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Sample records for point wetting drop

  1. Wetting and evaporation of binary mixture drops.

    Science.gov (United States)

    Sefiane, Khellil; David, Samuel; Shanahan, Martin E R

    2008-09-11

    Experimental results on the wetting behavior of water, methanol, and binary mixture sessile drops on a smooth, polymer-coated substrate are reported. The wetting behavior of evaporating water/methanol drops was also studied in a water-saturated environment. Drop parameters (contact angle, shape, and volume) were monitored in time. The effects of the initial relative concentrations on subsequent evaporation and wetting dynamics were investigated. Physical mechanisms responsible for the various types of wetting behavior during different stages are proposed and discussed. Competition between evaporation and hydrodynamic flow are evoked. Using an environment saturated with water vapor allowed further exploration of the controlling mechanisms and underlying processes. Wetting stages attributed to differential evaporation of methanol were identified. Methanol, the more volatile component, evaporates predominantly in the initial stage. The data, however, suggest that a small proportion of methanol remained in the drop after the first stage of evaporation. This residual methanol within the drop seems to influence subsequent wetting behavior strongly.

  2. Drop splashing is independent of substrate wetting

    Science.gov (United States)

    Latka, Andrzej; Boelens, Arnout M. P.; Nagel, Sidney R.; de Pablo, Juan J.

    2018-02-01

    A liquid drop impacting a dry solid surface with sufficient kinetic energy will splash, breaking apart into numerous secondary droplets. This phenomenon shows many similarities to forced wetting, including the entrainment of air at the contact line. Because of these similarities and the fact that forced wetting has been shown to depend on the wetting properties of the surface, existing theories predict splashing to depend on wetting properties as well. However, using high-speed interference imaging, we observe that at high capillary numbers wetting properties have no effect on splashing for various liquid-surface combinations. Additionally, by fully resolving the Navier-Stokes equations at length and time scales inaccessible to experiments, we find that the shape and motion of the air-liquid interface at the contact line/edge of the droplet are independent of wettability. We use these findings to evaluate existing theories and to compare splashing with forced wetting.

  3. Non-wetting drops at liquid interfaces: from liquid marbles to Leidenfrost drops

    Science.gov (United States)

    Wong, Clint Y. H.; Adda-Bedia, Mokhtar; Vella, Dominic

    We consider the flotation of deformable, non-wetting drops on a liquid interface. We consider the deflection of both the liquid interface and the droplet itself in response to the buoyancy forces, density difference and the various surface tensions within the system. Our results suggest new insight into a range of phenomena in which such drops occur, including Leidenfrost droplets and floating liquid marbles. In particular, we show that the floating state of liquid marbles is very sensitive to the tension of the particle-covered interface and suggest that this sensitivity may make such experiments a useful assay of the properties of these complex interfaces.

  4. Evaporation dynamics of completely wetting drops on geometrically textured surfaces

    Science.gov (United States)

    Mekhitarian, Loucine; Sobac, Benjamin; Dehaeck, Sam; Haut, Benoît; Colinet, Pierre

    2017-10-01

    This study deals with the evaporation dynamics of completely wetting and highly volatile drops deposited on geometrically textured but chemically homogeneous surfaces. The texturation consists in a cylindrical pillars array with a square pitch. The triple line dynamics and the drop shape are characterized by an interferometric method. A parametric study is realized by varying the radius and the height of the pillars (at fixed interpillar distance), allowing to distinguish three types of dynamics: i) an evaporation-dominated regime with a receding triple line; ii) a spreading-dominated regime with an initially advancing triple line; iii) a cross-over region with strong pinning effects. The overall picture is in qualitative agreement with a mathematical model showing that the selected regime mostly depends on the value of a dimensionless parameter comparing the time scales for evaporation and spreading into the substrate texture.

  5. Drop spreading and penetration into pre-wetted powders

    KAUST Repository

    Marston, Jeremy

    2013-05-01

    We present results from an experimental study of the impact of liquid drops onto powder beds which are pre-wetted with the impacting liquid. Using high-speed video imaging, we study both the dynamics of the initial spreading regime and drainage times once the drop has reached its maximum spread on the surface. During the initial spreading stage, we compare our experimental data to a previously developed model which incorporates imbibition into the spreading dynamics and observe reasonable agreement. We find that the maximum spread is a strong function of the moisture content in the powder bed and that the total time from impact to complete drainage is always shorter than that for dry powder. Our results indicate that there is an optimum moisture content (or saturation) which leads to the fastest penetration. We use simple scaling arguments which also identify an optimum moisture content for fastest penetration, which agrees very well with the experimental result. © 2013 Elsevier B.V.

  6. Impact of ultra-viscous drops: air-film gliding and extreme wetting

    KAUST Repository

    Langley, Kenneth

    2017-01-23

    A drop impacting on a solid surface must push away the intervening gas layer before making contact. This entails a large lubricating air pressure which can deform the bottom of the drop, thus entrapping a bubble under its centre. For a millimetric water drop, the viscous-dominated flow in the thin air layer counteracts the inertia of the drop liquid. For highly viscous drops the viscous stresses within the liquid also affect the interplay between the drop and the gas. Here the drop also forms a central dimple, but its outer edge is surrounded by an extended thin air film, without contacting the solid. This is in sharp contrast with impacts of lower-viscosity drops where a kink in the drop surface forms at the edge of the central disc and makes a circular contact with the solid. Larger drop viscosities make the central air dimple thinner. The thin outer air film subsequently ruptures at numerous random locations around the periphery, when it reaches below 150 nm thickness. This thickness we measure using high-speed two-colour interferometry. The wetted circular contacts expand rapidly, at orders of magnitude larger velocities than would be predicted by a capillary-viscous balance. The spreading velocity of the wetting spots is independent of the liquid viscosity. This may suggest enhanced slip of the contact line, assisted by rarefied-gas effects, or van der Waals forces in what we call extreme wetting. Myriads of micro-bubbles are captured between the local wetting spots.

  7. Playing with water drops: from wetting to optics through electrostatics

    International Nuclear Information System (INIS)

    Domps, A; Roques-Carmes, T

    2011-01-01

    We present a consistent series of activities, including experiments and basic computational studies, investigating the shape and optical properties of water drops in connection with novel technological devices. Most of the work can be carried out with simple teaching equipment and is well suited to undergraduate students. Firstly, we show how the mass variations of a sessile drop can be used to control its curvature and hence to produce lenses with tunable focal distance. Alternatively, the shape of the drop can be varied using electrowetting on dielectric (EWOD). We propose a simple pedagogical approach to this phenomenon in connection with historical electrostatic apparatus. A detailed process for the preparation of an EWOD device is given, together with a focimetric method allowing the analysis of electrowetting effects in practical exercises. Finally, the manipulations of a commercialized variable focus lens illustrate that EWOD is at the heart of most recent technological developments, making practical work in optics more attractive than traditional exercises using conventional lenses.

  8. Playing with Water Drops: From Wetting to Optics through Electrostatics

    Science.gov (United States)

    Domps, A.; Roques-Carmes, T.

    2011-01-01

    We present a consistent series of activities, including experiments and basic computational studies, investigating the shape and optical properties of water drops in connection with novel technological devices. Most of the work can be carried out with simple teaching equipment and is well suited to undergraduate students. Firstly, we show how the…

  9. Capillarity and wetting phenomena drops, bubbles, pearls, waves

    CERN Document Server

    Gennes, Pierre-Gilles; Quéré, David

    2004-01-01

    As I glance out my window in the early morning, I can see beads of droplets gracing a spider web. The film of dew that has settled on the threads is unstable and breaks up spontaneously into droplets. This phenomenon has implications for the treatment of textile fibers (the process known as "oiling"), glass, and carbon. It is no less important when applying mascara! I take my morning shower. The moment I step out, I dry off by way of evaporation (which makes me feel cold) and by dewetting (the process by which dry areas form spontaneously and expand on my skin). As I rush into my car under a pelting rain, my attention is caught by small drops stuck on my windshield. I also notice larger drops rolling down and others larger still that, like snails, leave behind them a trail of water. I ask myself what the difference is between these rolling drops and grains of sand tumbling down an incline. I wonder why the smallest drops remain stuck. The answers to such questions do help car manufacturers treat the surface o...

  10. Numerical investigation of dynamic effects for sliding drops on wetting defects

    Science.gov (United States)

    Cavalli, Andrea; Musterd, Michiel; Mugele, Frieder

    2015-02-01

    The ability to trap or deflect sliding drops is of great interest in microfluidics, as it has several technological applications, ranging from self-cleaning and fog harvesting surfaces to laboratory-on-a-chip devices. We present a three-dimensional numerical model that describes sliding droplets interacting with wetting defects of variable strength and size. This approach provides relevant insight if compared to simplified analytic models, as it allows us to assess the relevance of the internal degrees of freedom of the droplet. We observe that the deformation of the drop enhances the effective strength and range of the defect, and we quantify this effect by comparison to a point-mass model. We also analyze the role of the steepness and strength of the defect on the drop motion, observing that small, strong defects are more effective at trapping than large, shallow traps of same excess surface energy. Finally, our results show quantitative agreement with previously reported electrowetting experiments, suggesting a universal behavior in droplet trapping that does not depend strongly on the nature of the defect.

  11. Substrate Wetting Under the Conditions of Drop Free Falling on a Heated Surface

    Directory of Open Access Journals (Sweden)

    Batischeva Ksenia A.

    2015-01-01

    Full Text Available We conducted an experimental study of a heated substrate wetting by drops of distilled water under the conditions of their free-falling. The studies were conducted using a shadow system, which consists of a light source, lens and high-speed video camera. It was found that the maximum wetted area of drop is directly proportional to its volume. The main ranges of evolution of distilled water drop behavior on the heated surface (change of geometry at contact with the surface have been conditionally divided.

  12. The fastest drop climbing on a wet conical fibre

    Science.gov (United States)

    Li, Er Qiang; Thoroddsen, Sigurdur T.

    2013-05-01

    We use high-speed video imaging to study the capillary-driven motion of a micro-droplet along the outside of a pre-wetted conical fiber. The cones are fabricated on a glass-puller with tip diameters as small as 1 μm, an order of magnitude smaller than in previous studies. The liquid is fed through the hollow fiber accumulating at the fiber tip to form droplets. The droplets are initially attached to the opening as they grow in size before detaching and traveling up the cone. This detachment can produce a transient oscillation of high frequency. The spatial variation of the capillary pressure drives the droplets towards the wider side of the cone. Various liquids were used to change the surface tension by a factor of 3.5 and viscosity by a factor of 1500. Within each droplet size and viscous-dissipation regime, the data for climbing speeds collapse on a single curve. Droplets traveling with and against gravity allow us to pinpoint the absolute strength of the driving capillary pressure and viscous stresses and thereby determine the prefactors in the dimensionless relationships. The motions are consistent with earlier results obtained from much larger cones. Translation velocities up to 270 mm/s were observed and overall the velocities follow capillary-viscous scaling, whereas the speed of the fastest droplets is limited by inertia following their emergence at the cone tip.

  13. The fastest drop climbing on a wet conical fibre

    KAUST Repository

    Li, Erqiang

    2013-05-21

    We use high-speed video imaging to study the capillary-driven motion of a micro-droplet along the outside of a pre-wetted conical fiber. The cones are fabricated on a glass-puller with tip diameters as small as 1 μm, an order of magnitude smaller than in previous studies. The liquid is fed through the hollow fiber accumulating at the fiber tip to form droplets. The droplets are initially attached to the opening as they grow in size before detaching and traveling up the cone. This detachment can produce a transient oscillation of high frequency. The spatial variation of the capillary pressure drives the droplets towards the wider side of the cone. Various liquids were used to change the surface tension by a factor of 3.5 and viscosity by a factor of 1500. Within each droplet size and viscous-dissipation regime, the data for climbing speeds collapse on a single curve. Droplets traveling with and against gravity allow us to pinpoint the absolute strength of the driving capillary pressure and viscous stresses and thereby determine the prefactors in the dimensionless relationships. The motions are consistent with earlier results obtained from much larger cones. Translation velocities up to 270 mm/s were observed and overall the velocities follow capillary-viscous scaling, whereas the speed of the fastest droplets is limited by inertia following their emergence at the cone tip.

  14. Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops.

    Science.gov (United States)

    Chen, Longquan; Bonaccurso, Elmar

    2014-08-01

    In this paper, we experimentally investigated the dynamic spreading of liquid drops on solid surfaces. Drop of glycerol water mixtures and pure water that have comparable surface tensions (62.3-72.8 mN/m) but different viscosities (1.0-60.1 cP) were used. The size of the drops was 0.5-1.2 mm. Solid surfaces with different lyophilic and lyophobic coatings (equilibrium contact angle θ(eq) of 0°-112°) were used to study the effect of surface wettability. We show that surface wettability and liquid viscosity influence wetting dynamics and affect either the coefficient or the exponent of the power law that describes the growth of the wetting radius. In the early inertial wetting regime, the coefficient of the wetting power law increases with surface wettability but decreases with liquid viscosity. In contrast, the exponent of the power law does only depend on surface wettability as also reported in literature. It was further found that surface wettability does not affect the duration of inertial wetting, whereas the viscosity of the liquid does. For low viscosity liquids, the duration of inertial wetting corresponds to the time of capillary wave propagation, which can be determined by Lamb's drop oscillation model for inviscid liquids. For relatively high viscosity liquids, the inertial wetting time increases with liquid viscosity, which may due to the viscous damping of the surface capillary waves. Furthermore, we observed a viscous wetting regime only on surfaces with an equilibrium contact angle θ(eq) smaller than a critical angle θ(c) depending on viscosity. A scaling analysis based on Navier-Stokes equations is presented at the end, and the predicted θ(c) matches with experimental observations without any additional fitting parameters.

  15. Four-point potential drop measurements for materials characterization

    Science.gov (United States)

    Bowler, Nicola

    2011-01-01

    The technique of measuring the voltage difference (potential drop) between two of the four electrodes of a four-point probe, in order to determine conductivity or surface resistivity of a test piece, is well established in the direct-current (dc) or quasi-dc regime. The technique finds wide usage in the semiconductor industry for the purpose of measuring surface resistivity of semiconductors, and also in the measurement of conductivity of metals, particularly of ferromagnetic metals for which conductivity cannot be easily measured using eddy-current nondestructive evaluation (NDE). In these applications, the conductivity of the test piece is deduced from an analytic formula that depends on the geometry of the probe and test piece. Such a formula requires, as an input, the measured value of the potential drop. Several analytical expressions exist for a variety of test-piece geometries and probe arrangements. Recently, it has been shown that broadband measurements of the potential drop, known as 'alternating current potential drop' (ac PD) measurements, can be used not only to obtain the conductivity of a test piece, but also its linear permeability μ. The beauty of this measurement is that the two parameters are completely decoupled in the quasi-static regime. In fact, μ does not appear in the quasi-static expression for σ. Hence, σ may be obtained from low-frequency ac PD measurements and then μ may be deduced as the frequency increases beyond the quasi-static regime, once σ is known. In this review, both dc and ac solutions that are useful in determining the conductivity of metals and semiconductors, and the permeability of ferromagnetic conductors, are summarized. In particular, flat test pieces with arbitrary thickness are considered. At the next level of complexity, a solution for a half-space coated with a surface layer is given, along with a discussion of the use of the four-point potential drop method for determining thickness of a surface layer, such

  16. Numerical investigation of dynamic effect for sliding drops on wetting defects

    NARCIS (Netherlands)

    Cavalli, Andrea; Musterd, M.; Mugele, Friedrich Gunther

    2015-01-01

    The ability to trap or deflect sliding drops is of great interest in microfluidics, as it has several technological applications, ranging from self-cleaning and fog harvesting surfaces to laboratory-on-a-chip devices. We present a three-dimensional numerical model that describes sliding droplets

  17. Numerical investigation of dynamic effects for sliding drops on wetting defects

    NARCIS (Netherlands)

    Cavalli, A.; Musterd, M.; Mugele, F.

    2015-01-01

    The ability to trap or deflect sliding drops is of great interest in microfluidics, as it has several technological applications, ranging from self-cleaning and fog harvesting surfaces to laboratory-on-a-chip devices. We present a three-dimensional numerical model that describes sliding droplets

  18. Point force singularities outside a drop covered with an incompressible surfactant: Image systems and their applications

    Science.gov (United States)

    Shaik, Vaseem A.; Ardekani, Arezoo M.

    2017-11-01

    In this work we derive the image flow fields for point force singularities placed outside a stationary drop covered with an insoluble, nondiffusing, and incompressible surfactant. We assume the interface to be Newtonian and use the Boussinesq-Scriven constitutive law for the interfacial stress tensor. We use this analytical solution to investigate two different problems. First, we derive the mobility matrix for two drops of arbitrary sizes covered with an incompressible surfactant. In the second example, we calculate the velocity of a swimming microorganism (modeled as a Stokes dipole) outside a drop covered with an incompressible surfactant.

  19. Modelling and investigation of partial wetting surfaces for drop dynamics using lattice Boltzmann method

    Science.gov (United States)

    Pravinraj, T.; Patrikar, Rajendra

    2017-07-01

    Partial wetting surfaces and its influence on the droplet movement of micro and nano scale being contemplated for many useful applications. The dynamics of the droplet usually analyzed with a multiphase lattice Boltzmann method (LBM). In this paper, the influence of partial wetting surface on the dynamics of droplet is systematically analyzed for various cases. Splitting of droplets due to chemical gradient of the surface is studied and analyses of splitting time for various widths of the strips for different Weber numbers are computed. With the proposed model one can tune the splitting volume and time by carefully choosing a strip width and droplet position. The droplet spreading on chemically heterogeneous surfaces shows that the spreading can be controlled not only by parameters of Weber number but also by tuning strip width ratio. The transportation of the droplet from hydrophobic surface to hydrophilic surface due to chemical gradient is simulated and analyzed using our hybrid thermodynamic-image processing technique. The results prove that with the progress of time the surface free energy decreases with increase in spreading area. Finally, the transportation of a droplet on microstructure gradient is demonstrated. The model explains the temporal behaviour of droplet during the spreading, recoiling and translation along with tracking of contact angle hysteresis phenomenon.

  20. Improved point-kinetics model for the BWR control rod drop accident

    International Nuclear Information System (INIS)

    Neogy, P.; Wakabayashi, T.; Carew, J.F.

    1985-01-01

    A simple prescription to account for spatial feedback weighting effects in RDA (rod drop accident) point-kinetics analyses has been derived and tested. The point-kinetics feedback model is linear in the core peaking factor, F/sub Q/, and in the core average void fraction and fuel temperature. Comparison with detailed spatial kinetics analyses indicates that the improved point-kinetics model provides an accurate description of the BWR RDA

  1. Numerical study of viscous dissipation during single drop impact on wetted surfaces

    Science.gov (United States)

    An, Yi; Yang, Shihao; Liu, Qingquan

    2017-11-01

    The splashing crown by the impact of a drop on a liquid film has been studied extensively since Yarin and Weiss (JFM 1995). The motion of the crown base is believed to be kinematic which results in the equation R =(2/3H)1/4(T-T0)1/2. This equation is believed to overestimate the crown size by about 15%. While Trojillo and Lee (PoF 2001) find the influence of the Re not notable. Considering the dissipation in the initial stage of the impact, Gao and Li (PRE, 2015) obtained a well-validated equation. However, how to estimate the dissipation is still worth some detailed discussion. We carried out a series of VOF simulations with special focusing on the influence of viscosity. The simulation is based on the Basilisk code to utilize adaptive mesh refinement. We found that the role of dissipation could be divided into three stages. When T> 1, the commonly used shallow water equation provides a good approximation while the initial condition should be considered properly. Between this two stages, the viscous dissipation is the governing factor and thus causes inaccurate estimation of the crown base motion in the third stage. This work was financially supported by the National Natural Science Foundation of China (No. 11672310, No. 11372326).

  2. VOF simulations of the contact angle dynamics during the drop spreading: standard models and a new wetting force model.

    Science.gov (United States)

    Malgarinos, Ilias; Nikolopoulos, Nikolaos; Marengo, Marco; Antonini, Carlo; Gavaises, Manolis

    2014-10-01

    In this study,a novel numerical implementation for the adhesion of liquid droplets impacting normally on solid dry surfaces is presented. The advantage of this new approach, compared to the majority of existing models, is that the dynamic contact angle forming during the surface wetting process is not inserted as a boundary condition, but is derived implicitly by the induced fluid flow characteristics (interface shape) and the adhesion physics of the gas-liquid-surface interface (triple line), starting only from the advancing and receding equilibrium contact angles. These angles are required in order to define the wetting properties of liquid phases when interacting with a solid surface. The physical model is implemented as a source term in the momentum equation of a Navier-Stokes CFD flow solver as an "adhesion-like" force which acts at the triple-phase contact line as a result of capillary interactions between the liquid drop and the solid substrate. The numerical simulations capture the liquid-air interface movement by considering the volume of fluid (VOF) method and utilizing an automatic local grid refinement technique in order to increase the accuracy of the predictions at the area of interest, and simultaneously minimize numerical diffusion of the interface. The proposed model is validated against previously reported experimental data of normal impingement of water droplets on dry surfaces at room temperature. A wide range of impact velocities, i.e. Weber numbers from as low as 0.2 up to 117, both for hydrophilic (θadv=10°-70°) and hydrophobic (θadv=105°-120°) surfaces, has been examined. Predictions include in addition to droplet spreading dynamics, the estimation of the dynamic contact angle; the latter is found in reasonable agreement against available experimental measurements. It is thus concluded that theimplementation of this model is an effective approach for overcoming the need of a pre-defined dynamic contact angle law, frequently adopted as

  3. Point-of-care technologies for molecular diagnostics using a drop of blood.

    Science.gov (United States)

    Song, Yujun; Huang, Yu-Yen; Liu, Xuewu; Zhang, Xiaojing; Ferrari, Mauro; Qin, Lidong

    2014-03-01

    Molecular diagnostics is crucial for prevention, identification, and treatment of disease. Traditional technologies for molecular diagnostics using blood are limited to laboratory use because they rely on sample purification and sophisticated instruments, are labor and time intensive, expensive, and require highly trained operators. This review discusses the frontiers of point-of-care (POC) diagnostic technologies using a drop of blood obtained from a finger prick. These technologies, including emerging biotechnologies, nanotechnologies, and microfluidics, hold the potential for rapid, accurate, and inexpensive disease diagnostics. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Thermodynamic Temperatures of High-Temperature Fixed Points: Uncertainties Due to Temperature Drop and Emissivity

    Science.gov (United States)

    Castro, P.; Machin, G.; Bloembergen, P.; Lowe, D.; Whittam, A.

    2014-07-01

    This study forms part of the European Metrology Research Programme project implementing the New Kelvin to assign thermodynamic temperatures to a selected set of high-temperature fixed points (HTFPs), Cu, Co-C, Pt-C, and Re-C. A realistic thermal model of these HTFPs, developed in finite volume software ANSYS FLUENT, was constructed to quantify the uncertainty associated with the temperature drop across the back wall of the cell. In addition, the widely applied software package, STEEP3 was used to investigate the influence of cell emissivity. The temperature drop, , relates to the temperature difference due to the net loss of heat from the aperture of the cavity between the back wall of the cavity, viewed by the thermometer, defining the radiance temperature, and the solid-liquid interface of the alloy, defining the transition temperature of the HTFP. The actual value of can be used either as a correction (with associated uncertainty) to thermodynamic temperature evaluations of HTFPs, or as an uncertainty contribution to the overall estimated uncertainty. In addition, the effect of a range of furnace temperature profiles on the temperature drop was calculated and found to be negligible for Cu, Co-C, and Pt-C and small only for Re-C. The effective isothermal emissivity is calculated over the wavelength range from 450 nm to 850 nm for different assumed values of surface emissivity. Even when furnace temperature profiles are taken into account, the estimated emissivities change only slightly from the effective isothermal emissivity of the bare cell. These emissivity calculations are used to estimate the uncertainty in the temperature assignment due to the uncertainty in the emissivity of the blackbody.

  5. Fog-harvesting inspired by the Stenocara beetle—An analysis of drop collection and removal from biomimetic samples with wetting contrast

    Science.gov (United States)

    White, Beatrice; Sarkar, Anjishnu; Kietzig, Anne-Marie

    2013-11-01

    This work examines the fog-harvesting ability of patterned and non-patterned samples in spray chamber experiments. The samples were prepared from different materials and the patterns under investigation were channels, hydrophobic patches and hydrophilic patches of contrasting wettability to mimic and optimize the alleged natural fog-harvesting ability of the Stenocara beetle. Fog-harvesting results based on the amount of collected water showed no significant differences among all samples, as the influence of “wind” was found to be the more dominant factor compared to the samples’ wetting characteristics. Video analysis of the experiments, however, revealed differences in the water collection and water removal mechanisms and were concluded to be more helpful than water collection results in the assessment of the various competing mechanisms in fog-harvesting experiments. The analysis with regard to surface wettability is based on drop rolling on the surface and roll-off into air, respectively. All patterned and most non-patterned samples exhibited drop motion by coalescence rather than rolling. Larger coalesced drops of non-spherical shape with irregular triple line shapes span the surface pattern on all our surfaces, which suggests that the underlying pattern of the surface has no dominant effect on the behavior of the droplets on these surfaces.

  6. Ground Validation Drop Camera Transect Points - St. Thomas/ St. John USVI - 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This shapefile denotes the location of underwater video that was collected by NOAA scientists using a SeaViewer drop camera system. Video were collected between...

  7. Slant Wet Delays from GNSS observations - Precise Point Positioning vs. Double Difference Approach

    Science.gov (United States)

    Moeller, Gregor; Weber, Robert

    2015-04-01

    The tropospheric parameter SWD (Slant Wet Delay) is the path delay caused by the highly variable amount of humidity in the atmosphere at altitudes below 12 km. It can be derived from Numerical Weather Predication data or even more precisely from dual- or multi-frequency observations of a regional GNSS reference network. In order to find the most adequate processing strategy dual GNSS observations of a small network of reference stations were simulated and tropospheric parameters were estimated in Precise Point Positioning (PPP) and in Double Difference (DD) mode. In DD mode the integer character of the phase ambiguities remains which allows to fix them to their true values and to obtain the tropospheric zenith delay as well as north and east (N/E) gradients with highest precision over very short time periods. In PPP mode orbit and clock errors are not cancelled out which affects the quality of the tropospheric estimates. On the other hand it has the advantage that the GNSS observations are processed undifferenced. Latter is important because the Zero Difference Residuals (ZDR) contain the azimuthal-anisotropic part of the tropospheric delay which is not covered by the estimated parameters. From Double Difference Residuals (DDR) the ZDR can be recovered too but only conditionally since common tropospheric effects have been cancelled out in advance by differencing. In this presentation we show how good the anisotropic slant path delays can be obtained from GNSS observations processed using both concepts - the PPP and the DD approach. Therefore tropospheric zenith delays and N/E gradients were estimated and Pseudo-ZDR were reconstructed from DDR and afterwards compared with ZDR derived from the PPP solution. In addition it is shown how good both concepts are applicable for observations at very low elevation angles and under extreme weather conditions. The IGS final and ultra-rapid service products were taken into account to define the best strategy not only for post

  8. Wet-bulb, dew point, and air temperature trends in Spain

    Science.gov (United States)

    Moratiel, R.; Soriano, B.; Centeno, A.; Spano, D.; Snyder, R. L.

    2017-10-01

    This study analyses trends of mean ( T m), maximum ( T x), minimum ( T n), dew point ( T d), and wet-bulb temperatures ( T w) on an annual, seasonal, and monthly time scale over Spain during the period 1981-2010. The main purpose was to determine how temperature and humidity changes are impacting on T w, which is probably a better measure of climate change than temperature alone. In this study, 43 weather stations were used to detect data trends using the nonparametric Mann-Kendall test and the Sen method to estimate the slope of trends. Significant linear trends observed for T m, T x, and T n versus year were 56, 58, and 47 % of the weather stations, respectively, with temperature ranges between 0.2 and 0.4 °C per decade. The months with bigger trends were April, May, June, and July with the highest trend for T x. The spatial behaviour of T d and T w was variable, with various locations showing trends from -0.6 to +0.3 °C per decade for T d and from -0.4 to +0.5 °C per decade for T w. Both T d and T w showed negative trends for July, August, September, November, and December. Comparing the trends versus time of each variable versus each of the other variables exhibited poor relationships, which means you cannot predict the trend of one variable from the trend of another variable. The trend of T x was not related to the trend of T n. The trends of T x, T m, and T n versus time were unrelated to the trends versus time of either T d or T w. The trend of T w showed a high coefficient of determination with the trend of T d with an annual value of R 2 = 0.86. Therefore, the T w trend is more related to changes in humidity than temperature.

  9. Shaping drops with textured surfaces

    Science.gov (United States)

    Ehlinger, Quentin; Biance, Anne-Laure; Ybert, Christophe

    2017-11-01

    When a drop impacts a substrate, it can behave differently depending on the nature of the surface and of the liquid (spreading, bouncing, resting, splashing ...). Understanding these behaviors is crucial to predict the drop morphology during and after impact. Whereas surface wettability has extensively been studied, the effect of surface roughness remains hardly explored. In this work, we consider the impact of a drop in a pure non-wetting situation by using superheated substrates i.e. in the Leidenfrost regime. The surface texture consists of a well-controlled microscopic defect shaped with photolithography on a smooth silicon wafer. Different regimes are observed, depending on the distance between the defect and the impact point and the defect size. Comparing the lamella thickness versus the defect height proves relevant as the transition criteria between regimes. Others characteristics of the drop behavior (direction of satellite droplet ejection, lamella rupture) are also well captured by inertial/capillary models. Drop impacts on multiple defects are also investigated and drop shape well predicted considering the interactions between the local flow and the defects.

  10. Comparison of wet and dry heat transfer and pressure drop tests of smooth and rough corrugated PVC packing in cooling towers

    International Nuclear Information System (INIS)

    Goshayeshi, H.R.; Missenden, J.F.

    1998-01-01

    This paper presents the results of an experimental investigation of the performance of a cooling tower with PVC packing. The following were examined; the effect of surface roughness, the effect of the angle of roughness and the effect of packing spacing. The investigation was divided into two parts: comparison of film heat transfer with air pressure drop, without water circulation and comparison of enthalpy change and pressure drop in the model cooling tower, with circulation of water. Seven commercial packing were investigated, covering a size range of 1.1< P/D<1.70 and 1≤p/e≤5 and a discussion of the dimensionless correlation resulting is given

  11. A critical analysis of one standard and five methods to monitor surface wetness and time-of-wetness

    Science.gov (United States)

    Camuffo, Dario; della Valle, Antonio; Becherini, Francesca

    2018-05-01

    Surface wetness is a synergistic factor to determine atmospheric corrosion, monument weathering, mould growth, sick buildings, etc. However, its detection and monitoring are neither easy nor homogeneous, for a number of factors that may affect readings. Various types of methods and sensors, either commercial or prototypes built in the lab, have been investigated and compared, i.e. the international standard ISO 9223 to evaluate corrosivity after wetness and time-of-wetness; indirect evaluation of wetness, based on the dew point calculated after the output of temperature and relative humidity sensors and direct measurements by means of capacitive wetness sensors, safety sensors, rain sensors (also known as leaf wetness sensors), infrared reflection sensors and fibre optic sensors. A comparison between the different methods is presented, specifying physical principles, forms of wetting to which they are respondent (i.e. condensation, ice melting, splashing drops, percolation and capillary rise), critical factors, use and cost.

  12. Modeling tropospheric wet delays with national GNSS reference network in China for BeiDou precise point positioning

    Science.gov (United States)

    Zheng, Fu; Lou, Yidong; Gu, Shengfeng; Gong, Xiaopeng; Shi, Chuang

    2017-10-01

    During past decades, precise point positioning (PPP) has been proven to be a well-known positioning technique for centimeter or decimeter level accuracy. However, it needs long convergence time to get high-accuracy positioning, which limits the prospects of PPP, especially in real-time applications. It is expected that the PPP convergence time can be reduced by introducing high-quality external information, such as ionospheric or tropospheric corrections. In this study, several methods for tropospheric wet delays modeling over wide areas are investigated. A new, improved model is developed, applicable in real-time applications in China. Based on the GPT2w model, a modified parameter of zenith wet delay exponential decay wrt. height is introduced in the modeling of the real-time tropospheric delay. The accuracy of this tropospheric model and GPT2w model in different seasons is evaluated with cross-validation, the root mean square of the zenith troposphere delay (ZTD) is 1.2 and 3.6 cm on average, respectively. On the other hand, this new model proves to be better than the tropospheric modeling based on water-vapor scale height; it can accurately express tropospheric delays up to 10 km altitude, which potentially has benefits in many real-time applications. With the high-accuracy ZTD model, the augmented PPP convergence performance for BeiDou navigation satellite system (BDS) and GPS is evaluated. It shows that the contribution of the high-quality ZTD model on PPP convergence performance has relation with the constellation geometry. As BDS constellation geometry is poorer than GPS, the improvement for BDS PPP is more significant than that for GPS PPP. Compared with standard real-time PPP, the convergence time is reduced by 2-7 and 20-50% for the augmented BDS PPP, while GPS PPP only improves about 6 and 18% (on average), in horizontal and vertical directions, respectively. When GPS and BDS are combined, the geometry is greatly improved, which is good enough to get a

  13. Bubble and drop interfaces

    CERN Document Server

    Miller

    2011-01-01

    The book aims at describing the most important experimental methods for characterizing liquid interfaces, such as drop profile analysis, bubble pressure and drop volume tensiometry, capillary pressure technique, and oscillating drops and bubbles. Besides the details of experimental set ups, also the underlying theoretical basis is presented in detail. In addition, a number of applications based on drops and bubbles is discussed, such as rising bubbles and the very complex process of flotation. Also wetting, characterized by the dynamics of advancing contact angles is discussed critically. Spec

  14. Energy-Saving Lipid Extraction from Wet Euglena gracilis by the Low-Boiling-Point Solvent Dimethyl Ether

    Directory of Open Access Journals (Sweden)

    Hideki Kanda

    2015-01-01

    Full Text Available We tested a wet extraction method for lipid extraction from Euglena gracilis water slurry at 0.51 MPa and 20 °C using liquefied dimethyl ether (DME. The yields, proximate analyses, elemental composition, and molecular weight distribution properties of the extracts from E. gracilis and the remaining residues obtained by DME extraction were compared with those of the extracts obtained by hexane Soxhlet extraction.

  15. The wetting transition in water

    Science.gov (United States)

    Friedman, Serah Ruth

    This work addresses both the design and experimental procedure for finding the wetting transition in water on a variety of solid surfaces. When a liquid drop is placed onto a solid surface it will either completely spread out or form a finite contact angle between 0 and 180 degrees. When a drop spreads, forming a film across the surface, this is called complete wetting. If a drop forms a finite contact angle with the surface, this is called partial wetting. A wetting transition is a surface phase transition from partial to complete wetting. This work is the first to experimentally measure the wetting transition in water on a solid surface. The temperature at which the wetting transition occurs is called the wetting temperature. The wetting temperature for solid-liquid-vapor systems can be theoretically predicted using both molecular dynamics simulations and density functional theory. Density functional theory predicts, with reasonable accuracy, the wetting temperature of "simple" non-polar liquids on a solid surface. The accuracy of density functional theory in predicting wetting temperature has yet to be experimentally tested on more complex polar liquids, and more specifically on water. In this work, we set out to measure the wetting transition in water on a variety of surfaces, namely: Graphite, Sapphire, Quartz, Mica, Gold, Silicon and Hexagonal Boron Nitride.

  16. Assessing the use of immersive virtual reality, mouse and touchscreen in pointing and dragging-and-dropping tasks among young, middle-aged and older adults.

    Science.gov (United States)

    Chen, Jiayin; Or, Calvin

    2017-11-01

    This study assessed the use of an immersive virtual reality (VR), a mouse and a touchscreen for one-directional pointing, multi-directional pointing, and dragging-and-dropping tasks involving targets of smaller and larger widths by young (n = 18; 18-30 years), middle-aged (n = 18; 40-55 years) and older adults (n = 18; 65-75 years). A three-way, mixed-factorial design was used for data collection. The dependent variables were the movement time required and the error rate. Our main findings were that the participants took more time and made more errors in using the VR input interface than in using the mouse or the touchscreen. This pattern applied in all three age groups in all tasks, except for multi-directional pointing with a larger target width among the older group. Overall, older adults took longer to complete the tasks and made more errors than young or middle-aged adults. Larger target widths yielded shorter movement times and lower error rates in pointing tasks, but larger targets yielded higher rates of error in dragging-and-dropping tasks. Our study indicated that any other virtual environments that are similar to those we tested may be more suitable for displaying scenes than for manipulating objects that are small and require fine control. Although interacting with VR is relatively difficult, especially for older adults, there is still potential for older adults to adapt to that interface. Furthermore, adjusting the width of objects according to the type of manipulation required might be an effective way to promote performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Wetting of real surfaces

    CERN Document Server

    Bormashenko, Edward Yu

    2013-01-01

    The problem of wetting and drop dynamics on various surfaces is very interesting from both the scientificas well as thepractical viewpoint, and subject of intense research.The results are scattered across papers in journals, sothis workwill meet the need for a unifying, comprehensive work.

  18. Wet-dog shake

    Science.gov (United States)

    Dickerson, Andrew; Mills, Zack; Hu, David

    2010-11-01

    The drying of wet fur is a critical to mammalian heat regulation. We investigate experimentally the ability of hirsute animals to rapidly oscillate their bodies to shed water droplets, nature's analogy to the spin cycle of a washing machine. High-speed videography and fur-particle tracking is employed to determine the angular position of the animal's shoulder skin as a function of time. We determine conditions for drop ejection by considering the balance of surface tension and centripetal forces on drops adhering to the animal. Particular attention is paid to rationalizing the relationship between animal size and oscillation frequency required to self-dry.

  19. An evaporation model of multicomponent solution drops

    Science.gov (United States)

    Sartori, Silvana; Liñán, Amable; Lasheras, Juan C.

    2010-11-01

    Solutions of polymers are widely used in the pharmaceutical industry as tablets coatings. These allow controlling the rate at which the drug is delivered, taste or appearance. The coating is performed by spraying and drying the tablets at moderate temperatures. The wetting of the coating solution on the pill's surface depends on the droplet Webber and Re numbers, angle of impact and on the rheological properties of the droplet. We present a model for the evaporation of multicomponent solutions droplets in a hot air environment with temperatures substantially lower than the boiling temperature of the solvent. As the liquid vaporizes from the surface the fluid in the drop increases in concentration, until reaching its saturation point. After saturation, precipitation occurs uniformly within the drop. As the surface regresses, a compacting front formed by the precipitate at its maximum packing density advances into the drop, while the solute continues precipitating uniformly. This porous shell grows fast due to the double effect of surface regression and precipitation. The evaporation rate is determined by the rates at which heat is transported to the droplet surface and at which liquid vapor diffuses away from it. When the drop is fully compacted, the evaporation is drastically reduced.

  20. Pressure Drop

    Science.gov (United States)

    Lawson, Mike

    2010-01-01

    Mike Lawson briefly discussed pressure drop for aerospace applications and presented short stories about adventures experienced while working at NASA and General Dynamics, including exposure to technologies like the Crew and Equipment Translation Aid (CETA) cart and the SWME.

  1. Foot Drop

    Science.gov (United States)

    ... is being done? The National Institute of Neurological Disorders and Stroke (NINDS) conducts research related to the neurological conditions that cause foot drop in its laboratories at the National ...

  2. NOAA Point Shapefile - Drop Camera transects, US Caribbean - Western Puerto Rico - Project NF-07-06-USVI-HAB - (2007), UTM 19N NAD83 (NCEI Accession 0131853)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This shapefile denotes the location of underwater photos and/or video that were collected by NOAA scientists using a drop camera system. Photos and/or video were...

  3. NOAA Point Shapefile - Drop Camera transects, US Caribbean - Western Puerto Rico - Project NF-07-06-USVI-HAB - (2007), UTM 19N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This shapefile denotes the location of underwater photos and/or video that were collected by NOAA scientists using a drop camera system. Photos and/or video were...

  4. NOAA Point Shapefile - Drop Camera transects, US Caribbean - Virgin Passage and St. John Shelf - Project NF-03-10-USVI-HAB - (2010), UTM 20N NAD83

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This shapefile denotes the location of underwater video that was collected by NOAA scientists using a SeaViewer drop camera system. For more information about this...

  5. Drop Tower Physics

    Science.gov (United States)

    Dittrich, William A. Toby

    2014-10-01

    The drop towers of yesteryear were used to make lead shot for muskets, as described in The Physics Teacher1 in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at the drop tower in Bremen, Germany. Using these drop towers, one can briefly investigate various physical systems operating in this near zero-g environment. The resulting "Drop Tower Physics" is a new and exciting way to challenge students with a physical example that requires solid knowledge of many basic physics principles, and it forces them to practice the scientific method. The question is, "How would a simple toy, like a pendulum, behave when it is suddenly exposed to a zero-g environment?" The student must then postulate a particular behavior, test the hypothesis against physical principles, and if the hypothesis conforms to these chosen physical laws, the student can formulate a final conclusion. At that point having access to a drop tower is very convenient, in that the student can then experimentally test his or her conclusion. The purpose of this discussion is to explain the response of these physical systems ("toys") when the transition is made to a zero-g environment and to provide video demonstrations of this behavior to support in-class discussions of Drop Tower Physics.

  6. Vibration-Induced Climbing of Drops

    Science.gov (United States)

    Brunet, P.; Eggers, J.; Deegan, R. D.

    2007-10-01

    We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wetted by the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up or down symmetry breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements. This phenomenon can be used to move a drop along an arbitrary path in a plane, without special surface treatments or localized forcing.

  7. Wetting behavior of mixtures of water and nonionic polyoxyethylene alcohol.

    Science.gov (United States)

    Wu, Chih-Kang; Chen, Li-Jen

    2005-07-19

    Five binary water + C4Ej mixtures, water + n-C4E0, water + 2-C4E0, water + iso-C4E0, water + n-C4E1, and water + iso-C4E1, were chosen to perform the surface/interfacial tension measurements over the experimental temperature range from 10 to 85 degrees C at the normal pressure by using a homemade pendent drop/bubble tensiometer. The symbol CiEj is the abbreviation of a nonionic polyoxyethylene alcohol CiH(2i+1)(OCH2CH2)jOH. The wetting behavior of the CiEj-rich phase at the interface separating gas and the aqueous phase is systematically examined according to the wetting coefficient resulting from the experimental data of surface/interfacial tensions measurements. For those systems with a lower critical solution temperature, for example, water + n-C6E2, water + n-C4E1, and water + iso-C4E1, a wetting transition from partial wetting to nonwetting is always observed when the system is brought to close to its lower critical solution temperature. On the other hand, to start with a partial wetting CiEj-rich phase, a wetting transition from partial wetting to complete wetting is always observed when the system is driven to approach its upper critical solution temperature. The effect of hydrophobicity of CiEj on the wetting behavior of the CiEj-rich phase at the interface separating gas and the aqueous phase was carefully investigated by using five sets of mixtures: (1) water + n-C4E0, water + n-C5E0, and water + n-C6E0; (2) water + 2-C4E0 and water + 2-C5E0; (3) water + 2-C4E0 and water + n-C4E0; (4) water + n-C4E1, water + n-C5E1, and water + n-C6E1; (5) water + n-C4E0 and water + n-C4E1. The CiEj-rich phase would tend to drive away from complete wetting (or nonwetting) to partial wetting with an increase in the hydrophobicity of CiEj in the binary water + CiEj system. All the wetting behavior observed in the water + CiEj mixtures is consistent with the prediction of the critical point wetting theory of Cahn.

  8. Pool impacts of Leidenfrost drop

    Science.gov (United States)

    Darbois Texier, Baptiste; Maquet, Laurent; Dorbolo, Stephane; Dehandschoewercker, Eline; Pan, Zhao; Truscott, Tadd

    2015-11-01

    This work concerns the impact of a droplet made of a volatile liquid (typically HFE) on a pool of an other liquid (typically silicone oil) which temperature is above the boiling point of the drop. Depending on the properties of the two liquids and the impacting conditions, four different regimes are observed. For low impacting speeds, the droplet bounces on the surface of the bath and finally levitates above it in a Leidenfrost state. Such a regime occurs as soon as the pool temperature exceeds the boiling point of the drop. This observation means that there is no threshold in temperature for a Leidenfrost effect on a liquid surface contrary to the case of a solid substrate. For intermediate impacting velocities, the pinch-off of the surface of the pool entraps the drop in the liquid bulk. The entrapped drop is separated from the pool by a layer of its own vapour in a similar way of antibulles. For increasing impacting speeds, the vapour layer between the drop and the pool does not hold during the pinch-off event. The contact of the drop with the hot liquid provokes a sudden and intense evaporation. At very large impacting speeds, the drop rapidely contacts the pool, spreads and finally induces a hemi-spherical cavity. In the end, these four different regimes are summarized in a Froud-Weber diagram which boundaries are discussed.

  9. Dilating Eye Drops

    Science.gov (United States)

    ... Frequently Asked Questions Español Condiciones Chinese Conditions Dilating Eye Drops En Español Read in Chinese What are dilating eye drops? Dilating eye drops contain medication to enlarge ( ...

  10. Feasibility and acceptability of point of care HIV testing in community outreach and GUM drop-in services in the North West of England: A programmatic evaluation

    Directory of Open Access Journals (Sweden)

    Jelliman Pauline

    2011-06-01

    Full Text Available Abstract Background In Liverpool, injecting drug users (IDUs, men-who-have-sex-with-men (MSM and UK Africans experience a disproportionate burden of HIV, yet services do not reach out to these groups and late presentations continue. We set out to: increase testing uptake in targeted marginalized groups through a community and genitourinary medicine (GUM-based point of care testing (POCT programme; and conduct a process evaluation to examine service provider inputs and document service user perceptions of the programme. Methods Mixed quantitative, qualitative and process evaluation methods were used. Service providers were trained to use fourth generation rapid antibody/antigen HIV tests. Existing outreach services incorporated POCT into routine practice. Clients completed a semi-structured questionnaire and focus group discussions (FGDs were held with service providers. Results Between September 2009 and June 2010, 953 individuals underwent POCT (GUM: 556 [59%]; community-based sites: 397 [42%]. Participants in the community were more likely to be male (p = 0.028, older (p Conclusions Community and GUM clinic-based POCT for HIV was feasible and acceptable to clients and service providers in a low prevalence setting. It successfully reached target groups, many of whom would not have otherwise tested. We recommend POCT be considered among strategies to increase the uptake of HIV testing among groups who are currently underserved.

  11. Coalescence of a Drop inside another Drop

    Science.gov (United States)

    Mugundhan, Vivek; Jian, Zhen; Yang, Fan; Li, Erqiang; Thoroddsen, Sigurdur

    2016-11-01

    Coalescence dynamics of a pendent drop sitting inside another drop, has been studied experimentally and in numerical simulations. Using an in-house fabricated composite micro-nozzle, a smaller salt-water drop is introduced inside a larger oil drop which is pendent in a tank containing the same liquid as the inner drop. On touching the surface of outer drop, the inner drop coalesces with the surrounding liquid forming a vortex ring, which grows in time to form a mushroom-like structure. The initial dynamics at the first bridge opening up is quantified using Particle Image Velocimetry (PIV), while matching the refractive index of the two liquids. The phenomenon is also numerically simulated using the open-source code Gerris. The problem is fully governed by two non-dimensional parameters: the Ohnesorge number and the diameter ratios of the two drops. The validated numerical model is used to better understand the dynamics of the phenomenon. In some cases a coalescence cascade is observed with liquid draining intermittently and the inner drop reducing in size.

  12. The wetting characteristics and surface tension of some Ni-based alloys on yttria, hafnia, alumina, and zirconia substrates

    Science.gov (United States)

    Kanetkar, C. S.; Kacar, A. S.; Stefanescu, D. M.

    1988-01-01

    The surface tension and wetting characteristics of four commercial Ni-based alloys (UD718, Waspaloy, UD720, and UD520), pure Ni, and three special alloys (Ni-20 percent Cr, Ni-20 percent Cr-1 percent Al, and Ni-20 percent Cr-4 percent Al) on various ceramic substrates (including alumina, zirconia, hafnia, and yttria) were investigated using sessile drop experiments. Most of the systems studied exhibited a nonwetting behavior. Wetting improved with holding time at a given temperature to the point that some systems, such as Ni-20Cr on alumina, Ni-20Cr-4Al on alumina and on yttria, became marginally wetting. Wetting characteristics were apparently related to constitutional undercooling, which in turn could be affected by the metal dissolving some of the substrate during measurements.

  13. West Point student drops out / Jorgen Johansson

    Index Scriptorium Estoniae

    Johansson, Jorgen

    2001-01-01

    Läti kohus mõistis välja kahjutasu Juris Matusevics'ilt, kes rikkus Läti kaitsejõududega sõlmitud kokkulepet, mis kohustas teda pärast USA West Pointi sõjaväeakadeemia lõpetamist teenima viis aastat Läti armees

  14. Leidenfrost drops on a heated liquid pool

    Science.gov (United States)

    Maquet, L.; Sobac, B.; Darbois-Texier, B.; Duchesne, A.; Brandenbourger, M.; Rednikov, A.; Colinet, P.; Dorbolo, S.

    2016-09-01

    We show that a volatile liquid drop placed at the surface of a nonvolatile liquid pool warmer than the boiling point of the drop can be held in a Leidenfrost state even for vanishingly small superheats. Such an observation points to the importance of the substrate roughness, negligible in the case considered here, in determining the threshold Leidenfrost temperature. A theoretical model based on the one proposed by Sobac et al. [Phys. Rev. E 90, 053011 (2014), 10.1103/PhysRevE.90.053011] is developed in order to rationalize the experimental data. The shapes of the drop and of the liquid substrate are analyzed. The model notably provides scalings for the vapor film thickness profile. For small drops, these scalings appear to be identical to the case of a Leidenfrost drop on a solid substrate. For large drops, in contrast, they are different, and no evidence of chimney formation has been observed either experimentally or theoretically in the range of drop sizes considered in this study. Concerning the evaporation dynamics, the radius is shown to decrease linearly with time whatever the drop size, which differs from the case of a Leidenfrost drop on a solid substrate. For high superheats, the characteristic lifetime of the drops versus the superheat follows a scaling law that is derived from the model, but, at low superheats, it deviates from this scaling by rather saturating.

  15. Spread of pathogens through rain drop impact

    Science.gov (United States)

    Kim, Seungho; Gruszewski, Hope; Gidley, Todd; Schmale, David G., III; Jung, Sunghwan

    2017-11-01

    Rain drop impact can disperse micron-sized pathogenic particles over long distances. In this study, we aim to elucidate mechanisms for disease dispersal when a rain drop impacts a particle-laden solid surface. Three different dispersal types were observed depending on whether the dispersed glass particles were dry or wet. For a dry particle dispersal, the movement of contact line made the particles initially jump off the surface with relatively high velocity. Then, air vortex was formed due to the air current entrained along with the falling drop, and advected the particles with relatively low velocity. For a wet particle dispersal, the contact line of a spreading liquid became unstable due to the presence of the particles on the substrate. This caused splashing at the contact line and ejected liquid droplets carrying the particles. Finally, we released a drop onto wheat plants infected with the rust fungus, Puccinia triticina, and found that nearly all of the satellite droplets from a single drop contained at least one rust spore. Also, we visualized such novel dispersal dynamics with a high-speed camera and characterized their features by scaling models. This research was partially supported by National Science Foundation Grant CBET-1604424.

  16. Thermocapillary reorientation of Janus drops

    Science.gov (United States)

    Rosales, Rodolfo; Saenz, Pedro

    2017-11-01

    Janus drops, named after the Ancient Roman two-faced god, are liquid drops formed from two immiscible fluids. Experimental observations indicate that a Janus drop may re-orientate in response to an applied external thermal gradient due to the Marangoni effect. Depending on the angle between the interior interface and the direction of the temperature gradient, disparities in the physical properties of the constituent liquids may lead to asymmetries in the thermocapillary flow. As a result, the drop will move along a curved path until a torque-free configuration is achieved, point after which it will continue on a straight trajectory. Here, we present the results of a theoretical investigation of this realignment phenomenon in the Stokes regime and in the limit of non-deformable interfaces. A 3D semi-analytical method in terms of polar spherical harmonics is developed to characterize and rationalize the hydrodynamic response (forces and torques), flow (velocity and temperature distribution) and trajectory of a Janus drop moving during the temperature-driven reorientation process. Furthermore, we discuss how this phenomenon may be exploited to develop dynamically reconfigurable micro-lenses. This work was partially supported by the US National Science Foundation through Grants DMS-1614043 and DMS-1719637.

  17. Drops on hydrophobic surfaces & vibrated fluid surfaces

    DEFF Research Database (Denmark)

    Wind-Willassen, Øistein

    of a droplet is then given, after which we set up a 2D computational Finite-Element Method (FEM) model for a neutrally buoyant drop immersed in another liquid. The model is validated by considering the volume loss over time. Subsequent to an introduction to the physics of wetting, the developed FEM model......-leap dynamics, exotic trajectories and the emergence of statistical behavior when the forcing is near the Faraday threshold....

  18. Probing the nanoscale: the first contact of an impacting drop

    KAUST Repository

    Li, Erqiang

    2015-11-16

    When a drop impacts onto a solid surface, the lubrication pressure in the air deforms its bottom into a dimple. This makes the initial contact with the substrate occur not at a point but along a ring, thereby entrapping a central disc of air. We use ultra-high-speed imaging, with 200 ns time resolution, to observe the structure of this first contact between the liquid and a smooth solid surface. For a water drop impacting onto regular glass we observe a ring of microbubbles, due to multiple initial contacts just before the formation of the fully wetted outer section. These contacts are spaced by a few microns and quickly grow in size until they meet, thereby leaving behind a ring of microbubbles marking the original air-disc diameter. On the other hand, no microbubbles are left behind when the drop impacts onto molecularly smooth mica sheets. We thereby conclude that the localized contacts are due to nanometric roughness of the glass surface, and the presence of the microbubbles can therefore distinguish between glass with 10 nm roughness and perfectly smooth glass. We contrast this entrapment topology with the initial contact of a drop impacting onto a film of extremely viscous immiscible liquid, where the initial contact appears to be continuous along the ring. Here, an azimuthal instability occurs during the rapid contraction at the triple line, also leaving behind microbubbles. For low impact velocities the nature of the initial contact changes to one initiated by ruptures of a thin lubricating air film.

  19. Scanning drop sensor

    Science.gov (United States)

    Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Shinde, Aniketa A.; Guevarra, Dan W.; Jones, Ryan J.; Marcin, Martin R.; Mitrovic, Slobodan

    2017-05-09

    Electrochemical or electrochemical and photochemical experiments are performed on a collection of samples by suspending a drop of electrolyte solution between an electrochemical experiment probe and one of the samples that serves as a test sample. During the electrochemical experiment, the electrolyte solution is added to the drop and an output solution is removed from the drop. The probe and collection of samples can be moved relative to one another so the probe can be scanned across the samples.

  20. Dynamics of wetting explored with inkjet printing

    Directory of Open Access Journals (Sweden)

    Völkel Simeon

    2017-01-01

    Full Text Available An inkjet printer head, which is capable of depositing liquid droplets with a resolution of 22 picoliters and high repeatability, is employed to investigate the wetting dynamics of drops printed on a horizontal plane as well as on a granular monolayer. For a sessile drop on a horizontal plane, we characterize the contact angle hysteresis, drop volume and contact line dynamics from side view images. We show that the evaporation rate scales with the dimension of the contact line instead of the surface area of the drop. We demonstrate that the system evolves into a closed cycle upon repeating the depositing-evaporating process, owing to the high repeatability of the printing facility. Finally, we extend the investigation to a granular monolayer in order to explore the interplay between liquid deposition and granular particles.

  1. NOAA Point Shapefile - Drop Camera transects, US Caribbean – Virgin Passage and St. John Shelf - Project NF-03-10-USVI-HAB - (2010), UTM 20N NAD83 (NCEI Accession 0131854)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This shapefile denotes the location of underwater video that was collected by NOAA scientists using a SeaViewer drop camera system. For more information about this...

  2. Wetting of silicone oil onto a cell-seeded substrate

    Science.gov (United States)

    Lu, Yongjie; Chan, Yau Kei; Chao, Youchuang; Shum, Ho Cheung

    2017-11-01

    Wetting behavior of solid substrates in three-phase systems containing two immiscible liquids are widely studied. There exist many three-phase systems in biological environments, such as droplet-based microfluidics or tamponade of silicone oil for eye surgery. However, few studies focus on wetting behavior of biological surfaces with cells. Here we investigate wetting of silicone oil onto cell-seeded PMMA sheet immersed in water. Using a simple parallel-plate cell, we show the effect of cell density, viscosity of silicone oil, morphology of silicone oil drops and interfacial tension on the wetting phenomenon. The dynamics of wetting is also observed by squeezing silicone oil drop using two parallel plates. Experimental results are explained based on disjoining pressure which is dependent on the interaction of biological surfaces and liquid used. These findings are useful for explaining emulsification of silicone oil in ophthalmological applications.

  3. Hemolymph drop impact outcomes on surfaces with varying wettability

    Science.gov (United States)

    Milionis, Athanasios; Ghokulla Krishnan, K.; Loth, Eric

    2015-08-01

    Insect fouling from coagulated hemolymph and exoskeleton parts is a major challenge in the aerospace industry for the next generation of aerodynamic surfaces, which will employ laminar flow that requires extremely smooth surfaces. However, the wetting physics and dynamics of hemolymph (insect blood) on surfaces are not well understood. The present study seeks to gain a fundamental insight on the effect of surface wetting characteristics and dynamics resulting from a hemolymph drop impact, the first such study. In particular, hemolymph drops extracted from Acheta domesticus were dispensed from a range of heights to vary the kinetic impact on surfaces, which had widely varying water wetting behavior (from superhydrophilic to superhydrophobic). The impact dynamics were investigated with high-speed imaging while the dried residues were studied with optical microscopy. It was found that a superhydrophobic surface (based on thermoplastic with silica nano-particles) was able to significantly reduce hemolymph drop spreading, and even provide complete rebound when impacting on inclined surfaces.

  4. Modeled Wet Nitrate Deposition

    Data.gov (United States)

    U.S. Environmental Protection Agency — Modeled data on nitrate wet deposition was obtained from Dr. Jeff Grimm at Penn State Univ. Nitrate wet depostion causes acidification and eutrophication of surface...

  5. Turbulence, bubbles and drops

    NARCIS (Netherlands)

    van der Veen, Roeland

    2016-01-01

    In this thesis, several questions related to drop impact and Taylor-Couette turbulence are answered. The deformation of a drop just before impact can cause a bubble to be entrapped. For many applications, such as inkjet printing, it is crucial to control the size of this entrapped bubble. To study

  6. Haptic perception of wetness

    NARCIS (Netherlands)

    Bergmann Tiest, W.M.; Kosters, N.D.; Daanen, H.A.M.; Kappers, A.M.L.

