for maize, peas, spinach, lettuce and paprika grown in loose soil taken in the Kecerovce locality. The results confirmed the assumption that the surface deposition of iodine is closely related to the morphological and physiological properties of the plants, although the substrate on which the plants are grown plays an appreciable role as well (the biomass production is higher for plants grown in loose soil than for those grown in aqueous nutrient solutions). The assumption that the above-ground parts retain iodine in higher quantities than the generative organs do was also proved. In the crops the retention of iodine was markedly differentiated in dependence on their overall consistency or on the structure of the surface cuticle layers. (author). 1 tab., 10 refs

  6. Residual stresses relaxation in surface-hardened half-space under creep conditions

    Directory of Open Access Journals (Sweden)

    Vladimir P. Radchenko

    2015-09-01

    Full Text Available We developed the method for solving the problem of residual stresses relaxation in surface-hardened layer of half-space under creep conditions. At the first stage we made the reconstruction of stress-strain state in half-space after plastic surface hardening procedure based on partial information about distribution for one residual stress tensor component experimentally detected. At the second stage using a numerical method we solve the problem of relaxation of self-balanced residual stresses under creep conditions. To solve this problem we introduce the following Cartesian system: x0y plane is aligned with hardened surface of half-space and 0z axis is directed to the depth of hardened layer. We also introduce the hypotheses of plane sections parallel to x0z and y0z planes. Detailed analysis of the problem has been done. Comparison of the calculated data with the corresponding test data was made for plane specimens (rectangular parallelepipeds made of EP742 alloy during T=650°C after the ultrasonic hardening with four hardening modes. We use half-space to model these specimens because penetration's depth of residual stresses is less than specimen general size in two digit exponent. There is enough correspondence of experimental and calculated data. It is shown that there is a decay (in modulus of pressing residual stresses under creep in 1.4–1.6 times.

  7. Surface and subsurface conditions in permafrost areas - a literature review

    International Nuclear Information System (INIS)

    Vidstrand, Patrik

    2003-02-01

    This report contains a summary of some of the information within existing technical and scientific literature on permafrost. Permafrost is viewed as one of the future climate driven process domains that may exist in Scandinavia, and that may give rise to significantly different surface and subsurface conditions than the present. Except for changes in the biosphere, permafrost may impact hydraulic, mechanical, and chemical subsurface processes and conditions. Permafrost and its influences on the subsurface conditions are thus of interest for the performance and safety assessments of deep geological waste repositories. The definition of permafrost is 'ground that stays at or below 0 deg C for at least two consecutive years'. Permafrost will effect the geological subsurface to some depth. How deep the permafrost may grow is a function of the heat balance, thermal conditions at the surface and within the ground, and the geothermal heat flux from the Earth's inner parts. The main chapters of the report summaries the knowledge on permafrost evolution, occurrence and distribution, and extracts information concerning hydrology and mechanical and chemical impacts due to permafrost related conditions. The results of a literature review are always dependent on the available literature. Concerning permafrost there is some literature available from investigations in the field of long-term repositories and some from mining industries. However, reports of these investigations are few and the bulk of permafrost literature comes from the science departments concerned with surficial processes (e.g. geomorphology, hydrology, agriculture, etc) and from engineering concerns, such as foundation of constructions and pipeline design. This focus within the permafrost research inevitably yields a biased but also an abundant amount of information on localised surficial processes and a limited amount on regional and deep permafrost characteristics. Possible conclusions are that there is

  8. Surface and subsurface conditions in permafrost areas - a literature review

    Energy Technology Data Exchange (ETDEWEB)

    Vidstrand, Patrik [Bergab, Goeteborg (Sweden)

    2003-02-01

    This report contains a summary of some of the information within existing technical and scientific literature on permafrost. Permafrost is viewed as one of the future climate driven process domains that may exist in Scandinavia, and that may give rise to significantly different surface and subsurface conditions than the present. Except for changes in the biosphere, permafrost may impact hydraulic, mechanical, and chemical subsurface processes and conditions. Permafrost and its influences on the subsurface conditions are thus of interest for the performance and safety assessments of deep geological waste repositories. The definition of permafrost is 'ground that stays at or below 0 deg C for at least two consecutive years'. Permafrost will effect the geological subsurface to some depth. How deep the permafrost may grow is a function of the heat balance, thermal conditions at the surface and within the ground, and the geothermal heat flux from the Earth's inner parts. The main chapters of the report summaries the knowledge on permafrost evolution, occurrence and distribution, and extracts information concerning hydrology and mechanical and chemical impacts due to permafrost related conditions. The results of a literature review are always dependent on the available literature. Concerning permafrost there is some literature available from investigations in the field of long-term repositories and some from mining industries. However, reports of these investigations are few and the bulk of permafrost literature comes from the science departments concerned with surficial processes (e.g. geomorphology, hydrology, agriculture, etc) and from engineering concerns, such as foundation of constructions and pipeline design. This focus within the permafrost research inevitably yields a biased but also an abundant amount of information on localised surficial processes and a limited amount on regional and deep permafrost characteristics. Possible conclusions are that

  9. Surface functionalization of SPR chip for specific molecular interaction analysis under flow condition

    Directory of Open Access Journals (Sweden)

    Tao Ma

    2017-03-01

    Full Text Available Surface functionalization of sensor chip for probe immobilization is crucial for the biosensing applications of surface plasmon resonance (SPR sensors. In this paper, we report a method circulating the dopamine aqueous solution to coat polydopamine film on sensing surface for surface functionalization of SPR chip. The polydopamine film with available thickness can be easily prepared by controlling the circulation time and the biorecognition elements can be immobilized on the polydopamine film for specific molecular interaction analysis. These operations are all performed under flow condition in the fluidic system, and have the advantages of easy implementation, less time consuming, and low cost, because the reagents and devices used in the operations are routinely applied in most laboratories. In this study, the specific absorption between the protein A probe immobilized on the sensing surface and human immunoglobulin G in the buffer is monitored based on this surface functionalization strategy to demonstrated its feasibility for SPR biosensing applications.

  10. The effect of physiological conditions on the surface structure of proteins: Setting the scene for human digestion of emulsions

    Science.gov (United States)

    Maldonado-Valderrama, J.; Gunning, A. P.; Ridout, M. J.; Wilde, P. J.; Morris, V. J.

    2009-10-01

    Understanding and manipulating the interfacial mechanisms that control human digestion of food emulsions is a crucial step towards improved control of dietary intake. This article reports initial studies on the effects of the physiological conditions within the stomach on the properties of the film formed by the milk protein ( β -lactoglobulin) at the air-water interface. Atomic force microscopy (AFM), surface tension and surface rheology techniques were used to visualize and examine the effect of gastric conditions on the network structure. The effects of changes in temperature, pH and ionic strength on a pre-formed interfacial structure were characterized in order to simulate the actual digestion process. Changes in ionic strength had little effect on the surface properties. In isolation, acidification reduced both the dilatational and the surface shear modulus, mainly due to strong repulsive electrostatic interactions within the surface layer and raising the temperature to body temperature accelerated the rearrangements within the surface layer, resulting in a decrease of the dilatational response and an increase of surface pressure. Together pH and temperature display an unexpected synergism, independent of the ionic strength. Thus, exposure of a pre-formed interfacial β -lactoglobulin film to simulated gastric conditions reduced the surface dilatational modulus and surface shear moduli. This is attributed to a weakening of the surface network in which the surface rearrangements of the protein prior to exposure to gastric conditions might play a crucial role.

  11. Environmental conditions to achieve low adhesion and low friction on diamond surfaces

    International Nuclear Information System (INIS)

    Guo, Haibo; Qi, Yue

    2010-01-01

    The adhesion and friction of both diamond and diamond-like carbon coatings can be dramatically changed by active gases in the environment, such as hydrogen, water vapor and humid air, due to tribochemical reactions. To understand the atmospheric effects and to predict the optimized environmental conditions (gas species, pressure and temperature), the tribochemical reactions on diamond surfaces are modeled from first principles thermodynamics. The results show that both H 2 and a mixture of H 2 O plus O 2 (such as humid air) can effectively achieve low adhesion and low friction with a fully –H or –OH passivated surface at very low partial pressures. Water vapor itself can passivate diamond (1 1 1) and (1 0 0) surfaces into half –H and half –OH terminated surfaces, but only at unrealistically high partial pressures. Even a trace amount of oxygen combined with water vapor can significantly reduce the water partial pressure for passivation. In all tribochemical reactions considered, the partial pressure required to reach low adhesion and low friction increases rapidly with temperature, and diamond (1 0 0) surface requires less partial pressures than (1 1 1) surface for surface passivation

  12. Investigation on the Temporal Surface Thermal Conditions for Thermal Comfort Researches Inside A Vehicle Cabin Under Summer Season Climate

    Directory of Open Access Journals (Sweden)

    Zhang Wencan

    2016-01-01

    Full Text Available With the proposes of improving occupant's thermal comfort and reducing the air conditioning power consumption, the present research carried out a comprehensive study on the surface thermal conductions and their influence parameters. A numerical model was built considering the transient conduction, convective and radiation heat transfer inside a vehicle cabin. For more accurate simulation of the radiation heat transfer behaviors, the radiation was considered into two spectral bands (short wave and long wave radiation, and the solar radiation was calculated by two solar fluxes (beam and diffuse solar radiation. An experiment was conducted to validate the numerical approach, showing a good agreement with the surface temperature. The surface thermal conditions were numerically simulated. The results show that the solar radiation is the most important factor in determining the internal surface thermal conditions. Effects of the window glass properties and the car body surface conditions were investigated. The numerical calculation results indicate that reducing the transitivity of window glass can effectively reduce the internal surface temperature. And the reflectivity of the vehicle cabin also has an important influence on the surface temperature, however, it's not so obvious as comparison to the window glass.

  13. On the initial condition problem of the time domain PMCHWT surface integral equation

    KAUST Repository

    Uysal, Ismail Enes; Bagci, Hakan; Ergin, A. Arif; Ulku, H. Arda

    2017-01-01

    Non-physical, linearly increasing and constant current components are induced in marching on-in-time solution of time domain surface integral equations when initial conditions on time derivatives of (unknown) equivalent currents are not enforced

  14. Effects of Seasonal Land Surface Conditions on Hydrometeorological Dynamics in South-western North America

    Science.gov (United States)

    2015-09-21

    rain gauges to measure precipitation , and 1 internal mini-flume to measure runoff . 9 Fig. 8. Processed fluxes measured at the two eddy...SECURITY CLASSIFICATION OF: Arid and semiarid landscapes in regions with seasonal precipitation experience dramatic changes that alter land surface...semiarid landscapes in regions with seasonal precipitation experience dramatic changes that alter land surface conditions, including soil moisture

  15. Investigation of surface boundary conditions for continuum modeling of RF plasmas

    Science.gov (United States)

    Wilson, A.; Shotorban, B.

    2018-05-01

    This work was motivated by a lacking general consensus in the exact form of the boundary conditions (BCs) required on the solid surfaces for the continuum modeling of Radiofrequency (RF) plasmas. Various kinds of number and energy density BCs on solid surfaces were surveyed, and how they interacted with the electric potential BC to affect the plasma was examined in two fundamental RF plasma reactor configurations. A second-order local mean energy approximation with equations governing the electron and ion number densities and the electron energy density was used to model the plasmas. Zero densities and various combinations of drift, diffusion, and thermal fluxes were considered to set up BCs. It was shown that the choice of BC can have a significant impact on the sheath and bulk plasma. The thermal and diffusion fluxes to the surface were found to be important. A pure drift BC for dielectric walls failed to produce a sheath.

  16. Water surface elevation from the upcoming SWOT mission under different flows conditions

    Science.gov (United States)

    Domeneghetti, Alessio; Schumann, Guy J. P.; Wei, Rui; Frasson, Renato P. M.; Durand, Michael; Pavelsky, Tamlin; Castellarin, Attilio; Brath, Armando

    2017-04-01

    The upcoming SWOT (Surface Water and Ocean Topography) satellite mission will provide unprecedented bi-dimensional observations of terrestrial water surface heights along rivers wider than 100m. Despite the literature reports several activities showing possible uses of SWOT products, potential and limitations of satellite observations still remain poorly understood and investigated. We present one of the first analyses regarding the spatial observation of water surface elevation expected from SWOT for a 140 km reach of the middle-lower portion of the Po River, in Northern Italy. The river stretch is characterized by a main channel varying from 100-500 m in width and a floodplain delimited by a system of major embankments that can be as wide as 5 km. The reconstruction of the hydraulic behavior of the Po River is performed by means of a quasi-2D model built with detailed topographic and bathymetric information (LiDAR, 2m resolution), while the simulation of remotely sensed hydrometric data is performed with a SWOT simulator that mimics the satellite sensor characteristics. Referring to water surface elevations associated with different flow conditions (maximum, minimum and average flow) this work characterizes the spatial observations provided by SWOT and highlights the strengths and limitations of the expected products. The analysis provides a robust reference for spatial water observations that will be available from SWOT and assesses possible effects of river embankments, river width and river topography under different hydraulic conditions. Results of the study characterize the expected accuracy of the upcoming SWOT mission and provide additional insights towards the appropriate exploitation of future hydrological observations.

  17. Effect of processing conditions on residual stress distributions by bead-on-plate welding after surface machining

    International Nuclear Information System (INIS)

    Ihara, Ryohei; Mochizuki, Masahito

    2014-01-01

    Residual stress is important factor for stress corrosion cracking (SCC) that has been observed near the welded zone in nuclear power plants. Especially, surface residual stress is significant for SCC initiation. In the joining processes of pipes, butt welding is conducted after surface machining. Residual stress is generated by both processes, and residual stress distribution due to surface machining is varied by the subsequent butt welding. In previous paper, authors reported that residual stress distribution generated by bead on plate welding after surface machining has a local maximum residual stress near the weld metal. The local maximum residual stress shows approximately 900 MPa that exceeds the stress threshold for SCC initiation. Therefore, for the safety improvement of nuclear power plants, a study on the local maximum residual stress is important. In this study, the effect of surface machining and welding conditions on residual stress distribution generated by welding after surface machining was investigated. Surface machining using lathe machine and bead on plate welding with tungsten inert gas (TIG) arc under various conditions were conducted for plate specimens made of SUS316L. Then, residual stress distributions were measured by X-ray diffraction method (XRD). As a result, residual stress distributions have the local maximum residual stress near the weld metal in all specimens. The values of the local maximum residual stresses are almost the same. The location of the local maximum residual stress is varied by welding condition. It could be consider that the local maximum residual stress is generated by same generation mechanism as welding residual stress in surface machined layer that has high yield stress. (author)

  18. Four chemical methods of porcelain conditioning and their influence over bond strength and surface integrity

    Science.gov (United States)

    Stella, João Paulo Fragomeni; Oliveira, Andrea Becker; Nojima, Lincoln Issamu; Marquezan, Mariana

    2015-01-01

    OBJECTIVE: To assess four different chemical surface conditioning methods for ceramic material before bracket bonding, and their impact on shear bond strength and surface integrity at debonding. METHODS: Four experimental groups (n = 13) were set up according to the ceramic conditioning method: G1 = 37% phosphoric acid etching followed by silane application; G2 = 37% liquid phosphoric acid etching, no rinsing, followed by silane application; G3 = 10% hydrofluoric acid etching alone; and G4 = 10% hydrofluoric acid etching followed by silane application. After surface conditioning, metal brackets were bonded to porcelain by means of the Transbond XP system (3M Unitek). Samples were submitted to shear bond strength tests in a universal testing machine and the surfaces were later assessed with a microscope under 8 X magnification. ANOVA/Tukey tests were performed to establish the difference between groups (α= 5%). RESULTS: The highest shear bond strength values were found in groups G3 and G4 (22.01 ± 2.15 MPa and 22.83 ± 3.32 Mpa, respectively), followed by G1 (16.42 ± 3.61 MPa) and G2 (9.29 ± 1.95 MPa). As regards surface evaluation after bracket debonding, the use of liquid phosphoric acid followed by silane application (G2) produced the least damage to porcelain. When hydrofluoric acid and silane were applied, the risk of ceramic fracture increased. CONCLUSIONS: Acceptable levels of bond strength for clinical use were reached by all methods tested; however, liquid phosphoric acid etching followed by silane application (G2) resulted in the least damage to the ceramic surface. PMID:26352845

  19. Water Contact Angle Dependence with Hydroxyl Functional Groups on Silica Surfaces under CO2 Sequestration Conditions.

    Science.gov (United States)

    Chen, Cong; Zhang, Ning; Li, Weizhong; Song, Yongchen

    2015-12-15

    Functional groups on silica surfaces under CO2 sequestration conditions are complex due to reactions among supercritical CO2, brine and silica. Molecular dynamics simulations have been performed to investigate the effects of hydroxyl functional groups on wettability. It has been found that wettability shows a strong dependence on functional groups on silica surfaces: silanol number density, space distribution, and deprotonation/protonation degree. For neutral silica surfaces with crystalline structure (Q(3), Q(3)/Q(4), Q(4)), as silanol number density decreases, contact angle increases from 33.5° to 146.7° at 10.5 MPa and 318 K. When Q(3) surface changes to an amorphous structure, water contact angle increases 20°. Water contact angle decreases about 12° when 9% of silanol groups on Q(3) surface are deprotonated. When the deprotonation degree increases to 50%, water contact angle decreases to 0. The dependence of wettability on silica surface functional groups was used to analyze contact angle measurement ambiguity in literature. The composition of silica surfaces is complicated under CO2 sequestration conditions, the results found in this study may help to better understand wettability of CO2/brine/silica system.

  20. Surface conditioning with Escherichia coli cell wall components can reduce biofilm formation by decreasing initial adhesion

    Directory of Open Access Journals (Sweden)

    Luciana C. Gomes

    2017-07-01

    Full Text Available Bacterial adhesion and biofilm formation on food processing surfaces pose major risks to human health. Non-efficient cleaning of equipment surfaces and piping can act as a conditioning layer that affects the development of a new biofilm post-disinfection. We have previously shown that surface conditioning with cell extracts could reduce biofilm formation. In the present work, we hypothesized that E. coli cell wall components could be implicated in this phenomena and therefore mannose, myristic acid and palmitic acid were tested as conditioning agents. To evaluate the effect of surface conditioning and flow topology on biofilm formation, assays were performed in agitated 96-well microtiter plates and in a parallel plate flow chamber (PPFC, both operated at the same average wall shear stress (0.07 Pa as determined by computational fluid dynamics (CFD. It was observed that when the 96-well microtiter plate and the PPFC were used to form biofilms at the same shear stress, similar results were obtained. This shows that the referred hydrodynamic feature may be a good scale-up parameter from high-throughput platforms to larger scale flow cell systems as the PPFC used in this study. Mannose did not have any effect on E. coli biofilm formation, but myristic and palmitic acid inhibited biofilm development by decreasing cell adhesion (in about 50%. These results support the idea that in food processing equipment where biofilm formation is not critical below a certain threshold, bacterial lysis and adsorption of cell components to the surface may reduce biofilm buildup and extend the operational time.

  1. First-principles study of low Miller index Ni3S2 surfaces in hydrotreating conditions.

    Science.gov (United States)

    Aray, Yosslen; Vega, David; Rodriguez, Jesus; Vidal, Alba B; Grillo, Maria Elena; Coll, Santiago

    2009-03-12

    Density functional theory (DFT) calculations combined with surface thermodynamic arguments and the Gibbs-Curie-Wulff equilibrium morphology formalism have been employed to explore the effect of the reaction conditions, temperature (T), and gas-phase partial pressures (PH2 and PH2S) on the stability of nickel sulfide (Ni3S2) surfaces. Furthermore, the strength and nature of chemical bonds for selected Ni3S2 surface cuts were investigated with the quantum theory of atoms in molecules methodology. A particular analysis of the electrostatic potential within this theoretical framework is performed to study the potential activity of nickel sulfide nanoparticles as hydrodesulfurization (HDS) catalysts. The calculated thermodynamic surface stabilities and the resulting equilibrium morphology model suggest that unsupported Ni3S2 nanoparticles mainly expose (111) and (111) type surface faces in HDS conditions. Analysis of the electrostatic potential mapped onto a selected electron density isocontour (0.001 au) on those expose surface reveals a poor potential reactivity toward electron-donating reagents (i.e., low Lewis acidity). Consequently, a very low attraction between coordinatively unsaturated active sites (Lewis sites) exposed at the catalytic particles and the S atoms coming from reagent polluting molecules does inactive these kinds of particles for HDS.

  2. Analysis of surface integrity in machining of AISI 304 stainless steel under various cooling and cutting conditions

    Science.gov (United States)

    Klocke, F.; Döbbeler, B.; Lung, S.; Seelbach, T.; Jawahir, I. S.

    2018-05-01

    Recent studies have shown that machining under specific cooling and cutting conditions can be used to induce a nanocrystalline surface layer in the workspiece. This layer has beneficial properties, such as improved fatigue strength, wear resistance and tribological behavior. In machining, a promising approach for achieving grain refinement in the surface layer is the application of cryogenic cooling. The aim is to use the last step of the machining operation to induce the desired surface quality to save time-consuming and expensive post machining surface treatments. The material used in this study was AISI 304 stainless steel. This austenitic steel suffers from low yield strength that limits its technological applications. In this paper, liquid nitrogen (LN2) as cryogenic coolant, as well as minimum quantity lubrication (MQL), was applied and investigated. As a reference, conventional flood cooling was examined. Besides the cooling conditions, the feed rate was varied in four steps. A large rounded cutting edge radius and finishing cutting parameters were chosen to increase the mechanical load on the machined surface. The surface integrity was evaluated at both, the microstructural and the topographical levels. After turning experiments, a detailed analysis of the microstructure was carried out including the imaging of the surface layer and hardness measurements at varying depths within the machined layer. Along with microstructural investigations, different topological aspects, e.g., the surface roughness, were analyzed. It was shown that the resulting microstructure strongly depends on the cooling condition. This study also shows that it was possible to increase the micro hardness in the top surface layer significantly.

  3. Corrosion and surface conditions of EUROFER 97 steel in Pb-17Li at 500 deg C

    International Nuclear Information System (INIS)

    Zmitko, M.; Splichal, K.; Masarik, V.

    2004-01-01

    In this work the corrosion behaviour of EUROFER 97 was examined in flowing Pb-17Li at the temperature 500 deg C up to 2500 hours. Surface morphology and chemical composition profiles and weight changes were investigated. Interaction of EUROFER 97 specimens with Pb-17Li melt results in a material dissolution, which is demonstrated by surface morphology and specimen weight changes. The specimen surfaces investigated after 500 and 1000 hours of exposure in Pb-17Li show similar surface appearance in both as-received and polished conditions. The corrosive damage occurs locally and a major part of surface areas is not affected. The exposure after 2500 hours evidences some visible decrease in the surface roughness for both surface conditions. The surface overlapping was observed and industrial tube productions have to avoid such types of defects. A small weight changes after 500 and 1000 hours and a higher weight decrease after 2500 hours were observed. The absolute values of the weight change after 500 and 1000 hours are about one order of magnitude lower than ones of weight changes after 2500 hours exposure. There were no significant differences of weight changes between as-received and polished surface conditions. The weight decrease of about 1 mg/cm 2 after 2500 hours is in a sufficient correlation with the value of about 4 mg/cm 2 evaluated from data of Fe-12Cr-1MoVW steel. The experiments have shown that the surface corrosive attack revealed only after a certain incubation period. During this period the surface layers are relatively stable to a direct attack of the surface by the melt. In the course of exposure time those layers are not further resistant and can influence the dissolutions of steel components. Concentration profiles of steel components near the steel surface were examined by EDX line-scan and point analyses. Under the experimental conditions no considerable profile of Cr and Fe in surface layers, as higher soluble steel components in Pb-17Li, was

  4. Distribution of near-surface permafrost in Alaska: estimates of present and future conditions

    Science.gov (United States)

    Pastick, Neal J.; Jorgenson, M. Torre; Wylie, Bruce K.; Nield, Shawn J.; Johnson, Kristofer D.; Finley, Andrew O.

    2015-01-01

    High-latitude regions are experiencing rapid and extensive changes in ecosystem composition and function as the result of increases in average air temperature. Increasing air temperatures have led to widespread thawing and degradation of permafrost, which in turn has affected ecosystems, socioeconomics, and the carbon cycle of high latitudes. Here we overcome complex interactions among surface and subsurface conditions to map nearsurface permafrost through decision and regression tree approaches that statistically and spatially extend field observations using remotely sensed imagery, climatic data, and thematic maps of a wide range of surface and subsurface biophysical characteristics. The data fusion approach generated medium-resolution (30-m pixels) maps of near-surface (within 1 m) permafrost, active-layer thickness, and associated uncertainty estimates throughout mainland Alaska. Our calibrated models (overall test accuracy of ~85%) were used to quantify changes in permafrost distribution under varying future climate scenarios assuming no other changes in biophysical factors. Models indicate that near-surface permafrost underlies 38% of mainland Alaska and that near-surface permafrost will disappear on 16 to 24% of the landscape by the end of the 21st Century. Simulations suggest that near-surface permafrost degradation is more probable in central regions of Alaska than more northerly regions. Taken together, these results have obvious implications for potential remobilization of frozen soil carbon pools under warmer temperatures. Additionally, warmer and drier conditions may increase fire activity and severity, which may exacerbate rates of permafrost thaw and carbon remobilization relative to climate alone. The mapping of permafrost distribution across Alaska is important for land-use planning, environmental assessments, and a wide-array of geophysical studies.

  5. Colonization by Cladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

    Science.gov (United States)

    Ahearn, D. G.; Simmons, R. B.; Switzer, K. F.; Ajello, L.; Pierson, D. L.

    1991-01-01

    Cladosporium cladosporioides and C. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.

  6. First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

    DEFF Research Database (Denmark)

    Saadi, Souheil; Hinnemann, Berit; Appel, Charlotte C.

    2011-01-01

    We investigate the structure and surface composition of the γ′-Ni3Al(111) and β-NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel–aluminum alloys are protected...... by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni3Al and NiAl surfaces, the conditions under which CO and OH...... adsorption is to be expected and under which it is inhibited, are mapped out. Because CO and OH are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the CO and OH...

  7. Local environmental conditions and the stability of protective layers on steel surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, J P [Technical Univ. of Denmark, Lyngby (Denmark); Bursik, A

    1996-12-01

    Local environmental conditions determine whether the protective layers on steel surfaces are stable. With unfavorable local environmental conditions, the protective layers may be subject to damage. Taking the cation conductivity of all plant cycle streams <0.2 {mu}S/cm for granted, an adequate feed-water and - if applicable - boiler water conditioning is required to prevent such damage. Even if the mentioned conditions are met in a bulk, the local environmental conditions may be inadequate. The reasons for this may be the disregarding of interactions among material, design, and chemistry. The paper presents many possible mechanisms of protective layer damage that are directly influenced or exacerbated by plant cycle chemistry. Two items are discussed in more detail: First, the application of all volatile treatment for boiler water conditioning of drum boiler systems operating at low pressures and, second, the chemistry in the transition zone water/steam in the low pressure turbine. The latter is of major interest for the understanding and prevention of corrosion due to high concentration of impurities in the aqueous liquid phases. This is a typical example showing that local environmental conditions may fundamentally differ from the overall bulk chemistry. (au) 19 refs.

  8. Air-side performance of a micro-channel heat exchanger in wet surface conditions

    Directory of Open Access Journals (Sweden)

    Srisomba Raviwat

    2017-01-01

    Full Text Available The effects of operating conditions on the air-side heat transfer, and pressure drop of a micro-channel heat exchanger under wet surface conditions were studied experimentally. The test section was an aluminum micro-channel heat exchanger, consisting of a multi-louvered fin and multi-port mini-channels. Experiments were conducted to study the effects of inlet relative humidity, air frontal velocity, air inlet temperature, and refrigerant temperature on air-side performance. The experimental data were analyzed using the mean enthalpy difference method. The test run was performed at relative air humidities ranging between 45% and 80%; air inlet temperature ranges of 27, 30, and 33°C; refrigerant-saturated temperatures ranging from 18 to 22°C; and Reynolds numbers between 128 and 166. The results show that the inlet relative humidity, air inlet temperature, and the refrigerant temperature had significant effects on heat transfer performance and air-side pressure drop. The heat transfer coefficient and pressure drop for the micro-channel heat exchanger under wet surface conditions are proposed in terms of the Colburn j factor and Fanning f factor.

  9. Study on Surface Integrity of AISI 1045 Carbon Steel when machined by Carbide Cutting Tool under wet conditions

    Directory of Open Access Journals (Sweden)

    Tamin N. Fauzi

    2017-01-01

    Full Text Available This paper presents the evaluation of surface roughness and roughness profiles when machining carbon steel under wet conditions with low and high cutting speeds. The workpiece materials and cutting tools selected in this research were AISI 1045 carbon steel and canela carbide inserts graded PM25, respectively. The cutting tools undergo machining tests by CNC turning operations and their performances were evaluated by their surface roughness value and observation of the surface roughness profile. The machining tests were held at varied cutting speeds of 35 to 53 m/min, feed rate of 0.15 to 0.50 mm/rev and a constant depth of cut of 1 mm. From the analysis, it was found that surface roughness increased as the feed rate increased. Varian of surface roughness was suspected due to interaction between cutting speeds and feed rates as well as nose radius conditions; whether from tool wear or the formation of a built-up edge. This study helps us understand the effect of cutting speed and feed rate on surface integrity, when machining AISI 1045 carbon steel using carbide cutting tools, under wet cutting conditions.

  10. Conditions affecting the release of phosphorus from surface lake sediments.

    Science.gov (United States)

    Christophoridis, Christophoros; Fytianos, Konstantinos

    2006-01-01

    Laboratory studies were conducted to determine the effect of pH and redox conditions, as well as the effect of Fe, Mn, Ca, Al, and organic matter, on the release of ortho-phosphates in lake sediments taken from Lakes Koronia and Volvi (Northern Greece). Results were evaluated in combination with experiments to determine P fractionation in the sediment. The study revealed the major effect of redox potential and pH on the release of P from lake sediments. Both lakes showed increased release rates under reductive conditions and high pH values. The fractionation experiments revealed increased mobility of the reductive P fraction as well as of the NaOH-P fraction, indicating participation of both fractions in the overall release of sediment-bound P, depending on the prevailing environmental conditions. The results were assessed in combination with the release patterns of Fe, Mn, Ca, Al, and organic matter, enabling the identification of more specific processes of P release for each lake. The basic release patterns included the redox induced reductive dissolution of P-bearing metal oxides and the competitive exchange of phosphate anions with OH- at high pH values. The formation of an oxidized surface microlayer under oxic conditions acted as a protective film, preventing further P release from the sediments of Lake Volvi, while sediments from Lake Koronia exhibited a continuous and increased tendency to release P under various physicochemical conditions, acting as a constant source of internal P loading.

  11. Experimental investigation of nucleate boiling on heated surfaces under subcooled conditions

    International Nuclear Information System (INIS)

    Schneider, C.; Hampel, R.; Traichel, A.; Hurtado, A.; Meissner, S.; Koch, E.

    2011-01-01

    In case of an accident at pressurized water reactors (PWR), critical boiling conditions can appear at the transition from bubble- to film boiling. During full power operation, heat transfer phenomena of sub cooled nucleate boiling occur on the surface of the fuel rods. To investigate the microscopic processes in nucleate boiling, a test facility with optical measuring methods was constructed. This allows analyzing the effects on a single bubble system at different parameters. For the generation of nucleate boiling, an optically transparent, electrically conductive coating was applied as a heating surface on a borosilicate substrate. The so-called ITO (Indium-Tin-Oxide) coating with a sheet resistance of 20 ohms enables an electrical heating at an optical transparent surface. These properties are prerequisites for the study of microscopic phenomena in the bubble formation with optical coherence tomography (OCT). OCT, generally used in medical diagnostics, is an imaging modality providing cross sectional and volumetric high resolution images. To make sure that the bubble formation takes place at a specific site, artificial nucleation sites in form of micro cavity will be inserted into the surface. Furthermore a small test facility was constructed to dedicate the wall temperature of a heated metal foil during subcooled boiling in non degassed water, which is the content of this paper. (author)

  12. Response Surface Methodology: An Extensive Potential to Optimize in vivo Photodynamic Therapy Conditions

    International Nuclear Information System (INIS)

    Tirand, Loraine; Bastogne, Thierry; Bechet, Denise M.Sc.; Linder, Michel; Thomas, Noemie; Frochot, Celine; Guillemin, Francois; Barberi-Heyob, Muriel

    2009-01-01

    Purpose: Photodynamic therapy (PDT) is based on the interaction of a photosensitizing (PS) agent, light, and oxygen. Few new PS agents are being developed to the in vivo stage, partly because of the difficulty in finding the right treatment conditions. Response surface methodology, an empirical modeling approach based on data resulting from a set of designed experiments, was suggested as a rational solution with which to select in vivo PDT conditions by using a new peptide-conjugated PS targeting agent, neuropilin-1. Methods and Materials: A Doehlert experimental design was selected to model effects and interactions of the PS dose, fluence, and fluence rate on the growth of U87 human malignant glioma cell xenografts in nude mice, using a fixed drug-light interval. All experimental results were computed by Nemrod-W software and Matlab. Results: Intrinsic diameter growth rate, a tumor growth parameter independent of the initial volume of the tumor, was selected as the response variable and was compared to tumor growth delay and relative tumor volumes. With only 13 experimental conditions tested, an optimal PDT condition was selected (PS agent dose, 2.80 mg/kg; fluence, 120 J/cm 2 ; fluence rate, 85 mW/cm 2 ). Treatment of glioma-bearing mice with the peptide-conjugated PS agent, followed by the optimized PDT condition showed a statistically significant improvement in delaying tumor growth compared with animals who received the PDT with the nonconjugated PS agent. Conclusions: Response surface methodology appears to be a useful experimental approach for rapid testing of different treatment conditions and determination of optimal values of PDT factors for any PS agent.

  13. Molecular Dynamics Simulation and Analysis of Interfacial Water at Selected Sulfide Mineral Surfaces under Anaerobic Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Jiaqi; Miller, Jan D.; Dang, Liem X.

    2014-04-10

    In this paper, we report on a molecular dynamics simulation (MDS) study of the behavior of interfacial water at selected sulfide mineral surfaces under anaerobic conditions. The study revealed the interfacial water structure and wetting characteristics of the pyrite (100) surface, galena (100) surface, chalcopyrite (012) surface, sphalerite (110) surface, and molybdenite surfaces (i.e., the face, armchair-edge, and zigzag-edge surfaces), including simulated contact angles, relative number density profiles, water dipole orientations, hydrogen-bonding, and residence times. For force fields of the metal and sulfur atoms in selected sulfide minerals used in the MDS, we used the universal force field (UFF) and another set of force fields optimized by quantum chemical calculations for interactions with interfacial water molecules at selected sulfide mineral surfaces. Simulation results for the structural and dynamic properties of interfacial water molecules indicate the natural hydrophobic character for the selected sulfide mineral surfaces under anaerobic conditions as well as the relatively weak hydrophobicity for the sphalerite (110) surface and two molybdenite edge surfaces. Part of the financial support for this study was provided by the U.S. Department of Energy (DOE) under Basic Science Grant No. DE-FG-03-93ER14315. The Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences (BES), of the DOE, funded work performed by Liem X. Dang. Battelle operates Pacific Northwest National Laboratory for DOE. The calculations were carried out using computer resources provided by BES. The authors are grateful to Professor Tsun-Mei Chang for valuable discussions.

  14. Micromorphology of leaf surface of Coelogyne Lindl. species (Orchidaceae Juss. in greenhouse conditions

    Directory of Open Access Journals (Sweden)

    Alexander G. Gyrenko

    2013-04-01

    Full Text Available The micromorphological characteristics of both adaxial and abaxial leaf surfaces of the plants of five Coelogyne Lindl. species (C. assamicaLinden & Rchb.f., C. brachyptera Rchb.f., C. cumingii Lindl., C. fimbriataLindl., C. lentiginosaLindl. under glasshouse conditions have been described.

  15. Effect of reactor finiteness on the boundary condition at the surface of a booster section

    International Nuclear Information System (INIS)

    Wassef, W.A.

    1982-01-01

    Effect of reactor finiteness on the boundary condition at the surface of an absorbing booster embedded in the reactor core is studied and formulated. The model used in these calculations depends on the Pl-Transport coupling technique. This method takes into consideration the rigorous neutron transport behavior inside the booster medium, while the Pl-approximation in the bulk of the scattering medium surrounding the booster which can be considered infinite in most practical applications. The neutron flux gradient parallel to the surface of the booster is considered. The geometrical configuration of the reactor core cross section is circular or rectangular. Finiteness of the reactor is introduced in the general formulation through its dimensions or buckling. Extensive numerical results are given to demonstrate the dependence of the boundary condition at the surface of the booster section on the reactor finiteness and the different physical parameters

  16. The Role of Meteorology and Surface Condition to Multi-Decadal Variations of Dust Emission in Sahara and Sahel

    Science.gov (United States)

    Kim, D.; Chin, M.; Diehl, T. L.; Bian, H.; Brown, M. E.; Remer, L. A.; Stockwell, W. R.

    2014-12-01

    North Africa is the world's largest dust source region influencing regional and global climate, human health, and even the local economy. However North Africa as a dust source is not uniform but it consists of the arid region (Sahara) and the semi-arid region (Sahel) with emission rates depending on meteorological and surface conditions. Several recent studies have shown that dust from North Africa seems to have a decreasing trend in the past three decades. The goal of this study is to better understand the controlling factors that determine the change of dust in North Africa using observational data and model simulations. First we analyze surface bareness conditions determined from a long-term satellite observed Normalized Difference Vegetation Index for 1980-2008. Then we examine the key meteorological variables of precipitation and surface winds. Modeling experiments were conducted using the NASA Goddard Chemistry Aerosol Radiation and Transport (GOCART) model, which has been recently updated with a dynamic dust source function. Using the method we separate the dust originating from the Sahel from that of the Sahara desert. We find that the surface wind speed is the most dominant factor affecting Sahelian dust emission while vegetation has a modulating effect. We will show regional differences in meteorological variables, surface conditions, dust emission, and dust distribution and address the relationships among meteorology, surface conditions, and dust emission/loading in the past three decades (1980-2008).

  17. On the initial condition problem of the time domain PMCHWT surface integral equation

    KAUST Repository

    Uysal, Ismail Enes

    2017-05-13

    Non-physical, linearly increasing and constant current components are induced in marching on-in-time solution of time domain surface integral equations when initial conditions on time derivatives of (unknown) equivalent currents are not enforced properly. This problem can be remedied by solving the time integral of the surface integral for auxiliary currents that are defined to be the time derivatives of the equivalent currents. Then the equivalent currents are obtained by numerically differentiating the auxiliary ones. In this work, this approach is applied to the marching on-in-time solution of the time domain Poggio-Miller-Chan-Harrington-Wu-Tsai surface integral equation enforced on dispersive/plasmonic scatterers. Accuracy of the proposed method is demonstrated by a numerical example.

  18. A Snow Density Dataset for Improving Surface Boundary Conditions in Greenland Ice Sheet Firn Modeling

    DEFF Research Database (Denmark)

    S. Fausto, Robert; E. Box, Jason; Vandecrux, Baptiste Robert Marcel

    2018-01-01

    The surface snow density of glaciers and ice sheets is of fundamental importance in converting volume to mass in both altimetry and surface mass balance studies, yet it is often poorly constrained. Site-specific surface snow densities are typically derived from empirical relations based...... on temperature and wind speed. These parameterizations commonly calculate the average density of the top meter of snow, thereby systematically overestimating snow density at the actual surface. Therefore, constraining surface snow density to the top 0.1 m can improve boundary conditions in high-resolution firn......-evolution modeling. We have compiled an extensive dataset of 200 point measurements of surface snow density from firn cores and snow pits on the Greenland ice sheet. We find that surface snow density within 0.1 m of the surface has an average value of 315 kg m−3 with a standard deviation of 44 kg m−3, and has...

  19. Tribological Properties of Surface-Textured and Plasma-Nitrided Pure Titanium Under Oil Lubrication Condition

    Science.gov (United States)

    Zhang, Baosen; Dong, Qiangsheng; Ba, Zhixin; Wang, Zhangzhong; Shi, Hancheng; Xue, Yanting

    2018-01-01

    Plasma nitriding was conducted as post-treatment for surface texture on pure titanium to obtain a continuous nitriding layer. Supersonic fine particles bombarding (SFPB) was carried out to prepare surface texture. The surface morphologies and chemical composition were analyzed using scanning electron microscope and energy disperse spectroscopy. The microstructures of modified layers were characterized by transmission electron microscope. The tribological properties of surface-textured and duplex-treated pure titanium under oil lubrication condition were systematically investigated in the ball-on-plate reciprocating mode. The effects of applied load and sliding velocity on the tribological behavior were analyzed. The results show that after duplex treatments, the grains size in modified layer becomes slightly larger, and hardness is obviously improved. Wear resistance of duplex-treated pure titanium is significantly improved referenced to untreated and surface-textured pure titanium, which is 3.22 times as much as untreated pure titanium and 2.15 times of that for surface-textured pure titanium, respectively.

  20. Effect of operational conditions of electroerosion machining on the surface microgeometry parameters of steels and alloys

    International Nuclear Information System (INIS)

    Foteev, N.K.

    1976-01-01

    Studies the influence of pulse duration and a series of operating conditions of a ShGI-40-440 spark-machining generator on changes in the basic surface microgeometry characteristics of components of stainless steel 1Kh18N10T, steel St 45 and hard alloy T14K8. The microgeometry characteristics of spark-machined surfaces differ significantly from the corresponding characteristics of surfaces machined by cutting and vibro-rolling

  1. Probing adsorption phenomena on a single crystal Pt-alloy surface under oxygen reduction reaction conditions

    DEFF Research Database (Denmark)

    Bondarenko, Alexander S.; Stephens, Ifan E.L.; Bech, Lone

    2012-01-01

    The adsorption dynamics of *OH and *O species at Pt(111) and Cu/Pt(111) near-surface alloy (NSA) surfaces in oxygen-free and O2-saturated 0.1M HClO4 was investigated. Subsurface Cu modifies the electronic structure at the Pt(111) surface resulting in weaker bonding to adsorbates like *OH, *H or *O....... This provides a basis for the high oxygen reduction activity of the NSA, as predicted by density functional theory calculations. The shift in *OH adsorption of around 0.16V towards more positive potentials can be clearly monitored in absence of O2 and under the oxygen reduction reaction (ORR) conditions...... for the Cu/Pt(111) NSA. In both cases, for Pt(111) and NSA, the *OH(*O) adsorption dynamics is very similar in the absence of oxygen and under ORR conditions. Therefore, theoretical assumptions about the coverage of adsorbates in the absence of oxygen can be reasonably extrapolated to the situation when...

  2. Surface-Initiated Graft Atom Transfer Radical Polymerization of Methyl Methacrylate from Chitin Nanofiber Macroinitiator under Dispersion Conditions

    Directory of Open Access Journals (Sweden)

    Ryo Endo

    2015-08-01

    Full Text Available Surface-initiated graft atom transfer radical polymerization (ATRP of methyl methacrylate (MMA from self-assembled chitin nanofibers (CNFs was performed under dispersion conditions. Self-assembled CNFs were initially prepared by regeneration from a chitin ion gel with 1-allyl-3-methylimidazolium bromide using methanol; the product was then converted into the chitin nanofiber macroinitiator by reaction with α-bromoisobutyryl bromide in a dispersion containing N,N-dimethylformamide. Surface-initiated graft ATRP of MMA from the initiating sites on the CNFs was subsequently carried out under dispersion conditions, followed by filtration to obtain the CNF-graft-polyMMA film. Analysis of the product confirmed the occurrence of the graft ATRP on the surface of the CNFs.

  3. 42 CFR 411.4 - Services for which neither the beneficiary nor any other person is legally obligated to pay.

    Science.gov (United States)

    2010-10-01

    ... or pay for that service. (b) Special conditions for services furnished to individuals in custody of... furlough, required to reside in mental health facilities, required to reside in halfway houses, required to...

  4. Adsorption of flexible polymer chains on a surface: Effects of different solvent conditions

    Science.gov (United States)

    Martins, P. H. L.; Plascak, J. A.; Bachmann, M.

    2018-05-01

    Polymer chains undergoing a continuous adsorption-desorption transition are studied through extensive computer simulations. A three-dimensional self-avoiding walk lattice model of a polymer chain grafted onto a surface has been treated for different solvent conditions. We have used an advanced contact-density chain-growth algorithm, in which the density of contacts can be directly obtained. From this quantity, the order parameter and its fourth-order Binder cumulant are computed, as well as the corresponding critical exponents and the adsorption-desorption transition temperature. As the number of configurations with a given number of surface contacts and monomer-monomer contacts is independent of the temperature and solvent conditions, it can be easily applied to get results for different solvent parameter values without the need of any extra simulations. In analogy to continuous magnetic phase transitions, finite-size-scaling methods have been employed. Quite good results for the critical properties and phase diagram of very long single polymer chains have been obtained by properly taking into account the effects of corrections to scaling. The study covers all solvent effects, going from the limit of super-self-avoiding walks, characterized by effective monomer-monomer repulsion, to poor solvent conditions that enable the formation of compact polymer structures.

  5. Reductive precipitation of neptunium on iron surfaces under anaerobic conditions

    Science.gov (United States)

    Yang, H.; Cui, D.; Grolimund, D.; Rondinella, V. V.; Brütsch, R.; Amme, M.; Kutahyali, C.; Wiss, A. T.; Puranen, A.; Spahiu, K.

    2017-12-01

    Reductive precipitation of the radiotoxic nuclide 237Np from nuclear waste on the surface of iron canister material at simulated deep repository conditions was investigated. Pristine polished as well as pre-corroded iron specimens were interacted in a deoxygenated solution containing 10-100 μM Np(V), with 10 mM NaCl and 2 mM NaHCO3 as background electrolytes. The reactivity of each of the two different systems was investigated by analyzing the temporal evolution of the Np concentration in the reservoir. It was observed that pre-oxidized iron specimen with a 40 μm Fe3O4 corrosion layer are considerably more reactive regarding the reduction and immobilization of aqueous Np(V) as compared to pristine polished Fe(0) surfaces. 237Np immobilized by the reactive iron surfaces was characterized by scanning electron microscopy as well as synchrotron-based micro-X-ray fluorescence and X-ray absorption spectroscopy. At the end of experiments, a 5-8 μm thick Np-rich layer was observed to be formed ontop of the Fe3O4 corrosion layer on the iron specimen. The findings from this work are significant in the context of performance assessments of deep geologic repositories using iron as high level radioactive waste (HLW) canister material and are of relevance regarding removing pollutants from contaminated soil or groundwater aquifer systems.

  6. Effect of the Machined Surfaces of AISI 4337 Steel to Cutting Conditions on Dry Machining Lathe

    Science.gov (United States)

    Rahim, Robbi; Napid, Suhardi; Hasibuan, Abdurrozzaq; Rahmah Sibuea, Siti; Yusmartato, Y.

    2018-04-01

    The objective of the research is to obtain a cutting condition which has a good chance of realizing dry machining concept on AISI 4337 steel material by studying surface roughness, microstructure and hardness of machining surface. The data generated from the experiment were then processed and analyzed using the standard Taguchi method L9 (34) orthogonal array. Testing of dry and wet machining used surface test and micro hardness test for each of 27 test specimens. The machining results of the experiments showed that average surface roughness (Raavg) was obtained at optimum cutting conditions when VB 0.1 μm, 0.3 μm and 0.6 μm respectively 1.467 μm, 2.133 μm and 2,800 μm fo r dry machining while which was carried out by wet machining the results obtained were 1,833 μm, 2,667 μm and 3,000 μm. It can be concluded that dry machining provides better surface quality of machinery results than wet machining. Therefore, dry machining is a good choice that may be realized in the manufacturing and automotive industries.

  7. Conductivity enhancement of surface-polymerized polyaniline films via control of processing conditions

    Science.gov (United States)

    Park, Chung Hyoi; Jang, Sung Kyu; Kim, Felix Sunjoo

    2018-01-01

    We investigate a fast and facile approach for the simultaneous synthesis and coating of conducting polyaniline (PANI) onto a substrate and the effects of processing conditions on the electrical properties of the fabricated films. Simultaneous polymerizing and depositing on the substrate forms a thin film with the average thickness of 300 nm and sheet resistance of 304 Ω/sq. Deposition conditions such as polymerization time (3-240 min), temperature (-10 to 40 °C), concentrations of monomer and oxidant (0.1-0.9 M), and type of washing solvents (acetone, water, and/or HCl solution) affect the film thickness, doping state, absorption characteristics, and solid-state nanoscale morphology, therefore affecting the electrical conductivity. Among the conditions, the surface-polymerized PANI film deposited at room temperature with acetone washing showed the highest conductivity of 22.2 S/cm.

  8. Initial conditions of urban permeable surfaces in rainfall-runoff models using Horton’s infiltration

    DEFF Research Database (Denmark)

    Davidsen, Steffen; Löwe, Roland; Høegh Ravn, Nanna

    2017-01-01

    Infiltration is a key process controlling runoff, but varies depending on antecedent conditions. This study provides estimates on initial conditions for urban permeable surfaces via continuous simulation of the infiltration capacity using historical rain data. An analysis of historical rainfall...... records show that accumulated rainfall prior to large rain events does not depend on the return period of the event. Using an infiltration-runoff model we found that for a typical large rain storm, antecedent conditions in general lead to reduced infiltration capacity both for sandy and clayey soils...... and that there is substantial runoff for return periods above 1–10 years....

  9. Plasma treatment of bulk niobium surface for superconducting rf cavities: Optimization of the experimental conditions on flat samples

    Directory of Open Access Journals (Sweden)

    M. Rašković

    2010-11-01

    Full Text Available Accelerator performance, in particular the average accelerating field and the cavity quality factor, depends on the physical and chemical characteristics of the superconducting radio-frequency (SRF cavity surface. Plasma based surface modification provides an excellent opportunity to eliminate nonsuperconductive pollutants in the penetration depth region and to remove the mechanically damaged surface layer, which improves the surface roughness. Here we show that the plasma treatment of bulk niobium (Nb presents an alternative surface preparation method to the commonly used buffered chemical polishing and electropolishing methods. We have optimized the experimental conditions in the microwave glow discharge system and their influence on the Nb removal rate on flat samples. We have achieved an etching rate of 1.7  μm/min⁡ using only 3% chlorine in the reactive mixture. Combining a fast etching step with a moderate one, we have improved the surface roughness without exposing the sample surface to the environment. We intend to apply the optimized experimental conditions to the preparation of single cell cavities, pursuing the improvement of their rf performance.

  10. Corrosion properties of sealing surface material for RPV under abnormal working conditions

    International Nuclear Information System (INIS)

    Liu Jinhua; Wen Yan; Zhang Xuemei; Hou Songmin; Gong Bin; He Yanchun

    2012-01-01

    Based on the corrosion issue of sealing surface material for RPV in some nuclear projects, the corrosion properties of sealing surface material for RPV under abnormal working conditions were investigated. The corrosion behavior of 308L stainless steel were studied by using autoclave in different contents of Cl - solutions, and these samples were observed and analyzed by means of the metalloscope and Scanning electron microscope (SEM). Results show that no pitting, crevice and stress corrosion occurred, when the content of Cl - was lower than 1 mg/L at the temperatures of 270℃ and the pressure of 5.5 MPa. However, with the increase of the content of Cl - , the susceptibility to pitting, crevice and stress corrosion of 308L was enhanced remarkably. (authors)

  11. Influence of annealing condition and multicycle AlGaAs/GaAs structures on the Al0.26Ga0.74As surface morphology

    International Nuclear Information System (INIS)

    Wei, Wenzhe; Wang, Yi; Guo, Xiang; Luo, Zijiang; Zhao, Zhen; Zhou, Haiyue; Ding, Zhao

    2015-01-01

    Highlights: • STM study on the change of AlGaAs surface morphology with varying annealing conditions. • Interesting phenomenon that the subsequent sample has more surface roughness than the previous samples do. A physical model was proposed to explain why the multi-runs growth can increase surface roughness. • The annealing conditions of AlGaAs/GaAs surface were proposed. - Abstract: The influence of annealing temperature, As 4 beam equivalent pressure and multi-runs growth on AlGaAs/GaAs structures was investigated. The real space ultrahigh vacuum scanning tunneling microscopy images showed that AlGaAs/GaAs surface morphology greatly depends on annealing conditions and initial state of surface. The reasons of the surface phenomenon are proposed, and a physical model was proposed to explain why the multi-runs growth structures can increase AlGaAs surface roughness. The reasonable preparation conditions for AlGaAs/GaAs structures were proposed

  12. The effect of root surface conditioning on smear layer removal in periodontal regeneration (a scanning electron microscopic study)

    Science.gov (United States)

    Fidyawati, D.; Soeroso, Y.; Masulili, S. L. C.

    2017-08-01

    The role of root surface conditioning treatment on smear layer removal of human teeth is affected by periodontitis in periodontal regeneration. The objective of this study is to analyze the smear layer on root surface conditioned with 2.1% minocycline HCl ointment (Periocline), and 24% EDTA gel (Prefgel). A total of 10 human teeth indicated for extraction due to chronic periodontitis were collected and root planed. The teeth were sectioned in thirds of the cervical area, providing 30 samples that were divided into three groups - minocycline ointment treatment, 24% EDTA gel treatment, and saline as a control. The samples were examined by scanning electron microscope. No significant differences in levels of smear layer were observed between the minocycline group and the EDTA group (p=0.759). However, there were significant differences in the level of smear layer after root surface treatment in the minocycline and EDTA groups, compared with the control group (p=0.00). There was a relationship between root surface conditioning treatment and smear layer levels following root planing.

  13. Effect of surface stress state on dissolution property of Alloy 690 in simulated primary water condition

    International Nuclear Information System (INIS)

    Kim, Kyung Mo; Shim, Hee-Sang; Lee, Eun Hee; Seo, Myung Ji; Han, Jung Ho; Hur, Do Haeng

    2014-01-01

    The dissolution control of nickel is important to reduce the radioactive dose rate and deterioration of fuel performance in the operation of nuclear power plants (PWR). The corrosion properties are affected by the metal surface residual stress introduced in manufacture process such as work hardening. This work studied the effect of surface modification on the release rate of Alloy 690, nickel-base alloy for a steam generator tube, in the test condition of simulated primary water chemistry in PWRs. The surface stress modification was applied by the electro-polishing and shot peening method. Shot peening process was applied using ceramic beads with different intensities through the variation of air pressure. The corrosion release tests performed at 330degC with LiOH 2 ppm and H 3 BO 4 1200 ppm, DH(dissolved hydrogen) 35 cc/kg (STP) and about 20 ppb of DO(dissolved oxygen) condition. The corrosion release rate was evaluated by a gravimetric analysis method and the surface analysed by SEM and optical microscope. The surface residual stress was measured by an X-ray diffractometer, and the distribution of stress state was evaluated by a micro-hardness tester. The metal ion release rate of alloy 690 was evaluated from the influence of the stress state on the metal surface. The oxide property and structure was affected by the residual stress in the oxide layer. (author)

  14. Synthetic surface for expansion of human mesenchymal stem cells in xeno-free, chemically defined culture conditions.

    Directory of Open Access Journals (Sweden)

    Paula J Dolley-Sonneville

    Full Text Available Human mesenchymal stem cells (HMSCS possess three properties of great interest for the development of cell therapies and tissue engineering: multilineage differentiation, immunomodulation, and production of trophic factors. Efficient ex vivo expansion of hMSCs is a challenging requirement for large scale production of clinical grade cells. Low-cost, robust, scalable culture methods using chemically defined materials need to be developed to address this need. This study describes the use of a xeno-free synthetic peptide acrylate surface, the Corning® Synthemax® Surface, for culture of hMSCs in serum-free, defined medium. Cell performance on the Corning Synthemax Surface was compared to cells cultured on biological extracellular matrix (ECM coatings in xeno-free defined medium and in traditional conditions on tissue culture treated (TCT plastic in fetal bovine serum (FBS supplemented medium. Our results show successful maintenance of hMSCs on Corning Synthemax Surface for eight passages, with cell expansion rate comparable to cells cultured on ECM and significantly higher than for cells in TCT/FBS condition. Importantly, on the Corning Synthemax Surface, cells maintained elongated, spindle-like morphology, typical hMSC marker profile and in vitro multilineage differentiation potential. We believe the Corning Synthemax Surface, in combination with defined media, provides a complete synthetic, xeno-free, cell culture system for scalable production of hMSCs.

  15. Analysis of influence of heat exchange conditions on the outer surface of the lithium-ion battery to electrolyte temperature under the conditions of high current loads

    Directory of Open Access Journals (Sweden)

    Krasnoshlykov Alexander

    2017-01-01

    Full Text Available Numerical analysis of thermal conditions of a lithium-ion battery using the software package ANSYS Electric and ANSYS Fluent has been carried out. Time dependence of the electrolyte temperature on the various heat exchange conditions on the outer surface has been obtained.

  16. Surface microhardness of three thicknesses of mineral trioxide aggregate in different setting conditions

    Directory of Open Access Journals (Sweden)

    Noushin Shokouhinejad

    2014-11-01

    Full Text Available Objectives This study aimed to compare the surface microhardness of mineral trioxide aggregate (MTA samples having different thicknesses and exposed to human blood from one side and with or without a moist cotton pellet on the other side. Materials and Methods Ninety cylindrical molds with three heights of 2, 4, and 6 mm were fabricated. In group 1 (dry condition, molds with heights of 2, 4, and 6 mm (10 molds of each were filled with ProRoot MTA (Dentsply Tulsa Dental, and the upper surface of the material was not exposed to any additional moisture. In groups 2 and 3, a distilled water- or phosphate-buffered saline (PBS-moistened cotton pellet was placed on the upper side of MTA, respectively. The lower side of the molds in all the groups was in contact with human blood-wetted foams. After 4 day, the Vickers microhardness of the upper surface of MTA was measured. Results In the dry condition, the 4 and 6 mm-thick MTA samples showed significantly lower microhardness than the 2 mm-thick samples (p = 0.003 and p = 0.001, respectively. However, when a distilled water- or PBS-moistened cotton pellet was placed over the MTA, no significant difference was found between the surface microhardness of samples having the abovementioned three thicknesses of the material (p = 0.210 and p = 0.112, respectively. Conclusions It could be concluded that a moist cotton pellet must be placed over the 4 to 6 mm-thick MTA for better hydration of the material. However, this might not be necessary when 2 mm-thick MTA is used.

  17. The impact of changing surface ocean conditions on the dissolution of aerosol iron

    Science.gov (United States)

    Fishwick, Matthew P.; Sedwick, Peter N.; Lohan, Maeve C.; Worsfold, Paul J.; Buck, Kristen N.; Church, Thomas M.; Ussher, Simon J.

    2014-11-01

    The proportion of aerosol iron (Fe) that dissolves in seawater varies greatly and is dependent on aerosol composition and the physicochemical conditions of seawater, which may change depending on location or be altered by global environmental change. Aerosol and surface seawater samples were collected in the Sargasso Sea and used to investigate the impact of these changing conditions on aerosol Fe dissolution in seawater. Our data show that seawater temperature, pH, and oxygen concentration, within the range of current and projected future values, had no significant effect on the dissolution of aerosol Fe. However, the source and composition of aerosols had the most significant effect on the aerosol Fe solubility, with the most anthropogenically influenced samples having the highest fractional solubility (up to 3.2%). The impact of ocean warming and acidification on aerosol Fe dissolution is therefore unlikely to be as important as changes in land usage and fossil fuel combustion. Our experimental results also reveal important changes in the size distribution of soluble aerosol Fe in solution, depending on the chemical conditions of seawater. Under typical conditions, the majority (77-100%) of Fe released from aerosols into ambient seawater existed in the colloidal (0.02-0.4 µm) size fraction. However, in the presence of a sufficient concentration of strong Fe-binding organic ligands (10 nM) most of the aerosol-derived colloidal Fe was converted to soluble Fe (<0.02 µm). This finding highlights the potential importance of organic ligands in retaining aerosol Fe in a biologically available form in the surface ocean.

  18. Diagnostic measurements on the great machines conditions of lignite surface mines

    Energy Technology Data Exchange (ETDEWEB)

    Helebrant, F.; Jurman, J.; Fries, J. [Technical University of Ostrava, Ostrava-Poruba (Czech Republic)

    2005-07-01

    An analysis of the diagnosis of loading and service dependability of a rail-mounted excavator used in surface lignite mining is described. Wheel power vibrations in electric motor bearings and electric motor input bearings to the gearbox were measured in situ, in horizontal, vertical, and axial directions. The data were analyzed using a mathematical relationship. The results are presented in a loading diagram that shows the deterioration and the acceptable lower bound of machine conditions over time. Work is continuing. 5 refs., 1 fig.

  19. Optimization of Coolant Technique Conditions for Machining A319 Aluminium Alloy Using Response Surface Method (RSM)

    Science.gov (United States)

    Zainal Ariffin, S.; Razlan, A.; Ali, M. Mohd; Efendee, A. M.; Rahman, M. M.

