Science.gov

Sample records for solid surfaces measured

  1. Comparing contact angle measurements and surface tension assessments of solid surfaces.

    PubMed

    Cwikel, Dory; Zhao, Qi; Liu, Chen; Su, Xueju; Marmur, Abraham

    2010-10-05

    Four types of contact angles (receding, most stable, advancing, and "static") were measured by two independent laboratories for a large number of solid surfaces, spanning a large range of surface tensions. It is shown that the most stable contact angle, which is theoretically required for calculating the Young contact angle, is a practical, useful tool for wettability characterization of solid surfaces. In addition, it is shown that the experimentally measured most stable contact angle may not always be approximated by an average angle calculated from the advancing and receding contact angles. The "static" CA is shown in many cases to be very different from the most stable one. The measured contact angles were used for calculating the surface tensions of the solid samples by five methods. Meaningful differences exist among the surface tensions calculated using four previously known methods (Owens-Wendt, Wu, acid-base, and equation of state). A recently developed, Gibbsian-based correlation between interfacial tensions and individual surface tensions was used to calculate the surface tensions of the solid surfaces from the most stable contact angle of water. This calculation yielded in most cases higher values than calculated with the other four methods. On the basis of some low surface energy samples, the higher values appear to be justified.

  2. Internal flow measurements of drop impacting a solid surface

    NASA Astrophysics Data System (ADS)

    Kumar, S. Santosh; Karn, Ashish; Arndt, Roger E. A.; Hong, Jiarong

    2017-03-01

    Understanding the fundamental physical process involved in drop impacts is important for a variety of engineering and scientific applications. Despite exhaustive research efforts on the dynamics of drop morphology upon impact, very few studies investigate the fluid dynamics induced within a drop upon impact. This study employs planar particle image velocimetry (PIV) with fluorescent particles to quantify the internal flow field of a drop impact on a solid surface. The image distortion caused by the curved liquid-air interface at the drop boundary is corrected using a ray-tracing algorithm. PIV analysis using the corrected images has yielded interesting insights into the flow initiated within a drop upon impact. Depending on the pre-impact conditions, characterized by impact number, different vortex modes are observed in the recoil phase of the drop impact. Further, the strength of these vortices and the kinetic energy of the internal flow field have been quantified. Our studies show a consistent negative power law correlation between vortex strength, internal kinetic energy and the impact number.

  3. Measurement of Surface Tension of Solid Cu by Improved Multiphase Equilibrium

    NASA Astrophysics Data System (ADS)

    Nakamoto, Masashi; Liukkonen, Matti; Friman, Michael; Heikinheimo, Erkki; Hämäläinen, Marko; Holappa, Lauri

    2008-08-01

    The surface tension of solid Cu was measured with the multiphase equilibrium (MPE) method in a Pb-Cu system at 700 °C, 800 °C, and 900 °C. A special focus was on the measurement of angles involved in MPE. First, the effect of reading error in each angle measurement on the final result of surface tension of solid was simulated. It was found that the two groove measurements under atmosphere conditions are the primary sources of error in the surface tension of solid in the present system. Atomic force microscopy (AFM) was applied to these angle measurements as a new method with high accuracy. The obtained surface-tension values of solid Cu in the present work were 1587, 1610, and 1521 mN/m at 700 °C, 800 °C, and 900 °C, respectively, representing reasonable temperature dependence.

  4. Quantitative Surface Emissivity and Temperature Measurements of a Burning Solid Fuel Accompanied by Soot Formation

    NASA Technical Reports Server (NTRS)

    Piltch, Nancy D.; Pettegrew, Richard D.; Ferkul, Paul; Sacksteder, K. (Technical Monitor)

    2001-01-01

    Surface radiometry is an established technique for noncontact temperature measurement of solids. We adapt this technique to the study of solid surface combustion where the solid fuel undergoes physical and chemical changes as pyrolysis proceeds, and additionally may produce soot. The physical and chemical changes alter the fuel surface emissivity, and soot contributes to the infrared signature in the same spectral band as the signal of interest. We have developed a measurement that isolates the fuel's surface emissions in the presence of soot, and determine the surface emissivity as a function of temperature. A commercially available infrared camera images the two-dimensional surface of ashless filter paper burning in concurrent flow. The camera is sensitive in the 2 to 5 gm band, but spectrally filtered to reduce the interference from hot gas phase combustion products. Results show a strong functional dependence of emissivity on temperature, attributed to the combined effects of thermal and oxidative processes. Using the measured emissivity, radiance measurements from several burning samples were corrected for the presence of soot and for changes in emissivity, to yield quantitative surface temperature measurements. Ultimately the results will be used to develop a full-field, non-contact temperature measurement that will be used in spacebased combustion investigations.

  5. Solid Surface Combustion Experiment

    NASA Image and Video Library

    1994-09-12

    STS064-10-011 (12 Sept. 1994) --- The Solid Surface Combustion Experiment (SSCE), designed to supply information on flame spread over solid fuel surfaces in the reduced-gravity environment of space, is pictured during flight day four operations. The middeck experiment measured the rate of spreading, the solid-phase temperature, and the gas-phase temperature of flames spreading over rectangular fuel beds. STS-64 marked the seventh trip into space for the Lewis Research Center experiment. Photo credit: NASA or National Aeronautics and Space Administration

  6. Methods for measuring work surface illuminance in adaptive solid state lighting networks

    NASA Astrophysics Data System (ADS)

    Lee, Byungkun; Aldrich, Matthew; Paradiso, Joseph A.

    2011-10-01

    The inherent control flexibility implied by solid-state lighting - united with the rich details offered by sensor networks - prompts us to rethink lighting control. In this research, we propose several techniques for measuring work surface illuminance and ambient light using a sensor network. The primary goal of this research is to measure work surface illuminance without distraction to the user. We discuss these techniques, including the lessons learned from our prior research. We present a new method for measuring the illuminance contribution of an arbitrary luminaire at the work surface by decomposing the modulated light into its fundamental and harmonic components.

  7. Dynamic measurement of the force required to move a liquid drop on a solid surface.

    PubMed

    Pilat, D W; Papadopoulos, P; Schäffel, D; Vollmer, D; Berger, R; Butt, H-J

    2012-12-11

    We measured the forces required to slide sessile drops over surfaces. The forces were measured by means of a vertical deflectable capillary stuck in the drop. The drop adhesion force instrument (DAFI) allowed the investigation of the dynamic lateral adhesion force of water drops of 0.1 to 2 μL volume at defined velocities. On flat PDMS surfaces, the dynamic lateral adhesion force increases linearly with the diameter of the contact area of the solid-liquid interface and linearly with the sliding velocity. The movement of the drop relative to the surfaces enabled us to resolve the pinning of the three-phase contact line to individual defects. We further investigated a 3D superhydrophobic pillar array. The depinning of the receding part of the rim of the drop occurred almost simultaneously from four to five pillars, giving rise to peaks in the lateral adhesion force.

  8. Spatially and temporally resolved measurements of the temperature inside droplets impinging on a hot solid surface

    NASA Astrophysics Data System (ADS)

    Chaze, William; Caballina, Ophélie; Castanet, Guillaume; Lemoine, Fabrice

    2017-08-01

    Heat transfers at the impact of a droplet on a hot solid surface are investigated experimentally. Millimeter-sized water droplets impinge a flat sapphire window heated at 600 °C. The time evolution of the droplet temperature is characterized using the two-color laser-induced fluorescence technique. For that, a Q-switched Nd:YAG laser is used for the excitation of the fluorescence to obtain instantaneous images of the droplet temperature. Water is seeded with two fluorescent dyes, one sensitive to temperature (fluorescein disodium) and the other not (sulforhodamine 640). Owing to a wavelength shift between the dyes' emissions, the fluorescence signal of the dyes can be detected separately by two cameras. The liquid temperature is determined with a good accuracy by doing the ratio of the images of the dyes' fluorescence. A critical feature of the method is that the image ratio is not disturbed by the deformation of the impacting droplet, which affects the signals of the dyes almost identically. Experiments are performed in the conditions of film boiling. A thin vapor film at the interface between the droplet and the solid surface prevents the deposition of liquid on the hot solid surface. Measurements highlight some differences in the rate of heat transfers and in the temperature distribution within the droplet between the bouncing and splashing regimes of impact.

  9. Some remarks on the solid surface tension determination from contact angle measurements

    NASA Astrophysics Data System (ADS)

    Zdziennicka, Anna; Szymczyk, Katarzyna; Krawczyk, Joanna; Jańczuk, Bronisław

    2017-05-01

    The measurements of water, formamide and diiodomethane contact angle (θ) on polytetrafluoroethylene (PTFE), polyethylene (PE), polymethyl methacrylate (PMMA), nylon 6, quartz and silica were performed. Based on the θ values of these liquids obtained on PTFE, the Lifshitz-van der Waals and acid-base and/or dispersion and polar components of their surface tension (ST) were determined. In turn, the θ values for water, formamide and diiodomethane on PMMA were applied to calculate the electron-acceptor and electron-donor parameters of the Lewis acid-base component of the formamide ST. For this calculation the same values of the electron-acceptor and electron-donor parameters for water ST were used. Taking into account the values of components and parameters of water, formamide and diiodomethane ST obtained by us, van Oss et al. and from the water(formamide)-n-alkane and water-diiodomethane interface tension, the components and parameters of studied solids ST were calculated. To this end different approaches to the interface tension were considered. The obtained values were compared with those in the literature. It was concluded that for determination of solid ST components and parameters, those of water, formamide and diiodomethane ST obtained from the θ measurements on the model solids should be used.

  10. Measurement of elastic force on a scanned probe near a solid surface

    NASA Astrophysics Data System (ADS)

    Drummond Roby, M. A.; Wetsel, G. C., Jr.

    1996-12-01

    The physical nature of the forces acting between a laterally vibrating probe in air near a solid surface has been investigated using a calibrated method for the experimental determination of dynamic force. The frequency response of the probe vibrating near its fundamental bending resonance was measured as a function of distance as the probe approached the surface. The experimental results were compared with a continuum-mechanical model of bending waves in a rod; the nature of the forces was inferred by determining the effect of various boundary conditions on the standing-wave motion of the probe. The results conclusively show that while in the initial stage of approach the force is dominated by fluid-dynamic effects, in the final stage of approach an elastic force appears. The appearance of the elastic deformation is characterized by a shift in the resonant frequency of the vibrating probe.

  11. The effective surface energy of heterogeneous solids measured by inverse gas chromatography at infinite dilution.

    PubMed

    Sun, Chenhang; Berg, John C

    2003-04-15

    Inverse gas chromatography (IGC) at infinite dilution has been widely used to access the nonspecific surface free energy of solid materials. Since most practical surfaces are heterogeneous, the effective surface energy given by IGC at infinite dilution is somehow averaged over the whole sample surface, but the rule of averaging has thus far not been established. To address this problem, infinite dilution IGC analysis was carried out on mixtures of known heterogeneity. These materials are obtained by mixing two types of solid particles with significantly different surface energies as characterized individually with IGC, and results are obtained for binary combinations in varying proportions. It is found that when all surface components have the same accessibility by probe molecules, the effective surface energy of such a heterogeneous surface is related to the surface energy distribution by a square root linear relationship, square root sigma(eff)(LW)= summation operator (i)phi(i) square root sigma(i)(LW), where sigma(i)(LW) refers to the nonspecific (Lifshitz-van der Waals) surface energy of patches i, and phi(i) to their area fraction.

  12. Direct measurement of energy barriers on rough and heterogeneous solid surfaces

    SciTech Connect

    Lloyd, T.B.; LaGow, J.; Connelly, G.M.

    1996-12-31

    This paper will deal with the phenomenon of energy barriers to the spread of liquids on solids. These barriers often manifest themselves as a {open_quotes}pinning{close_quotes} of a sessile drop as liquid is added to it. That is, the volume of the drop increases, but the diameter does not. Thus the advancing contact angle ({theta}{sub a}) increases to a maximum. At the point where the hydrostatic pressure in the drop overcomes the {open_quotes}pinning{close_quotes} force the diameter suddenly increases and the drop relaxes to a metastable configuration which has a lower {theta}{sub a}. Energy barriers should be considered in many applications such as the spreading of liquid adhesives where thorough wetting is the goal. The interfacial forces involved are both long-range Lifshitz-van der Waals (LW) forces and short-range acid-base (AB) forces. The authors will describe how they measure the energy barriers on real surfaces directly and resolve them into their LW and AB components.

  13. Use of molecular beams for kinetic measurements of chemical reactions on solid surfaces

    NASA Astrophysics Data System (ADS)

    Zaera, Francisco

    2017-05-01

    In this review we survey the contributions that molecular beam experiments have provided to our understanding of the dynamics and kinetics of chemical interactions of gas molecules with solid surfaces. First, we describe the experimental details of the different instrumental setups and approaches available for the study of these systems under the ultrahigh vacuum conditions and with the model planar surfaces often used in modern surface-science experiments. Next, a discussion is provided of the most important fundamental aspects of the dynamics of chemical adsorption that have been elucidated with the help of molecular beam experiments, which include the development of potential energy surfaces, the determination of the different channels for energy exchange between the incoming molecules and the surface, the identification of adsorption precursor states, the understanding of dissociative chemisorption, the determination of the contributions of corrugation, steps, and other structural details of the surface to the adsorption process, the effect to molecular steering, the identification of avenues for assisting adsorption, and the molecular details associated with the kinetics of the uptake of adsorbates as a function of coverage. We follow with a summary of the work directed at the determination of kinetic parameters and mechanistic details of surface reactions associated with catalysis, mostly those promoted by late transition metals. This discussion we initiate with an overview of what has been learned about simple bimolecular reactions such as the oxidation of CO and H2 with O2 and the reaction of CO with NO, and continue with the review of the studies of more complex systems such as the oxidation of alcohols, the conversion of organic acids, the hydrogenation and isomerization of olefins, and the oxidative activation of alkanes under conditions of short contact times. Sections 6 and 7 of this review deal with the advances made in the use of molecular beams with

  14. Solid surface luminescence analysis

    NASA Astrophysics Data System (ADS)

    Hurtubise, R. J.

    1984-04-01

    Several advances were made in understanding the interactions responsible for room-temperature phosphorescence. Infrared data showed strong room-temperature phosphorescence from compounds adsorbed on some surfaces which contained adsorbed water. A partial model for phosphor/solid-surface interactions was developed for nitrogen heterocycles and polycyclic aromatic hydrocarbons adsorbed on poly(acrylic acid)-salt mixtures. Hydroxyl aromatics behave as hydrogen donors, hydrogen accepting species, or as both hydrogen donors and hydrogen acceptors when adsorbed on solid-surfaces. Several new analytical methods and techniques were developed. Poly(acrylic acid)-phosphor solutions that were spotted on filter paper resulted in lower limits of detection and better reproducibility. Both qualitative and quantitative analysis of mixtures were achieved at the nanogram level by using room-temperature fluorescence and phosphorescence. In addition, the combined use of zeroth and second derivative room-temperature fluorescence and phosphorescence spectra was developed into a useful analytical approach.

  15. Measuring forces and spatiotemporal evolution of thin water films between an air bubble and solid surfaces of different hydrophobicity.

    PubMed

    Shi, Chen; Cui, Xin; Xie, Lei; Liu, Qingxia; Chan, Derek Y C; Israelachvili, Jacob N; Zeng, Hongbo

    2015-01-27

    A combination of atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) was used to measure simultaneously the interaction force and the spatiotemporal evolution of the thin water film between a bubble in water and mica surfaces with varying degrees of hydrophobicity. Stable films, supported by the repulsive van der Waals-Casimir-Lifshitz force were always observed between air bubble and hydrophilic mica surfaces (water contact angle, θ(w) < 5°) whereas bubble attachment occurred on hydrophobized mica surfaces. A theoretical model, based on the Reynolds lubrication theory and the augmented Young-Laplace equation including the effects of disjoining pressure, provided excellent agreement with experiment results, indicating the essential physics involved in the interaction between air bubble and solid surfaces can be elucidated. A hydrophobic interaction free energy per unit area of the form: WH(h) = -γ(1 - cos θ(w))exp(-h/D(H)) can be used to quantify the attraction between bubble and hydrophobized solid substrate at separation, h, with γ being the surface tension of water. For surfaces with water contact angle in the range 45° < θ(w) < 90°, the decay length DH varied between 0.8 and 1.0 nm. This study quantified the hydrophobic interaction in asymmetric system between air bubble and hydrophobic surfaces, and provided a feasible method for synchronous measurements of the interaction forces with sub-nN resolution and the drainage dynamics of thin films down to nm thickness.

  16. Temperature measurements on solid surfaces in rack-storage fires using IR thermography

    NASA Astrophysics Data System (ADS)

    de Vries, J.; Ren, N.; Chaos, M.

    2015-05-01

    The development of fire modeling tools capable of predicting large-scale fire phenomena is of great value to the fire science community. To this end, FM Global has developed an open-source CFD fire simulation code, FireFOAM. The accuracy of this code relies fundamentally on high-quality experimental validation data. However, at larger scales, detailed measurements of local quantities (e.g., surface temperatures) needed for model validation are difficult to obtain. Often, the information obtained from large-scale fire tests is limited to the global heat release rates (HRR) or point temperature or heat flux measurements from embedded thermocouples or heat flux gauges, respectively. The present study addresses this limitation by introducing IR thermographic measurements in a three- and a five-tier-high rack storage scenario. IR temperatures are compared against modeled results. The tested and modeled cases represent realistic industrial warehouse fire scenarios. The rack-stored commodity consisted of corrugated paperboard boxes wrapped around a steel cubic liners, placed on top of a hardwood pallet. The global heat release rate was measured using a 20- MW fire products collector located inside FM Global's Fire Technology Laboratory. An in-house calibrated microbolometer IR camera was used to obtain two-dimensional temperature measurements on the fuel surfaces and on the surfaces inside the flue spaces. Maximum temperatures up to 1200 K were observed on the external surfaces of the test array. Inside the flue spaces between pallet loads, temperatures up to 1400 K were measured. The modeled fire spread results match well fire spread shown in the IR thermographic images. The peak modeled surface temperatures obtained inside some of the horizontal flue spaces were ~1400K, which agreed well with the peak temperatures seen by the IR camera. The effect of the flames present between the surfaces of interest and the IR camera only contribute to about 50 K increase in measured

  17. Full-field spreading velocity measurement inside droplets impinging on a dry solid surface

    NASA Astrophysics Data System (ADS)

    Erkan, Nejdet; Okamoto, Koji

    2014-11-01

    Liquid droplet impacts onto solid surfaces have attracted enormous amount of attention from wide range of research fields including experimental and numerical investigations. Unlike experimental efforts, numerical and analytical studies generated various sets of data. In this study, we investigated the spreading velocities inside the water droplets impinging onto a dry glass substrate using time-resolved PIV. The method, together with the high spatiotemporal resolution and the additional treatments improving the robustness, allowed us to resolve the radial velocity profiles efficiently in the spreading phase. Several impact velocity cases ranging from 0.40 to 0.96 m/s were studied. They correspond to low and moderate level Weber numbers (4.9-27.6). We observed that instantaneous radial velocity distributions exhibit linear and nonlinear modes. The nonlinearity is caused by the vortical flows formed at outer regions of the spreading liquid lamella. We demonstrated that even at low impact velocities the linear parts of the profiles obey a quasi-one-dimensional theory proposed in the literature. The comparison of obtained results with a literature-based numerical study, performed for high range of Weber numbers, confirmed the simultaneous existence of linear and nonlinear parts in the radial velocity profiles. In spite of the scale differences in terms of Weber number, the agreements in the tendencies of the profiles imply the validity of the mechanism considered in the numerical study even at low and moderate level range of Weber numbers.

  18. Study of the adsorbed layer on a solid electrode surface by specular reflection measurement

    NASA Astrophysics Data System (ADS)

    Kusu, Fumiyo; Takamura, Kiyoko

    1985-07-01

    Specular reflection measurements were carried out to study the adsorbed layers of certain heterocyclic compounds such as adenine, barbital, 2'-deoxyadenosine, phenobarbital, pyridine and thymine. When pyridine was present in 0.1M NaClO 4, a marked decrease in the reflectivity of a gold electrode was observed. In the potential range near the point of zero charge on the reflectivity-potential curve, the decrease was due to the adsorption of pyridine. Assuming the reflectivity change to be proportional to the surface coverage, the potential and concentration dependence of pyridine adsorption was determined and analysed on the basis of a Langmuir-type adsorption isotherm. The refractive indices and extinction coefficients for the adsorbed layers of the compounds investigated were evaluated using the observed reflectivity change, according to relations proposed by McIntyre and Aspnes.

  19. A multifibre optic sensor to measure the liquid film thickness between a moving bubble and an inclined solid surface

    NASA Astrophysics Data System (ADS)

    Perron, A.; Kiss, L. I.; Verreault, R.

    2006-06-01

    In this paper, a multifibre optic sensor is developed to measure the thickness of the liquid film located between a moving bubble and an inclined surface. The sensor takes into account the presence of a second interface independently of its distance from the solid surface. In the first part of the paper, a mathematical model is developed to simulate the behaviour of several configurations of the fibre optic sensor in order to determine the best configuration of the sensor. In the second part, the calibration setup is presented and described in detail. In the last part of the paper, the method is validated. The results showed that the applicability range of the sensor is from 125 µm to 1400 µm. In the operating range, the accuracy of the sensor is around 5%.

  20. Extracting local surface charges and charge regulation behavior from atomic force microscopy measurements at heterogeneous solid-electrolyte interfaces

    NASA Astrophysics Data System (ADS)

    Zhao, Cunlu; Ebeling, Daniel; Siretanu, Igor; van den Ende, Dirk; Mugele, Frieder

    2015-10-01

    We present a method to determine the local surface charge of solid-liquid interfaces from Atomic Force Microscopy (AFM) measurements that takes into account shifts of the adsorption/desorption equilibria of protons and ions as the cantilever tip approaches the sample. We recorded AFM force distance curves in dynamic mode with sharp tips on heterogeneous silica surfaces partially covered by gibbsite nano-particles immersed in an aqueous electrolyte with variable concentrations of dissolved NaCl and KCl at pH 5.8. Forces are analyzed in the framework of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory in combination with a charge regulation boundary that describes adsorption and desorption reactions of protons and ions. A systematic method to extract the equilibrium constants of these reactions by simultaneous least-squared fitting to experimental data for various salt concentrations is developed and is shown to yield highly consistent results for silica-electrolyte interfaces. For gibbsite-electrolyte interfaces, the surface charge can be determined, yet, an unambiguous identification of the relevant surface speciation reactions is not possible, presumably due to a combination of intrinsic chemical complexity and heterogeneity of the nano-particle surfaces.

  1. Study of temperature-programmed desorption of tert-butylamine to measure the surface acidity of solid catalysts

    SciTech Connect

    Aguayo, A.T.; Arandes, J.M.; Olazar, M.; Bilbao, J. )

    1991-08-01

    In this paper, the technique of temperature-programmed desorption of tert-butylamine is described to measure the surface acidity of solid catalysts. The use of this base has advantages over the use of ammonia, pyridine, and n-butylamine. The desorption measurement is carried out by two methods, gas chromatography and thermogravimetry, and the advised conditions are described for both methods. Catalysts of SiO{sub 2}/Al{sub 2}O{sub 3}, bifunctionals of Ni-SiO{sub 2}/Al{sub 2}O{sub 3}, and a commercial cracking zeolite have been studied. A comparison of the desorption results with those of the other acidity measurement techniques (such as titration with n-butylamine in the liquid phase and kinetic measurement of isomerization of n-butenes as the test reaction) allows the acidity measured with tert-butylamine desorption to be classified as strong, corresponding to the active sites in most of the reactions among the hydrocarbon compounds catalyzed by acids.

  2. Surface modification of solids

    SciTech Connect

    Appleton, B.R.

    1984-05-01

    The use of ion beam and pulsed laser processing is reviewed for the near-surface modification of a wide range of materials. The techniques of ion implantation doping, ion beam and laser mixing, and pulsed-laser annealing are stressed with particular emphasis on the nonequilibrium aspects of these processing techniques and on new materials properties which can result. Examples are presented illustrating the utility of these techniques for fundamental materials research as well as practical surface modifications.

  3. Association between stall surface and some animal welfare measurements in freestall dairy herds using recycled manure solids for bedding.

    PubMed

    Husfeldt, A W; Endres, M I

    2012-10-01

    The objective of this cross-sectional study was to investigate the association between stall surface and some animal welfare measurements in upper Midwest US dairy operations using recycled manure solids as bedding material. The study included 34 dairy operations with herd sizes ranging from 130 to 3,700 lactating cows. Forty-five percent of the herds had mattresses and 55% had deep-bedded stalls. Farms were visited once between July and October 2009. At the time of visit, at least 50% of the cows in each lactating pen were scored for locomotion, hygiene, and hock lesions. On-farm herd records were collected for the entire year and used to investigate mortality, culling, milk production, and mastitis incidence. Stall surface was associated with lameness and hock lesion prevalence. Lameness prevalence (locomotion score ≥ 3 on a 1 to 5 scale) was lower in deep-bedded freestalls (14.4%) than freestalls with mattresses (19.8%). Severe lameness prevalence (locomotion score ≥ 4) was also lower for cows housed in deep-bedded freestalls (3.6%) than for cows housed in freestalls with mattresses (5.9%). In addition, the prevalence of hock lesions (hock lesion scores ≥ 2 on a 1 to 3 scale, with 1=no lesion, 2=hair loss or mild lesion, and 3=swelling or severe lesion) and severe hock lesions (hock lesion score=3) was lower in herds with deep-bedded freestalls (49.4%; 6.4%) than in herds with mattresses (67.3%; 13.2%). Herd turnover rates were not associated with stall surface; however, the percentage of removals due to voluntary (low milk production, disposition, and dairy) and involuntary (death, illness, injury, and reproductive) reasons was different between deep-bedded and mattress-based freestalls. Voluntary removals averaged 16% of all herd removals in deep-bedded herds, whereas in mattress herds, these removals were 8%. Other welfare measurements such as cow hygiene, mortality rate, mastitis incidence, and milk production were not associated with stall surface.

  4. Enzyme catalysis on solid surfaces.

    PubMed

    Laurent, Nicolas; Haddoub, Rose; Flitsch, Sabine L

    2008-06-01

    Enzyme-catalysed reactions in which substrates are bound (immobilised) to solid surfaces are becoming increasingly important in biotechnology. There is a general drive for miniaturisation and automation in chemistry and biology, and immobilisation of the reaction intermediates and substrates, for example on microarrays or nanoparticles, helps to address technical challenges in this area. In bionanotechnology, enzyme catalysis can provide highly selective and biocompatible tools for the modification of surfaces on the nano-scale. Here, we review the range of enzyme-catalysed reactions that have been successfully performed on the solid phase and discuss their application in biotechnology.

  5. Femtosecond laser controlled wettability of solid surfaces.

    PubMed

    Yong, Jiale; Chen, Feng; Yang, Qing; Hou, Xun

    2015-12-14

    Femtosecond laser microfabrication is emerging as a hot tool for controlling the wettability of solid surfaces. This paper introduces four typical aspects of femtosecond laser induced special wettability: superhydrophobicity, underwater superoleophobicity, anisotropic wettability, and smart wettability. The static properties are characterized by the contact angle measurement, while the dynamic features are investigated by the sliding behavior of a liquid droplet. Using different materials and machining methods results in different rough microstructures, patterns, and even chemistry on the solid substrates. So, various beautiful wettabilities can be realized because wettability is mainly dependent on the surface topography and chemical composition. The distinctions of the underlying formation mechanism of these wettabilities are also described in detail.

  6. Attractive forces between hydrophobic solid surfaces measured by AFM on the first approach in salt solutions and in the presence of dissolved gases.

    PubMed

    Azadi, Mehdi; Nguyen, Anh V; Yakubov, Gleb E

    2015-02-17

    Interfacial gas enrichment of dissolved gases (IGE) has been shown to cover hydrophobic solid surfaces in water. The atomic force microscopy (AFM) data has recently been supported by molecular dynamics simulation. It was demonstrated that IGE is responsible for the unexpected stability and large contact angle of gaseous nanobubbles at the hydrophobic solid-water interface. Here we provide further evidence of the significant effect of IGE on an attractive force between hydrophobic solid surfaces in water. The force in the presence of dissolved gas, i.e., in aerated and nonaerated NaCl solutions (up to 4 M), was measured by the AFM colloidal probe technique. The effect of nanobubble bridging on the attractive force was minimized or eliminated by measuring forces on the first approach of the AFM probe toward the flat hydrophobic surface and by using high salt concentrations to reduce gas solubility. Our results confirm the presence of three types of forces, two of which are long-range attractive forces of capillary bridging origin as caused by either surface nanobubbles or gap-induced cavitation. The third type is a short-range attractive force observed in the absence of interfacial nanobubbles that is attributed to the IGE in the form of a dense gas layer (DGL) at hydrophobic surfaces. Such a force was found to increase with increasing gas saturation and to decrease with decreasing gas solubility.

  7. Simultaneous measurement of dynamic force and spatial thin film thickness between deformable and solid surfaces by integrated thin liquid film force apparatus.

    PubMed

    Zhang, Xurui; Tchoukov, Plamen; Manica, Rogerio; Wang, Louxiang; Liu, Qingxia; Xu, Zhenghe

    2016-11-09

    Interactions involving deformable surfaces reveal a number of distinguishing physicochemical characteristics that do not exist in interactions between rigid solid surfaces. A unique fully custom-designed instrument, referred to as integrated thin liquid film force apparatus (ITLFFA), was developed to study the interactions between one deformable and one solid surface in liquid. Incorporating a bimorph force sensor with interferometry, this device allows for the simultaneous measurement of the time-dependent interaction force and the corresponding spatiotemporal film thickness of the intervening liquid film. The ITLFFA possesses the specific feature of conducting measurement under a wide range of hydrodynamic conditions, with a displacement velocity of deformable surfaces ranging from 2 μm s(-1) to 50 mm s(-1). Equipped with a high speed camera, the results of a bubble interacting with hydrophilic and partially hydrophobic surfaces in aqueous solutions indicated that ITLFFA can provide information on interaction forces and thin liquid film drainage dynamics not only in a stable film but also in films of the quick rupture process. The weak interaction force was extracted from a measured film profile. Because of its well-characterized experimental conditions, ITLFFA permits the accurate and quantitative comparison/validation between measured and calculated interaction forces and temporal film profiles.

  8. Solid surface mapping by inverse gas chromatography.

    PubMed

    Gutiérrez, M C; Osuna, S; Baráibar, I

    2005-09-16

    Inverse gas chromatography (IGC) at infinite dilution, is a technique for characterising solid surfaces. Current practice is the injection of n-alkane homologous series to obtain the free energy of adsorption of the CH2 group, from which the London component of the solid surface free energy, gamma(d)s, is calculated. A value around 40 mJ/m2 is obtained for poly(ethylene), and 30 mJ/m2 for a clean glass fibre, while the potential surface interactivity of a glass fibre is far greater than that of poly(ethylene). A specific component of the surface, in mJ/m2, should be calculated in order to obtain significant parameters. As applied up to date, when calculating the specific component of the surface energy, the fact that W(sp)a energy values are in a totally different scale than AN or DN values is a major drawback. Consequently, Ka and Kb values obtained are in arbitrary energy units, different from those of the London component measured by injecting the n-alkane series. This paper proposes a method to obtain Ka and Kb values of the surface in the same energetic scale than the London component. The method enables us to correct the traditional London component of a solid, obtaining a new value, where the amount of WaCH2 accounting for Debye interactions with polar sites, is excluded. As a result, an approach to surface mapping is performed in several different substrate materials. We show results obtained on different solid surfaces: poly(ethylene), clean glass fibre, glass beads, chemically modified glass beads and carbon fibre.

  9. Phase conjugate Twyman-Green interferometer for testing spherical surfaces and lenses and for measuring refractive indices of liquids or solid transparent materials

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Dokhanian, Mostafa; Venkateswarlu, Putcha; George, M. C.

    1990-01-01

    The present paper describes an application of a phase conjugate Twyman-Green interferometer using barium titanate as a self-pumping mirror for testing optical components like concave and convex spherical mirrors and lenses. The aberrations introduced by the beam splitter while testing concave or convex spherical mirrors of large aperture are automatically eliminated due to self-focussing property of the phase conjugate mirror. There is no necessity for a good spherical surface as a reference surface unlike in classical Twyman-Green interferometer or Williams interferometer. The phase conjugate Twyman Green interferometer with a divergent illumination can be used as a test plate for checking spherical surfaces. A nondestructive technique for measuring the refractive indices of a Fabry Perot etalon by using a phase conjugate interferometer is also suggested. The interferometer is found to be useful for measuring the refractive indices of liquids and solid transparent materials with an accuracy of the order of + or - 0.0004.

  10. Phase conjugate Twyman-Green interferometer for testing spherical surfaces and lenses and for measuring refractive indices of liquids or solid transparent materials

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Dokhanian, Mostafa; Venkateswarlu, Putcha; George, M. C.

    1990-01-01

    The present paper describes an application of a phase conjugate Twyman-Green interferometer using barium titanate as a self-pumping mirror for testing optical components like concave and convex spherical mirrors and lenses. The aberrations introduced by the beam splitter while testing concave or convex spherical mirrors of large aperture are automatically eliminated due to self-focussing property of the phase conjugate mirror. There is no necessity for a good spherical surface as a reference surface unlike in classical Twyman-Green interferometer or Williams interferometer. The phase conjugate Twyman Green interferometer with a divergent illumination can be used as a test plate for checking spherical surfaces. A nondestructive technique for measuring the refractive indices of a Fabry Perot etalon by using a phase conjugate interferometer is also suggested. The interferometer is found to be useful for measuring the refractive indices of liquids and solid transparent materials with an accuracy of the order of + or - 0.0004.

  11. Topological Surface States in Dense Solid Hydrogen.

    PubMed

    Naumov, Ivan I; Hemley, Russell J

    2016-11-11

    Metallization of dense hydrogen and associated possible high-temperature superconductivity represents one of the key problems of physics. Recent theoretical studies indicate that before becoming a good metal, compressed solid hydrogen passes through a semimetallic stage. We show that such semimetallic phases predicted to be the most stable at multimegabar (∼300  GPa) pressures are not conventional semimetals: they exhibit topological metallic surface states inside the bulk "direct" gap in the two-dimensional surface Brillouin zone; that is, metallic surfaces may appear even when the bulk of the material remains insulating. Examples include hydrogen in the Cmca-12 and Cmca-4 structures; Pbcn hydrogen also has metallic surface states but they are of a nontopological nature. The results provide predictions for future measurements, including probes of possible surface superconductivity in dense hydrogen.

  12. Topological Surface States in Dense Solid Hydrogen

    NASA Astrophysics Data System (ADS)

    Naumov, Ivan I.; Hemley, Russell J.

    2016-11-01

    Metallization of dense hydrogen and associated possible high-temperature superconductivity represents one of the key problems of physics. Recent theoretical studies indicate that before becoming a good metal, compressed solid hydrogen passes through a semimetallic stage. We show that such semimetallic phases predicted to be the most stable at multimegabar (˜300 GPa ) pressures are not conventional semimetals: they exhibit topological metallic surface states inside the bulk "direct" gap in the two-dimensional surface Brillouin zone; that is, metallic surfaces may appear even when the bulk of the material remains insulating. Examples include hydrogen in the Cmca-12 and Cmca-4 structures; Pbcn hydrogen also has metallic surface states but they are of a nontopological nature. The results provide predictions for future measurements, including probes of possible surface superconductivity in dense hydrogen.

  13. Method and apparatus for measuring surface movement of a solid object that is subjected to external vibrations

    DOEpatents

    Schultz, T.J.; Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.

    1995-04-25

    A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figs.

  14. Method and apparatus for measuring surface movement of a solid object that is subjected to external vibrations

    DOEpatents

    Schultz, Thomas J.; Kotidis, Petros A.; Woodroffe, Jaime A.; Rostler, Peter S.

    1995-01-01

    A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading.

  15. Universal deformation of soft substrates near a contact line and the direct measurement of solid surface stresses.

    PubMed

    Style, Robert W; Boltyanskiy, Rostislav; Che, Yonglu; Wettlaufer, J S; Wilen, Larry A; Dufresne, Eric R

    2013-02-08

    Droplets deform soft substrates near their contact lines. Using confocal microscopy, we measure the deformation of silicone gel substrates due to glycerol and fluorinated-oil droplets for a range of droplet radii and substrate thicknesses. For all droplets, the substrate deformation takes a universal shape close to the contact line that depends on liquid composition, but is independent of droplet size and substrate thickness. This shape is determined by a balance of interfacial tensions at the contact line and provides a novel method for direct determination of the surface stresses of soft substrates. Moreover, we measure the change in contact angle with droplet radius and show that Young's law fails for small droplets when their radii approach an elastocapillary length scale. For larger droplets the macroscopic contact angle is constant, consistent with Young's law.

  16. Universal Deformation of Soft Substrates Near a Contact Line and the Direct Measurement of Solid Surface Stresses

    NASA Astrophysics Data System (ADS)

    Style, Robert W.; Boltyanskiy, Rostislav; Che, Yonglu; Wettlaufer, J. S.; Wilen, Larry A.; Dufresne, Eric R.

    2013-02-01

    Droplets deform soft substrates near their contact lines. Using confocal microscopy, we measure the deformation of silicone gel substrates due to glycerol and fluorinated-oil droplets for a range of droplet radii and substrate thicknesses. For all droplets, the substrate deformation takes a universal shape close to the contact line that depends on liquid composition, but is independent of droplet size and substrate thickness. This shape is determined by a balance of interfacial tensions at the contact line and provides a novel method for direct determination of the surface stresses of soft substrates. Moreover, we measure the change in contact angle with droplet radius and show that Young’s law fails for small droplets when their radii approach an elastocapillary length scale. For larger droplets the macroscopic contact angle is constant, consistent with Young’s law.

  17. Examination of instability growth in solid liner surfaces using comparisons of two dimensional MHD calculations and measured data

    SciTech Connect

    Atchison, W.L.; Faehl, R.J.; Morgan, D.V.; Reinovsky, R.E.

    1997-10-01

    Experiments being conducted at the Los Alamos National Laboratory Pegasus facility are examining stability issues for driving an aluminum liner with a pulsed magnetic field. The Pegasus facility provides a current of 5 to 8 Megamperes to compress a cylindrical liner. Liners of various size and thickness are used, depending on the specific experimental objectives. In several of these experiments, the outer surface clearly develops perturbations in the mass distribution. These perturbations are strongest when the aluminum is suspected to have melted and in some cases partially vaporized. A series of specific experiments was designed to examine the growth rate of these instabilities. These experiments involved machining a sine wave onto the outer surface of the liner to seed a given wavelength. Two-dimensional MHD calculations, using the measured current profile, were performed to model the behavior of the liner under magnetic field compression. These predictions were made with a 2D Eulerian code complete with a Steinburg-Guinan strength model. The results of these calculations will be discussed in this paper. The density contours at specific times will be compared with the processed radiography.

  18. Designing a miniaturised heated stage for in situ optical measurements of solid oxide fuel cell electrode surfaces, and probing the oxidation of solid oxide fuel cell anodes using in situ Raman spectroscopy.

    PubMed

    Brightman, E; Maher, R; Offer, G J; Duboviks, V; Heck, C; Cohen, L F; Brandon, N P

    2012-05-01

    A novel miniaturised heated stage for in operando optical measurements on solid oxide fuel cell electrode surfaces is described. The design combines the advantages of previously reported designs, namely, (i) fully controllable dual atmosphere operation enabling fuel cell pellets to be tested in operando with either electrode in any atmosphere being the focus of study, and (ii) combined electrochemical measurements with optical spectroscopy measurements with the potential for highly detailed study of electrochemical processes; with the following advances, (iii) integrated fitting for mounting on a mapping stage enabling 2-D spatial characterisation of the surface, (iv) a compact profile that is externally cooled, enabling operation on an existing microscope without the need for specialized lenses, (v) the ability to cool very rapidly, from 600 °C to 300 °C in less than 5 min without damaging the experimental apparatus, and (vi) the ability to accommodate a range of pellet sizes and thicknesses.

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

    PubMed

    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.

  20. Eigenstress model for electrochemistry of solid surfaces

    PubMed Central

    Ma, Hongxin; Xiong, Xilin; Gao, Panpan; Li, Xi; Yan, Yu; Volinsky, Alex A.; Su, Yanjing

    2016-01-01

    Thermodynamic analysis and molecular dynamics simulations were conducted to systematically study the size-dependent electrochemical response of solids. By combining the generalized Young-Laplace equation with the popular Butler-Volmer formulation, the direct influence of surface stress on solid film electrochemical reactions was isolated. A series of thermodynamic formulas were developed to describe the size-dependent electrochemical properties of the solid surface. These formulas include intrinsic surface elastic parameters, such as surface eigenstress and surface elastic modulus. Metallic films of Au, Pt, Ni, Cu and Fe were studied as examples. The anodic current density of the metal film increased, while the equilibrium potential decreased with increasing solid film thickness. PMID:27256492

  1. Anisotropic surface chemistry of crystalline pharmaceutical solids.

    PubMed

    Heng, Jerry Y Y; Bismarck, Alexander; Williams, Daryl R

    2006-10-06

    The purpose of this study was to establish the link between the wetting behavior of crystalline pharmaceutical solids and the localized surface chemistry. A range of conventional wetting techniques were evaluated and compared with a novel experimental approach: sessile drop contact angle measurements on the individual facets of macroscopic (>1 cm) single crystals. Conventional measurement techniques for determining surface energetics such as capillary rise and sessile drops on powder compacts were found not to provide reliable results. When the macroscopic crystal approach was used, major differences for advancing contact angles, theta(a), of water were observed-as low as 16 degrees on facet (001) and as high as 68 degrees on facet (010) of form I paracetamol. theta(a) trends were in excellent agreement with X-ray photoelectron spectroscopy surface composition and known crystallographic structures, suggesting a direct relationship to the local surface chemistry. Inverse gas chromatography (IGC) was further used to probe the surface properties of milled and unmilled samples, as a function of particle size. IGC experiments confirmed that milling exposes the weakest attachment energy facet, with increasing dominance as particle size is reduced. The weakest attachment energy facet was also found to exhibit the highest theta(a) for water and to be the most hydrophobic facet. This anisotropic wetting behavior was established for a range of crystalline systems: paracetamol polymorphs, aspirin, and ibuprofen racemates. theta(a) was found to be very sensitive to the local surface chemistry. It is proposed that the hydrophilicity/hydrophobicity of facets reflects the presence of functional groups at surfaces to form hydrogen bonds with external molecules.

  2. Nondestructive image detection of surface and sub-surface defects of solid materials by OBD

    NASA Astrophysics Data System (ADS)

    Shi, Baixuan; Gong, Jian

    1996-09-01

    The measurement principle for detecting surface and sub-surface defects in solid materials by the optical beam deflection method (OBD) is described. The detectable depth of sub-surface defects is predicted through calculating the dependence of the surface temperature distribution of a solid sample, typically metal Al, on the thickness of the solid material and modulation frequencies of a pump laser. The defects in surface and sub-surface of some samples such as carbon film coated on glass, C/C composite material and metallic Al, etc., experimentally detected and directly displayed by grey image or 3D image.

  3. Solid-surface luminescence analysis

    SciTech Connect

    Hurtubise, R.J.

    1991-01-01

    We have characterized several interactions that are very important in solid-matrix luminescence. With silica gel chromatoplates and filter paper, simple equations were derived for calculating the individual contributions to the percent decrease in luminescence due to either moisture or to a quenching gas. For sodium acetate as a solid matrix and p-aminobenzoate as a model compound, it was concluded that p-aminobenzoate was incorporated into the crystal structure of sodium acetate, and the triplet energy was lost be skeletal vibrations in sodium acetate. Also, with the same system is was shown that p-aminobenzoate did not undergo rotational relaxation, and thus rotational processes did not contribute to the deactivation of the triplet state. Several results were obtained from model compounds adsorbed on filter paper under different temperature and humidity conditions and with a variety of heavy atoms present. Fundamental photophysical equations were used in calculating several basic parameters that revealed information on rate processes and how the absorbed energy was distributed in an adsorbed lumiphor. The most important advancement with filter paper was the development of equations that relate phosphorescence parameters of adsorbed phosphors to the Young's modulus of filter paper. These equations are based on a fundamental theory that relates the hydrogen-bonding network of paper to the modulus of paper.

  4. A measurement method for distinguishing the real contact area of rough surfaces of transparent solids using improved Otsu technique

    NASA Astrophysics Data System (ADS)

    Song, Bao-Jiang; Yan, Shao-Ze; Xiang, Wu-Wei-Kai

    2015-01-01

    An experimental method of measuring the real contact area of transparent blocks based on the principle of total internal reflection is presented, intending to support the investigation of friction characteristics, heat conduction, and energy dissipation at the contact interface. A laser sheet illuminates the contact interface, and the transmitted laser sheet is projected onto a screen. Then the contact information is acquired from the screen by a camera. An improved Otsu method is proposed to process the data of experimental images. It can compute the threshold of the overall image and filter out all the pixels one by one. Through analyzing the experimental results, we describe the relationship between the real contact area and the positive pressure during a continuous loading process, at different loading rates, with the polymethyl methacrylate (PMMA) material. A hysteresis phenomenon in the relationship between the real contact area and the positive pressure is found and explained. Project supported by the National Natural Science Foundation of China (Grant No. 11272171), the Beijing Natural Science Foundation, China (Grant No. 3132030), and the Education Ministry Doctoral Fund of China (Grant No. 20120002110070).

  5. Surface cleanliness measurement procedure

    DOEpatents

    Schroder, Mark Stewart; Woodmansee, Donald Ernest; Beadie, Douglas Frank

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  6. Simple and accurate measurement of carbamazepine in surface water by use of porous membrane-protected micro-solid-phase extraction coupled with isotope dilution mass spectrometry.

    PubMed

    Teo, Hui Ling; Wong, Lingkai; Liu, Qinde; Teo, Tang Lin; Lee, Tong Kooi; Lee, Hian Kee

    2016-03-17

    To achieve fast and accurate analysis of carbamazepine in surface water, we developed a novel porous membrane-protected micro-solid-phase extraction (μ-SPE) method, followed by liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) analysis. The μ-SPE device (∼0.8 × 1 cm) was fabricated by heat-sealing edges of a polypropylene membrane sheet to devise a bag enclosing the sorbent. The analytes (both carbamazepine and isotope-labelled carbamazepine) were first extracted by μ-SPE device in the sample (10 mL) via agitation, then desorbed in an organic solvent (1 mL) via ultrasonication. Several parameters such as organic solvent for pre-conditioning of μ-SPE device, amount of sorbent, adsorption time, and desorption solvent and time were investigated to optimize the μ-SPE efficiency. The optimized method has limits of detection and quantitation estimated to be 0.5 ng L(-1) and 1.6 ng L(-1), respectively. Surface water samples spiked with different amounts of carbamazepine (close to 20, 500, and 1600 ng L(-1), respectively) were analysed for the validation of method precision and accuracy. Good precision was obtained as demonstrated by relative standard deviations of 0.7% for the samples with concentrations of 500 and 1600 ng kg(-1), and 5.8% for the sample with concentration of 20 ng kg(-1). Good accuracy was also demonstrated by the relative recoveries in the range of 96.7%-103.5% for all samples with uncertainties of 1.1%-5.4%. Owing to the same chemical properties of carbamazepine and isotope-labelled carbamazepine, the isotope ratio in the μ-SPE procedure was accurately controlled. The use of μ-SPE coupled with IDMS analysis significantly facilitated the fast and accurate measurement of carbamazepine in surface water.

  7. Characterization of the Surface of Moving Solid $(4) $ 4 He

    NASA Astrophysics Data System (ADS)

    Livne, Ethan; Eyal, Anna; Scaly, Ori; Polturak, Emil

    2015-08-01

    Crystal grains of solid He can move in relation to each other even when embedded inside the solid [1, 2]. In this work, we characterize a macroscopic motion of solid hcp He composed of such grains. Motion is induced by applying an external torque to the solid contained inside an annular channel mounted on a torsional oscillator. In order to characterize the surface of the moving solid, we developed an in situ flow detection method using a sensitive "microphone" embedded in the wall of the channel. Motion is detected by counting the vibrations induced by rows of He atoms moving past the microphone. Such vibrations were detected only at T = 0.5 K, our lowest temperature. At this temperature, the measured dissipation associated with the solid He is zero within our accuracy. Our results indicate that the orientation of the surface of the moving solid is the (0001) basal plane of the hcp structure. At T = 0.5 K, we found that for speeds m/s, the solid flows without detectable friction.

  8. Drop Impact on a Solid Surface

    NASA Astrophysics Data System (ADS)

    Josserand, C.; Thoroddsen, S. T.

    2016-01-01

    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.

  9. Surface Science at the Solid Liquid Interface

    DTIC Science & Technology

    1993-10-06

    quantitative changes of A4’ in the different adsorption of OH(ad) to molecular H20 and O(ad)] a further small states on Ni (221 ) and Ni (665) are not a... ADSORPTION * MODELING OF THE WATER-SOLID INTERFACE * THEORY OF CHARGED SOLID SURFACES A POSTER SESSION IS PLANNED FOR MONDAY EVENING WITH POSTERS ON DISPLAY...Pat Thiel [Iowa State] and by Dr. Fred Wagner [General Motors], who discussed adsorption of water and co- adsorption (leading to liquid interface

  10. Precision surface measurement.

    PubMed

    Jiang, X

    2012-08-28

    Surface size, geometry and texture are some of the most influential subjects in the fields of precision and ultra-precision engineering, defining the functional interface through which emerging products operate. Next-generation products demand super-smooth surfaces, freeform geometries or even deterministically introduced microstructures to provide functional performance. Technological progress using these surfaces types is possible only if the associated manufacturing processes are rigorously controlled and the surfaces are measurable. Metrology for advanced surfaces is not established. The current state of the art is challenged in respect to (i) surface characteristics, extremity of size, ultra precision, quality, geometric complexity, or combinations of these aspects, and (ii) measurement technology for the manufacturing environment, in particular, online, non-contact, high speed, ease of use, small footprint and robustness. This study addresses the challenges in this subject area and discusses some fundaments and principles derived from interdisciplinary research. The combination of these aspects is enabling the creation of manufacturing-environment-based measurement technology. This is expected to facilitate advanced surface manufacture over a wide range of sectors, including large science programmes and high-technology engineering.

  11. Surface and bulk photochemistry of solids

    NASA Astrophysics Data System (ADS)

    Franchy, René

    1998-06-01

    This article reviews aspects of photochemistry on solid surfaces. In order to understand the photo-induced processes a brief introduction is given to the interaction between light and the solid-gas interfaces. The adsorption of molecules on solid surfaces, and the negative ion resonances (NIR) by inelastic electron scattering are briefly discussed. There are three photoinduced processes which occur on surfaces: photoinduced desorption (PID), photoinduced dissociation and photoinduced reactions. The mechanisms of the photoinduced processes are discussed and related to the experimentally determined cross sections. Photoinduced processes are driven: (i) by direct electronic excitation of the adsorbate, (ii) by substrate excitation, (iii) by both adsorbate and substrate excitation, or (iv) by charge transfer dissociation. The usual experimental methods and the light sources are presented. Most of the experimental examples deal with photo-stimulated experiments in the IR-visible and UV region. In some examples photon stimulated desorption of ions of physisorbed molecules is studied by using VUV synchrotron radiation in the energy range between 13-40 eV. In addition to desorption and dissociation, photo-excited molecules can react with each other and form new chemical bonds leading to new species on the surface. Photoinduced polymerizations of formaldehyde on Ag(111) occur after irradiation with light at 0034-4885/61/6/003/img1.

  12. Total external reflection of X-rays from solid surfaces

    NASA Astrophysics Data System (ADS)

    Stozharov, V. M.

    2017-01-01

    The reflection of X-rays from solid surfaces is comprehensively studied using the measurements of patterns of total external reflection and X-ray diffraction with the aid of a parabolic mirror. Principles for theoretical processing of X-ray patterns are developed. An inverse dependence of the refractive index of X-ray radiation on the interplanar distances in crystallites is obtained.

  13. Solid Surface Combustion Experiment Yields Significant Observations

    NASA Technical Reports Server (NTRS)

    Sacksteder, Kurt R.; Koudelka, John M.; Vergilii, Franklin

    1999-01-01

    The spread of a flame over solid fuel is not only a fundamental textbook combustion phenomenon, but also the central element of destructive fires that cause tragic loss of life and property each year. Throughout history, practical measures to prevent and fight fires have been developed, but these have often been based on lessons learned in a costly fire. Since the 1960 s, scientists and engineers have employed powerful tools of scientific research to understand the details of flame spread and how a material can be rendered nonflammable. High-speed computers have enabled complex flame simulations, whereasand lasers have provided measurements of the chemical composition, temperature, and air velocities inside flames. The microgravity environment has emerged as the third great tool for these studies. Spreading flames are complex combinations of chemical reactions and several physical processes including the transport of oxygen and fuel vapor to the flame and the transfer of heat from the flame to fresh fuel and to the surroundings. Depending on its speed, air motion in the vicinity of the flame can affect the flame in substantially different ways. For example, consider the difference between blowing on a campfire and blowing out a match. On Earth, gravity induces air motion because of buoyancy (the familiar rising hot gases); this process cannot be controlled experimentally. For theoreticians, buoyant air motion complicates the problem modeling of flame spread beyond the capacity of modern computers to simulate. The microgravity environment provides experimental control of air motion near spreading flames, with results that can be compared with detailed theory. The Solid Surface Combustion Experiment (SSCE) was designed to obtain benchmark flame spreading data in quiescent test atmospheres--the limiting case of flames spreading. Professor Robert Altenkirch, Vice President for Research at Mississippi State University, proposed the experiment concept, and the NASA Lewis

  14. Applications of Surface Science to Solid Lubricants

    DTIC Science & Technology

    1993-03-15

    reactivity of MoS2 as determined by these surface science techniques, and to relate this fundamental understanding to the performance of MoS2 as a solid...molybdenum disulfide ( MoS2 ) that has been per- formed at The Aerospace Corporation and other institutions. The Aerospace personnel that originally...Jeffrey Childs. This report represents the compilation of many years of work on MoS2 , and we gratefully acknowledge the technical guidance provided

  15. Surface activity of solid particles with extremely rough surfaces.

    PubMed

    Nonomura, Yoshimune; Komura, Shigeyuki

    2008-01-15

    The solid particles are adsorbed at liquid-liquid interfaces and form self-assembled structures when the particles have suitable wettability to both liquids. Here, we show theoretically how the extreme roughness on the particle surface affects their adsorption properties. In our previous work, we discussed the adsorption behavior of the solid particles with microstructured surfaces using the so-called Wenzel model [Y. Nonomura et al., J. Phys. Chem. B 110 (2006) 13124]. In the present study, the wettability and the adsorbed position of the particles with extremely rough surfaces are studied based on the Cassie-Baxter model. We predict that the adsorbed position and the interfacial energy depend on the interfacial tensions between the solid and liquid phases, the radius of the particle, and the fraction of the particle surface area that is in contact with the external liquid phase. Interestingly, the initial state of the system governs whether the particle is adsorbed at the interface or not. The shape of the particle is also an important factor which governs the adsorbed position. The disk-shaped particle and the spherical particle which is partially covered with the extremely rough surface, i.e. Janus particle, are adsorbed at the liquid-liquid interface in an oriented state. We should consider not only the interfacial tensions, but also the surface structure and the particle shape to control the adsorption behavior of the particle.

  16. Solid Surface Combustion at Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Altenkirch, R. A.

    1985-01-01

    The spread of a flame in the gas over the surface of a solid combustible involves in an essential way the transfer of heat from the flame to the solid fuel immediately ahead of it. This heat transfer is affected by the character of the gas phase flame, and so the phenomenon of flame spreading under reduced gravity, in which the flow is generated by gasification of the solid combustible, is apt to be different from what occurs under the Earth's normal gravitational acceleration where the flow is largely buoyancy driven. An experiment is being designed for the Middeck of the Space Shuttle to aid us in understanding the process of flame spreading in the absence of a buoyancy driven flow. A chamber approximately 0.35 cu.m. in volume is to contain either a thin sample of a cellulosic material or a thick sample of polymethyl-methacrylate and an oxidizing environment of O2 and N2. Samples will be ignited at one end, and the ensuing flame spread will be filmed. The spread rate can be determined from the films, and surface and gas-phase temperatures just above the surface will also be recorded. These data will help to clarify the mechanism of forward heat transfer in the low gravity flames.

  17. Rupture of lipid vesicles near solid surfaces

    NASA Astrophysics Data System (ADS)

    Takáts-Nyeste, Annamária; Derényi, Imre

    2014-11-01

    The behavior of lipid vesicles near solid surfaces, despite its scientific and technological significance, is poorly understood. By simultaneously taking into account (i) the dynamics of spontaneous pore opening and closing in surface bound vesicles; (ii) their volume loss via leakage through the pores; (iii) and the propagation of their contact line, we have developed a simple model that can fully describe the detailed mechanism of and provide the necessary conditions for the rupture of vesicles and the subsequent formation of supported lipid bilayers. The predictions of the model are in qualitative agreement with many of the experimental observations.

  18. Molecular self-assembly at solid surfaces.

    PubMed

    Otero, Roberto; Gallego, José María; de Parga, Amadeo L Vázquez; Martín, Nazario; Miranda, Rodolfo

    2011-11-23

    Self-assembly, the process by which objects initially distributed at random arrange into well-defined patterns exclusively due to their local mutual interactions without external intervention, is generally accepted to be the most promising method for large-scale fabrication of functional nanostructures. In particular, the ordering of molecular building-blocks deposited at solid surfaces is relevant for the performance of many organic electronic and optoelectronic devices, such as organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) or photovoltaic solar cells. However, the fundamental knowledge on the nature and strength of the intermolecular and molecule-substrate interactions that govern the ordering of molecular adsorbates is, in many cases, rather scarce. In most cases, the structure and morphology of the organic-metal interface is not known and it is just assumed to be the same as in the bulk, thereby implicitly neglecting the role of the surface on the assembly. However, this approximation is usually not correct, and the evidence gathered over the last decades points towards an active role of the surface in the assembly, leading to self-assembled structures that only in a few occasions can be understood by considering just intermolecular interactions in solid or gas phases. In this work we review several examples from our recent research demonstrating the apparently endless variety of ways in which the surface might affect the assembly of organic adsorbates.

  19. Rupture and dewetting of water films on solid surfaces.

    PubMed

    Mulji, Neil; Chandra, Sanjeev

    2010-12-01

    An experimental study was conducted to observe rupture and dewetting of water films, 0.5-2mm thick, on solid surfaces. The effects of surface roughness, wettability, protrusions on surfaces, and air entrapment between films and surfaces were studied. Film thickness measurements were made and film rupture and surface dewetting photographed. Experiments showed that liquid films ruptured first along the highest edges of test surfaces. Placing a protrusion on the surface had no effect-the liquid film continued to rupture along the edges. A thermodynamic model was developed to show that protrusions lower the surface energy of the system and promote wetting. Increasing surface roughness therefore increases film stability by resisting rupture and dewetting. Water films could be punctured by introducing an air bubble that burst and created a hole. The hole would close if the film was thick and the solid-liquid contact angle was either small or large; the hole would grow larger if the film was thin and the contact angle was in the mid-range (∼80°). An analytical model that calculates the difference between the surface energies of the two states can be used to predict whether a hole would lead to surface dewetting or not. Copyright © 2010 Elsevier Inc. All rights reserved.

  20. Acoustic Measurements for Small Solid Rocket Motors

    NASA Technical Reports Server (NTRS)

    Vargas, Magda B.; Kenny, R. Jeremy

    2010-01-01

    Models have been developed to predict large solid rocket motor acoustic loads based on the scaling of small solid rocket motors. MSFC has measured several small solid rocket motors in horizontal and launch configurations to anchor these models. Solid Rocket Test Motor (SRTM) has ballistics similar to the Reusable Solid Rocket Motor (RSRM) therefore a good choice for acoustic scaling. Acoustic measurements were collected during the test firing of the Insulation Configuration Extended Length (ICXL) 7,6, and 8 (in firing order) in order to compare to RSRM horizontal firing data. The scope of this presentation includes: Acoustic test procedures and instrumentation implemented during the three SRTM firings and Data analysis method and general trends observed in the data.

  1. Measurement of surface microtopography

    NASA Technical Reports Server (NTRS)

    Wall, S. D.; Farr, T. G.; Muller, J.-P.; Lewis, P.; Leberl, F. W.

    1991-01-01

    Acquisition of ground truth data for use in microwave interaction modeling requires measurement of surface roughness sampled at intervals comparable to a fraction of the microwave wavelength and extensive enough to adequately represent the statistics of a surface unit. Sub-centimetric measurement accuracy is thus required over large areas, and existing techniques are usually inadequate. A technique is discussed for acquiring the necessary photogrammetric data using twin film cameras mounted on a helicopter. In an attempt to eliminate tedious data reduction, an automated technique was applied to the helicopter photographs, and results were compared to those produced by conventional stereogrammetry. Derived root-mean-square (RMS) roughness for the same stereo-pair was 7.5 cm for the automated technique versus 6.5 cm for the manual method. The principal source of error is probably due to vegetation in the scene, which affects the automated technique but is ignored by a human operator.

  2. Laboratory Measurements of Celestial Solids

    NASA Technical Reports Server (NTRS)

    Sievers, A. J.; Beckwith, S. V. W.

    1997-01-01

    Our experimental study has focused on laboratory measurements of the low temperature optical properties of a variety of astronomically significant materials in the infrared and mm-wave region of the spectrum. Our far infrared measurements of silicate grains with an open structure have produced a variety of unusual results: (1) the low temperature mass opacity coefficient of small amorphous 2MgO(central dot)SiO2 and MgO(central dot)2SiO2 grains are many times larger than the values previously used for interstellar grain material; (2) all of the amorphous silicate grains studied possess the characteristic temperature dependent signature associated with two level systems in bulk glass; and (3) a smaller but nonzero two level temperature dependence signature is also observed for crystalline particles, its physical origin is unclear. These laboratory measurements yield surprisingly large and variable values for the mm-wave absorption coefficients of small silicate particles similar to interstellar grains, and suggest that the bulk absorptivity of interstellar dust at these long wavelengths will not be well known without such studies. Furthermore, our studies have been useful to better understand the physics of the two level absorption process in amorphous and crystalline grains to gain confidence in the wide applicability of these results.

  3. An accurate determination of the surface energy of solid selenium

    NASA Astrophysics Data System (ADS)

    Guisbiers, G.; Arscott, S.; Snyders, R.

    2012-12-01

    Selenium is currently a key element for developing nano and micro-technologies. Nevertheless, the surface energy of solid selenium (γSe) reported in the literature is still questionable. In this work, we have measured γSe = 0.291 ± 0.025 J/m2 at 293 K using the sessile drop technique with different probe liquids, namely ethylene glycol, de-ionized water, mercury, and gallium. This value is in excellent agreement with theoretical predictions.

  4. Gravity effects on flame spreading over solid surfaces

    NASA Technical Reports Server (NTRS)

    Andracchio, C. R.; Cochran, T. H.

    1976-01-01

    The effects of gravity on the spreading of a flame over a solid combustible surface were determined. Flame propagation rates were measured from specimens of thin cellulose acetate sheets burning in both normal gravity (1 g) and reduced gravity (0 g) environments; the specimens were burned in various quiescent mixtures of oxygen, helium, argon, and nitrogen. A correlation for normal gravity and reduced gravity burning was obtained based on theoretical models of previous investigators.

  5. a Reflection (electron, 2ELECTRON) Coincidence Experiment for Solid Surfaces.

