Science.gov

Sample records for direct contact boiling

  1. Experimental investigation of direct contact three phase boiling heat transfer

    SciTech Connect

    Bruce, W.D.

    1981-01-01

    The system which was studied in the present work consisted of one liquid undergoing vaporization by contact with a hotter immiscible liquid. The liquids and vapor were contacted in a counterflow spray column with only differential increases in vapor quality. Experiments yielded vertical temperature profiles, flow rates of the phases, liquid holdups, pressure drops, and a characterization of flow patterns. A micro-computer was utilized for measuring temperatures in the column at the rate of 1500 to 1600 times per second at several depths. Analysis of the experimental data indicate that the maximum temperature difference between the phases is 0.5F/sup 0/, and that a temperature crossover occurs at the lower end of the column. The heat transfer fluid undergoes flash vaporization at its inlet at the top of the column, and much of its sensible heat is tranferred to the dispersed phase near the top of the column. Temperature profiles along the length of the boiler are nearly flat, and very little heat transfer occurs in the lower part of the boiler. A chemical method was developed for measuring effective interfacial area in a direct contact boiler. The theoretical basis of the method is discussed, and physico-chemical data necessary for application of the technique are reported. Water solubility of methyl salicylate was measured as a function of temperature, and the second order reaction rate coefficient for saponification of methyl salicylate by sodium hydroxide was determined from sodium hydroxide concentration versus time data and a computer model of a well-mixed semibatch reactor. The activation energy for the reaction was found to be 9.58 kilocalories per gram mole.

  2. Pool boiling enhancement through contact line augmentation

    NASA Astrophysics Data System (ADS)

    Raghupathi, P. A.; Kandlikar, S. G.

    2017-05-01

    In addition to transient conduction, microconvection, and microlayer evaporation, contact line region heat transfer has been identified as an important mode of heat transfer during boiling. In this work, we demonstrate that generating additional contact line regions within the base of a nucleating bubble leads to critical heat flux (CHF) enhancement. The creation of a liquid meniscus adjacent to 10-20 μm deep microgrooves in the bubble base area was responsible for the generation of the additional contact line regions. The depth of the microgrooves was determined such that a sufficient reservoir of liquid is present in the meniscus to sustain evaporation in the contact line region throughout the bubble cycle. The effective contact line length at the base of the bubble was seen to be a good indicator of the CHF (wetted area) over the surface. The microgroove geometry played a significant role in influencing the bubble dynamics and bubble departure diameter during boiling. It was seen that the bubbles were able to bridge and grow over the shallow microgrooves of 10-20 μm depth and generate additional contact line regions but were pinned and constrained within the grooves in the case of the microgrooves deeper than 100 μm. For shallow grooves, narrow grooves resulted in smaller bubbles, which in turn reduced the contact line length. The findings of this work could be used to design heat transfer surfaces that significantly enhance the contact line region contribution and CHF by placing shallow enhancement features on the surface of the heater.

  3. Conversion of direct process high-boiling residue to monosilanes

    DOEpatents

    Brinson, Jonathan Ashley; Crum, Bruce Robert; Jarvis, Jr., Robert Frank

    2000-01-01

    A process for the production of monosilanes from the high-boiling residue resulting from the reaction of hydrogen chloride with silicon metalloid in a process typically referred to as the "direct process." The process comprises contacting a high-boiling residue resulting from the reaction of hydrogen chloride and silicon metalloid, with hydrogen gas in the presence of a catalytic amount of aluminum trichloride effective in promoting conversion of the high-boiling residue to monosilanes. The present process results in conversion of the high-boiling residue to monosilanes. At least a portion of the aluminum trichloride catalyst required for conduct of the process may be formed in situ during conduct of the direct process and isolation of the high-boiling residue.

  4. Boils

    MedlinePlus

    ... the boil is very bad or comes back. Antibacterial soaps and creams cannot help much once a boil ... following may help prevent the spread of infection: Antibacterial soaps Antiseptic (germ-killing) washes Keeping clean (such as ...

  5. Liquid-solid contact during flow film boiling of subcooled freon-11

    SciTech Connect

    Chang, K.H.; Witte, L.C. )

    1990-05-01

    Liquid-solid contacts were measured for flow film boiling of subcooled Freon-11 over an electrically heated cylinder equipped with a surface microthermocouple probe. No systematic variation of the extent of liquid-solid contact with wall superheat, liquid subcooling, or velocity was detected. Only random small-scale contacts that contribute negligibly to overall heat transfer were detected when the surface was above the homogenous nucleation temperature of the Freon-11. When large-scale contacts were detected, they led to an unexpected intermediate transition from local film boiling to local transition boiling. An explanation is proposed for these unexpected transitions. A comparison of analytical results that used experimentally determined liquid-solid contact parameters to experimental heat fluxes did not show good agreement. It was concluded that the available model for heat transfer accounting for liquid-solid contact is not adequate for flow film boiling.

  6. Boils

    MedlinePlus

    ... or recurrent boils, which are usually due to Staph infections. The bacteria are picked up somewhere and then ... version of boils is folliculitis . This is an infection of hair follicles, usually with Staph bacteria. These often itch more than hurt. The ...

  7. DIRECT-CYCLE, BOILING-WATER NUCLEAR REACTOR

    DOEpatents

    Harrer, J.M.; Fromm, L.W. Jr.; Kolba, V.M.

    1962-08-14

    A direct-cycle boiling-water nuclear reactor is described that employs a closed vessel and a plurality of fuel assemblies, each comprising an outer tube closed at its lower end, an inner tube, fuel rods in the space between the tubes and within the inner tube. A body of water lying within the pressure vessel and outside the fuel assemblies is converted to saturated steam, which enters each fuel assembly at the top and is converted to superheated steam in the fuel assembly while it is passing therethrough first downward through the space between the inner and outer tubes of the fuel assembly and then upward through the inner tube. (AEC)

  8. Thermal singularity and contact line motion in pool boiling: Effects of substrate wettability.

    PubMed

    Taylor, M T; Qian, Tiezheng

    2016-03-01

    The dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)] is employed to model the growth of a single vapor bubble in a superheated liquid on a flat homogeneous substrate. The bubble spreading dynamics in the pool boiling regime has been numerically investigated for one-component van der Waals fluids close to the critical point, with a focus on the effect of the substrate wettability on bubble growth and contact line motion. The substrate wettability is found to control the apparent contact angle and the rate of bubble growth (the rate of total evaporation), through which the contact line speed is determined. An approximate expression is derived for the contact line speed, showing good agreement with the simulation results. This demonstrates that the contact line speed is primarily governed by (1) the circular shape of interface (for slow bubble growth), (2) the constant apparent contact angle, and (3) the constant bubble growth rate. It follows that the contact line speed has a sensitive dependence on the substrate wettability via the apparent contact angle which also determines the bubble growth rate. Compared to hydrophilic surfaces, hydrophobic surfaces give rise to a thinner shape of bubble and a higher rate of total evaporation, which combine to result in a much faster contact line speed. This can be linked to the earlier formation of a vapor film and hence the onset of boiling crisis.

  9. Thermal singularity and contact line motion in pool boiling: Effects of substrate wettability

    NASA Astrophysics Data System (ADS)

    Taylor, M. T.; Qian, Tiezheng

    2016-03-01

    The dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007), 10.1103/PhysRevE.75.036304] is employed to model the growth of a single vapor bubble in a superheated liquid on a flat homogeneous substrate. The bubble spreading dynamics in the pool boiling regime has been numerically investigated for one-component van der Waals fluids close to the critical point, with a focus on the effect of the substrate wettability on bubble growth and contact line motion. The substrate wettability is found to control the apparent contact angle and the rate of bubble growth (the rate of total evaporation), through which the contact line speed is determined. An approximate expression is derived for the contact line speed, showing good agreement with the simulation results. This demonstrates that the contact line speed is primarily governed by (1) the circular shape of interface (for slow bubble growth), (2) the constant apparent contact angle, and (3) the constant bubble growth rate. It follows that the contact line speed has a sensitive dependence on the substrate wettability via the apparent contact angle which also determines the bubble growth rate. Compared to hydrophilic surfaces, hydrophobic surfaces give rise to a thinner shape of bubble and a higher rate of total evaporation, which combine to result in a much faster contact line speed. This can be linked to the earlier formation of a vapor film and hence the onset of boiling crisis.

  10. Boiling effect in liquid nitrogen directly cooled Yb³⁺:YAG laser.

    PubMed

    Sakurai, Toshimitsu; Chosrowjan, Haik; Furuse, Hiroaki; Taniguchi, Seiji; Kitamura, Toshiyuki; Fujita, Masayuki; Ishii, Shinya; Izawa, Yasukazu

    2016-02-20

    Liquid nitrogen (LN2) behavior on the surface of excited Yb(3+):YAG is investigated using fluorometry. From the time-resolved temperature variations and integrated fluorescence spectra intensity on this directly cooled Yb(3+):YAG surface, we observe a phase transition of LN2 from nucleate boiling to film boiling. As a result of this pool boiling, good beam quality should occur when the temperature and heat flux at an excited surface of Yb(3+):YAG are below 95 K and 15.8  W/cm2, respectively. That is, the LN2 should remain in a steady state of nucleate boiling to produce good beam quality using pool boiling.

  11. Boiling of the interface between two immiscible liquids below the bulk boiling temperatures of both components.

    PubMed

    Pimenova, Anastasiya V; Goldobin, Denis S

    2014-11-01

    We consider the problem of boiling of the direct contact of two immiscible liquids. An intense vapour formation at such a direct contact is possible below the bulk boiling points of both components, meaning an effective decrease of the boiling temperature of the system. Although the phenomenon is known in science and widely employed in technology, the direct contact boiling process was thoroughly studied (both experimentally and theoretically) only for the case where one of liquids is becoming heated above its bulk boiling point. On the contrary, we address the case where both liquids remain below their bulk boiling points. In this paper we construct the theoretical description of the boiling process and discuss the actualisation of the case we consider for real systems.

  12. Thermal performance of a geofluid direct-contact heat exchanger

    SciTech Connect

    Wiggins, D.J.; Mines, G.L.; Wahl, E.

    1983-01-01

    A sieve-tray direct-contact heat exchanger was used to transfer heat from a 280/sup 0/F geothermal fluid to the working fluid, isobutane, in the Raft River 60kW prototype plant. A series of experiments were run at different working fluid-to-geofluid flow ratios which produced different boiling conditions. In this paper, the results of these experiments are analyzed on the basis of thermal performance. The flow ratio, the geofluid outlet temperature, the working fluid inlet temperature, the amount of working fluid dissolved or entrained in geofluid, and tray efficiency are varied and preheating temperature profiles are calculated. These are compared with the experimentally obtained temperature profiles and the relative effects of the variables are evaluated. From this, it was determined that the approach temperature difference was on the order of .1/sup 0/ after 17 preheating trays, and the tray efficiencies, which appear to be about the same for all trays, reached approx. 70%. It was also determined that entrainment has a negligible effect on column thermal performance. The thermal performance of this column compares favorably with a spray-tower direct-contact heat exchanger and a shell-and-tube heat exchanger in terms of overall heat-transfer coefficient. Distributor tray and boiling tray behavior are discussed. These is some discussion of operations and thermal hydraulics as well.

  13. Direct-Write Contacts: Metallization and Contact Formation; Preprint

    SciTech Connect

    van Hest, M. F. A. M.; Curtis, C. J.; Miedaner, A.; Pasquarelli, R. M.; Kaydonova, T.; Hersh, P.; Ginley, D. S.

    2008-05-01

    Using direct-write approaches in photovoltaics for metallization and contact formation can significantly reduce the cost per watt of producing photovoltaic devices. Inks have been developed for various materials, such as Ag, Cu, Ni and Al, which can be used to inkjet print metallizations for various kinds of photovoltaic devices. Use of these inks results in metallization with resistivities close to those of bulk materials. By means of inkjet printing a metallization grid can be printed with better resolution, i.e. smaller lines, than screen-printing. Also inks have been developed to deposit transparent conductive oxide films by means of ultrasonic spraying.

  14. Numerical Investigation of Boiling

    NASA Astrophysics Data System (ADS)

    Sagan, Michael; Tanguy, Sebastien; Colin, Catherine

    2012-11-01

    In this work, boiling is numerically investigated, using two phase flow direct numerical simulation based on a level set / Ghost Fluid method. Nucleate boiling implies both thermal issue and multiphase dynamics issues at different scales and at different stages of bubble growth. As a result, the different phenomena are investigated separately, considering their nature and the scale at which they occur. First, boiling of a static bubble immersed in an overheated liquid is analysed. Numerical simulations have been performed at different Jakob numbers in the case of strong density discontinuity through the interface. The results show a good agreement on bubble radius evolution between the theoretical evolution and numerical simulation. After the validation of the code for the Scriven test case, interaction of a bubble with a wall is studied. A numerical method taking into account contact angle is evaluated by comparing simulations of the spreading of a liquid droplet impacting on a plate, with experimental data. Then the heat transfer near the contact line is investigated, and simulations of nucleate boiling are performed considering different contact angles values. Finally, the relevance of including a model to take into account the evaporation of the micro layer is discussed.

  15. Direct contact, binary fluid geothermal boiler

    DOEpatents

    Rapier, P.M.

    1979-12-27

    Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carryover through the turbine causing corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

  16. Direct contact, binary fluid geothermal boiler

    DOEpatents

    Rapier, Pascal M.

    1982-01-01

    Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carry-over through the turbine causes corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.

  17. ER contact sites direct late endosome transport.

    PubMed

    Wijdeven, Ruud H; Jongsma, Marlieke L M; Neefjes, Jacques; Berlin, Ilana

    2015-12-01

    Endosomes shuttle select cargoes between cellular compartments and, in doing so, maintain intracellular homeostasis and enable interactions with the extracellular space. Directionality of endosomal transport critically impinges on cargo fate, as retrograde (microtubule minus-end directed) traffic delivers vesicle contents to the lysosome for proteolysis, while the opposing anterograde (plus-end directed) movement promotes recycling and secretion. Intriguingly, the endoplasmic reticulum (ER) is emerging as a key player in spatiotemporal control of late endosome and lysosome transport, through the establishment of physical contacts with these organelles. Earlier studies have described how minus-end-directed motor proteins become discharged from vesicles engaged at such contact sites. Now, Raiborg et al. implicate ER-mediated interactions, induced by protrudin, in loading plus-end-directed motor kinesin-1 onto endosomes, thereby stimulating their transport toward the cell's periphery. In this review, we recast the prevailing concepts on bidirectional late endosome transport and discuss the emerging paradigm of inter-compartmental regulation from the ER-endosome interface viewpoint. © 2015 WILEY Periodicals, Inc.

  18. Experimental investigation and simulation of flow boiling of nanofluids in different flow directions

    NASA Astrophysics Data System (ADS)

    Afrand, Masoud; Abedini, Ehsan; Teimouri, Hamid

    2017-03-01

    In this work, the flow boiling of TiO2/water and Al2O3/water nanofluids was investigated experimentally and simulated with two phases. Experimental results were obtained in two directions and compared together. The volume fraction and heat transfer coefficient obtained from the vertical tube were compared with those obtained from the horizontal tube. The results showed that the contours of vapor volume fraction in horizontal tube are completely different from the vertical tube, which is due to the buoyancy effect. Moreover, the effect of nanoparticles on both flow directions was almost the same, while heat transfer coefficient was not the same in these flow directions. Based on the experimental result, presence of nanoparticles in the base fluid cannot increase the heat transfer coefficient.

  19. Direct Numerical Simulation of Boiling Multiphase Flows: State-of-the-Art, Modeling, Algorithmic and Computer Needs

    SciTech Connect

    Nourgaliev R.; Knoll D.; Mousseau V.; Berry R.

    2007-04-01

    The state-of-the-art for Direct Numerical Simulation (DNS) of boiling multiphase flows is reviewed, focussing on potential of available computational techniques, the level of current success for their applications to model several basic flow regimes (film, pool-nucleate and wall-nucleate boiling -- FB, PNB and WNB, respectively). Then, we discuss multiphysics and multiscale nature of practical boiling flows in LWR reactors, requiring high-fidelity treatment of interfacial dynamics, phase-change, hydrodynamics, compressibility, heat transfer, and non-equilibrium thermodynamics and chemistry of liquid/vapor and fluid/solid-wall interfaces. Finally, we outline the framework for the {\\sf Fervent} code, being developed at INL for DNS of reactor-relevant boiling multiphase flows, with the purpose of gaining insight into the physics of multiphase flow regimes, and generating a basis for effective-field modeling in terms of its formulation and closure laws.

  20. Geysers advanced direct contact condenser research

    SciTech Connect

    Henderson, J.; Bahning, T.; Bharathan, D.

    1997-12-31

    The first geothermal application of the Advanced Direct Contact Condenser (ADCC) technology developed by the National Renewable Energy Laboratory (NREL) is now operational and is being tested at The Geysers Power Plant Unit 11. This major research effort is being supported through the combined efforts of NREL, The Department of Energy (DOE), and Pacific Gas and Electric (PG&E). NREL and PG&E have entered into a Cooperative Research And Development Agreement (CRADA) for a project to improve the direct-contact condenser performance at The Geysers Power Plant. This project is the first geothermal adaptation of an advanced condenser design developed for the Ocean Thermal Energy Conversion (OTEC) systems. PG&E expects this technology to improve power plant performance and to help extend the life of the steam field by using steam more efficiently. In accordance with the CRADA, no money is transferred between the contracting parties. In this case the Department of Energy is funding NREL for their efforts in this project and PG&E is contributing funds in kind. Successful application of this technology at The Geysers will provide a basis for NREL to continue to develop this technology for other geothermal and fossil power plant systems.

  1. Non-contact method for directing electrotaxis

    NASA Astrophysics Data System (ADS)

    Ahirwar, Dinesh K.; Nasser, Mohd W.; Jones, Travis H.; Sequin, Emily K.; West, Joseph D.; Henthorne, Timothy L.; Javor, Joshua; Kaushik, Aniruddha M.; Ganju, Ramesh K.; Subramaniam, Vish V.

    2015-06-01

    We present a method to induce electric fields and drive electrotaxis (galvanotaxis) without the need for electrodes to be in contact with the media containing the cell cultures. We report experimental results using a modification of the transmembrane assay, demonstrating the hindrance of migration of breast cancer cells (SCP2) when an induced a.c. electric field is present in the appropriate direction (i.e. in the direction of migration). Of significance is that migration of these cells is hindered at electric field strengths many orders of magnitude (5 to 6) below those previously reported for d.c. electrotaxis, and even in the presence of a chemokine (SDF-1α) or a growth factor (EGF). Induced a.c. electric fields applied in the direction of migration are also shown to hinder motility of non-transformed human mammary epithelial cells (MCF10A) in the presence of the growth factor EGF. In addition, we also show how our method can be applied to other cell migration assays (scratch assay), and by changing the coil design and holder, that it is also compatible with commercially available multi-well culture plates.

  2. Non-contact method for directing electrotaxis

    PubMed Central

    Ahirwar, Dinesh K.; Nasser, Mohd W.; Jones, Travis H.; Sequin, Emily K.; West, Joseph D.; Henthorne, Timothy L.; Javor, Joshua; Kaushik, Aniruddha M.; Ganju, Ramesh K.; Subramaniam, Vish V.

    2015-01-01

    We present a method to induce electric fields and drive electrotaxis (galvanotaxis) without the need for electrodes to be in contact with the media containing the cell cultures. We report experimental results using a modification of the transmembrane assay, demonstrating the hindrance of migration of breast cancer cells (SCP2) when an induced a.c. electric field is present in the appropriate direction (i.e. in the direction of migration). Of significance is that migration of these cells is hindered at electric field strengths many orders of magnitude (5 to 6) below those previously reported for d.c. electrotaxis, and even in the presence of a chemokine (SDF-1α) or a growth factor (EGF). Induced a.c. electric fields applied in the direction of migration are also shown to hinder motility of non-transformed human mammary epithelial cells (MCF10A) in the presence of the growth factor EGF. In addition, we also show how our method can be applied to other cell migration assays (scratch assay), and by changing the coil design and holder, that it is also compatible with commercially available multi-well culture plates. PMID:26055698

  3. Direct contact heat recovery from molten salt

    NASA Astrophysics Data System (ADS)

    Technological deficiencies associated with efficient and economical retrieval of heat energy from molten salt systems are addressed. The large latent heat of fusion stored in molten salt hydrates and other candidate phase change materials (PCM) is removed by internal boiling of a volatile heat transfer fluid (HTF). This procedure eliminates the conventional use of submerged heat exchangers which are costly and, in crystallizing salts, ineffective. The thermochemical conditions and material properties that are critical for application of this concept in environments that yield significant energy savings are investigated and defined.