    2018-03-01

    Background/Objectives: The paper discusses about the optimum cutting parameters with coolant techniques condition (1.0 mm nozzle orifice, wet and dry) to optimize surface roughness, temperature and tool wear in the machining process based on the selected setting parameters. The selected cutting parameters for this study were the cutting speed, feed rate, depth of cut and coolant techniques condition. Methods/Statistical Analysis Experiments were conducted and investigated based on Design of Experiment (DOE) with Response Surface Method. The research of the aggressive machining process on aluminum alloy (A319) for automotive applications is an effort to understand the machining concept, which widely used in a variety of manufacturing industries especially in the automotive industry. Findings: The results show that the dominant failure mode is the surface roughness, temperature and tool wear when using 1.0 mm nozzle orifice, increases during machining and also can be alternative minimize built up edge of the A319. The exploration for surface roughness, productivity and the optimization of cutting speed in the technical and commercial aspects of the manufacturing processes of A319 are discussed in automotive components industries for further work Applications/Improvements: The research result also beneficial in minimizing the costs incurred and improving productivity of manufacturing firms. According to the mathematical model and equations, generated by CCD based RSM, experiments were performed and cutting coolant condition technique using size nozzle can reduces tool wear, surface roughness and temperature was obtained. Results have been analyzed and optimization has been carried out for selecting cutting parameters, shows that the effectiveness and efficiency of the system can be identified and helps to solve potential problems.

  20. Do European Standard Disinfectant tests truly simulate in-use microbial and organic soiling conditions on food preparation surfaces?

    Science.gov (United States)

    Meyer, B; Morin, V N; Rödger, H-J; Holah, J; Bird, C

    2010-04-01

    The results from European standard disinfectant tests are used as one basis to approve the use of disinfectants in Europe. The design of these laboratory-based tests should thus simulate as closely as possible the practical conditions and challenges that the disinfectants would encounter in use. No evidence is available that the organic and microbial loading in these tests simulates actual levels in the food service sector. Total organic carbon (TOC) and total viable count (TVC) were determined on 17 visibly clean and 45 visibly dirty surfaces in two restaurants and the food preparation surfaces of a large retail store. These values were compared to reference values recovered from surfaces soiled with the organic and microbial loading, following the standard conditions of the European Surface Test for bactericidal efficacy, EN 13697. The TOC reference values for clean and dirty conditions were higher than the data from practice, but cannot be regarded as statistical outliers. This was considered as a conservative assessment; however, as additional nine TOC samples from visibly dirty surfaces were discarded from the analysis, as their loading made them impossible to process. Similarly, the recovery of test organisms from surfaces contaminated according to EN 13697 was higher than the TVC from visibly dirty surfaces in practice; though they could not be regarded as statistical outliers of the whole data field. No correlation was found between TVC and TOC in the sampled data, which re-emphasizes the potential presence of micro-organisms on visibly clean surfaces and thus the need for the same degree of disinfection as visibly dirty surfaces. The organic soil and the microbial burden used in EN disinfectant standards represent a realistic worst-case scenario for disinfectants used in the food service and food-processing areas.

  1. Influence of boundary conditions on the existence and stability of minimal surfaces of revolution made of soap films

    Science.gov (United States)

    Salkin, Louis; Schmit, Alexandre; Panizza, Pascal; Courbin, Laurent

    2014-09-01

    Because of surface tension, soap films seek the shape that minimizes their surface energy and thus their surface area. This mathematical postulate allows one to predict the existence and stability of simple minimal surfaces. After briefly recalling classical results obtained in the case of symmetric catenoids that span two circular rings with the same radius, we discuss the role of boundary conditions on such shapes, working with two rings having different radii. We then investigate the conditions of existence and stability of other shapes that include two portions of catenoids connected by a planar soap film and half-symmetric catenoids for which we introduce a method of observation. We report a variety of experimental results including metastability—an hysteretic evolution of the shape taken by a soap film—explained using simple physical arguments. Working by analogy with the theory of phase transitions, we conclude by discussing universal behaviors of the studied minimal surfaces in the vicinity of their existence thresholds.

  2. A Snow Density Dataset for Improving Surface Boundary Conditions in Greenland Ice Sheet Firn Modeling

    Directory of Open Access Journals (Sweden)

    Robert S. Fausto

    2018-05-01

    Full Text Available The surface snow density of glaciers and ice sheets is of fundamental importance in converting volume to mass in both altimetry and surface mass balance studies, yet it is often poorly constrained. Site-specific surface snow densities are typically derived from empirical relations based on temperature and wind speed. These parameterizations commonly calculate the average density of the top meter of snow, thereby systematically overestimating snow density at the actual surface. Therefore, constraining surface snow density to the top 0.1 m can improve boundary conditions in high-resolution firn-evolution modeling. We have compiled an extensive dataset of 200 point measurements of surface snow density from firn cores and snow pits on the Greenland ice sheet. We find that surface snow density within 0.1 m of the surface has an average value of 315 kg m−3 with a standard deviation of 44 kg m−3, and has an insignificant annual air temperature dependency. We demonstrate that two widely-used surface snow density parameterizations dependent on temperature systematically overestimate surface snow density over the Greenland ice sheet by 17–19%, and that using a constant density of 315 kg m−3 may give superior results when applied in surface mass budget modeling.

  3. Surface crack behavior in socket weld of nuclear piping under fatigue loading condition

    International Nuclear Information System (INIS)

    Choi, Y.H.; Kim, J.S.; Choi, S.Y.

    2005-01-01

    The ASME B and PV Code Sec. III allows the socket weld for the nuclear piping in spite of the weakness on the weld integrity. Recently, the integrity of the socket weld is regarded as a safety concern in nuclear power plants because many failures and leaks have been reported in the socket weld. OPDE (OECD Piping Failure Data Exchange) database lists 108 socket weld failures among 2,399 nuclear piping failure cases during 1970 to 2001. Eleven failures in the socket weld were also reported in Korean NPPs. Many failure cases showed that the root cause of the failure is the fatigue and the gap requirement for the socket weld given in ASME Code was not satisfied. The purpose of this paper is to evaluate the fatigue crack behavior of a surface crack in the socket weld under fatigue loading condition considering the gap effect. Three-dimensional finite element analysis was performed to estimate the fatigue crack behavior of the surface crack. Three types of loading conditions such as the deflection due to vibration, the pressure transient ranging from P=0 to 15.51 MPa, and the thermal transient ranging from T=25 C to 288 C were considered. The results are as follows; 1) The socket weld is susceptible to the vibration where the vibration levels exceed the requirement in the ASME operation and maintenance (OM) Code. 2) The effect of pressure or temperature transient load on the socket weld integrity is not significant. 3) No-gap condition gives very high possibility of the crack initiation at the socket weld under vibration loading condition. 4) For the specific systems having the vibration condition to exceed the requirement in the ASME Code OM and/or the transient loading condition from P=0 and T=25 C to P=15.51 MPa and T=288 C, radiographic examination to examine the gap during the construction stage is recommended. (orig.)

  4. Importance of initial buoyancy field on evolution of mantle thermal structure: Implications of surface boundary conditions

    Directory of Open Access Journals (Sweden)

    Petar Glišović

    2015-01-01

    Full Text Available Although there has been significant progress in the seismic imaging of mantle heterogeneity, the outstanding issue that remains to be resolved is the unknown distribution of mantle temperature anomalies in the distant geological past that give rise to the present-day anomalies inferred by global tomography models. To address this question, we present 3-D convection models in compressible and self-gravitating mantle initialised by different hypothetical temperature patterns. A notable feature of our forward convection modelling is the use of self-consistent coupling of the motion of surface tectonic plates to the underlying mantle flow, without imposing prescribed surface velocities (i.e., plate-like boundary condition. As an approximation for the surface mechanical conditions before plate tectonics began to operate we employ the no-slip (rigid boundary condition. A rigid boundary condition demonstrates that the initial thermally-dominated structure is preserved, and its geographical location is fixed during the evolution of mantle flow. Considering the impact of different assumed surface boundary conditions (rigid and plate-like on the evolution of thermal heterogeneity in the mantle we suggest that the intrinsic buoyancy of seven superplumes is most-likely resolved in the tomographic images of present-day mantle thermal structure. Our convection simulations with a plate-like boundary condition reveal that the evolution of an initial cold anomaly beneath the Java-Indonesian trench system yields a long-term, stable pattern of thermal heterogeneity in the lowermost mantle that resembles the present-day Large Low Shear Velocity Provinces (LLSVPs, especially below the Pacific. The evolution of subduction zones may be, however, influenced by the mantle-wide flow driven by deeply-rooted and long-lived superplumes since Archean times. These convection models also detect the intrinsic buoyancy of the Perm Anomaly that has been identified as a unique

  5. Characterizing water surface elevation under different flow conditions for the upcoming SWOT mission

    Science.gov (United States)

    Domeneghetti, A.; Schumann, G. J.-P.; Frasson, R. P. M.; Wei, R.; Pavelsky, T. M.; Castellarin, A.; Brath, A.; Durand, M. T.

    2018-06-01

    The Surface Water and Ocean Topography satellite mission (SWOT), scheduled for launch in 2021, will deliver two-dimensional observations of water surface heights for lakes, rivers wider than 100 m and oceans. Even though the scientific literature has highlighted several fields of application for the expected products, detailed simulations of the SWOT radar performance for a realistic river scenario have not been presented in the literature. Understanding the error of the most fundamental "raw" SWOT hydrology product is important in order to have a greater awareness about strengths and limits of the forthcoming satellite observations. This study focuses on a reach (∼140 km in length) of the middle-lower portion of the Po River, in Northern Italy, and, to date, represents one of the few real-case analyses of the spatial patterns in water surface elevation accuracy expected from SWOT. The river stretch is characterized by a main channel varying from 100 to 500 m in width and a large floodplain (up to 5 km) delimited by a system of major embankments. The simulation of the water surface along the Po River for different flow conditions (high, low and mean annual flows) is performed with inputs from a quasi-2D model implemented using detailed topographic and bathymetric information (LiDAR, 2 m resolution). By employing a simulator that mimics many SWOT satellite sensor characteristics and generates proxies of the remotely sensed hydrometric data, this study characterizes the spatial observations potentially provided by SWOT. We evaluate SWOT performance under different hydraulic conditions and assess possible effects of river embankments, river width, river topography and distance from the satellite ground track. Despite analyzing errors from the raw radar pixel cloud, which receives minimal processing, the present study highlights the promising potential of this Ka-band interferometer for measuring water surface elevations, with mean elevation errors of 0.1 cm and 21

  6. The influence of surface type on the absorbed radiation by a human under hot, dry conditions

    Science.gov (United States)

    Hardin, A. W.; Vanos, J. K.

    2018-01-01

    Given the predominant use of heat-retaining materials in urban areas, numerous studies have addressed the urban heat island mitigation potential of various "cool" options, such as vegetation and high-albedo surfaces. The influence of altered radiational properties of such surfaces affects not only the air temperature within a microclimate, but more importantly the interactions of long- and short-wave radiation fluxes with the human body. Minimal studies have assessed how cool surfaces affect thermal comfort via changes in absorbed radiation by a human ( R abs) using real-world, rather than modeled, urban field data. The purpose of the current study is to assess the changes in the absorbed radiation by a human—a critical component of human energy budget models—based on surface type on hot summer days (air temperatures > 38.5∘C). Field tests were conducted using a high-end microclimate station under predominantly clear sky conditions over ten surfaces with higher sky view factors in Lubbock, Texas. Three methods were used to measure and estimate R abs: a cylindrical radiation thermometer (CRT), a net radiometer, and a theoretical estimation model. Results over dry surfaces suggest that the use of high-albedo surfaces to reduce overall urban heat gain may not improve acute human thermal comfort in clear conditions due to increased reflected radiation. Further, the use of low-cost instrumentation, such as the CRT, shows potential in quantifying radiative heat loads within urban areas at temporal scales of 5-10 min or greater, yet further research is needed. Fine-scale radiative information in urban areas can aid in the decision-making process for urban heat mitigation using non-vegetated urban surfaces, with surface type choice is dependent on the need for short-term thermal comfort, or reducing cumulative heat gain to the urban fabric.

  7. Method for Pre-Conditioning a Measured Surface Height Map for Model Validation

    Science.gov (United States)

    Sidick, Erkin

    2012-01-01

    This software allows one to up-sample or down-sample a measured surface map for model validation, not only without introducing any re-sampling errors, but also eliminating the existing measurement noise and measurement errors. Because the re-sampling of a surface map is accomplished based on the analytical expressions of Zernike-polynomials and a power spectral density model, such re-sampling does not introduce any aliasing and interpolation errors as is done by the conventional interpolation and FFT-based (fast-Fourier-transform-based) spatial-filtering method. Also, this new method automatically eliminates the measurement noise and other measurement errors such as artificial discontinuity. The developmental cycle of an optical system, such as a space telescope, includes, but is not limited to, the following two steps: (1) deriving requirements or specs on the optical quality of individual optics before they are fabricated through optical modeling and simulations, and (2) validating the optical model using the measured surface height maps after all optics are fabricated. There are a number of computational issues related to model validation, one of which is the "pre-conditioning" or pre-processing of the measured surface maps before using them in a model validation software tool. This software addresses the following issues: (1) up- or down-sampling a measured surface map to match it with the gridded data format of a model validation tool, and (2) eliminating the surface measurement noise or measurement errors such that the resulted surface height map is continuous or smoothly-varying. So far, the preferred method used for re-sampling a surface map is two-dimensional interpolation. The main problem of this method is that the same pixel can take different values when the method of interpolation is changed among the different methods such as the "nearest," "linear," "cubic," and "spline" fitting in Matlab. The conventional, FFT-based spatial filtering method used to

  8. MAARGHA: A Prototype System for Road Condition and Surface Type Estimation by Fusing Multi-Sensor Data

    Directory of Open Access Journals (Sweden)

    Deepak Rajamohan

    2015-07-01

    Full Text Available Road infrastructure in countries like India is expanding at a rapid pace and is becoming increasingly difficult for authorities to identify and fix the bad roads in time. Current Geographical Information Systems (GIS lack information about on-road features like road surface type, speed breakers and dynamic attribute data like the road quality. Hence there is a need to build road monitoring systems capable of collecting such information periodically. Limitations of satellite imagery with respect to the resolution and availability, makes road monitoring primarily an on-field activity. Monitoring is currently performed using special vehicles that are fitted with expensive laser scanners and need skilled resource besides providing only very low coverage. Hence such systems are not suitable for continuous road monitoring. Cheaper alternative systems using sensors like accelerometer and GPS (Global Positioning System exists but they are not equipped to achieve higher information levels. This paper presents a prototype system MAARGHA (MAARGHA in Sanskrit language means an eternal path to solution, which demonstrates that it can overcome the disadvantages of the existing systems by fusing multi-sensory data like camera image, accelerometer data and GPS trajectory at an information level, apart from providing additional road information like road surface type. MAARGHA has been tested across different road conditions and sensor data characteristics to assess its potential applications in real world scenarios. The developed system achieves higher information levels when compared to state of the art road condition estimation systems like Roadroid. The system performance in road surface type classification is dependent on the local environmental conditions at the time of imaging. In our study, the road surface type classification accuracy reached 100% for datasets with near ideal environmental conditions and dropped down to 60% for datasets with shadows and

  9. Probing adsorption phenomena on a single crystal Pt-alloy surface under oxygen reduction reaction conditions

    International Nuclear Information System (INIS)

    Bondarenko, Alexander S.; Stephens, Ifan E.L.; Bech, Lone; Chorkendorff, Ib

    2012-01-01

    Highlights: ► Impedance spectroscopy of Cu/Pt(1 1 1) near-surface alloy and Pt(1 1 1). ► Presence of oxygen changes little the adsorption dynamics. ► Adsorption dynamics similar on alloy and Pt(1 1 1). ► Electrosorption phenomena on alloy shifted in potential, relative to Pt(1 1 1). - Abstract: The adsorption dynamics of *OH and *O species at Pt(1 1 1) and Cu/Pt(1 1 1) near-surface alloy (NSA) surfaces in oxygen-free and O 2 -saturated 0.1 M HClO 4 was investigated. Subsurface Cu modifies the electronic structure at the Pt(1 1 1) surface resulting in weaker bonding to adsorbates like *OH, *H or *O. This provides a basis for the high oxygen reduction activity of the NSA, as predicted by density functional theory calculations. The shift in *OH adsorption of around 0.16 V towards more positive potentials can be clearly monitored in absence of O 2 and under the oxygen reduction reaction (ORR) conditions for the Cu/Pt(1 1 1) NSA. In both cases, for Pt(1 1 1) and NSA, the *OH(*O) adsorption dynamics is very similar in the absence of oxygen and under ORR conditions. Therefore, theoretical assumptions about the coverage of adsorbates in the absence of oxygen can be reasonably extrapolated to the situation when oxygen reduction takes place at the surface. A ∼5-fold improvement in the ORR activity over the Pt(1 1 1) at 0.9 V (RHE) was measured for the Cu/Pt(1 1 1) near-surface alloy.

  10. Surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars

    Science.gov (United States)

    Bishop, Janice L.; Fairén, Alberto G.; Michalski, Joseph R.; Gago-Duport, Luis; Baker, Leslie L.; Velbel, Michael A.; Gross, Christoph; Rampe, Elizabeth B.

    2018-03-01

    The ancient rock record for Mars has long been at odds with climate modelling. The presence of valley networks, dendritic channels and deltas on ancient terrains points towards running water and fluvial erosion on early Mars1, but climate modelling indicates that long-term warm conditions were not sustainable2. Widespread phyllosilicates and other aqueous minerals on the Martian surface3-6 provide additional evidence that an early wet Martian climate resulted in surface weathering. Some of these phyllosilicates formed in subsurface crustal environments5, with no association with the Martian climate, while other phyllosilicate-rich outcrops exhibit layered morphologies and broad stratigraphies7 consistent with surface formation. Here, we develop a new geochemical model for early Mars to explain the formation of these clay-bearing rocks in warm and wet surface locations. We propose that sporadic, short-term warm and wet environments during a generally cold early Mars enabled phyllosilicate formation without requiring long-term warm and wet conditions. We conclude that Mg-rich clay-bearing rocks with lateral variations in mixed Fe/Mg smectite, chlorite, talc, serpentine and zeolite occurrences formed in subsurface hydrothermal environments, whereas dioctahedral (Al/Fe3+-rich) smectite and widespread vertical horizonation of Fe/Mg smectites, clay assemblages and sulphates formed in variable aqueous environments on the surface of Mars. Our model for aluminosilicate formation on Mars is consistent with the observed geological features, diversity of aqueous mineralogies in ancient surface rocks and state-of-the-art palaeoclimate scenarios.

  11. Can environmental conditions trigger cyanobacterial surfaces and following carbonate formation: implication for biomineralization and biotechnology

    Science.gov (United States)

    Paulo, C.; Dittrich, M.; Zhu, T.

    2015-12-01

    In this presentation we will give an overview what kind of the factors may trigger carbonate formations at the cell surfaces under a variety of environmental conditions. As examples, we will present the results from our recent studies on formation of calcium carbonates, dolomites and bio-cements. The extracellular polymeric substances (EPS) in the Synechococcuscell envelope are recognized key players in the nucleation of carbonates in marine and freshwater environments. Yet, little is known about a nutrient contents control over the molecular composition of Synechococcus cell envelope, and consequently, biomineralization. In the first study, we investigated how a variation of the phosphorus (P) in the growth media can lead to changes in the surface reactivity of the cells and impact their ability to form carbonates. The objective of the second study is to gain insights into the spatial distribution of cyanobacterial EPS and dolomite from different sediment layers of Khor Al-Adaid sabkha (Qatar). Here, we characterized microbial mats on molecular level in respect of organic and inorganic components using in-situ 2D Raman spectroscopy and Atomic Force Microscopy (AFM) were used. Additionally, 2D chemical maps of sediment layers documented spectral characterizations of minerals and organic matter of microbial origins at high spatial resolution. Finally, we will show the results from the experiments with auto-phototrophic cyanobacteria Gloeocapsa PCC73106, which habitat on the monument surfaces, towards its application for bio-concrete, a product of microbial carbonate precipitation. We studied the biomineralization in biofilm forming Gloeocapsa PCC73106 on the concrete surface as a pre-requirement for microbial carbonate precipitation. Biomineralization on the concrete surface by live cells and killed cells were compared with that under the abiotic condition. Our experiments allow us to conclude that environmental conditions play a significant role in the control of

  12. Influence of different land surfaces on atmospheric conditions measured by a wireless sensor network

    Science.gov (United States)

    Lengfeld, Katharina; Ament, Felix

    2010-05-01

    Atmospheric conditions close to the surface, like temperature, wind speed and humidity, vary on small scales because of surface heterogeneities. Therefore, the traditional measuring approach of using a single, highly accurate station is of limited representativeness for a larger domain, because it is not able to determine these small scale variabilities. However, both the variability and the domain averages are important information for the development and validation of atmospheric models and soil-vegetation-atmosphere-transfer (SVAT) schemes. Due to progress in microelectronics it is possible to construct networks of comparably cheap meteorological stations with moderate accuracy. Such a network provides data in high spatial and temporal resolution. The EPFL Lausanne developed such a network called SensorScope, consisting of low cost autonomous stations. Each station observes air and surface temperature, humidity, wind direction and speed, incoming solar radiation, precipitations, soil moisture and soil temperature and sends the data via radio communication to a base station. This base station forwards the collected data via GSM/GPRS to a central server. Within the FLUXPAT project in August 2009 we deployed 15 stations as a twin transect near Jülich, Germany. One aim of this first experiment was to test the quality of the low cost sensors by comparing them to more accurate reference measurements. It turned out, that although the network is not highly accurate, the measurements are consistent. Consequently an analysis of the pattern of atmospheric conditions is feasible. For example, we detect a variability of ± 0.5K in the mean temperature at a distance of only 2.3 km. The transect covers different types of vegetation and a small river. Therefore, we analyzed the influence of different land surfaces and the distance to the river on meteorological conditions. On the one hand, some results meet our expectations, e.g. the relative humidity decreases with increasing

  13. A new shape reproduction method based on the Cauchy-condition surface for real-time tokamak reactor control

    International Nuclear Information System (INIS)

    Kurihara, K.

    2000-01-01

    A new shape reproduction method is investigated on the basis of an applied mathematical approach. An analytically exact solution of Maxwell's equations in a static current field yields an (boundary) integral equation. In application of this equation to tokamak plasma shape reproduction, it is made clear that a Cauchy condition (both Dirichlet and Neumann conditions) on a hypothetical surface is necessarily identified. To calculate the Cauchy condition using magnetic sensor signals, conversion to numerical formulation of this method is conducted. Then, reproduction errors by this method are evaluated through two numerical tests: The first test uses ideal signals produced from a full equilibrium code in the JT-60 geometry, and the second test uses actual sensor signals in JT-60 experiments. In addition, it is shown that positioning and shape of the Cauchy condition surface is insensitive to reproduction error. Finally, this method is clarified to have preferable features for real-time tokamak reactor control

  14. A system to test the ground surface conditions of construction sites--for safe and efficient work without physical strain.

    Science.gov (United States)

    Koningsveld, Ernst; van der Grinten, Maarten; van der Molen, Henk; Krause, Frank

    2005-07-01

    Ground surface conditions on construction sites have an important influence on the health and safety of workers and their productivity. The development of an expert-based "working conditions evaluation" system is described, intended to assist site managers in recognising unsatisfactory ground conditions and remedying these. The system was evaluated in the period 2002-2003. The evaluation shows that companies recognize poor soil/ground conditions as problematic, but are not aware of the specific physical workload hazards. The developed methods allow assessment of the ground surface quality and selection of appropriate measures for improvement. However, barriers exist at present to wide implementation of the system across the industry. Most significant of these is that responsibility for a site's condition is not clearly located within contracting arrangements, nor is it a topic of serious negotiation.

  15. 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

  16. Surface-water nutrient conditions and sources in the United States Pacific Northwest

    Science.gov (United States)

    Wise, D.R.; Johnson, H.M.

    2011-01-01

    The SPAtially Referenced Regressions On Watershed attributes (SPARROW) model was used to perform an assessment of surface-water nutrient conditions and to identify important nutrient sources in watersheds of the Pacific Northwest region of the United States (U.S.) for the year 2002. Our models included variables representing nutrient sources as well as landscape characteristics that affect nutrient delivery to streams. Annual nutrient yields were higher in watersheds on the wetter, west side of the Cascade Range compared to watersheds on the drier, east side. High nutrient enrichment (relative to the U.S. Environmental Protection Agency's recommended nutrient criteria) was estimated in watersheds throughout the region. Forest land was generally the largest source of total nitrogen stream load and geologic material was generally the largest source of total phosphorus stream load generated within the 12,039 modeled watersheds. These results reflected the prevalence of these two natural sources and the low input from other nutrient sources across the region. However, the combined input from agriculture, point sources, and developed land, rather than natural nutrient sources, was responsible for most of the nutrient load discharged from many of the largest watersheds. Our results provided an understanding of the regional patterns in surface-water nutrient conditions and should be useful to environmental managers in future water-quality planning efforts.

  17. Foam Core Particleboards with Intumescent FRT Veneer: Cone Calorimeter Testing With Varying Adhesives, Surface Layer Thicknesses, and Processing Conditions

    Science.gov (United States)

    Mark A. Dietenberger; Johannes Welling; Ali Shalbafan

    2014-01-01

    Intumescent FRT Veneers adhered to the surface of foam core particleboard to provide adequate fire protection were evaluated by means of cone calorimeter tests (ASTM E1354). The foam core particleboards were prepared with variations in surface layer treatment, adhesives, surface layer thicknesses, and processing conditions. Ignitability, heat release rate profile, peak...

  18. Impact of chemical lateral boundary conditions in a regional air quality forecast model on surface ozone predictions during stratospheric intrusions

    Science.gov (United States)

    Pendlebury, Diane; Gravel, Sylvie; Moran, Michael D.; Lupu, Alexandru

    2018-02-01

    A regional air quality forecast model, GEM-MACH, is used to examine the conditions under which a limited-area air quality model can accurately forecast near-surface ozone concentrations during stratospheric intrusions. Periods in 2010 and 2014 with known stratospheric intrusions over North America were modelled using four different ozone lateral boundary conditions obtained from a seasonal climatology, a dynamically-interpolated monthly climatology, global air quality forecasts, and global air quality reanalyses. It is shown that the mean bias and correlation in surface ozone over the course of a season can be improved by using time-varying ozone lateral boundary conditions, particularly through the correct assignment of stratospheric vs. tropospheric ozone along the western lateral boundary (for North America). Part of the improvement in surface ozone forecasts results from improvements in the characterization of near-surface ozone along the lateral boundaries that then directly impact surface locations near the boundaries. However, there is an additional benefit from the correct characterization of the location of the tropopause along the western lateral boundary such that the model can correctly simulate stratospheric intrusions and their associated exchange of ozone from stratosphere to troposphere. Over a three-month period in spring 2010, the mean bias was seen to improve by as much as 5 ppbv and the correlation by 0.1 depending on location, and on the form of the chemical lateral boundary condition.

  19. Improving the Yule-Nielsen modified Neugebauer model by dot surface coverages depending on the ink superposition conditions

    Science.gov (United States)

    Hersch, Roger David; Crete, Frederique

    2005-01-01

    Dot gain is different when dots are printed alone, printed in superposition with one ink or printed in superposition with two inks. In addition, the dot gain may also differ depending on which solid ink the considered halftone layer is superposed. In a previous research project, we developed a model for computing the effective surface coverage of a dot according to its superposition conditions. In the present contribution, we improve the Yule-Nielsen modified Neugebauer model by integrating into it our effective dot surface coverage computation model. Calibration of the reproduction curves mapping nominal to effective surface coverages in every superposition condition is carried out by fitting effective dot surfaces which minimize the sum of square differences between the measured reflection density spectra and reflection density spectra predicted according to the Yule-Nielsen modified Neugebauer model. In order to predict the reflection spectrum of a patch, its known nominal surface coverage values are converted into effective coverage values by weighting the contributions from different reproduction curves according to the weights of the contributing superposition conditions. We analyze the colorimetric prediction improvement brought by our extended dot surface coverage model for clustered-dot offset prints, thermal transfer prints and ink-jet prints. The color differences induced by the differences between measured reflection spectra and reflection spectra predicted according to the new dot surface estimation model are quantified on 729 different cyan, magenta, yellow patches covering the full color gamut. As a reference, these differences are also computed for the classical Yule-Nielsen modified spectral Neugebauer model incorporating a single halftone reproduction curve for each ink. Taking into account dot surface coverages according to different superposition conditions considerably improves the predictions of the Yule-Nielsen modified Neugebauer model. In

  20. Surface-Water Conditions in Georgia, Water Year 2005

    Science.gov (United States)

    Painter, Jaime A.; Landers, Mark N.

    2007-01-01

    INTRODUCTION The U.S. Geological Survey (USGS) Georgia Water Science Center-in cooperation with Federal, State, and local agencies-collected surface-water streamflow, water-quality, and ecological data during the 2005 Water Year (October 1, 2004-September 30, 2005). These data were compiled into layers of an interactive ArcReaderTM published map document (pmf). ArcReaderTM is a product of Environmental Systems Research Institute, Inc (ESRI?). Datasets represented on the interactive map are * continuous daily mean streamflow * continuous daily mean water levels * continuous daily total precipitation * continuous daily water quality (water temperature, specific conductance dissolved oxygen, pH, and turbidity) * noncontinuous peak streamflow * miscellaneous streamflow measurements * lake or reservoir elevation * periodic surface-water quality * periodic ecological data * historical continuous daily mean streamflow discontinued prior to the 2005 water year The map interface provides the ability to identify a station in spatial reference to the political boundaries of the State of Georgia and other features-such as major streams, major roads, and other collection stations. Each station is hyperlinked to a station summary showing seasonal and annual stream characteristics for the current year and for the period of record. For continuous discharge stations, the station summary includes a one page graphical summary page containing five graphs, a station map, and a photograph of the station. The graphs provide a quick overview of the current and period-of-record hydrologic conditions of the station by providing a daily mean discharge graph for the water year, monthly statistics graph for the water year and period of record, an annual mean streamflow graph for the period of record, an annual minimum 7-day average streamflow graph for the period of record, and an annual peak streamflow graph for the period of record. Additionally, data can be accessed through the layer's link

  1. Surface chemistry of tribochemical reactions explored in ultrahigh vacuum conditions

    International Nuclear Information System (INIS)

    Lara-Romero, Javier; Maya-Yescas, Rafael; Rico-Cerda, Jose Luis; Rivera-Rojas, Jose Luis; Castillo, Fernando Chinas; Kaltchev, Matey; Tysoe, Wilfred T.

    2006-01-01

    The thermal decomposition of model extreme-pressure lubricant additives on clean iron was studied in ultrahigh vacuum conditions using molecular beam strategies. Methylene chloride and chloroform react to deposit a solid film consisting of FeCl 2 and carbon, and evolve only hydrogen into the gas phase. No gas-phase products and less carbon on the surface are detected in the case of carbon tetrachloride. Dimethyl and diethyl disulfide react on clean iron to deposit a saturated sulfur plus carbon layer at low temperatures (∼600 K) and an iron sulfide film onto a Fe + C underlayer at higher temperatures (∼950 K). Methane is the only gas-phase product when dimethyl disulfide reacts with iron. Ethylene and hydrogen are detected when diethyl disulfide is used

  2. Influence of annealing condition and multicycle AlGaAs/GaAs structures on the Al{sub 0.26}Ga{sub 0.74}As surface morphology

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Wenzhe; Wang, Yi; Guo, Xiang [College of Big Data and Information Engineering, Guizhou University, Guiyang 550025 (China); Luo, Zijiang [School of Education Administration, Guizhou University of Finance and Economics, Guiyang 550025 (China); Zhao, Zhen; Zhou, Haiyue [College of Big Data and Information Engineering, Guizhou University, Guiyang 550025 (China); Ding, Zhao, E-mail: zding@gzu.edu.cn [College of Big Data and Information Engineering, Guizhou University, Guiyang 550025 (China)

    2015-08-01

    Highlights: • STM study on the change of AlGaAs surface morphology with varying annealing conditions. • Interesting phenomenon that the subsequent sample has more surface roughness than the previous samples do. A physical model was proposed to explain why the multi-runs growth can increase surface roughness. • The annealing conditions of AlGaAs/GaAs surface were proposed. - Abstract: The influence of annealing temperature, As{sub 4} beam equivalent pressure and multi-runs growth on AlGaAs/GaAs structures was investigated. The real space ultrahigh vacuum scanning tunneling microscopy images showed that AlGaAs/GaAs surface morphology greatly depends on annealing conditions and initial state of surface. The reasons of the surface phenomenon are proposed, and a physical model was proposed to explain why the multi-runs growth structures can increase AlGaAs surface roughness. The reasonable preparation conditions for AlGaAs/GaAs structures were proposed.

  3. VNIR Reflectance and MIR Emissivity Spectra of Ordinary Chondrite Meteorites Under Simulated Asteroid Surface Conditions

    Science.gov (United States)

    Gemma, M.; Shirley, K.; Glotch, T. D.; Ebel, D. S. S.

    2017-12-01

    Recent missions have revealed much about the nature of many Near-Earth asteroids, including the NEAR-Shoemaker target 433 Eros and Hayabusa target 25142 Itokawa. Both asteroids appear to have mineralogy consistent with ordinary chondrite meteorites. Laboratory spectral analysis of well-constrained meteorite samples can be employed as a reference tool to characterize and constrain data from current and future asteroid studies. A sample set of ordinary chondrite meteorites was chosen from the collection at the American Museum of Natural History. Six meteorites, spanning groups H, L, and LL, were prepared at four different size fractions (25-63 μm, 63-90 μm, 90-125 μm, 125-250 μm) in an attempt to mimic regolith known to exist on asteroids such as 433 Eros and 25142 Itokawa. At the Center for Planetary Exploration at Stony Brook University, spectra of the ordinary chondrite material were measured under simulated asteroid surface conditions ( 10-6 mbar, 150 K chamber temperature, low intensity illumination). The samples were used in two experiments: one measuring visible and near-infrared (VNIR) reflectance spectra at a series of temperatures, and the other measuring mid-infrared (MIR) emissivity spectra. The emissivity measurements require accurate simulation of the thermal environment within asteroid regolith, achieved by inducing a thermal gradient within the sample that results in a surface brightness temperature around 323 K (similar to the surface of 25142 Itokawa). Mid-IR emissivity spectra were collected for each sample at a surface temperature of 323 K, and reflectance spectra were collected in increments of 10 K, over the range 283 K to 373 K. Preliminary VNIR spectra show spreads similar to those seen in Hinrichs and Lucey (2002). Preliminary MIR emissivity spectra suggest that under asteroid surface conditions, the position of the Christiansen feature shifts to shorter wavelengths and emissivity is lower in the Reststrahlen bands when compared to

  4. Effect of Reaction Conditions on the Surface Modification of Cellulose Nanofibrils with Aminopropyl Triethoxysilane

    Directory of Open Access Journals (Sweden)

    Eduardo Robles

    2018-04-01

    Full Text Available Nine different surface modifications of cellulose nanofibrils (CNF with 3-aminopropyl triethoxysilane (ATS by using three different solvent systems (water, ethanol, and a mixture of both were investigated. The effect of reaction conditions, such as silane to cellulose ratio and solvent type were evaluated to determine their contribution to the extent of the silane modification. Nanofibril properties were evaluated by infrared spectroscopy, powder X-ray diffraction, surface free energy, thermogravimetry, 13C and 29Si nuclear magnetic resonance, and electronic microscopy. The influence of the solvent in the solvolysis of the silane was reflected in the presence or absence of ethoxy groups in the silane. On the other hand, whereas the surface modification was increased directly proportionally to silane ratio on the reaction, the aggregation of nanofibrils was also increased, which can play a negative role in certain applications. The increment of silane modification also had substantial repercussions on the crystallinity of the nanofibrils by the addition of amorphous components to the crystalline unit; moreover, silane surface modifications enhanced the hydrophobic character of the nanofibrils.

  5. Influence of Pre-Sintered Zirconia Surface Conditioning on Shear Bond Strength to Resin Cement

    Directory of Open Access Journals (Sweden)

    Tomofumi Sawada

    2016-06-01

    Full Text Available This study analyzed the shear bond strength (SBS of resin composite on zirconia surface to which a specific conditioner was applied before sintering. After sintering of either conditioner-coated or uncoated specimens, both groups were divided into three subgroups by their respective surface modifications (n = 10 per group: no further treatment; etched with hydrofluoric acid; and sandblasted with 50 µm Al2O3 particles. Surfaces were characterized by measuring different surface roughness parameters (e.g., Ra and Rmax and water contact angles. Half of the specimens underwent thermocycling (10,000 cycles, 5–55 °C after self-adhesive resin cement build-up. The SBSs were measured using a universal testing machine, and the failure modes were analyzed by microscopy. Data were analyzed by nonparametric and parametric tests followed by post-hoc comparisons (α = 0.05. Conditioner-coated specimens increased both surface roughness and hydrophilicity (p < 0.01. In the non-thermocycled condition, sandblasted surfaces showed higher SBSs than other modifications, irrespective of conditioner application (p < 0.05. Adhesive fractures were commonly observed in the specimens. Thermocycling favored debonding and decreased SBSs. However, conditioner-coated specimens upon sandblasting showed the highest SBS (p < 0.05 and mixed fractures were partially observed. The combination of conditioner application before sintering and sandblasting after sintering showed the highest shear bond strength and indicated improvements concerning the failure mode.

  6. Linking atmospheric synoptic transport, cloud phase, surface energy fluxes, and sea-ice growth: observations of midwinter SHEBA conditions

    Science.gov (United States)

    Persson, P. Ola G.; Shupe, Matthew D.; Perovich, Don; Solomon, Amy

    2017-08-01

    Observations from the Surface Heat Budget of the Arctic Ocean (SHEBA) project are used to describe a sequence of events linking midwinter long-range advection of atmospheric heat and moisture into the Arctic Basin, formation of supercooled liquid water clouds, enhancement of net surface energy fluxes through increased downwelling longwave radiation, and reduction in near-surface conductive heat flux loss due to a warming of the surface, thereby leading to a reduction in sea-ice bottom growth. The analyses provide details of two events during Jan. 1-12, 1998, one entering the Arctic through Fram Strait and the other from northeast Siberia; winter statistics extend the results. Both deep, precipitating frontal clouds and post-frontal stratocumulus clouds impact the surface radiation and energy budget. Cloud liquid water, occurring preferentially in stratocumulus clouds extending into the base of the inversion, provides the strongest impact on surface radiation and hence modulates the surface forcing, as found previously. The observations suggest a minimum water vapor threshold, likely case dependent, for producing liquid water clouds. Through responses to the radiative forcing and surface warming, this cloud liquid water also modulates the turbulent and conductive heat fluxes, and produces a thermal wave penetrating into the sea ice. About 20-33 % of the observed variations of bottom ice growth can be directly linked to variations in surface conductive heat flux, with retarded ice growth occurring several days after these moisture plumes reduce the surface conductive heat flux. This sequence of events modulate pack-ice wintertime environmental conditions and total ice growth, and has implications for the annual sea-ice evolution, especially for the current conditions of extensive thinner ice.

  7. Assessment of a surface-layer parameterization scheme in an atmospheric model for varying meteorological conditions

    Directory of Open Access Journals (Sweden)

    T. J. Anurose

    2014-06-01

    Full Text Available The performance of a surface-layer parameterization scheme in a high-resolution regional model (HRM is carried out by comparing the model-simulated sensible heat flux (H with the concurrent in situ measurements recorded at Thiruvananthapuram (8.5° N, 76.9° E, a coastal station in India. With a view to examining the role of atmospheric stability in conjunction with the roughness lengths in the determination of heat exchange coefficient (CH and H for varying meteorological conditions, the model simulations are repeated by assigning different values to the ratio of momentum and thermal roughness lengths (i.e. z0m/z0h in three distinct configurations of the surface-layer scheme designed for the present study. These three configurations resulted in differential behaviour for the varying meteorological conditions, which is attributed to the sensitivity of CH to the bulk Richardson number (RiB under extremely unstable, near-neutral and stable stratification of the atmosphere.

  8. Evaluation of the conditions imposed by the fracture surface geometry on water seepage through fractured porous media

    International Nuclear Information System (INIS)

    Fuentes, Nestor O.; Faybishenko, B.

    2003-01-01

    In order to determine the geometric patterns of the fracture surfaces that imposes conditions on the fluid flow through fractured porous media, a series a fracture models have been analyzed using the RIMAPS technique and the variogram method. Results confirm that the main paths followed by the fluid channels are determined by the surface topography and remain constant during water seepage evolution. Characteristics scale lengths of both situations: fracture surface and the flow of water, are also found. There exists a relationship between the scale lengths corresponding to each situation. (author)

  9. Effect of two-step and one-step surface conditioning of glass ceramic on adhesion strength of orthodontic bracket and effect of thermo-cycling on adhesion strength.

    Science.gov (United States)

    Asiry, Moshabab A; AlShahrani, Ibrahim; Alaqeel, Samer M; Durgesh, Bangalore H; Ramakrishnaiah, Ravikumar

    2018-08-01

    The adhesion strength of orthodontic brackets bonded to dental glass ceramics was evaluated after ceramic surface was treated with two-step and one-step surface conditioning systems, and subjecting to thermo-cycling. A total of forty specimens were fabricated from silica based glass ceramic (lithium disilicate) by duplicating the buccal surface of maxillary first premolar. The specimens were randomly assigned to two experimental groups (n = 20), group one specimens were treated with two-step surface conditioning system (IPS ceramic etching gel™ and Monobond plus™) and group two specimens were treated with one-step surface conditioning system (Monobond etch and prime™). The surface roughness of the specimens after treatment with two-step and one-step surface conditioning system was measured using non-contact surface profilometer. Ten randomly selected specimens from each group were subjected to thermo-cycling and the remaining ten served as baseline. The shear bond strength of the specimens was measured using universal material testing machine. The adhesive remnant index score was calculated, and the results of surface roughness and bond strength were tabulated and subjected to analysis of variance and post hoc tukey's test at a significance level of p step conditioning system had higher surface roughness and bond strength than one-step conditioning system. The majority of the specimens treated with both two-step and one-step conditioned specimens showed adhesive failure after subjecting thermo-cycling. Traditional two-step conditioning provides better bond strength. The clinical importance of the study is that, the silane promoted adhesion significantly reduces on exposure to thermo-cycling. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Stability conditions of stationary rupture of liquid layers on an immiscible fluid surface

    Energy Technology Data Exchange (ETDEWEB)

    Viviani, A. [Seconda Univ. di Napoli, Aversa (Italy). Facolta di Ingegneria; Kostarev, K.; Shmyrov, A.; Zuev, A. [Inst. of Continuous Media Mechanics, Perm (Russian Federation)

    2009-07-01

    The stationary equilibrium shape of a 3-phase liquids-gas system was investigated. The system consisted of a horizontal liquid layer with an upper free boundary placed on the immiscible fluid interface. The study investigated the stability conditions of rupture of the liquid layer surface. The dependence of rupture parameters on the experimental cuvette diameter and layer thickness was investigated, as well as the difference in the values of surface tension of the examined fluids. The 2-layer system of horizontal fluid layers was formed in a glass cylindrical cuvette. The liquid substrate was tetrachloride carbon (CCI{sub 4}), while upper layers included water, glycerine, ethyleneglycol, and aqueous solutions of 1,4-butanediol C{sub 4}H{sub 10}O{sub 2} and isopropanol C{sub 3H8L}. Initially, the surface of the substrate fluid was overlaid with a horizontal liquid layer. The rupture was formed by subjecting the layer surface to short-time actions of a narrow directional air jet. After rupture formation, the layer thickness increased gradually. The measurements demonstrated that the rupture diameter depends on the initial thickness of the upper layer as well as the diameter of the cuvette, and the difference in the values of the surface tension of the examined fluids. Analysis of the experimental relationships indicated that the critical thickness of the breaking layer is a constant value for any specific pairs of fluids. 4 refs., 7 figs.

  11. An energy-based equilibrium contact angle boundary condition on jagged surfaces for phase-field methods.

    Science.gov (United States)

    Frank, Florian; Liu, Chen; Scanziani, Alessio; Alpak, Faruk O; Riviere, Beatrice

    2018-08-01

    We consider an energy-based boundary condition to impose an equilibrium wetting angle for the Cahn-Hilliard-Navier-Stokes phase-field model on voxel-set-type computational domains. These domains typically stem from μCT (micro computed tomography) imaging of porous rock and approximate a (on μm scale) smooth domain with a certain resolution. Planar surfaces that are perpendicular to the main axes are naturally approximated by a layer of voxels. However, planar surfaces in any other directions and curved surfaces yield a jagged/topologically rough surface approximation by voxels. For the standard Cahn-Hilliard formulation, where the contact angle between the diffuse interface and the domain boundary (fluid-solid interface/wall) is 90°, jagged surfaces have no impact on the contact angle. However, a prescribed contact angle smaller or larger than 90° on jagged voxel surfaces is amplified. As a remedy, we propose the introduction of surface energy correction factors for each fluid-solid voxel face that counterbalance the difference of the voxel-set surface area with the underlying smooth one. The discretization of the model equations is performed with the discontinuous Galerkin method. However, the presented semi-analytical approach of correcting the surface energy is equally applicable to other direct numerical methods such as finite elements, finite volumes, or finite differences, since the correction factors appear in the strong formulation of the model. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Recombination of chlorine atoms on plasma-conditioned stainless steel surfaces in the presence of adsorbed Cl{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Stafford, Luc; Poirier, Jean-Sebastien; Margot, Joelle [Departement de Physique, Universite de Montreal, Montreal, Quebec, H3C 3J7 (Canada); Khare, Rohit; Guha, Joydeep; Donnelly, Vincent M, E-mail: luc.stafford@umontreal.c, E-mail: vmdonnelly@uh.ed [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204 (United States)

    2009-03-07

    We investigated the interactions of atomic and molecular chlorine with plasma-conditioned stainless steel surfaces through both experiments and modelling. The recombination of Cl during adsorption and desorption of Cl{sub 2} was characterized using a rotating-substrate technique in which portions of the cylindrical substrate surface are periodically exposed to an inductively coupled chlorine plasma and then to an Auger electron spectrometer in separate, differentially pumped chambers. After several hours of exposure to the Cl{sub 2} plasma, the stainless steel substrate became coated with a Si-oxychloride-based layer (Fe : Si : O : Cl {approx} 1 : 13 : 13 : 3) due to chlorine adsorption and the erosion of the silica discharge tube. Desorption of Cl{sub 2} from this surface was monitored through measurements of pressure rises in the Auger chamber as a function of substrate rotation frequency. Significant adsorption and desorption of Cl{sub 2} was observed with the plasma off, similar to that observed previously on plasma-conditioned anodized aluminium surfaces, but with much faster desorption rates that are most likely attributable to the smoother and non-porous stainless steel surface morphology. When the plasma was turned on, a much larger pressure rise was observed due to Langmuir-Hinshelwood recombination of Cl atoms. Recombination coefficients, {gamma}{sub Cl}, ranged from 0.004 to 0.03 and increased with Cl-to-Cl{sub 2} number density ratio. This behaviour was observed previously for anodized aluminium surfaces, and was explained by the blocking of Cl recombination sites by adsorbed Cl{sub 2}. Application of this variable recombination coefficient to the modelling of high-density chlorine plasmas gives a much better agreement with measured Cl{sub 2} percent dissociations compared with predictions obtained with a recombination coefficient that is independent of plasma conditions.

  13. Identification of a Catalytically Highly Active Surface Phase for CO Oxidation over PtRh Nanoparticles under Operando Reaction Conditions

    Science.gov (United States)

    Hejral, U.; Franz, D.; Volkov, S.; Francoual, S.; Strempfer, J.; Stierle, A.

    2018-03-01

    Pt-Rh alloy nanoparticles on oxide supports are widely employed in heterogeneous catalysis with applications ranging from automotive exhaust control to energy conversion. To improve catalyst performance, an atomic-scale correlation of the nanoparticle surface structure with its catalytic activity under industrially relevant operando conditions is essential. Here, we present x-ray diffraction data sensitive to the nanoparticle surface structure combined with in situ mass spectrometry during near ambient pressure CO oxidation. We identify the formation of ultrathin surface oxides by detecting x-ray diffraction signals from particular nanoparticle facets and correlate their evolution with the sample's enhanced catalytic activity. Our approach opens the door for an in-depth characterization of well-defined, oxide-supported nanoparticle based catalysts under operando conditions with unprecedented atomic-scale resolution.

  14. Influence of Surface Conditioning Protocols on Reparability of CAD/CAM Zirconia-reinforced Lithium Silicate Ceramic.

    Science.gov (United States)

    Al-Thagafi, Rana; Al-Zordk, Walid; Saker, Samah

    2016-01-01

    To test the effect of surface conditioning protocols on the reparability of CAD/CAM zirconia-reinforced lithium silicate ceramic compared to lithium-disilicate glass ceramic. Zirconia-reinforced lithium silicate ceramic (Vita Suprinity) and lithium disilicate glass-ceramic blocks (IPS e.max CAD) were categorized into four groups based on the surface conditioning protocol used. Group C: no treatment (control); group HF: 5% hydrofluoric acid etching for 60 s, silane (Monobond-S) application for 60 s, air drying; group HF-H: 5% HF acid etching for 60 s, application of silane for 60 s, air drying, application of Heliobond, light curing for 20 s; group CO: sandblasting with CoJet sand followed by silanization. Composite resin (Tetric EvoCeram) was built up into 4 x 6 x 3 mm blocks using teflon molds. All specimens were subjected to thermocycling (5000x, 5°C to 55°C). The microtensile bond strength test was employed at a crosshead speed of 1 mm/min. SEM was employed for evaluation of all the debonded microbars, the failure type was categorized as either adhesive (failure at adhesive layer), cohesive (failure at ceramic or composite resin), or mixed (failure between adhesive layer and substrate). Two-way ANOVA and the Tukey's HSD post-hoc test were applied to test for significant differences in bond strength values in relation to different materials and surface pretreatment (p ceramic types used (p ceramics and lithium-disilicate glass ceramic could be improved when ceramic surfaces are sandblasted with CoJet sand followed by silanization.

  15. Late Quaternary Palaeoceanographic Changes in Sea Surface Conditions in the Tropical Atlantic

    Science.gov (United States)

    Fischel, Andrea; Seidenkrantz, Marit-Solveig; Kuijpers, Antoon; Nürnberg, Dirk

    2013-04-01

    Palaeoceanographic changes and the variability in surface water mass hydrography are reconstructed in order to track tropical ocean and climate variability and inter-hemispheric heat exchange through the last 42,000 year BP. Our studies are based on the relative abundance of planktonic foraminifera combined with sea surface temperature approximation based Mg/Ca measurements, XRF scanning and stable oxygen isotope analyses in a 5 m long gravity core Ga307-Win-12GC (17°50.80N, 64°48.7290W), retrieved in the Virgin Island Basin in approx. 3,960 m water depth. The Virgin Island Basin is the deepest part of the Anegada-Jungfern Passage in the northeast Caribbean, one of the most important pathways for water mass exchange between the Central Atlantic and the Caribbean Sea. Due to its bathymetry surface waters as well as deep water mass strata from the northern and southern hemisphere enter the basin, comprising Caribbean Surface Water (CSW), Antarctic Intermediate Water (AAIW), Atlantic Intermediate Water (AIW) and North Atlantic Deep Water (NADW). The planktonic foraminiferal assemblage suggests rather stable sea-surface conditions during the Holocene in the NE Caribbean. However, major changes in the hydrographic setting could be identified within the glacial period. During the glacial period, clear millennial-scale variability in sea-surface temperature and productivity are present. Fluctuations in the relative abundance of Globigerinoides ruber in the sediment core may be correlated to Dansgaard-Oeschger events in the northern North Atlantic. Furthermore an increase in relative abundance of Globorotalia rubescens occurs synchronous with ice rafted debris layers described from the North Atlantic. The faunal changes in the tropical Atlantic may thus be correlated to major climate changes in the North Atlantic, mainly D-O cyclicity as well as Heinrich events. Thus, the synchronous change in water mass distribution and hydrographic cyclicity suggests a possible linkage

  16. Bond strengths of brackets bonded to enamel surfaces conditioned with femtosecond and Er:YAG laser systems.

    Science.gov (United States)

    Aglarci, Cahide; Demir, Necla; Aksakalli, Sertac; Dilber, Erhan; Sozer, Ozlem Akinci; Kilic, Hamdi Sukur

    2016-08-01

    The aim of this study was to compare femtosecond and Er:YAG laser systems with regard to enamel demineralization and bracket bond strength. Human-extracted premolars were randomized to three groups (n = 17) depending on the conditioning treatment used for the buccal surfaces: 37 % orthophosphoric acid, Er:YAG laser etching (MSP mode 120 mJ, 10 Hz, 1.2 W), and femtosecond laser etching (0.4 W, 800 nm, 90 fs/pulse, 1 kHz). Metal brackets were bonded with Transbond XT to the conditioned surfaces and light cured for 20 s. The samples were thermocycled (5000 cycles, 5-55 °C) and subjected to shear bond strength (SBS) testing using a universal testing machine. Failure types were analyzed under an optical stereomicroscope and SEM. The adhesive remnant index (ARI) was evaluated to assess residual adhesive on the enamel surface. The results revealed no significant differences in SBS between the Er:YAG laser (7.2 ± 3.3 MPa) and acid etching groups (7.3 ± 2.7 MPa; p enamel interface.

  17. High-flux He+ irradiation effects on surface damages of tungsten under ITER relevant conditions

    International Nuclear Information System (INIS)

    Liu, Lu; Liu, Dongping; Hong, Yi; Fan, Hongyu; Ni, Weiyuan; Yang, Qi; Bi, Zhenhua; Benstetter, Günther; Li, Shouzhe

    2016-01-01

    A large-power inductively coupled plasma source was designed to perform the continuous helium ions (He + ) irradiations of polycrystalline tungsten (W) under International Thermonuclear Experimental Reactor (ITER) relevant conditions. He + irradiations were performed at He + fluxes of 2.3 × 10 21 –1.6 × 10 22 /m 2  s and He + energies of 12–220 eV. Surface damages and microstructures of irradiated W were observed by scanning electron microscopy. This study showed the growth of nano-fuzzes with their lengths of 1.3–2.0 μm at He + energies of >70 eV or He + fluxes of >1.3 × 10 22 /m 2  s. Nanometer-sized defects or columnar microstructures were formed in W surface layer due to low-energy He + irradiations at an elevated temperature (>1300 K). The diffusion and coalescence of He atoms in W surface layers led to the growth and structures of nano-fuzzes. This study indicated that a reduction of He + energy below 12–30 eV may greatly decrease the surface damage of tungsten diverter in the fusion reactor.

  18. Physico-chemical changes of ZnO nanoparticles with different size and surface chemistry under physiological pH conditions.

    Science.gov (United States)

    Gwak, Gyeong-Hyeon; Lee, Won-Jae; Paek, Seung-Min; Oh, Jae-Min

    2015-03-01

    We studied the physico-chemical properties of ZnO nanoparticles under physiological pH conditions (gastric, intestinal and plasma) as functions of their size (20 and 70 nm) and surface chemistry (pristine, L-serine, or citrate coating). ZnO nanoparticles were dispersed in phosphate buffered saline under physiological pH conditions and aliquots were collected at specific time points (0.5, 1, 4, 10 and 24 h) for further characterization. The pH values of the aqueous ZnO colloids at each condition were in the neutral to slightly basic range and showed different patterns depending on the original size and surface chemistry of the ZnO nanoparticles. The gastric pH condition was found to significantly dissolve ZnO nanoparticles up to 18-30 wt%, while the intestinal or plasma pH conditions resulted in much lower dissolution amounts than expected. Based on the X-ray diffraction patterns and X-ray absorption spectra, we identified partial phase transition of the ZnO nanoparticles from wurtzite to Zn(OH)2 under the intestinal and plasma pH conditions. Using scanning electron microscopy, we verified that the overall particle size and morphology of all ZnO nanoparticles were maintained regardless of the pH. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. The Potential of Using Landsat 7 Data for the Classification of Sea Ice Surface Conditions During Summer

    Science.gov (United States)

    Markus, Thorsten; Cavalieri, Donald J.; Ivanoff, Alvaro; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    During spring and summer, the Surface of the Arctic sea ice cover undergoes rapid changes that greatly affect the surface albedo and significantly impact the further decay of the sea ice. These changes are primarily the development of a wet snow cover and the development of melt ponds. As melt pond diameters generally do not exceed a couple of meters, the spatial resolutions of sensors like AVHRR and MODIS are too coarse for their identification. Landsat 7, on the other hand, has a spatial resolution of 30 m (15 m for the pan-chromatic band). The different wavelengths (bands) from blue to near-infrared offer the potential to distinguish among different surface conditions. Landsat 7 data for the Baffin Bay region for June 2000 have been analyzed. The analysis shows that different surface conditions, such as wet snow and meltponded areas, have different signatures in the individual Landsat bands. Consistent with in-situ albedo measurements, melt ponds show up as blueish whereas dry and wet ice have a white to gray appearance in the Landsat true-color image. These spectral differences enable the distinction of melt ponds. The melt pond fraction for the scene studied in this paper was 37%.

  20. The boundary condition for vertical velocity and its interdependence with surface gas exchange

    Science.gov (United States)

    Kowalski, Andrew S.

    2017-07-01

    The law of conservation of linear momentum is applied to surface gas exchanges, employing scale analysis to diagnose the vertical velocity (w) in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E) and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = E/ρ. This is true even right down at the surface where the boundary condition is w|0 = E/ρ|0 (where w|0 and ρ|0 represent the vertical velocity and density of air at the surface). This Stefan flow velocity implies upward transport of a non-diffusive nature that is a general feature of the troposphere but is of particular importance at the surface, where it assists molecular diffusion with upward gas migration (of H2O, for example) but opposes that of downward-diffusing species like CO2 during daytime. The definition of flux-gradient relationships (eddy diffusivities) requires rectification to exclude non-diffusive transport, which does not depend on scalar gradients. At the microscopic scale, the role of non-diffusive transport in the process of evaporation from inside a narrow tube - with vapour transport into an overlying, horizontal airstream - was described long ago in classical mechanics and is routinely accounted for by chemical engineers, but has been neglected by scientists studying stomatal conductance. Correctly accounting for non-diffusive transport through stomata, which can appreciably reduce net CO2 transport and marginally boost that of water vapour, should improve characterisations of ecosystem and plant functioning.

  1. HF Surface Wave Radar Operation in Adverse Conditions

    National Research Council Canada - National Science Library

    Ponsford, Anthony M; Dizaji, Reza M; McKerracher, Richard

    2005-01-01

    ...) system based on HF Surface Wave Radar (HFSWR). the primary objective behind the programme was to demonstrate the capability of HFSWR to continuously detect and track surface targets (ships and icebergs...

  2. Experimental and numerical study on inlet and outlet conditions of a bulb turbine with considering free surface

    International Nuclear Information System (INIS)

    Zhao, Y P; Liao, W L; Feng, H D; Ruan, H; Luo, X Q

    2012-01-01

    For a bulb turbine, it has a low head and a big runner diameter, and the free surface influences the flow at the inlet and outlet of the turbine, which bring many problems such as vibration, cracks and cavitation to the turbine. Therefore, it is difficult to get the precise internal flow characteristics through a numerical simulation with conventional ideal flow conditions. In this paper, both numerical and experimental methods are adopted to investigate the flow characteristics at the inlet and outlet of the bulb turbine with considering free surface. Firstly, experimental and numerical studies in a low head pressure pipeline are conducted, and the corresponding boundary condition according with reality is obtained through the comparison between the model test result and the CFD simulation result. Then, through an analysis of the velocity and pressure fields at the inlet of the bulb turbine at different heads, the flow characteristics and rules at the entrance of the bulb turbine have been revealed with considering free surface; Finally, the performance predictions for a bulb turbine have been conducted by using the obtained flow rules at the inlet as the boundary condition of a turbine, and the causes that lead to non-uniform forces on blades, cavitation and vibration have been illustrated in this paper, which also provide a theory basis for an accurate numerical simulation and optimization design of a bulb turbine.

  3. Photoelectron spectroscopy of surfaces under humid conditions

    International Nuclear Information System (INIS)

    Bluhm, Hendrik

    2010-01-01

    The interaction of water with surfaces plays a major role in many processes in the environment, atmosphere and technology. Weathering of rocks, adhesion between surfaces, and ionic conductance along surfaces are among many phenomena that are governed by the adsorption of molecularly thin water layers under ambient humidities. The properties of these thin water films, in particular their thickness, structure and hydrogen-bonding to the substrate as well as within the water film are up to now not very well understood. Ambient pressure photoelectron spectroscopy (APXPS) is a promising technique for the investigation of the properties of thin water films. In this article we will discuss the basics of APXPS as well as the particular challenges that are posed by investigations in water vapor at Torr pressures. We will also show examples of the application of APXPS to the study of water films on metals and oxides.