    NASA Astrophysics Data System (ADS)

    Zhu, Hong

    A state-of-the-art reflection (e,2e) coincidence experiment for solid surfaces has been designed, constructed, and implemented. Single crystal silicon reconstructed surfaces were studied to establish the feasibility of applying the coincidence spectroscopy technique to solid surfaces. The ultra high vacuum system necessary for clean surface studies has achieved a base pressure of 3 times 10^{-11} Torr. A narrow angle electron gun with a LaB_6 offset-cathode was designed to meet the specifications of the experiment. In order to improve the time resolution of the apparatus, so as to enhance the true-to-accidental coincidence ratio, a compensation method utilizing lens -coupled spectrometers was developed for the electron energy analyzers used in the experiment. The components of the apparatus were characterized, and the surface conditions of the sample were monitored by the spectrometer systems used in the (e,2e) experiment: energy loss spectra, silicon Auger peaks, and a limited angular range of the electron diffraction pattern from silicon have been measured. Computer control of voltage supplies to the gun and the spectrometer systems, and automatic data acquisition have been achieved for total automation of the experiment. For the first time true coincidences have been searched for on solid surfaces, using the configuration for the determination of electron momentum distributions. In the experiment, surface contamination has been found and verified. Although the observation of true coincidences was hindered due to the contamination, the accidental coincidence count rates were measured. This measurement has led to an estimate of the lower limit of the triple differential cross section for the (e,2e) reaction, which is needed to observe true coincidences. The result suggests that the experiment is feasible only if the contamination problem is overcome.

  6. Degreasing of Solid Surfaces by Microbubble Cleaning

    NASA Astrophysics Data System (ADS)

    Miyamoto, Makoto; Ueyama, Satoshi; Hinomoto, Nobuhide; Saitoh, Tadashi; Maekawa, Shigeki; Hirotsuji, Junji

    2007-03-01

    It is increasingly required to reduce the environmental impact and cost in the field of industrial cleaning. As a substitute for conventional degreasing technology using organic solvents, acids, and alkalis, the authors have developed a new cleaning technology that uses microbubbles having an average diameter of about 70 μm. Grease being adsorbed onto a bubble’s surface and grease being separated from a solid surface by its buoyancy were captured using a high-speed microscopic video camera to demonstrate the degreasing capability of bubbles. High-density microbubbles were generated by adding a trace amount of a specific chemical (0.1% weight or less). The cleaning performance using microbubbles was found to be highly improved compared with that using normal bubbles. It was also revealed that the grease removal efficiency was strongly dependent on the viscosity of the grease. Raising the temperature of the cleaning solution is an effective method of improving cleaning performance by reducing the viscosity. Finally, the degreasing of about 150 machining metal parts at the same time was demonstrated to exceed the common target cleaning level (5-20 μg/cm2) in only 2 min because of their large surface area. Furthermore, the high degreasing performance was maintained even after repeated use of the cleaning solution because of the separation of grease due to buoyancy.

  7. Localization through Surface Folding in Solid Foams under Compression

    NASA Astrophysics Data System (ADS)

    Reis, P. M.; Corson, F.; Boudaoud, A.; Roman, B.

    2009-07-01

    We report a combined experimental and theoretical study of the compression of a solid foam coated with a thin elastic film. Past a critical compression threshold, a pattern of localized folds emerges with a characteristic size that is imposed by an instability of the thin surface film. We perform optical surface measurements of the statistical properties of these localization zones and find that they are characterized by robust exponential tails in the strain distributions. Following a hybrid continuum and statistical approach, we develop a theory that accurately describes the nucleation and length scale of these structures and predicts the characteristic strains associated with the localized regions.

  8. Acoustic Measurements of Small Solid Rocket Motor

    NASA Technical Reports Server (NTRS)

    Vargas, Magda B.; Kenny, R. Jeremy

    2010-01-01

    Rocket acoustic noise can induce loads and vibration on the vehicle as well as the surrounding structures. Models have been developed to predict these acoustic loads based on scaling existing solid rocket motor data. The NASA Marshall Space Flight Center acoustics team has measured several small solid rocket motors (thrust below 150,000 lbf) to anchor prediction models. This data will provide NASA the capability to predict the acoustic environments and consequent vibro-acoustic response of larger rockets (thrust above 1,000,000 lbf) such as those planned for the NASA Constellation program. This paper presents the methods used to measure acoustic data during the static firing of small solid rocket motors and the trends found in the data.

  9. Acoustic Measurements of Small Solid Rocket Motor

    NASA Technical Reports Server (NTRS)

    Vargas, Magda B.; Kenny, R. Jeremy

    2010-01-01

    Rocket acoustic noise can induce loads and vibration on the vehicle as well as the surrounding structures. Models have been developed to predict these acoustic loads based on scaling existing solid rocket motor data. The NASA Marshall Space Flight Center acoustics team has measured several small solid rocket motors (thrust below 150,000 lbf) to anchor prediction models. This data will provide NASA the capability to predict the acoustic environments and consequent vibro-acoustic response of larger rockets (thrust above 1,000,000 lbf) such as those planned for the NASA Constellation program. This paper presents the methods used to measure acoustic data during the static firing of small solid rocket motors and the trends found in the data.

  10. Solid-solid phase transition measurements in iron

    SciTech Connect

    Schwartz, Cynthia Louise

    2010-01-01

    Previously, dynamic experiments on iron have observed a non-zero transition time and width in the solid-solid {alpha}-{var_epsilon} phase transition. Using Proton Radiography at the Los Alamos Neutron Science Center, we have performed plate impact experiments on iron to further study the {alpha}-{var_epsilon} phase transition which occurs at 13GPa. A 40mm bore powder gun was coupled to a proton radiography beam line and imaging system and synchronized to the impact of the projectile on the target sample with the proton beam pattern. A typical experimental configuration for the iron study, as shown below in 3 color-enhanced radiographs, is a 40mm diameter aluminum sabot impacting a 40mm diameter of polycrystalline ARMCO iron. The iron is backed by a sapphire optical window for velocimetry measurements. The aluminum flyer on the left of the iron is barely visible for visual display purposes. Direct density jumps were measured which corresponded to calculations to within 1% using a Wondy mUlti-phase equation of state model. In addition, shock velocities were measured using an edge fitting technique and followed that edge movement from radiograph to radiograph, where radiographs are separated in time by 500 ns. Preliminary measurements give a shock velocity (P1 wave) of 5.251 km/s. The projectile velocity was 0.725 km/s which translate to a peak stress of 17.5 GPa. Assuming the P1 wave is instantaneous, we are able to calibrate the chromatic, motion, object and camera blur by measuring the width of the P1 wave. This approximation works in this case since each of the two density jumps are small compared to the density of the object. Subtracting the measured width of the P1 wave in quadrature from the width of the P2 wave gives a preliminary measurement of the transition length of 265 {mu}m. Therefore, a preliminary measured phase transition relaxation time {tau} = transition length/u{sub s} = 265 {mu}m/5.251 km/s = 50 ns. Both Boettger and Jensen conclude that the

  11. Particle engineering in pharmaceutical solids processing: surface energy considerations.

    PubMed

    Williams, Daryl R

    2015-01-01

    During the past 10 years particle engineering in the pharmaceutical industry has become a topic of increasing importance. Engineers and pharmacists need to understand and control a range of key unit manufacturing operations such as milling, granulation, crystallisation, powder mixing and dry powder inhaled drugs which can be very challenging. It has now become very clear that in many of these particle processing operations, the surface energy of the starting, intermediate or final products is a key factor in understanding the processing operation and or the final product performance. This review will consider the surface energy and surface energy heterogeneity of crystalline solids, methods for the measurement of surface energy, effects of milling on powder surface energy, adhesion and cohesion on powder mixtures, crystal habits and surface energy, surface energy and powder granulation processes, performance of DPI systems and finally crystallisation conditions and surface energy. This review will conclude that the importance of surface energy as a significant factor in understanding the performance of many particulate pharmaceutical products and processes has now been clearly established. It is still nevertheless, work in progress both in terms of development of methods and establishing the limits for when surface energy is the key variable of relevance.

  12. Armor Plate Surface Roughness Measurements

    DTIC Science & Technology

    2005-04-01

    Armor Plate Surface Roughness Measurements by Brian Stanton, William Coburn, and Thomas J. Pizzillo ARL-TR-3498 April 2005... Armor Plate Surface Roughness Measurements Brian Stanton, William Coburn and Thomas J. Pizzillo Sensors and Electron Devices Directorate...October 2004 5a. CONTRACT NUMBER 5b. GRANT NUMBER 4. TITLE AND SUBTITLE Armor Plate Surface Roughness Measurements 5c. PROGRAM ELEMENT NUMBER

  13. Turbulent boundary layer over solid and porous surfaces with small roughness

    NASA Technical Reports Server (NTRS)

    Kong, F. Y.; Schetz, J. A.; Collier, F.

    1982-01-01

    Skin friction and profiles of mean velocity, axial and normal turbulence intensity, and Reynolds stress in the untripped boundary layer were measured directly on a large diameter, axisymmetric body with: (1) a smooth, solid surface; (2) a sandpaper-roughened, solid surface; (3) a sintered metal, porous surface; (4) a smooth, perforated titanium surface; (5) a rough solid surface made of fine, diffusion bonded screening, and (6) a rough, porous surface of the same screening. Results obtained for each of these surfaces are discussed. It is shown that a rough, porous wall simply does not influence the boundary layer in the same way as a rough solid wall. Therefore, turbulent transport models for boundary layers over porous surfaces either with or without injection or suction, must include both surface roughness and porosity effects.

  14. Solid Surface Combustion Experiment: Thick Fuel Results

    NASA Technical Reports Server (NTRS)

    Altenkirch, Robert A.; Bhattacharjee, Subrata; West, Jeff; Tang, Lin; Sacksteder, Kurt; Delichatsios, Michael A.

    1997-01-01

    The results of experiments for spread over polymethylmethacrylate, PMMA, samples in the microgravity environment of the Space Shuttle are described. The results are coupled with modelling in an effort to describe the physics of the spread process for thick fuels in a quiescent, microgravity environment and uncover differences between thin and thick fuels. A quenching phenomenon not present for thin fuels is delineated, namely the fact that for thick fuels the possibility exists that, absent an opposing flow of sufficient strength to press the flame close enough to the fuel surface to allow the heated layer in the solid to develop, the heated layer fails to become 'fully developed.' The result is that the flame slows, which in turn causes an increase in the relative radiative loss from the flame, leading eventually to extinction. This potential inability of a thick fuel to develop a steady spread rate is not present for a thin fuel because the heated layer is the fuel thickness, which reaches a uniform temperature across the thickness relatively rapidly.

  15. Solid capillarity: when and how does surface tension deform soft solids?

    NASA Astrophysics Data System (ADS)

    Andreotti, Bruno; Bäumchen, Oliver; Boulogne, François; Daniels, Karen E.; Dufresne, Eric R.; Perrin, Hugo; Salez, Thomas; Snoeijer, Jacco H.; Style, Robert W.

    Soft solids differ from stiff solids in an important way: their surface stresses can drive large deformations. Based on a topical workshop held in the Lorentz Center in Leiden, this Opinion highlights some recent advances in the growing field of solid capillarity and poses key questions for its advancement.

  16. Drop impact onto semi-infinite solid surface

    NASA Astrophysics Data System (ADS)

    Chen, Huanchen; Amirfazli, Alidad

    2016-11-01

    The drop impact onto solid surfaces has been studied intensively due to its importance in different applications, e.g. spray coating, inkjet printing and agricultural sprays. The previous studies on this topic were typically focused either on the drop impact onto an infinite solid surface (i.e. a solid surface that is large, and the impact happens far away from the surface edges), or onto a finite solid surface (e.g. drop impact onto a target smaller than the droplet). However, in practice, it is also possible for the impact onto a large surface but close to its edge (named as semi-infinite surface). In this first study of its kind, the process of drop impact onto a semi-infinite surface (both hydrophobic and hydrophilic) was investigated experimentally. During the impact process, part of the liquid lamella can spread out of the surface (free lamella). Depending on the distance between the impact point and surface edge, the free lamella can recede, or partially recede back to the surface, or completely break apart at the surface edge. The behavior of free lamella can also affect the morphology of the part of liquid lamella which remains in contact with the solid surface, especially in the receding phase (e.g. occurrence of drop rebound). Various morphologies observed for lamella breakage at the surface edge will also be discussed for surfaces of different wettabilities.

  17. Surface roughness measurements

    NASA Astrophysics Data System (ADS)

    Howard, Thomas G.

    1994-10-01

    The Optics Division is currently in the research phase of producing grazing-incidence mirrors to be used in x-ray detector applications. The traditional method of construction involves labor-intensive glass grinding. This also culminates in a relatively heavy mirror. For lower resolution applications, the mirrors may be of a replicated design which involves milling a mandrel as a negative of the final shape and electroplating the cylindrical mirror onto it. The mirror is then separated from the mandrel by cooling. The mandrel will shrink more than the 'shell' (mirror) allowing it to be pulled from the mandrel. Ulmer (2) describes this technique and its variations in more detail. To date, several mirrors have been tested at MSFC by the Optical Fabrication Branch by focusing x-ray energy onto a detector with limited success. Little is known about the surface roughness of the actual mirror. Hence, the attempt to gather data on these surfaces. The test involves profiling the surface of a sample, replicating the surface as described above, and then profiling the replicated surface.

  18. Universal deformation of soft substrates near contact line reveals solid surface stresses

    NASA Astrophysics Data System (ADS)

    Style, Robert; Wettlaufer, John; Wilen, Larry; Dufresne, Eric

    2012-11-01

    We study how sessile droplets behave on soft substrates. Using confocal microscopy, we investigate how droplet surface tension (and Laplace pressure) deforms the substrate. We show that the near-tip shape of the wetting ridge is entirely determined by the surface tensions of the three contacting phases. In particular we can use this observation to (i) directly measure solid-vapour and solid-liquid surface tensions, (ii) resolve how out-of-plane force balance is ensured at the contact line.

  19. Surface temperature measurement errors

    SciTech Connect

    Keltner, N.R.; Beck, J.V.

    1983-05-01

    Mathematical models are developed for the response of surface mounted thermocouples on a thick wall. These models account for the significant causes of errors in both the transient and steady-state response to changes in the wall temperature. In many cases, closed form analytical expressions are given for the response. The cases for which analytical expressions are not obtained can be easily evaluated on a programmable calculator or a small computer.

  20. Homogenous Surface Nucleation of Solid Polar Stratospheric Cloud Particles

    NASA Technical Reports Server (NTRS)

    Tabazadeh, A.; Hamill, P.; Salcedo, D.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    A general surface nucleation rate theory is presented for the homogeneous freezing of crystalline germs on the surfaces of aqueous particles. While nucleation rates in a standard classical homogeneous freezing rate theory scale with volume, the rates in a surface-based theory scale with surface area. The theory is used to convert volume-based information on laboratory freezing rates (in units of cu cm, seconds) of nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD) aerosols into surface-based values (in units of sq cm, seconds). We show that a surface-based model is capable of reproducing measured nucleation rates of NAT and NAD aerosols from concentrated aqueous HNO3 solutions in the temperature range of 165 to 205 K. Laboratory measured nucleation rates are used to derive free energies for NAT and NAD germ formation in the stratosphere. NAD germ free energies range from about 23 to 26 kcal mole, allowing for fast and efficient homogeneous NAD particle production in the stratosphere. However, NAT germ formation energies are large (greater than 26 kcal mole) enough to prevent efficient NAT particle production in the stratosphere. We show that the atmospheric NAD particle production rates based on the surface rate theory are roughly 2 orders of magnitude larger than those obtained from a standard volume-based rate theory. Atmospheric volume and surface production of NAD particles will nearly cease in the stratosphere when denitrification in the air exceeds 40 and 78%, respectively. We show that a surface-based (volume-based) homogeneous freezing rate theory gives particle production rates, which are (not) consistent with both laboratory and atmospheric data on the nucleation of solid polar stratospheric cloud particles.

  1. Homogenous Surface Nucleation of Solid Polar Stratospheric Cloud Particles

    NASA Technical Reports Server (NTRS)

    Tabazadeh, A.; Hamill, P.; Salcedo, D.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    A general surface nucleation rate theory is presented for the homogeneous freezing of crystalline germs on the surfaces of aqueous particles. While nucleation rates in a standard classical homogeneous freezing rate theory scale with volume, the rates in a surface-based theory scale with surface area. The theory is used to convert volume-based information on laboratory freezing rates (in units of cu cm, seconds) of nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD) aerosols into surface-based values (in units of sq cm, seconds). We show that a surface-based model is capable of reproducing measured nucleation rates of NAT and NAD aerosols from concentrated aqueous HNO3 solutions in the temperature range of 165 to 205 K. Laboratory measured nucleation rates are used to derive free energies for NAT and NAD germ formation in the stratosphere. NAD germ free energies range from about 23 to 26 kcal mole, allowing for fast and efficient homogeneous NAD particle production in the stratosphere. However, NAT germ formation energies are large (greater than 26 kcal mole) enough to prevent efficient NAT particle production in the stratosphere. We show that the atmospheric NAD particle production rates based on the surface rate theory are roughly 2 orders of magnitude larger than those obtained from a standard volume-based rate theory. Atmospheric volume and surface production of NAD particles will nearly cease in the stratosphere when denitrification in the air exceeds 40 and 78%, respectively. We show that a surface-based (volume-based) homogeneous freezing rate theory gives particle production rates, which are (not) consistent with both laboratory and atmospheric data on the nucleation of solid polar stratospheric cloud particles.

  2. Solids flow rate measurement in dense slurries

    SciTech Connect

    Porges, K.G.; Doss, E.D.

    1993-09-01

    Accurate and rapid flow rate measurement of solids in dense slurries remains an unsolved technical problem, with important industrial applications in chemical processing plants and long-distance solids conveyance. In a hostile two-phase medium, such a measurement calls for two independent parameter determinations, both by non-intrusive means. Typically, dense slurries tend to flow in laminar, non-Newtonian mode, eliminating most conventional means that usually rely on calibration (which becomes more difficult and costly for high pressure and temperature media). These issues are reviewed, and specific solutions are recommended in this report. Detailed calculations that lead to improved measuring device designs are presented for both bulk density and average velocity measurements. Cross-correlation, chosen here for the latter task, has long been too inaccurate for practical applications. The cause and the cure of this deficiency are discussed using theory-supported modeling. Fluid Mechanics are used to develop the velocity profiles of laminar non-Newtonian flow in a rectangular duct. This geometry uniquely allows the design of highly accurate `capacitive` devices and also lends itself to gamma transmission densitometry on an absolute basis. An absolute readout, though of less accuracy, is also available from a capacitive densitometer and a pair of capacitive sensors yields signals suitable for cross-correlation velocity measurement.

  3. Softening of edges of solids by surface tension

    NASA Astrophysics Data System (ADS)

    Mora, Serge; Pomeau, Yves

    2015-05-01

    Surface tension tends to minimize the area of interfaces between pieces of matter in different thermodynamic phases, be they in the solid or the liquid state. This can be relevant for the macroscopic shape of very soft solids and lead to a roughening of initially sharp edges. We calculate this effect for a Neo-Hookean elastic solid, with assumptions corresponding to actual experiments, namely the case where an initially sharp edge is rounded by the effect of surface tension felt when the fluid surrounding the soft solid (and so surface tension) is changed at the solid/liquid boundary. We consider two opposite limits where the analysis can be carried to the end, the one of a shallow angle and the one of a very sharp angle. Both cases yield a discontinuity of curvature in the state with surface tension although the initial state had a discontinuous slope.

  4. Softening of edges of solids by surface tension.

    PubMed

    Mora, Serge; Pomeau, Yves

    2015-05-20

    Surface tension tends to minimize the area of interfaces between pieces of matter in different thermodynamic phases, be they in the solid or the liquid state. This can be relevant for the macroscopic shape of very soft solids and lead to a roughening of initially sharp edges. We calculate this effect for a Neo-Hookean elastic solid, with assumptions corresponding to actual experiments, namely the case where an initially sharp edge is rounded by the effect of surface tension felt when the fluid surrounding the soft solid (and so surface tension) is changed at the solid/liquid boundary. We consider two opposite limits where the analysis can be carried to the end, the one of a shallow angle and the one of a very sharp angle. Both cases yield a discontinuity of curvature in the state with surface tension although the initial state had a discontinuous slope.

  5. Surface effects on nanoindentation of soft solids by different indenters

    NASA Astrophysics Data System (ADS)

    Ding, Yue; Niu, Xin-Rui; Wang, Gang-Feng; Feng, Xi-Qiao; Yu, Shou-Wen

    2016-11-01

    For soft materials like biological tissues and gels, surface energy and hyperelasticity have significant influences on their mechanical response to external load. In this paper, we investigate the effects of surface energy on nanoindentation of hyperelastic solids by using conical, flat and spherical indenters. The hyperelastic behavior of soft solids is characterized by the neo-Hookean model, and the influence of surface energy is analyzed through finite element simulations. For the three typical indenters, the explicit relations between compressive load and indent depth are obtained considering both finite deformation and surface energy. When the contact radius is comparable with the ratio of surface energy density to elastic modulus, surface energy will evidently alter the contact pressure, surface profile, and overall response. Compared to the linear elastic predictions, the neo-Hookean hyperelasticity tends to increase the indent depth, while surface energy has a reverse effect. The obtained results are helpful to accurately characterize the mechanical response of soft solids via nanoindentation tests.

  6. Measurement of Thermal Radiation Properties of Solids

    NASA Technical Reports Server (NTRS)

    Richmond, J. C. (Editor)

    1963-01-01

    The overall objectives of the Symposium were to afford (1) an opportunity for workers in the field to describe the equipment and procedures currently in use for measuring thermal radiation properties of solids, (2) an opportunity for constructive criticism of the material presented, and (3) an open forum for discussion of mutual problems. It was also the hope of the sponsors that the published proceedings of the Symposium would serve as a valuable reference on measurement techniques for evaluating thermal radiation properties of solids, partic.ularly for those with limited experience in the field. Because of the strong dependence of emitted flux upon temperature, the program committee thought it advisable to devote the first session to a discussion of the problems of temperature measurement. All of the papers in Session I were presented at the request of and upon topics suggested by the Committee. Because of time and space limitations, it, was impossible to consider all temperature measurement problems that might arise--the objective was rather to call to the attention of the reader some of the problems that might be encountered, and to provide references that might provide solutions.

  7. Structure and properties of solid surfaces

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.

    1974-01-01

    Difficulties in experimental studies of crystalline surfaces are related to the fact that surface atoms have an intrinsic tendency to react with their environment. A second problem is connected with the effective thickness of surfaces, which ranges from one to several atom layers. The phenomenology of surface interactions with gases are considered, taking into account physical adsorption, chemisorption, and the oxidation of surfaces. Studies of the surface structure are discussed, giving attention to field emission microscopy, field-ion microscopy, electron diffraction techniques, Auger spectroscopy, scanning electron microscopy, electron probe microanalysis, ion microprobe methods, and low-energy backscattering spectroscopy. Investigations of semiconductor surfaces are also described.

  8. Structure and properties of solid surfaces

    NASA Technical Reports Server (NTRS)

    Gatos, H. C.

    1974-01-01

    Difficulties in experimental studies of crystalline surfaces are related to the fact that surface atoms have an intrinsic tendency to react with their environment. A second problem is connected with the effective thickness of surfaces, which ranges from one to several atom layers. The phenomenology of surface interactions with gases are considered, taking into account physical adsorption, chemisorption, and the oxidation of surfaces. Studies of the surface structure are discussed, giving attention to field emission microscopy, field-ion microscopy, electron diffraction techniques, Auger spectroscopy, scanning electron microscopy, electron probe microanalysis, ion microprobe methods, and low-energy backscattering spectroscopy. Investigations of semiconductor surfaces are also described.

  9. Understanding contact angle hysteresis on an ambient solid surface

    NASA Astrophysics Data System (ADS)

    Wang, Yong Jian; Guo, Shuo; Chen, Hsuan-Yi; Tong, Penger

    2016-05-01

    We report a systematic study of contact angle hysteresis (CAH) with direct measurement of the capillary force acting on a contact line formed on the surface of a long glass fiber intersecting a liquid-air interface. The glass fiber of diameter 1 -2 μ m and length 100 -200 μ m is glued onto the front end of a rectangular cantilever beam, which is used for atomic force microscopy. From the measured hysteresis loop of the capillary force for 28 different liquids with varying surface tensions and contact angles, we find a universal behavior of the unbalanced capillary force in the advancing and receding directions and the spring constant of a stretched meniscus by the glass fiber. Measurements of the capillary force and its fluctuations suggest that CAH on an ambient solid surface is caused primarily by two types of coexisting and spatially intertwined defects with opposite natures. The contact line is primarily pinned by the relatively nonwetting (repulsive) defects in the advancing direction and by the relatively wetting (attractive) defects in the receding direction. Based on the experimental observations, we propose a "composite model" of CAH and relevant scaling laws, which explain the basic features of the measured hysteresis force loops.

  10. Understanding contact angle hysteresis on an ambient solid surface.

    PubMed

    Wang, Yong Jian; Guo, Shuo; Chen, Hsuan-Yi; Tong, Penger

    2016-05-01

    We report a systematic study of contact angle hysteresis (CAH) with direct measurement of the capillary force acting on a contact line formed on the surface of a long glass fiber intersecting a liquid-air interface. The glass fiber of diameter 1-2μm and length 100-200μm is glued onto the front end of a rectangular cantilever beam, which is used for atomic force microscopy. From the measured hysteresis loop of the capillary force for 28 different liquids with varying surface tensions and contact angles, we find a universal behavior of the unbalanced capillary force in the advancing and receding directions and the spring constant of a stretched meniscus by the glass fiber. Measurements of the capillary force and its fluctuations suggest that CAH on an ambient solid surface is caused primarily by two types of coexisting and spatially intertwined defects with opposite natures. The contact line is primarily pinned by the relatively nonwetting (repulsive) defects in the advancing direction and by the relatively wetting (attractive) defects in the receding direction. Based on the experimental observations, we propose a "composite model" of CAH and relevant scaling laws, which explain the basic features of the measured hysteresis force loops.

  11. Oceanic Precipitation Measurement - Surface Validation

    NASA Astrophysics Data System (ADS)

    Klepp, Christian

    2013-04-01

    State-of-the-art satellite derived and reanalysis based precipitation climatologies still show remarkably large differences in frequency, amount, intensity, variability and temporal behavior of precipitation over the oceans. Additionally so far appropriate in-situ validation instruments were not available for shipboard use. The uncertainties are largest for light precipitation within the ITCZ and subtropics and for cold season high-latitude precipitation including mix-phase and snowfall. Hence, a long-term issue on which IPWG and GPM-GV is urging more attention is the provision of high quality surface validation data in oceanic areas using innovative ship-based instruments. Precipitation studies would greatly benefit from systematic dataset collection and analysis as such data could also be used to constrain precipitation retrievals. To achieve this goal, the KlimaCampus and Max Planck Institute for Meteorology in Hamburg, Germany funded this project that uses automated shipboard optical disdrometers, called Eigenbrodt ODM470, that are capable of measuring liquid and solid precipitation using drop size distributions in minute intervals on moving ships with high accuracy even under high wind speeds and rough sea states. Since the project start in 2009 the statistical basis for a conclusive validation has significantly improved with comprehensive data collection of more than 3 million minutes of precipitation measurements onboard six ships. Currently, six ODM470 instrument systems are available of which three are long-term mounted onboard the German research icebreaker R/V Polarstern (Alfred Wegner Institut) since June 2010, on R/V Akademik Ioffe (P.P.Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia) since September 2010 and on R/V Maria S. Merian (Brise Research, University of Hamburg) since December 2011. Three instruments are used for additional short-term shipboard campaigns and intercomparison projects. The core regions for these

  12. Computerized interferometric surface measurements [Invited].

    PubMed

    Wyant, James C

    2013-01-01

    The addition of electronics, computers, and software to interferometry has enabled enormous improvements in optical metrology. This paper discusses four areas in which computerized interferometric measurement improvements have been made in the measurement of surface shape and surface roughness: (a) The use of computer-generated holograms for the testing of aspheric optics, (b) phase-shifting interferometry for getting interferometric data into a computer so the data can be analyzed, (c) computerized interference microscopes, including multiple-wavelength and coherence scanning, for the precision measurement of surface microstructure, and (d) vibration-insensitive dynamic interferometers for enabling precise measurements in noncontrolled environments.

  13. Condensed matter physics at surfaces and interfaces of solids

    SciTech Connect

    Mele, E.J.

    1992-01-01

    This research program is focused on structural and elastic properties of crystalline solids and interfaces between solids. We are particularly interested in novel forms of structural ordering and the effects of this ordering on the lattice dynamical properties. We are currently studying structural and vibrational properties of the surfaces of the elemental alkaline earths (particularly Be), and structural phenomena in the doped fullerites.

  14. Thermospreading of a liquid upon a solid surface

    NASA Astrophysics Data System (ADS)

    Bykhovskii, A. I.

    1990-02-01

    One-dimensional spreading of a liquid upon a solid surface is considered under the condition of a constant temperature gradient along the surface (thermospreading). If the spreading liquid interacts with the underlying surface, forming a solution or a chemical compound, a thermoflow of mixing takes place along with thermocapillary and thermo-osmotic flows.

  15. Measuring Light Reflectance of BGO Crystal Surfaces

    NASA Astrophysics Data System (ADS)

    Janecek, Martin; Moses, William W.

    2008-10-01

    A scintillating crystal's surface reflectance has to be well understood in order to accurately predict and optimize the crystal's light collection through Monte Carlo simulations. In this paper, we measure the inner surface reflectance properties for BGO. The measurements include BGO crystals with a mechanically polished surface, rough-cut surface, and chemically etched surface, and with various reflectors attached, both air-coupled and with coupling compound. The measurements are performed with a laser aimed at the center of a hemispherical shaped BGO crystal. The hemispherical shape eliminates any non-perpendicular angles for light entering and exiting the crystal. The reflected light is collected with an array of photodiodes. The laser can be set at an arbitrary angle, and the photodiode array is rotated to fully cover 2pi of solid angle. The current produced in the photodiodes is readout with a digital multimeter connected through a multiplexer. The two rows of photodiodes achieve 5-degree by 4-degree resolution, and the current measurement has a dynamic range of 105:1. The acquired data was not described by the commonly assumed linear combination of specular and diffuse (Lambertian) distributions, except for a very few surfaces. Surface roughness proved to be the most important parameter when choosing crystal setup. The reflector choice was of less importance and of almost no consequence for rough-cut surfaces. Pure specular reflection distribution for all incidence angles was measured for polished surfaces with VM2000 film, while the most Lambertian distribution for any surface finish was measured for titanium dioxide paint. The distributions acquired in this paper will be used to create more accurate Monte Carlo models for light reflection distribution within BGO crystals.

  16. Measuring Light Reflectance of BGO Crystal Surfaces

    SciTech Connect

    Janecek, Martin; Moses, William

    2008-07-28

    A scintillating crystal's surface reflectance has to be well understood in order to accurately predict and optimize the crystal?s light collection through Monte Carlo simulations. In this paper, we measure the inner surface reflectance properties for BGO. The measurements include BGO crystals with a mechanically polished surface, rough-cut surface, and chemically etched surface, and with various reflectors attached, both air- coupled and with coupling compound. The measurements are performed with a laser aimed at the center of a hemispherical shaped BGO crystal. The hemispherical shape eliminates any non-perpendicular angles for light entering and exiting the crystal. The reflected light is collected with an array of photodiodes. The laser can be set at an arbitrary angle, and the photodiode array is rotated to fully cover 2? of solid angle. The current produced in the photodiodes is readout with a digital multimeter connected through a multiplexer. The two rows of photodiodes achieve 5-degree by 4-degree resolution, and the current measurement has a dynamic range of 10^5:1. The acquired data was not described by the commonly assumed linear combination of specular and diffuse (Lambertian) distributions, except for a very few surfaces. Surface roughness proved to be the most important parameter when choosing crystal setup. The reflector choice was of less importance and of almost no consequence for rough-cut surfaces. Pure specular reflection distribution for all incidence angles was measured for polished surfaces with VM2000 film, while the most Lambertian distribution for any surface finish was measured for titanium dioxide paint. The distributions acquired in this paper will be used to create more accurate Monte Carlo models for light reflection distribution within BGO crystals.

  17. Thermal slip for liquids at rough solid surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Chengbin; Chen, Yongping; Peterson, G. P.

    2014-06-01

    Molecular dynamics simulation is used to examine the thermal slip of liquids at rough solid surfaces as characterized by fractal Cantor structures. The temperature profiles, potential energy distributions, thermal slip, and interfacial thermal resistance are investigated and evaluated for a variety of surface topographies. In addition, the effects of liquid-solid interaction, surface stiffness, and boundary condition on thermal slip length are presented. Our results indicate that the presence of roughness expands the low potential energy regions in adjacent liquids, enhances the energy transfer at liquid-solid interface, and decreases the thermal slip. Interestingly, the thermal slip length and thermal resistance for liquids in contact with solid surfaces depends not only on the statistical roughness height, but also on the fractal dimension (i.e., topographical spectrum).

  18. Elastocapillarity: Surface Tension and the Mechanics of Soft Solids

    NASA Astrophysics Data System (ADS)

    Style, Robert W.; Jagota, Anand; Hui, Chung-Yuen; Dufresne, Eric R.

    2017-03-01

    It is widely appreciated that surface tension can dominate the behavior of liquids at small scales. Solids also have surface stresses of a similar magnitude, but they are usually overlooked. However, recent work has shown that these can play a central role in the mechanics of soft solids such as gels. Here, we review this emerging field. We outline the theory of surface stresses, from both mechanical and thermodynamic perspectives, emphasizing the relationship between surface stress and surface energy. We describe a wide range of phenomena at interfaces and contact lines where surface stresses play an important role. We highlight how surface stresses cause dramatic departures from classic theories for wetting (Young-Dupré), adhesion (Johnson-Kendall-Roberts), and composites (Eshelby). A common thread is the importance of the ratio of surface stress to an elastic modulus, which defines a length scale below which surface stresses can dominate.

  19. Tools for measuring surface cleanliness

    DOEpatents

    Schroder, Mark Stewart; Woodmansee, Donald Ernest; Beadie, Douglas Frank

    2002-01-01

    A procedure and tools for quantifying surface cleanliness are described. Cleanliness of a target surface is quantified by wiping a prescribed area of the surface with a flexible, bright white cloth swatch, preferably mounted on a special tool. The cloth picks up a substantial amount of any particulate surface contamination. The amount of contamination is determined by measuring the reflectivity loss of the cloth before and after wiping on the contaminated system and comparing that loss to a previous calibration with similar contamination. In the alternative, a visual comparison of the contaminated cloth to a contamination key provides an indication of the surface cleanliness.

  20. Turbulent boundary layer over solid and porous surfaces with small roughness

    NASA Technical Reports Server (NTRS)

    Kong, F. Y.; Schetz, J. A.; Collier, F.

    1982-01-01

    The wind tunnel models and instrumentation used as well as data reduction and error analysis techniques employed are described for an experimental study conducted to measure directly skin friction and obtain profiles of mean velocity, axial and normal turbulence intensity, and Reynolds stress in the untripped boundary on a large diameter axisymmetric body. Results are given for such a body with a (1) smooth, solid surface; (2) a sandpaper roughened, solid surface; (3) a sintered metal, porous surface; (4) a ""smooth'' performated titanium surface; (5) a rough, solid surface made of fine diffusion bonded screening; and (6) a rough, porous surface made of the same screening. The roughness values were in low range (k+ 5 to 7) just above what is normally considered ""hydraulically smooth''. Measurements were taken at several axial locations and tow or normal stream freestream velocities, 45.1 m/sec and 53.5 m/sec.

  1. Atmosphere-surface exchange measurements.

    PubMed

    Dabberdt, W F; Lenschow, D H; Horst, T W; Zimmerman, P R; Oncley, S P; Delany, A C

    1993-06-04

    The exchange of various trace species and energy at the earth's surface plays an important role in climate, ecology, and human health and welfare. Surface exchange measurements can be difficult to obtain yet are important to understand physical processes, assess environmental and global change impacts, and develop robust parameterizations of atmospheric processes. The physics and turbulent structure of the atmospheric boundary layer are reviewed as they contribute to dry surface exchange rates (fluxes). Micrometeorological, budget, and enclosure techniques used to measure or estimate surface fluxes are described, along with their respective advantages and limitations. Various measurement issues (such as site characteristics, sampling considerations, sensor attributes, and flow distortion) impact on the ability to obtain representative surface-based and airborne flux data.

  2. Precursors to splashing of liquid droplets on a solid surface.

    PubMed

    Mandre, Shreyas; Mani, Madhav; Brenner, Michael P

    2009-04-03

    A high velocity impact between a liquid droplet and a solid surface produces a splash. Classical work traced the origin of the splash to a thin sheet of fluid ejected near the impact point. Mechanisms of sheet formation have heretofore relied on initial contact of the droplet and the surface. We demonstrate that, neglecting intermolecular forces between the liquid and the solid, the liquid does not contact the solid, and instead spreads on a very thin air film. The interface of the droplet develops a high curvature and emits capillary waves.

  3. Development of surfaces repelling negatively buoyant solid particles

    NASA Astrophysics Data System (ADS)

    Semmler, Carina; Alexeev, Alexander

    2011-03-01

    Using a hybrid computational method that integrates the lattice Boltzmann model for fluid dynamics and the lattice spring model for solids, we examine the motion of negatively buoyant solid microparticles in shear flow near a solid wall decorated with regularly distributed rigid posts. The posts are arranged in a square pattern and tilted relative to the flow direction. We show that when rigid posts are tilted against flow, secondary flows emerge that prevent the deposition of suspended particles on the solid surface. We probe the effect of post geometry on the development of secondary flows and identify the optimal post architecture in terms of the mass of levitated solid particles. Our results are useful for designing anti-fouling surfaces that repel colloidal particles carried by fluid.

  4. Measuring Roughnesses Of Optical Surfaces

    NASA Technical Reports Server (NTRS)

    Coulter, Daniel R.; Al-Jumaily, Gahnim A.; Raouf, Nasrat A.; Anderson, Mark S.

    1994-01-01

    Report discusses use of scanning tunneling microscopy and atomic force microscopy to measure roughnesses of optical surfaces. These techniques offer greater spatial resolution than other techniques. Report notes scanning tunneling microscopes and atomic force microscopes resolve down to 1 nm.

  5. Probing and mapping electrode surfaces in solid oxide fuel cells.

    PubMed

    Blinn, Kevin S; Li, Xiaxi; Liu, Mingfei; Bottomley, Lawrence A; Liu, Meilin

    2012-09-20

    Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen (1-7). The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion(2). Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation(8-12). It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition(8, 10, 13, 14) ("coking") and sulfur poisoning(11, 15) and the manner in which surface modifications stave off this degradation(16). The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM

  6. Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

    PubMed Central

    Blinn, Kevin S.; Li, Xiaxi; Liu, Mingfei; Bottomley, Lawrence A.; Liu, Meilin

    2012-01-01

    Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM

  7. Lost surface waves in nonpiezoelectric solids

    NASA Astrophysics Data System (ADS)

    Eliseev, Eugene A.; Morozovska, Anna N.; Glinchuk, Maya D.; Kalinin, Sergei V.

    2017-07-01

    The existence of shear surface acoustic waves (SAWs) has been regarded as impossible in nonpiezoelectrics with homogeneous flat surfaces. We show that transverse shear SAWs can propagate near the flat surfaces of all crystalline dielectrics due to the omnipresent flexoelectric coupling. It appears that the penetration depth of the previously unexplored SAW is defined by the flexocoupling strength. Since the SAW occurs due to the flexoelectric coupling, we name it the flexoelectric SAW (flexo-SAW). We predict that the phonon spectra corresponding to the flexo-SAWs and bulk phonon modes can be separated in thin nonpiezoelectric films, such as strontium titanate.

  8. Scanning Tunneling Microspectroscopy of Solids and Surfaces - Final Report

    SciTech Connect

    Wolf, E. L.

    2002-03-15

    Experimental and theoretical research on the bulk and surface properties of conductive solid state materials has been performed based on the techniques of scanning tunneling microscopy and scanning tunneling spectroscopy, often at cryogenic temperatures. The research has focused on the electronic properties, particularly the superconductivity, of high temperature superconductors and other layered systems. The superconducting electronic density of states N(E)=dI/dV of the high T{sub c} superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} was measured with spatial resolution of 5 A at 4.2K. An internal superconducting proximity effect was inferred to operate between Cu and Bi based layers of the crystal in those regions where the Bi layers are metallic in nature. This research project supported the thesis research of several young scientists, and led to a significant number of published papers, presentations and reports.

  9. Solid scintillation counting: a new technique for measuring radiolabeled compounds.

    PubMed

    Wunderly, S W

    1989-01-01

    This report describes the theory and practice of anew solid scintillator technique for measurement of radiolabeled compounds useful in bioresearch. Solid scintillation counting is expected to replace liquid scintillation counting in certain applications involving non-volatile radiolabeled substrates.

  10. Artefacts for optical surface measurement

    NASA Astrophysics Data System (ADS)

    Robson, Stuart; Beraldin, J.-Angelo; Brownhill, Andrew; MacDonald, Lindsay

    2011-07-01

    Flexible manufacturing technologies are supporting the routine production of components with freeform surfaces in a wide variety of materials and surface finishes. Such surfaces may be exploited for both aesthetic and performance criteria for a wide range of industries, for example automotive, aircraft, small consumer goods and medial components. In order to ensure conformance between manufactured part and digital design it is necessary to understand, validate and promote best practice of the available measurement technologies. Similar, but currently less quantifiable, measurement requirements also exist in heritage, museum and fine art recording where objects can be individually hand crafted to extremely fine levels of detail. Optical 3D measurement systems designed for close range applications are typified by one or more illumination sources projecting a spot, line or structured light pattern onto a surface or surfaces of interest. Reflections from the projected light are detected in one or more imaging devices and measurements made concerning the location, intensity and optionally colour of the image. Coordinates of locations on the surface may be computed either directly from an understanding of the illumination and imaging geometry or indirectly through analysis of the spatial frequencies of the projected pattern. Regardless of sensing configuration some independent means is necessary to ensure that measurement capability will meet the requirements of a given level of object recording and is consistent for variations in surface properties and structure. As technologies mature, guidelines for best practice are emerging, most prominent at the current time being the German VDI/VDE 2634 and ISO/DIS 10360-8 guidelines. This considers state of the art capabilities for independent validation of optical non-contact measurement systems suited to the close range measurement of table top sized manufactured or crafted objects.

  11. Surface roughness effects with solid lubricants dispersed in mineral oils

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Goglia, P. R.; Sliney, H. E.

    1983-01-01

    The lubricating effectiveness of solid-lubricant dispersions are investigated in both point and line contacts using surfaces with both random and directional roughness characteristics. Friction and wear data obtained at relatively low speeds and at room temperature, indicate that the existence of solid lubricants such as graphite, MoS2, and PTFE in a plain mineral oil generally will not improve the effectiveness of the oil as a lubricant for such surfaces. Under boundary lubrication conditions, the friction force, as a function of time, initially depends upon the directional roughness properties of the contacting surfaces irrespective of whether the base oil or dispersions are used as lubricants.

  12. Surface roughness effects with solid lubricants dispersed in mineral oils

    NASA Technical Reports Server (NTRS)

    Cusano, C.; Goglia, P. R.; Sliney, H. E.

    1983-01-01

    The lubricating effectiveness of solid-lubricant dispersions are investigated in both point and line contacts using surfaces with both random and directional roughness characteristics. Friction and wear data obtained at relatively low speeds and at room temperature, indicate that the existence of solid lubricants such as graphite, MoS2, and PTFE in a plain mineral oil generally will not improve the effectiveness of the oil as a lubricant for such surfaces. Under boundary lubrication conditions, the friction force, as a function of time, initially depends upon the directional roughness properties of the contacting surfaces irrespective of whether the base oil or dispersions are used as lubricants.

  13. Method for Measuring Changes in Surface Tension on Agar

    PubMed Central

    Weisberg, David S.; Dworkin, Martin

    1983-01-01

    The surface tension of agar surfaces was determined by measuring the contact angles formed by drops of various hydrophobic liquids on the surface and then calculating the composite surface free energy function by solving a series of simultaneous equations derived from these data. This method was used to measure the change in the surface tension of agar produced by the addition of various concentrations of albumin. The resulting curve was typical of the effect of increasing concentrations of surfactants on surface tension. The method was compared with other methods of determining surface tension of solids, and it was concluded that the technique used here provided the most reliable results. PMID:16346273

  14. Lift-Off Instability During the Impact of a Drop on a Solid Surface

    NASA Astrophysics Data System (ADS)

    Rubinstein, Shmuel; Kolinski, John; Mahadevan, L.

    2014-11-01

    We directly measure the rapid spreading dynamics succeeding the impact of a droplet of fluid on a solid, dry surface. Upon impact, the air separating the liquid from the solid surface fails to drain and wetting is delayed as the liquid rapidly spreads outwards over a nanometer thin film of air. We show that the approach of the spreading liquid front toward the surface is unstable and the spreading front lifts off away from the surface. Lift-off ensues well before the liquid contacts the surface, in contrast with prevailing paradigm where lift-off of the liquid is contingent on solid-liquid contact and the formation of a viscous boundary layer. Here I will discuss the dynamics of liquid spreading over a thin film of air and its lift-off away from the surface over a large range of fluid viscosities.

  15. Chemistry and Physics of Solid Surfaces 5

    DTIC Science & Technology

    1984-04-01

    53, 76? (1981); f) B.K. Teo , D.C. Joy (eds.): EXAFS Spectroscopy, Techniques and Appli- cations (Plenum, New York 1981) 10.6 A. Bianconi: Appl. Surf...Meeussen, B.P. Veltman, P. Bennema, C. van Leeuwen , G.H. Gilmer: J. Crystal Growth 24/25, 491 (1974) 13.3 A review of surface roughening and crystal

  16. Hydrodynamic entrapment of bacteria swimming near a solid surface

    NASA Astrophysics Data System (ADS)

    Giacché, Davide; Ishikawa, Takuji; Yamaguchi, Takami

    2010-11-01

    The near-surface motility of bacteria is important in the initial formation of biofilms and in many biomedical applications. The swimming motion of Escherichia coli near a solid surface is investigated both numerically and experimentally. A boundary element method is used to predict the hydrodynamic entrapment of E. coli bacteria, their trajectories, and the minimum separation of the cell from the surface. The numerical results show the existence of a stable swimming distance from the boundary that depends only on the shape of the cell body and the flagellum. The experimental validation of the numerical approach allows one to use the numerical method as a predictive tool to estimate with reasonable accuracy the near-wall motility of swimming bacteria of known geometry. The analysis of the numerical database demonstrated the existence of a correlation between the radius of curvature of the near-wall circular trajectory and the separation gap. Such correlation allows an indirect estimation of either of the two quantities by a direct measure of the other without prior knowledge of the cell geometry. This result may prove extremely important in those biomedical and technical applications in which the near-wall behavior of bacteria is of fundamental importance.

  17. Solid colloids with surface-mobile linkers.

    PubMed

    van der Meulen, Stef A J; Helms, Gesa; Dogterom, Marileen

    2015-06-17

    In this report we review the possibilities of using colloids with surface mobile linkers for the study of colloidal self-assembly processes. A promising route to create systems with mobile linkers is the use of lipid (bi-)layers. These lipid layers can be either used in the form of vesicles or as coatings for hard colloids and emulsion droplets. Inside the lipid bilayers molecules can be inserted via membrane anchors. Due to the fluidity of the lipid bilayer, the anchored molecules remain mobile. The use of different lipid mixtures even allows creating Janus-like particles that exhibit directional bonding if linkers are used which have a preference for a certain lipid phase. In nature mobile linkers can be found e.g. as receptors in cells. Therefore, towards the end of the review, we also briefly address the possibility of using colloids with surface mobile linkers as model systems to mimic cell-cell interactions and cell adhesion processes.

  18. Solid colloids with surface-mobile linkers

    NASA Astrophysics Data System (ADS)

    van der Meulen, Stef A. J.; Helms, Gesa; Dogterom, Marileen

    2015-06-01

    In this report we review the possibilities of using colloids with surface mobile linkers for the study of colloidal self-assembly processes. A promising route to create systems with mobile linkers is the use of lipid (bi-)layers. These lipid layers can be either used in the form of vesicles or as coatings for hard colloids and emulsion droplets. Inside the lipid bilayers molecules can be inserted via membrane anchors. Due to the fluidity of the lipid bilayer, the anchored molecules remain mobile. The use of different lipid mixtures even allows creating Janus-like particles that exhibit directional bonding if linkers are used which have a preference for a certain lipid phase. In nature mobile linkers can be found e.g. as receptors in cells. Therefore, towards the end of the review, we also briefly address the possibility of using colloids with surface mobile linkers as model systems to mimic cell-cell interactions and cell adhesion processes.

  19. Molecules at Solid Surfaces: A Personal Reminiscence

    NASA Astrophysics Data System (ADS)

    Ertl, Gerhard

    2017-05-01

    I was fortunate to start my career in physical chemistry at a time when the development of the ultrahigh vacuum technique and of novel physical methods enabled the study of processes on well-defined surfaces at an atomic scale. These investigations included the mechanisms of heterogeneously catalyzed reactions, such as CO oxidation and ammonia synthesis, and phenomena of spatio-temporal self-organization, as described by the concepts of nonlinear dynamics.

  20. Laser velocimeter measurements of multiphase flow of solids

    NASA Astrophysics Data System (ADS)

    Kadambi, J. R.; Chen, R. C.; Bhunia, S.

    A unique refractive index matched facility for studying solid-liquid multiphase flow has been developed. The refractive index matching of the solid and the liquid allows the use of non-intrusive Laser Doppler Velocimetry (LDV) to measure the solid and the liquid velocities. These measurements will be useful in developing a better understanding of solid-liquid flows, especially solid-liquid and solid-solid interactions. Silica gel and 50 percent sodium iodide solution in water (refractive index approx. 1.443) are used as the refractive index matched solid and liquid respectively. A two color back scatter mode LDV is used for making velocity measurements. Tests were conducted in solid-liquid slurries with volumetric solid concentration levels of 5 percent and 15 percent in the Reynolds number (Re) range of 400 to 9200. Silica gel particles of mean diameter 40 microns were used. Measurements included mapping of the solid and liquid velocities and obtaining the pressure drop data. Signal processing technique utilizing histogram of velocity measurements made at a point and signal amplitude discrimination was successfully used for differentiating between solid and liquid velocities.

  1. Laser velocimeter measurements of multiphase flow of solids

    SciTech Connect

    Kadambi, J.R.; Chen, R.C.; Bhunia, S.

    1989-01-01

    A unique refractive index matched facility for studying solid-liquid multiphase flow has been developed. The refractive index matching of the solid and the liquid allows the use of non-intrusive Laser Doppler Velocimetry (LDV) to measure the solid and the liquid velocities. These measurements will be useful in developing a better understanding of solid-liquid flows, especially solid-liquid and solid-solid interactions. Silica gel and 50% sodium iodide solution in water (refractive index {approx}1.443) are used as the refractive index matched solid and liquid respectively. A two color back scatter mode LDV is used for making velocity measurements. Tests were conducted in solid-liquid slurries with volumetric solid concentration levels of 5% and 15% in the Reynolds number (Re) range of 400 to 9200. Silica gel particles of mean diameter 40 microns were used. Measurements included mapping of the solid and liquid velocities and obtaining the pressure drop data. Signal processing technique utilizing histogram of velocity measurements made at a point and signal amplitude discrimination was successfully used for differentiating between solid and liquid velocities. 34 refs., 61 figs., 5 tabs.

  2. Solid/free-surface juncture boundary layer and wake

    NASA Astrophysics Data System (ADS)

    Longo, J.; Huang, H. P.; Stern, F.

    The Reynolds-averaged flow for a solid/free-surface juncture boundary layer and wake is documented. The three mean-velocity components and five of the Reynolds stresses are measured for a surface-piercing flat plate in a towing tank using a laser-Doppler velocimeter system for both boundary-layer and wake planes in regions close to the free surface. The experimental method is described, including the foil-plate model, laser-Doppler velocimeter system, conditions, and uncertainty analysis. The underlying flow data is in excellent agreement with benchmark data. Inner (near the plate and wake centerplane and below the free surface) and outer (near the free surface) regions of high streamwise vorticity of opposite sign are observed, which transport, respectively, high mean velocity and low turbulence from the outer to the inner and low mean velocity and high turbulence from the inner to the outer portions of the boundary layer and wake. For the wake, the inner region of vorticity is relatively weak. The physical mechanism for the streamwise vorticity is analyzed with regard to the Reynolds-averaged streamwise vorticity equation. The anisotropy of the crossplane normal Reynolds stresses closely correlates with the vorticity and, additionally, indicates similarity, i.e., its nature is such that it only depends on the proximity to the plate and free surface boundaries or wake centerplane symmetry plane. Free-surface effects on the Reynolds stresses are analyzed with regard to the behavior close to the free surface of the turbulent kinetic energy and the normal components of the anisotropy tensor and the anisotropy invariants. Close to the free surface, the turbulent kinetic energy is nearly constant and increases for the inner and outer portions, respectively, of the boundary layer and wake and the normal components of the anisotropy tensor and the anisotropy invariants roughly correspond to the limiting values for two-component turbulence. The similarities and

  3. Fluoroalkylated Silicon-Containing Surfaces - Estimation of Solid Surface Energy

    DTIC Science & Technology

    2010-10-20

    acetone, chloroform and dodecane or diiodomethane, dimethyl sulfoxide and water. 3 SYNOPSIS TOC KEYWORDS Superhydrophobicity ...surfaces that are not wetted by liquid droplets, i. e. superhydrophobic ,1-4 oleophobic,5-15 hygrophobic,16 omniphobic7, 12 surfaces. These surfaces have...potential applications in oil-water separation, non-wettable textiles,2, 3, 6, 8, 9, 14, 15 and fingerprint/smudge resistant touch-screen devices

  4. Fundamental Interactions of Water with Solid Surfaces

    DTIC Science & Technology

    1990-07-20

    of Surface General Motors Research Labs Solvation Effects in Electrochemistry" 11:30 a.m. Discussion 12:30 a.m. Lunch Evening Session: Interaction of...Chemical Dept. Cu(11l0 and Pt(111): the Formation General Motors Research Labs of H 30 ?" 30500 Mound Road Warren, MI 48090-9055 Prof. J. Michael White...07974 Montreal, Oueoec H3C 3S7 CANADA Fisher. Gaien Bry 301 General Motors Research Laos. Physica) Chemistry Dept 30500 Mound Road Warren. 1-1• ý 4H1. 9

  5. Heat transfer between elastic solids with randomly rough surfaces.

    PubMed

    Volokitin, A I; Lorenz, B; Persson, B N J

    2010-01-01

    We study the heat transfer between elastic solids with randomly rough surfaces.We include both the heat transfer from the area of real contact, and the heat transfer between the surfaces in the non-contact regions.We apply a recently developed contact mechanics theory, which accounts for the hierarchical nature of the contact between solids with roughness on many different length scales. For elastic contact, at the highest (atomic) resolution the area of real contact typically consists of atomic (nanometer) sized regions, and we discuss the implications of this for the heat transfer. For solids with very smooth surfaces, as is typical in many modern engineering applications, the interfacial separation in the non-contact regions will be very small, and for this case we show the importance of the radiative heat transfer associated with the evanescent electromagnetic waves which exist outside of all bodies.

  6. A nonmonotonic dependence of the contact angles on the surface polarity for a model solid surface.

    PubMed

    Qi, Chonghai; Zhou, Bo; Wang, Chunlei; Zheng, Yujun; Fang, Haiping

    2017-03-01

    Based on molecular dynamics simulations, we found a nonmonotonic relationship between the contact angle of water droplets and the surface polarity on a solid surface with specific hexagonal charge patterns at room temperature. The contact angle firstly decreases and then increases as polarity (denoted as charge q) increases from 0 e to 1.0 e with a vertex value of q = 0.5 e. We observed a different wetting behavior for a water droplet on a conventional nonwetted solid surface when q ≤ 0.5 e, and a water droplet on an ordered water monolayer adsorbed on a highly polar solid surface when q > 0.5 e. The solid-water interaction, density of water, hydrogen bonds, and water structures were analyzed. Remarkably, there was up to six times difference in the solid-water interactions despite the same value of the apparent contact angle values.

  7. Terraced spreading of simple liquids on solid surfaces

    NASA Technical Reports Server (NTRS)

    Yang, Ju-Xing; Koplik, Joel; Banavar, Jayanth R.

    1992-01-01

    We have studied the spreading of liquid drops on a solid surface by molecular-dynamics simulations of coexisting three-phase Lennard-Jones systems of liquid, vapor, and solid. We consider both spherically symmetric atoms and diatomic molecules, and a range of interaction strengths. As the attraction between liquid and solid increases we observe a smooth transition in spreading regimes, from partial to complete to terraced wetting. In the terraced case, where distinct monomolecular layers spread with different velocities, the layers are ordered but not solid, with substantial molecular diffusion both within and between layers. The quantitative behavior resembles recent experimental findings, but the detailed dynamics differ. In particular, the layers exhibit an unusual spreading law, where their radii vary in time as R-squared approximately equal to log10t, which disagrees with experiments on polymeric liquids as well as recent calculations.

  8. Terraced spreading of simple liquids on solid surfaces

    NASA Technical Reports Server (NTRS)

    Yang, Ju-Xing; Koplik, Joel; Banavar, Jayanth R.

    1992-01-01

    We have studied the spreading of liquid drops on a solid surface by molecular-dynamics simulations of coexisting three-phase Lennard-Jones systems of liquid, vapor, and solid. We consider both spherically symmetric atoms and diatomic molecules, and a range of interaction strengths. As the attraction between liquid and solid increases we observe a smooth transition in spreading regimes, from partial to complete to terraced wetting. In the terraced case, where distinct monomolecular layers spread with different velocities, the layers are ordered but not solid, with substantial molecular diffusion both within and between layers. The quantitative behavior resembles recent experimental findings, but the detailed dynamics differ. In particular, the layers exhibit an unusual spreading law, where their radii vary in time as R-squared approximately equal to log10t, which disagrees with experiments on polymeric liquids as well as recent calculations.

  9. Surface-environment effects in spin crossover solids

    NASA Astrophysics Data System (ADS)

    Gudyma, Iu.; Maksymov, A.

    2017-06-01

    The impact of surface effects on thermal induced spin crossover phenomenon is a subject of a broad and current interest. Using the modified Ising-like model of spin crossover solids with the ligand field as function of the molecule' positions and random component on surface by means of Metropolis Monte Carlo algorithm the thermal spin transition curves were calculated. The analysis of spin configuration during transition gives a general idea about contribution of molecules from the surface and inside the lattice into resulting magnetization of the systems. The behavior of hysteresis loop for various surface coupling and fluctuations strength has been described.

  10. Surface segregation in Ni(W) solid solution

    NASA Astrophysics Data System (ADS)

    Sagie, Eyal; Polak, Micha

    2000-07-01

    The surface composition of Ni-7%W solid solution equilibrated under UHV in the range 750-1100 K was determined by means of quantitative Auger electron spectroscopy. Only part of the excess tungsten accumulated at the sputter-cleaned surface dissolved upon subsequent annealing, and from the temperature dependence of the residual W equilibrium concentration, quantified for two different in-depth distribution models, segregation enthalpies and excess entropies are derived. The observed tungsten surface segregation tendency indicates dominance of elastic strain release over weakened interatomic bonding driving forces in this solid solution. Tungsten segregation levels are relatively low because of the small net energetic driving force, and due to a suppressing excess entropy effect. Adsorption of oxygen on the alloy surfaces enhances W segregation at elevated temperatures due to preferential WO interactions.

  11. Measuring the Valence of Nanocrystal Surfaces

    SciTech Connect

    Owen, Jonathan Scharle

    2016-11-30

    The goal of this project is to understand and control the interplay between nanocrystal stoichiometry, surface ligand binding and exchange, and the optoelectronic properties of semiconductor nanocrystals in solution and in thin solid films. We pursued three research directions with this goal in mind: 1) We characterized nanocrystal stoichiometry and its influence on the binding of L-type and X-type ligands, including the thermodynamics of binding and the kinetics of ligand exchange. 2) We developed a quantitative understanding of the relationship between surface ligand passivation and photoluminescence quantum yield. 3) We developed methods to replace the organic ligands on the nanocrystal with halide ligands and controllably deposit these nanocrystals into thin films, where electrical measurements were used to investigate the electrical transport and internanocrystal electronic coupling.

  12. Theory of flame spread above solids. [fuel exothermic surface reactions

    NASA Technical Reports Server (NTRS)

    Sirignano, W. A.

    1974-01-01

    A theory for flame spread above a solid fuel is presented. The special case is considered whereby the oxidation is an exothermic surface reaction. The spreading rate is predicted as a function of the thermochemical properties, fuel-bed thickness, and convective velocity. Also, the theory predicts temperature, mass fraction, and heat flux as a function of position.

  13. Solid stress and elastic energy as measures of tumour mechanopathology

    PubMed Central

    Nia, Hadi T.; Liu, Hao; Seano, Giorgio; Datta, Meenal; Jones, Dennis; Rahbari, Nuh; Incio, Joao; Chauhan, Vikash P.; Jung, Keehoon; Martin, John D.; Askoxylakis, Vasileios; Padera, Timothy P.; Fukumura, Dai; Boucher, Yves; Hornicek, Francis J.; Grodzinsky, Alan J.; Baish, James W.; Munn, Lance L.

    2017-01-01

    Solid stress and tissue stiffness affect tumour growth, invasion, metastasis and treatment. Unlike stiffness, which can be precisely mapped in tumours, the measurement of solid stresses is challenging. Here, we show that two-dimensional spatial mappings of solid stress and the resulting elastic energy in excised or in situ tumours with arbitrary shapes and wide size ranges can be obtained via three distinct and quantitative techniques that rely on the measurement of tissue displacement after disruption of the confining structures. Application of these methods in models of primary tumours and metastasis revealed that: (i) solid stress depends on both cancer cells and their microenvironment; (ii) solid stress increases with tumour size; and (iii) mechanical confinement by the surrounding tissue significantly contributes to intratumoural solid stress. Further study of the genesis and consequences of solid stress, facilitated by the engineering principles presented here, may lead to significant discoveries and new therapies. PMID:28966873

  14. Solid stress and elastic energy as measures of tumour mechanopathology.

    PubMed

    Nia, Hadi T; Liu, Hao; Seano, Giorgio; Datta, Meenal; Jones, Dennis; Rahbari, Nuh; Incio, Joao; Chauhan, Vikash P; Jung, Keehoon; Martin, John D; Askoxylakis, Vasileios; Padera, Timothy P; Fukumura, Dai; Boucher, Yves; Hornicek, Francis J; Grodzinsky, Alan J; Baish, James W; Munn, Lance L; Jain, Rakesh K

    2016-01-01

    Solid stress and tissue stiffness affect tumour growth, invasion, metastasis and treatment. Unlike stiffness, which can be precisely mapped in tumours, the measurement of solid stresses is challenging. Here, we show that two-dimensional spatial mappings of solid stress and the resulting elastic energy in excised or in situ tumours with arbitrary shapes and wide size ranges can be obtained via three distinct and quantitative techniques that rely on the measurement of tissue displacement after disruption of the confining structures. Application of these methods in models of primary tumours and metastasis revealed that: (i) solid stress depends on both cancer cells and their microenvironment; (ii) solid stress increases with tumour size; and (iii) mechanical confinement by the surrounding tissue significantly contributes to intratumoural solid stress. Further study of the genesis and consequences of solid stress, facilitated by the engineering principles presented here, may lead to significant discoveries and new therapies.