  4. 37 CFR 10.33 - Direct contact with prospective clients.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Direct contact with... Patent and Trademark Office Code of Professional Responsibility § 10.33 Direct contact with prospective... evidencing undue influence, intimidation, or overreaching. The term “solicit” includes contact in person,...

  5. 37 CFR 10.33 - Direct contact with prospective clients.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Direct contact with... Patent and Trademark Office Code of Professional Responsibility § 10.33 Direct contact with prospective... evidencing undue influence, intimidation, or overreaching. The term “solicit” includes contact in person,...

  6. Spectral measurements of direct and scattered gamma radiation at a boiling-water reactor site

    NASA Astrophysics Data System (ADS)

    Block, R. C.; Preiss, I. L.; Ryan, R. M.; Vargo, G. J.

    1990-12-01

    Quantitative surveys of direct and scattered gamma radiation emitted from the steam-power conversion systems of a boiling-water reactor and other on-site radiation sources were made using a directionally shielded HPGe gamma spectrometry system. The purpose of this study was to obtain data on the relative contributions and energy distributions of direct and scattered gamma radiation in the site environs. The principal radionuclide of concern in this study is 16N produced by the 16O(n,p) 16N reaction in the reactor coolant. Due to changes in facility operation resulting from the implementation of hydrogen water chemistry (HWC), the amount of 16N transported from the reactor to the main steam system under full power operation is excepted to increase by a factor of 1.2 to 5.0. This increase in the 16N source term in the nuclear steam must be considered in the design of new facilities to be constructed on site as well as the evaluation of existing facilities with repect to ALARA (As Low As Reasonably Achievable) dose limits in unrestricted areas. This study consisted of base-line measurements taken under normal BWR chemistry conditions in October, 1987 and a corresponding set taken under HWC conditions in July, 1988. Ground-level and elevated measurements, corresponding to second-story building height, were obtained. The primary conclusion of this study is that direct radiation from the steam-power conversion system is the predominant source of radiation in the site environs of this reactor and that air scattering (i.e. skyshine) does not appear to be significant.

  7. String flash-boiling in gasoline direct injection simulations with transient needle motion

    SciTech Connect

    Baldwin, Eli T.; Grover, Jr., Ronald O.; Parrish, Scott E.; Duke, D. J.; Matusik, K. E.; Powell, C. F.; Kastengren, A. L.; Schmidt, D. P.

    2016-09-06

    A computational study was performed to investigate the influence of transient needle motion on gasoline direct injection (GDI) internal nozzle flow and near-field sprays. Simulations were conducted with a compressible Eulerian flow solver modeling liquid, vapor, and non-condensable gas phases with a diffuse interface. Variable rate generation and condensation of fuel vapor were captured using the homogeneous relaxation model (HRM). The non-flashing (spray G) and flashing (spray G2) conditions specified by the Engine Combustion Network were modeled using the nominal spray G nozzle geometry and transient needle lift and wobble were based upon ensemble averaged x-ray imaging preformed at Argonne National Lab. The minimum needle lift simulated was 5 μm and dynamic mesh motion was achieved with Laplacian smoothing. The results were qualitatively validated against experimental imaging and the experimental rate of injection profile was captured accurately using pressure boundary conditions and needle motion to actu- ate the injection. Needle wobble was found to have no measurable effect on the flow. Low needle lift is shown to result in vapor generation as fuel rushes past the needle. In conclusion, the internal injector flow is shown to contain many transient and interacting vortices which cause perturbations in the spray angle, fluctuations in the mass flux, and frequently result in string flash-boiling.

  8. String flash-boiling in gasoline direct injection simulations with transient needle motion

    DOE PAGES

    Baldwin, Eli T.; Grover, Jr., Ronald O.; Parrish, Scott E.; ...

    2016-09-06

    A computational study was performed to investigate the influence of transient needle motion on gasoline direct injection (GDI) internal nozzle flow and near-field sprays. Simulations were conducted with a compressible Eulerian flow solver modeling liquid, vapor, and non-condensable gas phases with a diffuse interface. Variable rate generation and condensation of fuel vapor were captured using the homogeneous relaxation model (HRM). The non-flashing (spray G) and flashing (spray G2) conditions specified by the Engine Combustion Network were modeled using the nominal spray G nozzle geometry and transient needle lift and wobble were based upon ensemble averaged x-ray imaging preformed at Argonnemore » National Lab. The minimum needle lift simulated was 5 μm and dynamic mesh motion was achieved with Laplacian smoothing. The results were qualitatively validated against experimental imaging and the experimental rate of injection profile was captured accurately using pressure boundary conditions and needle motion to actu- ate the injection. Needle wobble was found to have no measurable effect on the flow. Low needle lift is shown to result in vapor generation as fuel rushes past the needle. In conclusion, the internal injector flow is shown to contain many transient and interacting vortices which cause perturbations in the spray angle, fluctuations in the mass flux, and frequently result in string flash-boiling.« less

  9. The effect of heating direction on flow boiling heat transfer of R134a in micro-channels

    NASA Astrophysics Data System (ADS)

    Xu, Mingchen; Jia, Li; Dang, Chao; Peng, Qi

    2017-04-01

    This paper presents effects of heating directions on heat transfer performance of R134a flow boiling in micro- channel heat sink. The heat sink has 30 parallel rectangular channels with cross-sectional dimensions of 500μm width 500μm depth and 30mm length. The experimental operation condition ranges of the heat flux and the mass flux were 13.48 to 82.25 W/cm2 and 373.3 to 1244.4 kg/m2s respectively. The vapor quality ranged from 0.07 to 0.93. The heat transfer coefficients of top heating and bottom heating both were up to 25 kW/m2 K. Two dominate transfer mechanisms of nucleate boiling and convection boiling were observed according to boiling curves. The experimental results indicated that the heat transfer coefficient of bottom heating was 13.9% higher than top heating in low heat flux, while in high heat flux, the heat transfer coefficient of bottom heating was 9.9%.higher than the top heating, because bubbles were harder to divorce the heating wall. And a modified correlation was provided to predict heat transfer of top heating.

  10. Applying Directed Graph Theory to Faculty Contact Structure.

    ERIC Educational Resources Information Center

    House, Ernest R.; Long, John M.

    Although recent writings indicate the importance of personal contact structures in diffusing innovations and in determining perceptions, the internal contact structure of the school faculty remains unexamined. This study applies directed graph theory, a new branch of mathematics, to analyzing school contact structure. Sociometric data and…

  11. 37 CFR 11.703 - Direct contact with prospective clients.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false Direct contact with... contact with prospective clients. (a) A practitioner shall not by in-person, live telephone or real-time electronic contact solicit professional employment from a prospective client when a significant motive...

  12. 37 CFR 11.703 - Direct contact with prospective clients.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Direct contact with... contact with prospective clients. (a) A practitioner shall not by in-person, live telephone or real-time electronic contact solicit professional employment from a prospective client when a significant motive...

  13. Direct-Write Contacts for Solar Cells

    SciTech Connect

    Kaydanova, T.; van Hest, M.F.A.M.; Miedaner, A.; Curtis, C. J.; Alleman, J. L.; Dabney, M. S.; Garnett, E.; Shaheen, S.; Ginley, D. S.; Smith, L.; Collins, R.; Hanoka, J. I.; Gabor, A. M.

    2005-01-01

    We report on our project to develop inkjet printable contacts for solar cells. Ag, Cu, and Ni metallizations were inkjet printed with near vacuum deposition quality. Thick, highly conducting lines of Ag and Cu demonstrating good adhesion to glass, Si, and PCB have been printed at 100-200 C in air and N2, respectively. Ag grids were inkjet-printed on Si solar cells and fired through silicon nitride AR layer at 850 C resulting in 8% cells. Next-generation multicomponent inks (including etching agents) have also been developed with improved fire-through contacts leading to higher cell efficiencies. The approach developed can be easily extended to other conductors such as Pt, Pd, and Au, etc. In addition, PEDOT-PSS polymer-based conductors were inkjet-printed with the conductivity as good or better than those of polymer-based conductors.

  14. Simplified method to obtain enhanced expression of tau protein from E. coli and one-step purification by direct boiling.

    PubMed

    KrishnaKumar, V Guru; Gupta, Sharad

    2017-01-03

    Tau is an intrinsically disordered protein responsible for maintaining the structure and stability of axonal microtubules. However, in certain disease conditions including Alzheimer's disease, tau protein may undergo biochemical and structural changes to form intracellular aggregates. Since tau is a proline- and arginine-rich eukaryotic protein, heterologous expression in Escherichia coli often results in poor yield and has been a major technical challenge. In the current work, we have improved the expressed yield of tau by overcoming codon bias problem and established a simplified protocol for efficient extraction. The reported method has two distinct features: (i) enhanced tau expression (upto eightfold) by supplementing deficient tRNAs that aid in rapid translation and (ii) direct boiling of expressed E. coli cells to extract tau with no separate cell lysis step. We further demonstrate that tau extracted by the direct boiling method is similar to tau purified by size-exclusion chromatography exhibiting similar structural and biophysical characteristics including aggregation propensity. Since morphologies and in vitro toxicity of fibrillar tau aggregates were also similar, tau extracted by the one-step direct boiling method can be used for tau aggregation assays without any additional purification.

  15. Comparison of direct boiling method with commercial kits for extracting fecal microbiome DNA by Illumina sequencing of 16S rRNA tags.

    PubMed

    Peng, Xin; Yu, Ke-Qiang; Deng, Guan-Hua; Jiang, Yun-Xia; Wang, Yu; Zhang, Guo-Xia; Zhou, Hong-Wei

    2013-12-01

    Low cost and high throughput capacity are major advantages of using next generation sequencing (NGS) techniques to determine metagenomic 16S rRNA tag sequences. These methods have significantly changed our view of microorganisms in the fields of human health and environmental science. However, DNA extraction using commercial kits has shortcomings of high cost and time constraint. In the present study, we evaluated the determination of fecal microbiomes using a direct boiling method compared with 5 different commercial extraction methods, e.g., Qiagen and MO BIO kits. Principal coordinate analysis (PCoA) using UniFrac distances and clustering showed that direct boiling of a wide range of feces concentrations gave a similar pattern of bacterial communities as those obtained from most of the commercial kits, with the exception of the MO BIO method. Fecal concentration by boiling method affected the estimation of α-diversity indices, otherwise results were generally comparable between boiling and commercial methods. The operational taxonomic units (OTUs) determined through direct boiling showed highly consistent frequencies with those determined through most of the commercial methods. Even those for the MO BIO kit were also obtained by the direct boiling method with high confidence. The present study suggested that direct boiling could be used to determine the fecal microbiome and using this method would significantly reduce the cost and improve the efficiency of the sample preparation for studying gut microbiome diversity.

  16. Direct Write Contacts for Solar Cells

    SciTech Connect

    Kaydanova, T.; van Hest, M.F.A.M.; Miedaner, A.; Curtis, C. J.; Alleman, J. L.; Dabney, M. S.; Garnett, E.; Shaheen, S.; Smith, L.; Collins, R.; Hanoka, J. I.; Gabor, A. M.; Ginley, D.S.

    2005-02-01

    Ag, Cu, and Ni metallizations were inkjet-printed with near-vacuum deposition quality. The approach developed can be easily extended to other conductors such as Pt, Pd, and Au. Thick, highly conducting lines of Ag and Cu demonstrating good adhesion to glass, Si, and PCB have been printed at 100-200 C in air and N2, respectively. Ag grids were inkjet-printed on Si solar cells and fired through the silicon nitride antireflective layer at 850 C resulting in 8%-efficient cells. Next-generation multicomponent inks (including etching agents) have also been developed with improved fire-through contacts leading to higher cell efficiencies. PEDOT-PSS polymer-based conductors were inkjet-printed with conductivity as good or better than that of spin-coated films.

  17. Direct-contact closed-loop heat exchanger

    DOEpatents

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1984-01-01

    A high temperature heat exchanger with a closed loop and a heat transfer liquid within the loop, the closed loop having a first horizontal channel with inlet and outlet means for providing direct contact of a first fluid at a first temperature with the heat transfer liquid, a second horizontal channel with inlet and outlet means for providing direct contact of a second fluid at a second temperature with the heat transfer liquid, and means for circulating the heat transfer liquid.

  18. Method and apparatus for high-efficiency direct contact condensation

    DOEpatents

    Bharathan, Desikan; Parent, Yves; Hassani, A. Vahab

    1999-01-01

    A direct contact condenser having a downward vapor flow chamber and an upward vapor flow chamber, wherein each of the vapor flow chambers includes a plurality of cooling liquid supplying pipes and a vapor-liquid contact medium disposed thereunder to facilitate contact and direct heat exchange between the vapor and cooling liquid. The contact medium includes a plurality of sheets arranged to form vertical interleaved channels or passageways for the vapor and cooling liquid streams. The upward vapor flow chamber also includes a second set of cooling liquid supplying pipes disposed beneath the vapor-liquid contact medium which operate intermittently in response to a pressure differential within the upward vapor flow chamber. The condenser further includes separate wells for collecting condensate and cooling liquid from each of the vapor flow chambers. In alternate embodiments, the condenser includes a cross-current flow chamber and an upward flow chamber, a plurality of upward flow chambers, or a single upward flow chamber. The method of use of the direct contact condenser of this invention includes passing a vapor stream sequentially through the downward and upward vapor flow chambers, where the vapor is condensed as a result of heat exchange with the cooling liquid in the contact medium. The concentration of noncondensable gases in the resulting condensate-liquid mixtures can be minimized by controlling the partial pressure of the vapor, which depends in part upon the geometry of the vapor-liquid contact medium. In another aspect of this invention, the physical and chemical performance of a direct contact condenser can be predicted based on the vapor and coolant compositions, the condensation conditions. and the geometric properties of the contact medium.

  19. Method and apparatus for high-efficiency direct contact condensation

    DOEpatents

    Bharathan, D.; Parent, Y.; Hassani, A.V.

    1999-07-20

    A direct contact condenser having a downward vapor flow chamber and an upward vapor flow chamber, wherein each of the vapor flow chambers includes a plurality of cooling liquid supplying pipes and a vapor-liquid contact medium disposed thereunder to facilitate contact and direct heat exchange between the vapor and cooling liquid. The contact medium includes a plurality of sheets arranged to form vertical interleaved channels or passageways for the vapor and cooling liquid streams. The upward vapor flow chamber also includes a second set of cooling liquid supplying pipes disposed beneath the vapor-liquid contact medium which operate intermittently in response to a pressure differential within the upward vapor flow chamber. The condenser further includes separate wells for collecting condensate and cooling liquid from each of the vapor flow chambers. In alternate embodiments, the condenser includes a cross-current flow chamber and an upward flow chamber, a plurality of upward flow chambers, or a single upward flow chamber. The method of use of the direct contact condenser of this invention includes passing a vapor stream sequentially through the downward and upward vapor flow chambers, where the vapor is condensed as a result of heat exchange with the cooling liquid in the contact medium. The concentration of noncondensable gases in the resulting condensate-liquid mixtures can be minimized by controlling the partial pressure of the vapor, which depends in part upon the geometry of the vapor-liquid contact medium. In another aspect of this invention, the physical and chemical performance of a direct contact condenser can be predicted based on the vapor and coolant compositions, the condensation conditions, and the geometric properties of the contact medium. 39 figs.

  20. A Direct analysis of elastic contact using super elements

    NASA Astrophysics Data System (ADS)

    Pedersen, Pauli

    2006-02-01

    Solutions to contact problems are important in mechanical as well as in civil engineering, and even for the most simple problems there is still a need for research results. In the present paper we suggest an alternative finite element procedure and by examples show the need for more knowledge related to the compliance of contact surfaces. The most simple solutions are named Hertz solutions from 1882, and we use some of these solutions for comparison with our finite element results. As a function of the total contact force we find the size of the contact area, the distribution of the contact pressure, and the contact compliance. In models of finite size the compliance depends on the flexibility of the total model, including the boundary condition of the model, and therefore disagreement with the locally based analytical models is expected and found. With computational contact mechanics we can solve more advanced contact problems and treat models that are closer to physical reality. The finite element method is widely used and solutions are obtained by incrementation and/or iteration for these non-linear problems with unknown boundary conditions. Still with these advanced tools the solution is difficult because of extreme sensitivity. Here we present a direct analysis of elastic contact without incrementation and iteration, and the procedure is based on a finite element super element technique. This means that the contacting bodies can be analyzed independently, and are only coupled through a direct analysis with low order super element stiffness matrices. The examples of the present paper are restricted to axisymmetric problems with isotropic, elastic materials and excluding friction. Direct extensions to cases of non-isotropy, including laminates, and to plane and general 3D models are possible.

  1. Direct contact between donor families and recipients: crisis or consolation?

    PubMed

    Albert, P

    1998-09-01

    A dramatic growth has been seen in the number of organ procurement organizations, transplant programs, and new initiatives related to solving the organ shortage, as well as in the development of protocols dealing with the logistics of facilitating organ and tissue recovery. Extensive deliberation on critical issues related to the organ donor shortage is evident in professional meetings, publications, and educational endeavors. Little research has been conducted, however, regarding direct contact between donor families and recipients, a highly controversial subject in transplantation and procurement. Should there be contact between donor families and recipients? What format should such contacts take? Who should decide? These are questions that must be considered in the field. This article will explore an organ procurement organization's 5-year experience regarding direct contact between donor families and recipients.

  2. Aspects of subcooled boiling

    SciTech Connect

    Bankoff, S.G.

    1997-12-31

    Subcooled boiling boiling refers to boiling from a solid surface where the bulk liquid temperature is below the saturation temperature (subcooled). Two classes are considered: (1) nucleate boiling, where, for large subcoolings, individual bubbles grow and collapse while remaining attached to the solid wall, and (2) film boiling, where a continuous vapor film separates the solid from the bulk liquid. One mechanism by which subcooled nucleate boiling results in very large surface heat transfer coefficient is thought to be latent heat transport within the bubble, resulting from simultaneous evaporation from a thin residual liquid layer at the bubble base, and condensation at the polar bubble cap. Another is the increased liquid microconvection around the oscillating bubble. Two related problems have been attacked. One is the rupture of a thin liquid film subject to attractive and repulsive dispersion forces, leading to the formation of mesoscopic drops, which then coalesce and evaporate. Another is the liquid motion in the vicinity of an oscillating contact line, where the bubble wall is idealized as a wedge of constant angle sliding on the solid wall. The subcooled film boiling problem has been attacked by deriving a general long-range nonlinear evolution equation for the local thickness of the vapor layer. Linear and weakly-nonlinear stability results have been obtained. A number of other related problems have been attacked.

  3. Direct contact heat transfer for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Wright, J. D.

    1982-03-01

    Direct contact heat exchange offers the potential for increased efficiency and lower heat transfer costs in a variety of thermal energy storage systems. SERI models of direct contact heat transfer based on literature information identified dispersed phase drop size, the mechanism of heat transfer within the drop, and dispersed phase holdup as the parameters controlling direct contact system performance. Tests were defined and equipment constructed to provide independent determination of drop size, heat transfer mechanism, and hold up. Further experiments are needed to conclusively determine whether the salt in a salt hydrate melt acts to block internal circulation. The potential of low temperature oil/salt hydrate latent heat storage systems is being evaluated in the laboratory.

  4. Direct contact heat transfer for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Wright, J. D.

    1980-11-01

    Direct contact heat exchange offers the potential for increased efficiency and lower heat transfer costs in a variety of thermal energy storage systems. Models of direct contact heat transfer based on literature information identified dispersed phase drop size, the mechanism of heat transfer within the drop, and dispersed phase holdup as the parameters controlling direct contact system performance. Tests were defined and equipment constructed to provide independent determination of drop size, heat transfer mechanism, and hold up. Experiments with heptane dispersed in water are described. The velocity at which drop formation changes from dropwise to jetting was overpredicted by all literature correlations. Further experiments are needed to conclusively determine whether the salt in a salt hydrate melt acts to block internal circulation. In addition, the potential of low temperature oil/salt hydrate latent heat storage systems is evaluated in the laboratory.