  4. Application-Ready Expedited MODIS Data for Operational Land Surface Monitoring of Vegetation Condition

    Directory of Open Access Journals (Sweden)

    Jesslyn F. Brown

    2015-12-01

    Full Text Available Monitoring systems benefit from high temporal frequency image data collected from the Moderate Resolution Imaging Spectroradiometer (MODIS system. Because of near-daily global coverage, MODIS data are beneficial to applications that require timely information about vegetation condition related to drought, flooding, or fire danger. Rapid satellite data streams in operational applications have clear benefits for monitoring vegetation, especially when information can be delivered as fast as changing surface conditions. An “expedited” processing system called “eMODIS” operated by the U.S. Geological Survey provides rapid MODIS surface reflectance data to operational applications in less than 24 h offering tailored, consistently-processed information products that complement standard MODIS products. We assessed eMODIS quality and consistency by comparing to standard MODIS data. Only land data with known high quality were analyzed in a central U.S. study area. When compared to standard MODIS (MOD/MYD09Q1, the eMODIS Normalized Difference Vegetation Index (NDVI maintained a strong, significant relationship to standard MODIS NDVI, whether from morning (Terra or afternoon (Aqua orbits. The Aqua eMODIS data were more prone to noise than the Terra data, likely due to differences in the internal cloud mask used in MOD/MYD09Q1 or compositing rules. Post-processing temporal smoothing decreased noise in eMODIS data.

  5. Reconstructing Sea Surface Conditions in the Bay of Bengal during the Mid-Pleistocene Transition

    Science.gov (United States)

    Lagos, A. D.; Dekens, P.; Reilly, B. T.; Selkin, P. A.; Meynadier, L.; Savian, J. F.

    2017-12-01

    During the Mid-Pleistocene Transition (MPT, 0.8-1.2Ma) Earth's glacial cycles transitioned from responding primarily to 41kyr obliquity cycles to responding to 100kyr eccentricity cycles. In the tropics, sea surface temperature (SST) in the eastern tropical Pacific cooled through the MPT, suggesting a strengthening of the equatorial Pacific zonal temperature gradient (Medina-Elizalde & Lea, 2005). The strong SST gradient would have intensified Walker Cell convection during the MPT and built up latent heat in the western Pacific, which could cause cold SST anomalies in the northern Indian Ocean (Liu et al., 2015). Due to a scarcity of records, it is unclear how climate and oceanic conditions evolved in the Indian Ocean during the MPT. A set of recent IODP expeditions, including 353 and 354, cored sediment from the Bay of Bengal. Several sites recovered by expedition 353 will be ideal for reconstructing monsoon intensity through time, while the expedition 354 cores from a longitudinal transect at 8°N are in a region not directly impacted by changes in freshwater input due to direct precipitation or run off. The sites are influenced by the northeastern migration of equatorial Indian Ocean water via the Southwest Monsoon Current, which supplies significant moisture to the monsoon. Expedition 354's southern Bay of Bengal sites are well situated for better understanding the link between the tropical Indian Ocean and the northern Bay of Bengal. We reconstructed sea surface conditions at IODP site 1452 (8°N, 87°E, 3670m water depth) in the distal Bengal Fan. A 3 meter long section of the core has been identified as the MPT using the Bruhnes/Matuyama, Jaramillo, and Cobb Mountain paleomagnetic reversals (France-Lanord et al., 2016). This section of site 1452 was sampled every 2cm ( 2kyr resolution). Approximately 30 G. sacculifer, a surface dwelling planktonic foraminifera, were picked from the 355-425μm size fraction. We measured Mg/Ca and δ18O on splits of the same

  6. Tissue responses to fractional transient heating with sinusoidal heat flux condition on skin surface.

    Science.gov (United States)

    Ezzat, Magdy A; El-Bary, Alaa A; Al-Sowayan, Noorah S

    2016-10-01

    A fractional model of Bioheat equation for describing quantitatively the thermal responses of skin tissue under sinusoidal heat flux conditions on skin surface is given. Laplace transform technique is used to obtain the solution in a closed form. The resulting formulation is applied to one-dimensional application to investigate the temperature distribution in skin with instantaneous surface heating for different cases. According to the numerical results and its graphs, conclusion about the fractional bioheat transfer equation has been constructed. Sensitivity analysis is performed to explore the thermal effects of various control parameters on tissue temperature. The comparisons are made with the results obtained in the case of the absence of time-fractional order. © 2016 Japanese Society of Animal Science. © 2016 Japanese Society of Animal Science.

  7. Electron Conditioning of Technical Aluminium Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Le Pimpec, F

    2004-09-02

    The effect of electron conditioning on commercially aluminium alloys 1100 and 6063 were investigated. Contrary to the assumption that electron conditioning, if performed long enough, can reduce and stabilize the SEY to low values (= 1.3, value of many pure elements [1]), the SEY of aluminium did not go lower than 1.8. In fact, it reincreases with continued electron exposure dose.

  8. Flat friction tests applied to austenic stainless steels with several surface finish. Analysis of adhesion conditions in friction

    International Nuclear Information System (INIS)

    Coello, J.; Miguel, V.; Ferrer, C.; Calatatyd, A.; Martinez, A.

    2008-01-01

    The main purpose of this work is to evaluate the tribological behaviour of austenic stainless steels AISI 304 with bright surface finishing (B). The assays have been carried out in flat faced dies system with mineral oil of 200 cts viscosity, S 2 Mo grease and in dry conditions. The relationship between friction coefficient and pressure and velocity has been established for the mineral oil as lubricant. In these conditions, a strong adhesive tendency has been found in boundary lubrication regime. The results obtained here, show us that S 2 Mo grease leads to lowest values for the friction coefficient. A minor adhesive behaviour tendency for AISI 316 steel, harder than 304 grades, has been found. A relevant plowing phenomena has been observed for the more critical friction conditions tried out. A surface hardener is produced as a consequence of that. (Author) 19 refs

  9. Free surface flows under compensated gravity conditions

    CERN Document Server

    Dreyer, Miachel E

    2007-01-01

    This book considers the behavior of fluids in a low-gravity environment with special emphasis on application in PMD (propellant management device) systems . In the compensated gravity environment of a spacecraft, the hydrostatic pressure decreases to very low values depending on the residual acceleration, and surface tension forces become dominant. Consequently, surface tension can be used to transport and position liquids if the residual acceleration and the resulting hydrostatic pressure are small compared to the capillary pressure. One prominent application is the use of PMDs in surface-tension satellite tanks. PMDs must ensure that the tank outlet is covered with liquid whenever outflow is demanded. Furthermore, PMDs are used to ensure expulsion and refilling of tanks for liquids and gases for life support, reactants, and experiment supplies. Since most of the PMD designs are not testable on ground and thus rely on analytical or numerical concepts, this book treats three different flow problems with analy...

  10. Standard test method for damage to contacting solid surfaces under fretting conditions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the studying or ranking the susceptibility of candidate materials to fretting corrosion or fretting wear for the purposes of material selection for applications where fretting corrosion or fretting wear can limit serviceability. 1.2 This test method uses a tribological bench test apparatus with a mechanism or device that will produce the necessary relative motion between a contacting hemispherical rider and a flat counterface. The rider is pressed against the flat counterface with a loading mass. The test method is intended for use in room temperature air, but future editions could include fretting in the presence of lubricants or other environments. 1.3 The purpose of this test method is to rub two solid surfaces together under controlled fretting conditions and to quantify the damage to both surfaces in units of volume loss for the test method. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5...

  11. Effects of surface finishing conditions on the biocompatibility of a nickel-chromium dental casting alloy.

    LENUS (Irish Health Repository)

    McGinley, Emma Louise

    2011-07-01

    To assess the effects of surface finishing condition (polished or alumina particle air abraded) on the biocompatibility of direct and indirect exposure to a nickel-chromium (Ni-Cr) d.Sign®10 dental casting alloy on oral keratinocytes. Biocompatibility was performed by assessing cellular viability and morphology, metabolic activity, cellular toxicity and presence of inflammatory cytokine markers.

  12. The Influence of As-Built Surface Conditions on Mechanical Properties of Ti-6Al-4V Additively Manufactured by Selective Electron Beam Melting

    Science.gov (United States)

    Sun, Y. Y.; Gulizia, S.; Oh, C. H.; Fraser, D.; Leary, M.; Yang, Y. F.; Qian, M.

    2016-03-01

    Achieving a high surface finish is a major challenge for most current metal additive manufacturing processes. We report the first quantitative study of the influence of as-built surface conditions on the tensile properties of Ti-6Al-4V produced by selective electron beam melting (SEBM) in order to better understand the SEBM process. Tensile ductility was doubled along with noticeable improvements in tensile strengths after surface modification of the SEBM-fabricated Ti-6Al-4V by chemical etching. The fracture surfaces of tensile specimens with different surface conditions were characterised and correlated with the tensile properties obtained. The removal of a 650- μm-thick surface layer by chemical etching was shown to be necessary to eliminate the detrimental influence of surface defects on mechanical properties. The experimental results and analyses underline the necessity to modify the surfaces of SEBM-fabricated components for structural applications, particularly for those components which contain complex internal concave and convex surfaces and channels.

  13. The boundary condition for vertical velocity and its interdependence with surface gas exchange

    Directory of Open Access Journals (Sweden)

    A. S. Kowalski

    2017-07-01

    Full Text Available The law of conservation of linear momentum is applied to surface gas exchanges, employing scale analysis to diagnose the vertical velocity (w in the boundary layer. Net upward momentum in the surface layer is forced by evaporation (E and defines non-zero vertical motion, with a magnitude defined by the ratio of E to the air density, as w = E/ρ. This is true even right down at the surface where the boundary condition is w|0 = E/ρ|0 (where w|0 and ρ|0 represent the vertical velocity and density of air at the surface. This Stefan flow velocity implies upward transport of a non-diffusive nature that is a general feature of the troposphere but is of particular importance at the surface, where it assists molecular diffusion with upward gas migration (of H2O, for example but opposes that of downward-diffusing species like CO2 during daytime. The definition of flux–gradient relationships (eddy diffusivities requires rectification to exclude non-diffusive transport, which does not depend on scalar gradients. At the microscopic scale, the role of non-diffusive transport in the process of evaporation from inside a narrow tube – with vapour transport into an overlying, horizontal airstream – was described long ago in classical mechanics and is routinely accounted for by chemical engineers, but has been neglected by scientists studying stomatal conductance. Correctly accounting for non-diffusive transport through stomata, which can appreciably reduce net CO2 transport and marginally boost that of water vapour, should improve characterisations of ecosystem and plant functioning.

  14. Nocturnal surface ozone enhancement over Portugal during winter: Influence of different atmospheric conditions

    KAUST Repository

    Kulkarni, Pavan S.

    2016-09-24

    Four distinct nocturnal surface ozone (NSO) enhancement events were observed, with NSO concentration exceeding 80μg/m3, at multiple ozone (O3) monitoring stations (32 sites) in January, November and December between year 2000–2010, in Portugal. The reasonable explanation for the observed bimodal pattern of surface ozone with enhanced NSO concentration during nighttime has to be transport processes, as the surface ozone production ceases at nighttime. Simultaneous measurements of O3 at multiple stations during the study period in Portugal suggest that horizontal advection alone cannot explain the observed NSO enhancement. Thus, detailed analysis of the atmospheric conditions, simulated with the Weather Research and Forecasting (WRF) model, were performed to evaluate the atmospheric mechanisms responsible for NSO enhancement in the region. Simulations revealed that each event occurred as a result of one or the combination of different atmospheric processes such as, passage of a cold front followed by a subsidence zone; passage of a moving surface trough, with associated strong horizontal wind speed and vertical shear; combination of vertical and horizontal transport at the synoptic scale; formation of a low level jet with associated vertical mixing below the jet stream. The study confirmed that large-scale flow pattern resulting in enhanced vertical mixing in the nocturnal boundary layer, plays a key role in the NSO enhancement events, which frequently occur over Portugal during winter months. © 2016 Elsevier Ltd

  15. Nocturnal surface ozone enhancement over Portugal during winter: Influence of different atmospheric conditions

    KAUST Repository

    Kulkarni, Pavan S.; Dasari, Hari Prasad; Sharma, Ashish; Bortoli, D.; Salgado, Rui; Silva, A.M.

    2016-01-01

    Four distinct nocturnal surface ozone (NSO) enhancement events were observed, with NSO concentration exceeding 80μg/m3, at multiple ozone (O3) monitoring stations (32 sites) in January, November and December between year 2000–2010, in Portugal. The reasonable explanation for the observed bimodal pattern of surface ozone with enhanced NSO concentration during nighttime has to be transport processes, as the surface ozone production ceases at nighttime. Simultaneous measurements of O3 at multiple stations during the study period in Portugal suggest that horizontal advection alone cannot explain the observed NSO enhancement. Thus, detailed analysis of the atmospheric conditions, simulated with the Weather Research and Forecasting (WRF) model, were performed to evaluate the atmospheric mechanisms responsible for NSO enhancement in the region. Simulations revealed that each event occurred as a result of one or the combination of different atmospheric processes such as, passage of a cold front followed by a subsidence zone; passage of a moving surface trough, with associated strong horizontal wind speed and vertical shear; combination of vertical and horizontal transport at the synoptic scale; formation of a low level jet with associated vertical mixing below the jet stream. The study confirmed that large-scale flow pattern resulting in enhanced vertical mixing in the nocturnal boundary layer, plays a key role in the NSO enhancement events, which frequently occur over Portugal during winter months. © 2016 Elsevier Ltd

  16. Relation between the Atmospheric Boundary Layer and Impact Factors under Severe Surface Thermal Conditions

    Directory of Open Access Journals (Sweden)

    Yinhuan Ao

    2017-01-01

    Full Text Available This paper reported a comprehensive analysis on the diurnal variation of the Atmospheric Boundary Layer (ABL in summer of Badain Jaran Desert and discussed deeply the effect of surface thermal to ABL, including the Difference in Surface-Air Temperature (DSAT, net radiation, and sensible heat, based on limited GPS radiosonde and surface observation data during two intense observation periods of experiments. The results showed that (1 affected by topography of the Tibetan Plateau, the climate provided favorable external conditions for the development of Convective Boundary Layer (CBL, (2 deep CBL showed a diurnal variation of three- to five-layer structure in clear days and five-layer ABL structure often occurred about sunset or sunrise, (3 the diurnal variation of DSAT influenced thickness of ABL through changes of turbulent heat flux, (4 integral value of sensible heat which rapidly converted by surface net radiation had a significant influence on the growth of CBL throughout daytime. The cumulative effect of thick RML dominated the role after CBL got through SBL in the development stage, especially in late summer, and (5 the development of CBL was promoted and accelerated by the variation of wind field and distribution of warm advection in high and low altitude.

  17. The internal structure and dynamics of the railgun plasma armature between infinitely wide ablating rails

    International Nuclear Information System (INIS)

    Frese, M.F.

    1991-01-01

    This paper reports on computer simulations of the plasma flow in two-dimensionally symmetric railgun plasma arcs that were performed. The direction of symmetry is normal to the insulator surface, so that the rails are effectively infinite in width. The rail surface ablates according to one of two ablation models, in which either all absorbed energy flux, or only the excess over that which the rail material can conduct away, ablates mass. A number of combinations of initial conditions, boundary conditions and resistivity models were explored. The full ablation model produces an arc of continuously growing mass and length, in which the current distribution reaches from the projectile half-way to the breech. The conduction limited ablation model produces a compact arc approximately eight times the bore height in length, which ceases to ablate material from the rails before the projectile reaches a velocity of 1 km/s. There is need for further study in several areas. These include the arc initiation process, the ablation of the insulators, and three-dimensional effects

  18. Optimization on Preparation Condition of Propolis Flavonoids Liposome by Response Surface Methodology and Research of Its Immunoenhancement Activity

    Directory of Open Access Journals (Sweden)

    Ju Yuan

    2013-01-01

    Full Text Available The aim of this study is to prepare propolis flavonoids liposome (PFL and optimize the preparation condition and to investigate further whether liposome could promote the immunoenhancement activity of propolis flavonoids (PF. PFL was prepared with ethanol injection method, and the preparation conditions of PFL were optimized with response surface methodology (RSM. Moreover, the immunoenhancement activity of PFL and PF in vitro was determined. The result showed that the optimal preparation conditions for PFL by response surface methodology were as follows: ratio of lipid to drug (w/w 9.6 : 1, ratio of soybean phospholipid to cholesterol (w/w 8.5 : 1, and speed of injection 0.8 mL·min−1. Under these conditions, the experimental encapsulation efficiency of PFL was 91.67 ± 0.21%, which was close to the predicted value. Therefore, the optimized preparation condition is very reliable. Moreover, the results indicated that PFL could not only significantly promote lymphocytes proliferation singly or synergistically with PHA, but also increase expression level of IL-2 and IFN-γ mRNA. These indicated that liposome could significantly improve the immunoenhancement activity of PF. PFL demonstrates the significant immunoenhancement activity, which provides the theoretical basis for the further experiment in vivo.

  19. [Optimization of prokaryotic expression conditions of Leptospira interrogans trigeminy genus-specific protein antigen based on surface response analysis].

    Science.gov (United States)

    Wang, Jiang; Luo, Dongjiao; Sun, Aihua; Yan, Jie

    2008-07-01

    Lipoproteins LipL32 and LipL21 and transmembrane protein OMPL1 have been confirmed as the superficial genus-specific antigens of Leptospira interrogans, which can be used as antigens for developing a universal genetic engineering vaccine. In order to obtain high expression of an artificial fusion gene lipL32/1-lipL21-ompL1/2, we optimized prokaryotic expression conditions. We used surface response analysis based on the central composite design to optimize culture conditions of a new antigen protein by recombinant Escherichia coli DE3.The culture conditions included initial pH, induction start time, post-induction time, Isopropyl beta-D-thiogalactopyranoside (IPTG) concentration, and temperature. The maximal production of antigen protein was 37.78 mg/l. The optimal culture conditions for high recombinant fusion protein was determined: initial pH 7.9, induction start time 2.5 h, a post-induction time of 5.38 h, 0.20 mM IPTG, and a post-induction temperature of 31 degrees C. Surface response analysis based on CCD increased the target production. This statistical method reduced the number of experiments required for optimization and enabled rapid identification and integration of the key culture condition parameters for optimizing recombinant protein expression.

  20. Determination of Optimum Condition of Leucine Content in Beef Protein Hydrolysate using Response Surface Methodology

    International Nuclear Information System (INIS)

    Siti Roha Ab Mutalib; Zainal Samicho; Noriham Abdullah

    2016-01-01

    The aim of this study is to determine the optimum condition of leucine content in beef hydrolysate. Beef hydrolysate was prepared by enzymatic hydrolysis using bromelain enzyme produced from pineapple peel. Parameter conditions such as concentration of bromelain, hydrolysis temperature and hydrolysis time were assessed to obtain the optimum leucine content of beef hydrolysate according to experimental design which was recommended by response surface methodology (RSM). Leucine content in beef hydrolysate was determined using AccQ. Tag amino acid analysis method using high performance liquid chromatography (HPLC). The condition of optimum leucine content was at bromelain concentration of 1.38 %, hydrolysis temperature of 42.5 degree Celcius and hydrolysis time of 31.59 hours with the predicted leucine content of 26.57 %. The optimum condition was verified with the leucine value obtained was 26.25 %. Since there was no significant difference (p>0.05) between the predicted and verified leucine values, thus it indicates that the predicted optimum condition by RSM can be accepted to predict the optimum leucine content in beef hydrolysate. (author)

  1. Comparative study of the free-surface boundary condition in two-dimensional finite-difference elastic wave field simulation

    International Nuclear Information System (INIS)

    Lan, Haiqiang; Zhang, Zhongjie

    2011-01-01

    The finite-difference (FD) method is a powerful tool in seismic wave field modelling for understanding seismic wave propagation in the Earth's interior and interpreting the real seismic data. The accuracy of FD modelling partly depends on the implementation of the free-surface (i.e. traction-free) condition. In the past 40 years, at least six kinds of free-surface boundary condition approximate schemes (such as one-sided, centred finite-difference, composed, new composed, implicit and boundary-modified approximations) have been developed in FD second-order elastodynamic simulation. Herein we simulate seismic wave fields in homogeneous and lateral heterogeneous models using these free-surface boundary condition approximate schemes and evaluate their stability and applicability by comparing with corresponding analytical solutions, and then quantitatively evaluate the accuracies of different approximate schemes from the misfit of the amplitude and phase between the numerical and analytical results. Our results confirm that the composed scheme becomes unstable for the V s /V p ratio less than 0.57, and suggest that (1) the one-sided scheme is only accurate to first order and therefore introduces serious errors for the shorter wavelengths, other schemes are all of second-order precision; (2) the new composed, implicit and boundary-modified schemes are stable even when the V s /V p ratio is less than 0.2; (3) the implicit and boundary-modified schemes are able to deal with laterally varying (heterogeneous) free surface; (4) in the corresponding stability range, the one-sided scheme shows remarkable errors in both phase and amplitude compared to analytical solution (which means larger errors in travel-time and reflection strength), the other five approximate schemes show better performance in travel-time (phase) than strength (amplitude)

  2. In vitro comparison of different 24% EDTA gel formulations efficacy on root surface conditioning

    OpenAIRE

    Sousa, Cliciane Portela; Frizzera, Fausto; Batista, Luiz Henrique Carvalho; Dantas, Andrea Abi Rached; Zandim-Barcelos, Daniela Leal; Sampaio, José Eduardo Cezar

    2013-01-01

    INTRODUCTION: The main goal of root biomodification is to modify the root surface in order to improve the repair of periodontal tissues destroyed by periodontal disease. OBJECTIVE: To evaluate the conditioning efficacy of 24% EDTA gel of different trademarks, considering the variables time and application method, by scanning electron microscopy. MATERIAL AND METHOD: 225 samples were randomly assigned to five groups: sterile saline solution (control); 24% EDTA (Santa Paula Pharmacy); 24% EDTA-...

  3. Assessing the ability of mechanistic volatilization models to simulate soil surface conditions: a study with the Volt'Air model.

    Science.gov (United States)

    Garcia, L; Bedos, C; Génermont, S; Braud, I; Cellier, P

    2011-09-01

    Ammonia and pesticide volatilization in the field is a surface phenomenon involving physical and chemical processes that depend on the soil surface temperature and water content. The water transfer, heat transfer and energy budget sub models of volatilization models are adapted from the most commonly accepted formalisms and parameterizations. They are less detailed than the dedicated models describing water and heat transfers and surface status. The aim of this work was to assess the ability of one of the available mechanistic volatilization models, Volt'Air, to accurately describe the pedo-climatic conditions of a soil surface at the required time and space resolution. The assessment involves: (i) a sensitivity analysis, (ii) an evaluation of Volt'Air outputs in the light of outputs from a reference Soil-Vegetation-Atmosphere Transfer model (SiSPAT) and three experimental datasets, and (iii) the study of three tests based on modifications of SiSPAT to establish the potential impact of the simplifying assumptions used in Volt'Air. The analysis confirmed that a 5 mm surface layer was well suited, and that Volt'Air surface temperature correlated well with the experimental measurements as well as with SiSPAT outputs. In terms of liquid water transfers, Volt'Air was overall consistent with SiSPAT, with discrepancies only during major rainfall events and dry weather conditions. The tests enabled us to identify the main source of the discrepancies between Volt'Air and SiSPAT: the lack of gaseous water transfer description in Volt'Air. They also helped to explain why neither Volt'Air nor SiSPAT was able to represent lower values of surface water content: current classical water retention and hydraulic conductivity models are not yet adapted to cases of very dry conditions. Given the outcomes of this study, we discuss to what extent the volatilization models can be improved and the questions they pose for current research in water transfer modeling and parameterization

  4. Gases Emission From Surface Layers of Sand Moulds and Cores Stored Under the Humid Air Conditions

    Directory of Open Access Journals (Sweden)

    Kaźnica N.

    2017-12-01

    Full Text Available A large number of defects of castings made in sand moulds is caused by gases. There are several sources of gases: gases emitted from moulds, cores or protective coatings during pouring and casting solidification; water in moulding sands; moisture adsorbed from surroundings due to atmospheric conditions changes. In investigations of gas volumetric emissions of moulding sands amounts of gases emitted from moulding sand were determined - up to now - in dependence of the applied binders, sand grains, protective coatings or alloys used for moulds pouring. The results of investigating gas volumetric emissions of thin-walled sand cores poured with liquid metal are presented in the hereby paper. They correspond to the surface layer in the mould work part, which is decisive for the surface quality of the obtained castings. In addition, cores were stored under conditions of a high air humidity, where due to large differences in humidity, the moisture - from surroundings - was adsorbed into the surface layer of the sand mould. Due to that, it was possible to asses the influence of the adsorbed moisture on the gas volumetric emission from moulds and cores surface layers by means of the new method of investigating the gas emission kinetics from thin moulding sand layers heated by liquid metal. The results of investigations of kinetics of the gas emission from moulding sands with furan and alkyd resins as well as with hydrated sodium silicate (water glass are presented. Kinetics of gases emissions from these kinds of moulding sands poured with Al-Si alloy were compared.

  5. Effects of phosphourus addition on the physical properties and surface condition of tungsten-copper composites

    International Nuclear Information System (INIS)

    Akiyoshi, N.; Nakada, K.; Nakayama, M.; Kohda, K.

    2001-01-01

    Tungsten-copper composites containing a small amount of phosphorus prepared using conventional P/M method. Cu 3 P powder was used as phosphorous source. The effects of phosphorus addition on the physical properties and the surface condition were investigated and the existing form of phosphorus was specified on the tungsten-copper composites The results are summarized as follows. The tungsten-copper composite containing 10 % copper, for example, demonstrated optimum thermal conductivity at the phosphorus addition of 0.02 %. The density of the composites was almost 100 % and the surface of the sintered body was flat and smooth after sintering at a temperature between 1100 and 1150 o C. It was shown that phosphorus exists as Co 2 P. (author)

  6. Influence of the biological conditions in the surface magnetic properties of nanocrystalline CoFeCrSiB ribbons

    International Nuclear Information System (INIS)

    Fal-Miyar, V.; Cerdeira, M.A.; Garcia, J.A.; Tejedor, M.; Potatov, A.P.; Pierna, A.R.; Marzo, F.F.; Vara, G.

    2007-01-01

    In this paper the result of a study of the influence of the biological conditions on the surface magnetic properties of nanocrystalline Co 64.5 Fe 2.5 Cr 3 B 15 Si 15 ribbons are presented and discussed. After the biological treatment the results show that, in the longitudinal direction, there is a hardening of the magnetic behavior and in the transverse direction the magnetization takes place in two steps. The surface saturation magnetization decreases in the treated samples. These results are explained considering the presence of magnetic oxides and non-conducting oxides on the surface of the treated samples

  7. Highly variable Pliocene sea surface conditions in the Norwegian Sea

    Directory of Open Access Journals (Sweden)

    P. E. Bachem

    2017-09-01

    Full Text Available The Pliocene was a time of global warmth with small sporadic glaciations, which transitioned towards the larger-scale Pleistocene glacial–interglacial variability. Here, we present high-resolution records of sea surface temperature (SST and ice-rafted debris (IRD in the Norwegian Sea from 5.32 to 3.14 Ma, providing evidence that the Pliocene surface conditions of the Norwegian Sea underwent a series of transitions in response to orbital forcing and gateway changes. Average SSTs are 2 °C above the regional Holocene mean, with notable variability on millennial to orbital timescales. Both gradual changes and threshold effects are proposed for the progression of regional climate towards the Late Pliocene intensification of Northern Hemisphere glaciation. Cooling from 4.5 to 4.3 Ma may be linked to the onset of poleward flow through the Bering Strait. This cooling was further intensified by a period of cool summers due to weak obliquity forcing. A 7 °C warming of the Norwegian Sea at 4.0 Ma suggests a major increase in northward heat transport from the North Atlantic, leading to an enhanced zonal SST gradient in the Nordic Seas, which may be linked to the expansion of sea ice in the Arctic and Nordic Seas. A warm Norwegian Sea and enhanced zonal temperature gradient between 4.0 and 3.6 Ma may have been a priming factor for increased glaciation around the Nordic Seas due to enhanced evaporation and precipitation at high northern latitudes.

  8. Long-term climate change: the evolution of shield surface boundary conditions

    International Nuclear Information System (INIS)

    Peltier, W.R.

    2007-01-01

    The Earths surface during the Pleistocene epoch has been repeatedly subjected to glacial cycles that have markedly influenced both the landscape and surface boundary conditions that, in part, governed past evolution of deep-seated Shield groundwater flow domains. As part of the Deep Geologic Repository Technology Programme simulations of the last Laurentide glacial episode have been undertaken with the University of Toronto Glacial System Model (GSM). The purpose of these simulations is to yield constrained predictions of the magnitude and time rate of change of peri-glacial, glacial and boreal regimes that have perturbed Shield flow domains in the geologic past. A detailed model of long timescale climate change has been developed, which is able to make useful predictions of the process of continental glaciation and deglaciation that has occurred in the past due to the small changes in the effective intensity of the Sun at the location of the Earth caused by gravitational many body effects in Solar System evolution. Based upon the success of this model we are able to assert that we have demonstrated a basic understanding of why this process has continually recurred in the past on a timescale of approximately 100 000 years. Continuing work with the Glacial Systems Model and efforts to provide explicit linkage to numerical analyses of sub-surface hydrology are beginning to yield a new understanding of groundwater flow system evolution and response to glacial perturbations. In so doing this understanding is not only providing a reasoned basis on which to examine issues of geosphere stability as relevant to the safety of a hypothetical repository for used nuclear fuel in Shield terrain, but is also offering an improved basis for the integrated interpretation of multi-disciplinary geo-scientific data necessary for development of a descriptive geosphere model that is seen as fundamental to the repository Safety Case. (author)

  9. Surface grinding characteristics of ferrous metals under high-speed and speed-stroke grinding conditions

    International Nuclear Information System (INIS)

    Ghani, A.K.; Choudhury, I.A.; Ahim, M.B.

    1999-01-01

    Some ferrous metals have been ground under different conditions with high-speed and speed-stroke in surface grinding operation. The paper describes experimental investigation of grinding forces in grinding some ferrous metals with the application of cutting fluids. Grinding tests have been carried out on mild steel, assab steel and stainless steel with different combinations of down feed and cross feed. The wheel speed was 27 m/sec while the table speed was maintained at the maximum possible 25 m/min. The grindability has been evaluated by measuring the grinding forces, grinding ratio, and surface finish. Grinding forces have been plotted against down feed of the grinding wheel and cross feed of the table. It has been observed that the radial and tangential grinding forces in stainless steel were higher than those in assab steel and mild steel

  10. Physicochemical characterization of engineered nanoparticles under physiological conditions: effect of culture media components and particle surface coating.

    Science.gov (United States)

    Fatisson, Julien; Quevedo, Ivan R; Wilkinson, Kevin J; Tufenkji, Nathalie

    2012-03-01

    The use of engineered nanoparticles (ENPs) in commercial products has increased substantially over the last few years. Some research has been conducted in order to determine whether or not such materials are cytotoxic, but questions remain regarding the role that physiological media and sera constituents play in ENP aggregation or stabilization. In this study, several characterization methods were used to evaluate the particle size and surface potential of 6 ENPs suspended in a number of culture media and in the presence of different culture media constituents. Dynamic light scattering (DLS) and fluorescence correlation spectroscopy (FCS) were employed for size determinations. Results were interpreted on the basis of ENP surface potentials evaluated from particle electrophoretic mobilities (EPM). Measurements made after 24h of incubation at 37°C showed that the cell culture medium constituents had only moderate impact on the physicochemical properties of the ENP, although incubation in bovine serum albumin destabilized the colloidal system. In contrast, most of the serum proteins increased colloidal stabilization. Moreover, the type of ENP surface modification played a significant role in ENP behavior whereby the complexity of interactions between the ENPs and the medium components generally decreased with increasing complexity of the particle surface. This investigation emphasizes the importance of ENP characterization under conditions that are representative of cell culture media or physiological conditions for improved assessments of nanoparticle cytotoxicity. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Breakdown conditioning of copper, CuZr and GlidCop® : effect of mechanical surface treatments

    CERN Document Server

    Ramsvik, T; Calatroni, S; Taborelli, M; CERN. Geneva. TS Department

    2007-01-01

    Motivated by the need of novel materials for the CLIC accelerating structures to resist mechanical fatigue, the copper based metals Copper Zirconium C15000 (CuZr) and GlidCop® Al-15 C15715 have been investigated by DC breakdown measurements, and compared with commercially pure Oxygen-free Copper C10100 (Cu-OFE). In all three cases the saturated breakdown fields (Esat) are similar, despite significant differences in their tensile strengths. In addition, the choice of mechanical surface preparation techniques influences the final breakdown characteristics. For both CuZr and GlidCop® immediate conditioning takes place when the surfaces are prepared by milling. For electro discharge machined (EDM) surfaces, however, several breakdown events are needed to obtain saturation. Specifically, for EDM treated CuZr and GlidCop®, ~50 and ~200 breakdown events are required to reach Esat.

  12. Effect of preparation conditions on physicochemical, surface and catalytic properties of cobalt ferrite prepared by coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    El-Shobaky, G.A., E-mail: elshobaky@yahoo.co [Physical Chemistry Department, National Research Center, Dokki, Cairo (Egypt); Turky, A.M.; Mostafa, N.Y.; Mohamed, S.K. [Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt)

    2010-03-18

    Cobalt ferrite nanoparticles were prepared via thermal treatment of cobalt-iron mixed hydroxides at 400-600 {sup o}C. The mixed hydroxides were coprecipitated from their nitrates solutions using NaOH as precipitating agent. The effects of pH and temperature of coprecipitation and calcination temperature on the physicochemical, surface and catalytic properties of the prepared ferrites were studied. The prepared systems were characterized using TG, DTG, DTA, chemical analysis, atomic absorption spectroscopy (AAS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) as well as surface and texture properties based on nitrogen adsorption-desorption isotherms. The prepared cobalt ferrites were found to be mesoporous materials that have crystallite size ranges between 8 and 45 nm. The surface and catalytic properties of the produced ferrite phase were strongly dependent on coprecipitation conditions of the mixed hydroxides and on their calcination temperature.

  13. Evaluation of surface detail reproduction, dimensional stability and gypsum compatibility of monophase polyvinyl-siloxane and polyether elastomeric impression materials under dry and moist conditions.

    Science.gov (United States)

    Vadapalli, Sriharsha Babu; Atluri, Kaleswararao; Putcha, Madhu Sudhan; Kondreddi, Sirisha; Kumar, N Suman; Tadi, Durga Prasad

    2016-01-01

    This in vitro study was designed to compare polyvinyl-siloxane (PVS) monophase and polyether (PE) monophase materials under dry and moist conditions for properties such as surface detail reproduction, dimensional stability, and gypsum compatibility. Surface detail reproduction was evaluated using two criteria. Dimensional stability was evaluated according to American Dental Association (ADA) specification no. 19. Gypsum compatibility was assessed by two criteria. All the samples were evaluated, and the data obtained were analyzed by a two-way analysis of variance (ANOVA) and Pearson's Chi-square tests. When surface detail reproduction was evaluated with modification of ADA specification no. 19, both the groups under the two conditions showed no significant difference statistically. When evaluated macroscopically both the groups showed statistically significant difference. Results for dimensional stability showed that the deviation from standard was significant among the two groups, where Aquasil group showed significantly more deviation compared to Impregum group (P < 0.001). Two conditions also showed significant difference, with moist conditions showing significantly more deviation compared to dry condition (P < 0.001). The results of gypsum compatibility when evaluated with modification of ADA specification no. 19 and by giving grades to the casts for both the groups and under two conditions showed no significant difference statistically. Regarding dimensional stability, both impregum and aquasil performed better in dry condition than in moist; impregum performed better than aquasil in both the conditions. When tested for surface detail reproduction according to ADA specification, under dry and moist conditions both of them performed almost equally. When tested according to macroscopic evaluation, impregum and aquasil performed significantly better in dry condition compared to moist condition. In dry condition, both the materials performed almost equally. In

  14. Influence of the initial surface condition on the release of nickel alloys in the primary circuit of PWRs

    International Nuclear Information System (INIS)

    Guinard, L.; Kerrec, O.; Noel, D.; Gardey, S.; Coulet, F.

    1997-01-01

    The effect of surface condition on corrosion and release and the mechanisms involved are investigated. The detrimental and beneficial effects of certain conditions or processes are identified: role of the last thermomechanical treatment, detrimental effect of cold-work, beneficial effect of electropolishing. The results can not be explained by mechanisms based only on solubility and mass transfer. Ionic migration through the inner barrier film is also probably involved. (K.A.)

  15. Implementation and Testing of Advanced Surface Boundary Conditions Over Complex Terrain in A Semi-idealized Model

    Science.gov (United States)

    Li, Y.; Epifanio, C.

    2017-12-01

    In numerical prediction models, the interaction between the Earth's surface and the atmosphere is typically accounted for in terms of surface layer parameterizations, whose main job is to specify turbulent fluxes of heat, moisture and momentum across the lower boundary of the model domain. In the case of a domain with complex geometry, implementing the flux conditions (particularly the tensor stress condition) at the boundary can be somewhat subtle, and there has been a notable history of confusion in the CFD community over how to formulate and impose such conditions generally. In the atmospheric case, modelers have largely been able to avoid these complications, at least until recently, by assuming that the terrain resolved at typical model resolutions is fairly gentle, in the sense of having relatively shallow slopes. This in turn allows the flux conditions to be imposed as if the lower boundary were essentially flat. Unfortunately, while this flat-boundary assumption is acceptable for coarse resolutions, as grids become more refined and the geometry of the resolved terrain becomes more complex, the appproach is less justified. With this in mind, the goal of our present study is to explore the implementation and usage of the full, unapproximated version of the turbulent flux/stress conditions in atmospheric models, thus taking full account of the complex geometry of the resolved terrain. We propose to implement the conditions using a semi-idealized model developed by Epifanio (2007), in which the discretized boundary conditions are reduced to a large, sparse-matrix problem. The emphasis will be on fluxes of momentum, as the tensor nature of this flux makes the associated stress condition more difficult to impose, although the flux conditions for heat and moisture will be considered as well. With the resulotion of 90 meters, some of the results show that the typical differences between flat-boundary cases and full/stress cases are on the order of 10%, with extreme

  16. Effect of sand versus grass training surfaces during an 8-week pre-season conditioning programme in team sport athletes.

    Science.gov (United States)

    Binnie, Martyn John; Dawson, Brian; Arnot, Mark Alexander; Pinnington, Hugh; Landers, Grant; Peeling, Peter

    2014-01-01

    This study compared the use of sand and grass training surfaces throughout an 8-week conditioning programme in well-trained female team sport athletes (n = 24). Performance testing was conducted pre- and post-training and included measures of leg strength and balance, vertical jump, agility, 20 m speed, repeat speed (8 × 20 m every 20 s), as well as running economy and maximal oxygen consumption (VO2max). Heart rate (HR), training load (rating of perceived exertion (RPE) × duration), movement patterns and perceptual measures were monitored throughout each training session. Participants completed 2 × 1 h conditioning sessions per week on sand (SAND) or grass (GRASS) surfaces, incorporating interval training, sprint and agility drills, and small-sided games. Results showed a significantly higher (P < 0.05) HR and training load in the SAND versus GRASS group throughout each week of training, plus some moderate effect sizes to suggest lower perceptual ratings of soreness and fatigue on SAND. Significantly greater (P < 0.05) improvements in VO2max were measured for SAND compared to GRASS. These results suggest that substituting sand for grass training surfaces throughout an 8-week conditioning programme can significantly increase the relative exercise intensity and training load, subsequently leading to superior improvements in aerobic fitness.

  17. Ground Boundary Conditions for Thermal Convection Over Horizontal Surfaces at High Rayleigh Numbers

    Science.gov (United States)

    Hanjalić, K.; Hrebtov, M.

    2016-07-01

    We present "wall functions" for treating the ground boundary conditions in the computation of thermal convection over horizontal surfaces at high Rayleigh numbers using coarse numerical grids. The functions are formulated for an algebraic-flux model closed by transport equations for the turbulence kinetic energy, its dissipation rate and scalar variance, but could also be applied to other turbulence models. The three-equation algebraic-flux model, solved in a T-RANS mode ("Transient" Reynolds-averaged Navier-Stokes, based on triple decomposition), was shown earlier to reproduce well a number of generic buoyancy-driven flows over heated surfaces, albeit by integrating equations up to the wall. Here we show that by using a set of wall functions satisfactory results are found for the ensemble-averaged properties even on a very coarse computational grid. This is illustrated by the computations of the time evolution of a penetrative mixed layer and Rayleigh-Bénard (open-ended, 4:4:1 domain) convection, using 10 × 10 × 100 and 10 × 10 × 20 grids, compared also with finer grids (e.g. 60 × 60 × 100), as well as with one-dimensional treatment using 1 × 1 × 100 and 1 × 1 × 20 nodes. The approach is deemed functional for simulations of a convective boundary layer and mesoscale atmospheric flows, and pollutant transport over realistic complex hilly terrain with heat islands, urban and natural canopies, for diurnal cycles, or subjected to other time and space variations in ground conditions and stratification.

  18. Evidence of the no-slip boundary condition of water flow between hydrophilic surfaces using atomic force microscopy.

    Science.gov (United States)

    Maali, Abdelhamid; Wang, Yuliang; Bhushan, Bharat

    2009-10-20

    In this study we present measurements of the hydrodynamic force exerted on a glass sphere glued to an atomic force microscopy (AFM) cantilever approaching a mica surface in water. A large sphere was used to reduce the impact of the cantilever beam on the measurement. An AFM cantilever with large stiffness was used to accurately determine the actual contact position between the sphere and the sample surface. The measured hydrodynamic force with different approach velocities is in good agreement with the Taylor force calculated in the lubrication theory with the no-slip boundary conditions, which verifies that there is no boundary slip on the glass and mica surfaces. Moreover, a detailed procedure of how to subtract the electrostatic double-layer force is presented.

  19. Effects of drop size and measuring condition on static contact angle measurement on a superhydrophobic surface with goniometric technique

    International Nuclear Information System (INIS)

    Seo, Kwangseok; Kim, Minyoung; Kim, Do Hyun; Ahn, Jeong Keun

    2015-01-01

    It is not a simple task to measure a contact angle of a water drop on a superhydrophobic surface with sessile drop method, because a roll-off angle is very low. Usually contact angle of a water drop on a superhydrophobic surface is measured by fixing a drop with intentional defects on the surface or a needle. We examined the effects of drop size and measuring condition such as the use of a needle or defects on the static contact angle measurement on superhydrophobic surface. Results showed that the contact angles on a superhydrophobic surface remain almost constant within intrinsic measurement errors unless there is a wetting transition during the measurement. We expect that this study will provide a deeper understanding on the nature of the contact angle and convenient measurement of the contact angle on the superhydrophobic surface.

  20. Electromagnetic diffraction by an impedance cylinder buried halfway between two half-spaces

    KAUST Repository

    Salem, Mohamed; Kamel, Aladin Hassan

    2011-01-01

    We consider the problem of electromagnetic diffraction from a cylinder with impedance surface and half-buried between two dielectric media. An arbitrary located electric dipole provides the excitation. The harmonic solution is presented as a series sum over a spectrum of a discrete-index Hankel transform, and the spectral amplitudes are determined by solving an infinite linear system of equations, which is constructed by applying the orthogonality relation of the 1D Green's function. © 2011 IEEE.

  1. Electromagnetic diffraction by an impedance cylinder buried halfway between two half-spaces

    KAUST Repository

    Salem, Mohamed

    2011-08-01

    We consider the problem of electromagnetic diffraction from a cylinder with impedance surface and half-buried between two dielectric media. An arbitrary located electric dipole provides the excitation. The harmonic solution is presented as a series sum over a spectrum of a discrete-index Hankel transform, and the spectral amplitudes are determined by solving an infinite linear system of equations, which is constructed by applying the orthogonality relation of the 1D Green\\'s function. © 2011 IEEE.

  2. Effect of cutting fluids and cutting conditions on surface integrity and tool wear in turning of Inconel 713C

    Science.gov (United States)

    Hikiji, R.

    2018-01-01

    The trend toward downsizing of engines helps to increase the number of turbochargers around Europe. As for the turbocharger, the temperature of the exhaust gas is so high that the parts made of nickel base super alloy Inconel 713C are used as high temperature strength metals. External turning of Inconel 713C which is used as the actual automotive parts was carried out. The effect of the cutting fluids and cutting conditions on the surface integrity and tool wear was investigated, considering global environment and cost performance. As a result, in the range of the cutting conditions used this time, when the depth of cut was small, the good surface integrity and tool life were obtained. However, in the case of the large corner radius, it was found that the more the cutting length increased, the more the tool wear increased. When the cutting length is so large, the surface integrity and tool life got worse. As for the cutting fluids, it was found that the synthetic type showed better performance in the surface integrity and tool life than the conventional emulsion. However, it was clear that the large corner radius made the surface roughness and tool life good, but it affected the size error etc. in machining the workpiece held in a cantilever style.

  3. Full 2D observation of water surface elevation from SWOT under different flow conditions

    Science.gov (United States)

    Domeneghetti, Alessio; Schumann, Guy; Rui, Wei; Durand, Michael; Pavelsky, Tamlin

    2016-04-01

    The upcoming Surface Water and Ocean Topography (SWOT) satellite mission is a joint project of NASA, Centre National d'Etudes Spatiales (CNES, France), the Canadian Space Agency, and the Space Agency of the UK that will provide a first global, high-resolution observation of ocean and terrestrial water surface heights. Characterized by an observation swath of 120 km and an orbit repeat interval of about 21 days, SWOT will provide unprecedented bi-dimensional observations of rivers wider than 50-100 m. Despite many research activities that have investigated potential uses of remotely sensed data from SWOT, potentials and limitations of the spatial observations provided by the satellite mission for flood modeling still remain poorly understood and investigated. In this study we present a first analysis of the spatial observation of water surface elevation that is expected from SWOT for a 140 km reach of the middle-lower portion of the Po River, in Northern Italy. The river stretch is characterized by a main channel varying from 200-500 m in width and a floodplain that can be as wide as 5 km and that is delimited by a system of major embankments. The reconstruction of the hydraulic behavior of the Po River is performed by means of a quasi-2d model built with detailed topographic and bathymetric information (LiDAR, 2 m resolution), while the simulation of the spatial observation sensed by SWOT is performed with a SWOT simulator that mimics the satellite sensor characteristics. Referring to water surface elevations associated with different flow conditions (maximum, minimum and average flow reproduced by means of the quasi-2d numerical model) this work provides a first characterization of the spatial observations provided by SWOT and highlights the strengths and limitations of the expected products. By referring to a real river reach the analysis provides a credible example of the type of spatial observations that will be available after launch of SWOT and offers a first

  4. Inspection Method for Contact Condition of Soil on the Surface of Underground Pipe Utilizing Resonance of Transverse Lamb Wave

    Science.gov (United States)

    Tanigawa, Hiroshi; Seno, Hiroaki; Watanabe, Yoshiaki; Nakajima, Koshiro

    1998-05-01

    A nondestructive inspection method to estimate the contact condition of soil on the surface of an underground pipe, utilizing the resonance of a transverse Lamb wave circulating along the pipe wall is proposed.The Q factor of the resonance is considered and measured under some contact conditions by sweeping the vibrating frequency in a 150-mm-inner diameter Fiberglass Reinforced Plastic Mortar (FRPM) pipe. It is confirmed that the Q factor shows a clear response to the change in the contact conditions. For example, the Q factor is 8.4 when the pipe is in ideal contact with the soil plane and goes up to 19.2 when a 100-mm-diameter void is located at the contact surface of the soil.The spatial resolution of the proposed inspection method is also measured by moving the sensing point along the direction of laying the length of the pipe into a 85-mm-diameter void. The resolution of the proposed method is estimated at about 50 mm.

  5. Influence of the initial surface condition on the release of nickel alloys in the primary circuit of PWRs

    Energy Technology Data Exchange (ETDEWEB)

    Guinard, L.; Kerrec, O.; Noel, D.; Gardey, S.; Coulet, F.

    1997-01-01

    The effect of surface condition on corrosion and release and the mechanisms involved are investigated. The detrimental and beneficial effects of certain conditions or processes are identified: role of the last thermomechanical treatment, detrimental effect of cold-work, beneficial effect of electropolishing. The results can not be explained by mechanisms based only on solubility and mass transfer. Ionic migration through the inner barrier film is also probably involved. (K.A.). 32 refs.

  6. Direct generation of titanium dioxide nanoparticles dispersion under supercritical conditions for photocatalytic active thermoplastic surfaces for microbiological inactivation

    International Nuclear Information System (INIS)

    Zydziak, Nicolas; Zanin, Maria-Helena Ambrosio; Trick, Iris; Hübner, Christof

    2015-01-01

    Thermoplastic poly(propylene) (PP) and acrylonitrile-butadiene-styrene (ABS) surfaces were coated with silica based films via the sol–gel process, containing titanium dioxide (TiO 2 ) as photocatalyst. TiO 2 was previously synthesized via sol–gel and treated under supercritical conditions in water dispersions. The characterization of the TiO 2 dispersions was performed via disc centrifuge to determine the particle size and via Raman spectroscopy and X-Ray Diffraction (XRD) to characterize the crystallinity of TiO 2 . The synthesized TiO 2 dispersions and commercially available TiO 2 particles were incorporated in silica based films which were synthesized under acidic or basic conditions, leading to dense or porous films respectively. The morphology of the films was characterized via Scanning Electron Microscopy (SEM). The incorporation of synthesized TiO 2 in the coating led to photocatalytically more active thermoplastic surfaces than films formulated with commercially available TiO 2 as determined via dye discoloration test. A microbiological test performed with Sarcina lutea confirmed this result and showed an inactivation factor of 6 (99.9999%) after 24 h UV irradiation, for synthesized TiO 2 incorporated in acidic formulated silica layer on ABS surfaces. - Highlights: • We report about photocatalytic layers formulated on thermoplastic surfaces. • We synthesized silica layer and TiO 2 via sol–gel and supercritical treatment. • Amorphous, crystalline and commercial dispersions were generated and characterized. • The morphology of dense and porous photocatalytic layers is observed via SEM. • Discoloration and microbiological tests correlate activity and surface morphology

  7. Surface analysis, by SNMS, of 316L steel exposed to simulated BWR conditions

    International Nuclear Information System (INIS)

    Buckley, D.; Schenker, E.

    1994-01-01

    Samples of 316L steel have been exposed to Boiling Light Water Reactor chemistry for between forty and seven thousand hours. These samples, with three different surface finishes, 'as-delivered', mechanically polished and electro-polished, have been analysed by Sputtered Neutral Mass Spectrometry and profiles of the constituent alloying elements have been obtained. Differences in the oxide that has built-up are compared and discussed in terms of current ideas of corrosion mechanisms. The structure of the oxide changes with exposure time for the experimental conditions. The effect of surface finish and water velocity have a clear marked effect on the oxide structure and growth rate, respectively: samples in a low water velocity stream form the protective oxide, chromia, and some mixed spinels; electro-polished samples have no chromium layer but show possible secondary passivation through the build-up of nickel; and samples in high velocity water form a simple structured oxide that does not reach a saturation thickness after 291 days but steadily increases. (author) 9 figs., 3 tabs., 7 refs

  8. Optimization of Electrochemical Treatment Process Conditions for Distillery Effluent Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    P. Arulmathi

    2015-01-01

    Full Text Available Distillery industry is recognized as one of the most polluting industries in India with a large amount of annual effluent production. In this present study, the optimization of electrochemical treatment process variables was reported to treat the color and COD of distillery spent wash using Ti/Pt as an anode in a batch mode. Process variables such as pH, current density, electrolysis time, and electrolyte dose were selected as operation variables and chemical oxygen demand (COD and color removal efficiency were considered as response variable for optimization using response surface methodology. Indirect electrochemical-oxidation process variables were optimized using Box-Behnken response surface design (BBD. The results showed that electrochemical treatment process effectively removed the COD (89.5% and color (95.1% of the distillery industry spent wash under the optimum conditions: pH of 4.12, current density of 25.02 mA/cm2, electrolysis time of 103.27 min, and electrolyte (NaCl concentration of 1.67 g/L, respectively.

  9. The static friction response of non-glabrous skin as a function of surface energy and environmental conditions

    NARCIS (Netherlands)

    Klaassen, Michel; de Vries, Erik G.; Masen, Marc Arthur

    2017-01-01

    The (local) environmental conditions have a significant effect on the interaction between skin and products. Plasticisation of the stratum corneum occurs at high humidity, causing this layer to soften and change its surface free energy. In this work we study the effects of the micro-climate on the

  10. DFT study of oxygen adsorption on Mo{sub 2}C(001) and (201) surfaces at different conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Lihong, E-mail: chenglihong001@126.com [School of Materials and Mechanical & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013, Jiangxi (China); Li, Wenkui; Chen, Zhiqin; Ai, Jianping; Zhou, Zehua [School of Materials and Mechanical & Electrical Engineering, Jiangxi Science and Technology Normal University, Nanchang 330013, Jiangxi (China); Liu, Jianwen, E-mail: liujw@nsccsz.gov.cn [National Supercomputing Center in Shenzhen, Shenzhen 518055 (China)

    2017-07-31

    Highlights: • O adsorption manners on Mo{sub 2}C surfaces were calculated by DFT method. • Stable oxygen adsorption states and coverage were identified at given T and p. • O{sub 2} results in full oxidation while H{sub 2}O and CO{sub 2} cause partial oxidation of Mo{sub 2}C surfaces. • Hydrogen could be used to avoid Mo{sub 2}C surface oxidation. - Abstract: Density functional theory (DFT) calculations were performed to investigate oxygen adsorption on Mo{sub 2}C(001) and (201)surfaces at different coverage. The energies and structures of oxygen from lowest to saturated coverages were clearly identified on each surface. Thermodynamics method was introduced to reveal the roles of temperature, pressure as well as oxygen sources (O{sub 2}, H{sub 2}O and CO{sub 2}) on the surface oxygen coverage, which is related to the surface oxidation. On the basis of phase diagram, we can easily identify the stable oxygen coverage at different defined conditions. In addition, it reveals that O{sub 2} is the strongest oxidant, which results in the full coverage of oxygen on both surfaces in a wide range of temperature and pressure. Then, H{sub 2}O and CO{sub 2} are weaker oxidants, which could only cause partial oxidation of Mo{sub 2}C surfaces. These results indicate the facile oxidation of Mo{sub 2}C catalyst. The possible ways to avoid surface oxidation are keeping higher temperature and H{sub 2} pressure in the gas phase.

  11. Capability of space-spectral analysis used for studying underground nuclear explosions effect on ground surface condition

    International Nuclear Information System (INIS)

    Melent'ev, M.I.; Velikanov, A.E.

    2003-01-01

    The article describes the results of the work of study of the influence underground nucleus blasts (UNB) on condition of the day surface of the site Balapan on the territory of Semipalatinsk Test Site using materials of remote space sensing. The estimation of the cosmic spectral analysis information density is given for revealing the post-explosive geo- dynamic processes. (author)

  12. Application and evaluation of LS-PIV technique for the monitoring of river surface velocities in high flow conditions

    OpenAIRE

    Jodeau , M.; Hauet , A.; Paquier , A.; Le Coz , J.; Dramais , G.

    2008-01-01

    Large Scale Particle Image Velocimetry (LS-PIV) is used to measure the surface flow velocities in a mountain stream during high flow conditions due to a reservoir release. A complete installation including video acquisition from a mobile elevated viewpoint and artificial flow seeding has been developed and implemented. The LS-PIV method was adapted in order to take into account the specific constraints of these high flow conditions. Using a usual LS-PIV data processing, significant variations...

  13. Heat and mass transfer boundary conditions at the surface of a heated sessile droplet

    Science.gov (United States)

    Ljung, Anna-Lena; Lundström, T. Staffan

    2017-12-01

    This work numerically investigates how the boundary conditions of a heated sessile water droplet should be defined in order to include effects of both ambient and internal flow. Significance of water vapor, Marangoni convection, separate simulations of the external and internal flow, and influence of contact angle throughout drying is studied. The quasi-steady simulations are carried out with Computational Fluid Dynamics and conduction, natural convection and Marangoni convection are accounted for inside the droplet. For the studied conditions, a noticeable effect of buoyancy due to evaporation is observed. Hence, the inclusion of moisture increases the maximum velocities in the external flow. Marangoni convection will, in its turn, increase the velocity within the droplet with up to three orders of magnitude. Results furthermore show that the internal and ambient flow can be simulated separately for the conditions studied, and the accuracy is improved if the internal temperature gradient is low, e.g. if Marangoni convection is present. Simultaneous simulations of the domains are however preferred at high plate temperatures if both internal and external flows are dominated by buoyancy and natural convection. The importance of a spatially resolved heat and mass transfer boundary condition is, in its turn, increased if the internal velocity is small or if there is a large variation of the transfer coefficients at the surface. Finally, the results indicate that when the internal convective heat transport is small, a rather constant evaporation rate may be obtained throughout the drying at certain conditions.

  14. THINK Half-Way and Beyond

    OpenAIRE

    GLACHANT, Jean-Michel; MEEUS, Leonardo; RUESTER, Sophia

    2012-01-01

    THINK is a Think Tank advising the European Commission on mid- and long-term energy policy. QM-32-12-022-EN-C (print) QM-32-12-022-EN-N (digital) Energy regulation and policy currently belong to the most important and developing areas in the European Union. THINK, the Florence School of Regulation’s (EUI) think tank advises the European Commission (DG Energy) on Energy Policy and presents policy options each semester. This booklet gives an overview of all the THINK results for the first 18...

  15. Their Name is Half-Way

    Directory of Open Access Journals (Sweden)

    Elena Bagina

    2014-01-01

    Full Text Available The article is devoted to the phenomenon of the Soviet architecture of the late 1950s – 60s. The name of the article is “Their name is halfway”. It expresses the sense of all the processes occurring both in society and architecture during the Khrushchev Thaw. Developing the socalled Stalin’s Empire in the 1930-1950s, the masters of architecture had travelled only half the way. If the power had not abruptly stopped this movement, we would probably have a unique modern architecture dissimilar to the “international style”. The collapse of the Soviet Union stopped the evolution of architecture again: the unique features of the Soviet architecture of the 1960s ceased to develop. Architects were carried away with ironic games of postmodernism, which led them to deadlock.

  16. Commentary: Memory Development: Halfway There?

    Science.gov (United States)

    Newcombe, Nora S.

    2015-01-01

    The study of development vacillates between a focus on change (i.e., studying how and why infants are so different from adults) and excitement about early competence and continuity (i.e., studying how capable infants are, and marveling at how similar they turn out to be to adults). The study of memory development has been no exception. This…

  17. Direct generation of titanium dioxide nanoparticles dispersion under supercritical conditions for photocatalytic active thermoplastic surfaces for microbiological inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Zydziak, Nicolas, E-mail: nicolas.zydziak@kit.edu [Polymer Engineering Department, Fraunhofer Institute of Chemical Technology, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany); Zanin, Maria-Helena Ambrosio [Laboratory of Chemical Processes and Particle Technology Bionanomanufacturing, Institute for Technological Research of the State of São Paulo – IPT, Av. Prof. Almeida Prado 532, Cidade Universitária, CEP 05508-901 São Paulo, SP (Brazil); Trick, Iris [Environmental Biotechnology and Bioprocess Engineering Department, Fraunhofer Institute for Interfacial Engineering and Biotechnology, Nobelstrasse 12, 70569 Stuttgart (Germany); Hübner, Christof [Polymer Engineering Department, Fraunhofer Institute of Chemical Technology, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal (Germany)

    2015-03-01

    Thermoplastic poly(propylene) (PP) and acrylonitrile-butadiene-styrene (ABS) surfaces were coated with silica based films via the sol–gel process, containing titanium dioxide (TiO{sub 2}) as photocatalyst. TiO{sub 2} was previously synthesized via sol–gel and treated under supercritical conditions in water dispersions. The characterization of the TiO{sub 2} dispersions was performed via disc centrifuge to determine the particle size and via Raman spectroscopy and X-Ray Diffraction (XRD) to characterize the crystallinity of TiO{sub 2}. The synthesized TiO{sub 2} dispersions and commercially available TiO{sub 2} particles were incorporated in silica based films which were synthesized under acidic or basic conditions, leading to dense or porous films respectively. The morphology of the films was characterized via Scanning Electron Microscopy (SEM). The incorporation of synthesized TiO{sub 2} in the coating led to photocatalytically more active thermoplastic surfaces than films formulated with commercially available TiO{sub 2} as determined via dye discoloration test. A microbiological test performed with Sarcina lutea confirmed this result and showed an inactivation factor of 6 (99.9999%) after 24 h UV irradiation, for synthesized TiO{sub 2} incorporated in acidic formulated silica layer on ABS surfaces. - Highlights: • We report about photocatalytic layers formulated on thermoplastic surfaces. • We synthesized silica layer and TiO{sub 2} via sol–gel and supercritical treatment. • Amorphous, crystalline and commercial dispersions were generated and characterized. • The morphology of dense and porous photocatalytic layers is observed via SEM. • Discoloration and microbiological tests correlate activity and surface morphology.