  15. Surface flow measurements from drones

    NASA Astrophysics Data System (ADS)

    Tauro, Flavia; Porfiri, Maurizio; Grimaldi, Salvatore

    2016-09-01

    Drones are transforming the way we sense and interact with the environment. However, despite their increased capabilities, the use of drones in geophysical sciences usually focuses on image acquisition for generating high-resolution maps. Motivated by the increasing demand for innovative and high performance geophysical observational methodologies, we posit the integration of drone technology and optical sensing toward a quantitative characterization of surface flow phenomena. We demonstrate that a recreational drone can be used to yield accurate surface flow maps of sub-meter water bodies. Specifically, drone's vibrations do not hinder surface flow observations, and velocity measurements are in agreement with traditional techniques. This first instance of quantitative water flow sensing from a flying drone paves the way to novel observations of the environment.

  16. Optical measurements on contaminated surfaces

    NASA Technical Reports Server (NTRS)

    Bonham, T. E.; Schmitt, R. J.; Linford, R. M. F.

    1975-01-01

    A bidirectional reflectometer system was developed for in situ measurements of the changes in spectral reflectance of surfaces contaminated with films of organic materials. The system permits experiments with films of controlled thickness in an environment that simulates the thermal, radiation, and vacuum conditions of space. The mechanical and optical construction of the reflectometer are discussed in detail, and actual data curves are used to illustrate its operation and performance.

  17. Spikes removal in surface measurement

    NASA Astrophysics Data System (ADS)

    Podulka, P.; Pawlus, P.; Dobrzański, P.; Lenart, A.

    2014-03-01

    Several cylinder surface topographies made from grey cast iron were measured by Talysurf CCI white light interferometer with and without use of spikes filter. They were plateau honed by abrasive stones. Measured area was 3.3 mm × 3.3 mm, height resolution was 0.01 nm. The forms were eliminated using polynomial of the 3rd degree. After it, spikes were removed using four methods. These approaches were compared. Parameters of the smaller and highest sensitivity on spikes presence were selected.

  18. Interferometric measurement of functional surfaces

    NASA Astrophysics Data System (ADS)

    Lehmann, Peter; Xie, Weichang; Kühnhold, Peter; Niehues, Jan

    2013-06-01

    Increasing capabilities in precision manufacturing and micro technology are accompanied by increasing demands of high precision industrial metrology systems. Especially for measuring functional surfaces, areal optical principles are widely used. If, in addition, nanometer height resolution is needed interferometers seem to be the most promising instruments. First, this contribution focuses on the transfer characteristics of white-light interferometers with microscopic field of view. In general, microscopic instruments suffer from their limited lateral resolution capabilities. Hence, the transfer function of these instruments is typically assumed to show a linear low-pass characteristic. We studied the transfer characteristics of white-light interferometers by theoretical simulations and experimental investigations. Our results show that in most practical cases these instruments behave nonlinear, i.e. the output surface profile cannot be obtained from the input profile by a simple linear filter operation. Although they are well-established, there are some further limitations of white-light interferometers if they are used to measure micro or even sub-microstructures. If edges, steeper slopes or abrupt slope changes are present on a measuring object characteristic errors such as batwings occur. Furthermore, a high effort concerning the correction of chromatic aberration is necessary in order to avoid dispersion effects. Otherwise, there will be systematic discrepancies between profiles obtained from evaluation of the coherence peak and those resulting from the phase of the interference signals. These may lead to 2π phase jumps if the fringe order is obtained from the position of the coherence peak. Finally, measurement artifacts may also result if the measured micro-structure shows discontinuities of the surface slope. This contribution analyses the different phenomena and discusses approaches to overcome existing limitations.

  19. Thin films of solid electrolytes and studies of their surface

    NASA Astrophysics Data System (ADS)

    Pan, Xiaoren; Gu, Zhi X.

    1991-11-01

    Much research work has been done on the materials of solid electrolytes and their applications. Solid electrolytes or fast ionic conductors are generally used in solid state batteries and solid state ionic devices. In the utilization of solid electrolytes, thin film forms have practical advantages. They will make the devices and batteries miniaturization which is particularly important for certain applications such as microelectronic devices, space programs, and integrated circuits of self-contained power. So preparation of thin films of solid electrolytes and studies of their surfaces are significant. There has been interest in the properties of amorphous ionic conductors, as glasses have acknowledged advantages over crystalline electrolytes, including physical isotropy, the absence of grain boundaries, and continuously-variable composition. Furthermore, many glasses based on silver halides have conductivities as high as 10 Scm-1 at room temperature. So we have chosen the quaternary system AgI-Ag2O-P2O5-B2O3 as the basic materials, prepared thin films, studied their properties, and constructed thin film electrolytic batteries.

  20. Surface tension and the mechanics of liquid inclusions in compliant solids

    NASA Astrophysics Data System (ADS)

    Style, Robert W.; Wettlaufer, John S.; Dufresne, Eric R.

    Eshelby's theory of inclusions has wide-reaching implications across the mechanics of materials and structures including the theories of composites, fracture, and plasticity. However, it does not include the effects of surface stress, which has recently been shown to control many processes in soft materials such as gels, elastomers and biological tissue. To extend Eshelby's theory of inclusions to soft materials, we consider liquid inclusions within an isotropic, compressible, linear-elastic solid. We solve for the displacement and stress fields around individual stretched inclusions, accounting for the bulk elasticity of the solid and the surface tension (\\textit{i.e.} isotropic strain-independent surface stress) of the solid-liquid interface. Surface tension significantly alters the inclusion's shape and stiffness as well as its near- and far-field stress fields. These phenomenon depend strongly on the ratio of inclusion radius, $R$, to an elastocapillary length, $L$. Surface tension is significant whenever inclusions are smaller than $100L$. While Eshelby theory predicts that liquid inclusions generically reduce the stiffness of an elastic solid, our results show that liquid inclusions can actually stiffen a solid when $R<3L/2$. Intriguingly, surface tension cloaks the far-field signature of liquid inclusions when $R=3L/2$. These results are have far-reaching applications from measuring local stresses in biological tissue, to determining the failure strength of soft composites.

  1. Surface tension and the mechanics of liquid inclusions in compliant solids.

    PubMed

    Style, Robert W; Wettlaufer, John S; Dufresne, Eric R

    2015-01-28

    Eshelby's theory of inclusions has wide-reaching implications across the mechanics of materials and structures including the theories of composites, fracture, and plasticity. However, it does not include the effects of surface stress, which has recently been shown to control many processes in soft materials such as gels, elastomers and biological tissue. To extend Eshelby's theory of inclusions to soft materials, we consider liquid inclusions within an isotropic, compressible, linear-elastic solid. We solve for the displacement and stress fields around individual stretched inclusions, accounting for the bulk elasticity of the solid and the surface tension (i.e. isotropic strain-independent surface stress) of the solid-liquid interface. Surface tension significantly alters the inclusion's shape and stiffness as well as its near- and far-field stress fields. These phenomena depend strongly on the ratio of the inclusion radius, R, to an elastocapillary length, L. Surface tension is significant whenever inclusions are smaller than 100L. While Eshelby theory predicts that liquid inclusions generically reduce the stiffness of an elastic solid, our results show that liquid inclusions can actually stiffen a solid when R<3L/2. Intriguingly, surface tension cloaks the far-field signature of liquid inclusions when R=3L/2. These results are have far-reaching applications from measuring local stresses in biological tissue, to determining the failure strength of soft composites.

  2. Surface and defect morphologies in anisotropic elastic and piezoelectric solids

    SciTech Connect

    Gao, Huajian; Barnett, D.M.

    1996-12-31

    The authors investigate issues related to the equilibrium and stability of surface and line defect morphologies in both piezoelectric and anisotropic elastic solids. Following their previous efforts which established that mechanical stresses in purely elastic solids can promote instability of an initially flat surface with respect to surface roughening, they show that the (initially flat) interface between two dissimilar piezoelectric solids can be unstable when subjected to coupled electromechanical loading. Quite recent cross-sectional observations of electrodeposited thin films by Japanese and British researchers provide experimental confirmation of these predictions. The authors also investigate the occurrence of equilibrium arrangements (zero Peach-Koehler force arrangements) of line defects (dislocations) in anisotropic elastic crystals in the absence of externally applied stresses. Contrary to prevailing opinion, equilibrium arrangements of dislocations under no externally applied stresses appear to be the rule rather than the exception. The existence of such {open_quotes}zero stress arrangements{close_quotes} is fundamental to developing micromechanical models of plastically deforming solids.

  3. Supramolecular architectures for the functionalization of solid surfaces.

    PubMed

    Knoll, W; Liley, M; Piscevic, D; Spinke, J; Tarlov, M J

    1997-01-01

    Surface plasmon optical techniques are described as sensitive tools that allow for the on-line characterization of supramolecular biofunctional architectures at solid/solution interfaces. After a short introduction into the fundamentals of surface plasmon optics the observation of the build up of a functional bio-interface by the self-assembly process of long chain thiolates at an Au surface is described. Criteria are developed for tailoring the SAM architectures optimized for maximum protein binding from solution by specific bio-recognition reactions. SPM is employed to image the selective binding of streptavidin to a functionalized SAM laterally patterned by UV-photolithographic techniques.

  4. Surface electron acceleration in relativistic laser-solid interactions

    NASA Astrophysics Data System (ADS)

    Chen, Min; Sheng, Zheng-Ming; Zheng, Jun; Ma, Yan-Yun; Bari, Muhammad; Li, Yu-Tong; Zhang, Jie

    2006-04-01

    Under the grazing incidence of a relativistic intense laser pulse onto a solid target, two-dimensional particle-in-cell simulations show that intense quasistatic magnetic and electric fields are generated near the front target surface during the interaction. Some electrons are confined in these quasistatic fields and move along the target surface with betatron oscillations. When this oscillating frequency is close to the laser frequency in the particle frame, these electrons can be accelerated significantly in the reflected laser field, similar to the inverse free-electron-laser acceleration. An analytical model for this surface betatron acceleration is proposed.

  5. Bulk and surface acoustic waves in solid-fluid Fibonacci layered materials.

    PubMed

    Quotane, I; El Boudouti, E H; Djafari-Rouhani, B; El Hassouani, Y; Velasco, V R

    2015-08-01

    We study theoretically the propagation and localization of acoustic waves in quasi-periodic structures made of solid and fluid layers arranged according to a Fibonacci sequence. We consider two types of structures: either a given Fibonacci sequence or a periodic repetition of a given sequence called Fibonacci superlattice. Various properties of these systems such as: the scaling law and the self-similarity of the transmission spectra or the power law behavior of the measure of the energy spectrum have been highlighted for waves of sagittal polarization in normal and oblique incidence. In addition to the allowed modes which propagate along the system, we study surface modes induced by the surface of the Fibonacci superlattice. In comparison with solid-solid layered structures, the solid-fluid systems exhibit transmission zeros which can break the self-similarity behavior in the transmission spectra for a given sequence or induce additional gaps other than Bragg gaps in a periodic structure.

  6. Microwave properties of solid CO2. [for Mars surface study

    NASA Technical Reports Server (NTRS)

    Simpson, R. A.; Howard, H. T.; Fair, B. C.

    1980-01-01

    Measurements over the range of 2.2 to 12.0 GHz show that CO2 snow is a slightly lossy dielectric whose constant varies with density following the Rayleigh formula to 1.27 g/cu cm. It is independent of frequency and does not vary with temperature in the 113 to 183 K range; frequency independence and agreement with the Rayleigh fit are obtained from measurements on dry block ice. The dielectric constant of solid CO2 in block form is lower than that of solid water ice or solid rock; in powder form, the constant for CO2 is also lower than that of H2O (snow) or soils. These measurements may be useful in limiting the interpretations of the Viking radio reflection experiment; a radio value of 3.0 for the dielectric constant near the North Pole would be strong evidence against the presence of cm thicknesses of CO2 in that region.

  7. Microwave properties of solid CO2. [for Mars surface study

    NASA Technical Reports Server (NTRS)

    Simpson, R. A.; Howard, H. T.; Fair, B. C.

    1980-01-01

    Measurements over the range of 2.2 to 12.0 GHz show that CO2 snow is a slightly lossy dielectric whose constant varies with density following the Rayleigh formula to 1.27 g/cu cm. It is independent of frequency and does not vary with temperature in the 113 to 183 K range; frequency independence and agreement with the Rayleigh fit are obtained from measurements on dry block ice. The dielectric constant of solid CO2 in block form is lower than that of solid water ice or solid rock; in powder form, the constant for CO2 is also lower than that of H2O (snow) or soils. These measurements may be useful in limiting the interpretations of the Viking radio reflection experiment; a radio value of 3.0 for the dielectric constant near the North Pole would be strong evidence against the presence of cm thicknesses of CO2 in that region.

  8. Laboratory evaluation of microwave Doppler velocimeter for solid flow measurements

    NASA Astrophysics Data System (ADS)

    Wu, Z.; Wang, H. G.; Isa, M.; Liu, C. G.

    2014-04-01

    Pneumatic-conveyed solid flows are common in many industrial processes. The flow speed may be high and varying. The density of solids may also change with time. The mass flow rate is usually difficult to quantify for such multphase flows. On the other hand, microwave Doppler radar has been used as a device for velocity measurement or motion detection. It would be feasible to use such a device for solid flow measurements. In this paper, the principle of using microwave Doppler radar for such an application is investigated. Experimental results obtained using a microwave Doppler velocimeter for different types of solid flows in a laboratory environment are presented.

  9. Long Term Surface Salinity Measurements

    NASA Technical Reports Server (NTRS)

    Schmitt, Raymond W.; Brown, Neil L.

    2005-01-01

    Our long-term goal is to establish a reliable system for monitoring surface salinity around the global ocean. Salinity is a strong indicator of the freshwater cycle and has a great influence on upper ocean stratification. Global salinity measurements have potential to improve climate forecasts if an observation system can be developed. This project is developing a new internal field conductivity cell that can be protected from biological fouling for two years. Combined with a temperature sensor, this foul-proof cell can be deployed widely on surface drifters. A reliable in-situ network of surface salinity sensors will be an important adjunct to the salinity sensing satellite AQUARIUS to be deployed by NASA in 2009. A new internal-field conductivity cell has been developed by N Brown, along with new electronics. This sensor system has been combined with a temperature sensor to make a conductivity - temperature (UT) sensor suitable for deployment on drifters. The basic sensor concepts have been proven on a high resolution CTD. A simpler (lower cost) circuit has been built for this application. A protection mechanism for the conductivity cell that includes antifouling protection has also been designed and built. Mr. A.Walsh of our commercial partner E-Paint has designed and delivered time-release formulations of antifoulants for our application. Mr. G. Williams of partner Clearwater Instrumentation advised on power and communication issues and supplied surface drifters for testing.

  10. Reflectance measurements from particulate surfaces

    NASA Astrophysics Data System (ADS)

    Peltoniemi, J.; Gritsevich, M.; Hakala, T.; Penttilä, A.; Eskelinen, J.; Dagsson-Waldhauserova, P.; Arnalds, O.; Guirado, D.; Muinonen, K.

    2014-07-01

    Asteroids consists of, e.g., metals and rocky materials, and comets consist of, e.g., icy and rocky materials and dust. Their surfaces can be covered by small particles. To certain extent, these surfaces can resemble some natural or artificial surfaces on the Earth, such as snow layers, sand, gravels, or silt. By measuring the reflectance from such surfaces, one can gain better understanding on how to interpret astronomical observations of asteroids and comets. Even if not completely analogous, these samples and measurements provide a strict test bed for the scattering models applied to interpret observations of small Solar System bodies. FIGIFIGO (Finnish Geodetic Institute's Field Gonio-spectro-polari- radiometer) can measure the bidirectional reflectance factor (BRF) of surface targets of a diameter of around 10 cm, in a selected angular range and resolution, in the spectral range of 400-2400 nm, at about 10-nm resolution, including linear polarisation (Stokes I, Q, and U, or reflection coefficient matrix elements R_{11}, R_{12}, and R_{13}). Using FIGIFIGO, over 500 samples have been measured over the past years, including over 100 snow samples and almost 100 samples resembling sand, silt, soil, dust, or gravel. For planetary studies, especially interesting are dark volcanic ash and silt samples from Eyjafjallajökull and Grímsvönt eruptions. These have been measured loose and compressed, smooth and rough, purely and deposited on snow. Further single-scattering measurements using the Granada setup and measurements using the Univ. Helsinki integrating sphere complement the picture. Generally, we have observed that the reflectance from volcanic materials behaves mostly as expected and modelled. BRF shows typical bowl shape with strong phase-angle dependence. Spectral features are smooth, with slight angular dependence. Polarisation depends strongly on the phase angle, weaker on other angles defining the scattering geometry, and smoothly on the wavelength. There

  11. Three-dimensional microscopic deformation measurements on cellular solids.

    PubMed

    Genovese, K

    2016-07-01

    The increasing interest in small-scale problems demands novel experimental protocols providing dense sets of 3D deformation data of complex shaped microstructures. Obtaining such information is particularly significant for the study of natural and engineered cellular solids for which experimental data collected at macro scale and describing the global mechanical response provide only limited information on their function/structure relationship. Cellular solids, in fact, due their superior mechanical performances to a unique arrangement of the bulk material properties (i.e. anisotropy and heterogeneity) and cell structural features (i.e. pores shape, size and distribution) at the micro- and nano-scales. To address the need for full-field experimental data down to the cell level, this paper proposes a single-camera stereo-Digital Image Correlation (DIC) system that makes use of a wedge prism in series to a telecentric lens for performing surface shape and deformation measurements on microstructures in three dimensions. Although the system possesses a limited measurement volume (FOV~2.8×4.3mm(2), error-free DOF ~1mm), large surface areas of cellular samples can be accurately covered by employing a sequential image capturing scheme followed by an optimization-based mosaicing procedure. The basic principles of the proposed method together with the results of the benchmarking of its metrological performances and error analysis are here reported and discussed in detail. Finally, the potential utility of this method is illustrated with micro-resolution three-dimensional measurements on a 3D printed honeycomb and on a block sample of a Luffa sponge under compression. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Residual Silicone Detection. [external tank and solid rocket booster surfaces

    NASA Technical Reports Server (NTRS)

    Smith, T.

    1980-01-01

    Both photoelectron emission and ellipsometry proved successful in detecting silicone contamination on unpainted and epoxy painted metal surfaces such as those of the external tank and the solid rocket booster. Great success was achieved using photoelectron emission (PEE). Panels were deliberately contaminated to controlled levels and then mapped with PEE to reveal the areas and levels that were contaminated. The panels were then tested with regard to adhesive properties. Tapes were bonded over the contaminated and uncontaminated regions and the peel force was measured, or the contaminated panels were bonded (with CPR 483 foam) to uncontaminated panels and made into lap shear specimens. Other panels were bonded and made into wedge specimens for hydrothermal stress endurance tests. Strong adhesion resulted if the PEE signal fell within an acceptance window, but was poor outside the acceptance window. A prototype instrument is being prepared which can automatically be scanned over the external liquid hydrogen tank and identify those regions that are contaminated and will cause bond degradation.

  13. Fermi surface measurements of lutetium

    NASA Astrophysics Data System (ADS)

    Johanson, W. R.; Crabtree, G. W.; Schmidt, F. A.

    1982-03-01

    We report de Haas-van Alphen (dHvA) measurements of the Fermi surface of lutetium at temperatures down to 0.3 K and in fields up to 150 kG in the (101¯0) and (112¯0) planes. Lutetium, having a filled 4f shell, serves as a nonmagnetic prototype of the structurally similar (hcp), trivalent, heavy rare earths from Gd to Tm. No complete frequency branches were observed, indicating that there are no closed pieces of surface. We observed all but one orbit predicted by relativistic-augmented-plane wave (RAPW) calculations of Keeton and Loucks, and the data support a geometry that is in good qualitative agreement with the existence of nested open electron and hole sheets.

  14. Fermi surface measurements of lutetium

    SciTech Connect

    Johanson, W.R.; Crabtree, G.W.; Schmidt, F.A.

    1982-03-01

    We report de Haas-van Alphen (dHvA) measurements of the Fermi surface of lutetium at temperatures down to 0.3 K and in fields up to 150 kG in the (1010) and (1120) planes. Lutetium, having a filled 4f shell, serves as a nonmagnetic prototype of the structurally similar (hcp), trivalent, heavy rare earths from Gd to Tm. No complete frequency branches were observed, indicating that there are no closed pieces of surface. We observed all but one orbit predicted by relativistic-augmented-plane wave (RAPW) calculations of Keeton and Loucks, and the data support a geometry that is in good qualitative agreement with the existence of nested open electron and hole sheets.

  15. Fermi surface measurements of lutetium

    SciTech Connect

    Johanson, W.R.; Crabtree, G.W.; Schmidt, F.A.

    1982-01-01

    We report de Haas-van Alphen (dHvA) measurements of the Fermi surface of Lutetium at temperatures down to .3K and in fields up to 150 kG in the (1010) and (1120) planes. Lutetium, having a filled 4f shell, serves as a non-magnetic prototype of the structurally similar (hcp), trivalent, heavy rare-earths from Gd to Tm. No complete frequency branches were observed, indicating that there are no closed pieces of surface. We observed all but one orbit predicted by relativistic-augmented-plane wave (RAPW) calculations of Keeton and Loucks, and the data support a geometry that is in good qualitative agreement with the existence of nested open electron and hole sheets.

  16. Dissolved-solids transport in surface water of the Muddy Creek Basin, Utah

    USGS Publications Warehouse

    Gerner, Steven J.

    2008-01-01

    Muddy Creek is located in the southeastern part of central Utah and is a tributary of the Dirty Devil River, which, in turn, is a tributary of the Colorado River. Dissolved solids transported from the Muddy Creek Basin may be stored in the lower Dirty Devil River Basin, but are eventually discharged to the Colorado River and impact downstream water users. This study used selected dissolved-solids measurements made by various local, State, and Federal agencies from the 1970s through 2006, and additional dissolved-solids data that were collected by the U.S. Geological Survey during April 2004 through November 2006, to compute dissolved-solids loads, determine the distribution of dissolved-solids concentrations, and identify trends in dissolved-solids concentration in surface water of the Muddy Creek Basin. The dissolved-solids concentration values measured in water samples collected from Muddy Creek during April 2004 through October 2006 ranged from 385 milligrams per liter (mg/L) to 5,950 mg/L. The highest dissolved-solids concentration values measured in the study area were in water samples collected at sites in South Salt Wash (27,000 mg/L) and Salt Wash (4,940 to 6,780 mg/L). The mean annual dissolved-solids load in Muddy Creek for the periods October 1976 to September 1980 and October 2005 to September 2006 was smallest at a site near the headwaters (9,670 tons per year [tons/yr]) and largest at a site at the mouth (68,700 tons/yr). For this period, the mean annual yield of dissolved solids from the Muddy Creek Basin was 44 tons per square mile. During October 2005 to September 2006, direct runoff transported as much as 45 percent of the annual dissolved-solids load at the mouth of Muddy Creek. A storm that occurred during October 5?7, 2006 resulted in a peak streamflow at the mouth of Muddy Creek of 7,150 cubic feet per second (ft3/s) and the transport of an estimated 35,000 tons of dissolved solids, which is about 51 percent of the average annual dissolved-solids

  17. Tuning the surface wettability of carbon nanotube carpets in multiscale hierarchical solids

    NASA Astrophysics Data System (ADS)

    Karumuri, Anil K.; He, Lvmeng; Mukhopadhyay, Sharmila M.

    2015-02-01

    An attractive approach of increasing functionality of solid surfaces is to create hierarchical multiscale morphology by attaching tailored carpet-like arrays of Carbon nanotubes (CNT) on them. Such surfaces offer fractal morphology along with unprecedented increase in specific surface areas, and significantly boost the potency of porous materials used in surface-active applications. However, full utilization of these structures will require intimate interaction between the solid surface and its environmental fluid. CNT arrays tend to be hydrophobic, which limit their effectiveness in aqueous environments. In this research, we investigated two different surface modifications methods to induce hydrophilic property to CNT nano-carpets on graphitic substrates: dry oxygen plasma treatment and wet sol-gel oxide coating. Structure, morphology, composition and chemistry of these multiscale surfaces have been related to wettability and water flow properties. Plasma oxygen treatments did not alter the surface morphology, but induced temporary wettability, that could be reversed by heat treatment. On the other hand, sol-gel treatment permanently coated the nanotubes with a strongly bonded layer of amorphous SiO2. This coating imparts permanent alterations in surface chemistry, contact angle, wettability and water flow. Porous carbon foams were coated with CNT arrays and their water permeability measured before and after sol-gel silica coating. The hydrophilic coating was seen to increase flow rate and reduce pressure build-up. These results have important implications on all devices that utilize surface activity of porous solids, such as catalytic membranes, antimicrobial filters, and microfluidic sensors.

  18. Three electrode measurements on solid electrolytes

    SciTech Connect

    Pham, A.Q.; Glass, R.S.

    1995-12-01

    AC impedance spectroscopy and chronopotentiometry have been used to study solid-state ionic conductors. Results obtained using three electrodes are compared to those using a two-electrode configuration. The uncompensated resistance was shown to depend strongly on the geometric placement of the electrodes. The optimal configuration for minimized uncompensated resistance effects is similar to the Luggin capillary arrangement in the liquid phase. The effect of non-negligible geometric capacitance on interpretation of results is discussed.

  19. Method for measuring surface temperature

    DOEpatents

    Baker, Gary A.; Baker, Sheila N.; McCleskey, T. Mark

    2009-07-28

    The present invention relates to a method for measuring a surface temperature using is a fluorescent temperature sensor or optical thermometer. The sensor includes a solution of 1,3-bis(1-pyrenyl)propane within a 1-butyl-1-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid solvent. The 1,3-bis(1-pyrenyl)propane remains unassociated when in the ground state while in solution. When subjected to UV light, an excited state is produced that exists in equilibrium with an excimer. The position of the equilibrium between the two excited states is temperature dependent.

  20. Highly efficient solid state catalysis by reconstructed (001) Ceria surface

    PubMed Central

    Solovyov, Vyacheslav F.; Ozaki, Toshinori; Atrei, Andrea; Wu, Lijun; Al-Mahboob, Abdullah; Sadowski, Jerzy T.; Tong, Xiao; Nykypanchuk, Dmytro; Li, Qiang

    2014-01-01

    Substrate engineering is a key factor in the synthesis of new complex materials. The substrate surface has to be conditioned in order to minimize the energy threshold for the formation of the desired phase or to enhance the catalytic activity of the substrate. The mechanism of the substrate activity, especially of technologically relevant oxide surfaces, is poorly understood. Here we design and synthesize several distinct and stable CeO2 (001) surface reconstructions which are used to grow epitaxial films of the high-temperature superconductor YBa2Cu3O7. The film grown on the substrate having the longest, fourfold period, reconstruction exhibits a twofold increase in performance over surfaces with shorter period reconstructions. This is explained by the crossover between the nucleation site dimensions and the period of the surface reconstruction. This result opens a new avenue for catalysis mediated solid state synthesis. PMID:24717357

  1. Highly efficient solid state catalysis by reconstructed (001) Ceria surface

    SciTech Connect

    Solovyov, VF; Ozaki, T; Atrei, A; Wu, LJ; Al-Mahboob, A; Sadowski, JT; Tong, X; Nykypanchuk, D; Li, Q

    2014-04-10

    Substrate engineering is a key factor in the synthesis of new complex materials. The substrate surface has to be conditioned in order to minimize the energy threshold for the formation of the desired phase or to enhance the catalytic activity of the substrate. The mechanism of the substrate activity, especially of technologically relevant oxide surfaces, is poorly understood. Here we design and synthesize several distinct and stable CeO2 (001) surface reconstructions which are used to grow epitaxial films of the high-temperature superconductor YBa2Cu3O7. The film grown on the substrate having the longest, fourfold period, reconstruction exhibits a twofold increase in performance over surfaces with shorter period reconstructions. This is explained by the crossover between the nucleation site dimensions and the period of the surface reconstruction. This result opens a new avenue for catalysis mediated solid state synthesis.

  2. Study of surface charge density on solid/liquid interfaces by modulating the electrical double layer

    NASA Astrophysics Data System (ADS)

    Pak, Hyuk Kyu; Moon, Jong Kyun

    2014-11-01

    A solid surface in contact with water or aqueous solution usually carries specific electric charges. These surface charges attract counter ions from the liquid side. Since the geometry of opposite charge distribution parallel to the solid/liquid interface is similar to that of a capacitor, it is called an electrical double layer capacitor (EDLC). Therefore, there is an electrical potential difference across an EDLC in equilibrium. When a liquid bridge is formed between two conducting plates, the system behaves as two serially connected EDLCs. In this work, we propose a new method for investigating the surface charge density on solid/liquid interfaces. By mechanically modulating the electrical double layers and simultaneously applying a DC bias voltage across the plates, an AC electric current can be generated. By measuring the voltage difference between the plates as a function of bias voltage, we can study the surface charge density on solid/liquid interfaces. Our experimental results agree very well with the simple equivalent circuit model proposed here. Furthermore, using this method, one can determine the polarity of the adsorbed state on the solid surface depending on the material used. This work was supported by Center for Soft and Living Matter through IBS program in Korea.

  3. Modifying Thermal Transport in Colloidal Nanocrystal Solids with Surface Chemistry.

    PubMed

    Liu, Minglu; Ma, Yuanyu; Wang, Robert Y

    2015-12-22

    We present a systematic study on the effect of surface chemistry on thermal transport in colloidal nanocrystal (NC) solids. Using PbS NCs as a model system, we vary ligand binding group (thiol, amine, and atomic halides), ligand length (ethanedithiol, butanedithiol, hexanedithiol, and octanedithiol), and NC diameter (3.3-8.2 nm). Our experiments reveal several findings: (i) The ligand choice can vary the NC solid thermal conductivity by up to a factor of 2.5. (ii) The ligand binding strength to the NC core does not significantly impact thermal conductivity. (iii) Reducing the ligand length can decrease the interparticle distance, which increases thermal conductivity. (iv) Increasing the NC diameter increases thermal conductivity. (v) The effect of surface chemistry can exceed the effect of NC diameter and becomes more pronounced as NC diameter decreases. By combining these trends, we demonstrate that the thermal conductivity of NC solids can be varied by an overall factor of 4, from ∼0.1-0.4 W/m-K. We complement these findings with effective medium approximation modeling and identify thermal transport in the ligand matrix as the rate-limiter for thermal transport. By combining these modeling results with our experimental observations, we conclude that future efforts to increase thermal conductivity in NC solids should focus on the ligand-ligand interface between neighboring NCs.

  4. Solid Deuterium-Tritium Surface Roughness In A Beryllium Inertial Confinement Fusion Shell

    SciTech Connect

    Kozioziemski, B J; Sater, J D; Moody, J D; Montgomery, D S; Gautier, C

    2006-04-19

    Solid deuterium-tritium (D-T) fuel layers for inertial confinement fusion experiments were formed inside of a 2 mm diameter beryllium shell and were characterized using phase-contrast enhanced x-ray imaging. The solid D-T surface roughness is found to be 0.4 {micro}m for modes 7-128 at 1.5 K below the melting temperature. The layer roughness is found to increase with decreasing temperature, in agreement with previous visible light characterization studies. However, phase-contrast enhanced x-ray imaging provides a more robust surface roughness measurement than visible light methods. The new x-ray imaging results demonstrate clearly that the surface roughness decreases with time for solid D-T layers held at 1.5 K below the melting temperature.

  5. Estimation of laser solid forming process based on temperature measurement

    NASA Astrophysics Data System (ADS)

    Tan, Hua; Chen, Jing; Zhang, Fengying; Lin, Xin; Huang, Weidong

    2010-02-01

    By using a moving disc heat source model, an analytical model was developed to describe laser solid forming (LSF) process with the feedback of the surface temperature of the molten pool, which can be used to estimate the geometric characterizations (width and height) of the clad layer rapidly. An on-line temperature measurement system was established and some single-pass cladding experiments were conducted while the molten pool temperature was monitored. It was found that the estimated geometric characterizations agreed well with the experimental results. In addition, the power consumed by conduction, convection, radiation, evaporation and absorption during LSF were also estimated by the model. It was shown that the majority of the total absorbed power was conducted to the substrate. The effective model can not only be used to optimize the processing parameters but also potentially applied to the real-time feedback control.

  6. Intensity-Value Corrections for Integrating Sphere Measurements of Solid Samples Measured Behind Glass

    SciTech Connect

    Johnson, Timothy J.; Bernacki, Bruce E.; Redding, Rebecca L.; Su, Yin-Fong; Brauer, Carolyn S.; Myers, Tanya L.; Stephan, Eric G.

    2014-11-01

    Accurate and calibrated directional-hemispherical reflectance spectra of solids are important for both in situ and remote sensing. Many solids are in the form of powders or granules and to measure their diffuse reflectance spectra in the laboratory, it is often necessary to place the samples behind a transparent medium such as glass for the ultraviolet (UV), visible, or near-infrared spectral regions. Using both experimental methods and a simple optical model, we demonstrate that glass (fused quartz in our case) leads to artifacts in the reflectance values. We report our observations that the measured reflectance values, for both hemispherical and diffuse reflectance, are distorted by the additional reflections arising at the air–quartz and sample–quartz interfaces. The values are dependent on the sample reflectance and are offset in intensity in the hemispherical case, leading to measured values up to ~6% too high for a 2% reflectance surface, ~3.8% too high for 10% reflecting surfaces, approximately correct for 40–60% diffuse-reflecting surfaces, and ~1.5% too low for 99% reflecting Spectralon® surfaces. For the case of diffuse-only reflectance, the measured values are uniformly too low due to the polished glass, with differences of nearly 6% for a 99% reflecting matte surface. The deviations arise from the added reflections from the quartz surfaces, as verified by both theory and experiment, and depend on sphere design. Finally, empirical correction factors were implemented into post-processing software to redress the artifact for hemispherical and diffuse reflectance data across the 300–2300 nm range.

  7. Intensity-value corrections for integrating sphere measurements of solid samples measured behind glass.

    PubMed

    Johnson, Timothy J; Bernacki, Bruce E; Redding, Rebecca L; Su, Yin-Fong; Brauer, Carolyn S; Myers, Tanya L; Stephan, Eric G

    2014-01-01

    Accurate and calibrated directional-hemispherical reflectance spectra of solids are important for both in situ and remote sensing. Many solids are in the form of powders or granules and to measure their diffuse reflectance spectra in the laboratory, it is often necessary to place the samples behind a transparent medium such as glass for the ultraviolet (UV), visible, or near-infrared spectral regions. Using both experimental methods and a simple optical model, we demonstrate that glass (fused quartz in our case) leads to artifacts in the reflectance values. We report our observations that the measured reflectance values, for both hemispherical and diffuse reflectance, are distorted by the additional reflections arising at the air-quartz and sample-quartz interfaces. The values are dependent on the sample reflectance and are offset in intensity in the hemispherical case, leading to measured values up to ~6% too high for a 2% reflectance surface, ~3.8% too high for 10% reflecting surfaces, approximately correct for 40-60% diffuse-reflecting surfaces, and ~1.5% too low for 99% reflecting Spectralon® surfaces. For the case of diffuse-only reflectance, the measured values are uniformly too low due to the polished glass, with differences of nearly 6% for a 99% reflecting matte surface. The deviations arise from the added reflections from the quartz surfaces, as verified by both theory and experiment, and depend on sphere design. Empirical correction factors were implemented into post-processing software to redress the artifact for hemispherical and diffuse reflectance data across the 300-2300 nm range.

  8. Nanodrop of an Ising magnetic fluid on a solid surface.

    PubMed

    Berim, Gersh O; Ruckenstein, Eli

    2011-07-19

    The density functional theory of inhomogeneous simple fluids is extended to an Ising magnetic fluid in contact with a solid surface, which is subjected to an external uniform or nonuniform magnetic field. The system is described by two coupled integral equations regarding the magnetic moment and fluid density distributions. The dependence of the contact angle that a nanodrop makes with the solid surface on the parameters involved in the magnetic interactions between the molecules of fluid and between the molecules of fluid and an external magnetic field is calculated. For the uniform magnetic field, the contact angle increases with increasing magnetic field, approaching an asymptotic value that depends on the strength of the fluid-fluid magnetic interactions. In the nonuniform field generated by a permanent magnet, the contact angle first increases with increasing magnetic field B(M) and then decreases, with the decrease being almost linear for large values of B(M). The obtained results are in qualitative agreement with the experimental data on the contact angle of magnetic drops on a solid surface available in the literature.

  9. Comparative study of semilocal density functionals on solids and surfaces

    NASA Astrophysics Data System (ADS)

    Mo, Yuxiang; Tian, Guocai; Tao, Jianmin

    2017-08-01

    Recently, Tao and Mo (TM) proposed an accurate nonempirical meta-generalized gradient approximation (meta-GGA). To better understand the performance of this functional, here we make a comparative study of the combinations of the TM exchange part with the original TPSS correlation (TMTPSS) and the modified TPSS correlation (TM) on a variety of solids and surfaces. Specifically, we compare the performance of these two functionals on 22 lattice constants and bulk moduli, 30 band gaps of semiconductors, 7 cohesive energies, and surface exchange-correlation energies of simple metals with rs ranging from 2 to 3 bohr.

  10. DNA translocation measurements through low-capacitance solid-state nanopore chips at high bandwidths

    NASA Astrophysics Data System (ADS)

    Chien, Chen-Chi; Niedzwiecki, David; Machielse, Bartholomeus; Balan, Adrian; Lin, Jianxun; Ong, Peijie; Shepard, Kenneth; Drndic, Marija

    2015-03-01

    We perform DNA translocation measurements with low-noise solid state nanopore chips. We obtain higher ion current signal-to-noise ratio and better resolution in ion current signals than previously reported in solid state nanopores at high bandwidths with chip capacitance lowering techniques of applying extra insulation on the chip surface. We show measurements of ion current during translocation of DNA molecules through thin silicon nitride (SiN) nanopores of small diameters at megahertz bandwidths with enhanced ionic signal-to-noise ratios. We further discuss how these results possibly pave the way towards identifying intramolecular DNA sequences with solid-state nanopores.

  11. REVIEWS OF TOPICAL PROBLEMS: Solid-surface electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Gomoyunova, M. V.

    1982-01-01

    Electron spectroscopy (ES) of the surface of a solid comprises a set of methods of studying its elemental composition, structure, electronic structure, and dynamics. The essence of almost all the methods consists in obtaining and studying the energy spectra and angular distributions of electrons emitted by the surface of the solid upon irradiation with fluxes of photons, electrons, or ions, or upon creating a strong electric field near it. Depending on the nature of the probe, one can distinguish photoelectron, secondary-electron, ion-electron, and field spectroscopy. Each of them is realized by several methods. In practically all the methods analysis of the characteristics that are obtained consists of singling out certain unitypical elementary events of interaction of the probe agent with the surface layers of the solid. As a rule, the depth of probing is determined by the mean free path of the electron with respect to inelastic interaction. In the electron energy range from tens to approximately hundreds of electron volts in various materials, it constitutes from one to several atomic layers. In determining elemental composition, the sensitivity of most of the ES methods is approximately equal to hundredths of a monolayer. One can employ a scanning probe to obtain the distribution of the elements over the surface of the specimen. Most of the ES methods have been invented in the past decade. At present the studies in the field of surface physics are intensively developing and have great scientific and important applied significance. This review briefly treats the physical fundamentals of the ES methods, their potentialities, classifies the methods, gives examples to illustrate them, and cursorily throws light on the fundamental technical means of realizing the methods.

  12. Progress in Infrared Pyrometry Measurements of Shocked Solids

    SciTech Connect

    Cazamias, J U; Hare, D E; Poulsen, P

    2001-11-05

    Temperature measurement is one of the grand challenges still facing experimental shock physics. A shock experiment fundamentally measures E({sigma}{sub x}, {var_epsilon}{sub 11}) which is an incomplete equation of state since temperature (or entropy) remains unspecified. Ideally, one would like to experimentally determine a free energy F(T, {var_epsilon}{sub ij}) from which all other thermo-mechanical properties might be derived. In practice, temperature measurement would allow direct comparison with theory/simulation since T and {var_epsilon}{sub 11} are in most theories the underlying variables. Temperature is a sensitive measure of energy partitioning, knowledge of which would increase our understanding phase boundaries and thermally activated processes (such as chemical reactivity (including dissociation and ionization)). Temperature measurement would also allow a thermodynamically consistent coupling of hydrodynamic equations of state to the material's constitutive (deformation) behavior. The measurement of the temperature of a material that has undergone severe strains at small time-scales is extremely difficult, and we are developing a method using infrared reflectance and pyrometry. The emitted power from a warm surface is measured over a range of wavelengths using a multi-channel IR detector with a response time of {approx}0.1 {micro}s. Each channel of the detector passes the radiation from a selected wavelength interval into a detector. Pyrometers typically have anywhere from three to six channels, and not all channels may have enough signal to contribute to the measurement under any given condition. The difficulty in the measurement lies in relating the radiance (power per unit area per solid angle) in each channel to the temperature of the surface since the radiance is determined not only by the temperature, but also by the emissivity of the surface. The emissivity is not a constant for any real surface, but varies both with angle of observation and

  13. Enhancement of dissolution of Telmisartan through use of solid dispersion technique - surface solid dispersion

    PubMed Central

    Patel, Bhumika; Parikh, R. H.; Swarnkar, Deepali

    2012-01-01

    The present study was aimed to increase the solubility of the poorly water soluble drug Telmisartan by using Surface solid dispersion (SSD) made of polymers like Poloxamer 407, PEG 6000 by Solvent evaporation method. The drug was solubilized by surfactants and/or polymers then adsorbed onto the surface of extremely fine carriers to increase its surface area and to form the SSD which give the more Surface area for absorption of the drug. A 22 full factorial design was used to investigate for each carrier the joint influence of formulation variables: Amount of carrier and adsorbent. Saturation solubility studies shows the improvement in solubility of drug batch SSD 8 give more solubility improvement than the other batch, in-vitro dissolution of pure drug, physical mixtures and SSDs were carried out in that SSDs were found to be effective in increasing the dissolution rate of Telmisartan in form of SSD when compared to pure drug. Also FT-IR spectroscopy, differential scanning calorimetry and X-ray diffractometry studies were carried out in order to characterize the drug and Surface solid dispersion. Furthermore, both DSC and X-ray diffraction showed a decrease in the melting enthalpy and reduced drug crystallinity consequently in SSDs. However, infrared spectroscopy revealed no drug interactions with the carriers. PMID:23066211

  14. Rupture of thin liquid films sprayed on solid surfaces

    NASA Astrophysics Data System (ADS)

    Kadoura, M.; Chandra, S.

    2013-02-01

    An experimental study was done to observe the formation of thin films by spraying liquid onto a solid surface and to determine the conditions under which the films would rupture or remain stable. Water, or water mixed with 20-70 % by weight of glycerin, was sprayed for varying lengths of time onto a circular, 165-mm-diameter plate made of either Plexiglas, steel, or Parafilm-M and the motion of the liquid recorded using a high-speed camera. Water films ruptured immediately after the impact near the center of the surface. Then, if the film thickness was greater than a critical value, the water flooded back and the hole closed; otherwise, the hole remained in the water layer. The critical film thickness increases linearly with advancing liquid-solid contact angle. Increasing liquid viscosity by adding glycerin had little effect on critical film thickness, but inhibited spreading of the liquid and suppressed initial rupture of the liquid layer. A surface energy model was used to predict the variation of critical film thickness with surface wettability.

  15. Solid Lubrication Fundamentals and Applications. Properties of Clean Surfaces: Adhesion, Friction, and Wear

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1998-01-01

    This chapter presents the adhesion, friction, and wear behaviors of smooth, atomically clean surfaces of solid-solid couples, such as metal-ceramic couples, in a clean environment. Surface and bulk properties, which determine the adhesion, friction, and wear behaviors of solid-solid couples, are described. The primary emphasis is on the nature and character of the metal, especially its surface energy and ductility. Also, the mechanisms of friction and wear for clean, smooth surfaces are stated.

  16. Three-dimensional reconstructions of solid surfaces using conventional microscopes.

    PubMed

    Ficker, Tomáš; Martišek, Dalibor

    2016-01-01

    The three-dimensional digital replicas of solid surfaces are subject of interest of different branches of science and technology. The present paper in its introductory parts brings an overview of the various microscopic reconstructive techniques based on optical sectioning. The main attention is devoted to conventional reconstruction methods and especially to that one employing the Fourier transform. The three-dimensional replicas of this special reconstructive frequency method are compared graphically and numerically with the three-dimensional replicas of the confocal method. Based on the comparative study it has been concluded that the quality of the conventional replicas of surfaces possessing textures of intermediate height irregularities is acceptable and almost comparable with the quality of confocal replicas. This study is relevant both for identifying a convenient technique that provides good qualities of three-dimensional replicas and for selecting the hardware whose price is affordable even for small research groups studying rougher surface textures.

  17. Technology of wear resistance increase of surface elements of friction couples using solid lubricants

    NASA Astrophysics Data System (ADS)

    Morgunov, A. P.; Masyagin, V. B.; Derkach, V. V.; Matveev, N. A.

    2017-06-01

    Based on the results of experimental investigations in wear resistance increase using lamellar solid lubricants the technology of wear resistance increase of surface elements of friction couples by applying solid lubricants is developed with the following surface plastic deformation providing enough bond strength of solid lubricant with an element surface and increasing operational life.

  18. Sugar Surfactant Based Microemulsions at Solid Surfaces: Influence of the Oil Type and Surface Polarity.

    PubMed

    Vargas-Ruiz, Salomé; Soltwedel, Olaf; Micciulla, Samantha; Sreij, Ramsia; Feoktystov, Artem; von Klitzing, Regine; Hellweg, Thomas; Wellert, Stefan

    2016-11-15

    The structure of sugar-surfactant-based bicontinuous microemulsions in the bulk and at hydrophilic and hydrophobic solid planar surfaces was studied by means of neutron scattering techniques (SANS, NR, and GISANS). In particular, the influence of the type of oil (tetradecane and methyl oleate) on the structural properties in the vicinity of surfaces was investigated at different oil-to-water ratios. In the case of hydrophilic surfaces, the analysis of the scattering length density profiles reveals an induced ordering of the oil and water domains perpendicular to the solid-liquid interface in both sets of microemulsions. At hydrophobic surfaces, differences in the near-surface ordering between microemulsions containing polar and nonpolar oils are observed.

  19. Comparison of contact angle hysteresis of different probe liquids on the same solid surface.

    PubMed

    Chibowski, Emil; Jurak, Malgorzata

    2013-02-01

    Advancing and receding contact angles of water, formamide and diiodomethane were measured on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) layers deposited on three different solid supports-glass, mica and poly(methyl methacrylate). Up to five statistical monolayers were deposited on the surfaces by spreading DPPC solution. It was found that even on five statistical DPPC monolayers, the hysteresis of a given liquid depends on the kind of solid support. Also on the same solid support the contact angle hysteresis is different for each probe liquid used. The AFM images show that the heights of roughness of the DPPC films cannot be the primary cause of the observed hysteresis because the heights are too small to cause the observed hystereses. It is believed that the hysteresis is due to the liquid film present right behind the three-phase solid surface/liquid drop/gas (vapour) contact line and the presence of Derjaguin pressure. The value of contact angle hysteresis depends on both the solid surface and liquid properties as well as on intermolecular interactions between them.

  20. Surface emission of landfill gas from solid waste landfill

    NASA Astrophysics Data System (ADS)

    Park, Jin-Won; Shin, Ho-Chul

    The surface emission of landfill gas (LFG) was studied to estimate the amount of LFG efflux from solid waste landfills using an air flux chamber. LFG efflux increased as atmospheric temperature increased during the day, and the same pattern for the surface emission was observed for the change of seasons. LFG efflux rate decreased from summer through winter. The average LFG efflux rates of winter, spring and summer were 0.1584, 0.3013 and 0.8597 m 3 m -2 h -1 respectively. The total amount of surface emission was calculated based on the seasonal LFG efflux rate and the landfill surface area. From the estimates of LFG generation, it is expected that about 30% of the generated LFG may be released through the surface without extraction process. As forced extraction with a blower proceeded, the extraction well pressure decreased from 1100 to -100 mm H 2O, and the LFG surface efflux decreased markedly above 80%. Thus, the utilization of LFG by forced extraction would be the good solution for global warming and air pollution by LFG.

  1. Scientific support for an orbiter middeck experiment on solid surface combustion

    NASA Technical Reports Server (NTRS)

    Altenkirch, Robert A.; Vedha-Nayagam, M.; Srikantaiah, Nataraj

    1988-01-01

    The objective is to determine the mechanism of gas-phase flame spread over solid fuel surfaces in the absence of any buoyancy or externally imposed gas-phase flow. Such understanding can be used to improve the fire safety aspects of space travel by providing information that will allow judicious selections of spacecraft materials and environments to be made. The planned experiment consists of measuring the flame spread rate over thermally thin and thermally thick fuels in a closed container in the low-gravity environment of the Space Shuttle. Measurements consist of flame spread rate and shape obtained from two views of the process as recorded on movie film and surface and gas-phase temperatures obtained from fine-wire thermocouples. The temperature measurements along with appropriate modeling provide information about the gas-to-solid heat flux. Environmental parameters to be varied are the oxygen concentration and pressure.

  2. Experimental study of surface tension, specific heat and thermal diffusivity of liquid and solid titanium

    NASA Astrophysics Data System (ADS)

    Zhou, K.; Wang, H. P.; Chang, J.; Wei, B.

    2015-10-01

    The thermophysical properties of liquid and solid titanium such as the surface tension, specific heat and thermal diffusivity have been investigated over a wide temperature range. By using electromagnetic levitation and oscillating drop method, the surface tension of liquid titanium was measured in the temperature range of 1802-2188 K. The viscosity and density of undercooled liquid titanium were calculated by some well-known models using the measured data as input. In addition, the specific heat of liquid titanium was determined over the experimental range using electromagnetic levitation and drop calorimetry obtaining the value of 33.64 J mol-1 K-1. In addition, the thermal diffusivity of solid titanium was measured by laser flash method in the temperature range of 171-1080 K.

  3. Modelling harmonic generation measurements in solids.

    PubMed

    Best, S R; Croxford, A J; Neild, S A

    2014-02-01

    Harmonic generation measurements typically make use of the plane wave result when extracting values for the nonlinearity parameter, β, from experimental measurements. This approach, however, ignores the effects of diffraction, attenuation, and receiver integration which are common features in a typical experiment. Our aim is to determine the importance of these effects when making measurements of β over different sample dimensions, or using different input frequencies. We describe a three-dimensional numerical model designed to accurately predict the results of a typical experiment, based on a quasi-linear assumption. An experiment is designed to measure the axial variation of the fundamental and second harmonic amplitude components in an ultrasonic beam, and the results are compared with those predicted by the model. The absolute β values are then extracted from the experimental data using both the simulation and the standard plane wave result. A difference is observed between the values returned by the two methods, which varies with axial range and input frequency.

  4. Solids concentration measurements in molten wax by an ultrasonic technique

    SciTech Connect

    Soong, Y.; Gamwo, I.K.; Blackwell, A.G.; Schehl, R.R.; Zarochak, M.F.

    1994-12-31

    The application of the three-phase slurry reactor system to coal liquefaction processing and chemical industries has recently received considerable attention. To design and efficiently operate a three-phase slurry reactor, the degree of dispersion of the solid (catalyst) in the reactor should be understood. The solids distribution within the reactor greatly affects its performance. An ultrasonic technique is under development for measuring solids concentration in a three-phase slurry reactor. Preliminary measurements have been made on slurries consisting of molten paraffin wax, glass beads, and nitrogen bubbles at 189 C. The data show that the velocity and attenuation of the sound are well-defined functions of the solid and gas concentrations in the molten wax.

  5. The measurement of surface gravity

    NASA Astrophysics Data System (ADS)

    Crossley, David; Hinderer, Jacques; Riccardi, Umberto

    2013-04-01

    This review covers basic theory and techniques behind the use of ground-based gravimetry at the Earth's surface. The orientation is toward modern instrumentation, data processing and interpretation for observing surface, land-based, time-variable changes to the geopotential. The instrumentation side is covered in some detail, with specifications and performance of the most widely used models of the three main types: the absolute gravimeters (FG5, A10 from Micro-g LaCoste), superconducting gravimeters (OSG, iGrav from GWR instruments), and the new generation of spring instruments (Micro-g LaCoste gPhone, Scintrex CG5 and Burris ZLS). A wide range of applications is covered, with selected examples from tides and ocean loading, atmospheric effects on gravity, local and global hydrology, seismology and normal modes, long period and tectonics, volcanology, exploration gravimetry, and some examples of gravimetry connected to fundamental physics. We show that there are only a modest number of very large signals, i.e. hundreds of µGal (10-8 m s-2), that are easy to see with all gravimeters (e.g. tides, volcanic eruptions, large earthquakes, seasonal hydrology). The majority of signals of interest are in the range 0.1-5.0 µGal and occur at a wide range of time scales (minutes to years) and spatial extent (a few meters to global). Here the competing effects require a careful combination of different gravimeter types and measurement strategies to efficiently characterize and distinguish the signals. Gravimeters are sophisticated instruments, with substantial up-front costs, and they place demands on the operators to maximize the results. Nevertheless their performance characteristics such as drift and precision have improved dramatically in recent years, and their data recording ability and ruggedness have seen similar advances. Many subtle signals are now routinely connected with known geophysical effects such as coseismic earthquake displacements, post-glacial rebound

  6. The measurement of surface gravity.

    PubMed

    Crossley, David; Hinderer, Jacques; Riccardi, Umberto

    2013-04-01

    This review covers basic theory and techniques behind the use of ground-based gravimetry at the Earth's surface. The orientation is toward modern instrumentation, data processing and interpretation for observing surface, land-based, time-variable changes to the geopotential. The instrumentation side is covered in some detail, with specifications and performance of the most widely used models of the three main types: the absolute gravimeters (FG5, A10 from Micro-g LaCoste), superconducting gravimeters (OSG, iGrav from GWR instruments), and the new generation of spring instruments (Micro-g LaCoste gPhone, Scintrex CG5 and Burris ZLS). A wide range of applications is covered, with selected examples from tides and ocean loading, atmospheric effects on gravity, local and global hydrology, seismology and normal modes, long period and tectonics, volcanology, exploration gravimetry, and some examples of gravimetry connected to fundamental physics. We show that there are only a modest number of very large signals, i.e. hundreds of µGal (10(-8) m s(-2)), that are easy to see with all gravimeters (e.g. tides, volcanic eruptions, large earthquakes, seasonal hydrology). The majority of signals of interest are in the range 0.1-5.0 µGal and occur at a wide range of time scales (minutes to years) and spatial extent (a few meters to global). Here the competing effects require a careful combination of different gravimeter types and measurement strategies to efficiently characterize and distinguish the signals. Gravimeters are sophisticated instruments, with substantial up-front costs, and they place demands on the operators to maximize the results. Nevertheless their performance characteristics such as drift and precision have improved dramatically in recent years, and their data recording ability and ruggedness have seen similar advances. Many subtle signals are now routinely connected with known geophysical effects such as coseismic earthquake displacements, post

  7. The solid surface combustion space shuttle experiment hardware description and ground-based test results

    NASA Technical Reports Server (NTRS)

    Vento, D. M.; Zavesky, R. J.; Sacksteder, K. R.; Altenkirch, R. A.

    1989-01-01

    The Lewis Research Center is developing a series of microgravity combustion experiments for the Space Shuttle. The Solid Surface Combustion Experiment (SSCE) is the first to be completed. SSCE will study flame spreading over thermally thin fuels (ashless filter paper) under microgravity conditions. The flight hardware consists of a combustion chamber containing the sample and a computer which takes the data and controls the experiment. Experimental data will include gas-phase and solid-phase temperature measurements and motion pictures of the combustion process. Flame spread rates will be determined from the motion pictures.

  8. Friction, Wear, and Surface Damage of Metals as Affected by Solid Surface Films

    NASA Technical Reports Server (NTRS)

    Bisson, Edmond E; Johnson, Robert L; Swikert, Max A; Godfrey, Douglas

    1956-01-01

    As predicted by friction theory, experiments showed that friction and surface damage of metals can be reduced by solid surface films. The ability of materials to form surface films that prevent welding was a very important factor in wear of dry and boundary lubricated surfaces. Films of graphitic carbon on cast irons, nio on nickel alloys, and feo and fe sub 3 o sub 4 on ferrous materials were found to be beneficial. Abrasive films such as fe sub 2 o sub 3 or moo sub 3 were definitely detrimental. It appears that the importance of oxide films to friction and wear processes has not been fully appreciated.

  9. Detailed electrical measurements on sago starch biopolymer solid electrolyte

    NASA Astrophysics Data System (ADS)

    Singh, Rahul; Baghel, Jaya; Shukla, S.; Bhattacharya, B.; Rhee, Hee-Woo; Singh, Pramod K.

    2014-12-01

    The biopolymer solid electrolyte has been synthesized and characterized. Potassium iodide (KI) has been added in polymer matrix to develop solid polymer electrolyte. Relationships between electrical, ionic transport parameter and mechanism have been studied in detail. Impedance spectroscopy reveals the detailed electrical studies and ion transport mechanism. The ion dissociation factor is compared with a measured dielectric constant at a fixed frequency. The dielectric data are calculated which support the ionic conductivity data.

  10. "Active surfaces" formed by immobilization of enzymes on solid-supported polymer membranes.

    PubMed

    Draghici, Camelia; Kowal, Justyna; Darjan, Alina; Meier, Wolfgang; Palivan, Cornelia G

    2014-10-07

    In various domains ranging from catalysis to medical and environmental sciences, there is currently much focus on the design of surfaces that present active compounds at the interface with their environments. Here, we describe the design of "active surfaces" based on solid-supported monolayers of asymmetric triblock copolymers, which serve as templates for the attachment of enzymes. A group of poly(ethylene glycol)-block-poly(γ-methyl-ε-caprolactone)-block-poly[(2-dimethylamino) ethyl methacrylate] amphiphilic copolymers, with different hydrophilic and hydrophobic domains (PEG45-b-PMCLx-b-PDMAEMAy) was selected to generate solid-supported polymer membranes. The behavior of the copolymers in terms of their molecular arrangements at the air-water interface was established by a combination of Langmuir isotherms and Brewster angle microscopy. Uniform thin layers of copolymers were obtained by transferring films onto silica solid supports at optimal surface pressure. These solid-supported polymer membranes were characterized by assessing various properties, such as monolayer thickness, hydrophilic/hydrophobic balance, topography, and roughness. Laccase, used as an enzyme model, was successfully attached to copolymer membranes by stable interactions as followed by quartz crystal microbalance with dissipation measurements, and its activity was preserved, as indicated by activity assays. The interaction between the amphiphilic triblock copolymer films and immobilized enzymes represents a straightforward approach to engineer "active surfaces", with biomolecules playing the active role by their intrinsic bioactivity.

  11. Contact angle of a nanodrop on a nanorough solid surface.

    PubMed

    Berim, Gersh O; Ruckenstein, Eli

    2015-02-21

    The contact angle of a cylindrical nanodrop on a nanorough solid surface is calculated, for both hydrophobic and hydrophilic surfaces, using the density functional theory. The emphasis of the paper is on the dependence of the contact angle on roughness. The roughness is modeled by rectangular pillars of infinite length located on the smooth surface of a substrate, with fluid-pillar interactions different in strength from the fluid-substrate ones. It is shown that for hydrophobic substrates the trend of the contact angle to increase with increasing roughness, which was noted in all previous studies, is not universally valid, but depends on the fluid-pillar interactions, pillar height, interpillar distance, as well as on the size of the drop. For hydrophilic substrate, an unusual kink-like dependence of the contact angle on the nanodrop size is found which is caused by the change in the location of the leading edges of the nanodrop on the surface. It is also shown that the Wenzel and Cassie-Baxter equations can not explain all the peculiarities of the contact angle of a nanodrop on a nanorough surface.

  12. Adhesion of Cryptosporidium parvum and Giardia lamblia to solid surfaces: the role of surface charge and hydrophobicity.

    PubMed

    Dai, X; Boll, J; Hayes, M E; Aston, D E

    2004-04-15

    Adhesion of Cryptosporidium parvum and Giardia lamblia to four materials of different surface charge and hydrophobicity was investigated. Glass beads were used with and without three polymer coatings: aminosilines (A0750), fluorosilines (T2494), an amino cationic polymer. Surface charge density and hydrophobicity of the beads were characterized by measuring the zeta potential (ZP) and the contact angle, respectively. Adhesion was derived from batch experiments where negatively charged (oo)cysts were mixed with the beads and recovery was determined by counting (oo)cysts remaining in suspension using a flow cytometer. Experimental results clearly show that adhesion to solid surfaces of C. parvum is different from G. lamblia. Adhesion of C. parvum to positively charged, hydrophilic beads (82% recovery relative to control) indicated that surface charge was the more important factor for C. parvum, dominating any hydrophobic effects. Adhesion of G. lamblia cysts to negatively charged, hydrophobic beads (0% recovery relative to control) indicated that although hydrophobicity and surface charge both played a role in the adhesion of G. lamblia to solid surfaces, hydrophobicity was more important than surface charge.

  13. Solids Fraction Measurement with a Reflective Fiber Optic Probe

    SciTech Connect

    Seachman, S.M.; Yue, P.C.; Ludlow, J.C.; Shadle, L.J.

    2006-11-01

    A method has been developed to extract solids fraction information from a reflective fiber optic probe. The commercially available reflective fiber optic probe was designed to measure axial particle velocity (both up and down directions). However, the reflected light intensity measured is related to particle size and particle concentration. A light reflection model is used to relate the reflected light intensity to solids fraction. In this model we assume that the reflected light intensity is a fixed fraction, K1, of the total light intensity lost in penetration of a solid layer. Also, the solids fraction is related to particle concentration, N, in the light path, by N = K2 (1- ε), where (1-ε) is the solids fraction. The parameters K1 and K2 are determined through a calibration and curve fitting procedure. This paper describes this procedure and the steps taken to derive the values of K1 and K2. It is proposed that the reflective fiber optic can be used for real time measurement of solids fraction in a circulating fluid bed.

  14. Lift-Off Instability During the Impact of a Drop on a Solid Surface

    NASA Astrophysics Data System (ADS)

    Kolinski, John M.; Mahadevan, L.; Rubinstein, Shmuel M.

    2014-04-01

    We directly measure the rapid spreading dynamics succeeding the impact of a droplet of fluid on a solid, dry surface. Upon impact, the air separating the liquid from the solid surface fails to drain and wetting is delayed as the liquid rapidly spreads outwards over a nanometer thin film of air. We show that the approach of the spreading liquid front toward the surface is unstable and the spreading front lifts off away from the surface. Lift-off ensues well before the liquid contacts the surface, in contrast with prevailing paradigm where lift-off of the liquid is contingent on solid-liquid contact and the formation of a viscous boundary layer. Here we investigate the dynamics of liquid spreading over a thin film of air and its lift-off away from the surface over a large range of fluid viscosities and find that the lift-off instability is dependent on viscosity and occurs at a time that scales with the viscosity to the power of one half.

  15. Lift-off instability during the impact of a drop on a solid surface.

    PubMed

    Kolinski, John M; Mahadevan, L; Rubinstein, Shmuel M

    2014-04-04

    We directly measure the rapid spreading dynamics succeeding the impact of a droplet of fluid on a solid, dry surface. Upon impact, the air separating the liquid from the solid surface fails to drain and wetting is delayed as the liquid rapidly spreads outwards over a nanometer thin film of air. We show that the approach of the spreading liquid front toward the surface is unstable and the spreading front lifts off away from the surface. Lift-off ensues well before the liquid contacts the surface, in contrast with prevailing paradigm where lift-off of the liquid is contingent on solid-liquid contact and the formation of a viscous boundary layer. Here we investigate the dynamics of liquid spreading over a thin film of air and its lift-off away from the surface over a large range of fluid viscosities and find that the lift-off instability is dependent on viscosity and occurs at a time that scales with the viscosity to the power of one half.