  5. Direct-contact closed-loop heat exchanger

    DOEpatents

    Berry, G.F.; Minkov, V.; Petrick, M.

    1981-11-02

    A high temperature heat exchanger is disclosed which has a closed loop and a heat transfer liquid within the loop, the closed loop having a first horizontal channel with inlet and outlet means for providing direct contact of a first fluid at a first temperature with the heat transfer liquid, a second horizontal channel with inlet and outlet means for providing direct contact of a second fluid at a second temperature with the heat transfer liquid, and means for circulating the heat transfer liquid.

  6. Pool boiling

    SciTech Connect

    Lallemand, M.

    1993-10-01

    Heat transfer between a wall and a stagnant boiling liquid is reviewed in this paper. The effect of different parameters on the boiling curve is pointed out on the basis of experimental data from the literature. Augmentation of heat transfer by enhanced surfaces is described briefly. The available correlations for prediction of heat transfer coefficients are given for the entire boiling curve, i.e., nucleate, transitional, and film boiling, and critical points. These correlations are useful for the design and operation of various heat-exchange systems.

  7. 37 CFR 10.33 - Direct contact with prospective clients.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Patent and Trademark Office Code of Professional Responsibility § 10.33 Direct contact with prospective clients. A practitioner may not solicit professional employment from a prospective client with whom the practitioner has no family or prior professional relationship, by mail, in-person or otherwise, when a...

  8. Flow Boiling and Condensation Experiment

    NASA Image and Video Library

    The Flow Boiling and Condensation Experiment is another investigation that examines the flow of a mixture of liquids and the vapors they produce when in contact with hot space system equipment. Coo...

  9. Direct measurement of friction of a fluctuating contact line

    NASA Astrophysics Data System (ADS)

    Guo, Shuo; Gao, Min; Xiong, Xiaomin; Wang, Yong Jian; Wang, Xiaoping; Sheng, Ping; Tong, Penger

    2013-03-01

    What happens at a moving contact line, where one fluid displaces another (immiscible) fluid over a solid surface, is a fundamental issue in fluid dynamics. In this presentation, we report a direct measurement of the friction coefficient in the immediate vicinity of a fluctuating contact line using a micron-sized vertical glass fiber with one end glued to an atomic force microscope (AFM) cantilever beam and the other end touching a liquid-air interface. By measuring the broadening of the resonance peak of the cantilever system with varying liquid viscosity η, we obtain the friction coefficient ξc associated with the contact line fluctuations on the glass fiber of diameter d and find it has the universal form, ξc = 0 . 8 πdη , independent of the contact angle. The result is further confirmed by using a soap film system whose bulk effect is negligibly small. This is the first time that the friction coefficient of a fluctuating contact line is measured. *Work supported by the Research Grants Council of Hong Kong SAR.

  10. The potential of block copolymer's directed self-assembly for contact hole shrink and contact multiplication

    NASA Astrophysics Data System (ADS)

    Tiron, R.; Gharbi, A.; Argoud, M.; Chevalier, X.; Belledent, J.; Pimmenta Barros, P.; Servin, I.; Navarro, C.; Cunge, G.; Barnola, S.; Pain, L.; Asai, M.; Pieczulewski, C.

    2013-03-01

    The goal of this paper is to investigate the potential of Directed Self-Assembly (DSA) to address contact via level patterning, by either Critical Dimension (CD) shrink or contact multiplication. Using the 300mm pilot line available in LETI and Arkema materials, our approach is based on the graphoepitaxy of PS-b- PMMA block copolymers (BCP). The process consists in the following steps: a) the lithography of guiding patterns, b) the DSA of block copolymers and PMMA removal and finally c) the transfer of PS patterns into the under-layer by plasma etching. Several integration schemes using 193nm dry lithography are evaluated: negative tone development (NTD) resists, a tri-layer approach, frozen resists, etc. The advantages and limitations of each approach are reported. Furthermore, the impact of the BCP on the final patterns characteristics is investigated by tuning different parameters such as the molecular weight of the polymeric constituents and the interaction with the substrate. The optimization of the self-assembly process parameters in terms of film thickness or bake (temperature and time) is also reported. Finally, the transfer capabilities of the PS nanostructures in bulk silicon substrate by using plasma-etching are detailed. These results show that DSA has a high potential to be integrated directly into the conventional CMOS lithography process in order to achieve high-resolution contact holes. Furthermore, in order to prevent design restrictions, this approach may be extended to more complex structures with multiple contacts and nonhexagonal symmetries.

  11. Potential industrial applications for direct contact waste heat recuperator systems

    NASA Astrophysics Data System (ADS)

    Semler, T. T.

    1981-02-01

    Four potential applications were chosen for economic analysis. They are: stack gas from diesel electric generation, boiler stack gas, waste heat stream from the hydraulic cement dry process dryer, and stack gas from the fire polishing of glass. The waste heat streams studied ranged from 175 to 7500 F. A physical analogue of the direct contact waste heat recuperator system was devised and used for costing purposes. Payback calculations were performed for these applications. Only the stack gas from the fire polishing of glass failed to show significant economic promise. A waste heat stream regime of greater than 10,000 cfm and between 400 and 7500 F was identified as most economically promising for direct contact waste heat recuperation and hot process water delivery.

  12. Thermal and hydraulic performance tests of a sieve-tray direct-contact heat exchanger vaporizing pure and mixed-hydrocarbon Rankine-cycle working fluids

    SciTech Connect

    Mines, G.L.; Demuth, O.J.; Wiggins, D.J.

    1983-08-01

    Experiments investigating a sieve-tray direct-contact heat exchanger were conducted at the Raft River Geothermal Test Site in southeastern Idaho using the 60-kW Mobile Heat Cycle Research Facility operating in the thermal loop mode (without a turbine). Isobutane, propane, and several hydrocarbon mixtures were heated and boiled in the direct-contact column, which is approx. 12 in. in diameter and 19-1/2 ft. high, using the energy from a 280/sup 0/F geothermal resource. Using pure fluids, isobutane or propane, the column operated much as intended, with 17 trays used for preheating and one or two accomplishing the boiling. For the pure fluids, individual tray efficiencies were found to be 70% or higher for preheating, and close to 100% for boiling; column pinch points were projected to be well under 1/sup 0/F with some runs reaching values as low as approx. 0.02/sup 0/F. Maximum geofluid throughputs for the isobutane tests corresponded roughly to the terminal rise velocity of a 1/32 in. working fluid droplet in geofluid. Boiling was found to occur in as many as 12 trays for the mixtures having the highest concentrations of the minor component, with overall efficiencies in the boiling section estimated on the order of 25 or 30%. Preheating tray efficiencies appeared to be fairly independent of working fluid, with pinch points ranging from as low as approx. 0.03/sup 0/F for a 0.95 isobutane/0.05 hexane mixture to approx. 2.3/sup 0/F for a 0.85 isobutane/0.05 hexane mixture. Column operation was noticeably less stable for the mixtures than for the pure fluids, with maximum throughputs dropping to as low as 40 to 50% of those for the pure fluids.

  13. Film boiling of magnetic nanofluids (MNFs) over a vertical plate in presence of a uniform variable-directional magnetic field

    NASA Astrophysics Data System (ADS)

    Malvandi, Amir

    2016-05-01

    External magnetic fields are able to tune the thermophysical properties of magnetic nanofluids (MNFs) and control the flow and heat transfer rate. Orientation and intensity of the external magnetic field would influence the thermal conductivity of MNFs and makes it anisotropic. The motivation behind this study is the need to examine the effects of anisotropic behavior of thermal conductivity on flow field and heat transfer characteristics at film boiling of MNFs over a vertical plate in the presence of a uniform variable-directional magnetic field. The modified Buongiorno model is employed for modeling the nanofluids to observe the effects of nanoparticle migration. The results have been obtained for different parameters, including Brownian motion to thermophoretic diffusion NBT, saturation nanoparticle concentration ϕsat, Hartmann number Ha, magnetic field angle α, and normal temperature difference γ = (Tw -Tsat) /Tw . A closed form expression for the distribution of nanoparticle volume fraction has been obtained and the effects of pertinent parameters on heat transfer rate have been investigated. It has been shown that the heat transfer rate is improved further when an external magnetic field exerts in the direction of the temperature gradient.

  14. Renewable Water: Direct Contact Membrane Distillation Coupled With Solar Ponds

    NASA Astrophysics Data System (ADS)

    Suarez, F. I.; Tyler, S. W.; Childress, A. E.

    2010-12-01

    The exponential population growth and the accelerated increase in the standard of living have increased significantly the global consumption of two precious resources: water and energy. These resources are intrinsically linked and are required to allow a high quality of human life. With sufficient energy, water may be harvested from aquifers, treated for potable reuse, or desalinated from brackish and seawater supplies. Even though the costs of desalination have declined significantly, traditional desalination systems still require large quantities of energy, typically from fossil fuels that will not allow these systems to produce water in a sustainable way. Recent advances in direct contact membrane distillation can take advantage of low-quality or renewable heat to desalinate brackish water, seawater or wastewater. Direct contact membrane distillation operates at low pressures and can use small temperature differences between the feed and permeate water to achieve a significant freshwater production. Therefore, a much broader selection of energy sources can be considered to drive thermal desalination. A promising method for providing renewable source of heat for direct contact membrane distillation is a solar pond, which is an artificially stratified water body that captures solar radiation and stores it as thermal energy at the bottom of the pond. In this work, a direct contact membrane distillation/solar pond coupled system is modeled and tested using a laboratory-scale system. Freshwater production rates on the order of 2 L day-1 per m2 of solar pond (1 L hr-1 per m2 of membrane area) can easily be achieved with minimal operating costs and under low pressures. While these rates are modest, they are six times larger than those produced by other solar pond-powered desalination systems - and they are likely to be increased if heat losses in the laboratory-scale system are reduced. Even more, this system operates at much lower costs than traditional desalination

  15. Geothermal materials survey : Arkansas Power and Light Development and Demonstration Project. 100kW power system using direct contact heat exchangers, El Dorado, Arkansas

    SciTech Connect

    Ellis, P.F. II

    1980-07-22

    The 100 kW plant is a direct contact boiling/direct contact condensing binary system using isopentane as the working fluid. Treated waste geothermal brine from the Great Lakes Chemical Co. (GLC) bromine recovery operation is the heat source. Brine is taken from the GLC Treated Brine Line at 205 to 210/sup 0/F and supplied to the pilot plant via the APL Brine Inlet Line. The brine enters the direct contact boiler (DCB) and vaporizes isopentane. The cooled brine is discharged into the reinjection pond at 135 to 155/sup 0/F. The brine flow rate is 45,655 to 87,030 lb(m)/hr (pounds mass per hour). The chemistry of the brine is discussed. The objectives here are to: (1) evaluate present pilot plant materials selections, (2) identify potential materials problems, and (3) recommend alternate materials for use in future systems. (MHR)

  16. Non-invasive diagnosis of cutaneous leishmaniasis by the direct boil loop-mediated isothermal amplification method and MinION™ nanopore sequencing.

    PubMed

    Imai, Kazuo; Tarumoto, Norihito; Amo, Kiyoko; Takahashi, Makoto; Sakamoto, Naoya; Kosaka, Atsushi; Kato, Yasuyuki; Mikita, Kei; Sakai, Jun; Murakami, Takashi; Suzuki, Yutaka; Maesaki, Shigefumi; Maeda, Takuya

    2017-03-11

    Cutaneous leishmaniasis (CL) is gaining attention as a public health problem. We present two cases of CL imported from Syria and Venezuela in Japan. We diagnosed them as CL non-invasively by the direct boil loop-mediated isothermal amplification method and an innovative sequencing method using the MinION™ sequencer. This report demonstrates that our procedure could be useful for the diagnosis of CL in both clinical and epidemiological settings.

  17. Frequency and direction of competitive anger in contact sports.

    PubMed

    Robazza, B; Bertollo, M; Bortoli, L

    2006-09-01

    The purpose of the present study was to investigate whether athletes involved in physical contact sports may interpret their feelings of anger as facilitative of performance, and to examine differences in the interpretation of anger as a function of the type of sport (team vs individual) or the competitive skill level (high vs low). A modified version of the State-Trait Anger Expression Inventory was administered to 100 Italian adult male athletes practicing rugby or individual combat sports (judo, freestyle wrestling, or Greco-Roman wrestling). The questionnaire was intended to measure the frequency and the direction (i.e., the facilitative-debilitative interpretation) of competitive anger. Many athletes engaged in contact sports tended interpret their competitive anger as facilitative of performance rather than debilitative. The type of sport and the athlete's standard level can mediate the individual's interpretation of the effects of anger symptoms upon performance. Competitors can interpret their anger as helpful to energize behavior and channel physical and mental resources for skill execution. Practitioners should assist athletes in gaining control over anger rather than attempting to suppress it.

  18. Thermal performance of direct contact heat exchangers for mixed hydrocarbons

    SciTech Connect

    Sharpe, L. Jr.; Coswami, D.Y.; Demuth, O.J.; Mines, G.

    1985-01-01

    This paper describes a physical and a mathematical model for evaluating the tray efficiencies for a direct contact heat exchanger (DCHX). The model is then used to determine the efficiencies for tests conducted on a 60kW sieve tray DCHX as heat is transferred from a geofluid (brine) to a working fluid (mixed hydrocarbons). It is assumed that there are three distinct regions in the column based on the state of the working fluid, as follows: Region I - Preheating with no vaporization; Region II - Preheating with moderate vaporization; and Region III - Major vaporization. The boundaries of these regions can be determined from the experimental data. In the model, mass balance and energy balance is written for a tray ''N'' in each of these regions. Finally, the ''tray efficiency'' or ''heat transfer'' effectiveness of the tray is calculated based on the definition that it is the ratio of the actual heat transfer to the maximum possible, thermodynamically.

  19. Direct contact droplet heat exchangers for thermal management in space

    NASA Technical Reports Server (NTRS)

    Bruckner, A. P.; Hertzberg, A.

    1982-01-01

    A liquid droplet heat exchanger for space applications is described which transfers heat between a gas and a liquid metal dispersed into droplets. The ability of the droplet heat exchanger to transfer heat between two media in direct contact over a wide temperature range circumvents many of the material limitations of conventional tube-type heat exchangers and does away with complicated plumbing systems and their tendency toward single point failure. Droplet heat exchangers offer large surface to volume ratios in a compact geometry, very low gas pressure drop, and high effectiveness. The application of the droplet heat exchanger in a high temperature Brayton cycle is discussed to illustrate its performance and operational characteristics.

  20. Countercurrent direct contact heat exchange process and system

    DOEpatents

    Wahl, III, Edward F.; Boucher, Frederic B.

    1979-01-01

    Recovery of energy from geothermal brines and other hot water sources by direct contact heat exchange with a working fluid, such as a hydrocarbon working fluid, e.g. isobutane. The process and system consists of a plurality of stages, each stage including mixing and settling units. In the first stage, hot brine and arm working fluid are intimately mixed and passed into a settler wherein the brine settles to the bottom of the settler and the hot working fluid rises to the top. The hot working fluid is passed to a heat engine or turbine to produce work and the working fluid is then recycled back into the system. The system is comprised of a series of stages each containing a settler and mixer, and wherein the working fluid and the brine flow in a countercurrent manner through the stages to recover the heat from the brine in increments and raise the temperature of the working fluid in increments.

  1. Treatment of radioactive wastewater using direct contact membrane distillation.

    PubMed

    Liu, Haiyang; Wang, Jianlong

    2013-10-15

    Direct contact membrane distillation (DCMD) was used to treat low level radioactive wastewater (LLRW). The dusty gas model (DGM) was used to analyze the mass transfer mechanism and calculate the permeate flux. The operating parameters such as feed temperature, feed velocity and feed concentration were studied. The experimental results showed that DCMD process can separate almost all Cs(+), Sr(2+) and Co(2+) from wastewater. The permeate flux decreased linearly when NaNO3 concentration increased from 1.0 to 200 g/L. The permeate flux remained about 60% of its initial flux even when NaNO3 concentration in feed solution was as high as 200 g/L. The dusty gas model can be successfully applied to estimate the mass transfer, and the experimental permeate flux values fitted well with that calculated by DGM. DCMD is a promising separation process for low level radioactive wastewater treatment.

  2. Direct Contact Membrane Distillation of Dairy Process Streams

    PubMed Central

    Hausmann, Angela; Sanciolo, Peter; Vasiljevic, Todor; Ponnampalam, Elankovan; Quispe-Chavez, Nohemi; Weeks, Mike; Duke, Mikel

    2011-01-01

    Membrane distillation (MD) was applied for the concentration of a range of dairy streams, such as whole milk, skim milk and whey. MD of a pure lactose solution was also investigated. Direct contact MD (DCMD) mode experiments were carried out in continuous concentration mode, keeping the warm feed/retentate and cold permeate stream temperatures at 54 °C and 5 °C respectively. Performance in terms of flux and retention was assessed. The flux was found to decrease with an increase of dry-matter concentration in the feed. Retention of dissolved solids was found to be close to 100% and independent of the dry-matter concentration in the feed. Fourier Transform Infrared Spectroscopy (FTIR) of the fouled membranes confirms organics being present in the fouling layer. PMID:24957495

  3. Direct contact membrane distillation of sugar aqueous solutions

    SciTech Connect

    Izquierdo-Gil, M.A.; Garcia-Payo, M.C.; Fernandez-Pineda, C.

    1999-06-01

    Results are given from direct contact membrane distillation, using tangential flows to the membrane, with sugar aqueous solutions. Several effects on the distillation process are examined: flow rate through the cell, nature of the feed solutions, initial concentrations of the feed solutions, average temperature, and temperature difference. On the basis of enthalpy flux conservation in the different regions, various systems of equations are proposed for the estimation of the interfacial temperatures. Based on the known temperatures of the liquid-vapor interfaces, the experimental distillate fluxes for several sets are fitted to the gas stagnant film diffusion model to obtain the effective diffusion coefficients of the water vapor-air mixture, D{sub ef}, and the results are analyzed.

  4. A review of micro-contact physics, materials, and failure mechanisms in direct-contact RF MEMS switches

    NASA Astrophysics Data System (ADS)

    Basu, A.; Adams, G. G.; McGruer, N. E.

    2016-10-01

    Direct contact, ohmic MEMS switches for RF applications have several advantages over other conventional switching devices. Advantages include lower insertion loss, higher isolation, and better switching figure-of-merit (cut-off frequency). The most important aspect of a direct-contact RF MEMS switch is the metal microcontact which can dictate the lifetime and reliability of the switch. Therefore, an understanding of contact reliability is essential for developing robust MEMS switches. This paper discusses and reviews the most important work done over the past couple of decades toward understanding ohmic micro-contacts. We initially discuss the contact mechanics and multi-physics models for studying Hertzian and multi-asperity contacts. We follow this with a discussion on models and experiments for studying adhesion. We then discuss experimental setups and the development of contact test stations by various groups for accelerated testing of microcontacts, as well as for analysis of contact reliability issues. Subsequently, we analyze a number of material transfer mechanisms in microcontacts under hot and cold switching conditions. We finally review the material properties that can help determine the selection of contact materials. A trade-off between contact resistance and high reliability is almost always necessary during selection of contact material; this paper discusses how the choice of materials can help address such trade-offs.

  5. Studying Positive and Negative Direct and Extended Contact: Complementing Self-Reports With Social Network Analysis.

    PubMed

    Wölfer, Ralf; Jaspers, Eva; Blaylock, Danielle; Wigoder, Clarissa; Hughes, Joanne; Hewstone, Miles

    2017-07-01

    Traditionally, studies of intergroup contact have primarily relied on self-reports, which constitute a valid method for studying intergroup contact, but has limitations, especially if researchers are interested in negative or extended contact. In three studies, we apply social network analyses to generate alternative contact parameters. Studies 1 and 2 examine self-reported and network-based parameters of positive and negative contact using cross-sectional datasets ( N = 291, N = 258), indicating that both methods help explain intergroup relations. Study 3 examines positive and negative direct and extended contact using the previously validated network-based contact parameters in a large-scale, international, and longitudinal dataset ( N = 12,988), demonstrating that positive and negative direct and extended contact all uniquely predict intergroup relations (i.e., intergroup attitudes and future outgroup contact). Findings highlight the value of social network analysis for examining the full complexity of contact including positive and negative forms of direct and extended contact.