  18. LSST summit facility construction progress report: reacting to design refinements and field conditions

    Science.gov (United States)

    Barr, Jeffrey D.; Gressler, William; Sebag, Jacques; Seriche, Jaime; Serrano, Eduardo

    2016-07-01

    The civil work, site infrastructure and buildings for the summit facility of the Large Synoptic Survey Telescope (LSST) are among the first major elements that need to be designed, bid and constructed to support the subsequent integration of the dome, telescope, optics, camera and supporting systems. As the contracts for those other major subsystems now move forward under the management of the LSST Telescope and Site (T and S) team, there has been inevitable and beneficial evolution in their designs, which has resulted in significant modifications to the facility and infrastructure. The earliest design requirements for the LSST summit facility were first documented in 2005, its contracted full design was initiated in 2010, and construction began in January, 2015. During that entire development period, and extending now roughly halfway through construction, there continue to be necessary modifications to the facility design resulting from the refinement of interfaces to other major elements of the LSST project and now, during construction, due to unanticipated field conditions. Changes from evolving interfaces have principally involved the telescope mount, the dome and mirror handling/coating facilities which have included significant variations in mass, dimensions, heat loads and anchorage conditions. Modifications related to field conditions have included specifying and testing alternative methods of excavation and contending with the lack of competent rock substrate where it was predicted to be. While these and other necessary changes are somewhat specific to the LSST project and site, they also exemplify inherent challenges related to the typical timeline for the design and construction of astronomical observatory support facilities relative to the overall development of the project.

  19. Evaluation of Surface Fatigue Strength Based on Surface Temperature

    Science.gov (United States)

    Deng, Gang; Nakanishi, Tsutomu

    Surface temperature is considered to be an integrated index that is dependent on not only the load and the dimensions at the contact point but also the sliding velocity, rolling velocity, surface roughness, and lubrication conditions. Therefore, the surface durability of rollers and gears can be evaluated more exactly and simply by the use of surface temperature rather than Hertzian stress. In this research, surface temperatures of rollers under different rolling and sliding conditions are measured using a thermocouple. The effects of load P, mean velocity Vm and sliding velocity Vs on surface temperature are clarified. An experimental formula, which expresses the linear relationship between surface temperature and the P0.86Vs1.31Vm-0.83 value, is used to determine surface temperature. By comparing calculated and measured temperature on the tooth surface of a gear, this formula is confirmed to be applicable for gear tooth surface temperature calculation.

  20. Robust and general method for determining surface fluid flow boundary conditions in articular cartilage contact mechanics modeling.

    Science.gov (United States)

    Pawaskar, Sainath Shrikant; Fisher, John; Jin, Zhongmin

    2010-03-01

    Contact detection in cartilage contact mechanics is an important feature of any analytical or computational modeling investigation when the biphasic nature of cartilage and the corresponding tribology are taken into account. The fluid flow boundary conditions will change based on whether the surface is in contact or not, which will affect the interstitial fluid pressurization. This in turn will increase or decrease the load sustained by the fluid phase, with a direct effect on friction, wear, and lubrication. In laboratory experiments or clinical hemiarthroplasty, when a rigid indenter or metallic prosthesis is used to apply load to the cartilage, there will not be any fluid flow normal to the surface in the contact region due to the impermeable nature of the indenter/prosthesis. In the natural joint, on the other hand, where two cartilage surfaces interact, flow will depend on the pressure difference across the interface. Furthermore, in both these cases, the fluid would flow freely in non-contacting regions. However, it should be pointed out that the contact area is generally unknown in advance in both cases and can only be determined as part of the solution. In the present finite element study, a general and robust algorithm was proposed to decide nodes in contact on the cartilage surface and, accordingly, impose the fluid flow boundary conditions. The algorithm was first tested for a rigid indenter against cartilage model. The algorithm worked well for two-dimensional four-noded and eight-noded axisymmetric element models as well as three-dimensional models. It was then extended to include two cartilages in contact. The results were in excellent agreement with the previous studies reported in the literature.

  1. Optimization of deposition conditions of CdS thin films using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Yücel, Ersin, E-mail: dr.ersinyucel@gmail.com [Department of Physics, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey); Güler, Nuray [Department of Physics, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey); Yücel, Yasin [Department of Chemistry, Faculty of Arts and Sciences, Mustafa Kemal University, 31034 Hatay (Turkey)

    2014-03-15

    Highlights: • Statistical methods used for optimization of CdS deposition parameters. • The morphology of the films was smooth, homogeneous and continuous. • Optimal conditions found as pH 11, stirring speed:361 rpm and deposition time: 55 min. • CdS thin film band gap value was 2.72 eV under the optimum conditions. -- Abstract: Cadmium sulfide (CdS) thin films were prepared on glass substrates by chemical bath deposition (CBD) technique under different pH, stirring speed and deposition time. Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to optimization of deposition parameters of the CdS thin films. RSM and CCD were also used to understand the significance and interaction of the factors affecting the film quality. Variables were determined as pH, stirring speed and deposition time. The band gap was chosen as response in the study. Influences of the variables on the band gap and the film quality were investigated. 5-level-3-factor central composite design was employed to evaluate the effects of the deposition conditions parameters such as pH (10.2–11.8), stirring speed (132–468 rpm) and deposition time (33–67 min) on the band gap of the films. The samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet–visible spectroscopy (UV–vis) measurements. The optimal conditions for the deposition parameters of the CdS thin films have been found to be: pH 11, 361 of stirring speed and 55 min of deposition time. Under the optimal conditions theoretical (predicted) band gap of CdS (2.66 eV) was calculated using optimal coded values from the model and the theoretical value is good agreement with the value (2.72 eV) obtained by verification experiment.

  2. The effect of simulated inflammatory conditions on the surface properties of titanium and stainless steel and their importance as biomaterials

    International Nuclear Information System (INIS)

    Fonseca-García, Abril; Pérez-Alvarez, J.; Barrera, C.C.; Medina, J.C.; Almaguer-Flores, A.; Sánchez, R. Basurto

    2016-01-01

    This work compares the surface modifications induced by the immersion in solutions that simulate inflammatory conditions of pure titanium (cpTi) and medical grade stainless steel (SS). The inflammatory conditions were simulated using a mixture of Hartman solution and 50 mM of hydrogen peroxide (H_2O_2) at pH = 5.2. The samples were immersed by 7 days refreshing the solution every day to keep the reactivity of the H_2O_2. The surface characteristics that were investigated were: elemental composition by X-ray photoelectron spectroscopy (XPS); topography by atomic force microscopy (AFM) and profilometry; wettability and surface energy by sessile drop contact angle and point of zero charge by titration. Moreover, the variations in the electrochemical response were evaluated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) performed before and after the treatment using the Hartman solution as the electrolyte. The XPS results indicated that for both metallic samples, oxidation of the surface was promoted and/or the oxide layer was thicker after the immersion. The roughness and the solid-liquid surface energy were increased; the samples showed a more hydrophilic character after the treatment. However, the surface energy of the solid estimated using the Van Oss–Chaudhury–Good approach showed different trends between the cpTi and the SS surfaces; the polar component decreased for cpTi, while it increased for SS. Finally, the electrochemical results indicated that the corrosion resistance (R_c_o_r) and the pore resistance (R_p_o) significantly decreased for cpTi, while both resistances were not significantly different for the SS. This is indicative of a higher dissolution of the cpTi compared to SS and the lower R_p_o means that the species are easily transported through the surface layer, which can be explained in terms of the formation of a porous TiO_x layer, not observed on the SS. The cpTi surface

  3. The effect of simulated inflammatory conditions on the surface properties of titanium and stainless steel and their importance as biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca-García, Abril [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México, México (Mexico); Pérez-Alvarez, J. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México (Mexico); Barrera, C.C. [Posgrado en Ciencias Médicas, Odontológicas y de la Salud, Universidad Nacional Autónoma de México, México (Mexico); Medina, J.C. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México (Mexico); Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México, México (Mexico); Almaguer-Flores, A. [Facultad de Odontología, Universidad Nacional Autónoma de México, México (Mexico); Sánchez, R. Basurto [Instituto Nacional de Investigaciones Nucleares, México (Mexico); and others

    2016-09-01

    This work compares the surface modifications induced by the immersion in solutions that simulate inflammatory conditions of pure titanium (cpTi) and medical grade stainless steel (SS). The inflammatory conditions were simulated using a mixture of Hartman solution and 50 mM of hydrogen peroxide (H{sub 2}O{sub 2}) at pH = 5.2. The samples were immersed by 7 days refreshing the solution every day to keep the reactivity of the H{sub 2}O{sub 2}. The surface characteristics that were investigated were: elemental composition by X-ray photoelectron spectroscopy (XPS); topography by atomic force microscopy (AFM) and profilometry; wettability and surface energy by sessile drop contact angle and point of zero charge by titration. Moreover, the variations in the electrochemical response were evaluated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) performed before and after the treatment using the Hartman solution as the electrolyte. The XPS results indicated that for both metallic samples, oxidation of the surface was promoted and/or the oxide layer was thicker after the immersion. The roughness and the solid-liquid surface energy were increased; the samples showed a more hydrophilic character after the treatment. However, the surface energy of the solid estimated using the Van Oss–Chaudhury–Good approach showed different trends between the cpTi and the SS surfaces; the polar component decreased for cpTi, while it increased for SS. Finally, the electrochemical results indicated that the corrosion resistance (R{sub cor}) and the pore resistance (R{sub po}) significantly decreased for cpTi, while both resistances were not significantly different for the SS. This is indicative of a higher dissolution of the cpTi compared to SS and the lower R{sub po} means that the species are easily transported through the surface layer, which can be explained in terms of the formation of a porous TiO{sub x} layer, not

  4. Experimental calibration and validation of sewer/surface flow exchange equations in steady and unsteady flow conditions

    Science.gov (United States)

    Rubinato, Matteo; Martins, Ricardo; Kesserwani, Georges; Leandro, Jorge; Djordjević, Slobodan; Shucksmith, James

    2017-09-01

    The linkage between sewer pipe flow and floodplain flow is recognised to induce an important source of uncertainty within two-dimensional (2D) urban flood models. This uncertainty is often attributed to the use of empirical hydraulic formulae (the one-dimensional (1D) weir and orifice steady flow equations) to achieve data-connectivity at the linking interface, which require the determination of discharge coefficients. Because of the paucity of high resolution localised data for this type of flows, the current understanding and quantification of a suitable range for those discharge coefficients is somewhat lacking. To fulfil this gap, this work presents the results acquired from an instrumented physical model designed to study the interaction between a pipe network flow and a floodplain flow. The full range of sewer-to-surface and surface-to-sewer flow conditions at the exchange zone are experimentally analysed in both steady and unsteady flow regimes. Steady state measured discharges are first analysed considering the relationship between the energy heads from the sewer flow and the floodplain flow; these results show that existing weir and orifice formulae are valid for describing the flow exchange for the present physical model, and yield new calibrated discharge coefficients for each of the flow conditions. The measured exchange discharges are also integrated (as a source term) within a 2D numerical flood model (a finite volume solver to the 2D Shallow Water Equations (SWE)), which is shown to reproduce the observed coefficients. This calibrated numerical model is then used to simulate a series of unsteady flow tests reproduced within the experimental facility. Results show that the numerical model overestimated the values of mean surcharge flow rate. This suggests the occurrence of additional head losses in unsteady conditions which are not currently accounted for within flood models calibrated in steady flow conditions.

  5. Uropathogenic Escherichia coli Express Type 1 Fimbriae Only in Surface Adherent Populations Under Physiological Growth Conditions

    DEFF Research Database (Denmark)

    Stærk, Kristian; Kolmos, Hans Jørn; Khandige, Surabhi

    2016-01-01

    were correlated with the ability to adhere to and invade cultured human bladder cells. RESULTS:  Although inactive during planktonic growth in urine, T1F expression occurs when UPEC settles on and infects bladder epithelial cells or colonizes catheters. As a result, UPEC in these sessile populations...... with increased expression during surface growth adaptation and infection of uroepithelial cells. This leads to separation of UPEC into low-expression planktonic populations and high-expression sessile populations....... enhances bladder cell adhesion and invasion potential. Only T1F-negative UPEC are subsequently released to the urine, thus limiting T1F expression to surface-associated UPEC alone. CONCLUSION:  Our results demonstrate that T1F expression is strictly regulated under physiological growth conditions...

  6. The bactericidal effect of surface micro-discharge plasma under different ambient conditions

    International Nuclear Information System (INIS)

    Shimizu, T; Zimmermann, J L; Morfill, G E

    2011-01-01

    A series of experiments on the bactericidal properties of plasmas using a surface micro-discharge (SMD) device in an atmosphere under different ambient temperatures and humidities was carried out. This plasma dispenser was developed for use as a disinfection system in private and public places (hospitals, medical practices, etc). The bactericidal effect is due to the interplay of the plasma and the chemical products produced via interactions with O 2 /N 2 and H 2 O vapour in air. To use this device in different countries and therefore under various ambient conditions, it is important to understand its behaviour and efficiency, especially with respect to air temperature and humidity. The experimental results obtained in this study show that the bactericidal properties of the SMD plasma dispenser are not sensitive to the different temperatures and humidities.

  7. The bactericidal effect of surface micro-discharge plasma under different ambient conditions

    Science.gov (United States)

    Shimizu, T.; Zimmermann, J. L.; Morfill, G. E.

    2011-02-01

    A series of experiments on the bactericidal properties of plasmas using a surface micro-discharge (SMD) device in an atmosphere under different ambient temperatures and humidities was carried out. This plasma dispenser was developed for use as a disinfection system in private and public places (hospitals, medical practices, etc). The bactericidal effect is due to the interplay of the plasma and the chemical products produced via interactions with O2/N2 and H2O vapour in air. To use this device in different countries and therefore under various ambient conditions, it is important to understand its behaviour and efficiency, especially with respect to air temperature and humidity. The experimental results obtained in this study show that the bactericidal properties of the SMD plasma dispenser are not sensitive to the different temperatures and humidities.

  8. Characterizing near-surface CO2 conditions before injection - Perspectives from a CCS project in the Illinois Basin, USA

    Science.gov (United States)

    Locke, R.A.; Krapac, I.G.; Lewicki, J.L.; Curtis-Robinson, E.

    2011-01-01

    The Midwest Geological Sequestration Consortium is conducting a large-scale carbon capture and storage (CCS) project in Decatur, Illinois, USA to demonstrate the ability of a deep saline formation to store one million tonnes of carbon dioxide (CO2) from an ethanol facility. Beginning in early 2011, CO2 will be injected at a rate of 1,000 tonnes/day for three years into the Mount Simon Sandstone at a depth of approximately 2,100 meters. An extensive Monitoring, Verification, and Accounting (MVA) program has been undertaken for the Illinois Basin Decatur Project (IBDP) and is focused on the 0.65 km2 project site. Goals include establishing baseline conditions to evaluate potential impacts from CO2 injection, demonstrating that project activities are protective of human health and the environment, and providing an accurate accounting of stored CO2. MVA efforts are being conducted pre-, during, and post- CO2 injection. Soil and net CO2 flux monitoring has been conducted for more than one year to characterize near-surface CO2 conditions. More than 2,200 soil CO2 flux measurements have been manually collected from a network of 118 soil rings since June 2009. Three ring types have been evaluated to determine which type may be the most effective in detecting potential CO 2 leakage. Bare soil, shallow-depth rings were driven 8 cm into the ground and were prepared to minimize surface vegetation in and near the rings. Bare soil, deep-depth rings were prepared similarly, but were driven 46 cm. Natural-vegetation, shallow-depth rings were driven 8 cm and are most representative of typical vegetation conditions. Bare-soil, shallow-depth rings had the smallest observed mean flux (1.78 ??mol m-2 s-1) versus natural-vegetation, shallow-depth rings (3.38 ??mol m-2 s-1). Current data suggest bare ring types would be more sensitive to small CO2 leak signatures than natural ring types because of higher signal to noise ratios. An eddy covariance (EC) system has been in use since June

  9. Parallel Study of HEND, RAD, and DAN Instrument Response to Martian Radiation and Surface Conditions

    Science.gov (United States)

    Martiniez Sierra, Luz Maria; Jun, Insoo; Litvak, Maxim; Sanin, Anton; Mitrofanov, Igor; Zeitlin, Cary

    2015-01-01

    Nuclear detection methods are being used to understand the radiation environment at Mars. JPL (Jet Propulsion Laboratory) assets on Mars include: Orbiter -2001 Mars Odyssey [High Energy Neutron Detector (HEND)]; Mars Science Laboratory Rover -Curiosity [(Radiation Assessment Detector (RAD); Dynamic Albedo Neutron (DAN))]. Spacecraft have instruments able to detect ionizing and non-ionizing radiation. Instrument response on orbit and on the surface of Mars to space weather and local conditions [is discussed] - Data available at NASA-PDS (Planetary Data System).

  10. Ensemble perturbation smoother for optimizing tidal boundary conditions by assimilation of High-Frequency radar surface currents – application to the German Bight

    Directory of Open Access Journals (Sweden)

    A. Barth

    2010-02-01

    Full Text Available High-Frequency (HF radars measure the ocean surface currents at various spatial and temporal scales. These include tidal currents, wind-driven circulation, density-driven circulation and Stokes drift. Sequential assimilation methods updating the model state have been proven successful to correct the density-driven currents by assimilation of observations such as sea surface height, sea surface temperature and in-situ profiles. However, the situation is different for tides in coastal models since these are not generated within the domain, but are rather propagated inside the domain through the boundary conditions. For improving the modeled tidal variability it is therefore not sufficient to update the model state via data assimilation without updating the boundary conditions. The optimization of boundary conditions to match observations inside the domain is traditionally achieved through variational assimilation methods. In this work we present an ensemble smoother to improve the tidal boundary values so that the model represents more closely the observed currents. To create an ensemble of dynamically realistic boundary conditions, a cost function is formulated which is directly related to the probability of each boundary condition perturbation. This cost function ensures that the boundary condition perturbations are spatially smooth and that the structure of the perturbations satisfies approximately the harmonic linearized shallow water equations. Based on those perturbations an ensemble simulation is carried out using the full three-dimensional General Estuarine Ocean Model (GETM. Optimized boundary values are obtained by assimilating all observations using the covariances of the ensemble simulation.

  11. Statistical optimization for alkali pretreatment conditions of narrow-leaf cattail by response surface methodology

    Directory of Open Access Journals (Sweden)

    Arrisa Ruangmee

    2013-08-01

    Full Text Available Response surface methodology with central composite design was applied to optimize alkali pretreatment of narrow-leafcattail (Typha angustifolia. Joint effects of three independent variables; NaOH concentration (1-5%, temperature (60-100 ºC,and reaction time (30-150 min, were investigated to evaluate the increase in and the improvement of cellulosic componentscontained in the raw material after pretreatment. The combined optimum condition based on the cellulosic content obtainedfrom this study is: a concentration of 5% NaOH, a reaction time of 120 min, and a temperature of 100 ºC. This result has beenanalyzed employing ANOVA with a second order polynomial equation. The model was found to be significant and was able topredict accurately the response of strength at less than 5% error. Under this combined optimal condition, the desirable cellulosic content in the sample increased from 38.5 to 68.3%, while the unfavorable hemicellulosic content decreased from 37.6 to7.3%.

  12. Falls in Swedish hurdle and steeplechase racing and the condition of the track surface

    DEFF Research Database (Denmark)

    Gottlieb-Vedi, M.; Pipper, Christian Bressen

    2015-01-01

    Falls in National Hunt races is a tragic part of the sport. The present study focuses on the relation between racing track conditions and the number of falls in Swedish jump racing. The assumption was that more horses fell on heavy or soft going than on good or firm going. Results from all jump...... races at Täby Racecourse (1992-2001) were recorded. Parameters registered were: type and number of races, racing surface and condition, total time to finish the race, number of starting horses and number of falls. In this period 212 races, corresponding to 1,556 horse starts, were registered. Falls were...... registered in 42 races and in total 61 horses fell. The fall frequency on horse level was significantly higher in steeplechases than in hurdle races (odds ratio =3.69; 95% confidence interval (CI) = 1.99-6.85). For the steeplechases recorded in this study, significantly more falls were seen in long distance...

  13. Iodine isotopes species fingerprinting environmental conditions in surface water along the northeastern Atlantic Ocean

    DEFF Research Database (Denmark)

    He, Peng; Hou, Xiaolin; Aldahan, Ala

    2013-01-01

    Concentrations and species of iodine isotopes (127I and 129I) provide vital information about iodine geochemistry, environmental conditions and water masses exchange in oceans. Despite extensive investigations of anthropogenic 129I in the Arctic Ocean and the Nordic Seas, concentrations of the is...... 129I in ocean environments and impact on climate at the ocean boundary layer.......Concentrations and species of iodine isotopes (127I and 129I) provide vital information about iodine geochemistry, environmental conditions and water masses exchange in oceans. Despite extensive investigations of anthropogenic 129I in the Arctic Ocean and the Nordic Seas, concentrations...... of the isotope in the Atlantic Ocean are, however, still unknown. We here present first data on 129I and 127I, and their species (iodide and iodate) in surface water transect along the northeastern Atlantic between 30° and 50°N. The results show iodate as the predominant species in the analyzed marine waters...

  14. Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic: The effect of surface conditioning

    NARCIS (Netherlands)

    Amaral, R.; Ozcan, M.; Bottino, M.A.; Valandro, L.F.

    2006-01-01

    Objectives. This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Methods. Thirty blocks (5 x 5 x 4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR,

  15. Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic : The effect of surface conditioning

    NARCIS (Netherlands)

    Amaral, R; Ozcan, M; Bottino, MA; Valandro, LF

    Objectives. This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Methods. Thirty blocks (5 x 5 x 4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR,

  16. Morphological Analysis of Dentin Surface after Conditioning with Two Different methods: Chemical and Mechanical.

    Science.gov (United States)

    Rafael, Caroline Freitas; Quinelato, Valquíria; Morsch, Carolina Schaffer; DeDeus, Gustavo; Reis, Claudia Mendonca

    2016-01-01

    Alternative pretreatment strategies of dentin and adhesionare constantly being developed and studied with the goal of improving the adhesion of resin restorative materials with this tissue. The objectives of the present study were to evaluate the ability of airborne-particle abrasion (APA) with aluminum oxide on dentin to remove the smear layer and the effects produced on the dentin microstructure. The phosphoric acid (PA) was used for a comparison. For that, 20 human third molars were randomly allocated into two experimental groups, according to the dentin pretreatment method used: G1 (N = 10) - PA, G2 (N = 10) -APA. For dentin surface analyses, an environmental scanning electron microscope (ESEM) was employed to observe dentin surfaces before and after the procedures. Before pretreatment, the specimens of both groups were smear covered. After pretreatment, the G1 images revealed dentin tubule orifices opened, enlarged and some erosive effects. (G2) exposed tubule orifices without enlargement, but crack-like alterations were observed on the surfaces. In this way, APA with aluminum oxide was able to remove the smear layer. The influences of the dentin roughness on adhesion and the consequences on dentin integrity and hardness need further investigations. A good conditioning of the dentin before cementation is necessary in order to obtain a satisfactory rehabilitation in adhesive dentistry. So, it is necessary to know all methods to do it.

  17. Determination of Critical Conditions for Puncturing Almonds Using Coupled Response Surface Methodology and Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Mahmood Mahmoodi-Eshkaftaki

    2013-01-01

    Full Text Available In this study, the effect of seed moisture content, probe diameter and loading velocity (puncture conditions on some mechanical properties of almond kernel and peeled almond kernel is considered to model a relationship between the puncture conditions and rupture energy. Furthermore, distribution of the mechanical properties is determined. The main objective is to determine the critical values of mechanical properties significant for peeling machines. The response surface methodology was used to find the relationship between the input parameters and the output responses, and the fitness function was applied to measure the optimal values using the genetic algorithm. Two-parameter Weibull function was used to describe the distribution of mechanical properties. Based on the Weibull parameter values, i.e. shape parameter (β and scale parameter (η calculated for each property, the mechanical distribution variations were completely described and it was confirmed that the mechanical properties are rule governed, which makes the Weibull function suitable for estimating their distributions. The energy model estimated using response surface methodology shows that the mechanical properties relate exponentially to the moisture, and polynomially to the loading velocity and probe diameter, which enabled successful estimation of the rupture energy (R²=0.94. The genetic algorithm calculated the critical values of seed moisture, probe diameter, and loading velocity to be 18.11 % on dry mass basis, 0.79 mm, and 0.15 mm/min, respectively, and optimum rupture energy of 1.97·10-³ J. These conditions were used for comparison with new samples, where the rupture energy was experimentally measured to be 2.68 and 2.21·10-³ J for kernel and peeled kernel, respectively, which was nearly in agreement with our model results.

  18. Influence of Chatter of VMC Arising During End Milling Operation and Cutting Conditions on Quality of Machined Surface

    Directory of Open Access Journals (Sweden)

    A.K.M.N. Amin, M.A. Rizal, and M. Razman

    2012-08-01

    Full Text Available Machine tool chatter is a dynamic instability of the cutting process. Chatter results in poor part surface finish, damaged cutting tool, and an irritating and unacceptable noise. Exten¬sive research has been undertaken to study the mechanisms of chatter formation. Efforts have been also made to prevent the occurrence of chatter vibration. Even though some progress have been made, fundamental studies on the mechanics of metal cutting are necessary to achieve chatter free operation of CNC machine tools to maintain their smooth operating cycle. The same is also true for Vertical Machining Centres (VMC, which operate at high cutting speeds and are capable of offering high metal removal rates. The present work deals with the effect of work materials, cutting conditions and diameter of end mill cutters on the frequency-amplitude characteristics of chatter and on machined surface roughness. Vibration data were recorded using an experimental rig consisting of KISTLER 3-component dynamometer model 9257B, amplifier, scope meters and a PC.  Three different types of vibrations were observed. The first type was a low frequency vibration, associated with the interrupted nature of end mill operation. The second type of vibration was associated with the instability of the chip formation process and the third type was due to chatter. The frequency of the last type remained practically unchanged over a wide range of cutting speed.  It was further observed that chip-tool contact processes had considerable effect on the roughness of the machined surface.Key Words: Chatter, Cutting Conditions, Stable Cutting, Surface Roughness.

  19. Surface temperature and surface heat flux determination of the inverse heat conduction problem for a slab

    International Nuclear Information System (INIS)

    Kuroyanagi, Toshiyuki

    1983-07-01

    Based on an idea that surface conditions should be a reflection of interior temperature and interior heat flux variation as inverse as interior conditions has been determined completely by the surface temperature and/on surface heat flux as boundary conditions, a method is presented for determining the surface temperature and the surface heat flux of a solid when the temperature and heat flux at an interior point are a prescribed function of time. The method is developed by the integration of Duhumels' integral which has unknown temperature or unknown heat flux in its integrand. Specific forms of surface condition determination are developed for a sample inverse problem: slab. Ducussing the effect of a degree of avairable informations at an interior point due to damped system and the effect of variation of surface conditions on those formulations, it is shown that those formulations are capable of representing the unknown surface conditions except for small time interval followed by discontinuous change of surface conditions. The small un-resolved time interval is demonstrated by a numerical example. An evaluation method of heat flux at an interior point, which is requested by those formulations, is discussed. (author)

  20. Surface Characteristics of Machined NiTi Shape Memory Alloy: The Effects of Cryogenic Cooling and Preheating Conditions

    Science.gov (United States)

    Kaynak, Y.; Huang, B.; Karaca, H. E.; Jawahir, I. S.

    2017-07-01

    This experimental study focuses on the phase state and phase transformation response of the surface and subsurface of machined NiTi alloys. X-ray diffraction (XRD) analysis and differential scanning calorimeter techniques were utilized to measure the phase state and the transformation response of machined specimens, respectively. Specimens were machined under dry machining at ambient temperature, preheated conditions, and cryogenic cooling conditions at various cutting speeds. The findings from this research demonstrate that cryogenic machining substantially alters austenite finish temperature of martensitic NiTi alloy. Austenite finish ( A f) temperature shows more than 25 percent increase resulting from cryogenic machining compared with austenite finish temperature of as-received NiTi. Dry and preheated conditions do not substantially alter austenite finish temperature. XRD analysis shows that distinctive transformation from martensite to austenite occurs during machining process in all three conditions. Complete transformation from martensite to austenite is observed in dry cutting at all selected cutting speeds.

  1. Surface adsorption behaviour of milk whey protein and pectin mixtures under conditions of air-water interface saturation.

    Science.gov (United States)

    Perez, Adrián A; Sánchez, Cecilio Carrera; Patino, Juan M Rodríguez; Rubiolo, Amelia C; Santiago, Liliana G

    2011-07-01

    Milk whey proteins (MWP) and pectins (Ps) are biopolymer ingredients commonly used in the manufacture of colloidal food products. Therefore, knowledge of the interfacial characteristics of these biopolymers and their mixtures is very important for the design of food dispersion formulations (foams and/or emulsions). In this paper, we examine the adsorption and surface dilatational behaviour of MWP/Ps systems under conditions in which biopolymers can saturate the air-water interface on their own. Experiments were performed at constant temperature (20 °C), pH 7 and ionic strength 0.05 M. Two MWP samples, β-lactoglobulin (β-LG) and whey protein concentrate (WPC), and two Ps samples, low-methoxyl pectin (LMP) and high-methoxyl pectin (HMP) were evaluated. The contribution of biopolymers (MWP and Ps) to the interfacial properties of mixed systems was evaluated on the basis of their individual surface molecular characteristics. Biopolymer bulk concentration capable of saturating the air-water interface was estimated from surface pressure isotherms. Under conditions of interfacial saturation, dynamic adsorption behaviour (surface pressure and dilatational rheological characteristics) of MWP/Ps systems was discussed from a kinetic point of view, in terms of molecular diffusion, penetration and configurational rearrangement at the air-water interface. The main adsorption mechanism in MWP/LMP mixtures might be the MWP interfacial segregation due to the thermodynamic incompatibility between MWP and LMP (synergistic mechanism); while the interfacial adsorption in MWP/HMP mixtures could be characterized by a competitive mechanism between MWP and HMP at the air-water interface (antagonistic mechanism). The magnitude of these phenomena could be closely related to differences in molecular composition and/or aggregation state of MWP (β-LG and WPC). Copyright © 2011 Elsevier B.V. All rights reserved.

  2. A study on EUV reticle surface molecular contamination under different storage conditions in a HVM foundry fab

    Science.gov (United States)

    Singh, SherJang; Yatzor, Brett; Taylor, Ron; Wood, Obert; Mangat, Pawitter

    2017-03-01

    The prospect of EUVL (Extreme Ultraviolet Lithography) insertion into HVM (High Volume Manufacturing) has never been this promising. As technology is prepared for "lab to fab" transition, it becomes important to comprehend challenges associated with integrating EUVL infrastructure within existing high volume chip fabrication processes in a foundry fab. The existing 193nm optical lithography process flow for reticle handling and storage in a fab atmosphere is well established and in-fab reticle contamination concerns are mitigated with the reticle pellicle. However EUVL reticle pellicle is still under development and if available, may only provide protection against particles but not molecular contamination. HVM fab atmosphere is known to be contaminated with trace amounts of AMC's (Atmospheric Molecular Contamination). If such contaminants are organic in nature and get absorbed on the reticle surface, EUV photon cause photo-dissociation resulting into carbon generation which is known to reduce multilayer reflectivity and also degrades exposure uniformity. Chemical diffusion and aggregation of other ions is also reported under the e-beam exposure of a EUV reticle which is known to cause haze issues in optical lithography. Therefore it becomes paramount to mitigate absorbed molecular contaminant concerns on EUVL reticle surface. In this paper, we have studied types of molecular contaminants that are absorbed on an EUVL reticle surface under HVM fab storage and handling conditions. Effect of storage conditions (gas purged vs atmospheric) in different storage pods (Dual pods, Reticle Clamshells) is evaluated. Absorption analysis is done both on ruthenium capping layer as well as TaBN absorber. Ru surface chemistry change as a result of storage is also studied. The efficacy of different reticle cleaning processes to remove absorbed contaminant is evaluated as well.

  3. The bactericidal effect of surface micro-discharge plasma under different ambient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, T; Zimmermann, J L; Morfill, G E, E-mail: tshimizu@mpe.mpg.de [Max-Planck Institute for Extraterrestrial Physics, Giessenbachstr., 85748 Garching (Germany)

    2011-02-15

    A series of experiments on the bactericidal properties of plasmas using a surface micro-discharge (SMD) device in an atmosphere under different ambient temperatures and humidities was carried out. This plasma dispenser was developed for use as a disinfection system in private and public places (hospitals, medical practices, etc). The bactericidal effect is due to the interplay of the plasma and the chemical products produced via interactions with O{sub 2}/N{sub 2} and H{sub 2}O vapour in air. To use this device in different countries and therefore under various ambient conditions, it is important to understand its behaviour and efficiency, especially with respect to air temperature and humidity. The experimental results obtained in this study show that the bactericidal properties of the SMD plasma dispenser are not sensitive to the different temperatures and humidities.

  4. Utility of remote sensing-based surface energy balance models to track water stress in rain-fed switchgrass under dry and wet conditions

    Science.gov (United States)

    Bhattarai, Nishan; Wagle, Pradeep; Gowda, Prasanna H.; Kakani, Vijaya G.

    2017-11-01

    The ability of remote sensing-based surface energy balance (SEB) models to track water stress in rain-fed switchgrass (Panicum virgatum L.) has not been explored yet. In this paper, the theoretical framework of crop water stress index (CWSI; 0 = extremely wet or no water stress condition and 1 = extremely dry or no transpiration) was utilized to estimate CWSI in rain-fed switchgrass using Landsat-derived evapotranspiration (ET) from five remote sensing based single-source SEB models, namely Surface Energy Balance Algorithm for Land (SEBAL), Mapping ET with Internalized Calibration (METRIC), Surface Energy Balance System (SEBS), Simplified Surface Energy Balance Index (S-SEBI), and Operational Simplified Surface Energy Balance (SSEBop). CWSI estimates from the five SEB models and a simple regression model that used normalized difference vegetation index (NDVI), near-surface temperature difference, and measured soil moisture (SM) as covariates were compared with those derived from eddy covariance measured ET (CWSIEC) for the 32 Landsat image acquisition dates during the 2011 (dry) and 2013 (wet) growing seasons. Results indicate that most SEB models can predict CWSI reasonably well. For example, the root mean square error (RMSE) ranged from 0.14 (SEBAL) to 0.29 (SSEBop) and the coefficient of determination (R2) ranged from 0.25 (SSEBop) to 0.72 (SEBAL), justifying the added complexity in CWSI modeling as compared to results from the simple regression model (R2 = 0.55, RMSE = 0.16). All SEB models underestimated CWSI in the dry year but the estimates from SEBAL and S-SEBI were within 7% of the mean CWSIEC and explained over 60% of variations in CWSIEC. In the wet year, S-SEBI mostly overestimated CWSI (around 28%), while estimates from METRIC, SEBAL, SEBS, and SSEBop were within 8% of the mean CWSIEC. Overall, SEBAL was the most robust model under all conditions followed by METRIC, whose performance was slightly worse and better than SEBAL in dry and wet years

  5. OPTIMIZATION OF SESAME SEEDS OIL EXTRACTION OPERATING CONDITIONS USING THE RESPONSE SURFACE DESIGN METHODOLOGY

    Directory of Open Access Journals (Sweden)

    HAITHAM OSMAN

    2016-12-01

    Full Text Available This paper applies Response Surface Design (RSD to model the experimental data obtained from the extraction of sesame seeds oil using n-hexane, chloroform and acetone as solvents under different operating conditions. The results obtained revealed that n-hexane outperformed the extraction obtained using chloroform and acetone. The developed model predicted that n-hexane with a rotational speed of 547 rpm and a contact time between the solvent and seeds of 19.46 hours with solvent: seeds ratio of 4.93, yields the optimum oil extracted of 37.03 %, outperforming chloroform and acetone models that gave prediction for 4.75 and 4.21 respectively. While the maximum predictions yield for chloroform is 6.73 %, under the operating conditions of 602 rpm, and 24 hours contact time, with a ratio of solvent: seeds of 1.74. On the other hand the acetone maximum prediction is only 4.37 %, with operational conditions of 467 rpm, and 6.00 hours contact time, with a ratio of solvent: seeds of 1. It is has been found that the maximum oil extraction yield obtained from the chloroform (6.73 % and Acetone (4.37 % is much lower than that predicted by n-hexane 37.03 %.

  6. Analysis of the influence of process conditions on the surface finish of ceramic materials manufactured by EDM

    International Nuclear Information System (INIS)

    Puertas-Arbizu, I.; Luis-Perez, C. J.

    2004-01-01

    Electrical discharge machining (EDM) is an emerging alternative versus some other manufacturing processes of conductive ceramic materials, such as: laser machining, electrochemical machining, abrasive water jet, ultrasonic machining and diamond wheel grinding. Due to its interest in the industrial field, in this work a study of the influence of process conditions on the surface aspect of three conductive ceramic materials: hot-pressed boron carbide (B 4 C), reaction-bonded silicon carbide (SiSiC) and cobalt-bonded tungsten carbide (WC-Co) is carried out. These materials are to be electrical discharge machined under different machining conditions and in the particular case of finish stages (Ra≤ 1 μm). (Author)

  7. Radionuclide transfer onto ground surface in surface water flow, 1

    International Nuclear Information System (INIS)

    Mukai, Masayuki; Takebe, Shinichi; Komiya, Tomokazu; Kamiyama, Hideo

    1991-07-01

    Radionuclides migration in ground surface water flow is considered to be one of the important path way in the scenario for environmental migration of radionuclides leaked from low level radioactive waste repository. Simulating the slightly sloped surface on which contaminated solution is flowing downward, testing for radionuclide migration on ground surface had been started. As it's first step, an experiment was carried out under the condition of restricted infiltration in order to elucidate the adsorption behavior of radionuclides onto the loamy soil surface in related with hydraulic conditions. Radionuclides concentration change in effluent solution with time and a concentration distribution of radionuclides adsorbed on the ground surface were obtained from several experimental conditions combining the rate and the duration time of the water flow. The radionuclides concentration in the effluent solution was nearly constant during each experimental period, and was reduced under the condition of lower flow rate. The surface distribution of radionuclides concentration showed two distinctive regions. The one was near the inlet vessel where the concentration was promptly reducing, and the other was following the former where the concentration was nearly constant. The characteristic surface distribution of radionuclides concentration can be explained by a two dimensional diffusion model with a first order adsorption reaction, based on the advection of flow rate distribution in perpendicular direction. (author)

  8. Surface grafting of poly(ethylene glycol) onto poly(acrylamide-co-vinyl amine) cross-linked films under mild conditions.

    Science.gov (United States)

    Yamamoto, Y; Sefton, M V

    1998-01-01

    Poly(ethylene glycol) (PEG) was grafted onto poly(acrylamide-co-vinyl amine) (poly(AM-co-VA)) film using tresylated PEG (TPEG) at 37 degrees C in aqueous buffers (pH 7.4) with a view to surface-modifying microencapsulated mammalian cells. Poly(AM-co-VA) film was synthesized by Hofmann degradation of a cross-linked poly(acrylamide) film. Conversion to vinyl amine on the surface of the film was approximately 50%, but bulk conversion was not observed; surface specificity was thought to be the result of cleavage of aminated polymer chains at the surface due to chain scission. Reaction between primary amine and TPEG gave a graft yield of 2 mol% (based on XPS) with respect to available surface amine groups, equivalent to 54 mol% ethylene oxide based on monomer units. Physical adsorption of non-activated polymer was done under identical conditions as a control and the difference in oxygen content was significant compared to TPEG. The type of buffer agent and buffer concentration did not influence graft yields. This graft reaction, which was completed in as little as 2 h was considered to be mild enough to be used for a surface modification of microcapsules containing cells without affecting their viability. Such a surface modification technique may prove to be a useful means of enhancing the biocompatibility of microcapsules (or any tissue engineering construct) even after cell encapsulation or seeding.

  9. Extremal surface barriers

    International Nuclear Information System (INIS)

    Engelhardt, Netta; Wall, Aron C.

    2014-01-01

    We present a generic condition for Lorentzian manifolds to have a barrier that limits the reach of boundary-anchored extremal surfaces of arbitrary dimension. We show that any surface with nonpositive extrinsic curvature is a barrier, in the sense that extremal surfaces cannot be continuously deformed past it. Furthermore, the outermost barrier surface has nonnegative extrinsic curvature. Under certain conditions, we show that the existence of trapped surfaces implies a barrier, and conversely. In the context of AdS/CFT, these barriers imply that it is impossible to reconstruct the entire bulk using extremal surfaces. We comment on the implications for the firewall controversy

  10. Extended survival of several organisms and amino acids under simulated martian surface conditions

    Science.gov (United States)

    Johnson, A. P.; Pratt, L. M.; Vishnivetskaya, T.; Pfiffner, S.; Bryan, R. A.; Dadachova, E.; Whyte, L.; Radtke, K.; Chan, E.; Tronick, S.; Borgonie, G.; Mancinelli, R. L.; Rothschild, L. J.; Rogoff, D. A.; Horikawa, D. D.; Onstott, T. C.

    2011-02-01

    Recent orbital and landed missions have provided substantial evidence for ancient liquid water on the martian surface as well as evidence of more recent sedimentary deposits formed by water and/or ice. These observations raise serious questions regarding an independent origin and evolution of life on Mars. Future missions seek to identify signs of extinct martian biota in the form of biomarkers or morphological characteristics, but the inherent danger of spacecraft-borne terrestrial life makes the possibility of forward contamination a serious threat not only to the life detection experiments, but also to any extant martian ecosystem. A variety of cold and desiccation-tolerant organisms were exposed to 40 days of simulated martian surface conditions while embedded within several centimeters of regolith simulant in order to ascertain the plausibility of such organisms' survival as a function of environmental parameters and burial depth. Relevant amino acid biomarkers associated with terrestrial life were also analyzed in order to understand the feasibility of detecting chemical evidence for previous biological activity. Results indicate that stresses due to desiccation and oxidation were the primary deterrent to organism survival, and that the effects of UV-associated damage, diurnal temperature variations, and reactive atmospheric species were minimal. Organisms with resistance to desiccation and radiation environments showed increased levels of survival after the experiment compared to organisms characterized as psychrotolerant. Amino acid analysis indicated the presence of an oxidation mechanism that migrated downward through the samples during the course of the experiment and likely represents the formation of various oxidizing species at mineral surfaces as water vapor diffused through the regolith. Current sterilization protocols may specifically select for organisms best adapted to survival at the martian surface, namely species that show tolerance to radical

  11. Spheroidal and toroidal configurations as sources of the Kerr metric. Pt. 1. A kinematical approach. [Boyer surface condition, singularity

    Energy Technology Data Exchange (ETDEWEB)

    de Felice, F; Nobili, L [Padua Univ. (Italy). Istituto di Fisica; Calvani, M [Padua univ. (Italy). Istituto di Astronomia

    1976-03-01

    The existence of extended Kerr metric sources of perfect fluid is taken as work-hypothesis to investigate the structure of the boundaries which derive from Boyer's surface condition. We find closed spheroidal configurations which hide an internal cavity as well as toroidal configurations; however, both the boundary of the internal cavity and the tori touch the ring singularity. We judge this feature non-physical and conclude that Boyer's condition is not sufficient to completely define a well behaved physical source.

  12. Effects of surface conditioning on repair bond strengths of non-aged and aged microhybrid, nanohybrid, and nanofilled composite resins

    NARCIS (Netherlands)

    Rinastiti, Margareta; Siswomihardjo, Widowati; Busscher, Henk J.; Ozcan, Mutlu

    2011-01-01

    This study evaluates effects of aging on repair bond strengths of microhybrid, nanohybrid, and nanofilled composite resins and characterizes the interacting surfaces after aging. Disk-shaped composite specimens were assigned to one of three aging conditions: (1) thermocycling (5,000x, 5-55 degrees

  13. Creep of MDF panels under constant load and cyclic environmental conditions. Influence of surface coating

    OpenAIRE

    Fernández-Golfín Seco, J. I.; Díez Barra, M. Rafael

    1997-01-01

    Four different strategies of surface coating (based on 80 g m2 melamin impregnated papers) were used on 19 mm thick commercial MDF panels to assess its reological behaviour under cyclic humidity conditions (20ºC 30 % rh-20ºC 90 % rh). Three different levels of stress (20 %, 30 % and 40 %), based on the ultimate load in bending, were used. Tests were conducted by means of the three points load system. For the same stress level, the relative creep of MDF panels was higher than that in par...

  14. Thermophysical Properties Measurement of High-Temperature Liquids Under Microgravity Conditions in Controlled Atmospheric Conditions

    Science.gov (United States)

    Watanabe, Masahito; Ozawa, Shumpei; Mizuno, Akotoshi; Hibiya, Taketoshi; Kawauchi, Hiroya; Murai, Kentaro; Takahashi, Suguru

    2012-01-01

    Microgravity conditions have advantages of measurement of surface tension and viscosity of metallic liquids by the oscillating drop method with an electromagnetic levitation (EML) device. Thus, we are preparing the experiments of thermophysical properties measurements using the Materials-Science Laboratories ElectroMagnetic-Levitator (MSL-EML) facilities in the international Space station (ISS). Recently, it has been identified that dependence of surface tension on oxygen partial pressure (Po2) must be considered for industrial application of surface tension values. Effect of Po2 on surface tension would apparently change viscosity from the damping oscillation model. Therefore, surface tension and viscosity must be measured simultaneously in the same atmospheric conditions. Moreover, effect of the electromagnetic force (EMF) on the surface oscillations must be clarified to obtain the ideal surface oscillation because the EMF works as the external force on the oscillating liquid droplets, so extensive EMF makes apparently the viscosity values large. In our group, using the parabolic flight levitation experimental facilities (PFLEX) the effect of Po2 and external EMF on surface oscillation of levitated liquid droplets was systematically investigated for the precise measurements of surface tension and viscosity of high temperature liquids for future ISS experiments. We performed the observation of surface oscillations of levitated liquid alloys using PFLEX on board flight experiments by Gulfstream II (G-II) airplane operated by DAS. These observations were performed under the controlled Po2 and also under the suitable EMF conditions. In these experiments, we obtained the density, the viscosity and the surface tension values of liquid Cu. From these results, we discuss about as same as reported data, and also obtained the difference of surface oscillations with the change of the EMF conditions.

  15. The effects of processing conditions on the surface morphology and hydrophobicity of polyvinylidene fluoride membranes prepared via vapor-induced phase separation

    Science.gov (United States)

    Peng, Yuelian; Fan, Hongwei; Ge, Ju; Wang, Shaobin; Chen, Ping; Jiang, Qi

    2012-12-01

    The present investigation reveals how the surface morphology and the hydrophobicity of polyvinylidene fluoride (PVDF) membranes, which were prepared via a vapor-induced phase separation method, were affected by the initial PVDF content in the casting solution and the air temperature. The surface morphology was characterized with scanning electron microscopy. A ternary phase diagram of PVDF/N, N-dimethylacetamide/water was constructed to explain the formation mechanism of the different morphologies. The results show that different membrane morphologies and hydrophobicities can be obtained by changing the processing conditions. Low air temperature and high PVDF contents facilitate the crystallization process, resulting in the formation of a porous skin and particle morphology, which increases the hydrophobicity of the surface. High air temperature and low PVDF contents are favorable for the formation of a net-like surface morphology via spinodal decomposition and lead to a superhydrophobic surface. Theoretical calculations were performed to testify that the net-like surface was more favorable for superhydrophobicity than the particle-based surface.

  16. "The Effects of Mixing Offenders with Non-Offenders: Findings from a Danish Quasi Experiment"

    DEFF Research Database (Denmark)

    Kjær Minke, Linda

    2011-01-01

    This study examines the effects of mixing offenders with nonoffenders at Skejby half-way house in Denmark. Skejby halfway house constitutes an outstanding social experiment, as offenders are deliberately mixed with non-offenders in order to reduce their risk of recidivism. The treatment group...

  17. Time-Resolved Analysis of Cytosolic and Surface-Associated Proteins of Staphylococcus aureus HG001 under Planktonic and Biofilm Conditions.

    Science.gov (United States)

    Moche, Martin; Schlüter, Rabea; Bernhardt, Jörg; Plate, Kristina; Riedel, Katharina; Hecker, Michael; Becher, Dörte

    2015-09-04

    Staphylococcal biofilms are associated with persistent infections due to their capacity to protect bacteria against the host's immune system and antibiotics. Cell-surface-associated proteins are of great importance during biofilm formation. In the present study, an optimized biotinylation approach for quantitative GeLC-MS-based analysis of the staphylococcal cell-surface proteome was applied and the cytoplasmic protein fraction was analyzed to elucidate proteomic differences between colony biofilms and planktonic cells. The experimental setup enabled a time-resolved monitoring of the proteome under both culture conditions and the comparison of biofilm cells to planktonic cells at several time points. This allowed discrimination of differences attributed to delayed growth phases from responses provoked by biofilm conditions. Biofilm cells expressed CcpA-dependent catabolic proteins earlier than planktonic cells and strongly accumulated proteins that belong to the SigB stress regulon. The amount of the cell-surface protein and virulence gene regulator Rot decreased within biofilms and MgrA-dependent regulations appeared more pronounced. Biofilm cells simultaneously up-regulated activators (e.g., SarZ) as well as repressors (e.g., SarX) of RNAIII. A decreased amount of high-affinity iron uptake systems and an increased amount of the iron-storage protein FtnA possibly indicated a lower demand of iron in biofilms.

  18. Characterization of the parameters at the origin of the chemical species hideout process at the fuel rod surface in boiling conditions

    International Nuclear Information System (INIS)

    Peybernes, J.; March, P.

    1999-01-01

    Current trends in nuclear power generation (and particularly in pressurized water reactors) are toward plant life extension and extended fuel burnup. A higher heat generation rate can induce local boiling regimes at the fuel rod surface in the hottest channels of the core, which can strongly modify the chemical environment of the cladding and influence the oxidation rate of zirconium alloys. Tests performed in out-of-pile loops under severe chemical and thermal-hydraulic conditions (nucleate boiling, higher lithium contents compared to PWRs) reveal two important phenomena: an increase of the oxidation rate of Zircaloy-4 cladding materials in 'high' lithiated environments; an enrichment of the chemical additives in the primary water (boron, lithium) at the surface of the cladding under nucleate boiling conditions. The latter phenomenon, also called 'hideout effect', is mainly controlled by some thermal hydraulic parameters such as bubble diameters and nucleation site density. These parameters strongly depend on the oxide morphology (roughness, porosity). The lack of reliable data in high temperature water environments has led to the development of a specific instrumentation based on visualization. The fitting of windows on the REGGAE out-of-pile loop provides an optical access to the two-phase flow regime under PWR operating conditions, allowing for the characterization of the parameters at the origin of the chemical species hideout process. These direct observations of the cladding surfaces subjected to nucleate boiling conditions provide information about the development of the boiling mechanisms in relation to the morphology of the oxide layers (porosity, thickness, roughness). (author)

  19. Analytical solution describing pesticide volatilization from soil affected by a change in surface condition.

    Science.gov (United States)

    Yates, S R

    2009-01-01

    An analytical solution describing the fate and transport of pesticides applied to soils has been developed. Two pesticide application methods can be simulated: point-source applications, such as idealized shank or a hot-gas injection method, and a more realistic shank-source application method that includes a vertical pesticide distribution in the soil domain due to a soil fracture caused by a shank. The solutions allow determination of the volatilization rate and other information that could be important for understanding fumigant movement and in the development of regulatory permitting conditions. The solutions can be used to characterize differences in emissions relative to changes in the soil degradation rate, surface barrier conditions, application depth, and soil packing. In some cases, simple algebraic expressions are provided that can be used to obtain the total emissions and total soil degradation. The solutions provide a consistent methodology for determining the total emissions and can be used with other information, such as field and laboratory experimental data, to support the development of fumigant regulations. The uses of the models are illustrated by several examples.

  20. OPTIMIZATION OF MICROWAVE AND AIR DRYING CONDITIONS OF QUINCE (CYDONIA OBLONGA, MILLER USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Cem Baltacioglu

    2015-03-01

    Full Text Available Effects of slice thickness of quince (Cydonia oblonga Miller , microwave incident power and air drying temperature on antioxidant activity and total phenolic content of quince were investigated during drying in microwave and air drying. Optimum conditions were found to be: i for microwave drying, 285 W and 4.14 mm thick (maximum antioxidant activity and 285 W and 6.85 mm thick (maximum total phenolic content, and ii for air drying, 75 ºC and 1.2 mm thick (both maximum antioxidant activity and total phenolic content. Drying conditions were optimized by using the response surface methodology. 13 experiments were carried out considering incident microwave powers from 285 to 795 W, air temperature from 46 to 74 ºC and slice thickness from 1.2 to 6.8 mm.

  1. Surface (glyco-)proteins: primary structure and crystallization under microgravity conditions

    Science.gov (United States)

    Claus, H.; Akca, E.; Schultz, N.; Karbach, G.; Schlott, B.; Debaerdemaeker, T.; De Clercq, J.-P.; König, H.

    2001-08-01

    The Archaea comprise microorganisms that live under environmental extremes, like high temperature, low pH value or high salt concentration. Their cells are often covered by a single layer of (glyco)protein subunits (S-layer) in hexagonal arrangement. In order to get further hints about the molecular mechanisms of protein stabilization we compared the primary and secondary structures of archaeal S-layer (glyco)proteins. We found an increase of charged amino acids in the S-layer proteins of the extreme thermophilic species compared to their mesophilic counterparts. Our data and those of other authors suggest that ionic interactions, e.g., salt bridges seem to be played a major role in protein stabilization at high temperatures. Despite the differences in the growth optima and the predominance of some amino acids the primary structures of S-layers revealed also a significant degree of identity between phylogenetically related archaea. These obervations indicate that protein sequences of S-layers have been conserved during the evolution from extremely thermophilic to mesophilic life. To support these findings the three-dimensional structure of the S-layer proteins has to be elucidated. Recently, we described the first successful crystallization of an extreme thermophilic surface(glyco)protein under microgravity conditions.

  2. Effect of SUS316L stainless steel surface conditions on the wetting of molten multi-component oxides ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jin, E-mail: wangjinustb@gmail.com [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Matsuda, Nozomu [Bar and Wire Product Unit, Nippon steel and Sumitomo Metal Corporation, Fukuoka, 802-8686 (Japan); Shinozaki, Nobuya [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Miyoshi, Noriko [The Center for Instrumental Analysis, Kyushu Institute of Technology, Fukuoka, 804-8550 (Japan); Shiraishi, Takanobu [Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588 (Japan)

    2015-02-01

    Highlights: • Multi-component oxides had a good wetting on stainless substrates with pretreatments. • Various substrates surface roughness caused the difference of final contact angles. • The wetting rate was slow on polished substrate due to the slow surface oxidation. - Abstract: A study on the effect of SUS316L stainless steel surface conditions on the wetting behavior of molten multi-component oxides ceramic was performed and aimed to contribute to the further understanding of the application of oxides ceramic in penetration treatment of stainless steel coatings and the deposition of stainless steel cermet coatings. The results show that at 1273 K, different surface pre-treatments (polishing and heating) had an important effect on the wetting behavior. The molten multi-component oxides showed good wettability on both stainless steel substrates, however, the wetting process on the polished substrate was significantly slower than that on the heated substrates. The mechanism of the interfacial reactions was discussed based on the microscopic and thermodynamic analysis, the substrates reacted with oxygen generated from the decomposition of the molten multi-component oxides and oxygen contained in the argon atmosphere, and the oxide film caused the molten multi-component oxides ceramic to spread on the substrates surfaces. For the polished substrate, more time was required for the surface oxidation to reach the surface composition of Heated-S, which resulted in relatively slow spreading and wetting rates. Moreover, the variance of the surface roughness drove the final contact angles to slightly different values following the sequence Polished-S > Heated-S.

  3. Surface-rain interactions: differences in copper runoff for copper sheet of different inclination, orientation, and atmospheric exposure conditions.

    Science.gov (United States)

    Hedberg, Yolanda S; Goidanich, Sara; Herting, Gunilla; Wallinder, Inger Odnevall

    2015-01-01

    Predictions of the diffuse dispersion of metals from outdoor constructions such as roofs and facades are necessary for environmental risk assessment and management. An existing predictive model has been compared with measured data of copper runoff from copper sheets exposed at four different inclinations facing four orientations at two different urban sites (Stockholm, Sweden, and Milan, Italy) during a 4-year period. Its applicability has also been investigated for copper sheet exposed at two marine sites(Cadiz, Spain, for 5 years, and Brest, France, for 9 years). Generally the model can be used for all given conditions. However, vertical surfaces should be considered as surfaces inclined 60-80 due to wind driven effects. The most important parameters that influence copper runoff, and not already included in the model, are the wind and rain characteristics that influence the actual rainfall volume impinging the surface of interest.

  4. Theoretical study on the interactions between chlordecone hydrate and acidic surface groups of activated carbon under basic pH conditions.

    Science.gov (United States)

    Melchor-Rodríguez, Kenia; Gamboa-Carballo, Juan José; Ferino-Pérez, Anthuan; Passé-Coutrin, Nady; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2018-05-01

    A theoretical study of the influence of acidic surface groups (SG) of activated carbon (AC) on chlordecone hydrate (CLDh) adsorption is presented, in order to help understanding the adsorption process under basic pH conditions. A seven rings aromatic system (coronene) with a functional group in the edge was used as a simplified model of AC to evaluate the influence of SG in the course of adsorption from aqueous solution at basic pH conditions. Two SG were modeled in their deprotonated form: carboxyl and hydroxyl (COO - and O - ), interacting with CLDh. In order to model the solvation process, all systems under study were calculated with up to three water molecules. Multiple Minima Hypersurface (MMH) methodology was employed to study the interactions of CLDh with SG on AC using PM7 semiempirical Hamiltonian, to explore the potential energy surfaces of the systems and evaluate their thermodynamic association energies. The re-optimization of representative structures obtained from MMH was done using M06-2X Density Functional Theory. The Quantum Theory of Atoms in Molecules (QTAIM) was used to characterize the interaction types. As result, the association of CLDh with acidic SG at basic pH conditions preferentially occurs between the two alcohol groups of CLDh with COO - and O - groups and by dispersive interactions of chlorine atoms of CLDh with the graphitic surface. On the other hand, the presence of covalent interactions between the negatively charged oxygen of SG and one hydrogen atom of CLDh alcohol groups (O - ⋯HO interactions) without water molecules, was confirmed by QTAIM study. It can be concluded that the interactions of CLDh with acidic SG of AC under basic pH conditions confirms the physical mechanisms of adsorption process. Copyright © 2018 Elsevier Inc. All rights reserved.

  5. Lithium Wall Conditioning And Surface Dust Detection On NSTX

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  6. Transversal Surfaces of Timelike Ruled Surfaces in Minkowski 3-Space

    OpenAIRE

    Önder, Mehmet

    2012-01-01

    In this study we give definitions and characterizations of transversal surfaces of timelike ruled surfaces. We study some special cases such as the striction curve is a geodesic, an asymptotic line or a line of curvature. Moreover, we obtain developable conditions for transversal surfaces of a timelike ruled surface.

  7. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated Mars surface UV radiation conditions

    Science.gov (United States)

    Poch, Olivier; Dequaire, Tristan; Stalport, Fabien; Jaber, Maguy; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-04-01

    The search for organic carbon-containing molecules at the surface of Mars, as clues of past habitability or remnants of life, is a major scientific goal for Mars exploration. Several lines of evidence, including the detection of phyllosilicates, suggest that early Mars offered favorable conditions for long-term sustaining of water. As a consequence, we can assume that in those days, endogenous chemical processes, or even primitive life, may have produced organic matter on Mars. Moreover, exogenous delivery from small bodies or dust particles is likely to have brought fresh organic molecules to the surface of Mars up today. Organic matter is therefore expected to be present at the surface/subsurface of the planet. But the current environmental conditions at the surface - UV radiation, oxidants and energetic particles - generate physico-chemical processes that may affect organic molecules. On the other hand, on Earth, phyllosilicates are known to accumulate and preserve organic matter. But are phyllosilicates efficient at preserving organic molecules under the current environmental conditions at the surface of Mars? We have monitored the qualitative and quantitative evolutions of glycine, urea and adenine interacting with the Fe3+-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) in a laboratory simulation setup. We have tested organic-rich samples which may be representative of the evaporation of a warm little pond of liquid water having concentrated organics on Mars. For each molecule, we have observed how the nontronite influences the quantum efficiency of its photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine: their efficiencies of photodecomposition are reduced by a factor

  8. Symmetry conditions of a nodal superconductor for generating robust flat-band Andreev bound states at its dirty surface

    Science.gov (United States)

    Ikegaya, Satoshi; Kobayashi, Shingo; Asano, Yasuhiro

    2018-05-01

    We discuss the symmetry property of a nodal superconductor that hosts robust flat-band zero-energy states at its surface under potential disorder. Such robust zero-energy states are known to induce the anomalous proximity effect in a dirty normal metal attached to a superconductor. A recent study has shown that a topological index NZES describes the number of zero-energy states at the dirty surface of a p -wave superconductor. We generalize the theory to clarify the conditions required for a superconductor that enables NZES≠0 . Our results show that NZES≠0 is realized in a topological material that belongs to either the BDI or CII class. We also present two realistic Hamiltonians that result in NZES≠0 .