  16. Surface tension and contact with soft elastic solids

    NASA Astrophysics Data System (ADS)

    Style, Robert W.; Hyland, Callen; Boltyanskiy, Rostislav; Wettlaufer, John S.; Dufresne, Eric R.

    2013-11-01

    The Johnson-Kendall-Roberts theory is the basis of modern contact mechanics. It describes how two deformable objects adhere together, driven by adhesion energy and opposed by elasticity. Here we characterize the indentation of glass particles into soft, silicone substrates using confocal microscopy. We show that, whereas the Johnson-Kendall-Roberts theory holds for particles larger than a critical, elastocapillary lengthscale, it fails for smaller particles. Instead, adhesion of small particles mimics the adsorption of particles at a fluid interface, with a size-independent contact angle between the undeformed surface and the particle given by a generalized version of the Young's law. A simple theory quantitatively captures this behaviour and explains how solid surface tension dominates elasticity for small-scale indentation of soft materials.

  17. Surface Specularity as an Indicator of Shock-Induced Solid-Liquid Phase Transitions

    SciTech Connect

    Gerald Stevens, Stephen Lutz, William Turley, Lynn Veeser

    2007-06-29

    When highly polished metal surfaces melt upon release after shock loading, they exhibit a number of features that suggest that significant surface changes accompany the phase transition. The reflection of light from such surfaces changes from specular (pre-shock) to diffuse upon melting. A familiar manifestation of this phenomenon is the loss of signal light in velocimetric measurements typically observed above pressures high enough to melt the free-surface. Unlike many other potential material phase-sensitive diagnostics (e.g., reflectometery, conductivity), changes in the specularity of reflection provide a dramatic, sensitive indicator of the solid-liquid phase transition. Data will be presented from multiple diagnostics that support the hypothesis that specularity changes indicate melt. These diagnostics include shadowgraphy, infrared imagery, high-magnification surface images, interferometric velocimetry, and most recently scattering angle measurements.

  18. Optical Measurement for Solid- and Liquid-Phase Sb2Te3 around Its Melting Point

    NASA Astrophysics Data System (ADS)

    Kuwahara, Masashi; Endo, Rie; Tsutsumi, Kouichi; Morikasa, Fukuyoshi; Tsuruoka, Tohru; Fukaya, Toshio; Suzuki, Michio; Susa, Masahiro; Endo, Tomoyoshi; Tadokoro, Toshiyasu

    2013-11-01

    We have developed a system for measuring the complex refractive index of liquid- and solid-phase chalcogenide around their melting points. The system consists of a spectroscopic ellipsometer, an infrared heating system, and prism optics. As a container for the chalcogenide, we use a customized quartz cell, evacuated to several pascal level to avoid sample degradation. We adopted a measurement configuration that uses access from the bottom side, because a mirror-like surface which is necessary for optical measurement was naturally and easily created at the container bottom by gravity. We succeeded in observing the remarkable difference on the indices between liquid- and solid-phase Sb2Te3.

  19. Solid supported lipid membranes: New concepts for the biomimetic functionalization of solid surfaces

    PubMed Central

    Knoll, W.; Naumann, R.; Friedrich, M.; Robertson, J. W. F.; Lösche, M.; Heinrich, F.; McGillivray, D. J.; Schuster, B.; Gufler, P. C.; Pum, D.; Sleytr, U. B.

    2010-01-01

    Surface-layer (S-layer) supported lipid membranes on solid substrates are interfacial architectures mimicking the supramolecular principle of cell envelopes which have been optimized for billions of years of evolution in most extreme habitats. The authors implement this biological construction principle in a variety of layered supramolecular architectures consisting of a stabilizing protein monolayer and a functional phospholipid bilayer for the design and development of new types of solid-supported biomimetic membranes with a considerably extended stability and lifetime—compared to existing platforms—as required for novel types of bioanalytical sensors. First, Langmuir monolayers of lipids at the water/air interface are used as test beds for the characterization of different types of molecules which all interact with the lipid layers in various ways and, hence, are relevant for the control of the structure, stability, and function of supported membranes. As an example, the interaction of S-layer proteins from the bulk phase with a monolayer of a phospholipid synthetically conjugated with a secondary cell wall polymer (SCWP) was studied as a function of the packing density of the lipids in the monolayer. Furthermore, SCWPs were used as a new molecular construction element. The exploitation of a specific lectin-type bond between the N-terminal part of selected S-layer proteins and a variety of glycans allowed for the buildup of supramolecular assemblies and thus functional membranes with a further increased stability. Next, S-layer proteins were self-assembled and characterized by the surface-sensitive techniques, surface plasmon resonance spectroscopy and quartz crystal microbalance with dissipation monitoring. The substrates were either planar gold or silicon dioxide sensor surfaces. The assembly of S-layer proteins from solution to solid substrates could nicely be followed in-situ and in real time. As a next step toward S-layer supported bilayer membranes

  20. Kinetics and molecular binding of GEPIs on solid surfaces

    NASA Astrophysics Data System (ADS)

    Wilson, Brandon

    proof-of-concept applications. In an enzyme immobilization study, for example enzymes immobilized via GEPIs showed significantly higher activity than those nonspecifically immobilized. In biomineralization studies, several bifunctional GEPIs showed the ability to mineralize hydroxyapatite out of a calcium phosphate solution, where control surfaces and peptides showed no mineralization ability. With the present first study, which established quantitative molecular binding procedures of solid binding peptides, it is now possible to design, tailor and implement GEPIs for a wide range of applications, from nanotechnology to medical problems that require an interface between a biopolymer/biosurface and an inorganic surface.

  1. Dynamic properties of municipal solid waste landfills from surface wave tests

    SciTech Connect

    Haker, C.D.; Rix, G.J.; Lai, C.G.

    1997-10-01

    The seismic stability of municipal solid waste (MSW) landfills is often a significant consideration in landfill design. However, until recently, the dynamic properties of the waste material itself, which govern the seismic response of MSW landfills, have often been approximated or assumed. Tests to determine the dynamic properties of the material directly have been limited. Measurements of seismic surface waves were used to determine the dynamic properties of MSW, which are the initial tangent shear modulus and low-strain hysteretic damping ratio. Surface wave tests were performed at three MSW landfills to determine their shear modulus and damping ratio profiles. Surface wave tests are ideal for measuring the near-surface shear modulus and damping profiles of MSW landfills because the tests are non-invasive, an advantage for testing environmentally sensitive waste material. Factors which influence the dynamic properties of waste including density, confinement, age, and placement techniques are used to interpret the measured shear modulus and damping ratio profiles.

  2. Nano Liquid Crystal Droplet Impact on Solid Surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; de Pablo, Juan; dePablo Team

    2015-03-01

    Liquid droplet impaction on solid surfaces is an important problem with a wide range of applications in everyday life. Liquid crystals (LCs) are anisotropic liquids whose internal structure gives rise to rich optical and morphological phenomena. In this work we study the liquid crystal droplet impaction on solid surfaces by molecular dynamics simulations. We employ a widely used Gay-Berne model to describe the elongated liquid crystal molecules and their interactions. Our work shows that, in contrast to isotropic liquids, drop deformation is symmetric unless an instability kicks in, in which case a nano scale liquid crystal droplet exhibits distinct anisotropic spreading modes that do not occur in simple liquids. The drop prefers spreading along the low viscosity direction, but inertia can in some cases overcome that bias. The effects of the director field of the droplet, preferred anchoring direction and the anchoring strength of the wall are investigated. Large scale (0.1 micron) simulations are performed to connect our nano scale results to the experiments. Our studies indicate that LCs could provide an interesting alternative for development of next-generation printing inks.

  3. Drop impact on solid surface: Short time self-similarity

    NASA Astrophysics Data System (ADS)

    Philippi, Julien; Lagrée, Pierre-Yves; Antkowiak, Arnaud

    2014-11-01

    Drop impact on a solid surface is a problem with many industrial or environmental applications. Many studies focused on the last stages of this phenomenon as spreading or splashing. In this study we are interested in the early stages of drop impact on solid surface. Inspired by Wagner theory developed by water entry community we shown the self-similar structure of the velocity field and the pressure field. The latter is shown to exhibit a maximum not near the impact point, but rather at the contact line. The motion of the contact line is furthermore shown to exhibit a transition from ``tank treading'' motion to pure sweeping when the lamella appears. We performed numerical simulations with the open-cource code Gerris which are in good agreement with theoretical predictions. Interestingly the inviscid self-similar impact pressure and velocities depend on the self-similar variable r /√{ t} . This allows to construct a seamless uniform analytical solution encompassing both impact and viscous effects. We predict quantitatively observables of interest, such as the evolution of total and maximum viscous shear stresses and net total force. We finally demonstrate that the structure of the flow resembles a stagnation point flow unexpectedly involving r /√{ t} .

  4. Ionization distances of multiply charged Rydberg ions approaching solid surfaces

    SciTech Connect

    Nedeljkovic, Lj. D.; Nedeljkovic, N. N.; Bozanic, D. K.

    2006-09-15

    The ionization distances R{sub c}{sup I} as well as the ionization rates and eigenenergies of one-electron multiply charged Rydberg ions (core charge Z>>1, principal quantum number n>>1) approaching solid surfaces are calculated. Within the framework of a nonperturbative etalon equation method (EEM), these quantities are obtained simultaneously. The complex energy eigenvalue problem for the decaying eigenstates is solved within the critical region R{approx_equal}R{sub c}{approx_equal}R{sub c}{sup I} of the ion-surface distances R. This region is characterized by the energy terms localized in the vicinity of the top of an effective potential barrier, created between the ion and polarized solid. We take into account that the parabolic symmetry is preserved for R{approx_equal}R{sub c} and that the parabolic quantum numbers can be taken as approximate but sufficiently good quantum numbers. The parabolic rates, energies, and corresponding ionization distances are presented in relatively simple analytical forms. The ionization distances are compared with the results of a classical overbarrier model. Comparison of the obtained energies and rates with the available theoretical predictions of the coupled angular mode method shows good agreement. The use of the EEM for an estimation of the upper limit of the first neutralization distance in the subsequent neutralization cascade is briefly discussed.

  5. Ice nuclei measurements from solid rocket motor effluents

    NASA Technical Reports Server (NTRS)

    Hindman, E. E., II

    1980-01-01

    The ice crystal forming nuclei (IN) measured in solid rocket motor (SRM) exhaust products is discussed in relation to space shuttle exhaust. Preliminary results from laboratory investigations and flight preparations for March 1978 Titan launch are discussed. The work necessary to provide adequate measurements of IN and cloud condensation nuclei (CCN) in the stabilized ground clouds from SRM's is studied.

  6. A nanostructured surface increases friction exponentially at the solid-gas interface

    NASA Astrophysics Data System (ADS)

    Phani, Arindam; Putkaradze, Vakhtang; Hawk, John E.; Prashanthi, Kovur; Thundat, Thomas

    2016-09-01

    According to Stokes’ law, a moving solid surface experiences viscous drag that is linearly related to its velocity and the viscosity of the medium. The viscous interactions result in dissipation that is known to scale as the square root of the kinematic viscosity times the density of the gas. We observed that when an oscillating surface is modified with nanostructures, the experimentally measured dissipation shows an exponential dependence on kinematic viscosity. The surface nanostructures alter solid-gas interplay greatly, amplifying the dissipation response exponentially for even minute variations in viscosity. Nanostructured resonator thus allows discrimination of otherwise narrow range of gaseous viscosity making dissipation an ideal parameter for analysis of a gaseous media. We attribute the observed exponential enhancement to the stochastic nature of interactions of many coupled nanostructures with the gas media.

  7. A nanostructured surface increases friction exponentially at the solid-gas interface.

    PubMed

    Phani, Arindam; Putkaradze, Vakhtang; Hawk, John E; Prashanthi, Kovur; Thundat, Thomas

    2016-09-06

    According to Stokes' law, a moving solid surface experiences viscous drag that is linearly related to its velocity and the viscosity of the medium. The viscous interactions result in dissipation that is known to scale as the square root of the kinematic viscosity times the density of the gas. We observed that when an oscillating surface is modified with nanostructures, the experimentally measured dissipation shows an exponential dependence on kinematic viscosity. The surface nanostructures alter solid-gas interplay greatly, amplifying the dissipation response exponentially for even minute variations in viscosity. Nanostructured resonator thus allows discrimination of otherwise narrow range of gaseous viscosity making dissipation an ideal parameter for analysis of a gaseous media. We attribute the observed exponential enhancement to the stochastic nature of interactions of many coupled nanostructures with the gas media.

  8. A nanostructured surface increases friction exponentially at the solid-gas interface

    PubMed Central

    Phani, Arindam; Putkaradze, Vakhtang; Hawk, John E.; Prashanthi, Kovur; Thundat, Thomas

    2016-01-01

    According to Stokes’ law, a moving solid surface experiences viscous drag that is linearly related to its velocity and the viscosity of the medium. The viscous interactions result in dissipation that is known to scale as the square root of the kinematic viscosity times the density of the gas. We observed that when an oscillating surface is modified with nanostructures, the experimentally measured dissipation shows an exponential dependence on kinematic viscosity. The surface nanostructures alter solid-gas interplay greatly, amplifying the dissipation response exponentially for even minute variations in viscosity. Nanostructured resonator thus allows discrimination of otherwise narrow range of gaseous viscosity making dissipation an ideal parameter for analysis of a gaseous media. We attribute the observed exponential enhancement to the stochastic nature of interactions of many coupled nanostructures with the gas media. PMID:27596851

  9. Enhancement of Li+ ion conductivity in solid polymer electrolytes using surface tailored porous silica nanofillers

    NASA Astrophysics Data System (ADS)

    Mohanta, Jagdeep; Singh, Udai P.; Panda, Subhendu K.; Si, Satyabrata

    2016-09-01

    The current study represents the design and synthesis of polyethylene oxide (PEO)-based solid polymer electrolytes by solvent casting approach using surface tailored porous silica as nanofillers. The surface tailoring of porous silica nanostructure is achieved through silanization chemistry using 3-glycidyloxypropyl trimethoxysilane in which silane part get anchored to the silica surface whereas epoxy group get stellated from the silica surface. Surface tailoring of silica with epoxy group increases the room temperature electrochemical performances of the resulting polymer electrolytes. Ammonical hydrolysis of organosilicate precursor is used for both silica preparation and their surface tailoring. The composite solid polymer electrolyte films are prepared by solution mixing of PEO with lithium salt in presence of silica nanofillers and cast into film by solvent drying, which are then characterized by impedance measurement for conductivity study and wide angle x-ray diffraction for change in polymer crystallinity. Room temperature impedance measurement reveals Li+ ion conductivity in the order of 10-4 S cm-1, which is correlated to the decrease in PEO crystallinity. The enhancement of conductivity is further observed to be dependent on the amount of silica as well as on their surface characteristics.

  10. Highlighting non-uniform temperatures close to liquid/solid surfaces

    NASA Astrophysics Data System (ADS)

    Noirez, L.; Baroni, P.; Bardeau, J. F.

    2017-05-01

    The present experimental measurements reveal that similar to external fields such as electric, magnetic, or flow fields, the vicinity of a solid surface can preclude the liquid molecules from relaxing to equilibrium, generating located non-uniform temperatures. The non-uniform temperature zone extends up to several millimeters within the liquid with a lower temperature near the solid wall (reaching ΔT = -0.15 °C ± 0.02 °C in the case of liquid water) counterbalanced at larger distances by a temperature rise. These effects highlighted by two independent methods (thermistor measurement and infra-red emissivity) are particularly pronounced for highly wetting surfaces. The scale over which non-uniform temperatures are extended indicates that the effect is assisted by intermolecular interactions, in agreement with recent developments showing that liquids possess finite shear elasticity and theoretical approaches integrating long range correlations.

  11. Surface properties of solids and surface acoustic waves: Application to chemical sensors and layer characterization

    NASA Astrophysics Data System (ADS)

    Krylov, V. V.

    1995-09-01

    A general phenomenological approach is given for the description of mechanical surface properties of solids and their influence on surface acoustic wave propogation. Surface properties under consideration may be changes of the stress distribution in subsurface atomic layers, the presence of adsorbed gas molecules, surface degradation as a result of impacts from an aggressive environment, damage due to mechanical manufacturing or polishing, deposition of thin films or liquid layers, surface corrugations, etc. If the characteristic thickness of the affected layers is much less than the wavelengths of the propagating surface waves, then the effects of all these irregularities can be described by means of non-classical boundary conditions incorporating the integral surface parameters such as surface tension, surface moduli of elasticity and surface mass density. The effect of surface properties on the propagation of Rayleigh surface waves is analysed in comparison with the results of traditional approaches, in particular with Auld's energy perturbation method. One of the important implications of the above-mentioned boudnary conditions is that they are adequate for the description of the effect of rarely distributed adsorbed atoms or molecules. This allows, in particular, to obtain a rigorous theoretical description of chemical sensors using surface acoustic waves and to derive analytical expressions for their sensitivity.

  12. Surface composition of solid-rocket exhausted aluminum oxide particles

    NASA Technical Reports Server (NTRS)

    Cofer, Wesley R., III; Winstead, Edward L.; Key, Lawrence E.

    1989-01-01

    Particulate samples of aluminum oxide were collected on Teflon filters from the exhaust plume of the Space Shuttle (STS-61A, October 30, 1985) over the altitude interval 4.6-7.6 km immediately after launch. These particles were analyzed using SEM, energy-dispersive X-ray analysis, electron spectroscopy for chemical analysis, X-ray fluorescent spectroscopy, and conventional wet-chemical techniques. The samples were 0.6-1.0 percent surface-chlorided (chlorided meaning predominantly aluminum chlorides and oxychlorides, possibly including other adsorbed forms of chloride) by weight. This level of chloriding is about one-third of the amount determined previously from laboratory-prepared alumina and surface site samples of solid-rocket-produced alumina (SRPA) after both had been exposed to moist HCl vapor at temperatures down to ambient. This level is equivalent to previous laboratory results with samples exposed to moist HCl at temperatures above the boiling point of water. It is suggested that the present lower chloriding levels, determined for samples from a 'dry' Shuttle exhaust cloud, underscore the importance of a liquid water/hydrochloric acid phase in governing the extent of surface chloriding of SRPA. The reduced chloriding is not trivial with respect to potential physical/chemical modification of the SRPA particle surfaces and their corresponding interaction with the atmosphere.

  13. Solid-on-solid model for surface growth in 2+1 dimensions

    NASA Astrophysics Data System (ADS)

    Hosseinabadi, S.; Masoudi, A. A.; Sadegh Movahed, M.

    2010-04-01

    We analyze in detail the solid-on-solid (SOS) model for growth processes on a square substrate in 2+1 dimensions. By using the Markovian surface properties, we introduce an alternative approach for determining the roughness exponent of a special type of SOS model-the restricted-solid-on-solid (RSOS) model-in 2+1 dimensions. This model is the SOS model with the additional restriction that the height difference must be S=1. Our numerical results show that the behavior of the SOS model in 2+1 dimensions for approximately S≥S×∼8 belongs to the two different universality classes: during the initial time stage, t

  14. Vibrational Spectroscopy of Water at Liquid/Solid Interfaces: Crossing the Isoelectric Point of a Solid Surface

    NASA Astrophysics Data System (ADS)

    Yeganeh, M. S.; Dougal, S. M.; Pink, H. S.

    1999-08-01

    We have used IR-visible sum-frequency generation (SFG) spectroscopy to demonstrate that water dipoles at a liquid/solid interface flip by 180° when the pH of the aqueous solution crosses the isoelectric point of the surface (IEPS). We have also shown, for the first time, that the SFG signal intensity and thus the nonlinear polarizability of a water/solid interface depends strongly on the hydroxyl number density of the solid surface. A new methodology for the determination of the IEPS of a nonconductive, low-surface area material was introduced.

  15. Spin-polarized photoelectron diffraction from magnetically-ordered solids and surfaces

    NASA Astrophysics Data System (ADS)

    Sinković, B.; Hermsmeier, B.; Fadley, C. S.

    1986-02-01

    We report the first experimental observation of Spin-Polarized Photoelectron Diffraction (SPPD), an effect which shows considerable promise for studying short-range order in magnetic solids and surfaces. The detection of photoelectron spin polarization in this experiment is provided by 3s-level multiplet splittings in 3d metals and their compounds; thus no external spin detector is required. Measurements on antiferromagnetic KMnF 3 show spin asymmetries of as high as 17% due to short-range order.

  16. Estimation of solid–liquid interfacial tension using curved surface of a soft solid

    PubMed Central

    Mondal, Subrata; Phukan, Monmee; Ghatak, Animangsu

    2015-01-01

    Unlike liquids, for crystalline solids the surface tension is known to be different from the surface energy. However, the same cannot be said conclusively for amorphous materials like soft cross-linked elastomers. To resolve this issue we have introduced here a direct method for measuring solid–liquid interfacial tension by using the curved surface of a solid. In essence, we have used the inner surface of tiny cylindrical channels embedded inside a soft elastomeric film for sensing the effect of the interfacial tension. When a liquid is inserted into the channel, because of wetting-induced alteration in interfacial tension, its thin wall deflects considerably; the deflection is measured with an optical profilometer and analyzed using the Föppl–von Kármán equation. We have used several liquids and cross-linked poly(dimethylsiloxane) as the solid to show that the estimated values of the solid–liquid interfacial tension matches with the corresponding solid–liquid interfacial energy reasonably well. PMID:26420871

  17. The Role of Surface Layer Processes in Solid Propellant Combustion.

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Satyanarayanan R.

    The qualitative multidimensional theory of composite solid propellant combustion based on the sandwich burning methodology was applied to certain specific problems: (a) burning rate enhancement by ferric oxide, (b) plateau burning behavior caused by binder melt flow effects, and (c) characterization of the combustion of new energetic oxidizers--ADN and HNIW. Exothermic reactions at the interfacial contact lines between AP particles and the binder in the surface layer of the burning propellant assume significance in the presence of ferric oxide, and control the burning rate. Binder melt flow covers adjacent AP particle surfaces increasingly at higher pressures, and disperses the O/F leading edge flames attached to coarse particles. It also causes fine AP/binder matrix areas on the surface not to support a steady premixed flame at intermediate pressures, resulting in an overall decrease in the burning rate with increasing pressure, which implies plateau or mesa effects. ADN self -deflagration rate is significantly higher than that of AP, and controls the sandwich burning rate to a great extent. The O/F flame of ADN and binder still behaves as rate limiting, although strongly supported by ADN self-deflagration. ADN melts and vaporizes substantially before the binder, allowing for the possibility of complex physical processes in the surface layer. The strong exothermic decomposition of HNIW at moderate temperatures causes the oxidizer particles in the surface layer to be the sites of burning rate control. The problems addressed in this study combinedly point to the significance of crucial surface layer processes under the situations of interest, and signal a need to characterize such processes directly and in greater detail.

  18. Lunar surface outgassing and alpha particle measurements

    SciTech Connect

    Lawson, S. L.; Feldman, W. C.; Lawrence, David J. ,; Moore, K. R.; Elphic, R. C.; Maurice, S.; Belian, Richard D.; Binder, Alan B.

    2002-01-01

    The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particle?; produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-2 18 (6.0 MeV, 3 minute half-life), and solid polonium-210 (5.3 MeV, 138 day half-life, but held up in production by the 21 year half-life of lead-210). These three nuclides are radioactive daughters from the decay of uranium-238.

  19. Measurement of solid precipitation with an optical disdrometer

    NASA Astrophysics Data System (ADS)

    Lempio, G. E.; Bumke, K.; Macke, A.

    2007-04-01

    A study about measurements of solid precipitation using an optical disdrometer is presented. The optical disdrometer is an improved version of the ODM 470 disdrometer. It allows to measure hydrometeors within a size range of 0.4 to 22 mm in diameter. The main advantage of this instrument is its ability to estimate accurately precipitation even under strong wind conditions (Großklaus, 1996). To measure solid precipitation a geometrical model was developed to determine the mean cross-sectional area of snow crystals for different predefined shapes and sizes. It serves to develop an algorithm, which relates the mean cross sectional area of snow crystals to their maximum dimension, liquid water content, and terminal velocity. The algorithm was applied to disdrometer measurements during winter 1999/2000 in Uppsala/Sweden. Resulting precipitation was compared to independent measurements of a Geonor gauge and to manual measurements. In terms of daily precipitation the disdrometer shows a reliable performance.

  20. Measuring and Plotting Surface-Contour Deviations

    NASA Technical Reports Server (NTRS)

    Aragon, Lino A.; Shuck, Thomas; Crockett, Leroy K.

    1987-01-01

    Hand-held device measures deviation of contour of surface from desired contour and provides output to x-y plotter. Carriage on device rolled along track representing desired contour, while spring-loaded stylus on device deflects perpendicularly to track to follow surface. Operator moves carriage of contour-measuring device on beamlike track. Stylus on carriage traces contour of surface above it. Carriage of measuring device holds transducer measuring cross-track displacement of surface from desired contour, and multiple-turn potentiometer measuring position along track.

  1. SSM - SOLID SURFACE MODELER, VERSION 6.0

    NASA Technical Reports Server (NTRS)

    Goza, S. P.

    1994-01-01

    The Solid Surface Modeler (SSM) is an interactive graphics software application for solid-shaded and wireframe three- dimensional geometric modeling. It enables the user to construct models of real-world objects as simple as boxes or as complex as Space Station Freedom. The program has a versatile user interface that, in many cases, allows mouse input for intuitive operation or keyboard input when accuracy is critical. SSM can be used as a stand-alone model generation and display program and offers high-fidelity still image rendering. Models created in SSM can also be loaded into other software for animation or engineering simulation. (See the information below for the availability of SSM with the Object Orientation Manipulator program, OOM, a graphics software application for three-dimensional rendering and animation.) Models are constructed within SSM using functions of the Create Menu to create, combine, and manipulate basic geometric building blocks called primitives. Among the simpler primitives are boxes, spheres, ellipsoids, cylinders, and plates; among the more complex primitives are tubes, skinned-surface models and surfaces of revolution. SSM also provides several methods for duplicating models. Constructive Solid Geometry (CSG) is one of the most powerful model manipulation tools provided by SSM. The CSG operations implemented in SSM are union, subtraction and intersection. SSM allows the user to transform primitives with respect to each axis, transform the camera (the user's viewpoint) about its origin, apply texture maps and bump maps to model surfaces, and define color properties; to select and combine surface-fill attributes, including wireframe, constant, and smooth; and to specify models' points of origin (the positions about which they rotate). SSM uses Euler angle transformations for calculating the results of translation and rotation operations. The user has complete control over the modeling environment from within the system. A variety of file

  2. SSM - SOLID SURFACE MODELER, VERSION 6.0

    NASA Technical Reports Server (NTRS)

    Goza, S. P.

    1994-01-01

    The Solid Surface Modeler (SSM) is an interactive graphics software application for solid-shaded and wireframe three- dimensional geometric modeling. It enables the user to construct models of real-world objects as simple as boxes or as complex as Space Station Freedom. The program has a versatile user interface that, in many cases, allows mouse input for intuitive operation or keyboard input when accuracy is critical. SSM can be used as a stand-alone model generation and display program and offers high-fidelity still image rendering. Models created in SSM can also be loaded into other software for animation or engineering simulation. (See the information below for the availability of SSM with the Object Orientation Manipulator program, OOM, a graphics software application for three-dimensional rendering and animation.) Models are constructed within SSM using functions of the Create Menu to create, combine, and manipulate basic geometric building blocks called primitives. Among the simpler primitives are boxes, spheres, ellipsoids, cylinders, and plates; among the more complex primitives are tubes, skinned-surface models and surfaces of revolution. SSM also provides several methods for duplicating models. Constructive Solid Geometry (CSG) is one of the most powerful model manipulation tools provided by SSM. The CSG operations implemented in SSM are union, subtraction and intersection. SSM allows the user to transform primitives with respect to each axis, transform the camera (the user's viewpoint) about its origin, apply texture maps and bump maps to model surfaces, and define color properties; to select and combine surface-fill attributes, including wireframe, constant, and smooth; and to specify models' points of origin (the positions about which they rotate). SSM uses Euler angle transformations for calculating the results of translation and rotation operations. The user has complete control over the modeling environment from within the system. A variety of file

  3. Chemical reactions on solid surfaces using molecular beam techniques

    NASA Astrophysics Data System (ADS)

    Palmer, R. L.

    1980-07-01

    Thermal energy molecular beams have been used to study chemical interactions with metal surfaces. Chemisorption of simple molecules such as H2, O2, CH4, C2Hx and CO was investigated on single and polycrystalline surfaces of Pt, Ni, Co, and Ag. Kinetic parameters and reaction mechanisms were determined for model catalytic reactions including CO and C2Hx oxidation and methanation from H2/CO mixtures. Chemical reactions of NOx with CO and D2 on Pt(111) and other surfaces have been surveyed and the kinetics of NO and O2 chemisorption have been measured. The theory of adsorption/desorption kinetics is reviewed and certain deficiencies identified.

  4. Lunar Surface Material - Spacecraft Measurements of Density and Strength

    NASA Technical Reports Server (NTRS)

    Jaffe, L. D.

    1969-01-01

    The relation of the density of the lunar surface layer to depth is probably best determined from spacecraft measurements of the bearing capacity as a function of depth. A comparison of these values with laboratory measurements of the bearing capacity of low-cohesion particulate materials as a function of the percentage of solid indicates that the bulk density at the lunar surface is about 1.1 grams per cubic centimeter and that it increases nearly linearly to about 1.6 grams per cubic centimeter at a depth of 5 centimeters.

  5. Lunar Surface Material - Spacecraft Measurements of Density and Strength

    NASA Technical Reports Server (NTRS)

    Jaffe, L. D.

    1969-01-01

    The relation of the density of the lunar surface layer to depth is probably best determined from spacecraft measurements of the bearing capacity as a function of depth. A comparison of these values with laboratory measurements of the bearing capacity of low-cohesion particulate materials as a function of the percentage of solid indicates that the bulk density at the lunar surface is about 1.1 grams per cubic centimeter and that it increases nearly linearly to about 1.6 grams per cubic centimeter at a depth of 5 centimeters.

  6. Surface fluctuations of liquids confined on flat and patterned solid substrates.

    PubMed

    Pottier, Basile; Verneuil, Emilie; Talini, Laurence; Pierre-Louis, Olivier

    2014-05-01

    We report experimental measurements of the surface fluctuations of micron-thick oil films spread onto a solid substrate. We use a recently developed optical technique based on the measurement of the deflection of a laser beam triggered by changes in the local surface slope. When the liquid is spread on a flat substrate, fluctuation dynamics slow down as the thickness is decreased, in quantitative agreement with previous predictions. In addition, we investigate the consequences on surface fluctuations of the patterning of the substrate with a rectangular grating. For liquid film thicknesses smaller than the typical wavelength probed, we demonstrate that surface fluctuations are modified by the underlying pattern: The shape of the fluctuation spectra varies periodically with the spatial position over the pattern and, in addition, the fluctuations become locally anisotropic. However, the spatially averaged spectrum is isotropic.

  7. Surface Specularity as an Indicator of Shock-induced Solid-liquid Phase Transitions in Tin

    SciTech Connect

    G. D. Stevens, S. S. Lutz, B. R. Marshall, W.D. Turley, et al.

    2007-12-01

    When highly polished metal surfaces melt upon release after shock loading, they exhibit features that suggest significant surface changes accompany the phase transition. The reflection of light from such surfaces changes from specular (pre-shock) to diffuse upon melting. Typical of this phenomenon is the loss of signal light in velocity interferometer system for any reflector (VISAR) measurements, which usually occurs at pressures high enough to melt the free surface. Unlike many other potential material phase-sensitive diagnostics (e.g., reflectometry, conductivity), that show relatively small (1%-10%) changes, the specularity of reflection provides a more sensitive and definitive (>10x) indication of the solid-liquid phase transition. Data will be presented that support the hypothesis that specularity changes indicate melt in a way that can be measured easily and unambiguously.

  8. Measuring solids concentration in stormwater runoff: comparison of analytical methods.

    PubMed

    Clark, Shirley E; Siu, Christina Y S

    2008-01-15

    Stormwater suspended solids typically are quantified using one of two methods: aliquot/subsample analysis (total suspended solids [TSS]) or whole-sample analysis (suspended solids concentration [SSC]). Interproject comparisons are difficult because of inconsistencies in the methods and in their application. To address this concern, the suspended solids content has been measured using both methodologies in many current projects, but the question remains about how to compare these values with historical water-quality data where the analytical methodology is unknown. This research was undertaken to determine the effect of analytical methodology on the relationship between these two methods of determination of the suspended solids concentration, including the effect of aliquot selection/collection method and of particle size distribution (PSD). The results showed that SSC was best able to represent the known sample concentration and that the results were independent of the sample's PSD. Correlations between the results and the known sample concentration could be established for TSS samples, but they were highly dependent on the sample's PSD and on the aliquot collection technique. These results emphasize the need to report not only the analytical method but also the particle size information on the solids in stormwater runoff.

  9. Measurements of muon-catalyzed dt fusion in solid HD

    NASA Astrophysics Data System (ADS)

    Porcelli, Tracy Ann

    1999-12-01

    The first measurement of muon catalyzed dt fusion ( dtm--> 4He + n + m- ) in solid HD at ~ 3 K has been performed. The theory describing the formation of the [(dtm)pe e] muonic molecule from the resonant reaction tm+HD-->[(dtm) pee] , a key process in the dt fusion cycle, can now be tested against the experimental results. Using an experimental technique which employs solid layers of hydrogen isotopes, the energy of molecular formation is determined via time of flight, and dt fusion time spectra in solid HD have been measured. The theory describing the resonant formation of the dtm muonic molecule is compared to the experimental results through Monte Carlo simulations. The energy dependent molecular formation rates calculated for HD at 3 K have been employed in the Monte Carlo with the resultant simulated fusion time spectra in fair agreement with the experimental results.

  10. Measurements of Muon Catalyzed dt Fusion in Solid HD

    NASA Astrophysics Data System (ADS)

    Porcelli, Tracy

    1999-05-01

    The first measurement of muon catalyzed dt fusion (dtμ arrow ^4He + n + μ^-) in solid HD at ~ 3 K has been performed. The theory describing the formation of the [(dtμ)pee)] muonic molecule from the resonant reaction tμ + HD arrow [(dtμ)pee], a key process in the dt fusion cycle, can now be tested against experimental results. Using an experimental technique which employs solid layers of hydrogen isotopes, the energy of molecular formation is determined via time of flight, and dt fusion time spectra in solid HD have been measured. The theory describing the resonant formation of the dtμ muonic molecule is compared to the experimental results through Monte Carlo simulations. The energy dependent molecular formation rates calculated for HD at 3 K have been employed in the Monte Carlo with the resultant fusion time spectra in fair agreement with the experimental results.

  11. Electrostatic Interaction of Long DNA Molecules with Solid State Surfaces

    NASA Astrophysics Data System (ADS)

    Li, Bingquan; Samuilov, Vladimir; Sokolov, Jonathan; Rafailovich, Miriam; Chu, Ben

    2004-03-01

    At low buffer concentration the electric charge of DNA molecules creates a strong electrostatic interaction and, as a result, a number of phenomena, such as the electro-hydrodynamic instability, partial adsorption at the buffer-semiconductor interface and stretching of DNA with the electric field. Long DNA molecules at the silicon substrate?buffer solution interface are very interesting objects for the electrical transport [1,2] and the mechanical properties, like entropic elasticity, studies. The system (DNA-substrate-electric field in the buffer solution) is very complicated. Due to the strong electrostatic interaction of DNA with the substrate, the image charge is generated, and the physical adsorption takes place. We have studied the S. Pombe genomic DNA of the order of 5 Mbp. Within a surface DNA is entropically partially recoiled due to electrostatic adsorption at a few points. While varying the direction of the low electric field the direction of the electroosmotic flow is changing and stretching the parts of DNA between the adsorption points. If the electric field is high enough, DNA is de-trapped and forms a compact coil. This behavior could be considered as an inverse mechanism of entropy trapping due to confined constrictions. In the case of the surface, DNA is recoiled and trapped in the stretched configuration in the deep energetic barrier by Si surface due to the strong electrostatic interaction. If the energy of the field is enough to overcome the barrier, DNA is detached. The Si surface could be considered as an analog of the entropic recoiling nanostructure. [1]. N. Pernodet, V. Samuilov, K. Shin, J. Sokolov, M.H. Rafailovich, D. Gersappe, B. Chu. DNA Electrophoresis on a Flat Surface, Physical Review Letters, 85 (2000) 5651-5654. [2] Y.-S. Seo, V.A. Samuilov, J. Sokolov, M. Rafailovich, B. Tinland, J. Kim, B. Chu. DNA separation at a liquid-solid interface, Electrophoresis, 23 (2002) 2618-2625.

  12. The solid surface combustion experiment aboard the USML-1 mission

    NASA Technical Reports Server (NTRS)

    Altenkirch, Robert A.; Sacksteder, Kurt; Bhattacharjee, Subrata; Ramachandra, Prashant A.; Tang, Lin; Wolverton, M. Katherine

    1994-01-01

    AA Experimental results from the five experiments indicate that flame spread rate increases with increasing ambient oxygen content and pressure. An experiment was conducted aboard STS-50/USML-1 in the solid Surface Combustion Experiment (SSCE) hardware for flame spread over a thin cellulosic fuel in a quiescent oxidizer of 35% oxygen/65% nitrogen at 1.0 atm. pressure in microgravity. The USML-1 test was the fourth of five planned experiments for thin fuels, one performed during each of five Space Shuttle Orbiter flights. Data that were gathered include gas- and solid-phase temperatures and motion picture flame images. Observations of the flame are described and compared to theoretical predictions from steady and unsteady models that include flame radiation from CO2 and H2O. Experimental results from the five esperiments indicate that flame spread rate increases with increasing ambient oxygen content and pressure. The brightness of the flame and the visible soot radiation also increase with increasing spread rate. Steady-state numerical predictions of temperature and spread rate and flame structure trends compare well with experimental results near the flame's leading edge while gradual flame evolution is captured through the unsteady model.

  13. Spreading characteristics of nanofluid droplets impacting onto a solid surface.

    PubMed

    Murshed, S M Sohel; de Castro, C A Nieto

    2011-04-01

    This paper reports an experimental investigation on the spreading characteristics of nanofluid droplets impinging on aluminum substrate under the influence of several key factors such as nanoparticle volume fraction, substrate temperature, and the Weber number. Sample nanofluid used is prepared by dispersing several volumetric concentrations (1 to 5%) of titanium dioxide nanoparticles in ethylene glycol. The entire dynamic process of each droplet collision with the substrate surface and the spreading phenomena is captured by using a high speed camera and then the transient spreading diameter and height of droplet are determined. It is found that the higher the concentration of nanoparticles the larger the spreading diameter of nanofluid droplet. As the surface temperature increases, the overall spreading diameter and height of nanofluid droplet significantly decreases and increases, respectively. At larger Weber number, the final spreading of the nanofluid droplet is also found to be larger than that of lower Weber number. Present results demonstrate that spreading characteristics of nanofluid droplets impacting onto solid surface are greatly influenced by each of the aforementioned factors.

  14. Positron dynamics in surface-charged solid argon

    SciTech Connect

    Jorgensen, L.V.; Merrison, J.P.; Deutch, B.I.; Charlton, M.; Jones, G.O.

    1995-10-15

    Studies have been made of the reemission of positrons incident at low energies upon solid argon to which electric fields were applied by charging an overlayer of molecular oxygen. An enhancement in positron reemission was observed which reached a maximum for an applied field of around 7 kV mm{sup {minus}1}. At this field strength the same yield was observed for implantation energies ranging from 1 to 10 keV, consistent with enhancement due to field-induced positron drift to the exit surface. At higher electric fields, the observed gradual decrease in enhancement was attributed to the heating of the positron energy distribution above the positronium formation threshold. Quantitative agreement with our experimental results has been obtained using a Monte Carlo simulation from which estimates for the positron diffusion length and mobility of 1.7(+2.0,{minus}0.4) {mu}m and 4.7(+2.9,{minus}0.4){times}10{sup {minus}3} m{sup 2} V{sup {minus}1} s{sup {minus}1}, respectively, have been derived. This model was also able to successfully reproduce previous results obtained using surface-charged argon {beta}{sup +} moderators. An abrupt and almost complete reduction in positron reemission was observed for applied surface potentials above a value which showed a weak dependence on film thickness.

  15. Surface free energy of a solid from contact angle hysteresis.

    PubMed

    Chibowski, Emil

    2003-04-25

    Nature of contact angle hysteresis is discussed basing on the literature data (Colloids Surf. A 189 (2001) 265) of dynamic advancing and receding contact angles of n-alkanes and n-alcohols on a very smooth surface of 1,1,2,-trichloro-1,2,2,-trifluoroethane (FC-732) film deposited on a silicon plate. The authors considered the liquid absorption and/or retention (swelling) processes responsible for the observed hysteresis. In this paper hysteresis is considered to be due to the liquid film left behind the drop during retreating of its contact line. Using the contact angle hysteresis an approach is suggested for evaluation of the solid surface free energy. Molecular spacing and the film structure are discussed to explain the difference in n-alkanes and n-alcohols behaviour as well as to explain the difference between dispersion free energy gamma(s)(d) and total surface free energy gamma(s)(tot) of FC-732, as determined from the advancing contact angles and the hysteresis, respectively.

  16. The hydrodynamics of bubble rise and impact with solid surfaces.

    PubMed

    Manica, Rogerio; Klaseboer, Evert; Chan, Derek Y C

    2016-09-01

    A bubble smaller than 1mm in radius rises along a straight path in water and attains a constant speed due to the balance between buoyancy and drag force. Depending on the purity of the system, within the two extreme limits of tangentially immobile or mobile boundary conditions at the air-water interface considerably different terminal speeds are possible. When such a bubble impacts on a horizontal solid surface and bounces, interesting physics can be observed. We study this physical phenomenon in terms of forces, which can be of colloidal, inertial, elastic, surface tension and viscous origins. Recent advances in high-speed photography allow for the observation of phenomena on the millisecond scale. Simultaneous use of such cameras to visualize both rise/deformation and the dynamics of the thin film drainage through interferometry are now possible. These experiments confirm that the drainage process obeys lubrication theory for the spectrum of micrometre to millimetre-sized bubbles that are covered in this review. We aim to bridge the colloidal perspective at low Reynolds numbers where surface forces are important to high Reynolds number fluid dynamics where the effect of the surrounding flow becomes important. A model that combines a force balance with lubrication theory allows for the quantitative comparison with experimental data under different conditions without any fitting parameter. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. The anomalous solid state decomposition of ammonium dinitramide: a matter of surface polarization.

    PubMed

    Rahm, Martin; Brinck, Tore

    2009-05-28

    Polarized dinitramide anions on the surface of solid ammonium dinitramide (ADN) have a decomposition barrier that is reduced by 16 kcal mol(-1) and explain the anomalous solid state decomposition of ADN.

  18. Solid state long range surface plasmon polariton single mode lasers

    NASA Astrophysics Data System (ADS)

    Karami Keshmarzi, Elham; Tait, R. Niall; Berini, Pierre

    2013-10-01

    Incorporation of a solid-state gain medium in the cladding of a Long Range Surface Plasmon Polariton (LRSPP) waveguide in order to create a single-mode near-infrared laser source is proposed. LRSPP Bragg gratings based on stepping the width of the metal strip are used to form the laser's cavity. Three laser configurations are presented: The first 2 lasers employ DBRs (Distributed Bragg Reflectors) in ECL (External Cavity Laser) architecture while the third is based on the DFB (Distributed Feedback) configuration. All 3 configurations are thermally tunable by heating the gratings directly by injecting current. The lasers are convenient to fabricate leading to inexpensive sources that could be used in optical integrated circuits or waveguide biosensors.

  19. Micro topography of different material surface by solid abrasive lapped at high speed

    NASA Astrophysics Data System (ADS)

    Tian, Chunlin; Yang, Jiandong; Fan, Jingfeng; Zhou, Huawen

    2007-12-01

    The principle of solid abrasives lapping is that the abrasives are fixed and made into a special lapping tool; the workpiece is lapped in high speed lapping machine tool. It possesses many advantages compared with traditional low speed lapping with particulate abrasives, e.g. high machining efficiency, low machining cost, high and stable machining accuracy. So the highly efficient lapping method has been paid close attention to. This paper made a study on surface micro topography of different material by solid abrasive lapped at high speed. In experiments the lapping technique parameter is fixed, and different workpiece which are made by T10 steel, carbide, ceramic glass and alumina ceramics are lapped. The surface micro topography is measured by SEM, from the measuring result, it can be known that there is some shallow scribe on the surface of T10 steel, and the obvious plastic deformation can be observed. The SEM pictures show that there is some scribe on the surface of ceramics glass after lapped, with more magnification times many micro cracking and some plastic hump can be observed on the scribe. These scribes and humps are first cause of depressing surface quality, and these micro cracking can result in a lot of diffuse reflection on workpiece surface, it decreases the glossiness of mirror surface. On the surface of alumina ceramics there are a lot of defects, the size of such defect is more than the scribe of abrasive, it can be sure that the defect is not produced by lapping, so the material quality is an important effect fact to surface macro topography. On the surface of carbide there are a little of scribe and air cavity, and the scribe is very shallow; the defect of powder metallurgy martial is the primary reason.

  20. Direct Measurement of the Surface Energy of Graphene.

    PubMed

    van Engers, Christian D; Cousens, Nico E A; Babenko, Vitaliy; Britton, Jude; Zappone, Bruno; Grobert, Nicole; Perkin, Susan

    2017-06-14

    Graphene produced by chemical vapor deposition (CVD) is a promising candidate for implementing graphene in a range of technologies. In most device configurations, one side of the graphene is supported by a solid substrate, wheras the other side is in contact with a medium of interest, such as a liquid or other two-dimensional material within a van der Waals stack. In such devices, graphene interacts on both faces via noncovalent interactions and therefore surface energies are key parameters for device fabrication and operation. In this work, we directly measured adhesive forces and surface energies of CVD-grown graphene in dry nitrogen, water, and sodium cholate using a modified surface force balance. For this, we fabricated large (∼1 cm(2)) and clean graphene-coated surfaces with smooth topography at both macro- and nanoscales. By bringing two such surfaces into contact and measuring the force required to separate them, we measured the surface energy of single-layer graphene in dry nitrogen to be 115 ± 4 mJ/m(2), which was similar to that of few-layer graphene (119 ± 3 mJ/m(2)). In water and sodium cholate, we measured interfacial energies of 83 ± 7 and 29 ± 6 mJ/m(2), respectively. Our work provides the first direct measurement of graphene surface energy and is expected to have an impact both on the development of graphene-based devices and contribute to the fundamental understanding of surface interactions.

  1. The measurement of surface gravity

    NASA Technical Reports Server (NTRS)

    Harrison, J. C.; Lacoste, L. J. B.

    1978-01-01

    LaCoste and Romberg G and D gravity meters are normally employed when attempting high precision measurement of gravity differences on land. The capabilities and limitations of these instruments are discussed.

  2. Solid Character of Membrane Ceramides: A Surface Rheology Study of Their Mixtures with Sphingomyelin

    PubMed Central

    Catapano, Elisa R.; Arriaga, Laura R.; Espinosa, Gabriel; Monroy, Francisco; Langevin, Dominique; López-Montero, Iván

    2011-01-01

    The compression and shear viscoelasticities of egg-ceramide and its mixtures with sphingomyelin were investigated using oscillatory surface rheology performed on Langmuir monolayers. We found high values for the compression and shear moduli for ceramide, compatible with a solid-state membrane, and extremely high surface viscosities when compared to typical fluid lipids. A fluidlike rheological behavior was found for sphingomyelin. Lateral mobilities, measured from particle tracking experiments, were correlated with the monolayer viscosities through the usual hydrodynamic relationships. In conclusion, ceramide increases the solid character of sphingomyelin-based membranes and decreases their fluidity, thus drastically decreasing the lateral mobilities of embedded objects. This mechanical behavior may involve important physiological consequences in biological membranes containing ceramides. PMID:22261061

  3. Changes in contact angle providing evidence for surface alteration in multi-component solid foods

    NASA Astrophysics Data System (ADS)

    Reinke, Svenja K.; Hauf, Katharina; Vieira, Josélio; Heinrich, Stefan; Palzer, Stefan

    2015-11-01

    Chocolate blooming, one of the major problems in the confectionery industry, is the formation of visible white spots or a greyish haze on the surface of chocolate products due to large sugar or fat crystals on the surface. This leads to aesthetic changes and deterioration of taste and thus large sales losses for the confectionery industry due to consumer complaints. Chocolate blooming is often related to migration of lipids or sugar molecules to the chocolate surface, where they recrystallize with an associated polymorphic change of crystal structure on the surface. The wetting behaviour from contact angle measurements gives further insight into surface properties and is needed to determine surface energies and to evaluate possible migration mechanisms and preferred pathways. Therefore, an equilibrium contact angle is needed which is not directly accessible and is influenced by surface texture and interaction between solid and test liquid. In this study, the surface of cocoa butter and conventional chocolates was characterized by measuring the contact angle with the sessile drop protocol. The influence of roughness, test liquid and pre-crystallization of the samples as well as the storage temperature were investigated. In case of no pre-crystallization, a change in surface properties due to storage at 20 °C was detected, whereas samples stored at 30 °C showed the same wetting behaviour as fresh samples. This is associated with polymorphic transformation from thermodynamically less stable crystals to more stable configurations.

  4. Analysis of measurements for solid state laser remote lidar system

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin

    1995-01-01

    The merits of using lidar systems for remote measurements of various atmospheric processes such as wind, turbulence, moisture, and aerosol concentration are widely recognized. Although the lidar technology has progressed considerably over the past two decades, significant research particularly in the area of solid state lidars remains to be conducted in order to fully exploit this technology. The work performed by the UAH (University of Alabama in Huntsville) personnel under this Delivery Order concentrated on analyses of measurements required in support of solid state laser remote sensing lidar systems which are to be designed, deployed, and used to measure atmospheric processes and constituents. UAH personnel has studied and recommended to NASA/MSFC the requirements of the optical systems needed to characterize the detection devices suitable for solid state wavelengths and to evaluate various heterodyne detection schemes. The 2-micron solid state laser technology was investigated and several preliminary laser designs were developed and their performance for remote sensing of atmospheric winds and clouds from a spaceborne platform were specified. In addition to the laser source and the detector, the other critical technologies necessary for global wind measurements by a spaceborne solid state coherent lidar systems were identified to be developed and demonstrated. As part of this work, an analysis was performed to determine the atmospheric wind velocity estimation accuracy using the line-of-sight measurements of a scanning coherent lidar. Under this delivery order, a computer database of materials related to the theory, development, testing, and operation of lidar systems was developed to serve as a source of information for lidar research and development.

  5. Measuring the Internal Environment of Solid Rocket Motors During Ignition

    NASA Technical Reports Server (NTRS)

    Weisenberg, Brent; Smith, Doug; Speas, Kyle; Corliss, Adam

    2003-01-01

    A new instrumentation system has been developed to measure the internal environment of solid rocket test motors during motor ignition. The system leverages conventional, analog gages with custom designed, electronics modules to provide safe, accurate, high speed data acquisition capability. To date, the instrumentation system has been demonstrated in a laboratory environment and on subscale static fire test motors ranging in size from 5-inches to 24-inches in diameter. Ultimately, this system is intended to be installed on a full-scale Reusable Solid Rocket Motor. This paper explains the need for the data, the components and capabilities of the system, and the test results.

  6. Communication: Fundamental measure theory for hard disks: fluid and solid.

    PubMed

    Roth, Roland; Mecke, Klaus; Oettel, Martin

    2012-02-28

    Two-dimensional hard-particle systems are rather easy to simulate but surprisingly difficult to treat by theory. Despite their importance from both theoretical and experimental points of view, theoretical approaches are usually qualitative or at best semi-quantitative. Here, we present a density functional theory based on the ideas of fundamental measure theory for two-dimensional hard-disk mixtures, which allows for the first time an accurate description of the structure of the dense fluid and the equation of state for the solid phase within the framework of density functional theory. The properties of the solid phase are obtained by freely minimizing the functional.

  7. Magnetostatic Surface Field Measurement Facility.

    DTIC Science & Technology

    1986-12-01

    COSATI CODES 1S. SUB ~JECT TERMS lContInue on reuerse if necessary and identify by bioct number) FIELD GROUP sue. GR. ,Ma gn et ic Fi eI ds 14 __2_4Aircraft...response of models up to two feet in size. Test measurements were made on metallic spheres and cylinders, and on a model F-106 aircraft over a 1-25 MHz...evaluations and Tim .- Peters made the measurements on the F-106 model aircraft . Special appreciation goes to Dr. Carl Baum of AFWL, who provided many of

  8. Instrumentation for Surface Flux Measurements

    DTIC Science & Technology

    2012-05-10

    National Park , she used the sonic and a Li-Cor C02-H20 analyzer at a height of 3 m to measure the vertical turbulent flux of C02 downwind of...SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) U. S. Army Research Office P.O. Box 12211 Research Triangle Park , NC 27709-2211 3. REPORT TYPE...and subgrid-scale array measurements In summer 2000 we lent 7 of the CSAT3 sonics to the National Center for Atmo- spheric Research (NCAR) for use in

  9. Low-activity solid waste measurements at Tokai Works

    SciTech Connect

    J. L. Parker; D. H. Beddingfield; H. O. Menlove

    1999-11-01

    There is significant interest in performing assay measurements of containerized low-activity solid waste. The authors have examined the cases of typical waste drum matrices containing small quantities of plutonium and fission products. They have discussed various measurement techniques and considered the advantages and disadvantages of each method. They present a new state-of-the-art passive neutron waste drum counter with minimum detectable mass limits far below those systems which they have previously fabricated.

  10. Aspheric Surface Measurement Using Capacitive Sensors

    PubMed Central

    Yuan, Daocheng; Zhao, Huiying; Tao, Xin; Li, Shaobo; Zhu, Xueliang; Zhang, Chupeng

    2017-01-01

    This paper proposes a new method for the measurement of spherical coordinates by using capacitive sensors as a non-contact probe solution of measurement of aspheric surfaces. The measurement of the average effect of the capacitive probe and the influence of capacitive probe tilting were studied with respect to an eccentric spherical surface. Based on the tested characteristic curve of the average effect of the sphere and probe, it was found that nonlinear and linear compensation resulted in high measurement accuracy. The capacitance probe was found to be trying to fulfill a need for performing nm-level precision measurement of aspheric electromagnetic surfaces. PMID:28604613

  11. Optical Measurements on Solid Specimens of Solid Rocket Motor Exhaust and Solid Rocket Motor Slag

    NASA Technical Reports Server (NTRS)

    Roberts, F. E., III

    1991-01-01

    Samples of aluminum slag were investigated to aid the Earth Science and Applications Division at the Marshall Space Flight Center (MSFC). Alumina from space motor propellant exhaust and space motor propellant slag was examined as a component of space refuse. Thermal emittance and solar absorptivity measurements were taken to support their comparison with reflectance measurements derived from actual debris. To determine the similarity between the samples and space motor exhaust or space motor slag, emittance and absorbance results were correlated with an examination of specimen morphology.

  12. Determination of protein surface excess on a liquid/solid interface by single-molecule counting.

    PubMed

    Li, Nan; Tang, Hui; Gai, Hongwei; Dong, Xiuling; Wang, Qi; Yeung, Edward S

    2009-08-01

    Determination of protein surface excess is an important way of evaluating the properties of biomaterials and the characteristics of biosensors. A single-molecule counting method is presented that uses a standard fluorescence microscope to measure coverage of a liquid/solid interface by adsorbed proteins. The extremely low surface excess of lysozyme and bovine serum albumin (BSA), in a bulk concentration range from 0.3 nmol L(-1) (0.02 microg mL(-1)) to 3 nmol L(-1) (0.2 microg mL(-1)), were measured by recording the counts of spatially isolated single molecules on either hydrophilic (glass) or hydrophobic (polydimethylsiloxane, PDMS) surfaces at different pH. The differences observed in amounts of adsorbed proteins under different experimental conditions can be qualitatively explained by the combined interactions of electrostatic and hydrophobic forces. This, in turn, implies that single-molecule counting is an effective way of measuring surface coverage at a liquid/solid interface.

  13. Optical and surface properties of optically transparent Li3 PO4 solid electrolyte layer for transparent solid batteries.

    PubMed

    Pat, Suat; Özen, Soner; Şenay, Volkan; Korkmaz, Şadan

    2016-07-01

    In this study, optical and surface properties of the optically transparent Li3 PO4 solid electrolyte layer for transparent solid battery have been investigated for the first time. To determine the optical properties, transmittance, absorbance, reflection, refractive index spectra, and optical band gap were determined by UV-Vis spectrophotometer and optical interferometer. The surface property of the transparent Li3 PO4 solid electrolyte was analyzed using atomic force microscopy. One another important parameter is contact angle (CA) surface free energy (SFE). CA and SFE were determined by optical tensiometer. These values probably are a most important parameter for polymer and hybrid battery performance. For the best performance, value of CA should be low. As a result, solid electrolyte layer is a highly transparent and it has a high wettability. SCANNING 38:317-321, 2016. © 2015 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

  14. Particle Engineering in Pharmaceutical Solids Processing: Surface Energy 
Considerations

    PubMed Central

    Williams, Daryl R.

    2015-01-01

    During the past 10 years particle engineering in the pharmaceutical industry has become a topic of increasing importance. Engineers and pharmacists need to understand and control a range of key unit manufacturing operations such as milling, granulation, crystallisation, powder mixing and dry powder inhaled drugs which can be very challenging. It has now become very clear that in many of these particle processing operations, the surface energy of the starting, intermediate or final products is a key factor in understanding the processing operation and or the final product performance. This review will consider the surface energy and surface energy heterogeneity of crystalline solids, methods for the measurement of surface energy, effects of milling on powder surface energy, adhesion and cohesion on powder mixtures, crystal habits and surface energy, surface energy and powder granulation processes, performance of DPI systems and finally crystallisation conditions and surface energy. This review will conclude that the importance of surface energy as a significant factor in understanding the performance of many particulate pharmaceutical products and processes has now been clearly established. It is still nevertheless, work in progress both in terms of development of methods and establishing the limits for when surface energy is the key variable of relevance. PMID:25876912

  15. Wetting theory for small droplets on textured solid surfaces

    PubMed Central

    Kim, Donggyu; Pugno, Nicola M.; Ryu, Seunghwa

    2016-01-01

    Conventional wetting theories on rough surfaces with Wenzel, Cassie-Baxter, and Penetrate modes suggest the possibility of tuning the contact angle by adjusting the surface texture. Despite decades of intensive study, there are still many experimental results that are not well understood because conventional wetting theory, which assumes an infinite droplet size, has been used to explain measurements of finite-sized droplets. Here, we suggest a wetting theory applicable to a wide range of droplet size for the three wetting modes by analyzing the free energy landscape with many local minima originated from the finite size. We find that the conventional theory predicts the contact angle at the global minimum if the droplet size is about 40 times or larger than the characteristic scale of the surface roughness, regardless of wetting modes. Furthermore, we obtain the energy barrier of pinning which can induce the contact angle hysteresis as a function of geometric factors. We validate our theory against experimental results on an anisotropic rough surface. In addition, we discuss the wetting on non-uniformly rough surfaces. Our findings clarify the extent to which the conventional wetting theory is valid and expand the physical understanding of wetting phenomena of small liquid drops on rough surfaces. PMID:27897194

  16. Wetting theory for small droplets on textured solid surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Donggyu; Pugno, Nicola M.; Ryu, Seunghwa

    2016-11-01

    Conventional wetting theories on rough surfaces with Wenzel, Cassie-Baxter, and Penetrate modes suggest the possibility of tuning the contact angle by adjusting the surface texture. Despite decades of intensive study, there are still many experimental results that are not well understood because conventional wetting theory, which assumes an infinite droplet size, has been used to explain measurements of finite-sized droplets. Here, we suggest a wetting theory applicable to a wide range of droplet size for the three wetting modes by analyzing the free energy landscape with many local minima originated from the finite size. We find that the conventional theory predicts the contact angle at the global minimum if the droplet size is about 40 times or larger than the characteristic scale of the surface roughness, regardless of wetting modes. Furthermore, we obtain the energy barrier of pinning which can induce the contact angle hysteresis as a function of geometric factors. We validate our theory against experimental results on an anisotropic rough surface. In addition, we discuss the wetting on non-uniformly rough surfaces. Our findings clarify the extent to which the conventional wetting theory is valid and expand the physical understanding of wetting phenomena of small liquid drops on rough surfaces.

  17. Contact-Angle Hysteresis Caused by a Random Distribution of Weak Heterogeneities on a Solid Surface.

    PubMed

    Öpik

    2000-03-15

    A model according to which contact-angle hysteresis arises as the result of a random distribution of irregularities on the solid surface is investigated on the basis of probability theory. An estimate is obtained of the mathematical expectation of the number of stable equilibria when the effective angle between the liquid-gas surface and the solid surface with which the liquid is in contact deviates from the value, say theta(0), which would obtain if the solid surface were uniform, i.e., free from irregularities. It is found that when the effective contact angle deviates from theta(0) by less than a critical value, then the expected number of stable equilibria increases exponentially with the length of the contact line; therefore such a contact angle can occur under static conditions. But if the deviation of the contact angle from theta(0) exceeds the critical value, then the expected number of stable equilibria decreases exponentially with the length of the contact line, so a stable equilibrium is not possible for a macroscopic length of the contact line. The method is applicable only if the random deviations of the spreading power (defined as the solid-gas surface tension minus the sum of the liquid-gas and liquid-solid surface tensions) from its average are sufficiently small. It is found that the critical deviation of the contact angle from theta(0) is, apart from a slowly varying logarithmic factor, proportional to H(2)rho(s), where H is a measure of the amplitude of the surface irregularities and rho(s) is the surface density (i.e., number per unit area) of the irregularities. This qualitative feature agrees with the results previously obtained by several other authors, and, moreover, there is a surprisingly close agreement of the proportionality factor with the results of some earlier work in which the method of statistical analysis was much less elaborate than here. The effect of the logarithmic factor is to make the critical deviation of the contact angle

  18. Imidazolium-based ionic liquids grafted on solid surfaces.

    PubMed

    Xin, Bingwei; Hao, Jingcheng

    2014-01-01

    Supported ionic liquids (SILs), which refer to ionic liquids (ILs) immobilized on supports, are among the most important derivatives of ILs. The immobilization process of ILs can transfer their desired properties to substrates. Combination of the advantages of ILs with those of support materials will derive novel performances while retaining properties of both moieties. SILs have been widely applied in almost all of fields involving ILs, and have brought about drastic expansion of the ionic liquid area. As green media in organic catalytic reactions, based on utilizing the ability of ILs to stabilize the catalysts, they have many advantages over free ILs, including avoiding the leaching of ILs, reducing their amount, and improving the recoverability and reusability of both themselves and catalysts. This has critical significance from both environmental and economical points of view. As novel functional materials in surface science and material chemistry, SILs are ideal surface modifying agents. They can modify and improve the properties of solids, such as wettability, lubricating property, separation efficiency and electrochemical response. With the achievements in the field of ILs, using magnetic nanoparticles (MNPs) to SILs has drawn increasing attention in catalytic reactions and separation technologies, and achieved substantial progress. The combination of MNPs and ILs renders magnetic SILs, which exhibit the unique properties of ILs as well as facile separation by an external magnetic field. In this article, we focus on imidazolium-based ILs covalently grafted to non-porous and porous inorganic materials. The excellent stability and durability of this kind of SILs offer a great advantage compared with free ILs and IL films physically adsorbed on substrates without covalent bonds. Including examples from our own research, we overview mainly the applications and achievements of covalent-linked SILs in catalytic reactions, surface modification, separation

  19. An effect of surface properties on detachment of adhered solid to cooling surface for formation of clathrate hydrate slurry

    NASA Astrophysics Data System (ADS)

    Daitoku, Tadafumi; Utaka, Yoshio

    In air-conditioning systems, it is desirable that the liquid-solid phase change temperature of a cool energy storage material is approximately 10 °C from the perspective of improving coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra-n-butylammonium Bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of the heat transfer surface properties on the scraping force for detachment of adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally.