  6. 21 CFR 882.1570 - Powered direct-contact temperature measurement device.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Powered direct-contact temperature measurement....1570 Powered direct-contact temperature measurement device. (a) Identification. A powered direct-contact temperature measurement device is a device which contains a power source and is used to measure...

  7. 21 CFR 882.1570 - Powered direct-contact temperature measurement device.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Powered direct-contact temperature measurement....1570 Powered direct-contact temperature measurement device. (a) Identification. A powered direct-contact temperature measurement device is a device which contains a power source and is used to measure...

  8. 21 CFR 882.1570 - Powered direct-contact temperature measurement device.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Powered direct-contact temperature measurement....1570 Powered direct-contact temperature measurement device. (a) Identification. A powered direct-contact temperature measurement device is a device which contains a power source and is used to measure...

  9. 21 CFR 882.1570 - Powered direct-contact temperature measurement device.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Powered direct-contact temperature measurement....1570 Powered direct-contact temperature measurement device. (a) Identification. A powered direct-contact temperature measurement device is a device which contains a power source and is used to measure...

  10. 21 CFR 882.1570 - Powered direct-contact temperature measurement device.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Powered direct-contact temperature measurement....1570 Powered direct-contact temperature measurement device. (a) Identification. A powered direct-contact temperature measurement device is a device which contains a power source and is used to measure...

  11. BOILING REACTORS

    DOEpatents

    Untermyer, S.

    1962-04-10

    A boiling reactor having a reactivity which is reduced by an increase in the volume of vaporized coolant therein is described. In this system unvaporized liquid coolant is extracted from the reactor, heat is extracted therefrom, and it is returned to the reactor as sub-cooled liquid coolant. This reduces a portion of the coolant which includes vaporized coolant within the core assembly thereby enhancing the power output of the assembly and rendering the reactor substantially self-regulating. (AEC)

  12. Numerical investigations on unstable direct contact condensation of cryogenic fluids

    NASA Astrophysics Data System (ADS)

    Jayachandran, K. N.; Arnab, Roy; Parthasarathi, Ghosh

    2017-02-01

    A typical problem of Direct Contact Condensation (DCC) occurs at the liquid oxygen (LOX) booster turbopump exit of oxidiser rich staged combustion cycle based semi-cryogenic rocket engines, where the hot gas mixture (predominantly oxygen and small amounts of combustion products) that runs the turbine mixes with LOX from the pump exit. This complex multiphase phenomena leads to the formation of solid CO2 & H2O, which is undesirable for the functioning of the main LOX turbopump. As a starting point for solving this complex problem, in this study, the hot gas mixture is taken as pure oxygen and hence, DCC of pure oxygen vapour jets in subcooled liquid oxygen is simulated using the commercial CFD package ANSYS CFX®. A two fluid model along with the thermal phase change model is employed for capturing the heat and mass transfer effects. The study mainly focuses on the subsonic DCC bubbling regime, which is reported as unstable with bubble formation, elongation, necking and collapsing effects. The heat transfer coefficients over a period of time have been computed and the various stages of bubbling have been analysed with the help of vapour volume fraction and pressure profiles. The results obtained for DCC of oxygen vapour-liquid mixtures is in qualitative agreement with the experimental results on DCC of steam-water mixtures.

  13. State of technology of direct contact heat exchanging

    SciTech Connect

    Vallario, R.W.; DeBellis, D.E.

    1984-05-01

    Specific objectives of this study were to assess the state of technology development and to identify and evaluate the constraints to wider use of direct contact heat exchanger (DCHE) technology in the U.S. The scope of this study is relatively broad; it includes many types of generic systems and end-use applications, both current and future. Domestic and foreign experience with DCHE technology are compared, although the primary focus is on domestic experience. Twenty-two distinct applications of DCHE technology were identified in this study and are examined in this report. The general format is to describe each system, explore its potential applications, discuss current and past research activities and identify major implementation barriers. Finally, as a result of discussions with principal users of DCHE systems and with other knowledgeable sources, generic and specific R and D needs to overcome specific implementation barriers have been identified. The following list of DCHE systems/concepts has been classified into four major end-uses; there is also a category for specialized (other) applications.

  14. Directional close-contact melting in glacier ice

    NASA Astrophysics Data System (ADS)

    Kowalski, Julia; Schüller, Kai

    2015-04-01

    The Saturnian moon Enceladus shows incidence of liquid water underneath a thick ice sheet cover and is thought to be a potential candidate for extraterrestrial life. However, direct exploration of these subglacial aquatic ecosystems is very challenging. Within the scope of the joint research project 'Enceladus Explorer' (EnEx) (consisting of FH Aachen, RWTH Aachen, Bergische Universität Wuppertal, Universität Bremen, TU Braunschweig und Bundeswehr Universität München), initiated by the German Space Agency, a maneuverable close-contact melting probe has been developed. The force-regulated and heater-controlled probe is able to melt against gravity or even on a curved trajectory. Hence, it offers additional degrees of freedom in its melting motion, e.g. for target oriented melting or obstacle avoidance strategies. General feasibility of the concept has been demonstrated in various field tests. However, in order to optimize its design and to adopt it to extraterrestrial missions a simulation model is needed, capable of determining melting velocity and efficiency at given environmental conditions and system configurations. Within this contribution, the physical situation is abstracted into a quasi-stationary mathematical model description, and a numerical solution strategy is developed to compute melting velocity and temperature distribution within the probe and the surrounding ice. We present an inverse solution approach, in which a background velocity field of the ice mimics the melting velocity. The fundamental balance laws are solved with the corresponding melting rate. Following Newton's laws, the resulting force acting on the probe has to balance the contact force exerted by the probe and can hence be used for convergence. We present both, analytical results to a simplified head geometry, as well as results from a simulation model implemented into the open source software Elmer for arbitrary head geometries. The latter can deal with the full 3d situation

  15. Odor Absorbing Hydrocolloid Dressings for Direct Wound Contact.

    PubMed

    Lipman, Roger D A; van Bavel, Davy

    2007-05-01

    Patients in institutional settings, such as hospitals and nursing homes, often have or acquire chronic wounds such as those resulting from venous insufficiency and pressure ulcers-these wounds can possess a very offensive odor. 1 The most direct way of avoiding or eliminating wound odor is to prevent or eradicate the infection responsible for it.Topical antibiotics, such as metronidazole gel (0.8 w/v) have proved to be quite effective, but can generate resistant organisms. Further, the action of metronidazole can be sluggish; often several days are needed for any infection to be resolved, and meanwhile the odor is still being generated.Thus, in practice, other methods such as charcoal-based dressings are often used with or with-out concomitant antibiotic therapy. Odor absorbing dressings have been marketed in one form or other for many years. During the past decades a number of charcoal based dressings have been introduced into the market. Some of the more current products are Actisorb ® Silver (Johnson & Johnson Medical Ltd, Gargrave, UK), CarboFlex ® (ConvaTec, Princeton, NJ), Carbonet ® (Smith and Nephew Abstract: Charcoal based odor-absorbing dressings for management of odoriferous chronic wounds have been marketed for many years. However, the presence of wound serum deactivates the charcoal and inhibits the adsorption of odor molecules. Charcoal dressings also gen-erally need adjunct fixation to hold them in place. A new series of hydrocolloid adhesives based on cyclodextrins has been developed to provide an alternative technology for the adsorption of chronic wound odors. Dressings incorporating this technology are suitable for direct wound contact. In presence of serum, superior odor absorption with these new materials in comparison with charcoal dressings has been demonstrated in vitro. These new dressings have significant fluid absorption potential, are self-adhesive, and require no additional fixa-tion. Some of the factors affecting performance of

  16. Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability

    DOE PAGES

    Li, Q.; Kang, Q. J.; Francois, M. M.; ...

    2015-03-03

    A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach (Li et al., 2013). The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid–vapor phase change. Using the model, the liquid–vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic featuresmore » and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Moreover, the effects of the heating surface wettability on boiling heat transfer are investigated. It is found that an increase in contact angle promotes the onset of boiling but reduces the critical heat flux, and makes the boiling process enter into the film boiling regime at a lower wall superheat, which is consistent with the findings from experimental studies.« less

  17. Lattice Boltzmann modeling of boiling heat transfer: The boiling curve and the effects of wettability

    SciTech Connect

    Li, Q.; Kang, Q. J.; Francois, M. M.; He, Y. L.; Luo, K. H.

    2015-03-03

    A hybrid thermal lattice Boltzmann (LB) model is presented to simulate thermal multiphase flows with phase change based on an improved pseudopotential LB approach (Li et al., 2013). The present model does not suffer from the spurious term caused by the forcing-term effect, which was encountered in some previous thermal LB models for liquid–vapor phase change. Using the model, the liquid–vapor boiling process is simulated. The boiling curve together with the three boiling stages (nucleate boiling, transition boiling, and film boiling) is numerically reproduced in the LB community for the first time. The numerical results show that the basic features and the fundamental characteristics of boiling heat transfer are well captured, such as the severe fluctuation of transient heat flux in the transition boiling and the feature that the maximum heat transfer coefficient lies at a lower wall superheat than that of the maximum heat flux. Moreover, the effects of the heating surface wettability on boiling heat transfer are investigated. It is found that an increase in contact angle promotes the onset of boiling but reduces the critical heat flux, and makes the boiling process enter into the film boiling regime at a lower wall superheat, which is consistent with the findings from experimental studies.

  18. Direct determination of three-phase contact line properties on nearly molecular scale.

    PubMed

    Winkler, P M; McGraw, R L; Bauer, P S; Rentenberger, C; Wagner, P E

    2016-05-17

    Wetting phenomena in multi-phase systems govern the shape of the contact line which separates the different phases. For liquids in contact with solid surfaces wetting is typically described in terms of contact angle. While in macroscopic systems the contact angle can be determined experimentally, on the molecular scale contact angles are hardly accessible. Here we report the first direct experimental determination of contact angles as well as contact line curvature on a scale of the order of 1nm. For water nucleating heterogeneously on Ag nanoparticles we find contact angles around 15 degrees compared to 90 degrees for the corresponding macroscopically measured equilibrium angle. The obtained microscopic contact angles can be attributed to negative line tension in the order of -10(-10) J/m that becomes increasingly dominant with increasing curvature of the contact line. These results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.

  19. Direct determination of three-phase contact line properties on nearly molecular scale

    NASA Astrophysics Data System (ADS)

    Winkler, P. M.; McGraw, R. L.; Bauer, P. S.; Rentenberger, C.; Wagner, P. E.

    2016-05-01

    Wetting phenomena in multi-phase systems govern the shape of the contact line which separates the different phases. For liquids in contact with solid surfaces wetting is typically described in terms of contact angle. While in macroscopic systems the contact angle can be determined experimentally, on the molecular scale contact angles are hardly accessible. Here we report the first direct experimental determination of contact angles as well as contact line curvature on a scale of the order of 1nm. For water nucleating heterogeneously on Ag nanoparticles we find contact angles around 15 degrees compared to 90 degrees for the corresponding macroscopically measured equilibrium angle. The obtained microscopic contact angles can be attributed to negative line tension in the order of ‑10‑10 J/m that becomes increasingly dominant with increasing curvature of the contact line. These results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.

  20. Direct determination of three-phase contact line properties on nearly molecular scale

    PubMed Central

    Winkler, P. M.; McGraw, R. L.; Bauer, P. S.; Rentenberger, C.; Wagner, P. E.

    2016-01-01

    Wetting phenomena in multi-phase systems govern the shape of the contact line which separates the different phases. For liquids in contact with solid surfaces wetting is typically described in terms of contact angle. While in macroscopic systems the contact angle can be determined experimentally, on the molecular scale contact angles are hardly accessible. Here we report the first direct experimental determination of contact angles as well as contact line curvature on a scale of the order of 1nm. For water nucleating heterogeneously on Ag nanoparticles we find contact angles around 15 degrees compared to 90 degrees for the corresponding macroscopically measured equilibrium angle. The obtained microscopic contact angles can be attributed to negative line tension in the order of −10−10 J/m that becomes increasingly dominant with increasing curvature of the contact line. These results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects. PMID:27183880

  1. A review of film boiling at cryogenic temperatures.

    NASA Technical Reports Server (NTRS)

    Hsu, Y. Y.

    1972-01-01

    Film boiling occurs in the quenching of metals, the chilling of biological species, the regenerative cooling of rockets, and the cooling down of a cryogenic fuel tank. Occasionally film boiling is also found in a nuclear reactor or in a cryomagnet. Aspects of film boiling involving an unconstrained liquid mass are considered, giving attention to the evaporation time, the Leidenfrost temperature, solid-liquid contacts, the thermal properties of the solid, effects of coating or scale, wettability, the metastable condition, and the velocity effect on drops. Developments discussed with regard to pool boiling are related to vertical surfaces, film boiling from horizontal surfaces, film boiling from a horizontal cylinder, film boiling from a sphere, and film boiling of helium. Processes of film boiling in a channel are also analyzed.

  2. Liquid metal boiling inception

    NASA Technical Reports Server (NTRS)

    Sabin, C. M.; Poppendiek, H. F.; Mouritzen, G.; Meckel, P. T.; Cloakey, J. E.

    1972-01-01

    An experimental study of the inception of boiling in potassium in forced convection is reported. The boiler consisted of a 0.19-inch inside diameter, niobium-1% zirconium boiler tube approximately six feet long. Heating was accomplished by direct electrical tube wall conduction. Experiments were performed with both all-liquid fill and two-phase fill startup sequences and with a range of flow rates, saturation temperatures, inert gas levels, and fill liquid temperatures. Superheat of the liquid above the equilibrium saturation temperature was observed in all the experiments. Incipient boiling liquid superheat ranged from a few degrees to several hundred. Comparisons of these data with other data and with several analytical treatments are presented.

  3. Direct and airborne contact dermatitis in a beekeeper from the Małopolska region.

    PubMed

    Basista, Katarzyna

    2012-09-01

    The paper describes an atypical case of simultaneous airborne and direct contact dermatitis in a beekeeper from the Małopolska region. This is the third such case described in a beekeeper in the world and the first in Poland. I suggest that propolis should be regarded as both a direct and airborne contact allergen in beekeepers.

  4. Development of a direct contact ice storage system

    SciTech Connect

    Poirier, R.

    1989-03-01

    The program described involves the design, construction, and performance testing of a Direct Freeze Thermal Energy Storage System. Task 1 (Design) has been completed; and Task 2 (construction) is in progress, with equipment procurements presently underway. Once constructed, the system will undergo extensive laboratory performance testing and analysis, followed by an assessment of the system`s cost effectiveness. This study will advance the understanding and development of the direct freeze concept, which offers inherent benefits for thermal energy storage.

  5. Direct and extended intergenerational contact and young people's attitudes towards older adults.

    PubMed

    Drury, Lisbeth; Hutchison, Paul; Abrams, Dominic

    2016-09-01

    Research suggests that positive intergenerational contact can improve young people's attitudes towards older adults. However, today's age-segregated society may not provide ample opportunities for positive contact between younger and older adults to occur on a regular basis. In three studies, we investigated whether the positive attitudinal outcomes associated with direct contact might also stem from a more indirect form of intergenerational relationship: extended contact. In Study 1 (N = 70), extended contact was associated with more positive attitudes towards older adults even when controlling for direct intergenerational contact (contact frequency and contact quality). In Study 2 (N = 110), the positive effects of direct and extended contact on young people's age-related attitudes were mediated by reductions in intergroup anxiety and ageing anxiety. The mediational effects of intergroup anxiety were replicated in Study 3 (N = 95) and ingroup norms additionally emerged as a mediator of the positive effects of extended contact on young people's attitudes towards older adults. Discussion focuses on the implications for strategies aimed at tackling ageism.

  6. The Potential Role of Direct and Indirect Contacts on Infection Spread in Dairy Farm Networks

    PubMed Central

    Natalini, Silvano; Zarenghi, Luca; Ricchi, Matteo; Bolzoni, Luca

    2017-01-01

    Animals’ exchanges are considered the most effective route of between-farm infectious disease transmission. However, despite being often overlooked, the infection spread due to contaminated equipment, vehicles, or personnel proved to be important for several livestock epidemics. This study investigated the role of indirect contacts in a potential infection spread in the dairy farm network of the Province of Parma (Northern Italy). We built between-farm contact networks using data on cattle exchange (direct contacts), and on-farm visits by veterinarians (indirect contacts). We compared the features of the contact structures by using measures on static and temporal networks. We assessed the disease spreading potential of the direct and indirect network structures in the farm system by using data on the infection state of farms by paratuberculosis. Direct and indirect networks showed non-trivial differences with respect to connectivity, contact distribution, and super-spreaders identification. Furthermore, our analyses on paratuberculosis data suggested that the contributions of direct and indirect contacts on diseases spread are apparent at different spatial scales. Our results highlighted the potential role of indirect contacts in between-farm disease spread and underlined the need for a deeper understanding of these contacts to develop better strategies for prevention of livestock epidemics. PMID:28125610

  7. The Potential Role of Direct and Indirect Contacts on Infection Spread in Dairy Farm Networks.

    PubMed

    Rossi, Gianluigi; De Leo, Giulio A; Pongolini, Stefano; Natalini, Silvano; Zarenghi, Luca; Ricchi, Matteo; Bolzoni, Luca

    2017-01-01

    Animals' exchanges are considered the most effective route of between-farm infectious disease transmission. However, despite being often overlooked, the infection spread due to contaminated equipment, vehicles, or personnel proved to be important for several livestock epidemics. This study investigated the role of indirect contacts in a potential infection spread in the dairy farm network of the Province of Parma (Northern Italy). We built between-farm contact networks using data on cattle exchange (direct contacts), and on-farm visits by veterinarians (indirect contacts). We compared the features of the contact structures by using measures on static and temporal networks. We assessed the disease spreading potential of the direct and indirect network structures in the farm system by using data on the infection state of farms by paratuberculosis. Direct and indirect networks showed non-trivial differences with respect to connectivity, contact distribution, and super-spreaders identification. Furthermore, our analyses on paratuberculosis data suggested that the contributions of direct and indirect contacts on diseases spread are apparent at different spatial scales. Our results highlighted the potential role of indirect contacts in between-farm disease spread and underlined the need for a deeper understanding of these contacts to develop better strategies for prevention of livestock epidemics.

  8. Bacteria-induced hatching of Trichuris muris eggs occurs without direct contact between eggs and bacteria.

    PubMed

    Koyama, Koichi

    2016-01-01

    Using three isolates of the murine parasitic nematode Trichuris muris, E, E/J (the E isolate maintained in Japan), and S, I have previously demonstrated that when the embryonated eggs of the E/J and E isolates are incubated with the intestinal bacteria Escherichia coli and Staphylococcus aureus, they are induced to hatch in vitro. However, the eggs of the S isolate are unresponsive to these bacteria. In the present study, I investigated whether direct contact between the embryonated eggs of the E/J and E isolates and bacteria is required to induce their hatching. To do so, a new co-culture system for eggs and bacteria (E. coli or S. aureus) was developed to block any direct contact between the eggs and the bacteria. In the hatching experiment using the new system, when direct contact between the eggs and bacteria was completely prevented, the eggs still hatched. However, the peak levels of hatching without direct contact were about 20 % lower than those with direct contact, and peak hatching occurred later without direct contact. This evidence suggests that hatching occurs without direct contact between the eggs and bacteria, and that unidentified material derived from active bacteria induces the hatching of embryonated eggs of the E/J and E isolates of T. muris in vitro.

  9. An Idealized Direct-Contact Biomass Pyrolysis Reactor Model

    NASA Technical Reports Server (NTRS)

    Miller, R. S.; Bellan, J.