    2011-01-01

    The sensation of wetness is well-known but barely investigated. There are no specific wetness receptors in the skin, but the sensation is mediated by temperature and pressure perception. In our study, we have measured discrimination thresholds for the haptic perception of wetness of three di erent

  7. Drop dispensing in a viscous outer liquid

    Directory of Open Access Journals (Sweden)

    Claudiu PATRASCU

    2017-12-01

    Full Text Available The formation and detachment of Newtonian drops in viscous external liquids is investigated. A global analysis of two necking processes is presented in order to highlight the behavior of such thinning phenomena, when controlled either by inertia or by viscous effects. Moving detached droplets in an immiscible outer liquid were studied in terms of velocity and drop-travel distance. Theoretical predictions are proposed and compared with experimental data for the volume of the drop and for the subsequent dynamics that follow after detachment. Our investigations point out that the drop rapidly achieves constant velocity, the value of it being in a satisfactory agreement with the model. Both the influence of the flow rate and that of the material properties on drop volume are pursued.

  8. Drop impact on spherical soft surfaces

    Science.gov (United States)

    Chen, Simeng; Bertola, Volfango

    2017-08-01

    The impact of water drops on spherical soft surfaces is investigated experimentally through high-speed imaging. The effect of a convex compliant surface on the dynamics of impacting drops is relevant to various applications, such as 3D ink-jet printing, where drops of fresh material impact on partially cured soft substrates with arbitrary shape. Several quantities which characterize the morphology of impacting drops are measured through image-processing, including the maximum and minimum spreading angles, length of the wetted curve, and dynamic contact angle. In particular, the dynamic contact angle is measured using a novel digital image-processing scheme based on a goniometric mask, which does not require edge fitting. It is shown that the surface with a higher curvature enhances the retraction of the spreading drop; this effect may be due to the difference of energy dissipation induced by the curvature of the surface. In addition, the impact parameters (elastic modulus, diameter ratio, and Weber number) are observed to significantly affect the dynamic contact angle during impact. A quantitative estimation of the deformation energy shows that it is significantly smaller than viscous dissipation.

  9. PREFACE: Wetting: introductory note

    Science.gov (United States)

    Herminghaus, S.

    2005-03-01

    The discovery of wetting as a topic of physical science dates back two hundred years, to one of the many achievements of the eminent British scholar Thomas Young. He suggested a simple equation relating the contact angle between a liquid surface and a solid substrate to the interfacial tensions involved [1], γlg cos θ = γsg - γsl (1) In modern terms, γ denotes the excess free energy per unit area of the interface indicated by its indices, with l, g and s corresponding to the liquid, gas and solid, respectively [2]. After that, wetting seems to have been largely ignored by physicists for a long time. The discovery by Gabriel Lippmann that θ may be tuned over a wide range by electrochemical means [3], and some important papers about modifications of equation~(1) due to substrate inhomogeneities [4,5] are among the rare exceptions. This changed completely during the seventies, when condensed matter physics had become enthusiastic about critical phenomena, and was vividly inspired by the development of the renormalization group by Kenneth Wilson [6]. This had solved the long standing problem of how to treat fluctuations, and to understand the universal values of bulk critical exponents. By inspection of the critical exponents of the quantities involved in equation~(1), John W Cahn discovered what he called critical point wetting: for any liquid, there should be a well-defined transition to complete wetting (i.e., θ = 0) as the critical point of the liquid is approached along the coexistence curve [7]. His paper inspired an enormous amount of further work, and may be legitimately viewed as the entrance of wetting into the realm of modern physics. Most of the publications directly following Cahn's work were theoretical papers which elaborated on wetting in relation to critical phenomena. A vast amount of interesting, and in part quite unexpected, ramifications were discovered, such as the breakdown of universality in thin film systems [8]. Simultaneously, a number

  10. Drop shape analysis for determination of dynamic contact angles by double sided elliptical fitting method

    DEFF Research Database (Denmark)

    Andersen, Nis Korsgaard; Taboryski, Rafael J.

    2017-01-01

    Contact angle measurements are a fast and simple way to measure surface properties and is therefore widely used to measure surface energy and quantify wetting of a solid surface by a liquid substance. In common praxis contact angle measurements are done with sessile drops on a horizontal surface...... fitted to a drop profile derived from the Young-Laplace equation. When measuring the wetting behaviour by tilting experiments this is not possible since it involves moving drops that are not in equilibrium. Here we present a fitting technique capable of determining the contact angle of asymmetric drops...

  11. Understanding the edge effect in wetting: a thermodynamic approach.

    Science.gov (United States)

    Fang, Guoping; Amirfazli, A

    2012-06-26

    Edge effect is known to hinder spreading of a sessile drop. However, the underlying thermodynamic mechanisms responsible for the edge effect still is not well-understood. In this study, a free energy model has been developed to investigate the energetic state of drops on a single pillar (from upright frustum to inverted frustum geometries). An analysis of drop free energy levels before and after crossing the edge allows us to understand the thermodynamic origin of the edge effect. In particular, four wetting cases for a drop on a single pillar with different edge angles have been determined by understanding the characteristics of FE plots. A wetting map describing the four wetting cases is given in terms of edge angle and intrinsic contact angle. The results show that the free energy barrier observed near the edge plays an important role in determining the drop states, i.e., (1) stable or metastable drop states at the pillar's edge, and (2) drop collapse by liquid spilling over the edge completely or staying at an intermediate sidewall position of the pillar. This thermodynamic model presents an energetic framework to describe the functioning of the so-called "re-entrant" structures. Results show good consistency with the literature and expand the current understanding of Gibbs' inequality condition.

  12. Motion of Drops on Surfaces with Wettability Gradients

    Science.gov (United States)

    Subramanian, R. Shankar; McLaughlin, John B.; Moumen, Nadjoua; Qian, Dongying

    2002-11-01

    A liquid drop present on a solid surface can move because of a gradient in wettability along the surface, as manifested by a gradient in the contact angle. The contact angle at a given point on the contact line between a solid and a liquid in a gaseous medium is the angle between the tangent planes to the liquid and the solid surfaces at that point and is measured within the liquid side, by convention. The motion of the drop occurs in the direction of increasing wettability. The cause of the motion is the net force exerted on the drop by the solid surface because of the variation of the contact angle around the periphery. This force causes acceleration of an initially stationary drop, and leads to its motion in the direction of decreasing contact angle. The nature of the motion is determined by the balance between the motivating force and the resisting hydrodynamic force from the solid surface and the surrounding gaseous medium. A wettability gradient can be chemically induced as shown by Chaudhury and Whitesides who provided unambiguous experimental evidence that drops can move in such gradients. The phenomenon can be important in heat transfer applications in low gravity, such as when condensation occurs on a surface. Daniel et al have demonstrated that the velocity of a drop on a surface due to a wettability gradient in the presence of condensation can be more than two orders of magnitude larger than that observed in the absence of condensation. In the present research program, we have begun to study the motion of a drop in a wettability gradient systematically using a model system. Our initial efforts will be restricted to a system in which no condensation occurs. The experiments are performed as follows. First, a rectangular strip of approximate dimensions 10 x 20 mm is cut out of a silicon wafer. The strip is cleaned thoroughly and its surface is exposed to the vapor from an alkylchlorosilane for a period lasting between one and two minutes inside a

  13. Wet oxidation of quinoline

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Kilen, H.H.

    1998-01-01

    The influence of oxygen pressure (0.4 and 2 MPa). reaction time (30 and 60 min) and temperature (260 and 280 degrees C) on the wet oxidation of quinoline has been studied. The dominant parameters for the decomposition of quinoline were oxygen pressure and reaction temperature. whereas the reaction...... time was less important within the range studied. Nitrifying bacteria were used to measure the inhibition from wet oxidative-treated samples to study the effect of the (wet oxidation) reaction conditions. Wet oxidation made quinoline more toxic to Nitrosomonas. This was observed for Nitrobacter as well....... The combined wet oxidation and biological treatment of reaction products resulted in 91% oxidation of the parent compound to CO2 and water. Following combined wet oxidation and biological treatment the sample showed low toxicity towards Nitrosomonas and no toxicity towards Nitrobacter. (C) 1998 Elsevier...

  14. Device for making liquid drops

    International Nuclear Information System (INIS)

    Yamada, Masao; Fukuda, Fumito; Nishikawa, Masana; Ishii, Takeshi.

    1976-01-01

    Object: To provide a device for producing liquid drops in the form of liquefied gases indispensable to make deuterium and tritium ice pellets used as a fusion fuel in a tokamak type fusion reactor. Structure: First, pressure P 1 at the upper surface of liquefied gas in a container and outlet pressure P 2 of a nozzle disposed at the lower part of the container are adjusted into the state of P 1 >= P 2 , and it is preset so that even under such conditions, the liquefied gas from the nozzle is not naturally flown out. Next, a vibration plate disposed within the container is rapidly downwardly advanced toward the nozzle through a predetermined distance. As a result, pressure of the liquefied gas within a depression under the vibration plate rises instantaneously or in a pulse fashion to dissatisfy the aforesaid set condition whereby the liquefied gas may be flown out from the nozzle in the form of liquid drops. In accordance with the present device, it is possible to produce a suitable number of drops at a suitable point. (Yoshihara, H.)

  15. PREFACE: Dynamics of wetting Dynamics of wetting

    Science.gov (United States)

    Grest, Gary S.; Oshanin, Gleb; Webb, Edmund B., III

    2009-11-01

    Capillary phenomena associated with fluids wetting other condensed matter phases have drawn great scientific interest for hundreds of years; consider the recent bicentennial celebration of Thomas Young's paper on equilibrium contact angles, describing the geometric shape assumed near a three phase contact line in terms of the relevant surface energies of the constituent phases [1]. Indeed, nearly a century has passed since the seminal papers of Lucas and Washburn, describing dynamics of capillary imbibition [2, 3]. While it is generally appreciated that dynamics of fluid wetting processes are determined by the degree to which a system is out of capillary equilibrium, myriad complications exist that challenge the fundamental understanding of dynamic capillary phenomena. The topic has gathered much interest from recent Nobel laureate Pierre-Gilles de Gennes, who provided a seminal review of relevant dissipation mechanisms for fluid droplets spreading on solid surfaces [4] Although much about the dynamics of wetting has been revealed, much remains to be learned and intrinsic technological and fundamental interest in the topic drives continuing high levels of research activity. This is enabled partly by improved experimental capabilities for resolving wetting processes at increasingly finer temporal, spatial, and chemical resolution. Additionally, dynamic wetting research advances via higher fidelity computational modeling capabilities, which drive more highly refined theory development. The significance of this topic both fundamentally and technologically has resulted in a number of reviews of research activity in wetting dynamics. One recent example addresses the evaluation of existing wetting dynamics theories from an experimentalist's perspective [5]. A Current Opinion issue was recently dedicated to high temperature capillarity, including dynamics of high temperature spreading [6]. New educational tools have recently emerged for providing instruction in wetting

  16. Tunable transport of drops on a vibrating inclined fiber

    Science.gov (United States)

    Bick, Alison; Boulogne, François; Sauret, Alban; Stone, Howard A.

    2015-11-01

    Transport of liquid drops in fibrous media occurs in various engineering systems such as fog harvesting or cleaning of textiles. The ability to tune or to control liquid movement can increase the system efficiency and enable new engineering applications. In this letter, we experimentally investigate how partially wetting drops on a single fiber can be manipulated by vibrating the fiber. We show that a sliding motion along the fiber or a dripping of the drop can be triggered by standing waves. We identify the conditions on the drop volume, the fiber tilt angle, and the amplitude and frequency of oscillations to observe these different behaviors. Finally, we experimentally illustrate that vibrations can be used to control the transport and the collection of water drops along a fiber using a combination of the sliding and dripping transitions.

  17. Control of Drop Motion by Mechanical Vibrations

    Science.gov (United States)

    Bestehorn, Michael

    2014-11-01

    Since the first experimental observations of Michael Faraday in 1831 it is known that a vibrating liquid may show an instability of its flat free surface with respect to oscillating regular surface patterns. We study thin liquid films on a horizontal substrate in the long wave approximation. The films are parametrically excited by mechanical horizontal or inclined oscillations. Inertia effects are taken into account and the standard thin film formulation is extended by a second equation for the vertically averaged mass flux. The films can be additionally unstable by Van der Waals forces on a partially wetting substrate, leading to the formation of drops. These drops can be manipulated by the vibrations to move in a desired direction. Linear results based on a damped complex valued Mathieu equation as well as fully nonlinear results using a reduced model will be presented, for more details see.

  18. Impact of granular drops

    KAUST Repository

    Marston, J. O.

    2013-07-15

    We investigate the spreading and splashing of granular drops during impact with a solid target. The granular drops are formed from roughly spherical balls of sand mixed with water, which is used as a binder to hold the ball together during free-fall. We measure the instantaneous spread diameter for different impact speeds and find that the normalized spread diameter d/D grows as (tV/D)1/2. The speeds of the grains ejected during the “splash” are measured and they rarely exceed twice that of the impact speed.

  19. Large drops cause complete coalescence

    Indian Academy of Sciences (India)

    The thin film below the drop drains out slowly with time, finally creating a hole in the drop when it comes in contact with the interface at t=0.37 Tc, a small matrix drop, also called satellite drop, is seen to be trapped during the film rupture. Such an entrapment was observed by Thoroddsen et al (2008) and Chen et al (2006).

  20. Two secondary drops

    Indian Academy of Sciences (India)

    Figure shows formation of two secondary drops of unequal size and their merger. The process is same as the earlier process until t= 0.039 Tc with necking occurring at two places, one at the bottom of the column and the other at the middle. The necking at the middle of the liquid column is due to Raleigh instability.

  1. Two secondary drops

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Notes: Figure shows formation of two secondary drops of unequal size and their merger. The process is same as the earlier process until t= 0.039 Tc with necking occurring at two places, one at the bottom of the column and the other at the middle. The necking at the ...

  2. Lambda-dropping

    DEFF Research Database (Denmark)

    Danvy, Olivier; Schultz, Ulrik Pagh

    1997-01-01

    the parameters that any of their callees might possibly need. Both lambda-lifting and lambda-dropping thus require one to compute a transitive closure over the call graph:• for lambda-lifting: to establish the Def/Use path of each free variable (these free variables are then added as parameters to each......Lambda-lifting a functional program transforms it into a set of recursive equations. We present the symmetric transformation: lambda-dropping. Lambda-dropping a set of recursive equations restores block structure and lexical scope.For lack of scope, recursive equations must carry around all...... of the functions in the call path);• for lambda-dropping: to establish the Def/Use path of each parameter (parameters whose use occurs in the same scope as their definition do not need to be passed along in the call path).Without free variables, a program is scope-insensitive. Its blocks are then free...

  3. Determination of the solid surface critical exponent β1 from contact-angle variation on approach to a wetting transition: Cyclohexane/aniline/quartz

    Science.gov (United States)

    Pallas, Norman R.

    2016-03-01

    The three-phase contact angle (θ) for the system cyclohexane/aniline/quartz has been measured from drop shapes as a function of temperature on approach to the cyclohexane/aniline upper consolute solution temperature Tc. The experiments employed exacting criteria previously established for thermodynamic-quality measurements at fluid interfaces. A first-order wetting transition from partial wetting to complete wetting was observed at a temperature Tw, 2.12 K below Tc. The contact angle vanishes at Tw, scaling as cos θ ˜ |T - Tc|β1-μ for T contact angle near the critical point for this system. These results are in marked contrast to previous measurements on this system from measurements of capillary rise and meniscus curvature.

  4. Evaluatie Wet openbare manifestaties

    NARCIS (Netherlands)

    Roorda, Berend; Brouwer, Jan; Schilder, A.E.

    2015-01-01

    Het rapport betreft een uitgebreide evaluatie van de Wet openbare manifestaties (Wom) in opdracht van het Ministerie van Binnenlandse Zaken en Koninkrijksrelaties. Op grond van onderzoek naar de parlementaire geschiedenis van de Wom, de literatuur, de jurisprudentie, gesprekken met beleidsadviseurs

  5. Enuresis (Bed-Wetting)

    Science.gov (United States)

    ... Symptoms of enuresis Enuresis is when an older child (age 7 or older) wets the bed at night ... feel guilt and embarrassment. It’s true that your child should take responsibility for bedwetting. He or she could do this ...

  6. Wetting Behavior and Reactivity of Molten Silicon with h-BN Substrate at Ultrahigh Temperatures up to 1750 °C

    Science.gov (United States)

    Polkowski, Wojciech; Sobczak, Natalia; Nowak, Rafał; Kudyba, Artur; Bruzda, Grzegorz; Polkowska, Adelajda; Homa, Marta; Turalska, Patrycja; Tangstad, Merete; Safarian, Jafar; Moosavi-Khoonsari, Elmira; Datas, Alejandro

    2017-12-01

    For a successful implementation of newly proposed silicon-based latent heat thermal energy storage systems, proper ceramic materials that could withstand a contact heating with molten silicon at temperatures much higher than its melting point need to be developed. In this regard, a non-wetting behavior and low reactivity are the main criteria determining the applicability of ceramic as a potential crucible material for long-term ultrahigh temperature contact with molten silicon. In this work, the wetting of hexagonal boron nitride (h-BN) by molten silicon was examined for the first time at temperatures up to 1750 °C. For this purpose, the sessile drop technique combined with contact heating procedure under static argon was used. The reactivity in Si/h-BN system under proposed conditions was evaluated by SEM/EDS examinations of the solidified couple. It was demonstrated that increase in temperature improves wetting, and consequently, non-wetting-to-wetting transition takes place at around 1650 °C. The contact angle of 90° ± 5° is maintained at temperatures up to 1750 °C. The results of structural characterization supported by a thermodynamic modeling indicate that the wetting behavior of the Si/h-BN couple during heating to and cooling from ultrahigh temperature of 1750 °C is mainly controlled by the substrate dissolution/reprecipitation mechanism.

  7. High-Speed Interferometry Under Impacting Drops

    KAUST Repository

    Langley, Kenneth R.

    2017-08-31

    Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

  8. Wetting and surface tension of bismate glass melt

    International Nuclear Information System (INIS)

    Shim, Seung-Bo; Kim, Dong-Sun; Hwang, Seongjin; Kim, Hyungsun

    2009-01-01

    Lead oxide glass frits are used widely in the electronics industry for low-temperature firing. On the other hand, one of the low-sintering and low-melting lead-free glass systems available, the bismate glass system, is considered to be an alternative to lead oxide glass. In order to extend the applications of Bi 2 O 3 glasses, this study examined the thermophysical properties of low-melting Bi 2 O 3 -B 2 O 3 -ZnO-BaO-Al 2 O 3 -SiO 2 glass frits with various ZnO/B 2 O 3 ratios. The fundamental thermal properties, such as glass transition temperature and softening point, were examined by differential thermal analysis and a glass softening point determination system. The wetting angles, viscosities and surface tension of the various bismate glasses on an alumina substrate were measured using hot-stage microscopy and the sessile drop method. These thermophysical properties will be helpful in understanding the work of adhesion and the liquid spread kinetics of glass frits.

  9. AC Electrowetting of Polymer Aqueous Drops on Parallel Electrodes

    Science.gov (United States)

    Zhang, Lu; Chetwani, Nishant; Chang, Hsueh-Chia; Zhu, Yingxi Elaine

    2009-03-01

    We have recently observed the strong field dependence of AC-electrowetting of simple electrolyte aqueous drops on parallel gold electrodes, yet the detailed dynamic process of AC-field induced surface wetting remains unclear. In this work, we use fluorescence labeled DNA aqueous solution as a model system to directly visualize the wetting process of aqueous drops under varied AC electric fields by using combined fluorescence microscopy and contact angle goniometer. The electrowetting behavior of DNA aqueous drops is observed at AC-field frequency greater than the reciprocal of the RC time scale for electrode screening. And the onset of AC electrowetting is accompanied by the observed oscillation in drop contour shape and contact line. In addition, the ejection of nanodrops from the parent aqueous drop is observed when the threshold AC-field amplitude is exceeded. A scaling theory based on electrode interfacial screening is developed to quantify the AC-electrowetting behavior with the dependence of AC-field frequency, strength and medium conductivity.

  10. Wet storage integrity update

    International Nuclear Information System (INIS)

    Bailey, W.J.; Johnson, A.B. Jr.

    1983-09-01

    This report includes information from various studies performed under the Wet Storage Task of the Spent Fuel Integrity Project of the Commercial Spent Fuel Management (CSFM) Program at Pacific Northwest Laboratory. An overview of recent developments in the technology of wet storage of spent water reactor fuel is presented. Licensee Event Reports pertaining to spent fuel pools and the associated performance of spent fuel and storage components during wet storage are discussed. The current status of fuel that was examined under the CSFM Program is described. Assessments of the effect of boric acid in spent fuel pool water on the corrosion and stress corrosion cracking of stainless steel and the stress corrosion cracking of stainless steel piping containing stagnant water at spent fuel pools are discussed. A list of pertinent publications is included. 84 references, 21 figures, 11 tables

  11. Drops and bubbles in contact with solid surfaces

    CERN Document Server

    Ferrari, Michele

    2012-01-01

    The third volume in a series dedicated to colloids and interfaces, Drops and Bubbles in Contact with Solid Surfaces presents an up-to-date overview of the fundamentals and applications of drops and bubbles and their interaction with solid surfaces. The chapters cover the theoretical and experimental aspects of wetting and wettability, liquid-solid interfacial properties, and spreading dynamics on different surfaces, including a special section on polymers. The book examines issues related to interpretation of contact angle from nano to macro systems. Expert contributors discuss interesting pec

  12. Evaporation of pure liquid sessile and spherical suspended drops: a review.

    Science.gov (United States)

    Erbil, H Yildirim

    2012-01-15

    A sessile drop is an isolated drop which has been deposited on a solid substrate where the wetted area is limited by a contact line and characterized by contact angle, contact radius and drop height. Diffusion-controlled evaporation of a sessile drop in an ambient gas is an important topic of interest because it plays a crucial role in many scientific applications such as controlling the deposition of particles on solid surfaces, in ink-jet printing, spraying of pesticides, micro/nano material fabrication, thin film coatings, biochemical assays, drop wise cooling, deposition of DNA/RNA micro-arrays, and manufacture of novel optical and electronic materials in the last decades. This paper presents a review of the published articles for a period of approximately 120 years related to the evaporation of both sessile drops and nearly spherical droplets suspended from thin fibers. After presenting a brief history of the subject, we discuss the basic theory comprising evaporation of micrometer and millimeter sized spherical drops, self cooling on the drop surface and evaporation rate of sessile drops on solids. The effects of drop cooling, resultant lateral evaporative flux and Marangoni flows on evaporation rate are also discussed. This review also has some special topics such as drop evaporation on superhydrophobic surfaces, determination of the receding contact angle from drop evaporation, substrate thermal conductivity effect on drop evaporation and the rate evaporation of water in liquid marbles. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Drop shape analysis for determination of dynamic contact angles by double sided elliptical fitting method

    International Nuclear Information System (INIS)

    Andersen, Nis Korsgaard; Taboryski, Rafael

    2017-01-01

    Contact angle measurements are a fast and simple way to measure surface properties and is therefore widely used to measure surface energy and quantify wetting of a solid surface by a liquid substance. In common praxis contact angle measurements are done with sessile drops on a horizontal surface fitted to a drop profile derived from the Young-Laplace equation. When measuring the wetting behaviour by tilting experiments this is not possible since it involves moving drops that are not in equilibrium. Here we present a fitting technique capable of determining the contact angle of asymmetric drops with very high accuracy even with blurry or noisy images. We do this by splitting the trace of a drop into a left and right part at the apex and then fit each side to an ellipse. (technical note)

  14. Anomalous water drop bouncing on a nanotextured surface by the Leidenfrost levitation

    Science.gov (United States)

    Lee, Doo Jin; Song, Young Seok

    2016-05-01

    We report an anomalous liquid drop bouncing phenomenon that is generated by the Leidenfrost levitation due to a vapor layer reducing energy dissipation during the collision. The Leidenfrost levitation of water drops on both a hydrophobic surface and nanotextured Cassie surface is investigated. When the water drop is positioned onto the hydrophobic surface, a superhydrophobic feature is observed by the levitation effect due to the vapor film, which results in a slow evaporation of the drop due to the low thermal conductivity of the vapor layer that inhibits heat transfer between the heated surface and the water drop. In contrast, for the nanotextured surface, the water drop can bounce off after impact on the surface when it overcomes gravitational and adhesion forces. The spontaneous water drop bouncing on the nanotextured surface is powered by the combination effect of the Leidenfrost levitation and the non-wetting Cassie state.

  15. WetVegEurope

    NARCIS (Netherlands)

    Landucci, Flavia; Řezníčková, Marcela; Šumberová, Kateřina; Hennekens, S.M.; Schaminée, J.H.J.

    2015-01-01

    WetVegEurope is a research project (http://www.sci.muni.cz/botany/vegsci/wetveg) whose goal is to provide a synthesized formalized classification of the aquatic and marsh vegetation across Europe at the level of phytosociological associations. In order to achieve the project objective, a

  16. First drop dissimilarity in drop-on-demand inkjet devices

    International Nuclear Information System (INIS)

    Famili, Amin; Palkar, Saurabh A.; Baldy, William J. Jr.

    2011-01-01

    As inkjet printing technology is increasingly applied in a broader array of applications, careful characterization of its method of use is critical due to its inherent sensitivity. A common operational mode in inkjet technology known as drop-on-demand ejection is used as a way to deliver a controlled quantity of material to a precise location on a target. This method of operation allows ejection of individual or a sequence (burst) of drops based on a timed trigger event. This work presents an examination of sequences of drops as they are ejected, indicating a number of phenomena that must be considered when designing a drop-on-demand inkjet system. These phenomena appear to be driven by differences between the first ejected drop in a burst and those that follow it and result in a break-down of the linear relationship expected between driving amplitude and drop mass. This first drop, as quantified by high-speed videography and subsequent image analysis, can be different in morphology, trajectory, velocity, and volume from subsequent drops within a burst. These findings were confirmed orthogonally by both volume and mass measurement techniques which allowed quantitation down to single drops.

  17. Drop Impact on a Solid Surface

    KAUST Repository

    Josserand, C.

    2015-09-22

    © Copyright 2016 by Annual Reviews. All rights reserved. A drop hitting a solid surface can deposit, bounce, or splash. Splashing arises from the breakup of a fine liquid sheet that is ejected radially along the substrate. Bouncing and deposition depend crucially on the wetting properties of the substrate. In this review, we focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of not only liquid inertia, viscosity, and surface tension, but also the surrounding gas. The gas cushions the initial contact; it is entrapped in a central microbubble on the substrate; and it promotes the so-called corona splash, by lifting the lamella away from the solid. Particular attention is paid to the influence of surface roughness, natural or engineered to enhance repellency, relevant in many applications.

  18. Lubrication model for evaporation of binary sessile drops

    Science.gov (United States)

    Williams, Adam; Sáenz, Pedro; Karapetsas, George; Matar, Omar; Sefiane, Khellil; Valluri, Prashant

    2017-11-01

    Evaporation of a binary mixture sessile drop from a solid substrate is a highly dynamic and complex process with flow driven both thermal and solutal Marangoni stresses. Experiments on ethanol/water drops have identified chaotic regimes on both the surface and interior of the droplet, while mixture composition has also been seen to govern drop wettability. Using a lubrication-type approach, we present a finite element model for the evaporation of an axisymmetric binary drop deposited on a heated substrate. We consider a thin drop with a moving contact line, taking also into account the commonly ignored effects of inertia which drives interfacial instability. We derive evolution equations for the film height, the temperature and the concentration field considering that the mixture comprises two ideally mixed volatile components with a surface tension linearly dependent on both temperature and concentration. The properties of the mixture such as viscosity also vary locally with concentration. We explore the parameter space to examine the resultant effects on wetting and evaporation where we find qualitative agreement with experiments in both these areas. This enables us to understand the nature of the instabilities that spontaneously emerge over the drop lifetime. EPSRC - EP/K00963X/1.

  19. Drop detachment and motion on fuel cell electrode materials.

    Science.gov (United States)

    Gauthier, Eric; Hellstern, Thomas; Kevrekidis, Ioannis G; Benziger, Jay

    2012-02-01

    Liquid water is pushed through flow channels of fuel cells, where one surface is a porous carbon electrode made up of carbon fibers. Water drops grow on the fibrous carbon surface in the gas flow channel. The drops adhere to the superficial fiber surfaces but exhibit little penetration into the voids between the fibers. The fibrous surfaces are hydrophobic, but there is a substantial threshold force necessary to initiate water drop motion. Once the water drops begin to move, however, the adhesive force decreases and drops move with minimal friction, similar to motion on superhydrophobic materials. We report here studies of water wetting and water drop motion on typical porous carbon materials (carbon paper and carbon cloth) employed in fuel cells. The static coefficient of friction on these textured surfaces is comparable to that for smooth Teflon. But the dynamic coefficient of friction is several orders of magnitude smaller on the textured surfaces than on smooth Teflon. Carbon cloth displays a much smaller static contact angle hysteresis than carbon paper due to its two-scale roughness. The dynamic contact angle hysteresis for carbon paper is greatly reduced compared to the static contact angle hysteresis. Enhanced dynamic hydrophobicity is suggested to result from the extent to which a dynamic contact line can track topological heterogeneities of the liquid/solid interface.

  20. Wetting 101 degrees.

    Science.gov (United States)

    Gao, Lichao; McCarthy, Thomas J

    2009-12-15

    We review our 2006-2009 publications on wetting and superhydrophobicity in a manner designed to serve as a useful primer for those who would like to use the concepts of this field. We demonstrate that the 1D (three-phase, solid/liquid/vapor) contact line perspective is simpler, more intuitive, more useful, and more consistent with facts than the disproved but widely held-to-be-correct 2D view. We give an explanation of what we believe to be the reason that the existing theoretical understanding is wrong and argue that the teaching of surface science over the last century has led generations of students and scientists to a misunderstanding of the wetting of solids by liquids. We review our analyses of the phenomena of contact angle hysteresis, the lotus effect, and perfect hydrophobicity and suggest that needlessly complex theoretical understandings, incorrect models, and ill-defined terminology are not useful and can be destructive.

  1. Wetting of porous solids.

    Science.gov (United States)

    Patkar, Saket; Chaudhuri, Parag

    2013-09-01

    This paper presents a simple, three stage method to simulate the mechanics of wetting of porous solid objects, like sponges and cloth, when they interact with a fluid. In the first stage, we model the absorption of fluid by the object when it comes in contact with the fluid. In the second stage, we model the transport of absorbed fluid inside the object, due to diffusion, as a flow in a deforming, unstructured mesh. The fluid diffuses within the object depending on saturation of its various parts and other body forces. Finally, in the third stage, oversaturated parts of the object shed extra fluid by dripping. The simulation model is motivated by the physics of imbibition of fluids into porous solids in the presence of gravity. It is phenomenologically capable of simulating wicking and imbibition, dripping, surface flows over wet media, material weakening, and volume expansion due to wetting. The model is inherently mass conserving and works for both thin 2D objects like cloth and for 3D volumetric objects like sponges. It is also designed to be computationally efficient and can be easily added to existing cloth, soft body, and fluid simulation pipelines.

  2. Effect of Atmospheric Press on Wet Bulb Depression

    Science.gov (United States)

    Wheeler, Raymond M.; Stasiak, Michael A.; Lawson, Jamie; Wehkamp, Cara Ann P.; Dixon, Michael A.

    2008-01-01

    Our measurements of wet bulb depression at different pressures matched the modeled adiabatic saturation temps reasonably well. At a dry bulb temp of 25 C, the normal wet bulb temp for 30% RH and 100 kPa is approx.15 C, but this dropped to approx.8 C at 10 kPa. The results suggest that psychrometers need direct calibration at the target pressures or that pressure corrected charts are required. For a given vapour pressure deficit, any moist surfaces, including transpiring plant leaves, will be cooler at lower pressures due to the increased evaporation rates.

  3. Topographical Anisotropy and Wetting of Ground Stainless Steel Surfaces

    Directory of Open Access Journals (Sweden)

    Cornelia Bellmann

    2012-12-01

    Full Text Available Microscopic and physico-chemical methods were used for a comprehensive surface characterization of different mechanically modified stainless steel surfaces. The surfaces were analyzed using high-resolution confocal microscopy, resulting in detailed information about the topographic properties. In addition, static water contact angle measurements were carried out to characterize the surface heterogeneity of the samples. The effect of morphological anisotropy on water contact angle anisotropy was investigated. The correlation between topography and wetting was studied by means of a model of wetting proposed in the present work, that allows quantifying the air volume of the interface water drop-stainless steel surface.

  4. Universality in dynamic wetting dominated by contact-line friction.

    Science.gov (United States)

    Carlson, Andreas; Bellani, Gabriele; Amberg, Gustav

    2012-04-01

    We report experiments on the rapid contact-line motion present in the early stages of capillary-driven spreading of drops on dry solid substrates. The spreading data fail to follow a conventional viscous or inertial scaling. By integrating experiments and simulations, we quantify a contact-line friction μ(f) which is seen to limit the speed of the rapid dynamic wetting. A scaling based on this contact-line friction is shown to yield a universal curve for the evolution of the contact-line radius as a function of time, for a range of fluid viscosities, drop sizes, and surface wettabilities.

  5. Drop impact and rebound dynamics on an inclined superhydrophobic surface.

    Science.gov (United States)

    Yeong, Yong Han; Burton, James; Loth, Eric; Bayer, Ilker S

    2014-10-14

    Due to its potential in water-repelling applications, the impact and rebound dynamics of a water drop impinging perpendicular to a horizontal superhydrophobic surface have undergone extensive study. However, drops tend to strike a surface at an angle in applications. In such cases, the physics governing the effects of oblique impact are not well studied or understood. Therefore, the objective of this study was to conduct an experiment to investigate the impact and rebound dynamics of a drop at various liquid viscosities, in an isothermal environment, and on a nanocomposite superhydrophobic surface at normal and oblique impact conditions (tilted at 15°, 30°, 45°, and 60°). This study considered drops falling from various heights to create normal impact Weber numbers ranging from 6 to 110. In addition, drop viscosity was varied by decreasing the temperature for water drops and by utilizing water-glycerol mixtures, which have similar surface tension to water but higher viscosities. Results revealed that oblique and normal drop impact behaved similarly (in terms of maximum drop spread as well as rebound dynamics) at low normal Weber numbers. However, at higher Weber numbers, normal and oblique impact results diverged in terms of maximum spread, which could be related to asymmetry and more complex outcomes. These asymmetry effects became more pronounced as the inclination angle increased, to the point where they dominated the drop impact and rebound characteristics when the surface was inclined at 60°. The drop rebound characteristics on inclined surfaces could be classified into eight different outcomes driven primarily by normal Weber number and drop Ohnesorge numbers. However, it was found that these outcomes were also a function of the receding contact angle, whereby reduced receding angles yielded tail-like structures. Nevertheless, the contact times of the drops with the coating were found to be generally independent of surface inclination.

  6. Gas Pressure-Drop Experiment

    Science.gov (United States)

    Luyben, William L.; Tuzla, Kemal

    2010-01-01

    Most chemical engineering undergraduate laboratories have fluid mechanics experiments in which pressure drops through pipes are measured over a range of Reynolds numbers. The standard fluid is liquid water, which is essentially incompressible. Since density is constant, pressure drop does not depend on the pressure in the pipe. In addition, flow…

  7. Hanging drop crystal growth apparatus

    Science.gov (United States)

    Naumann, Robert J. (Inventor); Witherow, William K. (Inventor); Carter, Daniel C. (Inventor); Bugg, Charles E. (Inventor); Suddath, Fred L. (Inventor)

    1990-01-01

    This invention relates generally to control systems for controlling crystal growth, and more particularly to such a system which uses a beam of light refracted by the fluid in which crystals are growing to detect concentration of solutes in the liquid. In a hanging drop apparatus, a laser beam is directed onto drop which refracts the laser light into primary and secondary bows, respectively, which in turn fall upon linear diode detector arrays. As concentration of solutes in drop increases due to solvent removal, these bows move farther apart on the arrays, with the relative separation being detected by arrays and used by a computer to adjust solvent vapor transport from the drop. A forward scattering detector is used to detect crystal nucleation in drop, and a humidity detector is used, in one embodiment, to detect relative humidity in the enclosure wherein drop is suspended. The novelty of this invention lies in utilizing angular variance of light refracted from drop to infer, by a computer algorithm, concentration of solutes therein. Additional novelty is believed to lie in using a forward scattering detector to detect nucleating crystallites in drop.

  8. Magnetic control of Leidenfrost drops.

    Science.gov (United States)

    Piroird, Keyvan; Clanet, Christophe; Quéré, David

    2012-05-01

    We show how a magnetic field can influence the motion of a paramagnetic drop made of liquid oxygen in a Leidenfrost state on solids at room temperature. It is demonstrated that the trajectory can be modified in both direction and velocity and that the results can be interpreted in terms of classical mechanics as long as the drop does not get too close to the magnet. We study the deviation and report that it can easily overcome 180∘ and even diverge under certain conditions, leading to situations where a drop gets captured. In the vicinity of the magnet, another type of trapping is observed, due to the deformation of the drop in this region, which leads to a strong energy dissipation. Conversely, drops can be accelerated by moving magnets (slingshot effect).

  9. Macrotextured spoked surfaces reduce the residence time of a bouncing Leidenfrost drop

    Science.gov (United States)

    Patterson, Colin J.; Shiri, Samira; Bird, James C.

    2017-02-01

    Liquid drops can bounce when they impact non-wetting surfaces. Recently, studies have demonstrated that the time that the bouncing drop contacts a superhydrophobic surface can be reduced by incorporating ridged macrotextures on the surface. Yet the existing models aimed at explaining this phenomenon offer incompatible predictions of the contact time when a drop impacts multiple intersecting macrotextures, or spokes. Furthermore, it is unclear whether the effects of the macrotexture on the drop hydrodynamics extend to non-wetting surfaces in which direct contact is avoided by a thin vapor layer. Here we demonstrate that the phenomenon observed for macrotextured, superhydrophobic surfaces extends to macrotextured, wettable surfaces above the Leidenfrost temperature. We show that the number of droplets and overall residence time both depend on the number of intersecting spokes. Finally, we compare and contrast our results with mechanistic models to rationalize various elements of the phenomenon.

  10. The impact of a Leidenfrost drop on a spoked surface texture

    Science.gov (United States)

    Shiri, Samira; Patterson, Colin; Bird, James

    2016-11-01

    Liquid drops can bounce when they impact non-wetting surfaces. Recently, studies have demonstrated that the time that the bouncing drop contacts a superhydrophobic surface can be reduced by incorporating ridged macrotextures on the surface. Yet the existing models aimed at explaining this phenomenon offer incompatible predictions of the contact time when a drop impacts multiple intersecting macrotextures, or spokes. Furthermore, it is unclear whether the effects of the macrotexture on the drop hydrodynamics extend to non-wetting surfaces in which direct contact is avoided by a thin vapor layer. Here we demonstrate that the phenomenon observed for macrotextured, superhydrophobic surfaces extends to macrotextured, wettable surfaces above the Leidenfrost temperature. We show that the number of droplets and overall residence time both depend on the number of intersecting spokes. Finally, we compare and contrast our results with mechanistic models to rationalize various elements of the phenomenon.

  11. Optical wet steam monitor

    Science.gov (United States)

    Maxey, L.C.; Simpson, M.L.

    1995-01-17

    A wet steam monitor determines steam particle size by using laser doppler velocimeter (LDV) device to produce backscatter light. The backscatter light signal is processed with a spectrum analyzer to produce a visibility waveform in the frequency domain. The visibility waveform includes a primary peak and a plurality of sidebands. The bandwidth of at least the primary frequency peak is correlated to particle size by either visually comparing the bandwidth to those of known particle sizes, or by digitizing the waveform and comparing the waveforms electronically. 4 figures.

  12. Trapping leidenfrost drops with crenelations.

    Science.gov (United States)

    Dupeux, Guillaume; Le Merrer, Marie; Clanet, Christophe; Quéré, David

    2011-09-09

    Drops placed on very hot solids levitate on a cushion of their own vapor, as discovered by Leidenfrost. This confers to these drops a remarkable mobility, which makes problematic their control and manipulation. Here we show how crenelated surfaces can be used to increase the friction of Leidenfrost drops by a factor on the order of 100, making them decelerate and be trapped on centimetric distances instead of the usual metric ones. We measure and characterize the friction force as a function of the design of the crenelations.

  13. Wet steam wetness measurement in a 10 MW steam turbine

    Directory of Open Access Journals (Sweden)

    Kolovratník Michal

    2014-03-01

    Full Text Available The aim of this paper is to introduce a new design of the extinction probes developed for wet steam wetness measurement in steam turbines. This new generation of small sized extinction probes was developed at CTU in Prague. A data processing technique is presented together with yielded examples of the wetness distribution along the last blade of a 10MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  14. Effect of humidity on the filter pressure drop

    International Nuclear Information System (INIS)

    Vendel, J.; Letourneau, P.

    1995-01-01

    The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO 2 ). Cesium hydroxyde (CsOH) of size of 2 μ M AMMD has been generated by an ultrasonic generator and the 0.7 μm AMMD titanium oxyde has been dispersed by a open-quotes turn-tableclose quotes generator. As it is noted in the BISWAS'publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced

  15. Effect of humidity on the filter pressure drop

    Energy Technology Data Exchange (ETDEWEB)

    Vendel, J.; Letourneau, P. [Institut de Protection et de Surete Nucleaire, Gif-sur-Yvette (France)

    1995-02-01

    The effects of humidity on the filter pressure drop have been reported in some previous studies in which it is difficult to draw definite conclusions. These studies show contradictory effects of humidity on the pressure drop probably due to differences in the hygroscopicity of the test aerosols. The objective of this paper is to present experimental results on the evolution of the filter pressure drop versus mass loading, for different test aerosols and relative humidities. Present results are compared to those found in various publication. An experimental device has been designed to measure filter pressure drop as the function of the areal density for relative humidity varying in the range of 9 % to 85 %. Experiments have been conducted with hygroscopic: (CsOH) and nonhygroscopic aerosols (TiO{sub 2}). Cesium hydroxyde (CsOH) of size of 2 {mu} M AMMD has been generated by an ultrasonic generator and the 0.7 {mu}m AMMD titanium oxyde has been dispersed by a {open_quotes}turn-table{close_quotes} generator. As it is noted in the BISWAS`publication [3], present results show, in the case of nonhygroscopic aerosols, a linear relationship of pressure drop to mass loading. For hygroscopic aerosols two cases must be considered: for relative humidity below the deliquescent point of the aerosol, the relationship of pressure drop to mass loading remains linear; above the deliquescent point, the results show a sudden increase in the pressure drop and the mass capacity of the filter is drastically reduced.

  16. Flow studies in a wet steam turbine

    Science.gov (United States)

    Evans, D. H.; Pouchot, W. D.

    1974-01-01

    The design and test results of a four stage wet vapor turbine operating with slightly superheated inlet steam and expanding to 10% exit moisture are presented. High speed movies at 3000 frames per second of liquid movement on the pressure side and along the trailing edge of the last stator blade are discussed along with back lighted photographs of moisture drops as they were torn from the stator blade trailing edge. Movies at lower framing rates were also taken of the exit of the last rotating blade and the casing moisture removal slot located in line with the rotor blade shroud. Also moisture removal data are presented of casing slot removal at the exit of the third and fourth rotor blades and for slots located in the trailing edge of the last stator blade. Finally, the degradation of turbine thermodynamic performance due to condensation formation and movement is discussed.

  17. 45-FOOT HIGH DROP TOWER

    Data.gov (United States)

    Federal Laboratory Consortium — The Drop Tower is used to simulate and measure the impact shocks that are exerted on parachute loads when they hit the ground. It is also used for HSL static lift to...

  18. Characteristics of wetting temperature during spray cooling

    International Nuclear Information System (INIS)

    Mitsutake, Yuichi; Monde, Masanori; Hidaka, Shinichirou

    2006-01-01

    An experimental study has been done to elucidate the effects of mass flux and subcooling of liquid and thermal properties of solid on the wetting temperature during cooling of a hot block with spray. A water spray was impinged at one of the end surfaces of a cylindrical block initially heated at 400 or 500degC. The experimental condition was mass fluxes G=1-9 kg/m 2 s and degrees of subcooling ΔT sub =20, 50, 80 K. Three blocks of copper, brass and carbon steel were prepared. During spray cooling internal block temperature distribution and sputtering sound pressure level were recorded and the surface temperature and heat flux were evaluated with 2D inverse heat conducting analysis. Cooling process on cooling curves is divided into four regimes categorized by change in a flow situation and the sound level. The wetting temperature defined as the wall temperature at a minimum heat flux point was measured over an extensive experimental range. The wetting wall temperature was correlated well with the parameter of GΔT sub . The wetting wall temperature increases as GΔT sub increases and reaches a constant value depending on the material of the surface at higher region of GΔT sub . (author)

  19. Should there be a "Wet" Soil Order in Soil Taxonomy?

    Science.gov (United States)

    Rabenhorst, Martin; Wessel, Barret; Stolt, Mark; Lindbo, David

    2017-04-01

    where along the soil wetness continuum would be the best point for recognizing a wet soil order.

  20. Wetting front instability in an initially wet unsaturated fracture

    International Nuclear Information System (INIS)

    Nicholl, M.J.; Glass, R.J.; Nguyen, H.A.

    1993-01-01

    Experimental results exploring gravity-driven wetting from instability in a pre-wetted, rough-walled analog fractures such as those at Yucca Mountain are presented. Initial conditions considered include a uniform moisture field wetted to field capacity of the analog fracture and the structured moisture field created by unstable infiltration into an initially dry fracture. As in previous studies performed under dry initial conditions, instability was found to result both at the cessation of stable infiltration and at flux lower than the fracture capacity under gravitational driving force. Individual fingers were faster, narrower, longer, and more numerous than observed under dry initial conditions. Wetting fronts were found to follow existing wetted structure, providing a mechanism for rapid recharge and transport

  1. Faster multiple emulsification with drop splitting.

    Science.gov (United States)

    Abate, Adam R; Weitz, David A

    2011-06-07

    Microfluidic devices can form emulsions in which the drops have an intricate, controlled structure; however, a challenge is that the droplets are produced slowly, typically only a few millilitres per hour. Here, we present a simple technique to increase the production rate. Using a large drop maker, we produce large drops at a fast volumetric rate; by splitting these drops several times in a splitting array, we create drops of the desired small size. The advantage of this over forming the small drops directly using a small drop maker is that the drops can be formed at much faster rates. This can be applied to the production of single and multiple emulsions.

  2. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen, E-mail: caoj@bjfu.edu.cn; Sun, Wenjing

    2015-01-01

    Highlights: • We studied the dynamic wetting behavior of thermally modified wood by wetting models. • We found lower wetting speed of water droplets on thermally modified wood surface. • Dynamic wetting behavior and surface chemical components show a strong correlation. - Abstract: In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C{sub 1}/C{sub 2} ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood.

  3. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    International Nuclear Information System (INIS)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen; Sun, Wenjing

    2015-01-01

    Highlights: • We studied the dynamic wetting behavior of thermally modified wood by wetting models. • We found lower wetting speed of water droplets on thermally modified wood surface. • Dynamic wetting behavior and surface chemical components show a strong correlation. - Abstract: In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C 1 /C 2 ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood

  4. Spreading Dynamics of an Ellipsoidal Drop Impacting on a Heated Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yun, Sungchan [Korea Nat’l. Univ. of Transportation, Chungju (Korea, Republic of)

    2017-03-15

    Unlike spherical drop impact, ellipsoidal drop impact can control the bouncing height on a heated surface by significantly altering impact behavior. To scrutinize the effect of the aspect ratio (AR) of the drop on the bounce suppression, in this study, non-axisymmetric spreading behaviors are observed from two side views and characterized based on the spreading width of the drop for horizontal principal axes. In addition, the maximum spreading width is investigated for various ARs. The results show that as the AR increases, the maximum spreading width of the minor axis increases, whereas that of the major axis shows no significant variation. In the regime of high AR and high impact velocity, liquid fragmentations by three parts are observed during bouncing. These fragmentations are discussed in this work. The hydrodynamic features of ellipsoidal drop impact will help understand bouncing control on non-wetting surfaces for several applications, such as self-cleaning and spray cooling.

  5. Avoided critical behavior in dynamically forced wetting.

    Science.gov (United States)

    Snoeijer, Jacco H; Delon, Giles; Fermigier, Marc; Andreotti, Bruno

    2006-05-05

    A solid object can be coated by a nonwetting liquid since a receding contact line cannot exceed a critical speed. In this Letter we study the dynamical wetting transition at which a liquid film gets deposited by withdrawing a vertical plate out of a liquid reservoir. It has recently been predicted that this wetting transition is critical with diverging time scales and coincides with the disappearance of stationary menisci. We demonstrate experimentally and theoretically that the transition is due to the formation of a solitary wave, well below the critical point. As a consequence, relaxation times remain finite at threshold. The structure of the liquid deposited on the plate involves a capillary ridge that does not trivially match the Landau-Levich film.

  6. Evaluation of Cask Drop Criticality Issues at K Basin

    Energy Technology Data Exchange (ETDEWEB)

    GOLDMANN, L.H.

    2000-01-24

    An analysis of ability of Multi-canister Overpack (MCO) to withstand drops at K Basin without exceeding the criticality design requirements. Report concludes the MCO will function acceptably. The spent fuel currently residing in the 105 KE and 105 KW storage basins will be placed in fuel storage baskets which will be loaded into the MCO cask assembly. During the basket loading operations the MCO cask assembly will be positioned near the bottom of the south load out pit (SLOP). The loaded MCO cask will be lifted from the SLOP transferred to the transport trailer and delivered to the Cold Vacuum Drying Facility (CVDF). In the wet condition there is a potential for criticality problems if significant changes in the designed fuel configurations occur. The purpose of this report is to address structural issues associated with criticality design features for MCO cask drop accidents in the 105 KE and 105 KW facilities.

  7. Drop formation of black liquor spraying; Mustalipeaen pisaroituminen

    Energy Technology Data Exchange (ETDEWEB)

    Fogelholm, C.J.; Kankkunen, A.; Nieminen, K.; Laine, J.; Miikkulainen, P. [Helsinki Univ. of Technology, Otaniemi (Finland): Lab. of Energy Technology and Environmental Protection

    1997-10-01

    Black liquor is a spent liquor of the pulp and paper industry. It is burned in kraft recovery boilers for chemical and energy recovery. The high dry solids content and viscosity of black liquor require a high spraying temperature. This affects the performance of the boiler. Kraft recovery boiler deposit formation, emissions and chemical recovery are strongly affected by the drop size and the velocity of the black liquor spray formed by a splashplate nozzle. The sheet breakup mechanism is studied with a system based on a video and image-analysis. The drop size of mill-scale nozzles was measured also with an image-analysis-system. Measurements were carried out in a spray test chamber. The sheet breakup mechanism and drop size tests were carried out both below and over the boiling point of black liquor. Special attention was paid to the effect of flashing on drop formation. Temperature increase normally decreases drop size. In the temperature where the wavy-sheet disintegration changes to perforated-sheet disintegration the drop size increases. Spray velocity rises when the temperature is increased above the boiling point. (orig.)

  8. Eliminating bias in rainfall estimates from microwave links due to antenna wetting

    Science.gov (United States)

    Fencl, Martin; Rieckermann, Jörg; Bareš, Vojtěch

    2014-05-01

    Commercial microwave links (MWLs) are point-to-point radio systems which are widely used in telecommunication systems. They operate at frequencies where the transmitted power is mainly disturbed by precipitation. Thus, signal attenuation from MWLs can be used to estimate path-averaged rain rates, which is conceptually very promising, since MWLs cover about 20 % of surface area. Unfortunately, MWL rainfall estimates are often positively biased due to additional attenuation caused by antenna wetting. To correct MWL observations a posteriori to reduce the wet antenna effect (WAE), both empirically and physically based models have been suggested. However, it is challenging to calibrate these models, because the wet antenna attenuation depends both on the MWL properties (frequency, type of antennas, shielding etc.) and different climatic factors (temperature, due point, wind velocity and direction, etc.). Instead, it seems straight forward to keep antennas dry by shielding them. In this investigation we compare the effectiveness of antenna shielding to model-based corrections to reduce the WAE. The experimental setup, located in Dübendorf-Switzerland, consisted of 1.85-km long commercial dual-polarization microwave link at 38 GHz and 5 optical disdrometers. The MWL was operated without shielding in the period from March to October 2011 and with shielding from October 2011 to July 2012. This unique experimental design made it possible to identify the attenuation due to antenna wetting, which can be computed as the difference between the measured and theoretical attenuation. The theoretical path-averaged attenuation was calculated from the path-averaged drop size distribution. During the unshielded periods, the total bias caused by WAE was 0.74 dB, which was reduced by shielding to 0.39 dB for the horizontal polarization (vertical: reduction from 0.96 dB to 0.44 dB). Interestingly, the model-based correction (Schleiss et al. 2013) was more effective because it reduced

  9. Interfacial Instabilities in Evaporating Drops

    Science.gov (United States)

    Moffat, Ross; Sefiane, Khellil; Matar, Omar

    2007-11-01

    We study the effect of substrate thermal properties on the evaporation of sessile drops of various liquids. An infra-red imaging technique was used to record the interfacial temperature. This technique illustrates the non-uniformity in interfacial temperature distribution that characterises the evaporation process. Our results also demonstrate that the evaporation of methanol droplets is accompanied by the formation of wave-trains in the interfacial temperature field; similar patterns, however, were not observed in the case of water droplets. More complex patterns are observed for FC-72 refrigerant drops. The effect of substrate thermal conductivity on the structure of the complex pattern formation is also elucidated.

  10. The Influence of Surface Anisotropy Crystalline Structure on Wetting of Sapphire by Molten Aluminum

    Science.gov (United States)

    Aguilar-Santillan, Joaquin

    2013-05-01

    The wetting of sapphire by molten aluminum was investigated by the sessile drop technique from 1073 K to 1473 K (800 °C to 1200 °C) at PO2 <10-15 Pa under Ar atmosphere. This study focuses on sapphire crystalline structure and its principle to the interface. The planes " a" and " b" are oxygen terminated structures and wet more by Al, whereas the " c" plane is an aluminum terminated structure. A wetting transition at 1273 K (1000 °C) was obtained and a solid surface tension proves the capillarity trends of the couple.

  11. Many Drops Interactions I: Simulation of Coalescence, Flocculation and Fragmentation of Multiple Colliding Drops with Smoothed Particle Hydrodynamics

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé

    2012-06-01

    Full Text Available Smoothed Particle Hydrodynamics (SPH is a Lagrangian mesh-free formalism and has been useful to model continuous fluid. This formalism is employed to solve the Navier-Stokes equations by replacing the fluid with a set of particles. These particles are interpolation points from which properties of the fluid can be determined. In this study, the SPH method is applied to simulate the hydrodynamics interaction of many drops, showing some settings for the coalescence, fragmentation and flocculation problem of equally sized liquid drops in three-dimensional spaces. For small velocities the drops interact only through their deformed surfaces and the flocculation of the droplets arises. This result is very different if the collision velocity is large enough for the fragmentation of droplets takes place. We observe that for velocities around 15 mm/ms the coalescence of droplets occurs. The velocity vector fields formed inside the drops during the collision process are shown.

  12. Pressure drop in contraction flow

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz

    This note is a supplement to Dynamic of Polymeric Liquids (DPL) page 178. DPL gives an equation for the pressure drop in a tapered (and circular) contraction, valid only at low angles. Here the general definition of contraction flow (the Bagley correction) and a more general method to find...

  13. Fluid flow in drying drops

    NARCIS (Netherlands)

    Gelderblom, Hanneke

    2013-01-01

    When a suspension drop evaporates, it leaves behind a drying stain. Examples of these drying stains encountered in daily life are coffee or tea stains on a table top, mineral rings on glassware that comes out of the dishwasher, or the salt deposits on the streets in winter. Drying stains are also

  14. Drops, contact lines, and electrowetting

    NARCIS (Netherlands)

    't Mannetje, Dieter

    2013-01-01

    In this work, we study the behaviour of drops and contact lines under the influence of electric fields, and how these can answer fundamental and industrial questions. Our focus is on studying the varying balance of the electric field, hysteresis forces and inertia as the speed of a contact line

  15. Correction of Pressure Drop in Steam and Water System in Performance Test of Boiler

    Science.gov (United States)

    Liu, Jinglong; Zhao, Xianqiao; Hou, Fanjun; Wu, Xiaowu; Wang, Feng; Hu, Zhihong; Yang, Xinsen

    2018-01-01

    Steam and water pressure drop is one of the most important characteristics in the boiler performance test. As the measuring points are not in the guaranteed position and the test condition fluctuation exsits, the pressure drop test of steam and water system has the deviation of measuring point position and the deviation of test running parameter. In order to get accurate pressure drop of steam and water system, the corresponding correction should be carried out. This paper introduces the correction method of steam and water pressure drop in boiler performance test.

  16. Capillary migration of large confined super-hydrophobic drops in wedges

    Science.gov (United States)

    Torres, Logan; Weislogel, Mark; Arnold, Sam

    2016-11-01

    When confined within an interior corner, drops and bubbles migrate to regions of minimum energy by the combined effects of surface tension, surface wetting, and corner geometry. Such capillary phenomena are exploited for passive phase separation operations in micro-fluidic devices on earth and macro-fluidic devices aboard spacecraft. Our study focuses on the migration of large inertial-capillary drops confined between two planar super-hydrophobic surfaces. In our experiments, the near weightless environment of a drop tower produces Bo <<1 for drop volumes O(10mL) with migration velocities up to 10 cm/s. We observe transient power law behavior as a function of drop volume, wedge angle, initial confinement, and fluid properties including contact angle. We then further demonstrate how the experiment method may be employed as a large horizontal quiescent droplet generator for studies ranging from inertial non-wetting moving contact line investigations to large geyser-free horizontal drop impacts. NASA Cooperative Agreement NNX12AO47A, URMP.

  17. Effects of Relative Humidity on the Coalescence of Small Precipitation Drops in Free Fall.

    Science.gov (United States)

    Ochs, Harry T., III; Beard, Kenneth V.; Laird, Neil F.; Holdridge, Donna J.; Schaufelberger, Daniel E.