  20. Dynamic contact angle measurements on superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Hyun; Kavehpour, H. Pirouz; Rothstein, Jonathan P.

    2015-03-01

    In this paper, the dynamic advancing and receding contact angles of a series of aqueous solutions were measured on a number of hydrophobic and superhydrophobic surfaces using a modified Wilhelmy plate technique. Superhydrophobic surfaces are hydrophobic surfaces with micron or nanometer sized surface roughness. These surfaces have very large static advancing contact angles and little static contact angle hysteresis. In this study, the dynamic advancing and dynamic receding contact angles on superhydrophobic surfaces were measured as a function of plate velocity and capillary number. The dynamic contact angles measured on a smooth hydrophobic Teflon surface were found to obey the scaling with capillary number predicted by the Cox-Voinov-Tanner law, θD3 ∝ Ca. The response of the dynamic contact angle on the superhydrophobic surfaces, however, did not follow the same scaling law. The advancing contact angle was found to remain constant at θA = 160∘, independent of capillary number. The dynamic receding contact angle measurements on superhydrophobic surfaces were found to decrease with increasing capillary number; however, the presence of slip on the superhydrophobic surface was found to result in a shift in the onset of dynamic contact angle variation to larger capillary numbers. In addition, a much weaker dependence of the dynamic contact angle on capillary number was observed for some of the superhydrophobic surfaces tested.

  1. A measuring system for surface roughness parameters

    NASA Astrophysics Data System (ADS)

    Han, Jinhong; Wang, Yunkai; Zhang, Xianfeng

    2006-11-01

    We designed a measurement and control system which can measure the surface roughness parameters with a Single Chip Micyoco (SCM) as its kernel. It uses an inductive transducer to pick up the data. The instrumental structure and the working principle are also introduced in this paper. The integrated hardware and software systems have been designed and improved. The prototype model was calibrated and the instrumental precision was analysed according to the measured data. In this system the surface roughness parameters can automatically be measured and controlled, such as data processing, determination of the reference line, disposal of the surface profile informations, display and print of the results etc.

  2. MPF Lander Measured Surface Pressure

    NASA Image and Video Library

    1997-10-14

    Here is a comparison of the most recent 24-hour met sessions. Note the general trend of increasing pressure with time into the mission. This indicates that the South polar cap is reducing, freeing CO2 into the atmosphere. Also note small pressure features around noon, which we think are "dust-devils." Sojourner spent 83 days of a planned seven-day mission exploring the Martian terrain, acquiring images, and taking chemical, atmospheric and other measurements. The final data transmission received from Pathfinder was at 10:23 UTC on September 27, 1997. Although mission managers tried to restore full communications during the following five months, the successful mission was terminated on March 10, 1998. http://photojournal.jpl.nasa.gov/catalog/PIA00976

  3. Lunar Surface Outgassing and Alpha Particle Measurements

    NASA Astrophysics Data System (ADS)

    Lawson, S. L.; Feldman, W. C.; Lawrence, D. J.; Moore, K. R.; Elphic, R. C.; Maurice, S.; Belian, R. D.; Binder, A. B.

    2002-01-01

    The Lunar Prospector Alpha Particle Spectrometer (LP APS) searched for lunar surface gas release events and mapped their distribution by detecting alpha particles produced by the decay of gaseous radon-222 (5.5 MeV, 3.8 day half-life), solid polonium-218 (6.0 MeV, 3 minute half-life), and solid polonium-210 (5.3 MeV, 138 day half-life, but held up in production by the 21 year half-life of lead-210). These three nuclides are radioactive daughters from the decay of uranium-238. Radon reaches the lunar surface either at areas of high soil porosity or where fissures release the trapped gases in which radon is entrained. Once released, the radon spreads out by "bouncing" across the surface on ballistic trajectories in a randomwalk process. The half-life of radon-222 allows the gas to spread out by several 100 km before it decays (depositing approximately half of the polonium-218 recoil nuclides on the lunar surface) and allows the APS to detect gas release events up to several days after they occur. The long residence time of the lead-210 precursor to polonium-210 allows the mapping of gas vents which have been active over the last approximately 60 years. Because radon and polonium are daughter products of the decay of uranium, the background level of alpha particle activity is a function of the lunar crustal uranium distribution.

  4. Theoretical model for adhesive friction between elastomers and rough solid surfaces

    NASA Astrophysics Data System (ADS)

    Momozono, Satoshi; Nakamura, Kenya; Kyogoku, Keiji

    2010-03-01

    A theoretical model for the adhesive friction between elastomers and rough solid surfaces is proposed on the basis of opening crack propagation processes at the boundary of the contact interfaces and the rate processes of formation of molecular bonds on the solid surface. This model, which is expressed as a product of the terms related to the two abovementioned processes, requires some measurable and fitted parameters such as the frictional shear strength expressed as a function of viscoelastic dissipation, rate-dependent elasticity, density of bonded molecular chains at a contact junction, critical velocity related to viscoelastic relaxation, and critical velocity related to the rate process of formation of molecular bonds on the solid surface. The friction-velocity relationship exhibits a remarkable fit to previously obtained experimental results for polymers such as engineering rubber, gels, and plastics (glassy polymers), and all fitting parameters are physically reasonable. The viscoelastic index "n" is also related to the "glass-to-rubber transition" of a nanometer-thick polymer layer for frictional behavior. Thus, from a practical viewpoint, this model can be used effectively for fitting the adhesive friction behavior of polymers.

  5. Impact of high-speed steam-droplet spray on solid surface

    NASA Astrophysics Data System (ADS)

    Sanada, Toshiyuki; Watanabe, Masao; Shirota, Minori; Yamase, Masao; Saito, Takayuki

    2008-07-01

    A novel technique for the generation of impact by a high-speed steam-droplet spray is proposed. Relatively low-pressure super-purified steam (0.1-0.2 MPa) is mixed with super-purified water in a nozzle, and then sprayed on a solid surface, which is located at approximately 10 mm from the nozzle. This spray is found to cause harsh erosion. The most striking result of this experiment is that the degree of erosion is strongly dependent on temperature; this dependence is hardly explained by the classical droplet impact theory. We recognize the occurrence of a strong focused rarefaction wave in the middle of the droplet; this rarefaction wave may cause cavitation. The existence of cavitation may be supported by the temperature susceptibility of erosion. We experimentally measure both the droplet velocity and diameter distributions by a Phase-Doppler Anemometer. We also numerically study the dynamics of a high-speed liquid droplet impact on a solid surface by solving the Euler equation using the conditions obtained by the experiments. We discuss the possibility of the formation of cavitation bubbles as the primary cause of the experimentally observed harsh erosion on a solid surface.

  6. Determination and application of the atomic geometries of solid surfaces

    NASA Astrophysics Data System (ADS)

    Duke, C. B.

    In order to calculate the electronic charge density and excitation spectra associated with a surface, the positions of the atomic constituents in the vicinity of the surface must be known. This paper is an assessment of the accuracy with which these positions can be determined by state-of-the-art analyses of experimental measurements, especially elastic low-energy electron diffraction, ion scattering spectroscopy (at both medium and high energies), and photoemission spectroscopy. The methodology is that of comparing the results of various techniques as applied to specific systems. Our major finding is that when carefully and accurately applied, the various methods provide structural results which are consistent to within about 0.1 Å. Perusal of the literature reveals larger discrepancies which, however, have exhibited a tendency to disappear as a function of increasing time once conflicting results became sufficiently precisely specified that the origin of the discrepancies could be identified and resolved. The examples of Pt(111), GaAs(110) and CO on Ni(100) provide explicit examples of the convergence of the various spectroscopies to common results with the passage of time. Finally, two applications of spectroscopically-determined surface structures are illustrated: the determination of surface states at the GaAs(110) surface and the description of the nature and consequences of Al replacement reactions at Al-semiconductor interfaces.

  7. Surface texture measurement for dental wear applications

    NASA Astrophysics Data System (ADS)

    Austin, R. S.; Mullen, F.; Bartlett, D. W.

    2015-06-01

    The application of surface topography measurement and characterization within dental materials science is highly active and rapidly developing, in line with many modern industries. Surface measurement and structuring is used extensively within oral and dental science to optimize the optical, tribological and biological performance of natural and biomimetic dental materials. Although there has historically been little standardization in the use and reporting of surface metrology instrumentation and software, the dental industry is beginning to adopt modern areal measurement and characterization techniques, especially as the dental industry is increasingly adopting digital impressioning techniques in order to leverage CAD/CAM technologies for the design and construction of dental restorations. As dental treatment becomes increasingly digitized and reliant on advanced technologies such as dental implants, wider adoption of standardized surface topography and characterization techniques will become evermore essential. The dental research community welcomes the advances that are being made in surface topography measurement science towards realizing this ultimate goal.

  8. Irreversible deposition/adsorption processes on solid surfaces

    NASA Astrophysics Data System (ADS)

    Schaaf, P.; Voegel, J.-C.; Senger, B.

    In this article, we summarize the knowledge in the field of irreversible deposition processes of large molecules or colloidal particles on solid surfaces. An irreversible adsorption process is defined as a process in which, once adsorbed, a particle can neither diffuse along, nor desorb from the surface. We first introduce the basic tools used in these studies, one of the most important being the concept of available surface function. General results relative to these processes are then presented. We discuss, in particular, the connection between the reduced variance of the number density fluctuations of adsorbed particles and the available surface function. We then review the main models which were introduced in the literature to account for these phenomena. They can be divided in two classes: (i) the models which are based entirely on statistical and geometrical grounds. The best known and most widely studied of them is the Random Sequential Adsorption (RSA) model which is discussed in details. For the processes in which gravity plays an important role one uses the Ballistic Deposition (BD) model. We also present models which are aimed at accounting for the behavior lying between the ballistic deposition and the RSA. (ii) The second type of models corresponds to those which take explicitly the diffusion of the particles in the vicinity of the adsorption plane into account. The results relative to these models, called diffusional models, are discussed in details. Finally, the last part of the review is devoted to experimental results. We show, in particular, that the Langmuir model, which is the most widely used model in the literature to account for the protein adsorption kinetics, does not predict correctly the experimental observations. We present and discuss in a critical way experimental evidence which seems to indicate the validity of the RSA and ballistic models. Cet article présente une synthèse des connaissances dans le domaine des processus d

  9. PREFACE: International Conference on Solid Films and Surfaces (ICSFS 2014)

    NASA Astrophysics Data System (ADS)

    Achete, C. A.; Almeida, C. M.; Cremona, M.; Rocca, M.; Stavale, F.

    2015-03-01

    Foreword The 17th ICSFS took place at the wonderful city of Rio de Janeiro, Brazil from the 8th to the 11th of September, 2014. The conference focused on recent advances in controlling and characterizing the physical and chemical properties of films and surfaces, with a particular emphasis on materials for electronic, photonic and spintronic applications. In addition, themes of bio-functionalized structures and devices were strongly discussed in the ICSFS, covering interdisciplinary nano and nano-bio science and technology. The conference has promoted, in various sub-fields of materials surfaces and thin films, an excellent forum for exchange of ideas, presentation of technical achievements and discussion of future directions in the field. In this volume of the IOP Conference Series: Materials Science and Engineering we are glad to present 11 peer-reviewed ICSFS contributing papers. The cross-disciplinary nature of conference topics is clearly reflected in these Proceedings' contents. The themes discussed ranged from those close to more traditional condensed matter physics, such as semiconductor surfaces to physical chemistry related issues. The Proceedings were organized in accordance with contributions presented at the Conference. We were glad with the presence of over 160 participants, including 24 invited and plenary talks and over 50 oral contributions. We strongly believe that these Proceedings will be useful for a wide audience of those interested in basic and applied surfaces and thin solid interfaces. Acknowledgment We would like to acknowledge the hard work, professional skills and efficiency of the team which oversaw the general organization, particularly of Dicom (Social Communication Division) from the National Institute of Metrology, Quality and Technology, Inmetro (Brazil). We also would like to thank all the invited speakers and session chairs for making the meeting such a great success. The Conference was supported and sponsored by Academia

  10. Embedded Sensors for Measuring Surface Regression

    NASA Technical Reports Server (NTRS)

    Gramer, Daniel J.; Taagen, Thomas J.; Vermaak, Anton G.

    2006-01-01

    The development and evaluation of new hybrid and solid rocket motors requires accurate characterization of the propellant surface regression as a function of key operational parameters. These characteristics establish the propellant flow rate and are prime design drivers affecting the propulsion system geometry, size, and overall performance. There is a similar need for the development of advanced ablative materials, and the use of conventional ablatives exposed to new operational environments. The Miniature Surface Regression Sensor (MSRS) was developed to serve these applications. It is designed to be cast or embedded in the material of interest and regresses along with it. During this process, the resistance of the sensor is related to its instantaneous length, allowing the real-time thickness of the host material to be established. The time derivative of this data reveals the instantaneous surface regression rate. The MSRS could also be adapted to perform similar measurements for a variety of other host materials when it is desired to monitor thicknesses and/or regression rate for purposes of safety, operational control, or research. For example, the sensor could be used to monitor the thicknesses of brake linings or racecar tires and indicate when they need to be replaced. At the time of this reporting, over 200 of these sensors have been installed into a variety of host materials. An MSRS can be made in either of two configurations, denoted ladder and continuous (see Figure 1). A ladder MSRS includes two highly electrically conductive legs, across which narrow strips of electrically resistive material are placed at small increments of length. These strips resemble the rungs of a ladder and are electrically equivalent to many tiny resistors connected in parallel. A substrate material provides structural support for the legs and rungs. The instantaneous sensor resistance is read by an external signal conditioner via wires attached to the conductive legs on the

  11. [Combustion temperature measurement of solid propellant by remote sensing FTIR].

    PubMed

    Li, Yan; Wang, Jun-De; Sun, Xiu-Yun; Zhou, Xue-Tie

    2004-08-01

    The combustion temperature of solid propellant was measured in this paper. Emission spectra of the combustion flame were collected with remote sensing FTIR at the resolution of 4 cm(-1). The combustion temperatures with the burning time were calculated from the maximum spectral line intensity and the molecular rotation-vibration spectra of HF molecule, respectively. Combustion temperatures at each time were all 1 788.8 K from the maximum spectral line intensity method. For comparison, the temperatures calculated from the molecular rotation-vibration spectra were 1 859.7, 1 848. 3, 1 804.0 and 1 782.7 K, respectively. Results show that the two methods are all dependable in measuring combustion temperature of solid propellant. But the maximum spectral line intensity method is more convenient and rapid than the other when the combustion is relatively stable.

  12. Hole-to-surface resistivity measurements.

    USGS Publications Warehouse

    Daniels, J.J.

    1983-01-01

    Hole-to-surface resistivity measurements over a layered volcanic tuff sequence illustrate procedures for gathering, reducing, and interpreting hole-to-surface resistivity data. The magnitude and direction of the total surface electric field resulting from a buried current source is calculated from orthogonal potential difference measurements for a grid of closely spaced stations. A contour map of these data provides a detailed map of the distribution of the electric field away from the drill hole. Resistivity anomalies can be enhanced by calculating the difference between apparent resistivities calculated from the total surface electric field and apparent resistivities for a layered earth model.-from Author

  13. Solid surface wetting and the deployment of drops in microgravity

    NASA Astrophysics Data System (ADS)

    Trinh, E. H.; Depew, J.

    1994-02-01

    The complete or partial deployment of liquid samples in low gravity is primarily influenced by the interfacial properties of the specific liquid and solid materials used because the overwhelming bias of the Earth gravitational acceleration is removed. This study addresses the engineering aspects of injecting and deploying drops of prescribed volume into an acoustic positioning chamber in microgravity. The specific problems of interest are the design, testing, and implementation of injector tips to be used in a simultaneously retracting dual-injector system in the Drop Physics Module microgravity experiment facility. Prior to release, the liquid to be deployed must be retained within a restricted area at the very end of the injectors under dynamic stimuli from the continuous injection flow as well as from the stepped motion of the injectors. The final released drop must have a well determined volume and negligible residual linear or angular momentum. The outcome of Earth-based short-duration low gravity experiments had been the selection of two types of injector tips which were flown as back-up parts. They were successfully utilized during the USML-1 Spacelab mission as the primary tips. The combination of a larger contact surface, liquid pinning with a sharp edge, and selective coating of strategic tip surfaces with a non-wetting compound has allowed a significant increase in the success rate of deployment of simple and compound drops of aqueous solutions of glycerol and silicone oil. The diameter of the samples studied in the Drop Physics Module range between 0.3 and 2.7 cm. The tests conducted on-orbit with a manually operated small device have allowed the calibration of the volume deployed for a few drop sizes. The design for improved tips to be used during the next USML flight is based on these results.

  14. Solid Surface Wetting and the Deployment of Drops in Microgravity

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Depew, J.

    1994-01-01

    The complete or partial deployment of liquid samples in low gravity is primarily influenced by the interfacial properties of the specific liquid and solid materials used because the overwhelming bias of the Earth gravitational acceleration is removed. This study addresses the engineering aspects of injecting and deploying drops of prescribed volume into an acoustic positioning chamber in microgravity. The specific problems of interest are the design, testing, and implementation of injector tips to be used in a simuttaneously retracting dual-injector system used in the Drop Physics Module microgravity experiment facility. Prior to release, the liquid to be deployed must be retained within a restricted area at the very end of the injectors even under dynamic stimuli due to continuous injection flow as well as to the stepped motion of the injectors, and the final released drop must have a well determined volume as well as negligible residual linear or angular momentum from the deployment process. The outcome of Earthbased short-duration low gravity experiments had been the selection of two types of injector tips which were flown as back-up parts and were successfully utilized during the USML-1 Spacelab mission. The combination of a larger contact surface, liquid pinning with a sharp edge, and selective coating of strategic tip surfaces with a non-wetting compound has allowed a significant increase in the success rate of deployment of simple and compound drops of aqueous solutions of glycerol and silicone oil. The diameter of the samples studied in the Drop Physics Module ranged between 0.3 and 2.7 cm. The tests conducted onsrbit with a manually operated small device have allowed the calibration of the volume deployed for a few drop sizes. The design for improved tips to be used during the next USML flight is based on these results.

  15. Solid surface wetting and the deployment of drops in microgravity

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Depew, J.

    1994-01-01

    The complete or partial deployment of liquid samples in low gravity is primarily influenced by the interfacial properties of the specific liquid and solid materials used because the overwhelming bias of the Earth gravitational acceleration is removed. This study addresses the engineering aspects of injecting and deploying drops of prescribed volume into an acoustic positioning chamber in microgravity. The specific problems of interest are the design, testing, and implementation of injector tips to be used in a simultaneously retracting dual-injector system in the Drop Physics Module microgravity experiment facility. Prior to release, the liquid to be deployed must be retained within a restricted area at the very end of the injectors under dynamic stimuli from the continuous injection flow as well as from the stepped motion of the injectors. The final released drop must have a well determined volume and negligible residual linear or angular momentum. The outcome of Earth-based short-duration low gravity experiments had been the selection of two types of injector tips which were flown as back-up parts. They were successfully utilized during the USML-1 Spacelab mission as the primary tips. The combination of a larger contact surface, liquid pinning with a sharp edge, and selective coating of strategic tip surfaces with a non-wetting compound has allowed a significant increase in the success rate of deployment of simple and compound drops of aqueous solutions of glycerol and silicone oil. The diameter of the samples studied in the Drop Physics Module range between 0.3 and 2.7 cm. The tests conducted on-orbit with a manually operated small device have allowed the calibration of the volume deployed for a few drop sizes. The design for improved tips to be used during the next USML flight is based on these results.

  16. Solid surface wetting and the deployment of drops in microgravity

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Depew, J.

    1994-01-01

    The complete or partial deployment of liquid samples in low gravity is primarily influenced by the interfacial properties of the specific liquid and solid materials used because the overwhelming bias of the Earth gravitational acceleration is removed. This study addresses the engineering aspects of injecting and deploying drops of prescribed volume into an acoustic positioning chamber in microgravity. The specific problems of interest are the design, testing, and implementation of injector tips to be used in a simultaneously retracting dual-injector system in the Drop Physics Module microgravity experiment facility. Prior to release, the liquid to be deployed must be retained within a restricted area at the very end of the injectors under dynamic stimuli from the continuous injection flow as well as from the stepped motion of the injectors. The final released drop must have a well determined volume and negligible residual linear or angular momentum. The outcome of Earth-based short-duration low gravity experiments had been the selection of two types of injector tips which were flown as back-up parts. They were successfully utilized during the USML-1 Spacelab mission as the primary tips. The combination of a larger contact surface, liquid pinning with a sharp edge, and selective coating of strategic tip surfaces with a non-wetting compound has allowed a significant increase in the success rate of deployment of simple and compound drops of aqueous solutions of glycerol and silicone oil. The diameter of the samples studied in the Drop Physics Module range between 0.3 and 2.7 cm. The tests conducted on-orbit with a manually operated small device have allowed the calibration of the volume deployed for a few drop sizes. The design for improved tips to be used during the next USML flight is based on these results.

  17. Surface-motility induction, attraction and hitchhiking between bacterial species promote dispersal on solid surfaces.

    PubMed

    Hagai, Efrat; Dvora, Reut; Havkin-Blank, Tal; Zelinger, Einat; Porat, Ziv; Schulz, Stefan; Helman, Yael

    2014-05-01

    The ability to move on solid surfaces provides ecological advantages for bacteria, yet many bacterial species lack this trait. We found that Xanthomonas spp. overcome this limitation by making use of proficient motile bacteria in their vicinity. Using X. perforans and Paenibacillus vortex as models, we show that X. perforans induces surface motility, attracts proficient motile bacteria and 'rides' them for dispersal. In addition, X. perforans was able to restore surface motility of strains that lost this mode of motility under multiple growth cycles in the lab. The described interaction occurred both on agar plates and tomato leaves and was observed between several xanthomonads and motile bacterial species. Thus, suggesting that this motility induction and hitchhiking strategy might be widespread and ecologically important. This study provides an example as to how bacteria can rely on the abilities of their neighboring species for their own benefit, signifying the importance of a communal organization for fitness.

  18. Low energy electron elastic reflection from solid surfaces

    NASA Astrophysics Data System (ADS)

    Starý, Vladimír.; Zemek, Josef

    2004-09-01

    Using our Monte-Carlo (MC) code, we calculated the ratio of the coefficients of elastic reflection of electrons from Si, SiO 2 and Au to those of Cu and Al in the electron energy range 0.2-1.0 and 1.5 keV (Au-Cu), respectively. The electron scattering was simulated by a single scattering model. For the MC calculations, we compared the elastic differential cross-sections calculated using a static field approximation with relativistic partial wave analysis on either the Thomas-Fermi-Dirac potential of free atoms (TFD model) or the Hartree-Fock-Wigner-Seitz (muffin-tin) potential of atoms in the solid state (HFWS model). The MC data were compared with the experimental values. For both models, reasonably good agreement for Si-Cu and SiO 2-Cu systems was found. In the Au-Cu system, better agreement was achieved using the TFD model. The addition of C in a surface interaction layer of 2-5 nm improves the agreement between simulated and experimental values for the Si-Al and Si-SiO 2 systems.

  19. Developments in measurement techniques for shock-loaded solids

    SciTech Connect

    Chhabildas, L.C.; Graham, R.A.

    1987-01-01

    Developments in measurement technique for study of wave profiles in shock-loaded solids over the past decade are reviewed and their influence examined. It is found that this period is characterized by considerable activity which has been concentrated on significant improvements to earlier developments. The most influential instrumental developments are noted and some perspective on the nature of the development of shock instrumentation is presented. An extensive reference list is included. 164 refs.

  20. Analysis of Rayleigh-Lamb Modes in Soft-solids with Application to Surface Wave Elastography

    NASA Astrophysics Data System (ADS)

    Benech, Nicolás; Grinspan, Gustavo; Aguiar, Sofía; Brum, Javier; Negreira, Carlos; tanter, Mickäel; Gennisson, Jean-Luc

    The goal of Surface Wave Elastography (SE) techniques is to estimate the shear elasticity of the sample by measuring the surface wave speed. In SE the thickness of the sample is often assumed to be infinite, in this way, the surface wave speed is directly linked to the sample's shear elasticity. However for many applications this assumption is not true. In this work, we study experimentally the Rayleigh-Lamb modes in soft solids of finite thickness to explore the optimal conditions for SWE. Experiments were carried out in three tissue mimicking phantoms of different thicknesses (10 mm, 20 mm and 60 mm) and same shear elasticity. The surface waves were generated at the surface of the phantom using piston attached to a mechanical vibrator. The central frequency of the excitation was varied between 60 Hz to 160 Hz. One component of the displacement field generated by the piston was measured at the surface and in the bulk of the sample trough a standard speckle tracking technique using a 256 element, 7.5 MHz central frequency linear array and an ultrasound ultrafast electronics. Finally, by measuring the phase velocity at each excitation frequency, velocity dispersion curves were obtained for each phantom. The results show that instead of a Rayleigh wave, zero order symmetric (S0) and antisymmetric (A0) Lamb modes are excited with this type of source. Moreover, in this study we show that due to the near field effects of the source, which are appreciable only in soft solids at low frequencies, both Lamb modes are separable in time and space. We show that while the Ao mode dominates close the source, the S0 mode dominates far away.

  1. Surface texture measurement for additive manufacturing

    NASA Astrophysics Data System (ADS)

    Triantaphyllou, Andrew; Giusca, Claudiu L.; Macaulay, Gavin D.; Roerig, Felix; Hoebel, Matthias; Leach, Richard K.; Tomita, Ben; Milne, Katherine A.

    2015-06-01

    The surface texture of additively manufactured metallic surfaces made by powder bed methods is affected by a number of factors, including the powder’s particle size distribution, the effect of the heat source, the thickness of the printed layers, the angle of the surface relative to the horizontal build bed and the effect of any post processing/finishing. The aim of the research reported here is to understand the way these surfaces should be measured in order to characterise them. In published research to date, the surface texture is generally reported as an Ra value, measured across the lay. The appropriateness of this method for such surfaces is investigated here. A preliminary investigation was carried out on two additive manufacturing processes—selective laser melting (SLM) and electron beam melting (EBM)—focusing on the effect of build angle and post processing. The surfaces were measured using both tactile and optical methods and a range of profile and areal parameters were reported. Test coupons were manufactured at four angles relative to the horizontal plane of the powder bed using both SLM and EBM. The effect of lay—caused by the layered nature of the manufacturing process—was investigated, as was the required sample area for optical measurements. The surfaces were also measured before and after grit blasting.

  2. Molecular dynamics analysis of a equilibrium nanoscale droplet on a solid surface with periodic roughness

    NASA Astrophysics Data System (ADS)

    Furuta, Yuma; Surblys, Donatas; Yamaguchi, Yastaka

    2016-11-01

    Molecular dynamics simulations of the equilibrium wetting behavior of hemi-cylindrical argon droplets on solid surfaces with a periodic roughness were carried out. The rough solid surface is located at the bottom of the calculation cell with periodic boundary conditions in surface lateral directions and mirror boundary condition at the top boundary. Similar to on a smooth surface, the change of the cosine of the droplet contact angle was linearly correlated to the potential well depth of the inter-atomic interaction between liquid and solid on a surface with a short roughness period while the correlation was deviated on one with a long roughness period. To further investigate this feature, solid-liquid, solid-vapor interfacial free energies per unit projected area of solid surface were evaluated by using the thermodynamic integration method in independent quasi-one-dimensional simulation systems with a liquid-solid interface or vapor-solid interface on various rough solid surfaces at a constant pressure. The cosine of the apparent contact angles estimated from the density profile of the droplet systems corresponded well with ones calculated from Young's equation using the interfacial energies evaluated in the quasi-one dimensional systems.

  3. Surface morphological response of crystalline solids to mechanical stresses and electric fields

    NASA Astrophysics Data System (ADS)

    Maroudas, Dimitrios

    2011-08-01

    Surface morphological evolution under the action of external fields is a fascinating topic that has attracted considerable attention within the surface science community over the past two decades. In addition to the interest in a fundamental understanding of field-induced nonlinear response and stability of surface morphology, the problem has been technologically significant in various engineering applications such as microelectronics and nanofabrication. In this report, we review theoretical progress in modeling the surface morphological response of stressed elastic solids under conditions that promote surface diffusion and of electrically conducting solids under surface electromigration conditions. A self-consistent model of surface transport and morphological evolution is presented that has provided the basis for the theoretical and computational work that is reviewed. According to this model, the surface morphological response of electrically conducting elastic solids to the simultaneous action of mechanical stresses and electric fields is analyzed. Emphasis is placed on metallic surfaces, including surfaces of voids in metallic thin films. Surfaces of stressed elastic solids are known to undergo morphological instabilities, such as the Asaro-Tiller or Grinfeld (ATG) instability that leads to emanation of crack-like features from the surface and their fast propagation into the bulk of the solid material. This instability is analyzed theoretically, simulated numerically, and compared with experimental measurements. The surface morphological evolution of electrically conducting, single-crystalline, stressed elastic solids under surface electromigration conditions is also examined. We demonstrate that, through surface electromigration, a properly applied and sufficiently strong electric field can stabilize the surface morphology of the stressed solid against both crack-like ATG instabilities and newly discovered secondary rippling instabilities; the effects of

  4. Surface morphological response of crystalline solids to mechanical stresses and electric fields

    NASA Astrophysics Data System (ADS)

    Maroudas, Dimitrios

    2011-08-01

    Surface morphological evolution under the action of external fields is a fascinating topic that has attracted considerable attention within the surface science community over the past two decades. In addition to the interest in a fundamental understanding of field-induced nonlinear response and stability of surface morphology, the problem has been technologically significant in various engineering applications such as microelectronics and nanofabrication. In this report, we review theoretical progress in modeling the surface morphological response of stressed elastic solids under conditions that promote surface diffusion and of electrically conducting solids under surface electromigration conditions. A self-consistent model of surface transport and morphological evolution is presented that has provided the basis for the theoretical and computational work that is reviewed. According to this model, the surface morphological response of electrically conducting elastic solids to the simultaneous action of mechanical stresses and electric fields is analyzed. Emphasis is placed on metallic surfaces, including surfaces of voids in metallic thin films.Surfaces of stressed elastic solids are known to undergo morphological instabilities, such as the Asaro-Tiller or Grinfeld (ATG) instability that leads to emanation of crack-like features from the surface and their fast propagation into the bulk of the solid material. This instability is analyzed theoretically, simulated numerically, and compared with experimental measurements. The surface morphological evolution of electrically conducting, single-crystalline, stressed elastic solids under surface electromigration conditions is also examined. We demonstrate that, through surface electromigration, a properly applied and sufficiently strong electric field can stabilize the surface morphology of the stressed solid against both crack-like ATG instabilities and newly discovered secondary rippling instabilities; the effects of

  5. Interactions of fragment ions of tetradecane with solid surfaces

    NASA Astrophysics Data System (ADS)

    Takaoka, Gikan H.; Takeuchi, Mitsuaki; Ryuto, Hiromichi; Imanaka, Kousuke; Hayashi, Kyohei

    2014-12-01

    Vapors of tetradecane (C14H30) were ionized by electron bombardment. The generated fragment ions such as C3H7, C6H13, and C12H25 ions were separated by an E × B filter (Wien filter) and accelerated toward Si(1 0 0) substrates. Thickness measurements showed that thin films were deposited on the Si substrates by C3H7- and C6H13-ion irradiation, although the Si substrate surface was predominantly sputtered by C12H25 ions. Rutherford backscattering spectroscopy showed that the irradiation damage by the fragment-ion beams decreased with the increasing molecular weight of the fragment ions at the same acceleration voltage. Furthermore, Raman spectra as well as X-ray photoelectron spectroscopy measurements showed that DLC films were formed by C3H7- and C6H13-ion irradiation with the film thickness being larger in case of C3H7. On the contrary, for C12H25-ion irradiation, chemical sputtering occurred by surface reactions of hydrogen and methyl radicals with silicon atoms. The chemical reaction at the irradiated substrate surface could be enhanced by the higher temperatures achieved by the high energy-density irradiation effect of the polyatomic ions.

  6. Techniques for Measuring Surface Potentials in Space

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Parker, Linda Neergaard

    2015-01-01

    Materials exposed to the space plasma environment charge to a net potential relative to the ambient plasma. The charging process is due to differential currents to the material surface that results in a net surface charge density. While this process is termed "spacecraft surface charging" when applied to aerospace hardware, it also applies to the surfaces of astronomical objects in direct contact with the space plasma environment including a number of planetary bodies, asteroids, and dust particles. The ability to measure surface potentials is important to many techniques used in conducting fundamental heliospheric science, spacecraft engineering operations, and space technology development activities. This presentation provides a survey of current technologies used to measure surface potentials of spacecraft and planetary bodies with examples of their application to space science and technology programs.

  7. Surface Temperature Measurements of Heterogeneous Explosives by IR Emission

    NASA Astrophysics Data System (ADS)

    Henson, B. F.; Funk, D. J.; Laabs, G. W.; Asay, B. W.

    1997-07-01

    Solid phase temperature is a key observable for understanding chemical and physical properties of energetic materials. Material decomposition during prolonged heating and the rate and mechanism of energy release during explosive ignition are both strongly coupled to the temperature field in the solid. Toward the end of addressing these issues we are pursuing the remote measurement of temperature by the quantitative collection of IR emission from the material surface. We present measurements of the integrated IR emission (1-5 mm) from both the heterogeneous explosive PBX 9501 and pure components at calibrated temperatures from 100C to 250C. The IR power emitted as a function of temperature is that expected of a black body, attenuated by a unique temperature-independent constant for each component which we report as the thermal emissivity of that component in this spectral region. In addition, we report preliminary measurements of the thermal transients from the unconfined surface of both PBX9501 and pressed HMX during ignition after periods of prolonged heating. We demonstrate that the measurement of IR emission in this spectral region provides both a reliable probe of static surface temperature and a unique observable of dynamic temperature change during ignition.

  8. The solid angle (geometry factor) for a spherical surface source and an arbitrary detector aperture

    DOE PAGES

    Favorite, Jeffrey A.

    2016-01-13

    It is proven that the solid angle (or geometry factor, also called the geometrical efficiency) for a spherically symmetric outward-directed surface source with an arbitrary radius and polar angle distribution and an arbitrary detector aperture is equal to the solid angle for an isotropic point source located at the center of the spherical surface source and the same detector aperture.

  9. Theoretical Foundation of Zisman's Empirical Equation for Wetting of Liquids on Solid Surfaces

    ERIC Educational Resources Information Center

    Zhu, Ruzeng; Cui, Shuwen; Wang, Xiaosong

    2010-01-01

    Theories of wetting of liquids on solid surfaces under the condition that van der Waals force is dominant are briefly reviewed. We show theoretically that Zisman's empirical equation for wetting of liquids on solid surfaces is a linear approximation of the Young-van der Waals equation in the wetting region, and we express the two parameters in…

  10. Theoretical Foundation of Zisman's Empirical Equation for Wetting of Liquids on Solid Surfaces

    ERIC Educational Resources Information Center

    Zhu, Ruzeng; Cui, Shuwen; Wang, Xiaosong

    2010-01-01

    Theories of wetting of liquids on solid surfaces under the condition that van der Waals force is dominant are briefly reviewed. We show theoretically that Zisman's empirical equation for wetting of liquids on solid surfaces is a linear approximation of the Young-van der Waals equation in the wetting region, and we express the two parameters in…

  11. The Measurement of Surface Rheological and Surface Adhesive Properties using Nanosphere Embedment

    NASA Astrophysics Data System (ADS)

    Hutcheson, Stephen; McKenna, Gregory

    2008-03-01

    In previous work, we determined the actual rheological behavior at the surface of a polystyrene film with nanometer scale resolution by applying a viscoelastic contact mechanics model to experimental data in the literature. The goal of our current research is to build upon this analysis and use nanosphere embedment experiments to probe the nanorheological behavior of polymer surfaces near the glass transition, in the melt state and in the solid rubbery state. An atomic force microscope (AFM) is used to measure the embedment depth as nanoparticles are pulled into the surface by the thermodynamic work of adhesion. The results show that, with properly designed experiments, both the surface adhesion properties and the surface rheological properties can be extracted from nanosphere embedment rates. We include work on a phase separated copolymer and a commercially available polydimethylsiloxane (PDMS) rubber.

  12. Bloodstain age analysis: toward solid state fluorescent lifetime measurements

    NASA Astrophysics Data System (ADS)

    Guo, Kevin; Zhegalova, Natalia; Achilefu, Samuel; Berezin, Mikhail Y.

    2013-03-01

    One of the most pressing unsolved challenges in forensic science is the determination of time since deposition (TSD) of bloodstains at crime scenes. Despite a number of high profile cases over the past couple hundred years involving controversy over TSD methods, no reliable quantitative method has been established. We present here an approach that has yet to be explored by forensic scientist: measuring the fluorescence lifetime of solid-state blood. Such a method would allow for on-site measurements of bloodstains utilizing the appropriate device, and would allow for rapid results returned in real-time to investigators.

  13. Measuring the Softness of an Athletic Surface.

    ERIC Educational Resources Information Center

    Brody, Howard

    1992-01-01

    Uses the context of sports surfaces to discuss the qualities of a surface that will produce a shock-absorbing effect. Discusses experiments to measure the shock-absorbing properties from two theoretical perspectives. Describes necessary equipment for the experiments. (MDH)

  14. Tuning Solid Surfaces from Hydrophobic to Superhydrophilic by Submonolayer Surface Modification

    SciTech Connect

    Meng, Sheng; Zhang, Zhenyu; Kaxiras, Efthimios

    2006-01-01

    Molecular-scale understanding and manipulation of the wetting behavior of water on solids remains a fundamental challenge. Using diamond as a model system, we show that the naturally hydrophobic behavior of a hydrogen-terminated C(111) surface can be manipulated by replacing the H termination with a monolayer of adsorbate. In particular, a mixed monolayer of 1 3 Na and 2 3 F atoms leads to superhydrophilic behavior, as shown by first-principles calculations. The physical origin of the superhydrophilic behavior is attributed to the ionic nature of the Na adatoms, which mediate the right degree of binding strength between water molecules and the substrate.

  15. Effect of surfactant surface coverage on formation of solid lipid nanoparticles (SLN).

    PubMed

    Helgason, T; Awad, T S; Kristbergsson, K; McClements, D J; Weiss, J

    2009-06-01

    The effect of surfactant surface coverage on formation and stability of Tween 20 stabilized tripalmitin solid lipid nanoparticles (SLN) was investigated. A lipid phase (10% w/w tripalmitin) and an aqueous phase (2% w/w Tween 20, 10 mM phosphate buffer, pH 7) were heated to 75 degrees C and then homogenized using a microfluidizer. The resulting oil-in-water emulsion was kept at a temperature (37 degrees C) above the crystallization temperature of the tripalmitin to prevent solidification of emulsion droplets, and additional surfactant at various concentrations (0-5% w/w Tween 20) was added. Droplets were then cooled to 5 degrees C to initiate crystallization and stored at 20 degrees C for 24 h. Particle size and/or aggregation were examined visually and by light scattering, and crystallization behavior was examined by differential scanning calorimetry (DSC). Excess Tween 20 concentration remaining in the aqueous phase was measured by surface tensiometry. Emulsion droplets after homogenization had a mean particle diameter of 134.1+/-2.0 nm and a polydispersity index of 0.08+/-0.01. After cooling to 5 degrees C at low Tween 20 concentrations, SLN dispersions rapidly gelled due to aggregation of particles driven by hydrophobic attraction between insufficiently covered lipid crystal surfaces. Upon addition of 1-5% w/w Tween 20, SLN dispersions became increasingly stable. At low added Tween 20 concentration (<1% w/w) the SLN formed gels but only increased slightly at higher surfactant concentrations (>1% w/w). The Tween 20 concentration in the aqueous phase decreased after tripalmitin crystallization suggesting additional surfactant adsorption onto solid surfaces. At higher Tween 20 concentrations, SLN had increasingly complex crystal structures as evidenced by the appearance of additional thermal transition peaks in the DSC. The results suggest that surfactant coverage at the interface may influence crystal structure and stability of solid lipid nanoparticles via

  16. Time evolution of reflective thermal lenses and measurement of thermal diffusivity in bulk solids.

    PubMed

    Doiron, Serge; Haché, Alain

    2004-07-20

    A simple method for optically measuring the thermal diffusivity of solids is demonstrated. The thermal displacement created on a substrate by a focused laser beam is determined from the divergence that it induces in a weak probe beam. The dynamics of the surface lens and the amplitude of the probe beam's divergence are then used to determine the thermal diffusivity of the substrate. Several materials that span a wide range of thermal properties are studied.

  17. A Portable, High Resolution, Surface Measurement Device

    NASA Technical Reports Server (NTRS)

    Ihlefeld, Curtis M.; Burns, Bradley M.; Youngquist, Robert C.

    2012-01-01

    A high resolution, portable, surface measurement device has been demonstrated to provide micron-resolution topographical plots. This device was specifically developed to allow in-situ measurements of defects on the Space Shuttle Orbiter windows, but is versatile enough to be used on a wide variety of surfaces. This paper discusses the choice of an optical sensor and then the decisions required to convert a lab bench optical measurement device into an ergonomic portable system. The necessary trade-offs between performance and portability are presented along with a description of the device developed to measure Orbiter window defects.

  18. Solid-state coherent laser radar wind shear measuring systems

    NASA Technical Reports Server (NTRS)

    Huffaker, R. Milton

    1992-01-01

    Coherent Technologies, Inc. (CTI) was established in 1984 to engage in the development of coherent laser radar systems and subsystems with applications in atmospheric remote sensing, and in target tracking, ranging and imaging. CTI focuses its capabilities in three major areas: (1) theoretical performance and design of coherent laser radar system; (2) development of coherent laser radar systems for government agencies such as DoD and NASA; and (3) development of coherent laser radar systems for commercial markets. The topics addressed are: (1) 1.06 micron solid-state coherent laser radar system; (2) wind measurement using 1.06 micron system; and flashlamp-pumped 2.09 micron solid-state coherent laser radar system.

  19. Solid Test Meal to Measure the Gastric Emptying with Magnetogastrography

    SciTech Connect

    Reynaga-Ornelas, M. G.; Roca-Chiapas, J. M. de ls; Cordova-Fraga, T.; Bernal, J. J.; Sosa, M.

    2008-08-11

    The gastric emptying is the time of evacuating the food ingested from the stomach to the duodenum in a controlled rate. Diverse studies express the results of the gastric emptying in form of half-time (t{sub 1/2}). The Magnetogastrography (MGG) is a biomagnetic technique that has the advantage of not being invasive, radiation free and does not interfere with the privacy of the subject. The objective was to analyze the magnetic signal of magnetic tracers mixed in a solid food to measure gastric emptying using Magnetogastrography. The ingested test meal displayed a magnetic signal, which served to obtain the signal registered by the fluxgate and the peristaltic contractions could be calculated while the stomach was emptying. The solid food product developed results to work satisfactorily in magnetogastrography.

  20. Preparation of stable silica surfaces for surface forces measurement

    NASA Astrophysics Data System (ADS)

    Ren, Huai-Yin; Mizukami, Masashi; Kurihara, Kazue

    2017-09-01

    A surface forces apparatus (SFA) measures the forces between two surfaces as a function of the surface separation distance. It is regarded as an essential tool for studying the interactions between two surfaces. However, sample surfaces used for the conventional SFA measurements have been mostly limited to thin (ca. 2-3 μm) micas, which are coated with silver layers (ca. 50 nm) on their back, due to the requirement of the distance determination by transmission mode optical interferometry called FECO (fringes of equal chromatic order). The FECO method has the advantage of determining the absolute distance, so it should be important to increase the availability of samples other than mica, which is chemically nonreactive and also requires significant efforts for cleaving. Recently, silica sheets have been occasionally used in place of mica, which increases the possibility of surface modification. However, in this case, the silver layer side of the sheet is glued on a cylindrical quartz disc using epoxy resin, which is not stable in organic solvents and can be easily swollen or dissolved. The preparation of substrates more stable under severe conditions, such as in organic solvents, is necessary for extending application of the measurement. In this study, we report an easy method for preparing stable silica layers of ca. 2 μm in thickness deposited on gold layers (41 nm)/silica discs by sputtering, then annealed to enhance the stability. The obtained silica layers were stable and showed no swelling in organic solvents such as ethanol and toluene.

  1. Preparation of stable silica surfaces for surface forces measurement.

    PubMed

    Ren, Huai-Yin; Mizukami, Masashi; Kurihara, Kazue

    2017-09-01

    A surface forces apparatus (SFA) measures the forces between two surfaces as a function of the surface separation distance. It is regarded as an essential tool for studying the interactions between two surfaces. However, sample surfaces used for the conventional SFA measurements have been mostly limited to thin (ca. 2-3 μm) micas, which are coated with silver layers (ca. 50 nm) on their back, due to the requirement of the distance determination by transmission mode optical interferometry called FECO (fringes of equal chromatic order). The FECO method has the advantage of determining the absolute distance, so it should be important to increase the availability of samples other than mica, which is chemically nonreactive and also requires significant efforts for cleaving. Recently, silica sheets have been occasionally used in place of mica, which increases the possibility of surface modification. However, in this case, the silver layer side of the sheet is glued on a cylindrical quartz disc using epoxy resin, which is not stable in organic solvents and can be easily swollen or dissolved. The preparation of substrates more stable under severe conditions, such as in organic solvents, is necessary for extending application of the measurement. In this study, we report an easy method for preparing stable silica layers of ca. 2 μm in thickness deposited on gold layers (41 nm)/silica discs by sputtering, then annealed to enhance the stability. The obtained silica layers were stable and showed no swelling in organic solvents such as ethanol and toluene.

  2. Chemistry of the silica surface: liquid-solid reactions of silica gel with trimethylaluminum.

    PubMed

    Li, Jianhua; DiVerdi, Joseph A; Maciel, Gary E

    2006-12-27

    The reaction of trimethylaluminum and dry, high-surface-area (500 m2/g) silica gel in a mixed slurry was studied using multinuclear, solid-state NMR spectroscopy. The products of the initial reaction were characterized, and their progress through subsequent washing with diethyl ether and reactions with measured amounts of water was followed. The quantitative distribution of different chemical forms of carbon deposited on the silica surface by the initial reaction was measured. The products of the initial reaction are dominated by methyl species of the types Al(CH3)n (with Si-O-Al linkages), Si-O-CH3, and (Si-O)4-nSi(CH3)n; aluminum is seen to exist predominantly as a five-coordinate species. Subsequent treatment with diethyl ether fails to remove any surface species, but instead the ether becomes strongly associated with the surface and highly resistant to removal. Stepwise additions of water hydrolyze the Al-CH3 and Si-O-CH3 moieties, leading to conversion of five-coordinate aluminum to four- and six-coordinate aluminum, and affect the partial release of the surface-associated diethyl ether; Si-CH3 moieties remain. The effect of aromatic and saturated solvents on the initial reaction was examined and found to cause a small but significant change in the distribution of products. Structures of aluminum-centered species on the silica surface consistent with the spectroscopic data are proposed.

  3. Temporal coherence of high-order harmonics generated at solid surfaces

    NASA Astrophysics Data System (ADS)

    Hemmers, D.; Behmke, M.; Karsch, S.; Keyling, J.; Major, Z.; Stelzmann, C.; Pretzler, G.

    2014-07-01

    We present interferometric measurements of the temporal coherence of high-order harmonics generated by reflection of a titanium sapphire laser off a solid surface. It is found that the coherence length of the harmonic emission is significantly reduced compared with the bandwidth limited case. To identify the responsible mechanism, the acquired data were analyzed by means of particle-in-cell simulations, whose results show good agreement between the calculated spectra and the measured coherence times. We show that the observed broadening can be understood consistently by the occurrence of a Doppler shift induced by the moving plasma surface, which is dented by the radiation pressure of the laser pulse. In this case, this Doppler effect would also lead to positive chirp of the emitted radiation.

  4. Surface heat transfer coefficient, heat efficiency, and temperature of pulsed solid-state lasers

    SciTech Connect

    Mann, K.; Weber, H.

    1988-08-01

    The temperature of solid-state lasers is a critical parameter. Efficiency and output power are strongly influenced by it. The two parameters which determine the temperature are the heat generation efficiency (HGE) and the surface heat transfer coefficient (SHTC) of the laser rod. These parameters allow the scaling of the rod temperature up to high pumping powers. Moreover, from the temperature inside the rod, the temperature gradients and the mechanical stress can be evaluated. Using transient temperature measurements, the SHTC and the HGE were determined for air- and water-cooled Nd:YAG and alexandrite lasers. The SHTC can be confirmed by theoretical considerations.

  5. Relaxation of surface tension in the liquid-solid interfaces of Lennard-Jones liquids.

    PubMed

    Lukyanov, Alex V; Likhtman, Alexei E

    2013-11-19

    We have established the surface tension relaxation time in the liquid-solid interfaces of Lennard-Jones (LJ) liquids by means of direct measurements in molecular dynamics (MD) simulations. The main result is that the relaxation time is found to be almost independent of the molecular structures and viscosity of the liquids (at 70-fold change) used in our study and lies in such a range that in slow hydrodynamic motion the interfaces are expected to be at equilibrium. The implications of our results for the modeling of dynamic wetting processes and interpretation of dynamic contact angle data are discussed.

  6. Tribology of thin wetting films between bubble and moving solid surface.

    PubMed

    Karakashev, Stoyan I; Stöckelhuber, Klaus W; Tsekov, Roumen; Phan, Chi M; Heinrich, Gert

    2014-08-01

    This work shows a successful example of coupling of theory and experiment to study the tribology of bubble rubbing on solid surface. Such kind of investigation is reported for the first time in the literature. A theory about wetting film intercalated between bubble and moving solid surface was developed, thus deriving the non-linear evolution differential equation which accounted for the friction slip coefficient at the solid surface. The stationary 3D film thickness profile, which appears to be a solution of the differential equation, for each particular speed of motion of the solid surface was derived by means of special procedure and unique interferometric experimental setup. This allowed us to determine the 3D map of the lift pressure within the wetting film, the friction force per unit area and the friction coefficient of rubbing at different speeds of motion of the solid surface. Thus, we observed interesting tribological details about the rubbing of the bubble on the solid surface like for example: 1. A regime of mixed friction between dry and lubricated friction exists in the range of 6-170 μm/s, beyond which the rubbing between the bubble and solid becomes completely lubricated and passes through the maximum; 2. The friction coefficient of rubbing has high values at very small speeds of solid's motion and reduces substantially with the increase of the speed of the solid motion until reaching small values, which change insignificantly with the further increase of the speed of the solid. Despite the numerous studies on the motion of bubble/droplet in close proximity to solid wall in the literature, the present investigation appears to be a step ahead in this area as far as we were able to derive 3D maps of the bubble close to the solid surface, which makes the investigation more profound.

  7. Coherent methods for measuring ophthalmic surfaces

    NASA Astrophysics Data System (ADS)

    Rottenkolber, Matthias; Podbielska, Halina

    1996-01-01

    Topographic analysis of the ophthalmic surfaces is an important task. Especially recently, when a laser assisted refractive surgery becomes more and more popular in a daily clinical praxis. Ophthalmologists need to know exact corneal parameters as a basis for proper operational approach, as well as for monitoring of the post-operative process. The fitting of the contact lenses can be more accurate when topography of both, cornea and contacts, can be precisely measured. We develop new coherent methods for measuring of the topography of curved optical surfaces. One of the proposed techniques is based on interferometry with a special distance measurement unit and spatial phase shifting interferogram evaluation. The other one uses deflectometry with spatial carrier frequency. The sensitivity of this method is adjustable and thus it closes the gap between the white light and interferometric measuring methods. The techniques proposed here can be suitable for measurement of the contact lenses or corneal surface.

  8. Wind noise measured at the ground surface.

    PubMed

    Yu, Jiao; Raspet, Richard; Webster, Jeremy; Abbott, Johnpaul

    2011-02-01

    Measurements of the wind noise measured at the ground surface outdoors are analyzed using the mirror flow model of anisotropic turbulence by Kraichnan [J. Acoust. Soc. Am. 28(3), 378-390 (1956)]. Predictions of the resulting behavior of the turbulence spectrum with height are developed, as well as predictions of the turbulence-shear interaction pressure at the surface for different wind velocity profiles and microphone mounting geometries are developed. The theoretical results of the behavior of the velocity spectra with height are compared to measurements to demonstrate the applicability of the mirror flow model to outdoor turbulence. The use of a logarithmic wind velocity profile for analysis is tested using meteorological models for wind velocity profiles under different stability conditions. Next, calculations of the turbulence-shear interaction pressure are compared to flush microphone measurements at the surface and microphone measurements with a foam covering flush with the surface. The measurements underneath the thin layers of foam agree closely with the predictions, indicating that the turbulence-shear interaction pressure is the dominant source of wind noise at the surface. The flush microphones measurements are intermittently larger than the predictions which may indicate other contributions not accounted for by the turbulence-shear interaction pressure.

  9. Probing the surface structure of divalent transition metals using surface specific solid-state NMR spectroscopy.

    PubMed

    Mason, Harris E; Harley, Stephen J; Maxwell, Robert S; Carroll, Susan A

    2012-03-06

    Environmental and geochemical systems containing paramagnetic species could benefit by using nuclear magnetic resonance (NMR) spectroscopy due to the sensitivity of the spectral response to small amounts paramagnetic interactions. In this study, we apply commonly used solid-state NMR spectroscopic methods combined with chemometrics analysis to probe sorption behavior of the paramagnetic cations Cu(2+) and Ni(2+)at the amorphous silica surface. We exploit the unique properties of paramagnets to derive meaningful structural information in these systems at low, environmentally relevant cation surface loadings by comparing the NMR response of sorption samples to paramagnetic free samples. These data suggest that a simple sorption model where the cation sorbs as inner sphere complexes at negatively charged, deprotonated silanol sites is appropriate. These results help constrain sorption models that are used to describe metal fate and transport.

  10. Contact angle measurement on rough surfaces.

    PubMed

    Meiron, Tammar S; Marmur, Abraham; Saguy, I Sam

    2004-06-15

    A new method for the measurement of apparent contact angles at the global energy minimum on real surfaces has been developed. The method consists of vibrating the surface, taking top-view pictures of the drop, monitoring the drop roundness, and calculating the contact angle from the drop diameter and weight. The use of the new method has been demonstrated for various rough surfaces, all having the same surface chemistry. In order to establish the optimal vibration conditions, the proper ranges for the system parameters (i.e., drop volume, vibration time, frequency of vibration, and amplitude of vibration) were determined. The reliability of the method has been demonstrated by the fact that the ideal contact angles of all surfaces, as calculated from the Wenzel equation using the measured apparent contact angles, came out to be practically identical. This ideal contact angle has been compared with three methods of calculation from values of advancing and receding contact angles.

  11. Desorption and sputtering on solid surfaces by low-energy multicharged ions

    NASA Astrophysics Data System (ADS)

    Motohashi, K.

    2009-11-01

    Desorption and sputtering on solid surfaces interacting with slow multicharged ions were studied by two different experimental methods: time-of-flight secondary ion mass spectrometry (TOF-SIMS) coupled with low-energy ion scattering spectroscopy (LEIS), and optical emission spectroscopy (OES) of secondary particles. Spectra reveal the anisotropic angular dependence of proton emission on an Al surface interacting with Arq+ (q = 8 and 14) ions at the incidence angle of ~0.5° (tangential angle to the surface). Simultaneous spectra of a GaN surface, scattering Ar+ ions and scattering protons reveal the kinetic energy distribution of Ar6+ (15 keV, ~10°) and the dependence of the protons on the kinetic energy of Ar+. Spectra of secondary particles, conducted on a Ti surface irradiated with Ar3+ ions (30 keV) at normal-incidence angle, reveal the mean velocity < v⊥ > of sputtered Ti* substrate atoms perpendicular to the surface, measured by analyzing intensity decay as a function of distance from the surface.

  12. X-Ray Opacity Measurements of Solid Density Plasmas

    NASA Astrophysics Data System (ADS)

    Wark, Justin; Preston, Thomas; Ciricosta, Orlando; Vinko, Sam; Hollebon, Patrick; Chung, Hyun-Kyung; Burian, Thomas; Chalupsky, Jaromir; Vozda, Vojtech; Hall, Frank; Spindloe, Christopher; Zastrau, Ulf; Dakovski, Georgi; Minitti, Michael

    2016-10-01

    Accurate opacity measurements of dense plasmas are scarce, in part owing to the difficulty in creating samples that are uniform in density and temperature, and the associated undertaking of an opacity measurement on a time-scale short compared with disassembly. Here we demonstrate that x-ray opacity information can be obtained from emissivity measurements of solid-density targets of varying but known thickness, irradiated by a sub-100-fsec x-ray pulse from LCLS. As the emission is generated by the creation of core-holes created by the FEL, and they are rapidly filled on a femtosecond time-scale, information is gleaned before any hydrodynamic motion. Comparision with simulations based on the SCFLY atomic-kinetics code reveal that the time-integrated emission data can provide a strong constraint on the opacity under well-defined conditions of density and temperature, and further demonstrate that the technique is relatively insensitive to x-ray pulse-length and spatial distribution. As an example we present measurements of the K-shell opacity of a solid-density magnesium plasma for all ion stages up to helium-like.

  13. Theoretical model of droplet wettability on a low-surface-energy solid under the influence of gravity.

    PubMed

    Yonemoto, Yukihiro; Kunugi, Tomoaki

    2014-01-01

    The wettability of droplets on a low surface energy solid is evaluated experimentally and theoretically. Water-ethanol binary mixture drops of several volumes are used. In the experiment, the droplet radius, height, and contact angle are measured. Analytical equations are derived that incorporate the effect of gravity for the relationships between the droplet radius and height, radius and contact angle, and radius and liquid surface energy. All the analytical equations display good agreement with the experimental data. It is found that the fundamental wetting behavior of the droplet on the low surface energy solid can be predicted by our model which gives geometrical information of the droplet such as the contact angle, droplet radius, and height from physical values of liquid and solid.

  14. Particle velocity and solid volume fraction measurements with a new capacitive flowmeter at the Solid/Gas Flow Test Facility. [Glass beads

    SciTech Connect

    Bobis, J.P.; Porges, K.G.A.; Raptis, A.C.; Brewer, W.E.; Bernovich, L.T.

    1986-08-01

    The performance of a new capacitive flowmeter has been assessed experimentally in a gas-entrained solid flow stream at the Argonne National Laboratory (ANL) Solid/Gas Flow Test Facility (S/GFTF) for solid feedrates in the range of 0.5 to 2 kg/s and solid-gas loadings up to 22, corresponding to a range of solid volume fractions extending from 0.004 to 0.016. Two types of nonintrusive instruments using the capacitive principle were fabricated at ANL and installed in the horizontal leg of a 12.3 m test section to sense the solids. An improved electrode geometry designed to maximize the coverage of the duct interior while minimizing the readout error due to a nonuniform electric field, was incorporated for one spoolpiece with the sensing electrodes on the outside surface of a ceramic liner and for another spoolpiece with the sensing electrodes mounted flush with the duct inside surface. The capacitive instruments measured the solid volume fraction and the average particle velocity. The results are compared with time-of-flight measurements of short-lived radioactive particles that duplicate closely the size and density of the 1000..mu.. glass beads used in these flow tests. Results show that the solid volume fraction measurements agree with the theoretical models presented and that the particle velocity deduced from the cross-correlation scheme agreed to within 5% of the irradiated particle velocity technique for the 21 to 31 m/s range generated with the S/GFTF. 43 refs., 36 figs., 19 tabs.

  15. Surface roughness measurement with laser triangulation

    NASA Astrophysics Data System (ADS)

    Bai, Fuzhong; Zhang, Xiaoyan; Tian, Chaoping

    2016-09-01

    A surface roughness measurement method is introduced in the paper, which is based on laser triangulation and digital image processing technique. In the measuring system, we use the line-structured light as light source, microscope lens and high-accuracy CCD sensor as displacement sensor as well. In addition, the working angle corresponding to the optimal sensitivity is considered in the optical structure design to improve the measuring accuracy. Through necessary image processing operation for the light strip image, such as center-line extraction with the barycenter algorithm, Gaussian filtering, the value of roughness is calculated. A standard planing surface is measured experimentally with the proposed method and the stylus method (Mitutoyo SJ-410) respectively. The profilograms of surface appearance are greatly similar in the shape and the amplitude to two methods. Also, the roughness statistics values are close. The results indicate that the laser triangulation with the line-structured light can be applied to measure the surface roughness with the advantages of rapid measurement and visualized display of surface roughness profile.

  16. Discrete transistor measuring and matching using a solid core oven.

    PubMed

    Inkinen, M; Mäkelä, K; Vuorela, T; Palovuori, K

    2013-03-01

    This paper presents transistor measurements done at a constant temperature. The aim in this research was to develop a reliable and repeatable method for measuring and searching transistor pairs with similar parameters, as in certain applications it is advantageous to use transistors from the same production batch due to the significant variability in batches from different manufacturers. Transistor manufacturing methods are well established, but due to the large variability in tolerance, not even transistors from the same manufacturing batch have identical properties. Transistors' electrical properties are also strongly temperature-dependent. Therefore, when measuring transistor properties, the temperature must be kept constant. For the measurement process, a solid-core oven providing stable temperature was implemented. In the oven, the base-to-emitter voltage (VBE) and DC-current gain (β) of 32 transistors could be measured simultaneously. The oven's temperature was controlled with a programmable thermostat, which allowed accurate constant temperature operation. The oven is formed by a large metal block with an individual chamber for each transistor to be measured. Isolation of individual transistors and the highly thermally conductive metal core structure prevent thermal coupling between transistors. The oven enables repeatable measurements, and thus measurements between different batches are comparable. In this research study, the properties of over 5000 transistors were measured and the variance of the aforementioned properties was analyzed.

  17. Discrete transistor measuring and matching using a solid core oven

    NASA Astrophysics Data System (ADS)

    Inkinen, M.; Mäkelä, K.; Vuorela, T.; Palovuori, K.

    2013-03-01

    This paper presents transistor measurements done at a constant temperature. The aim in this research was to develop a reliable and repeatable method for measuring and searching transistor pairs with similar parameters, as in certain applications it is advantageous to use transistors from the same production batch due to the significant variability in batches from different manufacturers. Transistor manufacturing methods are well established, but due to the large variability in tolerance, not even transistors from the same manufacturing batch have identical properties. Transistors' electrical properties are also strongly temperature-dependent. Therefore, when measuring transistor properties, the temperature must be kept constant. For the measurement process, a solid-core oven providing stable temperature was implemented. In the oven, the base-to-emitter voltage (VBE) and DC-current gain (β) of 32 transistors could be measured simultaneously. The oven's temperature was controlled with a programmable thermostat, which allowed accurate constant temperature operation. The oven is formed by a large metal block with an individual chamber for each transistor to be measured. Isolation of individual transistors and the highly thermally conductive metal core structure prevent thermal coupling between transistors. The oven enables repeatable measurements, and thus measurements between different batches are comparable. In this research study, the properties of over 5000 transistors were measured and the variance of the aforementioned properties was analyzed.

  18. The heat capacity of water near solid surfaces

    NASA Astrophysics Data System (ADS)

    Vučelić, V.; Vučelić, D.

    1983-11-01

    Anomalous heat capacities of water at solid/water interfaces have been obtained. The solids vary from inorganic (zeolites, porous class, silica gel, activated carbon) to biological (protein lysozyme and adrenal gland). Water heat capacities at all interfaces exhibit the same pattern. At room temperature the small values are close to ice and increase with temperature, reaching the value of free water between 380 and 440 K.