    1996-01-01

    A numerical study is performed in order to assess the performance of biomass pyrolysis reactors which utilize direct particle-wall thermal conduction heating. An idealized reactor configuration consisting of a flat-plate turbulent boundary layer flow with particle convection along the heated wall and incorporating particle re-entrainment is considered.

  10. An Idealized Direct-Contact Biomass Pyrolysis Reactor Model

    NASA Technical Reports Server (NTRS)

    Miller, R. S.; Bellan, J.

    1996-01-01

    A numerical study is performed in order to assess the performance of biomass pyrolysis reactors which utilize direct particle-wall thermal conduction heating. An idealized reactor configuration consisting of a flat-plate turbulent boundary layer flow with particle convection along the heated wall and incorporating particle re-entrainment is considered.

  11. Contact Inhibition of Locomotion in vivo controls neural crest directional migration

    PubMed Central

    Carmona-Fontaine, Carlos; Matthews, Helen K.; Kuriyama, Sei; Moreno, Mauricio; Dunn, Graham A.; Parsons, Maddy; Stern, Claudio D.; Mayor, Roberto

    2008-01-01

    Contact Inhibition of Locomotion was discovered by Abercrombie more than 50 years ago to describe the behaviour of fibroblast cells confronting each other in vitro, where they retract their protrusions and change direction upon contact1,2. Its failure was suggested to contribute to malignant invasion3-6. However, the molecular basis of Contact Inhibition of Locomotion and whether it also occurs in vivo are still unknown. Here we show that neural crest cells, a highly migratory and multipotent embryonic cell population, whose behaviour has been likened to malignant invasion6-8, exhibit Contact Inhibition of Locomotion both in vivo and in vitro, and that this accounts for their directional migration. When two migrating neural crest cells meet, they stop, collapse their protrusions and change direction. In contrast, when a neural crest cell meets another cell type, it fails to display Contact Inhibition of Locomotion; instead, it invades the other tissue, like metastatic cancer cells3,5,9. We show that inhibition of non-canonical Wnt signalling abolishes both Contact Inhibition of Locomotion and the directionality of neural crest migration. Wnt signalling members localise at the site of cell contact, leading to activation of RhoA in this region. These results provide the first example of Contact Inhibition of Locomotion in vivo, present an explanation for coherent directional migration of group of cells and establish a novel role for non-canonical Wnt signalling. PMID:19078960

  12. Contact inhibition of locomotion in vivo controls neural crest directional migration.

    PubMed

    Carmona-Fontaine, Carlos; Matthews, Helen K; Kuriyama, Sei; Moreno, Mauricio; Dunn, Graham A; Parsons, Maddy; Stern, Claudio D; Mayor, Roberto

    2008-12-18

    Contact inhibition of locomotion was discovered by Abercrombie more than 50 years ago and describes the behaviour of fibroblast cells confronting each other in vitro, where they retract their protrusions and change direction on contact. Its failure was suggested to contribute to malignant invasion. However, the molecular basis of contact inhibition of locomotion and whether it also occurs in vivo are still unknown. Here we show that neural crest cells, a highly migratory and multipotent embryonic cell population, whose behaviour has been likened to malignant invasion, demonstrate contact inhibition of locomotion both in vivo and in vitro, and that this accounts for their directional migration. When two migrating neural crest cells meet, they stop, collapse their protrusions and change direction. In contrast, when a neural crest cell meets another cell type, it fails to display contact inhibition of locomotion; instead, it invades the other tissue, in the same manner as metastatic cancer cells. We show that inhibition of non-canonical Wnt signalling abolishes both contact inhibition of locomotion and the directionality of neural crest migration. Wnt-signalling members localize at the site of cell contact, leading to activation of RhoA in this region. These results provide the first example of contact inhibition of locomotion in vivo, provide an explanation for coherent directional migration of groups of cells and establish a previously unknown role for non-canonical Wnt signalling.

  13. Mutual enhancement of differentiation of osteoblasts and osteocytes occurs through direct cell-cell contact.

    PubMed

    Fujita, Koji; Xing, Qian; Khosla, Sundeep; Monroe, David G

    2014-11-01

    There is increasing evidence that osteocytes regulate multiple aspects of bone remodeling through bi-directional communication with osteoblasts. This is potentially mediated through cell-cell contact via osteocytic dendritic processes, through the activity of secreted factors, or both. To test whether cell-cell contact affects gene expression patterns in osteoblasts and osteocytes, we used a co-culture system where calvarial osteoblasts and IDG-SW3 osteocytes were allowed to touch through a porous membrane, while still being physically separated to allow for phenotypic characterization. Osteoblast/osteocyte cell-contact resulted in up-regulation of osteoblast differentiation genes in the osteoblasts, when compared to wells where no cell contact was allowed. Examination of osteocyte gene expression when in direct contact with osteoblasts also revealed increased expression of osteocyte-specific genes. These data suggest that physical contact mutually enhances both the osteoblastic and osteocytic character of each respective cell type. Interestingly, Gja1 (a gap junction protein) was increased in the osteoblasts only when in direct contact with the osteocytes, suggesting that Gja1 may mediate some of the effects of direct cell contact. To test this hypothesis, we treated the direct contact system with the gap junction inhibitor 18-alpha-glycyrrhetinic acid and found that Bglap expression was significantly inhibited. This suggests that osteocytes may regulate late osteoblast differentiation at least in part through Gja1. Identification of the specific factors involved in the enhancement of differentiation of both osteoblasts and osteocytes when in direct contact will uncover new biology concerning how these bone cells communicate.

  14. Pool Boiling Experiment Has Successful Flights

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Pool Boiling Experiment (PBE) is designed to improve understanding of the fundamental mechanisms that constitute nucleate pool boiling. Nucleate pool boiling is a process wherein a stagnant pool of liquid is in contact with a surface that can supply heat to the liquid. If the liquid absorbs enough heat, a vapor bubble can be formed. This process occurs when a pot of water boils. On Earth, gravity tends to remove the vapor bubble from the heating surface because it is dominated by buoyant convection. In the orbiting space shuttle, however, buoyant convection has much less of an effect because the forces of gravity are very small. The Pool Boiling Experiment was initiated to provide insight into this nucleate boiling process, which has many Earthbound applications, such as steam-generation power plants, petroleum, and other chemical plants. Also, by using the test fluid R-113, the Pool Boiling Experiment can provide some basic understanding of the boiling behavior of cryogenic fluids without the large cost of an experiment using an actual cryogen.

  15. Pool Boiling Experiment Has Five Successful Flights

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Fran

    1997-01-01

    The Pool Boiling Experiment (PBE) is designed to improve understanding of the fundamental mechanisms that constitute nucleate pool boiling. Nucleate pool boiling is a process wherein a stagnant pool of liquid is in contact with a surface that can supply heat to the liquid. If the liquid absorbs enough heat, a vapor bubble can be formed. This process occurs when a pot of water boils. On Earth, gravity tends to remove the vapor bubble from the heating surface because it is dominated by buoyant convection. In the orbiting space shuttle, however, buoyant convection has much less of an effect because the forces of gravity are very small. The Pool Boiling Experiment was initiated to provide insight into this nucleate boiling process, which has many earthbound applications in steamgeneration power plants, petroleum plants, and other chemical plants. In addition, by using the test fluid R-113, the Pool Boiling Experiment can provide some basic understanding of the boiling behavior of cryogenic fluids without the large cost of an experiment using an actual cryogen.

  16. Direct contact as a moderator of extended contact effects: cross-sectional and longitudinal impact on outgroup attitudes, behavioral intentions, and attitude certainty.

    PubMed

    Christ, Oliver; Hewstone, Miles; Tausch, Nicole; Wagner, Ulrich; Voci, Alberto; Hughes, Joanne; Cairns, Ed

    2010-12-01

    Cross-group friendships (the most effective form of direct contact) and extended contact (i.e., knowing ingroup members who have outgroup friends) constitute two of the most important means of improving outgroup attitudes. Using cross-sectional and longitudinal samples from different intergroup contexts, this research demonstrates that extended contact is most effective when individuals live in segregated neighborhoods having only few, or no, direct friendships with outgroup members. Moreover, by including measures of attitudes and behavioral intentions the authors showed the broader impact of these forms of contact, and, by assessing attitude certainty as one dimension of attitude strength, they tested whether extended contact can lead not only to more positive but also to stronger outgroup orientations. Cross-sectional data showed that direct contact was more strongly related to attitude certainty than was extended contact, but longitudinal data showed both forms of contact affected attitude certainty in the long run.

  17. SUPERHEATING IN A BOILING WATER REACTOR

    DOEpatents

    Treshow, M.

    1960-05-31

    A boiling-water reactor is described in which the steam developed in the reactor is superheated in the reactor. This is accomplished by providing means for separating the steam from the water and passing the steam over a surface of the fissionable material which is not in contact with the water. Specifically water is boiled on the outside of tubular fuel elements and the steam is superheated on the inside of the fuel elements.

  18. Direct observation of frictional contacts: New insights for state-dependent properties

    USGS Publications Warehouse

    Dieterich, J.H.; Kilgore, B.D.

    1994-01-01

    Rocks and many other materials display a rather complicated, but characteristic, dependence of friction on sliding history. These effects are well-described by empirical rate- and state-dependent constitutive formulations which have been utilized for analysis of fault slip and earthquake processes. We present a procedure for direct quantitative microscopic observation of frictional contacts during slip. The observations reveal that frictional state dependence represents an increase of contact area with contact age. Transient changes of sliding resistance correlate with changes in contact area and arise from shifts of contact population age. Displacement-dependent replacement of contact populations is shown to cause the diagnostic evolution of friction over a characteristic sliding distance that occurs whenever slip begins or sliding conditions change. ?? 1994 Birkha??user Verlag.

  19. Direct determination of three-phase contact line properties on nearly molecular scale

    SciTech Connect

    Winkler, P. M.; McGraw, R. L.; Bauer, P. S.; Rentenberger, C.; Wagner, P. E.

    2016-05-17

    Wetting phenomena in multi-phase systems govern the shape of the contact line which separates the different phases. For liquids in contact with solid surfaces wetting is typically described in terms of contact angle. While in macroscopic systems the contact angle can be determined experimentally, on the molecular scale contact angles are hardly accessible. Here we report the first direct experimental determination of contact angles as well as contact line curvature on a scale of the order of 1nm. For water nucleating heterogeneously on Ag nanoparticles we find contact angles around 15 degrees compared to 90 degrees for the corresponding macroscopically measured equilibrium angle. The obtained microscopic contact angles can be attributed to negative line tension in the order of –10–10 J/m that becomes increasingly dominant with increasing curvature of the contact line. Furthermore, these results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.

  20. Direct determination of three-phase contact line properties on nearly molecular scale

    DOE PAGES

    Winkler, P. M.; McGraw, R. L.; Bauer, P. S.; ...

    2016-05-17

    Wetting phenomena in multi-phase systems govern the shape of the contact line which separates the different phases. For liquids in contact with solid surfaces wetting is typically described in terms of contact angle. While in macroscopic systems the contact angle can be determined experimentally, on the molecular scale contact angles are hardly accessible. Here we report the first direct experimental determination of contact angles as well as contact line curvature on a scale of the order of 1nm. For water nucleating heterogeneously on Ag nanoparticles we find contact angles around 15 degrees compared to 90 degrees for the corresponding macroscopicallymore » measured equilibrium angle. The obtained microscopic contact angles can be attributed to negative line tension in the order of –10–10 J/m that becomes increasingly dominant with increasing curvature of the contact line. Furthermore, these results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.« less

  1. Direct and indirect contacts between cattle farms in north-west England.

    PubMed

    Brennan, M L; Kemp, R; Christley, R M

    2008-05-15

    Little is known regarding the types and frequencies of contact that exist between farms and which of these may act as pathogen transmission routes; however it is likely that farms demonstrate considerable heterogeneity in such contacts. In this cross-sectional study, we explored the direct and indirect contact types and frequencies that exist between cattle farms within a region, focusing on potential routes of pathogen transmission. The owners/managers of 56 farms located in a 10 km by 10 km study area in north-west England were administered an interview-based questionnaire between June and September 2005. Information was obtained relating to contact types and frequencies, including those involving animal movements, equipment sharing between farms and any contractors or companies visiting the farms. The data was explored using hierarchical cluster analysis and network analysis. There was considerable variation between farms arising from different contact types. Some networks exhibited great connectivity, incorporating approximately 90% of the farms interviewed in a single component, whilst other networks were more fragmented, with multiple small components (sets of connected farms not linked with other farms). A range of factors influencing contact between farms were identified. For example, contiguous farms were more likely to be linked via other contacts, such as sharing of equipment and direct farm-to-farm animal movements (p<0.001 and p=0.02, respectively). The frequency of contacts was also investigated; it is likely that the amount of contact a farm receives from a company or contractor and whether or not biosecurity is performed after contact would impact on disease transmission potential. We found considerable heterogeneity in contact frequency and that many company and contractor personnel undertook little biosecurity. These findings lead to greater understanding of inter-farm contact and may aid development of appropriate biosecurity practices and

  2. Patterns of direct and indirect contact between cattle and badgers naturally infected with tuberculosis.

    PubMed

    Drewe, J A; O'Connor, H M; Weber, N; McDonald, R A; Delahay, R J

    2013-07-01

    Tuberculosis (TB) due to infection with Mycobacterium bovis is transmitted between cattle and badgers (Meles meles) in the UK and Ireland but it is unclear where or when transmission occurs. We investigated direct and indirect interactions between badgers and cattle using automated proximity loggers on animals and at badger latrines located on pasture, in an area of south-west England with a high-density badger population. Direct contacts (interactions within 1.4 m) between badgers and cattle at pasture were very rare (four out of >500000 recorded animal-to-animal contacts) despite ample opportunity for interactions to occur. Indirect interactions (visits to badger latrines by badgers and cattle) were two orders of magnitude more frequent than direct contacts: 400 visits by badgers and 1700 visits by cattle were recorded. This suggests that indirect contacts might be more important than direct contacts in terms of disease transmission at pasture. The TB infection status of individual badgers (ascribed with 93% accuracy using three diagnostic tests) did not affect the frequency or duration of their visits to latrines located on pasture grazed by cattle. Nevertheless, there was wide variation in contact behaviour between individuals, which highlights the importance of understanding heterogeneity in contact patterns when developing strategies to control disease spread in wildlife and livestock.

  3. Anisotropic forces from spatially constrained focal adhesions mediate contact guidance directed cell migration.

    PubMed

    Ray, Arja; Lee, Oscar; Win, Zaw; Edwards, Rachel M; Alford, Patrick W; Kim, Deok-Ho; Provenzano, Paolo P

    2017-04-12

    Directed migration by contact guidance is a poorly understood yet vital phenomenon, particularly for carcinoma cell invasion on aligned collagen fibres. We demonstrate that for single cells, aligned architectures providing contact guidance cues induce constrained focal adhesion maturation and associated F-actin alignment, consequently orchestrating anisotropic traction stresses that drive cell orientation and directional migration. Consistent with this understanding, relaxing spatial constraints to adhesion maturation either through reduction in substrate alignment density or reduction in adhesion size diminishes the contact guidance response. While such interactions allow single mesenchymal-like cells to spontaneously 'sense' and follow topographic alignment, intercellular interactions within epithelial clusters temper anisotropic cell-substratum forces, resulting in substantially lower directional response. Overall, these results point to the control of contact guidance by a balance of cell-substratum and cell-cell interactions, modulated by cell phenotype-specific cytoskeletal arrangements. Thus, our findings elucidate how phenotypically diverse cells perceive ECM alignment at the molecular level.

  4. Direct and indirect contact rates among livestock operations in Colorado and Kansas.

    PubMed

    McReynolds, Sara W; Sanderson, Michael W; Reeves, Aaron; Sinclair, Marna; Hill, Ashley E; Salman, Mo D

    2014-05-01

    To characterize direct and indirect contacts among livestock operations in Colorado and Kansas. Cross-sectional quarterly survey. 532 livestock producers. Livestock producers in Colorado and Kansas were recruited by various means to participate in the survey, which was sent out via email or postal mail once quarterly (in March, June, September, and December) throughout 2011. Data were entered into an electronic record, and descriptive statistics were summarized. Large swine operations moving animals to other large swine operations had the highest outgoing direct contact rates (range, 5.9 to 24.53/quarter), followed by dairy operations moving cattle to auction or other dairy operations (range, 2.6 to 10.34/quarter). Incoming direct contact rates for most quarters were highest for large feedlots (range, 0 to 11.56/quarter) and dairies (range, 3.90 to 5.78/quarter). For large feedlots, mean total indirect contacts through feed trucks, livestock haulers, and manure haulers each exceeded 725 for the year. Dairy operations had a mean of 434.25 indirect contacts from milk trucks and 282.25 from manure haulers for the year. High direct contact rates detected among large swine operations may suggest a risk for direct disease transmission within the integrated swine system. Indirect contacts as well as incoming direct contacts may put large feedlots at substantial risk for disease introduction. These data can be useful for establishing and evaluating policy and biosecurity guidelines for livestock producers in the central United States. The results may be used to inform efforts to model transmission and control of infectious diseases such as foot-and-mouth disease in this region.

  5. Image based weighted center of proximity versus directly measured knee contact location during simulated gait

    PubMed Central

    Wang, Hongsheng; Chen, Tony; Koff, Matthew F.; Hutchinson, Ian D.; Gilbert, Susannah; Choi, Dan; Warren, Russell F.; Rodeo, Scott A.; Maher, Suzanne A.

    2014-01-01

    To understand the mechanical consequences of knee injury requires a detailed analysis of the effect of that injury on joint contact mechanics during activities of daily living. Three-dimensional (3D) knee joint geometric models have been combined with knee joint kinematics to dynamically estimate the location of joint contact during physiological activities – using a weighted center of proximity (WCoP) method. However, the relationship between the estimated WCoP and the actual location of contact has not been defined. The objective of this study was to assess the relationship between knee joint contact location as estimated using the image-based WCoP method, and a directly measured weighted center of contact (WCoC) method during simulated walking. To achieve this goal, we created knee specific models of six human cadaveric knees from magnetic resonance imaging. All knees were then subjected to physiological loads on a knee simulator intended to mimic gait. Knee joint motion was captured using a motion capture system. Knee joint contact stresses were synchronously recorded using a thin electronic sensor throughout gait, and used to compute WCoC for the medial and lateral plateaus of each knee. WCoP was calculated by combining knee kinematics with the MRI-based knee specific model. Both metrics were compared throughout gait using linear regression. The anteroposterior (AP) location of WCoP was significantly correlated with that of WCoC on both tibial plateaus in all specimens (P < 0.01, 95% confidence interval of Person’s coefficient r > 0), but the correlation was not significant in the mediolateral (ML) direction for 4/6 knees (P > 0.05). Our study demonstrates that while the location of joint contact obtained from 3D knee joint contact model, using the WCoP method, is significantly correlated with the location of actual contact stresses in the AP direction, that relationship is less certain in the ML direction. PMID:24837219

  6. 77 FR 14022 - Guidance for Industry: Testing for Salmonella Species in Human Foods and Direct-Human-Contact...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-08

    ... Human Foods and Direct-Human-Contact Animal Foods; Availability AGENCY: Food and Drug Administration... Direct- Human-Contact Animal Foods.'' The document provides guidance to firms that manufacture, process, pack, or hold human foods or direct-human- contact animal foods intended for distribution to consumers...

  7. Design of high-pressure direct contact heater for promising power supply units: Experimental substantiation

    NASA Astrophysics Data System (ADS)

    Somova, E. V.; Shvarts, A. L.; Turkin, A. V.

    2016-11-01

    The results of experimental studies of superheated steam condensation on feed water jets in a highpressure, direct-contact heat exchanger are presented. Direct contact feed water heater (DCFWH) can be used in a dual-flow diagram of a steam-power unit with ultrasupercritical steam parameters (35 MPa, 700/720°C). The direct contact feed water heater is included in the flow diagram of the II circuit in a promising power unit; it provides feed water heating to 340°C in all maintenance and emergency operation modes of the unit. The reliability of the high-pressure direct contact heater operation in this flow diagram is of major importance in relation to the danger of lead solidification in the tube space of the steam generator. Technical requirements to the design of the high-pressure direct contact heater for increasing the heat exchange efficiency are formulated based on the results of earlier studies with steam-water mixture as the heating medium. The results of studies of superheated steam condensation on jets presented in this study testify that feed water is additionally heated to the required temperature at the output of the installation. The influence of initial feed water parameters (outflow velocity and temperature) on the jet heating length is elucidated. The numerical approximation of the experimental data for determination of the jet heating length in the nominal and partial power unit loads is obtained. The results of the calculations are used to simplify the design of the water-supplying element for the direct contact feed water heater. The proposed design of direct contact feed water heater is characterized by simplicity and low metal intensity, which provides the installation reliability at the considered pressure level due to the minimum number of structural elements.