    1995-11-01

    Observations of the effects of relative humidity on coalescence are limited to studies using supported drops or streams of drops, and the results are contradictory. In this paper, findings are presented on the effect of high and low relative humidity on collisions between freely falling drops. Comparisons between the collision outcomes (coalescence, bounce, and temporary coalescence with and without satellite drops) for high-humidity (RH > 95%) and low-humidity (RH 30%) experiments were made for small precipitation drops at terminal velocity and with minimal electric charge. Coalescence begins after the air-film between colliding drops is drained sufficiently to allow the drops to make contact. For temporary coalescence, the union of the two drops is not permanent because the rotational energy caused by a non-head-on collision is sufficient to pull the coalesing drops apart. One or more satellite drops form during a temporary coalescence when water filament between the separating drops breaks in more than one location. Experiments with higher drop charge were used to examine further the influence of humidity on coalescence. Our results show that relative humidity does not affect the coalescence efficiency for small precipitation drops. The effect of humidity is limited to collisions where permanent coalescence does not occur, and the collision outcome can be temporary coalescence. In cases where bounce is also a possible outcome, it was found that the probability of bounce is enhanced at the expense of temporary coalescence when relative humidity is decreased. For two of the comparisons between high-humidity and low-humidity results, the fraction of temporary coalescence collision outcomes halved at low humidity. Since the colliding drops are at the wet-bulb temperature, this effect is traced to the colder air gap that drains more slowly and retards coalescence at lower humidifies. At high relative humidity the number of satellite drops about doubles with the

  18. Dancing drops over vibrating substrates

    Science.gov (United States)

    Borcia, Rodica; Borcia, Ion Dan; Helbig, Markus; Meier, Martin; Egbers, Christoph; Bestehorn, Michael

    2017-04-01

    We study the motion of a liquid drop on a solid plate simultaneously submitted to horizontal and vertical harmonic vibrations. The investigation is done via a phase field model earlier developed for describing static and dynamic contact angles. The density field is nearly constant in every bulk region (ρ = 1 in the liquid phase, ρ ≈ 0 in the vapor phase) and varies continuously from one phase to the other with a rapid but smooth variation across the interfaces. Complicated explicit boundary conditions along the interface are avoided and captured implicitly by gradient terms of ρ in the hydrodynamic basic equations. The contact angle θ is controlled through the density at the solid substrate ρ S , a free parameter varying between 0 and 1 [R. Borcia, I.D. Borcia, M. Bestehorn, Phys. Rev. E 78, 066307 (2008)]. We emphasize the swaying and the spreading modes, earlier theoretically identified by Benilov and Billingham via a shallow-water model for drops climbing uphill along an inclined plane oscillating vertically [E.S. Benilov, J. Billingham, J. Fluid Mech. 674, 93 (2011)]. The numerical phase field simulations will be completed by experiments. Some ways to prevent the release of the dancing drops along a hydrophobic surface into the gas atmosphere are also discussed in this paper.

  19. Numerical analysis of wet separation of particles by density differences

    Science.gov (United States)

    Markauskas, D.; Kruggel-Emden, H.

    2017-07-01

    Wet particle separation is widely used in mineral processing and plastic recycling to separate mixtures of particulate materials into further usable fractions due to density differences. This work presents efforts aiming to numerically analyze the wet separation of particles with different densities. In the current study the discrete element method (DEM) is used for the solid phase while the smoothed particle hydrodynamics (SPH) is used for modeling of the liquid phase. The two phases are coupled by the use of a volume averaging technique. In the current study, simulations of spherical particle separation were performed. In these simulations, a set of generated particles with two different densities is dropped into a rectangular container filled with liquid. The results of simulations with two different mixtures of particles demonstrated how separation depends on the densities of particles.

  20. 40 CFR 424.40 - Applicability; description of the covered calcium carbide furnaces with wet air pollution control...

    Science.gov (United States)

    2010-07-01

    ... covered calcium carbide furnaces with wet air pollution control devices subcategory. 424.40 Section 424.40... FERROALLOY MANUFACTURING POINT SOURCE CATEGORY Covered Calcium Carbide Furnaces With Wet Air Pollution... with wet air pollution control devices subcategory. The provisions of this subpart are applicable to...

  1. 40 CFR 425.10 - Applicability; description of the hair pulp, chrome tan, retan-wet finishing subcategory.

    Science.gov (United States)

    2010-07-01

    ... pulp, chrome tan, retan-wet finishing subcategory. 425.10 Section 425.10 Protection of Environment... POINT SOURCE CATEGORY Hair Pulp, Chrome Tan, Retan-Wet Finish Subcategory § 425.10 Applicability; description of the hair pulp, chrome tan, retan-wet finishing subcategory. The provisions of this subpart are...

  2. 40 CFR 425.20 - Applicability; description of the hair save, chrome tan, retan-wet finish subcategory.

    Science.gov (United States)

    2010-07-01

    ... save, chrome tan, retan-wet finish subcategory. 425.20 Section 425.20 Protection of Environment... POINT SOURCE CATEGORY Hair Save, Chrome Tan, Retan-Wet Finish Subcategory § 425.20 Applicability; description of the hair save, chrome tan, retan-wet finish subcategory. The provisions of this subpart are...

  3. Active connectors for microfluidic drops on demand

    Energy Technology Data Exchange (ETDEWEB)

    Galas, Jean-Christophe; Studer, Vincent [Laboratoire de Neurobiologie, ESPCI-CNRS UMR 7637, 10 rue Vauquelin 75231 Paris cedex 05 (France); Bartolo, Denis [PMMH-ESPCI-CNRS UMR 7636-Universite Paris 6-Universite Paris 7, 10 rue Vauquelin 75231 Paris cedex 05 (France)], E-mail: jean-christophe.galas@espci.fr, E-mail: denis.bartolo@espci.fr, E-mail: vincent.studer@espci.fr

    2009-07-15

    We introduce a simple and versatile microfluidic drop-on-demand solution that enables independent and dynamical control of both the drop size and the drop production rate. To do so, we combine a standard microfluidic T-junction and a novel active switching component that connects the microfluidic channel to the macroscopic liquid reservoirs. Firstly, we explain how to make this simple but accurate drop-on-demand device. Secondly, we carefully characterize its dynamic response and its range of operations. Finally, we show how to generate complex two-dimensional drop patterns dynamically in single or multiple synchronized drop-on-demand devices.

  4. Semifluorinated Alkane Eye Drops for Treatment of Dry Eye Disease--A Prospective, Multicenter Noninterventional Study.

    Science.gov (United States)

    Steven, Philipp; Scherer, Dieter; Krösser, Sonja; Beckert, Michael; Cursiefen, Claus; Kaercher, Thomas

    2015-10-01

    Evaporation of the tear film is heavily discussed as one core reason for dry eye disease (DED). Subsequently, new artificial tear products are developed that specifically target this pathomechanism. Perfluorohexyloctane (F6H8, NovaTears(®)) from the family of semifluorinated alkanes is a novel substance that has been approved as a medical device, as a nonblurring wetting agent for the ocular surface. Thirty patients with hyperevaporative dry eye received F6H8 during a prospective, multicenter, observational 6-week study. Patients were advised to apply 1 drop 4 times daily in both eyes. Parameters assessed included best corrected visual acuity, intraocular pressure, Schirmer I test, tear fluid, tear film breakup time (TFBUT), corneal staining, meibum secretion, and Ocular Surface Disease Index (OSDI(©)). From the 30 patients recruited, 25 completed the trial per protocol. Four patients discontinued F6H8 and 1 patient did not present for follow-up. F6H8 treatment led to significant reduction of corneal staining and significant increase of Schirmer I and TFBUT. In addition, OSDI score dropped significantly from a mean of 55 (± 23.0) to 34 (± 22.4). Visual acuity and ocular pressure did not change. This prospective observational study shows significant beneficial effects in patients suffering from evaporative DED, using F6H8 in all the relevant parameters tested. The decrease of the OSDI by a mean of 21 points was particularly remarkable and clearly exceeds minimal, clinical important differences for mild or moderate and severe disease. Overall, F6H8 (NovaTears) seems to be safe and effective in treating mild to moderate hyperevaporative DED.

  5. Semifluorinated Alkane Eye Drops for Treatment of Dry Eye Disease—A Prospective, Multicenter Noninterventional Study

    Science.gov (United States)

    Scherer, Dieter; Krösser, Sonja; Beckert, Michael; Cursiefen, Claus; Kaercher, Thomas

    2015-01-01

    Abstract Purpose: Evaporation of the tear film is heavily discussed as one core reason for dry eye disease (DED). Subsequently, new artificial tear products are developed that specifically target this pathomechanism. Perfluorohexyloctane (F6H8, NovaTears®) from the family of semifluorinated alkanes is a novel substance that has been approved as a medical device, as a nonblurring wetting agent for the ocular surface. Methods: Thirty patients with hyperevaporative dry eye received F6H8 during a prospective, multicenter, observational 6-week study. Patients were advised to apply 1 drop 4 times daily in both eyes. Parameters assessed included best corrected visual acuity, intraocular pressure, Schirmer I test, tear fluid, tear film breakup time (TFBUT), corneal staining, meibum secretion, and Ocular Surface Disease Index (OSDI©). Results: From the 30 patients recruited, 25 completed the trial per protocol. Four patients discontinued F6H8 and 1 patient did not present for follow-up. F6H8 treatment led to significant reduction of corneal staining and significant increase of Schirmer I and TFBUT. In addition, OSDI score dropped significantly from a mean of 55 (±23.0) to 34 (±22.4). Visual acuity and ocular pressure did not change. Conclusions: This prospective observational study shows significant beneficial effects in patients suffering from evaporative DED, using F6H8 in all the relevant parameters tested. The decrease of the OSDI by a mean of 21 points was particularly remarkable and clearly exceeds minimal, clinical important differences for mild or moderate and severe disease. Overall, F6H8 (NovaTears) seems to be safe and effective in treating mild to moderate hyperevaporative DED. PMID:26296040

  6. Investigation on flow and heat transfer characteristics in rectangular channel with drop-shaped pin fins

    Directory of Open Access Journals (Sweden)

    Fengming Wang

    2012-12-01

    Full Text Available The flow and heat transfer characteristics inside a rectangular channel embedded with pin fins were numerically and experimentally investigated. Several differently shaped pin fins (i.e., circular, elliptical, and drop-shaped with the same cross-sectional areas were compared in a staggered arrangement. The Reynolds number based on the obstructed section hydraulic diameter (defined as the ratio of the total wetted surface area to the open duct volume available for flow was varied from 4800 to 8200. The more streamlined drop-shaped pin fins were better at delaying or suppressing separation of the flow passing through them, which decreased the aerodynamic penalty compared to circular pin fins. The heat transfer enhancement of the drop-shaped pin fins was less than that of the circular pin fins. In terms of specific performance parameters, drop-shaped pin fins are a promising alternative configuration to circular pin fins.

  7. Process for recovering uranium from wet process phosphoric acid (III)

    International Nuclear Information System (INIS)

    Pyrih, R.Z.; Rickard, R.S.; Carrington, O.F.

    1983-01-01

    Uranium is conventionally recovered from wet-process phosphoric acid by two liquid ion exchange steps using a mixture of mono- and disubstituted phenyl esters of orthophosphoric acid (OPPA). Efficiency of the process drops as the mono-OPPA is lost preferentially to the aqueous phase. This invention provides a process for the removal of the uranium process organics (OPPA and organic solvents) from the raffinate of the first liquid ion exchange step and their return to the circuit. The process organics are removed by a combination flotation and absorption step, which results in the recovery of the organics on beads of a hydrophobic styrene polymer

  8. Aerial wetting contact angle measurement using confocal microscopy

    OpenAIRE

    Chesna, Jacob W.; Wiedmaier, Bob F.; Wang, Jinlin; Samara, Ayman; Leach, Richard K.; Her, Tsing-Hua; Smith, Stuart T.

    2016-01-01

    A method is presented in which the wetting contact angle of a sessile drop is acquired aerially using confocal techniques to measure the radius and the height of a droplet deposited on a planar surface. The repeatability of this method is typically less than 0.25°, and often less than 0.1°, for droplet diameters less than 1 mm. To evaluate accuracy of this method, an instrument uncertainty budget is developed, which predicts a combined uncertainty of 0.91° for a 1 mm diameter water droplet wi...

  9. Wetting of Water on Graphene

    KAUST Repository

    Bera, Bijoyendra

    2016-11-28

    The wetting properties of graphene have proven controversial and difficult to assess. The presence of a graphene layer on top of a substrate does not significantly change the wetting properties of the solid substrate, suggesting that a single graphene layer does not affect the adhesion between the wetting phase and the substrate. However, wetting experiments of water on graphene show contact angles that imply a large amount of adhesion. Here, we investigate the wetting of graphene by measuring the mass of water vapor adsorbing to graphene flakes of different thickness at different relative humidities. Our experiments unambiguously show that the thinnest of graphene flakes do not adsorb water, from which it follows that the contact angle of water on these flakes is ~180o. Thicker flakes of graphene nanopowder, on the other hand, do adsorb water. A calculation of the van der Waals (vdW) interactions that dominate the adsorption in this system confirms that the adhesive interactions between a single atomic layer of graphene and water are so weak that graphene is superhydrophobic. The observations are confirmed in an independent experiment on graphene-coated water droplets that shows that it is impossible to make liquid \\'marbles\\' with molecularly thin graphene.

  10. Coffee-stain growth dynamics on dry and wet surfaces

    Science.gov (United States)

    Boulogne, François; Ingremeau, François; Stone, Howard A.

    2017-02-01

    The drying of a drop containing particles often results in the accumulation of the particles at the contact line. In this work, we investigate the drying of an aqueous colloidal drop surrounded by a hydrogel that is also evaporating. We combine theoretical and experimental studies to understand how the surrounding vapor concentration affects the particle deposit during the constant radius evaporation mode. In addition to the common case of evaporation on an otherwise dry surface, we show that in a configuration where liquid is evaporating from a flat surface around the drop, the singularity of the evaporative flux at the contact line is suppressed and the drop evaporation is homogeneous. For both conditions, we derive the velocity field and we establish the temporal evolution of the number of particles accumulated at the contact line. We predict the growth dynamics of the stain and the drying timescales. Thus, dry and wet conditions are compared with experimental results and we highlight that only the dynamics is modified by the evaporation conditions, not the final accumulation at the contact line.

  11. A drop penetration method to measure powder blend wettability.

    Science.gov (United States)

    Wang, Yifan; Liu, Zhanjie; Muzzio, Fernando; Drazer, German; Callegari, Gerardo

    2018-03-01

    Water wettability of pharmaceutical blends affects important quality attributes of final products. We investigate the wetting properties of a pharmaceutical blend lubricated with Magnesium Stearate (MgSt) as a function of the mechanical shear strain applied to the blend. We measure the penetration dynamics of sessile drops deposited on slightly compressed powder beds. We consider a blend composed of 9% Acetaminophen 90% Lactose and 1% MgSt by weight. Comparing the penetration time of water and a reference liquid Polydimethylsiloxane (silicon oil) we obtain an effective cosine of the contact angle with water, based on a recently developed drop penetration method. We repeat the experiments for blends exposed to increasing levels of shear strain and demonstrate a significant decrease in water wettability (decrease in the cosine of the contact angle). The results are consistent with the development of a hydrophobic film coating the powder particles as a result of the increased shear strain. Finally, we show that, as expected dissolution times increase with the level of shear strain. Therefore, the proposed drop penetration method could be used to directly assess the state of lubrication of a pharmaceutical blend and act as a quality control on powder blend attributes before the blend is tableted. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Drag and drop display & builder

    Energy Technology Data Exchange (ETDEWEB)

    Bolshakov, Timofei B.; Petrov, Andrey D.; /Fermilab

    2007-12-01

    The Drag and Drop (DnD) Display & Builder is a component-oriented system that allows users to create visual representations of data received from data acquisition systems. It is an upgrade of a Synoptic Display mechanism used at Fermilab since 2002. Components can be graphically arranged and logically interconnected in the web-startable Project Builder. Projects can be either lightweight AJAX- and SVG-based web pages, or they can be started as Java applications. The new version was initiated as a response to discussions between the LHC Controls Group and Fermilab.

  13. Determination of the solid surface critical exponent β_1 from contact-angle variation on approach to a wetting transition: Cyclohexane/aniline/quartz

    International Nuclear Information System (INIS)

    Pallas, Norman R.

    2016-01-01

    The three-phase contact angle (θ) for the system cyclohexane/aniline/quartz has been measured from drop shapes as a function of temperature on approach to the cyclohexane/aniline upper consolute solution temperature T_c. The experiments employed exacting criteria previously established for thermodynamic-quality measurements at fluid interfaces. A first-order wetting transition from partial wetting to complete wetting was observed at a temperature T_w, 2.12 K below T_c. The contact angle vanishes at T_w, scaling as cos θ ∼ |T − T_c|"β"_1"−"μ for T < T_w and cos θ = 1.0 for T_w < T < T_c. The experimental results give a value for β_1 = 0.74 ± 0.03, in agreement with theoretical calculations. The data clearly rule out higher order contributions to the change in the contact angle near the critical point for this system. These results are in marked contrast to previous measurements on this system from measurements of capillary rise and meniscus curvature.

  14. Determination of the solid surface critical exponent β{sub 1} from contact-angle variation on approach to a wetting transition: Cyclohexane/aniline/quartz

    Energy Technology Data Exchange (ETDEWEB)

    Pallas, Norman R., E-mail: Sam-7-iam@hotmail.com [BP Research Centre Warrensville, 4440 Warrensville Center Road, Cleveland, Ohio 44128 (United States)

    2016-03-21

    The three-phase contact angle (θ) for the system cyclohexane/aniline/quartz has been measured from drop shapes as a function of temperature on approach to the cyclohexane/aniline upper consolute solution temperature T{sub c}. The experiments employed exacting criteria previously established for thermodynamic-quality measurements at fluid interfaces. A first-order wetting transition from partial wetting to complete wetting was observed at a temperature T{sub w}, 2.12 K below T{sub c}. The contact angle vanishes at T{sub w}, scaling as cos θ ∼ |T − T{sub c}|{sup β{sub 1}−μ} for T < T{sub w} and cos θ = 1.0 for T{sub w} < T < T{sub c}. The experimental results give a value for β{sub 1} = 0.74 ± 0.03, in agreement with theoretical calculations. The data clearly rule out higher order contributions to the change in the contact angle near the critical point for this system. These results are in marked contrast to previous measurements on this system from measurements of capillary rise and meniscus curvature.

  15. Physical chemistry of wet chemical anisotropic etching of silicon

    NARCIS (Netherlands)

    Elwenspoek, Michael Curt

    1995-01-01

    In this paper we explain a view to understand the anisotropy of the etching of silicon in certain wet chemical agents (such as KOH). The starting point is the assumption that the [Left angle bracket]111[Right Angle Bracket] face of silicon is a flat face, the etch rate of which is then governed by a

  16. Manipulating dynamic drops using a hybrid superhydrophobic/hydrophilic surface

    Science.gov (United States)

    Guo, Yunhe; Song, Dong; Song, Baowei; Hu, Haibao

    2016-11-01

    A hybrid surface composed of superhydrophobic patterns on hydrophilic substrate was fabricated by selective painting. The impingement of a water drop on this surface was investigated using lattice Boltzmann simulation. When a drop impinged on the boundary line between the superhydrophobic and hydrophilic area, the drop would spread preferentially to the hydrophilic area while the spreading at the superhydrophobic area was highly impeded. The maximum spreading diameters as well as the spreading time, which are extremely important for the heat transfer on solid surfaces, were analyzed in detail. By adjusting the distance between the landing point and the boundary line of the superhydrophobic/hydrophilic area, the maximum spreading diameter and spreading time could be altered precisely. The impinging velocity has been found to be important on the manipulation of the dynamic droplet as well.

  17. Asymmetric drop coalescence launches fungal ballistospores with directionality.

    Science.gov (United States)

    Liu, Fangjie; Chavez, Roger L; Patek, S N; Pringle, Anne; Feng, James J; Chen, Chuan-Hua

    2017-07-01

    Thousands of fungal species use surface energy to power the launch of their ballistospores. The surface energy is released when a spherical Buller's drop at the spore's hilar appendix merges with a flattened drop on the adaxial side of the spore. The launching mechanism is primarily understood in terms of energetic models, and crucial features such as launching directionality are unexplained. Integrating experiments and simulations, we advance a mechanistic model based on the capillary-inertial coalescence between the Buller's drop and the adaxial drop, a pair that is asymmetric in size, shape and relative position. The asymmetric coalescence is surprisingly effective and robust, producing a launching momentum governed by the Buller's drop and a launching direction along the adaxial plane of the spore. These key functions of momentum generation and directional control are elucidated by numerical simulations, demonstrated on spore-mimicking particles, and corroborated by published ballistospore kinematics. Our work places the morphological and kinematic diversity of ballistospores into a general mechanical framework, and points to a generic catapulting mechanism of colloidal particles with implications for both biology and engineering. © 2017 The Author(s).

  18. Does Surface Roughness Amplify Wetting?

    Czech Academy of Sciences Publication Activity Database

    Malijevský, Alexandr

    2014-01-01

    Roč. 141, č. 18 (2014), s. 184703 ISSN 0021-9606 R&D Projects: GA ČR GA13-09914S Institutional support: RVO:67985858 Keywords : density functional theory * wetting * roughness Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.952, year: 2014

  19. Coalescence of fog droplets: Differential fog water deposition on wet and dry forest canopies

    Science.gov (United States)

    Tobón, C.; Barrero, J.

    2010-07-01

    The Páramo ecosystem is a high-altitude (2800 - 4500 masl), natural ecosystems which comprises approximately 42000 km2, extending across the Andes from north of Peru, Ecuador, Colombia and western part of Venezuela. Andean páramos are widely considered to be prime suppliers of large volumes of high-quality water for large cities and for hydropower production. As páramos tend to be subjected to persistent fog incidence, fog interception by the vegetation is a common process in these ecosystems, representing not only an extra input of water to the ecosystem but also to suppress evaporation. In this process, small drops of water, transported by the wind, are captured by the surfaces of the vegetation, acting as physical obstacles to the flow of fog. These drops condense in the exposed surfaces and drip towards the ground or evaporate from the surfaces. The quantification of the magnitude of these processes is important for the quantification of the water balance of river basins where these types of ecosystems exist. Although the great hydrological importance of fog in montane tropical ecosystems little is known about its physical principles related to the interception of fog by physical barriers as vegetation, notably the differential behaviour of a wet and dry vegetation in the efficiency of capturing water from the fog. To characterize and quantify this efficiency of páramo vegetation in capturing water from the fog, during wet and dry canopy conditions, an experimental design was set up at the Páramo de Chingaza (Colombia) where paired samples of espeletia branches (dry and wet) were exposed to different fog events, and at the same time Juvik cylinders were exposed by the side of the experimental site, to measured fog inputs. Cylinders were also paired (wet and dry) at the beginning of the experiments. Results indicated that exposed wet and dry samples have a significant difference on the magnitude of water intercepted from the fog, being, in average, the wet

  20. Child Abuse and Neglect Among Children Who Drop Out of School: A Study in Izmir, Turkey.

    Science.gov (United States)

    Sofuoğlu, Zeynep; Sariyer, Görkem; Aydin, Fulya; Cankardas, Sinem; Kandemirci, Birsu

    2016-10-01

    Child abuse and neglect (CAN), and dropping out of school have long been recognized as pervasive social problems globally, and Turkey is no exception. This study aims to explore the prevalence and incidence of CAN in children who drop out of school of Turkey, using the ISPCAN Child abuse Screening Tool, Children's Version, which is an appropriate tool for multinational comparisons. Data from a convenience sample of children who drop out of school age 11, 13, and 16 from Izmir were collected either by interviews or by self-completion. The results show that, compared to children who do not drop out of school, children who drop out of school have higher rates of psychological and physical abuse and neglect within the family. This study not only highlights the need for preventive laws for CAN and dropping out of school, but also points to direction for future research.

  1. 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.

  2. The Rhetoric of "Unconditional Surrender" and the Decision to Drop the Atomic Bomb.

    Science.gov (United States)

    Hikins, James W.

    1983-01-01

    Analyzes the decision to drop the atomic bomb from a rhetorical point of view, arguing that the bombs were launched because of an American commitment to a particular rhetoric that focused on the propaganda slogan "unconditional surrender." (PD)

  3. Wetting of two-dimensional physically patterned surfaces

    Science.gov (United States)

    Bell, Michael Scott

    An understanding of wetting phenomena is important, in part, due to the many practical applications of controlled wetting. Some of the most exciting applications involve superhydrophobic surfaces, on which water droplets exhibit contact angles larger than 150° and contact angle hysteresis less than 10°. These surfaces are notable for their low-drag, antifouling, and self-cleaning properties, among others. Wetting is known to be affected by both the chemistry and the physical patterning of a surface, with the chemistry affecting what is called the intrinsic contact angle, which is the contact angle displayed by a droplet on a smooth flat surface made of the given material. To date, the largest intrinsic contact angle observed for any material is only about 120°, which does not confer superhydrophobicity. Thus, physical patterning is a crucial component of any superhydrophobic surface. Interestingly, many natural examples of superhydrophobic surfaces exist, with one of the most notable being the lotus leaf. In designing such surfaces, scientists have turned to the natural examples for inspiration, and have found that most natural examples have multiple (usually two) scales of roughness, commonly referred to as hierarchical roughness. Though hierarchical roughness is ubiquitous in the superhydrophobic surfaces of the natural world, its precise role in conferring superhydrophobicity has so far remained elusive. In this work, we develop a thermodynamic model to study the wetting of two-dimensional physically patterned surfaces. Past models that have been developed for this purpose often make several assumptions: the drop must be much larger than the surface features while simultaneously being small enough that the effects of gravity are negligible. Many of these models ultimately rely on the older Cassie and Wenzel models, which themselves make assumptions about the drop size relative to the surface features--namely that the drop is again much larger than the surface

  4. Wetting behaviour and reactivity between liquid Gd and ZrO2 substrate

    Directory of Open Access Journals (Sweden)

    Turalska P.

    2017-01-01

    Full Text Available The wetting behavior and reactivity between molten pure Gd and polycrystalline 3YSZ substrate (ZrO2 stabilized with 3 wt% of Y2O3were experimentally determined by a sessile drop method using a classical contact heating coupled with drop pushing procedure. The test was performed under an inert flowing gas atmosphere (Ar at two temperatures of 1362°C and 1412°C. Immediately after melting (Tm=1341°C, liquid Gd did not wet the substrate forming a contact angle of θ=141°. The non-wetting to wetting transition (θ < 90° took place after about 110 seconds of interaction and was accompanied by a sudden decrease in the contact angle value to 67°. Further heating of the couple to 1412 °C did not affect wetting (θ=67°±1°. The solidified Gd/3YSZ couple was studied by means of optical microscopy and scanning electron microscopy coupled with X-ray energy dispersive spectroscopy. Structural investigations revealed that the wettability in the Gd/3YSZ system is of a reactive nature associated with the formation of a continuous layer of a wettable reaction product Gd2Zr2O7.

  5. Kinetic effects in dynamic wetting

    Science.gov (United States)

    Sprittles, James

    2017-11-01

    The maximum speed at which a liquid can wet a solid is limited by the need to displace gas lubrication films in front of the moving contact line. The characteristic height of these films is often comparable to the mean free path in the gas so that hydrodynamic models do not adequately describe the flow physics. In this talk, I will develop a model which incorporates kinetic effects in the gas, via the Boltzmann equation, and can predict experimentally-observed increases in the maximum speed of wetting when (a) the liquid's viscosity is varied, (b) the ambient gas pressure is reduced or (c) the meniscus is confined. This work was supported by the Leverhulme Trust (Research Project Grant) and the Engineering & Physical Sciences Research Council (Grant EP/N016602/1).

  6. Formative Assessment Probes: Wet Jeans

    Science.gov (United States)

    Keeley, Page

    2015-01-01

    Picture a wet towel or a puddle of water on a hot, sunny day. An hour later, the towel is dry and the puddle no longer exists. What happened to the water? Where did it go? These are questions that reveal myriad interesting student ideas about evaporation and the water cycle--ideas that provide teachers with a treasure trove of data they can use to…

  7. Wet water glass production plant

    Directory of Open Access Journals (Sweden)

    Stanković Mirjana S.

    2003-01-01

    Full Text Available The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant of a capacity of 75,000 t/y was manufactured, at "Zeolite Mira", Mira (VE, Italy, in 1997. and 1998, increasing detergent zeolite production, from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate dissolution plant. The main goal was increasing the detergent zeolite production. The technological cycle of NaOH was closed, and no effluents emitted, and there is no pollution (except for the filter cake. The wet water glass production process is fully automatized, and the product has uniform quality. The production process can be controlled manually, which is necessary during start - up, and repairs. By installing additional process equipment (centrifugal pumps and heat exchangers technological bottlenecks were overcome, and by adjusting the operation of autoclaves, and water glass filters and also by optimizing the capacities of process equipment.

  8. Surface Modifications in Adhesion and Wetting

    Science.gov (United States)

    Longley, Jonathan

    Advances in surface modification are changing the world. Changing surface properties of bulk materials with nanometer scale coatings enables inventions ranging from the familiar non-stick frying pan to advanced composite aircraft. Nanometer or monolayer coatings used to modify a surface affect the macro-scale properties of a system; for example, composite adhesive joints between the fuselage and internal frame of Boeing's 787 Dreamliner play a vital role in the structural stability of the aircraft. This dissertation focuses on a collection of surface modification techniques that are used in the areas of adhesion and wetting. Adhesive joints are rapidly replacing the familiar bolt and rivet assemblies used by the aerospace and automotive industries. This transition is fueled by the incorporation of composite materials into aircraft and high performance road vehicles. Adhesive joints have several advantages over the traditional rivet, including, significant weight reduction and efficient stress transfer between bonded materials. As fuel costs continue to rise, the weight reduction is accelerating this transition. Traditional surface pretreatments designed to improve the adhesion of polymeric materials to metallic surfaces are extremely toxic. Replacement adhesive technologies must be compatible with the environment without sacrificing adhesive performance. Silane-coupling agents have emerged as ideal surface modifications for improving composite joint strength. As these coatings are generally applied as very thin layers (compression of a water drop between two gradient surfaces. This inchworm type motion is studied in detail and offers an alternative method to surface vibration for moving drops in microfluidic devices. The final surface modification considered is the application of a thin layer of rubber to a rigid surface. While this technique has many practical uses, such as easy release coatings in marine environments, it is applied herein to enable spontaneous

  9. Star-shaped oscillations of Leidenfrost drops

    Science.gov (United States)

    Ma, Xiaolei; Liétor-Santos, Juan-José; Burton, Justin C.

    2017-03-01

    We experimentally investigate the self-sustained, star-shaped oscillations of Leidenfrost drops. The drops levitate on a cushion of evaporated vapor over a heated, curved surface. We observe modes with n =2 -13 lobes around the drop periphery. We find that the wavelength of the oscillations depends only on the capillary length of the liquid and is independent of the drop radius and substrate temperature. However, the number of observed modes depends sensitively on the liquid viscosity. The dominant frequency of pressure variations in the vapor layer is approximately twice the drop oscillation frequency, consistent with a parametric forcing mechanism. Our results show that the star-shaped oscillations are driven by capillary waves of a characteristic wavelength beneath the drop and that the waves are generated by a large shear stress at the liquid-vapor interface.

  10. Sepsis from dropped clips at laparoscopic cholecystectomy

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Sarwat E-mail: sarwathussain@hotmail.com

    2001-12-01

    We report seven patients in whom five dropped surgical clips and two gallstones were visualized in the peritoneal cavity, on radiological studies. In two, subphrenic abscesses and empyemas developed as a result of dropped clips into the peritoneal cavity during or following laparoscopic cholecystectomy. In one of these two, a clip was removed surgically from the site of an abscess. In two other patients dropped gallstones, and in three, dropped clips led to no complications. These were seen incidentally on studies done for other indications. Abdominal abscess secondary to dropped gallstones is a well-recognized complication of laparoscopic cholecystectomy (LC). We conclude that even though dropped surgical clips usually do not cause problems, they should be considered as a risk additional to other well-known causes of post-LC abdominal sepsis.

  11. Sepsis from dropped clips at laparoscopic cholecystectomy

    International Nuclear Information System (INIS)

    Hussain, Sarwat

    2001-01-01

    We report seven patients in whom five dropped surgical clips and two gallstones were visualized in the peritoneal cavity, on radiological studies. In two, subphrenic abscesses and empyemas developed as a result of dropped clips into the peritoneal cavity during or following laparoscopic cholecystectomy. In one of these two, a clip was removed surgically from the site of an abscess. In two other patients dropped gallstones, and in three, dropped clips led to no complications. These were seen incidentally on studies done for other indications. Abdominal abscess secondary to dropped gallstones is a well-recognized complication of laparoscopic cholecystectomy (LC). We conclude that even though dropped surgical clips usually do not cause problems, they should be considered as a risk additional to other well-known causes of post-LC abdominal sepsis

  12. Hydrothermal waves in evaporating sessile drops

    OpenAIRE

    Brutin, D.; Rigollet, F.; Niliot, C. Le

    2009-01-01

    Drop evaporation is a simple phenomena but still unclear concerning the mechanisms of evaporation. A common agreement of the scientific community based on experimental and numerical work evidences that most of the evaporation occurs at the triple line. However, the rate of evaporation is still empirically predicted due to the lack of knowledge on the convection cells which develop inside the drop under evaporation. The evaporation of sessile drop is more complicated than it appears due to the...

  13. Relevant time- and length scale of touch-down for drops impacting on a heated surface

    Science.gov (United States)

    van Limbeek, Michiel A. J.; Shirota, Minori; Sun, Chao; Prosperetti, Andrea; Lohse, Detlef

    2015-11-01

    The vapor generated from a liquid drop impacting a hot solid surface can prevent it to make contact, depending on the solid temperature. The minimum temperature when no contact is made between the drop and the solid is called the dynamic Leidenfrost temperature. The latent heat needed to generated the vapor is drawn from the solid, and in general the Leidenfrost temperature depends on the solid thermal properties. Here we show experiments conducted on a sapphire plate, to minimize the cooling of the solid and ensuring nearly isothermal conditions. By using high speed total internal reflection imaging, we observe the drop base during impact up to about 100nm above the substrate surface. By this technique we are able to study the processes responsible for the transition between fully wetting and fully levitating drop impact conditions as the solid temperature increases. We reveal the relevant length- and time-scales for the dimple formation under the drop and explain their relevance for the late-time dynamics. As the transition regime is traversed from low to high temperature, the liquid-solid contact gradually decreases which reduces the friction with the solid, enhancing the spreading of the drop considerably.

  14. European wet deposition maps based on measurements

    NARCIS (Netherlands)

    Leeuwen EP van; Erisman JW; Draaijers GPJ; Potma CJM; Pul WAJ van; LLO

    1995-01-01

    To date, wet deposition maps on a European scale have been based on long-range transport model results. For most components wet deposition maps based on measurements are only available on national scales. Wet deposition maps of acidifying components and base cations based on measurements are needed

  15. Soft drop jet mass measurement

    CERN Document Server

    Roloff, Jennifer Kathryn; The ATLAS collaboration

    2018-01-01

    Calculations of jet substructure observables that are accurate beyond leading-logarithm accuracy have recently become available. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This poster documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross-section is measured as a function of log( ρ^2), where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 ifb of sqrt(s) = 13 TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

  16. Finite size effects on textured surfaces: recovering contact angles from vagarious drop edges.

    Science.gov (United States)

    Gauthier, Anaïs; Rivetti, Marco; Teisseire, Jérémie; Barthel, Etienne

    2014-02-18

    A clue to understand wetting hysteresis on superhydrophobic surfaces is the relation between receding contact angle and surface textures. When the surface textures are large, there is a significant distribution of local contact angles around the drop. As seen from the cross section, the apparent contact angle oscillates as the triple line recedes. Our experiments demonstrate that the origin of these oscillations is a finite size effect. Combining side and bottom views of the drop, we take into account the 3D conformation of the surface near the edge to evaluate an intrinsic contact angle from the oscillations of the apparent contact angle. We find that for drops receding on axisymmetric textures the intrinsic receding contact angle is the minimum value of the oscillation while for a square lattice it is the maximum.

  17. Reducing the residence time of a bouncing drop with spoked macrotexture

    Science.gov (United States)

    Patterson, Colin; Bird, James

    2015-11-01

    Liquid drops can bounce when they impact non-wetting surfaces. Recently, studies have demonstrated that the time that the bouncing drop resides at the surface can be adjusted with the presence of ridged macrotextures. When non-parallel macrotextures are present, they intersect to create spoked junctions. At sufficient velocity, a drop impacting a junction might be expected to breakup into smaller droplets; yet it is unclear how many droplets would be produced and the time for these droplets to clear the surface. Here, we show that the number droplets and overall residence time depends on both the number of spokes and the Weber number. We experimentally demonstrate that the center-assisted recoil framework extends beyond superhydrophobic surfaces to those above the Leidenfrost temperature. Finally, we present a physical model that rationalizes our results.

  18. New Methods of Determining Two-Phase CO2 Relative Permeability and Temperature and Pressure Dependence of CO2 Relative Permeability in Water-Wet Rocks

    Science.gov (United States)

    Chen, X.; Kianinejad, A.; Gao, S.; DiCarlo, D. A.

    2017-12-01

    The prediction of CO2 geological sequestration requires CO2 relative permeability as a key input. However, due to the low viscosity of CO2, experimental measurements often encounter capillary end effects and give lower CO2 relative permeability data than actual values. Previous work shows that using a long core and pressure taps, capillary end effects can be minimized during steady-state CO2-brine two-phase corefloods and accurate CO2 relative permeability data can be obtained. This is achieved by using X-ray CT to measure in situ saturation profile versus time and multiple pressure transducers to measure pressure drops of individual sections. In particular, the core exit section's pressure drop is not used. Based on Buckley Leverett theory, we outline a new method to calculate in situ water fractional flows along the core using measured in situ water saturation profiles. Along with pressure drop and saturation measurements, the water fractional flows can be used to directly calculate unsteady-state CO2-brine relative permeability for each section (excluding the exit section) of the core using Darcy-Buckingham equation. On the other hand, the fractional flows, pressure drops and saturations can be used to extend the conventional JBN method to calculate unsteady-state CO2-brine relative permeability at each pressure tap locations of the core. Both unsteady-state methods give consistent CO2-brine relative permeability data with the steady-state methods and give more data points. Since the core exit section is not used, CO2 relative permeability is obtained with minimized capillary end effect. Compared with the conventional JBN, the extended JBN gives more data points and more accurate data. Furthermore, we find steady-state CO2 relative permeability does not depend on temperature or pressure within 20-60°C and 8-12 MPa in Berea sandstones. This is because CO2 is always the non-wetting phase and flowing inside pores in water-wet rocks and small changes in contact

  19. Are the Stress Drops of Small Earthquakes Good Predictors of the Stress Drops of Larger Earthquakes?

    Science.gov (United States)

    Hardebeck, J.

    2017-12-01

    Uncertainty in PSHA could be reduced through better estimates of stress drop for possible future large earthquakes. Studies of small earthquakes find spatial variability in stress drop; if large earthquakes have similar spatial patterns, their stress drops may be better predicted using the stress drops of small local events. This regionalization implies the variance with respect to the local mean stress drop may be smaller than the variance with respect to the global mean. I test this idea using the Shearer et al. (2006) stress drop catalog for M1.5-3.1 events in southern California. I apply quality control (Hauksson, 2015) and remove near-field aftershocks (Wooddell & Abrahamson, 2014). The standard deviation of the distribution of the log10 stress drop is reduced from 0.45 (factor of 3) to 0.31 (factor of 2) by normalizing each event's stress drop by the local mean. I explore whether a similar variance reduction is possible when using the Shearer catalog to predict stress drops of larger southern California events. For catalogs of moderate-sized events (e.g. Kanamori, 1993; Mayeda & Walter, 1996; Boyd, 2017), normalizing by the Shearer catalog's local mean stress drop does not reduce the standard deviation compared to the unmodified stress drops. I compile stress drops of larger events from the literature, and identify 15 M5.5-7.5 earthquakes with at least three estimates. Because of the wide range of stress drop estimates for each event, and the different techniques and assumptions, it is difficult to assign a single stress drop value to each event. Instead, I compare the distributions of stress drop estimates for pairs of events, and test whether the means of the distributions are statistically significantly different. The events divide into 3 categories: low, medium, and high stress drop, with significant differences in mean stress drop between events in the low and the high stress drop categories. I test whether the spatial patterns of the Shearer catalog

  20. Evaporation of oil-water emulsion drops when heated at high temperature

    Science.gov (United States)

    Strizhak, P. A.; Piskunov, M. V.; Kuznetsov, G. V.; Voytkov, I. S.

    2017-10-01

    An experimental study on conditions and main characteristics for high-temperature (more than 700 K) evaporation of oil-water drops is presented. The high-temperature water purification from impurities can be the main practical application of research results. Thus, the heating of drops is implemented by the two typical schemes: on a massive substrate (the heating conditions are similar to those achieved in a heating chamber) and in a flow of the heated air. In the latter case, the heating conditions correspond to those attained while moving water drops with impurities in a counter high-temperature gaseous flow in the process of water purification. Evaporation time as function of heating temperature is presented. The influence of oil product concentration in an emulsion drop on evaporation characteristics is discussed. The conditions for intensive flash boiling of an emulsion drop and its explosive breakup with formation of the fine droplets cloud are pointed out. Heat fluxes required for intensive flash boiling and explosive breakup of a drop with further formation of the fine aerosol are determined in the boundary layer of a drop. The fundamental differences between flash boiling and explosive breakup of an emulsion drop when heated on a substrate and in a flow of the heated air are described. The main prospects for the development of the high-temperature water purification technology are detailed taking into account the fast emulsion drop breakup investigated in the paper.

  1. That's one small drop for Mankind...

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    In August, the members of an ISOLDE project called LOI88 successfully employed a new technique to study the interaction of metal ions in a liquid. It’s the first time that specific ions have been studied in a liquid medium - a technical achievement that opens promising doors for biochemistry.   In the heart of the LOI88 experiment: this is the point where the metal ions (from the left) enter the drop.  “More than half of the proteins in the human body contain metal ions such as magnesium, zinc and copper,” explains Monika Stachura, a biophysicist at the University of Copenhagen and the LOI88 project leader. “We know that these elements are crucial to a protein’s structure and function but their behaviour and interactions are not known in detail.” Detecting these ions directly in  a body-like environment is problematic as their closed atomic shells make them invisible to most spectroscopic techniques. However, using ...

  2. Many Drops Make a Lake

    Directory of Open Access Journals (Sweden)

    Chaitanya S. Mudgal

    2014-03-01

    greater knowledge, better skills and disseminate this knowledge through this journal to influence as many physicians and their patients as possible. They have taken the knowledge of their teachers, recognized their giants and are now poised to see further than ever before. My grandmother often used to quote to me a proverb from India, which when translated literally means “Many drops make a lake”. I cannot help but be amazed by the striking similarities between the words of Newton and this Indian saying. Therefore, while it may seem intuitive, I think it must be stated that it is vital for the betterment of all our patients that we recognize our own personal lakes to put our drops of knowledge into. More important is that we recognize that it is incumbent upon each and every one of us to contribute to our collective lakes of knowledge such as ABJS. And finally and perhaps most importantly we need to be utterly cognizant of never letting such lakes of knowledge run dry.... ever.

  3. Drop Impact on Superheated Surfaces

    NARCIS (Netherlands)

    Tran, Tuan; Staat, Erik-Jan; Prosperetti, Andrea; Sun, Chao; Lohse, Detlef

    2012-01-01

    At the impact of a liquid droplet on a smooth surface heated above the liquid’s boiling point, the droplet either immediately boils when it contacts the surface (“contact boiling”), or without any surface contact forms a Leidenfrost vapor layer towards the hot surface and bounces back (“gentle film

  4. Improved hydrogen sorption kinetics in wet ball milled Mg hydrides

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Li

    2011-05-04

    In this work, wet ball milling method is used in order to improve hydrogen sorption behaviour due to its improved microstructure of solid hydrogen materials. Compared to traditional ball milling method, wet ball milling has benefits on improvement of MgH{sub 2} microstructure and further influences on its hydrogen sorption behavior. With the help of solvent tetrahydrofuran (THF), wet ball milled MgH{sub 2} powder has much smaller particle size and its specific surface area is 7 times as large as that of dry ball milled MgH{sub 2} powder. Although after ball milling the grain size is decreased a lot compared to as-received MgH{sub 2} powder, the grain size of wet ball milled MgH{sub 2} powder is larger than that of dry ball milled MgH{sub 2} powder due to the lubricant effect of solvent THF during wet ball milling. The improved particle size and specific surface area of wet ball milled MgH{sub 2} powder is found to be determining its hydrogen sorption kinetics especially at relatively low temperatures. And it also shows good cycling sorption behavior, which decides on its industrial applicability. With three different catalysts MgH{sub 2} powder shows improved hydrogen sorption behavior as well as the cyclic sorption behavior. Among them, the Nb{sub 2}O{sub 5} catalyst is found to be the most effective one in this work. Compared to the wet ball milled MgH{sub 2} powder, the particle size and specific surface area of the MgH{sub 2} powder with catalysts are similar to the previous ones, while the grain size of the MgH{sub 2} with catalysts is much finer. In this case, two reasons for hydrogen sorption improvement are suggested: one is the reduction of the grain size. The other may be as pointed out in some literatures that formation of new oxidation could enhance the hydrogen sorption kinetics, which is also the reason why its hydrogen capacity is decreased compared to without catalysts. After further ball milling, the specific surface area of wet ball milled Mg

  5. WET SOLIDS FLOW ENHANCEMENT; SEMIANNUAL

    International Nuclear Information System (INIS)

    Hugo S. Caram; Natalie Foster

    1997-01-01

    The objective was to visualize the flow of granular materials in flat bottomed silo. This was done by for dry materials introducing mustard seeds and poppy seeds as tracer particles and imaging them using Nuclear Magnetic Resonance. The region sampled was a cylinder 25 mm in diameter and 40 mm in length. Eight slices containing 128*128 to 256*256 pixels were generated for each image. The size of the silo was limited by the size of the high resolution NMR imager available. Cross-sections of 150mm flat bottomed silos, with the tracer layers immobilized by a gel, showed similar qualitative patterns for both dry and wet granular solids

  6. Drop test facility available to private industry

    International Nuclear Information System (INIS)

    Shappert, L.B.; Box, W.D.

    1983-01-01

    In 1978, a virtually unyielding drop test impact pad was constructed at Oak Ridge National Laboratory's (ORNL's) Tower Shielding Facility (TSF) for the testing of heavy shipping containers designed for transporting radioactive materials. Because of the facility's unique capability for drop-testing large, massive shipping packages, it has been identified as a facility which can be made available for non-DOE users

  7. Total Site Heat Integration Considering Pressure Drops

    Directory of Open Access Journals (Sweden)

    Kew Hong Chew

    2015-02-01

    Full Text Available Pressure drop is an important consideration in Total Site Heat Integration (TSHI. This is due to the typically large distances between the different plants and the flow across plant elevations and equipment, including heat exchangers. Failure to consider pressure drop during utility targeting and heat exchanger network (HEN synthesis may, at best, lead to optimistic energy targets, and at worst, an inoperable system if the pumps or compressors cannot overcome the actual pressure drop. Most studies have addressed the pressure drop factor in terms of pumping cost, forbidden matches or allowable pressure drop constraints in the optimisation of HEN. This study looks at the implication of pressure drop in the context of a Total Site. The graphical Pinch-based TSHI methodology is extended to consider the pressure drop factor during the minimum energy requirement (MER targeting stage. The improved methodology provides a more realistic estimation of the MER targets and valuable insights for the implementation of the TSHI design. In the case study, when pressure drop in the steam distribution networks is considered, the heating and cooling duties increase by 14.5% and 4.5%.

  8. Breakfast patterns of frozen impacted drops

    Science.gov (United States)

    Thievenaz, Virgile; Josserand, Christophe; Seon, Thomas

    2017-11-01

    We investigate experimentally the solidification of a water drop during its impact on a sub-zero cooled metallic plate. As the drop impacts the substrate, a first thin layer of ice builds-up in the briefest moment. Afterwards, the competition between the liquid solidification and its retraction on this ice layer leads to a variety of frozen drop patterns. Typically, with a change of temperature the drop can freeze into a fried egg or a doughnut shape. These frozen motifs experience different sizes and can even disappear so only the thin pancake remains. These patterns have been explored through a range of parameters such as : plate temperature, thermal properties, drop size and impact velocity. Phase-diagrams show the range and the transition temperatures between the different patterns as a function of those parameters. The experimental results are discussed using a scaling law approach, allowing basic understanding of the underlying physics.

  9. 40 CFR 425.30 - Applicability; description of the hair save or pulp, non-chrome tan, retan-wet finish subcategory.

    Science.gov (United States)

    2010-07-01

    ... save or pulp, non-chrome tan, retan-wet finish subcategory. 425.30 Section 425.30 Protection of... FINISHING POINT SOURCE CATEGORY Hair Save or Pulp, Non-Chrome Tan, Retan-Wet Finish Subcategory § 425.30 Applicability; description of the hair save or pulp, non-chrome tan, retan-wet finish subcategory. The...

  10. Elucidating the mysteries of wetting.

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Edmund Blackburn, III (,; ); Bourdon, Christopher Jay; Grillet, Anne Mary; Sackinger, Philip A.; Grest, Gary Stephen; Emerson, John Allen; Ash, Benjamin Jesse; Heine, David R.; Brooks, Carlton, F.; Gorby, Allen D.

    2005-11-01

    Nearly every manufacturing and many technologies central to Sandia's business involve physical processes controlled by interfacial wetting. Interfacial forces, e.g. conjoining/disjoining pressure, electrostatics, and capillary condensation, are ubiquitous and can surpass and even dominate bulk inertial or viscous effects on a continuum level. Moreover, the statics and dynamics of three-phase contact lines exhibit a wide range of complex behavior, such as contact angle hysteresis due to surface roughness, surface reaction, or compositional heterogeneities. These thermodynamically and kinetically driven interactions are essential to the development of new materials and processes. A detailed understanding was developed for the factors controlling wettability in multicomponent systems from computational modeling tools, and experimental diagnostics for systems, and processes dominated by interfacial effects. Wettability probed by dynamic advancing and receding contact angle measurements, ellipsometry, and direct determination of the capillary and disjoining forces. Molecular scale experiments determined the relationships between the fundamental interactions between molecular species and with the substrate. Atomistic simulations studied the equilibrium concentration profiles near the solid and vapor interfaces and tested the basic assumptions used in the continuum approaches. These simulations provide guidance in developing constitutive equations, which more accurately take into account the effects of surface induced phase separation and concentration gradients near the three-phase contact line. The development of these accurate models for dynamic multicomponent wetting allows improvement in science based engineering of manufacturing processes previously developed through costly trial and error by varying material formulation and geometry modification.

  11. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    Science.gov (United States)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen; Sun, Wenjing

    2015-01-01

    In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C1/C2 ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood.

  12. Drop impact splashing and air entrapment

    KAUST Repository

    Thoraval, Marie-Jean

    2013-03-01

    Drop impact is a canonical problem in fluid mechanics, with numerous applications in industrial as well as natural phenomena. The extremely simple initial configuration of the experiment can produce a very large variety of fast and complex dynamics. Scientific progress was made in parallel with major improvements in imaging and computational technologies. Most recently, high-speed imaging video cameras have opened the exploration of new phenomena occurring at the micro-second scale, and parallel computing allowed realistic direct numerical simulations of drop impacts. We combine these tools to bring a new understanding of two fundamental aspects of drop impacts: splashing and air entrapment. The early dynamics of a drop impacting on a liquid pool at high velocity produces an ejecta sheet, emerging horizontally in the neck between the drop and the pool. We show how the interaction of this thin liquid sheet with the air, the drop or the pool, can produce micro-droplets and bubble rings. Then we detail how the breakup of the air film stretched between the drop and the pool for lower impact velocities can produce a myriad of micro-bubbles.

  13. Wetting on micro-structured surfaces: modelling and optimization

    DEFF Research Database (Denmark)

    Cavalli, Andrea

    The present thesis deals with the wetting of micro-structured surfaces by various fluids, and its goal is to elucidate different aspects of this complex interaction. In this work we address some of the most relevant topics in this field such as superhydrophobicity, oleophobicity, unidirectional......-off angles. Such behaviour arises when drops are suspended on a micron or submicron texture, so that their contact with the substrate is minute. This suspended state (known as Cassie-Baxter state) is however prone to failure if the liquid-air interface is perturbed, a common situation in real life...... circumstances. We apply the numerical method of Topology Optimization to this problem, in order to find the optimal texture to support the superhydrophobic configuration. Our optimization provides designs which are consistent with strategies employed by Nature to achieve the same effect. Furthermore, our...

  14. Initial Electrospreading of Aqueous Electrolyte Drops

    Science.gov (United States)

    Chen, Longquan; Li, Chunli; van der Vegt, Nico F. A.; Auernhammer, Günter K.; Bonaccurso, Elmar

    2013-01-01

    The early spreading of a liquid drop on a solid surface driven by inertial, capillary, and electrostatic forces is of fundamental interest, since most commonly used surfaces are (naturally) charged. We studied the effect of applying an electric potential between a drop and a surface on the early spreading of aqueous electrolyte drops. We found that spreading dynamics not only depended on the potential, but also on the electrolyte concentration. Based on molecular dynamics simulations of the ion distribution in spreading nanodrops under an applied potential, we propose a simple model to explain the relation between applied potential, electrolyte concentration, and early spreading dynamics.

  15. Wet motor geroter fuel pump

    Energy Technology Data Exchange (ETDEWEB)

    Wiernicki, M.V.

    1987-05-05

    This patent describes a wet motor gerotor fuel pump for pumping fuel from a fuel source to an internal combustion which consists of: gerotor pump means comprising an inner pump gear, an outer pump gear, and second tang means located on one of the inner and outer pump gears. The second tang means further extends in a second radial direction radially offset from the first radial direction and forms a driving connection with the first tang means such that the fuel pump pumps fuel from the fuel source into the narrow conduit inlet chamber, through the gerotor pump means past the electric motor means into the outlet housing means substantially along the flow axis to the internal combustion engine.

  16. Directional Transport of a Liquid Drop between Parallel-Nonparallel Combinative Plates.

    Science.gov (United States)

    Huang, Yao; Hu, Liang; Chen, Wenyu; Fu, Xin; Ruan, Xiaodong; Xie, Haibo

    2018-04-17

    Liquids confined between two parallel plates can perform the function of transmission, support, or lubrication in many practical applications, due to which to maintain liquids stable within their working area is very important. However, instabilities may lead to the formation of leaking drops outside the bulk liquid, thus it is necessary to transport the detached drops back without overstepping the working area and causing destructive leakage to the system. In this study, we report a novel and facile method to solve this problem by introducing the wedgelike geometry into the parallel gap to form a parallel-nonparallel combinative construction. Transport performances of this structure were investigated. The criterion for self-propelled motion was established, which seemed more difficult to meet than that in the nonparallel gap. Then, we performed a more detailed investigation into the drop dynamics under squeezing and relaxing modes because the drops can surely return in hydrophilic combinative gaps, whereas uncertainties arose in gaps with a weak hydrophobic character. Therefore, through exploration of the transition mechanism of the drop motion state, a crucial factor named turning point was discovered and supposed to be directly related to the final state of the drops. On the basis of the theoretical model of turning point, the criterion to identify whether a liquid drop returns to the parallel part under squeezing and relaxing modes was achieved. These criteria can provide guidance on parameter selection and structural optimization for the combinative gap, so that the destructive leakage in practical productions can be avoided.

  17. Drop impact on superheated surfaces.

    Science.gov (United States)

    Tran, Tuan; Staat, Hendrik J J; Prosperetti, Andrea; Sun, Chao; Lohse, Detlef

    2012-01-20

    At the impact of a liquid droplet on a smooth surface heated above the liquid's boiling point, the droplet either immediately boils when it contacts the surface ("contact boiling"), or without any surface contact forms a Leidenfrost vapor layer towards the hot surface and bounces back ("gentle film boiling"), or both forms the Leidenfrost layer and ejects tiny droplets upward ("spraying film boiling"). We experimentally determine conditions under which impact behaviors in each regime can be realized. We show that the dimensionless maximum spreading γ of impacting droplets on the heated surfaces in both gentle and spraying film boiling regimes shows a universal scaling with the Weber number We (γ~We(2/5)), which is much steeper than for the impact on nonheated (hydrophilic or hydrophobic) surfaces (γ~We(1/4)). We also interferometrically measure the vapor thickness under the droplet. © 2012 American Physical Society

  18. Triple-line behavior and wettability controlled by nanocoated substrates: influence on sessile drop evaporation.

    Science.gov (United States)

    Sobac, B; Brutin, D

    2011-12-20

    In this article, we investigate the influence of the surface properties of substrates on the evaporation process. Using various nanocoatings, it is possible to modify the surface properties of substrates, such as the roughness and the surface energy, while maintaining constant thermal properties. Experiments are conducted under atmospheric conditions with five fluids (methanol, ethanol, propanol, toluene and water) and four coatings (PFC, PTFE, SiOC, and SiO(x)). The various combinations of these fluids and coatings allow for a wide range of drop evaporation properties to be studied: the dynamics of the triple line, the volatility of fluids, and a large range of wettabilities (from 17 to 135°). The experimental data are in very good quantitative agreement with existing models of quasi-steady, diffusion-driven evaporation. The experimental results show that the dynamics of the evaporative rate are proportional to the dynamics of the wetting radius. Thus, the models succeed in describing the evaporative dynamics throughout the evaporation process regardless of the behavior of the triple line. Moreover, the use of various liquids reveals the validity of the models regardless of their volatility. The results also confirm the recent finding of a universal relation for the time evolution of the drop mass, independent of the drop size and initial contact angle. Finally, this study highlights the separate and coupled roles of the triple line and the wettability on the sessile drop evaporation process. Data reveal that the more wet and pinned a drop, the shorter the evaporation time. © 2011 American Chemical Society

  19. Carbon nanotube fiber spun from wetted ribbon

    Science.gov (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  20. Micro-splashing by drop impacts

    KAUST Repository

    Thoroddsen, Sigurdur T.

    2012-07-18

    We use ultra-high-speed video imaging to observe directly the earliest onset of prompt splashing when a drop impacts onto a smooth solid surface. We capture the start of the ejecta sheet travelling along the solid substrate and show how it breaks up immediately upon emergence from the underneath the drop. The resulting micro-droplets are much smaller and faster than previously reported and may have gone unobserved owing to their very small size and rapid ejection velocities, which approach 100 m s-1, for typical impact conditions of large rain drops. We propose a phenomenological mechanism which predicts the velocity and size distribution of the resulting microdroplets. We also observe azimuthal undulations which may help promote the earliest breakup of the ejecta. This instability occurs in the cusp in the free surface where the drop surface meets the radially ejected liquid sheet. © 2012 Cambridge University Press.