  19. Distance Measurements between Homonuclear Spins in Rotating Solids

    NASA Astrophysics Data System (ADS)

    Weintraub, O.; Vega, S.; Hoelger, C.; Limbach, H. H.

    The effective Hamiltonian of the "simple excitation for the dephasing of the rotational-echo amplitudes" (SEDRA) experiment has been derived. This experiment enables the determination of the strength of the dipolar interaction of a homonuclear spin pair in a solid, rotating at the magic angle, and thus provides a way to measure internuclear distances. The dipolar decay of the rotational-echo amplitudes of powder samples, generated by a set of π pulses, is measured together with the echo decay that is not influenced by the dipolar interaction. The latter is measured by the transverse-echo SEDRA experiment that refocuses the SEDRA decay. The Floquet theory approach is utilized to evaluate the effective Hamiltonians that describe the behavior of the spin systems. The influence of the chemical-shift anisotropy parameters of the interacting spins on the effective SEDRA Hamiltonian is also discussed. Results of Δ S/ S0 SEDRA experiments on the 15N spin pair in solid 3(5)-methyl-5(3) -phenylpyrazole- 15N 2 are shown and compared with exact calculations. The data suggest a nuclear distance between the nitrogen atoms of 1.385 ± 0.025 Å.

  20. Precise displacement measurement for a local surface.

    PubMed

    Yeh, Sheng Lih; Lin, Shyh Tsong; Chang, Yu Hsin

    2009-11-01

    An optical measurement method to get the in-plane and out-of-plane displacements of a local surface using a laser is proposed. The proposed method simultaneously derives the in-plane and out-of-plane displacements by measuring the shift of interference fringes formed by scattered beams. The average errors of the in-plane and out-of-plane displacement measurements are significantly smaller than 10 nm. Moreover, the proposed method uses only low-cost optical elements.

  1. Implementing landfill surfaces methane monitoring for the municipal solid waste landfill NSPS/EG

    SciTech Connect

    Huitric, R.; Banaji, J.

    1996-11-01

    The United States Environmental Protection Agency`s (USEPA) Municipal Solid Waste Landfill New Source Performance Standard (NSPS) and Emission Guidelines (EG) implements a landfill surface methane performance standard to verify emissions control effectiveness. The standard requires that periodic measures of surface gases along a predesignated route be less than 500 ppm methane at any point. During rule proposal, SWANA`s Landfill Gas Management Division (LFGMD) had advocated a performance standard as a more economic and effective alternative to the very prescriptive requirements first proposed by the USEPA in 1991. However, LFGMD recommended an averaged rather than a point source measure of the surface gases. Under the final NSPS rule, the landfill surface gas must be tested along the landfill`s perimeter and along interior routes each quarter. The interior routes must be aligned such that no route portion is more than 30 meters from any other portion. Exemptions are allowed for hazardous areas. A portable methane detector meeting USEPA`s Method 21 requirements is used to continuously sample air pumped from a probe or wand placed between 5 and 10 centimeters of the ground surface as a technician walks along a route. This paper addresses various implementation issues and discusses the development of possible monitoring alternatives, as allowed by the rule.

  2. Study of solid surface interactions with binary liquid mixtures and liquid crystals

    NASA Astrophysics Data System (ADS)

    Polak, Robert Dale

    The adsorption profile of a binary liquid mixture against a solid substrate was studied using an optical probe. The effective surface field was controlled by partially coating one half of the glass surface with octadecyltrichlorosilane, while the other half remained bare. On the bare surface, one component of the binary liquid mixture was strongly adsorbed to the surface, and, in the one-phase region, adsorption could be observed far from the bulk transition temperature. This adsorption scales as expected by a normal surface transition in which the surface orders at a higher temperature than the bulk. On the partially coated surface, the adsorption could only be observed very near the bulk critical temperature. Over the course of the first several days of the experiment, the adsorption profile changed, but it eventually became stable. Scaling analysis of the stable surface suggests the possibility that the surface was in the crossover region between normal and ordinary (where the surface and bulk order at the same temperature) surface transitions. In a separate series of experiments, the interaction between a nematic liquid crystal and substrate was studied, in particular, the energetic cost to deviate the surface director from its preferred orientation. To accurately determine the energetic cost, denoted by the polar anchoring coefficient W, of a typical alignment layer/liquid crystal was measured using three techniques. The first is the 'high-electric-field' (HEF) technique was found to give the largest value of W. In the course of the study, the HEF technique was improved by no longer requiring the measurement of capacitance of the sample liquid crystal cell. Also, the source of the large value of W is detected, and a protocol was developed to determine the reliability of the results given by the HEF technique. Two other techniques are used to determine W: the measurement of capacitance in a magnetic field and the measurement of the Frederiks transition at

  3. Synthesis of thiolated glycosaminoglycans and grafting to solid surfaces.

    PubMed

    Köwitsch, Alexander; Jurado Abreu, Mauricio; Chhalotre, Ankur; Hielscher, Martin; Fischer, Steffen; Mäder, Karsten; Groth, Thomas

    2014-12-19

    Glycosaminoglycans (GAGs) with varying degree of sulfation were chemically modified to obtain thiolated analogues (tGAGs) for subsequent surface grafting on vinyl-terminated self-assembled monolayers. Thiolation was achieved by the use of the disulfide containing crosslinker 3,3'-dithiobis(propanoic hydrazide) and subsequent reduction of the disulfide with dithiothreitol. Two different molar ratios of the crosslinker were used for conjugation. The tGAGs were characterized by (1)H-NMR, Raman and flow-field-flow-fractionation (A4F) to determine the chemical composition, structure and molecular weight of the products. Ellman's reagent was used to quantify the thiol concentration of tGAGs. The tGAGs were immobilized onto vinyl-terminated glass and silicon via thiol-ene reaction. This was achieved by homogeneous immobilization from solution as well as with microcontact printing and exposure to UV light. The results of water contact angle measurement (WCA), ellipsometry and confocal laser scanning microscopy (CLSM) demonstrated that the resulting surface coverage was dependent on the degree of thiolation of GAGs.

  4. From Single Bubbles on Solid Surfaces to Massive Bubbly Flow During Decompression Sickness

    NASA Astrophysics Data System (ADS)

    Karapantsios, T. D.; Kostoglou, M.; Evgenidis, S. P.

    2008-06-01

    Gas bubbles can be generated on solid surfaces covered by a liquid as a result of desorption of dissolved gases when the liquid becomes supersaturated with respect to dissolved gases. This work starts from basic phenomena controlling single bubble growth on a solid surface, extends to growth of multiple adjacent bubbles and their subsequent detachment from the surface into the liquid and, finally, copes with the detection and characterization of multiple bubbles flowing with the liquid (bubbly flow). Apparently, this is a very broad topic and can not be dealt with in just one report. As regards bubble growth, here only the case of thermal degassing is examined in which bubbles are produced locally on a hot spot surrounded by cold liquid layers. Thermal degassing is more general than decompression degassing (in fact, it encompasses it) since in addition to mass transfer involves also heat transfer processes. As regards bubbly flows the emphasis is on novel techniques that allow measurement of gas/liquid fractions and bubble size distributions at conditions such as those met during Decompression Sickness (DCS) in human veins and arteries.

  5. Apparatus for measuring surface particulate contamination

    DOEpatents

    Woodmansee, Donald E.

    2002-01-01

    An apparatus for measuring surface particulate contamination includes a tool for collecting a contamination sample from a target surface, a mask having an opening of known area formed therein for defining the target surface, and a flexible connector connecting the tool to the mask. The tool includes a body portion having a large diameter section defining a surface and a small diameter section extending from the large diameter section. A particulate collector is removably mounted on the surface of the large diameter section for collecting the contaminants. The tool further includes a spindle extending from the small diameter section and a spool slidingly mounted on the spindle. A spring is disposed between the small diameter section and the spool for biasing the spool away from the small diameter section. An indicator is provided on the spindle so as to be revealed when the spool is pressed downward to compress the spring.

  6. Measurement of elastic nonlinearity of soft solid with transient elastography

    NASA Astrophysics Data System (ADS)

    Catheline, S.; Gennisson, J.-L.; Fink, M.

    2003-12-01

    Transient elastography is a powerful tool to measure the speed of low-frequency shear waves in soft tissues and thus to determine the second-order elastic modulus μ (or the Young's modulus E). In this paper, it is shown how transient elastography can also achieve the measurement of the nonlinear third-order elastic moduli of an Agar-gelatin-based phantom. This method requires speed measurements of polarized elastic waves measured in a statically stressed isotropic medium. A static uniaxial stress induces a hexagonal anisotropy (transverse isotropy) in solids. In the special case of uniaxially stressed isotropic media, the anisotropy is not caused by linear elastic coefficients but by the third-order nonlinear elastic constants, and the medium recovers its isotropic properties as soon as the uniaxial stress disappears. It has already been shown how transient elastography can measure the elastic (second-order) moduli in a media with transverse isotropy such as muscles. Consequently this method, based on the measurement of the speed variations of a low-frequency (50-Hz) polarized shear strain waves as a function of the applied stress, allows one to measure the Landau moduli A, B, C that completely describe the third-order nonlinearity. The several orders of magnitude found among these three constants can be justified from the theoretical expression of the internal energy.

  7. Measurement of Gas-Surface Accommodation

    NASA Astrophysics Data System (ADS)

    Trott, W. M.; Rader, D. J.; Castañeda, J. N.; Torczynski, J. R.; Gallis, M. A.

    2008-12-01

    Thermal accommodation coefficients have been determined for a variety of gas-surface combinations using an experimental apparatus developed to measure both the pressure dependence of the conductive heat flux and the variation of gas density between parallel plates separated by a gas-filled gap. Effects of gas composition, surface roughness and surface contamination have been examined with this system, and the behavior of gas mixtures has also been explored. Results are discussed in comparison with previous parallel-plate experimental studies as well as numerical simulations.

  8. Thermal transport study across interface “nanostructured solid surface / fluid” by photoacoustic technique

    NASA Astrophysics Data System (ADS)

    Voitenko, K.; Isaiev, M.; Pastushenko, A.; Andrusenko, D.; Kuzmich, A.; Lysenko, V.; Burbelo, R.

    2017-01-01

    In the paper the experimental study of heat transport across the interface “porous silicon/liquid” by photoacoustic technique is reported. Two cases with and without liquid covering of porous silicon surface were considered. Thermal perturbations were excited at the surface of porous silicon as a result of absorption of the light with modulated intensity. The resulting thermal-elastic stresses arising in the system were registered with piezoelectric transducer. The amplitude-frequency dependencies of the voltage on the piezoelectric electrodes were measured. The presence of the liquid film leads to decreasing of the amplitude of photoacoustic signal as a result of the thermal energy evacuation from the porous silicon into the liquid. The experimental dependencies were fitted with the results of simulation that takes into account heat fluxes separation at the porous silicon/liquid interface. With the presented method one can precisely measure heat fluxes transferred from the solid into contacting fluid. Moreover, the presented approach can be easily adopted for the thermal conductivity study of the different nanofluids as well as thermal resistance at the interface nanostructured solid/fluid.

  9. Dielectric Measurements of Solid ^4He in Vycor

    NASA Astrophysics Data System (ADS)

    Day, James; Beamish, John

    2004-03-01

    It is well established that confinement in pores suppresses the freezing of liquids, including helium. Pressures greater than about 36 bar are required in order to freeze ^4He in the small pores of vycor glass. Recent torsional oscillator measurements^1 at pressures around 60 bar, where the ^4He is expected to be completely solid at low temperatures, showed a decrease in period below about 175 mK, suggesting the possibility of decoupling of a 'supersolid' phase of ^4He. We have made capacitive measurements of the pressure and density of ^4He in vycor. Solidification in the pores was easily detected from the resulting change in the ^4He density. At a pressure of about 40 bar, freezing began at 1.64 K and was accompanied by a 2% density increase. Cooling the solid ^4He/vycor system below 20 mK did not reveal any unexpected capacitance changes that might indicate that helium was entering or leaving the pores. With a capacitance resolution better than 1 ppm, a ^4He density change of 0.01% would have been detected. This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC). 1. E Kim and MHW Chan (Nature, to be published)

  10. Molecular Architecture Studied by the Surface Forces Measurement.

    PubMed

    Kurihara, Kazue

    2016-11-29

    This feature article reviews the surface forces measurement as a tool for studying molecular architecture chemistry. The history of the measurement is briefly described in the Introduction. The general overview covers specific features of the surface forces measurement as a tool for studying and using molecular architecture. This measurement is powerful for understanding interaction forces and for characterizing and discovering the phenomena at solid-liquid interfaces and soft complex matter. An apparatus for opaque samples was developed, which can be used to study not only opaque samples in various media but also electrochemical processes under various electrochemical potentials. Our studies of molecular architecture are reviewed; they include biological molecular recognition especially involved in the enzyme-substrate interaction; polyelectrolyte brushes exhibiting steric repulsion, which can be reproduced by the osmotic pressure of the counterions, and a density-dependent transition; the hydrogen-bonded molecular macrocluster formation of alcohol and carboxylic acids adsorbed on silica in nonpolar solvents such as cyclohexane; and surface forces between ferrocene-modified electrodes under various applied potentials. These studies demonstrate how the forces measurement is used to identify interacting species such as in biological systems to reveal unknown phenomena and to characterize soft complex matter and the effective potential of the electrodes. Readers will be introduced to the broad applications of the force measurement.

  11. The surface tension of a solid at the solid-vacuum interface, an evaluation from adsorption and wall potential calculations.

    PubMed

    Jakubov, Tim S; Mainwaring, David E

    2007-03-15

    A method for the evaluation of quantities that are experimentally inaccessible such as the surface tension at the solid-vacuum interface and the superficial tension of the fluid in contact with the solid is presented. The approach is based on consideration of an equilibrium of a fluid in solid capillary wherein a balance between surface and capillary forces has been replaced by conceptual alternative interfacial and centrifugal forces. This approach involves the simultaneous numerical solution one the special forms of the Gibbs equation for solid-fluid interface and a generalized Kelvin equation derived earlier. The latter equation takes into account interactions between the solid thick cylindrical wall and confined fluid, this body-body interaction potential has been primarily calculated using the Lennard-Jones (6-12) expression for the atom-atom pair potentials and expressed by hypergeometrical functions having good convergences. All numerical calculations shown here have been performed for the model graphite-argon system at 90 K. Finally, an analysis of the accuracy of the proposed method is considered.

  12. Measurement and modeling of pressure-driven transient burning of solid propellants

    NASA Astrophysics Data System (ADS)

    Murphy, Jeffrey John

    The overall goal of this research is to improve the understanding and predictive capability of combustion-driven instabilities in solid rocket motors. Transient burning rates of solid propellants are not well characterized; better combustion diagnostics and theoretical models are needed. This work covers both of these areas. A new diagnostic technique using ultrasound echo-location for precisely measuring the unsteady burning rate of a solid propellant is described. Also, new methods for modeling transient burning in heterogeneous solid propellants are developed. In the experimental section of this study, ultrasound is used to measure the burning-rate response of several solid propellants to an oscillatory chamber pressure with a frequency of up to 300 Hz. The technique described here is among the first to make wholesale use of digital signal processing for burning-rate measurement. The data are corrected for compression of the propellant by the chamber pressure. The effects of a changing thermal profile on the measurement are also discussed. Results of the experiments compare favorably to data from two other response function measurement techniques. In the modeling section of this study, two transient heterogeneous propellant combustion models, applicable to fine oxidizer composite propellants, are examined. The "surface accumulation model" supposes that components accumulate in a layer at the surface. Each component reaches an equilibrium concentration inversely proportional to its burning rate. The "double reaction layer model" supposes that a molten binder layer covers the propellant. The oxidizer gasifies underneath the layer, while the binder gasifies at the surface. The double reaction layer model qualitatively produces features observed in experimental laser-recoil response function data: a sharp resonance peak accompanied by a shift from negative to positive phase. The surface accumulation model does not produce these features. The presence of time delay

  13. Self-Calibrating Surface Measuring Machine

    NASA Astrophysics Data System (ADS)

    Greenleaf, Allen H.

    1983-04-01

    A new kind of surface-measuring machine has been developed under government contract at Itek Optical Systems, a Division of Itek Corporation, to assist in the fabrication of large, highly aspheric optical elements. The machine uses four steerable distance-measuring interferometers at the corners of a tetrahedron to measure the positions of a retroreflective target placed at various locations against the surface being measured. Using four interferometers gives redundant information so that, from a set of measurement data, the dimensions of the machine as well as the coordinates of the measurement points can be determined. The machine is, therefore, self-calibrating and does not require a structure made to high accuracy. A wood-structured prototype of this machine was made whose key components are a simple form of air bearing steering mirror, a wide-angle cat's eye retroreflector used as the movable target, and tracking sensors and servos to provide automatic tracking of the cat's eye by the four laser beams. The data are taken and analyzed by computer. The output is given in terms of error relative to an equation of the desired surface. In tests of this machine, measurements of a 0.7 m diameter mirror blank have been made with an accuracy on the order of 0.2µm rms.

  14. Development of a surface panel measurement system

    NASA Technical Reports Server (NTRS)

    Jones, D. L.

    1981-01-01

    Reflector measurement systems are studied in support of the reshaping of the 34 meter antenna at Goldstone. The requirements for measurement systems are presented. A survey is made of the surface errors of existing antennas. Reflector measurement systems are divided into three categories and representative examples of each category are illustrated and discussed. Parametric error analyses are made of selected optical systems. The existing measurement method using a theodolite at the vertex is retained. A method using a theodolite on the RF cone is a possible variant.

  15. Evaluation of crystallization behavior on the surface of nifedipine solid dispersion powder using inverse gas chromatography.

    PubMed

    Miyanishi, Hideo; Nemoto, Takayuki; Mizuno, Masayasu; Mimura, Hisashi; Kitamura, Satoshi; Iwao, Yasunori; Noguchi, Shuji; Itai, Shigeru

    2013-02-01

    To investigate crystallization behavior on the surface of amorphous solid dispersion powder using inverse gas chromatography (IGC) and to predict the physical stability at temperatures below the glass transition temperature (T (g)). Amorphous solid dispersion powder was prepared by melt-quenching of a mixture of crystalline nifedipine and polyvinylpyrrolidon (PVP) K-30. IGC was conducted by injecting undecane (probe gas) and methane (reference gas) repeatedly to the solid dispersion at temperatures below T (g). Surface crystallization was evaluated by the retention volume change of undecane based on the observation that the surface of the solid dispersion with crystallized nifedipine gives an increased retention volume. On applying the retention volume change to the Hancock-Sharp equation, surface crystallization was found to follow a two-dimensional growth of nuclei mechanism. Estimation of the crystallization rates at temperatures far below T (g) using the Avrami-Erofeev equation and Arrhenius equation showed that, to maintain its quality for at least three years, the solid dispersion should be stored at -20°C (T (g) - 65°C). IGC can be used to evaluate crystallization behavior on the surface of a solid dispersion powder, and, unlike traditional techniques, can also predict the stability of the solid dispersion based on the surface crystallization behavior.

  16. Broad reactivity trends for oxygen-isotope exchange from the near-surface regions of some metal (hydr)oxide solids.

    PubMed

    Loring, John S; Rosenqvist, Jörgen; Casey, William H

    2004-06-01

    The flux of (18)O from suspensions of isotopically enriched Cr(III) and Rh(III) hydroxide solids at varying temperature and pH was measured in a series of experiments. Most of these solids are metal hydroxide nanospheres that have a large surface area and a narrow distribution in particle sizes and contain inert metals (Cr(III) and Rh(III)). Using rate data for dissolved multimeric complexes as a guide, the solids were enriched in (18)O under conditions that were intended to affect mostly bound water molecules (eta-OH(2)) at the surface, but this point could not be verified. Nevertheless, the fluxes of (18)O back into solution from the isotopically enriched surfaces indicate that increased pH, which partly deprotonates the surface, is surprisingly unimportant to the rate and does not measurably affect (18)O fluxes. Although these data are sparse, Rh(III) solids react at rates that are lower than for Cr(III) solids, and the rates of exchange for crystalline and amorphous solids are relatively close. The results indicate that rates of ligand exchange at these surface sites are controlled dominantly by the local metal-oxygen bond strengths and that long-range forces are relatively unimportant. These experiments also indicate a strategy for measuring rates of ligand exchange from solid surfaces.

  17. The effects of solid rocket motor effluents on selected surfaces and solid particle size, distribution, and composition for simulated shuttle booster separation motors

    NASA Technical Reports Server (NTRS)

    Jex, D. W.; Linton, R. C.; Russell, W. M.; Trenkle, J. J.; Wilkes, D. R.

    1976-01-01

    A series of three tests was conducted using solid rocket propellants to determine the effects a solid rocket plume would have on thermal protective surfaces (TPS). The surfaces tested were those which are baselined for the shuttle vehicle. The propellants used were to simulate the separation solid rocket motors (SSRM) that separate the solid rocket boosters (SRB) from the shuttle launch vehicle. Data cover: (1) the optical effects of the plume environment on spacecraft related surfaces, and (2) the solid particle size, distribution, and composition at TPS sample locations.

  18. Measurement of surface scratches on aircraft structures

    NASA Astrophysics Data System (ADS)

    Sarr, Dennis P.

    1996-01-01

    In assuring the quality of aircraft, the skin quality must be free of surface imperfections. Surface imperfections such as scratches are unacceptable for cosmetic and structural reasons. Scratches beyond a certain depth are not repairable, resulting in costly replacement of an aircraft's part. Measurements of aircraft exterior surfaces require a ladder or cherry picker for positioning the inspector. Commercially-available computer vision systems are not portable, easy to use, or ergonomic. The machine vision system must be designed with these criteria in mind. The scratch measurement system (SMS) uses computer vision, digital signal processing, and automated inspection methods. The system is portable and battery powered. It is certified for measuring the depth and width of the anomaly. The SMS provides a comprehensive, analytical, and accurate reading. A hardcopy output provides a permanent record of the analysis. The graphical data shows the surface profile and provides substantial information of the surface anomaly. The factory and flight line use the SMS at different stages of aircraft production. Six systems have been built for use within Boeing. A patent was issued for the SMS in February 1994.

  19. [Role of the gravity vector in blood cell interaction with solid surface].

    PubMed

    Tiurin-Kuz'min, A Iu

    2007-01-01

    The gravity vector was shown to bear importance to the blood cell interaction with a foreign macroscopic solid surface. Contacting of human whole blood with the underside but not top side of a solid plate out of foreign material amplifies many times generation of active forms of oxygen. This observation may be testimony to gravitational polarization of intracell processes.

  20. Dynamics of a nanoparticle rotating in the near field of a heated solid surface

    NASA Astrophysics Data System (ADS)

    Dedkov, G. V.; Kyasov, A. A.

    2017-08-01

    General expressions for the force of attraction to the surface and the projections of torque exerted on a particle rotating near a solid surface at an arbitrary orientation of the angular velocity vector have been found. It has been shown that the particle decelerates over time and the angular velocity vector tends to be oriented perpendicularly to the surface at any initial conditions.

  1. Measurement of surface deformation of soft tissue.

    PubMed

    Stokes, I; Greenapple, D M

    1985-01-01

    A method is described for measuring the surface shape and deformations of soft tissue in three dimensions. The method uses close range stereophotogrammetry to record the three-dimensional locations of miniature optical targets applied to the tissue surface. This has been applied to study of human lumbar intervertebral disc. Measurements of the strain along surface annular fibers have been made under varying loads. In this case the maximum expected errors are about 0.15 mm, which corresponds to a strain of less than 1%. Preliminary findings have differed from predictions made in published mathematical models for the disc in that they show very little strain of the annulus in compression loading, but confirm axial torsional loading as liable to produce mechanical disruption of the disc annulus.

  2. Optical Roughness Measurements Of Industrial Surfaces

    NASA Astrophysics Data System (ADS)

    Gilsinn, David; Vorburger, Theodore; Cao, Lin-Xiang; Giauque, Charles; Scire, Fredric; Teague, E. Clayton

    1986-10-01

    This paper reviews our efforts to develop the theory and instrumentation needed to measure surface roughness of manufactured surfaces by optical scattering methods. We are addressing three key problems: developing a valid and sufficient optical scattering theory for this roughness range, applying appropriate mathematical inversion techniques so that practical roughness parameters can be calculated from scattering distributions, and finally evaluating a compact commercial instrument for a wide variety of problems. Recent results from our group suggest that the simple phase screen approximation model of optical scattering validly describes light scattering from machined metal surfaces with a predominant surface lay in the 0.01 pm R to 3.0 pm R range. A model for scattering in the entire farr-field hemisphere and obsera vations on our r approach to the inverse problem is given.

  3. Operation Argus. Surface measurements - project midas

    SciTech Connect

    Newman, P.; Chernosky, E.; Markham, T.; McCabe, L.; Peterson, A.

    1984-08-31

    The objective was to make surface measurements of the electromagnetic and optical effects in the detonation area (South Atlantic) and in the area geomagnetically conjugate (Azores) during the Argus experiment. The project participated in three events - Argus I, II, and III.

  4. Surface pressure measurements on a hypersonic vehicle

    SciTech Connect

    Oberkampf, W L; Aeschliman, D P; Henfling, J F; Larson, D E; Payne, J L

    1996-01-01

    Extensive surface pressure measurements were obtained on a hypersonic vehicle configuration at Mach 8 for the purpose of computational fluid dynamics code validation. Experiments were conducted in the Sandia National Laboratories hypersonic wind tunnel. All measurements were made for laminar flow conditions at a Reynolds number (based on model length) of 1.81 x 10{sup 6} and perfect gas conditions. The basic vehicle configuration is a spherically blunted, 10{degree} half- angle cone, with a slice parallel to the axis of the vehicle. To the aft portion of the slice could be attached flaps of varying angle; 10, 20, and 30{degree}. Surface pressure measurements were obtained for angles of attack from -10 to +18{degree}, for various roll angles, at 96 locations on the body surface. All three deflected flap angles produced separated flow on the sliced portion of the body in front of the flap. Because of the three-dimensional expansion over the slice, the separated flow on the slice and flap was also highly three- dimensional. The results of the present experiment provide extensive surface pressure measurements for the validation of computational fluid dynamics codes for separated flow caused by an embedded shock wave.

  5. Sea-surface salinity: the missing measurement

    NASA Astrophysics Data System (ADS)

    Stocker, Erich F.; Koblinsky, Chester

    2003-04-01

    Even the youngest child knows that the sea is salty. Yet, routine, global information about the degree of saltiness and the distribution of the salinity is not available. Indeed, the sea surface salinity measurement is a key missing measurement in global change research. Salinity influences circulation and links the ocean to global change and the water-cycle. Space-based remote sensing of important global change ocean parameters such as sea-surface temperature and water-cycle parameters such as precipitation have been available to the research community but a space-based global sensing of salinity has been missing. In July 2002, the National Aeronautical and Space Administration (NASA) announced that the Aquarius mission, focused on the global measurement of sea surface salinity, is one of the missions approved under its ESSP-3 program. Aquarius will begin a risk-reduction phase during 2003. Aquarius will carry a multi-beam 1.4 GHz (L-band) radiometer used for retrieving salinity. It also will carry a 1.2 GHz (L-band) scatterometer used for measuring surface roughness. Aquarius is tentatively scheduled for a 2006 launch into an 8-day Sun-synchronous orbit. Aquarius key science data product will be a monthly, global surface salinity map at 100 km resolution with an accuracy of 0.2 practical salinity units. Aquarius will have a 3 year operational period. Among other things, global salinity data will permit estimates of sea surface density, or buoyancy, that drives the ocean's three-dimensional circulation.

  6. Surface charge mapping of solid surfaces in water by pulsed-force-mode atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Miyatani, T.; Okamoto, S.; Rosa, A.; Marti, O.; Fujihira, M.

    We have studied the lateral distribution of charges on various surfaces in water by measuring the electrical double layer forces between a Si3N4 atomic force microscope (AFM) tip and the surfaces. By increasing the pH of the solution around the isoelectric point (IEP) of Si3N4 of approximately 6, the charge on the Si3N4 AFM tip was changed from positive to negative. The surface charges of the samples were also controlled by the pH of the solution in which the sample oxides were dipped. When the samples were electronically conductive, the surface charge was controlled by the electrode potentials. When the sample surface was heterogeneous in terms of the isoelectric point or point of zero charge (pzc), the surface charge was changed from one place to the other. As a heterogeneous oxide sample, a quartz plate patterned with alumina was used. The lateral charge distributions on such surfaces were mapped by pulsed-force-mode AFM. The lateral resolution of the present method was found to be approximately 20 nm.

  7. Adhesion of bubbles and drops to solid surfaces, and anisotropic surface tensions studied by capillary meniscus dynamometry.

    PubMed

    Danov, Krassimir D; Stanimirova, Rumyana D; Kralchevsky, Peter A; Marinova, Krastanka G; Stoyanov, Simeon D; Blijdenstein, Theodorus B J; Cox, Andrew R; Pelan, Eddie G

    2016-07-01

    Here, we review the principle and applications of two recently developed methods: the capillary meniscus dynamometry (CMD) for measuring the surface tension of bubbles/drops, and the capillary bridge dynamometry (CBD) for quantifying the bubble/drop adhesion to solid surfaces. Both methods are based on a new data analysis protocol, which allows one to decouple the two components of non-isotropic surface tension. For an axisymmetric non-fluid interface (e.g. bubble or drop covered by a protein adsorption layer with shear elasticity), the CMD determines the two different components of the anisotropic surface tension, σs and σφ, which are acting along the "meridians" and "parallels", and vary throughout the interface. The method uses data for the instantaneous bubble (drop) profile and capillary pressure, but the procedure for data processing is essentially different from that of the conventional drop shape analysis (DSA) method. In the case of bubble or drop pressed against a substrate, which forms a capillary bridge, the CBD method allows one to determine also the capillary-bridge force for both isotropic (fluid) and anisotropic (solidified) adsorption layers. The experiments on bubble (drop) detachment from the substrate show the existence of a maximal pulling force, Fmax, that can be resisted by an adherent fluid particle. Fmax can be used to quantify the strength of adhesion of bubbles and drops to solid surfaces. Its value is determined by a competition of attractive transversal tension and repulsive disjoining pressure forces. The greatest Fmax values have been measured for bubbles adherent to glass substrates in pea-protein solutions. The bubble/wall adhesion is lower in solutions containing the protein HFBII hydrophobin, which could be explained with the effect of sandwiched protein aggregates. The applicability of the CBD method to emulsion systems is illustrated by experiments with soybean-oil drops adherent to hydrophilic and hydrophobic substrates in

  8. Reprogrammable Assembly of Molecular Motor on Solid Surfaces via Dynamic Bonds.

    PubMed

    Yu, Li; Sun, Jian; Wang, Qian; Guan, Yan; Zhou, Le; Zhang, Jingxuan; Zhang, Lanying; Yang, Huai

    2017-06-01

    Controllable assembly of molecular motors on solid surfaces is a fundamental issue for providing them to perform physical tasks. However, it can hardly be achieved by most previous methods due to their inherent limitations. Here, a general strategy is designed for the reprogrammable assembly of molecular motors on solid surfaces based on dynamic bonds. In this method, molecular motors with disulfide bonds can be remotely, reversibly, and precisely attached to solid surfaces with disulfide bonds, regardless of their chemical composition and microstructure. More importantly, it not only allows encoding geometric information referring to a pattern of molecular motors, but also enables erasing and re-encoding of geometric information via hemolytic photocleavage and recombination of disulfide bonds. Thus, solid surfaces can be regarded as "computer hardware", where molecular motors can be reformatted and reprogramed as geometric information. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Towards attosecond measurement in molecules and at surfaces

    NASA Astrophysics Data System (ADS)

    Marangos, Jonathan

    2015-05-01

    1) We will present a number of experimental approaches that are being developed at Imperial College to make attosecond timescale measurements of electronic dynamics in suddenly photoionized molecules and at surfaces. A brief overview will be given of some of the unanswered questions in ultrafast electron and hole dynamics in molecules and solids. These questions include the existence of electronic charge migration in molecules and how this process might couple to nuclear motion even on the few femtosecond timescale. How the timescale of photoemission from a surface may differ from that of an isolated atom, e.g. due to electron transport phenomena associated with the distance from the surface of the emitting atom and the electron dispersion relation, is also an open question. 2) The measurement techniques we are currently developing to answer these questions are HHG spectroscopy, attosecond pump-probe photoelectron/photoion studies, and attosecond pump-probe transient absorption as well as attosecond streaking for measuring surface emission. We will present recent advances in generating two synchronized isolated attosecond pulses at different colours for pump-probe measurements (at 20 eV and 90 eV respectively). Results on generation of isolated attosecond pulses at 300 eV and higher photon energy using a few-cycle 1800 nm OPG source will be presented. The use of these resources for making pump-probe measurements will be discussed. Finally we will present the results of streaking measurement of photoemission wavepackets from two types of surface (WO3 and a evaporated Au film) that show a temporal broadening of ~ 100 as compared to atomic streaks that is consistent with the electron mean free path in these materials. Work supported by ERC and EPSRC.

  10. Aluminum flame temperature measurements in solid propellant combustion.

    PubMed

    Parigger, Christian G; Woods, Alexander C; Surmick, David M; Donaldson, A B; Height, Jonathan L

    2014-01-01

    The temperature in an aluminized propellant is determined as a function of height and plume depth from diatomic AlO and thermal emission spectra. Higher in the plume, 305 and 508 mm from the burning surface, measured AlO emission spectra show an average temperature with 1σ errors of 2980 ± 80 K. Lower in the plume, 152 mm from the burning surface, an average AlO emission temperature of 2450 ± 100 K is inferred. The thermal emission analysis yields higher temperatures when using constant emissivity. Particle size effects along the plume are investigated using wavelength-dependent emissivity models.

  11. A methodology for modeling surface effects on stiff and soft solids

    NASA Astrophysics Data System (ADS)

    He, Jin; Park, Harold S.

    2017-09-01

    We present a computational method that can be applied to capture surface stress and surface tension-driven effects in both stiff, crystalline nanostructures, like size-dependent mechanical properties, and soft solids, like elastocapillary effects. We show that the method is equivalent to the classical Young-Laplace model. The method is based on converting surface tension and surface elasticity on a zero-thickness surface to an initial stress and corresponding elastic properties on a finite thickness shell, where the consideration of geometric nonlinearity enables capturing the out-of-plane component of the surface tension that results for curved surfaces through evaluation of the surface stress in the deformed configuration. In doing so, we are able to use commercially available finite element technology, and thus do not require consideration and implementation of the classical Young-Laplace equation. Several examples are presented to demonstrate the capability of the methodology for modeling surface stress in both soft solids and crystalline nanostructures.

  12. Surface temperature measurements of heterogeneous explosives by IR emission

    SciTech Connect

    Henson, B.F.; Funk, D.J.; Dickson, P.M.; Fugard, C.S.; Asay, B.W.

    1998-03-01

    The authors present measurements of the integrated IR emission (1--5 {micro}m) from both the heterogeneous explosive PBX 9501 and pure HMX at calibrated temperatures from 300 C to 2,500 C. The IR power emitted as a function of temperature is that expected of a black body, attenuated by a unique temperature independent constant which the authors report as the thermal emissivity. The authors have utilized this calibration of IR emission in measurements of the surface temperature from PBX 9501 subject to 1 GPa, two dimensional impact, and spontaneous ignition in unconfined cookoff. They demonstrate that the measurement of IR emission in this spectral region provides a temperature probe of sufficient sensitivity to resolve the thermal response from the solid explosive throughout the range of weak mechanical perturbation, prolonged heating to ignition, and combustion.

  13. Surface temperature measurements of heterogeneous explosives by IR emission

    NASA Astrophysics Data System (ADS)

    Henson, B. F.; Funk, D. J.; Dickson, P. M.; Fugard, C. S.; Asay, B. W.

    1998-07-01

    We present measurements of the integrated IR emission (1-5 μm) from both the heterogeneous explosive PBX 9501 and pure HMX at calibrated temperatures from 30 °C to 250 °C. The IR power emitted as a function of temperature is that expected of a black body, attenuated by a unique temperature independent constant which we report as the thermal emissivity. We have utilized this calibration of IR emission in measurements of the surface temperature from PBX 9501 subject to 1 GPa, two dimensional impact, and spontaneous ignition in unconfined cookoff. We demonstrate that the measurement of IR emission in this spectral region provides a temperature probe of sufficient sensitivity to resolve the thermal response from the solid explosive throughout the range of weak mechanical perturbation, prolonged heating to ignition, and combustion.

  14. Surface topographical changes measured by phase-locked interferometry

    NASA Technical Reports Server (NTRS)

    Lauer, J. L.; Fung, S. S.

    1984-01-01

    An electronic optical laser interferometer capable of resolving depth differences of as low as 30 A and planar displacements of 6000 A was constructed to examine surface profiles of bearing surfaces without physical contact. Topological chemical reactivity was determined by applying a drop of dilute alcoholic hydrochloric acid and measuring the profile of the solid surface before and after application of this probe. Scuffed bearing surfaces reacted much faster than virgin ones but that bearing surfaces exposed to lubricants containing an organic chloride reacted much more slowly. The reactivity of stainless steel plates, heated in a nitrogen atmosphere to different temperatures, were examined later at ambient temperature. The change of surface contour as a result of the probe reaction followed Arrhenius-type relation with respect to heat treatment temperature. The contact area of the plate of a ball/plate sliding elastohydrodynamic contact run on trimethylopropane triheptanoate with or without additives was optically profiled periodically. As scuffing was approached, the change of profile within the contact region changed much more rapidly by the acid probe and assumed a constant high value after scuffing. A nonetching metallurgical phase was found in the scuff mark, which was apparently responsible for the high reactivity.

  15. Directional emittance surface measurement system and process

    NASA Technical Reports Server (NTRS)

    Puram, Chith K. (Inventor); Daryabeigi, Kamran (Inventor); Wright, Robert (Inventor); Alderfer, David W. (Inventor)

    1994-01-01

    Apparatus and process for measuring the variation of directional emittance of surfaces at various temperatures using a radiometric infrared imaging system. A surface test sample is coated onto a copper target plate provided with selective heating within the desired incremental temperature range to be tested and positioned onto a precision rotator to present selected inclination angles of the sample relative to the fixed positioned and optically aligned infrared imager. A thermal insulator holder maintains the target plate on the precision rotator. A screen display of the temperature obtained by the infrared imager, and inclination readings are provided with computer calculations of directional emittance being performed automatically according to equations provided to convert selected incremental target temperatures and inclination angles to relative target directional emittance values. The directional emittance of flat black lacquer and an epoxy resin measurements obtained are in agreement with the predictions of the electromagnetic theory and with directional emittance data inferred from directional reflectance measurements made on a spectrophotometer.

  16. Characterization of Solid Liquid Suspensions Utilizing Ultrasonic Measurements

    NASA Astrophysics Data System (ADS)

    Panetta, P. D.; Tucker, B. J.; Pappas, R. A.; Ahmed, S.

    2003-03-01

    Rapid, on-line determination of particle size and concentration is required for the efficient process measurement and control of many processes in government and industrial applications such as waste remediation for the Department of Energy sites and process control for chemical and pharmaceutical manufacturing. However, existing methods based on ultrasonic attenuation can become inaccurate for highly concentrated suspensions due to careful transducer alignment and the complicated mathematics required to describe multiple scattering, which controls the attenuation. Two measurements that help to overcome these difficulties are the ultrasonic backscattering and diffuse field. Backscattering is attractive because the single scattering theories typically used to describe backscattering are mathematically simpler than attenuation theories and lend themselves to more stable inversion processes. Also, the measurements of backscattering and diffuse fields do not require long travel distances and can be made with a single transducer thus eliminating alignment problems. We will present ultrasonic measurements on solid liquid suspensions designed to elucidate the particle size and concentration at high concentrations.

  17. Lidar measurements of solid rocket propellant fire particle plumes.

    PubMed

    Brown, David M; Brown, Andrea M; Willitsford, Adam H; Dinello-Fass, Ryan; Airola, Marc B; Siegrist, Karen M; Thomas, Michael E; Chang, Yale

    2016-06-10

    This paper presents the first, to our knowledge, direct measurement of aerosol produced by an aluminized solid rocket propellant (SRP) fire on the ground. Such fires produce aluminum oxide particles small enough to loft high into the atmosphere and disperse over a wide area. These results can be applied to spacecraft launchpad accidents that expose spacecraft to such fires; during these fires, there is concern that some of the plutonium from the spacecraft power system will be carried with the aerosols. Accident-related lofting of this material would be the net result of many contributing processes that are currently being evaluated. To resolve the complexity of fire processes, a self-consistent model of the ground-level and upper-level parts of the plume was determined by merging ground-level optical measurements of the fire with lidar measurements of the aerosol plume at height during a series of SRP fire tests that simulated propellant fire accident scenarios. On the basis of the measurements and model results, the Johns Hopkins University Applied Physics Laboratory (JHU/APL) team was able to estimate the amount of aluminum oxide (alumina) lofted into the atmosphere above the fire. The quantification of this ratio is critical for a complete understanding of accident scenarios, because contaminants are transported through the plume. This paper provides an estimate for the mass of alumina lofted into the air.

  18. Quantification of the glucosamine content in the filamentous fungus Monascus ruber cultured on solid surfaces.

    PubMed

    Chysirichote, Teerin; Reiji, Takahashi; Asami, Kazuhiro; Ohtaguchi, Kazuhisa

    2014-05-01

    We evaluated whether the glucosamine content in the filamentous fungus Monascus ruber NBRC 32318, cultured on a solid surface (agar) containing different carbon and nitrogen sources, could be used as a measure of biomass. The relationship between the amounts of glucosamine and biomass was independent of the cultivation period, but was dependent on the carbon source (D-glucose, D-fructose, maltose, sucrose, or rice starch) and the nitrogen source (ammonium chloride, sodium nitrate, monosodium glutamate, or yeast extract) in the agar; it was also dependent on the culture method (solid-surface culture or submerged culture). We concluded that the amount of glucosamine extracted from M. ruber is a useful index for the fungal biomass when the relationship between M. ruber biomass and glucosamine content has previously been calibrated for the carbon and nitrogen sources used. Examination of microphotographs of M. ruber hyphae in conjunction with quantification of the glucosamine and biomass contents indicated that the variation in the glucosamine content per unit biomass affects the hyphal morphology of the fungus, and especially the hyphal diameter.

  19. Diblock copolymer adsorption onto a solid surface as revealed by evanescent wave ellipsometry

    SciTech Connect

    Kim, M.W. ); Russell, T.P. . Almaden Research Center); Moses, T.; Chen, W.; Shen, Y.R. . Center for Advanced Materials Univ. of California, Berkeley, CA . Dept. of Physics)

    1994-12-05

    The interfacial behavior of diblock copolymers play an important role in many practical applications, for example, polymer compatibilization, adhesion, and colloid stabilization. There has been considerable theoretical and experimental effort to understand the adsorption behavior of diblock copolymers from a solution onto a solid surface. Recent neutron reflectivity measurements on solutions of symmetric diblock copolymers of polystyrene and poly(methyl methacrylate), denoted P(S-b-MMA), near a quartz wall have shown that the PMMA segments adsorb preferentially onto the quartz forming a dense layer. However, the segmental concentration of polystyrene (PS) was too low to be observable. Evanescent wave ellipsometry, EWE, on the other hand, allows one to determine the density of molecules adsorbed onto a surface without labeling the segments with deuterium. Here, EWE results on P(S-b-MMA) adsorbed onto a solid substrate are presented as a function of molecular weight. It is shown that the adsorbed amount of copolymer is maximized for a particular molecular weight. This result contradicts theoretical predictions, and a possible origin of this discrepancy is provided.

  20. In situ lithium diffusion measurement in solid ionic conductors using short-lived radiotracer beam of 8Li

    NASA Astrophysics Data System (ADS)

    Ishiyama, H.; Jeong, S. C.; Watanabe, Y. X.; Hirayama, Y.; Imai, N.; Miyatake, H.; Oyaizu, M.; Osa, A.; Otokawa, Y.; Matsuda, M.; Nishio, K.; Makii, H.; Sato, T. K.; Kuwata, N.; Kawamura, J.; Nakao, A.; Ueno, H.; Kim, Y. H.; Kimura, S.; Mukai, M.

    2015-07-01

    We developed an in situ radiotracer method for diffusion studies in solids using short-lived α-emitting 8Li tracer. In the method, while implanting a pulsed 8Li beam into a solid material of interest, the α particles emitted into the implantation side of the sample surface were detected as a function of time. By changing the implantation depth and the detection angle against the sample surface according to lithium diffusivity (deep implantation and large angle with a large solid angle, or shallow implantation and small angle with a narrow solid angle), the method can be sensitive to a wide range of diffusion length ranging from micrometer scale to nanometer scale per second. The feasibility of the method was demonstrated by measuring the lithium diffusion coefficients to the order of 10-12 cm2/s in lithium ionic conductors.

  1. Collective Surface Diffusion Measurements with the STM

    NASA Astrophysics Data System (ADS)

    Tringides, Michael C.

    1996-03-01

    Time dependent processes in surface overlayers at finite coverage are described in terms of the collective diffusion coefficient D_c. Dc can be measured from the time dependent correlation function C(t), of an initial concentration fluctuation formed in a probe area A. C(t) follows a characteristic 1/D_ct time dependence at long times. The STM can be easily used^1 to measure C(t) and, therefore, Dc by monitoring the current fluctuations with the tip fixed over a location (i.e, by suspending the scanning process). The probe area A is defined by the tunneling region. Experiments on O/Si(111) at low coverage will be described that show a dramatic increase of the current fluctuations (when compared to the clean surface) with the addition of oxygen. The analysis of the current fluctuations obtained at different temperatures is consistent with the 1/D_ct form of the correlation function. This method of measuring collective surface diffusion has the unique advantage of ultrafast speed (limited only by the electronics) and can be used to test predictions about the statistical mechanics of surface diffusion in an ensemble of particles. * Ames Laboratory is operated for the U. S. Department of Energy under Contract No. W-7405-Eng-82. 1. M. L. Lozano and M. C. Tringides, Europhys. Lett. 30 , 537 (1995).

  2. Drag force and surface roughness measurements on freshwater biofouled surfaces.

    PubMed

    Andrewartha, J; Perkins, K; Sargison, J; Osborn, J; Walker, G; Henderson, A; Hallegraeff, G

    2010-05-01

    The detrimental effect of biofilms on skin friction for near wall flows is well known. The diatom genera Gomphonema and Tabellaria dominated the biofilm mat in the freshwater open channels of the Tarraleah Hydropower Scheme in Tasmania, Australia. A multi-faceted approach was adopted to investigate the drag penalty for biofouled 1.0 m x 0.6 m test plates which incorporated species identification, drag measurement in a recirculating water tunnel and surface characterisation using close-range photogrammetry. Increases in total drag coefficient of up to 99% were measured over clean surface values for biofouled test plates incubated under flow conditions in a hydropower canal. The effective roughness of the biofouled surfaces was found to be larger than the physical roughness; the additional energy dissipation was caused in part by the vibration of the biofilms in three-dimensions under flow conditions. The data indicate that there was a roughly linear relationship between the maximum peak-to-valley height of a biofilm and the total drag coefficient.

  3. Solid-state dosimeters: A new approach for mammography measurements

    SciTech Connect

    Brateman, Libby F.; Heintz, Philip H.

    2015-02-15

    Purpose: To compare responses of modern commercially available solid-state dosimeters (SStDs) used in mammography medical physics surveys for two major vendors of current digital mammography units. To compare differences in dose estimates among SStD responses with ionization chamber (IC) measurements for several target/filter (TF) combinations and report their characteristics. To review scientific bases for measurements of quantities required for mammography for traditional measurement procedures and SStDs. Methods: SStDs designed for use with modern digital mammography units were acquired for evaluation from four manufacturers. Each instrument was evaluated under similar conditions with the available mammography beams provided by two modern full-field digital mammography units in clinical use: a GE Healthcare Senographe Essential (Essential) and a Hologic Selenia Dimensions 5000 (Dimensions), with TFs of Mo/Mo, Mo/Rh; and Rh/Rh and W/Rh, W/Ag, and W/Al, respectively. Measurements were compared among the instruments for the TFs over their respective clinical ranges of peak tube potentials for kVp and half-value layer (HVL) measurements. Comparisons for air kerma (AK) and their associated relative calculated average glandular doses (AGDs), i.e., using fixed mAs, were evaluated over the limited range of 28–30 kVp. Measurements were compared with reference IC measurements for AK, reference HVLs and calculated AGD, for two compression paddle heights for AK, to evaluate scatter effects from compression paddles. SStDs may require different positioning from current mammography measurement protocols. Results: Measurements of kVp were accurate in general for the SStDs (within −1.2 and +1.1 kVp) for all instruments over a wide range of set kVp’s and TFs and most accurate for Mo/Mo and W/Rh. Discrepancies between measurements and reference values were greater for HVL and AK. Measured HVL values differed from reference values by −6.5% to +3.5% depending on the SStD and

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. Surface brightness measurements for APM galaxies

    NASA Astrophysics Data System (ADS)

    Shao, Z.; Maddox, S. J.; Jones, J. B.; Coles, P.

    2003-01-01

    This paper considers some simple surface brightness (SB) estimates for galaxies in the Automated Plate Measuring machine (APM) catalogue in order to derive homogeneous SB data for a very large sample of faint galaxies. The isophotal magnitude and area are used to estimate the central surface brightness and total magnitude based on the assumption of an exponential SB profile. The SB measurements are corrected for field effects on each UK Schmidt plate and the zero-point of each plate is adjusted to give a uniform sample of SB and total magnitude estimates over the whole survey. Results are obtained for 2.4 million galaxies with blue photographic magnitudes brighter than bJ= 20.5 covering 4300 deg2 in the region of the South Galactic Cap. Almost all galaxies in our sample have central surface brightness in the range 20 to 24 bJ mag arcsec-2. The SB measurements we obtain are compared to previous SB measurements and we find an acceptable level of error of +/-0.2 bJ mag arcsec-2. The distribution of SB profiles is considered for different galaxy morphologies for the bright APM galaxies. We find that early-type galaxies have more centrally concentrated profiles.

  6. Minimizing Uncertainty in Cryogenic Surface Figure Measurement

    NASA Technical Reports Server (NTRS)

    Blake, Peter; Mink, Ronald G.; Chambers, John; Robinson, F. David; Content, David; Davila, Pamela

    2005-01-01

    A new facility at the Goddard Space Flight Center is designed to measure with unusual accuracy the surface figure of mirrors at cryogenic temperatures down to 12 K. The facility is currently configured for spherical mirrors with a radius of curvature (ROC) of 600 mm, and apertures of about 150 mm or less. The goals of the current experiment were to 1) Obtain the best possible estimate of test mirror surface figure, S(x,y) at 87 K and 20 K; 2) Obtain the best estimate of the cryo-change, Delta (x,y): the change in surface figure between room temperature and the two cryo-temperatures; and 3) Determine the uncertainty of these measurements, using the definitions and guidelines of the ISO Guide to the Expression of Uncertainty in Measurement. A silicon mirror was tested, and the cry-change from room temperature to 20K was found to be 3.7 nm rms, with a standard uncertainty of 0.23 nm in the rms statistic. Both the cryo-change figure and the uncertainty are among the lowest such figures yet published. This report describes the facilities, experimental methods, and uncertainty analysis of the measurements.

  7. Minimizing Uncertainty in Cryogenic Surface Figure Measurement

    NASA Technical Reports Server (NTRS)

    Blake, Peter; Mink, Ronald G.; Chambers, John; Robinson, F. David; Content, David; Davila, Pamela

    2005-01-01

    A new facility at the Goddard Space Flight Center is designed to measure with unusual accuracy the surface figure of mirrors at cryogenic temperatures down to 12 K. The facility is currently configured for spherical mirrors with a radius of curvature (ROC) of 600 mm, and apertures of about 150 mm or less. The goals of the current experiment were to 1) Obtain the best possible estimate of test mirror surface figure, S(x,y) at 87 K and 20 K; 2) Obtain the best estimate of the cryo-change, Delta (x,y): the change in surface figure between room temperature and the two cryo-temperatures; and 3) Determine the uncertainty of these measurements, using the definitions and guidelines of the ISO Guide to the Expression of Uncertainty in Measurement. A silicon mirror was tested, and the cry-change from room temperature to 20K was found to be 3.7 nm rms, with a standard uncertainty of 0.23 nm in the rms statistic. Both the cryo-change figure and the uncertainty are among the lowest such figures yet published. This report describes the facilities, experimental methods, and uncertainty analysis of the measurements.

  8. Thermally driven flows between a Leidenfrost solid and a ratchet surface.

    PubMed

    Hardt, Steffen; Tiwari, Sudarshan; Baier, Tobias

    2013-06-01

    The significance of thermally driven flows for the propulsion of Leidenfrost solids on a ratchet surface is studied based on a numerical solution of the Boltzmann equation. The resulting flow patterns are dominated by vortices developing at the edges of the ratchet teeth. In a previous analysis it had been claimed that thermally driven flows could cause the propulsion of Leidenfrost objects. In contrast to that analysis, it is found that such flows make an insignificant contribution to the thrust of Leidenfrost solids on ratchet surfaces, which is dominated by the pressure-driven flow due to the sublimating solid.

  9. Effect of suspended particles upon drying process of volatile droplet sitting on solid surface

    NASA Astrophysics Data System (ADS)

    Ueno, I.; Kochiya, K.

    Particle motion in volatile droplet on the solid surface especially the behavior of particles depositing in the vicinity of solid-liquid-gas boundary line contact line is focused This phenomenon is called as coffee stain problem Particle motion in the droplet is analyzed by reconstruction of spatio-temporal particle motion by applying three-dimensional particle tracking velocimetry 3-D PTV We discuss the effect of the suspended particles upon the drying process of the droplet Morphological discussion on the particles stuck on the solid surface after the dryout the droplet is also conducted

  10. Surface acoustic BLOCH oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling in a solid.

    PubMed

    de Lima, M M; Kosevich, Yu A; Santos, P V; Cantarero, A

    2010-04-23

    We present the experimental observation of Bloch oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling of surface acoustic waves in perturbed grating structures on a solid substrate. A model providing a quantitative description of our experimental observations, including multiple Landau-Zener transitions of the anticrossed surface acoustic Wannier-Stark states, is developed. The use of a planar geometry for the realization of the Bloch oscillations and Landau-Zener tunneling allows a direct access to the elastic field distribution. The vertical surface displacement has been measured by interferometry.

  11. Effect of Geometry on Electrokinetic Characterization of Solid Surfaces.

    PubMed

    Kumar, Abhijeet; Kleinen, Jochen; Venzmer, Joachim; Gambaryan-Roisman, Tatiana

    2017-08-01

    An analytical approach is presented to describe pressure-driven streaming current (Istr) and streaming potential (Ustr) generation in geometrically complex samples, for which the classical Helmholtz-Smoluchowski (H-S) equation is known to be inaccurate. The new approach is valid under the same prerequisite conditions that are used for the development of the H-S equation, that is, the electrical double layers (EDLs) are sufficiently thin and surface conductivity and electroviscous effects are negligible. The analytical methodology is developed using linear velocity profiles to describe liquid flow inside of EDLs and using simplifying approximations to describe macroscopic flow. At first, a general expression is obtained to describe the Istr generated in different cross sections of an arbitrarily shaped sample. Thereafter, assuming that the generated Ustr varies only along the pressure-gradient direction, an expression describing the variation of generated Ustr along the sample length is obtained. These expressions describing Istr and Ustr generation constitute the theoretical foundation of this work, which is first applied to a set of three nonuniform cross-sectional capillaries and thereafter to a square array of cylindrical fibers (model porous media) for both parallel and transverse fiber orientation cases. Although analytical solutions cannot be obtained for real porous substrates because of their random structure, the new theory provides useful insights into the effect of important factors such as fiber orientation, sample porosity, and sample dimensions. The solutions obtained for the model porous media are used to device strategies for more accurate zeta potential determination of porous fiber plugs. The new approach could be thus useful in resolving the long-standing problem of sample geometry dependence of zeta potential measurements.

  12. Surface coating effects in remote sensing measurements

    USGS Publications Warehouse

    Watson, Robert D.

    1970-01-01

    Measurements of the infrared spectra of a liquid-(water) coated quartz substrate and a solid-(pyrophyllite) coated quartzite are compared to theoretical values. Results demonstrate that in the case of the water-coated quartz, a loss in spectral contrast of the quartz emission occurs at the principal restrahlen wavelengths of 8.5, 9.0, and 12.5 µ but is most pronounced at 12.5 µ. In the case of pyrophyllite-coated quartzite, additional spectral features appear between 8.0 and 10.0 µ as the exposure of quartzite through the pyrophyllite coating is increased. Addition of the pure quartzite and pyrophyllite spectra, weighted by exposed area, is shown to satisfactorily describe the composite spectra.

  13. Measurement of cylindrical Rayleigh surface waves using line-focused PVDF transducers and defocusing measurement method.

    PubMed

    Lin, Chun-I; Lee, Yung-Chun

    2014-08-01

    Line-focused PVDF transducers and defocusing measurement method are applied in this work to determine the dispersion curve of the Rayleigh-like surface waves propagating along the circumferential direction of a solid cylinder. Conventional waveform processing method has been modified to cope with the non-linear relationship between phase angle of wave interference and defocusing distance induced by a cylindrically curved surface. A cross correlation method is proposed to accurately extract the cylindrical Rayleigh wave velocity from measured data. Experiments have been carried out on one stainless steel and one glass cylinders. The experimentally obtained dispersion curves are in very good agreement with their theoretical counterparts. Variation of cylindrical Rayleigh wave velocity due to the cylindrical curvature is quantitatively verified using this new method. Other potential applications of this measurement method for cylindrical samples will be addressed.

  14. EDITORIAL: Precision Density Measurements of Solids and Liquids

    NASA Astrophysics Data System (ADS)

    Bettin, Horst

    2006-10-01

    This special feature is dedicated to methods and applications of density measurements of the highest precision. It contains papers from the 210th PTB Seminar 'Precision Density Measurements of Solids and Liquids', which was held at the Physikalisch-Technische Bundesanstalt, Germany, on 24 26 October 2005 and was sponsored by the Helmholtz Funds e.V., Germany. More than 55 density experts from 20 countries attended the seminar. The participants came from national metrological institutes, calibration laboratories, verification offices, universities and manufactures of density meters. Thus, many interesting discussions were stimulated between various groups, in particular between those in research and those working on applications. The main topics of the seminar were the realization of the density unit and its dissemination by comparison methods. The research activities for the determination of the Avogadro constant stimulated the development of new methods as well as the improvement of more conventional methods in order to reach density uncertainties below 0.1 ppm. Technical and physical limitations of the methods were discussed as well as applications and future trends. This special feature contains nine papers based on presentations given at the seminar. Two additional papers on liquid density reference standards and compressibility measurements of liquids complete the feature. I would like to take this opportunity to thank all the authors who contributed to this special feature, which I hope provides an excellent compendium of the topics discussed at the seminar.

  15. Measuring densities of solids and liquids using magnetic levitation: fundamentals.

    PubMed

    Mirica, Katherine A; Shevkoplyas, Sergey S; Phillips, Scott T; Gupta, Malancha; Whitesides, George M

    2009-07-29

    This paper describes an analytical system that uses magnetic levitation to measure densities of solids and water-immiscible organic liquids with accuracies ranging from +/-0.0002 to +/-0.02 g/cm(3), depending on the type of experiment. The technique is compatible with densities of 0.8-3 g/cm(3) and is applicable to samples with volumes of 1 pL to 1 mL; the samples can be either spherical or irregular in shape. The method employs two permanent NdFeB magnets positioned with like poles facing one another--with the axis between the poles aligned with the gravitational field--and a container filled with paramagnetic medium (e.g., MnCl(2) dissolved in water) placed between these magnets. Density measurements are obtained by placing the sample into the container and measuring the position of the sample relative to the bottom magnet. The balance of magnetic and gravitational forces determines the vertical position of the sample within the device; knowing this position makes it possible to calculate the density of the sample.

  16. Analysis of Measurements for Solid State Lidar Development

    NASA Technical Reports Server (NTRS)

    Amzajerdian, Farzin

    1996-01-01

    A Detector Characterization Facility (DCF), capable of measuring 2-micron detection devices and evaluating heterodyne receivers, was developed at the Marshall Space Flight Center. The DCF is capable of providing all the necessary detection parameters for design, development, and calibration of coherent and incoherent solid state laser radar (lidar) systems. The coherent lidars in particular require an accurate knowledge of detector heterodyne quantum efficient, nonlinearity properties, and voltage-current relationship as a function of applied optical power. At present, no detector manufacturer provides these qualities or adequately characterizes their detectors for heterodyne detection operation. In addition, the detector characterization facility measures the detectors DC and AC quantum efficiencies noise equivalent power and frequency response up to several GHz. The DCF is also capable of evaluating various heterodyne detection schemes such as balanced detectors and fiber optic interferometers. The design and analyses of measurements for the DCF were preformed over the previous year and a detailed description of its design and capabilities was provided in the NASA report NAS8-38609/DO77. It should also be noted that the DCF design was further improved to allow for the characterization of diffractive andholographical optical elements and other critical components of coherent lidar systems.

  17. On quantum effects on the surface of solid hydrogen

    SciTech Connect

    Marchenko, V. I.

    2013-10-15

    The low-frequency spectrum of hypothetical superfluidity on the free surface of a quantum crystal of hydrogen is determined. In the quantum-rough state of the surface, crystallization waves with a quadratic spectrum should propagate. In the atomically smooth state, the spectrum is linear. Crystallization waves propagating along elementary steps are also considered.

  18. Determination of the Surface Tension of Microporous Membranes Using Contact Angle Measurements

    PubMed

    Tröger; Lunkwitz; Bürger

    1997-10-15

    In this paper, a new method of determining the surface tension of the solid material that a microporous membrane is made from is introduced. The method is based on the well known determination of the so-called contact angle that is formed on the solid/liquid/gaseous three phase line. A nonideal state of the solid phase leads to a deviation of the contact angle that can be observed experimentally from the equilibrium angle that arises from the thermodynamically state of lowest energy, as it must be used to calculate the solid surface tension via the Young equation. The deviation caused from the porous structure of the solid material will be taken into account in this work. Doing so, we derived an equation that connects the surface porosity, the measured contact angle, and the equilibrium contact angle. Using this equation, the measured and therefore deviated contact angles can be corrected for the porosity of the solid material, yielding the contact angle observable on a surface made from the same but nonporous material. The equation derived was tested on different microporous membranes made from expanded poly(tetrafluoroethylene). The surface porosity needed was determined using scanning electron microscopy followed by computerized image analysis. Copyright 1997 Academic Press. Copyright 1997Academic Press

  19. Surface drifters measuring sea water salinity

    NASA Astrophysics Data System (ADS)

    Reverdin, Gilles; Centurioni, Luca; Sena-Martins, Meike; Garcia-Ladona, Emilio; Ballabrera, Joaquim; Salvador, Joaquin; Sommer, Anna; Boutin, Jacqueline

    2017-04-01

    Surface drifters have been introduced in the early 1990s by P.P. Niiler to measure the salinity of the near-surface water as well as its temperature. First, they were deployed to document large scale advection of surface salinity fronts, such as during TOGA-COARE (1991). More recently, salinity drifter data were used for three purposes: 1 - provide in situ data coverage for validation of sea surface (SSS) products, such as provided by band-L microwave radiometry from satellite missions, Aquarius, SMOS, SMAP 2 - provide data for better understanding upper ocean response to air-sea interactions, such as during rainfall, or near-surface warming during low wind events 3 - provide estimates of surface advection of salinity features and their contribution to ocean freshwater budget We will review the drifters that have been deployed and where data were collected, the challenges encountered in correcting the data, ongoing plans and future developments. A comparison of salinity data of more than 60 SVP drifters to SMOS and Aquarius SSS fields in the North Atlantic subtropical gyre illustrates the potential for validating products from satellite missions over more than a year (SPURS-1 2012-2013 experiment). Data collocated during tropical rain events illustrate a short-term response of near-surface salinity and temperature that can be quantified, although we lack precise collocated wind data. It is rather consistent with independently-derived surface salinity response to rain based on SMOS salinity retrievals, and model estimations. An extreme case of close to 10 psu near-surface salinity drop due to rainfall is presented. Recent salinity drifter deployments in the rainy region of the eastern Pacific ITCZ (SPURS-2 2016 experiment) illustrate the small time and space scale variability associated with freshwater lenses in this region. Some data from a new tag (surpact) will be presented with simultaneous estimates of sea state, rain rate, temperature and salinity during rain

  20. Surface tension and a self-consistent theory of soft composite solids with elastic inclusions.

    PubMed

    Mancarella, Francesco; Wettlaufer, John S

    2017-02-07

    The importance of surface tension effects is being recognized in the context of soft composite solids, where they are found to significantly affect the mechanical properties, such as the elastic response to an external stress. It has recently been discovered that Eshelby's inclusion theory breaks down when the inclusion size approaches the elastocapillary length L≡γ/E, where γ is the inclusion/host surface tension and E is the host Young's modulus. Extending our recent results for liquid inclusions, here we model the elastic behavior of a non-dilute distribution of isotropic elastic spherical inclusions in a soft isotropic elastic matrix, subject to a prescribed infinitesimal far-field loading. Within our framework, the composite stiffness is uniquely determined by the elastocapillary length L, the spherical inclusion radius R, and the stiffness contrast parameter C, which is the ratio of the inclusion to the matrix stiffness. We compare the results with those from the case of liquid inclusions, and we derive an analytical expression for elastic cloaking of the composite by the inclusions. Remarkably, we find that the composite stiffness is influenced significantly by surface tension even for inclusions two orders of magnitude more stiff than the host matrix. Finally, we show how to simultaneously determine the surface tension and the inclusion stiffness using two independent constraints provided by global and local measurements.