  8. Secondary pool boiling effects

    NASA Astrophysics Data System (ADS)

    Kruse, C.; Tsubaki, A.; Zuhlke, C.; Anderson, T.; Alexander, D.; Gogos, G.; Ndao, S.

    2016-02-01

    A pool boiling phenomenon referred to as secondary boiling effects is discussed. Based on the experimental trends, a mechanism is proposed that identifies the parameters that lead to this phenomenon. Secondary boiling effects refer to a distinct decrease in the wall superheat temperature near the critical heat flux due to a significant increase in the heat transfer coefficient. Recent pool boiling heat transfer experiments using femtosecond laser processed Inconel, stainless steel, and copper multiscale surfaces consistently displayed secondary boiling effects, which were found to be a result of both temperature drop along the microstructures and nucleation characteristic length scales. The temperature drop is a function of microstructure height and thermal conductivity. An increased microstructure height and a decreased thermal conductivity result in a significant temperature drop along the microstructures. This temperature drop becomes more pronounced at higher heat fluxes and along with the right nucleation characteristic length scales results in a change of the boiling dynamics. Nucleation spreads from the bottom of the microstructure valleys to the top of the microstructures, resulting in a decreased surface superheat with an increasing heat flux. This decrease in the wall superheat at higher heat fluxes is reflected by a "hook back" of the traditional boiling curve and is thus referred to as secondary boiling effects. In addition, a boiling hysteresis during increasing and decreasing heat flux develops due to the secondary boiling effects. This hysteresis further validates the existence of secondary boiling effects.

  9. Thermohydrodynamics of boiling in a van der Waals fluid.

    PubMed

    Laurila, T; Carlson, A; Do-Quang, M; Ala-Nissila, T; Amberg, G

    2012-02-01

    We present a modeling approach that enables numerical simulations of a boiling Van der Waals fluid based on the diffuse interface description. A boundary condition is implemented that allows in and out flux of mass at constant external pressure. In addition, a boundary condition for controlled wetting properties of the boiling surface is also proposed. We present isothermal verification cases for each element of our modeling approach. By using these two boundary conditions we are able to numerically access a system that contains the essential physics of the boiling process at microscopic scales. Evolution of bubbles under film boiling and nucleate boiling conditions are observed by varying boiling surface wettability. We observe flow patters around the three-phase contact line where the phase change is greatest. For a hydrophilic boiling surface, a complex flow pattern consistent with vapor recoil theory is observed.

  10. Unsteady heat transfer during subcooled film boiling

    NASA Astrophysics Data System (ADS)

    Yagov, V. V.; Zabirov, A. R.; Lexin, M. A.

    2015-11-01

    Cooling of high-temperature bodies in subcooled liquid is of importance for quenching technologies and also for understanding the processes initiating vapor explosion. An analysis of the available experimental information shows that the mechanisms governing heat transfer in these processes are interpreted ambiguously; a more clear-cut definition of the Leidenfrost temperature notion is required. The results of experimental observations (Hewitt, Kenning, and previous investigations performed by the authors of this article) allow us to draw a conclusion that there exists a special mode of intense heat transfer during film boil- ing of highly subcooled liquid. For revealing regularities and mechanisms governing intense transfer of energy in this process, specialists of Moscow Power Engineering Institute's (MPEI) Department of Engineering Thermal Physics conduct systematic works aimed at investigating the cooling of high-temperature balls made of different metals in water with a temperature ranging from 20 to 100°C. It has been determined that the field of temperatures that takes place in balls with a diameter of more than 30 mm in intense cooling modes loses its spherical symmetry. An approximate procedure for solving the inverse thermal conductivity problem for calculating the heat flux density on the ball surface is developed. During film boiling, in which the ball surface temperature is well above the critical level for water, and in which liquid cannot come in direct contact with the wall, the calculated heat fluxes reach 3-7 MW/m2.

  11. Droplet Impingement Boiling on Heated Superhydrophobic Surfaces

    NASA Astrophysics Data System (ADS)

    Crockett, Julie; Clavijo, Cristian; Maynes, Daniel

    2015-11-01

    When a droplet impinges on a solid surface at a temperature well above the saturation temperature, vaporization of the liquid begins immediately after contact. Different boiling regimes may result depending on the surface temperature and volatility of the liquid. The nucleate boiling regime is characterized by explosive atomization, which occurs when vapor bubbles burst causing an extravagant shower of small micro droplets as well as the well-known ``sizzling'' sound. In this work, we show that the vapor is surprisingly re-directed during impingement on a superhydrophobic surface such that atomization is completely suppressed. We hypothesize that this occurs because vapor escapes through the superhydrophobic interface such that the top of the droplet remains free of bursting vapor bubbles. We explore a wide range of surface patterning with feature spacing of 8 to 32 microns and solid area fractions of 10 to 50 percent; surface temperatures from 100 C to 400 C; and Weber numbers of 1 to 100. Atomization is found to decrease with increasing feature spacing and decreasing solid fraction, and vanishes completely for large spacing. It may be that large feature spacing promotes early transition to the Leidenfrost regime.

  12. Gravity Effects in Microgap Flow Boiling

    NASA Technical Reports Server (NTRS)

    Robinson, Franklin; Bar-Cohen, Avram

    2017-01-01

    Increasing integration density of electronic components has exacerbated the thermal management challenges facing electronic system developers. The high power, heat flux, and volumetric heat generation of emerging devices are driving the transition from remote cooling, which relies on conduction and spreading, to embedded cooling, which facilitates direct contact between the heat-generating device and coolant flow. Microgap coolers employ the forced flow of dielectric fluids undergoing phase change in a heated channel between devices. While two phase microcoolers are used routinely in ground-based systems, the lack of acceptable models and correlations for microgravity operation has limited their use for spacecraft thermal management. Previous research has revealed that gravitational acceleration plays a diminishing role as the channel diameter shrinks, but there is considerable variation among the proposed gravity-insensitive channel dimensions and minimal research on rectangular ducts. Reliable criteria for achieving gravity-insensitive flow boiling performance would enable spaceflight systems to exploit this powerful thermal management technique and reduce development time and costs through reliance on ground-based testing. In the present effort, the authors have studied the effect of evaporator orientation on flow boiling performance of HFE7100 in a 218 m tall by 13.0 mm wide microgap cooler. Similar heat transfer coefficients and critical heat flux were achieved across five evaporator orientations, indicating that the effect of gravity was negligible.

  13. On direct-writing methods for electrically contacting GaAs and Ge nanowire devices

    NASA Astrophysics Data System (ADS)

    Chen, Guannan; Gallo, Eric M.; Burger, Joan; Nabet, Bahram; Cola, Adriano; Prete, Paola; Lovergine, Nico; Spanier, Jonathan E.

    2010-05-01

    The electronic transport and gating characteristics in GaAs and Ge nanowires (NWs) are altered significantly following either indirect or direct exposure to a focused Ga+ ion beam (FIB), such as that used to produce Pt electrical contacts to NWs. While these results challenge the assumptions made in some previously reported work relating to the electronic properties of semiconductor NWs using FIB-assisted production of contacts and/or their leads, local electron beam induced deposition is shown to be a reliable and facile route for producing robust electrical contacts to individual vapor phase-grown NWs in a manner that enables study of their actual carrier transport properties.

  14. Investigation of the Dynamic Contact Angle Using a Direct Numerical Simulation Method.

    PubMed

    Zhu, Guangpu; Yao, Jun; Zhang, Lei; Sun, Hai; Li, Aifen; Shams, Bilal

    2016-11-15

    A large amount of residual oil, which exists as isolated oil slugs, remains trapped in reservoirs after water flooding. Numerous numerical studies are performed to investigate the fundamental flow mechanism of oil slugs to improve flooding efficiency. Dynamic contact angle models are usually introduced to simulate an accurate contact angle and meniscus displacement of oil slugs under a high capillary number. Nevertheless, in the oil slug flow simulation process, it is unnecessary to introduce the dynamic contact angle model because of a negligible change in the meniscus displacement after using the dynamic contact angle model when the capillary number is small. Therefore, a critical capillary number should be introduced to judge whether the dynamic contact model should be incorporated into simulations. In this study, a direct numerical simulation method is employed to simulate the oil slug flow in a capillary tube at the pore scale. The position of the interface between water and the oil slug is determined using the phase-field method. The capacity and accuracy of the model are validated using a classical benchmark: a dynamic capillary filling process. Then, different dynamic contact angle models and the factors that affect the dynamic contact angle are analyzed. The meniscus displacements of oil slugs with a dynamic contact angle and a static contact angle (SCA) are obtained during simulations, and the relative error between them is calculated automatically. The relative error limit has been defined to be 5%, beyond which the dynamic contact angle model needs to be incorporated into the simulation to approach the realistic displacement. Thus, the desired critical capillary number can be determined. A three-dimensional universal chart of critical capillary number, which functions as static contact angle and viscosity ratio, is given to provide a guideline for oil slug simulation. Also, a fitting formula is presented for ease of use.

  15. Optimizations of packed sorbent and inlet temperature for large volume-direct aqueous injection-gas chromatography to determine high boiling volatile organic compounds in water.

    PubMed

    Yu, Bofan; Song, Yonghui; Han, Lu; Yu, Huibin; Liu, Yang; Liu, Hongliang

    2014-08-22

    For the expanded application area, fast trace analysis of certain high boiling point (i.e., 150-250 °C) volatile organic compounds (HVOCs) in water, a large volume-direct aqueous injection-gas chromatography (LV-DAI-GC) method was optimized for the following parameters: packed sorbent for sample on-line pretreatment, inlet temperature and detectors configuration. Using the composite packed sorbent self-prepared with lithium chloride and a type of diatomite, the method enabled safe injection of an approximately 50-100 μL sample at an inlet temperature of 150 °C in the splitless mode and separated HVOCs from water matrix in 2 min. Coupled with a flame ionization detector (FID), an electron capture detector (ECD) and a flame photometric detector (FPD), the method could simultaneously quantify 27 HVOCs that belong to seven subclasses (i.e., halogenated aliphatic hydrocarbons, chlorobenzenes, nitrobenzenes, anilines, phenols, polycyclic aromatic hydrocarbons and organic sulfides) in 26 min. Injecting a 50 μL sample without any enrichment step, such as cryotrap focusing, the limits of quantification (LOQs) for the 27 HVOCs was 0.01-3 μg/L. Replicate analyses of the 27 HVOCs spiked source and river water samples exhibited good precision (relative standard deviations ≤ 11.3%) and accuracy (relative errors ≤ 17.6%). The optimized LV-DAI-GC was robust and applicable for fast determination and automated continuous monitoring of HVOCs in surface water.

  16. Non-contact data access with direction identification for industrial differential serial bus.

    PubMed

    Xie, Kai; Li, Xiaoping; Zhang, Hanlu; Yang, Ming; Ye, Yinghao

    2013-06-01

    We propose a non-contact method for accessing data in industrial differential serial bus applications, which could serve as an effective and safe online testing and diagnosing tool. The data stream and the transmission direction are reconstructed simultaneously from the near-field emanations of a twisted pair, eliminating direct contact with the actual conductors, and avoiding damage to the insulation (only the outer sheathing is removed). A non-contact probe with the ability to sense electric and magnetic fields is presented, as are theories for data reconstruction, direction identification, and a circuit implementation. The prototype was built using inexpensive components and then tested on a standard RS-485 industrial serial bus. Experimental results verified the validity of the proposed scheme.

  17. Basic Research on a Latent Heat Thermal Energy Storage by Direct Contact Melting and Soldification

    NASA Astrophysics Data System (ADS)

    Saito, Akihiro; Saito, Akio; Utaka, Yoshio; Okuda, Kenichi; Katayama, Kozo

    A basic experimental research on a latent heat thermal energy storage system , utilizing a simple and effective heat exchange mechanism by a direct contact between the phase change material (PCM) and the heat transfer fluid (HTF), was shown. Discharging experiments on direct contact latent heat thermal energy reservoir using n-Eicosane as the PCM and water as the HTF, were performed, based on the conditions obtained in previous report. Then, operating conditions for suitable discharging process were searched from the experimental results (outlet water temperature response and local temperature response in the reservoir). Moreover, solidification mechanisms of PCM, which had been presumed in previous report, were confirmed from these experimental results, and the simple physical model on direct contact heat exchange in the reservoir was proposed. Then, the outlet water temperature response by this model was compared with the experimental results.

  18. Basic Research on a Latent Heat Thermal Energy Storage by Direct Contact Melting and Solidification

    NASA Astrophysics Data System (ADS)

    Saito, Akihiro; Saito, Akio; Utaka, Yoshio; Okuda, Kenichi; Katayama, Kozo

    A basic experimental research on a latent heat thermal energy storage system, utilizing a simple and effective heat exchange mechanism by a direct contact between the phase change material (PCM) and the heat transfer fluid (HTF) , was shown. In this report, authors proposed the direct contact latent heat thermal energy storage system using industrial paraffin and n-Eicosane as the PCM, and using water as the HTF. The observations were performed concerning the HTF separation from the solid PCM in the solidification process (heat discharging process), and concerning the water pass formation within the solid PCM. Then, it was confirmed that the system worked effectively by using n-Eicosane as the PCM. And authors discussed the mechanism of direct contact solidification process from experimental results.

  19. Evidence for Transmission of Bluetongue Virus Serotype 26 through Direct Contact

    PubMed Central

    Henstock, Mark; Fay, Petra; Veronesi, Eva; Gubbins, Simon; Graves, Samantha; Frost, Lorraine; Oura, Christopher

    2014-01-01

    The aim of this study was to assess the mechanisms of transmission of bluetongue virus serotype 26 (BTV-26) in goats. A previous study, which investigated the pathogenicity and infection kinetics of BTV-26 in goats, unexpectedly revealed that one control goat may have been infected through a direct contact transmission route. To investigate the transmission mechanisms of BTV-26 in more detail an experimental infection study was carried out in which three goats were infected with BTV-26, three goats were kept uninfected, but were housed in direct contact with the infected goats, and an additional four goats were kept in indirect contact separated from infected goats by metal gates. This barrier allowed the goats to have occasional face-to-face contact in the same airspace, but feeding, watering, sampling and environmental cleaning was carried out separately. The three experimentally infected goats did not show clinical signs of BTV, however high levels of viral RNA were detected and virus was isolated from their blood. At 21 dpi viral RNA was detected in, and virus was isolated from the blood of the three direct contact goats, which also seroconverted. The four indirect barrier contact goats remained uninfected throughout the duration of the experiment. In order to assess replication in a laboratory model species of Culicoides biting midge, more than 300 Culicoides sonorensis were fed a BTV-26 spiked blood meal and incubated for 7 days. The dissemination of BTV-26 in individual C. sonorensis was inferred from the quantity of virus RNA and indicated that none of the insects processed at day 7 possessed transmissible infections. This study shows that BTV-26 is easily transmitted through direct contact transmission between goats, and the strain does not seem to replicate in C. sonorensis midges using standard incubation conditions. PMID:24797910

  20. Reversed boiling curve phenomenon on surfaces with interlaced wettability

    NASA Astrophysics Data System (ADS)

    Hsu, C. C.; Chiu, W. C.; Kuo, L. S.; Chen, P. H.

    2014-10-01

    We experimentally investigated the effects of contact angle difference of heterogeneous wettability surfaces on pool boiling. For surfaces exhibiting heterogeneous wettability, this study determined that the pool boiling curve experiences a superheat decrease in some regions before the system achieves the critical heat flux. In addition, oscillation of the vapor column and bubble transverse motions on the heterogeneous wettability coated surface were observed.

  1. Modulating contact angle hysteresis to direct fluid droplets along a homogenous surface.

    PubMed

    Luo, Mingxiang; Gupta, Rohini; Frechette, Joelle

    2012-02-01

    The shape and motion of drops on surfaces is governed by the balance between the driving and the pinning forces. Here we demonstrate control over the motion of droplets on an inclined surface by exerting control over the contact angle hysteresis. The external modulation of contact angle hysteresis is achieved through a voltage-induced local molecular reorganization within the surface film at the solid-liquid interface. We show that tuning contact angle hysteresis alone is sufficient to direct and deform drops when subjected to a constant external driving force, here gravity, in the absence of a pre-defined surface energy gradient or pattern. We also show that the observed stretching and contraction of the drops mimic the motion of an inchworm. Such reversible manipulation of the pinning forces could be an attractive means to direct drops, especially with the dominance of surface forces at micro-/nanoscale.

  2. Proximal contact tightness between direct-composite additions in the posterior dentition: an in vitro investigation.

    PubMed

    Wolff, Diana; Hahn, Philipp; Ding, Paul; Maier-Kraus, Theresa; Frese, Cornelia; Doerfer, Christof; Staehle, Hans Joerg

    2012-01-01

    The aim of the study was to test whether a novel three-step matrix technique for posterior direct-composite additions creates sufficiently strong proximal contacts. Contact tightness was measured between direct-composite additions and between original teeth on a model. Therefore, the frictional forces required to remove a straight, 0.05-mm-thick, metal matrix band inserted between adjacent teeth and held by a universal testing machine (Zwicki, Zwick GmbH, Ulm, Germany) were recorded. Measurements were taken at three time points to carry out reference analysis: at baseline, after removal of the maxillary right second premolar (tooth #15) to simulate a diastema, and after closure of the diastema by inserting two direct-composite additions with the three-step matrix technique on the maxillary right first premolar (tooth #14) and first molar (tooth #16). Measurements were performed in the maxillary right (first) and left (second) quadrants to document sagittal displacement. The original contact tightness values were between 1.65 ± 0.88 N and 3.05 ± 0.60 N in the first quadrant and between 1.23 ± 0.51 N and 2.18 ± 0.43 N in the second quadrant. After removal of tooth 15, values decreased significantly in the first quadrant and insignificantly in the second. After reconstruction, the contact tightness between teeth 14 and 16 was significantly stronger (tighter) (3.20 ± 0.80 N) than the originally measured contact tightness between teeth 14 and 15 (2.86 ± 0.64 N) and teeth 15 and 16 (1.65 ± 0.88 N) (p=0.006 and 0.001, respectively). Within the limitations of an in vitro investigation, this study has shown that by using a novel, three-step matrix technique, direct posterior composite additions can form sufficiently tight proximal contacts.

  3. How does surface wettability influence nucleate boiling?

    NASA Astrophysics Data System (ADS)

    Phan, Hai Trieu; Caney, Nadia; Marty, Philippe; Colasson, Stéphane; Gavillet, Jérôme

    2009-05-01

    Although the boiling process has been a major subject of research for several decades, its physics still remain unclear and require further investigation. This study aims at highlighting the effects of surface wettability on pool boiling heat transfer. Nanocoating techniques were used to vary the water contact angle from 20° to 110° by modifying nanoscale surface topography and chemistry. The experimental results obtained disagree with the predictions of the classical models. A new approach of nucleation mechanism is established to clarify the nexus between the surface wettability and the nucleate boiling heat transfer. In this approach, we introduce the concept of macro- and micro-contact angles to explain the observed phenomenon. To cite this article: H.T. Phan et al., C. R. Mecanique 337 (2009).