  9. Model development and optimization of operating conditions to maximize PEMFC performance by response surface methodology

    International Nuclear Information System (INIS)

    Kanani, Homayoon; Shams, Mehrzad; Hasheminasab, Mohammadreza; Bozorgnezhad, Ali

    2015-01-01

    Highlights: • The optimization of the operating parameters in a serpentine PEMFC is done using RSM. • The RSM model can predict the cell power over the wide range of operating conditions. • St-An, St-Ca and RH-Ca have an optimum value to obtain the best performance. • The interactions of the operating conditions affect the output power significantly. • The cathode and anode stoichiometry are the most effective parameters on the power. - Abstract: Optimization of operating conditions to obtain maximum power in PEMFCs could have a significant role to reduce the costs of this emerging technology. In the present experimental study, a single serpentine PEMFC is used to investigate the effects of operating conditions on the electrical power production of the cell. Four significant parameters including cathode stoichiometry, anode stoichiometry, gases inlet temperature, and cathode relative humidity are studied using Design of Experiment (DOE) to obtain an optimal power. Central composite second order Response Surface Methodology (RSM) is used to model the relationship between goal function (power) and considered input parameters (operating conditions). Using this statistical–mathematical method leads to obtain a second-order equation for the cell power. This model considers interactions and quadratic effects of different operating conditions and predicts the maximum or minimum power production over the entire working range of the parameters. In this range, high stoichiometry of cathode and low stoichiometry of anode results in the minimum cell power and contrary the medium range of fuel and oxidant stoichiometry leads to the maximum power. Results show that there is an optimum value for the anode stoichiometry, cathode stoichiometry and relative humidity to reach the best performance. The predictions of the model are evaluated by experimental tests and they are in a good agreement for different ranges of the parameters

  10. Impact of environmental conditions on sub-surface storage tanks ...

    African Journals Online (AJOL)

    Cast iron made storage tanks with gasoline fluid were buried under the soil at a depth of 4 m under various environment conditions. The simulated conditions include natural rain fail, temperature and acidic, alkaline and neutral soils. A control condition of neutral sea sand as base and filling materials were also investigated.

  11. Evaluation of two transport aircraft and several ground test vehicle friction measurements obtained for various runway surface types and conditions. A summary of test results from joint FAA/NASA Runway Friction Program

    Science.gov (United States)

    Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

    1990-01-01

    Tests with specially instrumented NASA Boeing 737 and 727 aircraft together with several different ground friction measuring devices were conducted for a variety of runway surface types and conditions. These tests are part of joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow and ice-covered runway conditions is discussed as well as ground vehicle friction data obtained under similar runway conditions. For a given contaminated runway surface condition, the correlation between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, type and amount of surface contaminant, and ambient temperature are discussed. The effect of surface type on wet friction levels is also evaluated from comparative data collected on grooved and ungrooved concrete and asphalt surfaces.

  12. Effect of road surfacing condition on tyre life

    CSIR Research Space (South Africa)

    Steyn, WJvdM

    2005-07-01

    Full Text Available simple patching of potholes and sealing of cracks to a reseal of the road or even recycling and rehabilitation of the failed sections of the road. These maintenance actions affect the surfacing of the road and therefore the experience of the tyre...

  13. An Introduction to an International Logistics Language.

    Science.gov (United States)

    1982-09-01

    cause difficulties for beginners as well as the professional in Systems and Logistics. 3. The author uses terms, acronyms, and abbreviations that are...guarantee flow guide flowchart fly -H focal fold had follow half Follow-on Support halfway follow-up handbook for handle force hang forecast hanger...surface flow (n)(v) - the direction of movement; to move in a con- tinuous speed flowchart (n) - a diagram which shows step by step procedures or

  14. Effects of moisture conditions of dental enamel surface on bond strength of brackets bonded with moisture-insensitive primer adhesive system.

    Science.gov (United States)

    Endo, Toshiya; Ozoe, Rieko; Sanpei, Sugako; Shinkai, Koichi; Katoh, Yoshiroh; Shimooka, Shohachi

    2008-07-01

    The purposes of this study were to evaluate the effects of different degrees of water contamination on the shear bond strength of orthodontic brackets bonded to dental enamel with a moisture-insensitive primer (MIP) adhesive system and to compare the modes of bracket/adhesive failure. A total of 68 human premolars were divided into four groups by primers and enamel surface conditions (desiccated, blot dry, and overwet). In group I, the hydrophobic Transbond XT primer adhesive system was used under desiccated conditions for bonding the brackets; in group II, the hydrophilic Transbond MIP adhesive system was used under desiccated conditions; in group III, the hydrophilic Transbond MIP adhesive system was used under blot dry conditions; and in group IV, the hydrophilic Transbond MIP adhesive system was used under overwet conditions. Shear bond strength was measured with a universal testing machine, and the mode of bracket/adhesive failure was determined according to the adhesive remnant index. The mean shear bond strengths were not significantly different among groups I, II, and III, and were higher than the clinically required range of 6 to 8 MPa. The mean shear bond strength achieved in group IV was significantly lower than that achieved in groups I, II, and III, and also lower than the clinically required values. Bond failure occurred at the enamel-adhesive interface more frequently in group IV than in groups I and III. To achieve clinically sufficient bond strengths with the hydrophilic MIP adhesive system, excess water should be blotted from the water-contaminated enamel surface.

  15. CONDITIONS FOR STABLE CHIP BREAKING AND PROVISION OF MACHINED SURFACE QUALITY WHILE TURNING WITH ASYMMETRIC TOOL VIBRATIONS

    Directory of Open Access Journals (Sweden)

    V. K. Sheleh

    2015-01-01

    Full Text Available The paper considers a process of turning structural steel with asymmetric tool vibrations directed along feeding. Asymmetric vibrations characterized by asymmetry coefficient of vibration cycle, their frequency and amplitude are additionally transferred to the tool in the turning process with the purpose to crush chips. Conditions of stable chip breaking and obtaining optimum dimensions of chip elements have been determined in the paper. In order to reduce a negative impact of the vibration amplitude on a cutting process and quality of the machined surfaces machining must be carried out with its minimum value. In this case certain ratio of the tool vibration frequency to the work-piece rotation speed has been ensured in the paper. A formula has been obtained for calculation of this ratio with due account of the expected length of chip elements and coefficient of vibration cycle asymmetry.Influence of the asymmetric coefficient of the tool vibration cycle on roughness of the machined surfaces and cutting tool wear has been determined in the paper. According to the results pertaining to machining of work-pieces made of 45 and ШХ15 steel the paper presents mathematical relationships of machined surface roughness with cutting modes and asymmetry coefficient of tool vibration cycle. Tool feeding being one of the cutting modes exerts the most significant impact on the roughness value and increase of the tool feeding entails increase in roughness. Reduction in coefficient of vibration cycle asymmetry contributes to surface roughness reduction. However, the cutting tool wear occurs more intensive. Coefficient of the vibration cycle asymmetry must be increased in order to reduce wear rate. Therefore, the choice of the coefficient of the vibration cycle asymmetry is based on the parameters of surface roughness which must be obtained after machining and intensity of tool wear rate.The paper considers a process of turning structural steel with asymmetric

  16. Influence of various surface-conditioning methods on the bond strength of metal brackets to ceramic surfaces

    NARCIS (Netherlands)

    Schmage, P; Nergiz, [No Value; Herrmann, W; Ozcan, M; Nergiz, Ibrahim; �zcan, Mutlu

    With the increase in adult orthodontic treatment comes the need to find a reliable method for bonding orthodontic brackets onto metal or ceramic crowns and fixed partial dentures. In this study, shear bond strength and surface roughness tests were used to examine the effect of 4 different surface

  17. Oxygen accumulation on metal surfaces investigated by XPS, AES and LEIS, an issue for sputter depth profiling under UHV conditions

    Science.gov (United States)

    Steinberger, R.; Celedón, C. E.; Bruckner, B.; Roth, D.; Duchoslav, J.; Arndt, M.; Kürnsteiner, P.; Steck, T.; Faderl, J.; Riener, C. K.; Angeli, G.; Bauer, P.; Stifter, D.

    2017-07-01

    Depth profiling using surface sensitive analysis methods in combination with sputter ion etching is a common procedure for thorough material investigations, where clean surfaces free of any contamination are essential. Hence, surface analytic studies are mostly performed under ultra-high vacuum (UHV) conditions, but the cleanness of such UHV environments is usually overrated. Consequently, the current study highlights the in principle known impact of the residual gas on metal surfaces (Fe, Mg, Al, Cr and Zn) for various surface analytics methods, like X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and low-energy ion scattering (LEIS). The investigations with modern, state-of-the-art equipment showed different behaviors for the metal surfaces in UHV during acquisition: (i) no impact for Zn, even after long time, (ii) solely adsorption of oxygen for Fe, slight and slow changes for Cr and (iii) adsorption accompanied by oxide formation for Al and Mg. The efficiency of different counter measures was tested and the acquired knowledge was finally used for ZnMgAl coated steel to obtain accurate depth profiles, which exhibited before serious artifacts when data acquisition was performed in an inconsiderate way.

  18. Growth rate and surface morphology of 4H-SiC crystals grown from Si-Cr-C and Si-Cr-Al-C solutions under various temperature gradient conditions

    Science.gov (United States)

    Mitani, Takeshi; Komatsu, Naoyoshi; Takahashi, Tetsuo; Kato, Tomohisa; Fujii, Kuniharu; Ujihara, Toru; Matsumoto, Yuji; Kurashige, Kazuhisa; Okumura, Hajime

    2014-09-01

    The growth rate and surface morphology of 4H-SiC crystals prepared by solution growth with Si1-xCrx and Si1-x-yCrxAly (x=0.4, 0.5 and 0.6; y=0.04) solvents were investigated under various temperature conditions. The growth rate was examined as functions of the temperature difference between the growth surface and C source, the amount of supersaturated C and supersaturation at the growth surface. We found that generation of trench-like surface defects in 4H-SiC crystals was suppressed using Si1-x-yCrxAly solvents even under highly supersaturated conditions where the growth rate exceeded 760 μm/h. Conversely, trench-like defects were observed in crystals grown with Si1-xCrx solvents under all experimental conditions. Statistical observation of the macrostep structure showed that the macrostep height in crystals grown with Si1-x-yCrxAly solvents was maintained at lower levels than that obtained using Si1-xCrx solvents. Addition of Al prevents the macrosteps from developing into large steps, which are responsible for the generation of trench-like surface defects.

  19. Effect of manufacturing and experimental conditions on the mechanical and surface properties of silicone elastomer scaffolds used in endothelial mechanobiological studies.

    Science.gov (United States)

    Campeau, Marc-Antoine; Lortie, Audrey; Tremblay, Pierrick; Béliveau, Marc-Olivier; Dubé, Dominic; Langelier, Ève; Rouleau, Léonie

    2017-07-14

    Mechanobiological studies allow the characterization of cell response to mechanical stresses. Cells need to be supported by a material with properties similar to the physiological environment. Silicone elastomers have been used to produce various in vitro scaffolds of different geometries for endothelial cell studies given its relevant mechanical, optical and surface properties. However, obtaining defined and repeatable properties is a challenge as depending on the different manufacturing and processing steps, mechanical and surface properties may vary significantly between research groups. The impact of different manufacturing and processing methods on the mechanical and surface properties was assessed by measuring the Young's modulus and the contact angle. Silicone samples were produced using different curing temperatures and processed with different sterilization techniques and hydrophilization conditions. Different curing temperatures were used to obtain materials of different stiffness with a chosen silicone elastomer, i.e. Sylgard 184 ® . Sterilization by boiling had a tendency to stiffen samples cured at lower temperatures whereas UV and ethanol did not alter the material properties. Hydrophilization using sulphuric acid allowed to decrease surface hydrophobicity, however this effect was lost over time as hydrophobic recovery occurred. Extended contact with water maintained decreased hydrophobicity up to 7 days. Mechanobiological studies require complete cell coverage of the scaffolds used prior to mechanical stresses exposure. Different concentrations of fibronectin and collagen were used to coat the scaffolds and cell seeding density was varied to optimize cell coverage. This study highlights the potential bias introduced by manufacturing and processing conditions needed in the preparation of scaffolds used in mechanobiological studies involving endothelial cells. As manufacturing, processing and cell culture conditions are known to influence cell

  20. Screening of penicillium species and optimisation of culture conditions for the production of ergot alkaloids using surface culture fermentation process

    International Nuclear Information System (INIS)

    Shahid, M.G.

    2015-01-01

    Abstract. The present study deals with the screening of fungal species and suitable fermentation medium for the production of ergot alkaloids. Various species of genus Penicillium were grown on different fermentation media by employing surface culture fermentation technique to achieve the most suitable medium and the best Penicillium sp. The results showed that medium M5 gave maximum yield with Penicillium commune. Different culture conditions such as effect of different carbon and nitrogen sources, their concentration levels, different pH values and sizes of inoculum on the production of ergot alkaloids were also studied to improve the yield. Maximum production of ergot alkaloids (4.32 mg/L) was achieved with 15 mL spore suspension at pH 5 in fermentation medium containing 35% (w/v) sucrose. All these results indicate that culture conditions are very much crucial to improve the yield of ergot alkaloids produced by Penicillium commune through surface culture process. (author)

  1. Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.

    Science.gov (United States)

    Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Enriquez-Victorero, Carlos; Montero-Alejo, Ana Lilian; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2016-04-01

    Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. HIFU scattering by the ribs: constrained optimisation with a complex surface impedance boundary condition

    Science.gov (United States)

    Gélat, P.; ter Haar, G.; Saffari, N.

    2014-04-01

    High intensity focused ultrasound (HIFU) enables highly localised, non-invasive tissue ablation and its efficacy has been demonstrated in the treatment of a range of cancers, including those of the kidney, prostate and breast. HIFU offers the ability to treat deep-seated tumours locally, and potentially bears fewer side effects than more established treatment modalities such as resection, chemotherapy and ionising radiation. There remains however a number of significant challenges which currently hinder its widespread clinical application. One of these challenges is the need to transmit sufficient energy through the ribcage to ablate tissue at the required foci whilst minimising the formation of side lobes and sparing healthy tissue. Ribs both absorb and reflect ultrasound strongly. This sometimes results in overheating of bone and overlying tissue during treatment, leading to skin burns. Successful treatment of a patient with tumours in the upper abdomen therefore requires a thorough understanding of the way acoustic and thermal energy is deposited. Previously, a boundary element (BE) approach based on a Generalised Minimal Residual (GMRES) implementation of the Burton-Miller formulation was developed to predict the field of a multi-element HIFU array scattered by human ribs, the topology of which was obtained from CT scan data [1]. Dissipative mechanisms inside the propagating medium have since been implemented, together with a complex surface impedance condition at the surface of the ribs. A reformulation of the boundary element equations as a constrained optimisation problem was carried out to determine the complex surface velocities of a multi-element HIFU array which generated the acoustic pressure field that best fitted a required acoustic pressure distribution in a least-squares sense. This was done whilst ensuring that an acoustic dose rate parameter at the surface of the ribs was kept below a specified threshold. The methodology was tested at an

  3. Conditioning of Si-interfaces by wet-chemical oxidation: Electronic interface properties study by surface photovoltage measurements

    Energy Technology Data Exchange (ETDEWEB)

    Angermann, Heike, E-mail: angermann@helmholtz-berlin.de

    2014-09-01

    Highlights: • Determination of electronic interface properties by contact-less surface photovoltage (SPV) technique. • Systematic correlations of substrate morphology and surface electronic properties. • Optimization of surface pre-treatment for flat, saw damage etched, and textured Si solar cell substrates. • Ultra-thin passivating Si oxide layers with low densities of rechargeable states by wet-chemical oxidation and subsequent annealing. • Environmentally acceptable processes, utilizing hot water, diluted HCl, or ozone low cost alternative to current approaches with concentrated chemicals. • The effect of optimized wet-chemical pre-treatments can be preserved during subsequent layer deposition. - Abstract: The field-modulated surface photovoltage (SPV) method, a very surface sensitive technique, was utilized to determine electronic interface properties on wet-chemically oxidized and etched silicon (Si) interfaces. The influence of preparation-induced surface micro-roughness and un-stoichiometric oxides on the resulting the surface charge, energetic distribution D{sub it}(E), and density D{sub it,min} of rechargeable states was studied by simultaneous, spectroscopic ellipsometry (SE) measurements on polished Si(111) and Si(100) substrates. Based on previous findings and new research, a study of conventional and newly developed wet-chemical oxidation methods was established, correlating the interactions between involved oxidizing and etching solutions and the initial substrate morphology to the final surface conditioning. It is shown, which sequences of wet-chemical oxidation and oxide removal, have to be combined in order to achieve atomically smooth, hydrogen terminated surfaces, as well as ultra-thin oxide layers with low densities of rechargeable states on flat, saw damage etched, and textured Si substrates, as commonly applied in silicon device and solar cell manufacturing. These conventional strategies for wet-chemical pre-treatment are mainly

  4. Conditioning of Si-interfaces by wet-chemical oxidation: Electronic interface properties study by surface photovoltage measurements

    International Nuclear Information System (INIS)

    Angermann, Heike

    2014-01-01

    Highlights: • Determination of electronic interface properties by contact-less surface photovoltage (SPV) technique. • Systematic correlations of substrate morphology and surface electronic properties. • Optimization of surface pre-treatment for flat, saw damage etched, and textured Si solar cell substrates. • Ultra-thin passivating Si oxide layers with low densities of rechargeable states by wet-chemical oxidation and subsequent annealing. • Environmentally acceptable processes, utilizing hot water, diluted HCl, or ozone low cost alternative to current approaches with concentrated chemicals. • The effect of optimized wet-chemical pre-treatments can be preserved during subsequent layer deposition. - Abstract: The field-modulated surface photovoltage (SPV) method, a very surface sensitive technique, was utilized to determine electronic interface properties on wet-chemically oxidized and etched silicon (Si) interfaces. The influence of preparation-induced surface micro-roughness and un-stoichiometric oxides on the resulting the surface charge, energetic distribution D it (E), and density D it,min of rechargeable states was studied by simultaneous, spectroscopic ellipsometry (SE) measurements on polished Si(111) and Si(100) substrates. Based on previous findings and new research, a study of conventional and newly developed wet-chemical oxidation methods was established, correlating the interactions between involved oxidizing and etching solutions and the initial substrate morphology to the final surface conditioning. It is shown, which sequences of wet-chemical oxidation and oxide removal, have to be combined in order to achieve atomically smooth, hydrogen terminated surfaces, as well as ultra-thin oxide layers with low densities of rechargeable states on flat, saw damage etched, and textured Si substrates, as commonly applied in silicon device and solar cell manufacturing. These conventional strategies for wet-chemical pre-treatment are mainly based on

  5. Influence of redox condition in iron, silicon and hydrogen contents of leached glass surface

    International Nuclear Information System (INIS)

    Manara, A.; Lanza, F.; Della Mea, G.; Rossi, C.; Salvagno, G.

    1984-01-01

    Surface analysis has been conducted on samples leached in a Sochlet apparatus at 100 0 C in the presence and in the absence of air. The XPS technique was applied to analyze the content of iron and silicon while the nuclear reaction method was utilized to analyze the content of hydrogen. Samples leached in argon atmosphere have shown a smaller content of iron and silicon with respect to the samples leached in air atmosphere. The H concentration has shown the same behavior. The results are discussed in terms of possible formation of iron compounds in the different redox condition and of their different stabilities and in terms of their efficiency in reducing exchange between Na + and H + ions. 11 references, 3 figures, 1 table

  6. Optimizing Cutting Conditions for Minimum Surface Roughness in Face Milling of High Strength Steel Using Carbide Inserts

    Directory of Open Access Journals (Sweden)

    Adel Taha Abbas

    2016-01-01

    Full Text Available A full factorial design technique is used to investigate the effect of machining parameters, namely, spindle speed (N, depth of cut (ap, and table feed rate (Vf, on the obtained surface roughness (Ra and Rt during face milling operation of high strength steel. A second-order regression model was built using least squares method depending on the factorial design results to approximate a mathematical relationship between the surface roughness and the studied process parameters. Analysis of variance was conducted to estimate the significance of each factor and interaction with respect to the surface roughness. For Ra, the results show that spindle speed, depth of cut, and table feed rate have a significant effect on the surface roughness in both linear and quadratic terms. There is also an interaction between depth of cut and feed rate. It also appears that feed rate has the greatest effect on the data variation followed by depth of cut. For Rt, the results show that the table feed rate is the most effective factor followed by the depth of cut, while the spindle speed had a significant small effect only in its quadratic term. The conditions of minimum Ra and Rt are identified through least square optimization. Moreover, multiobjective optimization for minimizing Ra and maximizing metal removal rate Q is conducted and the results are presented.

  7. Impact of groundwater capillary rises as lower boundary conditions for soil moisture in a land surface model

    Science.gov (United States)

    Vergnes, Jean-Pierre; Decharme, Bertrand; Habets, Florence

    2014-05-01

    Groundwater is a key component of the global hydrological cycle. It sustains base flow in humid climate while it receives seepage in arid region. Moreover, groundwater influences soil moisture through water capillary rise into the soil and potentially affects the energy and water budget between the land surface and the atmosphere. Despite its importance, most global climate models do not account for groundwater and their possible interaction with both the surface hydrology and the overlying atmosphere. This study assesses the impact of capillary rise from shallow groundwater on the simulated water budget over France. The groundwater scheme implemented in the Total Runoff Integrated Pathways (TRIP) river routing model in a previous study is coupled with the Interaction between Soil Biosphere Atmosphere (ISBA) land surface model. In this coupling, the simulated water table depth acts as the lower boundary condition for the soil moisture diffusivity equation. An original parameterization accounting for the subgrid elevation inside each grid cell is proposed in order to compute this fully-coupled soil lower boundary condition. Simulations are performed at high (1/12°) and low (0.5°) resolutions and evaluated over the 1989-2009 period. Compared to a free-drain experiment, upward capillary fluxes at the bottom of soil increase the mean annual evapotranspiration simulated over the aquifer domain by 3.12 % and 1.54 % at fine and low resolutions respectively. This process logically induces a decrease of the simulated recharge from ISBA to the aquifers and contributes to enhance the soil moisture memory. The simulated water table depths are then lowered, which induces a slight decrease of the simulated mean annual river discharges. However, the fully-coupled simulations compare well with river discharge and water table depth observations which confirms the relevance of the coupling formalism.

  8. Surface origin and control of resonance Raman scattering and surface band gap in indium nitride

    International Nuclear Information System (INIS)

    Alarcón-Lladó, Esther; Brazzini, Tommaso; Ager, Joel W

    2016-01-01

    Resonance Raman scattering measurements were performed on indium nitride thin films under conditions where the surface electron concentration was controlled by an electrolyte gate. As the surface condition is tuned from electron depletion to accumulation, the spectral feature at the expected position of the ( E 1 , A 1 ) longitudinal optical (LO) near 590 cm −1 shifts to lower frequency. The shift is reversibly controlled with the applied gate potential, which clearly demonstrates the surface origin of this feature. The result is interpreted within the framework of a Martin double resonance, where the surface functions as a planar defect, allowing the scattering of long wavevector phonons. The allowed wavevector range, and hence the frequency, is modulated by the electron accumulation due to band gap narrowing. A surface band gap reduction of over 500 meV is estimated for the conditions of maximum electron accumulation. Under conditions of electron depletion, the full InN bandgap ( E g   =  0.65 eV) is expected at the surface. The drastic change in the surface band gap is expected to influence the transport properties of devices which utilize the surface electron accumulation layer. (paper)

  9. Surface origin and control of resonance Raman scattering and surface band gap in indium nitride

    Science.gov (United States)

    Alarcón-Lladó, Esther; Brazzini, Tommaso; Ager, Joel W.

    2016-06-01

    Resonance Raman scattering measurements were performed on indium nitride thin films under conditions where the surface electron concentration was controlled by an electrolyte gate. As the surface condition is tuned from electron depletion to accumulation, the spectral feature at the expected position of the (E 1, A 1) longitudinal optical (LO) near 590 cm-1 shifts to lower frequency. The shift is reversibly controlled with the applied gate potential, which clearly demonstrates the surface origin of this feature. The result is interpreted within the framework of a Martin double resonance, where the surface functions as a planar defect, allowing the scattering of long wavevector phonons. The allowed wavevector range, and hence the frequency, is modulated by the electron accumulation due to band gap narrowing. A surface band gap reduction of over 500 meV is estimated for the conditions of maximum electron accumulation. Under conditions of electron depletion, the full InN bandgap (E g  =  0.65 eV) is expected at the surface. The drastic change in the surface band gap is expected to influence the transport properties of devices which utilize the surface electron accumulation layer.

  10. Dry Phosphorus silicate glass etching and surface conditioning and cleaning for multi-crystalline silicon solar cell processing

    International Nuclear Information System (INIS)

    Kagilik, Ahmed S.

    2014-01-01

    As an alternative to the wet chemical etching method, dry chemical etching processes for Phosphorus silicate glass [PSG} layer removal using Trifluormethane/Sulfur Hexafluoride (CHF 3 / SF 6 ) gas mixture in commercial silicon-nitride plasma enhanced chemical vapour deposition (SiN-PECVD) system is applied. The dependence of the solar cell performance on the etching temperature is investigated and optimized. It is found that the SiN-PECVD system temperature variation has a significant impact on the whole solar cell characteristics. A dry plasma cleaning treatment of the Si wafer surface after the PSG removal step is also investigated and developed. The cleaning step is used to remove the polymer film which is formed during the PSG etching using both oxygen and hydrogen gases. By applying an additional cleaning step, the polymer film deposited on the silicon wafer surface after PSG etching is eliminated. The effect of different plasma cleaning conditions on solar cell performance is investigated. After optimization of the plasma operating conditions, the performance of the solar cell is improved and the overall gain in efficiency of 0.6% absolute is yielded compared to a cell without any further cleaning step. On the other hand, the best solar cell characteristics can reach values close to that achieved by the conventional wet chemical etching processes demonstrating the effectiveness of the additional O 2 /H 2 post cleaning treatment.(author)

  11. A comprehensive approach to identify dominant controls of the behavior of a land surface-hydrology model across various hydroclimatic conditions

    Science.gov (United States)

    Haghnegahdar, Amin; Elshamy, Mohamed; Yassin, Fuad; Razavi, Saman; Wheater, Howard; Pietroniro, Al

    2017-04-01

    Complex physically-based environmental models are being increasingly used as the primary tool for watershed planning and management due to advances in computation power and data acquisition. Model sensitivity analysis plays a crucial role in understanding the behavior of these complex models and improving their performance. Due to the non-linearity and interactions within these complex models, Global sensitivity analysis (GSA) techniques should be adopted to provide a comprehensive understanding of model behavior and identify its dominant controls. In this study we adopt a multi-basin multi-criteria GSA approach to systematically assess the behavior of the Modélisation Environmentale-Surface et Hydrologie (MESH) across various hydroclimatic conditions in Canada including areas in the Great Lakes Basin, Mackenzie River Basin, and South Saskatchewan River Basin. MESH is a semi-distributed physically-based coupled land surface-hydrology modelling system developed by Environment and Climate Change Canada (ECCC) for various water resources management purposes in Canada. We use a novel method, called Variogram Analysis of Response Surfaces (VARS), to perform sensitivity analysis. VARS is a variogram-based GSA technique that can efficiently provide a spectrum of sensitivity information across a range of scales within the parameter space. We use multiple metrics to identify dominant controls of model response (e.g. streamflow) to model parameters under various conditions such as high flows, low flows, and flow volume. We also investigate the influence of initial conditions on model behavior as part of this study. Our preliminary results suggest that this type of GSA can significantly help with estimating model parameters, decreasing calibration computational burden, and reducing prediction uncertainty.

  12. Surface chemistry analysis of lithium conditioned NSTX graphite tiles correlated to plasma performance

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, C.N., E-mail: chase.taylor@inl.gov [Purdue University, School of Nuclear Engineering, West Lafayette, IN 47906 (United States); Birck Nanotechnology Center, Discovery Park, West Lafayette, IN 47907 (United States); Luitjohan, K.E. [Purdue University, School of Nuclear Engineering, West Lafayette, IN 47906 (United States); Heim, B. [Purdue University, School of Nuclear Engineering, West Lafayette, IN 47906 (United States); Birck Nanotechnology Center, Discovery Park, West Lafayette, IN 47907 (United States); Kollar, L. [Purdue University, School of Nuclear Engineering, West Lafayette, IN 47906 (United States); Allain, J.P. [Purdue University, School of Nuclear Engineering, West Lafayette, IN 47906 (United States); Birck Nanotechnology Center, Discovery Park, West Lafayette, IN 47907 (United States); Skinner, C.H.; Kugel, H.W.; Kaita, R.; Roquemore, A.L. [Princeton Plasma Physics Laboratory, Princeton, NJ 08543 (United States); Maingi, R. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2013-12-15

    Lithium wall conditioning in NSTX has resulted in reduced divertor recycling, improved energy confinement, and reduced frequency of edge-localized modes (ELMs), up to the point of complete ELM suppression. NSTX tiles were removed from the vessel following the 2008 campaign and subsequently analyzed using X-ray photoelectron spectroscopy as well as nuclear reaction ion beam analysis. In this paper we relate surface chemistry to deuterium retention/recycling, develop methods for cleaning of passivated NSTX tiles, and explore a method to effectively extract bound deuterium from lithiated graphite. Li–O–D and Li–C–D complexes characteristic of deuterium retention that form during NSTX operations are revealed by sputter cleaning and heating. Heating to ∼850 °C desorbed all deuterium complexes observed in the O 1s and C 1s photoelectron energy ranges. Tile locations within approximately ±2.5 cm of the lower vertical/horizontal divertor corner appear to have unused Li-O bonds that are not saturated with deuterium, whereas locations immediately outboard of this region indicate high deuterium recycling. X-ray photo electron spectra of a specific NSTX tile with wide ranging lithium coverage indicate that a minimum lithium dose, 100–500 nm equivalent thickness, is required for effective deuterium retention. This threshold is suspected to be highly sensitive to surface morphology. The present analysis may explain why plasma discharges in NSTX continue to benefit from lithium coating thickness beyond the divertor deuterium ion implantation depth, which is nominally <10 nm.

  13. Silver endotaxy in silicon under various ambient conditions and their use as surface enhanced Raman spectroscopy substrates

    International Nuclear Information System (INIS)

    Juluri, R.R.; Ghosh, A.; Bhukta, A.; Sathyavathi, R.; Satyam, P.V.

    2015-01-01

    Search for reliable, robust and efficient substrates for surface enhanced Raman spectroscopy (SERS) leads to the growth of various shapes and nanostructures of noble metals, and in particular, Ag nanostructures for this purpose. Coherently embedded (also known as endotaxial) Ag nanostructures in silicon substrates can be made robust and reusable SERS substrates. In this paper, we show the possibility of the growth of Ag endotaxial structures in Si crystal during Ar and low-vacuum annealing conditions while this is absent in O 2 and ultra high vacuum (UHV) annealing conditions and along with their respective use as SERS substrates. Systems annealed under air-annealing and low-vacuum conditions were found to show larger enhancement factors (typically ≈ 5 × 10 5 in SERS measurement for 0.5 nM Crystal Violet (CV) molecule) while the systems prepared under UHV-annealing conditions (where no endotaxial Ag structures were formed) were found to be not effective as SERS substrates. Extensive electron microscopy, synchrotron X-ray diffraction and Rutherford backscattering spectrometry techniques were used to understand the structural aspects. - Highlights: • Various aspects on the growth of endotaxial Ag nanostructures are presented. • Optimum amount of oxygen is necessary for the growth of endotaxial structures. • Reaction of oxygen with GeOx and SiOx plays a crucial role. • Ag nanostructures prepared under UHV conditions show low SERS activity • SERS enhancement is better for low-vacuum and argon annealing conditions

  14. Surface runoff and soil erosion by difference of surface cover characteristics using by an oscillating rainfall simulator

    Science.gov (United States)

    Kim, J. K.; Kim, M. S.; Yang, D. Y.

    2017-12-01

    Sediment transfer within hill slope can be changed by the hydrologic characteristics of surface material on hill slope. To better understand sediment transfer of the past and future related to climate changes, studies for the changes of soil erosion due to hydrological characteristics changes by surface materials on hill slope are needed. To do so, on-situ rainfall simulating test was conducted on three different surface conditions, i.e. well covered with litter layer condition (a), undisturbed bare condition (b), and disturbed bare condition (c) and these results from rainfall simulating test were compared with that estimated using the Limburg Soil Erosion Model (LISEM). The result from the rainfall simulating tests showed differences in the infiltration rate (a > b > c) and the highest soil erosion rate was occurred on c condition. The result from model also was similar to those from rainfall simulating tests, however, the difference from the value of soil erosion rate between two results was quite large on b and c conditions. These results implied that the difference of surface conditions could change the surface runoff and soil erosion and the result from the erosion model might significantly underestimate on bare surface conditions rather than that from rainfall simulating test.

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

    Science.gov (United States)

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

    2016-02-01

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

  16. ASSESSMENT OF SURFACE QUALITY FOR CHOSEN MILLING STRATEGIES WHEN PRODUCING RELIEF SURFACES

    OpenAIRE

    Jan Varga; Jozef Stahovec; Jozef Beno; Marek Vrabeľ

    2014-01-01

    The paper deals with design and modeling of the relief surfaces that are produced in milling. Modeled and real surface quality is presented for the chosen fragments of the relief surfaces. Fragmentation of the relief surfaces has been made by the surface sampling. Milling strategies are compared with regard to surface formation. Surface quality was checked with regard to applied cutting conditions.

  17. Adaptative changes of leaf surface of tropical orchid Cattleya gaskelliana (N.E.Br. B.S. Williams after transferring from in vitro to ex vitro conditions

    Directory of Open Access Journals (Sweden)

    Lyudmila I. Buyun

    2013-04-01

    Full Text Available The leaf surface micromorphology of Cattleya gaskellianajuvenile plants, propagated in vitrofrom seeds, as well as of adult plants, cultivated in glasshouse, was analyzed by scanning electron microscopy (SEM. The leaves of both juvenile and adult plants are hypostomatic, their stomata are of tetracytic type. It was found that development of single stomata on the adaxial leaf surface of juvenile plants was induced byin vitro conditions. During the acclimation of in vitro propagated plants to glasshouse conditions the following changes of leaf surface micromorphology have been observed: 1 configuration of epidermal cells changed; 2 dimensions of typical epidermal cells reduced; 3 stomata density and their dimensions increased. The results suggest that structural changes, probably, can be regarded as an adaptation to avoid excessive rate leaf transpiration during a period of C. gaskelliana juvenile plants acclimation to glasshouse conditions. In the case when micromorphological leaf characteristics (stomata density per mm2, stomatal index, epidermal cells number per mm 2 of in vitro propagated plants of C. gaskelliana were comparable to those of adult plants, survival rate was more than 95%.

  18. Optimisation of Ultrasound-Assisted Extraction Conditions for Phenolic Content and Antioxidant Capacity from Euphorbia tirucalli Using Response Surface Methodology

    Science.gov (United States)

    Vuong, Quan V.; Goldsmith, Chloe D.; Dang, Trung Thanh; Nguyen, Van Tang; Bhuyan, Deep Jyoti; Sadeqzadeh, Elham; Scarlett, Christopher J.; Bowyer, Michael C.

    2014-01-01

    Euphorbia tirucalli (E. tirucalli) is now widely distributed around the world and is well known as a source of traditional medicine in many countries. This study aimed to utilise response surface methodology (RSM) to optimise ultrasonic-assisted extraction (UAE) conditions for total phenolic compounds (TPC) and antioxidant capacity from E. tirucalli leaf. The results showed that ultrasonic temperature, time and power effected TPC and antioxidant capacity; however, the effects varied. Ultrasonic power had the strongest influence on TPC; whereas ultrasonic temperature had the greatest impact on antioxidant capacity. Ultrasonic time had the least impact on both TPC and antioxidant capacity. The optimum UAE conditions were determined to be 50 °C, 90 min. and 200 W. Under these conditions, the E. tirucalli leaf extract yielded 2.93 mg GAE/g FW of TPC and exhibited potent antioxidant capacity. These conditions can be utilised for further isolation and purification of phenolic compounds from E. tirucalli leaf. PMID:26785074

  19. Polarization optics of the Brewster's dark patch visible on water surfaces versus solar height and sky conditions: theory, computer modeling, photography, and painting.

    Science.gov (United States)

    Takács, Péter; Barta, András; Pye, David; Horváth, Gábor

    2017-10-20

    When the sun is near the horizon, a circular band with approximately vertically polarized skylight is formed at 90° from the sun, and this skylight is only weakly reflected from the region of the water surface around the Brewster's angle (53° from the nadir). Thus, at low solar heights under a clear sky, an extended dark patch is visible on the water surface when one looks toward the north or south quarter perpendicular to the solar vertical. In this work, we study the radiance distribution of this so-called Brewster's dark patch (BDP) in still water as functions of the solar height and sky conditions. We calculate the pattern of reflectivity R of a water surface for a clear sky and obtain from this idealized situation the shape of the BDP. From three full-sky polarimetric pictures taken about a clear, a partly cloudy, and an overcast sky, we determine the R pattern and compose from that synthetic color pictures showing how the radiance distribution of skylight reflected at the water surface and the BDPs would look under these sky conditions. We also present photographs taken without a linearly polarizing filter about the BDP. Finally, we show a 19th century painting on which a river is seen with a dark region of the water surface, which can be interpreted as an artistic illustration of the BDP.

  20. AlSiTiN and AlSiCrN multilayer coatings: Effects of structure and surface composition on tribological behavior under dry and lubricated conditions

    International Nuclear Information System (INIS)

    Faga, Maria Giulia; Gautier, Giovanna; Cartasegna, Federico; Priarone, Paolo C.; Settineri, Luca

    2016-01-01

    Graphical abstract: - Highlights: • The demand for high performance nanostructured coatings has been increasing. • AlSiTiN and AlSiCrN nanocomposite coatings were deposited by PVD technique. • Coatings were analyzed in terms of structure, hardness and adhesion. • Tribological properties under dry and lubricated conditions were studied. • The effects of surface and bulk properties on friction evolution were assessed. - Abstract: Nanocomposite coatings have been widely studied over the last years because of their high potential in several applications. The increased interest for these coatings prompted the authors to study the tribological properties of two nanocomposites under dry and lubricated conditions (applying typical MQL media), in order to assess the influence of the surface and bulk properties on friction evolution. To this purpose, multilayer and nanocomposite AlSiTiN and AlSiCrN coatings were deposited onto tungsten carbide-cobalt (WC-Co) samples. Uncoated WC-Co materials were used as reference. Coatings were analyzed in terms of hardness and adhesion. The structure of the samples was assessed by X-ray diffraction (XRD), while the surface composition was studied by XPS analysis. Friction tests were carried out under both dry and lubricated conditions using an inox ball as counterpart. Both coatings showed high hardness and good adhesion to the substrate. As far as the friction properties are concerned, in dry conditions the surface properties affect the sliding contact at the early beginning, while bulk structure and tribolayer formation determine the main behavior. Only AlSiTiN coating shows a low and stable coefficient of friction (COF) under dry condition, while the use of MQL media results in a rapid stabilization of the COF for all the materials.

  1. Novel tree-like WO3 nanoplatelets with very high surface area synthesized by anodization under controlled hydrodynamic conditions

    OpenAIRE

    Fernández Domene, Ramón Manuel; Sánchez Tovar, Rita; SEGURA SANCHIS, ELENA; Garcia-Anton, Jose

    2016-01-01

    In the present work, a new WO3 nanostructure has been obtained by anodization in a H2SO4/NaF electrolyte under controlled hydrodynamic conditions using a Rotating Disk Electrode (RDE) configuration. Anodized samples were analyzed by means of Field Emission Scanning Electronic Microscopy (FESEM), Confocal Raman Microscopy and photoelectrochemical measurements. The new nanostructure, which consists of nanoplatelets clusters growing in a tree-like manner, presents a very high surface area expose...

  2. Thermal performance of a spirally coiled finned tube heat exchanger under wet-surface conditions

    International Nuclear Information System (INIS)

    Wongwises, Somchai; Naphon, Paisarn

    2006-01-01

    This paper is a continuation of the author's previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data

  3. Correlation of Growth and Surface Properties of Poly(\\(p\\-xylylenes to  Reaction Conditions

    Directory of Open Access Journals (Sweden)

    Andreas Reichel

    2015-05-01

    Full Text Available Parylene, a non-critical, non-toxic layer material, which is not only a candidate for low-\\(K\\ dielectrics, but also well suited for long-term applications in the human body, has been deposited by (plasma-enhanced chemical vapor deposition of the monomeric species. To that end, a specially-designed reactor exhibiting a cracker tube at its entrance, which serves as the upstream control, and a cooling trap in front of the downstream control has been applied. The process of polymerization has been traced and is explained by evaporating the dimeric species followed by dissociation in the cracker at elevated temperatures and, eventually, to the coating of the polymeric film in terms of thermodynamics. Alternatively, the process of dissociation has been accomplished applying a microwave plasma. In both cases, the monomerization is controlled by mass spectrometry. The window for surface polymerization could be clearly defined in terms of a factor of dilution by an inert gas for the chemical vapor deposition (CVD case and in the case of plasma-enhanced chemical vapor deposition (PECVD, additionally by the power density. The characterization of the layer parameters has been carried out by several analytical tools: scanning electron microscopy and atomic force microscopy to determine the surface roughness and density and depth of voids in the film, which influence the layer capacitance and deteriorate the breakdown voltage, a bulk property. The main issue is the conduct against liquids between the two borders' hydrophilic and hydrophobic conduct, but also the super-hydrophobic character, which is the condition for the Lotus effect. The surface tension has been evaluated by contact angle measurements. Fourier-transform infrared spectroscopy has proven the conservation of all of the functional groups during polymerization.

  4. Analysis of the dual phase lag bio-heat transfer equation with constant and time-dependent heat flux conditions on skin surface

    Directory of Open Access Journals (Sweden)

    Ziaei Poor Hamed

    2016-01-01

    Full Text Available This article focuses on temperature response of skin tissue due to time-dependent surface heat fluxes. Analytical solution is constructed for DPL bio-heat transfer equation with constant, periodic and pulse train heat flux conditions on skin surface. Separation of variables and Duhamel’s theorem for a skin tissue as a finite domain are employed. The transient temperature responses for constant and time-dependent boundary conditions are obtained and discussed. The results show that there is major discrepancy between the predicted temperature of parabolic (Pennes bio-heat transfer, hyperbolic (thermal wave and DPL bio-heat transfer models when high heat flux accidents on the skin surface with a short duration or propagation speed of thermal wave is finite. The results illustrate that the DPL model reduces to the hyperbolic model when τT approaches zero and the classic Fourier model when both thermal relaxations approach zero. However for τq = τT the DPL model anticipates different temperature distribution with that predicted by the Pennes model. Such discrepancy is due to the blood perfusion term in energy equation. It is in contrast to results from the literature for pure conduction material, where the DPL model approaches the Fourier heat conduction model when τq = τT . The burn injury is also investigated.

  5. Seed banks in a degraded desert shrubland: Influence of soil surface condition and harvester ant activity on seed abundance

    Science.gov (United States)

    DeFalco, L.A.; Esque, T.C.; Kane, J.M.; Nicklas, M.B.

    2009-01-01

    We compared seed banks between two contrasting anthropogenic surface disturbances (compacted, trenched) and adjacent undisturbed controls to determine whether site condition influences viable seed densities of perennial and annual Mojave Desert species. Viable seeds of perennials were rare in undisturbed areas (3-4 seeds/m2) and declined to importance of litter as an indicator of site degradation and recovery potential in arid lands.

  6. Experimental simulations of oxidizing conditions and organic decomposition on the surface of Mars

    International Nuclear Information System (INIS)

    Stoker, C.R.; Mancinelli, R.L.; Mckay, C.P.

    1988-01-01

    One important scientific objective of a Mars Rover Sample Return mission would be to look for traces of living and extinct life on Mars. An instrument to search for organic carbon may be the simplest instrument that could screen samples which are interesting from a biological point of view. An experimental program is described which would help to understand the nature of the oxidizing soil on Mars and the mechanism responsible for organic degradation on the Martian surface. This is approached by lab simulations of the actual conditions that occur on Mars, particularly the oxidant production by atmospheric photochemistry, and the combined effects of UV light and oxidants in decomposing organic compounds. The results will be used to formulate models of the photochemistry of the atmospheric, the atmosphere-soil interaction, and the diffusion of reactive compounds into the soils. This information will provide insights and constraints on the design of a sampling strategy to search for organic compounds on Mars

  7. The relative influence of H2O and CO2 on the primitive surface conditions of Venus

    Science.gov (United States)

    Salvador, A.; Massol, H.; Davaille, A.; Marcq, E.; Sarda, P.; Chassefiere, E.

    2017-12-01

    How the volatile content influences the primordial surface conditions of terrestrial planets and, thus, their future geodynamic evolution is an important question to answer. We simulate the secular convective cooling of a 1-D magma ocean (MO) in interaction with its outgassed atmosphere. A first rapid cooling stage, where efficient MO cooling and degassing take place, producing the atmosphere, is followed by a second quasi steady state where the heat flux balance is dominated by the solar flux. The end ofthe rapid cooling stage (ERCS) is reached when the mantle heat flux becomes negligible compared tothe absorbed solar flux. Varying the initial CO2 and H2O contents and the solar distance, we showed that the resulting surface conditions at ERCS strongly depend on these parameters and that water ocean's formation obeys simple scaling laws.Although today's Venus is located beyond the inner edge of the habitable zone due to its high albedo, its high CO2/H2O ratio prevents any water ocean formation.We already showed that depending on the formation time of its cloudcover and resulting albedo, only 0.3 Earth ocean mass might be sufficient to form a water ocean onearly Venus. Here we investigate more precisely these results by taking into account the effect of shortwave radiation on the radiative budget by computing the feedbacks between atmospheric composition and incident stellar flux instead of using a prescribed albedo value.

  8. On the appropriate definition of soil profile configuration and initial conditions for land surface-hydrology models in cold regions

    Science.gov (United States)

    Sapriza-Azuri, Gonzalo; Gamazo, Pablo; Razavi, Saman; Wheater, Howard S.

    2018-06-01

    Arctic and subarctic regions are amongst the most susceptible regions on Earth to global warming and climate change. Understanding and predicting the impact of climate change in these regions require a proper process representation of the interactions between climate, carbon cycle, and hydrology in Earth system models. This study focuses on land surface models (LSMs) that represent the lower boundary condition of general circulation models (GCMs) and regional climate models (RCMs), which simulate climate change evolution at the global and regional scales, respectively. LSMs typically utilize a standard soil configuration with a depth of no more than 4 m, whereas for cold, permafrost regions, field experiments show that attention to deep soil profiles is needed to understand and close the water and energy balances, which are tightly coupled through the phase change. To address this gap, we design and run a series of model experiments with a one-dimensional LSM, called CLASS (Canadian Land Surface Scheme), as embedded in the MESH (Modélisation Environmentale Communautaire - Surface and Hydrology) modelling system, to (1) characterize the effect of soil profile depth under different climate conditions and in the presence of parameter uncertainty; (2) assess the effect of including or excluding the geothermal flux in the LSM at the bottom of the soil column; and (3) develop a methodology for temperature profile initialization in permafrost regions, where the system has an extended memory, by the use of paleo-records and bootstrapping. Our study area is in Norman Wells, Northwest Territories of Canada, where measurements of soil temperature profiles and historical reconstructed climate data are available. Our results demonstrate a dominant role for parameter uncertainty, that is often neglected in LSMs. Considering such high sensitivity to parameter values and dependency on the climate condition, we show that a minimum depth of 20 m is essential to adequately represent

  9. Surface distribution of brachyuran megalopae and ichthyoplankton in the Columbia River plume during transition from downwelling to upwelling conditions

    Science.gov (United States)

    Roegner, G. Curtis; Daly, Elizabeth A.; Brodeur, Richard D.

    2013-06-01

    In the California Current coastal boundary zone, the spring transition between downwelling and upwelling conditions, along with the fluctuating structure of the Columbia River plume, creates highly dynamic interactions. In this study, we investigated whether the surface distribution of brachyuran larvae and ichthyoplankton would track the dynamics of the Columbia River plume. By happenstance, the cruise period coincided with the spring transition from downwelling to sustained upwelling conditions in 2010, a year when the transition was delayed and Columbia River flow was substantially higher than average. We used time series of wind and freshwater input to evaluate the influence of physical forcing on oceanographic patterns, and sampled hydrography and surface plankton concentrations within a 182 km2 grid off Willapa Bay, WA. Additionally, two longer transects, one cross-shelf and the other along-shore, were made to discern the extent of plume influence on larval crab and fish abundance. We found that plume waters that were trapped in a northward-flowing coastal-boundary current during downwelling conditions were advected offshore after several days of upwelling-favorable winds. Neustonic collections of brachyuran larvae and ichthyoplankton varied in response to this large seaward advective event. Megalopae of cancrid crabs exhibited patterns of both offshore transport (Cancer oregonensis/productus) and nearshore retention (C. magister). Additionally, abundant numbers of large juvenile widow (Sebastes entomelas) and yellowtail (S. flavidus) rockfish of a size appropriate for settlement were sampled during a period when ocean conditions favored high recruitment success. These results demonstrated that the response of planktonic crab larvae and ichthyoplankton to large-scale advection varied by species, with larger and more vagile fish exhibiting less evidence of passive transport than smaller crab larvae. Importantly, portions of the planktonic fish and crab

  10. Subnanometer Resolution and Enhanced Friction Contrast at the Surface of Perylene Diimide PDI8-CN2 Thin Films in Ambient Conditions.

    Science.gov (United States)

    Buzio, Renato; Gerbi, Andrea; Barra, Mario; Chiarella, Fabio; Gnecco, Enrico; Cassinese, Antonio

    2018-03-13

    We report high-resolution surface morphology and friction force maps of polycrystalline organic thin films derived by deposition of the n-type perylene diimide semiconductor PDI8-CN 2 . We show that the in-plane molecular arrangement into ordered, cofacial slip-stacked rows results in a largely anisotropic surface structure, with a characteristic sawtooth corrugation of a few Ångstroms wavelength and height. Load-controlled experiments reveal different types of friction contrast between the alternating sloped and stepped regions, with transitions from atomic-scale dissipative stick-slip to smooth sliding with ultralow friction within the surface unit cell. Notably, such a rich phenomenology is captured under ambient conditions. We demonstrate that friction contrast is well reproduced by numerical simulations assuming a reduced corrugation of the tip-molecule potential nearby the step edges. We propose that the side alkyl chains pack into a compact low-surface-energy overlayer, and friction modulation reflects periodic heterogeneity of chains bending properties and subsurface anchoring to the perylene cores.

  11. Tensile bond strength of resin composite repair in vitro using different surface preparation conditionings to an aged CAD/CAM resin nanoceramic.

    Science.gov (United States)

    Stawarczyk, Bogna; Krawczuk, Andreas; Ilie, Nicoleta

    2015-03-01

    This study was conducted in order to assess the pretreatment method (air abrasion, both wet and dry, and Al2O3 grinder), the conditioning method (comprised of different adhesive systems), the repair resin composite (low and high modulus of elasticity), the contamination of CoJet air-abraded surfaces with water, and the effect phosphoric acid on the macrotensile bond strength (TBS) to aged CAD/CAM resin nanoceramic (RNC). Aged RNC substrates (LAVA Ultimate, 3M ESPE; N = 900; 10,000 cycles, 5 °C/55 °C) were air-abraded (CoJet 3M ESPE) with and without water contamination or treated with an Al2O3 grinder (Cimara, Voco). Immediately after pretreatment, half of the specimens were additionally cleaned with phosphoric acid, while the rest were only rinsed with water. Four intermediate agents (Futurabond U/VOCO, Scotchbond Universal/3M ESPE, One Coat Bond/Coltène Whaledent, visio.link/bredent) were selected for conditioning the surface, while no conditioned specimens acted as control groups. Specimens were thereafter repaired using two direct resin composites (Arabesk Top and GrandioSo, VOCO), stored for 24 h at 37 °C in H2O, and thermally aged for 10,000 cycles (5 °C/55 °C; n = 15/subgroup). TBS and failure types were determined and evaluated with four- and one-way ANOVA and χ (2) test (p universal adhesives proved to be effective intermediate agents for repairing aged CAD/CAM RNC, while visio.link and Scotchbond Universal performed slightly better than Futurabond U. Phosphoric acid or water contamination of the air-abraded surface does not affect the repair bond strength.

  12. Prolonged silicon carbide integrated circuit operation in Venus surface atmospheric conditions

    Directory of Open Access Journals (Sweden)

    Philip G. Neudeck

    2016-12-01

    Full Text Available The prolonged operation of semiconductor integrated circuits (ICs needed for long-duration exploration of the surface of Venus has proven insurmountably challenging to date due to the ∼ 460 °C, ∼ 9.4 MPa caustic environment. Past and planned Venus landers have been limited to a few hours of surface operation, even when IC electronics needed for basic lander operation are protected with heavily cumbersome pressure vessels and cooling measures. Here we demonstrate vastly longer (weeks electrical operation of two silicon carbide (4H-SiC junction field effect transistor (JFET ring oscillator ICs tested with chips directly exposed (no cooling and no protective chip packaging to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere. This represents more than 100-fold extension of demonstrated Venus environment electronics durability. With further technology maturation, such SiC IC electronics could drastically improve Venus lander designs and mission concepts, fundamentally enabling long-duration enhanced missions to the surface of Venus.

  13. Comparison of Sensible Heat Flux from Eddy Covariance and Scintillometer over different land surface conditions

    Science.gov (United States)

    Zeweldi, D. A.; Gebremichael, M.; Summis, T.; Wang, J.; Miller, D.

    2008-12-01

    The large source of uncertainty in satellite-based evapotranspiration algorithm results from the estimation of sensible heat flux H. Traditionally eddy covariance sensors, and recently large-aperture scintillometers, have been used as ground truth to evaluate satellite-based H estimates. The two methods rely on different physical measurement principles, and represent different foot print sizes. In New Mexico, we conducted a field campaign during summer 2008 to compare H estimates obtained from the eddy covariance and scintillometer methods. During this field campaign, we installed sonic anemometers; one propeller eddy covariance (OPEC) equipped with net radiometer and soil heat flux sensors; large aperture scintillometer (LAS); and weather station consisting of wind speed, direction and radiation sensors over three different experimental areas consisting of different roughness conditions (desert, irrigated area and lake). Our results show the similarities and differences in H estimates obtained from these various methods over the different land surface conditions. Further, our results show that the H estimates obtained from the LAS agree with those obtained from the eddy covariance method when high frequency thermocouple temperature, instead of the typical weather station temperature measurements, is used in the LAS analysis.

  14. OPTIMIZATION OF PRETREATMENT CONDITIONS OF CARROTS TO MAXIMIZE JUICE RECOVERY BY RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    H. K. SHARMA

    2006-12-01

    Full Text Available Carrot juice was expressed in a hydraulic press using a wooden set up. Carrot samples pretreated at different designed combinations, using Central Composite Rotatable Design (CCRD, Response Surface Methodology (RSM, of pH, temperature and time were expressed and juice so obtained was characterized for various physico-chemical parameters which involved yield, TSS and water content, reducing sugars, total sugars and color (absorbance. The study indicated that carrots exposed to the different pretreatment conditions resulted in increased amount of yield than that of the control. The responses were optimized by numerical method and were found to be 78.23% yield, 0.93% color (abs, 3.41% reducing sugars, 5.53% total sugars, 6.69obrix, and 90.50% water content. All the derived mathematical models for the various responses were found to be fit significantly to predict the data.

  15. Enhanced Boiling on Micro-Configured Composite Surfaces Under Microgravity Conditions

    Science.gov (United States)

    Zhang, Nengli; Chai, An-Ti

    1999-01-01

    In order to accommodate the growing thermal management needs of future space platforms, several two-phase active thermal control systems (ATCSs) have evolved and were included in the designs of space stations. Compared to the pumped single-phase liquid loops used in the conventional Space Transportation System and Spacelab, ATCSs offer significant benefits that may be realized by adopting a two-phase fluid-loop system. Alternately, dynamic power systems (DPSs), based on the Rankine cycle, seem inevitably to be required to supply the electrical power requirements of expanding space activities. Boiling heat transfer is one of the key technologies for both ATCSs and DPSs. Nucleate boiling near critical heat flux (CHF) can transport very large thermal loads with much smaller device size and much lower pumping power. However, boiling performance deteriorates in a reduced gravity environment and operation in the CHF regime is precarious because any slight overload will cause the heat transfer to suddenly move to the film boiling regime, which in turn, will result in burnout of the heat transfer surfaces. New materials, such as micro-configured metal-graphite composites, can provide a solution for boiling enhancement. It has been shown experimentally that this type of material manifests outstanding boiling heat transfer performance and their CHF is also extended to higher values. Due to the high thermal conductivity of graphite fiber (up to 1,200 W/m-K in the fiber direction), the composite surfaces are non-isothermal during the boiling process. The composite surfaces are believed to have a much wider safe operating region (a more uniform boiling curve in the CHF regime) because non-isothermal surfaces have been found to be less sensitive to variations of wall superheat in the CHF regime. The thermocapillary forces formed by the temperature difference between the fiber tips and the metal matrix play a more important role than the buoyancy in the bubble detachment, for the

  16. Extreme fire events are related to previous-year surface moisture conditions in permafrost-underlain larch forests of Siberia

    International Nuclear Information System (INIS)

    Forkel, Matthias; Beer, Christian; Thonicke, Kirsten; Cramer, Wolfgang; Bartalev, Sergey; Schmullius, Christiane

    2012-01-01

    Wildfires are a natural and important element in the functioning of boreal forests. However, in some years, fires with extreme spread and severity occur. Such severe fires can degrade the forest, affect human values, emit huge amounts of carbon and aerosols and alter the land surface albedo. Usually, wind, slope and dry air conditions have been recognized as factors determining fire spread. Here we identify surface moisture as an additional important driving factor for the evolution of extreme fire events in the Baikal region. An area of 127 000 km 2 burned in this region in 2003, a large part of it in regions underlain by permafrost. Analyses of satellite data for 2002–2009 indicate that previous-summer surface moisture is a better predictor for burned area than precipitation anomalies or fire weather indices for larch forests with continuous permafrost. Our analysis advances the understanding of complex interactions between the atmosphere, vegetation and soil, and how coupled mechanisms can lead to extreme events. These findings emphasize the importance of a mechanistic coupling of soil thermodynamics, hydrology, vegetation functioning, and fire activity in Earth system models for projecting climate change impacts over the next century. (letter)

  17. Tenskinmetric Evaluation of Surface Energy Changes in Adult Skin: Evidence from 834 Normal Subjects Monitored in Controlled Conditions

    Directory of Open Access Journals (Sweden)

    Camilla Dal Bosco

    2014-03-01

    Full Text Available To evaluate the influence of the skin aging critical level on the adult skin epidermal functional state, an improved analytical method based on the skin surface energetic measurement (TVS modeling was developed. Tenskinmetric measurements were carried out non-invasively in controlled conditions by contact angle method using only a water-drop as reference standard liquid. Adult skin was monitored by TVS Observatory according to a specific and controlled thermal protocol (Camianta protocol in use at the interconnected “Mamma Margherita Terme spa” of Terme Euganee. From June to November 2013, the surface free energy and the epidermal hydration level of adult skin were evaluated on arrival of 265 male and 569 female adult volunteers (51–90 years of age and when they departed 2 weeks later. Sensitive measurements were carried out at 0.1 mN/m. High test compliance was obtained (93.2% of all guests. Very interesting results are obtained. The high sensitivity and discrimination power of tenskinmetry combined with a thermal Camianta protocol demonstrate the possibility to evaluate at baseline level the surface energetic changes and the skin reactivity which occurs on adult skin.

  18. The effect of surface pre-conditioning treatments on the local composition of Zr-based conversion coatings formed on aluminium alloys

    Science.gov (United States)

    Cerezo, J.; Vandendael, I.; Posner, R.; de Wit, J. H. W.; Mol, J. M. C.; Terryn, H.

    2016-03-01

    This study investigates the effect of different alkaline, acidic and thermal pre-conditioning treatments applied to different Al alloy surfaces. The obtained results are compared to the characteristics of Zr-based conversion coatings that were subsequently generated on top of these substrates. Focus is laid on typical elemental distributions on the sample surfaces, in particular on the amount of precipitated functional additives such as Cu species that are present in the substrate matrix as well as in the conversion bath solutions. To this aim, Field Emission Auger Electron spectra, depth profiles and surface maps with superior local resolution were acquired and compared to scanning electron microscopy images of the sample. The results show how de-alloying processes, which occur at and around intermetallic particles in the Al matrix during typical industrial alkaline or acidic cleaning procedures, provide a significant source of crystallization cores for any following coating processes. This is in particular due for Cu-species, as the resulting local Cu structures on the surface strongly affect the film formation and compositions of state-of-the-art Zr-based films. The findings are highly relevant for industrial treatments of aluminium surfaces, especially for those that undergo corrosion protection and painting process steps prior to usage.