  1. Blood drop patterns: Formation and applications.

    Science.gov (United States)

    Chen, Ruoyang; Zhang, Liyuan; Zang, Duyang; Shen, Wei

    2016-05-01

    The drying of a drop of blood or plasma on a solid substrate leads to the formation of interesting and complex patterns. Inter- and intra-cellular and macromolecular interactions in the drying plasma or blood drop are responsible for the final morphologies of the dried patterns. Changes in these cellular and macromolecular components in blood caused by diseases have been suspected to cause changes in the dried drop patterns of plasma and whole blood, which could be used as simple diagnostic tools to identify the health of humans and livestock. However, complex physicochemical driving forces involved in the pattern formation are not fully understood. This review focuses on the scientific development in microscopic observations and pattern interpretation of dried plasma and whole blood samples, as well as the diagnostic applications of pattern analysis. Dried drop patterns of plasma consist of intricate visible cracks in the outer region and fine structures in the central region, which are mainly influenced by the presence and concentration of inorganic salts and proteins during drying. The shrinkage of macromolecular gel and its adhesion to the substrate surface have been thought to be responsible for the formation of the cracks. Dried drop patterns of whole blood have three characteristic zones; their formation as functions of drying time has been reported in the literature. Some research works have applied engineering treatment to the evaporation process of whole blood samples. The sensitivities of the resultant patterns to the relative humidity of the environment, the wettability of the substrates, and the size of the drop have been reported. These research works shed light on the mechanisms of spreading, evaporation, gelation, and crack formation of the blood drops on solid substrates, as well as on the potential applications of dried drop patterns of plasma and whole blood in diagnosis. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  2. Pressure drop in flashing flow through obstructions

    International Nuclear Information System (INIS)

    Weinle, M.E.; Johnston, B.S.

    1985-01-01

    An experiment was designed to investigate the pressure drop for flashing flow across obstructions of different geometries at various flow rates. Tests were run using two different orifices to determine if the two-phase pressure drop could be characterized by the single phase loss coefficient and the general behavior of the two-phase multiplier. For the geometries studied, it was possible to correlate the multiplier in a geometry-independent fashion

  3. Tipping Point

    Medline Plus

    Full Text Available ... en español Blog About OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point The Tipping Point by ... danger death electrical fall furniture head injury product safety television tipover tv Watch the video in Adobe ...

  4. Static and Dynamic Wetting Behavior of Triglycerides on Solid Surfaces.

    Science.gov (United States)

    Michalski; Saramago

    2000-07-15

    Triglyceride wetting properties on solid surfaces of different hydro-phobicities were investigated using three different methods, namely, the sessile drop method for static contact angle measurements, the Wilhelmy method for dynamic contact angle measurements, and the captive bubble method to investigate thin triglyceride film stability. For solid surfaces having a surface free energy higher than the surface tension of triglycerides (tributyrin, tricaprylin, and triolein), a qualitative correlation was observed between wetting and solid/triglyceride relative hydrophobicities. On surfaces presenting extreme hydrophobic or hydrophilic properties, medium-chain triglycerides had a behavior similar to that of long-chain unsaturated ones. On a high-energy surface (glass), tricaprylin showed an autophobic effect subsequent to molecular adsorption in trident conformation on the solid, observed with the three methods. Thin triglyceride films between an air bubble and a solid surface were stable for a short time, for solids with a surface free energy larger than the triglyceride surface tension. If the solid surface had a lower surface free energy, the thin film collapsed after a time interval which increased with triglyceride viscosity. Copyright 2000 Academic Press.

  5. Transmission studies involving a wet fowl pox isolate.

    Science.gov (United States)

    Eleazer, T H; Harrell, J S; Blalock, H G

    1983-01-01

    An isolate of fowl pox (FP) virus from a case of "wet" pox in commercial white leghorn (WL) pullets was used to expose WL cockerels via the comb-scratch (CS), eye-drop (ED), or laryngeal-swab (LS) route. Seven days postinoculation (PI), the groups challenged via CS had scabby proliferative pox lesions at the challenge site, the groups challenged via LS had slight dyspnea and rales, and 20% of the cockerels challenged via ED had mild conjunctivitis and lacrimation. By termination of the trial on day 21 PI, the CS-challenged groups had developed pronounced pox lesions. The LS-challenged groups showed severe dyspnea and rales with pronounced raised plaque-like lesions at the opening to the trachea and extending into the upper quarter of the trachea with heavy yellowish caseous exudate partly occluding the glottis. The ED-challenged groups had severe lacrimation and conjunctivitis and small pox lesions on the face, comb, and wattles; 12 of 18 had proliferative lesions on the oral mucosa in the area of the larynx. Forty-five percent of the LS-challenged groups died of suffocation. Pox virus was re-isolated from tissues in all treatment groups. Wet pox transmission appears to be possible via the LS and ED routes.

  6. Contact angles of wetting and water stability of soil structure

    Science.gov (United States)

    Kholodov, V. A.; Yaroslavtseva, N. V.; Yashin, M. A.; Frid, A. S.; Lazarev, V. I.; Tyugai, Z. N.; Milanovskiy, E. Yu.

    2015-06-01

    From the soddy-podzolic soils and typical chernozems of different texture and land use, dry 3-1 mm aggregates were isolated and sieved in water. As a result, water-stable aggregates and water-unstable particles composing dry 3-1 mm aggregates were obtained. These preparations were ground, and contact angles of wetting were determined by the static sessile drop method. The angles varied from 11° to 85°. In most cases, the values of the angles for the water-stable aggregates significantly exceeded those for the water-unstable components. In terms of carbon content in structural units, there was no correlation between these parameters. When analyzing the soil varieties separately, the significant positive correlation between the carbon content and contact angle of aggregates was revealed only for the loamy-clayey typical chernozem. Based on the multivariate analysis of variance, the value of contact wetting angle was shown to be determined by the structural units belonging to water-stable or water-unstable components of macroaggregates and by the land use type. In addition, along with these parameters, the texture has an indirect effect.

  7. Calculation of Water Drop Trajectories to and About Arbitrary Three-Dimensional Bodies in Potential Airflow

    Science.gov (United States)

    Norment, H. G.

    1980-01-01

    Calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Any subsonic, external, non-lifting flow can be accommodated; flow into, but not through, inlets also can be simulated. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Seven codes are described: (1) a code used to debug and plot body surface description data; (2) a code that processes the body surface data to yield the potential flow field; (3) a code that computes flow velocities at arrays of points in space; (4) a code that computes water drop trajectories from an array of points in space; (5) a code that computes water drop trajectories and fluxes to arbitrary target points; (6) a code that computes water drop trajectories tangent to the body; and (7) a code that produces stereo pair plots which include both the body and trajectories. Code descriptions include operating instructions, card inputs and printouts for example problems, and listing of the FORTRAN codes. Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.

  8. Electromagnetic radiation from linearly and nonlinearly oscillating charge drops

    Science.gov (United States)

    Grigor'ev, A. I.; Shiryaeva, S. O.

    2016-12-01

    It has been shown that analytic calculations of the intensity of electromagnetic radiation from an oscillating charged drop in the approximation linear in the oscillation amplitude (small parameter is on the order of 0.1) give only the quadrupole component of the total radiation. The dipole component can only be obtained in calculations using higher-order approximations. Nevertheless, the intensity of the dipole radiation turns out to be substantially higher (by 14-15 orders of magnitude). This is because the decomposition of radiation from a system of charges into multipole components (differing even in the rates of decrease in the potential with the distance) is carried out using the expansion in a substantially smaller parameter, viz., the ratio of the size of the emitting system (in our case, a drop of radius 10 μm) to the distance to the point of observation in the wave zone of the emission of radiation (emitted wavelength) of 100-1000 m. As a result, this second small parameter is on the order of 10-7 to 10-8. On the other hand, in accordance with the field theory, the ratio of intensities of quadrupole and dipole radiations is proportional to the squared ratio of the hydrodynamic velocity of the oscillating surface of a charged drop to the velocity of propagation of an electromagnetic signal in vacuum (velocity of light), which yields a ratio of 10-14 to 10-15.

  9. Application of Hanging Drop Technique for Kidney Tissue Culture.

    Science.gov (United States)

    Wang, Shaohui; Wang, Ximing; Boone, Jasmine; Wie, Jin; Yip, Kay-Pong; Zhang, Jie; Wang, Lei; Liu, Ruisheng

    2017-01-01

    The hanging drop technique is a well-established method used in culture of animal tissues. However, this method has not been used in adult kidney tissue culture yet. This study was to explore the feasibility of using this technique for culturing adult kidney cortex to study the time course of RNA viability in the tubules and vasculature, as well as the tissue structural integrity. In each Petri dish with the plate covered with sterile buffer, a section of mouse renal cortex was cultured within a drop of DMEM culture medium on the inner surface of the lip facing downward. The tissue were then harvested at each specific time points for Real-time PCR analysis and histological studies. The results showed that the mRNA level of most Na+ related transporters and cotransporters were stably maintained within 6 hours in culture, and that the mRNA level of most receptors found in the vasculature and glomeruli were stably maintained for up to 9 days in culture. Paraffin sections of the cultured renal cortex indicated that the tubules began to lose tubular integrity after 6 hours, but the glomeruli and vasculatures were still recognizable up to 9 days in culture. We concluded that adult kidney tissue culture by hanging drop method can be used to study gene expressions in vasculature and glomeruli. © 2017 The Author(s). Published by S. Karger AG, Basel.

  10. Characteristics of wet work in nurses

    NARCIS (Netherlands)

    Jungbauer, FHW; Steenstra, FB; Groothoff, JW; Coenraads, PJ

    Background objectives: Nursing is known for its high prevalence of hand dermatitis, mainly caused by the intense exposure to wet work in nursing activities. We aimed to study the characteristics of wet work exposure in nursing. Method: Trained observers monitored the duration and frequency of

  11. Defined wetting properties of optical surfaces

    Science.gov (United States)

    Felde, Nadja; Coriand, Luisa; Schröder, Sven; Duparré, Angela; Tünnermann, Andreas

    2017-10-01

    Optical surfaces equipped with specific functional properties have attracted increasing importance over the last decades. In the light of cost reduction, hydrophobic self-cleaning behavior is aspired. On the other side, hydrophilic properties are interesting due to their anti-fog effect. It has become well known that such wetting states are significantly affected by the surface morphology. For optical surfaces, however, this fact poses a problem, as surface roughness can induce light scattering. The generation of optical surfaces with specific wetting properties, hence, requires a profound understanding of the relation between the wetting and the structural surface properties. Thus, our work concentrates on a reliable acquisition of roughness data over a wide spatial frequency range as well as on the comprehensive description of the wetting states, which is needed for the establishment of such correlations. We will present our advanced wetting analysis for nanorough optical surfaces, extended by a vibration-based procedure, which is mainly for understanding and tailoring the wetting behavior of various solid-liquid systems in research and industry. Utilizing the relationships between surface roughness and wetting, it will be demonstrated how different wetting states for hydrophobicity and hydrophilicity can be realized on optical surfaces with minimized scatter losses.

  12. Leaf Wetness within a Lily Canopy

    NARCIS (Netherlands)

    Jacobs, A.F.G.; Heusinkveld, B.G.; Klok, E.J.

    2005-01-01

    A wetness duration experiment was carried out within a lily field situated adjacent to coastal dunes in the Netherlands. A within-canopy model was applied to simulate leaf wetness in three layers, with equal leaf area indices, within the canopy. This simulation model is an extension of an existing

  13. Ovine wet carcass syndrome of unknown aetiology

    African Journals Online (AJOL)

    A condition of unknown aetiology, known as 'the wet sheep carcass syndrome' has led to the loss of about ... aetiology. Introduction. Wet sheep carcasses were seen with increasing frequency at abattoirs from January 1981. ... the holding pens, and transport stress. In the high incidence area (see Figure 1), feeding systems.

  14. Curvature controlled wetting in two dimensions

    DEFF Research Database (Denmark)

    Gil, Tamir; Mikheev, Lev V.

    1995-01-01

    . As the radius of the substrate r0→∞, the leading effect of the curvature is adding the Laplace pressure ΠL∝r0-1 to the pressure balance in the film. At temperatures and pressures under which the wetting is complete in planar geometry, Laplace pressure suppresses divergence of the mean thickness of the wetting...

  15. The Drop Tower Bremen -Experiment Operation

    Science.gov (United States)

    Könemann, Thorben; von Kampen, Peter; Rath, Hans J.

    The idea behind the drop tower facility of the Center of Applied Space Technology and Micro-gravity (ZARM) in Bremen is to provide an inimitable technical opportunity of a daily access to short-term weightlessness on earth. In this way ZARM`s european unique ground-based microgravity laboratory displays an excellent economic alternative for research in space-related conditions at low costs comparable to orbital platforms. Many national and international ex-perimentalists motivated by these prospects decide to benefit from the high-quality and easy accessible microgravity environment only provided by the Drop Tower Bremen. Corresponding experiments in reduced gravity could open new perspectives of investigation methods and give scientists an impressive potential for a future technology and multidisciplinary applications on different research fields like Fundamental Physics, Astrophysics, Fluid Dynamics, Combus-tion, Material Science, Chemistry and Biology. Generally, realizing microgravity experiments at ZARM`s drop tower facility meet new requirements of the experimental hardware and may lead to some technical constraints in the setups. In any case the ZARM Drop Tower Operation and Service Company (ZARM FAB mbH) maintaining the drop tower facility is prepared to as-sist experimentalists by offering own air-conditioned laboratories, clean rooms, workshops and consulting engineers, as well as scientific personal. Furthermore, ZARM`s on-site apartment can be used for accommodations during the experiment campaigns. In terms of approaching drop tower experimenting, consulting of experimentalists is mandatory to successfully accomplish the pursued drop or catapult capsule experiment. For this purpose there will be a lot of expertise and help given by ZARM FAB mbH in strong cooperation to-gether with the experimentalists. However, in comparison to standard laboratory setups the drop or catapult capsule setup seems to be completely different at first view. While defining a

  16. Study of eye drops dispensing and dose variability by using plastic dropper tips.

    Science.gov (United States)

    Sklubalová, Zdenka; Zatloukal, Zdenek

    2006-02-01

    The application of eye drops from flexible dropper bottles fitted with different types of dropper tips is associated with the high variability of eye drop weights. The aim of this report was to investigate the simultaneous effect of three factors influencing the mean weight of drops dispensing from two plastic dropper tips. Using a designed experiment (Box-Behnken), the effect of the concentration of benzalkonium chloride solutions (BAC) in the range of 0-0.02%, the dispensing angle from 90 degrees to 30 degrees from horizontal, and the residual volume of liquid in the dropper bottle from 4 to 10 mL on the mean drop weights were examined. The significant effect of the increase in BAC concentration resulted in a linear decrease in drop weights for both of the dropper tips investigated. The significant effect of the dispensing angle was influenced by the dropper tip design. For the dropper tip A, the effect of the dropper tip tilt was described by the quadratic equation with a minimum, which corresponded to the dispensing angle equal to that of 48 degrees from horizontal. Below this angle, the increase in drop weights occurred due to the drop formation from the wetted external surface of the tip orifice. The linear decrease in drop weights in response to the decrease in dispensing angle was detected for the dropper tip B. The regression equations and the contour line plots obtained allowed the drop weights to be estimated for the actual combinations of both the BAC concentration and the dispensing angle. The effect of the residual volume was found to be non-significant. Based on the formula of Tate's law, the direct proportion between surface tension of a solution and the radius of the effective perimeter of a dropper tip can be used to estimate the theoretical maximal weight of drops at the dispensing angle of 90 degrees . Using the stalagmometric values of surface tension of the BAC solutions, the maximal drop weights were estimated for both of the dropper tips

  17. [Optimize dropping process of Ginkgo biloba dropping pills by using design space approach].

    Science.gov (United States)

    Shen, Ji-Chen; Wang, Qing-Qing; Chen, An; Pan, Fang-Lai; Gong, Xing-Chu; Qu, Hai-Bin

    2017-07-01

    In this paper, a design space approach was applied to optimize the dropping process of Ginkgo biloba dropping pills. Firstly, potential critical process parameters and potential process critical quality attributes were determined through literature research and pre-experiments. Secondly, experiments were carried out according to Box-Behnken design. Then the critical process parameters and critical quality attributes were determined based on the experimental results. Thirdly, second-order polynomial models were used to describe the quantitative relationships between critical process parameters and critical quality attributes. Finally, a probability-based design space was calculated and verified. The verification results showed that efficient production of Ginkgo biloba dropping pills can be guaranteed by operating within the design space parameters. The recommended operation ranges for the critical dropping process parameters of Ginkgo biloba dropping pills were as follows: dropping distance of 5.5-6.7 cm, and dropping speed of 59-60 drops per minute, providing a reference for industrial production of Ginkgo biloba dropping pills. Copyright© by the Chinese Pharmaceutical Association.

  18. Stress Drops for Potentially Induced Earthquake Sequences

    Science.gov (United States)

    Huang, Y.; Beroza, G. C.; Ellsworth, W. L.

    2015-12-01

    Stress drop, the difference between shear stress acting across a fault before and after an earthquake, is a fundamental parameter of the earthquake source process and the generation of strong ground motions. Higher stress drops usually lead to more high-frequency ground motions. Hough [2014 and 2015] observed low intensities in "Did You Feel It?" data for injection-induced earthquakes, and interpreted them to be a result of low stress drops. It is also possible that the low recorded intensities could be a result of propagation effects. Atkinson et al. [2015] show that the shallow depth of injection-induced earthquakes can lead to a lack of high-frequency ground motion as well. We apply the spectral ratio method of Imanishi and Ellsworth [2006] to analyze stress drops of injection-induced earthquakes, using smaller earthquakes with similar waveforms as empirical Green's functions (eGfs). Both the effects of path and linear site response should be cancelled out through the spectral ratio analysis. We apply this technique to the Guy-Greenbrier earthquake sequence in central Arkansas. The earthquakes migrated along the Guy-Greenbrier Fault while nearby injection wells were operating in 2010-2011. Huang and Beroza [GRL, 2015] improved the magnitude of completeness to about -1 using template matching and found that the earthquakes deviated from Gutenberg-Richter statistics during the operation of nearby injection wells. We identify 49 clusters of highly similar events in the Huang and Beroza [2015] catalog and calculate stress drops using the source model described in Imanishi and Ellsworth [2006]. Our results suggest that stress drops of the Guy-Greenbrier sequence are similar to tectonic earthquakes at Parkfield, California (the attached figure). We will also present stress drop analysis of other suspected induced earthquake sequences using the same method.

  19. Long term wet spent nuclear fuel storage

    International Nuclear Information System (INIS)

    1987-04-01

    The meeting showed that there is continuing confidence in the use of wet storage for spent nuclear fuel and that long-term wet storage of fuel clad in zirconium alloys can be readily achieved. The importance of maintaining good water chemistry has been identified. The long-term wet storage behaviour of sensitized stainless steel clad fuel involves, as yet, some uncertainties. However, great reliance will be placed on long-term wet storage of spent fuel into the future. The following topics were treated to some extent: Oxidation of the external surface of fuel clad, rod consolidation, radiation protection, optimum methods of treating spent fuel storage water, physical radiation effects, and the behaviour of spent fuel assemblies of long-term wet storage conditions. A number of papers on national experience are included

  20. Observation of nonlinear sloshing induced by wetting dynamics

    Science.gov (United States)

    Michel, Guillaume; Pétrélis, François; Fauve, Stéphan

    2017-02-01

    Back-and-forth oscillations of a container filled with fluid often result in spilling as the gravest mode gets excited, a well-known phenomenon experienced in everyday life and of particular importance in industry. Our understanding of sloshing is largely restricted to linear response, and existing extensions mostly focus on nonlinear coupling between modes. Linear theory is expected to correctly model the dynamics of the system as long as the amplitude of the mode remains small compared to another length scale, so far unknown. Using a fluid in the vicinity of its critical point, we demonstrate that in perfect wetting this length scale is neither the wavelength nor the capillary length but a much shorter one, the thickness of the boundary layer. Above this crossover length scale, the resonance frequency remains roughly constant while dissipation significantly increases. We also show that dynamical wetting is involved in both linear and nonlinear dissipative processes.

  1. Comparison of Wet and Dry Grinding in Electromagnetic Mill

    Directory of Open Access Journals (Sweden)

    Szymon Ogonowski

    2018-03-01

    Full Text Available Comparison of dry and wet grinding process in an electromagnetic mill is presented in this paper. The research was conducted in a batch copper ore grinding. Batch mode allows for precise parametrization and constant repetitive conditions of the experiments. The following key aspects were tested: processing time, feed size, size of the grinding media, mass of the material and graining media, and density of the pulp. The particles size distribution of the product samples was analyzed in the laboratory after each experiment. The paper discusses the experimental results as well as the concept of dry and wet grinding and classification circuits for the electromagnetic mill. The main points of the discussion are the size reduction effectiveness and power consumption of the entire system.

  2. Thermal activation of superheated lipid-coated perfluorocarbon drops.

    Science.gov (United States)

    Mountford, Paul A; Thomas, Alec N; Borden, Mark A

    2015-04-28

    This study explored the thermal conditions necessary for the vaporization of superheated perfluorocarbon nanodrops. Droplets C3F8 and C4F10 coated with a homologous series of saturated diacylphosphatidylcholines were formed by condensation of 4 μm diameter microbubbles. These drops were stable at room temperature and atmospheric pressure, but they vaporized back into microbubbles at higher temperatures. The vaporization transition was measured as a function of temperature by laser light extinction. We found that C3F8 and C4F10 drops experienced 90% vaporization at 40 and 75 °C, respectively, near the theoretical superheat limits (80-90% of the critical temperature). We therefore conclude that the metastabilty of these phase-change agents arises not from the droplet Laplace pressure altering the boiling point, as previously reported, but from the metastability of the pure superheated fluid to homogeneous nucleation. The rate of C4F10 drop vaporization was quantified at temperatures ranging from 55 to 75 °C, and an apparent activation energy barrier was calculated from an Arrhenius plot. Interestingly, the activation energy increased linearly with acyl chain length from C14 to C20, indicating that lipid interchain cohesion plays an important role in suppressing the vaporization rate. The vaporized drops (microbubbles) were found to be unstable to dissolution at high temperatures, particularly for C14 and C16. However, proper choice of the fluorocarbon and lipid species provided a nanoemulsion that could undergo at least ten reversible condensation/vaporization cycles. The vaporization properties presented in this study may facilitate the engineering of tunable phase-shift particles for diagnostic imaging, targeted drug delivery, tissue ablation, and other applications.

  3. Drop impact entrapment of bubble rings

    KAUST Repository

    Thoraval, M.-J.

    2013-04-29

    We use ultra-high-speed video imaging to look at the initial contact of a drop impacting on a liquid layer. We observe experimentally the vortex street and the bubble-ring entrapments predicted numerically, for high impact velocities, by Thoraval et al. (Phys. Rev. Lett., vol. 108, 2012, article 264506). These dynamics mainly occur within 50 -s after the first contact, requiring imaging at 1 million f.p.s. For a water drop impacting on a thin layer of water, the entrapment of isolated bubbles starts through azimuthal instability, which forms at low impact velocities, in the neck connecting the drop and pool. For Reynolds number Re above -12 000, up to 10 partial bubble rings have been observed at the base of the ejecta, starting when the contact is -20% of the drop size. More regular bubble rings are observed for a pool of ethanol or methanol. The video imaging shows rotation around some of these air cylinders, which can temporarily delay their breakup into micro-bubbles. The different refractive index in the pool liquid reveals the destabilization of the vortices and the formation of streamwise vortices and intricate vortex tangles. Fine-scale axisymmetry is thereby destroyed. We show also that the shape of the drop has a strong influence on these dynamics. 2013 Cambridge University Press.

  4. Drop Testing Representative Multi-Canister Overpacks

    Energy Technology Data Exchange (ETDEWEB)

    Snow, Spencer D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Morton, Dana K. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-06-01

    The objective of the work reported herein was to determine the ability of the Multi- Canister Overpack (MCO) canister design to maintain its containment boundary after an accidental drop event. Two test MCO canisters were assembled at Hanford, prepared for testing at the Idaho National Engineering and Environmental Laboratory (INEEL), drop tested at Sandia National Laboratories, and evaluated back at the INEEL. In addition to the actual testing efforts, finite element plastic analysis techniques were used to make both pre-test and post-test predictions of the test MCOs structural deformations. The completed effort has demonstrated that the canister design is capable of maintaining a 50 psig pressure boundary after drop testing. Based on helium leak testing methods, one test MCO was determined to have a leakage rate not greater than 1x10-5 std cc/sec (prior internal helium presence prevented a more rigorous test) and the remaining test MCO had a measured leakage rate less than 1x10-7 std cc/sec (i.e., a leaktight containment) after the drop test. The effort has also demonstrated the capability of finite element methods using plastic analysis techniques to accurately predict the structural deformations of canisters subjected to an accidental drop event.

  5. Analysis of the Dryden Wet Bulb GLobe Temperature Algorithm for White Sands Missile Range

    Science.gov (United States)

    LaQuay, Ryan Matthew

    2011-01-01

    In locations where workforce is exposed to high relative humidity and light winds, heat stress is a significant concern. Such is the case at the White Sands Missile Range in New Mexico. Heat stress is depicted by the wet bulb globe temperature, which is the official measurement used by the American Conference of Governmental Industrial Hygienists. The wet bulb globe temperature is measured by an instrument which was designed to be portable and needing routine maintenance. As an alternative form for measuring the wet bulb globe temperature, algorithms have been created to calculate the wet bulb globe temperature from basic meteorological observations. The algorithms are location dependent; therefore a specific algorithm is usually not suitable for multiple locations. Due to climatology similarities, the algorithm developed for use at the Dryden Flight Research Center was applied to data from the White Sands Missile Range. A study was performed that compared a wet bulb globe instrument to data from two Surface Atmospheric Measurement Systems that was applied to the Dryden wet bulb globe temperature algorithm. The period of study was from June to September of2009, with focus being applied from 0900 to 1800, local time. Analysis showed that the algorithm worked well, with a few exceptions. The algorithm becomes less accurate to the measurement when the dew point temperature is over 10 Celsius. Cloud cover also has a significant effect on the measured wet bulb globe temperature. The algorithm does not show red and black heat stress flags well due to shorter time scales of such events. The results of this study show that it is plausible that the Dryden Flight Research wet bulb globe temperature algorithm is compatible with the White Sands Missile Range, except for when there are increased dew point temperatures and cloud cover or precipitation. During such occasions, the wet bulb globe temperature instrument would be the preferred method of measurement. Out of the 30

  6. Tipping Point

    Medline Plus

    Full Text Available ... OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point ... 24 hours a day. For young children whose home is a playground, it’s the best way to ...

  7. Fixed Points

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 5. Fixed Points - From Russia with Love - A Primer of Fixed Point Theory. A K Vijaykumar. Book Review Volume 5 Issue 5 May 2000 pp 101-102. Fulltext. Click here to view fulltext PDF. Permanent link:

  8. Skid resistance determination for pavement management and wet-weather road safety

    Directory of Open Access Journals (Sweden)

    T.F. Fwa

    2017-09-01

    Full Text Available Road accidents during wet weather have been a topic of major concern of road engineers in regions of wet-tropical climate and in other parts of the world during the wet season of the year. Road safety studies indicate that approximately 20% of all road accidents occurred during wet weather, and that the skid resistance of wet pavements have a major influence on the occurrences of wet-weather accidents. Monitoring of wet pavement skid resistance has been an integral part of a typical pavement management system. However, because of the lack of prediction capability of pavement skid resistance under various rainfall intensities, the minimum skid resistance threshold for safe wet-weather driving has been specified by highway agencies based on either engineering judgement or past experience. It is shown in this paper that the single-point minimum skid resistance threshold is inadequate to offer a complete description of the skid resistance performance of the pavement sections in question for effective management of a road network. It is unable to assess the risk involved in an actual wet-weather condition where the pavement surface water-film thickness and vehicle speed are different from standard test conditions. This limitation of the current system of specifying a minimum skid resistance threshold can be overcome by adopting a theoretically sound approach to represent pavement skid resistance under different conditions of water-film thickness and vehicle speed. This paper describes the theoretical basis of the approach and the development of a mechanistically derived three-dimensional finite-element skid resistance simulation model to predict skid resistance. The application of the proposed approach and the skid resistance prediction procedure in pavement management system and wet-weather driving safety assessment is presented.

  9. Ultrasonic characterization of single drops of liquids

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Dipen N. (Los Alamos, NM)

    1998-01-01

    Ultrasonic characterization of single drops of liquids. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted, by surface tension. The surfaces of the interferometer elements may be readily cleansed by a stream of solvent followed by purified air when it is desired to change samples. A single drop of liquid is sufficient for high-quality measurement. Examples of samples which may be investigated using the apparatus and method of the present invention include biological specimens (tear drops; blood and other body fluid samples; samples from tumors, tissues, and organs; secretions from tissues and organs; snake and bee venom, etc.) for diagnostic evaluation, samples in forensic investigations, and detection of drugs in small quantities.

  10. Superheated drop as a neutron spectrometer

    Science.gov (United States)

    Das, Mala; Chatterjee, B. K.; Roy, B.; Roy, S. C.

    2000-09-01

    Superheated drops are known to vaporise when exposed to energetic nuclear radiation since the discovery of bubble chamber. The application of superheated drops in neutron research especially in neutron dosimetry is a subject of intense research for quite sometime. As the degree of superheat increases in a given liquid, less and less energetic neutrons are required to cause nucleation. This property of superheated liquid makes it possible to use it as a neutron spectrometer. Neutron detection efficiency of superheated drops made of R12 exposed to Am-Be neutron source has been measured over a wide range of temperature -17-60°C and the results have been utilised to construct the energy spectrum of the neutron source. This paper demonstrates that a suitable neutron spectrometer may be constructed by using a single liquid and varying the temperature of the liquid suitably at a closer grid.

  11. Superheated drop as a neutron spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Das, Mala; Chatterjee, B.K.; Roy, B. E-mail: biva@bosemain.boseinst.ernet.in; Roy, S.C

    2000-09-21

    Superheated drops are known to vaporise when exposed to energetic nuclear radiation since the discovery of bubble chamber. The application of superheated drops in neutron research especially in neutron dosimetry is a subject of intense research for quite sometime. As the degree of superheat increases in a given liquid, less and less energetic neutrons are required to cause nucleation. This property of superheated liquid makes it possible to use it as a neutron spectrometer. Neutron detection efficiency of superheated drops made of R12 exposed to Am-Be neutron source has been measured over a wide range of temperature -17-60 deg. C and the results have been utilised to construct the energy spectrum of the neutron source. This paper demonstrates that a suitable neutron spectrometer may be constructed by using a single liquid and varying the temperature of the liquid suitably at a closer grid.

  12. Tunable Transport of Drops on a Vibrating Fiber

    Science.gov (United States)

    Bick, Alison; Sauret, Alban; Boulogne, Francois; Stone, Howard

    2014-11-01

    Transport of liquid drops on a fibrous medium is common in engineering systems such as fog harvesting and textile cleaning. The control of the drop movement on fibrous media can make these engineering systems more efficient. We investigated how to move drops along a single inclined fiber by controlling fiber vibration. Drop motion: static, sliding or falling, depends on the fiber inclination angle, drop volume, and the distance of the drop from the vibrating source. Specifically, by vibrating the fiber the transition between the three drop motion states can be controlled. By defining the response of drop movement to vibration frequency, we can model the drop movement transition. This knowledge is directly useful for controlling drop movement on the fiber. In particular, we experimentally demonstrated that vibration frequency can be used to transport a drop along a fiber.

  13. Technical Efficiency of Wet Season Melon Farming

    Directory of Open Access Journals (Sweden)

    Ananti Yekti

    2017-03-01

    Full Text Available Melon is one of high-value horticulture commodity which is cultivated widely in Kulon Progo regency. The nature of agricultural products is heavily dependent on the season, so it causes the prices of agricultural products always fluctuated every time. In wet season the price of agricultural products tends to be more expensive. Melon cultivation in wet season provide an opportunity to earn higher profits than in the dry season. The price of agricultural products tends to be more expensive in wet season, thus melon cultivation in wet season prospectively generate high profits. In order to achieve high profitability, melon farming has to be done efficiently. Objective of this study was to 1 determined the factors that influence melon production in wet season 2 measured technical efficiency of melon farming and 3 identified the factors that influanced technical efficiency. Data collected during April – June 2014. Location determined by multistage cluster sampling. 45 samples of farmers who cultivated melon during wet season obtained based on quota sampling technique. Technical efficiency was measured using Cobb-Douglas Stochastic Frontier. The result reveals that 1 land use, quantity of seed, K fertilizer contributed significantly increasing melon production, while N fertilizer decreased melon production significantly 2 technical efficiency indeces ranged from 0.40 to 0.99, with a mean of  0.77; 3 farmer’s experience gave significant influence to technical efficiency of melon farming in wet season.

  14. Resolving an ostensible inconsistency in calculating the evaporation rate of sessile drops.

    Science.gov (United States)

    Chini, S F; Amirfazli, A

    2017-05-01

    This paper resolves an ostensible inconsistency in the literature in calculating the evaporation rate for sessile drops in a quiescent environment. The earlier models in the literature have shown that adapting the evaporation flux model for a suspended spherical drop to calculate the evaporation rate of a sessile drop needs a correction factor; the correction factor was shown to be a function of the drop contact angle, i.e. f(θ). However, there seemed to be a problem as none of the earlier models explicitly or implicitly mentioned the evaporation flux variations along the surface of a sessile drop. The more recent evaporation models include this variation using an electrostatic analogy, i.e. the Laplace equation (steady-state continuity) in a domain with a known boundary condition value, or known as the Dirichlet problem for Laplace's equation. The challenge is that the calculated evaporation rates using the earlier models seemed to differ from that of the recent models (note both types of models were validated in the literature by experiments). We have reinvestigated the recent models and found that the mathematical simplifications in solving the Dirichlet problem in toroidal coordinates have created the inconsistency. We also proposed a closed form approximation for f(θ) which is valid in a wide range, i.e. 8°≤θ≤131°. Using the proposed model in this study, theoretically, it was shown that the evaporation rate in the CWA (constant wetted area) mode is faster than the evaporation rate in the CCA (constant contact angle) mode for a sessile drop. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Mechanisms behind the stabilizing action of cellulose nanofibrils in wet-stable cellulose foams.

    Science.gov (United States)

    Cervin, Nicholas Tchang; Johansson, Erik; Benjamins, Jan-Willem; Wågberg, Lars

    2015-03-09

    The principal purpose of the investigation was to clarify the mechanisms behind the stabilizing action of cellulose nanofibrils (CNFs) in wet-stable cellulose foams. Following the basic theories for particle-stabilized foams, the investigation was focused on how the surface energy of the stabilizing CNF particles, their aspect ratio and charge density, and the concentration of CNF particles at the air-water interface affect the foam stability and the mechanical properties of a particle-stabilized air-liquid interface. The foam stability was evaluated from how the foam height changed over time, and the mechanical properties of the interface were evaluated as the complex viscoelastic modulus of the interface using the pendant drop method. The most important results and conclusions are that CNFs can be used as stabilizing particles for aqueous foams already at a concentration as low as 5 g/L. The major reasons for this were the small dimensions of the CNF and their high aspect ratio, which is important for gel-formation and the complex viscoelastic modulus of the particle-filled air-water interface. The influence of the aspect ratio was also demonstrated by a much higher foam stability of foams stabilized with CNFs than of foams stabilized by cellulose nanocrystals (CNC) with the same chemical composition. The charge density of the CNFs affects the level of liberation within larger aggregates and hence also the number of contact points at the interface and the gel formation and complex viscoelastic modulus of the air-water interface. The charges also result in a disjoining pressure related to the long-range repulsive electrostatic pressure between particle-stabilized bubbles and hence contribute to foam stability.

  16. Analysis of Wetting and Contact Angle Hysteresis on Chemically Patterned Surfaces

    KAUST Repository

    Xu, Xianmin

    2011-01-01

    Wetting and contact angle hysteresis on chemically patterned surfaces in two dimensionsare analyzed from a stationary phase-field model for immiscible two phase fluids. We first study the sharp-interface limit of the model by the method of matched asymptotic expansions. We then justify the results rigorously by the γ-convergence theory for the related variational problem and study the properties of the limiting minimizers. The results also provide a clear geometric picture of the equilibrium configuration of the interface. This enables us to explicitly calculate the total surface energy for the two phase systems on chemically patterned surfaces with simple geometries, namely the two phase flow in a channel and the drop spreading. By considering the quasi-staticmotion of the interface described by the change of volume (or volume fraction), we can follow the change-of-energy landscape which also reveals the mechanism for the stick-slip motion of the interface and contact angle hysteresis on the chemically patterned surfaces. As the interface passes throughpatterned surfaces, we observe not only stick-slip of the interface and switching of the contact angles but also the hysteresis of contact point and contact angle. Furthermore, as the size of the patternde creases to zero, the stick-slip becomes weaker but the hysteresis becomes stronger in the sense that one observes either the advancing contact angle or the receding contact angle (when the interface ismoving in the opposite direction) without the switching in between. © 2011 Society for Industrial and Applied Mathematics.

  17. Wet scrubbing of biomass producer gas tars using vegetable oil

    Science.gov (United States)

    Bhoi, Prakashbhai Ramabhai

    The overall aims of this research study were to generate novel design data and to develop an equilibrium stage-based thermodynamic model of a vegetable oil based wet scrubbing system for the removal of model tar compounds (benzene, toluene and ethylbenzene) found in biomass producer gas. The specific objectives were to design, fabricate and evaluate a vegetable oil based wet scrubbing system and to optimize the design and operating variables; i.e., packed bed height, vegetable oil type, solvent temperature, and solvent flow rate. The experimental wet packed bed scrubbing system includes a liquid distributor specifically designed to distribute a high viscous vegetable oil uniformly and a mixing section, which was designed to generate a desired concentration of tar compounds in a simulated air stream. A method and calibration protocol of gas chromatography/mass spectroscopy was developed to quantify tar compounds. Experimental data were analyzed statistically using analysis of variance (ANOVA) procedure. Statistical analysis showed that both soybean and canola oils are potential solvents, providing comparable removal efficiency of tar compounds. The experimental height equivalent to a theoretical plate (HETP) was determined as 0.11 m for vegetable oil based scrubbing system. Packed bed height and solvent temperature had highly significant effect (p0.05) effect on the removal of model tar compounds. The packing specific constants, Ch and CP,0, for the Billet and Schultes pressure drop correlation were determined as 2.52 and 2.93, respectively. The equilibrium stage based thermodynamic model predicted the removal efficiency of model tar compounds in the range of 1-6%, 1-4% and 1-2% of experimental data for benzene, toluene and ethylbenzene, respectively, for the solvent temperature of 30° C. The NRTL-PR property model and UNIFAC for estimating binary interaction parameters are recommended for modeling absorption of tar compounds in vegetable oils. Bench scale

  18. Characteristics of wet work in nurses.

    Science.gov (United States)

    Jungbauer, F H W; Steenstra, F B; Groothoff, J W; Coenraads, P J

    2005-04-01

    Nursing is known for its high prevalence of hand dermatitis, mainly caused by the intense exposure to wet work in nursing activities. We aimed to study the characteristics of wet work exposure in nursing. Trained observers monitored the duration and frequency of different wet work activities in 45 randomly chosen nurses from different wards during a morning shift, using a method of continuous observation based on labour-observation techniques. Wet work in intensive care units accounted for 24% of the overall morning shift duration, with a frequency of 49 incidents. This was 16% in dialysis wards, with a frequency of 30 incidents, and 9% on regular wards, with a frequency of 39 incidents. The wet work activities had short mean duration cycles. The mean duration of occlusion by gloves was 3.1 min on regular wards and 6.7 min in intensive care units. The characteristics of wet work in nurses differed substantially, depending on the ward. According to the German regulation TRGS 531, our observations classify nursing as a wet work occupation, due to the frequency of wet work rather than its duration. The mean duration of occlusion in our observations was short, which makes an occlusion-induced irritating effect doubtful. Reduction in wet work exposure in nursing on regular wards could focus on the reduction of the frequency of hand-washing and patient-washing. We suggest increasing the use of gloves for patient washing. Although this will increase exposure to occlusion from gloves, it may reduce the frequency of exposure to water and soap by about a quarter.

  19. How to determine wet-snow instability

    Science.gov (United States)

    Reiweger, Ingrid; Mitterer, Christoph

    2017-04-01

    Processes leading to wet-snow instability are very complex and highly non-linear in time and space. Infiltrating water changes wet-snow strength and other mechanical properties. A high liquid water content presumably favors fracture propagation, which consequently has an influence on the formation of wet slab avalanches. The weakening of snow due to liquid water within the snowpack might be gradual (melt event) or sudden (rain-on-snow event). There are several feedback mechanisms between liquid water and snow stratigraphy, making the weakening process complex. We used modelled stability indices to determine periods with high wet-snow instability. These indices were either based on energy and mass balances indicating critical amounts of water within the snowpack or on simple hydro-mechanical relationships. In addition to the modelled indices, preliminary field studies investigated the fracture initiation and fracture propagation propensity within wet snowpacks. We therefore performed Rutschblock and propagation saw tests in faceted weak layers with different volumetric liquid water contents. Results of simulations and field experiments showed that a critical amount of liquid water combined with a pre-critical snow stratigraphy were relevant for wet-snow instability. The critical amount of water was assumed to drive both failure initiation and fracture propagation. The simulated indices and observed stability tests indicated a high wet-snow instability when the volumetric liquid water content within faceted weak layers exceeded 3. Within our propagation saw test measurements crack propagation propensity even slightly decreased at very low liquid water contents compared to completely dry conditions, presumably due to capillary forces. For liquid water contents higher than 3-4%, however, crack propagation propensity strongly increased, which we assume was due to the weakening of bonds between grains within the increasingly wet weak snow layer. Our results could be used

  20. Shuttlecock Velocity of a Badminton Drop Shot

    Directory of Open Access Journals (Sweden)

    Ampharin Ongvises

    2013-12-01

    Full Text Available In a badminton ‘drop shot’, the shuttlecock is struck by a non-rotating racquet at low speed. In this investigation, a shuttlecock was hit by a badminton racquet in a linear collision, simulating a drop shot. The collision was recorded with high-speed video and the velocities of the racquet and shuttlecock determined. The relationship between the impact velocity of the racquet and the velocity of the shuttlecock as it leaves the badminton racquet after collision was found to be proportional over the range tested.

  1. Vortex-Induced Vapor Explosion during Drop Impact on a Superheated Pool

    KAUST Repository

    Alchalabi, M.A.

    2017-04-18

    Ultra high-speed imaging is used to investigate the vapor explosion when a drop impacts onto a high-temperature pool. The two liquids are immiscible, a low boiling-temperature perfluorohexane drop, at room temperature, which impacts a high boiling-temperature soybean-oil pool, which is heated well above the boiling temperature of the drop. We observe different regimes: weak and strong nucleate boiling, film boiling or Leidenfrost regime and entrainment followed by vapor explosion. The vapor explosions were seen to depend on the formation of a rotational flow at the edge of the impact crater, near the pool surface, which resembles a vortex ring. This rotational motion entrains a thin sheet of the drop liquid, to become surrounded by the oil. In that region, the vapor explosion starts at a point after which it propagates azimuthally along the entire periphery at high speed.

  2. Influence of dispersion degree of water drops on efficiency of extinguishing of flammable liquids

    Directory of Open Access Journals (Sweden)

    Korolchenko Dmitriy

    2016-01-01

    Full Text Available Depending on the size of water drops, process of fire extinguishing is focused either in a zone of combustion or on a burning liquid surface. This article considers two alternate solutions of a heat balance equation. The first solution allows us to trace decrease of temperature of a flammable liquid (FL surface to a temperature lower than fuel flash point at which combustion is stopped. And the second solution allows us to analyze decrease of burnout rate to a negligible value at which steam-air mixture becomes nonflammable. As a result of solve of a heat balance equation it was made the following conclusion: water drops which size is equal to 100 μm will completely evaporate in a zone of combustion with extent of 1 m if the flying speed of drops is even 16 mps (acc. to Stokes v = 3 mps; whereas drops of larger size will evaporate only partially.

  3. Catalytic wet oxidation of black liquor

    OpenAIRE

    Viader Riera, Gerard

    2012-01-01

    The major aspects of wet air oxidation and catalytic wet air oxidation have been reviewed in this work paying special attention to the reaction mechanisms, kinetics and the industrial process. In the experimental section a set of heterogeneous catalysts have been tested in the wet oxidation of non-wood black liquor. The oxidation runs were performed batchwise in a laboratory-scale mechanically stirred slurry reactor for 1 h at a temperature of 170°C and total pressure of 12 bar. Pure oxygen w...

  4. Wetting of B4C, TiC and graphite substrates by molten Mg

    International Nuclear Information System (INIS)

    Zhang Dan; Shen Ping; Shi Laixin; Jiang Qichuan

    2011-01-01

    Highlights: → The wettability of TiC, B4C and C by molten Mg was determined using an improved sessile drop method. → A new method to evaluate the wetting behavior coupled with evaporation and reaction was proposed. → The bonding characteristics in the Mg/B4C, Mg/TiC and Mg/graphite systems were evaluated. - Abstract: The isotherm wetting of B 4 C, TiC and graphite substrates by molten Mg was studied in a flowing Ar atmosphere at 973-1173 K using an improved sessile drop method. The initial contact angles are in the ranges of 95-87 deg., 74-60 deg. and 142-124 deg., respectively, moderately depending on the temperature. All the systems are non-reactive in nature; however, the presence of impurity of free boron at the B 4 C surface gave rise to the chemical reaction with molten Mg and thus promoted the wettability to a certain degree. A new method was proposed to evaluate the wetting behavior coupled with evaporation and chemical reaction. Furthermore, based on the comparison of the work of adhesion and cohesion, the bonding in the Mg/B 4 C and Mg/TiC systems is presumably mainly chemical while that in the Mg/graphite system is physical.

  5. Tipping Point

    Medline Plus

    Full Text Available ... Point by CPSC Blogger September 22, 2009 appliance child Childproofing CPSC danger death electrical fall furniture head ... see news reports about horrible accidents involving young children and furniture, appliance and tv tip-overs. The ...

  6. 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.

  7. Wetting transitions on textured hydrophilic surfaces.

    Science.gov (United States)

    Ishino, C; Okumura, K

    2008-04-01

    We consider the quasi-static energy of a drop on a textured hydrophilic surface, with taking the contact angle hysteresis (CAH) into account. We demonstrate how energy varies as the contact state changes from the Cassie state (in which air is trapped at the drop bottom) to the Wenzel state (in which liquid fills the texture at the drop bottom) assuming that the latter state nucleates from the center of the drop bottom. When the textured substrate is hydrophilic enough to allow spontaneous penetration of liquid film of the texture thickness, the present theory asserts that the drop develops into an experimentally observed state in which a drop looks like an egg fried without flipped over (sunny-side up) with a well-defined radius of "the egg yolk." Otherwise, the final contact state of the drop becomes like a Wenzel state, but with the contact circle smaller than the original Wenzel state due to the CAH. We provide simple analytical estimations for the yolk radius of the "sunny-side-up" state and for the final radius of the contact circle of the pseudo-Wenzel state.

  8. An algorithm for the optimal collection of wet waste.

    Science.gov (United States)

    Laureri, Federica; Minciardi, Riccardo; Robba, Michela

    2016-02-01

    This work refers to the development of an approach for planning wet waste (food waste and other) collection at a metropolitan scale. Some specific modeling features distinguish this specific waste collection problem from the other ones. For instance, there may be significant differences as regards the values of the parameters (such as weight and volume) characterizing the various collection points. As it happens for classical waste collection planning, even in the case of wet waste, one has to deal with difficult combinatorial problems, where the determination of an optimal solution may require a very large computational effort, in the case of problem instances having a noticeable dimensionality. For this reason, in this work, a heuristic procedure for the optimal planning of wet waste is developed and applied to problem instances drawn from a real case study. The performances that can be obtained by applying such a procedure are evaluated by a comparison with those obtainable via a general-purpose mathematical programming software package, as well as those obtained by applying very simple decision rules commonly used in practice. The considered case study consists in an area corresponding to the historical center of the Municipality of Genoa. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Spontaneous evaporation of the acetone drop

    Science.gov (United States)

    Dunin, S. Z.; Nagornov, O. V.

    2017-12-01

    The exact solution of the problem on evaporation of the acetone sessile drop at solid substrate is derived. The solution allows us to analyze the temperature field behavior at various thermodynamic parameters. The Marangoni forces are calculated in explicit form. The solution can be used to check numerical approaches for similar problems.

  10. Check valves with drop-shaped disk

    Energy Technology Data Exchange (ETDEWEB)

    1943-03-19

    This report discusses improvements possible with drop check valves. Up to the time of the report, the most important improvements had been: (1) lightening of the drop by hollowing it out, (2) reducing lift to reduce impact, (3) increasing clearance in the guide to minimize the danger of it getting stuck, (4) drilling of a safety hole which would indicate excessive wear of the housing by a leak. Other possibilities for the above improvements had produced the following conclusions: (1) a further lightening of the drop was found possible by milling out the halves with a milling cutter, by welding them together and thus eliminating the threaded portion, or by having the drop open on the bottom; (2) further reduction in lift was not found possible in most sizes, but for reduction of the impact effect by a cushion of oil or paste, the seating surface was widened as much as possible; (3) sticking of certain check valves caused by ferrous sulfide deposits could be solved by use of a certain bushing in the housing; (4) some plants favored and some disfavored the safety hole, but in general, plants were to service check valves and change them at such regular intervals as experience dictated; (5) the seat plate was no longer solid steel, but a welded piece.

  11. Goose droppings as food for reindeer

    NARCIS (Netherlands)

    van der Wal, R; Loonen, MJJE

    Feeding conditions for Svalbard reindeer, Rangifer tarandus platyrhynchus, on Spitsbergen are generally poor, owing to low availability of forage. We report on coprophagy: the use of goose faeces as an alternative food source for reindeer. Fresh droppings from Barnacle Geese, Branta leucopsis,

  12. Modeling merging behavior at lane drops.

    Science.gov (United States)

    2015-02-01

    In work-zone configurations where lane drops are present, merging of traffic at the taper presents an operational concern. In : addition, as flow through the work zone is reduced, the relative traffic safety of the work zone is also reduced. Improvin...

  13. 49 CFR 178.603 - Drop test.

    Science.gov (United States)

    2010-10-01

    ... of natural wood, Plywood boxes, Reconstituted wood boxes, Fiberboard boxes, Plastic boxes, Steel or... drums, Plastic drums and Jerricans, Composite packagings which are in the shape of a drum Six—(three for... Administrator. (c) Special preparation of test samples for the drop test. (1) Testing of plastic drums, plastic...

  14. 49 CFR 178.965 - Drop test.

    Science.gov (United States)

    2010-10-01

    ... Large Packaging design types and performed periodically as specified in § 178.955(e) of this subpart. (b... § 178.960(d). (d) Test method. (1) Samples of all Large Packaging design types must be dropped onto a... be restored to the upright position for observation. (2) Large Packaging design types with a capacity...

  15. The initial regime of drop coalescence

    Science.gov (United States)

    Anthony, Christopher; Harris, Michael; Basaran, Osman

    2017-11-01

    Drop coalescence plays a key role in both industry and nature. Consequently, study of the phenomenon has been the focus of numerous experimental, computational and theoretical works to date. In coalescence, two drops come into contact and a liquid bridge forms between them. As time advances, this bridge grows from microscopic to macroscopic scales. Despite the large volume of work dedicated to this problem, currently experiment, theory, and computation are not in perfect agreement with respect to the earliest times following the initial contact of the drops. Experiments report an initial regime where the radius of the connecting bridge grows linearly in time before a transition to either a Stokes regime or an inertial regime where either viscous or inertial forces balance capillary force. In the initial linear regime, referred to as the inertially-limited viscous regime, all three forces are thought to be important. This is in contrast to theory which predicts that all coalescence events begin in the Stokes regime. We use high accuracy numerical simulation to show that the existing discrepancy in the literature can be resolved by paying careful attention to the initial conditions that set the shape and size of the bridge connecting the two drops.

  16. The stability of cylindrical pendant drops

    CERN Document Server

    McCuan, John

    2018-01-01

    The author considers the stability of certain liquid drops in a gravity field satisfying a mixed boundary condition. He also considers as special cases portions of cylinders that model either the zero gravity case or soap films with the same kind of boundary behavior.

  17. Reactor Flow and Pressure Drop Study

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, R. E.

    1969-07-15

    A study was made to determine the flow rates and pressure drops for all primary system flow paths through the FTR. The main data and results are in tables, diagrams and curves. The results are intended to provide a common basis for evaluation of parametric changes in the system.

  18. Biomechanical analysis of drop and countermovement jumps

    NARCIS (Netherlands)

    Bobbert, M. F.; Mackay, M.T.; Schinkelshoek, D.; Huijing, P. A.; van Ingen Schenau, G. J.

    For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle

  19. Scaling the drop size in coflow experiments

    International Nuclear Information System (INIS)

    Castro-Hernandez, E; Gordillo, J M; Gundabala, V; Fernandez-Nieves, A

    2009-01-01

    We perform extensive experiments with coflowing liquids in microfluidic devices and provide a closed expression for the drop size as a function of measurable parameters in the jetting regime that accounts for the experimental observations; this expression works irrespective of how the jets are produced, providing a powerful design tool for this type of experiments.

  20. Scaling the drop size in coflow experiments

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Hernandez, E; Gordillo, J M [Area de Mecanica de Fluidos, Universidad de Sevilla, Avenida de los Descubrimientos s/n, 41092 Sevilla (Spain); Gundabala, V; Fernandez-Nieves, A [School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States)], E-mail: jgordill@us.es

    2009-07-15

    We perform extensive experiments with coflowing liquids in microfluidic devices and provide a closed expression for the drop size as a function of measurable parameters in the jetting regime that accounts for the experimental observations; this expression works irrespective of how the jets are produced, providing a powerful design tool for this type of experiments.

  1. Structure of Wet Specimens in Electron Microscopy

    Science.gov (United States)

    Parsons, D. F.

    1974-01-01

    Discussed are past work and recent advances in the use of electron microscopes for viewing structures immersed in gas and liquid. Improved environmental chambers make it possible to examine wet specimens easily. (Author/RH)

  2. 7 CFR 51.897 - Wet.

    Science.gov (United States)

    2010-01-01

    ... the grapes are wet from moisture from crushed, leaking, or decayed berries or from rain. Grapes which are moist from dew or other moisture condensation such as that resulting from removing grapes from a...

  3. ROE Wet Nitrate Deposition 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet nitrate deposition in kilograms per hectare from 2011 to 2013. Summary data in this indicator were provided by EPA’s...

  4. ROE Wet Nitrate Deposition 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet nitrate deposition in kilograms per hectare from 1989 to 1991. Summary data in this indicator were provided by EPA’s...

  5. ROE Wet Sulfate Deposition 2009-2011

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet sulfate deposition in kilograms per hectare from 2009 to 2011. Summary data in this indicator were provided by EPA’s...

  6. Wet granular matter a truly complex fluid

    CERN Document Server

    Herminghaus, Stephan

    2013-01-01

    This is a monograph written for the young and advanced researcher who is entering the field of wet granular matter and keen to understand the basic physical principles governing this state of soft matter. It treats wet granulates as an instance of a ternary system, consisting of the grains, a primary, and a secondary fluid. After addressing wetting phenomena in general and outlining the basic facts on dry granular systems, a chapter on basic mechanisms and their effects is dedicated to every region of the ternary phase diagram. Effects of grain shape and roughness are considered as well. Rather than addressing engineering aspects such as existing books on this topic do, the book aims to provide a generalized framework suitable for those who want to understand these systems on a more fundamental basis. Readership: For the young and advanced researcher entering the field of wet granular matter.

  7. 7 CFR 29.3567 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO... damage if treated in the customary manner. (See Rule 22, § 29.3623.) (For extremely wet or watered...

  8. 7 CFR 29.2316 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO... order. Wet applies to any tobacco which is not damaged but which is likely to damage if treated in the...

  9. 7 CFR 29.3077 - Wet (W).

    Science.gov (United States)

    2010-01-01

    ... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO... doubtful-keeping order. Wet applies to any tobacco which is not damaged but which is likely to damage if...

  10. A New Approach to Measure Contact Angle and Evaporation Rate with Flow Visualization in a Sessile Drop

    Science.gov (United States)

    Zhang, Nengli; Chao, David F.

    1999-01-01

    The contact angle and the spreading process of sessile droplet are very crucial in many technological processes, such as painting and coating, material processing, film-cooling applications, lubrication, and boiling. Additionally, as it is well known that the surface free energy of polymers cannot be directly, measured for their elastic and viscous restraints. The measurements of liquid contact angle on the polymer surfaces become extremely important to evaluate the surface free energy of polymers through indirect methods linked with the contact angle data. Due to the occurrence of liquid evaporation is inevitable, the effects of evaporation on the contact angle and the spreading become very important for more complete understanding of these processes. It is of interest to note that evaporation can induce Marangoni-Benard convection in sessile drops. However, the impacts of the inside convection on the wetting and spreading processes are not clear. The experimental methods used by previous investigators cannot simultaneously measure the spreading process and visualize the convection inside. Based on the laser shadowgraphic system used by the present author, a very simple optical procedure has been developed to measure the contact angle, the spreading speed, the evaporation rate, and to visualize inside convection of a sessile drop simultaneously. Two CCD cameras were used to synchronously record the real-time diameter of the sessile drop, which is essential for determination of both spreading speed and evaporation rate, and the shadowgraphic image magnified by the sessile drop acting as a thin plano-convex lens. From the shadowgraph, the inside convection of the drop can be observed if any and the image outer diameter, which linked to the drop profile, can be measured. Simple equations have been derived to calculate the drop profile, including the instantaneous contact angle, height, and volume of the sessile drop, as well as the evaporation rate. The influence of

  11. Wet winter pore pressures in railway embankments

    OpenAIRE

    Briggs, Kevin M; Smethurst, Joel A; Powrie, William; O'Brien, Anthony S

    2013-01-01

    This paper demonstrates the influence of extreme wet winter weather on pore water pressures within clay fill railway embankments, using field monitoring data and numerical modelling. Piezometer readings taken across the London Underground Ltd network following the wet winter of 2000/2001 were examined, and showed occurrences of hydrostatic pore water pressure within embankments but also many readings below this. A correlation was found between the maximum pore water pressures and the permeabi...

  12. Leaf wetness distribution within a potato crop

    Science.gov (United States)

    Heusinkveld, B. G.

    2010-07-01

    The Netherlands has a mild maritime climate and therefore the major interest in leaf wetness is associated with foliar plant diseases. During moist micrometeorological conditions (i.e. dew, fog, rain), foliar fungal diseases may develop quickly and thereby destroy a crop quickly. Potato crop monocultures covering several hectares are especially vulnerable to such diseases. Therefore understanding and predicting leaf wetness in potato crops is crucial in crop disease control strategies. A field experiment was carried out in a large homogeneous potato crop in the Netherlands during the growing season of 2008. Two innovative sensor networks were installed as a 3 by 3 grid at 3 heights covering an area of about 2 hectares within two larger potato crops. One crop was located on a sandy soil and one crop on a sandy peat soil. In most cases leaf wetting starts in the top layer and then progresses downward. Leaf drying takes place in the same order after sunrise. A canopy dew simulation model was applied to simulate spatial leaf wetness distribution. The dew model is based on an energy balance model. The model can be run using information on the above-canopy wind speed, air temperature, humidity, net radiation and within canopy air temperature, humidity and soil moisture content and temperature conditions. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with the leaf wetness sensors if all local conditions were considered. The measurements show that the spatial correlation of leaf wetness decreases downward.