  4. Eyes only? Perceiving eye contact is neither sufficient nor necessary for attentional capture by face direction.

    PubMed

    Böckler, Anne; van der Wel, Robrecht P R D; Welsh, Timothy N

    2015-09-01

    Direct eye contact and motion onset both constitute powerful cues that capture attention. Recent research suggests that (social) gaze and (non-social) motion onset influence information processing in parallel, even when combined as sudden onset direct gaze cues (i.e., faces suddenly establishing eye contact). The present study investigated the role of eye visibility for attention capture by these sudden onset face cues. To this end, face direction was manipulated (away or towards onlooker) while faces had closed eyes (eliminating visibility of eyes, Experiment 1), wore sunglasses (eliminating visible eyes, but allowing for the expectation of eyes to be open, Experiment 2), and were inverted with visible eyes (disrupting the integration of eyes and faces, Experiment 3). Participants classified targets appearing on one of four faces. Initially, two faces were oriented towards participants and two faces were oriented away from participants. Simultaneous to target presentation, one averted face became directed and one directed face became averted. Attention capture by face direction (i.e., facilitation for faces directed towards participants) was absent when eyes were closed, but present when faces wore sunglasses. Sudden onset direct faces can, hence, induce attentional capture, even when lacking eye cues. Inverted faces, by contrast, did not elicit attentional capture. Thus, when eyes cannot be integrated into a holistic face representation they are not sufficient to capture attention. Overall, the results suggest that visibility of eyes is neither necessary nor sufficient for the sudden direct face effect.

  5. Evaporation, Boiling and Bubbles

    ERIC Educational Resources Information Center

    Goodwin, Alan

    2012-01-01

    Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

  6. Evaporation, Boiling and Bubbles

    ERIC Educational Resources Information Center

    Goodwin, Alan

    2012-01-01

    Evaporation and boiling are both terms applied to the change of a liquid to the vapour/gaseous state. This article argues that it is the formation of bubbles of vapour within the liquid that most clearly differentiates boiling from evaporation although only a minority of chemistry textbooks seems to mention bubble formation in this context. The…

  7. Anisotropic forces from spatially constrained focal adhesions mediate contact guidance directed cell migration

    PubMed Central

    Ray, Arja; Lee, Oscar; Win, Zaw; Edwards, Rachel M.; Alford, Patrick W.; Kim, Deok-Ho; Provenzano, Paolo P.

    2017-01-01

    Directed migration by contact guidance is a poorly understood yet vital phenomenon, particularly for carcinoma cell invasion on aligned collagen fibres. We demonstrate that for single cells, aligned architectures providing contact guidance cues induce constrained focal adhesion maturation and associated F-actin alignment, consequently orchestrating anisotropic traction stresses that drive cell orientation and directional migration. Consistent with this understanding, relaxing spatial constraints to adhesion maturation either through reduction in substrate alignment density or reduction in adhesion size diminishes the contact guidance response. While such interactions allow single mesenchymal-like cells to spontaneously ‘sense' and follow topographic alignment, intercellular interactions within epithelial clusters temper anisotropic cell–substratum forces, resulting in substantially lower directional response. Overall, these results point to the control of contact guidance by a balance of cell–substratum and cell–cell interactions, modulated by cell phenotype-specific cytoskeletal arrangements. Thus, our findings elucidate how phenotypically diverse cells perceive ECM alignment at the molecular level. PMID:28401884

  8. Antibacterial properties of aged dental cements evaluated by direct-contact and agar diffusion tests.

    PubMed

    Lewinstein, Israel; Matalon, Shlomo; Slutzkey, Shimshon; Weiss, Ervin I

    2005-04-01

    Since failure of fixed partial dentures is most frequently caused by caries, it would be advantageous if cements possessed antibacterial properties. The purpose of this study was to evaluate the antibacterial properties of 3 dental cements using the direct-contact test and agar diffusion test. For the direct-contact test, wells (n = 4) of microtiter plates were coated with the tested cements (Harvard cement, Duralon, and Ketac-Cem) while Streptococcus mutans suspension was placed directly on the cements. Bacterial growth was evaluated by a temperature-controlled microplate spectrophotometer. Eight wells of bacteria without the tested cements served as the positive control. Six wells of the tested cement without bacteria served as the negative control. For the agar diffusion test, triplicate specimens of freshly mixed cements were poured into uniform wells (5 mm in diameter) punched in the agar plates inoculated with Streptococcus mutans . After incubation at 37 degrees C for 24 hours, the agar plates were examined for bacterial growth and the diameter of the halo formed in the bacterial lawn was measured. In both tests, each cement was mixed in 2 different powder/liquid ratios. For the direct-contact test, data were initially recorded after 1 hour of incubation. Additional experiments were performed on specimens that were aged for 24 hours, 1 week, 1 month, and 3 months before assessment by either direct-contact test or agar diffusion test. The data were subjected to 1-way ANOVA with the Tukey post hoc test (alpha=.05). Compared with the control group, Duralon and Harvard cements demonstrated antibacterial properties even after 3 months with the direct-contact test (P <.002), while Ketac-Cem exhibited no antibacterial properties. In the agar diffusion test, no antibacterial activity was observed for any of the tested cements. The different powder/liquid ratios had a negligible effect on the antibacterial properties of the tested cements. Within the limitations of

  9. Ohmic contact formation on n-type Ge by direct deposition of TiN

    SciTech Connect

    Iyota, Masatoshi; Yamamoto, Keisuke; Wang, Dong; Yang, Haigui; Nakashima, Hiroshi

    2011-05-09

    We succeeded in Ohmic contact formation on an n-Ge substrate by direct sputter deposition from a TiN target and subsequent postmetallization annealing (PMA) at 350 deg. C. The Schottky barrier heights of the TiN/n-Ge and TiN/p-Ge contacts were 0.18 eV and 0.50 eV, respectively, and were maintained up to a PMA temperature of 550 deg. C. These electrical characteristics are likely to be associated with an approximately 1-nm-thick interlayer formed at a TiN/Ge interface, which leads to the alleviation of the Fermi level pinning. We demonstrated the validity of the TiN/n-Ge contact using an n{sup +}/p junction, which showed an excellent ideal factor of n=1.01.

  10. Direct probing of contact electrification by using optical second harmonic generation technique

    PubMed Central

    Chen, Xiangyu; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa; Wang, Zhong Lin

    2015-01-01

    Contact electrification between two different materials is one of the oldest fields of study in solid-state physics. Here, we introduced an innovative system based on optical electric-field-induced second harmonic generation (EFI-SHG) technique that can directly monitor the dynamic performance of the contact electrification on the surface of polyimide film. After the contact, the EFI-SHG system visualized briefly three relaxations of the tribo-induced charges on the surface of a polyimide film, a fast relaxation within 3 min followed by two much slower relaxations, which were possibly related to different charge diffusion routes. The contact electrification under several special experimental conditions (wind, water and steam) was studied to demonstrate the high flexibility and material selectivity of the EFI-SHG. The EFI-SHG studies confirmed the motion of the water can remove the surface charge, while the appearance and the evaporation of a thin water layer cannot enhance the charge diffusion. We anticipate that this experimental technique will find a variety of applications in the field of contact electrification and the development of the recently invented triboelectric nano generator. PMID:26272162

  11. Direct probing of contact electrification by using optical second harmonic generation technique

    NASA Astrophysics Data System (ADS)

    Chen, Xiangyu; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa; Wang, Zhong Lin

    2015-08-01

    Contact electrification between two different materials is one of the oldest fields of study in solid-state physics. Here, we introduced an innovative system based on optical electric-field-induced second harmonic generation (EFI-SHG) technique that can directly monitor the dynamic performance of the contact electrification on the surface of polyimide film. After the contact, the EFI-SHG system visualized briefly three relaxations of the tribo-induced charges on the surface of a polyimide film, a fast relaxation within 3 min followed by two much slower relaxations, which were possibly related to different charge diffusion routes. The contact electrification under several special experimental conditions (wind, water and steam) was studied to demonstrate the high flexibility and material selectivity of the EFI-SHG. The EFI-SHG studies confirmed the motion of the water can remove the surface charge, while the appearance and the evaporation of a thin water layer cannot enhance the charge diffusion. We anticipate that this experimental technique will find a variety of applications in the field of contact electrification and the development of the recently invented triboelectric nano generator.

  12. Direct Contact Sorptive Extraction: A Robust Method for Sampling Plant Volatiles in the Field.

    PubMed

    Kfoury, Nicole; Scott, Eric; Orians, Colin; Robbat, Albert

    2017-09-27

    Plants produce volatile organic compounds (VOCs) with diverse structures and functions, which change in response to environmental stimuli and have important consequences for interactions with other organisms. To understand these changes, in situ sampling is necessary. In contrast to dynamic headspace (DHS), which is the most often employed method, direct contact sampling employing a magnetic stir bar held in place by a magnet eliminates artifacts produced by enclosing plant materials in glass or plastic chambers. Direct-contact sorptive extraction (DCSE) using polydimethylsiloxane coated stir bars (Twisters) coated stir bars is more sensitive than DHS, captures a wider range of compounds, minimizes VOC collection from neighboring plants, and distinguishes the effects of herbivory in controlled and field conditions. Because DCSE is relatively inexpensive and simple to employ, scalability of field trials can be expanded concomitant with increased sample replication. The sensitivity of DCSE combined with the spectral deconvolution data analysis software makes the two ideal for comprehensive, in situ profiling of plant volatiles.

  13. CONTINUOUS ANALYZER UTILIZING BOILING POINT DETERMINATION

    DOEpatents

    Pappas, W.S.

    1963-03-19

    A device is designed for continuously determining the boiling point of a mixture of liquids. The device comprises a distillation chamber for boiling a liquid; outlet conduit means for maintaining the liquid contents of said chamber at a constant level; a reflux condenser mounted above said distillation chamber; means for continuously introducing an incoming liquid sample into said reflux condenser and into intimate contact with vapors refluxing within said condenser; and means for measuring the temperature of the liquid flowing through said distillation chamber. (AEC)

  14. Direct Deposition of Low Resistance Thermally Stable Ohmic Contacts to n-SiC

    DTIC Science & Technology

    2001-06-01

    Direct Deposition of Low Resistance Thermally Stable Ohmic Contacts to n-SiC by M. W. Cole, P. C. Joshi, M. H . Ervin, J. D. Demaree, M...SiC M. W. Cole, P. C. Joshi, J. D. Demaree, C. W. Hubbard, and J. K. Hirvonen Weapons and Materials Research Directorate, ARL M. H . Ervin and...device operation. ii Acknowledgments The authors would like to acknowledge H . Kim, A. Pique, D. B. Chrisey, C. K. Richardson, and M. H . Wisnioski

  15. Livestock-Associated MRSA Carriage in Patients without Direct Contact with Livestock

    PubMed Central

    van Rijen, Miranda M. L.; Bosch, Thijs; Verkade, Erwin J. M.; Schouls, Leo; Kluytmans, Jan A. J. W.

    2014-01-01

    Background Livestock-associated MRSA (MC398) has emerged and is related to an extensive reservoir in pigs and veal calves. Individuals with direct contact with these animals and their family members are known to have high MC398 carriage rates. Until now it was assumed that MC398 does not spread to individuals in the community without pig or veal calf exposure. To test this, we identified the proportion of MC398 in MRSA positive individuals without contact with pigs/veal calves or other known risk factors (MRSA of unknown origin; MUO). Methods In 17 participating hospitals, we determined during two years the occurrence of MC398 in individuals without direct contact with livestock and no other known risk factor (n = 271) and tested in a post analysis the hypothesis whether hospitals in pig-dense areas have higher proportions of MC398 of all MUO. Results Fifty-six individuals (20.7%) without animal contact carried MC398. In hospitals with high pig-densities in the adherence area, the proportion of MC398 of all MUO was higher than this proportion in hospitals without pigs in the surroundings. Conclusions One fifth of the individuals carrying MUO carried MC398. So, MC398 is found in individuals without contact to pigs or veal calves. The way of transmission from the animal reservoir to these individuals is unclear, probably by human-to-human transmission or by exposure to the surroundings of the stables. Further research is needed to investigate the way of transmission. PMID:25000521

  16. Computations of Boiling in Microgravity

    NASA Technical Reports Server (NTRS)

    Tryggvason, Gretar; Jacqmin, David

    1999-01-01

    The absence (or reduction) of gravity, can lead to major changes in boiling heat transfer. On Earth, convection has a major effect on the heat distribution ahead of an evaporation front, and buoyancy determines the motion of the growing bubbles. In microgravity, convection and buoyancy are absent or greatly reduced and the dynamics of the growing vapor bubbles can change in a fundamental way. In particular, the lack of redistribution of heat can lead to a large superheat and explosive growth of bubbles once they form. While considerable efforts have been devoted to examining boiling experimentally, including the effect of microgravity, theoretical and computational work is limited to very simple models. In this project, the growth of boiling bubbles is studied by direct numerical simulations where the flow field is fully resolved and the effects of inertia, viscosity, surface deformation, heat conduction and convection, as well as the phase change, are fully accounted for. The proposed work is based on previously funded NASA work that allowed us to develop a two-dimensional numerical method for boiling flows and to demonstrate the ability of the method to simulate film boiling. While numerical simulations of multi-fluid flows have been advanced in a major way during the last five years, or so, similar capability for flows with phase change are still in their infancy. Although the feasibility of the proposed approach has been demonstrated, it has yet to be extended and applied to fully three-dimensional simulations. Here, a fully three-dimensional, parallel, grid adaptive code will be developed. The numerical method will be used to study nucleate boiling in microgravity, with particular emphasis on two aspects of the problem: 1) Examination of the growth of bubbles at a wall nucleation site and the instabilities of rapidly growing bubbles. Particular emphasis will be put on accurately capturing the thin wall layer left behind as a bubble expands along a wall, on

  17. Development of separation techniques for a direct contact thermal energy storage system

    SciTech Connect

    Min, T.C.; Tomlinson, J.J.

    1989-03-01

    In direct contact ice-making processes, the refrigerant will pick up water vapor through direct percolation and oil from the compressor. The purpose of this project is to investigate methods for separating water vapor and oil from a mixture to complete a refrigeration cycle. In this paper, we report critical review on two separation techniques. From a literature search, we have identified a third technique; and plan to evaluate this method by bench-scale experiments. A recommendation for future work is included.

  18. Boiling from small cylinders.

    NASA Technical Reports Server (NTRS)

    Bakhru, N.; Lienhard, J. H.

    1972-01-01

    Heat transfer is observed as a function of temperature on small horizontal wires in water and four organic liquids. When the wire radius is sufficiently small, the hydrodynamic transitions in the boiling curve disappear and the curve becomes monotonic. Three modes of heat removal are identified for the monotonic curve and described analytically: a natural convection mode, a mixed film boiling and natural convection mode, and a pure film boiling mode. Nucleate boiling does not occur on the small wires. The study was motivated by an interest in predicting the behavior of large heaters at low gravity. The application of the present results to such circumstances is therefore discussed. It is proposed that the peak and minimum heat fluxes will vanish at low gravity as well as on small wires.

  19. Odd-Boiled Eggs

    ERIC Educational Resources Information Center

    Kaminsky, Kenneth; Scheman, Naomi

    2010-01-01

    At a Shabbat lunch in Madrid not long ago, the conversation turned to the question of boiling eggs. One of the guests mentioned that a Dutch rabbi he knew had heard that in order to make it more likely that boiled eggs be kosher, you should add an egg to the pot if the number you began with was even. According to the laws of Kashruth, Jews may not…

  20. Odd-Boiled Eggs

    ERIC Educational Resources Information Center

    Kaminsky, Kenneth; Scheman, Naomi

    2010-01-01

    At a Shabbat lunch in Madrid not long ago, the conversation turned to the question of boiling eggs. One of the guests mentioned that a Dutch rabbi he knew had heard that in order to make it more likely that boiled eggs be kosher, you should add an egg to the pot if the number you began with was even. According to the laws of Kashruth, Jews may not…

  1. Evaluation of cytotoxic effects of six self-etching adhesives with direct and indirect contact tests.

    PubMed

    Kusdemir, Mahmut; Gunal, Solen; Ozer, Fusun; Imazato, Satoshi; Izutani, Naomi; Ebisu, Shigeyuki; Blatz, Markus B

    2011-01-01

    This study evaluated the cytotoxicity of self-etching primers/adhesives by direct contact and dentin barrier tests. The three two-step self-etching systems Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Prime&Bond NT/NRC (PB) and one-step self-etching systems Reactmer Bond (RB), Clearfil Tri-S Bond (CTS), and Adper Prompt L-Pop (AP) were examined. In direct contact tests, L929 cells were cultured in the presence of diluted solutions (50, 20, 10, and 1%) of primer/conditioner of adhesive systems. For dentin barrier tests, each system was applied onto 0.5 or 1.5 mm thick human dentin assembled in a simple pulp chamber device and incubated for 24 h at 37°C to make the diffusive components contact the L929 cells placed at the bottom of the chamber. The cytotoxic effects were assessed by MTT assay. Cell culture without application of any primers/adhesives served as the control for both tests. One-way ANOVA and Tukey HSD tests were used for statistical analyses. The direct contact tests demonstrated that CSE and CPB were less toxic than the other materials at all dilutions. In the dentin barrier tests, toxic effects of materials were reduced with an increase in thickness of intervening dentin. CSE and CPB showed less cytotoxicity than the other adhesives (p<0.05) when applied to 0.5 mm-thick dentin, and CSE was the least toxic in the 1.5 mm-dentin group (p<0.05). Dentin thickness positively affected biocompatibility of the tested bonding systems. Two-step self-etching systems with HEMA-based primers were more biocompatible than other self-etching adhesives.

  2. An approach to directional drilling simulation: finite element and finite segment methods with contact

    NASA Astrophysics Data System (ADS)

    Arbatani, Siamak; Callejo, Alfonso; Kövecses, József; Kalantari, Masoud; Marchand, Nick R.; Dargahi, Javad

    2016-06-01

    Directional drilling is a popular technique for oil well drilling. Accurate prediction of the directional performance is critical in order to achieve the desired well profile. Simplified geometry methods are, to date, the industry standard for predicting directional performance. A comprehensive, high-fidelity method for the simulation of directional drilling is presented here. It consists of a detailed discretization of the actual geometry and a rigorous application of two modeling techniques: the finite element and the finite segment methods. By doing so, the dynamic problem is addressed from two different yet complementary perspectives: structural mechanics and rigid-body motion. Collision detection and contact dynamics algorithms are also presented. Results show that both methods agree in terms of the dynamic response, and that the build rate estimations are consistent with available experimental data. Owing to the framework efficiency and physics-based nature, the presented tools are very well-suited for design engineering and real-time simulation.

  3. Direct TFIIA-TFIID protein contacts drive budding yeast ribosomal protein gene transcription.

    PubMed

    Layer, Justin H; Weil, P Anthony

    2013-08-09

    We have previously shown that yeast TFIID provides coactivator function on the promoters of ribosomal protein-encoding genes (RPGs) by making direct contact with the transactivator repressor activator protein 1 (Rap1). Further, our structural studies of assemblies generated with purified Rap1, TFIID, and TFIIA on RPG enhancer-promoter DNA indicate that Rap1-TFIID interaction induces dramatic conformational rearrangements of enhancer-promoter DNA and TFIID-bound TFIIA. These data indicate a previously unknown yet critical role for yeast TFIIA in the integration of activator-TFIID contacts with promoter conformation and downstream preinitiation complex formation and/or function. Here we describe the use of systematic mutagenesis to define how specific TFIIA contacts contribute to these processes. We have verified that TFIIA is required for RPG transcription in vivo and in vitro, consistent with the existence of a critical Rap1-TFIIA-TFIID interaction network. We also identified essential points of contact for TFIIA and Rap1 within the Rap1 binding domain of the Taf4 subunit of TFIID. These data suggest a mechanism for how interactions between TFIID, TFIIA, and Rap1 contribute to the high rate of transcription initiation seen on RPGs in vivo.