  19. Influence of growth conditions on adhesion of yeast Candida spp. and Pichia spp. to stainless steel surfaces.

    Science.gov (United States)

    Tomičić, Ružica; Raspor, Peter

    2017-08-01

    An understanding of adhesion behavior of Candida and Pichia yeast under different environmental conditions is key to the development of effective preventive measures against biofilm-associated infection. Hence in this study we investigated the impact of growth medium and temperature on Candida and Pichia adherence using stainless steel (AISI 304) discs with different degrees of surface roughness (Ra = 25.20-961.9 nm), material typical for the food processing industry as well as medical devices. The adhesion of the yeast strains to stainless steel surfaces grown in Malt Extract broth (MEB) or YPD broth at three temperatures (7 °C, 37 °C, 43 °C for Candida strains and 7 °C, 27 °C, 32 °C for Pichia strains) was assessed by crystal violet staining. The results showed that the nutrient content of medium significantly influenced the quantity of adhered cells by the tested yeasts. Adhesion of C. albicans and C. glabrata on stainless steel surfaces were significantly higher in MEB, whereas for C. parapsilosis and C. krusei it was YPD broth. In the case with P. pijperi and P. membranifaciens, YPD broth was more effective in promoting adhesion than MEB. On the other hand, our data indicated that temperature is a very important factor which considerably affects the adhesion of these yeast. There was also significant difference in cell adhesion on all types of stainless steel surfaces for all tested yeast. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Do morphometric parameters and geological conditions determine chemistry of glacier surface ice? Spatial distribution of contaminants present in the surface ice of Spitsbergen glaciers (European Arctic).

    Science.gov (United States)

    Lehmann, Sara; Gajek, Grzegorz; Chmiel, Stanisław; Polkowska, Żaneta

    2016-12-01

    The chemism of the glaciers is strongly determined by long-distance transport of chemical substances and their wet and dry deposition on the glacier surface. This paper concerns spatial distribution of metals, ions, and dissolved organic carbon, as well as the differentiation of physicochemical parameters (pH, electrical conductivity) determined in ice surface samples collected from four Arctic glaciers during the summer season in 2012. The studied glaciers represent three different morphological types: ground based (Blomlibreen and Scottbreen), tidewater which evolved to ground based (Renardbreen), and typical tidewater glacier (Recherchebreen). All of the glaciers are functioning as a glacial system and hence are subject to the same physical processes (melting, freezing) and the process of ice flowing resulting from the cross-impact force of gravity and topographic conditions. According to this hypothesis, the article discusses the correlation between morphometric parameters, changes in mass balance, geological characteristics of the glaciers and the spatial distribution of analytes on the surface of ice. A strong correlation (r = 0.63) is recorded between the aspect of glaciers and values of pH and ions, whereas dissolved organic carbon (DOC) depends on the minimum elevation of glaciers (r = 0.55) and most probably also on the development of the accumulation area. The obtained results suggest that although certain morphometric parameters largely determine the spatial distribution of analytes, also the geology of the bed of glaciers strongly affects the chemism of the surface ice of glaciers in the phase of strong recession.

  1. Pavement Condition Assessment Using IRI from Roadroid and Surface Distress Index Method on National Road in Sumenep Regency

    Science.gov (United States)

    Arianto, T.; Suprapto, M.; Syafi’i

    2018-03-01

    The pavement condition will decrease due to the influence of traffic and environment, so that the maintenance effort is needed to maintain the road condition during the service period. In order to carry out road maintenance activities right on target, there needs to be a plan based on accurate pavement condition data. Road roughness is the most commonly used condition parameter in evaluating pavement conditions objectively because road roughness data is relatively easy to obtain, well correlated with vehicle operating costs and the most relevant parameter in road functional performance measurement. The Roadroid is an Android-based application that measures road roughness by using vibration sensors on a smartphone so it is possible to get an International Roughness Index (IRI) value as an indicator of pavement conditions more easily and efficiently. Besides based on road roughness, pavement condition evaluation can also be done visually by using Surface Distress Index (SDI) method that uses the total crack area parameters, average crack width, total number of potholes and the average depth of rutting. This study attempts to assess the condition of Jenderal Sudirman-Kalianget road by combining IRI Roadroid value and SDI value which will be used as the basis to determine the required road maintenance. This road segment is one of the national strategic road connecting the center of Sumenep regency with the Kalianget harbor. Based on IRI measurement and SDI calculation, the pavement condition of Jenderal Sudirman-Kalianget road can be described 4.2 kilometers (37.17%) were good and 2.3 kilometers (20.35%) were fair that need routine maintenance. While 2.1 kilometers (18.58%) were bad and 2.7 kilometers (23.89%) were poor that need periodical maintenance and reconstruction.

  2. Optimizing the conditions for hydrothermal liquefaction of barley straw for bio-crude oil production using response surface methodology

    DEFF Research Database (Denmark)

    Zhu, Zhe; Rosendahl, Lasse Aistrup; Toor, Saqib Sohail

    2018-01-01

    The present paper examines the conversion of barley straw to bio-crude oil (BO) via hydrothermal liquefaction. Response surface methodology based on central composite design was utilized to optimize the conditions of four independent variables including reaction temperature (factor X1, 260-340 oC...... phenols and their derivatives, acids, aromatic hydrocarbon, ketones, N-contained compounds and alcohols, which makes it a promising material in the applications of either bio-fuel or as a phenol substitute in bio-phenolic resins....

  3. Adherence to abiotic surface induces SOS response in Escherichia coli K-12 strains under aerobic and anaerobic conditions.

    Science.gov (United States)

    Costa, Suelen B; Campos, Ana Carolina C; Pereira, Ana Claudia M; de Mattos-Guaraldi, Ana Luiza; Júnior, Raphael Hirata; Rosa, Ana Cláudia P; Asad, Lídia M B O

    2014-09-01

    During the colonization of surfaces, Escherichia coli bacteria often encounter DNA-damaging agents and these agents can induce several defence mechanisms. Base excision repair (BER) is dedicated to the repair of oxidative DNA damage caused by reactive oxygen species (ROS) generated by chemical and physical agents or by metabolism. In this work, we have evaluated whether the interaction with an abiotic surface by mutants derived from E. coli K-12 deficient in some enzymes that are part of BER causes DNA damage and associated filamentation. Moreover, we studied the role of endonuclease V (nfi gene; 1506 mutant strain) in biofilm formation. Endonuclease V is an enzyme that is involved in DNA repair of nitrosative lesions. We verified that endonuclease V is involved in biofilm formation. Our results showed more filamentation in the xthA mutant (BW9091) and triple xthA nfo nth mutant (BW535) than in the wild-type strain (AB1157). By contrast, the mutant nfi did not present filamentation in biofilm, although its wild-type strain (1466) showed rare filaments in biofilm. The filamentation of bacterial cells attaching to a surface was a consequence of SOS induction measured by the SOS chromotest. However, biofilm formation depended on the ability of the bacteria to induce the SOS response since the mutant lexA Ind(-) did not induce the SOS response and did not form any biofilm. Oxygen tension was an important factor for the interaction of the BER mutants, since these mutants exhibited decreased quantitative adherence under anaerobic conditions. However, our results showed that the presence or absence of oxygen did not affect the viability of BW9091 and BW535 strains. The nfi mutant and its wild-type did not exhibit decreased biofilm formation under anaerobic conditions. Scanning electron microscopy was also performed on the E. coli K-12 strains that had adhered to the glass, and we observed the presence of a structure similar to an extracellular matrix that depended on the

  4. DIAGNOSTICS OF WORKPIECE SURFACE CONDITION BASED ON CUTTING TOOL VIBRATIONS DURING MACHINING

    Directory of Open Access Journals (Sweden)

    Jerzy Józwik

    2015-05-01

    Full Text Available The paper presents functional relationships between surface geometry parameters, feed and vibrations level in the radial direction of the workpiece. Time characteristics of the acceleration of cutting tool vibration registered during C45 steel and stainless steel machining for separate axes (X, Y, Z were presented as a function of feedrate f. During the tests surface geometric accuracy assessment was performed and 3D surface roughness parameters were determined. The Sz parameter was selected for the analysis, which was then collated with RMS vibration acceleration and feedrate f. The Sz parameter indirectly provides information on peak to valley height and is characterised by high generalising potential i.e. it is highly correlated to other surface and volume parameters of surface roughness. Test results presented in this paper may constitute a valuable source of information considering the influence of vibrations on geometric accuracy of elements for engineers designing technological processes.

  5. The dependence of sea surface slope on atmospheric stability and swell conditions

    Science.gov (United States)

    Hwang, Paul A.; Shemdin, Omar H.

    1988-01-01

    A tower-mounted optical device is used to measure the two-orthogonal components of the sea surface slope. The results indicate that an unstable stratification at the air-sea interface tends to enhance the surface roughness. The presence of a long ocean swell system steers the primary direction of shortwave propagation away from wind direction, and may increase or reduce the mean square slope of the sea surface.

  6. Optimization of fermentation conditions for 1,3-propanediol production by marine Klebsiella pneumonia HSL4 using response surface methodology

    Science.gov (United States)

    Li, Lili; Zhou, Sheng; Ji, Huasong; Gao, Ren; Qin, Qiwei

    2014-09-01

    The industrially important organic compound 1,3-propanediol (1,3-PDO) is mainly used as a building block for the production of various polymers. In the present study, response surface methodology protocol was followed to determine and optimize fermentation conditions for the maximum production of 1,3-PDO using marine-derived Klebsiella pneumoniae HSL4. Four nutritional supplements together with three independent culture conditions were optimized as follows: 29.3 g/L glycerol, 8.0 g/L K2 HPO4, 7.6 g/L (NH4)2 SO4, 3.0 g/L KH2 PO4, pH 7.1, cultivation at 35°C for 12 h. Under the optimal conditions, a maximum 1,3-PDO concentration of 14.5 g/L, a productivity of 1.21 g/(L·h) and a conversion of glycerol of 0.49 g/g were obtained. In comparison with the control conditions, fermentation under the optimized conditions achieved an increase of 38.8% in 1,3-PDO concentration, 39.0% in productivity and 25.7% in glycerol conversion in flask. This enhancement trend was further confirmed when the fermentation was conducted in a 5-L fermentor. The optimized fermentation conditions could be an important basis for developing lowcost, large-scale methods for industrial production of 1,3-PDO in the future.

  7. Mars analog minerals' spectral reflectance characteristics under Martian surface conditions

    Science.gov (United States)

    Poitras, J. T.; Cloutis, E. A.; Salvatore, M. R.; Mertzman, S. A.; Applin, D. M.; Mann, P.

    2018-05-01

    We investigated the spectral reflectance properties of minerals under a simulated Martian environment. Twenty-eight different hydrated or hydroxylated phases of carbonates, sulfates, and silica minerals were selected based on past detection on Mars through spectral remote sensing data. Samples were ground and dry sieved to <45 μm grain size and characterized by XRD before and after 133 days inside a simulated Martian surface environment (pressure 5 Torr and CO2 fed). Reflectance spectra from 0.35 to 4 μm were taken periodically through a sapphire (0.35-2.5 μm) and zinc selenide (2.5-4 μm) window over a 133-day period. Mineral stability on the Martian surface was assessed through changes in spectral characteristics. Results indicate that the hydrated carbonates studied would be stable on the surface of Mars, only losing adsorbed H2O while maintaining their diagnostic spectral features. Sulfates were less stable, often with shifts in the band position of the SO, Fe, and OH absorption features. Silicas displayed spectral shifts related to SiOH and hydration state of the mineral surface, while diagnostic bands for quartz were stable. Previous detection of carbonate minerals based on 2.3-2.5 μm and 3.4-3.9 μm features appears to be consistent with our results. Sulfate mineral detection is more questionable since there can be shifts in band position related to SO4. The loss of the 0.43 μm Fe3+ band in many of the sulfates indicate that there are fewer potential candidates for Fe3+ sulfates to permanently exist on the Martian surface based on this band. The gypsum sample changed phase to basanite during desiccation as demonstrated by both reflectance and XRD. Silica on Mars has been detected using band depth ratio at 1.91 and 1.96 μm and band minimum position of the 1.4 μm feature, and the properties are also used to determine their age. This technique continues to be useful for positive silica identifications, however, silica age appears to be less consistent

  8. Estimation of surface absorptivity in laser surface heating process with experimental data

    International Nuclear Information System (INIS)

    Chen, H-T; Wu, X-Y

    2006-01-01

    This study applies a hybrid technique of the Laplace transform and finite-difference methods in conjunction with the least-squares method and experimental temperature data inside the test material to predict the unknown surface temperature, heat flux and absorptivity for various surface conditions in the laser surface heating process. In this study, the functional form of the surface temperature is unknown a priori and is assumed to be a function of time before performing the inverse calculation. In addition, the whole time domain is divided into several analysis sub-time intervals and then these unknown estimates on each analysis interval can be predicted. In order to show the accuracy of the present inverse method, comparisons are made among the present estimates, direct results and previous results, showing that the present estimates agree with the direct results for the simulated problem. However, the present estimates of the surface absorptivity deviate slightly from previous estimated results under the assumption of constant thermal properties. The effect of the surface conditions on the surface absorptivity and temperature is not negligible

  9. Analysis of progression of fatigue conditions in biceps brachii muscles using surface electromyography signals and complexity based features.

    Science.gov (United States)

    Karthick, P A; Makaram, Navaneethakrishna; Ramakrishnan, S

    2014-01-01

    Muscle fatigue is a neuromuscular condition where muscle performance decreases due to sustained or intense contraction. It is experienced by both normal and abnormal subjects. In this work, an attempt has been made to analyze the progression of muscle fatigue in biceps brachii muscles using surface electromyography (sEMG) signals. The sEMG signals are recorded from fifty healthy volunteers during dynamic contractions under well defined protocol. The acquired signals are preprocessed and segmented in to six equal parts for further analysis. The features, such as activity, mobility, complexity, sample entropy and spectral entropy are extracted from all six zones. The results are found showing that the extracted features except complexity feature have significant variations in differentiating non-fatigue and fatigue zone respectively. Thus, it appears that, these features are useful in automated analysis of various neuromuscular activities in normal and pathological conditions.

  10. Interaction of Strong Turbulence With Free Surfaces

    Science.gov (United States)

    Dalrymple, Robert A.

    Spray from a nozzle, spilling breakers, and “rooster tails” from speeding boats are all examples of a turbulent flow with a free surface. In many cases like these, the free surface is difficult to discern as the volume of air in the fluid can exceed that of the water.In traditional studies, the free surface is simply defined as a continuous surface separating the fluid from air. The pressure at the surface is assumed to be atmospheric pressure and the fluid comprising the surface moves with the surface. While these conditions are sufficient for non-turbulent flows, such as nonbreaking water waves, and lead to the (albeit non-linear) dynamic and kinematic free surface boundary conditions that serve to provide sufficient conditions to determine the surface, they are not valid descriptions for a bubbly free surface in a highly turbulent regime, such as the roller in front of a spilling breaker or the propeller wash behind a ship.

  11. Investigations of the surface tension of coal ash slags under gasification conditions; Untersuchungen zur Oberflaechenspannung von Kohleschlacken unter Vergasungsbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Melchior, Tobias

    2011-10-26

    In the context of CO{sub 2}-emission-induced global warming, greenhouse gases resulting from the production of electricity in coal-fired power plants gain increasing attention. One possible way to reduce such emissions is to gasify coal instead of burning it. The corresponding process is referred to as Integrated Gasification Combined Cycle and allows for the separation of CO{sub 2} before converting a synthesis gas into electrical energy. However, further improvements in efficiency and availability of this plant technology are needed to render the alternative generation of electricity sensible from an economic point of view. One corresponding approach introduces hot gas cleaning facilities to the gasification plant which guarantee a removal of slag particles from the synthesis gas at high temperatures. The development of such filters depends on the availability of data on the material properties of the coal ash slags to be withdrawn. In this respect, the surface tension is a relevant characteristic. Currently, the surface tension of real coal ash slags as well as of synthetic model systems was measured successfully by means of the sessile drop and the maximum bubble pressure method. With regard to the sessile drop technique, those experiments were conducted in a gasification-like atmosphere at temperatures of up to 1500 C. Furthermore, the pressure inside the experimental vessel was raised to 10 bar in order to allow for deriving the influence of this variable on the surface tension. In contrast, maximum bubble pressure trials were realised at atmospheric pressure while the gas atmosphere assured inert conditions. For performing sessile drop measurements, a corresponding apparatus was set up and is described in detail in this thesis. Three computer algorithms were employed to calculate surface tensions out of the photos of sessile drops and their individual performance was evaluated. A very good agreement between two of the codes was found while the third one

  12. Investigating ozone-induced decomposition of surface-bound permethrin for conditions in aircraft cabins.

    Science.gov (United States)

    Coleman, B K; Wells, J R; Nazaroff, W W

    2010-02-01

    The reaction of ozone with permethrin can potentially form phosgene. Published evidence on ozone levels and permethrin surface concentrations in aircraft cabins indicated that significant phosgene formation might occur in this setting. A derivatization technique was developed to detect phosgene with a lower limit of detection of 2 ppb. Chamber experiments were conducted with permethrin-coated materials (glass, carpet, seat fabric, and plastic) exposed to ozone under cabin-relevant conditions (150 ppb O(3), 4.5/h air exchange rate, means of material-balance modeling indicates that the upper limit on the phosgene level in aircraft cabins resulting from this chemistry is approximately 1 microg/m(3) or approximately 0.3 ppb. It was thus determined that phosgene formation, if it occurs in aircraft cabins, is not likely to exceed relevant, health-based phosgene exposure guidelines. Phosgene formation from ozone-initiated oxidation of permethrin in the aircraft cabin environment, if it occurs, is estimated to generate levels below the California Office of Environmental Health Hazard Assessment acute reference exposure level of 4 microg/m(3) or approximately 1 ppb.

  13. The effect of surface chemistry on particulate fouling under flow-boiling conditions

    International Nuclear Information System (INIS)

    Turner, C.W.; Klimas, S.J.

    2001-01-01

    A model of particulate fouling has been developed that takes account of the influence of deposit consolidation on the kinetics of the fouling process. Fouling kinetics predicted by the model are linear, falling-rate or asymptotic, depending on the relative magnitudes of the rate constants for deposition, re-entrainment, and consolidation. One of the key predictions of the model is that the steady-state fouling rate is proportional to the ratio Kλ c /λ, where K, λ c and λ are the rate constants for deposition, consolidation, and removal, respectively. Tests conducted in a high-temperature recirculating-water loop have demonstrated that chemistry exerts a strong influence on the fouling kinetics of particulate corrosion product under flow-boiling conditions in alkaline water at 270 o C. For example, the fouling rates of lepidocrocite and hematite are 12 and 50 times greater, respectively, than the rate for magnetite. It is argued that the difference can be attributed to the sign of the surface charge that develops on the metal oxide surfaces in the high-temperature coolant, which, in turn, is a function of pH relative to the isoelectric point of the metal oxide. Chemical effects also influence fouling behaviour through the rate of consolidation. For example, when morpholine is used for the alkalizing agent the fouling rate is 3-5 times higher than the case when the pH is controlled using dimethylamine. The difference is attributed to the rate of deposit consolidation, which is 6-20 times greater than the rate of deposit removal for morpholine compared to 0.2-0.3 times the rate of removal for dimethylamine. The results of this investigation, together with the insights provided by the fouling model, are being used to guide the selection of the alkalizing amine to optimize its properties for both corrosion (pH) control and deposit control in the steam generator. (author)

  14. Mapping of the seasonal dynamic properties of building walls in actual periodic conditions and effects produced by solar radiation incident on the outer and inner surfaces of the wall

    International Nuclear Information System (INIS)

    Mazzeo, D.; Oliveti, G.; Arcuri, N.

    2016-01-01

    Highlights: • Dynamic thermal behaviour of building walls subjected to actual periodic loadings. • Dynamic parameters of wall in terms of energy and of heat flux are defined. • Different solar absorption coefficients and orientations of wall are considered. • On the internal surface is present or absent a shortwave radiant field. • Seasonal thermal characteristics for different plant operating regime are provided. - Abstract: In this work, the dynamic characteristics of the external walls of air-conditioned buildings subject to the joint action of periodic non-sinusoidal external and internal loadings are determined. The dynamic parameters used are the energy decrement factor, which is evaluated by means of the fluctuating heat flux in a semi-period exiting and entering the wall, the decrement factor of the maximum peak and minimum peak of the heat flux in a period and the relative time lags. The fluctuating heat flux in the wall in steady periodic regime conditions is determined with an analytical model obtained by resolving the equivalent electrical circuit. The preceding parameters are used for a study of the influence of solar radiation on the dynamic characteristics of the walls in summer and winter air-conditioning. Solar radiation is considered as operating on the external surface and on the internal surface due to the presence in the indoor environments of a shortwave radiant field. The absorbed solar heat flux by the external surface varies, modifying the solar absorption coefficient and wall orientation. Indoors, we considered a continuous operating regime of the plant and a regime with nocturnal attenuation. The results obtained, relating to 1152 different boundary conditions, were used for the construction of maps of dynamic characteristics, different on variation of the plant functioning regime and of the shortwave radiant load on the internal surface. The maps show the dependence of the decrement factors and of the time lags on variation of

  15. Equivalence of chain conformations in the surface region of a polymer melt and a single Gaussian chain under critical conditions.

    Science.gov (United States)

    Skvortsov, A M; Leermakers, F A M; Fleer, G J

    2013-08-07

    In the melt polymer conformations are nearly ideal according to Flory's ideality hypothesis. Silberberg generalized this statement for chains in the interfacial region. We check the Silberberg argument by analyzing the conformations of a probe chain end-grafted at a solid surface in a sea of floating free chains of concentration φ by the self-consistent field (SCF) method. Apart from the grafting, probe chain and floating chains are identical. Most of the results were obtained for a standard SCF model with freely jointed chains on a six-choice lattice, where immediate step reversals are allowed. A few data were generated for a five-choice lattice, where such step reversals are forbidden. These coarse-grained models describe the equilibrium properties of flexible atactic polymer chains at the scale of the segment length. The concentration was varied over the whole range from φ = 0 (single grafted chain) to φ = 1 (probe chain in the melt). The number of contacts with the surface, average height of the free end and its dispersion, average loop and train length, tail size distribution, end-point and overall segment distributions were calculated for a grafted probe chain as a function of φ, for several chain lengths and substrate∕polymer interactions, which were varied from strong repulsion to strong adsorption. The computations show that the conformations of the probe chain in the melt do not depend on substrate∕polymer interactions and are very similar to the conformations of a single end-grafted chain under critical conditions, and can thus be described analytically. When the substrate∕polymer interaction is fixed at the value corresponding to critical conditions, all equilibrium properties of a probe chain are independent of φ, over the whole range from a dilute solution to the melt. We believe that the conformations of all flexible chains in the surface region of the melt are close to those of an appropriate single chain in critical conditions, provided

  16. Computer analysis of the significance of surface boundary conditions on the collection of α-induced charge

    International Nuclear Information System (INIS)

    Terrill, K.W.; Hu, C.; Neureuther, A.R.; California Univ., Berkeley

    1983-01-01

    The collection of α-particle generated charge by collectors surrounded by either uniform reflecting or uniform absorbing surfaces are compared as the two extreme cases of any real condition in IC's. The comparison for varying α-particle energies and collector sizes indicates that the differences in collected charge for the two cases is less than a factor of two if the α-particle strike is through the center of the collector. It is shown that variation of collected charge with feature length is approximately linear in both cases. The effect of scaling on soft errors in static RAM's is discussed. It is assumed that the charge transport is by diffusion only. (author)

  17. Temperature distribution of a water droplet moving on a heated super-hydrophobic surface under the icing condition

    Science.gov (United States)

    Yamazaki, Masafumi; Sumino, Yutaka; Morita, Katsuaki

    2017-11-01

    In the aviation industry, ice accretion on the airfoil has been a hazardous issue since it greatly declines the aerodynamic performance. Electric heaters and bleed air, which utilizes a part of gas emissions from engines, are used to prevent the icing. Nowadays, a new de-icing system combining electric heaters and super hydrophobic coatings have been developed to reduce the energy consumption. In the system, the heating temperature and the coating area need to be adjusted. Otherwise, the heater excessively consumes energy when it is set too high and when the coating area is not properly located, water droplets which are once dissolved possibly adhere again to the rear part of the airfoil as runback ice In order to deal with these problems, the physical phenomena of water droplets on the hydrophobic surface demand to be figured out. However, not many investigations focused on the behavior of droplets under the icing condition have been conducted. In this research, the temperature profiling of the rolling droplet on a heated super-hydrophobic surface is experimentally observed by the dual luminescent imaging.

  18. How Does the Gibbs Inequality Condition Affect the Stability and Detachment of Floating Spheres from the Free Surface of Water?

    Science.gov (United States)

    Feng, Dong-xia; Nguyen, Anh V

    2016-03-01

    Floating objects on the air-water interfaces are central to a number of everyday activities, from walking on water by insects to flotation separation of valuable minerals using air bubbles. The available theories show that a fine sphere can float if the force of surface tension and buoyancies can support the sphere at the interface with an apical angle subtended by the circle of contact being larger than the contact angle. Here we show that the pinning of the contact line at the sharp edge, known as the Gibbs inequality condition, also plays a significant role in controlling the stability and detachment of floating spheres. Specifically, we truncated the spheres with different angles and used a force sensor device to measure the force of pushing the truncated spheres from the interface into water. We also developed a theoretical modeling to calculate the pushing force that in combination with experimental results shows different effects of the Gibbs inequality condition on the stability and detachment of the spheres from the water surface. For small angles of truncation, the Gibbs inequality condition does not affect the sphere detachment, and hence the classical theories on the floatability of spheres are valid. For large truncated angles, the Gibbs inequality condition determines the tenacity of the particle-meniscus contact and the stability and detachment of floating spheres. In this case, the classical theories on the floatability of spheres are no longer valid. A critical truncated angle for the transition from the classical to the Gibbs inequality regimes of detachment was also established. The outcomes of this research advance our understanding of the behavior of floating objects, in particular, the flotation separation of valuable minerals, which often contain various sharp edges of their crystal faces.

  19. Kinematical Compatibility Conditions for Vorticity Across Shock Waves

    Science.gov (United States)

    Baty, Roy

    2015-11-01

    This work develops the general kinematical compatibility conditions for vorticity across arbitrary shock waves in compressible, inviscid fluids. The vorticity compatibility conditions are derived from the curl of the momentum equation using singular distributions defined on two-dimensional shock wave surfaces embedded in three-dimensional flow fields. The singular distributions are represented as generalized differential operators concentrated on moving shock wave surfaces. The derivation of the compatibility conditions for vorticity requires the application of second-order generalized derivatives and elementary tensor algebra. The well-known vorticity jump conditions across a shock wave are then shown to follow from the general kinematical compatibility conditions for vorticity by expressing the flow field velocity in vectorial components normal and tangential to a shock surface.

  20. Effects of endodontic post surface treatment, dentin conditioning, and artificial aging on the retention of glass fiber-reinforced composite resin posts.

    Science.gov (United States)

    Albashaireh, Zakereyya S; Ghazal, Muhamad; Kern, Matthias

    2010-01-01

    Several post surface treatments with or without the application of a bonding agent have been recommended to improve the bond strength of resin cements to posts. A regimen that produces the maximum bond strength of glass fiber-reinforced composite resin posts has not been verified. The purpose of this study was to evaluate the influence of post surface conditioning methods and artificial aging on the retention and microleakage of adhesively luted glass fiber-reinforced composite resin posts. Seventy-two endodontically treated single-rooted teeth were prepared for glass fiber-reinforced composite resin posts. The posts were submitted to 3 different surface treatments (n=24), including no treatment, etching with phosphoric acid, and airborne-particle abrasion. Subgroups of the posts (n=8) were then allocated for 3 different experimental conditions: no artificial aging, no bonding agent; no artificial aging, bonding agent; or artificial aging, bonding agent. The posts were luted with resin cement (Calibra). Post retention was measured in tension at a crosshead speed of 2 mm/min. The posts assigned for microleakage investigation were placed in fuchsin dye for 72 hours. The dislodged posts and the post spaces were examined microscopically to evaluate the mode of failure and explore the microleakage. Data were analyzed by 2-way ANOVA followed by Tukey HSD test (alpha=.05). The mean (SD) retention values for test groups ranged from 269 (63.8) to 349 (52.2) N. The retention values of the airborne-particle-abrasion group were significantly higher than those of the acidic-treatment and no-treatment groups. The application of bonding agent on the post surface produced no significant influence on retention. The mean retention values after artificial aging were significantly higher than without artificial aging. Microscopic evaluation demonstrated that the failure mode was primarily mixed. Treating the surface of the posts with phosphoric acid for 15 seconds before cementation

  1. Trapped surfaces in spherical stars

    International Nuclear Information System (INIS)

    Bizon, P.; Malec, E.; O'Murchadha, N.

    1988-01-01

    We give necessary and sufficient conditions for the existence of trapped surfaces in spherically symmetric spacetimes. These conditions show that the formation of trapped surfaces depends on both the degree of concentration and the average flow of the matter. The result can be considered as a partial validation of the cosmic-censorship hypothesis

  2. Occurrence and behavior of butyltins in intertidal and shallow subtidal surface sediments of an estuarine beach under different sampling conditions

    Science.gov (United States)

    Santos, Dayana Moscardi dos; Sant'Anna, Bruno Sampaio; Sandron, Daniela Corsino; Cardoso de Souza, Sara; Cristale, Joyce; Marchi, Mary Rosa Rodrigues de; Turra, Alexander

    2010-07-01

    Contamination by butyltin compounds (BTs) has been reported in estuarine environments worldwide, with serious impacts on the biota of these areas. Considering that BTs can be degraded by varying environmental conditions such as incident light and salinity, the short-term variations in such factors may lead to inaccurate estimates of BTs concentrations in nature. Therefore, the present study aimed to evaluate the possibility that measurements of BTs in estuarine sediments are influenced by different sampling conditions, including period of the day (day or night), tidal zone (intertidal or subtidal), and tides (high or low). The study area is located on the Brazilian southeastern coast, São Vicente Estuary, at Pescadores Beach, where BT contamination was previously detected. Three replicate samples of surface sediment were collected randomly in each combination of period of the day, tidal zone, and tide condition, from three subareas along the beach, totaling 72 samples. BTs were analyzed by GC-PFPD using a tin filter and a VF-5 column, by means of a validated method. The concentrations of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) ranged from undetectable to 161 ng Sn g -1 (d.w.). In most samples (71%), only MBT was quantifiable, whereas TBTs were measured in only 14, suggesting either an old contamination or rapid degradation processes. DBT was found in 27 samples, but could be quantified in only one. MBT concentrations did not differ significantly with time of day, zones, or tide conditions. DBT and TBT could not be compared under all these environmental conditions, because only a few samples were above the quantification limit. Pooled samples of TBT did not reveal any difference between day and night. These results indicated that, in assessing contamination by butyltin compounds, surface-sediment samples can be collected in any environmental conditions. However, the wide variation of BTs concentrations in the study area, i.e., over a very small

  3. Influence of growth conditions and surface reaction byproducts on GaN grown via metal organic molecular beam epitaxy: Toward an understanding of surface reaction chemistry

    Science.gov (United States)

    Pritchett, David; Henderson, Walter; Burnham, Shawn D.; Doolittle, W. Alan

    2006-04-01

    The surface reaction byproducts during the growth of GaN films via metal organic molecular beam epitaxy (MOMBE) were investigated as a means to optimize material properties. Ethylene and ethane were identified as the dominant surface reaction hydrocarbon byproducts, averaging 27.63% and 7.15% of the total gas content present during growth. Intense ultraviolet (UV) photoexcitation during growth was found to significantly increase the abundance of ethylene and ethane while reducing the presence of H2 and N2. At 920°C, UV excitation was shown to enhance growth rate and crystalline quality while reducing carbon incorporation. Over a limited growth condition range, a 4.5×1019-3.4×1020 cm-3 variation in carbon incorporation was achieved at constant high vacuum. Coupled with growth rate gains, UV excitation yielded films with ˜58% less integrated carbon content. Structural material property variations are reported for various ammonia flows and growth temperatures. The results suggest that high carbon incorporation can be achieved and regulated during MOMBE growth and that in-situ optimization through hydrocarbon analysis may provide further enhancement in the allowable carbon concentration range.

  4. Target surface condition during reactive glow discharge sputtering of copper

    International Nuclear Information System (INIS)

    Depla, D; Haemers, J; Gryse, R De

    2002-01-01

    During reactive glow discharge sputtering of copper in an argon/nitrogen plasma, we noticed an abrupt change of the target voltage and the deposition rate when the nitrogen concentration in the plasma exceeds a critical value. To explain this behaviour, the target surface after reactive glow discharge sputtering was examined by x-ray photoelectron spectroscopy (XPS). An experimental arrangement was constructed that allows direct transfer of the glow discharge cathode to the XPS analysis chamber without air exposure. These XPS measurements revealed that several different chemical states of nitrogen are present in the layer that forms on the target surface. The relative concentration of these different states changes when the critical nitrogen concentration in the plasma is exceeded

  5. Wall conditioning and plasma surface interactions in DIII-D

    International Nuclear Information System (INIS)

    Jackson, G.L.; Petersen, P.I.; Schaffer, M.S.; Taylor, P.L.; Taylor, T.S.; Doyle, B.L.; Walsh, D.S.; Hill, D.N.; Hsu, W.L.; Winter, J.

    1990-09-01

    Wall conditioning is used in DIII-D for both reduction of impurity influxes and particle control. The methods used include: baking, pulsed discharge cleaning, hydrogen glow cleaning, helium and neon glow conditioning, and carbonization. Helium glow wall conditioning applied before every tokamak discharge has been effective in impurity removal and particle control and has significantly expanded the parameter space in which DIII-D operates to include limiter and ohmic H-mode discharges and higher β T at low q. The highest values of divertor plasma current (3.0 MA) and stored energy (3.6 MJ) and peaked density profiles in H-mode discharges have been observed after carbonization. Divertor physics studies in DIII-D include sweeping the X-point to reduce peak heat loads, measurement of particle and heat fluxes in the divertor region, and erosion studies. The DIII-D Advanced Divertor has been installed and bias and baffle experiments will begin in the fall of 1991. 15 refs., 4 figs

  6. Effects of Thermal Radiation and Chemical Reaction on MHD Free Convection Flow past a Flat Plate with Heat Source and Convective Surface Boundary Condition

    OpenAIRE

    E.Hemalatha; N. Bhaskar Reddy

    2015-01-01

    This paper analyzes the radiation and chemical reaction effects on MHD steady two-dimensional laminar viscous incompressible radiating boundary layer flow over a flat plate in the presence of internal heat generation and convective boundary condition. It is assumed that lower surface of the plate is in contact with a hot fluid while a stream of cold fluid flows steadily over the upper surface with a heat source that decays exponentially. The Rosseland approximation is used to desc...

  7. Long-range surface plasmon resonance sensor with liquid micro-channels to maintain the symmetry condition of the refractive index

    International Nuclear Information System (INIS)

    Kan, Tetsuo; Kojo, Hiroyuki; Iwase, Eiji; Matsumoto, Kiyoshi; Shimoyama, Isao

    2010-01-01

    We propose a method to maintain the symmetry of the refractive index with respect to an Au film, in which the refractive indices are the same near both surfaces of the Au film, for LRSPR (long-range surface plasmon resonance) sensors. Maintenance of the symmetry is necessary for exciting the LRSPR mode. However, because the buffer layer under the Au film is usually made of a solid dielectric material with a constant refractive index, the quality of the measurement is reduced when the refractive index of the analyte used is dramatically different from that of the buffer layer. To solve this problem, the proposed sensor is equipped with liquid channels under the Au film. The Au film used in this study was supported by a thin (100 nm) polymer film forming parallel, one-dimensional liquid channels with a 29 µm pitch. Because the analyte solution flows in the channels, both surfaces of the Au film face the same analyte. Thus, this configuration automatically satisfies the symmetry condition for analytes with a wide range of refractive indices. We examined the validity of the sensor and compared it to that of a conventional sensor by measuring the LRSPR for five analyte solutions with different refractive indices. LRSPR dips were clearly observed for all of the analytes tested. The dip of the conventional LRSPR sensor became shallow when the refractive index increased, with the final dip depth being 65% of the initial dip depth for a refractive index of 1.358. In contrast, the dip depth of the proposed LRSPR sensor remained constant over the entire measured refractive index range of 1.331 to 1.358. These results indicate that the proposed sensor maintains the symmetry condition and confirm that the proposed method is effective for highly sensitive LRSPR measurements for a wide variety of analyte species

  8. Analysis of the incompressible Navier-Stokes equations with a quasi free-surface condition

    NARCIS (Netherlands)

    E.H. van Brummelen (Harald)

    1999-01-01

    textabstractNumerical solution of free-surface flows with a free-surface that can be represented by a height-function, is of great practical importance. Dedicated methods have been developed for the efficient solution of steady free-surface potential flow. These methods solve a sequence of

  9. Oxygen accumulation on metal surfaces investigated by XPS, AES and LEIS, an issue for sputter depth profiling under UHV conditions

    Energy Technology Data Exchange (ETDEWEB)

    Steinberger, R., E-mail: roland.steinberger@jku.at [Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Celedón, C.E., E-mail: carlos.celedon@usm.cl [Institut für Experimentalphysik, Abteilung für Atom- und Oberflächenphysik, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Departamento de Física, Universidad Técnica Federico Santa María, Valaparaíso, Casilla 110-V (Chile); Bruckner, B., E-mail: barbara.bruckner@jku.at [Institut für Experimentalphysik, Abteilung für Atom- und Oberflächenphysik, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Roth, D., E-mail: dietmar.roth@jku.at [Institut für Experimentalphysik, Abteilung für Atom- und Oberflächenphysik, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Duchoslav, J., E-mail: jiri.duchoslav@jku.at [Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); Arndt, M., E-mail: martin.arndt@voestalpine.com [voestalpine Stahl GmbH, voestalpine-Straße 3, 4031 Linz (Austria); Kürnsteiner, P., E-mail: p.kuernsteiner@mpie.de [Center for Surface and Nanoanalytics, Johannes Kepler University Linz, Altenberger Straße 69, 4040 Linz (Austria); and others

    2017-07-31

    Highlights: • Investigation on the impact of residual gas prevailing in UHV chambers. • For some metals detrimental oxygen uptake could be observed within shortest time. • Totally different behavior was found: no changes, solely adsorption and oxidation. • The UHV residual gas may severely corrupt results obtained from depth profiling. • A well-considered data acquisition sequence is the key for reliable depth profiles. - Abstract: Depth profiling using surface sensitive analysis methods in combination with sputter ion etching is a common procedure for thorough material investigations, where clean surfaces free of any contamination are essential. Hence, surface analytic studies are mostly performed under ultra-high vacuum (UHV) conditions, but the cleanness of such UHV environments is usually overrated. Consequently, the current study highlights the in principle known impact of the residual gas on metal surfaces (Fe, Mg, Al, Cr and Zn) for various surface analytics methods, like X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and low-energy ion scattering (LEIS). The investigations with modern, state-of-the-art equipment showed different behaviors for the metal surfaces in UHV during acquisition: (i) no impact for Zn, even after long time, (ii) solely adsorption of oxygen for Fe, slight and slow changes for Cr and (iii) adsorption accompanied by oxide formation for Al and Mg. The efficiency of different counter measures was tested and the acquired knowledge was finally used for ZnMgAl coated steel to obtain accurate depth profiles, which exhibited before serious artifacts when data acquisition was performed in an inconsiderate way.

  10. Effects of silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets

    Directory of Open Access Journals (Sweden)

    Saadet Atsü

    2011-06-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effects of tribochemical silica coating and silane surface conditioning on the bond strength of rebonded metal and ceramic brackets. MATERIAL AND METHODS: Twenty debonded metal and 20 debonded ceramic brackets were randomly assigned to receive one of the following surface treatments (n=10 for each group: (1 sandblasting (control; (2 tribochemical silica coating combined with silane. Brackets were rebonded to the enamel surface on the labial and lingual sides of premolars with a light-polymerized resin composite. All specimens were stored in distilled water for 1 week and then thermocycled (5,000 cycles between 5-55ºC. Shear bond strength values were measured using a universal testing machine. Student's t-test was used to compare the data (α=0.05. Failure mode was assessed using a stereomicroscope, and the treated and non-treated bracket surfaces were observed by scanning electron microscopy. RESULTS: Rebonded ceramic brackets treated with silica coating followed by silanization had significantly greater bond strength values (17.7±4.4 MPa than the sandblasting group (2.4±0.8 MPa, P<0.001. No significant difference was observed between the rebonded metal brackets treated with silica coating with silanization (15±3.9 MPa and the sandblasted brackets (13.6±3.9 MPa. Treated rebonded ceramic specimens primarily exhibited cohesive failure in resin and adhesive failure at the enamel-adhesive interface. CONCLUSIONS: In comparison to sandblasting, silica coating with aluminum trioxide particles followed by silanization resulted in higher bond strengths of rebonded ceramic brackets.

  11. 10 CFR 960.5-2-8 - Surface characteristics.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Surface characteristics. 960.5-2-8 Section 960.5-2-8... Closure § 960.5-2-8 Surface characteristics. (a) Qualifying condition. The site shall be located such that, considering the surface characteristics and conditions of the site and surrounding area, including surface...

  12. Water boiling on the corium melt surface under VVER severe accident conditions

    International Nuclear Information System (INIS)

    Bechta, S.V.; Vitol, S.A.; Krushinov, E.V.; Granovsky, V.S.; Sulatsky, A.A.; Khabensky, V.B.; Lopukh, D.B.; Petrov, Y.B.; Pechenkov, A.Y.

    2000-01-01

    Experimental results are presented on the interaction of corium melt with water supplied on its surface. The tests were conducted in the 'Rasplav-2' experimental facility. Corium melt was generated by induction melting in the cold crucible. The following data were obtained: heat transfer at boiling water-melt surface interaction, gas and aerosol release, post-interaction solidified corium structure. The corium melt charge had the following composition, mass%: 60% UO 2+x -16% ZrO 2 -15% Fe 2 O 3 -6% Cr 2 O 3 -3% Ni 2 O 3 . The melt surface temperature ranged within 1920-1970 K. (orig.)

  13. Water boiling on the corium melt surface under VVER severe accident conditions

    International Nuclear Information System (INIS)

    Bechta, S.V.; Vitol, S.A.; Krushinov, E.V.

    1999-01-01

    Experimental results are presented on the interaction between corium melt and water supplied onto its surface. The tests were conducted on the Rasplav-2' experimental facility. Induction melting in a cold crucible was used to produce the melt. The following data have been obtained: heat transfer at water boiling on the melt surface, aerosol release, structure of the post-interaction solidified corium. The corium melt had the following composition, mass %: 60%UO 2 - 16%ZrO 2 - 15%Fe 2 O 3 - 6%Cr 2 O 3 -3%Ni 2 O 3 . The melt surface temperature was 1650-1700degC. (author)

  14. Optimization extraction conditions for improving phenolic content and antioxidant activity in Berberis asiatica fruits using response surface methodology (RSM).

    Science.gov (United States)

    Belwal, Tarun; Dhyani, Praveen; Bhatt, Indra D; Rawal, Ranbeer Singh; Pande, Veena

    2016-09-15

    This study for the first time designed to optimize the extraction of phenolic compounds and antioxidant potential of Berberis asiatica fruits using response surface methodology (RSM). Solvent selection was done based on the preliminary experiments and a five-factors-three-level, Central Composite Design (CCD). Extraction temperature (X1), sample to solvent ratio (X3) and solvent concentration (X5) significantly affect response variables. The quadratic model well fitted for all the responses. Under optimal extraction conditions, the dried fruit sample mixed with 80% methanol having 3.0 pH in a ratio of 1:50 and the mixture was heated at 80 °C for 30 min; the measured parameters was found in accordance with the predicted values. High Performance Liquid Chromatography (HPLC) analysis at optimized condition reveals 6 phenolic compounds. The results suggest that optimization of the extraction conditions is critical for accurate quantification of phenolics and antioxidants in Berberis asiatica fruits, which may further be utilized for industrial extraction procedure. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Development of surface wettability characteristics for enhancing pool boiling heat transfer

    International Nuclear Information System (INIS)

    Kim, Moo Hwan; Jo, Hang Jin

    2010-05-01

    For several centuries, many boiling experiments have been conducted. Based on literature survey, the characteristic of heating surface in boiling condition played as an important role which mainly influenced to boiling performance. Among many surface factor, the fact that wettability effect is significant to not only the enhancement of critical heat flux(CHF) but also the nucleate boiling heat transfer is also supported by other kinds of boiling experiments. In this regard, the excellent boiling performance (a high CHF and heat transfer performance) in pool boiling could be achieved through some favorable surface modification which satisfies the optimized wettability condition. To find the optimized boiling condition, we design the special heaters to examine how two materials, which have different wettability (e.g. hydrophilic and hydrophobic), affect the boiling phenomena. The special heaters have hydrophobic dots on hydrophilic surface. The contact angle of hydrophobic surface is 120 .deg. to water at the room temperature. The contact angle of hydrophilic surface is 60 .deg. at same conditions. To conduct the experiment with new surface condition, we developed new fabrication method and design the pool boiling experimental apparatus. Through this facility, we can the higher CHF on pattern surface than that on hydrophobic surface, and the higher boiling heat transfer performance on pattern surface than that on hydrophilic surface. Based on this experimental results, we concluded that we proposed new heating surface condition and surface fabrication method to realize the best boiling condition by modified heating surface condition

  16. Plasma-polymerized perfluoro(methylcyclohexane) coating on ethylene propylene diene elastomer surface: Effect of plasma processing condition on the deposition kinetics, morphology and surface energy of the film

    International Nuclear Information System (INIS)

    Tran, N.D.; Dutta, N.K.; Choudhury, N. Roy

    2005-01-01

    Plasma polymerization of perfluoro (methylcyclohexane) was carried out under cold plasma process operated at 13.56 MHz to deposit pore-free, uniform, ultra-thin film on an ethylene propylene diene terpolymer (EPDM) substrate in a view to modify the surface characteristics. The plasma fluoropolymeric films were formed at different plasma treatment times (from 20 s to 16 min), applied powers (20 to 100 W) and precursor flow rates to produce high quality films in a controllable yet tunable fashion. Scanning electron microscopy was employed successfully to characterize the evolution of the morphological feature in the film and also to determine the thickness of the coating. The surface energy of the film was determined by sessile drop method using different solvents as probe liquids. It is observed that a pore-free homogeneous plasma polymer thin film is formed within 20 s of treatment time, however, the morphology of the film depends on the plasma processing conditions, such as plasma power, precursor flow rate and deposition time. With increased time and power at a constant flow rate, the morphology of the film progressively changes from flat smooth to globular and rough. The kinetics and activation energy of the plasma polymer film deposition process were also estimated. The surface energy of the EPDM substrate decreased dramatically with plasma coating, however, it appears to be independent of the treatment time

  17. Shell condition and survival of Puget Sound pteropods are impaired by ocean acidification conditions.

    Directory of Open Access Journals (Sweden)

    D Shallin Busch

    Full Text Available We tested whether the thecosome pteropod Limacina helicina from Puget Sound, an urbanized estuary in the northwest continental US, experiences shell dissolution and altered mortality rates when exposed to the high CO2, low aragonite saturation state (Ωa conditions that occur in Puget Sound and the northeast Pacific Ocean. Five, week-long experiments were conducted in which we incubated pteropods collected from Puget Sound in four carbon chemistry conditions: current summer surface (∼460-500 µatm CO2, Ωa≈1.59, current deep water or surface conditions during upwelling (∼760 and ∼1600-1700 µatm CO2, Ωa≈1.17 and 0.56, and future deep water or surface conditions during upwelling (∼2800-3400 µatm CO2, Ωa≈0.28. We measured shell condition using a scoring regime of five shell characteristics that capture different aspects of shell dissolution. We characterized carbon chemistry conditions in statistical analyses with Ωa, and conducted analyses considering Ωa both as a continuous dataset and as discrete treatments. Shell dissolution increased linearly as aragonite saturation state decreased. Discrete treatment comparisons indicate that shell dissolution was greater in undersaturated treatments compared to oversaturated treatments. Survival increased linearly with aragonite saturation state, though discrete treatment comparisons indicated that survival was similar in all but the lowest saturation state treatment. These results indicate that, under starvation conditions, pteropod survival may not be greatly affected by current and expected near-future aragonite saturation state in the NE Pacific, but shell dissolution may. Given that subsurface waters in Puget Sound's main basin are undersaturated with respect to aragonite in the winter and can be undersaturated in the summer, the condition and persistence of the species in this estuary warrants further study.

  18. Shell condition and survival of Puget Sound pteropods are impaired by ocean acidification conditions.

    Science.gov (United States)

    Busch, D Shallin; Maher, Michael; Thibodeau, Patricia; McElhany, Paul

    2014-01-01

    We tested whether the thecosome pteropod Limacina helicina from Puget Sound, an urbanized estuary in the northwest continental US, experiences shell dissolution and altered mortality rates when exposed to the high CO2, low aragonite saturation state (Ωa) conditions that occur in Puget Sound and the northeast Pacific Ocean. Five, week-long experiments were conducted in which we incubated pteropods collected from Puget Sound in four carbon chemistry conditions: current summer surface (∼460-500 µatm CO2, Ωa≈1.59), current deep water or surface conditions during upwelling (∼760 and ∼1600-1700 µatm CO2, Ωa≈1.17 and 0.56), and future deep water or surface conditions during upwelling (∼2800-3400 µatm CO2, Ωa≈0.28). We measured shell condition using a scoring regime of five shell characteristics that capture different aspects of shell dissolution. We characterized carbon chemistry conditions in statistical analyses with Ωa, and conducted analyses considering Ωa both as a continuous dataset and as discrete treatments. Shell dissolution increased linearly as aragonite saturation state decreased. Discrete treatment comparisons indicate that shell dissolution was greater in undersaturated treatments compared to oversaturated treatments. Survival increased linearly with aragonite saturation state, though discrete treatment comparisons indicated that survival was similar in all but the lowest saturation state treatment. These results indicate that, under starvation conditions, pteropod survival may not be greatly affected by current and expected near-future aragonite saturation state in the NE Pacific, but shell dissolution may. Given that subsurface waters in Puget Sound's main basin are undersaturated with respect to aragonite in the winter and can be undersaturated in the summer, the condition and persistence of the species in this estuary warrants further study.

  19. Non-equilibrium surface conditions and microstructural changes following pulsed laser irradiation and ion beam mixing of Ni overlayers on sintered alpha-SiC

    International Nuclear Information System (INIS)

    More, K.L.; Davis, R.F.

    1986-01-01

    Pulsed laser irradiation and ion beam mixing of thin Ni overlayers on sintered alpha-SiC have been investigated as potential surface modification techniques for the enhancement of the mechanical properties of the SiC. Each of these surface processing methods are nonequilibrium techniques; materials interactions can be induced at the specimen surface which are not possible with conventional thermal techniques. As a result of the surface modification, the physical properties of the ceramic can be altered under the correct processing conditions. Following laser irradiation using a pulsed ruby or krypton fluoride (KrF) excimer laser, the fracture strength of the SiC was increased by approximately 50 percent and 20 percent, respectively. However, ion-beam mixing of Ni on SiC resulted in no change in fracture strength. Cross-sectional transmission electron microscopy, scanning electron microscopy, secondary ion mass spectroscopy, and Rutherford backscattering techniques, have been used to characterize the extent of mixing between the Ni and SiC as a result of the surface modification and to determine the reason(s) for the observed changes in fracture strength. 19 references

  20. Optimization of functionalization conditions for protein analysis by AFM

    Energy Technology Data Exchange (ETDEWEB)

    Arroyo-Hernández, María, E-mail: maria.arroyo@ctb.upm.es [Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid (Spain); Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid (Spain); Daza, Rafael; Pérez-Rigueiro, Jose; Elices, Manuel; Nieto-Márquez, Jorge; Guinea, Gustavo V. [Centro de Tecnología Biomédica, Universidad Politécnica de Madrid, 28223 Pozuelo de Alarcón, Madrid (Spain); Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2014-10-30

    Highlights: • Highest fluorescence is obtained for central conditions. • Largest primary amine contribution is obtained for central conditions. • RMS roughness is smaller than 1 nm for all functional films. • Selected deposition conditions lead to proper RMS and functionality values. • LDH proteins adsorbed on AVS-films were observed by AFM. - Abstract: Activated vapor silanization (AVS) is used to functionalize silicon surfaces through deposition of amine-containing thin films. AVS combines vapor silanization and chemical vapor deposition techniques and allows the properties of the functionalized layers (thickness, amine concentration and topography) to be controlled by tuning the deposition conditions. An accurate characterization is performed to correlate the deposition conditions and functional-film properties. In particular, it is shown that smooth surfaces with a sufficient surface density of amine groups may be obtained with this technique. These surfaces are suitable for the study of proteins with atomic force microscopy.

  1. Mapping land water and energy balance relations through conditional sampling of remote sensing estimates of atmospheric forcing and surface states

    Science.gov (United States)

    Farhadi, Leila; Entekhabi, Dara; Salvucci, Guido

    2016-04-01

    In this study, we develop and apply a mapping estimation capability for key unknown parameters that link the surface water and energy balance equations. The method is applied to the Gourma region in West Africa. The accuracy of the estimation method at point scale was previously examined using flux tower data. In this study, the capability is scaled to be applicable with remotely sensed data products and hence allow mapping. Parameters of the system are estimated through a process that links atmospheric forcing (precipitation and incident radiation), surface states, and unknown parameters. Based on conditional averaging of land surface temperature and moisture states, respectively, a single objective function is posed that measures moisture and temperature-dependent errors solely in terms of observed forcings and surface states. This objective function is minimized with respect to parameters to identify evapotranspiration and drainage models and estimate water and energy balance flux components. The uncertainty of the estimated parameters (and associated statistical confidence limits) is obtained through the inverse of Hessian of the objective function, which is an approximation of the covariance matrix. This calibration-free method is applied to the mesoscale region of Gourma in West Africa using multiplatform remote sensing data. The retrievals are verified against tower-flux field site data and physiographic characteristics of the region. The focus is to find the functional form of the evaporative fraction dependence on soil moisture, a key closure function for surface and subsurface heat and moisture dynamics, using remote sensing data.

  2. Microclimatic conditions at the external surface of building envelopes

    Energy Technology Data Exchange (ETDEWEB)

    Kragh, M.K.

    1998-12-31

    The project is described, the motivation for the research and the microclimate is defined in relation to both building physics research and applications. Air temperatur, air humidity, solar radiation and air velocity are briefly considered, whilst driving rain and long-wave radiation are described in more detail. Convective heat transfer and surface coefficients are discussed, although they are not microclimatic factors, merely resulting from combinations of such factors. They are included as they are important in relation to transfer of heat and moisture at the surface of the building envelope. Driving rain measurement is the main area of interest, including development of measurement equipment. Long-wave irradiation is measured and compared with empirical formulae from the literature. Window convection heat transfer is another main area of interest. Nocturnal convective heat transfer from a double pane glazing is studied and measurement principles are discussed. Finally, a compilation of meteorological data for hygrothermal simulations, including estimation of driving rain, is described. System error estimation in relation to the window convection measurements, design notes on an apparatus for external convection measurement, formulae for conversion of relative humitity and dry-bulb temperature into dew point temperature. (EG) 66 refs.

  3. Microclimatic conditions at the external surface of building envelopes

    Energy Technology Data Exchange (ETDEWEB)

    Kragh, M K

    1999-12-31

    The project is described, the motivation for the research and the microclimate is defined in relation to both building physics research and applications. Air temperatur, air humidity, solar radiation and air velocity are briefly considered, whilst driving rain and long-wave radiation are described in more detail. Convective heat transfer and surface coefficients are discussed, although they are not microclimatic factors, merely resulting from combinations of such factors. They are included as they are important in relation to transfer of heat and moisture at the surface of the building envelope. Driving rain measurement is the main area of interest, including development of measurement equipment. Long-wave irradiation is measured and compared with empirical formulae from the literature. Window convection heat transfer is another main area of interest. Nocturnal convective heat transfer from a double pane glazing is studied and measurement principles are discussed. Finally, a compilation of meteorological data for hygrothermal simulations, including estimation of driving rain, is described. System error estimation in relation to the window convection measurements, design notes on an apparatus for external convection measurement, formulae for conversion of relative humitity and dry-bulb temperature into dew point temperature. (EG) 66 refs.

  4. Quantitative proteomic view on secreted, cell surface-associated, and cytoplasmic proteins of the methicillin-resistant human pathogen Staphylococcus aureus under iron-limited conditions.

    Science.gov (United States)

    Hempel, Kristina; Herbst, Florian-Alexander; Moche, Martin; Hecker, Michael; Becher, Dörte

    2011-04-01

    Staphylococcus aureus is capable of colonizing and infecting humans by its arsenal of surface-exposed and secreted proteins. Iron-limited conditions in mammalian body fluids serve as a major environmental signal to bacteria to express virulence determinants. Here we present a comprehensive, gel-free, and GeLC-MS/MS-based quantitative proteome profiling of S. aureus under this infection-relevant situation. (14)N(15)N metabolic labeling and three complementing approaches were combined for relative quantitative analyses of surface-associated proteins. The surface-exposed and secreted proteome profiling approaches comprise trypsin shaving, biotinylation, and precipitation of the supernatant. By analysis of the outer subproteomic and cytoplasmic protein fraction, 1210 proteins could be identified including 221 surface-associated proteins. Thus, access was enabled to 70% of the predicted cell wall-associated proteins, 80% of the predicted sortase substrates, two/thirds of lipoproteins and more than 50% of secreted and cytoplasmic proteins. For iron-deficiency, 158 surface-associated proteins were quantified. Twenty-nine proteins were found in altered amounts showing particularly surface-exposed proteins strongly induced, such as the iron-regulated surface determinant proteins IsdA, IsdB, IsdC and IsdD as well as lipid-anchored iron compound-binding proteins. The work presents a crucial subject for understanding S. aureus pathophysiology by the use of methods that allow quantitative surface proteome profiling.

  5. X-ray evaluation of residual stress distributions within surface machined layer generated by surface machining and sequential welding

    International Nuclear Information System (INIS)

    Taniguchi, Yuu; Okano, Shigetaka; Mochizuki, Masahito

    2017-01-01

    The excessive tensile residual stress generated by welding after surface machining may be an important factor to cause stress corrosion cracking (SCC) in nuclear power plants. Therefore we need to understand and control the residual stress distribution appropriately. In this study, residual stress distributions within surface machined layer generated by surface machining and sequential welding were evaluated by X-ray diffraction method. Depth directional distributions were also investigated by electrolytic polishing. In addition, to consider the effect of work hardened layer on the residual stress distributions, we also measured full width at half maximum (FWHM) obtained from X-ray diffraction. Testing material was a low-carbon austenitic stainless steel type SUS316L. Test specimens were prepared by surface machining with different cutting conditions. Then, bead-on-plate welding under the same welding condition was carried out on the test specimens with different surface machined layer. As a result, the tensile residual stress generated by surface machining increased with increasing cutting speed and showed nearly uniform distributions on the surface. Furthermore, the tensile residual stress drastically decreased with increasing measurement depth within surface machined layer. Then, the residual stress approached 0 MPa after the compressive value showed. FWHM also decreased drastically with increasing measurement depth and almost constant value from a certain depth, which was almost equal regardless of the machining condition, within surface machined layer in all specimens. After welding, the transverse distribution of the longitudinal residual stress varied in the area apart from the weld center according to machining conditions and had a maximum value in heat affected zone. The magnitude of the maximum residual stress was almost equal regardless of the machining condition and decreased with increasing measurement depth within surface machined layer. Finally, the

  6. The Impact of Biofilms upon Surfaces Relevant to an Intermediate Level Radioactive Waste Geological Disposal Facility under Simulated Near-Field Conditions

    Directory of Open Access Journals (Sweden)

    Christopher J. Charles

    2017-07-01

    Full Text Available The ability of biofilms to form on a range of materials (cementious backfill (Nirex Reference Vault Backfill (NRVB, graphite, and stainless steel relevant to potential UK intermediate level radioactive waste (ILW disposal concepts was investigated by exposing these surfaces to alkaliphilic flocs generated by mature biofilm communities. Flocs are aggregates of biofilm material that are able to act as a transport vector for the propagation of biofilms. In systems where biofilm formation was observed there was also a decrease in the sorption of isosaccharinic acids to the NRVB. The biofilms were composed of cells, extracellular DNA (eDNA, proteins, and lipids with a smaller polysaccharide fraction, which was biased towards mannopyranosyl linked carbohydrates. The same trend was seen with the graphite and stainless steel surfaces at these pH values, but in this case the biofilms associated with the stainless steel surfaces had a distinct eDNA basal layer that anchored the biofilm to the surface. At pH 13, no structured biofilm was observed, rather all the surfaces accumulated an indistinct organic layer composed of biofilm materials. This was particularly the case for the stainless steel coupons which accumulated relatively large quantities of eDNA. The results demonstrate that there is the potential for biofilm formation in an ILW-GDF provided an initiation source for the microbial biofilm is present. They also suggest that even when conditions are too harsh for biofilm formation, exposed surfaces may accumulate organic material such as eDNA.