  13. Allergenic Ingredients in Personal Hygiene Wet Wipes.

    Science.gov (United States)

    Aschenbeck, Kelly A; Warshaw, Erin M

    Wet wipes are a significant allergen source for anogenital allergic contact dermatitis. The aim of the study was to calculate the frequency of potentially allergenic ingredients in personal hygiene wet wipes. Ingredient lists from brand name and generic personal hygiene wet wipes from 4 large retailers were compiled. In the 54 personal hygiene wet wipes evaluated, a total of 132 ingredients were identified (average of 11.9 ingredients per wipe). The most common ingredients were Aloe barbadensis (77.8%), citric acid (77.8%), fragrance (72.2%), sorbic acid derivatives (63.0%), tocopherol derivatives (63.0%), glycerin (59.3%), phenoxyethanol (55.6%), disodium cocoamphodiacetate (53.7%), disodium ethylenediaminetetraacetic acid (EDTA) (42.6%), propylene glycol (42.6%), iodopropynyl butylcarbamate (40.7%), chamomile extracts (38.9%), sodium benzoate (35.2%), bronopol (22.2%), sodium citrate (22.2%), lanolin derivatives (20.4%), parabens (20.4%), polyethylene glycol derivatives (18.5%), disodium phosphate (16.7%), dimethylol dimethyl hydantoin (DMDM) (14.8%), and cocamidopropyl propylene glycol (PG)-dimonium chloride phosphate (11.1%). Of note, methylisothiazolinone (5.6%) was uncommon; methylchloroisothiazolinone was not identified in the personal hygiene wet wipes examined. There are many potential allergens in personal hygiene wet wipes, especially fragrance and preservatives.

  14. Lifetime of oil drops pressed by buoyancy against a planar interface: Large drops

    Science.gov (United States)

    Rojas, Clara; García-Sucre, Máximo; Urbina-Villalba, Germán

    2010-11-01

    In a previous report [C. Rojas, G. Urbina-Villalba, and M. García-Sucre, Phys. Rev. E 81, 016302 (2010)10.1103/PhysRevE.81.016302] it was shown that emulsion stability simulations are able to reproduce the lifetime of micrometer-size drops of hexadecane pressed by buoyancy against a planar water-hexadecane interface. It was confirmed that small drops (ri<10μm) stabilized with β -casein behave as nondeformable particles, moving with a combination of Stokes and Taylor tensors as they approach the interface. Here, a similar methodology is used to parametrize the potential of interaction of drops of soybean oil stabilized with bovine serum albumin. The potential obtained is then employed to study the lifetime of deformable drops in the range 10≤ri≤1000μm . It is established that the average lifetime of these drops can be adequately replicated using the model of truncated spheres. However, the results depend sensibly on the expressions of the initial distance of deformation and the maximum film radius used in the calculations. The set of equations adequate for large drops is not satisfactory for medium-size drops (10≤ri≤100μm) , and vice versa. In the case of large particles, the increase in the interfacial area as a consequence of the deformation of the drops generates a very large repulsive barrier which opposes coalescence. Nevertheless, the buoyancy force prevails. As a consequence, it is the hydrodynamic tensor of the drops which determine the characteristic behavior of the lifetime as a function of the particle size. While the average values of the coalescence time of the drops can be justified by the mechanism of film thinning, the scattering of the experimental data of large drops cannot be rationalized using the methodology previously described. A possible explanation of this phenomenon required elaborate simulations which combine deformable drops, capillary waves, repulsive interaction forces, and a time-dependent surfactant adsorption.

  15. Effects of surfactant treatments on the wettability of the surface layer and the wetting patterns in a water repellent dune sand with grass cover

    NARCIS (Netherlands)

    Dekker, L.W.; Oostindie, K.; Ritsema, C.J.

    2000-01-01

    This study evaluates the effectiveness of a new surfactant formulation (Primer R604) for amelioration and management of soil water repellency in a dune sand, as measured with the water drop penetration test, and soil moisture content and wetting rate assessments. A dune sand with grass cover with a

  16. Ecological destabilisation of alluvial wet monsoon rainforest primarily through hydro-geomorphic feedbacks and secondarily through fire in tropical northern Australia

    Science.gov (United States)

    Larsen, Annegret; May, Jan-Hendrik

    2015-04-01

    Isolated patches of wet monsoon forest within a eucalyptus-savanna dominated landscape are present within many springs and alluvial valleys in the Australian Monsoon Tropics (AMT). Using combined field evidence, lidar, and remote sensing data, we observe the ongoing and potentially irreversible destruction of wet monsoon forest downstream of Wangi Waterfalls in Litchfield National Park through hydro-geomorphic feedbacks accompanying the retreat of an alluvial knickpoint. This knickpoint retreat leads to a downstream drop in in-channel water level, which in turn drives a drop in the local groundwater table in a highly transmissive shallow aquifer. This drop in groundwater level causes the shallow anabranches and the formerly water saturated peat floodplain surface to dry out, which results in a reduction in vegetation density. These dry surface conditions then allow the monsoon forest to burn during annual to bi-annual low-intensity bush fires; while wet rainforest remaining upstream of the knickpoint are unlikely to burn. In this paper, we show that hydro-geomorphic feedbacks provide the initial destabilization, with fire able to then take advantage of the resulting environmental conditions. We challenge the prevalent view that fire has first order control in the extension of these ecosystems and show that this is more likely to be second order, since the wet monsoon forest is already diminishing regardless of fire, although fire certainly accelerates its decline. The distribution of remaining wet monsoon forest is therefore strongly dependent on the local hydrological conditions, and less on the frequency of fire.

  17. Coalescence collision of liquid drops I: Off-center collisions of equal-size drops

    Directory of Open Access Journals (Sweden)

    Alejandro Acevedo-Malavé

    2011-09-01

    Full Text Available The Smoothed Particle Hydrodynamics method (SPH is used here to model off-center collisions of equal-size liquid drops in a three-dimensional space. In this study the Weber number is calculated for several conditions of the droplets dynamics and the velocity vector fields formed inside the drops during the collision process are shown. For the permanent coalescence the evolution of the kinetic and internal energy is shown and also the approaching to equilibrium of the resulting drop. Depending of the Weber number three possible outcomes for the collision of droplets is obtained: permanent coalescence, flocculation and fragmentation. The fragmentation phenomena are modeled and the formation of small satellite drops can be seen. The ligament that is formed follows the “end pinching” mechanism and it is transformed into a flat structure.

  18. Viscoelastic and poroelastic effects in the wetting dynamics of soft gels by liquids

    Science.gov (United States)

    Limat, Laurent; Dervaux, Julien; Roche, Matthieu; Zhao, Menghua; Narita, Tetsuharu; Lequeux, Francois

    2017-11-01

    We have developed experiments and modeling of elastowetting dynamics on soft gels. First, wetting is very sensitive to the thickness of the gel, when deposited on a rigid basis. We reconsidered Long et al. approach, and extended it to finite depth. This yields a new scaling law, at low thickness, for dynamic contact angle, in very good agreement with experiment but not consistent with recent approachs assuming Neuman triangle to hold even in the dynamics. In a second step, we examined solvent migration in the bulk of the gel, and showed that poroelasticity is an essential ingredient to understand old unsolved issues (hysteresis on elastomers by Extrand and Kumagai), as well as recent puzzling measurements (long life footprints left by drops). Our calculations lead to ridges at the contact lines evolving logarithmically with time, with a very strong infuence on wetting properties of soft materials, and with possible applications to biophysics.

  19. Reactive Wetting of Pure Titanium by Molten 6061 and 4043 Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    ZHONG Wei-qiang

    2017-12-01

    Full Text Available The wetting of TA2 pure Ti by two industrial grade Al alloys (i.e.,6061 Al and 4043 Al alloys was studied by using the modified sessile drop method at 600,650,700℃ under high vacuum. The results show Al/Ti system is a typical reactive wetting, the small amount of alloying element Si in the Al alloys can cause significant enrichment at liquid/solid interface and satisfy thermodynamic condition;the formation of the Si-rich phase (Ti7Al5Si12 strangling material exchange at triple line zone; Ti7Al5Si12 decomposition and Al3Ti formation can remove the oxide film and promote wetting;the spreading dynamics can be described by reaction product control model, further the whole wetting behavior can be divided into two stages:the first stage for the nonlinear spreading and the second stage forthe linear spreading;the activation energies which are 56kJ/mol, 47kJ/mol for nonlinear stages of 6061 Al and 4043 Al alloys, and 112kJ/mol for linear stage of 6061 Al alloys, respectively,Ti7Al5Si12 decomposition is corresponding to the nonlinear spreading.

  20. A pressure drop model for PWR grids

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Dong Seok; In, Wang Ki; Bang, Je Geon; Jung, Youn Ho; Chun, Tae Hyun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A pressure drop model for the PWR grids with and without mixing device is proposed at single phase based on the fluid mechanistic approach. Total pressure loss is expressed in additive way for form and frictional losses. The general friction factor correlations and form drag coefficients available in the open literatures are used to the model. As the results, the model shows better predictions than the existing ones for the non-mixing grids, and reasonable agreements with the available experimental data for mixing grids. Therefore it is concluded that the proposed model for pressure drop can provide sufficiently good approximation for grid optimization and design calculation in advanced grid development. 7 refs., 3 figs., 3 tabs. (Author)

  1. How drops start sliding over solid surfaces

    Science.gov (United States)

    Gao, Nan; Geyer, Florian; Pilat, Dominik W.; Wooh, Sanghyuk; Vollmer, Doris; Butt, Hans-Jürgen; Berger, Rüdiger

    2018-02-01

    It has been known for more than 200 years that the maximum static friction force between two solid surfaces is usually greater than the kinetic friction force--the force that is required to maintain the relative motion of the surfaces once the static force has been overcome. But the forces that impede the lateral motion of a drop of liquid on a solid surface are not as well characterized, and there is a lack of understanding about liquid-solid friction in general. Here, we report that the lateral adhesion force between a liquid drop and a solid can also be divided into a static and a kinetic regime. This striking analogy with solid-solid friction is a generic phenomenon that holds for liquids of different polarities and surface tensions on smooth, rough and structured surfaces.

  2. Drop evaporation and triple line dynamics

    Science.gov (United States)

    Sobac, Benjamin; Brutin, David; Gavillet, Jerome; Université de Provence Team; Cea Liten Team

    2011-03-01

    Sessile drop evaporation is a phenomenon commonly came across in nature or in industry with cooling, paintings or DNA mapping. However, the evaporation of a drop deposited on a substrate is not completely understood due to the complexity of the problem. Here we investigate, with several nano-coating of the substrate (PTFE, SiOx, SiOc and CF), the influence of the dynamic of the triple line on the evaporation process. The experiment consists in analyzing simultaneously the motion of the triple line, the kinetics of evaporation, the internal thermal motion and the heat and mass transfer. Measurements of temperature, heat-flux and visualizations with visible and infrared cameras are performed. The dynamics of the evaporative heat flux appears clearly different depending of the motion of the triple line

  3. Semisupervised Community Detection by Voltage Drops

    Directory of Open Access Journals (Sweden)

    Min Ji

    2016-01-01

    Full Text Available Many applications show that semisupervised community detection is one of the important topics and has attracted considerable attention in the study of complex network. In this paper, based on notion of voltage drops and discrete potential theory, a simple and fast semisupervised community detection algorithm is proposed. The label propagation through discrete potential transmission is accomplished by using voltage drops. The complexity of the proposal is OV+E for the sparse network with V vertices and E edges. The obtained voltage value of a vertex can be reflected clearly in the relationship between the vertex and community. The experimental results on four real networks and three benchmarks indicate that the proposed algorithm is effective and flexible. Furthermore, this algorithm is easily applied to graph-based machine learning methods.

  4. Head-on collision of drops: A numerical investigation

    Science.gov (United States)

    Nobari, M. R.; Jan, Y.-J.; Tryggvason, G.

    1993-01-01

    The head-on collision of equal sized drops is studied by full numerical simulations. The Navier-Stokes equations are solved for fluid motion both inside and outside the drops using a front tracking/finite difference technique. The drops are accelerated toward each other by a body force that is turned off before the drops collide. When the drops collide, the fluid between them is pushed outward leaving a thin later bounded by the drop surface. This layer gets progressively thinner as the drops continue to deform and in several of the calculations this double layer is artificially removed once it is thin enough, thus modeling rupture. If no rupture takes place, the drops always rebound, but if the film is ruptured the drops may coalesce permanently or coalesce temporarily and then split again.

  5. Drag and Drop API v HTML5

    OpenAIRE

    BARABÁŠ, Vít

    2013-01-01

    The work (the bachelor´s thesis) deals with a new way of web application management via the "drag and drop" technique in the HTML5 programming language. The work is divided into two parts. The first part consists of DND API description in HTML5. The support analysis within common web browsers is included as a part of this description. The second, practical part of the thesis focuses on a concept and the following realisation of a photogallery using DND API.

  6. Sessile Drop Evaporation and Leidenfrost Phenomenon

    OpenAIRE

    A. K. Mozumder; M. R. Ullah; A. Hossain; M. A. Islam

    2010-01-01

    Problem statement: Quenching and cooling are important process in manufacturing industry for controlling the mechanical properties of materials, where evaporation is a vital mode of heat transfer. Approach: This study experimentally investigated the evaporation of sessile drop for four different heated surfaces of Aluminum, Brass, Copper and Mild steel with a combination of four different liquids as Methanol, Ethanol, Water and NaCl solution. The time of evaporation for the droplet on the hot...

  7. Superheated drop as a neutron spectrometer

    OpenAIRE

    Das, Mala; Chatterjee, B. K.; Roy, B.; Roy, S. C.

    2000-01-01

    Superheated drops are known to vaporise when exposed to energetic nuclear radiation since the discovery of bubble chamber. As the degree of superheat increases in a given liquid, less and less energetic neutrons are required to cause nucleation. This property of superheated liquids are being utilised to develope the neutron spectromer. A new principle of neutron spectrometry using Superheated liquid are developed and the developed principle has been tested by Am-Be neutron source.

  8. Low-Pressure-Drop Shutoff Valve

    Science.gov (United States)

    Thornborrow, John

    1994-01-01

    Flapper valve remains open under normal flow conditions but closes upon sudden increases to high rate of flow and remains closed until reset. Valve is fluid/mechanical analog of electrical fuse or circuit breaker. Low-pressure-drop shutoff valve contains flapper machined from cylindrical surface. During normal flow conditions, flapper presents small cross section to flow. (Useful in stopping loss of fluid through leaks in cooling systems.)

  9. The jet mass distribution after Soft Drop

    Science.gov (United States)

    Marzani, Simone; Schunk, Lais; Soyez, Gregory

    2018-02-01

    We present a first-principle computation of the mass distribution of jets which have undergone the grooming procedure known as Soft Drop. This calculation includes the resummation of the large logarithms of the jet mass over its transverse momentum, up to next-to-logarithmic accuracy, matched to exact fixed-order results at next-to-leading order. We also include non-perturbative corrections obtained from Monte-Carlo simulations and discuss analytic expressions for hadronisation and Underlying Event effects.

  10. Influence of pH on wetting kinetics of a pine forest soil

    Science.gov (United States)

    Amer, Ahmad; Schaumann, Gabriele; Diehl, Dörte

    2014-05-01

    Water repellent properties of organic matter significantly alter soil water dynamics. Various environmental factors control appearance and breakup of repellency in soil. Beside water content and temperature also pH exerts an influence on soil water repellency although investigations achieved partly ambiguous results; some found increasing repellency with increasing pH (Terashima et al. 2004; Duval et al. 2005), other with decreasing pH (Karnok et al. 1993; Roper 2005) and some found repellency maxima at intermediate pH and an increase with decreasing and with increasing pH (Bayer and Schaumann 2007; Diehl et al. 2010). The breakup of repellency may be observed via the time dependent sessile drop contact angle (TISED). With water contact time, soil-water contact angle decreases until complete wetting is reached. Diehl and Schaumann (2007) calculated the activation energy of the wetting process from the rate of sessile drop wetting obtained at different temperatures and draw conclusions on chemical or physical nature of repellency. The present study aims at the influence of pH on the wetting kinetics of soil. Therefore, TISED of soil was determined as a function of pH and temperature. We used upper soil samples (0 - 10 cm) from a pine forest in the southwest of Germany (Rheinland-Pfalz). Samples were air-dried, sieved Geoderma 158(3-4): 375-384. Diehl, D. and G. E. Schaumann (2007). Hydrol. Processes 21(17): 2255 - 2265. Duval, J. F. L., K. J. Wilkinson, et al. (2005). Environ Sci Technol 39(17): 6435-6445. Karnok, K. A., E. J. Rowland, et al. (1993). Agron J 85(5): 983-986. Roper, M. M. (2005). Aust J Soil Res 43: 803-810. Terashima, M., M. Fukushima, et al. (2004). Colloids and Surfaces, A: Physicochemical and Engineering Aspects 247(1-3): 77-83.

  11. Vortex-induced buckling of a viscous drop impacting a pool

    KAUST Repository

    Li, Erqiang

    2017-07-20

    We study the intricate buckling patterns which can form when a viscous drop impacts a much lower viscosity miscible pool. The drop enters the pool by its impact inertia, flattens, and sinks by its own weight while stretching into a hemispheric bowl. Upward motion along the outer bottom surface of this bowl produces a vortical boundary layer which separates along its top and rolls up into a vortex ring. The vorticity is therefore produced in a fundamentally different way than for a drop impacting a pool of the same liquid. The vortex ring subsequently advects into the bowl, thereby stretching the drop liquid into ever thinner sheets, reaching the micron level. The rotating motion around the vortex pulls in folds to form multiple windings of double-walled toroidal viscous sheets. The axisymmetric velocity field thereby stretches the drop liquid into progressively finer sheets, which are susceptible to both axial and azimuthal compression-induced buckling. The azimuthal buckling of the sheets tends to occur on the inner side of the vortex ring, while their folds can be stretched and straightened on the outside edge. We characterize the total stretching from high-speed video imaging and use particle image velocimetry to track the formation and evolution of the vortex ring. The total interfacial area between the drop and the pool liquid can grow over 40-fold during the first 50 ms after impact. Increasing pool viscosity shows entrapment of a large bubble on top of the drop, while lowering the drop viscosity produces intricate buckled shapes, appearing at the earliest stage and being promoted by the crater motions. We also present an image collage of the most intriguing and convoluted structures observed. Finally, a simple point-vortex model reproduces some features from the experiments and shows variable stretching along the wrapping sheets.

  12. Eye-Drops for Activation of DREADDs

    Directory of Open Access Journals (Sweden)

    William T. Keenan

    2017-11-01

    Full Text Available Designer Receptors Exclusively Activated by Designer Drugs (DREADDs are an important tool for modulating and understanding neural circuits. Depending on the DREADD system used, DREADD-targeted neurons can be activated or repressed in vivo following a dose of the DREADD agonist clozapine-N-oxide (CNO. Because DREADD experiments often involve behavioral assays, the method of CNO delivery is important. Currently, the most common delivery method is intraperitoneal (IP injection. IP injection is both a fast and reliable technique, but it is painful and stressful particularly when many injections are required. We sought an alternative CNO delivery paradigm, which would retain the speed and reliability of IP injections without being as invasive. Here, we show that CNO can be effectively delivered topically via eye-drops. Eye-drops robustly activated DREADD-expressing neurons in the brain and peripheral tissues and does so at the same dosages as IP injection. Eye-drops provide an easier, less invasive and less stressful method for activating DREADDs in vivo.

  13. Drop friction on liquid-infused surfaces

    Science.gov (United States)

    Gas, Armelle; Keiser, Ludovic; Clanet, Christophe; Quere, David

    2017-11-01

    Trapping a thin liquid film in the roughness of a textured material creates a surface that is partially solid and partially liquid, referred to as a lubricant-impregnated surface. Those surfaces have recently raised a great interest for their promising industrial applications. Indeed, they proved to drastically reduce adhesion of a broad range of liquids, leading to enhanced mobility, and strong anti-biofouling, anti-icing and anti-fogging properties. In our talk we discuss the nature of the friction generated as a drop glides on a textured material infused by another liquid. Different regimes are observed, depending on the viscosities of both liquids. While a viscous drop is simply opposed by a Stokes-type friction, the force opposing a drop moving on a viscous substrate becomes non-linear in velocity. A liquid on an infused material is surrounded by a meniscus, and this specific feature is proposed to be responsible for the special observed frictions, on both adhesive and nonadhesive substrates.

  14. Organization of microbeads in Leidenfrost drops.

    Science.gov (United States)

    Maquet, Laurent; Colinet, Pierre; Dorbolo, Stéphane

    2014-06-21

    We investigated the organization of micrometric hydrophilic beads (glass or basalt) immersed in Leidenfrost drops. Starting from a large volume of water compared to the volume of the beads, while the liquid evaporates, we observed that the grains are eventually trapped at the interface of the droplet and accumulate. At a moment, the grains entirely cover the droplet. We measured the surface area at this moment as a function of the total mass of particles inserted in the droplet. We concluded that the grains form a monolayer around the droplet assuming (i) that the packing of the beads at the surface is a random close packing and (ii) that the initial surface of the drop is larger than the maximum surface that the beads can cover. Regarding the evaporation dynamics, the beads are found to reduce the evaporation rate of the drop. The slowdown of the evaporation is interpreted as being the consequence of the dewetting of the particles located at the droplet interface which makes the effective surface of evaporation smaller. As a matter of fact, contact angles of the beads with the water deduced from the evaporation rates are consistent with contact angles of beads directly measured at a flat air-water interface of water in a container.

  15. Ultrasonic characterization of single drops of liquids

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, D.N.

    1998-04-14

    Ultrasonic characterization of single drops of liquids is disclosed. The present invention includes the use of two closely spaced transducers, or one transducer and a closely spaced reflector plate, to form an interferometer suitable for ultrasonic characterization of droplet-size and smaller samples without the need for a container. The droplet is held between the interferometer elements, whose distance apart may be adjusted, by surface tension. The surfaces of the interferometer elements may be readily cleansed by a stream of solvent followed by purified air when it is desired to change samples. A single drop of liquid is sufficient for high-quality measurement. Examples of samples which may be investigated using the apparatus and method of the present invention include biological specimens (tear drops; blood and other body fluid samples; samples from tumors, tissues, and organs; secretions from tissues and organs; snake and bee venom, etc.) for diagnostic evaluation, samples in forensic investigations, and detection of drugs in small quantities. 5 figs.

  16. Practical neutron dosimetry with superheated drops.

    Science.gov (United States)

    Apfel, R E; Lo, Y C

    1989-01-01

    The Superheated Drop Detector (SDD) is a new kind of neutron detector based on the same principle as that of the bubble chamber, except the superheated material is in drop form suspended by a gel or polymer as first described by Apfel (U.S. Patent 4,143,274). Previously, we have developed a theoretical model for the prediction of the threshold neutron energy to nucleate bubbles in our superheated materials and a model for the calculation of the energy dependent response function of SDD. The results of the theoretical calculations agree with the experimental measurements reasonably well. We found the measured response curve of one of our SDDs follows the same trend as the ideal ICRP dose equivalent response curve within 40% for neutrons of energy above 100 keV and within a factor of 10 below 100 keV. Therefore, it is possible to make a rem-response Superheated Drop Detector. We have further calibrated our SDD with 252Cf neutron sources (both bare and D2O moderated). The results are in reasonable agreement with our theoretical predictions, which proves that our model is valid not only for monoenergetic neutrons but also for neutrons from a radioactive source. The principles of operation of our detector, which can be used in neutron dosimetry, area monitoring, and neutron spectrometry, are discussed.

  17. Wetting films on chemically patterned surfaces.

    Science.gov (United States)

    Karakashev, Stoyan I; Stöckelhuber, Klaus W; Tsekov, Roumen

    2011-11-15

    The behavior of thin wetting films on chemically patterned surfaces was investigated. The patterning was performed by means of imprinting of micro-grid on methylated glass surface with UV-light (λ=184.8 nm). Thus imprinted image of the grid contained hydrophilic cells and hydrophobic bars on the glass surface. For this aim three different patterns of grids were utilized with small, medium and large size of cells. The experiment showed that the drainage of the wetting aqueous films was not affected by the type of surface patterning. However, after film rupturing in the cases of small and medium cells of the patterned grid the liquid from the wetting film underwent fast self-organization in form of regularly ordered droplets covering completely the cells of the grid. The droplets reduced significantly their size upon time due to evaporation. In the cases of the largest cell grid, a wet spot on the place of the imprinted grid was formed after film rupturing. This wet spot disassembled slowly in time. In addition, formation of a periodical zigzag three-phase contact line (TPCL) was observed. This is a first study from the planned series of studies on this topic. Copyright © 2011 Elsevier Inc. All rights reserved.

  18. Project Fog Drops. Part 1: Investigations of warm fog properties

    Science.gov (United States)

    Pilie, R. J.; Eadie, W.; Mack, E. J.; Rogers, C.; Kocmond, W. C.

    1972-01-01

    A detailed study was made of the micrometeorological and microphysical characteristics of eleven valley fogs occurring near Elmira, New York. Observations were made of temperature, dew point, wind speed and direction, dew deposition, vertical wind velocity, and net radiative flux. In fog, visibility was continuously recorded and periodic measurements were made of liquid water content and drop-size distribution. The observations were initiated in late evening and continued until the time of fog dissipation. The vertical distribution of temperature in the lowest 300 meters and cloud nucleus concentration at several heights were measured from an aircraft before fog nucleus concentrations at several heights were measured from an aircraft before fog formation. A numerical model was developed to investigate the life cycle of radiation fogs. The model predicts the temporal evolution of the vertical distributions of temperature, water vapor, and liquid water as determined by the turbulent transfer of heat and moisture. The model includes the nocturnal cooling of the earth's surface, dew formation, fog drop sedimentation, and the absorption of infrared radiation by fog.

  19. Conceptual Biorefinery Design and Research Targeted for 2022: Hydrothermal Liquefacation Processing of Wet Waste to Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Snowden-Swan, Lesley J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhu, Yunhua [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bearden, Mark D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Seiple, Timothy E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jones, Susanne B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schmidt, Andrew J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Billing, Justin M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hallen, Richard T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hart, Todd R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Liu, Jian [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Albrecht, Karl O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fox, Samuel P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Maupin, Gary D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Elliott, Douglas C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-12-28

    The Department of Energy Bioenergy Technologies Office (BETO) invests in research and development of new pathways for commercially viable conversion of biomass into drop-in ready transportation fuels, fuel blendstocks and products. The primary emphasis has been on terrestrial and algae feedstocks, but more recently BETO has begun to explore the potential of wet wastes for biofuel production, with focus on wastewater residuals, manure, food waste, and fats, oils and grease. A recent resource analysis estimates that 77 million dry tons per year of these wastes are generated annually, 65% of which are underutilized for any beneficial purpose. Approximately 14 million dry tons of the total resource is wastewater residuals (sludge and biosolids) generated at the nation’s wastewater treatment plants (WWTPs). Conversion of this resource into transportation fuels could significantly contribute to the creation of a new domestic bioenergy and bioproduct industry, while providing an economically and environmentally sustainable alternative for current waste disposal practices. Hydrothermal liquefaction (HTL) is a process that uses hot, pressurized water in the condensed phase to convert biomass to a thermally stable oil product, also known as “biocrude”, which can then be thermo-catalytically upgraded to hydrocarbon fuel blendstocks. HTL is conceptually simple, has a high carbon efficiency, and can be applied to a wide range of wet feedstocks at similar processing conditions. The purpose of this report is to document the conceptual design, economics and supporting data for a sludge-to-fuel pathway via HTL and biocrude upgrading. The configuration includes a HTL plant that is co-located with a WWTP and a larger scale biocrude upgrading plant for production of hydrocarbon fuel blendstocks. Experimental data from bench scale testing of a 1:1 mixture of primary:secondary sludges are used to establish the economic and technical assumptions for the analysis. The design

  20. Evaporation from rain-wetted forest in relation to canopy wetness, canopy cover, and net radiation

    NARCIS (Netherlands)

    Klaassen, W.

    2001-01-01

    Evaporation from wet canopies is commonly calculated using E-PM, the Penman-Monteith equation with zero surface resistance. However, several observations show a lower evaporation from rain-wetted forest. Possible causes for the difference between E-PM and experiments are evaluated to provide rules

  1. Advanced methods for the treatment of organic aqueous wastes: wet air oxidation and wet peroxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Debellefontaine, Hubert; Chakchouk, Mehrez; Foussard, Jean Noel [Institut National des Sciences Appliquees (INSA), 31 - Toulouse (France). Dept. de Genie des Procedes Industriels; Tissot, Daniel; Striolo, Phillipe [IDE Environnement S.A., Toulouse (France)

    1993-12-31

    There is a growing concern about the problems of wastes elimination. Various oxidation techniques are suited for elimination of organic aqueous wastes, however, because of the environmental drawbacks of incineration, liquid phase oxidation should be preferred. `Wet Air Oxidation` and `Wet Peroxide Oxidation`are alternative processes which are discussed in this paper. 17 refs., 13 figs., 4 tabs.

  2. CONSTOR registered V/TC drop tests. Pre-test analysis by finite element method

    International Nuclear Information System (INIS)

    Voelzer, W.; Koenig, S.; Klein, K.; Tso, C.F.; Owen, S.; Monk, C.

    2004-01-01

    The CONSTOR registered family of steel-concrete-steel sandwich cask designs have been developed to fulfil both the internationally valid IAEA criteria for transportation and the requirements for long-term intermediate storage in the US and various European countries. A comprehensive drop testing programme using a full-scale prototype test cask (CONSTOR registered V/TC) has been developed as part of the application for a transport license in both Germany and the US. The drop tests using the full-scale cask will be performed by BAM at test facilities in Horstwalde. The tests will include five different 9m drops onto flat unyielding targets and seven different 1m drops onto a punch. The first drop test, a 9m side drop, will be performed during PATRAM 2004. The other drop tests will take place during the following year. The development of the cask design and the formulation of the drop test programme has been supported by an extensive series of finite element analyses. The objectives of the finite element analyses were; to provide an intermediate step in demonstrating the performance of the CONSTOR registered in fulfilling the requirements of 10 CFR 71 and the IAEA transport regulations. To justify the selection of drop tests. To predict the performance of V/TC during the drop tests. To estimate the strain and acceleration time histories at measuring points on the test cask and to aid in the setting up of the test instrumentation. To develop an analysis model that can be used in future safety analyses for transport and storage license applications and which can confidently be used to demonstrate the performance of the package. This paper presents an overview of the analyses performed, including a summary of all the different drop orientations that were considered. The major assumptions employed during the analyses are also discussed, as are the specifics of the modelling techniques that were employed. At the end of the paper, the key results obtained from the analyses

  3. Laplacian drop shapes and effect of random perturbations on accuracy of surface tension measurement for different drop constellations.

    Science.gov (United States)

    Saad, Sameh M I; Neumann, A Wilhelm

    2015-08-01

    Theoretical drop shapes are calculated for three drop constellations: pendant drops, constrained sessile drops, and unconstrained sessile drops. Based on total Gaussian curvature, shape parameter and critical shape parameter are discussed as a function of different drop sizes and surface tensions. The shape parameter is linked to physical parameters for every drop constellation. The as yet unavailable detailed dimensional analysis for the unconstrained sessile drop is presented. Results show that the unconstrained sessile drop shape depends on a dimensionless volume term and the contact angle. Random perturbations are introduced and the accuracy of surface tension measurement is assessed for precise and perturbed profiles of the three drop constellations. It is concluded that pendant drops are the best method for accurate surface tension measurement, followed by constrained sessile drops. The unconstrained sessile drops come last because they tend to be more spherical at low and moderate contact angles. Of course, unconstrained sessile drops are the only option if contact angles are to be measured. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Teknologi penyamakan kulit wet blue buaya

    Directory of Open Access Journals (Sweden)

    Bambang Oetojo

    1992-08-01

    Full Text Available For this study it was used 12 pieces of grain salted crocodile skin of 11 up to 14 inch width. All of the crocodile skin were process up to pickling with the same way. Furthermore pickled crocodile skins were process up to pickling with the same way. Furthermore pickled crocodile skins and was done twice. The wet blue output from the research was visual investigated for the coulor using staning scale method. For comparition it was used pickled crocodile skins. Statistical analysis pints out that there is unsignify difference (P<0.05 the influence of the used of basic chrome sulphate to the colour of wet blue crocodile skins. Practical meaning of the research is, for tanning of crocodile skins to the wet blue, it is used 1.5% basic chromium sulphate.

  5. Molecular Dynamics Simulations for Predicting Surface Wetting

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2014-06-01

    Full Text Available The investigation of wetting of a solid surface by a liquid provides important insights; the contact angle of a liquid droplet on a surface provides a quantitative measurement of this interaction and the degree of attraction or repulsion of that liquid type by the solid surface. Molecular dynamics (MD simulations are a useful way to examine the behavior of liquids on solid surfaces on a nanometer scale. Thus, we surveyed the state of this field, beginning with the fundamentals of wetting calculations to an examination of the different MD methodologies used. We highlighted some of the advantages and disadvantages of the simulations, and look to the future of computer modeling to understand wetting and other liquid-solid interaction phenomena.

  6. Handling of wet residues in industry

    DEFF Research Database (Denmark)

    Villanueva, Alejandro

    to water bodies and uses of such bodies, distance to available agricultural land, characteristics of the local wastewater treatment plant, local and national legislation, or availability of subsidies. This study uses as example the geographical, legislative, economic and social boundary conditions......In countries with high prices of fresh water use and wastewater discharge, water recycling has become an alternative to traditional water consumption and discharge for industries with water-based processes. Industrial water recycling means in many cases that water has to be treated and cleaned......, to remove from it the substances which presence impedes reusing the water. These substances accumulate in a by-product called wet residue. An integral part of water recycling projects in the industry is the handling and disposal of the wet residues generated. The treatment, utilisation and disposal of wet...

  7. Fatigue Performance of SFPSC under Hot-Wet Environments and Cyclic Bending Loads

    Directory of Open Access Journals (Sweden)

    Shanshan Luo

    2018-01-01

    Full Text Available A new structural material named “steel fiber polymer structural concrete (SFPSC” with features of both high strength and high toughness was developed by this research group and applied to the bridge superstructures in the hot-wet environments. In order to investigate the fatigue performance and durability of SFPSC under hot-wet environments, the environment and fatigue load uncoupling method and the coupling action of environment and fatigue load were used or developed. Three-point bending fatigue experiments with uncoupling action of environments and cyclic loads were carried out for SFPSC specimens which were pretreated under hot-wet environments, and the experiments with the coupling action of environments and cyclic loads for SFPSC specimens were carried out under hot-wet environments. Then, the effects of hot-wet environments and the experimental methods on the fatigue mechanism of SFPSC material were discussed, and the environmental fatigue equations of SFPSC material under coupling and uncoupling action of hot-wet environments and cyclic bending loads were established. The research results show that the fatigue limits of SFPSC under the coupling action of the environments and cyclic loads were lower about 15%. The proposed fatigue equations could be used to estimate the fatigue lives and fatigue limits of SFPSC material.

  8. Sphere impact and penetration into wet sand

    KAUST Repository

    Marston, J. O.

    2012-08-07

    We present experimental results for the penetration of a solid sphere when released onto wet sand. We show, by measuring the final penetration depth, that the cohesion induced by the water can result in either a deeper or shallower penetration for a given release height compared to dry granular material. Thus the presence of water can either lubricate or stiffen the granular material. By assuming the shear rate is proportional to the impact velocity and using the depth-averaged stopping force in calculating the shear stress, we derive effective viscosities for the wet granular materials.

  9. Rolling viscous drops on a non-wettable surface containing both micro- and macro-scale roughness

    Science.gov (United States)

    Abolghasemibizaki, Mehran; Robertson, Connor J.; Fergusson, Christian P.; McMasters, Robert L.; Mohammadi, Reza

    2018-02-01

    It has previously been shown that when a liquid drop of high viscosity is placed on a non-wettable inclined surface, it rolls down at a constant descent velocity determined by the balance between viscous dissipation and the reduction rate of its gravitational potential energy. Since increasing the roughness of the surface boosts its non-wetting property, the drop should move faster on a surface structured with macrotextures (ribbed surface). Such a surface was obtained from a superhydrophobic soot coating on a solid specimen printed with an extruder-type 3D printer. The sample became superoleophobic after a functionalization process. The descent velocity of glycerol drops of different radii was then measured on the prepared surface for varied tilting angles. Our data show that the drops roll down on the ribbed surface approximately 27% faster (along the ridges) than on the macroscopically smooth counterpart. This faster velocity demonstrates that ribbed surfaces can be promising candidates for drag-reduction and self-cleaning applications. Moreover, we came up with a modified scaling model to predict the descent velocity of viscous rolling drops more accurately than what has previously been reported in the literature.

  10. Thermal dimensioning of wet natural draft cooling systems

    International Nuclear Information System (INIS)

    Bourillot, Claudine.

    1975-01-01

    The conventional models of calculating wet natural draft cooling systems include two different parts. First, the thermal calculation of the dispersion is made either with an ''exact'' method of separating convection and evaporation phenomena and taking account for the steam in exces in the saturated air, or with a ''simplified'' method considering the heat transfer in the whole as resulting of a difference in enthalpies. (The latter is the Merkel theory). Secondly, the draft equation is solved for calculating air flow rate. Values of the mass transfer coefficients and pressure drops of the dispersion being needed for the computation, test bench measurements are made by the designers. As for counter-current cooling systems the models of the dispersion calculation are one-dimensional models not allowing the radial flow and air temperature distributions to be simulated; exchanges inside the rain zone are also neglected. As for crossed-current cooling systems the flow geometry entails a more complicated two-dimensional model to be used for the dispersion. In both cases, the dependence on meteorological factors such as wind, height gradients of temperature, or sunny features are disregarded [fr

  11. Manipulating the voltage drop in graphene nanojunctions using a gate potential

    DEFF Research Database (Denmark)

    Papior, Nick Rübner; Gunst, Tue; Stradi, Daniele

    2016-01-01

    the impact of electrostatic gating in nanojunctions between graphene electrodes operating at finite bias. Using first principles quantum transport simulations, we show that the voltage drop across \\emph{symmetric} junctions changes dramatically and controllably in gated systems compared to non...... of graphene in the proximity of the Dirac point. Due to the electrostatic gating, each electrode exposes different density of states in the bias window between the two different electrode Fermi energies, thereby leading to a non-symmetry in the voltage drop across the device. This selective pinning is found...

  12. Drying drops : Drying drops containing solutes: From hydrodynamical to mechanical instabilities.

    Science.gov (United States)

    Giorgiutti-Dauphiné, F; Pauchard, L

    2018-03-19

    The drying of complex fluids involves a large number of microscopic phenomena (transport and organization of non-volatile solutes) as well as hydrodynamic and mechanical instabilities. These phenomena can be captured in drying sessile drops where different domains can be identified: strong concentration gradients, formation of a glassy or porous envelope that withstands mechanical stress, and consolidation of a layer strongly adhering to the substrate at the drop edge. In colloidal systems, we quantify the evolution of the particle volume fraction at a nanometric scale and microscopic scale and identify the conditions for the envelope formation at the free surface by balancing the effect of diffusion and evaporation. When a solid envelope is formed at a drop surface, the mechanical instabilities induced by the drying result in different drop shapes. Finally, large drying stresses build up in the solid layer adhering on the substrate, and possibly cause crack formation. In particular, we study how crack patterns are affected by the contact angle of drops and the drying conditions. A particular interest of the review is devoted to drying pattern of solutes.

  13. Simplified procedure for determining of drop and stilling basin

    Directory of Open Access Journals (Sweden)

    Ali R. Vatankhah

    2014-03-01

    Full Text Available Drops are used to effectively dissipate the surplus energy of the water flow. A closed conduit drop conveys water and stills it at its downstream. I-type pipe drop is one kind of the closed conduit drops which is used in irrigation networks as a typical hydraulic structure. Sump elevation is an important design parameter for I-type pipe drop. Similarly, in supercritical flow structures, such as open channel chutes, determination of stilling basin invert elevation is very important. At present, these key design parameters are determined by the momentum and energy equations using tedious trial-and-error procedure. In this study, square conduit drop, pipe drop, and rectangular stilling basin are considered, and three explicit equations have been developed by (multiple nonlinear regression technique to determine the sump and stilling basin invert elevations. Being very simple and accurate, these equations can be easily used to design the closed conduit drops and stilling basins by hydraulic engineers.

  14. Determination of optimal formulation for extrusion granulation by compression test of wet kneaded mass.

    Science.gov (United States)

    Ohnishi, Yoshito; Okamoto, Takumi; Watano, Satoru

    2004-10-01

    The purpose of this study is to propose the application of a compression test to the determination of an optimal formulation for extrusion granulation. The electric current during extrusion was measured and the characteristics of the wet kneaded mass in the compression test were analyzed under various operating conditions, with different types of extruders and several formulations of kneaded mass. It was found that addition of a binder (HPC-L) to pharmaceutical powders lowered the load of a high-compressing type extruder, since the binder reduced the friction among the wet mass during extrusion. Also, the support stress was found to be proportional to the compression pressure without a binder, although an inflection point appeared on the support stress curve when a binder was present. This inflection point suggested large water retention of the wet kneaded mass, at which the medium of pressure was changed from a discontinuous solid powder to a continuous liquid, and large water retention contributed to the low friction of the wet mass. The friction of the wet kneaded mass and the aptitude of the formulation for extrusion were understood by using the compression test. The compression test is a very useful procedure at the first stage of a formulation study.

  15. Evaluation of the nugget diameter in spot welded joints between two steel sheets by means of a potential drop technique

    Science.gov (United States)

    Tohmyoh, Hironori; Ikarashi, Hidetomo; Matsui, Yoichi; Hasegawa, Yuta; Obara, Satoshi

    2015-08-01

    A potential drop technique which utilizes the electrical circuit used in resistance spot welding is reported. Spot welded samples comprising two steel sheets were inserted between the two Cu electrodes and a constant direct current was supplied between the electrodes. The potential drop between two points, one on each electrode, was determined by analysis for various values of nugget diameter and various values of the contact resistance between the Cu electrodes and the steel sheet sample. The nugget diameter of the spot welded joint could be quantitatively evaluated from the measured potential drop and the equation obtained from the analysis.

  16. Process Analytical Technology for High Shear Wet Granulation: Wet Mass Consistency Reported by In-Line Drag Flow Force Sensor Is Consistent With Powder Rheology Measured by At-Line FT4 Powder Rheometer.

    Science.gov (United States)

    Narang, Ajit S; Sheverev, Valery; Freeman, Tim; Both, Douglas; Stepaniuk, Vadim; Delancy, Michael; Millington-Smith, Doug; Macias, Kevin; Subramanian, Ganeshkumar

    2016-01-01

    Drag flow force (DFF) sensor that measures the force exerted by wet mass in a granulator on a thin cylindrical probe was shown as a promising process analytical technology for real-time in-line high-resolution monitoring of wet mass consistency during high shear wet granulation. Our previous studies indicated that this process analytical technology tool could be correlated to granulation end point established independently through drug product critical quality attributes. In this study, the measurements of flow force by a DFF sensor, taken during wet granulation of 3 placebo formulations with different binder content, are compared with concurrent at line FT4 Powder Rheometer characterization of wet granules collected at different time points of the processing. The wet mass consistency measured by the DFF sensor correlated well with the granulation's resistance to flow and interparticulate interactions as measured by FT4 Powder Rheometer. This indicated that the force pulse magnitude measured by the DFF sensor was indicative of fundamental material properties (e.g., shear viscosity and granule size/density), as they were changing during the granulation process. These studies indicate that DFF sensor can be a valuable tool for wet granulation formulation and process development and scale up, as well as for routine monitoring and control during manufacturing. Copyright © 2016. Published by Elsevier Inc.

  17. Partial coalescence from bubbles to drops

    KAUST Repository

    Zhang, F. H.

    2015-10-07

    The coalescence of drops is a fundamental process in the coarsening of emulsions. However, counter-intuitively, this coalescence process can produce a satellite, approximately half the size of the original drop, which is detrimental to the overall coarsening. This also occurs during the coalescence of bubbles, while the resulting satellite is much smaller, approximately 10 %. To understand this difference, we have conducted a set of coalescence experiments using xenon bubbles inside a pressure chamber, where we can continuously raise the pressure from 1 up to 85 atm and thereby vary the density ratio between the inner and outer fluid, from 0.005 up to unity. Using high-speed video imaging, we observe a continuous increase in satellite size as the inner density is varied from the bubble to emulsion-droplet conditions, with the most rapid changes occurring as the bubble density grows up to 15 % of that of the surrounding liquid. We propose a model that successfully relates the satellite size to the capillary wave mode responsible for its pinch-off and the overall deformations from the drainage. The wavelength of the primary wave changes during its travel to the apex, with the instantaneous speed adjusting to the local wavelength. By estimating the travel time of this wave mode on the bubble surface, we also show that the model is consistent with the experiments. This wavenumber is determined by both the global drainage as well as the interface shapes during the rapid coalescence in the neck connecting the two drops or bubbles. The rate of drainage is shown to scale with the density of the inner fluid. Empirically, we find that the pinch-off occurs when 60 % of the bubble fluid has drained from it. Numerical simulations using the volume-of-fluid method with dynamic adaptive grid refinement can reproduce these dynamics, as well as show the associated vortical structure and stirring of the coalescing fluid masses. Enhanced stirring is observed for cases with second

  18. Update on the Purdue University 2-second Drop Tower

    Science.gov (United States)

    Collicott, Steven

    an update on progress for the micro-gravity community. The most noticeable current activity is testing of the air-bag decelerator. The tower is one that will use a free-falling experiment inside of a drag shield to avoid most aerodynamic drag. The airbag is designed from experiences of others yet the small, triangular room in which the tower terminates imposes challenges. The airbag is approximately 1.5m diameter and 1.5m tall. Initial testing led to a desire to increase vent area, and just this week the bag has returned from the shop that was modifying it. On-board computer, battery packs, lighting, and cameras have been acquired. Thanks to Lockheed Martin, one camera is 500 frames per second with 1.3 million 12-bit gray scale pixels per frame. The Spincraft company donated steel hemisphere-cylinders to serve as the nose of the drag shield. Wind tunnel and CFD modeling of the drag shield has been performed by Purdue undergraduate aerospace students. Currently the drag shield structure and experiment package structure are being design and analyzed. The experiment volume is approximately a cylinder 0.45m diameter and 0.6m tall. Tower operation is intended to commence in fall 2010 with inert package drops at full mass and full height. Developing the operations procedures, especially operational safety, are the goals of this work. First science is then expected in the winter. References 1. Y. Chen, "A Study of Capillary Flow in a Vane-wall Gap in Zero Gravity," Ph.D. thesis, School of Aeronautics and Astronautics, Purdue University. August 2003. 2. Y. Chen and S. H. Collicott, "Investigation of the Symmetric Wetting of a Vane-Wall Gap in Propellant Tanks," AIAA Journal, 42, No. 2, pp. 305-314, February 2004. 3. Y. Chen, and S. H. Collicott, "Experimental Study on the Capillary Flow in a Vane-Wall Gap Geometry," AIAA Journal, 43, No. 11, pp. 2395-2403, November, 2005. 4. Y. Chen and S. H. Collicott, "Study of Wetting in an Asymmetrical Vane-Wall Gap in Propellant Tanks

  19. Temporal sequencing of throughfall drop generation as revealed by use of a large-scale rainfall simulator

    Science.gov (United States)

    Nanko, K.; Levia, D. F., Jr.; Iida, S.; SUN, X.; Shinohara, Y.; Sakai, N.

    2017-12-01

    Scientists have been interested in throughfall drop size and its distribution because of its importance to soil erosion and the forest water balance. An indoor experiment was employed to deepen our understanding of throughfall drop generation processes to promote better management of forested ecosystems. The indoor experiment provides a unique opportunity to examine an array of constant rainfall intensities that are ideal conditions to pick up the effect of changing intensities and not found in the fields. Throughfall drop generation was examined for three species- Cryptomeria japonica D. Don (Japanese cedar), Chamaecyparis obtusa (Siebold & Zucc.) Endl. (Japanese cypress), and Zelkova serrata Thunb. (Japanese zelkova)- under both leafed and leafless conditions in the large-scale rainfall simulator in the National Research Institute for Earth Science and Disaster Resilience (Tsukuba, Japan) at varying rainfall intensities ranging from15 to 100 mm h-1. Drop size distributions of the applied rainfall and throughfall were measured simultaneously by 20 laser disdrometers. Utilizing the drop size dataset, throughfall was separated into three components: free throughfall, canopy drip, and splash throughfall. The temporal sequencing of the throughfall components were analyzed on a 1-min interval during each experimental run. The throughfall component percentage and drop size of canopy drip differed among tree species and rainfall intensities and by elapsed time from the beginning of the rainfall event. Preliminary analysis revealed that the time differences to produce branch drip as compared to leaf (or needle) drip was partly due to differential canopy wet-up processes and the disappearance of branch drips due to canopy saturation, leading to dissimilar throughfall drop size distributions beneath the various tree species examined. This research was supported by JSPS Invitation Fellowship for Research in Japan (Grant No.: S16088) and JSPS KAKENHI (Grant No.: JP15H05626).

  20. Delayed Frost Growth on Jumping-Drop Superhydrophobic Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Boreyko, Jonathan B [ORNL; Collier, Pat [ORNL

    2013-01-01

    Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an inter-drop frost wave. The growth of this inter-drop frost front is shown to be up to three times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of inter-drop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an inter-drop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser was found to be superior to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by minimizing the success of interdrop ice bridge formation.

  1. Preparation and Stability of Voriconazole Eye Drop Solution▿

    OpenAIRE

    Dupuis, Antoine; Tournier, Nicolas; Le Moal, Gwenaël; Venisse, Nicolas

    2008-01-01

    The combined systemic and topical administration of voriconazole has successfully been used to treat keratomycosis. Because no voriconazole eye drop product is commercially available, we prepared a sterile eye drop solution (10 mg/ml). Voriconazole remains stable over 30 days, providing an eye drop solution suitable for use for the topical treatment of fungal keratitis.

  2. Spent Nuclear Fuel (SNF) Bounding Drop Support Calculations

    Energy Technology Data Exchange (ETDEWEB)

    CHENAULT, D.M.

    1999-11-16

    This report evaluates different drop heights, concrete and other impact media to which the transport package and/or the MCO is dropped. A prediction method is derived for estimating the resultant impact factor for determining the bounding drop case for the SNF Project.

  3. Inverse Leidenfrost Effect: Levitating Drops on Liquid Nitrogen.

    Science.gov (United States)

    Adda-Bedia, M; Kumar, S; Lechenault, F; Moulinet, S; Schillaci, M; Vella, D

    2016-05-03

    We explore the interaction between a liquid drop (initially at room temperature) and a bath of liquid nitrogen. In this scenario, heat transfer occurs through film-boiling: a nitrogen vapor layer develops that may cause the drop to levitate at the bath surface. We report the phenomenology of this inverse Leidenfrost effect, investigating the effect of the drop size and density by using an aqueous solution of a tungsten salt to vary the drop density. We find that (depending on its size and density) a drop either levitates or instantaneously sinks into the bulk nitrogen. We begin by measuring the duration of the levitation as a function of the radius R and density ρd of the liquid drop. We find that the levitation time increases roughly linearly with drop radius but depends weakly on the drop density. However, for sufficiently large drops, R ≥ Rc(ρd), the drop sinks instantaneously; levitation does not occur. This sinking of a (relatively) hot droplet induces film-boiling, releasing a stream of vapor bubbles for a well-defined length of time. We study the duration of this immersed-drop bubbling finding similar scalings (but with different prefactors) to the levitating drop case. With these observations, we study the physical factors limiting the levitation and immersed-film-boiling times, proposing a simple model that explains the scalings observed for the duration of these phenomena, as well as the boundary of (R,ρd) parameter space that separates them.

  4. Dynamics of the vapor layer below a Leidenfrost drop.

    Science.gov (United States)

    Caswell, Thomas A

    2014-07-01

    In the Leidenfrost effect a small drop of fluid is levitated, above a sufficiently hot surface, on a persistent vapor layer generated by evaporation from the drop. The vapor layer thermally insulates the drop from the surface leading to extraordinarily long drop lifetimes. The top-view shape of the levitated drops can exhibit persistent starlike vibrations. I extend recent work [Burton et al., Phys. Rev. Lett. 109, 074301 (2012)] to study the bottom surface of the drop using interference imaging. In this work I use a high-speed camera and automated image analysis to image, locate, and classify the interference fringes. From the interference fringes I reconstruct the shape and height profile of the rim where the drop is closest to the surface. I measure the drop-size dependence of the planar vibrational mode frequencies, which agree well with previous work. I observe a distinct breathing mode in the average radius of the drop, the frequency of which scales differently with drop size than the other modes. This breathing mode can be tightly coupled to a vertical motion of the drop. I further observe a qualitative difference in the structure and dynamics of the vertical profile of the rim between large and small drops.

  5. The evaporation of the charged and uncharged water drops ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Oscillations of the drop and the change in airflow around drops are suggested to contribute to lowering of the ventilation coefficients for charged drops. Applicability of the results to a small fraction of highly charged raindrops falling through the sub-cloud layer below thunderstorm is discussed. The relaxation time required for ...

  6. Spent Nuclear Fuel (SNF) Bounding Drop Support Calculations

    International Nuclear Information System (INIS)

    CHENAULT, D.M.

    1999-01-01

    This report evaluates different drop heights, concrete and other impact media to which the transport package and/or the MCO is dropped. A prediction method is derived for estimating the resultant impact factor for determining the bounding drop case for the SNF Project

  7. Catalytic gasification of dry and wet biomass

    NARCIS (Netherlands)

    van Rossum, G.; Potic, B.; Kersten, Sascha R.A.; van Swaaij, Willibrordus Petrus Maria

    2009-01-01

    Catalytic gasification of dry biomass and of wet biomass streams in hot compressed water are reviewed and discussed as potential technologies for the production of synthesis gas, hydrogen- and methane-rich gas. Next to literature data also new experimental results from our laboratory on catalytic

  8. Microwave moisture sensing of wet bales

    Science.gov (United States)

    Sensing of moisture in very wet lint bales is unique due to the fact that moisture distribution is typically non-uniform and can in some instances be highly localized. This issue is even further complicated by the use of a sensor that reads only a portion of the bale and/or with a sensor that provid...

  9. Verification of wet blasting decontamination technology

    International Nuclear Information System (INIS)

    Matsubara, Sachito; Murayama, Kazunari; Yoshida, Hirohisa; Igei, Shigemitsu; Izumida, Tatsuo

    2013-01-01

    Macoho Co., Ltd. participated in the projects of 'Decontamination Verification Test FY 2011 by the Ministry of the Environment' and 'Decontamination Verification Test FY 2011 by the Cabinet Office.' And we tested verification to use a wet blasting technology for decontamination of rubble and roads contaminated by the accident of Fukushima Daiichi Nuclear Power Plant of the Tokyo Electric Power Company. As a results of the verification test, the wet blasting decontamination technology showed that a decontamination rate became 60-80% for concrete paving, interlocking, dense-grated asphalt pavement when applied to the decontamination of the road. When it was applied to rubble decontamination, a decontamination rate was 50-60% for gravel and approximately 90% for concrete and wood. It was thought that Cs-134 and Cs-137 attached to the fine sludge scraped off from a decontamination object and the sludge was found to be separated from abrasives by wet cyclene classification: the activity concentration of the abrasives is 1/30 or less than the sludge. The result shows that the abrasives can be reused without problems when the wet blasting decontamination technology is used. (author)

  10. Aqueous Wetting Films on Fused Quartz.

    Science.gov (United States)

    Mazzoco; Wayner

    1999-06-15

    Using an image analyzing interferometer, IAI, the interfacial characteristics of an isothermal constrained vapor bubble, CVB, in a quartz cuvette were studied as a precursor to heat transfer research. The effects of pH and electrolyte concentration on the meniscus properties (curvature and adsorbed film thickness) and the stability of the aqueous wetting films were evaluated. The surface potential in the electric double layer was a function of the cleaning and hydroxylation of the quartz surface. The disjoining pressure isotherm for pure water was very close to that predicted by the Langmuir equation. For aqueous solutions of moderate electrolyte concentration, the Gouy-Chapman theory provided a good representation of the electrostatic effects in the film. The effect of temperature on the film properties of aqueous solutions and pure water was also evaluated: The meniscus curvature decreased with increasing temperature, while Marangoni effects, intermolecular forces, and local evaporation and condensation enhanced waves on the adsorbed film layer. Pure water wetting films were mechanically metastable, breaking into droplets and very thin films (less than 10 nm) after a few hours. Aqueous wetting films with pH 12.4 proved to be stable during a test of several months, even when subjected to temperature and mechanical perturbations. The mechanical stability of wetting films can explain the reported differences between the critical heat fluxes of pure water and aqueous solutions. The IAI-CVB technique is a simple and versatile experimental technique for studying the characteristics of interfacial systems. Copyright 1999 Academic Press.

  11. Cohesion and agglomeration of wet powders

    Science.gov (United States)

    Raux, Pascal S.; Biance, Anne-Laure

    2018-01-01

    Wet high-shear granulation consists in vigorously mixing grains and a liquid binder to create agglomerates of various sizes. The process results from a balance between cohesion of the wet granular agglomerates and fragmentation due to the high mixing. By performing a simple test with glass beads and various liquids, we first focus on the static cohesion of wet granular media. Contrary to previous works, we extend the study to larger values of the liquid fraction w . After the well-documented plateau, the cohesive strength increases again with w , a behavior we capture by a simple model. We then focus on the dynamical cohesion of the media and we design an agglomeration process that consists in vibrating a bead/liquid mixture at a large amplitude. The vibrations induce not only the fluidization of the wet granular material but also the formation of aggregates. As expected, their size is affected by the liquid content, the frequency, and the amplitude of the vibrations, similarly to high-shear granulation data. However, the number of beads in an agglomerate does not depend on the bead size, showing a self-similar mechanism of agglomeration. The role of the static cohesion strength in this dynamical process remains therefore ambiguous.

  12. Wet steam turbines for CANDU-Reactors

    International Nuclear Information System (INIS)

    Westmacott, C.H.L.