  1. Static and dynamic contact angles of water droplet on a solid surface using molecular dynamics simulation.

    PubMed

    Hong, Seung Do; Ha, Man Yeong; Balachandar, S

    2009-11-01

    The present study investigates the variation of static contact angle of a water droplet in equilibrium with a solid surface in the absence of a body force and the dynamic contact angles of water droplet moving on a solid surface for different characteristic energies using the molecular dynamics simulation. With increasing characteristic energy, the static contact angle in equilibrium with a solid surface in the absence of a body force decreases because the hydrophobic surface changes its characteristics to the hydrophilic surface. In order to consider the effect of moving water droplet on the dynamic contact angles, we apply the constant acceleration to an individual oxygen and hydrogen atom. In the presence of a body force, the water droplet changes its shape with larger advancing contact angle than the receding angle. The dynamic contact angles are compared with the static contact angle in order to see the effect of the presence of a body force.

  2. Comparison of satellite and airborne sensor data on sea surface temperature and suspended solid distribution

    NASA Astrophysics Data System (ADS)

    Nishimura, Y.; Saito, K.; Hayakawa, S.; Narigasawa, K.

    1992-07-01

    Sea surface temperature and suspended solid were observed simultaneously by LANDSAT TM, NOAA AVHRR and airborne MSS. The authors compared the following items through the data, i.e., 1) Sea surface temperature, 2) Suspended solid in the sea water, 3) Monitoring ability on ocean environment. It was found that distribution patterns of sea surface temperature and suspended solid in the Ariake Sea obtained from LANDSAT TM are similar with those from airborne MSS in a scale of 1:300,000. Sea surface temperature estimated from NOAA AVHRR data indicates a fact of an ocean environment of the Ariake Sea and the around sea area. It is concluded that the TM data can be used for the monitoring of sea environment. The NOAA AVHRR data is useful for the estimation of sea surface temperature with the airborne MSS data.

  3. Measuring Wind Ventilation of Dense Surface Snow

    NASA Astrophysics Data System (ADS)

    Drake, S. A.; Huwald, H.; Selker, J. S.; Higgins, C. W.; Lehning, M.; Thomas, C. K.

    2014-12-01

    Wind ventilation enhances exposure of suspended, canopy-captured and corniced snow to subsaturated air and can significantly increase sublimation rate. Although sublimation rate may be high for highly ventilated snow this snow regime represents a small fraction snow that resides in a basin potentially minimizing its influence on snow mass balance. In contrast, the vast majority of a seasonal snowpack typically resides as poorly ventilated surface snow. The sublimation rate of surface snow is often locally so small as to defy direct measurement but regionally pervasive enough that the integrated mass loss of frozen water across a basin may be significant on a seasonal basis. In a warming climate, sublimation rate increases even in subfreezing conditions because the equilibrium water vapor pressure over ice increases exponentially with temperature. To better understand the process of wintertime surface snow sublimation we need to quantify the depth to which turbulent and topographically driven pressure perturbations effect air exchange within the snowpack. Hypothetically, this active layer depth increases the effective ventilated snow surface area, enhancing sublimation above that given by a plane, impermeable snow surface. We designed and performed a novel set of field experiments at two sites in the Oregon Cascades during the 2014 winter season to examine the spectral attenuation of pressure perturbations with depth for dense snow as a function of turbulence intensity and snow permeability. We mounted a Campbell Scientific Irgason Integrated CO2 and H2O Open Path Gas Analyzer and 3-D Sonic Anemometer one meter above the snow to capture mean and turbulent wind forcing and placed outlets of four high precision ParoScientific 216B-102 pressure transducers at different depths to measure the depth-dependent pressure response to wind forcing. A GPS antenna captured data acquisition time with sufficient precision to synchronize a Campbell Scientific CR-3000 acquiring

  4. Reliability and Consistency of Surface Contamination Measurements

    SciTech Connect

    Rouppert, F.; Rivoallan, A.; Largeron, C.

    2002-02-26

    Surface contamination evaluation is a tough problem since it is difficult to isolate the radiations emitted by the surface, especially in a highly irradiating atmosphere. In that case the only possibility is to evaluate smearable (removeable) contamination since ex-situ countings are possible. Unfortunately, according to our experience at CEA, these values are not consistent and thus non relevant. In this study, we show, using in-situ Fourier Transform Infra Red spectrometry on contaminated metal samples, that fixed contamination seems to be chemisorbed and removeable contamination seems to be physisorbed. The distribution between fixed and removeable contamination appears to be variable. Chemical equilibria and reversible ion exchange mechanisms are involved and are closely linked to environmental conditions such as humidity and temperature. Measurements of smearable contamination only give an indication of the state of these equilibria between fixed and removeable contamination at the time and in the environmental conditions the measurements were made.

  5. Surface Defects Enhanced Visible Light Photocatalytic H2 Production for Zn-Cd-S Solid Solution.

    PubMed

    Zhang, Xiaoyan; Zhao, Zhao; Zhang, Wanwan; Zhang, Guoqiang; Qu, Dan; Miao, Xiang; Sun, Shaorui; Sun, Zaicheng

    2016-02-10

    In order to investigate the defect effect on photocatalytic performance of the visible light photocatalyst, Zn-Cd-S solid solution with surface defects is prepared in the hydrazine hydrate. X-ray photoelectron spectra and photoluminescence results confirm the existence of defects, such as sulfur vacancies, interstitial metal, and Zn and Cd in the low valence state on the top surface of solid solutions. The surface defects can be effectively removed by treating with sulfur vapor. The solid solution with surface defect exhibits a narrower band gap, wider light absorption range, and better photocatalytic perfomance. The optimized solid solution with defects exhibits 571 μmol h(-1) for 50 mg photocatalyst without loading Pt as cocatalyst under visible light irradiation, which is fourfold better than that of sulfur vapor treated samples. The wavelength dependence of photocatalytic activity discloses that the enhancement happens at each wavelength within the whole absorption range. The theoretical calculation shows that the surface defects induce the conduction band minimum and valence band maximum shift downward and upward, respectively. This constructs a type I junction between bulk and surface of solid solution, which promotes the migration of photogenerated charges toward the surface of nanostructure and leads to enhanced photocatalytic activity. Thus a new method to construct highly efficient visible light photocatalysts is opened.

  6. Axilla surface area for males and females: measured distribution.

    PubMed

    Cowan-Ellsberry, Christina; McNamee, Pauline M; Leazer, Tyra

    2008-10-01

    With the recent introduction of exposure-based Quantitative Risk Assessment (QRA) as an approach to the evaluation, of materials in finished consumer products that are potential dermal sensitizers, the need for robust exposure data was clearly identified. The objective of this current study is to provide a value for the axilla surface area (SA) that is statistically derived and can be used in dermal sensitization QRA for ingredients of personal care products meant for use on the axilla. The axilla surface area measured for 60 men and 60 women resulted in a median surface area for a single axilla of 64.5 cm(2) for females and 135.5 cm(2) for males. These participants were representative of the United States population in their range of heights and weights. Furthermore, combining these surface area data with measured use data from this and other studies has enabled calculations of consumer exposure to solid APDO products on a dose/unit area/day basis (9.1 mg/cm(2)/d).

  7. Feasibility study of solid surface subreflector production techniques

    NASA Technical Reports Server (NTRS)

    1982-01-01

    The principal effort was to study technical feasibility and cost aspects of the production technique of spin forming a subreflector reflective surface to a desired surface of revolution, back the surface with fiberglass to stabilize it sufficiently so that it may be machined to the target surface tolerance of .008 inches Root Mean Square (RMS) with a goal of .003 inches RMS. To verify this production technique, analyses was performed to define the production procedure. A price estimate for a 150 inch diameter subreflector for a 34 meter cassegrain antenna. During this feasibility study, numerous production processes were evaluated theoretically as production approaches for single surface, non-welded subreflectors. The first successful was the principal process of spin forming the reflective surface, backing with fiberglass and machining to a final contour. The second successful process was spin forming or bump forming a thicker reflective surface, with an integral (welded in) structure as a backing and machining the mounting pads and reflector to a final configuration.

  8. Microwave Radiometric Measurement of Sea Surface Salinity.

    DTIC Science & Technology

    1984-04-01

    potential problems of polution and urban water sup- plies. Although salinity can be measured from a surface vessel, economic consider- ations advocate...Washington, DC 20350 Commander Naval Sea System Commandaa ComAinder ATTN: Mr. C. Smith, NAVSEA 63R* Nval Air Development Center "’-’. "Washington, DC...20362 ATTN: Mr. R. Bollard, Code 2062% .’* Warminster, PA 18974 • .’.Commander CNaval Sea System CommandCoimCander Headquarters Naval Air Systems

  9. Surface Wear Measurement Using Optical Correlation Technique

    NASA Astrophysics Data System (ADS)

    Acinger, Kresimir

    1983-12-01

    The coherent optical correlation technique was applied for measuring the surface wear of a tappet (part of car engine), worn by friction with the camshaft. It was found that maximum correlation intensity decays exponentially with the number of wear cycles (i.e. camshaft revolutions). Tappets of the same make have an identical rate of correlation decay. Tappets of different makes have different rates of correlation decay which are in agreement with observed long term wear.

  10. Measurement of single crystal surface parameters

    NASA Technical Reports Server (NTRS)

    Swanson, L. W.; Bell, A. E.; Strayer, R. W.

    1972-01-01

    The sticking coefficient and thermal desorption spectra of Cs from the (110) plane of W was investigated. A sticking coefficient of unity for the monolayer region was measured for T 250 K. Several distinct binding states were observed in the thermal desorption spectrum. Work function and electron reflection measurements were made on the (110) and (100) crystal faces of Mo. Both LEED and Auger were used to determine the orientation and cleanliness of the crystal surfaces. The work function values obtained for the (110) and (100) planes of Mo were 4.92 and 4.18 eV respectively.

  11. Accurate measurement of LED lens surface temperature

    NASA Astrophysics Data System (ADS)

    Perera, Indika U.; Narendran, Nadarajah; Liu, Yi-wei

    2013-09-01

    Radiant power emitted by high power light-emitting diodes (LEDs) have been steadily increasing over the past decade. High radiation, especially short wavelength, can increase the temperature and negatively affect the primary lens performance of high-power LEDs. In this regards, assessment of lens temperature during operation is important. Past studies have shown large errors when thermocouples are used for measuring temperature in high radiant flux environments. Therefore, the objective of this study was to understand the problem in using thermocouples to measure LED lens surface temperature and to find a solution to improving the measurement accuracy. A laboratory study was conducted to better understand the issue. Results showed that most of the error is due to absorption of visible radiant energy by the thermocouple. In this study, the measurements made using an infrared (IR) thermal imaging system were used as the reference temperature because the IR imaging system is unaffected by radiant flux in the visible range. After studying the thermocouple wire metallurgy and its radiation absorption properties, a suitable material was identified to shield the thermocouple from visible radiation. Additionally, a silicone elastomer was used to maintain the thermal interface between the lens surface and the thermocouple junction bead. With these precautions, the lens temperature measurements made using the J-type thermocouple and the IR imaging system matched very well.

  12. Evaluation of Arctic broadband surface radiation measurements

    NASA Astrophysics Data System (ADS)

    Matsui, N.; Long, C. N.; Augustine, J.; Halliwell, D.; Uttal, T.; Longenecker, D.; Niebergall, O.; Wendell, J.; Albee, R.

    2012-02-01

    The Arctic is a challenging environment for making in-situ surface radiation measurements. A standard suite of radiation sensors is typically designed to measure incoming and outgoing shortwave (SW) and thermal infrared, or longwave (LW), radiation. Enhancements may include various sensors for measuring irradiance in narrower bandwidths. Many solar radiation/thermal infrared flux sensors utilize protective glass domes and some are mounted on complex mechanical platforms (solar trackers) that keep sensors and shading devices trained on the sun along its diurnal path. High quality measurements require striking a balance between locating stations in a pristine undisturbed setting free of artificial blockage (such as from buildings and towers) and providing accessibility to allow operators to clean and maintain the instruments. Three significant sources of erroneous data in the Arctic include solar tracker malfunctions, rime/frost/snow deposition on the protective glass domes of the radiometers and operational problems due to limited operator access in extreme weather conditions. In this study, comparisons are made between the global and component sum (direct [vertical component] + diffuse) SW measurements. The difference between these two quantities (that theoretically should be zero) is used to illustrate the magnitude and seasonality of arctic radiation flux measurement problems. The problem of rime/frost/snow deposition is investigated in more detail for one case study utilizing both SW and LW measurements. Solutions to these operational problems that utilize measurement redundancy, more sophisticated heating and ventilation strategies and a more systematic program of operational support and subsequent data quality protocols are proposed.

  13. Measurements of slip length for flows over graphite surface with gas domains

    NASA Astrophysics Data System (ADS)

    Li, Dayong; Wang, Yuliang; Pan, Yunlu; Zhao, Xuezeng

    2016-10-01

    We present the measurements of slip lengths for the flows of purified water over graphite surface covered with surface nanobubbles or nano/micropancakes, which can be produced after using high temperature water to replace low temperature water. The slip length values measured on bare graphite surface, nano/micropancake or nanobubble covered graphite surfaces are about 8 nm, 27 nm, and 63 nm, respectively. Our results indicate that the gaseous domains formed at the solid-liquid interface, including surface nanobubbles and nano/micropancakes, could act as a lubricant and significantly increase slip length.

  14. Solid-state, surface, and catalytic properties of oxides

    NASA Astrophysics Data System (ADS)

    Kung, H. H.

    1981-08-01

    Catalysis by transition metal oxides was investigated and four areas are emphasized. In the first area, an adsorbed oxygen species on iron oxide was characterized. This species desorb, with an activation energy of 38 kcal/mole, and it has a coverage of 1.4 x 10(16) molecules/m(2). Its desorption follows a second order kinetics suggesting that it is an atomic species. The high activation energy suggests that the species may only be active in total oxidation. In the second area, ZnO surfaces containing controlled defects in the form of steps were studied. It is found that the nonpolar flat a stepped and a polar surface behave differently. The CO2 adsorbs with increasing strength on these three surfaces in this order. Methanol does not decompose on a stoichiometric. The stepped surface is active in methanol decomposition in the manner like the vacancy.

  15. Optical measurement system for characterizing plastic surfaces

    NASA Astrophysics Data System (ADS)

    Gahleitner, R.; Niel, Kurt S.; Frank, S.

    2008-02-01

    Injection molded plastic parts are often influenced with the surface defect tiger stripes, which dramatically reduce the visual quality. Tiger stripes are known as alternating bands of bright and dull regions normally to the molded flow direction. This defect highly depends on the injection time and on the formation of the plastic compound. In the last years, the intensity of the tiger stripes defect was controlled visually. For quantifying the tiger strip defect a new, efficient, repeatable, reliable and nondestructive optical measurement system is proposed. To evaluate the dependency of the injection time, a number of five DIN-A5 plastic specimens are molded. Each of the five plates consists of the same material but they have different injection times. For the measurement, one specimen is put into the specimen holder, which is placed on the drawer of a closed cabinet. In this inside black painted cabinet a LED light source and a CCD Camera are mounted. The beams of the LED light are diffuse reflected on the surface of the specimen. To catch only parallel beams by the lens of the camera a large distance between specimen and camera is realized by two justified mirrors in the cabinet. The bright and dull regions of the tiger stripe defect have different diffuse reflection parameters. Thus in a picture of defined brightness the visibility of this defect is very good. To enhance the repeatability the failure of the camera noise and of the light oscillation is reduced by mends of averaging multiple images. Next, the surface structure is filtered out of the image and a representing number of horizontal grey-value lines are extracted. The so called tiger line signal is the difference between the grey line and a calculated polynomial function (degree of 6) and shows the surface defect of each line oscillating on the zero x-axis. For each tiger line signal the mean squared error is evaluated. To calculate a quantitative value of the whole surface, all line errors are

  16. Measurement of suspended solids in lakes and oceans using satellite remote sensing data

    NASA Technical Reports Server (NTRS)

    Sydor, M. (Principal Investigator)

    1980-01-01

    Using satellite remote sensing data to measure low concentrations of suspended solids in lakes and oceans requires careful evaluation of background signals from the atmosphere and the water surface. Typical background corrections for Lake Superior are presented and the spectral distribution of the residual radiance from three major categories of turbidity in the lake are determined. The results indicate that for large bodies of water, some general information on atmospheric scattering, water clarity, and the optical properties of suspended solids allows estimates of concentrations of suspended solids to within + or - 0.5 mg/L without using real time ground truth data. Under calibrated conditions the threshold detection level is 0.3 mg/L for the fine particulates dispersed throughout the lake and 1 mg/L for the highly light absorbing effluent from rivers. Comparisons of the minimum reflectance over the open lake areas with reflection from the highly absorbing tannin water from rivers provides a check on the clarity of the atmosphere and the excessive background scatter from the water surface.

  17. Study of Surface Wave Propagation in Fluid-Saturated Porous Solids.

    NASA Astrophysics Data System (ADS)

    Azcuaga, Valery Francisco Godinez

    1995-01-01

    This study addresses the surface wave propagation phenomena on fluid-saturated porous solids. The analytical method for calculation of surface wave velocities (Feng and Johnson, JASA, 74, 906, 1983) is extended to the case of a porous solid saturated with a wetting fluid in contact with a non-wetting fluid, in order to study a material combination suitable for experimental investigation. The analytical method is further extended to the case of a non-wetting fluid/wetting fluid-saturated porous solid interface with an arbitrary finite surface stiffness. These extensions of the analytical method allows to theoretically study surface wave propagation phenomena during the saturation process. A modification to the 2-D space-time reflection Green's function (Feng and Johnson, JASA, 74, 915, 1983) is introduced in order to simulate the behavior of surface wave signals detected during the experimental investigation of surface wave propagation on fluid-saturated porous solids (Nagy, Appl. Phys. Lett., 60, 2735, 1992). This modification, together with the introduction of an excess attenuation for the Rayleigh surface mode, makes it possible to explain the apparent velocity changes observed on the surface wave signals during saturation. Experimental results concerning the propagation of surface waves on an alcohol-saturated porous glass are presented. These experiments were performed at frequencies of 500 and 800 kHz and show the simultaneous propagation of the two surface modes predicted by the extended analytical method. Finally an analysis of the displacements associated with the different surface modes is presented. This analysis reveals that it is possible to favor the generation of the Rayleigh surface mode or of the slow surface mode, simply by changing the type of transducer used in the generation of surface waves. Calculations show that a shear transducer couples more energy into the Rayleigh mode, whereas a longitudinal transducer couples more energy into the slow

  18. Subnanosecond measurements of detonation fronts in solid high explosives

    NASA Astrophysics Data System (ADS)

    Sheffield, S. A.; Bloomquist, D. D.; Tarver, C. M.

    1984-04-01

    Detonation fronts in solid high explosives have been examined through measurements of particle velocity histories resulting from the interaction of a detonation wave with a thin metal foil backed by a water window. Using a high time resolution velocity-interferometer system, experiments were conducted on three explosives—a TATB (1,3,5-triamino-trinitrobenzene)-based explosive called PBX-9502, TNT (2,4,6-Trinitrotoluene), and CP (2-{5-cyanotetrazolato} pentaamminecobalt {III} perchlorate). In all cases, detonation-front rise times were found to be less than the 300 ps resolution of the interferometer system. The thermodynamic state in the front of the detonation wave was estimated to be near the unreacted state determined from an extrapolation of low-pressure unreacted Hugoniot data for both TNT and PBX-9502 explosives. Computer calculations based on an ignition and growth model of a Zeldovich-von Neumann-Doering (ZND) detonation wave show good agreement with the measurements. By using the unreacted Hugoniot and a JWL equation of state for the reaction products, we estimated the initial reaction rate in the high explosive after the detonation wave front interacted with the foil to be 40 μs-1 for CP, 60 μs-1 for TNT, and 80 μs-1 for PBX-9502. The shape of the profiles indicates the reaction rate decreases as reaction proceeds.

  19. Subnanosecond measurements of detonation fronts in solid high explosives

    SciTech Connect

    Sheffield, S.A.; Bloomquist, D.D.; Tarver, C.M.

    1984-04-15

    Detonation fronts in solid high explosives have been examined through measurements of particle velocity histories resulting from the interaction of a detonation wave with a thin metal foil backed by a water window. Using a high time resolution velocity-interferometer system, experiments were conducted on three explosives: a TATB (1,3,5-triamino-trinitrobenzene)-based explosive called PBX-9502, TNT (2,4,6-Trinitrotoluene), and CP (2-)5-cyanotetrazolato) pentaamminecobalt )III) perchlorate). In all cases, detonation-front rise times were found to be less than the 300 ps resolution of the interferometer system. The thermodynamic state in the front of the detonation wave was estimated to be near the unreacted state determined from an extrapolation of low-pressure unreacted Hugoniot data for both TNT and PBX-9502 explosives. Computer calculations based on an ignition and growth model of a Zeldovich--von Neumann--Doering (ZND) detonation wave show good agreement with the measurements. By using the unreacted Hugoniot and a JWL equation of state for the reaction products, we estimated the initial reaction rate in the high explosive after the detonation wave front interacted with the foil to be 40 ..mu..s/sup -1/ for CP, 60 ..mu..s/sup -1/ for TNT, and 80 ..mu..s/sup -1/ for PBX-9502. The shape of the profiles indicates the reaction rate decreases as reaction proceeds.

  20. Angular distributions of 5eV atomic oxygen scattered from solid surfaces on the LDEF satellite

    NASA Technical Reports Server (NTRS)

    Gregory, John C.; Peters, Palmer N.

    1992-01-01

    The angular distribution of 5eV atomic oxygen scattered off several smooth solid surfaces was measured by experiment A0114 which flew on board the Long Duration Exposure Facility (LDEF). Target surfaces were silver, vitreous carbon, and lithium fluoride crystal. The apparatus was entirely passive. It used the property of silver surfaces to absorb oxygen atoms with high efficiency; the silver is converted to optically transmissive silver oxide. A collimated beam of oxygen atoms is allowed to fall on the target surface at some pre-set angle. Reflected atoms are then intercepted by a silver film placed so that it subtends a considerable solid angle from the primary beam impact on the target surface. The silver films are evaporated onto flexible optically-clear polycarbonate sheets which are scanned later to determine oxygen uptake. While the silver detector cannot measure atom velocity or energy, its physical configuration allows easy coverage of large angular space both in the beam-plane (that which includes the incident beam and the surface normal), and in the azimuthal plane of the target surface.

  1. Surface and bulk crystallization of amorphous solid water films: Confirmation of “top-down” crystallization

    SciTech Connect

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-01-11

    Here, the crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism was confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a “top-down” crystallization mechanism.

  2. Surface and bulk crystallization of amorphous solid water films: Confirmation of “top-down” crystallization

    SciTech Connect

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-10-01

    The crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism was confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a “top-down” crystallization mechanism.

  3. Surface and bulk crystallization of amorphous solid water films: Confirmation of “top-down” crystallization

    DOE PAGES

    Yuan, Chunqing; Smith, R. Scott; Kay, Bruce D.

    2016-01-11

    Here, the crystallization kinetics of nanoscale amorphous solid water (ASW) films are investigated using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). TPD measurements are used to probe surface crystallization and RAIRS measurements are used to probe bulk crystallization. Isothermal TPD results show that surface crystallization is independent of the film thickness (from 100 to 1000 ML). Conversely, the RAIRS measurements show that the bulk crystallization time increases linearly with increasing film thickness. These results suggest that nucleation and crystallization begin at the ASW/vacuum interface and then the crystallization growth front propagates linearly into the bulk. This mechanism wasmore » confirmed by selective placement of an isotopic layer (5% D2O in H2O) at various positions in an ASW (H2O) film. In this case, the closer the isotopic layer was to the vacuum interface, the earlier the isotopic layer crystallized. These experiments provide direct evidence to confirm that ASW crystallization in vacuum proceeds by a “top-down” crystallization mechanism.« less

  4. An Instrument for Real-Time Measurement of Solid Rocket Motor Insulation Erosion

    NASA Technical Reports Server (NTRS)

    McWhorter, B. B.

    1999-01-01

    An instrument (eroding potentionmeter) has been designed to measure real-time case wall and inhibitor insulation char depth within a rocket motor during firing. Thus measurement can be close to the real-time recession of the insulation surface. The eroding potentionmeter consists of two small (3 mils 9in diameter) twisted resistive wires that are polyimide insulated. The wire pair form an electrical circuit and will recede with the erosion of the rocket motor internal insulation. A constant current applied along the wires will detect the resistance change via a voltage drop across the wires as the wire pair recedes with the decomposition fo the insulation. The eroding potentionmeter, as presently designed, can be an effective tool for real time measurement of internal insulation recession of a solid rocket motor. This tool will provide a way to accurately measure inhibitor performance or to measure flight effects of insulation erosion on a flight test. The eroding potentiometer has been verified on a plasma torch test and two static tests of a small solid rocket motor. There are some irregularities in the measured date, but the data remains useful in determining the real-time performance of internal insulation during a motor firing.

  5. Surface compositions of solid and liquid indium-tin alloys by auger electron spectroscopy using ion bombardment

    SciTech Connect

    Komiyama, M.; Tsukamoto, H.; Ogino, Y.

    1986-09-01

    Equilibrium surface compositions of solid and liquid In-Sn alloys of various bulk compositions were examined by Auger electron spectroscopy. The composition relaxation at the solid surfaces of this alloy system was very fast, and utilizing this the bulk compositions of the solid alloys and the corresponding surface compositions were determined using Xe-ion bombardment in conjunction. Above the temperature 1.2 times the melting point, the surface compositions were constant regardless of temperature, and coincided with the nominal bulk composition. As the temperature was lowered toward the melting point, surface segregation became apparent, and at around the melting point the surface composition nearly coincided with those of the solid alloys. When surface segregation occurred, In segregated to the surfaces of Sn-rich alloys and Sn to the surfaces of In-rich alloys. Under the influence of surface oxygen In segregates to the solid surface at any alloy composition.

  6. Intensity offset and correction of solid spectral library samples measured behind glass

    SciTech Connect

    Bernacki, Bruce E.; Redding, Rebecca L.; Su, Yin-Fong; Brauer, Carolyn S.; Johnson, Timothy J.

    2013-05-18

    Accurate and calibrated diffuse reflectance spectra libraries of solids are becoming more important for hyperspectral and multispectral remote sensing exploitation. Many solids are in the form of powders or granules and in order to measure their diffuse reflectance spectra in the laboratory, it is often necessary to place the samples behind a transparent medium such as glass or quartz for the UV, visible or near-infrared spectral regions to prevent their unwanted dispersal into the instrument or laboratory environment. Using both experimental and theoretical methods we have found that for the case of fused quartz this leads to an intensity offset in the reflectance values. Although expected dispersive effects were observed for the fused quartz window in the UV, the measured hemispherical reflectance values are predominantly vertically shifted by the reflectance from the air-quartz and sample-quartz interfaces with intensity dependent offsets leading to measured values up to nearly 6% too high for a 2% reflectance surface, 3.8% too high for 10% reflecting materials, approximately correct (to within experimental error) for 40% to 60% diffuse reflecting surfaces, and 2% too low for 99% reflecting Spectralon surfaces. For the diffuse reflectance case, the measured values are uniformly too low due to the glass, with differences nearly 6% too high for reflectance values approaching 99%. The deviations arise from the added reflections from the quartz surfaces as verified by theory, modeling and experiment. Empirical correction factors were implemented into post-processing software to redress the artifact for hemispherical and diffuse reflectance data across the 300 nm to 2300 nm range.

  7. Intensity offset and correction of solid spectral library samples measured behind glass

    NASA Astrophysics Data System (ADS)

    Bernacki, Bruce E.; Redding, Rebecca L.; Su, Yin-Fong; Brauer, Carolyn S.; Johnson, Timothy J.

    2013-05-01

    Accurate and calibrated diffuse reflectance spectra libraries of solids are becoming more important for hyperspectral and multispectral remote sensing exploitation. Many solids are in the form of powders or granules and in order to measure their diffuse reflectance spectra in the laboratory, it is often necessary to place the samples behind a transparent medium such as glass or quartz for the ultraviolet (UV), visible or near-infrared spectral regions to prevent their unwanted dispersal into the instrument or laboratory environment. Using both experimental and theoretical methods we have found that for the case of fused quartz this leads to an intensity offset in the reflectance values. Although expected dispersive effects were observed for the fused quartz window in the UV, the measured hemispherical reflectance values are predominantly vertically shifted by the reflectance from the air-quartz and sample-quartz interfaces with intensity dependent offsets leading to measured values up to ˜6% too high for a 2% reflectance surface, ˜3.8% too high for 10% reflecting materials, approximately correct (to within experimental error) for 40% to 60% diffuse reflecting surfaces, and ˜2% too low for 99% reflecting Spectralon surfaces. For the diffuse reflectance case, the measured values are uniformly too low due to the glass, with differences nearly 6% too high for reflectance values approaching 99%. The deviations arise from the added reflections from the quartz surfaces as verified by theory, modeling and experiment. Empirical correction factors were implemented into post-processing software to redress the artifact for hemispherical and diffuse reflectance data across the 300 nm to 2300 nm range.

  8. Charge exchange of medium energy H and He ions emerging from solid surfaces

    NASA Astrophysics Data System (ADS)

    Kitsudo, Y.; Shibuya, K.; Nishimura, T.; Hoshino, Y.; Vickridge, I.; Kido, Y.

    2009-02-01

    Charge exchange of medium energy H and He ions emerging from clean solid surfaces is studied extensively using a toroidal electrostatic analyzer with an excellent energy resolution. The charge distributions of He ions scattered from sub-monolayers near a surface are non-equilibrated, resulting in a surface peak even for poly-crystal solids. By solving simultaneous rate equations numerically, we derive electron capture and loss cross sections for Ni and Au surfaces. Based on a free electron gas model, non-equilibrated He+ fractions dependent on emerging angle reveals uniform electronic surfaces for metals and corrugated surfaces for Si and graphite with covalent bonds. It is also found that equilibrium charge fractions of H+ are independent of surface materials (Z2) and in contrast equilibrium He+ fractions depend pronouncedly on Z2. The data obtained are compared with semi-empirical formulas.

  9. Acoustic Impedance Measurement for Underground Surfaces.

    NASA Astrophysics Data System (ADS)

    Cockcroft, Paul William

    Available from UMI in association with The British Library. Requires signed TDF. This thesis investigates the measurement of acoustic impedance for surfaces likely to be found in underground coal mines. By introducing the concepts of industrial noise, the effects of noise on the ear and relevant legislation the need for the protection of workers can be appreciated. Representative acoustic impedance values are vital as input for existing computer models that predict sound levels in various underground environments. These enable the mining engineer to predict the noise level at any point within a mine in the vicinity of noisy machinery. The concepts of acoustic intensity and acoustic impedance are investigated and different acoustic impedance measurement techniques are detailed. The possible use of either an impedance tube or an intensity meter for these kinds of measurements are suggested. The problems with acoustic intensity and acoustic impedance measurements are discussed with reference to the restraints that an underground environment imposes on any measurement technique. The impedance tube method for work in an acoustics laboratory is shown and the theory explained, accompanied by a few representative results. The use of a Metravib intensity meter in a soundproof chamber to gain impedance values is explained in detail. The accompanying software for the analysis of the two measured pressure signals is shown as well as the actual results for a variety of test surfaces. The use of a Nagra IV-SJ tape recorder is investigated to determine the effect of recording on the measurement and subsequent analysis of the input signals, particularly with reference to the phase difference introduced between the two simultaneous pressure signals. The subsequent use of a Norwegian Electronic intensity meter, including a proposal for underground work, is shown along with results for tests completed with this piece of equipment. Finally, recommendations are made on how to link up

  10. Thin Film Sensors for Surface Measurements

    NASA Technical Reports Server (NTRS)

    Martin, Lisa C.; Wrbanek, John D.; Fralick, Gustave C.

    2001-01-01

    Advanced thin film sensors that can provide accurate surface temperature, strain, and heat flux measurements have been developed at NASA Glenn Research Center. These sensors provide minimally intrusive characterization of advanced propulsion materials and components in hostile, high-temperature environments as well as validation of propulsion system design codes. The sensors are designed for applications on different material systems and engine components for testing in engine simulation facilities. Thin film thermocouples and strain gauges for the measurement of surface temperature and strain have been demonstrated on metals, ceramics and advanced ceramic-based composites of various component configurations. Test environments have included both air-breathing and space propulsion-based engine and burner rig environments at surface temperatures up to 1100 C and under high gas flow and pressure conditions. The technologies developed for these sensors as well as for a thin film heat flux gauge have been integrated into a single multifunctional gauge for the simultaneous real-time measurement of surface temperature, strain, and heat flux. This is the first step toward the development of smart sensors with integrated signal conditioning and high temperature electronics that would have the capability to provide feedback to the operating system in real-time. A description of the fabrication process for the thin film sensors and multifunctional gauge will be provided. In addition, the material systems on which the sensors have been demonstrated, the test facilities and the results of the tests to-date will be described. Finally, the results will be provided of the current effort to demonstrate the capabilities of the multifunctional gauge.

  11. Physics of solid and liquid alkali halide surfaces near the melting point

    NASA Astrophysics Data System (ADS)

    Zykova-Timan, T.; Ceresoli, D.; Tartaglino, U.; Tosatti, E.

    2005-10-01

    This paper presents a broad theoretical and simulation study of the high-temperature behavior of crystalline alkali halide surfaces typified by NaCl(100), of the liquid NaCl surface near freezing, and of the very unusual partial wetting of the solid surface by the melt. Simulations are conducted using two-body rigid-ion Born-Mayer-Huggins-Fumi-Tosi (BMHFT) potentials, with full treatment of long-range Coulomb forces. After a preliminary check of the description of bulk NaCl provided by these potentials, which seems generally good even at the melting point, we carry out a new investigation of solid and liquid surfaces. Solid NaCl(100) is found in this model to be very anharmonic and yet exceptionally stable when hot. It is predicted by a thermodynamic integration calculation of the surface free energy that NaCl(100) should be a well-ordered, nonmelting surface, metastable even well above the melting point. By contrast, the simulated liquid NaCl surface is found to exhibit large thermal fluctuations and no layering order. In spite of that, it is shown to possess a relatively large surface free energy. The latter is traced to a surface entropy deficit, reflecting some kind of surface short-range order. We show that the surface short-range order is most likely caused by the continuous transition of the bulk ionic melt into the vapor, made of NaCl molecules and dimers rather than of single ions. Finally, the solid-liquid interface free energy is derived through Young's equation from direct simulation of partial wetting of NaCl(100) by a liquid droplet. The resulting interface free energy is large, in line with the conspicuous solid-liquid 27% density difference. A partial wetting angle near 50° close to the experimental value of 48° is obtained in the process. It is concluded that three elements, namely, the exceptional anharmonic stability of the solid (100) surface, the molecular short-range order at the liquid surface, and the costly solid-liquid interface, all

  12. Effect of Paramagnetic Ions on NMR Relaxation of Fluids at Solid Surfaces

    NASA Astrophysics Data System (ADS)

    Foley, I.; Farooqui, S. A.; Kleinberg, R. L.

    Proton NMR longitudinal and transverse relaxation times of water-saturated powder packs have been measured. The powders were a series of synthetic calcium silicates with known concentrations of iron or manganese paramagnetic ions. The rate of water proton relaxation has been found to be linearly proportional to the concentration of paramagnetic ion. The constant of proportionality is used to determine the electron relaxation time of ions at the fluid-solid interface. A substantial relaxivity is found in the absence of paramagnetic ions. Thus the oxide surface itself is an unexpectedly good relaxer of fluid-borne nuclear spins. The results answer some long-standing questions connected with the NMR properties of fluid-saturated sedimentary rocks.

  13. Interactions of the Cluster Beams with Solid Surfaces

    NASA Astrophysics Data System (ADS)

    Nakagawa, Sachiko T.

    The characteristics of a cluster beam interaction with a solid target are reviewed from the viewpoint of computer simulation. The similarity and dissimilarity of irradiation effects between single and cluster ion beams are the main emphasis of the review. The speed-range of a projectile studied is below the Bethe range (v1≤v0 Z1) but not so low, where electronic energy loss is significant. Because of the multiple collisions (in time and space) a classical molecular dynamic simulation is useful, whereas the multiplicity in energy is more significant for a molecular projectile. Here the collision stage of energy transfer from a projectile to target during the collision stage is separated from the succeeding relaxation stage. The multiplicity in the collision stage can cause molecular effects, however they are not always so significant. In the relaxation stage a somewhat enhanced effect can occur when the locally deposited energy exceeds a certain level.

  14. Microalgae Scatter off Solid Surfaces by Hydrodynamic and Contact Forces

    NASA Astrophysics Data System (ADS)

    Contino, Matteo; Lushi, Enkeleida; Tuval, Idan; Kantsler, Vasily; Polin, Marco

    2015-12-01

    Interactions between microorganisms and solid boundaries play an important role in biological processes, such as egg fertilization, biofilm formation, and soil colonization, where microswimmers move within a structured environment. Despite recent efforts to understand their origin, it is not clear whether these interactions can be understood as being fundamentally of hydrodynamic origin or hinging on the swimmer's direct contact with the obstacle. Using a combination of experiments and simulations, here we study in detail the interaction of the biflagellate green alga Chlamydomonas reinhardtii, widely used as a model puller microorganism, with convex obstacles, a geometry ideally suited to highlight the different roles of steric and hydrodynamic effects. Our results reveal that both kinds of forces are crucial for the correct description of the interaction of this class of flagellated microorganisms with boundaries.

  15. Preface: Special Topic Section on Advanced Electronic Structure Methods for Solids and Surfaces

    SciTech Connect

    Michaelides, Angelos; Martinez, Todd J.; Alavi, Ali; Kresse, Georg

    2015-09-14

    This Special Topic section on Advanced Electronic Structure Methods for Solids and Surfaces contains a collection of research papers that showcase recent advances in the high accuracy prediction of materials and surface properties. It provides a timely snapshot of a growing field that is of broad importance to chemistry, physics, and materials science.

  16. Freezing of Water next to Solid Surfaces Probed Using Sum-Frequency Generation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Anim-Danso, Emmanuel; Kurian, Anish; Ge, Liehui; Alizadeh, Azar; Dhinojwala, Ali

    2012-02-01

    The control of ice formation next to solid surfaces is important in many technological applications such as de-icing for aircrafts and generation of power using wind turbines. We have studied the water-ice transition next to sapphire surface to understand the freezing transition and nucleation of ice. The infrared-visible sum frequency generation spectroscopy is sensitive to the structure and orientation of water molecules next to the solid interface and provides direct information on transition kinetics at the interface. The differences in the nucleation kinetics will be discussed for water in contact with hydrophilic and hydrophobic surfaces.

  17. Switching in of Ac-(Ala)10-NHMe at a solid surface.

    PubMed

    Biggs, Mark J; Mijajlovic, Milan

    2008-09-01

    Using molecular simulation, we show how Ac-(Ala)(10)-NHMe adsorbed on a solid surface switches between three conformations at distinct surface energies. The first switch is from an alpha-helix to a 3.1(10)-helix. The second involves further stretching to a 2(7)-helix. This switching has several potential applications including memory in molecular computers to motility elements in nanotechnology, and could be relevant to biological activity of proteins near solid surfaces (e.g., nano and aerosol particles) and disease processes induced by such interactions.

  18. Fractal properties of aggregates of metal nanoclusters on solid surface

    NASA Astrophysics Data System (ADS)

    Samsonov, V. M.; Kuznetsova, Yu. V.; D'yakova, E. V.

    2016-02-01

    AFM images are used to determine and analyze fractal characteristics (cluster fraction dimension and lacunarity) of aggregates of Au and Ag nanoclusters on metal films of the same metal produced with the aid of thermal vacuum deposition on mica surface. A fractal dimension of 1.6 that corresponds to typical samples with relatively uniform distribution of nanoclusters on the film surface is in agreement with the mean value calculated from experimental data of Belko et al., who studied the fractal dimension of Au nanoclusters on a different dielectric (quartz) surface. When a compact single aggregate of Au nanoclusters is formed on a certain active center or defect, the fractal cluster dimension decreases to 1.4. The experimental data are compared with the results of existing theoretical models of association of nanoclusters in 2D systems.

  19. Relativistic Laser Acceleration Of Electrons Along Solid Surfaces

    NASA Astrophysics Data System (ADS)

    Sheng, Z. M.; Li, Y. T.; Chen, M.; Ma, Y. Y.; Yuan, X. H.; Xu, M. H.; Zheng, Z. Y.; Liang, W. X.; Yu, Q. Z.; Zhang, Y.; Liu, F.; Wang, Z. H.; Wei, Z. Y.; Jin, Z.; Zhang, J.; Nakamura, T.; Mima, K.

    2006-12-01

    Recent experimental and theoretical studies on surface electron emission will be presented. A collimated fast electron beam was observed along the target surface irradiated by intense laser pulses up to 20TW when the laser is incident with large angles such as over 45 degree. Numerical simulations suggest that such an electron beam is formed due to the confinement of the surface quasistatic electric and magnetic fields. Meanwhile, an acceleration process similar to the inverse-free-electron-laser is found to occur and is responsible for the generation of the most energetic electrons. A general formula for electron angular distributions accounting for the quasistatic electric and magnetic fields is given. In certain conditions, quasi-monoenergetic electron beams are also produced. These results are of interest for potential applications of laser-produced electron beams and helpful to the undersanding of the cone-target physics in the fast ignition related experiments.

  20. Deformation Measurements of Smart Aerodynamic Surfaces

    NASA Technical Reports Server (NTRS)

    Fleming, Gary A.; Burner, Alpheus

    2005-01-01

    Video Model Deformation (VMD) and Projection Moire Interferometry (PMI) were used to acquire wind tunnel model deformation measurements of the Northrop Grumman-built Smart Wing tested in the NASA Langley Transonic Dynamics Tunnel. The F18-E/F planform Smart Wing was outfitted with embedded shape memory alloys to actuate a seamless trailing edge aileron and flap, and an embedded torque tube to generate wing twist. The VMD system was used to obtain highly accurate deformation measurements at three spanwise locations along the main body of the wing, and at spanwise locations on the flap and aileron. The PMI system was used to obtain full-field wing shape and deformation measurements over the entire wing lower surface. Although less accurate than the VMD system, the PMI system revealed deformations occurring between VMD target rows indistinguishable by VMD. This paper presents the VMD and PMI techniques and discusses their application in the Smart Wing test.

  1. Deformation measurements of smart aerodynamic surfaces

    NASA Astrophysics Data System (ADS)

    Fleming, Gary A.; Burner, Alpheus W.

    1999-10-01

    Video Model Deformation (VMD) and Projection Moire Interferometry (PMI) were used to acquire wind tunnel model deformation measurements of the Northrop Grumman-built Smart Wing tested in the NASA Langley Transonic Dynamics Tunnel. The F18-E/F platform Smart Wing was outfitted with embedded shape memory alloys to actuate a seamless trailing edge aileron and flat, and an embedded torque tube to generate wing twist. The VMD system was used to obtain highly accurate deformation measurements at three spanwise locations along the main body of the wing, and at spanwise locations on the flap and aileron. The PMI system was used to obtain full-field wing shape and deformation measurements over the entire wing lower surface. Although less accurate than the VMD system, the PMI system revealed deformations occurring between VMD target rows indistinguishable by VMD. This paper presents the VMD and PMI techniques and discusses their application in the Smart Wing test.

  2. Surface ozone measurements using differential absorption lidar

    NASA Astrophysics Data System (ADS)

    Jain, Sohan L.; Arya, B. C.; Ghude, Sachin D.; Arora, Arun K.; Sinha, Randhir K.

    2005-01-01

    Human activities have been influencing the global atmosphere since the beginning of the industrial era, causing shifts from its natural state. The measurements have shown that tropospheric ozone is increasing gradually due to anthropogenic activities. Surface ozone is a secondary pollutant, its concentration in lower troposphere depends upon its precursors (CO, CH4, non methane hydrocarbons, NOx) as well as weather and transport phenomenon. The surface ozone exceeding the ambient air quality standard is health hazard to human being, animal and vegetation. The regular information of its concentrations on ground levels is needed for setting ambient air quality objectives and understanding photo chemical air pollution in urban areas. A Differential Absorption Lidar (DIAL) using a tunable CO2 laser has been designed and developed at National Physical Laboratory, New Delhi, to monitor water vapour, surface ozone, ammonia, ethylene etc. Some times ethylene and surface ozone was found to be more than 40 ppb and 140 ppb respectively which is a health hazard. Seasonal variation in ozone concentrations shows maximum in the months of summer and autumn and minimum in monsoon and winter months. In present communication salient features of experimental set up and results obtained will be presented in detail.

  3. Pulsed surface flashover across solid insulators in vacuum

    NASA Technical Reports Server (NTRS)

    Ko, S. T.; Lakdawala, V. K.

    1985-01-01

    The phenomenon of pulsed surface flashover is studied using a fast image converter camera. A still photograph of a surface flashover for a TiO2 test piece reveals that the breakdown path is a straight line perpendicular to the streak direction. It is found that visible light is initially emitted from the cathode and that the light front propagates at a constant speed of about 1 x 10 to the 7th m/s. The low luminous light is emitted up to the point where the gap is bridged by the bright light.

  4. Pulsed surface flashover across solid insulators in vacuum

    NASA Technical Reports Server (NTRS)

    Ko, S. T.; Lakdawala, V. K.

    1985-01-01

    The phenomenon of pulsed surface flashover is studied using a fast image converter camera. A still photograph of a surface flashover for a TiO2 test piece reveals that the breakdown path is a straight line perpendicular to the streak direction. It is found that visible light is initially emitted from the cathode and that the light front propagates at a constant speed of about 1 x 10 to the 7th m/s. The low luminous light is emitted up to the point where the gap is bridged by the bright light.

  5. [Response surface method optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis preparation genistein].

    PubMed

    Jin, Xin; Zhang, Zhen-Hai; Zhu, Jing; Sun, E; Yu, Dan-Hong; Chen, Xiao-Yun; Liu, Qi-Yuan; Ning, Qing; Jia, Xiao-Bin

    2012-04-01

    This article reports that nano-silica solid dispersion technology was used to raise genistein efficiency through increasing the enzymatic hydrolysis rate. Firstly, genistin-nano-silica solid dispersion was prepared by solvent method. And differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were used to verify the formation of solid dispersion, then enzymatic hydrolysis of solid dispersion was done by snailase to get genistein. With the conversion of genistein as criteria, single factor experiments were used to study the different factors affecting enzymatic hydrolysis of genistin and its solid dispersion. And then, response surface method was used to optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis. The optimum condition to get genistein through enzymatic hydrolysis of genistin-nano-silica solid dispersion was pH 7.1, temperature 52.2 degrees C, enzyme concentration 5.0 mg x mL(-1) and reaction time 7 h. Under this condition, the conversion of genistein was (93.47 +/- 2.40)%. Comparing with that without forming the genistin-nano-silica solid dispersion, the conversion increased 2.62 fold. At the same time, the product of hydrolysis was purified to get pure genistein. The method of enzymatic hydrolysis of genistin-nano-silica solid dispersion by snailase to obtain genistein is simple, efficiency and suitable for the modern scale production.

  6. Improved method of measuring pressure coupled response for composite solid propellants

    NASA Astrophysics Data System (ADS)

    Su, Wanxing; Wang, Ningfei; Li, Junwei; Zhao, Yandong; Yan, Mi

    2014-04-01

    Pressure coupled response is one of the main causes of combustion instability in the solid rocket motor. It is also a characteristic parameter for predicting the stability. The pressure coupled response function is usually measured by different methods to evaluate the performance of new propellant. Based on T-burner and "burning surface doubled and secondary attenuation", an improved method for measuring the pressure coupled response of composite propellant is introduced in this article. A computational fluid dynamics (CFD) study has also been conducted to validate the method and to understand the pressure oscillation phenomenon in T-burner. Three rounds of tests were carried out on the same batch of aluminized AP/HTPB composite solid propellant. The experimental results show that the sample propellant had a high response function under the conditions of high pressure (~11.5 MPa) and low frequency (~140 Hz). The numerically predicted oscillation frequency and amplitude are consistent with the experimental results. One practical solid rocket motor using this sample propellant was found to experience pressure oscillation at the end of burning. This confirms that the sample propellant is prone to combustion instability. Finally, acoustic pressure distribution and phase difference in T-burner were analyzed. Both the experimental and numerical results are found to be associated with similar acoustic pressure distribution. And the phase difference analysis showed that the pressure oscillations at the head end of the T-burner are 180° out of phase from those in the aft end of the T-burner.

  7. The Scattering of Gas Atoms from Solid Surfaces

    ERIC Educational Resources Information Center

    Walton, Alan J.

    1977-01-01

    Traditional undergraduate courses in gas kinetic theory encourage the view that in all collisions between a gas atom and a surface, the angle of incidence of the gas atom equals its angle of reflection. This article illustrates and explains the incorrectness in assuming specular reflection and zero dwell time. (Author/MA)

  8. Electronic Structure of Solids and Their Surfaces and Interfaces.

    DTIC Science & Technology

    1981-06-30

    adjustments to the -seudopotentials, but it h-sn’t worked weJ . When nonlocal pseudopotf!ntials were used, as in the calculqtio-s of (’helikowshy...Study of H Chemisorption on NiO Surfaces", Phys. Rev. Lett. 40, 347 -350 (1978). 5. A. B. Kunz and D. L. Klein, "Unrestricted Hartree-Fock Approach to

  9. Metal halide solid-state surface treatment for nanocrystal materials

    DOEpatents

    Luther, Joseph M.; Crisp, Ryan; Beard, Matthew C.

    2016-04-26

    Methods of treating nanocrystal and/or quantum dot devices are described. The methods include contacting the nanocrystals and/or quantum dots with a solution including metal ions and halogen ions, such that the solution displaces native ligands present on the surface of the nanocrystals and/or quantum dots via ligand exchange.

  10. The Scattering of Gas Atoms from Solid Surfaces

    ERIC Educational Resources Information Center

    Walton, Alan J.

    1977-01-01

    Traditional undergraduate courses in gas kinetic theory encourage the view that in all collisions between a gas atom and a surface, the angle of incidence of the gas atom equals its angle of reflection. This article illustrates and explains the incorrectness in assuming specular reflection and zero dwell time. (Author/MA)

  11. Hydroxyapatite synthesis on solid surfaces using a biological approach

    NASA Astrophysics Data System (ADS)

    Wang, A.; Mei, J.; Tse, Y. Y.; Jones, I. P.; Sammons, R. L.

    2012-12-01

    Many naturally occurring mineralisation processes yield hydroxyapatite (HA) or related salts, but biological routes to calcification have not generally been exploited for production of hydroxyapatite for clinical and industrial applications. Serratia sp. NCIMB 40259 is a non-pathogenic Gram-negative bacterium which is capable of growing as a biofilm on many surfaces and can be used to form HA coatings on a variety of polymeric and metallic materials, including titanium. Here we review previous work and report the results of more recent studies on the influence of titanium compositional and surface properties on Serratia adherence and proliferation and biomineralisation on commercially pure titanium (cp Ti) discs and a Ti mesh. Bacterial adherence was equivalent on cpTi and Ti6Al4V, and biofilms formed on both rough and mirror-polished cpTi surfaces. Embedded alumina particles and alkali treatment did not noticeably alter the precipitation of Serratia HA, nor the structure of the coating in comparison with non-treated substrates. Coatings were retained after sintering at 800°C in argon, although the original curved plate-like crystals changed to nano-scale β-tricalcium phosphate particles. A phosphorous-rich diffusion zone formed at the coating-titanium interface. Bacterial mineralisation may have applications as a method for producing coatings on implants in non load-bearing sites, and non-clinical applications where a high surface area is the major concern.

  12. Predicting second gas-solid virial coefficients using calculated molecular properties on various carbon surfaces.

    PubMed

    Rybolt, Thomas R; Janeksela, Vanessa E; Hooper, Dana N; Thomas, Howard E; Carrington, Nathan A; Williamson, Eric J

    2004-04-01

    Gas-solid chromatography was used to obtain values of the second gas-solid virial coefficient, B2s, in the temperature range from 343 to 493 K for seven adsorbate gases: methane, ethane, propane, chloromethane, chlorodifluoromethane, dimethyl ether, and sulfur hexafluoride. Carboxen-1000, a 1200 m2/g carbon molecular sieve (Supelco Inc.), was used as the adsorbent. These data were combined with earlier work to make a combined data set of 36 different adsorbate gases variously interacting with from one to four different carbon surfaces. All B2s values were extrapolated to 403 K to create a set of 65 different gas-solid B2s values at a fixed temperature. The B2s value for a given gas-solid system can be converted to a chromatographic retention time at any desired flow rate and can be converted to the amount of gas adsorbed at any pressure in the low-coverage, Henry's law region. Beginning with a theoretical equation for the second gas-solid virial coefficient, various quantitative structure retention relations (QSRR) were developed and used to correlate the B2s values for different gas adsorbates with different carbon surfaces. Two calculated adsorbate molecular parameters (molar refractivity and connectivity index), when combined with two adsorbent parameters (surface area and a surface energy contribution to the gas-solid interaction), provided an effective correlation (r2 = 0.952) of the 65 different B2s values. The two surface parameters provided a simple yet useful representation of the structure and energy of the carbon surfaces and thus our correlations considered variation in both the adsorbate gas and the adsorbent solid.

  13. Interferometer Development for Study of Interactions between Flames on Parallel Solid Surfaces

    NASA Technical Reports Server (NTRS)

    Goldmeer, J. S.; Urban, D. L.; Yuan, Z. G.

    1999-01-01

    The interactions between flames spreading over parallel solid sheets of paper are being studied in normal gravity and in microgravity. This geometry provides interesting opportunities to study the interaction of radiative and diffusive transport mechanisms on the spread process. These transport mechanisms are changed when the flame interacts with other flames. Most practical heterogeneous combustion processes involve interacting discrete burning fuel elements, consequently, the study of these interactions is of practical significance. Owing largely to this practical importance, flame interactions have been an area of active research, however microgravity research has been largely limited to droplets. Consideration of flame spread over parallel solid surfaces has been limited to 1-g studies. To study the conductive transport in these flames, an interferometer system has been developed for use in the drop tower. The system takes advantage of a single beam interferometer: Point Diffraction Interferometry (PDI) which uses a portion of the light through the test section to provide the reference beam. Like other interferometric and Schlieren systems, it is a line of sight measurement and is subject to the usual edge and concentration effects. The advantage over Schlieren and shearing interferometry systems is that the fringes are lines of constant index of refraction rather than of its gradient so the images are more readily interpreted. The disadvantage is that it is less able to accommodate a range of temperature gradients.

  14. Uncertainty in measurement of surface topography

    NASA Astrophysics Data System (ADS)

    Haitjema, Han

    2015-09-01

    The 2.5-dimensional (2.5D) roughness parameters were standardized in 2012. With their increasing use in science and industry, the request for traceability and uncertainty evaluation for these parameters follows logically. This paper gives an overview of the problems and possibilities that appear when uncertainties have to be associated with values that are derived from a measured surface topography, such as the Ra-value of a periodic specimen, the RSm value of a type-D standard, and the Sa-value of a single cutoff length of a type D standard. It is shown that straightforward implementation of the methods described in the ‘Guide to the Expression of Uncertainty in Measurement’ (GUM) leads to impossible and impracticable equations because of the correlations between some millions of measurement points. A practical solution is found by considering the main aspects of uncertainty, as these are given in the recent ISO 25178 standards series, and applying these to a measured surface topography as a whole.

  15. Passive manipulation of free-surface instability by deformable solid bilayers

    NASA Astrophysics Data System (ADS)

    Sahu, Shivam; Shankar, V.

    2016-07-01

    This study deals with the elastohydrodynamic coupling that occurs in the flow of a liquid layer down an inclined plane lined with a deformable solid bilayer and its consequences on the stability of the free surface of the liquid layer. The fluid is Newtonian and incompressible, while the linear elastic constitutive relation has been considered for the deformable solid bilayer, and the densities of the fluid and the two solids are kept equal. A temporal linear stability analysis is carried out for this coupled solid-fluid system. A long-wave asymptotic analysis is employed to obtain an analytical expression for the complex wavespeed in the low wave-number regime, and a numerical shooting method is used to solve the coupled set of governing differential equations in order to obtain the stability criterion for arbitrary values of the wave number. In a previous work on plane Couette flow past an elastic bilayer, Neelmegam et al. [Phys. Rev. E 90, 043004 (2014), 10.1103/PhysRevE.90.043004] showed that the instability of the flow can be significantly influenced by the nature of the solid layer, which is adjacent to the liquid layer. In stark contrast, for free-surface flow past a bilayer, our long-wave asymptotic analysis demonstrates that the stability of the free-surface mode is insensitive to the nature of the solid adjacent to the liquid layer. Instead, it is the effective shear modulus of the bilayer Geff (given by H /Geff=H1/G1+H2/G2 , where H =H1+H2 is the total thickness of the solid bilayer, H1 and H2 are the thicknesses of the two solid layers, and G1 and G2 are the shear moduli of the two solid layers) that determines the stability of the free surface in the long-wave limit. We show that for a given Reynolds number, the free-surface instability is stabilized when Geff decreases below a critical value. At finite wave numbers, our numerical solution indicates that additional instabilities at the free surface and the liquid-solid interface can be induced by wall

  16. PMMA Solid bottle optical microresonator for measure relative humidity.

    NASA Astrophysics Data System (ADS)

    Avila, D. A.; Horta, S. D.; Torres, C. O.

    2017-01-01

    In this work we studied experimentally the performance of an solid bottle optical resonator made of PMMA (polymethylmethacrylate) for measure the relative humidity of the medium. In the developed device, the WGMs modes within the microcavity are excited by the proximity of an optical fiber taper with an outer diameter of the order of 3-5 microns made from stretching a standard optical fiber of Silica by the flame brushing technique. In the resonant device, the field produced by a laser system tunable TLS is guided through the fiber taper and is coupled into the microcavity by the approach of the fiber taper to the equatorial zone of the microbottle, causing the excitation of the WGMs resonant modes inside the same. When the device is subjected to changes in relative humidity of the medium, the wavelengths of resonance of WGMs modes that have been coupled in the microresonator are shifted spectrally depending on the external humidity, showing an experimental sensitivity in the resonator due to changes in the relative humidity of the medium. In the experiment, it was possible to produce different samples of optical resonators with a profile shaped bottle with different maximum diameters achieving a maximum sensitivity of 0.032 nm/% RH for a resonator with equatorial diameter of 1250 μm.

  17. Indium adhesion provides quantitative measure of surface cleanliness

    NASA Technical Reports Server (NTRS)

    Krieger, G. L.; Wilson, G. J.

    1968-01-01

    Indium tipped probe measures hydrophobic and hydrophilic contaminants on rough and smooth surfaces. The force needed to pull the indium tip, which adheres to a clean surface, away from the surface provides a quantitative measure of cleanliness.

  18. Thermodynamic, kinetic and conformational analysis of proteins diffusion-sorption on a solid surface.

    PubMed

    Sanfeld, Albert; Royer, Catherine; Steinchen, Annie

    2015-08-01

    In this paper we examine particularly some of the more fundamental properties of protein conformational changes at a solid surface coupled with diffusion from the bulk of an aqueous solution and with the adsorption-desorption processes. We focus our attention on adsorbed protein monolayers upon a solid surface using a thermodynamic and kinetic analytical development. Account is also taken of the effects on the overall rate of the conformational change on a solid surface of deviation from ideality, of protein flexibility, of surface free energy and of interaction with reactive solid sites. Our theory applied to steady states is illustrated by examples such as folding-misfolding-unfolding of RNase and SNase on a solid surface after diffusion and adsorption from an aqueous solution. For this purpose, we put forward the determining steps which shall lead to the steady state. The existence of three situations is highlighted according to the values of the typical constants relevant for the protein considered: reaction rate determining step, diffusion and sorption determining steps, mixed adsorption diffusion and reaction rate. Finally, we have tried to link the developments of our theories to a large literature based on experimental results encountered during proteins diffusion-sorption-reaction processes, fundamental topics that has been since long investigated by Miller's team in MPKG.

  19. Random Process Theory Approach to Geometric Heterogeneous Surfaces: Effective Fluid-Solid Interaction

    NASA Astrophysics Data System (ADS)

    Khlyupin, Aleksey; Aslyamov, Timur

    2017-06-01

    Realistic fluid-solid interaction potentials are essential in description of confined fluids especially in the case of geometric heterogeneous surfaces. Correlated random field is considered as a model of random surface with high geometric roughness. We provide the general theory of effective coarse-grained fluid-solid potential by proper averaging of the free energy of fluid molecules which interact with the solid media. This procedure is largely based on the theory of random processes. We apply first passage time probability problem and assume the local Markov properties of random surfaces. General expression of effective fluid-solid potential is obtained. In the case of small surface irregularities analytical approximation for effective potential is proposed. Both amorphous materials with large surface roughness and crystalline solids with several types of fcc lattices are considered. It is shown that the wider the lattice spacing in terms of molecular diameter of the fluid, the more obtained potentials differ from classical ones. A comparison with published Monte-Carlo simulations was discussed. The work provides a promising approach to explore how the random geometric heterogeneity affects on thermodynamic properties of the fluids.

  20. Studies of Ternary Surface Complexes at Liquid-Solid Interfaces in Seawater

    PubMed

    Zhengbin; Wei; Liansheng; Youjun; Zhijian

    1997-06-01

    The E (%)-pH curves of the ternary surface complexes at liquid-solid interfaces in the simulated seawater system of alpha-FeOOH-Cu(II)-tryptophan were determined. The diffuse reflectance IR spectra of the species at the solid surfaces in the above ternary equilibration system were examined. The above two results were comparatively studied. It is shown that the coadsorption of Cu(II) and tryptophan on alpha-FeOOH surface results in the formation of the ternary surface complex. Cu(II) can promote the exchange adsorption of tryptophan on alpha-FeOOH surface. The diffuse reflectance IR spectra can give us some evidence for the structure of the ternary surface complex, and these results are in accordance with the results of the E (%)-pH curves.