  7. Water boiling on the corium melt surface under VVER severe accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V.; Vitol, S.A.; Krushinov, E.V.; Granovsky, V.S.; Sulatsky, A.A.; Khabensky, V.B. [Sci. Res. Technol. Inst., Leningrad (Russian Federation); Lopukh, D.B.; Petrov, Y.B.; Pechenkov, A.Y. [St. Petersburg Electrotechnical University (SPbEU), Prof. Popov st 5/3, St. Petersburg (Russian Federation)

    2000-01-01

    Experimental results are presented on the interaction of corium melt with water supplied on its surface. The tests were conducted in the 'Rasplav-2' experimental facility. Corium melt was generated by induction melting in the cold crucible. The following data were obtained: heat transfer at boiling water-melt surface interaction, gas and aerosol release, post-interaction solidified corium structure. The corium melt charge had the following composition, mass%: 60% UO{sub 2+x}-16% ZrO{sub 2}-15% Fe{sub 2}O{sub 3}-6% Cr{sub 2}O{sub 3}-3% Ni{sub 2}O{sub 3}. The melt surface temperature ranged within 1920-1970 K. (orig.)

  8. Water boiling on the corium melt surface under VVER severe accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V.; Vitol, S.A.; Krushinov, E.V. [Research Institute of Technology, Sosnovy Bor (NITI) (RU)] [and others

    1999-07-01

    Experimental results are presented on the interaction between corium melt and water supplied onto its surface. The tests were conducted on the Rasplav-2' experimental facility. Induction melting in a cold crucible was used to produce the melt. The following data have been obtained: heat transfer at water boiling on the melt surface, aerosol release, structure of the post-interaction solidified corium. The corium melt had the following composition, mass %: 60%UO{sub 2}- 16%ZrO{sub 2}- 15%Fe{sub 2}O{sub 3} - 6%Cr{sub 2}O{sub 3}-3%Ni{sub 2}O{sub 3}. The melt surface temperature was 1650-1700degC. (author)

  9. Dependence of Lunar Surface Charging on Solar Wind Plasma Conditions and Solar Irradiation

    Science.gov (United States)

    Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.; Burchill, J. K.; Collier, M. R.; Zimmerman, M. I.; Vondrak, R. R.; Delory, G. T.; Pfaff, R. F.

    2014-01-01

    The surface of the Moon is electrically charged by exposure to solar radiation on its dayside, as well as by the continuous flux of charged particles from the various plasma environments that surround it. An electric potential develops between the lunar surface and ambient plasma, which manifests itself in a near-surface plasma sheath with a scale height of order the Debye length. This study investigates surface charging on the lunar dayside and near-terminator regions in the solar wind, for which the dominant current sources are usually from the pohotoemission of electrons, J(sub p), and the collection of plasma electrons J(sub e) and ions J(sub i). These currents are dependent on the following six parameters: plasma concentration n(sub 0), electron temperature T(sub e), ion temperature T(sub i), bulk flow velocity V, photoemission current at normal incidence J(sub P0), and photo electron temperature T(sub p). Using a numerical model, derived from a set of eleven basic assumptions, the influence of these six parameters on surface charging - characterized by the equilibrium surface potential, Debye length, and surface electric field - is investigated as a function of solar zenith angle. Overall, T(sub e) is the most important parameter, especially near the terminator, while J(sub P0) and T(sub p) dominate over most of the dayside.

  10. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

  11. Surface spectra of Weyl semimetals through self-adjoint extensions

    Science.gov (United States)

    Seradjeh, Babak; Vennettilli, Michael

    2018-02-01

    We apply the method of self-adjoint extensions of Hermitian operators to the low-energy, continuum Hamiltonians of Weyl semimetals in bounded geometries and derive the spectrum of the surface states on the boundary. This allows for the full characterization of boundary conditions and the surface spectra on surfaces both normal to the Weyl node separation as well as parallel to it. We show that the boundary conditions for quadratic bulk dispersions are, in general, specified by a U (2 ) matrix relating the wave function and its derivatives normal to the surface. We give a general procedure to obtain the surface spectra from these boundary conditions and derive them in specific cases of bulk dispersion. We consider the role of global symmetries in the boundary conditions and their effect on the surface spectrum. We point out several interesting features of the surface spectra for different choices of boundary conditions, such as a Mexican-hat shaped dispersion on the surface normal to Weyl node separation. We find that the existence of bound states, Fermi arcs, and the shape of their dispersion, depend on the choice of boundary conditions. This illustrates the importance of the physics at and near the boundaries in the general statement of bulk-boundary correspondence.

  12. Testate amoebae communities sensitive to surface moisture conditions in Patagonian peatlands

    Science.gov (United States)

    Loisel, J.; Booth, R.; Charman, D.; van Bellen, S.; Yu, Z.

    2017-12-01

    Here we examine moss surface samples that were collected during three field campaigns (2005, 2010, 2014) across southern Patagonian peatlands to assess the potential use of testate amoebae and 13C isotope data as proxy indicators of soil moisture. These proxies have been widely tested across North America, but their use as paleoecological tools remains sparse in the southern hemisphere. Samples were collected along a hydrological gradient spanning a range of water table depth from 0cm in wet hollows to over 85cm in dry hummocks. Moss moisture content was measured in the field. Over 25 taxa were identified, with many of them not found in North America. Ordinations indicate statistically significant and dominant effects of soil moisture and water table depth on testate assemblages, though interestingly 13C is even more strongly correlated with testates amoebae than direct soil conditions. It is possible that moss 13C signature constitutes a compound indicator that represents seasonal soil moisture better than opportunistic sampling during field campaigns. There is no significant effect of year or site across the dataset. In addition to providing a training set that translates testate amoebae moisture tolerance range into water tabel depth for Patagonian peatlands, we also compare our results with those from the North American training set to show that, despite 'novel' Patagonian taxa, the robustness of international training sets is probably sufficient to quantify most changes in soil moisture from any site around the world. We also identify key indicator species that are shown to be of universal value in peat-based hydrological reconstructions.

  13. Chemical stabilization of graphite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bistrika, Alexander A.; Lerner, Michael M.

    2018-04-03

    Embodiments of a device, or a component of a device, including a stabilized graphite surface, methods of stabilizing graphite surfaces, and uses for the devices or components are disclosed. The device or component includes a surface comprising graphite, and a plurality of haloaryl ions and/or haloalkyl ions bound to at least a portion of the graphite. The ions may be perhaloaryl ions and/or perhaloalkyl ions. In certain embodiments, the ions are perfluorobenzenesulfonate anions. Embodiments of the device or component including stabilized graphite surfaces may maintain a steady-state oxidation or reduction surface current density after being exposed to continuous oxidation conditions for a period of at least 1-100 hours. The device or component is prepared by exposing a graphite-containing surface to an acidic aqueous solution of the ions under oxidizing conditions. The device or component can be exposed in situ to the solution.

  14. Technology transfer: Half-way houses. No. 17

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, R.W.

    1995-05-01

    In the fall of 1993, 1 was asked by the Center for National Security Studies (CNSS) of the Los Alamos National Laboratory (LANL) to study the ways in which technology transfer and defense conversion had been accomplished at General Atomics (GA) and Science Applications International Corporation (SAIC) by interviewing Harold Agnew, who had served as director of Los Alamos before becoming president of General Atomics in 1979, and J. Robert Beyster, who had been a staff member at Los Alamos and at General Atomics before founding SAIC in 1969. Harold Agnew readily complied with my request for an interview and also suggested that I talk to Douglas Fouquet, who is in charge of public relations at General Atomics and is their unofficial historian. Robert Beyster was not available for an interview, but, through the courtesy of John C. Hopkins, a former director of CNSS, I was able to interview SAIC`s executive vice president, Donald M. Kerr, who is also a former director at Los Alamos, and Steven Rockwood, a sector vice president at SAIC who was formerly a staff member at the Laboratory Because Agnew, Kerr, and Rockwood are all familiar with LANL, as well as with their respective companies, the interviews becam exercises In comparative analyses of technology transfer. In what follows, I have tried to summarize both the interviews and some of the research which attended them. It is the historian`s hope that by use of comparative institutional analyses, Laboratory administrators may learn something of value in directing their efforts toward the transfer of technology to private industry and other government agencies.

  15. Injury and illness sustained by human competitors in the 2010 iditarod sled dog race.

    Science.gov (United States)

    Gallea, James W; Higgins, George L; Germann, Carl A; Strout, Tania D

    2014-07-01

    Alaska's 1049-mile Iditarod Trail Sled Dog Race is the world's longest sled dog race and the flagship event in the sport of sled dog racing. Race conditions are typically harsh. Physicians are not officially enlisted to care for human competitors. Instead, medical needs are met through an informal system of volunteers, local health care providers, and a fleet of bush planes. The goals of this study were to identify the types of human injury and illness experienced and the methods by which these conditions are treated. Competitors in the 2010 Iditarod were surveyed at the halfway point and at the finish of the race. Survey elements included specific types and frequencies of injuries and illnesses, and the sources and types of treatments. Seventy-one teams entered the race, 62 participated in the halfway point survey, and 55 completed the finish line survey. Ninety-nine injuries were reported by 42 (68%) of the survey respondents. Frostbite was the most common injury, occurring in 20 (31%) of the respondents. Musculoskeletal pain was also commonly reported. Two mushers sustained closed head injuries, with 1 requiring evacuation. Twenty-three mushers (37%) reported an acute nontraumatic condition, most frequently an upper respiratory infection (9 respondents). In most instances, medical conditions were self-managed. Race veterinarians and support staff, as well as local village clinicians, administered the majority of care, typically wound care or oral antibiotic administration. Most injuries and illnesses sustained by mushers in the Iditarod are minor and self-treatable. Life-threatening conditions are rare, and the need for an organized medical care system seems low. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. Neptunium (V) Adsorption to a Halophilic Bacterium Under High Ionic Strength Conditions: A Surface Complexation Modeling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Ams, David A [Los Alamos National Laboratory

    2012-06-11

    Rationale for experimental design: Np(V) -- important as analog for Pu(V) and for HLW scenarios; High ionic strength -- relevant to salt-based repositories such as the WIPP; Halophilic microorganisms -- representative of high ionic strength environments. For the first time showed: Significant adsorbant to halophilic microorganisms over entire pH range under high ionic strength conditions; Strong influence of ionic strength with increasing adsorption with increasing ionic strength (in contrast to trends of previous low ionic strength studies); Effect of aqueous Np(V) and bacterial surface site speciation on adsorption; and Developed thermodynamic models that can be incorporated into geochemical speciation models to aid in the prediction of the fate and transport of Np(V) in more complex systems.

  17. West-WRF Sensitivity to Sea Surface Temperature Boundary Condition in California Precipitation Forecasts of AR Related Events

    Science.gov (United States)

    Zhang, X.; Cornuelle, B. D.; Martin, A.; Weihs, R. R.; Ralph, M.

    2017-12-01

    We evaluated the merit in coastal precipitation forecasts by inclusion of high resolution sea surface temperature (SST) from blended satellite and in situ observations as a boundary condition (BC) to the Weather Research and Forecast (WRF) mesoscale model through simple perturbation tests. Our sensitivity analyses shows that the limited improvement of watershed scale precipitation forecast is credible. When only SST BC is changed, there is an uncertainty introduced because of artificial model state equilibrium and the nonlinear nature of the WRF model system. With the change of SST on the order of a fraction of a degree centigrade, we found that the part of random perturbation forecast response is saturated after 48 hours when it reaches to the order magnitude of the linear response. It is important to update the SST at a shorter time period, so that the independent excited nonlinear modes can cancel each other. The uncertainty in our SST configuration is quantitatively equivalent to adding to a spatially uncorrelated Guasian noise of zero mean and 0.05 degree of standard deviation to the SST. At this random noise perturbation magnitude, the ensemble average behaves well within a convergent range. It is also found that the sensitivity of forecast changes in response to SST changes. This is measured by the ratio of the spatial variability of mean of the ensemble perturbations over the spatial variability of the corresponding forecast. The ratio is about 10% for surface latent heat flux, 5 % for IWV, and less than 1% for surface pressure.

  18. Mixed and mixing layer depths in the ocean surface boundary layer under conditions of diurnal stratification

    Science.gov (United States)

    Sutherland, G.; Reverdin, G.; Marié, L.; Ward, B.

    2014-12-01

    A comparison between mixed (MLD) and mixing (XLD) layer depths is presented from the SubTRopical Atlantic Surface Salinity Experiment (STRASSE) cruise in the subtropical Atlantic. This study consists of 400 microstructure profiles during fairly calm and moderate conditions (2 background level. Two different thresholds for the background dissipation level are tested, 10-8 and 10-9 m2 s-3, and these are compared with the MLD as calculated using a density threshold. The larger background threshold agrees with the MLD during restratification but only extends to half the MLD during nighttime convection, while the lesser threshold agrees well during convection but is deeper by a factor of 2 during restratification. Observations suggest the use of a larger density threshold to determine the MLD in a buoyancy driven regime.

  19. Influence of surface conditions on fatigue strength through the numerical simulation of microstructure; Etude par simulation numerique de la microstructure de l'influence de l'etat de surface sur la resistance a la fatigue d'un acier 304L

    Energy Technology Data Exchange (ETDEWEB)

    Le Pecheur, A.; Clavel, M.; Rey, C.; Bompard, P. [Laboratoire MSSMat, UMR 8579 CNRS, Ecole Centrale Paris (France); Le Pecheur, A.; Curtit, F.; Stephan, J.M. [Departement MMC, EDF RD, Site des Renardieres (France)

    2010-11-15

    A thermal fatigue test (INTHERPOL) was developed by EDF in order to study the initiation of cracks. These tests are carried out on tubular specimens under various thermal loadings and surface finish qualities in order to give an account of these parameters on crack initiation. The main topic of this study is to test the sensitivity of different fatigue criteria to surface conditions using a micro/macro modelling approach. Therefore a 304L polycrystalline aggregate, used for cyclic plasticity based FE modelling, have been considered as a Representative Volume Element located at the surface and subsurface of the test tube. This aggregate has been cyclically strained according to the results issued from FE simulation of INTHERPOL thermal fatigue experiment. Different surface parameters have been numerically simulated: effects of local microstructure and of grains orientation, effects of machining: metallurgical prehardening, residual stress gradient, and surface roughness. Three different fatigue criteria (Manson Coffin, Fatemi Socie and dissipated energy types), previously fitted at a macro-scale for thermal fatigue of 304L, have been computed at a meso scale, in order to show the surface 'hot spots' features and test the sensitivity of these three criteria to different surface conditions. Results show that grain orientation and neighbouring play an important role on the location of hot spots, and also that the positive effect of pre-straining and the negative effect of roughness on fatigue life are not all similarly predicted by these different fatigue criteria. (authors)

  20. Quantifying the changes of soil surface microroughness due to rainfall impact on a smooth surface

    Directory of Open Access Journals (Sweden)

    B. K. B. Abban

    2017-09-01

    Full Text Available This study examines the rainfall-induced change in soil microroughness of a bare smooth soil surface in an agricultural field. The majority of soil microroughness studies have focused on surface roughness on the order of ∼ 5–50 mm and have reported a decay of soil surface roughness with rainfall. However, there is quantitative evidence from a few studies suggesting that surfaces with microroughness less than 5 mm may undergo an increase in roughness when subject to rainfall action. The focus herein is on initial microroughness length scales on the order of 2 mm, a low roughness condition observed seasonally in some landscapes under bare conditions and chosen to systematically examine the increasing roughness phenomenon. Three rainfall intensities of 30, 60, and 75 mm h−1 are applied to a smoothened bed surface in a field plot via a rainfall simulator. Soil surface microroughness is recorded via a surface-profile laser scanner. Several indices are utilized to quantify the soil surface microroughness, namely the random roughness (RR index, the crossover length, the variance scale from the Markov–Gaussian model, and the limiting difference. Findings show a consistent increase in roughness under the action of rainfall, with an overall agreement between all indices in terms of trend and magnitude. Although this study is limited to a narrow range of rainfall and soil conditions, the results suggest that the outcome of the interaction between rainfall and a soil surface can be different for smooth and rough surfaces and thus warrant the need for a better understanding of this interaction.

  1. City ventilation of Hong Kong at no-wind conditions

    Science.gov (United States)

    Yang, Lina; Li, Yuguo

    We hypothesize that city ventilation due to both thermally-driven mountain slope flows and building surface flows is important in removing ambient airborne pollutants in the high-rise dense city Hong Kong at no-wind conditions. Both spatial and temporal urban surface temperature profiles are an important boundary condition for studying city ventilation by thermal buoyancy. Field measurements were carried out to investigate the diurnal thermal behavior of urban surfaces (mountain slopes, and building exterior walls and roofs) in Hong Kong by using the infrared thermography. The maximum urban surface temperature was measured in the early noon hours (14:00-15:00 h) and the minimum temperature was observed just before sunrise (5:00 h). The vertical surface temperature of the building exterior wall was found to increase with height at daytime and the opposite occurred at nighttime. The solar radiation and the physical properties of the various urban surfaces were found to be important factors affecting the surface thermal behaviors. The temperature difference between the measured maximum and minimum surface temperatures of the four selected exterior walls can be at the highest of 16.7 °C in the early afternoon hours (15:00 h). Based on the measured surface temperatures, the ventilation rate due to thermal buoyancy-induced wall surface flows of buildings and mountain slope winds were estimated through an integral analysis of the natural convection flow over a flat surface. At no-wind conditions, the total air change rate by the building wall flows (2-4 ACH) was found to be 2-4 times greater than that by the slope flows due to mountain surface (1 ACH) due to larger building exterior surface areas and temperature differences with surrounding air. The results provide useful insights into the ventilation of a high-rise dense city at no-wind conditions.

  2. Synchrotron radiation induced TXRF of low Z elements on Si wafer surfaces at SSRL-comparison of excitation geometries and condition

    International Nuclear Information System (INIS)

    Streli, C.; Wobrauschek, P.; Kregsamer, P.; Pepponi, G.; Pianetta, P.; Pahlke, S.; Fabry, L.

    2000-01-01

    The determination of low Z elements, like Na and Al at ultra trace levels on Si wafer surfaces is demanded by semiconductor industry. SR-TXRF is a promising method to fulfill the task, if a special energy dispersive detector with an ultra thin window is used. Synchrotron radiation is the ideal suited excitation source for TXRF of low Z elements due to its intensive, natural collimated and linear polarized radiation with wide spectral range down to low energies even below 1 keV. TXRF offers some advantages for wafer surface analysis like nondestructive investigation and mapping capability. Experiments have been performed at SSRL beamline 3-4, a bending magnet beamline using white (<3 keV) and monochromatic radiation, as well as on beamline 3-3, using a crystal monochromator as well as a multilayer monochromator. A comparison of excitation detection geometries was performed, using a sidelooking detector with vertical positioned wafer as well as a downlooking detector with a horizontally arranged wafer. The advantages and disadvantages of the various geometries and excitation conditions are presented and the results compared. Detection limits are in the 100 fg range for Na, determined with droplet samples on Si wafer surfaces. (author)

  3. Decontamination of radioactively contaminated surfaces

    International Nuclear Information System (INIS)

    1986-10-01

    By this standard objective conditions to evaluate and test the ease of decontamination of surfaces under laboratory conditions are to be laid down. Ease of decontamination in this context denotes the summed-up effect of two material properties: a) the capacity of the material for retaining radioactive substances at its surface; b) the ease with which these substances are given off again in the course of cleaning processes. (orig./HP) [de

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

    International Nuclear Information System (INIS)

    McCrea, Keith R.

    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-(sigma) 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(pi)-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

  5. Optimization of the Conditions for Extraction of Serine Protease from Kesinai Plant (Streblus asper Leaves Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Md. Zaidul Islam Sarker

    2011-11-01

    Full Text Available Response surface methodology (RSM using a central composite design (CCD was employed to optimize the conditions for extraction of serine protease from kesinai (Streblus asper leaves. The effect of independent variables, namely temperature (42.5,47.5, X1, mixing time (2–6 min, X2, buffer content (0–80 mL, X3 and buffer pH (4.5–10.5, X4 on specific activity, storage stability, temperature and oxidizing agent stability of serine protease from kesinai leaves was investigated. The study demonstrated that use of the optimum temperature, mixing time, buffer content and buffer pH conditions protected serine protease during extraction, as demonstrated by low activity loss. It was found that the interaction effect of mixing time and buffer content improved the serine protease stability, and the buffer pH had the most significant effect on the specific activity of the enzyme. The most desirable conditions of 2.5 °C temperature, 4 min mixing time, 40 mL buffer at pH 7.5 was established for serine protease extraction from kesinai leaves.

  6. Surface freezing of water

    OpenAIRE

    P?rez-D?az, J. L.; ?lvarez-Valenzuela, M. A.; Rodr?guez-Celis, F.

    2016-01-01

    Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered?exclusively?by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on ...

  7. Black holes as mirrors: quantum information in random subsystems

    International Nuclear Information System (INIS)

    Hayden, Patrick; Preskill, John

    2007-01-01

    We study information retrieval from evaporating black holes, assuming that the internal dynamics of a black hole is unitary and rapidly mixing, and assuming that the retriever has unlimited control over the emitted Hawking radiation. If the evaporation of the black hole has already proceeded past the ''half-way'' point, where half of the initial entropy has been radiated away, then additional quantum information deposited in the black hole is revealed in the Hawking radiation very rapidly. Information deposited prior to the half-way point remains concealed until the half-way point, and then emerges quickly. These conclusions hold because typical local quantum circuits are efficient encoders for quantum error-correcting codes that nearly achieve the capacity of the quantum erasure channel. Our estimate of a black hole's information retention time, based on speculative dynamical assumptions, is just barely compatible with the black hole complementarity hypothesis

  8. PC-version of RAM6-code for calculation of parameters of the effective logarithmic boundary condition at the absorbent rod surface in reactor

    International Nuclear Information System (INIS)

    Le Van Ngoc; Ngo Dang Nhan

    1990-01-01

    The RAM-6 code for calculation of parameters of the effective logarithmic boundary condition at the absorbent rod surface in reactor is suitably modofied to work on IBM PC, the instructions for its usage are presented and capabilities of the personal cpmputer oriented RAM-6 code are demonstrated. (author). 4 refs, 5 tabs, 2 figs

  9. The conditions for electrodeposition of insoluble hydroxides at a cathode surface

    DEFF Research Database (Denmark)

    Hansen, P.Gregers

    1959-01-01

    The pH values obtained in the vicinity of a cathode surface where hydrogen evolution takes place are discussed using the concept of a diffusion layer. It is shown that a given current density I determines a hydrogen ion concentration Cmax in the solution, above which no hydroxide deposition...... at the cathode can be expected to take place. The shape of the pH distribution makes it possible to define a hydroxyl ion layer, the thickness of which approaches zero as the hydrogen ion concentration approaches Cmax. It is found that relatively high pH values (11–13) are easily obtained at a cathode surface...

  10. CONDITIONING OF INTERMEDIATE-LEVEL WASTE AT FORSCHUNGSZENTRUM JUELICH GMBH

    International Nuclear Information System (INIS)

    Krumbach, H.

    2003-01-01

    This contribution to the group of low-level, intermediate, mixed and hazardous waste describes the conditioning of intermediate-level mixed waste (dose rate above 10 mSv/h at the surface) from Research Centre Juelich (FZJ). Conditioning of the waste by supercompaction is performed at Research Centre Karlsruhe (FZK). The waste described is radioactive waste arising from research at Juelich. This waste includes specimens and objects from irradiation experiments in the research reactors Merlin (FRJ-1) and Dido (FRJ-2) at FZJ. In principle, radioactive waste at Forschungszentrum Juelich GmbH is differentiated by the surface dose rate at the waste package. Up to a surface dose rate of 10 mSv/h, the waste is regarded as low-level. The radioactive waste described here has a surface dose rate above 10 mSv/h. Waste up to 10 mSv/h is conditioned at the Juelich site according to different conditioning methods. The intermediate-level waste can only be conditioned by supercompaction in the processing facility for intermediate-level waste from plant operation at Research Centre Karlsruhe. Research Centre Juelich also uses this waste cell to condition its intermediate-level waste from plant operation

  11. Probing surface magnetism with ion beams

    International Nuclear Information System (INIS)

    Winter, H.

    2007-01-01

    Ion beams can be used to probe magnetic properties of surfaces by a variety of different methods. Important features of these methods are related to trajectories of atomic projectiles scattered from the surface of a solid target and to the electronic interaction mechanisms in the surface region. Both items provide under specific conditions a high sensitivity for the detection of magnetic properties in the region at the topmost layer of surface atoms. This holds in particular for scattering under planar surface channeling conditions, where under grazing impact atoms or ions are reflected specularly from the surface without penetration into the subsurface region. Two different types of methods are employed based on the detection of the spin polarization of emitted or captured electrons and on spin blocking effects for capture into atomic terms. These techniques allow one to probe the long range and short range magnetic order in the surface region

  12. Influence of intermediate layers on the surface condition of laser crystallized silicon thin films and solar cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Höger, Ingmar, E-mail: ingmar.hoeger@ipht-jena.de; Gawlik, Annett; Brückner, Uwe; Andrä, Gudrun [Leibniz-Institut für Photonische Technologien, PF 100239, 07702 Jena (Germany); Himmerlich, Marcel; Krischok, Stefan [Institut für Mikro-und Nanotechnologien, Technische Universität Ilmenau, PF 100565, 98684 Ilmenau (Germany)

    2016-01-28

    The intermediate layer (IL) between glass substrate and silicon plays a significant role in the optimization of multicrystalline liquid phase crystallized silicon thin film solar cells on glass. This study deals with the influence of the IL on the surface condition and the required chemical surface treatment of the crystallized silicon (mc-Si), which is of particular interest for a-Si:H heterojunction thin film solar cells. Two types of IL were investigated: sputtered silicon nitride (SiN) and a layer stack consisting of silicon nitride and silicon oxide (SiN/SiO). X-ray photoelectron spectroscopy measurements revealed the formation of silicon oxynitride (SiO{sub x}N{sub y}) or silicon oxide (SiO{sub 2}) layers at the surface of the mc-Si after liquid phase crystallization on SiN or SiN/SiO, respectively. We propose that SiO{sub x}N{sub y} formation is governed by dissolving nitrogen from the SiN layer in the silicon melt, which segregates at the crystallization front during crystallization. This process is successfully hindered, when additional SiO layers are introduced into the IL. In order to achieve solar cell open circuit voltages above 500 mV, a removal of the formed SiO{sub x}N{sub y} top layer is required using sophisticated cleaning of the crystallized silicon prior to a-Si:H deposition. However, solar cells crystallized on SiN/SiO yield high open circuit voltage even when a simple wet chemical surface treatment is applied. The implementation of SiN/SiO intermediate layers facilitates the production of mesa type solar cells with open circuit voltages above 600 mV and a power conversion efficiency of 10%.

  13. Enzymatic Phorbol Esters Degradation using the Germinated Jatropha Curcas Seed Lipase as Biocatalyst: Optimization Process Conditions by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Avita Kusuma Wardhani

    2016-10-01

    Full Text Available Utilization of Jatropha curcas seed cake is limited by the presence of phorbol esters (PE, which are the main toxic compound and heat stable. The objective of this research was to optimize the reaction conditions of the enzymatic PE degradation of the defatted Jatropha curcas seed cake (DJSC using the acetone-dried lipase from the germinated Jatropha curcas seeds as a biocatalyst. Response Surface Methodology (RSM using three-factors-three-levels Box-Behnken design was used to evaluate the effects of the reaction time, the ratio of buffer volume to DJSC, and the ratio of enzyme to DJSC on PE degradation. The results showed that the optimum conditions of PE degradation were 29.33 h, 51.11 : 6 (mL/g, and 30.10 : 5 (U/g cake for the reaction time, the ratio of buffer volume to DJSC, and the ratio of enzyme to DJSC, respectively. The predicted degradation of PE was 98.96% and not significantly different with the validated data of PE degradation. PE content was 0.035 mg/g, in which it was lower than PE in non-toxic Jatropha seeds. The results indicated that enzymatic degradation of PE might be a promising method for degradation of PE.  Copyright © 2016 BCREC GROUP. All rights reserved Received: 22nd December 2015; Revised: 1st April 2016; Accepted: 14th April 2016 How to Cite: Wardhani, A.K., Hidayat, C., Hastuti, P. (2016. Enzymatic Phorbol Esters Degradation using the Germinated Jatropha Curcas Seed Lipase as Biocatalyst: Optimization Process Conditions by Response Surface Methodology. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3: 346-353 (doi:10.9767/bcrec.11.3.574.346-353 Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.574.346-353

  14. Influencing factors on the visibility of surface distresses

    Science.gov (United States)

    Smęt, Wojciech; Skakuj, Marek

    2018-05-01

    A systematic and future-oriented maintenance management requires quality-assured data regarding the condition of the roadway. An important characteristic for assessing the condition of the road surface are cracks [1]. Experience has proven that the road surface temperature and residual humidity can influence the visibility of cracks. To investigate and quantify these influencing factors in more detail, the Federal Ministry of Transport and Digital Infrastructure has implemented a comprehensive research project [2], during which several measurement campaigns were carried out at different seasons and at different temperatures and humidity degrees of the road surface. The visibility of the cracks was assessed using the German approach ZTV ZEB-StB [3]. After evaluating the cracks, the data was synchronized and the network allocation of the geo-referenced raw data was realized. The relevant condition performance indicators were calculated subsequently. For each evaluation section of 100 meters length, the mean road surface temperature was calculated and, if available, the type and year of construction of the surface course was determined. The evaluated data was visualized to establish correlations between the data and the influencing factors. For the statistical analysis of the results, a total of six comparative scenarios were defined in which the influencing factors of road surface temperature and residual humidity were assessed. This paper documents the results of the research project. In order to obtain a uniform and comparable picture of the condition of the road surface over the years and thus to be able to observe the aging process of the road surface, the measurement campaigns are to be carried out under defined conditions. The research project included proposals for defining and further specifying the measurement conditions.

  15. Plasma facing surface composition during NSTX Li experiments

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, C.H., E-mail: cskinner@pppl.gov [Princeton Plasma Physics Laboratory, POB 451, Princeton, NJ 08543 (United States); Sullenberger, R. [Department of Mechanical and Aerospace Engineering, Princeton University, NJ 08540 (United States); Koel, B.E. [Department of Chemical and Biological Engineering, Princeton University, NJ 08540 (United States); Jaworski, M.A.; Kugel, H.W. [Princeton Plasma Physics Laboratory, POB 451, Princeton, NJ 08543 (United States)

    2013-07-15

    Lithium conditioned plasma facing surfaces have lowered recycling and enhanced plasma performance on many fusion devices. However, the nature of the plasma–lithium surface interaction has been obscured by the difficulty of in-tokamak surface analysis. We report laboratory studies of the chemical composition of lithium surfaces exposed to typical residual gases found in tokamaks. Solid lithium and a molybdenum alloy (TZM) coated with lithium have been examined using X-ray photoelectron spectroscopy, temperature programmed desorption, and Auger electron spectroscopy both in ultrahigh vacuum conditions and after exposure to trace gases. Lithium surfaces near room temperature were oxidized after exposure to 1–2 Langmuirs of oxygen or water vapor. The oxidation rate by carbon monoxide was four times less. Lithiated PFC surfaces in tokamaks will be oxidized in about 100 s depending on the tokamak vacuum conditions.

  16. Field-emitting Townsend regime of surface dielectric barrier discharges emerging at high pressure up to supercritical conditions

    International Nuclear Information System (INIS)

    Pai, David Z; Stauss, Sven; Terashima, Kazuo

    2015-01-01

    Surface dielectric barrier discharges (DBDs) in CO 2 from atmospheric pressure up to supercritical conditions generated using 10 kHz ac excitation are investigated experimentally. Using current–voltage and charge–voltage measurements, imaging, optical emission spectroscopy, and spontaneous Raman spectroscopy, we identify and characterize a field-emitting Townsend discharge regime that emerges above 0.7 MPa. An electrical model enables the calculation of the discharge-induced capacitances of the plasma and the dielectric, as well as the space-averaged values of the surface potential and the potential drop across the discharge. The space-averaged Laplacian field is accounted for in the circuit model by including the capacitance due to the fringe electric field from the electrode edge. The electrical characteristics are demonstrated to fit the description of atmospheric-pressure Townsend DBDs (Naudé et al 2005 J. Phys. D: Appl. Phys. 38 530–8), i.e. self-sustained DBDs with minimal space-charge effects. The purely continuum emission spectrum is due to electron–neutral bremsstrahlung corresponding to an average electron temperature of 2600 K. Raman spectra of CO 2 near the critical point demonstrate that the average gas temperature increases by less than 1 K. (paper)

  17. Smooth polyhedral surfaces

    KAUST Repository

    Gü nther, Felix; Jiang, Caigui; Pottmann, Helmut

    2017-01-01

    Polyhedral surfaces are fundamental objects in architectural geometry and industrial design. Whereas closeness of a given mesh to a smooth reference surface and its suitability for numerical simulations were already studied extensively, the aim of our work is to find and to discuss suitable assessments of smoothness of polyhedral surfaces that only take the geometry of the polyhedral surface itself into account. Motivated by analogies to classical differential geometry, we propose a theory of smoothness of polyhedral surfaces including suitable notions of normal vectors, tangent planes, asymptotic directions, and parabolic curves that are invariant under projective transformations. It is remarkable that seemingly mild conditions significantly limit the shapes of faces of a smooth polyhedral surface. Besides being of theoretical interest, we believe that smoothness of polyhedral surfaces is of interest in the architectural context, where vertices and edges of polyhedral surfaces are highly visible.

  18. Smooth polyhedral surfaces

    KAUST Repository

    Günther, Felix

    2017-03-15

    Polyhedral surfaces are fundamental objects in architectural geometry and industrial design. Whereas closeness of a given mesh to a smooth reference surface and its suitability for numerical simulations were already studied extensively, the aim of our work is to find and to discuss suitable assessments of smoothness of polyhedral surfaces that only take the geometry of the polyhedral surface itself into account. Motivated by analogies to classical differential geometry, we propose a theory of smoothness of polyhedral surfaces including suitable notions of normal vectors, tangent planes, asymptotic directions, and parabolic curves that are invariant under projective transformations. It is remarkable that seemingly mild conditions significantly limit the shapes of faces of a smooth polyhedral surface. Besides being of theoretical interest, we believe that smoothness of polyhedral surfaces is of interest in the architectural context, where vertices and edges of polyhedral surfaces are highly visible.

  19. Mechanism of supercooled droplet freezing on surfaces.

    Science.gov (United States)

    Jung, Stefan; Tiwari, Manish K; Doan, N Vuong; Poulikakos, Dimos

    2012-01-10

    Understanding ice formation from supercooled water on surfaces is a problem of fundamental importance and general utility. Superhydrophobic surfaces promise to have remarkable 'icephobicity' and low ice adhesion. Here we show that their icephobicity can be rendered ineffective by simple changes in environmental conditions. Through experiments, nucleation theory and heat transfer physics, we establish that humidity and/or the flow of a surrounding gas can fundamentally switch the ice crystallization mechanism, drastically affecting surface icephobicity. Evaporative cooling of the supercooled liquid can engender ice crystallization by homogeneous nucleation at the droplet-free surface as opposed to the expected heterogeneous nucleation at the substrate. The related interplay between droplet roll-off and rapid crystallization is also studied. Overall, we bring a novel perspective to icing and icephobicity, unveiling the strong influence of environmental conditions in addition to the accepted effects of the surface conditions and hydrophobicity.

  20. Influence of soil on St3 surface spectroscopic characteristics under cathode protection conditions

    International Nuclear Information System (INIS)

    Kuznetsova, E.G.; Lazorenko-Manevich, R.M.; Sokolova, L.A.; Remezkova, L.V.

    1992-01-01

    Using electroreflection spectra it is shown, that St3 surface following long holding in cold clay without cathode protection is less heterogeneous relative to water absorption, than surface of initial specimens, as well as, of specimens holded in wet clay. This variation of distribution of adsorption centres by heats of water absorption results from stable absorption of surface-and-active components of clayed soil and is accompanied by increase of St3 corrosion stability. Long-term cathode polarization reduces initial distribution and decreases corrosion stability of St3

  1. Improving Weather Research and Forecasting Model Initial Conditions via Surface Pressure Analysis

    Science.gov (United States)

    2015-09-01

    ADDRESS(ES) US Army Research Laboratory ATTN: RDRL- CIE -M 2800 Powder Mill Road Adelphi, MD 20783-1138 8. PERFORMING ORGANIZATION REPORT NUMBER...air radii of influence to account for the smaller error correlation length scales at the surface. However, the surface observations are limited to a...analysis will only account for errors in the first guess due to errors in the meteorological features (e.g., the strength of an area of high pressure

  2. Optimization of conditions for probiotic curd formulation by Enterococcus faecium MTCC 5695 with probiotic properties using response surface methodology.

    Science.gov (United States)

    Ramakrishnan, Vrinda; Goveas, Louella Concepta; Prakash, Maya; Halami, Prakash M; Narayan, Bhaskar

    2014-11-01

    Enterococcus faecium MTCC 5695 possessing potential probiotic properties as well as enterocin producing ability was used as starter culture. Effect of time (12-24 h) and inoculum level (3-7 % v/v) on cell growth, bacteriocin production, antioxidant property, titrable acidity and pH of curd was studied by response surface methodology (RSM). The optimized conditions were 26.48 h and 2.17%v/v inoculum and the second order model validated. Co cultivation studies revealed that the formulated product had the ability to prevent growth of foodborne pathogens that affect keeping quality of the product during storage. The results indicated that application of E. faecium MTCC 5695 along with usage of optimized conditions attributed to the formation of highly consistent well set curd with bioactive and bioprotective properties. Formulated curd with potential probiotic attributes can be used as therapeutic agent for the treatment of foodborne diseases like Traveler's diarrhea and gastroenteritis which thereby help in improvement of bowel health.

  3. Influence of irradiation conditions on plasma evolution in laser-surface interaction

    Science.gov (United States)

    Hermann, J.; Boulmer-Leborgne, C.; Dubreuil, B.; Mihailescu, I. N.

    1993-09-01

    The plasma plume induced by pulsed CO2 laser irradiation of a Ti target at power densities up to 4×108 W cm-2 was studied by emission spectroscopy. Time- and space-resolved measurements were performed by varying laser intensity, laser temporal pulse shape, ambient gas pressure, and the nature of the ambient gas. Experimental results are discussed by comparison with usual models. We show that shock wave and plasma propagation depend critically on the ratio Ivap/Ii, Ivap being the intensity threshold for surface vaporization and Ii the plasma ignition threshold of the ambient gas. Spectroscopic diagnostics of the helium breakdown plasma show maximum values of electron temperature and electron density in the order of kTe˜10 eV and ne=1018 cm-3, respectively. The plasma cannot be described by local thermodynamic equilibrium modeling. Nevertheless, excited metal atoms appear to be in equilibrium with electrons, hence, they can be used like a probe to measure the electron temperature. In order to get information on the role of the plasma in the laser-surface interaction, Ti surfaces were investigated by microscopy after irradiation. Thus an enhanced momentum transfer from the plasma to the target due to the recoil pressure of the breakdown plasma could be evidenced.

  4. Evaporation under vacuum condition

    International Nuclear Information System (INIS)

    Mizuta, Satoshi; Shibata, Yuki; Yuki, Kazuhisa; Hashizume, Hidetoshi; Toda, Saburo; Takase, Kazuyuki; Akimoto, Hajime

    2000-01-01

    In nuclear fusion reactor design, an event of water coolant ingress into its vacuum vessel is now being considered as one of the most probable accidents. In this report, the evaporation under vacuum condition is evaluated by using the evaporation model we have developed. The results show that shock-wave by the evaporation occurs whose behavior strongly depends on the initial conditions of vacuum. And in the case of lower initial pressure and temperature, the surface temp finally becomes higher than other conditions. (author)

  5. Tensile bond strength of metal bracket bonding to glazed ceramic surfaces with different surface conditionings.

    Science.gov (United States)

    Akhoundi, Ms Ahmad; Kamel, M Rahmati; Hashemi, Sh Mahmood; Imani, M

    2011-01-01

    The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments. Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA). Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primer and adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively. The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (Ptensile bond strength.

  6. Surface flow in severe plastic deformation of metals by sliding

    International Nuclear Information System (INIS)

    Mahato, A; Yeung, H; Chandrasekar, S; Guo, Y

    2014-01-01

    An in situ study of flow in severe plastic deformation (SPD) of surfaces by sliding is described. The model system – a hard wedge sliding against a metal surface – is representative of surface conditioning processes typical of manufacturing, and sliding wear. By combining high speed imaging and image analysis, important characteristics of unconstrained plastic flow inherent to this system are highlighted. These characteristics include development of large plastic strains on the surface and in the subsurface by laminar type flow, unusual fluid-like flow with vortex formation and surface folding, and defect and particle generation. Preferred conditions, as well as undesirable regimes, for surface SPD are demarcated. Implications for surface conditioning in manufacturing, modeling of surface deformation and wear are discussed

  7. Radiative heat exchange between surfaces

    International Nuclear Information System (INIS)

    Yener, Y.; Yuncu, H.

    1987-01-01

    The geometrical features of radiative heat exchange between surfaces are discussed first by developing various radiation shape factor relations. The governing equations for enclosures with diffusely emitting and diffusely reflecting surfaces, as well as the equations for enclosures with gray surfaces having specular component of reflectivity are introduced next. Finally, a simplified model for enclosures with isothermal surfaces under the assumption of uniform radiosity over the surfaces is discussed, and various working relations for different conditions are presented

  8. Study on fermentation conditions of palm juice vinegar by response surface methodology and development of a kinetic model

    Directory of Open Access Journals (Sweden)

    S. Ghosh

    2012-09-01

    Full Text Available Natural vinegar is one of the fermented products which has some potentiality with respect to a nutraceutical standpoint. The present study is an optimization of the fermentation conditions for palm juice vinegar production from palm juice (Borassus flabellifer wine, this biochemical process being aided by Acetobacter aceti (NCIM 2251. The physical parameters of the fermentation conditions such as temperature, pH, and time were investigated by Response Surface Methodology (RSM with 2³ factorial central composite designs (CCD. The optimum pH, temperature and time were 5.5, 30 °C and 72 hrs for the highest yield of acetic acid (68.12 g / L. The quadratic model equation had a R² value of 0.992. RSM played an important role in elucidating the basic mechanisms in a complex situation, thus providing better process control by maximizing acetic acid production with the respective physical parameters. At the optimized conditions of temperature, pH and time and with the help of mathematical kinetic equations, the Monod specific growth rate ( µ max= 0.021 h-1, maximum Logistic specific growth rate ( µ 'max = 0.027 h-1 and various other kinetic parameters were calculated, which helped in validation of the experimental data. Therefore, the established kinetic models may be applied for the production of natural vinegar by fermentation of low cost palm juice.

  9. Surface Microstructure Replication in Injection Moulding

    DEFF Research Database (Denmark)

    Hansen, Hans Nørgaard; Arlø, Uffe Rolf

    2005-01-01

    topography is transcribed onto the plastic part through complex mechanisms. This replication however, is not perfect, and the replication quality depends on the plastic material properties, the topography itself, and the process conditions. This paper describes and discusses an investigation of injection...... moulding of surface microstructures. Emphasis is put on the ability to replicate surface microstructures under normal injection moulding conditions, notably with low cost materials at low mould temperatures. The replication of surface microstructures in injection moulding has been explored...... for Polypropylene at low mould temperatures. The process conditions were varied over the recommended process window for the material. The geometry of the obtained structures was analyzed. Evidence suggests that step height replication quality depends linearly on structure width in a certain range. Further...

  10. The machined surface of magnesium AZ31 after rotary turning at air cooling condition

    Science.gov (United States)

    Akhyar, G.; Purnomo, B.; Hamni, A.; Harun, S.; Burhanuddin, Y.

    2018-04-01

    Magnesium is a lightweight metal that is widely used as an alternative to iron and steel. Magnesium has been applied in the automotive industry to reduce the weight of a component, but the machining process has the disadvantage that magnesium is highly flammable because it has a low flash point. High temperature can cause the cutting tool wear and contributes to the quality of the surface roughness. The purpose of this study is to obtain the value of surface roughness and implement methods of rotary cutting tool and air cooling output vortex tube cooler to minimize the surface roughness values. Machining parameters that is turning using rotary cutting tool at speed the workpiece of (Vw) 50, 120, 160 m/min, cutting speed of rotary tool of (Vt) 25, 50, 75 m/min, feed rate of (f) 0.1, 0.15, 0.2 mm/rev, and depth of cut of 0.3 mm. Type of tool used is a carbide tool diameter of 16 mm and air cooling pressure of 6 bar. The results show the average value of the lowest surface roughness on the speed the workpiece of 80 m/min, cutting speed of rotary tool of 50 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.3 mm. While the average value of the highest surface roughness on the speed the workpiece of 160 m/min, cutting speed of rotary tool of 50 m/min, feed rate of 0.2 mm/rev, and depth of cut of 0.3 mm. The influence of machining parameters concluded the higher the speed of the workpiece the surface roughness value higher. Otherwise the higher cutting speed of rotary tool then the lower the surface roughness value. The observation on the surface of the rotary tool, it was found that no uniform tool wear which causes non-uniform surface roughness. The use of rotary cutting tool contributing to lower surface roughness values generated.

  11. History and Surface Condition of the Lewis Chessmen in the Collection of the National Museums Scotland (Hebrides, late 12th-early 13th centuries)

    OpenAIRE

    Tate, Jim; Reiche, I.; Pinzari, F.; Clark, J.; Caldwell, D.

    2013-01-01

    This paper summarises on-going work to examine the surface condition of the 11 chess pieces in the collection of the National Museums Scotland. The chess pieces are part of the hoard found on the isle of Lewis on the west coast of Scotland and are remarkable examples of medieval ivory carving. The aim of the work is to characterise surface features that can be used to draw new information about the materials from which the pieces were made, their history from the period of their manufacture u...

  12. Fluid-solid boundary conditions for multiparticle collision dynamics

    International Nuclear Information System (INIS)

    Whitmer, Jonathan K; Luijten, Erik

    2010-01-01

    The simulation of colloidal particles suspended in solvent requires an accurate representation of the interactions between the colloids and the solvent molecules. Using the multiparticle collision dynamics method, we examine several proposals for stick boundary conditions, studying their properties in both plane Poiseuille flow (where fluid interacts with the boundary of a stationary macroscopic solid) and particle-based colloid simulations (where the boundaries are thermally affected and in motion). In addition, our simulations compare various collision rules designed to remove spurious slip near solid surfaces, and the effects of these rules on the thermal motion of colloidal particles. Furthermore, we demonstrate that stochastic reflection of the fluid at solid boundaries fails to faithfully represent stick boundary conditions, and conclude that bounce-back conditions should be applied at both mobile and stationary surfaces. Finally, we generalize these ideas to create partial slip boundary conditions at both stationary and mobile surfaces.

  13. Impact of roughness, wettability and hydrodynamic conditions on the incrustation on stainless steel surfaces

    International Nuclear Information System (INIS)

    Bogacz, Wojciech; Lemanowicz, Marcin; Al-Rashed, Mohsen H.; Nakonieczny, Damian; Piotrowski, Tomasz; Wójcik, Janusz

    2017-01-01

    Highlights: • Steel plates (X5CrNi18-10) with different roughness and wettability were prepared. • Incrustation of MgSO 4 ·7H 2 O under laminar flow (Re = 59–178) was investigated. • Influence of surface properties and fluid velocity on incrustation was found. • Wettability and surface roughness cannot be considered separately. • Analysis of heat transfer and incrustation time-lapse videos are presented. - Abstract: The goal of this work was to investigate the influence of the stainless steel surface roughness and wettability on incrustation of MgSO 4 ·7H 2 O from aqueous solutions and resulting heat transfer resistance. The experiments were done for laminar flow (Re = 59–178) which is characteristic for regions of apparatus where fouling usually begin. A series of steel plates (X5CrNi18-10) were prepared and used as a heat transfer surfaces. Their properties, i.e. roughness, wettability and elementary composition of surfaces were determined. The experiments were done using specially designed flow cell equipped with Peltier element. Each incrustation measurement lasted for two hours, during which heat transfer resistance was measured as a function of time. After the experiments the mass of crystalline deposit was weighted. It was proved that wettability as well as surface roughness cannot be considered separately in the case of incrustation phenomenon. The knowledge of surface roughness is insufficient due to the fact, that it is possible to obtain surfaces with similar roughness but substantially different wettability for the same material.

  14. Characterization of polymer surface structure and surface mechanical behaviour by sum frequency generation surface vibrational spectroscopy and atomic force microscopy

    International Nuclear Information System (INIS)

    Opdahl, Aric; Koffas, Telly S; Amitay-Sadovsky, Ella; Kim, Joonyeong; Somorjai, Gabor A

    2004-01-01

    Sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM) have been used to study polymer surface structure and surface mechanical behaviour, specifically to study the relationships between the surface properties of polymers and their bulk compositions and the environment to which the polymer is exposed. The combination of SFG surface vibrational spectroscopy and AFM has been used to study surface segregation behaviour of polyolefin blends at the polymer/air and polymer/solid interfaces. SFG surface vibrational spectroscopy and AFM experiments have also been performed to characterize the properties of polymer/liquid and polymer/polymer interfaces, focusing on hydrogel materials. A method was developed to study the surface properties of hydrogel contact lens materials at various hydration conditions. Finally, the effect of mechanical stretching on the surface composition and surface mechanical behaviour of phase-separated polyurethanes, used in biomedical implant devices, has been studied by both SFG surface vibrational spectroscopy and AFM. (topical review)

  15. The mechanical problems on additive manufacturing of viscoelastic solids with integral conditions on a surface increasing in the growth process

    Science.gov (United States)

    Parshin, D. A.; Manzhirov, A. V.

    2018-04-01

    Quasistatic mechanical problems on additive manufacturing aging viscoelastic solids are investigated. The processes of piecewise-continuous accretion of such solids are considered. The consideration is carried out in the framework of linear mechanics of growing solids. A theorem about commutativity of the integration over an arbitrary surface increasing in the solid growing process and the time-derived integral operator of viscoelasticity with a limit depending on the solid point is proved. This theorem provides an efficient way to construct on the basis of Saint-Venant principle solutions of nonclassical boundary-value problems for describing the mechanical behaviour of additively formed solids with integral satisfaction of boundary conditions on the surfaces expanding due to the additional material influx to the formed solid. The constructed solutions will retrace the evolution of the stress-strain state of the solids under consideration during and after the processes of their additive formation. An example of applying the proved theorem is given.

  16. The development of surface topography by heavy ion sputtering

    International Nuclear Information System (INIS)

    Whitton, J.L.; Carter, G.

    1981-01-01

    The results of a detailed, systematic investigation of the development of energetic argon ion bombardment induced surface features on polycrystal and single crystal copper are presented. It is shown that the crystal structure itself is the dominant factor deciding the final form of surface topography. The earlier proposed ''necessary conditions'' for development of surface topography, viz. surface impurity, asperities, growth, surface migration and redeposition are shown to be unimportant under the clean conditions of the experiments. (Auth.)

  17. Elastic interaction between surface and spherical pore

    International Nuclear Information System (INIS)

    Ganeev, G.Z.; Kadyrzhanov, K.K.; Kislitsyn, S.B.; Turkebaev, T.Eh.

    2000-01-01

    The energy of elastic interaction of a gas-filled spherical cavity with a boundary of an elastic isotropic half-space is determined. The elastic field of a system of a spherical cavity - boundary is represented as an expansion in series of potential functions. The factors of expansions are determined by boundary conditions on a free surface of an elastic half-space and on a spherical surface of a cavity with pressure of gas P. Function of a Tresca-Miesesa on a surface of elastic surface is defined additionally with purpose creep condition determination caused by gas pressure in the cavity. (author)

  18. Surface freezing of water.

    Science.gov (United States)

    Pérez-Díaz, J L; Álvarez-Valenzuela, M A; Rodríguez-Celis, F

    2016-01-01

    Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered-exclusively-by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. Humidity triggers surface freezing as soon as it overpasses a defined value for a given temperature, generating a plurality of nucleation nodes. An evidence of simultaneous nucleation of surface ice crystals is also provided.

  19. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated martian surface ultraviolet radiation conditions.

    Science.gov (United States)

    Poch, Olivier; Jaber, Maguy; Stalport, Fabien; Nowak, Sophie; Georgelin, Thomas; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-03-01

    Most of the phyllosilicates detected at the surface of Mars today are probably remnants of ancient environments that sustained long-term bodies of liquid water at the surface or subsurface and were possibly favorable for the emergence of life. Consequently, phyllosilicates have become the main mineral target in the search for organics on Mars. But are phyllosilicates efficient at preserving organic molecules under current environmental conditions at the surface of Mars? We monitored the qualitative and quantitative evolutions of glycine, urea, and adenine in interaction with the Fe(3+)-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K), and pressure (6 ± 1 mbar) in a laboratory simulation setup. We tested organic-rich samples that were representative of the evaporation of a small, warm pond of liquid water containing a high concentration of organics. For each molecule, we observed how the nontronite influences its quantum efficiency of photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine; their efficiencies of photodecomposition were reduced by a factor of 5 when mixed at a concentration of 2.6 × 10(-2) mol of molecules per gram of nontronite. Moreover, when the amount of nontronite in the sample of glycine was increased by a factor of 2, the gain of photoprotection was multiplied by a factor of 5. This indicates that the photoprotection provided by the nontronite is not a purely mechanical shielding effect but is also due to stabilizing interactions. No new evolution product was firmly identified, but the results obtained with urea suggest a particular reactivity in the presence of nontronite, leading to an increase of its dissociation rate.

  20. Conditioning of intermediate-level waste at Forschungszentrum Juelich GmbH

    International Nuclear Information System (INIS)

    Krumbach, H.

    2003-01-01

    This contribution to the group of low-level, intermediate, mixed and hazardous waste describes the conditioning of intermediate-level mixed waste (dose rate above 10 mSv/h at the surface) from Research Centre Juelich (FZJ). Conditioning of the waste by supercompaction is performed at Research Centre Karlsruhe (FZK). The waste described is radioactive waste arising from research at Juelich. This waste includes specimens and objects from irradiation experiments in the research reactors Merlin (FRJ-1) and Dido (FRJ-2) at FZJ. In principle, radioactive waste at Forschungszentrum Juelich GmbH is differentiated by the surface dose rate at the waste package. Up to a surface dose rate of 10 mSv/h, the waste is regarded as low-level. The radioactive waste described here has a surface dose rate above 10 mSv/h. Waste up to 10 mSv/h is conditioned at the Juelich site according to different conditioning methods. The intermediate-level waste can only be conditioned by supercompaction in the processing facility for intermediate-level waste from plant operation at Research Centre Karlsruhe. Research Centre Juelich also uses this waste cell to condition its intermediate-level waste from plant operation. (orig.)

  1. 29 CFR 1917.12 - Slippery conditions.

    Science.gov (United States)

    2010-07-01

    ... eliminate, to the extent possible, conditions causing slippery working and walking surfaces in immediate... 29 Labor 7 2010-07-01 2010-07-01 false Slippery conditions. 1917.12 Section 1917.12 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR...

  2. Potřeby klientů domu na půl cesty v rámci tvorby a realizace vlastních volnočasových aktivit a definování parametrů programu pro jejich podporu

    OpenAIRE

    Kholl, Pavel

    2013-01-01

    This diploma thesis deals with a leisure time of clients of the Halfway House. The aim of the thesis is to map the content and structure of their leisure time. The thesis seeks to define what the representatives of the target group need for better self realization. Based on these findings author of the thesis design a new program supporting their spending of leisure time. The thesis consists of two parts: theoretical part and practical part. The theoretical part presents a halfway house socia...

  3. Surface modification of gas diffusion layers by inorganic nanomaterials for performance enhancement of proton exchange membrane fuel cells at low RH conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cindrella, L. [Fuel Cell Research Lab, Engineering Technology Department, Arizona State University, 7001 E Williams Field Rd., Mesa, AZ 85212 (United States); Department of Chemistry, National Institute of Technology, Tiruchirappalli, Tamil Nadu 620015 (India); Kannan, A.M. [Fuel Cell Research Lab, Engineering Technology Department, Arizona State University, 7001 E Williams Field Rd., Mesa, AZ 85212 (United States); Ahmad, R.; Thommes, M. [Quantachrome Instruments, 1900 Corporate Drive, Boynton Beach, FL 33426 (United States)

    2009-08-15

    Prompted by our earlier study that fumed silica on gas diffusion layer (GDL) favored a performance improvement of the single fuel cell at lower RH conditions, the present study has been carried out with inorganic oxides in the nanoscale such as TiO{sub 2}, Al{sub 2}O{sub 3}, commercially available mixed oxides, hydrophilic silica and aerosil silica. The structure of each of the oxide coating on the GDL surface has resulted in refinement with graded pore dimension as seen from the Hg porosimetry data. The fuel cell evaluation at various RH conditions (50-100%) revealed that the performance of all the inorganic oxides loaded GDL is very high compared to that of pristine GDL. The results confirm our earlier observation that inorganic oxides on GDL bring about structural refinement favorable for the transport of gases, and their water retaining capacity enable a high performance of the fuel cell even at low RH conditions. (author)

  4. Natural emissions under future climate condition and their effects on surface ozone in the Yangtze River Delta region, China

    Science.gov (United States)

    Xie, Min; Shu, Lei; Wang, Ti-jian; Liu, Qian; Gao, Da; Li, Shu; Zhuang, Bing-liang; Han, Yong; Li, Meng-meng; Chen, Pu-long

    2017-02-01

    The natural emissions of ozone precursors (NOx and VOCs) are sensitive to climate. Future climate change can impact O3 concentrations by perturbing these emissions. To better estimate the variation of natural emissions under different climate conditions and understand its effect on surface O3, we model the present and the future air quality over the Yangtze River Delta (YRD) region by running different simulations with the aid of the WRF-CALGRID model system that contains a natural emission module. Firstly, we estimate the natural emissions at present and in IPCC A1B scenario. The results show that biogenic VOC emission and soil NOx emission over YRD in 2008 is 657 Gg C and 19.1 Gg N, respectively. According to climate change, these emissions in 2050 will increase by 25.5% and 11.5%, respectively. Secondly, the effects of future natural emissions and meteorology on surface O3 are investigated and compared. It is found that the variations in meteorological fields can significantly alter the spatial distribution of O3 over YRD, with the increases of 5-15 ppb in the north and the decreases of -5 to -15 ppb in the south. However, only approximately 20% of the surface O3 increases caused by climate change can be attributed to the natural emissions, with the highest increment up to 2.4 ppb. Finally, Ra (the ratio of impacts from NOx and VOCs on O3 formation) and H2O2/HNO3 (the ratio between the concentrations of H2O2 and HNO3) are applied to study the O3 sensitivity in YRD. The results show that the transition value of H2O2/HNO3 will turn from 0.3 to 0.5 in 2008 to 0.4-0.8 in 2050. O3 formation in the YRD region will be insensitive to VOCs under future climate condition, implying more NOx need to be cut down. Our findings can help us understand O3 variation trend and put forward the reasonable and effective pollution control policies in these famous polluted areas.

  5. Plasma–Surface Interactions Under High Heat and Particle Fluxes

    Directory of Open Access Journals (Sweden)

    Gregory De Temmerman

    2013-01-01

    Full Text Available The plasma-surface interactions expected in the divertor of a future fusion reactor are characterized by extreme heat and particle fluxes interacting with the plasma-facing surfaces. Powerful linear plasma generators are used to reproduce the expected plasma conditions and allow plasma-surface interactions studies under those very harsh conditions. While the ion energies on the divertor surfaces of a fusion device are comparable to those used in various plasma-assited deposition and etching techniques, the ion (and energy fluxes are up to four orders of magnitude higher. This large upscale in particle flux maintains the surface under highly non-equilibrium conditions and bring new effects to light, some of which will be described in this paper.

  6. Estimating environmental conditions affecting protozoal pathogen removal in surface water wetland systems using a multi-scale, model-based approach.