    1977-01-01

    The technical characteristics of 4 wet steam turbine aggregates used in the Pickering nuclear power station are reported on along with operational experience. So far, the general experience was positive. Furthermore, plans are mentioned to use this type of turbines in other CANDU reactors. (UA) [de

  13. Wetting at the nanometer scale: effects of long-range forces and substrate heterogeneities

    International Nuclear Information System (INIS)

    Checco, Antonio

    2003-01-01

    Wetting phenomena on the nano-scale remain poorly understood in spite of their growing theoretical and practical interest. In this context, the present work aimed at studying partial wetting of nanometer-sized alkane droplets on 'model' surfaces build by self-assembly of organic monolayers. For this purpose a novel technique, based on 'noncontact' Atomic Force Microscopy (AFM), has been developed to image, with minimal artefacts, drops of adjustable size directly condensed on so- lid surfaces. We have thus shown that contact angle of alkanes, wetting a weakly heterogeneous, silanized substrate, noticeably decreases from its macroscopic value for droplets sizes in the submicron range. The line tension, arising in this case from purely dispersive long-range interactions between the liquid and the substrate, is theoretically too weak to be responsible for the observed effect. Therefore we have supposed that contact angle is affected by mesoscopic chemical heterogeneities of the substrate whenever the droplets size becomes sufficiently small. This scenario has been supported by numerical simulations based on a simplified model of the spatial distribution of surface defects. Similar experiments, performed on different substrates (monolayers made of alkane-thiols self-assembled on gold and of alkyl chains covalently bound onto a silicon surface), have also shown that wetting on small scales is strongly affected by minimal physical and chemical surface heterogeneities. Finally, to provide further examples of the potential of the above mentioned AFM technique, we have studied the wettability of nano-structured surfaces and the local wetting properties of hair. (author) [fr

  14. Characterization of highly hydrophobic textiles by means of X-ray microtomography, wettability analysis and drop impact

    Science.gov (United States)

    Santini, M.; Guilizzoni, M.; Fest-Santini, S.; Lorenzi, M.

    2017-11-01

    Highly hydrophobic surfaces have been intensively investigated in the last years because their properties may lead to very promising technological spillovers encompassing both everyday use and high-tech fields. Focusing on textiles, hydrophobic fabrics are of major interest for applications ranging from clothes to architecture to environment protection and energy conversion. Gas diffusion media - made by a gas diffusion layer (GDL) and a microporous layer (MPL) - for fuel cells are a good benchmark to develop techniques aimed at characterizing the wetting performances of engineered textiles. An experimental investigation was carried out about carbon-based, PTFE-treated GDLs with and without MPLs. Two samples (woven and woven-non-woven) were analysed before and after coating with a MPL. Their three-dimensional structure was reconstructed and analysed by computer-aided X-ray microtomography (µCT). Static and dynamic wettability analyses were then carried out using a modified axisymmetric drop shape analysis technique. All the surfaces exhibited very high hydrophobicity, three of them near to a super-hydrophobic behavior. Water drop impacts were performed, evidencing different bouncing, sticking and fragmentation outcomes for which critical values of the Weber number were identified. Finally, a µCT scan of a drop on a GDL was performed, confirming the Cassie-Baxter wetting state on such surface.

  15. Drop Distribution Determination in a Liquid-Liquid Dispersion by Image Processing

    Directory of Open Access Journals (Sweden)

    Luís M. R. Brás

    2009-01-01

    Full Text Available This paper presents the implementation of an algorithm for automatic identification of drops with different sizes in monochromatic digitized frames of a liquid-liquid chemical process. These image frames were obtained at our Laboratory, using a nonintrusive process, with a digital video camera, a microscope, and an illumination setup from a dispersion of toluene in water within a transparent mixing vessel. In this implementation, we propose a two-phase approach, using a Hough transform that automatically identifies drops in images of the chemical process. This work is a promising starting point for the possibility of performing an automatic drop classification with good results. Our algorithm for the analysis and interpretation of digitized images will be used for the calculation of particle size and shape distributions for modelling liquid-liquid systems.

  16. Calculation of water drop trajectories to and about arbitrary three-dimensional lifting and nonlifting bodies in potential airflow

    Science.gov (United States)

    Norment, H. G.

    1985-01-01

    Subsonic, external flow about nonlifting bodies, lifting bodies or combinations of lifting and nonlifting bodies is calculated by a modified version of the Hess lifting code. Trajectory calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Inlet flow can be accommodated, and high Mach number compressibility effects are corrected for approximately. Seven codes are described: (1) a code used to debug and plot body surface description data; (2) a code that processes the body surface data to yield the potential flow field; (3) a code that computes flow velocities at arrays of points in space; (4) a code that computes water drop trajectories from an array of points in space; (5) a code that computes water drop trajectories and fluxes to arbitrary target points; (6) a code that computes water drop trajectories tangent to the body; and (7) a code that produces stereo pair plots which include both the body and trajectories. Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.

  17. Wet Deposition Flux of Reactive Organic Carbon

    Science.gov (United States)

    Safieddine, S.; Heald, C. L.

    2016-12-01

    Reactive organic carbon (ROC) is the sum of non-methane volatile organic compounds (NMVOCs) and primary and secondary organic aerosols (OA). ROC plays a key role in driving the chemistry of the atmosphere, affecting the hydroxyl radical concentrations, methane lifetime, ozone formation, heterogeneous chemical reactions, and cloud formation, thereby impacting human health and climate. Uncertainties on the lifecycle of ROC in the atmosphere remain large. In part this can be attributed to the large uncertainties associated with the wet deposition fluxes. Little is known about the global magnitude of wet deposition as a sink of both gas and particle phase organic carbon, making this an important area for research and sensitivity testing in order to better understand the global ROC budget. In this study, we simulate the wet deposition fluxes of the reactive organic carbon of the troposphere using a global chemistry transport model, GEOS-Chem. We start by showing the current modeled global distribution of ROC wet deposition fluxes and investigate the sensitivity of these fluxes to variability in Henry's law solubility constants and spatial resolution. The average carbon oxidation state (OSc) is a useful metric that depicts the degree of oxidation of atmospheric reactive carbon. Here, we present for the first time the simulated gas and particle phase OSc of the global troposphere. We compare the OSc in the wet deposited reactive carbon flux and the dry deposited reactive carbon flux to the OSc of atmospheric ROC to gain insight into the degree of oxidation in deposited material and, more generally, the aging of organic material in the troposphere.

  18. Model of an Evaporating Drop Experiment

    Science.gov (United States)

    Rodriguez, Nicolas

    2017-11-01

    A computational model of an experimental procedure to measure vapor distributions surrounding sessile drops is developed to evaluate the uncertainty in the experimental results. Methanol, which is expected to have predominantly diffusive vapor transport, is chosen as a validation test for our model. The experimental process first uses a Fourier transform infrared spectrometer to measure the absorbance along lines passing through the vapor cloud. Since the measurement contains some errors, our model allows adding random noises to the computational integrated absorbance to mimic this. Then the resulting data are interpolated before passing through a computed tomography routine to generate the vapor distribution. Next, the gradients of the vapor distribution are computed along a given control volume surrounding the drop so that the diffusive flux can be evaluated as the net rate of diffusion out of the control volume. Our model of methanol evaporation shows that the accumulated errors of the whole experimental procedure affect the diffusive fluxes at different control volumes and are sensitive to how the noisy data of integrated absorbance are interpolated. This indicates the importance of investigating a variety of data fitting methods to choose which is best to present the data. Trinity University Mach Fellowship.

  19. Vlasov simulations of parallel potential drops

    Directory of Open Access Journals (Sweden)

    H. Gunell

    2013-07-01

    Full Text Available An auroral flux tube is modelled from the magnetospheric equator to the ionosphere using Vlasov simulations. Starting from an initial state, the evolution of the plasma on the flux tube is followed in time. It is found that when applying a voltage between the ends of the flux tube, about two thirds of the potential drop is concentrated in a thin double layer at approximately one Earth radius altitude. The remaining part is situated in an extended region 1–2 Earth radii above the double layer. Waves on the ion timescale develop above the double layer, and they move toward higher altitude at approximately the ion acoustic speed. These waves are seen both in the electric field and as perturbations of the ion and electron distributions, indicative of an instability. Electrons of magnetospheric origin become trapped between the magnetic mirror and the double layer during its formation. At low altitude, waves on electron timescales appear and are seen to be non-uniformly distributed in space. The temporal evolution of the potential profile and the total voltage affect the double layer altitude, which decreases with an increasing field aligned potential drop. A current–voltage relationship is found by running several simulations with different voltages over the system, and it agrees with the Knight relation reasonably well.

  20. Visualization of the impact of water drops on a hot surface: effect of drop velocity and surface inclination

    Energy Technology Data Exchange (ETDEWEB)

    Celata, Gian Piero; Mariani, Andrea; Zummo, Giuseppe [ENEA, Institute of Thermal-Fluid Dynamics, S. Maria di Galeria (Rome) (Italy); Cumo, Maurizio [Universita di Roma ' ' La Sapienza' ' , Rome (Italy)

    2006-08-15

    The behaviour of one drop impinging on a hot surface by varying the surface temperature, the drop velocity and the position of the surface (horizontal and a inclined 45 ) both at a temperature below and above the Leidenfrost temperature has been experimentally evaluated, estimating the temperature at which the drop rebounds. A large influence on the drop velocity has been evidenced. The inclination of the surface decreases the critical value of the temperature above which the surface is not rewetted. (orig.)

  1. Venturi Wet Gas Flow Modeling Based on Homogeneous and Separated Flow Theory

    Directory of Open Access Journals (Sweden)

    Xu Ying

    2008-10-01

    Full Text Available When Venturi meters are used in wet gas, the measured differential pressure is higher than it would be in gas phases flowing alone. This phenomenon is called over-reading. Eight famous over-reading correlations have been studied by many researchers under low- and high-pressure conditions, the conclusion is separated flow model and homogeneous flow model performing well both under high and low pressures. In this study, a new metering method is presented based on homogeneous and separated flow theory; the acceleration pressure drop and the friction pressure drop of Venturi under two-phase flow conditions are considered in new correlation, and its validity is verified through experiment. For low pressure, a new test program has been implemented in Tianjin University’s low-pressure wet gas loop. For high pressure, the National Engineering Laboratory offered their reports on the web, so the coefficients of the new proposed correlation are fitted with all independent data both under high and low pressures. Finally, the applicability and errors of new correlation are analyzed.

  2. Deformed liquid marbles: Freezing drop oscillations with powders

    KAUST Repository

    Marston, Jeremy

    2012-09-01

    In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

  3. Wet adhesion and adhesive locomotion of snails on anti-adhesive non-wetting surfaces.

    Directory of Open Access Journals (Sweden)

    Neil J Shirtcliffe

    Full Text Available Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted, texture (smooth, rough or granular or wetting property (hydrophilic or hydrophobic via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces.

  4. Wet adhesion and adhesive locomotion of snails on anti-adhesive non-wetting surfaces.

    Science.gov (United States)

    Shirtcliffe, Neil J; McHale, Glen; Newton, Michael I

    2012-01-01

    Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted), texture (smooth, rough or granular) or wetting property (hydrophilic or hydrophobic) via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces.

  5. Stator winding service life analysis of wet winding motor RCP

    International Nuclear Information System (INIS)

    Yeoh Eingyee; Li Linsen; Wang Ziguan; Shen Feng

    2017-01-01

    The reactor coolant pump type RUV of KSB is specially designed for the Westinghouse AP1000 reactor. It is hermetically sealed, wet winding motor pump. This wet winding motor concept has higher efficiency as compared to a canned motor since there are no eddy current losses, but this makes the stator cable insulator face the challenge of degradation by γ-irradiation in coolant. Radiation dose at the RUV is evaluated in interest from the material degradation point of view and the service life of stator winding in RUV is preliminarily analyzed. The values obtained are less than the dose rate and the dose which change the mechanical properties of the insulator material. According to the preliminary analysis, it can be concluded that the degradation of cable insulator of stator winding by γ-irradiation in coolant is negligible for the 60 years' service life of reactor coolant pump. This result also ensures crosslinked polyethylene used as cable insulator of stator winding is reliable in reactor coolant pump. (author)

  6. Optical Detection and Magnetic Manipulation of Drops in Microfluidic Devices

    Science.gov (United States)

    Kerbage, Charles

    2005-03-01

    We demonstrate an integrated magneto-optic microfluidic device for drop detection and sorting. Optical detection of water drops formed in a continuous oil phase flow is performed using optical fibers which are integrated into the channels of the PDMS (Polydimethylsiloxane) based microfluidic device. The size and the velocity of the drops can be determined by measuring the transmission intensity as a function of time. We also show that such a device can be used to detect fluorescent materials introduced in the drop itself. Moreover, introducing nano-scale magnetic particles into the water drops allows for drop sorting by means of a magnetic field gradient. This magnetic field is generated through thin film permalloy integrated into the device itself and tuned by an external coil. We show that the sorting depends on the magnetic field gradient, material composite and volume fraction of the magnetic material in the drops.

  7. Jumps, somersaults, and symmetry breaking in Leidenfrost drops

    Science.gov (United States)

    Chen, Simeng; Bertola, Volfango

    2016-08-01

    When a droplet of water impacts a heated surface, the drop may be observed to bounce. Recently is has been found that small quantities (˜100 ppm) of polymer additives such as polyethylene oxide can significantly increase the maximum bouncing height of drops. This effect has been explained in terms of the reduction of energy dissipation caused by polymer additives during the drop retraction and rebound, resulting in higher mechanical energy available for bouncing. Here we demonstrate, by comparing three types of fluids (Newtonian, shear-thinning, and viscoelastic), that the total kinetic energy carried by low-viscosity Newtonian drops during retraction is partly transformed into rotational kinetic energy rather than dissipated when compared with high-viscosity or non-Newtonian drops. We also show that non-Newtonian effects play little role in the energy distribution during drop impact, while the main effect is due to the symmetry break observed during the retraction of low-viscosity drops.

  8. Drop Pinch-Off for Discrete Flows from a Capillary

    Directory of Open Access Journals (Sweden)

    Wilson M.C.T.

    2013-07-01

    Full Text Available The problem of drop formation and pinch-off from a capillary tube under the influence of gravity has been extensively studied when the internal capillary pressure gradient is constant. This ensures a continuous time independent flow field inside the capillary tube typically of the Poiseuille flow type. Characteristic drop ejection behaviour includes: periodic drop ejection, drop ejection with associated satellite production, complex dripping, chaotic behaviour and jetting. It is well known that this characteristic behaviour is governed by the Weber (We and Ohnesorge (Oh numbers (for a given Bond number and may be delineated in a We verses Oh operability diagram. An in-depth physical understanding of drop ejection is also of great importance to industry where the tight control of drop size and ejection velocity are of critical importance in industrial processes such as sealants used in electronics assembly and inkjet printing. However, the use of such a continuous flow approach for drop ejection in industry is often impractical since such flows cannot be operator controlled. For this reason it is important to investigate so-called discrete pipe flows where the flow can be turned on and off at will. This means the flow inside the pipe is now time-dependent being controlled in a step-wise fashion. As a first stage in the investigation of drop pinch-off behaviour in discrete pipe flows this paper will study the critical pinch-off time required for drop ejection starting from a pendant drop. This is the discrete amount of time the pipe flow is turned on for in order for a drop to be ejected from the capillary. A Newtonian incompressible free-surface CFD flow code developed at the University of Leeds is used to investigate the critical pinch-off time for a range of internal pipe velocities (the central flow maximum in Poiseuille flow. It is found that the time required for drop ejection to occur decreases exponentially with internal pipe velocity

  9. Evaporation of a liquid drop on a hot liquid surface, (1)

    International Nuclear Information System (INIS)

    Iida, Yoshihiro; Takashima, Takeo

    1980-01-01

    As for the phenomena occurring when two kinds of liquid at different temperature come in contact, the clarification of the basic, general matters of the phenomena has not been made yet. Such situation has been caused by the facts that the detailed observation of the aspect in liquid-liquid contact becomes impossible as the disturbance on the interface becomes violent, and it is difficult to obtain the quantitative data and to change temperature difference largely in practice. In this study, liquid drops were dropped on the free surface of another liquid at the temperature higher than the saturation temperature of the dropping liquid, and it was attempted to obtain the basic knowledge concerning the general behavior at the time of liquid-liquid contact by determining the aspect of evaporation and its change and evaporation time. For this experiment, the silicone oil with four different kinematic viscosity was used as the high temperature liquid, and n-pentane and dichloromethane soluble in the mother liquid, and acetone and methyl alcohol insoluble in the mother liquid were used as the liquid drops. The experimental apparatuses and method and the results are reported. The evaporation time curves presented lying S-shape basically, similarly to the evaporation on solid surfaces. The point of maximum evaporation time and the point of maximum heat transfer rate existed. (J.P.N.)

  10. Pet Fiber Reinforced Wet-Mix Shotcrete with Walnut Shell as Replaced Aggregate

    Directory of Open Access Journals (Sweden)

    Weimin Cheng

    2017-03-01

    Full Text Available In the rapidly developing modern society, many raw materials, such as crushed limestone and river sand, which are limited, are consumed by the concrete industry. Naturally, the usage of waste materials in concrete have become an interesting research area in recent years, which is used to reduce the negative influence of concrete on the environment. Hence, this paper presents the development of a sustainable lightweight wet-mix shotcrete by replacing natural coarse gravel with a kind of byproduct, nut shell (walnut. Fibers made from dumped polyethylene terephthalate (PET bottles were mixed in the composite to improve the properties of the lightweight wet-mix shotcrete. The initial evaluation of the fresh concrete mixed with different volume fraction of walnut shell was carried out in terms of its performance capacities of mechanical properties (i.e., tensile and compressive strength, pumpability and shootability (i.e., slump, pressure drop per meter and rebound rate and the results were compared with plain concrete. With increase of walnut shell, compressive and splitting tensile strength of casting concrete decreased, while slump and pressure drop reduced slightly. Additionally, appropriate dosage of walnut shell can improve the shootability of fresh concrete with low rebound rate and larger build-up thickness. In the second series tests, polypropylene (PP fiber and multi-dimension fiber were also mixed in composite for comparative analysis. After mixing fibers, the splitting tensile strength had obtained marked improvement with slight reduction of compressive strength, along with acceptable fluctuation in terms of pumpability and shootability. Furthermore, relation of density and compressive strength, relation of rebound and density, build-up thickness and relation of compressive and splitting tensile strength were discussed. This study found wet-mix shotcrete incorporating PET fiber with walnut shell of about 35% coarse aggregate replacement

  11. Rain drop size distribution over the Tibetan Plateau

    Science.gov (United States)

    Porcù, Federico; D'Adderio, Leo Pio; Prodi, Franco; Caracciolo, Clelia

    2014-12-01

    Over the last decade, interest in measuring and studying rain drop size distribution (DSD) has grown due to applications in cloud physics, in calibration of space-borne and ground-based microwave active precipitation sensors and in soil science and agriculture. Such studies are of particular interest over remote areas, where knowledge of clouds and precipitation processes is lacking while the need for remote sensing based precipitation estimates is growing in global water cycle and climate trend studies. Disdrometric data over the Tibetan Plateau were collected during the 2010 monsoon season using the Pludix disdrometer, a vertically pointing, continuous wave, X-band, low power radar. Three experimental sites were set up at altitudes greater than 3300 m a.s.l., and a total number of 37 rain events were measured at two of the three sites. The analysis focuses on 2-min and 5-min DSD data for selected convective and stratiform events and the results are discussed in comparison with previous studies performed at lower altitudes. The time evolution of DSDs shows a regular behavior with respect to rain intensity: they change concavity and show a breakup signature in cases of the highest rain rates. Collisional breakup takes place for relatively lower rain rates, compared to the low-altitude measurements, and the size of the largest drops is also relatively smaller. An overall rainfall characteristic evaluation is also performed on the whole data set, deriving DSD integral parameters in order to compute a relationship between reflectivity and rain rate, resulting in A = 214 (A = 247) and b = 1.25 (b = 1.15) for convective (stratiform) precipitation.

  12. Biosensor design based on Marangoni flow in an evaporating drop.

    Science.gov (United States)

    Trantum, Joshua R; Baglia, Mark L; Eagleton, Zachary E; Mernaugh, Raymond L; Haselton, Frederick R

    2014-01-21

    Effective point-of-care diagnostics require a biomarker detection strategy that is low-cost and simple-to-use while achieving a clinically relevant limit of detection. Here we report a biosensor that uses secondary flows arising from surface Marangoni stresses in an evaporating drop to concentrate target-mediated particle aggregates in a visually detectable spot. The spot size increases with increasing target concentration within the dynamic range of the assay. The particle deposition patterns are visually detectable and easily measured with simple optical techniques. We use optical coherence tomography to characterize the effect of cross-sectional flow fields on the motion of particles in the presence and absence of target (aggregated and non-aggregated particles, respectively). We show that choice of substrate material and the presence of salts and glycerol in solution promote the Marangoni-induced flows that are necessary to produce signal in the proposed design. These evaporation-driven flows generate signal in the assay on a PDMS substrate but not substrates with greater thermal conductivity like indium tin oxide-coated glass. In this proof-of-concept design we use the M13K07 bacteriophage as a model target and 1 μm-diameter particles surface functionalized with anti-M13 monoclonal antibodies. Using standard microscopy-based techniques to measure the final spot size, the assay has a calculated limit-of-detection of approximately 100 fM. Approximately 80% of the maximum signal is generated within 10 minutes of depositing a 1 μL drop of reacted sample on PDMS enabling a relatively quick time-to-result.

  13. Crack formation and prevention in colloidal drops

    Science.gov (United States)

    Kim, Jin Young; Cho, Kun; Ryu, Seul-A.; Kim, So Youn; Weon, Byung Mook

    2015-08-01

    Crack formation is a frequent result of residual stress release from colloidal films made by the evaporation of colloidal droplets containing nanoparticles. Crack prevention is a significant task in industrial applications such as painting and inkjet printing with colloidal nanoparticles. Here, we illustrate how colloidal drops evaporate and how crack generation is dependent on the particle size and initial volume fraction, through direct visualization of the individual colloids with confocal laser microscopy. To prevent crack formation, we suggest use of a versatile method to control the colloid-polymer interactions by mixing a nonadsorbing polymer with the colloidal suspension, which is known to drive gelation of the particles with short-range attraction. Gelation-driven crack prevention is a feasible and simple method to obtain crack-free, uniform coatings through drying-mediated assembly of colloidal nanoparticles.

  14. Drop Impact on to Moving Liquid Pools

    Science.gov (United States)

    Muñoz-Sánchez, Beatriz Natividad; Castrejón-Pita, José Rafael; Castrejón-Pita, Alfonso Arturo; Hutchings, Ian M.

    2014-11-01

    The deposition of droplets on to moving liquid substrates is an omnipresent situation both in nature and industry. A diverse spectrum of phenomena emerges from this simple process. In this work we present a parametric experimental study that discerns the dynamics of the impact in terms of the physical properties of the fluid and the relative velocity between the impacting drop and the moving liquid pool. The behaviour ranges from smooth coalescence (characterized by little mixing) to violent splashing (generation of multiple satellite droplets and interfacial vorticity). In addition, transitional regimes such as bouncing and surfing are also found. We classify the system dynamics and show a parametric diagram for the conditions of each regime. This work was supported by the EPSRC (Grant EP/H018913/1), the Royal Society, Becas Santander Universidades and the International Relationships Office of the University of Extremadura.

  15. Shape oscillations of a viscoelastic drop

    International Nuclear Information System (INIS)

    Khismatullin, Damir B.; Nadim, Ali

    2001-01-01

    Small-amplitude axisymmetric shape deformations of a viscoelastic liquid drop in microgravity are theoretically analyzed. Using the Jeffreys constitutive equation for linear viscoelasticity, the characteristic equation for the frequency and decay factor of the shape oscillations is derived. Asymptotic analysis of this equation is performed in the low- and high-viscosity limits and for the cases of small, moderate, and large elasticities. Elastic effects are shown to give rise to a type of shape oscillation that does not depend on the surface tension. The existence of such oscillations is confirmed by numerical solution of the characteristic equation in various regimes. A method for determining the viscoelastic properties of highly viscous liquids based upon experimental measurements of the frequency and damping rate of such shape oscillations is suggested

  16. Horizontal Drop of 21- PWR Waste Package

    International Nuclear Information System (INIS)

    A.K. Scheider

    2001-01-01

    The objective of this calculation is to determine the structural response of the waste package (WP) dropped horizontally from a specified height. The WP used for that purpose is the 21-Pressurized Water Reactor (PWR) WP. The scope of this document is limited to reporting the calculation results in terms of stress intensities. The information provided by the sketches (Attachment I) is that of the potential design of the type of WP considered in this calculation, and all obtained results are valid for that design only. This calculation is associated with the WP design and was performed by the Waste Package Design group in accordance with the ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 16). AP-3.12Q, ''Calculations'' (Ref. 11) is used to perform the calculation and develop the document. The sketches attached to this calculation provide the potential dimensions and materials for the 21-PWR WP design

  17. Biodiesel production from wet municipal sludge: evaluation of in situ transesterification using xylene as a cosolvent.

    Science.gov (United States)

    Choi, O K; Song, J S; Cha, D K; Lee, J W

    2014-08-01

    This study proposes a method to produce biodiesel from wet wastewater sludge. Xylene was used as an alternative cosolvent to hexane for transesterification in order to enhance the biodiesel yield from wet wastewater sludge. The water present in the sludge could be separated during transesterification by employing xylene, which has a higher boiling point than water. Xylene enhanced the biodiesel yield up to 8.12%, which was 2.5 times higher than hexane. It was comparable to the maximum biodiesel yield of 9.68% obtained from dried sludge. Xylene could reduce either the reaction time or methanol consumption, when compared to hexane for a similar yield. The fatty acid methyl esters (FAMEs) content of the biodiesel increased approximately two fold by changing the cosolvent from hexane to xylene. The transesterification method using xylene as a cosolvent can be applied effectively and economically for biodiesel recovery from wet wastewater sludge without drying process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Influence on rewetting temperature and wetting delay during rewetting rod bundle by various radial jet models

    International Nuclear Information System (INIS)

    Debbarma, Ajoy; Pandey, Krishna Murari

    2016-01-01

    Numerical investigation of the rewetting of single sector fuel assembly of Advanced Heavy Water Reactor (AHWR) has been carried out to exhibit the effect of coolant jet diameters (2, 3 and 4 mm) and jet directions (Model: M, X and X2). The rewetting phenomena with various jet models are compared on the basis of rewetting temperature and wetting delay. Temperature-time curve have been evaluated from rods surfaces at different circumference, radial and axial locations of rod bundle. The cooling curve indicated the presence of vapor in respected location, where it prevents the contact between the firm and fluid phases. The peak wall temperature represents as rewetting temperature. The time period observed between initial to rewetting temperature point is wetting delay. It was noted that as improved in various jet models, rewetting temperature and wetting delay reduced, which referred the coolant stipulation in the rod bundle dominant vapor formation.

  19. The Use of Wet Cupping for Persistent Nonspecific Low Back Pain: Randomized Controlled Clinical Trial.

    Science.gov (United States)

    AlBedah, Abdullah; Khalil, Mohamed; Elolemy, Ahmed; Hussein, Asim A; AlQaed, Meshari; Al Mudaiheem, Abdullah; Abutalib, Raid A; Bazaid, Faisal Mohamed; Bafail, Ahmad Saeed; Essa, AboBakr; Bakrain, Mohammed Yahia

    2015-08-01

    To evaluate the effectiveness and safety of wet cupping therapy as a single treatment for persistent nonspecific low back pain (PNSLBP). Randomized controlled trial comparing wet cupping versus no treatment in PNSLBP. Outpatient clinic in three secondary care hospitals in Saudi Arabia. Eighty eligible participants with PNSLBP for at least 3 months were randomly allocated to an intervention group (n=40) or to a control group (n=40). Six wet cupping sessions within 2 weeks, each of which were done at two bladder meridian (BL) acupuncture points among BL23, BL24, and BL25. Only acetaminophen was allowed as a rescue treatment in both groups. The Numeric Rating Scale (NRS), McGill Present Pain Intensity (PPI), and Oswestry Disability Questionnaire (ODQ) were used as outcome measures. Numbers of acetaminophen tablets taken were compared at 4 weeks from baseline. Adverse events were recorded. At the end of the intervention, statistically significant differences in the three outcome measures favoring the wet cupping group compared with the control group were seen: NRS score, 29.2 (95% confidence interval [CI], 24.6-33.8) versus 57.9 (95% CI, 53.3-62.6), respectively; PPI score, 1.17 (95% CI, 0.96-1.4) versus 2.3 (95% CI, 2.1- 2.7); and ODQ score, 19.6 (95% CI, 16.5-22.7) versus 35.4 (95% CI, 32.3-38.5) (p=0.0001). This improvement continued for another 2 weeks after the end of the intervention. Acetaminophen was used less in the wet cupping group, but this difference was not statistically significant. No adverse events were reported. Wet cupping is potentially effective in reducing pain and improving disability associated with PNSLBP at least for 2 weeks after the end of the wet cupping period. Placebo-controlled trials are needed.

  20. Dynamics of Wetting of Ultra Hydrophobic Surfaces

    Science.gov (United States)

    Mohammad Karim, Alireza; Kim, Jeong-Hyun; Rothstein, Jonathan; Kavehpour, Pirouz; Mechanical and Industrial Engineering, University of Massachusetts, Amherst Collaboration

    2013-11-01

    Controlling the surface wettability of hydrophobic and super hydrophobic surfaces has extensive industrial applications ranging from coating, painting and printing technology and waterproof clothing to efficiency increase in power and water plants. This requires enhancing the knowledge about the dynamics of wetting on these hydrophobic surfaces. We have done experimental investigation on the dynamics of wetting on hydrophobic surfaces by looking deeply in to the dependency of the dynamic contact angles both advancing and receding on the velocity of the three-phase boundary (Solid/Liquid/Gas interface) using the Wilhelmy plate method with different ultra-hydrophobic surfaces. Several fluids with different surface tension and viscosity are used to study the effect of physical properties of liquids on the governing laws.

  1. Wet precipitators for sulphuric acid plants

    International Nuclear Information System (INIS)

    Ojanpera, R.O.

    1989-01-01

    Both the service requirements and design construction details have changed considerably in recent years for wet electrostatic precipitators as used for gas cleaning ahead of metallurgical sulphuric acid plants. Increased concern over acid quality has resulted in more emphasis on dust efficiencies compared to collection of acid mist. Also, higher static operating pressures have caused large structural loads on casing and internal components. In this paper these two issues are addressed in the following ways: Recognition that all dusts do not collect similarly. The mechanism by which various dusts collect affect the design of the entire wet gas cleaning system. Use of both traditional and newer materials of construction to accommodate the higher design pressures while still maintaining corrosion resistance

  2. Experimental evaluation of dry/wet air-cooled heat exchangers. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, S.G.; Gruel, R.L.; Huenefeld, J.C.; Eschbach, E.J.; Johnson, B.M.; Kreid, D.K.

    1982-08-01

    The ultimate goal of this project was to contribute to the development of improved cooling facilities for power plants. Specifically, the objective during FY-81 was to experimentally determine the thermal performance and operating characteristics of an air-cooled heat exchanger surface manufactured by the Unifin Company. The performance of the spiral-wound finned tube surface (Unifin) was compared with two inherently different platefin surfaces (one developed by the Trane Co. and the other developed by the HOETERV Institute) which were previously tested as a part of the same continuing program. Under dry operation the heat transfer per unit frontal area per unit inlet temperature difference (ITD) of the Unifin surface was 10% to 20% below that of the other two surfaces at low fan power levels. At high fan power levels, the performances of the Unifin and Trane surfaces were essentially the same, and 25% higher than the HOETERV surface. The design of the Unifin surface caused a significantly larger air-side pressure drop through the heat exchanger both in dry and deluge operation. Generally higher overall heat transfer coefficients were calculated for the Unifin surface under deluged operation. They ranged from 2.0 to 3.5 Btu/hr-ft/sup 2/-/sup 0/F as compared to less than 2.0 Btu hr-ft/sup 2/-/sup 0/F for the Trane and HOETERV surfaces under similar conditions. The heat transfer enhancement due to the evaporative cooling effect was also measureably higher with the Unifin surface as compared to the Trane surface. This can be primarily attributed to the better wetting characteristics of the Unifin surface. If the thermal performance of the surfaces are compared at equal face velocities, the Unifin surface is as much as 35% better. This method of comparison accounts for the wetting characteristics while neglecting the effect of pressure drop. Alternatively the surfaces when compared at equal pressure drop essentially the same thermal performance.

  3. Wet cupping therapy restores sympathovagal imbalances in cardiac rhythm.

    Science.gov (United States)

    Arslan, Müzeyyen; Yeşilçam, Nesibe; Aydin, Duygu; Yüksel, Ramazan; Dane, Senol

    2014-04-01

    A recent study showed that cupping had therapeutic effects in rats with myocardial infarction and cardiac arrhythmias. The current studyaimed to investigate the possible useful effects of cupping therapy on cardiac rhythm in terms of heart rate variability (HRV). Forty healthy participants were included. Classic wet cupping therapy was applied on five points of the back. Recording electrocardiography (to determine HRV) was applied 1 hour before and 1 hour after cupping therapy. All HRV parameters increased after cupping therapy compared with before cupping therapy in healthy persons. These results indicate for the first time in humans that cupping might be cardioprotective. In this study, cupping therapy restored sympathovagal imbalances by stimulating the peripheral nervous system.

  4. Making Activated Carbon by Wet Pressurized Pyrolysis

    Science.gov (United States)

    Fisher, John W.; Pisharody, Suresh; Wignarajah, K.; Moran, Mark

    2006-01-01

    A wet pressurized pyrolysis (wet carbonization) process has been invented as a means of producing activated carbon from a wide variety of inedible biomass consisting principally of plant wastes. The principal intended use of this activated carbon is room-temperature adsorption of pollutant gases from cooled incinerator exhaust streams. Activated carbon is highly porous and has a large surface area. The surface area depends strongly on the raw material and the production process. Coconut shells and bituminous coal are the primary raw materials that, until now, were converted into activated carbon of commercially acceptable quality by use of traditional production processes that involve activation by use of steam or carbon dioxide. In the wet pressurized pyrolysis process, the plant material is subjected to high pressure and temperature in an aqueous medium in the absence of oxygen for a specified amount of time to break carbon-oxygen bonds in the organic material and modify the structure of the material to obtain large surface area. Plant materials that have been used in demonstrations of the process include inedible parts of wheat, rice, potato, soybean, and tomato plants. The raw plant material is ground and mixed with a specified proportion of water. The mixture is placed in a stirred autoclave, wherein it is pyrolized at a temperature between 450 and 590 F (approximately between 230 and 310 C) and a pressure between 1 and 1.4 kpsi (approximately between 7 and 10 MPa) for a time between 5 minutes and 1 hour. The solid fraction remaining after wet carbonization is dried, then activated at a temperature of 500 F (260 C) in nitrogen gas. The activated carbon thus produced is comparable to commercial activated carbon. It can be used to adsorb oxides of sulfur, oxides of nitrogen, and trace amounts of hydrocarbons, any or all of which can be present in flue gas. Alternatively, the dried solid fraction can be used, even without the activation treatment, to absorb

  5. Exposure to wet work in working Australians.

    Science.gov (United States)

    Keegel, Tessa G; Nixon, Rosemary L; LaMontagne, Anthony D

    2012-02-01

    The Australian National Hazard Exposure Worker Surveillance (NHEWS) Survey 2008 was a cross-sectional survey undertaken by Safe Work Australia to inform the development of exposure prevention initiatives for occupational disease. This is a descriptive study of workplace exposures. To assess the occupational and demographic characteristics of workers reporting exposure to wet work. Computer-assisted telephone interviews were conducted with 4500 workers. Two wet work exposure outcomes (frequent washing of hands and duration of time spent at work with the hands immersed in liquids) were analysed. The response rate for the study was 42.3%. For hand-washing, 9.8% [95% confidence interval (CI) 8.9-10.7] reported washing their hands more than 20 times per day. For immersion of hands in liquids, 4.5% (95% CI 3.9-5.1) reported immersion for more than 2 hr per day. Females were more likely to report exposure to frequent hand-washing than males [odds ratio (OR) 1.97, 95% CI 1.49-2.61]. Workers in the lowest occupational skill level jobs were more likely to report increased exposure to hands immersed in liquids than those in the highest (OR 6.41, 95% CI 3.78-10.88). Workers reporting skin exposure to chemicals were more likely to report exposure to hand-washing (OR 3.68, 95% CI 2.91-4.66) and immersion of the hands in liquids (OR 4.09, 95% CI 2.92-5.74). Specific groups of workers reported high levels of exposure to wet work. There were differences between the profiles of workers reporting frequent hand-washing and workers reporting increased duration of exposure to hands immersed in liquids. We also found a high correlation between wet work and chemical exposure. © 2011 John Wiley & Sons A/S.

  6. Wet flue gas desulphurization and new fuels

    Energy Technology Data Exchange (ETDEWEB)

    Kiil, S.; Dam-Johansen, K.; Michelsen, M.L.

    1998-04-01

    This thesis describes experimental and theoretical investigations of wet flue gas desulphurization (FGD). A review of the current knowledge of the various rate determining steps in wet FDG plants is presented. The mechanism underlying the rate of dissolution of finely grained limestone particles was examined in a laboratory batch apparatus using acid titration. Three Danish limestones of different origin were tested. A transient, mass transport controlled, mathematical model was developed to describe the dissolution process. Model predictions were found to be qualitatively in good agreement with experimental data. Empirical correlations for the dimensionless mass transfer coefficients in a pilot plant (falling-film column) were determined. The presence of inert particles in the liquid phase was found to decrease the rate of gas phase mass transport with up to 15%, though the effect could not be correlated. A detailed model for a wet FGD pilot plant, based on the falling film principle, was developed. All important rate determining steps, absorption of SO{sub 2}, oxidation of HSO{sub 3}{sup -}, dissolution of limestone, and crystallisation of gypsum were included. Model predictions were compared to experimental data such as gas phase concentration profiles of SO{sub 2}, slurry pH-profiles, solids contents of slurry, liquid phase concentrations, and residual limestone in the gypsum. The possibility of co-firing straw and coal was investigated in a full-scale power plant. No effects on the overall performance of the wet FGD plant were observed, though laboratory experiments with fine dust and fly ash from the full-scale experiments showed a decrease in limestone reactivity. (EG) EFP-95. 45 refs.; Also ph.d. thesis of Soeren Kiil

  7. Study of polycaprolactone wet electrospinning process

    Directory of Open Access Journals (Sweden)

    E. Kostakova

    2014-08-01

    Full Text Available Wet electrospinning is a useful method for 3-dimensional structure control of nanofibrous materials. This innovative technology uses a liquid collector instead of the metal one commonly used for standard electrospinning. The article compares the internal structural features of polycaprolactone (PCL nanofibrous materials prepared by both technologies. We analyze the influence of different water/ethanol compositions used as a liquid collector on the morphology of the resultant polycaprolactone nanofibrous materials. Scanning electron micro-photographs have revealed a bimodal structure in the wet electrospun materials composed of micro and nanofibers uniformly distributed across the sample bulk. We have shown that the full-faced, twofold fiber distribution is due to the solvent composition and is induced and enhanced by increasing the ethanol weight ratio. Moreover, the comparison of fibrous layers morphology obtained by wet and dry spinning have revealed that beads that frequently appeared in dry spun materials are created by Plateau-Rayleigh instability of the fraction of thicker fibers. Theoretical conditions for spontaneous and complete immersion of cylindrical fibers into a liquid collector are also derived here.

  8. The Wetting Properties of UBM-coated Si-wafer to the Lead-free Solders in Si-wafer/Bumps/Glass Flip-Chip Bonding System

    Energy Technology Data Exchange (ETDEWEB)

    Hong, S.M.; Park, J.Y. [Seoul National University, Seoul (Korea); Park, C.B.; Jung, J.P. [University of Seoul, Seoul (Korea); Kang, C.S. [Seoul National University, Seoul (Korea)

    2000-04-24

    In an attempt to estimate the wetting properties of wettable metal layers by wetting balance method, an analysis of wetting curves of the coating later was performed. Based on the analysis, wetting properties of UBM-coated Si-plate were estimated by the new wettability indices. The wetting curves of the one and both sides-coated UBM layers have the similar shape and show the similar tendency to the temperature. So the wetting property estimation of one side coating is possible with wetting balance method. For UBM of Si-chip, Cr/Cu/Au UBM is better than Ti/Ni/Au in the point of wetting time. At general reflow temperature, the wettability of high melting point solders (Sn-Sb, Sn-Ag) is better than that of low melting point ones (Sn-Bi, Sn-In). The contact angle of the one side coated plate to the solder can be calculated from the force balance equation by measuring the static state force and the tilt angle. (author). 4 refs., 2 tabs., 9 figs.

  9. Flexural properties of repaired heat-polymerising acrylic resin after wetting with monomer and acetone.

    Science.gov (United States)

    Bural, Canan; Bayraktar, Gülsen; Aydin, Ismail; Yusufoğlu, Ibrahim; Uyumaz, Natuk; Hanzade, Mete

    2010-09-01

    Repair strength can be improved by treating fractured surfaces of a denture. This study investigated flexural properties of heat-polymerised acrylic resin specimens repaired with auto-polymerising and visible light curing (VLC) resins after the repair surfaces were wetted with monomers or acetone. Fifty-four specimens (65 x 10 x 2.5 mm) were prepared and 48 of them were sectioned to simulate denture fracture. Butt-joint designed repair surfaces were wetted with heat-, auto-polymerising monomers and acetone for 180 s and repaired with auto-polymerising and VLC resins. After repairs, specimens were subjected to three-point bending test and flexural strength, strain, fracture load, modulus of elasticity and deflection values were recorded. Data were analysed with Student t and LSD tests (p properties, while wetting with acetone did not provide superior effect over both monomers. In clinical use, wetting the repair surfaces may result in stronger repairs. The use of bonding agent in VLC resin repairs in combination with wetting agent results in improved flexural properties.

  10. Marangoni Flow Induced Evaporation Enhancement on Binary Sessile Drops.

    Science.gov (United States)

    Chen, Pin; Harmand, Souad; Ouenzerfi, Safouene; Schiffler, Jesse

    2017-06-15

    The evaporation processes of pure water, pure 1-butanol, and 5% 1-butanol aqueous solution drops on heated hydrophobic substrates are investigated to determine the effect of temperature on the drop evaporation behavior. The evolution of the parameters (contact angle, diameter, and volume) during evaporation measured using a drop shape analyzer and the infrared thermal mapping of the drop surface recorded by an infrared camera were used in investigating the evaporation process. The pure 1-butanol drop does not show any thermal instability at different substrate temperatures, while the convection cells created by the thermal Marangoni effect appear on the surface of the pure water drop from 50 °C. Because 1-butanol and water have different surface tensions, the infrared video of the 5% 1-butanol aqueous solution drop shows that the convection cells are generated by the solutal Marangoni effect at any substrate temperature. Furthermore, when the substrate temperature exceeds 50 °C, coexistence of the thermal and solutal Marangoni flows is observed. By analyzing the relation between the ratio of the evaporation rate of pure water and 1-butanol aqueous solution drops and the Marangoni number, a series of empirical equations for predicting the evaporation rates of pure water and 1-butanol aqueous solution drops at the initial time as well as the equations for the evaporation rate of 1-butanol aqueous solution drop before the depletion of alcohol are derived. The results of these equations correspond fairly well to the experimental data.

  11. The dynamics of liquid drops and their interaction with solids of varying wettabilities

    KAUST Repository

    Sprittles, J. E.

    2012-01-01

    Microdrop impact and spreading phenomena are explored as an interface formation process using a recently developed computational framework. The accuracy of the results obtained from this framework for the simulation of high deformation free-surface flows is confirmed by a comparison with previous numerical studies for the large amplitude oscillations of free liquid drops. Our code\\'s ability to produce high resolution benchmark calculations for dynamic wetting flows is then demonstrated by simulating microdrop impact and spreading on surfaces of greatly differing wettability. The simulations allow one to see features of the process which go beyond the resolution available to experimental analysis. Strong interfacial effects which are observed at the microfluidic scale are then harnessed by designing surfaces of varying wettability that allow new methods of flow control to be developed. © 2012 American Institute of Physics.

  12. Characteristics of wet work in the cleaning industry

    NARCIS (Netherlands)

    Jungbauer, F H W; Van Der Harst, J J; Schuttelaar, M L; Groothoff, J W; Coenraads, P J

    Wet work is the main cause of occupational contact dermatitis in the cleaning industry. Dermatologists and occupational physicians need to base their primary and secondary prevention for workers in the cleaning industry on the characteristics of wet work exposures. We quantified the burden of wet

  13. Experimental and Theoretical Investigations of Wet Flue Gas Desulphurisation

    DEFF Research Database (Denmark)

    Kiil, Søren

    This thesis describes experimental and theoretical investigations of wet flue gas desulphurisa-tion (FGD). A review of the current knowledge of the various rate determining steps in wet FGD plants is presented. The experimental work covers laboratory studies as well as pilot- and full-scale exper...... and mass transport phenomena in wet FGD plants....

  14. Artificial wetting of buffer material. Small scale

    International Nuclear Information System (INIS)

    Holt, E.; Marjavaara, P.; Loeija, M.

    2011-07-01

    The purpose of this work was to investigate the swelling behaviour of artificially wetted highly compacted bentonite buffer blocks used in deposition holes for nuclear waste containment. The target was to make a preliminary study if homogeneous and rapid swelling of the bentonite is possible to achieve in the gap between the buffer and the rock wall of the deposition hole by artificial wetting. It is expected that the thermal, mechanical, chemical and hydraulic properties of the whole deposition system are better when the bentonite-rock gap is closed. In practice it is desirable that the bentonite material has a volume increase sufficient enough to create pressure against the rock surface. Uniform bentonite buffer swelling into the gap would prevent rock scaling while lowering the risks of bentonite piping and erosion due to potential water flow. In this work, two preliminary sets of tests were done on bentonite block swelling and water filtration through pellets. The majority of work was within the primary tests, where bentonite blocks were confined in a test chamber and swelling was induced by artificial wetting. Water was poured directly into the gap from the top, without the aid of pipes or pressure. After the initial watering, no additional water or moisture was made available for the system during the test duration. The resulting bentonite swelling pressure in both the radial and vertical directions was measured over time. 13 different test scenarios were investigated, including: varying block size of 10 cm height disks or 30 cm blocks, eccentric aligned blocks with gap sizes of 5 and 45 mm, gap sizes of 25 mm or 50 mm, using gap filling with pellets or granular in combined with water, free upward swelling or confinement, addition of water at varying rates, and longer term test duration. In some cases, video images were taken during the swelling, to get an indication of the time until the gap was sealed. After the wetting tests, material properties of the

  15. Study of microscale interfacial phenomena during phase change processes: Analysis of micro-drops and thin films

    Science.gov (United States)

    Gokhale, Shripad

    Interfacial phenomena in the three phase contact line region, where a liquid-vapor interface intersects a solid surface, are of importance to many phenomena such as contact angle, adsorption, surface patterning, spreading, thin film stability, phase change, etc. The objectives of this work are to experimentally analyze the coupled phenomena of spreading and phase change for a partially wetting system. We studied five experimental systems: S1---spreading of apolar n-butanol drops during phase change processes, S2 and S3---effects of surface modification on n-butanol spreading and dewetting of the meniscus, S4---spreading of polar 2-propanol drop, S5---coalescence of 2-propanol droplets, and S6---evaporation and spreading of surfactant laden micro-drops of water. Using system S1, we found that the interfacial velocity for the drop during condensation and evaporation is a function of the apparent contact angle and the rate of change of radius of curvature. Using systems S2 and S3, the vivid difference in the behavior of the retracting meniscus with respect to its variation in apparent contact angle and curvature was found to depend on the wettability. Using system S4, an improved image analyzing technique based on the reflectivity measurements using interferometry was developed, which gives fundamental insights about the physics of interfacial phenomena of a spreading drop during phase change. The reflectivity technique was also used in system S5 to study the shapes of condensing drops during their coalescence on the quartz surface. We found that the curvature and its gradient govern the growth and coalescence of the condensing drops. In system S6, the stability of the adsorbed film was analyzed using the concept of minimization of the interfacial free energy. During a phase change process, the thin film of the surfactant solution was unstable and it broke into micro-drops. The drop profiles were experimentally measured and analyzed during the phase change process as

  16. Clinical Importance of the Heel Drop Test and a New Clinical Score for Adult Appendicitis

    Science.gov (United States)

    Ahn, Shin; Lee, Hyeji; Choi, Wookjin; Ahn, Ryeok; Hong, Jung-Suk; Sohn, Chang Hwan; Seo, Dong Woo; Lee, Yoon-Seon; Lim, Kyung Soo; Kim, Won Young

    2016-01-01

    Objective We tried to evaluate the accuracy of the heel drop test in patients with suspected appendicitis and tried to develop a new clinical score, which incorporates the heel drop test and other parameters, for the diagnosis of this condition. Methods We performed a prospective observational study on adult patients with suspected appendicitis at two academic urban emergency departments between January and August 2015. The predictive characteristics of each parameter, along with heel drop test results were calculated. A composite score was generated by logistic regression analysis. The performance of the generated score was compared to that of the Alvarado score. Results Of the 292 enrolled patients, 165 (56.5%) had acute appendicitis. The heel drop test had a higher predictive value than rebound tenderness. Variables and their points included in the new (MESH) score were pain migration (2), elevated white blood cell (WBC) >10,000/μL (3), shift to left (2), and positive heel drop test (3). The MESH score had a higher AUC than the Alvarado score (0.805 vs. 0.701). Scores of 5 and 11 were chosen as cut-off values; a MESH score ≥5 compared to an Alvarado score ≥5, and a MESH score ≥8 compared to an Alvarado score ≥7 showed better performance in diagnosing appendicitis. Conclusion MESH (migration, elevated WBC, shift to left, and heel drop test) is a simple clinical scoring system for assessing patients with suspected appendicitis and is more accurate than the Alvarado score. Further validation studies are needed. PMID:27723842

  17. Clinical Importance of the Heel Drop Test and a New Clinical Score for Adult Appendicitis.

    Directory of Open Access Journals (Sweden)

    Shin Ahn

    Full Text Available We tried to evaluate the accuracy of the heel drop test in patients with suspected appendicitis and tried to develop a new clinical score, which incorporates the heel drop test and other parameters, for the diagnosis of this condition.We performed a prospective observational study on adult patients with suspected appendicitis at two academic urban emergency departments between January and August 2015. The predictive characteristics of each parameter, along with heel drop test results were calculated. A composite score was generated by logistic regression analysis. The performance of the generated score was compared to that of the Alvarado score.Of the 292 enrolled patients, 165 (56.5% had acute appendicitis. The heel drop test had a higher predictive value than rebound tenderness. Variables and their points included in the new (MESH score were pain migration (2, elevated white blood cell (WBC >10,000/μL (3, shift to left (2, and positive heel drop test (3. The MESH score had a higher AUC than the Alvarado score (0.805 vs. 0.701. Scores of 5 and 11 were chosen as cut-off values; a MESH score ≥5 compared to an Alvarado score ≥5, and a MESH score ≥8 compared to an Alvarado score ≥7 showed better performance in diagnosing appendicitis.MESH (migration, elevated WBC, shift to left, and heel drop test is a simple clinical scoring system for assessing patients with suspected appendicitis and is more accurate than the Alvarado score. Further validation studies are needed.

  18. Smoothed particle hydrodynamics simulations of evaporation and explosive boiling of liquid drops in microgravity.

    Science.gov (United States)

    Sigalotti, Leonardo Di G; Troconis, Jorge; Sira, Eloy; Peña-Polo, Franklin; Klapp, Jaime

    2015-07-01

    The rapid evaporation and explosive boiling of a van der Waals (vdW) liquid drop in microgravity is simulated numerically in two-space dimensions using the method of smoothed particle hydrodynamics. The numerical approach is fully adaptive and incorporates the effects of surface tension, latent heat, mass transfer across the interface, and liquid-vapor interface dynamics. Thermocapillary forces are modeled by coupling the hydrodynamics to a diffuse-interface description of the liquid-vapor interface. The models start from a nonequilibrium square-shaped liquid of varying density and temperature. For a fixed density, the drop temperature is increased gradually to predict the point separating normal boiling at subcritical heating from explosive boiling at the superheat limit for this vdW fluid. At subcritical heating, spontaneous evaporation produces stable drops floating in a vapor atmosphere, while at near-critical heating, a bubble is nucleated inside the drop, which then collapses upon itself, leaving a smaller equilibrated drop embedded in its own vapor. At the superheat limit, unstable bubble growth leads to either fragmentation or violent disruption of the liquid layer into small secondary drops, depending on the liquid density. At higher superheats, explosive boiling occurs for all densities. The experimentally observed wrinkling of the bubble surface driven by rapid evaporation followed by a Rayleigh-Taylor instability of the thin liquid layer and the linear growth of the bubble radius with time are reproduced by the simulations. The predicted superheat limit (T(s)≈0.96) is close to the theoretically derived value of T(s)=1 at zero ambient pressure for this vdW fluid.

  19. Spatial and Temporal Stress Drop Variations of the 2011 Tohoku Earthquake Sequence

    Science.gov (United States)

    Miyake, H.

    2013-12-01

    The 2011 Tohoku earthquake sequence consists of foreshocks, mainshock, aftershocks, and repeating earthquakes. To quantify spatial and temporal stress drop variations is important for understanding M9-class megathrust earthquakes. Variability and spatial and temporal pattern of stress drop is a basic information for rupture dynamics as well as useful to source modeling. As pointed in the ground motion prediction equations by Campbell and Bozorgnia [2008, Earthquake Spectra], mainshock-aftershock pairs often provide significant decrease of stress drop. We here focus strong motion records before and after the Tohoku earthquake, and analyze source spectral ratios considering azimuth- and distance dependency [Miyake et al., 2001, GRL]. Due to the limitation of station locations on land, spatial and temporal stress drop variations are estimated by adjusting shifts from the omega-squared source spectral model. The adjustment is based on the stochastic Green's function simulations of source spectra considering azimuth- and distance dependency. We assumed the same Green's functions for event pairs for each station, both the propagation path and site amplification effects are cancelled out. Precise studies of spatial and temporal stress drop variations have been performed [e.g., Allmann and Shearer, 2007, JGR], this study targets the relations between stress drop vs. progression of slow slip prior to the Tohoku earthquake by Kato et al. [2012, Science] and plate structures. Acknowledgement: This study is partly supported by ERI Joint Research (2013-B-05). We used the JMA unified earthquake catalogue and K-NET, KiK-net, and F-net data provided by NIED.

  20. Drop Test Results of CRDM under Seismic Loads

    International Nuclear Information System (INIS)

    Choi, Myoung-Hwan; Cho, Yeong-Garp; Kim, Gyeong-Ho; Sun, Jong-Oh; Huh, Hyung

    2016-01-01

    This paper describes the test results to demonstrate the drop performance of CRDM under seismic loads. The top-mounted CRDM driven by the stepping motor for Jordan Research and Training Reactor (JRTR) has been developed in KAERI. The CRDM for JRTR has been optimized by the design improvement based on that of the HANARO. It is necessary to verify the drop performance under seismic loads such as operating basis earthquake (OBE) and safe shutdown earthquake (SSE). Especially, the CAR drop times are important data for the safety analysis. confirm the drop performance under seismic loads. The delay of drop time at Rig no. 2 due to seismic loads is greater than that at Rig no. 3. The total pure drop times under seismic loads are estimated as 1.169 and 1.855, respectively

  1. The Influence of Concentrace Mineral Drops on Performance Broiler

    Directory of Open Access Journals (Sweden)

    Sigit Mugiyono

    1999-05-01

    Full Text Available A research has been conducted in Experimental Farm Faculty of Animal Husbandry Unsoed from July 1 st until August 15 th, 1996. The purpose want to study the influence of CMD supplementation in drinking water consists of M0 = control; M1 = 0.5 drops/1000 cc, M2 = 1 drops/1000 cc; M3 = 1.5 drops/1000 cc and M4 = 2 drops/1000cc. The performance observed were growth, body weight, feed consumption, feed conversion, drinking water consumption; and income over feed and mineral cost (IOFMC. The research involved 100 broiler chickens divided that CMD supplementation until 2 drops/1000cc did not significantly affect on the performance of broiler chickens except in income over feed and mineral cost (P<0.05. (Animal Production 1(2: 56-62 (1999 Key Words: broiler, concentrace mineral drops, performance.

  2. A study of fungi on droppings of certain birds

    Directory of Open Access Journals (Sweden)

    C. S. Singh

    2014-08-01

    Full Text Available Droppings of fowl, owl, parrot, pigeon and sparrow were asepticaly collected in sterilized bottles from different places at Gorakhpur, 54 fungi were isolated. The number of fungi was more in the pigeon showing considerable decrease in the fowl and the sparrow. In the parrot and the owl, however. the fungi were egual in number. The number of Phycomycetes was almost the same on droppings of all birds, from parrot only one species could be isolated. A larger number of Ascomyteces was recorded from fowl, less from pigeon and owl and the least (two each on sparrow and parrot droppings. The Basidiomycetes, represented by two species only, were recorded on owl and pigeon droppings. Pigeon droppings yielded the largest number of Deuteromycetes. They were egual in numbers on owl and parrot while on fowl and sparrow their number was comparatively less. Mycelia sterilia, though poor in their numbers, were recorded on all the bird droppings excepting owl.

  3. Drop Impact on Textile Material: Effect of Fabric Properties

    Directory of Open Access Journals (Sweden)

    Romdhani Zouhaier

    2014-09-01

    Full Text Available This paper presents an experimental study of impact of water drop on a surface in a spreading regime with no splashing. Three surfaces were studied: virgin glass, coating film and woven cotton fabric at different construction parameters. All experiments were carried out using water drop with the same free fall high. Digidrop with high-resolution camera is used to measure the different parameters characterising this phenomenon. Results show an important effect of the height of the free fall on the drop profile and the spreading behaviour. An important drop deformation at the surface impact was observed. Then, fabric construction as the weft count deeply affects the drop impact. For plain weave, an increase of weft count causes a decrease in penetration and increase in the spreading rate. The same result was obtained for coated fabric. Therefore, the impact energy was modified and the drop shape was affected, which directly influenced the spreading rate.

  4. Drop entrainment from the surface of oil mist filters: mechanisms, kinetics, and drop spectra

    OpenAIRE

    Wurster, S.; Kolb, H.; Meyer, J.; Kasper, G.

    2016-01-01

    Oil entrainment from coalescence filters has been characterized by different techniques. Drop spectra and entrainment rates were measured by a combination of techniques from 1 mm over long periods of time. Dominant entrainment mechanism(s) are identified on the basis of comparisons of entrainment rates measured in different regions of the filter surface with rates of air bubble formation, measurements of oil film thickness, as well as visual observations. Experiments are supported by force es...