  1. Molecular weight evaluation of poly-dimethylsiloxane on solid surfaces using silver deposition/TOF-SIMS

    NASA Astrophysics Data System (ADS)

    Inoue, Masae; Murase, Atsushi

    2004-06-01

    Molecular ions include information about end groups, functional groups and molecular weight. A method for directly detecting this in the high-mass region of the spectrum (>1000 amu) from poly-dimethylsiloxane (PDMS) on a solid surface was investigated. It was found that a TOF-SIMS analysis of silver-deposited surfaces (silver deposition/TOF-SIMS) is useful for this purpose. Two methods for silver deposition, the diode sputtering method and the vacuum evaporation coating method, were tried. The former required the sample to be cooled so as to prevent the damage of the sample surface due to thermal oxidation; the latter caused no damage to sample surfaces at room temperature. Using silver deposition/TOF-SIMS analysis, silver-cationized quasi-molecular ions were clearly detected from PDMS on solid surfaces and their images were observed without the interference of deposited silver. By applying to the analysis of paint defects, etc., it was confirmed that this technique is useful to analyze practical industrial materials. Silver-cationized ions were detected not only from PDMS, but also from other organic materials, such as some kinds of lubricant additives and fluorine oils on solid surfaces. Therefore, silver deposition/TOF-SIMS was proved to be useful for the analysis of thin substances on solid surfaces.

  2. The dynamics of the water droplet impacting onto hot solid surfaces at medium Weber numbers

    NASA Astrophysics Data System (ADS)

    Mitrakusuma, Windy H.; Kamal, Samsul; Indarto; Dyan Susila, M.; Hermawan; Deendarlianto

    2017-10-01

    The effects of the wettability of a droplet impacting onto a hot solid surface under medium Weber numbers were studied experimentally. The Weber numbers used in the present experiment were 52.1, 57.6, and 63.1. Three kinds of solid surfaces with different wettability were used. These were normal stainless steel (NSS), TiO2 coated NSS, and TiO2 coated NSS radiated with ultraviolet rays. The surface temperatures were varied from 60 to 200 °C. The image of side the view and 30° from horizontal were taken to explain the spreading and the interfacial behavior of a single droplet during impact the hot solid surfaces. It was found that under medium Weber numbers, the surface wettability plays an important role on the droplet spreading and evaporation time during the impact on the hot solid surfaces. The higher the wettability, the larger the droplet spreading on the hot surface, and the lower the evaporation time.

  3. Free-Surface Optical Scattering as an Indicator of the Shock-Induced Solid-Liquid Phase Transition in Tin

    SciTech Connect

    Stevens, G. D.; Lutz, S. S.; Marshall, B. R.; Turley, W. D.; Veeser, L. R.; Furlanetto, M. R.; Hixson, R. S.; Holtkamp, D. B.; Jensen, B. J.; Rigg, P. A.; Wilke, M. D.

    2008-07-01

    When highly polished metal surfaces melt upon release after shock loading, they exhibit features that suggest significant surface changes accompany the phase transition. The reflection of light from such surfaces changes from specular (pre-shock) to diffuse upon melting. A familiar manifestation of this phenomenon is the loss of signal light in VISAR measurements, which occurs at pressures high enough to melt the free surface. Unlike many other potential material phase-sensitive diagnostics (e.g., reflectometry, conductivity) that show relatively small (1%–10%) changes, the specularity of reflection provides a more sensitive and definitive indication of the solid-liquid phase transition. Data will be presented that support the hypothesis that specularity changes indicate melt in a way that can be measured easily and unambiguously.

  4. Lenticular array for spatial filtering velocimetry of laser speckles from solid surfaces.

    PubMed

    Jakobsen, Michael L; Hanson, Steen G

    2004-08-20

    We present a low-cost optical design for the detection of speckle translation, which can provide measures of in-plane translation or the rotation of a solid structure. A nonspecular target surface is illuminated with coherent light. The scattered light is propagated through an optical arrangement that has been particularly designed for the type of mechanical measurand for which the sensor is intended. The dynamics of the speckle field that arise from the target surface are projected onto a lenticular array, constituting a narrow spatial bandpass filter for the speckle spectrum. The filter provides access to the full phase information of the temporal quasi-sinusoidal intensity output; thus differential arrangements of photodetectors can provide suppression of low-frequency oscillations and higher harmonics, and the direction of the speckle translation can be determined. The spatial filter of the sensor is characterized, and the precision of the sensor when it is integrated with an electronic zero-crossing-detection processor is investigated. The best measurement accuracy obtained at constant velocity is 1% at 1.6-mm translation; the relative standard deviation decreases with the square root of the distance traveled.

  5. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    SciTech Connect

    Liaw, B.Y.; Song, S.Y.

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  6. Gas-Solid Dynamics at Disordered and Adsorbate Covered Surfaces.

    DTIC Science & Technology

    1987-05-15

    Schrodinger equation . Specific numerical results are presented for pulses of area equal to v, 21r, 31r, 4r and 51r for both symmetric and asymmetric... Semiclassical Perturbation Theory for Atom Scattering from Surfaces with Defects 1 Presented here is an extension of semiclassical perturbation theory (SCP...Involved in solving the AWM equations in equivalent to that Involved for elastic scattering in the same formulation. As an initial Illustration, expUclt

  7. Test data from small solid propellant rocket motor plume measurements (FA-21)

    NASA Technical Reports Server (NTRS)

    Hair, L. M.; Somers, R. E.

    1976-01-01

    A program is described for obtaining a reliable, parametric set of measurements in the exhaust plumes of solid propellant rocket motors. Plume measurements included pressures, temperatures, forces, heat transfer rates, particle sampling, and high-speed movies. Approximately 210,000 digital data points and 15,000 movie frames were acquired. Measurements were made at points in the plumes via rake-mounted probes, and on the surface of a large plate impinged by the exhaust plume. Parametric variations were made in pressure altitude, propellant aluminum loading, impinged plate incidence angle and distance from nozzle exit to plate or rake. Reliability was incorporated by continual use of repeat runs. The test setup of the various hardware items is described along with an account of test procedures. Test results and data accuracy are discussed. Format of the data presentation is detailed. Complete data are included in the appendix.

  8. Fast electron beam measurements from relativistically intense, frequency-doubled laser-solid interactions

    NASA Astrophysics Data System (ADS)

    Scott, R. H. H.; Pérez, F.; Streeter, M. J. V.; Clark, E. L.; Davies, J. R.; Schlenvoigt, H.-P.; Santos, J. J.; Hulin, S.; Lancaster, K. L.; Dorchies, F.; Fourment, C.; Vauzour, B.; Soloviev, A. A.; Baton, S. D.; Rose, S. J.; Norreys, P. A.

    2013-09-01

    Experimental measurements of the fast electron beam created by the interaction of relativistically intense, frequency-doubled laser light with planar solid targets and its subsequent transport within the target are presented and compared with those of a similar experiment using the laser fundamental frequency. Using frequency-doubled laser light, the fast electron source size is significantly reduced, while evidence suggests the divergence angle may be reduced. Pyrometric measurements of the target rear surface temperature and the Cu Kα imager data indicate the laser to fast electron absorption fraction is reduced using frequency doubled laser light. Bremsstrahlung measurements indicate the fast electron temperature is 125 keV, while the laser energy absorbed into forward-going fast electrons was found to be 16 ± 4% for frequency doubled light at a mean laser intensity of 5 ± 3 × 1018 W cm-2.

  9. Tribological Properties of Laser Microtextured Surface Bonded With Composite Solid Lubricant at High Temperature

    PubMed Central

    Hua, Xijun; Sun, Jianguo; Zhang, Peiyun; Liu, Kai; Wang, Rong; Ji, Jinghu; Fu, Yonghong

    2016-01-01

    A combination technology of the solid lubricant and the laser surface texturing (LST) can significantly improve the tribological properties of friction pairs. The plate sample was textured by fiber laser and composite lubricant of polyimide (PI) and molybdenum disulfide (MoS2) powders were filled in the microdimples. Sliding friction performances of micron-sized composite lubricant and nano-sized composite lubricant were investigated by ring-plate tribometer at temperatures ranging from room temperature (RT) to 400 °C. On the one hand, the results of the micron-sized composite lubricant show that the friction coefficient of the textured surface filled with composite lubricant (TS) exhibits the lowest level and the highest stability compared to a textured surface without solid lubrication, smooth surface without lubrication, smooth surface burnished with a layer of composite solid lubricant. The better dimple density range is 35–46%. The friction coefficients of the sample surface filled with micron-composite solid lubricant with the texture density of 35% are maintained at a low level (about 0.1) at temperatures ranging from RT to 300 °C. On the other hand, the results of the nano-sized composite lubricant show that these friction properties are better than those of MoS2-PI micron-sized composite. The friction coefficients of MoS2-PI-CNTs nano-sized composite solid lubricant are lower than those of the MoS2-PI composite lubricant at temperatures ranging from RT to 400 °C. In addition, the possible mechanisms involving the synergetic effect of the surface texture and the solid lubricant are discussed in the present work. PMID:27303112

  10. Tribological Properties of Laser Microtextured Surface Bonded With Composite Solid Lubricant at High Temperature.

    PubMed

    Hua, Xijun; Sun, Jianguo; Zhang, Peiyun; Liu, Kai; Wang, Rong; Ji, Jinghu; Fu, Yonghong

    2016-07-01

    A combination technology of the solid lubricant and the laser surface texturing (LST) can significantly improve the tribological properties of friction pairs. The plate sample was textured by fiber laser and composite lubricant of polyimide (PI) and molybdenum disulfide (MoS2) powders were filled in the microdimples. Sliding friction performances of micron-sized composite lubricant and nano-sized composite lubricant were investigated by ring-plate tribometer at temperatures ranging from room temperature (RT) to 400 °C. On the one hand, the results of the micron-sized composite lubricant show that the friction coefficient of the textured surface filled with composite lubricant (TS) exhibits the lowest level and the highest stability compared to a textured surface without solid lubrication, smooth surface without lubrication, smooth surface burnished with a layer of composite solid lubricant. The better dimple density range is 35-46%. The friction coefficients of the sample surface filled with micron-composite solid lubricant with the texture density of 35% are maintained at a low level (about 0.1) at temperatures ranging from RT to 300 °C. On the other hand, the results of the nano-sized composite lubricant show that these friction properties are better than those of MoS2-PI micron-sized composite. The friction coefficients of MoS2-PI-CNTs nano-sized composite solid lubricant are lower than those of the MoS2-PI composite lubricant at temperatures ranging from RT to 400 °C. In addition, the possible mechanisms involving the synergetic effect of the surface texture and the solid lubricant are discussed in the present work.

  11. Evaluation of the measurement uncertainty when measuring the resistance of solid isolating materials to tracking

    NASA Astrophysics Data System (ADS)

    Stare, E.; Beges, G.; Drnovsek, J.

    2006-07-01

    This paper presents the results of research into the measurement of the resistance of solid isolating materials to tracking. Two types of tracking were investigated: the proof tracking index (PTI) and the comparative tracking index (CTI). Evaluation of the measurement uncertainty in a case study was performed using a test method in accordance with the IEC 60112 standard. In the scope of the tests performed here, this particular test method was used to ensure the safety of electrical appliances. According to the EN ISO/IEC 17025 standard (EN ISO/IEC 17025), in the process of conformity assessment, the evaluation of the measurement uncertainty of the test method should be carried out. In the present article, possible influential parameters that are in accordance with the third and fourth editions of the standard IEC 60112 are discussed. The differences, ambiguities or lack of guidance referring to both editions of the standard are described in the article 'Ambiguities in technical standards—case study IEC 60112—measuring the resistance of solid isolating materials to tracking' (submitted for publication). Several hundred measurements were taken in the present experiments in order to form the basis for the results and conclusions presented. A specific problem of the test (according to the IEC 60112 standard) is the great variety of influential physical parameters (mechanical, electrical, chemical, etc) that can affect the results. At the end of the present article therefore, there is a histogram containing information on the contributions to the measurement uncertainty.

  12. Solid sulfur in vacuum: Sublimation effects on surface microtexture, color and spectral reflectance, and applications to planetary surfaces

    NASA Technical Reports Server (NTRS)

    Nash, D. B.

    1987-01-01

    A form of sulfur that is white at room temperature and very fluffy in texture has been found in laboratory experiments on the effects of vacuum sublimation (evaporation) on solid sulfur. This work is an outgrowth of proton sputtering experiments on sulfur directed toward understanding Jovian magnetospheric effects on the surface of Io. Fluffy white sulfur is formed on the surface of solid yellow, tan, or brown sulfur melt freezes in vacuum by differential (fractional) evaporation of two or more sulfur molecular species present in the original sulfur; S(8) ring sulfur is thought to be the dominant sublimination phase lost to the vacuum sink, and polymeric chain sulfur S(u) the dominant residual phase that remains in place, forming the residual fluffy surface layer. The reflectance spectrum of the original sulfur surface is greaty modified by formation of the fluffy layer: the blue absorption band-edge and shoulder move 0.05 to 0.06 microns toward shorter wavelengths resulting in a permanent increase in reflectivity near 0.42 to 0.46 microns; the UV reflectivity below 0.40 microns is reduced. This form of sulfur should exist in large quantity on the surface of Io, especially in hotspot regions if there is solid free sulfur there that has solidified from a melt. Its color and spectra will indicate relative crystallization age on a scale of days to months and/or surface temperature distribution history.

  13. Advanced LWIR hyperspectral sensor for on-the-move proximal detection of liquid/solid contaminants on surfaces

    NASA Astrophysics Data System (ADS)

    Giblin, Jay P.; Dixon, John; Dupuis, Julia R.; Cosofret, Bogdan R.; Marinelli, William J.

    2017-05-01

    Sensor technologies capable of detecting low vapor pressure liquid surface contaminants, as well as solids, in a noncontact fashion while on-the-move continues to be an important need for the U.S. Army. In this paper, we discuss the development of a long-wave infrared (LWIR, 8-10.5 μm) spatial heterodyne spectrometer coupled with an LWIR illuminator and an automated detection algorithm for detection of surface contaminants from a moving vehicle. The system is designed to detect surface contaminants by repetitively collecting LWIR reflectance spectra of the ground. Detection and identification of surface contaminants is based on spectral correlation of the measured LWIR ground reflectance spectra with high fidelity library spectra and the system's cumulative binary detection response from the sampled ground. We present the concepts of the detection algorithm through a discussion of the system signal model. In addition, we present reflectance spectra of surfaces contaminated with a liquid CWA simulant, triethyl phosphate (TEP), and a solid simulant, acetaminophen acquired while the sensor was stationary and on-the-move. Surfaces included CARC painted steel, asphalt, concrete, and sand. The data collected was analyzed to determine the probability of detecting 800 μm diameter contaminant particles at a 0.5 g/m2 areal density with the SHSCAD traversing a surface.

  14. Adsorption of the Three-phase Emulsion on Various Solid Surfaces.

    PubMed

    Enomoto, Yasutaka; Imai, Yoko; Tajima, Kazuo

    2017-07-01

    The present study investigates the adsorption of the three-phase emulsion on various solid/water interfaces. Vesicles can be used as emulsifiers in the three-phase emulsions and act as an independent phase unlike the surfactant used in conventional emulsions; therefore, it is expected that the three-phase emulsion formed by the adhesion of vesicles to the oil/water interface will adsorb on various solid/water interfaces. The cationic three-phase emulsion was prepared to encourage emulsion adsorption on negatively charged solid substrates in water. The emulsifier polyoxyethylene-(10) hydrogenated castor oil was rendered cationic by mixing with the surfactant cetyltrimethylammonium bromide and then used to prepare the cationic three-phase emulsion of hexadecane-in-water. Three solid substrates (silicon, glass, and copper) were dipped in the cationic emulsion and the emulsion was found to adsorb on the solid substrates while maintaining its structure. The amount of hexadecane adsorbed on the various surfaces was investigated by gas chromatography and found to increase with increasing hexadecane concentration in the emulsion and eventually plateaued just like molecular adsorption. The maximum surface coverage of the emulsion on the substrates was approximately 80%. However, even the equivalent nonionic three-phase emulsion was found to adsorb on the three solid surfaces. This was attributed to a novel mechanism of irreversible adhesion via the van der Waals attractive force.

  15. In Vivo Airway Surface Liquid Cl− Analysis with Solid-State Electrodes

    PubMed Central

    Caldwell, Ray A.; Grubb, Barbara R.; Tarran, Robert; Boucher, Richard C.; Knowles, Michael R.; Barker, Pierre M.

    2002-01-01

    The pathogenesis of cystic fibrosis (CF) airways disease remains controversial. Hypotheses that link mutations in CFTR and defects in ion transport to CF lung disease predict that alterations in airway surface liquid (ASL) isotonic volume, or ion composition, are critically important. ASL [Cl−] is pivotal in discriminating between these hypotheses, but there is no consensus on this value given the difficulty in measuring [Cl−] in the “thin” ASL (∼30 μm) in vivo. Consequently, a miniaturized solid-state electrode with a shallow depth of immersion was constructed to measure ASL [Cl−] in vivo. In initial experiments, the electrode measured [Cl−] in physiologic salt solutions, small volume (7.6 μl) test solutions, and in in vitro cell culture models, with ≥93% accuracy. Based on discrepancies in reported values and/or absence of data, ASL Cl− measurements were made in the following airway regions and species. First, ASL [Cl−] was measured in normal human nasal cavity and averaged 117.3 ± 11.2 mM (n = 6). Second, ASL [Cl−] measured in large airway (tracheobronchial) regions were as follows: rabbit trachea and bronchus = 114.3 ± 1.8 mM; (n = 6) and 126.9 ± 1.7 mM; (n = 3), respectively; mouse trachea = 112.8 ± 4.2 mM (n = 13); and monkey bronchus = 112.3 ± 10.9 mM (n = 3). Third, Cl− measurements were made in small (1–2 mm) diameter airways of the rabbit (108.3 ± 7.1 mM, n = 5) and monkey (128.5 ± 6.8 mM, n = 3). The measured [Cl−], in excess of 100 mM throughout all airway regions tested in multiple species, is consistent with the isotonic volume hypothesis to describe ASL physiology. PMID:11773234

  16. Contact Angle of Drops Measured on Nontransparent Surfaces and Capillary Flow Visualized

    NASA Technical Reports Server (NTRS)

    Chao, David F.; Zhang, Nengli

    2003-01-01

    The spreading of a liquid on a solid surface is important for various practical processes, and contact-angle measurements provide an elegant method to characterize the interfacial properties of the liquid with the solid substrates. The complex physical processes occurring when a liquid contacts a solid play an important role in determining the performance of chemical processes and materials. Applications for these processes are in printing, coating, gluing, textile dyeing, and adhesives and in the pharmaceutical industry, biomedical research, adhesives, flat panel display manufacturing, surfactant chemistry, and thermal engineering.

  17. Surface response of a fluid-loaded solid to impulsive line and point forces: Application to scanning acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Every, A. G.; Briggs, G. A. D.

    1998-07-01

    Algorithms are presented for calculating the two- and three-dimensional time domain dynamic Green's functions of a pair of joined semi-infinite anisotropic elastic continua. They are used to calculate the normal surface displacement response of fluid-loaded solids to impulsive line and point forces. Particular attention is given to the resonant and singular features in the response associated with the Stoneley-Scholte interfacial wave, leaky Rayleigh and pseudosurface acoustic waves, and lateral waves, i.e., surface skimming bulk waves of the solid and of the liquid. The various regimes are explored, in which the fluid sound speed and acoustic impedance range from small to large as compared to those of the solid. The effects of elastic anisotropy of the solid are illustrated with results for a carbon fiber composite and for the principal crystallographic cuts of a number of cubic crystals of anisotropy coefficient η=2C44/(C11-C12) greater and less than unity. Calculated images, representing the dependence of the normal displacement response on time and direction, are in good agreement with published acoustic microscopy images of a number of anisotropic solids that have been measured with a configuration of two line focus or two point focus lenses. These images display prominent features due to leaky Rayleigh and pseudosurface waves, as well as sharper lateral wave structures. The mode of excitation and detection does not, however, couple into the water lateral wave and Sholte wave, which are absent from the measured images. This effect is simulated by setting a finite cutoff, determined by the aperture angles of the lenses, to the spatial Fourier transform of the surface Green's function.

  18. A kinetic model of adsorption on solid surfaces

    NASA Astrophysics Data System (ADS)

    Aoki, Kazuo; Giovangigli, Vincent; Hattori, Masanari

    2016-11-01

    A kinetic model describing physisorption and chemisorption of gas particles on a crystal surface is introduced. A single kinetic equation is used to model gas and physisorbed particles interacting with an average potential and colliding with phonons. This equation is coupled to a kinetic equation describing localized chemisorbed species. A modified kinetic entropy is introduced for the coupled system and the H theorem is established. Using a fluid scaling and the Chapman-Enskog asymptotic method, fluid boundary conditions for the physisorbed and chemisorbed species are derived from the kinetic model.

  19. A new concept for solid surface deployable antennas

    NASA Astrophysics Data System (ADS)

    Guest, S. D.; Pellegrino, S.

    1996-01-01

    This paper presents a new class of rigid-panel deployable antennas. The antenna surface is divided into a series of panels, which fold by wrapping around a central hub. All connections between the panels are made by revolute joints. This new folding technique has significant advantages over previous concepts, both in terms of packaged size, and mechanical simplicity. Furthermore, the size and shape of the packaged reflector can be readily adapted to any particular set of mission requirements. A small hardware demonstrator, which has been designed, manufactured and successfully tested, is discussed in the paper.

  20. Local Surface Structure From Disparity Measurements

    NASA Astrophysics Data System (ADS)

    Jenkin, Michael R. M.; Jepson, Allan D.; Tsotsos, John K.

    1988-02-01

    Current theories of stereopsis involve three distinct stages: First, the two images of a stereo pair are processed separately to extract monocular features. One common choice of feature is the presence of a zero-crossing in a bandpassed versions of the image. Second, the monocular features in one image are matched with corresponding features found in the other image. In practice this second stage cannot be expected to produce only the correct matches, and a third stage must be considered in order to remove the incorrect matches ("false targets"). There are therefore three main issues the design of such a traditional algorithm for stereopsis, namely i) the choice of image features; the choice of matching criteria; and iii) the way false targets are avoided or eliminated. In this paper we introduce a different approach. We propose that symbolic features should not be extracted from the monocular images in the first stage of processing. Rather we examine a technique for measuring the local phase difference between the two images. We show how local phase difference in a bandpassed version of the image can be interpreted as disparity. This essentially combines the first two stages of the traditional approach. These disparity measurements may contain "false targets" which must be eliminated. Building upon the results of these disparty detectors, we show that a simple surface model based on object cohesiveness and local surface planarity across a range of spatial-frequency tuned channels can be used to reduce false matches. The resulting local planar surface support can be used to segment the image into planar regions in depth. Due to the independent nature of both the disparity detection and local planar support mechanism, this method is capable of dealing with both opaque and transparent stimuli.

  1. Water drop impact onto oil covered solid surfaces

    NASA Astrophysics Data System (ADS)

    Chen, Ningli; Chen, Huanchen; Amirfazli, Alidad

    2016-11-01

    Droplet impact onto an oily surface can be encountered routinely in industrial applications; e.g., in spray cooling. It is not clear from literature what impact an oil film may have on the impact process. In this work, water drop impact onto both hydrophobic (glass) and hydrophilic (OTS) substrates which were covered by oil films (silicone) of different thickness (5um-50um) and viscosity (5cst-100cst) were performed. The effects of drop impact velocity, film thickness, and viscosity of the oil film and wettability of the substrate were studied. Our results show that when the film viscosity and impact velocity is low, the water drop deformed into the usual disk shape after impact, and rebounded from the surface. Such rebound phenomena disappears, when the viscosity of oil becomes very large. With the increase of the impact velocity, crown and splashing appears in the spreading phase. The crown and splashing behavior appears more easily with the increase of film thickness and decrease of its viscosity. It was also found that the substrate wettability can only affect the impact process in cases which drop has a large Webber number (We = 594), and the film's viscosity and thickness are small. This work was support by National Natural Science Foundation of China and the Project Number is 51506084.

  2. Sputter-induced isotopic fractionation at solid surfaces

    SciTech Connect

    Watson, C.C.; Haff, P.K.

    1980-01-01

    Elemental and isotopic mass fractionation in both binary and multicomponent media are investigated within the framework of the familiar collision-cascade model for sputtering. Some of the most salient features of the phenomenon are explicable on this basis. It is found that the partitioning of beam-deposited energy among the various target components can account for differentiations in the secondary recoil fluxes only on the order of one part per thousand, indicating the importance of the surface potentials when large enrichment effects occur. A mechanism governing the translation of internal recoil fluxes into external sputtered fluxes is proposed in order to account for isotopic fractionation, for which the surface binding effects are assumed to be negligible. The predicted initial fractionations are delta/sub f/(/sup 40/Ca : /sup 44/Ca) =33 parts per thousand in the calcium-containing mineral plagioclase and delta/sub f/(/sup 40/Ca : /sup 44/Ca) =24 parts per thousand in CaF/sub 2/, in reasonable agreement with recent data on isotopic fractionation.

  3. Solid He: Progress, Status, and Outlook for Mass Flux Measurements

    NASA Astrophysics Data System (ADS)

    Hallock, R. B.

    2015-07-01

    After a brief introduction, what is provided there is brief summary of work with solid He done at the University of Massachusetts Amherst and an outlook for future work. What is presented here is based on a presentation made at the Quantum Gases Fluids and Solids Workshop in Sao Paulo, Brazil in August of 2014. Our work with solid He is aimed at the question: Can a sample cell filled with solid He support a mass flux through the cell? The answer, as will be shown here, is yes. Evidence for this from several types of experiments will be reviewed. There will be an emphasis on more recent work, work that explores how the flux observed depends on temperature and on the He impurity level. The behavior observed suggests that solid He may be an example of a material that demonstrates Bosonic Luttinger liquid behavior. The normalized He flux has a universal temperature dependence. The presence of He at different impurity levels shows that the He blocks the flux at a characteristic temperature. The behavior appears to be consistent with the cores of dislocations as the entity that carries the flux, but it is clear that more work needs to be done to fully understand solid He.

  4. Fluid dynamics at the interface between contacting elastic solids with randomly rough surfaces.

    PubMed

    Persson, B N J

    2010-07-07

    We study fluid dynamics at the interface between elastic solids with randomly rough surfaces. The contact mechanics model of Persson is used to take into account the elastic interaction between the solid walls, and the Bruggeman effective medium theory to account for the influence of the disorder on the fluid flow. We calculated the flow tensor which determines the pressure flow factor and, for example, the leak rate of static seals. It is shown how the perturbation treatment of Tripp can be extended to arbitrary order in the ratio between the root-mean-square roughness amplitude and the average interfacial surface separation. We introduce a matrix D(ζ), determined by the surface roughness power spectrum, which can be used to describe the anisotropy of the surface at any magnification ζ. Results are presented for the asymmetry factor γ(ζ) (generalized Peklenik number) for grinded steel and sandblasted PMMA surfaces. © 2010 IOP Publishing Ltd

  5. Interfacial fracture between highly crosslinked polymer networks and a solid surface: Effect of interfacial bond density

    SciTech Connect

    STEVENS,MARK J.

    2000-03-23

    For highly crosslinked, polymer networks bonded to a solid surface, the effect of interfacial bond density as well as system size on interfacial fracture is studied molecular dynamics simulations. The correspondence between the stress-strain curve and the sequence of molecular deformations is obtained. The failure strain for a fully bonded surface is equal to the strain necessary to make taut the average minimal path through the network from the bottom solid surface to the top surface. At bond coverages less than full, nanometer scale cavities form at the surface yielding an inhomogeneous strain profile. The failure strain and stress are linearly proportional to the number of bonds at the interface unless the number of bonds is so few that van der Waals interactions dominate. The failure is always interfacial due to fewer bonds at the interface than in the bulk.

  6. Advanced Concepts in Nanotexturing of Solid Surfaces for Composite Applications

    DTIC Science & Technology

    2006-11-01

    an image capture program employing LabView software. Contact angles were measured using HPLC grade water by defining a circle about the drop, and... semiautomatic algorithm for Rutherford backscattering analysis, Nuclear Instruments and Methods in Physics Research Section B, 15, 227-231. Hirai Y

  7. Direct measurement of sub-Debye-length attraction between oppositely charged surfaces.

    PubMed

    Kampf, Nir; Ben-Yaakov, Dan; Andelman, David; Safran, S A; Klein, Jacob

    2009-09-11

    Using a surface force balance with fast video analysis, we have measured directly the attractive forces between oppositely charged solid surfaces (charge densities sigma(+), sigma(-)) across water over the entire range of interaction, in particular, at surface separations D below the Debye screening length lambda(S). At very low salt concentration we find a long-ranged attraction between the surfaces (onset ca. 100 nm), whose variation at Dsurface charge asymmetry (sigma(+) not equal to |sigma(-)|).

  8. Measuring runoff-suspended solids using an improved turbidometer method.

    PubMed

    Ginting, Daniel; Mamo, Martha

    2006-01-01

    Differences in particle size distribution between runoff standards and unknown samples affect the accuracy of estimation of total suspended solids (TSS) concentration using the nephelometric turbidity (NTU) method. The objective was to quantify the effects of a sucrose solution as suspending medium and contrasting particle size distribution on nephelometric turbidity and accuracy of TSS estimation. Nineteen benchmark soils varying in texture and color were divided into particle size distribution of <250 and <2000 microm. Soils from these two aggregate classes were then made into suspension ranging from 0.2 to 15 g L-1 using distilled deionized water. Runoff suspensions ranging from 0.2 to 21 g L-1 were also collected from different watersheds. Turbidity of soil and runoff suspensions was measured in sucrose solution and in distilled deionized water. The sucrose solution density ranged from 1.10 to 1.30 kg L-1. Increasing sucrose solution density decreased turbidity. The TSS concentration was most sensitive to changes in turbidity with the 1.30 kg L-1 sucrose solution. Using the 1.30 kg L-1 sucrose solution, particle size bias and error of TSS estimates were decreased by at least 20% compared to distilled deionized water. Reduction in refraction index differences between the suspended particles and sucrose solution combined with reduced particle settling and reduced Brownian motion resulted in dampening the effects of particle size distribution. We propose a sucrose solution of 1.30 kg L-1 as a better suspending medium to dampen the effect of particle size distribution and thus improve suspension TSS concentration estimation.

  9. Drop Impact of Viscous Suspensions on Solid Surfaces

    NASA Astrophysics Data System (ADS)

    Bolleddula, Daniel; Aliseda, Alberto

    2009-11-01

    Droplet impact is a well studied subject with over a century of progress. Most studies are motivated by applications such as inkjet printing, agriculture spraying, or printed circuit boards. Pharmaceutically relevant fluids provide an experimental set that has received little attention. Medicinal tablets are coated by the impaction of micron sized droplets of aqueous suspensions and subsequently dried for various purposes such as brand recognition, mask unpleasant taste, or functionality. We will present a systematic study of micron sized drop impact of Newtonian and Non-Newtonian fluids used in pharmaceutical coating processes. In our experiments we extend the range of Ohnesorge numbers, O(1), of previous studies on surfaces of varying wettability and roughness.

  10. Frictional dynamics of viscoelastic solids driven on a rough surface.

    PubMed

    Landes, François P; Rosso, Alberto; Jagla, E A

    2015-07-01

    We study the effect of viscoelastic dynamics on the frictional properties of a (mean-field) spring-block system pulled on a rough surface by an external drive. When the drive moves at constant velocity V, two dynamical regimes are observed: at fast driving, above a critical threshold V(c), the system slides at the drive velocity and displays a friction force with velocity weakening. Below V(c) the steady sliding becomes unstable and a stick-slip regime sets in. In the slide-hold-slide driving protocol, a peak of the friction force appears after the hold time and its amplitude increases with the hold duration. These observations are consistent with the frictional force encoded phenomenologically in the rate-and-state equations. Our model gives a microscopical basis for such macroscopic description.

  11. Instrument for elemental composition studies of solids on planetary surfaces with sub-ppm detection sensitivity

    NASA Astrophysics Data System (ADS)

    Tulej, M.; Riedo, A.; Meyer, S.; Iakovleva, M.; Neuland, M.; Wurz, P.

    2012-04-01

    Current space instruments prove to be successful for a global chemical mapping of the entire planetary body or to perform a local chemical analysis, helpful in determination of modal mineralogy. Nevertheless, the sensitivity and low spatial resolution of these spectroscopic instruments limit the chemical analysis to the most abundant elements with some exceptions (e.g., measurements of Th, K, and H elements by Gamma and neutron spectrometers). Furthermore, the spectroscopic analysis typically provides the chemical composition of 1 micrometer of the uppermost surface layers, which are frequently affected by space weathering effects, again, with the exception of Gamma/neutron investigation where the composition of up to 1 m thick subsurface can be measured. New and recently accepted space instruments, such as Laser Induced Breakdown (LIBS) and Laser Ablation/Ionisation Mass Spectrometers (LIMS) are thought to improve these chemical analysis providing more localised chemical sampling with higher sensitivity and accuracy. We will demonstrate the performance of a highly miniaturised laser ablation time of flight mass spectrometer designed for space research for the elemental analysis of solid materials (Rohner et al., 2003). The instrument enables mass spectrometric analysis with sub-ppm detection limits and a typical mass resolution of ~700, sufficient to detect all elements and their isotopes. The studies of NIST standards, minerals and meteoritic samples will be reviewed to emphasize its capability for quantitative analysis and chemical mapping of the inhomogeneous samples with a high spatial (vertical and lateral) resolution. LIMS measurements provide means for investigation of principal elements (metals, non-metals) and allow an analysis of trace elements distributed within a suite of soils and rocks. Thus, LIMS measurements will allow the identification of the mineralogical context of planetary surface and better understanding of the geologic/geochemical structure

  12. Growth behavior of surface cracks in the circumferential plane of solid and hollow cylinders

    NASA Technical Reports Server (NTRS)

    Forman, R. G.; Shivakumar, V.

    1986-01-01

    Experiments were conducted to study the growth behavior of surface fatigue cracks in the circumferential plane of solid and hollow cylinders. In the solid cylinders, the fatigue cracks were found to have a circular arc crack front with specific upper and lower limits to the arc radius. In the hollow cylinders, the fatigue cracks were found to agree accurately with the shape of a transformed semiellipse. A modification to the usual nondimensionalization expression used for surface flaws in flat plates was found to give correct trends for the hollow cylinder problem.

  13. Evaporation of liquid microdroplets levitated above a solid surface heated below the saturation temperature

    NASA Astrophysics Data System (ADS)

    Kirichenko, D. P.; Zaitsev, D. V.; Kabov, O. A.

    2016-10-01

    This paper presents a study of the interaction of liquid microdroplets falling on a solid surface whose temperature is varied from 75 °C to 155 °C. It has been shown for the first time that droplet levitation above a solid surface is possible at a temperature below the saturation temperature. It has been found that for levitated droplets, the specific evaporation rate is constant in time, but for sessile droplets, it increases sharply. The evaporation rate for sessile droplet was found an order of magnitude higher than that for levitated droplets.

  14. A new method for the measurement of solids holdup in gas-liquid-solid three-phase systems

    SciTech Connect

    Wenge, F.; Chisti, Y.; Moo-Young, M.

    1995-03-01

    Gas-liquid-solid multiphase systems are commonly encountered in the chemical process industry, in bio-processing, and in environmental pollution abatement devices. A method for the measurement of gas and solids holdups in gas-liquid-solid multiphase devices is developed and tested. The method depends on measurements of hydrostatic pressures in the three-phase dispersion followed by interruption of gas flow, complete gas disengagement, and a second pressure measurement in the resulting two-phase solid-liquid slurry, over a short period of time (< 30 s). The proposed method is compared with results obtained with physical sampling of the multiphase flow in vertical up- and down-flow in a large airlift reactor (0.243 m diameter, 7.825 m overall height, 2.44 riser-to-downcomer cross-sectional area ratio). Applicability of the technique to slurries of glass beads in tap water is demonstrated for various sizes and concentrations of beads over a range of gas flow rates (0.070--0.150 {times} 10{sup {minus}3} m bead diameter, 2,500 kg/m{sup 3} solids density, 0.02--0.17 m/s superficial gas velocity).

  15. Nanoparticle self-structuring in a nanofluid film spreading on a solid surface.

    PubMed

    Nikolov, Alex; Kondiparty, Kirti; Wasan, Darsh

    2010-06-01

    Liquids containing nanoparticles (nanofluids) exhibit different spreading or thinning behaviors on solids than liquids without nanoparticles. Previous experiments and theoretical investigations have demonstrated that the spreading of nanofluids on solid surfaces is enhanced compared to the spreading of base fluids without nanoparticles. However, the mechanisms for the observed enhancement in the spreading of nanofluids on solid substrates are not well understood. The complex nature of the interactions between the particles in the nanofluid and with the solid substrate alters the spreading dynamics [Wasan, D. T.; Nikolov, A. D. Nature 2003, 423, 156]. Here, we report, for the first time, the results of an experimental observation of nanoparticles self-structuring in a nanofluid film formed between an oil drop and a solid surface. Using a silica-nanoparticle aqueous suspension (with a nominal diameter of 19 nm and 10 vol %) and reflected light interferometry, we show the nanoparticle layering (i.e., stratification) phenomenon during film thinning on a smooth hydrophilic glass surface. Our experiments revealed that the film thickness stability on a solid substrate depends on the film size (i.e., the drop size). A film formed from a small drop (with a high capillary pressure) is thicker and contains more particle layers than a film formed from a large drop (with a lower capillary pressure). The data for the film-meniscus contact angle verses film thickness (corresponding to the different number of particle layers) were obtained and used to calculate the film structural energy isotherm. These results may provide a better understanding of the complex phenomena involved in the enhanced spreading of nanofluids on solid surfaces.

  16. [Combustion temperature measurement of solid propellant and the effect of organic compound on combustion temperature].

    PubMed

    Zhou, Xue-tie; Li, Yan; Chen, Zuo-ru; Wang, Jun-de

    2003-06-01

    The FTIR emission spectra in the spectral range of 4,500-300 cm-1 for the solid propellants were measured by a remote sensing FTIR system. The P-branch of fine structure of HCl fundamental band lying at 3.46 microns was used for precise combustion temperature measurement of the solid propellant. The effect of the organic compound in the solid propellant on the combustion temperature was discussed.

  17. Quadrotor helicopter for surface hydrological measurements

    NASA Astrophysics Data System (ADS)

    Pagano, C.; Tauro, F.; Porfiri, M.; Grimaldi, S.

    2013-12-01

    Surface hydrological measurements are typically performed through user-assisted and intrusive field methodologies which can be inadequate to monitor remote and extended areas. In this poster, we present the design and development of a quadrotor helicopter equipped with digital acquisition system and image calibration units for surface flow measurements. This custom-built aerial vehicle is engineered to be lightweight, low-cost, highly customizable, and stable to guarantee optimal image quality. Quadricopter stability guarantees minimal vibrations during image acquisition and, therefore, improved accuracy in flow velocity estimation through large scale particle image velocimetry algorithms or particle tracking procedures. Stability during the vehicle pitching and rolling is achieved by adopting large arm span and high-wing configurations. Further, the vehicle framework is composed of lightweight aluminum and durable carbon fiber for optimal resilience. The open source Ardupilot microcontroller is used for remote control of the quadricopter. The microcontroller includes an inertial measurement unit (IMU) equipped with accelerometers and gyroscopes for stable flight through feedback control. The vehicle is powered by a 3 cell (11.1V) 3000 mAh Lithium-polymer battery. Electronic equipment and wiring are hosted into the hollow arms and on several carbon fiber platforms in the waterproof fuselage. Four 35A high-torque motors are supported at the far end of each arm with 10 × 4.7 inch propellers. Energy dissipation during landing is accomplished by four pivoting legs that, through the use of shock absorbers, prevent the impact energy from affecting the frame thus causing significant damage. The data capturing system consists of a GoPro Hero3 camera and in-house built camera gimbal and shock absorber damping device. The camera gimbal, hosted below the vehicle fuselage, is engineered to maintain the orthogonality of the camera axis with respect to the water surface by

  18. Coalescence of sessile microdroplets subject to a wettability gradient on a solid surface

    NASA Astrophysics Data System (ADS)

    Ahmadlouydarab, Majid; Lan, Chuanjin; Das, Arup Kumar; Ma, Yanbao

    2016-09-01

    While there are intensive studies on the coalescence of sessile macroscale droplets, there is little study on the coalescence of sessile microdroplets. In this paper, the coalescence process of two sessile microdroplets is studied by using a many-body dissipative particle dynamics numerical method. A comprehensive parametric study is conducted to investigate the effects on the coalescence process from the wettability gradient, hydrophilicity of the solid surface, and symmetric or asymmetric configurations. A water bridge is formed after two microdroplets contact. The temporal evolution of the coalescence process is characterized by the water bridge's radii parallel to the solid surface (Wm) and perpendicular to the solid surface (Hm). It is found that the changes of both Hm and Wm with time follow a power law; i.e., Hm=β1τβ and Wm=α1τα . The growth of Hm and Wm depends on the hydrophilicity of the substrate. Wm grows faster than Hm on a hydrophilic surface, and Hm grows faster than Wm on a hydrophobic surface. This is due to the strong competition between capillary forces induced by the water-bridge curvature and the solid substrate hydrophobicity. Also, flow structure analysis shows that regardless of the coalescence type once the liquid bridge is formed the liquid flow direction inside the capillary bridge is to expand the bridge radius. Finally, we do not observe oscillation of the merged droplet during the coalescence process, possibly due to the significant effects of the viscous forces.

  19. Influence of Geometry on a High Surface Area-Solid Phase Microextraction Sampler for Chemical Vapor Collection

    DTIC Science & Technology

    2007-06-04

    Title of Thesis: Influence of Geometry on a High Surface Area-Solid Phase Microextraction Sampler for Chemical Vapor Collection Name of...TITLE AND SUBTITLE Influence of Geometry on a High Surface Area-Solid Phase Microextraction Sampler for Chemical Vapor Collection 5a. CONTRACT...SUPPLEMENTARY NOTES 14. ABSTRACT The High Surface Area Solid Phase Microextraction (HSA-SPME) device is an internally heated sampling device designed for

  20. Surface functionalization of solid state ultra-high molecular weight polyethylene through chemical grafting

    NASA Astrophysics Data System (ADS)

    Sherazi, Tauqir A.; Rehman, Tayyiba; Naqvi, Syed Ali Raza; Shaikh, Ahson Jabbar; Shahzad, Sohail Anjum; Abbas, Ghazanfar; Raza, Rizwan; Waseem, Amir

    2015-12-01

    The surface of ultra-high molecular weight polyethylene (UHMWPE) powder was functionalized with styrene using chemical grafting technique. The grafting process was initiated through radical generation on base polymer matrix in the solid state by sodium thiosulfate, while peroxides formed at radical sites during this process were dissociated by ceric ammonium nitrate. Various factors were optimized and reasonably high level of monomer grafting was achieved, i.e., 15.6%. The effect of different acids as additive and divinyl benzene (DVB) as a cross-linking agent was also studied. Post-grafting sulfonation was conducted to introduce the ionic moieties to the grafted polymer. Ion-exchange capacity (IEC) was measured experimentally and is found to be 1.04 meq g-1, which is in close agreement with the theoretical IEC values. The chemical structure of grafted and functionalized polymer was characterized by attenuated total reflection infrared spectroscopy (ATR-FTIR) and thermal properties were investigated by thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Thermal analysis depicts that the presence of radicals on the polymer chain accelerates the thermal decomposition process. The results signify that the chemical grafting is an effective tool for substantial surface modification and subsequent functionalization of polyethylene.

  1. Description of Different Solid Adsorbent Surfaces Adsorption Mechanisms Based on a Sequential Decomposition of Isotherms

    NASA Astrophysics Data System (ADS)

    Humpola, Pablo D.; Odetti, Hector S.; Flores, Ethel S. E.; Vicente, Jose Luis

    2013-06-01

    In order to analyze the adsorption capacities of different solid substrates, we present a multi-step method to separately study the isotherm at different pressure ranges (steps). The method is based on simple gas isotherm measurements (nitrogen, methane, carbon dioxide, argon, and oxygen) and is tested to describe the adsorption process and characterize a graphitized surface (GCB) and two different granular activated carbons (GAC). The GCB isotherms are described as a sum of Fowler-Guggenheim-Langmuir shifted curves; isotherm behaviors are quite similar at different temperatures, but change below a certain threshold. In GAC the first steps show the same adsorption characteristics at low pressures (Dubinin's description), but this behavior changes at higher pressure regimes, which allows one to elucidate how heterogeneous the surfaces are or how strong the interactions between adsorbed molecules are for this marginal adsorption to occur. We tested different approaches (from BET multilayer to Aranovich) and found quite different features. We finally conclude that if the description of the adsorption on complex substrates, such as those presented here, is carried using only one model, e. g. Dubinin in case of GACs, the resulting characteristics of the adsorbent would be very biased.

  2. Line Tension of Twist-Free Carbon Nanotube Lyotropic Liquid Crystal Microdroplets on Solid Surfaces.

    PubMed

    Jamali, Vida; Biggers, Evan G; van der Schoot, Paul; Pasquali, Matteo

    2017-09-12

    Line tension, i.e., the force on a three-phase contact line, has been a subject of extensive research due to its impact on technological applications including nanolithography and nanofluidics. However, there is no consensus on the sign and magnitude of the line tension, mainly because it only affects the shape of small droplets, below the length scale dictated by the ratio of line tension to surface tension σ/τ. This ratio is related to the size of constitutive molecules in the system, which translates to a nanometer for conventional fluids. Here, we show that this ratio is orders of magnitude larger in lyotropic liquid crystal systems comprising micrometer-long colloidal particles. Such systems are known to form spindle-shaped elongated liquid crystal droplets in coexistence with the isotropic phase, with the droplets flattening when in contact with flat solid surfaces. We propose a method to characterize the line tension by fitting measured droplet shape to a macroscopic theoretical model that incorporates interfacial forces and elastic deformation of the nematic phase. By applying this method to hundreds of droplets of carbon nanotubes dissolved in chlorosulfonic acid, we find that σ/τ ∼ -0.84 ± 0.06 μm. This ratio is 2 orders of magnitude larger than what has been reported for conventional fluids, in agreement with theoretical scaling arguments.

  3. Chemical interactions of polycyclic organic compounds with coal fly ash and related solid surfaces

    SciTech Connect

    Mamantov, G.; Wehry, E.L.

    1990-03-01

    The interactions of polycyclic aromatic hydrocarbons (PAHs) with particulate surfaces (especially those of coal fly ash) have been investigated, and the influence of coal ash surface properties on the photochemical transformation of adsorbed PAHs has been studied. The overall objective of the work has been to characterize the effects of adsorption onto atmospheric particulate matter on the chemical behavior of PAHs released into the atmosphere via combustion processes. Progress is reported in the following areas of effort: (a) Major emphasis has been devoted to the interactions of PAHs with the different particulate phases that are found in heterogeneous coal ash samples. Techniques have been developed and thoroughly characterized for the fractionation of coal ashes into carbonaceous, mineral-magnetic, and mineral-nonmagnetic subfractions. Heats of adsorption for pyrene on such subfractions have been measured by gas-solid chromatography, and the photoreactivity of pyrene and benz[a]anthracene on ash subfractions has been examined. Carbonaceous particles exhibit the highest affinity for vapor-phase PAHS; mineral magnetic particles usually exhibit the smallest tendency to sorb PAHs from the vapor phase. Adsorption of PAHs on carbonaceous particles suppresses, virtually completely, their tendency to undergo photochemical transformation. For coal ashes that contain few carbonaceous particles, the adsorption and photochemical transformation of PAHs tend to be dominated by the mineral nonmagnetic particles; PAHs adsorbed on these particles tend to exhibit relatively efficient phototransformation.

  4. Measurements of an expanding surface flashover plasma

    SciTech Connect

    Harris, J. R.

    2014-05-21

    A better understanding of vacuum surface flashover and the plasma produced by it is of importance for electron and ion sources, as well as advanced accelerators and other vacuum electronic devices. This article describes time-of-flight and biased-probe measurements made on the expanding plasma generated from a vacuum surface flashover discharge. The plasma expanded at velocities of 1.2–6.5 cm/μs, and had typical densities of 10{sup 10}–10{sup 12} cm{sup −3}. The expansion velocity of the plasma leading edge often exhibited a sharp increase at distances of about 50 mm from the discharge site. Comparison with biased-probe data suggests that, under most conditions, the plasma leading edge was dominated by negative ions, with the apparent increase in velocity being due to fast H{sup −} overtaking slower, heavier ions. In some cases, biased-probe data also showed abrupt discontinuities in the plasma energy distribution co-located with large changes in the intercepted plasma current, suggesting the presence of a shock in the leading edge of the expanding plasma.

  5. Global trends of measured surface air temperature

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lebedeff, Sergej

    1987-01-01

    The paper presents the results of surface air temperature measurements from available meteorological stations for the period of 1880-1985. It is shown that the network of meteorological stations is sufficient to yield reliable long-term, decadal, and interannual temperature changes for both the Northern Hemisphere and the Southern Hemisphere, despite the fact that most stations are located on the continents. The results indicate a global warming of about 0.5-0.7 C in the past century, with warming of similar magnitude in both hemispheres. A strong warming trend between 1965 and 1980 raised the global mean temperature in 1980 and 1981 to the highest level in the period of instrumental records. Selected graphs of the temperature change in each of the eight latitude zones are included.

  6. Global trends of measured surface air temperature

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lebedeff, Sergej

    1987-01-01

    The paper presents the results of surface air temperature measurements from available meteorological stations for the period of 1880-1985. It is shown that the network of meteorological stations is sufficient to yield reliable long-term, decadal, and interannual temperature changes for both the Northern Hemisphere and the Southern Hemisphere, despite the fact that most stations are located on the continents. The results indicate a global warming of about 0.5-0.7 C in the past century, with warming of similar magnitude in both hemispheres. A strong warming trend between 1965 and 1980 raised the global mean temperature in 1980 and 1981 to the highest level in the period of instrumental records. Selected graphs of the temperature change in each of the eight latitude zones are included.

  7. Measurement of Nonlinear Receptivity to Surface Irregularities

    NASA Technical Reports Server (NTRS)

    Davila-Acaron, Jose B.; Hajj, Muhammad R.

    1998-01-01

    Acoustic receptivity is the process by which acoustic disturbances are internalized into the shear layer to generate instability waves. Experiments have shown that, when tuned to the eigenvalue modes, the amplitude of the resulting T-S waves scales with the acoustic field intensity. When a surface irregularity is present, the characteristic wall wavenumber forces a spatial mode onto the near-wall mean velocity field, thus providing modal length scales comparable to those of T-S waves. In this experiment an attempt was made to increase the acoustic receptivity by exciting a difference mode via a quadratic interaction between two larger-wavenumber, forced modes. The difference mode is tuned to the dominant T-S eigenmode wavenumber. As expected, an increased receptivity corresponding to the difference mode was measured downstream of branch I, suggesting the presence of the nonlinearity.

  8. Online Condition Measurement of High Power Solid State Laser Cutting Optics using Ultrasound Signals

    NASA Astrophysics Data System (ADS)

    Neumeier, Benedikt; Schmitt-Landsiedel, Doris

    The occurrence of thermally induced focal shifts in high power solid state laser cutting applications has been reported. A fraction of laser light is absorbed in transmissive optical elements and at optical surface contaminations, leading to a temperature rise of the optical elements. The object of this study is experimental identification of temperature changes in laser cutting head optics during processing, and development of a novel method utilizing ultrasound to measure the bulk temperature online for every optical element in the cutting head. A thermal model is provided for each optical element and allows to estimate the absorbed laser power, the condition and focal shift of the optics. The novel method is compared to existing techniques using thermopiles as temperature sensors. Our measurement system facilitates a closed loop focal shift compensation control and enables a fast reacting emergency shutdown when the temperature of an optical element reaches a damage threshold.

  9. Quantitative measurement of in-plane acoustic field components using surface-mounted fiber sensors

    NASA Technical Reports Server (NTRS)

    Claus, Richard O.; Dhawan, Rajat R.; Gunther, Michael F.; Murphy, Kent A.

    1993-01-01

    Extrinsic Fabry-Perot interferometric sensors have been used to obtain calibrated, quantitative measurements of the in-plane displacement components associated with the propagation of ultrasonic elastic stress waves on the surfaces of solids. The frequency response of the sensor is determined by the internal spacing between the two reflecting fiber endface surfaces which form the Fabry-Perot cavity, a distance which is easily controlled during fabrication. With knowledge of the material properties of the solid, the out-of-plane displacement component of the wave may also be determined, giving full field data.

  10. Acoustically Induced Microparticle Orbiting and Clustering on a Solid Surface

    NASA Astrophysics Data System (ADS)

    Abdel-Fattah, A.; Tarimala, S.; Roberts, P. M.

    2008-12-01

    Behavior of colloidal particles in the bulk solution or at interfaces under the effect of high-frequency acoustics is critical to many seemingly different applications ranging from enhanced oil recovery to improved mixing in microfluidic channels and from accelerated contaminant extractions to surface cleaning, drug delivery and microelectronics. It can be detrimental or beneficial, depending on the application. In medical research, flow cytometry and microfluidics, for example, acoustically induced clustering of tracer particles and/or their sticking to the walls of channels, vessels, or tubes often becomes a problem. On the other hand, it can be tailored to enhance processes such as mixing in microfluidic devices, particle separation and sizing, and power generation microdevices. To better understand the underlying mechanisms, microscopic visualization experiments were performed in which polystyrene fluorescent (468/508 nm wavelength) microspheres with a mean diameter of 2.26-µm and density of 1.05 g/cm3, were suspended in either de-ionized water or a 0.1M NaCl solution. The freshly-prepared colloidal suspension was injected into a parallel-plate glass flow cell, which was subjected to high-frequency acoustics (200-500 kHz) through a piezoelectric transducer attached to one of the cell's outer walls. When the suspending medium is de-ionized water, acoustic stimulation of the cell at 313 kHz induced three distinct particle behaviors: 1) entrainment and bulk transport via wavelength-scale Rayleigh streaming, 2) transport via direct radiation forces to concentrate at nodal or anti-nodal planes, and 3) entrapment via boundary layer vorticular microstreaming resulting in mobile particles orbiting deposited particles. This latter phenomenon is intriguing. It occurs at specific frequencies and the shape of the orbits is determined by the applied frequency, whereas the rotation speed is proportional to the applied amplitude. At the higher ionic strength, on the other

  11. Surface passivation for tight-binding calculations of covalent solids

    NASA Astrophysics Data System (ADS)

    Bernstein, N.

    2007-07-01

    Simulation of a cluster representing a finite portion of a larger covalently bonded system requires the passivation of the cluster surface. We compute the effects of an explicit hybrid orbital passivation (EHOP) on the atomic structure in a model bulk, three-dimensional, narrow gap semiconductor, which is very different from the wide gap, quasi-one-dimensional organic molecules where most passivation schemes have been studied in detail. The EHOP approach is directly applicable to minimal atomic orbital basis methods such as tight-binding. Each broken bond is passivated by a hybrid created from an explicitly expressed linear combination of basis orbitals, chosen to represent the contribution of the missing neighbour, e.g. a sp3 hybrid for a single bond. The method is tested by computing the forces on atoms near a point defect as a function of cluster geometry. We show that, compared to alternatives such as pseudo-hydrogen passivation, the force on an atom converges to the correct bulk limit more quickly as a function of cluster radius, and that the force is more stable with respect to perturbations in the position of the cluster centre. The EHOP method also obviates the need for parameterizing the interactions between the system atoms and the passivating atoms. The method is useful for cluster calculations of non-periodic defects in large systems and for hybrid schemes that simulate large systems by treating finite regions with a quantum-mechanical model, coupled to an interatomic potential description of the rest of the system.

  12. 40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Procedure and method detection limit... method detection limit for measurement of settleable solids. For the purposes of this part, the following... CFR part 136, the method detection limit for measuring settleable solids under this part shall be 0.4...

  13. 40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 31 2013-07-01 2013-07-01 false Procedure and method detection limit... Procedure and method detection limit for measurement of settleable solids. For the purposes of this part.... Notwithstanding any provision of 40 CFR part 136, the method detection limit for measuring settleable solids under...

  14. 40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 30 2014-07-01 2014-07-01 false Procedure and method detection limit... Procedure and method detection limit for measurement of settleable solids. For the purposes of this part.... Notwithstanding any provision of 40 CFR part 136, the method detection limit for measuring settleable solids under...

  15. 40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Procedure and method detection limit... method detection limit for measurement of settleable solids. For the purposes of this part, the following... CFR part 136, the method detection limit for measuring settleable solids under this part shall be 0.4...

  16. 40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Procedure and method detection limit... Procedure and method detection limit for measurement of settleable solids. For the purposes of this part.... Notwithstanding any provision of 40 CFR part 136, the method detection limit for measuring settleable solids under...

  17. Surface chemistry of group 11 atomic layer deposition precursors on silica using solid-state nuclear magnetic resonance spectroscopy.

    PubMed

    Pallister, Peter J; Barry, Seán T

    2017-02-07

    The use of chemical vapour deposition (CVD) and atomic layer deposition (ALD) as thin film deposition techniques has had a major impact on a number of fields. The deposition of pure, uniform, conformal thin films requires very specific vapour-solid reactivity that is largely unknown for the majority of ALD and CVD precursors. This work examines the initial chemisorption of several thin film vapour deposition precursors on high surface area silica (HSAS) using (13)C, (31)P, and quantitative (29)Si nuclear magnetic resonance spectroscopy (NMR). Two copper metal precursors, 1,3-diisopropyl-imidazolin-2-ylidene copper (I) hexamethyldisilazide (1) and 1,3-diethyl-imidazolin-2-ylidene copper(I) hexamethyldisilazide (2), and one gold metal precursor, trimethylphosphine gold(III) trimethyl (3), are examined. Compounds 1 and 2 were found to chemisorb at the hydroxyl surface-reactive sites to form a ||-O-Cu-NHC surface species and fully methylated silicon (||-SiMe3, due to reactivity of the hexamethyldisilazane (HMDS) ligand on the precursor) at 150 °C and 250 °C. From quantitative (29)Si solid-state NMR (SS-NMR) spectroscopy measurements, it was found that HMDS preferentially reacts at geminal disilanol surface sites while the copper surface species preferentially chemisorbed to lone silanol surface species. Additionally, the overall coverage was strongly dependent on temperature, with higher overall coverage of 1 at higher temperature but lower overall coverage of 2 at higher temperature. The chemisorption of 3 was found to produce a number of interesting surface species on HSAS. Gold(III) trimethylphosphine, reduced gold phosphine, methylated phosphoxides, and graphitic carbon were all observed as surface species. The overall coverage of 3 on HSAS was only about 10% at 100 °C and, like the copper compounds, had a preference for lone silanol surface reactive sites. The overall coverage and chemisorbed surface species have implications to the overall growth rate and

  18. Surface chemistry of group 11 atomic layer deposition precursors on silica using solid-state nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Pallister, Peter J.; Barry, Seán T.

    2017-02-01

    The use of chemical vapour deposition (CVD) and atomic layer deposition (ALD) as thin film deposition techniques has had a major impact on a number of fields. The deposition of pure, uniform, conformal thin films requires very specific vapour-solid reactivity that is largely unknown for the majority of ALD and CVD precursors. This work examines the initial chemisorption of several thin film vapour deposition precursors on high surface area silica (HSAS) using 13C, 31P, and quantitative 29Si nuclear magnetic resonance spectroscopy (NMR). Two copper metal precursors, 1,3-diisopropyl-imidazolin-2-ylidene copper (I) hexamethyldisilazide (1) and 1,3-diethyl-imidazolin-2-ylidene copper(I) hexamethyldisilazide (2), and one gold metal precursor, trimethylphosphine gold(III) trimethyl (3), are examined. Compounds 1 and 2 were found to chemisorb at the hydroxyl surface-reactive sites to form a ||-O-Cu-NHC surface species and fully methylated silicon (||-SiMe3, due to reactivity of the hexamethyldisilazane (HMDS) ligand on the precursor) at 150 °C and 250 °C. From quantitative 29Si solid-state NMR (SS-NMR) spectroscopy measurements, it was found that HMDS preferentially reacts at geminal disilanol surface sites while the copper surface species preferentially chemisorbed to lone silanol surface species. Additionally, the overall coverage was strongly dependent on temperature, with higher overall coverage of 1 at higher temperature but lower overall coverage of 2 at higher temperature. The chemisorption of 3 was found to produce a number of interesting surface species on HSAS. Gold(III) trimethylphosphine, reduced gold phosphine, methylated phosphoxides, and graphitic carbon were all observed as surface species. The overall coverage of 3 on HSAS was only about 10% at 100 °C and, like the copper compounds, had a preference for lone silanol surface reactive sites. The overall coverage and chemisorbed surface species have implications to the overall growth rate and purity of

  19. Surfactant molecules to promote removal of cadmium ions from solid surfaces: A complementary experimental-simulational study

    NASA Astrophysics Data System (ADS)

    Pacheco-Blas, María del Alba; Dominguez, Hector; Rivera, Margarita

    2017-03-01

    Sodium dodecyl sulfate (SDS) was used to interact with metallic ions to demonstrate the efficiency of surfactant molecules to promote desorption of metals from solid surfaces. Scanning electron and atomic force microscopy were employed to study desorption of cadmium ions from highly oriented pyrolytic graphite (HOPG), as a model to understand the removal of metallic ions from carbon substrates. Contact angle measurements were carried out to investigate the wettability behavior of the surfactant on the contaminated surface. The desorption mechanism from a microscopic level was studied by using molecular dynamic simulations. Density profiles and pair correlation functions were analyzed to determine the cadmium-surface interaction in the presence of surfactant molecules to improve ion detachment. Simulations showed that surfactant molecules moved in between the adsorbed cadmium ions and the graphite surface pushing up the metallic groups to improve metal desorption. The experimental and theoretical results agree with atomic absorption spectroscopy results.

  20. Analysis of amorphous solid dispersions using 2D solid-state NMR and (1)H T(1) relaxation measurements.

    PubMed

    Pham, Tran N; Watson, Simon A; Edwards, Andrew J; Chavda, Manisha; Clawson, Jacalyn S; Strohmeier, Mark; Vogt, Frederick G

    2010-10-04

    Solid-state NMR (SSNMR) can provide detailed structural information about amorphous solid dispersions of pharmaceutical small molecules. In this study, the ability of SSNMR experiments based on dipolar correlation, spin diffusion, and relaxation measurements to characterize the structure of solid dispersions is explored. Observation of spin diffusion effects using the 2D (1)H-(13)C cross-polarization heteronuclear correlation (CP-HETCOR) experiment is shown to be a useful probe of association between the amorphous drug and polymer that is capable of directly proving glass solution formation. Dispersions of acetaminophen and indomethacin in different polymers are examined using this approach, as well as (1)H double-quantum correlation experiments to probe additional structural features. (1)H-(19)F CP-HETCOR serves a similar role for fluorinated drug molecules such as diflunisal in dispersions, providing a rapid means to prove the formation of a glass solution. Phase separation is detected using (13)C, (19)F, and (23)Na-detected (1)H T(1) experiments in crystalline and amorphous solid dispersions that contain small domains. (1)H T(1) measurements of amorphous nanosuspensions of trehalose and dextran illustrate the ability of SSNMR to detect domain size effects in dispersions that are not glass solutions via spin diffusion effects. Two previously unreported amorphous solid dispersions involving up to three components and containing voriconazole and telithromycin are analyzed using these experiments to demonstrate the general applicability of the approach.