    Science.gov (United States)

    Daniels, Miles E; Hogan, Jennifer; Smith, Woutrina A; Oates, Stori C; Miller, Melissa A; Hardin, Dane; Shapiro, Karen; Los Huertos, Marc; Conrad, Patricia A; Dominik, Clare; Watson, Fred G R

    2014-09-15

    Cryptosporidium parvum, Giardia lamblia, and Toxoplasma gondii are waterborne protozoal pathogens distributed worldwide and empirical evidence suggests that wetlands reduce the concentrations of these pathogens under certain environmental conditions. The goal of this study was to evaluate how protozoal removal in surface water is affected by the water temperature, turbidity, salinity, and vegetation cover of wetlands in the Monterey Bay region of California. To examine how protozoal removal was affected by these environmental factors, we conducted observational experiments at three primary spatial scales: settling columns, recirculating wetland mesocosm tanks, and an experimental research wetland (Molera Wetland). Simultaneously, we developed a protozoal transport model for surface water to simulate the settling columns, the mesocosm tanks, and the Molera Wetland. With a high degree of uncertainty expected in the model predictions and field observations, we developed the model within a Bayesian statistical framework. We found protozoal removal increased when water flowed through vegetation, and with higher levels of turbidity, salinity, and temperature. Protozoal removal in surface water was maximized (~0.1 hour(-1)) when flowing through emergent vegetation at 2% cover, and with a vegetation contact time of ~30 minutes compared to the effects of temperature, salinity, and turbidity. Our studies revealed that an increase in vegetated wetland area, with water moving through vegetation, would likely improve regional water quality through the reduction of fecal protozoal pathogen loads. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Mechanics of active surfaces

    Science.gov (United States)

    Salbreux, Guillaume; Jülicher, Frank

    2017-09-01

    We derive a fully covariant theory of the mechanics of active surfaces. This theory provides a framework for the study of active biological or chemical processes at surfaces, such as the cell cortex, the mechanics of epithelial tissues, or reconstituted active systems on surfaces. We introduce forces and torques acting on a surface, and derive the associated force balance conditions. We show that surfaces with in-plane rotational symmetry can have broken up-down, chiral, or planar-chiral symmetry. We discuss the rate of entropy production in the surface and write linear constitutive relations that satisfy the Onsager relations. We show that the bending modulus, the spontaneous curvature, and the surface tension of a passive surface are renormalized by active terms. Finally, we identify active terms which are not found in a passive theory and discuss examples of shape instabilities that are related to active processes in the surface.

  8. Are atmospheric surface layer flows ergodic?

    Science.gov (United States)

    Higgins, Chad W.; Katul, Gabriel G.; Froidevaux, Martin; Simeonov, Valentin; Parlange, Marc B.

    2013-06-01

    The transposition of atmospheric turbulence statistics from the time domain, as conventionally sampled in field experiments, is explained by the so-called ergodic hypothesis. In micrometeorology, this hypothesis assumes that the time average of a measured flow variable represents an ensemble of independent realizations from similar meteorological states and boundary conditions. That is, the averaging duration must be sufficiently long to include a large number of independent realizations of the sampled flow variable so as to represent the ensemble. While the validity of the ergodic hypothesis for turbulence has been confirmed in laboratory experiments, and numerical simulations for idealized conditions, evidence for its validity in the atmospheric surface layer (ASL), especially for nonideal conditions, continues to defy experimental efforts. There is some urgency to make progress on this problem given the proliferation of tall tower scalar concentration networks aimed at constraining climate models yet are impacted by nonideal conditions at the land surface. Recent advancements in water vapor concentration lidar measurements that simultaneously sample spatial and temporal series in the ASL are used to investigate the validity of the ergodic hypothesis for the first time. It is shown that ergodicity is valid in a strict sense above uniform surfaces away from abrupt surface transitions. Surprisingly, ergodicity may be used to infer the ensemble concentration statistics of a composite grass-lake system using only water vapor concentration measurements collected above the sharp transition delineating the lake from the grass surface.

  9. Modeling driver stop/run behavior at the onset of a yellow indication considering driver run tendency and roadway surface conditions.

    Science.gov (United States)

    Elhenawy, Mohammed; Jahangiri, Arash; Rakha, Hesham A; El-Shawarby, Ihab

    2015-10-01

    The ability to model driver stop/run behavior at signalized intersections considering the roadway surface condition is critical in the design of advanced driver assistance systems. Such systems can reduce intersection crashes and fatalities by predicting driver stop/run behavior. The research presented in this paper uses data collected from two controlled field experiments on the Smart Road at the Virginia Tech Transportation Institute (VTTI) to model driver stop/run behavior at the onset of a yellow indication for different roadway surface conditions. The paper offers two contributions. First, it introduces a new predictor related to driver aggressiveness and demonstrates that this measure enhances the modeling of driver stop/run behavior. Second, it applies well-known artificial intelligence techniques including: adaptive boosting (AdaBoost), random forest, and support vector machine (SVM) algorithms as well as traditional logistic regression techniques on the data in order to develop a model that can be used by traffic signal controllers to predict driver stop/run decisions in a connected vehicle environment. The research demonstrates that by adding the proposed driver aggressiveness predictor to the model, there is a statistically significant increase in the model accuracy. Moreover the false alarm rate is significantly reduced but this reduction is not statistically significant. The study demonstrates that, for the subject data, the SVM machine learning algorithm performs the best in terms of optimum classification accuracy and false positive rates. However, the SVM model produces the best performance in terms of the classification accuracy only. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Laser surface texturing of tool steel: textured surfaces quality evaluation

    Science.gov (United States)

    Šugár, Peter; Šugárová, Jana; Frnčík, Martin

    2016-05-01

    In this experimental investigation the laser surface texturing of tool steel of type 90MnCrV8 has been conducted. The 5-axis highly dynamic laser precision machining centre Lasertec 80 Shape equipped with the nano-second pulsed ytterbium fibre laser and CNC system Siemens 840 D was used. The planar and spherical surfaces first prepared by turning have been textured. The regular array of spherical and ellipsoidal dimples with a different dimensions and different surface density has been created. Laser surface texturing has been realized under different combinations of process parameters: pulse frequency, pulse energy and laser beam scanning speed. The morphological characterization of ablated surfaces has been performed using scanning electron microscopy (SEM) technique. The results show limited possibility of ns pulse fibre laser application to generate different surface structures for tribological modification of metallic materials. These structures were obtained by varying the processing conditions between surface ablation, to surface remelting. In all cases the areas of molten material and re-cast layers were observed on the bottom and walls of the dimples. Beside the influence of laser beam parameters on the machined surface quality during laser machining of regular hemispherical and elipsoidal dimple texture on parabolic and hemispherical surfaces has been studied.

  11. The decontamination of soft-plated nickel surfaces compared to alternative surface materials used in radioactive transport and storage containers

    International Nuclear Information System (INIS)

    Zwicky, H.U.; Bedenig, D.O.; Bohringer, I.M.; Petrik, F.

    1983-01-01

    Surfaces of raw, nickel-plated, and epoxy-coated spheroidal graphite cast iron, together with stainless steel, were contaminated with a modified fission product solution then conditioned by heat treatment. This was followed by a variety of simple decontamination techniques. It was shown that the ease of removal of contaminations similar to those expected on a dry storage container surface is significantly affected by the roughness of the surface. The raw cast iron surface was virtually impossible to significantly decontaminate. Highest decontamination factors were obtained on nickel-plated and epoxy-painted surfaces using steam/detergent mixtures. Stainless steel only performed well in a polished condition. In a supplementary irradiation experiment, scanning electron microscopy indicated visible decomposition of an epoxy-painted surface at a gamma dose of 3.1 X 10 6 Gy (3.1 X 10 8 rad). A nickel-plated surface did not undergo any visible changes at the same dose

  12. The role of the style as a sense-organ in relation to wilting of the flower.

    Science.gov (United States)

    Gilissen, L J

    1976-01-01

    Pollen tube growth in the style (Petunia ♀xNicotiana ♂) accelerated wilting. Pollination and germination on the stigmatic surface (Petunia ♀xAtropa ♂) did not change the stage of flowering in comparison with unpollinated flowers. Wilting of the corolla was accelerated by cutting off the stigma or cutting the style half-way down. Removal of the entire style also brought about an acceleration, however, to a lesser extent. The role of the style as a sense-organ with regard to the transmission of information from stigma and style to other flower organs is discussed.

  13. He implantation induced nanovoids in crystalline Si

    International Nuclear Information System (INIS)

    Kilpelaeinen, S.; Kuitunen, K.; Slotte, J.; Tuomisto, F.; Bruno, E.; Mirabella, S.; Priolo, F.

    2009-01-01

    Positron annihilation spectroscopy (PAS) in Doppler broadening mode was used to study the vacancy profile of crystalline Si after He and B implantation and subsequent annealing. In the He-implanted samples two different void layers were observed, one consisting of large voids at the projected range of He and another containing 'nanovoids' slightly larger than divacancies at roughly halfway between R p of He and the surface. The nanovoid layer was shown to be absent from samples co-implanted with B, implying that interstitials created during B implantation get trapped in the nanovoids and fill them, thus hindering interstitial-mediated B diffusion.

  14. Correlation between processing conditions of Cu2ZnSn(SxSe1-x)4 and modulated surface photovoltage

    Science.gov (United States)

    Lin, X. Z.; Dittrich, Th.; Fengler, S.; Lux-Steiner, M. Ch.; Ennaoui, A.

    2013-04-01

    Cu2ZnSn(SxSe1-x)4 (CZTSSe) layers deposited from multi-component nanoparticle inks were characterized by modulated surface photovoltage (SPV) spectroscopy to investigate the effect of annealing conditions. The SPV signals increased strongly with decreasing sulfur content. Band gaps were obtained in terms of SPV onset energy. A diffusion length of above 1 μm was estimated for photo-generated electrons at x = 0.28. The band gap increased with increasing x showing an anomaly in the range of 0.5 < x < 1. The results suggested that an excess of selenium is required for the formation of a photo-active phase reliable for efficient Cu2ZnSn(SxSe1-x)4-based solar cells.

  15. Boundary conditions on the plasma emitter surface in the presence of a particle counter flow: I. Ion emitter

    Energy Technology Data Exchange (ETDEWEB)

    Astrelin, V. T., E-mail: V.T.Astrelin@inp.nsk.su; Kotelnikov, I. A. [Russian Academy of Sciences, Budker Institute of Nuclear Physics, Siberian Branch (Russian Federation)

    2017-02-15

    Emission of positively charged ions from a plasma emitter irradiated by a counterpropagating electron beam is studied theoretically. A bipolar diode with a plasma emitter in which the ion temperature is lower than the electron temperature and the counter electron flow is extracted from the ion collector is calculated in the one-dimensional model. An analog of Bohm’s criterion for ion emission in the presence of a counterpropagating electron beam is derived. The limiting density of the counterpropagating beam in a bipolar diode operating in the space-charge-limited-emission regime is calculated. The full set of boundary conditions on the plasma emitter surface that are required for operation of the high-current optics module in numerical codes used to simulate charged particle sources is formulated.

  16. Functional levels of floor surface roughness for the prevention of slips and falls: clean-and-dry and soapsuds-covered wet surfaces.

    Science.gov (United States)

    Kim, In-Ju; Hsiao, Hongwei; Simeonov, Peter

    2013-01-01

    Literature has shown a general trend that slip resistance performance improves with floor surface roughness. However, whether slip resistance properties are linearly correlated with surface topographies of the floors or what roughness levels are required for effective slip resistance performance still remain to be answered. This pilot study aimed to investigate slip resistance properties and identify functional levels of floor surface roughness for practical design applications in reducing the risk of slip and fall incidents. A theory model was proposed to characterize functional levels of surface roughness of floor surfaces by introducing a new concept of three distinctive zones. A series of dynamic friction tests were conducted using 3 shoes and 9 floor specimens under clean-and-dry as well as soapsuds-covered slippery wet environments. The results showed that all the tested floor-shoe combinations provided sufficient slip resistances performance under the clean-and-dry condition. A significant effect of floor type (surface roughness) on dynamic friction coefficient (DFC) was found in the soapsuds-covered wet condition. As compared to the surface roughness effects, the shoe-type effects were relatively small. Under the soapsuds-covered wet condition, floors with 50 μm in Ra roughness scale seemed to represent an upper bound in the functional range of floor surface roughness for slip resistance because further increase of surface roughness provided no additional benefit. A lower bound of the functional range for slip resistance under the soapsuds-covered wet condition was estimated from the requirement of DFC > 0.4 at Ra ≅ 17 μm. Findings from this study may have potential safety implications in the floor surface design for reducing slip and fall hazards. Published by Elsevier Ltd.

  17. Impact of surface coating and environmental conditions on the fate and transport of silver nanoparticles in the aquatic environment

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, Laura-Jayne A.; Valsami-Jones, Eugenia [School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Lead, Jamie R., E-mail: Jlead@mailbox.sc.edu [School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Center for Environmental Nanoscience and Risk (CENR), Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia 29208 (United States); Baalousha, Mohammed, E-mail: Mbaalous@mailbox.sc.edu [Center for Environmental Nanoscience and Risk (CENR), Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia 29208 (United States)

    2016-10-15

    The role of surface coating (polyvinylpyrrolidone (PVP) and citrate) and water chemistry on the fate and behavior of AgNPs in aquatic microcosms is reported in this study. The migration and transformation of the AgNPs was examined in low (ultrapure water-UPW) and high ionic strength (moderately hard water – MHW) preparations, and in the presence of modeled natural organic matter (NOM) of Suwannee River Fulvic Acid (SRFA). The migration and fate of the AgNPs in the microcosms was validated using a sedimentation-diffusion model and the aggregation behavior was monitored by UV–visible spectrometry (UV–vis). Dissolved and particulate Ag concentrations (% Ag) were analyzed by ultrafiltration methods. Imaging of the AgNPs was captured using transmission electron microscopy (TEM). Results indicate that PVP-coated AgNPs (PVP-AgNPs) remained stable for 28 days with similarly distributed concentrations of the PVP-AgNPs throughout the columns in each of the water conditions after approximately 96 h (4 days). The sedimentation-diffusion model confirmed PVP-AgNP stability in each condition, by showing diffusion dominated transport by using the original unaltered AgNP sizes to fit the parameters. In comparison, citrate AgNPs were largely unstable in the more complex water preparations (MHW). In MHW, aggregation dominated behavior followed by sedimentation/dissolution controlled transport was observed. The addition of SRFA to MHW resulted in small stabilizing effects, to the citrate coated AgNPs, producing smaller sized AgNPs (TEM) and mixed sedimentation and diffusion migration compared the studies absent of SRFA. The results suggest that surface coating and solution chemistry has a major impact on AgNP stability, furthermore the corresponding modeling will support the experimental understanding of the overall fate of AgNPs in the environment. - Highlights: • Aquatic microcosms were used to study the transport and behavior of AgNPs • Experiments were conducted in low

  18. Impact of surface coating and environmental conditions on the fate and transport of silver nanoparticles in the aquatic environment

    International Nuclear Information System (INIS)

    Ellis, Laura-Jayne A.; Valsami-Jones, Eugenia; Lead, Jamie R.; Baalousha, Mohammed

    2016-01-01

    The role of surface coating (polyvinylpyrrolidone (PVP) and citrate) and water chemistry on the fate and behavior of AgNPs in aquatic microcosms is reported in this study. The migration and transformation of the AgNPs was examined in low (ultrapure water-UPW) and high ionic strength (moderately hard water – MHW) preparations, and in the presence of modeled natural organic matter (NOM) of Suwannee River Fulvic Acid (SRFA). The migration and fate of the AgNPs in the microcosms was validated using a sedimentation-diffusion model and the aggregation behavior was monitored by UV–visible spectrometry (UV–vis). Dissolved and particulate Ag concentrations (% Ag) were analyzed by ultrafiltration methods. Imaging of the AgNPs was captured using transmission electron microscopy (TEM). Results indicate that PVP-coated AgNPs (PVP-AgNPs) remained stable for 28 days with similarly distributed concentrations of the PVP-AgNPs throughout the columns in each of the water conditions after approximately 96 h (4 days). The sedimentation-diffusion model confirmed PVP-AgNP stability in each condition, by showing diffusion dominated transport by using the original unaltered AgNP sizes to fit the parameters. In comparison, citrate AgNPs were largely unstable in the more complex water preparations (MHW). In MHW, aggregation dominated behavior followed by sedimentation/dissolution controlled transport was observed. The addition of SRFA to MHW resulted in small stabilizing effects, to the citrate coated AgNPs, producing smaller sized AgNPs (TEM) and mixed sedimentation and diffusion migration compared the studies absent of SRFA. The results suggest that surface coating and solution chemistry has a major impact on AgNP stability, furthermore the corresponding modeling will support the experimental understanding of the overall fate of AgNPs in the environment. - Highlights: • Aquatic microcosms were used to study the transport and behavior of AgNPs • Experiments were conducted in low

  19. Surface microstructure replication in injection molding

    DEFF Research Database (Denmark)

    Theilade, Uffe Arlø; Hansen, Hans Nørgaard

    2006-01-01

    topography is transcribed onto the plastic part through complex mechanisms. This replication, however, is not perfect, and the replication quality depends on the plastic material properties, the topography itself, and the process conditions. This paper describes and discusses an investigation of injection...... molding of surface microstructures. The fundamental problem of surface microstructure replication has been studied. The research is based on specific microstructures as found in lab-on-a-chip products and on rough surfaces generated from EDM (electro discharge machining) mold cavities. Emphasis is put...... on the ability to replicate surface microstructures under normal injection-molding conditions, i.e., with commodity materials within typical process windows. It was found that within typical process windows the replication quality depends significantly on several process parameters, and especially the mold...

  20. Unified formulation of radiation conditions for the wave equation

    DEFF Research Database (Denmark)

    Krenk, Steen

    2002-01-01

    A family of radiation conditions for the wave equation is derived by truncating a rational function approxiamtion of the corresponding plane wave representation, and it is demonstrated how these boundary conditions can be formulated in terms of fictitious surface densities, governed by second......-order wave equations on the radiating surface. Several well-established radiation boundary conditions appear as special cases, corresponding to different choice of the coefficients in the rational approximation. The relation between these choices is established, and an explicit formulation in terms...

  1. Macroscopic and radiographic examination of proximal root surface caries

    International Nuclear Information System (INIS)

    Nordenram, G.; Bergvist, A.; Johnson, G.; Henriksen, C.O.; Anneroth, G.

    1988-01-01

    The purpose of the study was to compare macroscopic and radiographic examination of proximal root surface caries of extracted teeth from patients aged 65-95 years. Although the study conditions for macroscopic and radiographic diagnosis favored more sensitive evaluations than routine clinical conditions, there was a 24% disagreement in diagnosis. This finding indicates that under routine clinical conditions it is difficult to register with certainty all superficial root carious lesions. Even in the absence of clinically detectable root surface caries, preventive measures should be considered for elderly people with exposed root surfaces

  2. Superparamagnetic iron oxide coated on the surface of cellulose nanospheres for the rapid removal of textile dye under mild condition

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Yunfeng [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Qin, Zongyi, E-mail: phqin@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Liu, Yannan; Cheng, Miao; Qian, Pengfei [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Qian, E-mail: drwangqian23@163.com [Department of Orthopaedics, Shanghai First People' s Hospital, Shanghai Jiaotong University, 100 Haining Road, Hongkou District, Shanghai 200080 (China); Zhu, Meifang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, and College of Material Science and Engineering, Donghua University, Shanghai 201620 (China)

    2015-12-01

    Graphical abstract: - Highlights: • Anchoring superparamagnetic iron oxide on the surface of cellulose nanospheres as magnetically recyclable nanocatalys. • Achieving highly efficient Fenton-like reaction on the surface of composite nanospheres for rapid removal of textile dye. • Reaching nearly 98.0% degradation of Navy blue within 5 min under mild condition. - Abstract: Magnetic composite nanoparticles (MNPs) were prepared by anchoring iron oxide (Fe{sub 3}O{sub 4}) on the surface of carboxyl cellulose nanospheres through a facile chemical co-precipitation method. The as-prepared MNPs were characterized by atomic force microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction measurement, thermal gravity analysis and vibrating sample magnetometry. These MNPs were of a generally spherical shape with a narrow size distribution, and exhibited superparamagnetic behaviors with high saturation magnetization. High efficient removal of Navy blue in aqueous solution was demonstrated at room temperature in a Fenton-like system containing the MNPs and H{sub 2}O{sub 2}, which benefited from small particle size, large surface area, high chemical activity, and good dispersibility of the MNPs. The removal efficiency of Navy blue induced by the MNPs prepared at a weight ratio of cellulose to iron of 1:2 were 90.6% at the first minute of the degradation reaction, and 98.0% for 5 min. Furthermore, these MNPs could be efficiently recycled and reused by using an external magnetic field. The approach presented in this paper promotes the use of renewable natural resources as templates for the preparation and stabilization of various inorganic nanomaterials for the purpose of catalysis, magnetic resonance imaging, biomedical and other potential applications.

  3. Tensile Bond Strength of Metal Bracket Bonding to Glazed Ceramic Surfaces With Different Surface Conditionings

    Directory of Open Access Journals (Sweden)

    M. Imani

    2011-12-01

    Full Text Available Objective: The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments.Materials and Methods: Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA. Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primerand adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively.Results: The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (P<0.01.Conclusion: In spite of limitations in laboratory studies it may be concluded that in application of Scotch bond multipurpose plus adhesive, phosphoric acid can be used instead of HFA for bonding brackets to the glazed ceramic restorations with enough tensile bond strength.

  4. A novel surface cleaning method for chemical removal of fouling lead layer from chromium surfaces

    International Nuclear Information System (INIS)

    Gholivand, Kh.; Khosravi, M.; Hosseini, S.G.; Fathollahi, M.

    2010-01-01

    Most products especially metallic surfaces require cleaning treatment to remove surface contaminations that remain after processing or usage. Lead fouling is a general problem which arises from lead fouling on the chromium surfaces of bores and other interior parts of systems which have interaction with metallic lead in high temperatures and pressures. In this study, a novel chemical solution was introduced as a cleaner reagent for removing metallic lead pollution, as a fouling metal, from chromium surfaces. The cleaner aqueous solution contains hydrogen peroxide (H 2 O 2 ) as oxidizing agent of lead layer on the chromium surface and acetic acid (CH 3 COOH) as chelating agent of lead ions. The effect of some experimental parameters such as acetic acid concentration, hydrogen peroxide concentration and temperature of the cleaner solution during the operation on the efficiency of lead cleaning procedure was investigated. The results of scanning electron microscopy (SEM) showed that using this procedure, the lead pollution layer could be completely removed from real chromium surfaces without corrosion of the original surface. Finally, the optimum conditions for the complete and fast removing of lead pollution layer from chromium surfaces were proposed. The experimental results showed that at the optimum condition (acetic acid concentration 28% (V/V), hydrogen peroxide 8% (V/V) and temperature 35 deg. C), only 15-min time is needed for complete removal of 3 g fouling lead from a chromium surface.

  5. FDTD Investigation on Electromagnetic Scattering from Two-Layered Rough Surfaces under UPML Absorbing Condition

    International Nuclear Information System (INIS)

    Juan, Li; Li-Xin, Guo; Hao, Zeng

    2009-01-01

    Electromagnetic scattering from one-dimensional two-layered rough surfaces is investigated by using finite-difference time-domain algorithm (FDTD). The uniaxial perfectly matched layer (UPML) medium is adopted for truncation of FDTD lattices, in which the finite-difference equations can be used for the total computation domain by properly choosing the uniaxial parameters. The rough surfaces are characterized with Gaussian statistics for the height and the autocorrelation function. The angular distribution of bistatic scattering coefficient from single-layered perfect electric conducting and dielectric rough surface is calculated and it is in good agreement with the numerical result with the conventional method of moments. The influence of the relative permittivity, the incident angle, and the correlative length of two-layered rough surfaces on the bistatic scattering coefficient with different polarizations are presented and discussed in detail. (fundamental areas of phenomenology (including applications))

  6. Manipulating surface wettability and oil absorbency of diatomite depending on processing and ambient conditions

    Science.gov (United States)

    Özen, İlhan; Şimşek, Süleyman; Okyay, Gamze

    2015-03-01

    In this study, a diatomite sample, which is a natural inorganic mineral with inherently high water and oil absorption capacity, was subjected to grinding before surface modification. Afterwards, the diatomite surface was modified via facile methods using a fluorocarbon (FC) chemical and stearic acid (SA) in addition to the sol-gel fluorosilanization (FS) process. The water and oil wettability, and oil absorbency properties of the unmodified and modified diatomites were investigated in addition to diatomite characterizations such as chemical content, surface area, particle size distribution, morphology, and modification efficiency. It was revealed that the wettability was changed completely depending on the surface modification agent and the media used, while the oil absorbency property surprisingly did not change. On the other hand, the oil absorbency was worsened by the grinding process, whereas the wettability was not affected.

  7. Preservation of atomically clean silicon surfaces in air by contact bonding

    DEFF Research Database (Denmark)

    Grey, Francois; Ljungberg, Karin

    1997-01-01

    When two hydrogen-passivated silicon surfaces are placed in contact under cleanroom conditions, a weak bond is formed. Cleaving this bond under ultrahigh vacuum (UHV) conditions, and observing the surfaces with low energy electron diffraction and scanning tunneling microscopy, we find that the or...... reconstruction from oxidation in air, Contact bonding opens the way to novel applications of reconstructed semiconductor surfaces, by preserving their atomic structure intact outside of a UHV chamber. (C) 1997 American Institute of Physics.......When two hydrogen-passivated silicon surfaces are placed in contact under cleanroom conditions, a weak bond is formed. Cleaving this bond under ultrahigh vacuum (UHV) conditions, and observing the surfaces with low energy electron diffraction and scanning tunneling microscopy, we find...... that the ordered atomic structure of the surfaces is protected from oxidation, even after the bonded samples have been in air for weeks. Further, we show that silicon surfaces that have been cleaned and hydrogen-passivated in UHV can be contacted in UHV in a similarly hermetic fashion, protecting the surface...

  8. Flow boundary conditions for chain-end adsorbing polymer blends.

    Science.gov (United States)

    Zhou, Xin; Andrienko, Denis; Delle Site, Luigi; Kremer, Kurt

    2005-09-08

    Using the phenol-terminated polycarbonate blend as an example, we demonstrate that the hydrodynamic boundary conditions for a flow of an adsorbing polymer melt are extremely sensitive to the structure of the epitaxial layer. Under shear, the adsorbed parts (chain ends) of the polymer melt move along the equipotential lines of the surface potential whereas the adsorbed additives serve as the surface defects. In response to the increase of the number of the adsorbed additives the surface layer becomes thinner and solidifies. This results in a gradual transition from the slip to the no-slip boundary condition for the melt flow, with a nonmonotonic dependence of the slip length on the surface concentration of the adsorbed ends.

  9. Tritium loading in ITER plasma-facing surfaces and its release under accident conditions

    International Nuclear Information System (INIS)

    Longhurst, G.R.; Anderl, R.A.; Pawelko, R.J.

    1996-01-01

    Plasma-facing surfaces of the International Thermonuclear Experimental Reactor (ITER) will take up tritium from the plasma. These surfaces will probably consist of matures of Be, C, and possibly W together with other impurities. Recent experimental results have suggested mechanisms, not previously considered in analyses, by which tritium and other hydrogen isotopes are retained in Be. This warrants revised modeling and estimation of the amount of tritium that will be deposited in ITER beryllium plasma-facing surfaces and the rates at which it can be released under postulated accident scenarios. In this paper we describe improvements in modeling and experiments planned at the Idaho National Engineering Laboratory (INEL) to investigate the tritium uptake and thermal release behavior for mixed plasma- facing materials. TMAP4 calculations were made using recent data to estimate first-wall tritium inventories in ITER. 16 refs., 1 fig

  10. Automotive System for Remote Surface Classification.

    Science.gov (United States)

    Bystrov, Aleksandr; Hoare, Edward; Tran, Thuy-Yung; Clarke, Nigel; Gashinova, Marina; Cherniakov, Mikhail

    2017-04-01

    In this paper we shall discuss a novel approach to road surface recognition, based on the analysis of backscattered microwave and ultrasonic signals. The novelty of our method is sonar and polarimetric radar data fusion, extraction of features for separate swathes of illuminated surface (segmentation), and using of multi-stage artificial neural network for surface classification. The developed system consists of 24 GHz radar and 40 kHz ultrasonic sensor. The features are extracted from backscattered signals and then the procedures of principal component analysis and supervised classification are applied to feature data. The special attention is paid to multi-stage artificial neural network which allows an overall increase in classification accuracy. The proposed technique was tested for recognition of a large number of real surfaces in different weather conditions with the average accuracy of correct classification of 95%. The obtained results thereby demonstrate that the use of proposed system architecture and statistical methods allow for reliable discrimination of various road surfaces in real conditions.

  11. EFFECT OF SURFACE CONDTIONINGON BOND STRENGTH TO ENAMEL AND DENTIN

    Directory of Open Access Journals (Sweden)

    M MOUSAVINASAB

    2002-09-01

    Full Text Available Introduction. Compoglass is a trade mark of dental compomers and because of its partially resinus structure, surface conditioning of dental surfaces is needed for a better bonding process. In this study, the effect of enamel and dentin conditioning procedure on shear bond strength (SBS of compoglass to tooth surfaces was studied. Methods. four groups each one including 11 sound premolars were chosen and their surfaces were prepared as following groups: group1, unconitioned dentin; group 2, dentin conditioning with phosphoric acid 35%; group 3, dentin conditioning with polyacrylic acid 20% group 4, unconditioning enamel; group 5, enamel conditioning with phosphoric acid 35%; and group 6, enamel conditioning with polyacrylic acid 20%. Compoglass was bonded to prepared surfaces and after fixation of the samples in acrylic molds, all samples were tested under shear force of instron testing machine at a rate of 1 mm/min speed. Results. The mean SBS obtained in these 6 groups were 6.207, 8.057, 10.146, 25.939 and 11.827 mpa. the mode of fracture also studied using a streomicroscope. Statistical analysis of the results showed that the maximum SBS obtained in group 5 and the lowest SBS about 6.207 mpa obtained in group 1. Despite increase in SBS group 2 and 3, there was no statistical differncies between group 1, 2 and 3. Discussion. Based on results of this study, conditioning of enamel and dentin surface due to improve SBS is recommeneded.

  12. 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)

  13. 49 CFR 572.21 - Test conditions and instrumentation.

    Science.gov (United States)

    2010-10-01

    ...-Year-Old Child § 572.21 Test conditions and instrumentation. (a)(1) The test probe used for head and... surface of the lumbar spine, and 0.3 inches dorsal to the accelerometer mounting plate surface. (1) The.... For thorax and lumbar spine tests, the seating surface is without the back support as shown in Figures...

  14. PHOTOGRAMMETRIC TECHNIQUES FOR ROAD SURFACE ANALYSIS

    Directory of Open Access Journals (Sweden)

    V. A. Knyaz

    2016-06-01

    Full Text Available The quality and condition of a road surface is of great importance for convenience and safety of driving. So the investigations of the behaviour of road materials in laboratory conditions and monitoring of existing roads are widely fulfilled for controlling a geometric parameters and detecting defects in the road surface. Photogrammetry as accurate non-contact measuring method provides powerful means for solving different tasks in road surface reconstruction and analysis. The range of dimensions concerned in road surface analysis can have great variation from tenths of millimetre to hundreds meters and more. So a set of techniques is needed to meet all requirements of road parameters estimation. Two photogrammetric techniques for road surface analysis are presented: for accurate measuring of road pavement and for road surface reconstruction based on imagery obtained from unmanned aerial vehicle. The first technique uses photogrammetric system based on structured light for fast and accurate surface 3D reconstruction and it allows analysing the characteristics of road texture and monitoring the pavement behaviour. The second technique provides dense 3D model road suitable for road macro parameters estimation.

  15. Evaluation of optimum conditions for pachyman encapsulated in poly(D,L-lactic acid nanospheres by response surface methodology and results of a related in vitro study

    Directory of Open Access Journals (Sweden)

    Zheng S

    2016-09-01

    Full Text Available Sisi Zheng, Li Luo, Ruonan Bo, Zhenguang Liu, Jie Xing, Yale Niu, Yuanliang Hu, Jiaguo Liu, Deyun Wang Institute of Traditional Chinese Veterinary Medicine, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, People’s Republic of China Abstract: This study aimed to optimize the preparation conditions of pachyman (PHY-loaded poly(D,L-lactic acid (PLA (PHYP nanospheres by response surface methodology, explore their characteristics, and assess their effects on splenic lymphocytes. Double emulsion solvent evaporation was used to synthesize PHYP nanospheres, and the optimal preparation conditions were identified as a concentration of poloxamer 188 (F68 (w/v of 0.33%, a concentration of PLA of 30 mg/mL, and a ratio of PLA to drug (w/w of 10.25:1 required to reach the highest encapsulation efficiency, which was calculated to be 59.10%. PHYP had a spherical shape with a smooth surface and uniform size and an evident effect of sustained release and relative stability. Splenic lymphocytes are crucial and multifunctional cells in the immune system, and their immunological properties could be enhanced significantly by PHYP treatment. This study confirmed that PHY encapsulated in PLA nanospheres had comparatively steady properties and exerted obvious immune enhancement. Keywords: PHYP, optimal preparation condition, RSM, in vitro study

  16. Reconnoitering the effect of shallow groundwater on land surface temperature and surface energy balance using MODIS and SEBS

    Directory of Open Access Journals (Sweden)

    F. Alkhaier

    2012-07-01

    Full Text Available The possibility of observing shallow groundwater depth and areal extent using satellite measurements can support groundwater models and vast irrigation systems management. Moreover, these measurements can help to include the effect of shallow groundwater on surface energy balance within land surface models and climate studies, which broadens the methods that yield more reliable and informative results. To examine the capacity of MODIS in detecting the effect of shallow groundwater on land surface temperature and the surface energy balance in an area within Al-Balikh River basin in northern Syria, we studied the interrelationship between in-situ measured water table depths and land surface temperatures measured by MODIS. We, also, used the Surface Energy Balance System (SEBS to calculate surface energy fluxes, evaporative fraction and daily evaporation, and inspected their relationships with water table depths. We found out that the daytime temperature increased while the nighttime temperature decreased when the depth of the water table increased. And, when the water table depth increased, net radiation, latent and ground heat fluxes, evaporative fraction and daily evaporation decreased, while sensible heat flux increased. This concords with the findings of a companion paper (Alkhaier et al., 2012. The observed clear relationships were the result of meeting both conditions that were concluded in the companion paper, i.e. high potential evaporation and big contrast in day-night temperature. Moreover, the prevailing conditions in this study area helped SEBS to yield accurate estimates. Under bare soil conditions and under the prevailing weather conditions, we conclude that MODIS is suitable for detecting the effect of shallow groundwater because it has proper imaging times and adequate sensor accuracy; nevertheless, its coarse spatial resolution is disadvantageous.

  17. Modeling of the effect of freezer conditions on the principal constituent parameters of ice cream by using response surface methodology.

    Science.gov (United States)

    Inoue, K; Ochi, H; Taketsuka, M; Saito, H; Sakurai, K; Ichihashi, N; Iwatsuki, K; Kokubo, S

    2008-05-01

    A systematic analysis was carried out by using response surface methodology to create a quantitative model of the synergistic effects of conditions in a continuous freezer [mix flow rate (L/h), overrun (%), cylinder pressure (kPa), drawing temperature ( degrees C), and dasher speed (rpm)] on the principal constituent parameters of ice cream [rate of fat destabilization (%), mean air cell diameter (mum), and mean ice crystal diameter (mum)]. A central composite face-centered design was used for this study. Thirty-one combinations of the 5 above-mentioned freezer conditions were designed (including replicates at the center point), and ice cream samples were manufactured and examined in a continuous freezer under the selected conditions. The responses were the 3 variables given above. A quadratic model was constructed, with the freezer conditions as the independent variables and the ice cream characteristics as the dependent variables. The coefficients of determination (R(2)) were greater than 0.9 for all 3 responses, but Q(2), the index used here for the capability of the model for predicting future observed values of the responses, was negative for both the mean ice crystal diameter and the mean air cell diameter. Therefore, pruned models were constructed by removing terms that had contributed little to the prediction in the original model and by refitting the regression model. It was demonstrated that these pruned models provided good fits to the data in terms of R(2), Q(2), and ANOVA. The effects of freezer conditions were expressed quantitatively in terms of the 3 responses. The drawing temperature ( degrees C) was found to have a greater effect on ice cream characteristics than any of the other factors.

  18. Surface physics : experimental

    International Nuclear Information System (INIS)

    Padalia, B.D.

    1978-01-01

    In this report, discussion is confined to some important ultra high vacuum surface techniques such as ultra-violet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and the low energy electron diffraction (LEED). An attempt is made to cover the basic principles and the experimental details of XPS and AES. Selected examples illustrating the potentialities of the above techniques to solve the important basic as well as applied problems relating to surfaces are presented. Salient features of the available commercial machines in which UPS, AES and LEED are combined to facilitate surface examination sequentially or simultaneously under identical experimental conditions are indicated. (auth.)

  19. Update on Simulating Ice-Cliff Failure

    Science.gov (United States)

    Parizek, B. R.; Christianson, K. A.; Alley, R. B.; Voytenko, D.; Vankova, I.; Dixon, T. H.; Walker, R. T.; Holland, D.

    2017-12-01

    Using a 2D full-Stokes diagnostic ice-flow model and engineering and glaciological failure criteria, we simulate the limiting physical conditions for rapid structural failure of subaerial ice cliffs. Previously, using a higher-order flowline model, we reported that the threshold height, in crevassed ice and/or under favorable conditions for hydrofracture or crack lubrication, may be only slightly above the 100-m maximum observed today and that under well-drained or low-melt conditions, mechanically-competent ice supports cliff heights up to 220 m (with a likely range of 180-275 m) before ultimately succumbing to tensional and compressive failure along a listric surface. However, proximal to calving fronts, bridging effects lead to variations in vertical normal stress from the background glaciostatic stress state that give rise to the along-flow gradients in vertical shear stress that are included within a full-Stokes momentum balance. When including all flowline stresses within the physics core, diagnostic solutions continue to support our earlier findings that slumping failure ultimately limits the upper bound for cliff heights. Shear failure still requires low cohesive strength, tensile failure leads to deeper dry-crevasse propagation (albeit, less than halfway through the cliff), and compressive failure drops the threshold height for triggering rapid ice-front retreat via slumping to 200 m (145-280 m).

  20. DNS, LES and RANS of turbulent heat transfer in boundary layer with suddenly changing wall thermal conditions

    International Nuclear Information System (INIS)

    Hattori, Hirofumi; Yamada, Shohei; Tanaka, Masahiro; Houra, Tomoya; Nagano, Yasutaka

    2013-01-01

    Highlights: • We study the turbulent boundary layer with heat transfer by DNS. • Turbulent boundary layers with suddenly changing wall thermal conditions are observed. • The detailed turbulent statistics and structures in turbulent thermal boundary layer are discussed. • Turbulence models in LES and RANS are evaluated using DNS results. • LES and RANS are almost in good agreement with DNS results. -- Abstract: The objectives of this study are to investigate a thermal field in a turbulent boundary layer with suddenly changing wall thermal conditions by means of direct numerical simulation (DNS), and to evaluate predictions of a turbulence model in such a thermal field, in which DNS of spatially developing boundary layers with heat transfer can be conducted using the generation of turbulent inflow data as a method. In this study, two types of wall thermal condition are investigated using DNS and predicted by large eddy simulation (LES) and Reynolds-averaged Navier–Stokes equation simulation (RANS). In the first case, the velocity boundary layer only develops in the entrance of simulation, and the flat plate is heated from the halfway point, i.e., the adiabatic wall condition is adopted in the entrance, and the entrance region of thermal field in turbulence is simulated. Then, the thermal boundary layer develops along a constant temperature wall followed by adiabatic wall. In the second case, velocity and thermal boundary layers simultaneously develop, and the wall thermal condition is changed from a constant temperature to an adiabatic wall in the downstream region. DNS results clearly show the statistics and structure of turbulent heat transfer in a constant temperature wall followed by an adiabatic wall. In the first case, the entrance region of thermal field in turbulence can be also observed. Thus, both the development and the entrance regions in thermal fields can be explored, and the effects upstream of the thermal field on the adiabatic region are

  1. Surface-enhanced Raman Spectroscopy of Ethephone Adsorbed on Silver Surface

    International Nuclear Information System (INIS)

    Lee, Chul Jae; Kim, Hee Jin; Karim, Mohammad Rezaul; Lee, Mu Sang

    2006-01-01

    We investigated the Surface-enhanced Raman Spectroscopy (SERS) spectrum of ethephone (2- chloroethylphosphonic acid). We observed significant signals in the ordinary Raman spectrum for solid-state ethephone as well as when it was adsorbed on a colloidal silver surface, strong vibrational signals were obtained at a very low concentration. The SERS spectra were obtained by silver colloids that were prepared by the γ - irradiation method. The influence of pH and the influence of anion (Cl - , Br - , I - ) on the adsorption orientation were investigated. Two different adsorption mechanisms were deduced, depending on the experimental conditions. The chlorine atom or the chlorine and two oxygen atoms were adsorbed on the colloidal silver surface. Among halide ions, Br - and I - were more strongly adsorbed on the colloidal silver surfaces. As a result, the adsorption of ethephone was less effective due to their steric hinderance

  2. Silver-Palladium Surfaces Inhibit Biofilm Formation

    DEFF Research Database (Denmark)

    Chiang, Wen-Chi; Schroll, Casper; Hilbert, Lisbeth Rischel

    2009-01-01

    Undesired biofilm formation is a major concern in many areas. In the present study, we investigated biofilm-inhibiting properties of a silver-palladium surface that kills bacteria by generating microelectric fields and electrochemical redox processes. For evaluation of the biofilm inhibition...... efficacy and study of the biofilm inhibition mechanism, the silver-sensitive Escherichia coli J53 and the silver-resistant E. coli J53[pMG101] strains were used as model organisms, and batch and flow chamber setups were used as model systems. In the case of the silver-sensitive strain, the silver......-palladium surfaces killed the bacteria and prevented biofilm formation under conditions of low or high bacterial load. In the case of the silver-resistant strain, the silver-palladium surfaces killed surface-associated bacteria and prevented biofilm formation under conditions of low bacterial load, whereas under...

  3. Investigation of optimal conditions for production of highly crystalline nanocellulose with increased yield via novel Cr(III)-catalyzed hydrolysis: Response surface methodology.

    Science.gov (United States)

    Chen, You Wei; Lee, Hwei Voon; Abd Hamid, Sharifah Bee

    2017-12-15

    For the first time, a highly efficient Cr(NO 3 ) 3 catalysis system was proposed for optimization the yield and crystallinity of nanocellulose end product. A five-level three-factor central composite design coupled with response surface methodology was employed to elucidate parameters interactions between three design factors, namely reaction temperature (x 1 ), reaction time (x 2 ) and concentration of Cr(NO 3 ) 3 (x 3 ) over a broad range of process conditions and determine the effect on crystallinity index and product yield. The developed models predicted the maximum nanocellulose yield of 87% at optimum process conditions of 70.6°C, 1.48h, and 0.48M Cr(NO 3 ) 3 . At these conditions, the obtained nanocellulose presented high crystallinity index (75.3%), spider-web-like interconnected network morphology with the average width of 31.2±14.3nm. In addition, the yielded nanocellulose rendered a higher thermal stability than that of original cellulosic source and expected to be widely used as reinforcement agent in bio-nanocomposites materials. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Surface-engineered substrates for improved human pluripotent stem cell culture under fully defined conditions.

    Science.gov (United States)

    Saha, Krishanu; Mei, Ying; Reisterer, Colin M; Pyzocha, Neena Kenton; Yang, Jing; Muffat, Julien; Davies, Martyn C; Alexander, Morgan R; Langer, Robert; Anderson, Daniel G; Jaenisch, Rudolf

    2011-11-15

    The current gold standard for the culture of human pluripotent stem cells requires the use of a feeder layer of cells. Here, we develop a spatially defined culture system based on UV/ozone radiation modification of typical cell culture plastics to define a favorable surface environment for human pluripotent stem cell culture. Chemical and geometrical optimization of the surfaces enables control of early cell aggregation from fully dissociated cells, as predicted from a numerical model of cell migration, and results in significant increases in cell growth of undifferentiated cells. These chemically defined xeno-free substrates generate more than three times the number of cells than feeder-containing substrates per surface area. Further, reprogramming and typical gene-targeting protocols can be readily performed on these engineered surfaces. These substrates provide an attractive cell culture platform for the production of clinically relevant factor-free reprogrammed cells from patient tissue samples and facilitate the definition of standardized scale-up friendly methods for disease modeling and cell therapeutic applications.

  5. Surfaces allowing for fractional statistics

    International Nuclear Information System (INIS)

    Aneziris, Charilaos.

    1992-07-01

    In this paper we give a necessary condition in order for a geometrical surface to allow for Abelian fractional statistics. In particular, we show that such statistics is possible only for two-dimentional oriented surfaces of genus zero, namely the sphere S 2 , the plane R 2 and the cylindrical surface R 1 *S 1 , and in general the connected sum of n planes R 2 -R 2 -R 2 -...-R 2 . (Author)

  6. Calculus of the fluence and the absorbed dose by the different head tissues before photons of distinct energies

    International Nuclear Information System (INIS)

    Azorin V, C.; Rivera M, T.; Vega C, H. R.; Azorin N, J.

    2009-10-01

    Two models were used, in the first one the head was built with the scalp that includes the skin and the adipose tissue, the skull, the brain and the tumor, it is modeled as a sphere of 1 cm of radius that be places in the center of the head pattern. The spherical models of the scalp, the skull and the brain were built respectively with spheres of 8.5, 8 and 7 cm of radius. The tumor was irradiated with an unidirectional beam of photons, the calculated cases were photons of 6 0Co and monoenergetic photons beams of 6, 8, 10 and 15 MeV. For each case be calculated the total photons fluence to 5, 10 and 15 cm in air and to 20.5 cm that is the interface between the air and head. This calculus included values of photons fluence halfway the scalp, halfway the skull, halfway the brain and in the tumor center. Also is calculated the total absorbed dose by the scalp, the skull, the brain and the tumor. (author)

  7. Flow Components in a NaK Test Loop Designed to Simulate Conditions in a Nuclear Surface Power Reactor

    Science.gov (United States)

    Polzin, Kurt A.; Godfroy, Thomas J.

    2008-01-01

    A test loop using NaK as the working fluid is presently in use to study material compatibility effects on various components that comprise a possible nuclear reactor design for use on the lunar surface. A DC electromagnetic (EM) pump has been designed and implemented as a means of actively controlling the NaK flow rate through the system and an EM flow sensor is employed to monitor the developed flow rate. These components allow for the matching of the flow rate conditions in test loops with those that would be found in a full-scale surface-power reactor. The design and operating characteristics of the EM pump and flow sensor are presented. In the EM pump, current is applied to a set of electrodes to produce a Lorentz body force in the fluid. A measurement of the induced voltage (back-EMF) in the flow sensor provides the means of monitoring flow rate. Both components are compact, employing high magnetic field strength neodymium magnets thermally coupled to a water-cooled housing. A vacuum gap limits the heat transferred from the high temperature NaK tube to the magnets and a magnetically-permeable material completes the magnetic circuit. The pump is designed to produce a pressure rise of 5 psi, and the flow sensor's predicted output is roughly 20 mV at the loop's nominal flow rate of 0.5 GPM.

  8. Investigation and Evaluation on Influence of Machining (CNC Conditions on Surface Quality of Paulownia Wood

    Directory of Open Access Journals (Sweden)

    Mohammad Aghajani

    2012-01-01

    Full Text Available The aim of this study was to investigate the effective factors on surface quality of paulownia wood during machining by advanced computer numerical controled (CNC machine. For this aim paulownia logs were provided and were converted to proper sizes (2.5 x 10 x 15 cm and then air dried. The Variable of this study were cutting speed (8.37 and 15.07 m/s, feeding rate (6 and 12 m/min, cutting depth (1and 5 mm, cutting method (down and up-milling and cutting pattern (tangential and radial. Roughness of cut specimens edge were evaluated by profilometer method according to ISO 13565 standard. For evaluation of surface quality, average roughness (Ra, maximum roughness (R max, valley roughness (Rv and peak roughness (Rp were used. Degrees of effectiveness of the parameters were evaluated by fractional factorial design as completely random design at confidence level of 95%. The result showed that cutting speed, cutting method and feed rate are influencive factors on surface quality of machined specimens and their effects were significant. With increasing cutting speed and decreasing feeding rate the roughness decreased and surface quality improved. In up-milling cutting method, degree of roughness was higher and consequently surface quality was inferior. It is to be noted that cutting method in comparison to other factors had the high influence on surface quality. The rest variables did now have independent influence on surface quality at 95% Confidence level. This study for achieving the optimum surface quality recommends that cutting speed of 15.07 m/s, feeding rate of 6 m/min, cutting method of down-milling and cutting depth of 1 mm for tangential cross section.

  9. Modification of AISI M2 high speed tool steels after laser surface melting under different operation conditions; Modificacion de los aceros rapidos de herramientas AISI M2 por fusion superficial con laser bajo diferentes condiciones de operacion

    Energy Technology Data Exchange (ETDEWEB)

    Arias, J.; Cabeza, M.; Castro, G.; Feijoo, I.; Merino, P.; Pena, G.

    2010-07-01

    We applied a laser surface melting treatment to AISIM2 high-speed steel hardened and tempered- and studied the resulting surface characteristics (microstructure) and mechanical behavior (hardness and wear performance). The steel was treated using a Nd:YAG continuous-wave laser with different operation conditions. The influence of the laser processing parameters on the single tracks and on melted surface layer obtained by multipass system with 50% overlap were studied. The microstructure for all conditions is formed by MC- and M{sub 2}C-type carbides, martensite and retained austenite; the quantities of this phase depends on the operations conditions. It has been determined that low levels of power density and high speed scanning of the beam leads to greater homogeneity in the microstructure with high hardness values and wear resistance. (Author) 26 refs.

  10. Selection of conformational states in surface self-assembly for a molecule with eight possible pairs of surface enantiomers

    DEFF Research Database (Denmark)

    Nuermaimaiti, Ajiguli; Schultz-Falk, Vickie; Lind Cramer, Jacob

    2016-01-01

    Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self-assembly of lamel......Self-assembly of a molecule with many distinct conformational states, resulting in eight possible pairs of surface enantiomers, is investigated on a Au(111) surface under UHV conditions. The complex molecule is equipped with alkyl and carboxyl moieties to promote controlled self......-assembly of lamellae structures. From statistical analysis of Scanning Tunnelling Microscopy (STM) data we observe a clear selection of specific conformational states after self-assembly. Using Density Functional Theory (DFT) calculations we rationalise how this selection is correlated to the orientation of the alkyl...

  11. Development of a reaction cell for in-situ/operando studies of surface of a catalyst under a reaction condition and during catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Luan; Tao, Franklin, E-mail: franklin.tao.2011@gmail.com [Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas 66045 (United States)

    2016-06-15

    Tracking surface chemistry of a catalyst during catalysis is significant for fundamental understanding of catalytic performance of the catalyst since it allows for establishing an intrinsic correlation between surface chemistry of a catalyst at its working status and its corresponding catalytic performance. Ambient pressure X-ray photoelectron spectroscopy can be used for in-situ studies of surfaces of different materials or devices in a gas. To simulate the gaseous environment of a catalyst in a fixed-bed a flowing gaseous environment of reactants around the catalyst is necessary. Here, we report the development of a new flowing reaction cell for simulating in-situ study of a catalyst surface under a reaction condition in gas of one reactant or during catalysis in a mixture of reactants of a catalytic reaction. The homemade reaction cell is installed in a high vacuum (HV) or ultrahigh vacuum (UHV) environment of a chamber. The flowing gas in the reaction cell is separated from the HV or UHV environment through well sealings at three interfaces between the reaction cell and X-ray window, sample door and aperture of front cone of an energy analyzer. Catalyst in the cell is heated through infrared laser beam introduced through a fiber optics interfaced with the reaction cell through a homemade feedthrough. The highly localized heating on the sample holder and Au-passivated internal surface of the reaction cell effectively minimizes any unwanted reactions potentially catalyzed by the reaction cell. The incorporated laser heating allows a fast heating and a high thermal stability of the sample at a high temperature. With this cell, a catalyst at 800 °C in a flowing gas can be tracked readily.

  12. Development of a reaction cell for in-situ/operando studies of surface of a catalyst under a reaction condition and during catalysis

    International Nuclear Information System (INIS)

    Nguyen, Luan; Tao, Franklin

    2016-01-01

    Tracking surface chemistry of a catalyst during catalysis is significant for fundamental understanding of catalytic performance of the catalyst since it allows for establishing an intrinsic correlation between surface chemistry of a catalyst at its working status and its corresponding catalytic performance. Ambient pressure X-ray photoelectron spectroscopy can be used for in-situ studies of surfaces of different materials or devices in a gas. To simulate the gaseous environment of a catalyst in a fixed-bed a flowing gaseous environment of reactants around the catalyst is necessary. Here, we report the development of a new flowing reaction cell for simulating in-situ study of a catalyst surface under a reaction condition in gas of one reactant or during catalysis in a mixture of reactants of a catalytic reaction. The homemade reaction cell is installed in a high vacuum (HV) or ultrahigh vacuum (UHV) environment of a chamber. The flowing gas in the reaction cell is separated from the HV or UHV environment through well sealings at three interfaces between the reaction cell and X-ray window, sample door and aperture of front cone of an energy analyzer. Catalyst in the cell is heated through infrared laser beam introduced through a fiber optics interfaced with the reaction cell through a homemade feedthrough. The highly localized heating on the sample holder and Au-passivated internal surface of the reaction cell effectively minimizes any unwanted reactions potentially catalyzed by the reaction cell. The incorporated laser heating allows a fast heating and a high thermal stability of the sample at a high temperature. With this cell, a catalyst at 800 °C in a flowing gas can be tracked readily.

  13. Evaporation from a sphagnum moss surface

    Science.gov (United States)

    D.S. Nichols; J.M. Brown

    1980-01-01

    Peat cores, 45 cm in diameter, were collected from a sphagnum bog in northern Minnesota, and used to measure the effects of different temperatures and water levels on evaporation from a sphagnum moss surface in a growth chamber. Under all conditions, evaporation from the moss surface was greater than that from a free-water surface. Evaporation from the moss increased...

  14. Hybrid surface design for robust superhydrophobicity.

    Science.gov (United States)

    Dash, Susmita; Alt, Marie T; Garimella, Suresh V

    2012-06-26

    Surfaces may be rendered superhydrophobic by engineering the surface morphology to control the extent of the liquid-air interface and by the use of low-surface-energy coatings. The droplet state on a superhydrophobic surface under static and dynamic conditions may be explained in terms of the relative magnitudes of the wetting and antiwetting pressures acting at the liquid-air interface on the substrate. In this paper, we discuss the design and fabrication of hollow hybrid superhydrophobic surfaces which incorporate both communicating and noncommunicating air gaps. The surface design is analytically shown to exhibit higher capillary (or nonwetting) pressure compared to solid pillars with only communicating air gaps. Six hybrid surfaces are fabricated with different surface parameters selected such that the Cassie state of a droplet is energetically favorable. The robustness of the surfaces is tested under dynamic impingement conditions, and droplet dynamics are explained using pressure-based transitions between Cassie and Wenzel states. During droplet impingement, the effective water hammer pressure acting due to the sudden change in the velocity of the droplet is determined experimentally and is found to be at least 2 orders of magnitude less than values reported in the literature. The experiments show that the water hammer pressure depends on the surface morphology and capillary pressure of the surface. We propose that the observed reduction in shock pressure may be attributed to the presence of air gaps in the substrate. This feature allows liquid deformation and hence avoids the sudden stoppage of the droplet motion as opposed to droplet behavior on smooth surfaces.

  15. Energy conditions and spacetime singularities

    International Nuclear Information System (INIS)

    Tipler, F.J.

    1978-01-01

    In this paper, a number of theorems are proven which collectively show that singularities will occur in spacetime under weaker energy conditions than the strong energy condition. In particular, the Penrose theorem, which uses only the weak energy condition but which applies only to open universes, is extended to all closed universes which have a Cauchy surface whose universal covering manifold is not a three-sphere. Furthermore, it is shown that the strong energy condition in the Hawking-Penrose theorem can be replaced by the weak energy condition and the assumption that the strong energy condition holds only on the average. In addition, it is demonstrated that if the Universe is closed, then the existence of singularities follows from the averaged strong energy condition alone. It is argued that any globally hyperbolic spacetime which satisfies the weak energy condition and which contains a black hole must be null geodesically incomplete

  16. Forces, surface finish and friction characteristics in surface engineered single- and multiple-point cutting edges

    International Nuclear Information System (INIS)

    Sarwar, M.; Gillibrand, D.; Bradbury, S.R.

    1991-01-01

    Advanced surface engineering technologies (physical and chemical vapour deposition) have been successfully applied to high speed steel and carbide cutting tools, and the potential benefits in terms of both performance and longer tool life, are now well established. Although major achievements have been reported by many manufacturers and users, there are a number of applications where surface engineering has been unsuccessful. Considerable attention has been given to the film characteristics and the variables associated with its properties; however, very little attention has been directed towards the benefits to the tool user. In order to apply surface engineering technology effectively to cutting tools, the coater needs to have accurate information relating to cutting conditions, i.e. cutting forces, stress and temperature etc. The present paper describes results obtained with single- and multiple-point cutting tools with examples of failures, which should help the surface coater to appreciate the significance of the cutting conditions, and in particular the magnitude of the forces and stresses present during cutting processes. These results will assist the development of a systems approach to cutting tool technology and surface engineering with a view to developing an improved product. (orig.)

  17. Generalized configurations of the reconstruction and hologram surface in digital holography

    International Nuclear Information System (INIS)

    Frere, C.

    1988-01-01

    Approximations are introduced for calculating the complex amplitude in holography, so that diffraction effects from curved lines and from the hologram surface are negligible. These effects are estimated. In the one-dimensional case, the calculation was made by the steady-phase method, with a weaker condition than the Fresnel condition. The one-dimensional transparency is exemplarily on straight, sinusoidal and elliptic lines while plane and cylindrical surfaces are chosen for the hologram surface. In the two-dimensional case, a numerical calculation is carried out using the fast Fourier transformation algorithm, and with a condition similar to the Fresnel condition. Compared with the transparency distribution, this method yields slightly disturbed reconstruction distributions. Inclined planes and cylindrical surfaces were chosen as hologram surfaces. The calculated complex amplitudes were encoded and materialized in a computer-supported hologram. (orig./DG) [de

  18. Statistical optimization of ultraviolet irradiate conditions for vitamin D₂ synthesis in oyster mushrooms (Pleurotus ostreatus using response surface methodology.

    Directory of Open Access Journals (Sweden)

    Wei-Jie Wu

    Full Text Available Response surface methodology (RSM was used to determine the optimum vitamin D2 synthesis conditions in oyster mushrooms (Pleurotus ostreatus. Ultraviolet B (UV-B was selected as the most efficient irradiation source for the preliminary experiment, in addition to the levels of three independent variables, which included ambient temperature (25-45°C, exposure time (40-120 min, and irradiation intensity (0.6-1.2 W/m2. The statistical analysis indicated that, for the range which was studied, irradiation intensity was the most critical factor that affected vitamin D2 synthesis in oyster mushrooms. Under optimal conditions (ambient temperature of 28.16°C, UV-B intensity of 1.14 W/m2, and exposure time of 94.28 min, the experimental vitamin D2 content of 239.67 µg/g (dry weight was in very good agreement with the predicted value of 245.49 µg/g, which verified the practicability of this strategy. Compared to fresh mushrooms, the lyophilized mushroom powder can synthesize remarkably higher level of vitamin D2 (498.10 µg/g within much shorter UV-B exposure time (10 min, and thus should receive attention from the food processing industry.

  19. Method of Maintaining the Required Values of Surface Roughness and Prediction of Technological Conditions for Cold Sheet Rolling

    Directory of Open Access Journals (Sweden)

    Valíček J.

    2014-06-01

    Full Text Available The paper is based on results obtained from topography of surfaces of sheets rolled from deep-drawing steel of the type KOHAL grade 697, non-alloy low-carbon structural steel EN 10263-2:2004 and aluminium. The presented results document correctness of the assumption that the rolling force Froll increases with the increasing reduction Δh and the quality of the rolled surface is improved at the simultaneous increasing of strength of rolled sheets and the decreasing of size of structural grains. The experiment was performed on the two-high rolling stand DUO 210 SVa, which enables only non-continuous technology in contrast to the rolling mill with continuous reduction on one sheet in several degrees on rolling trains, in consequence of which the obtained height parameters of the section are in close correlation with the predicted dependence. Contribution of the work consists in the creation of a mathematical model (algorithm for predicting technological parameters of the two-high rolling stand DUO 210 SVa at change of the absolute reduction Δh, for example for a deep-drawing steel of the type KOHAL grade 697 and non-alloy lowcarbon structural steel PN EN 10263-2:2004 and aluminium, and also in the development of a method of calculation applicable to any material being rolled in general, because the authors have found that various materials can be differentiated by a derived analytical criterion IKP. This criterion is a function of ratio between the modulus of elasticity of reference material and that of actually rolled material. The reference material is here deep-drawing steel of the type KOHAL grade 697. Verification was carried out by measuring changes of final surface roughness profile and final strength of rolled sheets of the stated materials in relation to reductions and those were compared with theoretically predicted values. It is possible to identify and predict on the basis of this algorithm an instant state of surface topography in

  20. Estimations of Atmospheric Conditions for Input to the Radar Performance Surface

    Science.gov (United States)

    2007-12-01

    distribution is unlimited 12b. DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) This study addresses the support of non- acoustic ASW operations by...BLANK v ABSTRACT This study addresses the support of non- acoustic ASW operations by timely atmospheric and ocean surface descriptions on features...24 Figure 12. Infrared Radiation Pyrometers , model KT15.82, Wintronics 2007