  5. Ergonomic factors related to drop-off detection with the long cane: effects of cane tips and techniques.

    Science.gov (United States)

    Kim, Dae Shik; Emerson, Robert S Wall; Curtis, Amy B

    2010-06-01

    This study examined the effect of cane tips and cane techniques on drop-off detection with the long cane. Blind pedestrians depend on a long cane to detect drop-offs. Missing a drop-off may result in falls or collision with moving vehicles in the street. Although cane tips appear to affect a cane user's ability to detect drop-offs, few experimental studies have examined such effect. A repeated-measures design with block randomization was used for the study. Participants were 17 adults who were legally blind and had no other disabilities. Participants attempted to detect the drop-offs of varied depths using different cane tips and cane techniques. Drop-off detection rates were similar between the marshmallow tip (77.0%) and the marshmallow roller tip (79.4%) when both tips were used with the constant contact technique, p = .294. However, participants detected drop-offs at a significantly higher percentage when they used the constant contact technique with the marshmallow roller tip (79.4%) than when they used the two-point touch technique with the marshmallow tip (63.2%), p marshmallow roller tip (perceived as a less advantageous tip) was more effective than the two-point touch technique used with a marshmallow tip (perceived as a more advantageous tip) in detecting drop-offs. The findings of the study may help cane users and orientation and mobility specialists select appropriate cane techniques and cane tips in accordance with the cane user's characteristics and the nature of the travel environment.

  6. Drops Bouncing on a Superhydrophobic Surface

    Science.gov (United States)

    van Swol, Frank

    2007-03-01

    Low solid interfacial energy and fractally rough surface topography confer to Lotus plants superhydrophobic (SH) properties like high contact angles, rolling and bouncing of liquid droplets, and self-cleaning of particle contaminants. By exploiting the porous fractal structure of a novel, synthetic SH surface it is possible to produce a synthetic lotus effect. This is relevant to realizing self-cleaning properties for particle concentration, and the slippery nature of the coating can be used to enhance the performance of fluidic devices. Here we report on molecular dynamics (MD) and some classical density functional theory calculations that provide valuable insight into the conditions needed to cause liquid droplets to form and bounce on a surface. The MD results report on the details of the droplets impacting surfaces of varying wettability, ranging from complete wetting to complete drying. For the SH surfaces we present results for the contact time, between droplet and surface, as a function of impact velocity, droplet size and surface friction.

  7. Evaporation of a sessile water drop and a drop of aqueous salt solution.

    Science.gov (United States)

    Misyura, S Y

    2017-11-07

    The influence of various factors on the evaporation of drops of water and aqueous salt solution has been experimentally studied. Typically, in the studies of drop evaporation, only the diffusive vapor transfer, radiation and the molecular heat conduction are taken into account. However, vapor-gas convection plays an important role at droplet evaporation. In the absence of droplet boiling, the influence of gas convection turns out to be the prevailing factor. At nucleate boiling, a prevailing role is played by bubbles generation and vapor jet discharge at a bubble collapse. The gas convection behavior for water and aqueous salt solution is substantially different. With a growth of salt concentration over time, the influence of the convective component first increases, reaches an extremum and then significantly decreases. At nucleate boiling in a salt solution it is incorrect to simulate the droplet evaporation and the heat transfer in quasi-stationary approximation. The evaporation at nucleate boiling in a liquid drop is divided into several characteristic time intervals. Each of these intervals is characterized by a noticeable change in both the evaporation rate and the convection role.

  8. Drop-out from a psychodynamic group psychotherapy outpatient unit.

    Science.gov (United States)

    Jensen, Hans Henrik; Mortensen, Erik Lykke; Lotz, Martin

    2014-11-01

    BACKGROUND. Drop-out from psychotherapy is common and represents a considerable problem in clinical practice and research. Aim. To explore pre-treatment predictors of early and late drop-out from psychodynamic group therapy in a public outpatient unit for non-psychotic disorders in Denmark. Methods. Naturalistic design including 329 patients, the majority with mood, neurotic and personality disorders referred to 39-session group therapy. Predictors were socio-demographic and clinical variables, self-reported symptoms (Symptom Check List-90-Revised) and personality style (Millon Clinical Multiaxial Inventory-II). Drop-out was classified into early and late premature termination excluding patients who dropped out for external reasons. Results. Drop-out comprised 20.6% (68 patients) of the sample. Logistic regression revealed social functioning, vocational training, alcohol problems and antisocial behavior to be related to drop-out. However, early drop-outs had prominent agoraphobic symptoms, lower interpersonal sensitivity and compulsive personality features, and late drop-outs cognitive and somatic anxiety symptoms and antisocial personality features. Clinical and psychological variables accounted for the major part of variance in predictions of drop-out, which ranged from 15.6% to 19.5% (Nagelkerke Pseudo R-Square). Conclusion. Social functioning was consistently associated with drop-out, but personality characteristics and anxiety symptoms differentiated between early and late drop-out. Failure to discriminate between stages of premature termination may explain some of the inconsistencies in the drop-out literature. Clinical implications. Before selection of patients to time-limited psychodynamic groups, self-reported symptoms should be thoroughly considered. Patients with agoraphobic symptoms should be offered alternative treatment. Awareness of and motivation to work with interpersonal issues may be essential for compliance with group therapy.

  9. Isolation of Indonesian Cananga oil by instantaneous controlled pressure drop

    OpenAIRE

    2008-01-01

    The isolation of cananga oil by a new process, Instantaneous Controlled Pressure Drop (DIC), was investigated. This process consists in heating the dry cananga (Cananga odorata Hook. fil. et Thomson,forma macrophylla) flowers for a short time period by steam, followed by an abrupt pressure drop into a vacuum (about 5 kPa). This pressure drop provokes auto-vaporization of the volatile compounds, puffing of flowers, breaking of cell walls and cooling. The effect of the process parameters, namel...

  10. Self-excited hydrothermal waves in evaporating sessile drops

    OpenAIRE

    Sefiane K.; Moffat J.R.; Matar O.K.; Craster R.V.

    2008-01-01

    Pattern formation driven by the spontaneous evaporation of sessile drops of methanol, ethanol, and FC-72 using infrared thermography is observed and, in certain cases, interpreted in terms of hydrothermal waves. Both methanol and ethanol drops exhibit thermal wave trains, whose wave number depends strongly on the liquid volatililty and substrate thermal conductivity. The FC- 72 drops develop cellular structures whose size is proportional to the local thickness. Prior to this work, hydrotherma...

  11. Studying the field induced breakup of acoustically levitated drops

    Science.gov (United States)

    Warschat, C.; Riedel, J.

    2017-10-01

    Coulomb fission of charged droplets (The terms drop and droplet are often used synonymous. Throughout this manuscript, to avoid confusion, the terms drop and droplet will be used for liquid spheres with radii in the millimeter range and the micrometer range, respectively. In our experiments, the first correspond to the parent drop while the latter describes the ejected progeny droplets.) is a well-studied natural phenomenon. Controlled droplet fission is already successfully employed in several technological applications. Still, since the occurring surface rupture relies on the exact understanding and description of the liquid gas boundary, some details are still under debate. Most empirical systematic studies observe falling micrometer droplets passing through the electric field inside a plate capacitor. This approach, although easily applicable and reliable, limits the experimental degrees of freedom regarding the observable time and the maximum size of the drops and can only be performed in consecutive individual observations of different subsequent drops. Here we present a novel setup to study the field induced breakup of acoustically levitated drops. The design does not bear any restrictions towards the temporal window of observation, and allows handling of drops of a tunable radius ranging from 10 μm to several millimeters and a real-time monitoring of one single drop. Our comprehensive study includes a time resolved visual inspection, laser shadowgraphy, laser induced fluorescence imaging, and ambient mass spectrometric interrogation of the nascent Taylor cone. The results shown for a millimeter sized drop, previously inaccessible for Coulomb fission experiments, are mostly comparable with previous results for smaller drops. The major difference is the time scale and the threshold potential of the drop rupture. Both values, however, resemble theoretically extrapolations to the larger radius. The technique allows for a systematic study of breakup behavior of

  12. Confined thermocapillary motion of a three-dimensional deformable drop

    Science.gov (United States)

    Brady, P. T.; Herrmann, M.; Lopez, J. M.

    2011-02-01

    In this paper, simulations are performed of the thermocapillary motion of three-dimensional and axisymmetric drops in a confined apparatus. The refined level-set grid method is used to track the interface and resolve very small deformations. We compare our results to theoretically predicted thermocapillary migration velocities of drops and to experimentally measured migration velocities in microgravity experiments. The motivation of the present work is to address four important questions surrounding thermocapillary migration. These are as follows. (1) What is the impact of initial conditions on both the initial transient and steady state drop behavior? (2) What is the impact of the domain geometry on drop behavior? (3) Do drops deform for intermediate Marangoni numbers and are those deformations axisymmetric? (4) Can the assumption of constant temperature fluid properties be used when simulating physical experiments? To answer the first question, we explore the parameter space of initial drop temperature distribution and drop holding time. We find that in lower Marangoni number regimes, the drop rapidly settles to a quasisteady state. For larger Marangoni numbers, the initial conditions dominate the drop behavior. To address the second and third questions, we look at the spatial distribution of tangential temperature gradients on the surface of the drop as well as drop deformations and migration velocities. The domain geometry induces nonaxisymmetric deformations and temperature distributions. The results of several axisymmetric runs with realistic physical properties are examined to answer the fourth question. It is found that the variation of material properties influences the drop migration behavior in a nontrivial way.

  13. Reducing Variability in Stress Drop with Root-Mean Acceleration

    Science.gov (United States)

    Crempien, J.; Archuleta, R. J.

    2012-12-01

    Stress drop is a fundamental property of the earthquake source. For a given tectonic region stress drop is assumed to be constant allowing for the scaling of earthquake spectra. However, the variability of the stress drop, either for worldwide catalogs or regional catalogs, is quite large. The variability around the median value is on the order of 1.5 in log10 units. One question that continues to pervade the analysis of stress drop is whether this variability is an inherent characteristic of the Earth or is an artifact of the determination of stress drop via the use of the spectral analysis. It is simple to see that the stress drop determined by seismic moment times corner frequency cubed that errors in the corner frequency will strongly influence the variability in the stress drop. To avoid this strong dependence on corner frequency cubed, we have examined the determination of stress drop based on the approach proposed by Hanks (1979), namely using the root-mean-square acceleration. The stress drop determined using rms acceleration may be advantageous because the stress drop is only affected by the square root of the corner frequency. To test this approach we have determined stress drops for the 2000 Tottori earthquake and its aftershocks. We use both the classic method of fitting to a spectrum as well as using rms acceleration. For a preliminary analysis of eight aftershocks and the mainshock we find that the variability in stress drop is reduced by about a factor of two. This approach needs more careful analysis of more events, which will be shown at the meeting.

  14. Geometry of the vapor layer under a leidenfrost drop.

    Science.gov (United States)

    Burton, J C; Sharpe, A L; van der Veen, R C A; Franco, A; Nagel, S R

    2012-08-17

    In the Leidenfrost effect, liquid drops deposited on a hot surface levitate on a thin vapor cushion fed by evaporation of the liquid. This vapor layer forms a concave depression in the drop interface. Using laser-light interference coupled to high-speed imaging, we measured the radius, curvature, and height of the vapor pocket, as well as nonaxisymmetric fluctuations of the interface for water drops at different temperatures. The geometry of the vapor pocket depends primarily on the drop size and not on the substrate temperature.

  15. Oscillating and star-shaped drops levitated by an airflow.

    Science.gov (United States)

    Bouwhuis, Wilco; Winkels, Koen G; Peters, Ivo R; Brunet, Philippe; van der Meer, Devaraj; Snoeijer, Jacco H

    2013-08-01

    We investigate the spontaneous oscillations of drops levitated above an air cushion, eventually inducing a breaking of axisymmetry and the appearance of "star drops". This is strongly reminiscent of the Leidenfrost stars that are observed for drops floating above a hot substrate. The key advantage of this work is that we inject the airflow at a constant rate below the drop, thus eliminating thermal effects and allowing for a better control of the flow rate. We perform experiments with drops of different viscosities and observe stable states, oscillations, and chimney instabilities. We find that for a given drop size the instability appears above a critical flow rate, where the latter is largest for small drops. All these observations are reproduced by numerical simulations, where we treat the drop using potential flow and the gas as a viscous lubrication layer. Qualitatively, the onset of instability agrees with the experimental results, although the typical flow rates are too large by a factor 10. Our results demonstrate that thermal effects are not important for the formation of star drops and strongly suggest a purely hydrodynamic mechanism for the formation of Leidenfrost stars.

  16. Electromagnetic radiation due to nonlinear oscillations of a charged drop

    Science.gov (United States)

    Shiryaeva, S. O.; Grigor'ev, A. N.; Kolbneva, N. Yu.

    2016-03-01

    The nonlinear oscillations of a spherical charged drop are asymptotically analyzed under the conditions of a multimode initial deformation of its equilibrium shape. It is found that if the spectrum of initially excited modes contains two adjacent modes, the translation mode of oscillations is excited among others. In this case, the center of the drop's charge oscillates about the equilibrium position, generating a dipole electromagnetic radiation. It is shown that the intensity of this radiation is many orders of magnitude higher than the intensity of the drop's radiation, which arises in calculations of the first order of smallness and is related to the drop's charged surface oscillations.

  17. Improving BWR fuel critical power without increasing bundle pressure drop

    International Nuclear Information System (INIS)

    Matzner, B.; Shiraishi, L.M.; Danielson, D.W.; Congdon, S.P.

    2004-01-01

    It has been almost axiomatic that BWR fuel bundle critical power performance could not be improved without an accompanying increase in bundle pressure drop. It appeared that in order to increase the bundle dryout resistance it was necessary to perturb the bundle coolant flow paths in some fashion. This resulted in an unacceptable bundle pressure drop increase. However, by adding part length rods to decrease bundle pressure drop and by inserting an extra spacer with rearranged spacer pitch and flow trippers on the channel wall at the top of the bundle to increase critical power it was possible to achieve the goal of increased bundle critical power without pressure drop increase. (author)

  18. Insights from the pollination drop proteome and the ovule transcriptome of Cephalotaxus at the time of pollination drop production.

    Science.gov (United States)

    Pirone-Davies, Cary; Prior, Natalie; von Aderkas, Patrick; Smith, Derek; Hardie, Darryl; Friedman, William E; Mathews, Sarah

    2016-05-01

    Many gymnosperms produce an ovular secretion, the pollination drop, during reproduction. The drops serve as a landing site for pollen, but also contain a suite of ions and organic compounds, including proteins, that suggests diverse roles for the drop during pollination. Proteins in the drops of species of Chamaecyparis, Juniperus, Taxus, Pseudotsuga, Ephedra and Welwitschia are thought to function in the conversion of sugars, defence against pathogens, and pollen growth and development. To better understand gymnosperm pollination biology, the pollination drop proteomes of pollination drops from two species of Cephalotaxus have been characterized and an ovular transcriptome for C. sinensis has been assembled. Mass spectrometry was used to identify proteins in the pollination drops of Cephalotaxus sinensis and C. koreana RNA-sequencing (RNA-Seq) was employed to assemble a transcriptome and identify transcripts present in the ovules of C. sinensis at the time of pollination drop production. About 30 proteins were detected in the pollination drops of both species. Many of these have been detected in the drops of other gymnosperms and probably function in defence, polysaccharide metabolism and pollen tube growth. Other proteins appear to be unique to Cephalotaxus, and their putative functions include starch and callose degradation, among others. Together, the proteins appear either to have been secreted into the drop or to occur there due to breakdown of ovular cells during drop production. Ovular transcripts represent a wide range of gene ontology categories, and some may be involved in drop formation, ovule development and pollen-ovule interactions. The proteome of Cephalotaxus pollination drops shares a number of components with those of other conifers and gnetophytes, including proteins for defence such as chitinases and for carbohydrate modification such as β-galactosidase. Proteins likely to be of intracellular origin, however, form a larger component of drops

  19. The Digital Drag and Drop Pillbox

    Science.gov (United States)

    Granger, Bradi B.; Locke, Susan C.; Bowers, Margaret; Sawyer, Tenita; Shang, Howard; Abernethy, Amy P.; Bloomfield, Richard A.; Gilliss, Catherine L.

    2017-01-01

    Objective: We present the design and feasibility testing for the “Digital Drag and Drop Pillbox” (D-3 Pillbox), a skill-based educational approach that engages patients and providers, measures performance, and generates reports of medication management skills. Methods: A single-cohort convenience sample of patients hospitalized with heart failure was taught pill management skills using a tablet-based D-3 Pillbox. Medication reconciliation was conducted, and aptitude, performance (% completed), accuracy (% correct), and feasibility were measured. Results: The mean age of the sample (n = 25) was 59 (36–89) years, 50% were women, 62% were black, 46% were uninsured, 46% had seventh-grade education or lower, and 31% scored very low for health literacy. However, most reported that the D-3 Pillbox was easy to read (78%), easy to repeat-demonstrate (78%), and comfortable to use (tablet weight) (75%). Accurate medication recognition was achieved by discharge in 98%, but only 25% reported having a “good understanding of my responsibilities.” Conclusions: The D-3 Pillbox is a feasible approach for teaching medication management skills and can be used across clinical settings to reinforce skills and medication list accuracy. PMID:28282304

  20. Career drop outs of young elite athletes

    Directory of Open Access Journals (Sweden)

    Petra Fišer

    2007-12-01

    Full Text Available The main problem of the study was to examine the characteristics of sports career drop outs of young elite sportswomen and their adaptation to the post-sport life. The sample included 20 ex-young elite sportswomen, who had brought their successful sport careers to an end before the age of 19. We used a modified interview about sports career termination (Cecić Erpič, 1998 for the investigation of the characteristics of their sports careers. To examine the caracteristics of sport careers we used frequency analysis and cluster analysis. The results showed that the participants mostly stated more than one reason for the termination of their career. The most common reasons for career termination were: lack of motivation, bad relations with trainers or co-competitors and dedication to school or education. After the end of a sports career most of the young sportswomen stayed actively in touch with sport, either as trainers, judges, or they remained engaged in sports for recreation.

  1. The viruses of wild pigeon droppings.

    Directory of Open Access Journals (Sweden)

    Tung Gia Phan

    Full Text Available Birds are frequent sources of emerging human infectious diseases. Viral particles were enriched from the feces of 51 wild urban pigeons (Columba livia from Hong Kong and Hungary, their nucleic acids randomly amplified and then sequenced. We identified sequences from known and novel species from the viral families Circoviridae, Parvoviridae, Picornaviridae, Reoviridae, Adenovirus, Astroviridae, and Caliciviridae (listed in decreasing number of reads, as well as plant and insect viruses likely originating from consumed food. The near full genome of a new species of a proposed parvovirus genus provisionally called Aviparvovirus contained an unusually long middle ORF showing weak similarity to an ORF of unknown function from a fowl adenovirus. Picornaviruses found in both Asia and Europe that are distantly related to the turkey megrivirus and contained a highly divergent 2A1 region were named mesiviruses. All eleven segments of a novel rotavirus subgroup related to a chicken rotavirus in group G were sequenced and phylogenetically analyzed. This study provides an initial assessment of the enteric virome in the droppings of pigeons, a feral urban species with frequent human contact.

  2. GENDER, DEBT, AND DROPPING OUT OF COLLEGE.

    Science.gov (United States)

    Dwyer, Rachel E; Hodson, Randy; McLoud, Laura

    2013-02-01

    For many young Americans, access to credit has become critical to completing a college education and embarking on a successful career path. Young people increasingly face the trade-off of taking on debt to complete college or foregoing college and taking their chances in the labor market without a college degree. These trade-offs are gendered by differences in college preparation and support and by the different labor market opportunities women and men face that affect the value of a college degree and future difficulties they may face in repaying college debt. We examine these new realities by studying gender differences in the role of debt in the pivotal event of graduating from college using the 1997 cohort of the national longitudinal Survey of youth. In this article, we find that women and men both experience slowing and even diminishing probabilities of graduating when carrying high levels of debt, but that men drop out at lower levels of debt than do women. We conclude by theorizing that high levels of debt are one of the mechanisms that sort women and men into different positions in the social stratification system.

  3. Andreas Acrivos Dissertation Award: Onset of Dynamic Wetting Failure - The Mechanics of High-Speed Fluid Displacement

    Science.gov (United States)

    Vandre, Eric

    2014-11-01

    Dynamic wetting is crucial to processes where a liquid displaces another fluid along a solid surface, such as the deposition of a coating liquid onto a moving substrate. Dynamic wetting fails when process speed exceeds some critical value, leading to incomplete fluid displacement and transient phenomena that impact a variety of applications, such as microfluidic devices, oil-recovery systems, and splashing droplets. Liquid coating processes are particularly sensitive to wetting failure, which can induce air entrainment and other catastrophic coating defects. Despite the industrial incentives for careful control of wetting behavior, the hydrodynamic factors that influence the transition to wetting failure remain poorly understood from empirical and theoretical perspectives. This work investigates the fundamentals of wetting failure in a variety of systems that are relevant to industrial coating flows. A hydrodynamic model is developed where an advancing fluid displaces a receding fluid along a smooth, moving substrate. Numerical solutions predict the onset of wetting failure at a critical substrate speed, which coincides with a turning point in the steady-state solution path for a given set of system parameters. Flow-field analysis reveals a physical mechanism where wetting failure results when capillary forces can no longer support the pressure gradients necessary to steadily displace the receding fluid. Novel experimental systems are used to measure the substrate speeds and meniscus shapes associated with the onset of air entrainment during wetting failure. Using high-speed visualization techniques, air entrainment is identified by the elongation of triangular air films with system-dependent size. Air films become unstable to thickness perturbations and ultimately rupture, leading to the entrainment of air bubbles. Meniscus confinement in a narrow gap between the substrate and a stationary plate is shown to delay air entrainment to higher speeds for a variety of

  4. Leidenfrost Point and Estimate of the Vapour Layer Thickness

    Science.gov (United States)

    Gianino, Concetto

    2008-01-01

    In this article I describe an experiment involving the Leidenfrost phenomenon, which is the long lifetime of a water drop when it is deposited on a metal that is much hotter than the boiling point of water. The experiment was carried out with high-school students. The Leidenfrost point is measured and the heat laws are used to estimate the…

  5. Degradation of paracetamol by catalytic wet air oxidation and sequential adsorption - Catalytic wet air oxidation on activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Quesada-Penate, I. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Julcour-Lebigue, C., E-mail: carine.julcour@ensiacet.fr [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France); Jauregui-Haza, U.J. [Instituto Superior de Tecnologias y Ciencias Aplicadas, Ave. Salvador Allende y Luaces, Habana (Cuba); Wilhelm, A.M.; Delmas, H. [Universite de Toulouse, INPT, UPS, Laboratoire de Genie Chimique, 4, Allee Emile Monso, F-31432 Toulouse (France); CNRS, Laboratoire de Genie Chimique, F-31432 Toulouse (France)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer Three activated carbons (AC) compared as adsorbents and oxidation catalysts. Black-Right-Pointing-Pointer Similar evolution for catalytic and adsorptive properties of AC over reuses. Black-Right-Pointing-Pointer Acidic and mesoporous AC to be preferred, despite lower initial efficiency. Black-Right-Pointing-Pointer Oxidative degradation of paracetamol improves biodegradability. Black-Right-Pointing-Pointer Convenient hybrid adsorption-regenerative oxidation process for continuous treatment. - Abstract: The concern about the fate of pharmaceutical products has raised owing to the increasing contamination of rivers, lakes and groundwater. The aim of this paper is to evaluate two different processes for paracetamol removal. The catalytic wet air oxidation (CWAO) of paracetamol on activated carbon was investigated both as a water treatment technique using an autoclave reactor and as a regenerative treatment of the carbon after adsorption in a sequential fixed bed process. Three activated carbons (ACs) from different source materials were used as catalysts: two microporous basic ACs (S23 and C1) and a meso- and micro-porous acidic one (L27). During the first CWAO experiment the adsorption capacity and catalytic performance of fresh S23 and C1 were higher than those of fresh L27 despite its higher surface area. This situation changed after AC reuse, as finally L27 gave the best results after five CWAO cycles. Respirometry tests with activated sludge revealed that in the studied conditions the use of CWAO enhanced the aerobic biodegradability of the effluent. In the ADOX process L27 also showed better oxidation performances and regeneration efficiency. This different ageing was examined through AC physico-chemical properties.

  6. Dynamics of the wet granular Leidenfrost phenomenon.

    Science.gov (United States)

    Roeller, Klaus; Herminghaus, Stephan

    2012-08-01

    By event-driven molecular dynamics simulations, we study the Leidenfrost effect for wet granular matter driven from below. In marked contrast to all earlier studies on other fluids, the dense plug hovering on the hot gas cushion undergoes an undamped oscillation. The location of the Hopf bifurcation leading to this oscillation is strongly dependent on the inelasticity of the grain impacts. The vertical separation into a gas phase with a condensed plug hovering above it is particularly pronounced due to the cohesiveness of the granulate. For sufficiently large system sizes, the Rayleigh-Taylor instability terminates the oscillatory state at late times.

  7. Experimental and visual study on flow patterns and pressure drops in U-tubes

    International Nuclear Information System (INIS)

    Da Silva Lima, J. R.

    2011-01-01

    In single- and two-phase flow heat exchangers (in particular 'coils'), besides the straight tubes there are also many singularities, in particular the 180° return bends (also called return bends or U-bends). However, contrary to the literature concerning pressure drops and heat transfer in straight tubes, where many experimental data and predicting methods are available, only a limited number of studies concerning U-bends can be found. Neither reliable experimental data nor proven prediction methods are available. Indeed, flow structure, pressure drop and heat transfer in U-bends are an old unresolved design problem in the heat transfer industry. Thus, the present study aims at providing further insight on two-phase pressure drops and flows patterns in U-bends. Based on a new type of U-bend test section, an extensive experimental study was conducted. The experimental campaign covered five test sections with three internal diameters (7.8, 10.8 and 13.4 mm), five bend diameters (24.8, 31.7, 38.1, 54.8 and 66.1 mm), tested for three orientations (horizontal, vertical upflow and vertical downflow), two fluids (R134a and R410A), two saturation temperatures (5 and 10 °C) and mass velocities ranging from 150 to 1000 kg s -1 m -2 . The flow pattern observations identified were stratified-wavy, slug-stratified-wavy, intermittent, annular, dryout and mist flows. The effects of the U-bend on the flow patterns were also observed. A total of 5655 pressure drop data were measured at seven different locations in the test section ( straight tubes and U-bend) providing a total of almost 40,000 data points. The straight tube data were first used to improve the actual two-phase straight tube model of Moreno-Quibén and Thome. This updated model was then used to developed a two-phase U-bend pressure drop model. Based on a comparison between experimental and predicted values, it is concluded that the new two-phase frictional pressure drop model for U-bends successfully

  8. Surfactant Facilitated Spreading of Aqueous Drops on Hydrophobic Surfaces

    Science.gov (United States)

    Kumar, Nitin; Couzis, Alex; Maldareili, Charles; Singh, Bhim (Technical Monitor)

    2001-01-01

    Microgravity technologies often require aqueous phases to spread over nonwetting hydrophobic solid surfaces. Surfactants facilitate the wetting of water on hydrophobic surfaces by adsorbing on the water/air and hydrophobic solid/water interfaces and lowering the surface tensions of these interfaces. The tension reductions decrease the contact angle, which increases the equilibrium wetted area. Hydrocarbon surfactants; (i.e., amphiphiles with a hydrophobic moiety consisting of an extended chain of (aliphatic) methylene -CH2- groups attached to a large polar group to give aqueous solubility) are capable of reducing the contact angles on surfaces which are not very hydrophobic, but do not reduce significantly the contact angles of the very hydrophobic surfaces such as parafilm, polyethylene or self assembled monolayers. Trisiloxane surfactants (amphiphiles with a hydrophobe consisting of methyl groups linked to a trisiloxane backbone in the form of a disk ((CH3)3-Si-O-Si-O-Si(CH3)3) and an extended ethoxylate (-(OCH2CH2)a-) polar group in the form of a chain with four or eight units) can significantly reduce the contact angle of water on a very hydrophobic surface and cause rapid and complete (or nearly complete) spreading (termed superspreading). The overall goal of the research described in this proposal is to establish and verify a theory for how trisiloxanes cause superspreading, and then use this knowledge as a guide to developing more general hydrocarbon based surfactant systems which superspread. We propose that the trisiloxane surfactants superspread because their structure allows them to strongly lower the high hydrophobic solid/aqueous tension when they adsorb to the solid surface. When the siloxane adsorbs, the hydrophobic disk parts of the molecule adsorb onto the surface removing the surface water. Since the cross-sectional area of the disk is larger than that of the extended ethoxylate chain, the disks can form a space-filling mat on the surface which

  9. Interface analysis of embedded chip resistor device package and its effect on drop shock reliability.

    Science.gov (United States)

    Park, Se-Hoon; Kim, Sun Kyoung; Kim, Young-Ho

    2012-04-01

    In this study, the drop reliability of an embedded passive package is investigated under JESD22-B111 condition. Chip resistors were buried in a PCB board, and it was electrically interconnected by electroless and electrolytic copper plating on a tin pad of a chip resistor without intermetallic phase. However tin, nickel, and copper formed a complex intermetallic phase, such as (Cu, Ni)6Sn5, (Cu, Ni)3Sn, and (Ni, Cu)3Sn2, at the via interface and via wall after reflow and aging. Since the amount of the tin layer was small compared with the solder joint, excessive intermetallic layer growth was not observed during thermal aging. Drop failures are always initiated at the IMC interface, and as aging time increases Cu-Sn-Ni IMC phases are transformed continuously due to Cu diffusion. We studied the intermetallic formation of the Cu via interface and simulated the stress distribution of drop shock by using material properties and board structure of embedded passive boards. The drop simulation was conducted according to the JEDEC standard. It was revealed that the crack starting point related to failure fracture changed due to intermetallic phase transformation along the via interface, and the position where failure occurs experimentally agrees well with our simulation results.

  10. The " Daphnia" Lynx Mark I Suborbital Flight Experiment: Hardware Qualification at the Drop Tower Bremen

    Science.gov (United States)

    Knie, Miriam; Schoppmann, Kathrin; Eck, Hendrik; Ribeiro, Bernard Wolfschoon; Laforsch, Christian

    2016-06-01

    The Drop Tower Bremen, a ground-based facility enabling research under real microgravity conditions, is an excellent platform for testing new types of experimental hardware to ensure full performance when deployed in costly and rare flight opportunities such as suborbital flights. Here we describe the " Daphnia" experiment which will fly on XCOR Aerospace Lynx Mark I and our experience from the hardware tests with the catapult system at the drop tower. The aim of the " Daphnia" experiment is to obtain data on the biological performance of daphnids and predator-prey interactions in microgravity, which are important for the development of aquatic bioregenerative life support systems (BLSS). The experiment consists of two subunits: The first unit is dedicated to predator-prey interactions, where behavioural analysis should reveal if microgravity interfere with prey ( Daphnia) detection or feeding and therefore may interrupt the trophic cascade. The functioning of such an artificial food web is indispensable for a long-lasting BLSS suitable for long-duration manned space missions or Earth-based explorations to extreme habitats. The second unit is designed to investigate the impact of microgravity on gene expression and the cytoskeleton in Daphnia. Next to data collection, the real microgravity conditions at the drop tower have helped to identify the weak points of the " Daphnia" experimental hardware and lead to further improvement. Hence, the drop tower is ideal for testing new experimental hardware which is indispensable before the implementation in suborbital flights.

  11. A Novel Method for Measuring In-Shoe Navicular Drop during Gait

    Directory of Open Access Journals (Sweden)

    Henrik Karstoft

    2012-08-01

    Full Text Available Analysis of foot movement is essential in the treatment and prevention of foot-related disorders. Measuring the in-shoe foot movement during everyday activities, such as sports, has the potential to become an important diagnostic tool in clinical practice. The current paper describes the development of a thin, flexible and robust capacitive strain sensor for the in-shoe measurement of the navicular drop. The navicular drop is a well-recognized measure of foot movement. The position of the strain sensor on the foot was analyzed to determine the optimal points of attachment. The sensor was evaluated against a state-of-the-art video-based system that tracks reflective markers on the bare foot. Preliminary experimental results show that the developed strain sensor is able to measure navicular drop on the bare foot with an accuracy on par with the video-based system and with a high reproducibility. Temporal comparison of video-based, barefoot and in-shoe measurements indicate that the developed sensor measures the navicular drop accurately in shoes and can be used without any discomfort for the user.

  12. A new method suitable for calculating accurately wetting temperature over a wide range of conditions: Based on the adaptation of continuation algorithm to classical DFT

    Science.gov (United States)

    Zhou, Shiqi

    2017-11-01

    A new scheme is put forward to determine the wetting temperature (Tw) by utilizing the adaptation of arc-length continuation algorithm to classical density functional theory (DFT) used originally by Frink and Salinger, and its advantages are summarized into four points: (i) the new scheme is applicable whether the wetting occurs near a planar or a non-planar surface, whereas a zero contact angle method is considered only applicable to a perfectly flat solid surface, as demonstrated previously and in this work, and essentially not fit for non-planar surface. (ii) The new scheme is devoid of an uncertainty, which plagues a pre-wetting extrapolation method and originates from an unattainability of the infinitely thick film in the theoretical calculation. (iii) The new scheme can be similarly and easily applied to extreme instances characterized by lower temperatures and/or higher surface attraction force field, which, however, can not be dealt with by the pre-wetting extrapolation method because of the pre-wetting transition being mixed with many layering transitions and the difficulty in differentiating varieties of the surface phase transitions. (iv) The new scheme still works in instance wherein the wetting transition occurs close to the bulk critical temperature; however, this case completely can not be managed by the pre-wetting extrapolation method because near the bulk critical temperature the pre-wetting region is extremely narrow, and no enough pre-wetting data are available for use of the extrapolation procedure.

  13. On the semiclassical description of nuclear Fermi liquid drops

    International Nuclear Information System (INIS)

    Schuck, P.

    1983-11-01

    In this series of lectures we aimed at presenting a self-contained semiclassical theory entirely based on the extended Thomas-Fermi or Wigner-Kirkwood h expansion in phase space. We saw that not only the Wigner transform of the single particle density matrix can be understood and very accurately represented in this way but that also generalisations to correlation functions are straightforward. First, we demonstrated a generalisation to superfluid nuclei and to superfluid nuclei in slow rotation. The latter involves already the (static) particle-hole correlation function and we saw how e.g. the reduction of the moment of inertia by roughly a factor of two could be explained very easily in an analytic way. We very clearly pointed out the necessity to treat particles (holes) individually in Thomas Fermi approximation. A further very promising result is that the linear response function for transferred momenta q>0.6 fm -1 can be very accurately represented in our p-h-Thomas Fermi approach. In the last paragraph we give somewhat speculative arguments that say the 2 + states of quasi macroscopic Fermi Liquid Drops could be well calculated in expanding the time dependent density matrix on a set of coherent states and a simple example for nearly harmonic potentials is given

  14. Total sleep time severely drops during adolescence.

    Directory of Open Access Journals (Sweden)

    Damien Leger

    Full Text Available UNLABELLED: Restricted sleep duration among young adults and adolescents has been shown to increase the risk of morbidities such as obesity, diabetes or accidents. However there are few epidemiological studies on normal total sleep time (TST in representative groups of teen-agers which allow to get normative data. PURPOSE: To explore perceived total sleep time on schooldays (TSTS and non schooldays (TSTN and the prevalence of sleep initiating insomnia among a nationally representative sample of teenagers. METHODS: Data from 9,251 children aged 11 to 15 years-old, 50.7% of which were boys, as part of the cross-national study 2011 HBSC were analyzed. Self-completion questionnaires were administered in classrooms. An estimate of TSTS and TSTN (week-ends and vacations was calculated based on specifically designed sleep habits report. Sleep deprivation was estimated by a TSTN - TSTS difference >2 hours. Sleep initiating nsomnia was assessed according to International classification of sleep disorders (ICSD 2. Children who reported sleeping 7 hours or less per night were considered as short sleepers. RESULTS: A serious drop of TST was observed between 11 yo and 15 yo, both during the schooldays (9 hours 26 minutes vs. 7 h 55 min.; p<0.001 and at a lesser extent during week-ends (10 h 17 min. vs. 9 h 44 min.; p<0.001. Sleep deprivation concerned 16.0% of chidren aged of 11 yo vs. 40.5% of those of 15 yo (p<0.001. Too short sleep was reported by 2.6% of the 11 yo vs. 24.6% of the 15 yo (p<0.001. CONCLUSION: Despite the obvious need for sleep in adolescence, TST drastically decreases with age among children from 11 to 15 yo which creates significant sleep debt increasing with age.

  15. Differences in CAPE between wet and dry spells of the monsoon over the southeastern peninsular India

    Science.gov (United States)

    Mohan, T. S.; Rao, T. N.; Rajeevan, M.

    2018-03-01

    In the present research we explored the variability of convective available potential energy (CAPE) during wet and dry spells over southeast India. Comparison between India Meteorological Department (IMD) observations and reanalysis products (NCEP, ERA-interim, and MERRA) reconfirms that gridded data sets can be utilized to fill the void of observations. Later, GPS radiosonde measurements made at Gadanki (13.5 N, 79.2 E) Andre analysis output are utilized to address key scientific issues related to CAPE over the southeastern peninsular region. They are: (1) How does CAPE vary between different spells of the Indian summer monsoon (i.e., from wet to dry spell)? (2) Does differences in CAPE and in the vertical structure of buoyancy between spells are localized features over Gadanki or observed all over southeastern peninsular region? (3) What physical/dynamical processes are responsible for the differences in CAPE between spells and how do they affect the convection growth in dry spell? Interestingly, CAPE is higher in wet spell than in dry spell, in contrast to the observations made elsewhere over land and warm oceans. Similar feature (high CAPE in wet spell) is observed at all grid points in the southeastern peninsular India. Furthermore, vertical buoyancy profiles show only one peak in the middle-upper troposphere in wet spell, while two peaks are observed in most of the profiles (66%) in dry spell over the entire study region in all the reanalysis products. Plausible mechanisms are discussed for the observed CAPE differences. They are, among others, timing of sounding with reference to rain occurrence, rapid buildup of surface instabilities, moistening of lower troposphere by evaporation of the surface moisture in wet spell, enhanced low-level moisture convergence, evaporation of rain in relatively warm and dry atmosphere, and reduction of positive buoyancy in dry spell. The omnipresence of stable layers and strong and deep shear in the presence of weak updrafts

  16. Anti-wetting Cu/Cr coating with micro-posts array structure fabricated by electrochemical approaches

    International Nuclear Information System (INIS)

    Zhou, Yufeng; Hang, Tao; Li, Feng; Li, Ming

    2013-01-01

    Microposts structured Cu/Cr multilayer coating was prepared by a simple two-step approach combining electroless and electro deposition. Surface morphologies of the as-prepared Cu/Cr multilayer coating characterized by field emission scanning electron microscopy show that this multilayer coating exhibits micro-posts arrayed structure with a layer of Cr uniformly covering the circular conical surface of Cu micro-cones array. The wettability test shows that the contact angle of Cu/Cr multilayer surface with water drop can be greater than 140° by optimizing the electrodeposition time of Cr. The mechanism of hydrophobicity of both the micro-cones arrayed and micro-posts arrayed structures was briefly discussed by comparing two different wetting modes. Due to its good anti-wetting property and unique structure, the micro-posts arrayed Cu/Cr multilayer coating is expected for extensive practical applications.

  17. Observation of a sequence of wetting transitions in the binary water+ethylene glycol monobutyl ether mixture

    Science.gov (United States)

    Wu, Chih-Kang; Chen, Li-Jen

    2005-08-01

    A homemade pendant drop/bubble tensiometer was assembled and applied to perform the surface-interfacial tension measurements for the binary water+ethylene glycol monobutyl ether (C4E1) mixture over the temperature range from 50to128°C at 10bar. The symbol CiEj is the abbreviation of a nonionic polyoxyethylene alcohol CiH2i+1(OCH2CH2)jOH. The wetting behavior of the C4E1-rich phase at the interface separating the gas and the aqueous phases was systematically examined according to the wetting coefficient calculated from the experimental results of surface/interfacial tensions. It was found that the C4E1-rich phase exhibits a sequence of wetting transitions, nonwetting→partial wetting→complete wetting, at the gas-water interface in the water+C4E1 system along with increasing the temperature, consistent with the conjecture of Kahlweit and Busse [J. Chem. Phys. 91, 1339 (1989)]. In addition, the relationship of the mutual solubility and the interfacial tension of the interface separating the C4E1-rich phase and the aqueous phase is discussed.

  18. Detection of bubble nucleation event in superheated drop detector ...

    Indian Academy of Sciences (India)

    2016-12-08

    Dec 8, 2016 ... Superheated drop detector consisting of drops of superheated liquid suspended in polymer or gel matrix is of great demand, mainly ... ing to which as the radiation deposits energy along its path inside the superheated liquid, ... resistance with change in pressure in a system. The frequency response of the ...

  19. Why Did They Not Drop Out? Narratives from Resilient Students

    Science.gov (United States)

    Lessard, Anne; Fortin, Laurier; Marcotte, Diane; Potvin, Pierre; Royer, Egide

    2009-01-01

    There is much to be learned from students who were at-risk for dropping out of school but persevered and graduated. The purpose of the study on which this article is based, was to describe how students who were at-risk for dropping out of school persevered and graduated. The voices of two students are introduced, highlighting the challenges they…

  20. SAW-controlled drop size for flow focusing.

    Science.gov (United States)

    Schmid, Lothar; Franke, Thomas

    2013-05-07

    We demonstrate the regularization of droplet formation by applying a surface acoustic wave (SAW) localized at the flow-focus junction of a drop maker. This allows electronic control of drop size in real time, without changing the flow rates or microchannel dimensions.

  1. Vortex Shedding and Depinning of Wind-Forced Liquid Drops

    Science.gov (United States)

    Simon, Roger; White, Edward

    2017-11-01

    Water drops adhere to solid substrates but can depin when wind forcing exceeds the adhesion force provided by surface tension. Schmucker and White (2012.DFD.M4.6) measured critical wind forcing limits for high-Reynolds-number airflow forcing and found a critical constant Weber number, Wecrit = 8.0 , for a range of drop Bond numbers. This work seeks to identify what behavior is associated with Wecrit = 8.0 and why wind-forced drops depin when they do. One hypothesis suggests that, at high Reynolds numbers, drops depin when their interface natural frequency matches the frequency of air vortex shedding in the separated drop wake. We investigate whether a resonance between vortex shedding and drop interface oscillations is involved with depinning. We measure the shedding frequencies behind solid protuberances of the same size as typical drops and, separately, water-drop interface frequencies. We compare our measured values under different flow conditions to establish whether shedding and interface resonance are related to depinning. 1Supported by the National Science Foundation through Grant CBET-1605947.

  2. 14 CFR 23.725 - Limit drop tests.

    Science.gov (United States)

    2010-01-01

    ... used in the drop test (lbs.); h=specified free drop height (inches); d=deflection under impact of the tire (at the approved inflation pressure) plus the vertical component of the axle travel relative to... must be made on the complete airplane, or on units consisting of wheel, tire, and shock absorber, in...

  3. Evaluation of Sodium Sulphacetamide drops in the Treatment of ...

    African Journals Online (AJOL)

    Sodium sulphacetamide eye drops had been used successfully in the past in the treatment of ophthalmia neonatorium (ON) but its use has decreased remarkably in recent time. The efficacy of 10 percent sodium sulphacetamide eye drops in the treatment of ON was prospectively evaluated in 68 neonates seen in our ...

  4. Student Drop-Out from German Higher Education Institutions

    Science.gov (United States)

    Heublein, Ulrich

    2014-01-01

    28% of students of any one year currently give up their studies in bachelor degree programmes at German higher education institutions. Drop-out is to be understood as the definite termination in the higher education system without obtaining an academic degree. The drop-out rate is thereby calculated with the help of statistical estimation…

  5. Complex cooling water systems optimization with pressure drop consideration

    CSIR Research Space (South Africa)

    Gololo, KV

    2012-12-01

    Full Text Available Pressure drop consideration has shown to be an essential requirement for the synthesis of a cooling water network where reuse/recycle philosophy is employed. This is due to an increased network pressure drop associated with additional reuse...

  6. Reconfigurable Optical Add-Drop Multiplexer Using Microring Resonators

    NARCIS (Netherlands)

    Klein, E.J.; Geuzebroek, D.H.; Kelderman, H.; Sengo, G.; Sengo, G.; Baker, Nigel; Driessen, A.

    2005-01-01

    We report a reconfigurable four-channel optical add–drop multiplexer for use in access networks. The optical add–drop multiplexer (OADM) is based on vertically coupled thermally tunable $Si_3N_4$ – $SiO_2$ microring resonators (MRs) and has been realized on a footprint of 0.25 mm2. Individual MRs in

  7. Drop shape visualization and contact angle measurement on curved surfaces.

    Science.gov (United States)

    Guilizzoni, Manfredo

    2011-12-01

    The shape and contact angles of drops on curved surfaces is experimentally investigated. Image processing, spline fitting and numerical integration are used to extract the drop contour in a number of cross-sections. The three-dimensional surfaces which describe the surface-air and drop-air interfaces can be visualized and a simple procedure to determine the equilibrium contact angle starting from measurements on curved surfaces is proposed. Contact angles on flat surfaces serve as a reference term and a procedure to measure them is proposed. Such procedure is not as accurate as the axisymmetric drop shape analysis algorithms, but it has the advantage of requiring only a side view of the drop-surface couple and no further information. It can therefore be used also for fluids with unknown surface tension and there is no need to measure the drop volume. Examples of application of the proposed techniques for distilled water drops on gemstones confirm that they can be useful for drop shape analysis and contact angle measurement on three-dimensional sculptured surfaces. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. The origin of star-shaped oscillations of Leidenfrost drops

    Science.gov (United States)

    Ma, Xiaolei; Burton, Justin C.

    We experimentally investigate the oscillations of Leidenfrost drops of water, liquid nitrogen, ethanol, methanol, acetone and isopropyl alcohol. The drops levitate on a cushion of evaporated vapor over a hot, curved surface which keeps the drops stationary. We observe star-shaped modes along the periphery of the drop, with mode numbers n = 2 to 13. The number of observed modes is sensitive to the properties of the liquid. The pressure oscillation frequency in the vapor layer under the drop is approximately twice that of the drop frequency, which is consistent with a parametric forcing mechanism. However, the Rayleigh and thermal Marangoni numbers are of order 10,000, indicating that convection should play a dominating role as well. Surprisingly, we find that the wavelength and frequency of the oscillations only depend on the thickness of the liquid, which is twice the capillary length, and do not depend on the mode number, substrate temperature, or the substrate curvature. This robust behavior suggests that the wavelength for the oscillations is set by thermal convection inside the drop, and is less dependent on the flow in the vapor layer under the drop

  9. Simulation of the drop impact test for moulded thermoplastic containers

    NARCIS (Netherlands)

    Reed, P.E.; Breedveld, G.; Lim, B.C.

    2000-01-01

    An analysis is made of the drop impact test for moulded plastics containers, as a first step towards the simulation of the impact event for design and development purposes. Experimental data are analysed from instrumented base drop impact testing of water-filled blow-moulded bottles, 20 and 210 l

  10. Microbial communities associated with wet flue gas desulfurization systems

    Directory of Open Access Journals (Sweden)

    Bryan P. Brown

    2012-11-01

    Full Text Available Flue gas desulfurization (FGD systems are employed to remove SOx gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal fired electricity generation facilities were evaluated using culture-dependent and –independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems.

  11. Microbial communities associated with wet flue gas desulfurization systems

    Science.gov (United States)

    Brown, Bryan P.; Brown, Shannon R.; Senko, John M.

    2012-01-01

    Flue gas desulfurization (FGD) systems are employed to remove SOx gasses that are produced by the combustion of coal for electric power generation, and consequently limit acid rain associated with these activities. Wet FGDs represent a physicochemically extreme environment due to the high operating temperatures and total dissolved solids (TDS) of fluids in the interior of the FGD units. Despite the potential importance of microbial activities in the performance and operation of FGD systems, the microbial communities associated with them have not been evaluated. Microbial communities associated with distinct process points of FGD systems at several coal-fired electricity generation facilities were evaluated using culture-dependent and -independent approaches. Due to the high solute concentrations and temperatures in the FGD absorber units, culturable halothermophilic/tolerant bacteria were more abundant in samples collected from within the absorber units than in samples collected from the makeup waters that are used to replenish fluids inside the absorber units. Evaluation of bacterial 16S rRNA genes recovered from scale deposits on the walls of absorber units revealed that the microbial communities associated with these deposits are primarily composed of thermophilic bacterial lineages. These findings suggest that unique microbial communities develop in FGD systems in response to physicochemical characteristics of the different process points within the systems. The activities of the thermophilic microbial communities that develop within scale deposits could play a role in the corrosion of steel structures in FGD systems. PMID:23226147

  12. What's So Bad about Being Wet All Over: Investigating Leaf Surface Wetness.

    Science.gov (United States)

    Brewer, Carol A.

    1996-01-01

    Presents investigations of leaf surface wetness that provide ideal opportunities for students to explore the relationships between leaf form and function, to study surface conditions of leaves and plant physiology, and to make predictions about plant adaptation in different environments. Describes simple procedures for exploring questions related…

  13. Reactive wetting by liquid sodium on thin Au platin

    International Nuclear Information System (INIS)

    Kawaguchi, Munemichi; Hamada, Hirotsugu

    2014-01-01

    For practical use of an under-sodium viewer, the behavior of sodium wetting is investigated by modeling the reactive and non-reactive wetting of metallic-plated steels by liquid sodium to simulate sodium wetting. The non-reactive wetting simulation results showed good agreement with Tanner's law, in which the time dependencies of the droplet radius and contact angle are expressed as R N ∝ t 1/10 and θ∝ t -3/10 , respectively; therefore, the model was considered suitable for the simulation. To simulate reactive wetting, the model of fluid flow induced by the interfacial reaction was incorporated into the simulation of non-reactive wetting. The reactive wetting simulation results, such as the behavior of the precursor liquid film and central droplet, showed good agreement with sodium wetting experiments using thin Au plating at 250°C. An important result of the reactive wetting simulation is that the gradient of the reaction energy at the interface appeared on the new interface around the triple line, and that fluid flow was induced. This interfacial reactivity during sodium wetting of thin Au plating was enhanced by the reaction of sodium and nickel oxide through pinholes in the plating. (author)

  14. Capillary-inertial colloidal catapults upon drop coalescence

    Science.gov (United States)

    Chen, Chuan-Hua

    2016-01-01

    Surface energy released upon drop coalescence is known to power the self-propelled jumping of liquid droplets on superhydrophobic solid surfaces, and the jumping droplets can additionally carry colloidal payloads toward self-cleaning. Here, we show that drop coalescence on a spherical particle leads to self-propelled launching of the particle from virtually any solid surface. The main prerequisite is an intermediate wettability of the particle, such that the momentum from the capillary-inertial drop coalescence process can be transferred to the particle. By momentum conservation, the launching velocity of the particle-drop complex is proportional to the capillary-inertial velocity based on the drop radius and to the fraction of the liquid mass in the total mass. The capillary-inertial catapult is not only an alternative mechanism for removing colloidal contaminants, but also a useful model system for studying ballistospore launching. PMID:27478201

  15. Silicon wavelength-selective partial-drop broadcast filter bank.

    Science.gov (United States)

    Su, Zhan; Cherchi, Matteo; Timurdogan, Erman; Sun, Jie; Moresco, Michele; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R

    2014-09-15

    We propose an approach to a wavelength-selective 1×N port optical broadcast network demonstrating the approach in a 1×8 port parallel optical drop filter bank utilizing adiabatic micro-ring tunable filters. The micro-ring filters exhibit first-order 92.7±3.7 GHz full width at half-maximum bandwidths with a 36.2 nm free spectral range, low-drop power variation (0.11 dB), and aggregate excess loss of only 1.1 dB in all drop ports. Error-free operation at a 10 Gbit/s data rate is achieved for all eight drop ports with less than a 0.5 dB power penalty among the ports. This wavelength-selective parallel-drop approach serves as a building block for on-chip all-to-all communication networks.

  16. Drop tests of the Three Mile Island knockout canister

    International Nuclear Information System (INIS)

    Box, W.D.; Aaron, W.S.; Shappert, L.B.; Childress, P.C.; Quinn, G.J.; Smith, J.V.

    1987-01-01

    A type of Three Mile Island Unit 2 (TMI-2) defueling canister, called a ''knockout'' canister, was subjected to a series of drop tests at the Oak Ridge National Laboratory's Drop Test Facility. These tests confirmed the structural integrity of internal fixed neutron poisons in support of a request for NRC licensing of this type of canister for the shipment of TMI-2 reactor fuel debris to the Idaho National Engineering Laboratory (INEL) for the Core Examination R and D Program. This report presents the data generated and the results obtained from a series of four drop tests that included two drops with the test assembly in the vertical position and two drops with the assembly in the horizontal position

  17. About applicability of thermodynamic parameters to small drops and clusters

    Science.gov (United States)

    Kharlamov, G. V.; Onischuk, A. A.; Vosel, S. V.; Purtov, P. A.

    2012-11-01

    In our paper the results of molecular dynamics calculations of nanodrops are presented. The density profiles, the Irving-Kirkwood pressure tensors, the chemical potentials of the systems, the equimolar radii of the drops and the radii of tension, the mechanical and thermodynamic surface tensions have been calculated. It is shown that both the mechanical and thermodynamic surface tensions decrease with the decrease of the equimolar radius of the drop and reach zero at the same R0 depending on temperature. With the further equimolar radius decrease the surface tension becomes negative. It means that such droplet is metastable and that the notion of the macroscopic surface tension cannot be applied to such small drops. The dependence of the ratio of the drop surface tension to the surface tension of the flat liquid-vapor interface on the ratio of the drop equimolar radius to R0 is a universal function.

  18. About applicability of thermodynamic parameters to small drops and clusters

    International Nuclear Information System (INIS)

    Kharlamov, G V; Onischuk, A A; Vosel, S V; Purtov, P A

    2012-01-01

    In our paper the results of molecular dynamics calculations of nanodrops are presented. The density profiles, the Irving-Kirkwood pressure tensors, the chemical potentials of the systems, the equimolar radii of the drops and the radii of tension, the mechanical and thermodynamic surface tensions have been calculated. It is shown that both the mechanical and thermodynamic surface tensions decrease with the decrease of the equimolar radius of the drop and reach zero at the same R 0 depending on temperature. With the further equimolar radius decrease the surface tension becomes negative. It means that such droplet is metastable and that the notion of the macroscopic surface tension cannot be applied to such small drops. The dependence of the ratio of the drop surface tension to the surface tension of the flat liquid-vapor interface on the ratio of the drop equimolar radius to R 0 is a universal function.

  19. Building micro-soccer-balls with evaporating colloidal fakir drops

    Science.gov (United States)

    Gelderblom, Hanneke; Marín, Álvaro G.; Susarrey-Arce, Arturo; van Housselt, Arie; Lefferts, Leon; Gardeniers, Han; Lohse, Detlef; Snoeijer, Jacco H.

    2013-11-01

    Drop evaporation can be used to self-assemble particles into three-dimensional microstructures on a scale where direct manipulation is impossible. We present a unique method to create highly-ordered colloidal microstructures in which we can control the amount of particles and their packing fraction. To this end, we evaporate colloidal dispersion drops from a special type of superhydrophobic microstructured surface, on which the drop remains in Cassie-Baxter state during the entire evaporative process. The remainders of the drop consist of a massive spherical cluster of the microspheres, with diameters ranging from a few tens up to several hundreds of microns. We present scaling arguments to show how the final particle packing fraction of these balls depends on the drop evaporation dynamics, particle size, and number of particles in the system.

  20. Doubly Reentrant Cavities Prevent Catastrophic Wetting Transitions on Intrinsically Wetting Surfaces

    KAUST Repository

    Domingues, Eddy

    2017-06-05

    Omniphobic surfaces, i.e. which repel all known liquids, have proven of value in applications ranging from membrane distillation to underwater drag reduction. A limitation of currently employed omniphobic surfaces is that they rely on perfluorinated coatings, increasing cost and environmental impact, and preventing applications in harsh environments. There is, thus, a keen interest in rendering conventional materials, such as plastics, omniphobic by micro/nano-texturing rather than via chemical make-up, with notable success having been achieved for silica surfaces with doubly reentrant micropillars. However, we found a critical limitation of microtextures comprising of pillars that they undergo catastrophic wetting transitions (apparent contact angles, θr → 0° from θr > 90°) in the presence of localized physical damages/defects or on immersion in wetting liquids. In response, a doubly reentrant cavity microtexture is introduced, which can prevent catastrophic wetting transitions in the presence of localized structural damage/defects or on immersion in wetting liquids. Remarkably, our silica surfaces with doubly reentrant cavities could exhibited apparent contact angles, θr ≈ 135° for mineral oil, where the intrinsic contact angle, θo ≈ 20°. Further, when immersed in mineral oil or water, doubly reentrant microtextures in silica (θo ≈ 40° for water) were not penetrated even after several days of investigation. Thus, microtextures comprising of doubly reentrant cavities might enable applications of conventional materials without chemical modifications, especially in scenarios that are prone to localized damages or immersion in wetting liquids, e.g. hydrodynamic drag reduction and membrane distillation.

  1. Formulation of indomethacin eye drops via complexation with cyclodextrins.

    Science.gov (United States)

    Halim Mohamed, Maaly A; Mahmoud, Azza A

    2011-03-01

    Topically administered indomethacin is used in the management and prevention of ocular inflammation and cystoid macular edema related to cataract surgery and in the maintenance of mydriasis during cataract surgery. Pharmaceutically, the main obstacle in formulating indomethacin as eye drops is its low solubility and aqueous instability. Inclusion complexation of indomethacin with cyclodextrins (CDs) was our interest in this research to obtain stable and effective aqueous indomethacin eye drops. The influence of β-CD, hydroxypropyl-β-CD (HP-β-CD), and sulfobutyl ether-β-CD (SBE-β-CD) on indomethacin solubility was investigated. Indomethacin-HP-β-CD complex was prepared and characterized by infrared spectroscopy, differential scanning calorimetry, and X-ray diffractometry and was subjected to in vitro release and stability studies. The anti-inflammatory effect of formulated indomethacin-HP-β-CD eye drops on chemically burned albino rabbit eyes was compared to those of Indocollyre(®) and Voltaren(®) eye drops. HP-β-CD was found to have a high solubilizing effect towards indomethacin and was thus selected for its formulation. Formulated indomethacin-HP-β-CD eye drops exhibited delayed release and high drug stability compared to the drug solution. Draize rabbit eye irritation test and histological examination on albino rabbit eyes treated with indomethacin-HP-β-CD eye drops revealed that these eye drops were non-irritant. The anti-inflammatory studies indicated that formulating indomethacin eye drops via complexation with HP-β-CD significantly improves the therapeutic efficacy of the indomethacin compared to the investigated eye drops. An aqueous ocular delivery system for the poor water soluble anti-inflammatory indomethacin was prepared using HP-β-CD as a complexing agent. Besides a sufficient solubility for the drug, many factors were studied in the development of this system, such as stability and safety. In addition, indomethacin-HP-β-CD eye drops

  2. Thermodynamic study contribution of U-Fe and U-Ga alloys by high temperature mass spectroscopy, and of the wetting of yttrium oxide by uranium

    International Nuclear Information System (INIS)

    Gardie, P.

    1992-01-01

    High temperature thermodynamic properties study of U-Fe and U-Ga alloys, and wetting study of yttrium oxide by uranium are presented. High temperature mass spectrometry coupled to a Knudsen effusion multi-cell allows to measure iron activity in U-Fe alloys and of gallium in U-Ga alloys, the U activity is deduced from Gibbs-Duhem equation. Wetting of the system U/Y 2 O 3-x is studied between 1413 K and 1973 K by the put drop method visualized by X-rays. This technique also furnishes density, surface tension of U and of U-Fe alloys put on Y 2 O 3-x . A new model of the interfacial oxygen action on wetting is done for the system U/Y 2 O 3-x . (A.B.)

  3. The Steiner ratio for points on a triangular lattice | de Wet | ORiON

    African Journals Online (AJOL)

    The study of spanning trees and Steiner trees arises naturally in applications, such as in the design of integrated circuit boards, communication networks, power networks and pipelines of minimum cost. In such applications the Steiner ratio is an indication of how badly a minimum spanning tree performs compared to a ...

  4. The Steiner ratio for points on a triangular lattice | de Wet | ORiON

    African Journals Online (AJOL)

    Journal Home > Vol 24, No 2 (2008) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Download this PDF file. The PDF file you selected should load here if your Web browser has a PDF reader plug-in installed (for example, a recent version of Adobe Acrobat ...

  5. Effect of Brine Composition on Wettability Alteration and Oil Recovery from Oil-wet Carbonate Rocks

    Science.gov (United States)

    Purswani, P.; Karpyn, Z.

    2016-12-01

    Brine composition is known to affect the effectiveness of waterflooding during enhanced oil recovery from carbonate reservoirs. Recent studies have identified Mg2+, Ca2+ and SO42- as critical ions, responsible for incremental oil recovery via wettability alteration. To investigate the underlying mechanism of wettability alteration and, to evaluate the individual contribution of these ions towards improving oil recovery, a series of coreflooding experiments are performed. Various characterization techniques like zeta potential (ZP), drop angle analysis and inductively coupled plasma mass spectrometry (ICP MS) analysis are performed to evaluate the surface interactions taking place at the carbonate core samples, brine solution and crude oil interfaces. Total dissolved solids and electrical conductivity measurements confirm the ionic strength of the brine samples. Acid number calculations, ZP and contact angle measurements confirm the initial oil-wetting state of the core. ICP MS analysis of the effluent brine, confirm the relationship between the ionic interactions and oil recovery.

  6. The results of the measurements of mass- and heat-transfer in the wet cooling tower

    International Nuclear Information System (INIS)

    Fabjan, Lj.; Gaspersic, B.

    1979-01-01

    These are the results of our investigations carried out on a packing inside a wet cooling tower for the purpose of studying the mass and heat transfer at the counterflow of water and humid air. The measurements on the experimental tower of the corresponding mathematical model reflect the average coefficient of mass and heat transfer for the unity of the active volume. Further the measurements of pressure drop at the air flow were carried out and thus the coefficient of aerodynamic losses were obtained. The results of measurements are given in the corresponding equations with the dimensionless numbers and diagrams. They will be of great use for the planning of new cooling towers. (author)

  7. Tympanoplasty: does dry or wet temporalis fascia graft matter?

    Science.gov (United States)

    Singh, G B; Kumar, D; Aggarwal, K; Garg, S; Arora, R; Kumar, S

    2016-08-01

    To evaluate the success rate of dry and wet temporalis fascia grafts in type I underlay tympanoplasty. A prospective, randomised study was conducted. One hundred adult patients (males and females) with chronic suppurative otitis media (mucosal type) were divided into 2 groups of 50 each: one group underwent dry graft tympanoplasty and the other underwent wet graft tympanoplasty. Fibroblast count was calculated in dry and wet grafts. The dry graft and wet graft groups had overall surgical success rates of 82 and 90 per cent, respectively; this finding was not statistically significant. A statistically significant high fibroblast count was observed in wet grafts, but it did not correlate with surgical success. A dry or wet temporalis fascia graft does not influence the outcome of tympanoplasty type I.

  8. Wet-cupping removes oxidants and decreases oxidative stress.

    Science.gov (United States)

    Tagil, Suleyman Murat; Celik, Huseyin Tugrul; Ciftci, Sefa; Kazanci, Fatmanur Hacievliyagil; Arslan, Muzeyyen; Erdamar, Nazan; Kesik, Yunus; Erdamar, Husamettin; Dane, Senol

    2014-12-01

    Wet-cupping therapy is one of the oldest known medical techniques. Although it is widely used in various conditions such as acute\\chronic inflammation, infectious diseases, and immune system disorders, its mechanism of action is not fully known. In this study, we investigated the oxidative status as the first step to elucidate possible mechanisms of action of wet cupping. Wet cupping therapy is implemented to 31 healthy volunteers. Venous blood samples and Wet cupping blood samples were taken concurrently. Serum nitricoxide, malondialdehyde levels and activity of superoxide dismutase and myeloperoxidase were measured spectrophotometrically. Wet cupping blood had higher activity of myeloperoxidase, lower activity of superoxide dismutase, higher levels of malondialdehyde and nitricoxide compared to the venous blood. Wet cupping removes oxidants and decreases oxidative stress. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Proteomic effects of wet cupping (Al-hijamah).

    Science.gov (United States)

    Almaiman, Amer A

    2018-01-01

    Wet cupping (Al-hijamah) is a therapeutic technique practiced worldwide as a part of the Unani system of medicine. It involves bloodletting from acupoints on a patient's skin to produce a therapeutic outcome. A thorough review of research articles on wet cupping with relevance to proteomics field that are indexed by Google Scholar, PubMed, and/or Science Direct databases was performed. Eight original research articles were summarized in this paper. Overall, wet cupping did not have a significant effect on C-reactive protein, Hsp-27, sister chromatid exchanges, and cell replication index. In contrast, wet cupping was found to produce higher oxygen saturation, eliminate lactate from subcutaneous tissues, remove blood containing higher levels of malondialdehyde and nitric oxide, and produce higher activity of myeloperoxidase. The proteomic effects of wet cupping therapy have not been adequately investigated. Thus, future studies on wet cupping that use systemic and sound protocols to avoid bias should be conducted.

  10. Dynamic wetting with viscous Newtonian and non-Newtonian fluids

    International Nuclear Information System (INIS)

    Wei, Y; Garoff, S; Rame, E; Walker, L M

    2009-01-01

    We examine various aspects of dynamic wetting with viscous Newtonian and non-Newtonian fluids. Rather than concentrating on the mechanisms that relieve the classic contact line stress singularity, we focus on the behavior in the wedge flow near the contact line which has the dominant influence on wetting with these fluids. Our experiments show that a Newtonian polymer melt composed of highly flexible molecules exhibits dynamic wetting behavior described very well by hydrodynamic models that capture the critical properties of the Newtonian wedge flow near the contact line. We find that shear thinning has a strong impact on dynamic wetting, by reducing the drag of the solid on the fluid near the contact line, while the elasticity of a Boger fluid has a weaker impact on dynamic wetting. Finally, we find that other polymeric fluids, nominally Newtonian in rheometric measurements, exhibit deviations from Newtonian dynamic wetting behavior.

  11. Full-Scale Testing of a Mercury Oxidation Catalyst Upstream of a Wet FGD System

    Energy Technology Data Exchange (ETDEWEB)

    Gary Blythe; Jennifer Paradis

    2010-06-30

    This document presents and discusses results from Cooperative Agreement DE-FC26-06NT42778, 'Full-scale Testing of a Mercury Oxidation Catalyst Upstream of a Wet FGD System,' which was conducted over the time-period July 24, 2006 through June 30, 2010. The objective of the project was to demonstrate at full scale the use of solid honeycomb catalysts to promote the oxidation of elemental mercury in pulverized-coal-fired flue gas. Oxidized mercury is removed downstream in wet flue gas desulfurization (FGD) absorbers and collected with the byproducts from the FGD system. The project was co-funded by EPRI, the Lower Colorado River Authority (LCRA), who also provided the host site, Great River Energy, Johnson Matthey, Southern Company, Salt River Project (SRP), the Tennessee Valley Authority (TVA), NRG Energy, Ontario Power and Westar. URS Group was the prime contractor and also provided cofunding. The scope of this project included installing and testing a gold-based catalyst upstream of one full-scale wet FGD absorber module (about 200-MW scale) at LCRA's Fayette Power Project (FPP) Unit 3, which fires Powder River Basin coal. Installation of the catalyst involved modifying the ductwork upstream of one of three wet FGD absorbers on Unit 3, Absorber C. The FGD system uses limestone reagent, operates with forced sulfite oxidation, and normally runs with two FGD modules in service and one spare. The full-scale catalyst test was planned for 24 months to provide catalyst life data. Over the test period, data were collected on catalyst pressure drop, elemental mercury oxidation across the catalyst module, and mercury capture by the downstream wet FGD absorber. The demonstration period began on May 6, 2008 with plans for the catalyst to remain in service until May 5, 2010. However, because of continual increases in pressure drop across the catalyst and concerns that further increases would adversely affect Unit 3 operations, LCRA decided to end the

  12. THERMAL TRANSFERS IN WET HYPERBARIC ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Tamara STANCIU

    2014-05-01

    Full Text Available The heat losses of human body are greater in underwater environment than in dry, normal atmosphere, due to the great heat capacity of water. Body temperature of divers in immersion was studied taking into account the pressure the divers are subjected to. The theoretic equation that describes the total heat transfer- at both levels: skin and respiratory system- was established, considering conduction, convection and respiratory gas heating and humidification. The body temperature of the divers was measured in a series of dives at different depths of immersion, conducted in the wet simulator of the Diving Center, in Constanta. The experimental results were in good accordance with the temperature predicted by the mathematical model.

  13. BERYLLIUM MEASUREMENT IN COMMERCIALLY AVAILABLE WET WIPES

    Energy Technology Data Exchange (ETDEWEB)

    Youmans-Mcdonald, L.

    2011-02-18

    Analysis for beryllium by fluorescence is now an established method which is used in many government-run laboratories and commercial facilities. This study investigates the use of this technique using commercially available wet wipes. The fluorescence method is widely documented and has been approved as a standard test method by ASTM International and the National Institute for Occupational Safety and Health (NIOSH). The procedure involves dissolution of samples in aqueous ammonium bifluoride solution and then adding a small aliquot to a basic hydroxybenzoquinoline sulfonate fluorescent dye (Berylliant{trademark} Inc. Detection Solution Part No. CH-2) , and measuring the fluorescence. This method is specific to beryllium. This work explores the use of three different commercial wipes spiked with beryllium, as beryllium acetate or as beryllium oxide and subsequent analysis by optical fluorescence. The effect of possible interfering metals such as Fe, Ti and Pu in the wipe medium is also examined.

  14. Textile UWB Antenna Bending and Wet Performances

    Directory of Open Access Journals (Sweden)

    Mai A. R. Osman

    2012-01-01

    Full Text Available The vision and ideas of wearable computing systems describe future electronic systems as an integral part of our everyday clothing that provides the wearer with such intelligent personal assistants. Recently, there has been growing interest in the antenna community to merge between wearable systems technology, ultrawideband (UWB technology and textile technology. This work aimed to make closer steps towards real wearability by investigating the possibilities of designing wearable UWB antenna where textile materials are used for the substrate as well as the conducting parts of the designed antenna. Two types of conducting materials have been used for conducting parts, while a nonconducting fabric has been used as antenna substrate material. A set of comparative results of the proposed design were presented and discussed. Moreover, effects on the return loss by means of measurements for each fabricated antenna prototype under bent and fully wet conditions were discussed in more details.

  15. Modelling spontaneous combustion in wet lignite

    Science.gov (United States)

    Gong, Rose; Burnell, John G.; Wake, Graeme C.

    1999-06-01

    A model of self-heating of wet coal is presented. This involves coupled heat and mass transport within a coal pile, together with an exothermic reaction and phase changes of water. There are four state variables: temperature, oxygen, water vapour and liquid water concentrations. Heat and mass are conducted or diffused through the pile, while simultaneously undergoing chemical reaction. As demonstrated by experiment, the heat release rate depends in a quadratic fashion on the liquid water content and this feature is a distinctive aspect of the model. After development of the model, an illustrative spatially uniform model of just three state variables (temperature, oxygen and liquid water concentrations) is analysed for its bifurcational structure of steady states, periodic solutions and their stability. By this means, thresholds for the onset of ignition can be determined as a function of the physical and chemical parameters.

  16. Wetting morphologies on chemically nanopatterned surfaces

    Science.gov (United States)

    Checco, Antonio; Gang, Oleg; Ocko, Benjamin M.

    2007-03-01

    We study the wetting of simple, volatile liquids on model chemical nanopatterns created using Local Oxidation Nanolithography. This technique makes use of a biased, metallic AFM tip to locally oxidize the methyl-terminations of a self-assembled monolayer (octadecylthrichlorosilane) into carboxylic acid termination[1]. With this method we have realized parallel, 50 to 500 nm wide, wettable stripes (carboxylic) embedded into a non-wettable (methyl) surface. Several organic (polar, non-polar), volatile liquids have been condensed onto the wettable stripes and the resulting droplet morphologies have been studied in-situ by using an environmental AFM. We show that close to saturation and for droplet thickness less than 10 nm long-range forces are relevant to the nanoliquid shape. These results are well described by Density Functional Theory assuming dispersive molecular interactions. In addition, we explore the dynamics of condensation/evaporation of the liquid nanodrops.

  17. Wet-Bulb-Globe Temperature Data Report

    Science.gov (United States)

    2015-03-01

    ARL‐SR‐0317 ● MAR 2015          US Army Research Laboratory      Wet‐ Bulb –Globe Temperature Data Report    by David P Sauter...originator.         ARL‐SR‐0317 ● MAR 2015      US Army Research Laboratory      Wet‐ Bulb –Globe Temperature Data Report    by David P Sauter...March 2015 2. REPORT TYPE  Special Report 3. DATES COVERED (From ‐ To)  11 Aug 2014–23 Aug 2014 4. TITLE AND SUBTITLE  Wet- Bulb –Globe Temperature

  18. Clinical Impact Upon Wound Healing and Inflammation in Moist, Wet, and Dry Environments

    Science.gov (United States)

    Junker, Johan P.E.; Kamel, Rami A.; Caterson, E.J.; Eriksson, Elof

    2013-01-01

    Significance Successful treatment of wounds relies on precise control and continuous monitoring of the wound-healing process. Wet or moist treatment of wounds has been shown to promote re-epithelialization and result in reduced scar formation, as compared to treatment in a dry environment. Recent Advances By treating wounds in a controlled wet environment, delivery of antimicrobials, analgesics, other bioactive molecules such as growth factors, as well as cells and micrografts, is allowed. The addition of growth factors or transplantation of cells yields the possibility of creating a regenerative wound microenvironment that favors healing, as opposed to excessive scar formation. Critical Issues Although several manufacturers have conceived products implementing the concept of moist wound healing, there remains a lack of commercial translation of wet wound-healing principles into clinically available products. This can only be mitigated by further research on the topic. Future Directions The strong evidence pointing to the favorable healing of wounds in a wet or moist environment compared to dry treatment will extend the clinical indications for this treatment. Further advances are required to elucidate by which means this microenvironment can be optimized to improve the healing outcome. PMID:24587972

  19. Upgrading wet granulation monitoring from hand squeeze test to mixing torque rheometry

    Science.gov (United States)

    Sakr, Walid F.; Ibrahim, Mohamed A.; Alanazi, Fars K.; Sakr, Adel A.

    2011-01-01

    With over 50 years of research in granulation technology, however more research is required to elucidate this widely applicable technology. Wetting phenomena could influence redistribution of individual ingredients within a granule according their solubility and also could affect the drying processes. Binder selection for a particular system is quite often empirical and dependent on the skills and experience of the formulator. Hand squeeze test was and still the main way for determination of wet granulation end point, but it is subjected to individual variation. It depends mainly on operator experience, so it is not possible to be validated. Literature reveals a variety of advanced monitoring techniques following up different wet massing stages. Torque measurement has been proved to be the most reliable control method as its tight relation to mass resistance. Many reports showed successful applications of mixing torque rheometer (MTR) for monitoring the wet massing procedure and scale up in addition to some preformulation applications. MTR as a new approach allows formulators to select a liquid addition range where the granule growth behavior is more predictable. PMID:23960772

  20. Mixing Behaviors of Wet Granular Materials in a Pulsating Fluidized Bed

    Science.gov (United States)

    Lim, Eldin Wee Chuan

    2017-11-01

    The Discrete Element Method combined with Computational Fluid Dynamics was coupled with a capillary liquid bridge force model for computational studies of mixing behaviors in a gas fluidized bed containing wet granular materials. There was a high tendency for wet particles to form large agglomerates within which relative motions between adjacent particles were hindered. This resulted in much lower mixing efficiencies compared with fluidization of dry particles. Capillary liquid bridge forces were on average stronger than both fluid drag forces and particle-particle collision forces. Particle exchange between agglomerates was necessary for mixing to occur during fluidization of wet granular materials but required strong capillary liquid bridge forces to be overcome. When pulsation of the inlet gas flow was applied, voidage waves comprising regions of high and low particle concentration formed within the fluidized bed. This allowed particles to cluster and disperse repeatedly, thus facilitating exchange of particles between agglomerates and promoting mixing of particles throughout the fluidized bed. This points towards the possibility of utilizing pulsed fluidization as an effective means of improving mixing efficiencies in fluidized bed systems containing wet granular materials.

  1. The wet compression technology for gas turbine power plants: Thermodynamic model

    International Nuclear Information System (INIS)

    Bracco, Stefano; Pierfederici, Alessandro; Trucco, Angela

    2007-01-01

    This paper examines from a thermodynamic point of view the effects of wet compression on gas turbine power plants, particularly analysing the influence of ambient conditions on the plant performance. The results of the mathematical model, implemented in 'Matlab' software, have been compared with the simulation results presented in literature and in particular the values of the 'evaporative rate', proposed in Araimo et al. [L. Araimo, A. Torelli, Thermodynamic analysis of the wet compression process in heavy duty gas turbine compressors, in: Proceedings of the 59th ATI Annual Congress, Genova, 2004, pp. 1249-1263; L. Araimo, A. Torelli, Wet compression technology applied to heavy duty gas turbines - GT power augmentation and efficiency upgrade, in: Proceedings of the 59th ATI Annual Congress, Genova, 2004, pp. 1265-1277] by 'Gas Turbines Department' of Ansaldo Energia S.p.A., have been taken into account to validate the model. The simulator permits to investigate the effects of the fogging and wet compression techniques and estimate the power and efficiency gain of heavy duty gas turbines operating in hot and arid conditions

  2. Reactive wetting of amorphous silica by molten Al–Mg alloys and their interfacial structures

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Laixin [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Shen, Ping, E-mail: shenping@jlu.edu.cn [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Zhang, Dan [Editorial Office, Journal of Bionic Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Jiang, Qichuan [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China)

    2016-07-30

    Highlights: • The wettability improves with increasing Mg concentration and temperature. • Reaction product zone consists of layered structures relating with Mg concentration. • Formation of MgAl{sub 2}O{sub 4} and MgO at the interface does not promote the wettability. • Formation of Mg{sub 2}Si plays a dominant role in promoting the wettability. • Anomalous recession of the triple line was mainly due to diminishing Mg in the alloy. - Abstract: The reactive wetting of amorphous silica substrates by molten Al–Mg alloys over a wide composition range was studied using a dispensed sessile drop method in a flowing Ar atmosphere. The effects of the nominal Mg concentration and temperature on the wetting and interfacial microstructures were discussed. The initial contact angle for pure Al on the SiO{sub 2} surface was 115° while that for pure Mg was 35° at 1073 K. For the Al–Mg alloy drop, it decreased with increasing nominal Mg concentration. The reaction zone was characterized by layered structures, whose formation was primarily controlled by the variation in the alloy concentration due to the evaporation of Mg and the interfacial reaction from the viewpoint of thermodynamics as well as by the penetration or diffusion of Mg, Al and Si from the viewpoint of kinetics. In addition, the effects of the reaction and the evaporation of Mg on the movement of the triple line were examined. The spreading of the Al–Mg alloy on the SiO{sub 2} surface was mainly attributed to the formation of Mg{sub 2}Si at the interface and the recession of the triple line to the diminishing Mg concentration in the alloy.

  3. RODDRP - A FORTRAN program for use in control rod calibration by the rod drop method

    International Nuclear Information System (INIS)

    Wilson, W.E.

    1972-01-01

    The different methods to measure reactivity which are applicable to control rod calibration are discussed. They include: 1) the positive period method, 2) the rod drop method, 3) the source-jerk method, 4) the rod oscillation method, and 5) the pulsed neutron method. The instrument setup used at WSU for rod drop measurements is presented. To speed up the analysis of power fall-off trace, a FORTRAN IV program called RODDRP was written to simultaneously solve the in-hour equation and relative neutron flux. The procedure for calculating the worth of the rod that produced the power trace is given. The reactivity for each time relative flux point is obtained. Conclusions about the status of the equipment are made

  4. Models optimization for the pressure drop calculation in two-phase flow cooled bundle

    International Nuclear Information System (INIS)

    Ladeira, L.C.D.; Rezende, H.C.

    1994-01-01

    The analysis of two-phase tests, performed in a mock-up of nuclear fuel element, to verify the applicability of existing calculation models to determine the pressure drop is presented. The tests were performed using Reynolds Number in the range from 4 x 10 4 to 1.6 x 10 5 , with heat flux up to 105 W/cm 2 , and three different levels of pressure: 2.0, 6.0 and 10.0 bar. The tests results were used to optimize the bubble detaching point in two correlations (Bowing and Lelouche-Zolotar) in order to obtain the subcooled void fraction. Comparison between measured and calculated results has shown that the pressure drop,in 96% of the tests, was reproduced within +- 16% when using the Bowing correlation, and +- 9% with the Lellouche-Zolotar one. (author)

  5. Leveraging microbial biosynthetic pathways for the generation of 'drop-in' biofuels.

    Science.gov (United States)

    Zargar, Amin; Bailey, Constance B; Haushalter, Robert W; Eiben, Christopher B; Katz, Leonard; Keasling, Jay D

    2017-06-01

    Advances in retooling microorganisms have enabled bioproduction of 'drop-in' biofuels, fuels that are compatible with existing spark-ignition, compression-ignition, and gas-turbine engines. As the majority of petroleum consumption in the United States consists of gasoline (47%), diesel fuel and heating oil (21%), and jet fuel (8%), 'drop-in' biofuels that replace these petrochemical sources are particularly attractive. In this review, we discuss the application of aldehyde decarbonylases to produce gasoline substitutes from fatty acid products, a recently crystallized reductase that could hydrogenate jet fuel precursors from terpene synthases, and the exquisite control of polyketide synthases to produce biofuels with desired physical properties (e.g., lower freezing points). With our increased understanding of biosynthetic logic of metabolic pathways, we discuss the unique advantages of fatty acid, terpene, and polyketide synthases for the production of bio-based gasoline, diesel and jet fuel. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Leveraging microbial biosynthetic pathways for the generation of 'drop-in' biofuels

    DEFF Research Database (Denmark)

    Zargar, Amin; Bailey, Constance B.; Haushalter, Robert W.

    2017-01-01

    and heating oil (21%), and jet fuel (8%), 'drop-in' biofuels that replace these petrochemical sources are particularly attractive. In this review, we discuss the application of aldehyde decarbonylases to produce gasoline substitutes from fatty acid products, a recently crystallized reductase that could......Advances in retooling microorganisms have enabled bioproduction of 'drop-in' biofuels, fuels that are compatible with existing spark-ignition, compression-ignition, and gas-turbine engines. As the majority of petroleum consumption in the United States consists of gasoline (47%), diesel fuel...... hydrogenate jet fuel precursors from terpene synthases, and the exquisite control of polyketide synthases to produce biofuels with desired physical properties (e.g., lower freezing points). With our increased understanding of biosynthetic logic of metabolic pathways, we discuss the unique advantages of fatty...

  7. Conductivity of PEDOT:PSS on Spin-Coated and Drop Cast Nanofibrillar Cellulose Thin Films.

    Science.gov (United States)

    Valtakari, Dimitar; Liu, Jun; Kumar, Vinay; Xu, Chunlin; Toivakka, Martti; Saarinen, Jarkko J

    2015-12-01

    Aqueous dispersion of conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) ( PSS) was deposited on spin-coated and drop cast nanofibrillar cellulose (NFC)-glycerol (G) matrix on a glass substrate. A thin glycerol film was utilized on plasma-treated glass substrate to provide adequate adhesion for the NFC-glycerol (NFC-G) film. The effects of annealing temperature, the coating method of NFC-G, and the coating time intervals on the electrical performance of the PSS were characterized. PSS on drop cast NFC-G resulted in 3 orders of magnitude increase in the electrical conductivity compared to reference PSS film on a reference glass substrate, whereas the optical transmission was only slightly decreased. The results point out the importance of the interaction between the PSS and the NFC-G for the electrical and barrier properties for thin film electronics applications.

  8. Drop Size Distribution - Based Separation of Stratiform and Convective Rain

    Science.gov (United States)

    Thurai, Merhala; Gatlin, Patrick; Williams, Christopher

    2014-01-01

    For applications in hydrology and meteorology, it is often desirable to separate regions of stratiform and convective rain from meteorological radar observations, both from ground-based polarimetric radars and from space-based dual frequency radars. In a previous study by Bringi et al. (2009), dual frequency profiler and dual polarization radar (C-POL) observations in Darwin, Australia, had shown that stratiform and convective rain could be separated in the log10(Nw) versus Do domain, where Do is the mean volume diameter and Nw is the scaling parameter which is proportional to the ratio of water content to the mass weighted mean diameter. Note, Nw and Do are two of the main drop size distribution (DSD) parameters. In a later study, Thurai et al (2010) confirmed that both the dual-frequency profiler based stratiform-convective rain separation and the C-POL radar based separation were consistent with each other. In this paper, we test this separation method using DSD measurements from a ground based 2D video disdrometer (2DVD), along with simultaneous observations from a collocated, vertically-pointing, X-band profiling radar (XPR). The measurements were made in Huntsville, Alabama. One-minute DSDs from 2DVD are used as input to an appropriate gamma fitting procedure to determine Nw and Do. The fitted parameters - after averaging over 3-minutes - are plotted against each other and compared with a predefined separation line. An index is used to determine how far the points lie from the separation line (as described in Thurai et al. 2010). Negative index values indicate stratiform rain and positive index indicate convective rain, and, moreover, points which lie somewhat close to the separation line are considered 'mixed' or 'transition' type precipitation. The XPR observations are used to evaluate/test the 2DVD data-based classification. A 'bright-band' detection algorithm was used to classify each vertical reflectivity profile as either stratiform or convective

  9. Thermal infrared mapping of the Leidenfrost drop evaporation

    Science.gov (United States)

    Wciślik, Sylwia

    2016-09-01

    The paper presents an author complementary study on the Leidenfrost drop evaporation. The research was conducted under ambient conditions and in the film boiling regime. Large water drops were placed on the copper substrate of the constant temperature Tw ranging from 297.6 to 404oC. The initial single drop diameter and its mass was D0 ≈ 1cm and m0 ≈ 1g respectively. One of the obtained results, for each Tw are the drop thermal images versus time. They were used to calculate an average temperature over the drop upper surface (Td). For an exemplary heating surface temperature of Tw = 297.6oC the average drop temperature is approximately 11oC lower than the saturation one and equals Td = 88,95oC. This value is estimated for the first 200s of evaporation and with time step size Δt = 0,5s. The drop upper surface temperature is highly variable and indicates strong convection inside it. This is due to the complex nature of heat and mass transfer. The maximum standard deviation from Td = 88,95oC is SD = 1.21.

  10. Inverse Leidenfrost effect: self-propelling drops on a bath

    Science.gov (United States)

    Gauthier, Anais; van der Meer, Devaraj; Lohse, Detlef; Physics of Fluids Team

    2017-11-01

    When deposited on very hot solid, volatile drops can levitate over a cushion of vapor, in the so-called Leidenfrost state. This phenomenon can also be observed on a hot bath and similarly to the solid case, drops are very mobile due to the absence of contact with the substrate that sustains them. We discuss here a situation of ``inverse Leidenfrost effect'' where room-temperature drops levitate on a liquid nitrogen pool - the vapor is generated here by the bath sustaining the relatively hot drop. We show that the drop's movement is not random: the liquid goes across the bath in straight lines, a pattern only disrupted by elastic bouncing on the edges. In addition, the drops are initially self-propelled; first at rest, they accelerate for a few seconds and reach velocities of the order of a few cm/s, before slowing down. We investigate experimentally the parameters that affect their successive acceleration and deceleration, such as the size and nature of the drops and we discuss the origin of this pattern.

  11. Application of Proteomics to the Study of Pollination Drops

    Directory of Open Access Journals (Sweden)

    Natalie Prior

    2013-04-01

    Full Text Available Premise of the study: Pollination drops are a formative component in gymnosperm pollen-ovule interactions. Proteomics offers a direct method for the discovery of proteins associated with this early stage of sexual reproduction. Methods: Pollination drops were sampled from eight gymnosperm species: Chamaecyparis lawsoniana (Port Orford cedar, Ephedra monosperma, Ginkgo biloba, Juniperus oxycedrus (prickly juniper, Larix ×marschlinsii, Pseudotsuga menziesii (Douglas-fir, Taxus ×media, and Welwitschia mirabilis. Drops were collected by micropipette using techniques focused on preventing sample contamination. Drop proteins were separated using both gel and gel-free methods. Tandem mass spectrometric methods were used including a triple quadrupole and an Orbitrap. Results: Proteins are present in all pollination drops. Consistency in the protein complement over time was shown in L. ×marschlinsii. Representative mass spectra from W. mirabilis chitinase peptide and E. monosperma serine carboxypeptidase peptide demonstrated high quality results. We provide a summary of gymnosperm pollination drop proteins that have been discovered to date via proteomics. Discussion: Using proteomic methods, a dozen classes of proteins have been identified to date. Proteomics presents a way forward in deepening our understanding of the biological function of pollination drops.

  12. Heat exchange between a bouncing drop and a superhydrophobic substrate.

    Science.gov (United States)

    Shiri, Samira; Bird, James C

    2017-07-03

    The ability to enhance or limit heat transfer between a surface and impacting drops is important in applications ranging from industrial spray cooling to the thermal regulation of animals in cold rain. When these surfaces are micro/nanotextured and hydrophobic, or superhydrophobic, an impacting drop can spread and recoil over trapped air pockets so quickly that it can completely bounce off the surface. It is expected that this short contact time limits heat transfer; however, the amount of heat exchanged and precise role of various parameters, such as the drop size, are unknown. Here, we demonstrate that the amount of heat exchanged between a millimeter-sized water drop and a superhydrophobic surface will be orders of magnitude less when the drop bounces than when it sticks. Through a combination of experiments and theory, we show that the heat transfer process on superhydrophobic surfaces is independent of the trapped gas. Instead, we find that, for a given spreading factor, the small fraction of heat transferred is controlled by two dimensionless groupings of physical parameters: one that relates the thermal properties of the drop and bulk substrate and the other that characterizes the relative thermal, inertial, and capillary dynamics of the drop.

  13. Electric generation and ratcheted transport of contact-charged drops

    Science.gov (United States)

    Cartier, Charles A.; Graybill, Jason R.; Bishop, Kyle J. M.

    2017-10-01

    We describe a simple microfluidic system that enables the steady generation and efficient transport of aqueous drops using only a constant voltage input. Drop generation is achieved through an electrohydrodynamic dripping mechanism by which conductive drops grow and detach from a grounded nozzle in response to an electric field. The now-charged drops are transported down a ratcheted channel by contact charge electrophoresis powered by the same voltage input used for drop generation. We investigate how the drop size, generation frequency, and transport velocity depend on system parameters such as the liquid viscosity, interfacial tension, applied voltage, and channel dimensions. The observed trends are well explained by a series of scaling analyses that provide insight into the dominant physical mechanisms underlying drop generation and ratcheted transport. We identify the conditions necessary for achieving reliable operation and discuss the various modes of failure that can arise when these conditions are violated. Our results demonstrate that simple electric inputs can power increasingly complex droplet operations with potential opportunities for inexpensive and portable microfluidic systems.

  14. Measurement of an Evaporating Drop on a Reflective Substrate

    Science.gov (United States)

    Chao, David F.; Zhang, Nengli

    2004-01-01

    A figure depicts an apparatus that simultaneously records magnified ordinary top-view video images and laser shadowgraph video images of a sessile drop on a flat, horizontal substrate that can be opaque or translucent and is at least partially specularly reflective. The diameter, contact angle, and rate of evaporation of the drop as functions of time can be calculated from the apparent diameters of the drop in sequences of the images acquired at known time intervals, and the shadowgrams that contain flow patterns indicative of thermocapillary convection (if any) within the drop. These time-dependent parameters and flow patterns are important for understanding the physical processes involved in the spreading and evaporation of drops. The apparatus includes a source of white light and a laser (both omitted from the figure), which are used to form the ordinary image and the shadowgram, respectively. Charge-coupled-device (CCD) camera 1 (with zoom) acquires the ordinary video images, while CCD camera 2 acquires the shadowgrams. With respect to the portion of laser light specularly reflected from the substrate, the drop acts as a plano-convex lens, focusing the laser beam to a shadowgram on the projection screen in front of CCD camera 2. The equations for calculating the diameter, contact angle, and rate of evaporation of the drop are readily derived on the basis of Snell s law of refraction and the geometry of the optics.

  15. Prophylactic Vancomycin Drops Reduce the Severity of Early Bacterial Keratitis in Keratoprosthesis

    Science.gov (United States)

    Konstantopoulos, Aris; Tan, Xiao Wei; Goh, Gwendoline Tze Wei; Saraswathi, Padmanabhan; Chen, Liyan; Nyein, Chan Lwin; Zhou, Lei; Beuerman, Roger; Tan, Donald Tiang Hwee; Mehta, Jod

    2015-01-01

    Background Artificial cornea transplantation, keratoprosthesis, improves vision for patients at high risk of failure with human cadaveric cornea. However, post-operative infection can cause visual loss and implant extrusion in 3.2–17% of eyes. Long-term vancomycin drops are recommended following keratoprosthesis to prevent bacterial keratitis. Evidence, though, in support of this practice is poor. We investigated whether prophylactic vancomycin drops prevented bacterial keratitis in an animal keratoprosthesis model. Methodology Twenty-three rabbits were assigned either to a prophylactic group (n = 13) that received vancomycin 1.4% drops 5 times/day from keratoprosthesis implantation to sacrifice, or a non-prophylactic group (n = 10) that received no drops. All rabbits had Staphylococcus aureus inoculation into the cornea at 7–12 days post-implantation and were sacrificed at predetermined time-points. Prophylactic and non-prophylactic groups were compared with slit-lamp photography (SLP), anterior segment optical coherence tomography (AS-OCT), and histology, immunohistochemistry and bacterial quantification of excised corneas. Corneal vancomycin pharmacokinetics were studied in 8 additional rabbits. Results On day 1 post-inoculation, the median SLP score and mean±SEM AS-OCT corneal thickness (CT) were greater in the non-prophylactic than the prophylactic group (11 vs. 1, p = 0.049 and 486.9±61.2 vs. 327.4±37.1 μm, p = 0.029 respectively). On days 2 and 4, SLP scores and CT were not significantly different. Immunohistochemistry showed a greater CD11b+ve/non-CD11b+ve cell ratio in the non-prophylactic group (1.45 vs. 0.71) on day 2. Bacterial counts were not significantly different between the two groups. Corneal vancomycin concentration (2.835±0.383 μg/ml) exceeded minimum inhibitory concentration (MIC) for Staphylococcus aureus only after 16 days of vancomycin drops. Two of 3 rabbits still developed infection despite bacterial inoculation after 16 days of

  16. Prophylactic Vancomycin Drops Reduce the Severity of Early Bacterial Keratitis in Keratoprosthesis.

    Directory of Open Access Journals (Sweden)

    Aris Konstantopoulos

    Full Text Available Artificial cornea transplantation, keratoprosthesis, improves vision for patients at high risk of failure with human cadaveric cornea. However, post-operative infection can cause visual loss and implant extrusion in 3.2-17% of eyes. Long-term vancomycin drops are recommended following keratoprosthesis to prevent bacterial keratitis. Evidence, though, in support of this practice is poor. We investigated whether prophylactic vancomycin drops prevented bacterial keratitis in an animal keratoprosthesis model.Twenty-three rabbits were assigned either to a prophylactic group (n = 13 that received vancomycin 1.4% drops 5 times/day from keratoprosthesis implantation to sacrifice, or a non-prophylactic group (n = 10 that received no drops. All rabbits had Staphylococcus aureus inoculation into the cornea at 7-12 days post-implantation and were sacrificed at predetermined time-points. Prophylactic and non-prophylactic groups were compared with slit-lamp photography (SLP, anterior segment optical coherence tomography (AS-OCT, and histology, immunohistochemistry and bacterial quantification of excised corneas. Corneal vancomycin pharmacokinetics were studied in 8 additional rabbits.On day 1 post-inoculation, the median SLP score and mean±SEM AS-OCT corneal thickness (CT were greater in the non-prophylactic than the prophylactic group (11 vs. 1, p = 0.049 and 486.9±61.2 vs. 327.4±37.1 μm, p = 0.029 respectively. On days 2 and 4, SLP scores and CT were not significantly different. Immunohistochemistry showed a greater CD11b+ve/non-CD11b+ve cell ratio in the non-prophylactic group (1.45 vs. 0.71 on day 2. Bacterial counts were not significantly different between the two groups. Corneal vancomycin concentration (2.835±0.383 μg/ml exceeded minimum inhibitory concentration (MIC for Staphylococcus aureus only after 16 days of vancomycin drops. Two of 3 rabbits still developed infection despite bacterial inoculation after 16 days of prophylactic drops

  17. Wetting Transition and Line Tension of Oil on Water

    Science.gov (United States)

    Matsubara, H.; Aratono, M.

    Wetting has attracted wide attention in the field of applied chemistry because of its crucial importance in industrial operations such as coating, painting, and lubrication. Here, we summarize our fundamental understandings of surfactant-assisted wetting transitions which we have found and studied for the last ten years. The difference between the surfactant-assisted wetting transitions and existing ones is discussed. Moreover, the relation between wetting transitions and the stability of the three-phase contact line is examined in terms of the line tension of oil lenses.

  18. On the gasification of wet biomass in supercritical water : over de vergassing van natte biomassa in superkritiek water

    NARCIS (Netherlands)

    Withag, J.A.M.

    2013-01-01

    Supercritical water gasification (SCWG) is a challenging thermo-chemical conversion route for wet biomass and waste streams into hydrogen and/or methane. At temperatures and pressures above the critical point the physical properties of water differ strongly from liquid water or steam. Because of the

  19. A new method for measuring the contact angles from digital images of liquid drops.

    Science.gov (United States)

    Mirzaei, M

    2017-11-01

    The drop hitting a solid surface may be symmetric or asymmetric, which depends on the surface texture and external force orientations. The accurate measurement of the contact angle is of fundamental importance for the purpose of scientific research, while having a substantial role in a wide range of practical applications. This paper presents a new image processing based method, as a computational scheme to measure the inclination angle of apparent edge curves in digital images. The main concept of the scheme is the emulation of a moving goniometer mask coupled with a Gaussian weighted function, which does not require edge fitting with analytic curves for the angle calculation. The algorithm produces as follow: allocating the exact position of the contact points by Harris corner detector function, selecting a series of points on the drop boundary near the contact points, setting goniometric mask on each given point and calculating the angles, applying the Gaussian weighted average function on the calculated angles and measure the objective contact angle. The scheme is tested on several images from recent studies in the available literature. The comparison between analytical and calculated angles shows less than 1° difference. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Theoretical Exploration of Barrel-Shaped Drops on Cactus Spines.

    Science.gov (United States)

    Luo, Cheng

    2015-11-03

    To survive an arid environment, desert cacti are capable of harvesting water from fog by transporting condensed water drops using their spines. Cactus spines have a conical shape. In this work, on the basis of the difference of liquid pressure, a new theoretical model has been developed for a barrel-shaped liquid drop on a conical wire. This model is further simplified to interpret the effects of contact angles, conical angle, surface microgrooves, and gravity on the drop movement along a cactus spine.

  1. Ultrasonic defect sizing using decibel drop methods. III

    International Nuclear Information System (INIS)

    Mills, C.; Goszczynski, J.; Mitchell, A.B.

    1988-03-01

    An earlier study on the use of ultrasonic decibel drop sizing methods for determining the length and vertical extent of flaws in welded steel sections was based on the scanning of machined flaws and fabrication flaws. The present study utilized the techniques developed to perform a similar study of the type of flaws expected to develop during service (e.g. fatigue cracks). The general findings are that: a) the use of decibel drops of less than 14 dB generally undersize the length of fatigue cracks; and b) the use of decibel drop methods to determine vertical extent is questionable

  2. Numerical simulation of the drop spreading on a horizontal plane

    Science.gov (United States)

    Zyuzina, N. A.; Ostapenko, V. V.

    2017-10-01

    A shallow water model of film flow is used to describe the process of a drop spreading on a horizontal plane, taking into account the liquid viscosity, heat-mass transfer and surface tension forces. To simulate this flow numerically in polar coordinates an unconditionally stable implicit difference scheme has been developed, which (in the case of evaporation) can calculate the drop spreading over a dry surface without special allocation of the drop boundary. A region of dimensionless parameters is singled out under which the evaporating droplet, as a result of surface tension forces, transforms into a circular ring before complete evaporation.

  3. Ready-made allogeneic ABO-specific serum eye drops

    DEFF Research Database (Denmark)

    Harritshøj, Lene Holm; Nielsen, Connie; Ullum, Henrik

    2014-01-01

    PURPOSE: To overcome problems and delays of the preparation of autologous serum eye drops, a production line of ABO-specific allogeneic serum eye drops from male blood donors was set up in a blood bank. Feasibility, clinical routine, safety and efficacy were evaluated in a cohort of patients...... serum treatment. CONCLUSION: Ready-made ABO-identical allogeneic serum eye drops were straightforwardly produced, quality-assured and registered as a safe standard blood product for the treatment of certain cases of severe dry eye disease. Therapeutic efficacy was comparable to previous reports...

  4. [Therapeutic bloodletting at Jing-well points combine hypothermia attenuated acute cerebral edema after traumatic brain injury in rats].

    Science.gov (United States)

    Miao, Xiao-mei; Cheng, Shi-xiang; Yang, Zhen; Zhang, Sai; Han, Wan-jun; Tu, Yue; Sun, Hong-tao

    2015-05-01

    To investigate the influence of therapeutic bloodletting at Jing-well points and hypothermia on acute cerebral edema after traumatic brain injury (TBI) in rats. Seventy-five SD rats were randomly divided into sham-operation group (Sham), TBI group (TBI), bloodletting group (BL), mild-induced hypothermia group (MIH), and bloodletting plus MIH group (BL + MIH) (n = 15). The model of TBI was established by electric controlled cortical impactor (eCCI). The rats of BL group were bloodletting at Jing-well points immediately after injury, twice daily. While the MIH group was settled on a hypothermia blanket promptly after TBI for 6 hours, so that the temperature dropped to 32 degrees. Each of measurement was performed after 48 hours. Magnetic resonance imaging (MRI) was used to evaluate the dynamic impairment of cerebral edema after TBI (n = 3). In addition, mNSS score, measurements of wet and dry brain weight, and Evans Blue assay were performed to investigate the neurologic deficit, cerebral water content (n = 8), and blood-brain barrier permeability (BBB), (n = 4), respectively. MRI analysis showed that the cerebral edema, hematoma and midline shifting of rats in TBI group was more serious than other treatment group. Meanwhile compared with TBI group, the mNSS scores of every treatment group were meaningfully lower (all P cerebral edema and BBB dysfunction and exert neuroprotective effects after TBI. The results suggest that the combination of BL and MIH is more effective than other treatment being used alone.

  5. Postfact phenomena of the wet-steam flow electrization in turbines

    Science.gov (United States)

    Tarelin, A. A.

    2017-11-01

    Physical processes occurring in a turbine with natural electrization of a humidity-steam flow and their effect on efficiency and reliability of the turbine operation has been considered. Causes of the electrical potential occurrence on a rotor shaft are analyzed. The wet steam's electrization exposure on the electrical potential that is one of the major factors of bearings' electroerosion has been demonstrated on the full-scale installation. Hydrogen formation in wheelspace of the turbine as a result of electrochemical processes and electric field exposure of the space charge has been considered. Hydrogen concentration dependence on a volume charge density in the steam flow has been determined. It is stated that the processes occurring behind the final stage of wet-steam turbines are similar to the ones in elaerosol ectrostatic generators. It has been demonstrated that this phenomenon causes the flow's temporal inhibition and starts pulsations. These factors' impact on power loss of the turbine has been evaluated and recommendations for their elimination have been offered. It has been determined that motions of charged drops can cause self-maintained discharges inside of the flow and between the flow and grounded surfaces that are accompanied by electromagnetic radiation of the wide spectrum. The integrated studies have shown that physical phenomena occurring due to natural electrization negatively affect efficiency and reliability of the turbine operation. Practical recommendations allowing one to minimize the negative effects of the flow natural electrization process have been offered.

  6. Method and apparatus for producing drops using a drop-on-demand dispenser

    Science.gov (United States)

    Chen, Alvin U.; Basaran, Osman A.

    2003-01-01

    A method and apparatus for dispensing fluid from a drop-on-demand (DOD) fluid dispenser. The method involves withdrawing fluid in the dispenser for a first duration of time, followed by a second duration of time during which the fluid is propelled toward the orifice of the dispenser. Following the period during which the fluid is propelled, there is a second withdrawing of the fluid into the dispenser. The duration of the propelling period is shorter than the duration of either the first withdrawing or the second withdrawing. The propelling of the fluid results in the extension of a small tongue of fluid from the meniscus of the fluid. The second withdrawing of the fluid results in a retraction of the meniscus into the passageway such that only the small tongue of fluid separates and is ejected from the dispenser.

  7. Handling test of eye drop dispenser--comparison of unit-dose pipettes with conventional eye drop bottles.

    Science.gov (United States)

    Parkkari, Minna; Latvala, Terho; Ropo, Auli

    2010-06-01

    The aims of this study were to investigate how elderly people handle single-use eye drop dispensers (unit-dose pipettes) and to compare the performance with conventional eye drop bottles. In this open-label study, the handling of unit-dose pipettes and conventional eye drop bottles was compared in 41 elderly people who had little or no prior regular use of eye drop dispensers. The participants tested both types of dispenser once, and the following 7 variables were studied: ease/difficulty of opening the dispenser; influence of the size for handling of the dispenser; influence of the shape for handling of the dispenser; observation of the contents in the dispenser; the feeling of the dispenser in the hand; ease/difficulty of drop instillation on the eye from the dispenser; and overall performance of the eye drop dispenser. The dispensers contained isotonic saline, and a visual analog scale was used for assessment of each of the above variables. The mean age of the participants was 73 years. A statistically significant difference in favor of the unit-dose pipettes was found with respect to observation of the contents in the dispenser, ease of administration, and the overall performance. Women regarded the unit-dose pipettes generally better than the bottles, but such a difference was not seen in men. The study participants managed the unit-dose pipettes at least as well as the conventional eye drop bottles. If anything, the unit-dose pipettes appeared to be easier to use.

  8. Address Points - Allegheny County Address Points 201601

    Data.gov (United States)

    NSGIC Education | GIS Inventory — This dataset contains Address Points in Allegheny County. The Address Points were created by GDR for the Allegheny County CAD project, October 2008. Data is updated...

  9. Depletion of water molecules during ethanol wet-bonding with etch and rinse dental adhesives

    Energy Technology Data Exchange (ETDEWEB)

    Gregoire, Genevieve, E-mail: gregoire@cict.fr [Department of Biomaterials, Faculty of Odontology, University Toulouse III, 31062, Toulouse (France); Sharrock, Patrick [Medical and Spatial Imaging Laboratory, University Toulouse III, Ave. Pompidou, 81104, Castres (France); Delannee, Mathieu [Department of Biomaterials, Faculty of Odontology, University Toulouse III, 31062, Toulouse (France); Delisle, Marie-Bernadette [Faculty of Medicine, University Toulouse III, 31062, Toulouse (France)

    2013-01-01

    The treatment of demineralized dentin with ethanol has been proposed as a way to improve hydrophobic monomer penetration into otherwise water saturated collagen fibrils. The ethanol rinse is expected to preserve the fibrils from collapsing while optimizing resin constituent infiltration for better long term adhesion. The physico-chemical investigations of demineralized dentin confirmed objectively these working hypotheses. Namely, Differential Scanning Calorimetry (DSC) measurements of the melting point of water molecules pointed to the presence of free and bound water states. Unfreezable water was the main type of water remaining following a rinsing step with absolute ethanol. Two different liquid water phases were also observed by Magic Angle Spinning (MAS) solid state Nuclear magnetic Resonance (NMR) spectroscopy. Infrared spectra of ethanol treated specimens illustrated differences with the fully hydrated specimens concerning the polar carbonyl vibrations. Optical microscopy observations as well as scanning electron microscopy showed an improved dentin-adhesive interface with ethanol wet bonding. The results indicate that water can be confined to strongly bound structural molecules when excess water is removed with ethanol prior to adhesive application. This should preserve collagen from hydrolysis upon aging of the hybrid layer. - Highlights: Black-Right-Pointing-Pointer Non-freezable water exists in demineralized dentine. Black-Right-Pointing-Pointer Free water can be removed by ethanol rinse of the demineralized collagen. Black-Right-Pointing-Pointer Ethanol wet bonding leads to a homogeneous hybrid layer free of defects.

  10. GPD+ wet tropospheric correctionsfor eight altimetric missions

    Science.gov (United States)

    Fernandes, Joana; Benveniste, Jérôme; Lázaro, Clara

    2016-07-01

    Due to its large space-temporal variability, the delay induced by the water vapour and liquid water content of the atmosphere in the altimeter signal or wet tropospheric delay (WTD) is still one of the largest sources of uncertainty in satellite altimetry. In the scope of the Sea Level Climate Change Initiative (SL-cci) project, the University of Porto (UPorto) has been developing methods to improve the wet tropospheric correction (WTC), which corrects for the effect of the WPD in the altimetric measurements. Developed as a coastal algorithm to remove land effects in the microwave radiometers (MWR) on board altimeter missions, the GNSS-derived Path Delay (GPD) methodology evolved over time, currently correcting for invalid observations due to land, ice and rain contamination, band instrument malfunction in open ocean, coastal and polar regions. The most recent version of the algorithm, GPD Plus (GPD+) computes wet path delays based on: i) WTC from the on-board MWR measurements, whenever they exist and are valid; ii) new WTC values estimated through space-time objective analysis of all available data sources, whenever the previous are considered invalid. In the estimation of the new WTC values, the following data sets are used: valid measurements from the on-board MWR, water vapour products derived from a set of 17 scanning imaging radiometers (SI-MWR) on board various remote sensing satellites and tropospheric delays derived from Global Navigation Satellite Systems (GNSS) coastal and island stations. In the estimation process, WTC derived from an atmospheric model such as the European Centre for Medium-range Weather Forecasts (ECMWF) ReAnalysis (ERA) Interim or the operational (Op) model are used as first guess, which is the adopted value in the absence of measurements. The corrections are provided for the most recent products of all missions used to generate the SL Essential Climate Variable (ECV): TOPEX/Poseidon- T/P, Jason-1, Jason-2, ERS-1, ERS-2, CryoSat-2

  11. Bird nesting and droppings control on highway structures.

    Science.gov (United States)

    2010-10-01

    This report provides a comprehensive literature survey of permanent and temporary deterrents to nesting and roosting, a : discussion of risks to human health and safety from exposure to bird nests and droppings and recommended protective measures, : ...

  12. The effect of dropping impact on bruising pomegranate fruit

    Directory of Open Access Journals (Sweden)

    M Mohammad Shafie

    2016-04-01

    Full Text Available Introduction: The pomegranate journey from orchard to supermarket is very complex and pomegranates are subjected to the variety of static and dynamic loads that could result in this damage and bruise occurring. Bruise area and bruise volume are the most important parameters to evaluate fruit damage occurred in harvest and postharvest stages. The bruising is defined as damage to fruit flesh usually with no abrasion of the peel. The two different types of dynamic loading which can physically cause fruit bruising are impact and vibration. The impact and vibration loadings may occur during picking or sorting as the pomegranates are dropped into storage bins and during transportation. The focus of this work was on the impact loading as this appeared to be the most prevalent. In view of the limitations of conventional testing methods (ASTM D3332 Standard Test Methods for Mechanical Shock Fragility of Products, the method and procedure for determining dropping bruise boundary of fruit were also established by adapting free-fall dropping tests. Materials and Methods: After the ‘Malas-e-Saveh’ pomegranates had been selected, they were numbered, and the weight and dimension of each sample were measured and recorded. Firmness in cheek region of each fruit was also measured. Fruit firmness was determined by measuring the maximum force during perforating the sample to a depth of 10 mm at a velocity of 100 mm min-1 with an 8 mm diameter cylindrical penetrometer mounted onto a STM-5 Universal Testing Machine (SANTAM, Design CO. LTD., England. Free-fall dropping tests with a series of drop heights (6, 7, 10, 15, 30 and 60 cm were conducted on fresh ‘Malas-e-Saveh’ pomegranates. Three samples were used for each dropping height, and each sample was subjected to impact on two different positions. Before the test was started, it was necessary to control the sample's drop position. The cheek of sample was placed on the fruit holder. An aluminum plate mounted

  13. Modeling gas kinetic effects in drop collision and impact

    Science.gov (United States)

    Chubynsky, Mykyta V.; Belousov, Kirill I.; Lockerby, Duncan A.; Sprittles, James E.

    2017-11-01

    When liquid drops collide with each other (collision) or with a solid surface (impact), the thickness of the intervening gas film (which, in particular, gives rise to bouncing off wettable surfaces) is often comparable to the mean free path of the gas molecules and thus gas kinetic effects are significant. We study drop collision and impact computationally using an interface-tracking finite element approach. The gas film is treated in the lubrication approximation. Gas kinetic effects are taken into account by introducing factors (functions of the Knudsen number) modifying the gas flow rate and shear stress. Our results for drop collision are in excellent agreement with those of Li who modeled the gas using the full Navier-Stokes equations with an effective viscosity. For impact, where Li's approach cannot be used, we obtain good agreement with drop bouncing experiments. We acknowledge the support of the Leverhulme Trust and the EPSRC (EP/N016602/1).

  14. Analysis of driver merging behavior at lane drops on freeways.

    Science.gov (United States)

    2013-12-01

    Lane changing assistance systems advise drivers on safe gaps for making mandatory lane changes at lane drops. In this : study, such a system was developed using a Bayes classifier and a decision tree to model lane changes. Detailed vehicle : trajecto...

  15. Bubble formation during drop impact on a heated pool

    Science.gov (United States)

    Tian, Yuansi; Alhazmi, Muath; Kouraytem, Nadia; Thoroddsen, Sigurdur

    2017-11-01

    Ultra high-speed video imaging, at up to 200 kfps, is used to investigate a drop impinging onto a high temperature pool. The room-temperature perfluorohexane drop, which has a boiling temperature as low as 56 °C impacts on the soybean oil pool heated up to around 200 °C, which is overwhelmingly higher than the boiling temperature of the drop. The bottom of the drop is therefore covered by a layer of vapor which prevents contact between the two immiscible liquid surfaces, akin to the Leidenfrost effect However, as the pool temperature is reduced, one starts seeing contact and the dynamics transition into the vapor explosion regime. At the boundary of this regime we observe some entrapment of scattered or a toroidal ring of small bubbles. Experimental video data will be presented to show this novel phenomenon and explain how these bubbles are formed and evolve.

  16. Herpes,zoster with Wrist Drop and Aberrant Lesions

    Directory of Open Access Journals (Sweden)

    R K Dutta

    1987-01-01

    Full Text Available A patient having herpes zoster involving C6, 7, 8, Dl and 2 segments, developed ipsilateral wrist drop and aberrant lesions. Paralytic deformity preceded the skin eruption by one day.

  17. Non-isothermal spreading of liquid drops on horizontal plates

    International Nuclear Information System (INIS)

    Ehrhard, P.; Davis, S.H.

    1990-05-01

    A viscous-liquid drop spreads on a smooth horizontal surface, which is uniformly heated or cooled. Lubrication theory is used to study thin drops subject to capillary, thermocapillary and gravity forces, and a variety of contact-angle-versus-speed conditions. It is found for isothermal drops that gravity is very important at large times and determines the power law for unlimited spreading. Predictions compare well with the experimental data on isothermal spreading for both two-dimensional and axisymmetric configurations. It is found that heating (cooling) retards (augments) the spreading process. When the advancing contact angle is zero, heating will cause the drop to spread only finitely far. For positive advancing contact angles, sufficient cooling will cause unlimited spreading. Thus, the heat transfer serves as a sentitive control on the spreading. (orig.) [de

  18. Origin and dynamics of vortex rings in drop splashing.

    Science.gov (United States)

    Lee, Ji San; Park, Su Ji; Lee, Jun Ho; Weon, Byung Mook; Fezzaa, Kamel; Je, Jung Ho

    2015-09-04

    A vortex is a flow phenomenon that is very commonly observed in nature. More than a century, a vortex ring that forms during drop splashing has caught the attention of many scientists due to its importance in understanding fluid mixing and mass transport processes. However, the origin of the vortices and their dynamics remain unclear, mostly due to the lack of appropriate visualization methods. Here, with ultrafast X-ray phase-contrast imaging, we show that the formation of vortex rings originates from the energy transfer by capillary waves generated at the moment of the drop impact. Interestingly, we find a row of vortex rings along the drop wall, as demonstrated by a phase diagram established here, with different power-law dependencies of the angular velocities on the Reynolds number. These results provide important insight that allows understanding and modelling any type of vortex rings in nature, beyond just vortex rings during drop splashing.

  19. Modeling merging behavior at lane drops : [tech transfer summary].

    Science.gov (United States)

    2015-02-01

    A better understanding of the merging behavior of drivers will lead : to the development of better lane-drop traffic-control plans and : strategies, which will provide better guidance to drivers for safer : merging.

  20. Self-excited hydrothermal waves in evaporating sessile drops

    Science.gov (United States)

    Sefiane, K.; Moffat, J. R.; Matar, O. K.; Craster, R. V.

    2008-08-01

    Pattern formation driven by the spontaneous evaporation of sessile drops of methanol, ethanol, and FC-72 using infrared thermography is observed and, in certain cases, interpreted in terms of hydrothermal waves. Both methanol and ethanol drops exhibit thermal wave trains, whose wave number depends strongly on the liquid volatililty and substrate thermal conductivity. The FC-72 drops develop cellular structures whose size is proportional to the local thickness. Prior to this work, hydrothermal waves have been observed in the absence of evaporation in shallow liquid layers subjected to an imposed temperature gradient. In contrast, here both the temperature gradients and the drop thickness vary spatially and temporally and are a natural consequence of the evaporation process.