  4. Direct TFIIA-TFIID Protein Contacts Drive Budding Yeast Ribosomal Protein Gene Transcription*

    PubMed Central

    Layer, Justin H.; Weil, P. Anthony

    2013-01-01

    We have previously shown that yeast TFIID provides coactivator function on the promoters of ribosomal protein-encoding genes (RPGs) by making direct contact with the transactivator repressor activator protein 1 (Rap1). Further, our structural studies of assemblies generated with purified Rap1, TFIID, and TFIIA on RPG enhancer-promoter DNA indicate that Rap1-TFIID interaction induces dramatic conformational rearrangements of enhancer-promoter DNA and TFIID-bound TFIIA. These data indicate a previously unknown yet critical role for yeast TFIIA in the integration of activator-TFIID contacts with promoter conformation and downstream preinitiation complex formation and/or function. Here we describe the use of systematic mutagenesis to define how specific TFIIA contacts contribute to these processes. We have verified that TFIIA is required for RPG transcription in vivo and in vitro, consistent with the existence of a critical Rap1-TFIIA-TFIID interaction network. We also identified essential points of contact for TFIIA and Rap1 within the Rap1 binding domain of the Taf4 subunit of TFIID. These data suggest a mechanism for how interactions between TFIID, TFIIA, and Rap1 contribute to the high rate of transcription initiation seen on RPGs in vivo. PMID:23814059

  5. Estimation of direct-contact fraction for phenanthrene in surfactant solutions by toxicity measurement.

    PubMed

    Lee, Hyo J; Lee, Min W; Lee, Dae S; Woo, Seung H; Park, Jong M

    2007-09-30

    The toxicity of solutions containing nonionic surfactants Tween 80, Brij 35 and/or phenanthrene to Pseudomonas putida ATCC 17484 was investigated. The fraction of direct contact between micellar-phase phenanthrene and bacterial cell surface was estimated by using the toxicity data and a mathematical model. The mathematical model was used to calculate phenanthrene concentration in the micellar phase and aqueous pseudophase separately. The first-order death rate constant increased from 0.088+/-0.016 to 0.25+/-0.067 h(-1) when the phenanthrene concentration was increased from 0 to 5.17 x 10(-6)M (equals water solubility). The intrinsic toxicity of surfactant was higher in Brij 35 than in Tween 80. When phenanthrene concentration was increased to 9.7 x 10(-5)M in surfactant solutions, the death rate constant increased to 1.8 +/- 0.024 and 0.41 +/- 0.088 h(-1) for 8.4 x 10(-4)M Brij 35 and 7.6 x 10(-4)M Tween 80. The direct-contact fraction was 0.083 and 0.044 for Brij 35 and Tween 80, respectively, under these conditions using exponential model. The toxicity increased with increasing phenanthrene concentration at a fixed surfactant concentration. The toxicity decreased with increasing the surfactant concentration at a fixed phenanthrene concentration due to decreased contact of bacteria with phenanthrene present in the interior of surfactant micelles.

  6. Does direct human eye contact function as a warning cue for domestic sheep (Ovis aries)?

    PubMed

    Beausoleil, Ngaio J; Stafford, Kevin J; Mellor, David J

    2006-08-01

    Direct eye contact may function as a warning cue during interspecific interactions, and human staring has been shown to influence the behavior of many species. The authors used an arena test to assess whether human staring altered the behavior of domestic sheep (Ovis aries) compared with no human eye contact. Sheep glanced at the staring human's face more often in the first 2 min of the test, indicating that they perceived a difference between the human stimuli. Staring also elicited more locomotor activity and urination than averted gaze. However, there were no differences in fear-related behaviors, suggesting that a staring human did not represent a greater immediate threat than a nonwatching human. These results imply that human staring is a warning cue for domestic sheep, but no more. Without further reinforcement, sheep quickly habituated to the warning cue.

  7. Direct measurements of the pressure distribution along the contact area during droplet impact

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh-Vinh; Matsumoto, Kiyoshi; Shimoyama, Isao

    2016-11-01

    We report direct measurements of the pressure distribution on the contact area during the impact of a droplet on a micropillar array. The measurements were realized using an array of MEMS-based force sensors fabricated underneath the micropillars. We show that immediately after the droplet hits the surface, the pressure becomes maximum at the center of the contact area and this maximum pressure value is more than 10 times larger than the dynamic pressure. This result emphasizes the effect of water-hammer-type pressure during the early stage of the impact. Furthermore, our measurement results demonstrate that the critical pressure associated with Cassie-Wenzel transition agrees well with the maximum capillary pressure of the micropillar array.

  8. Placement error in directed self-assembly of block copolymers for contact hole application

    NASA Astrophysics Data System (ADS)

    Bouanani, Shayma; Tiron, Raluca; Bos, Sandra; Gharbi, Ahmed; Barros, Patricia Pimenta; Hazart, Jérôme; Robert, Frédéric; Lapeyre, Céline; Ostrovsky, Alain; Monget, Cédric

    2016-04-01

    Directed self-assembly (DSA) of block copolymers has shown interesting results for contact hole application, as a vertical interconnection access for CMOS sub-10 nm technology. The control of critical dimension uniformity (CDU), defectivity, and placement error (PE) is challenging and depends on multiple processes and material parameters. This paper reports the work done using the 300-mm pilot line available in materials to integrate the DSA process on contact and via level patterning. In the first part, a reliable methodology for PE measurement is defined. By tuning intrinsic edge detection parameters on standard reference images, the working window is determined. The methodology is then implemented to analyze the experimental data. The impact of the planarization process on PE and the importance of PE as a complement of CDU and hole open yield for process window determination are discussed.

  9. A Ghost Fluid/Level Set Method for boiling flows and liquid evaporation: Application to the Leidenfrost effect

    NASA Astrophysics Data System (ADS)

    Rueda Villegas, Lucia; Alis, Romain; Lepilliez, Mathieu; Tanguy, Sébastien

    2016-07-01

    The development of numerical methods for the direct numerical simulation of two-phase flows with phase change, in the framework of interface capturing or interface tracking methods, is the main topic of this study. We propose a novel numerical method, which allows dealing with both evaporation and boiling at the interface between a liquid and a gas. Indeed, in some specific situations involving very heterogeneous thermodynamic conditions at the interface, the distinction between boiling and evaporation is not always possible. For instance, it can occur for a Leidenfrost droplet; a water drop levitating above a hot plate whose temperature is much higher than the boiling temperature. In this case, boiling occurs in the film of saturated vapor which is entrapped between the bottom of the drop and the plate, whereas the top of the water droplet evaporates in contact of ambient air. The situation can also be ambiguous for a superheated droplet or at the contact line between a liquid and a hot wall whose temperature is higher than the saturation temperature of the liquid. In these situations, the interface temperature can locally reach the saturation temperature (boiling point), for instance near a contact line, and be cooler in other places. Thus, boiling and evaporation can occur simultaneously on different regions of the same liquid interface or occur successively at different times of the history of an evaporating droplet. Standard numerical methods are not able to perform computations in these transient regimes, therefore, we propose in this paper a novel numerical method to achieve this challenging task. Finally, we present several accuracy validations against theoretical solutions and experimental results to strengthen the relevance of this new method.

  10. A Ghost Fluid/Level Set Method for boiling flows and liquid evaporation: Application to the Leidenfrost effect

    SciTech Connect

    Rueda Villegas, Lucia; Alis, Romain; Lepilliez, Mathieu; Tanguy, Sébastien

    2016-07-01

    The development of numerical methods for the direct numerical simulation of two-phase flows with phase change, in the framework of interface capturing or interface tracking methods, is the main topic of this study. We propose a novel numerical method, which allows dealing with both evaporation and boiling at the interface between a liquid and a gas. Indeed, in some specific situations involving very heterogeneous thermodynamic conditions at the interface, the distinction between boiling and evaporation is not always possible. For instance, it can occur for a Leidenfrost droplet; a water drop levitating above a hot plate whose temperature is much higher than the boiling temperature. In this case, boiling occurs in the film of saturated vapor which is entrapped between the bottom of the drop and the plate, whereas the top of the water droplet evaporates in contact of ambient air. The situation can also be ambiguous for a superheated droplet or at the contact line between a liquid and a hot wall whose temperature is higher than the saturation temperature of the liquid. In these situations, the interface temperature can locally reach the saturation temperature (boiling point), for instance near a contact line, and be cooler in other places. Thus, boiling and evaporation can occur simultaneously on different regions of the same liquid interface or occur successively at different times of the history of an evaporating droplet. Standard numerical methods are not able to perform computations in these transient regimes, therefore, we propose in this paper a novel numerical method to achieve this challenging task. Finally, we present several accuracy validations against theoretical solutions and experimental results to strengthen the relevance of this new method.

  11. Methods for the direct simulation of nanoscale film breakup and contact angles

    NASA Astrophysics Data System (ADS)

    Mahady, Kyle

    This thesis investigates direct simulation of fluids with free surfaces and contact lines, with a focus on capturing nanoscale physics in a continuum based computational framework. Free surfaces and contact lines have long presented some of the most challenging problems in computational fluid dynamics. Extensive progress has been made in recent years, and a wide variety of different methods are currently employed for direct simulation in these contexts. The complexity of the full governing equations for such flows poses significant challenges in terms of analytical techniques, and leads to lengthy computational times for direct simulations. For these reasons, reduced models are preferable in many contexts, even when it is not clear that such reduced models strictly apply. Recent advances in nanotechnology motivate the comparison between direct simulations and reduced models by presenting situations in which each possesses advantages; these experiments involve the deposition of nanoscale flat metallic structures onto a surface with unprecedented precision, the almost instantaneous liquefaction of which leads to new initial liquid configurations which have been previously impossible to achieve in an experimental setup. The mechanisms that lead to the instability of these structures are a combination of classical liquid instability (such as Rayleigh-Plateau), novel capillary instabilities driven by the initial geometry, and nanoscale physics. This study begins by examining the differences in qualitative behavior between direct numerical simulation of the full equations and a particular reduced model in the context of wetting and dewetting of drops. Afterwards, a specific initial liquid geometry is presented, the breakup of which requires direct numerical simulation in order to explain the experimental behavior. A parameter study of this geometry demonstrates that it offers a rich variety of dynamics; the breakup of the geometry is found to result in nanoparticle

  12. A Study of Nucleate Boiling with Forced Convection in Microgravity

    NASA Technical Reports Server (NTRS)

    Merte, Herman, Jr.

    1999-01-01

    purposes. In addition, it is desirable to reduce the number of variables as much as possible in a fundamental study. These considerations dictated the use of a flat heater surface, which is rectangular in shape, 1.91 cm by 3.81 cm (0.75 x 1.5 inches), consisting either of a 400 Angstrom thick semi-transparent gold film sputtered on a quartz substrate which serves simultaneously as a heater and a resistance thermometer, or a copper substrate of the same size. The heater substrate is a disc which can be rotated so that the heated length in the flow direction can be changed from 1.91 to 3.81 cm (0.75 to 1.5 inches). The fluid is R-113, and the velocities can be varied between 0.5 cm/s and 60 cm/s. For a sufficiently low velocity the CHF can be modeled reasonably well at various orientations by the correlation for pool boiling corrected for the influence of bulk liquid subcooling, multiplied by the square root of q, the angle relative to horizontal. This arises from equating buoyancy and drag forces in the inverted positions where the vapor bubbles are held against the heater surface as they slide. A distortion of the measurements relative to pool boiling occurs as the flow velocity increases. In modeling this effect at different levels of subcooling it appeared appropriate to estimate the volumetric rate of vapor generation, using measurements of bubble frequency (or residence time), void fraction and average bubble boundary layer thickness. These were determined with the use of a platinum hot wire probe 0.025 mm in diameter by 1.3 mm long, applying a constant current to distinguish between contact with liquid or vapor. Two-dimensional spatial variations are obtained with a special mechanism to resolve displacements in increments of 0.025 mm. From such measurements it was determined that the fraction of the surface heat transfer resulting in evaporation varies inversely with the subcooling correction factor for the CHF. The measured inverse bubble residence time is normalized

  13. Direct-Contact Low-Frequency Ultrasound Clearance of Biofilm From Metallic Implant Materials

    PubMed Central

    Paribathan, Chaitra; Shanmugam, Mayilvahanan; Ramasubbu, Narayanan

    2017-01-01

    Introduction: Biofilms are recognized as a significant deterrent to wound healing and to the management of exposed or infected surgical implants. Biofilms can be disrupted by a variety of enzymatic and mechanical interventions. This experiment was designed to determine whether direct-contact low-frequency ultrasound has the ability to clear biofilms and what then happens to the released bacteria. Methods: Staphylococcus epidermidis biofilm was grown on the surfaces of metallic discs composed of titanium and stainless steel, comparable with the alloys used in surgical implants. The discs were treated with a control of irrigation and no ultrasound, followed by the ultrasound for a 10 second of exposure at a mid-level power setting. The irrigation materials used was either normal saline or hypochlorous acid. The effluent was cultured to determine colony-forming units, and the discs were stained with crystal violet to determine whether there was a residual biofilm. Results: The biofilm was cleared completely from all discs when treated with direct-contact low-frequency ultrasound. However, the released bacteria were viable and could be cultured from the effluent when saline was used as the irrigation medium. When hypochlorous acid was used as the irrigation medium, there was complete killing of all planktonic bacteria. Conclusion: Direct-contact low-frequency ultrasound is effective when used to clear biofilms from metallic implant materials. By using hypochlorous acid as the irrigant during treatment, all of the bacteria released from the biofilm were killed as well. The implications for clinical application are important and need to be independently studied. PMID:28405263

  14. Direct-Contact Low-Frequency Ultrasound Clearance of Biofilm From Metallic Implant Materials.

    PubMed

    Granick, Mark S; Paribathan, Chaitra; Shanmugam, Mayilvahanan; Ramasubbu, Narayanan

    2017-01-01

    Introduction: Biofilms are recognized as a significant deterrent to wound healing and to the management of exposed or infected surgical implants. Biofilms can be disrupted by a variety of enzymatic and mechanical interventions. This experiment was designed to determine whether direct-contact low-frequency ultrasound has the ability to clear biofilms and what then happens to the released bacteria. Methods:Staphylococcus epidermidis biofilm was grown on the surfaces of metallic discs composed of titanium and stainless steel, comparable with the alloys used in surgical implants. The discs were treated with a control of irrigation and no ultrasound, followed by the ultrasound for a 10 second of exposure at a mid-level power setting. The irrigation materials used was either normal saline or hypochlorous acid. The effluent was cultured to determine colony-forming units, and the discs were stained with crystal violet to determine whether there was a residual biofilm. Results: The biofilm was cleared completely from all discs when treated with direct-contact low-frequency ultrasound. However, the released bacteria were viable and could be cultured from the effluent when saline was used as the irrigation medium. When hypochlorous acid was used as the irrigation medium, there was complete killing of all planktonic bacteria. Conclusion: Direct-contact low-frequency ultrasound is effective when used to clear biofilms from metallic implant materials. By using hypochlorous acid as the irrigant during treatment, all of the bacteria released from the biofilm were killed as well. The implications for clinical application are important and need to be independently studied.

  15. Radiolysis of boiling water

    NASA Astrophysics Data System (ADS)

    Yang, Shuang; Katsumura, Yosuke; Yamashita, Shinichi; Matsuura, Chihiro; Hiroishi, Daisuke; Lertnaisat, Phantira; Taguchi, Mitsumasa

    2016-06-01

    γ-radiolysis of boiling water has been investigated. The G-value of H2 evolution was found to be very sensitive to the purity of water. In high-purity water, both H2 and O2 gases were formed in the stoichiometric ratio of 2:1; a negligible amount of H2O2 remained in the liquid phase. The G-values of H2 and O2 gas evolution depend on the dose rate: lower dose rates produce larger yields. To clarify the importance of the interface between liquid and gas phase for gas evolution, the gas evolution under Ar gas bubbling was measured. A large amount of H2 was detected, similar to the radiolysis of boiling water. The evolution of gas was enhanced in a 0.5 M NaCl aqueous solution. Deterministic chemical kinetics simulation elucidated the mechanism of radiolysis in boiling water.

  16. Identification of the proteins in direct contact with duck globin mRNA.

    PubMed

    Lockard, R E

    1987-07-27

    Proteins in direct contact with translationally active and repressed duck globin mRNA were determined by irradiating blood or lysates with ultraviolet light. Cross-linked proteins from polyribosomes and free mRNP particles were 14C-labeled by reductive methylation and identified on SDS-polyacrylamide gels upon autoradiography. Results indicate that ten cross-linked proteins are common to both polysomal and free mRNP, however, a 44 kDa protein appears to be specific for repressed mRNP particles. Furthermore, the notable lack of cross-linked proteins in the 20-30 kDa range in free mRNP supports the view that the characteristic low molecular mass 'prosomal' proteins, previously found associated with translationally repressed duck globin free mRNP [(1984) EMBO J. 3, 29-34], do not interact directly with the mRNA molecule.

  17. Stability analysis of direct contact heat exchangers subject to system perturbations. Final report, Task 2

    SciTech Connect

    Jacobs, H.R.

    1985-01-01

    This report includes a project summary, copies of two papers resulting from the work and the Ph.D. Dissertation of Dr. Mehdi Golafshani entitled, ''Stability of a Direct Contact Heat Exchanger''. Specifically, the work deals with the operational stability of a spray column type heat exchanger subject to disturbances typical of those which can occur for geothermal applications. A computer program was developed to solve the one-dimensional transient two-phase flow problem and it was applied to the design of a spray column. The operation and design of the East Mesa 500kW/sub e/ direct contactor was assessed. It is shown that the heat transfer is governed by the internal resistance of the dispersed phase. In fact, the performance is well-represented by diffusion of heat within the drops. 5 refs.

  18. Thermal analysis of a solar pond power plant operated with a direct contact boiler

    NASA Astrophysics Data System (ADS)

    Sonn, A.; Letan, R.

    1981-11-01

    A solar pond power plant operated with a direct contact boiler was thermally analyzed. A binary cycle system of concentrated brine, and an organic working fluid were considered. Brine temperature of 80 C, condensation at 30 C, a 75 percent efficient turbine, and 70 percent efficient pumps were specified for the analysis. The current study involved six working fluids: butane, pentane, hexane, and freons R113, R114, R12. Each of these fluids exhibited a maximum efficiency of the system at characteristic operating conditions of the boiler. The system efficiency increased as the boiler pressure approached that of the pond. Net electrical outputs of 7-9 percent of the heat inputs were obtained for the low pressure fluids, such as pentane, hexane, and R113. Gravity flow of brine to boiler increased these values to 8-11 percent. Solute losses in brine by direct contact in boiler were estimated for pentane, as 125 kg per year per sq km of pond, or 63 kg/MWe-year. Similar orders of magnitude are obtained for the other fluids.

  19. Direct soil contact values for ecological receptors exposed to weathered petroleum hydrocarbon (PHC) fraction 2.

    PubMed

    Angell, Robin A; Kullman, Steve; Shrive, Emma; Stephenson, Gladys L; Tindal, Miles

    2012-11-01

    Ecological tier 1 Canada-wide standards (CWS) for petroleum hydrocarbon (PHC) fraction 2 (F2; >nC10-C16) in soil were derived using ecotoxicological assessment endpoints (effective concentrations [ECs]/lethal concentrations [LCs]/inhibitory concentrations, 25% [IC25s]) with freshly spiked (fresh) fine- and coarse-grained soils. These soil standards might be needlessly conservative when applied to field samples with weathered hydrocarbons. The purpose of the present study was to assess the degradation and toxicity of weathered PHC F2 in a fine-grained soil and to derive direct soil contact values for ecological receptors. Fine-grained reference soils were spiked with distilled F2 and weathered for 183 d. Toxicity tests using plants and invertebrates were conducted with the weathered F2-spiked soils. Endpoint EC/IC25s were calculated and used to derive soil standards for weathered F2 in fine-grained soil protective of ecological receptors exposed via direct soil contact. The values derived for weathered F2 were less restrictive than current ecological tier 1 CWS for F2 in soil.

  20. Predicting transmembrane helix packing arrangements using residue contacts and a force-directed algorithm.

    PubMed

    Nugent, Timothy; Jones, David T

    2010-03-19

    Alpha-helical transmembrane proteins constitute roughly 30% of a typical genome and are involved in a wide variety of important biological processes including cell signalling, transport of membrane-impermeable molecules and cell recognition. Despite significant efforts to predict transmembrane protein topology, comparatively little attention has been directed toward developing a method to pack the helices together. Here, we present a novel approach to predict lipid exposure, residue contacts, helix-helix interactions and finally the optimal helical packing arrangement of transmembrane proteins. Using molecular dynamics data, we have trained and cross-validated a support vector machine (SVM) classifier to predict per residue lipid exposure with 69% accuracy. This information is combined with additional features to train a second SVM to predict residue contacts which are then used to determine helix-helix interaction with up to 65% accuracy under stringent cross-validation on a non-redundant test set. Our method is also able to discriminate native from decoy helical packing arrangements with up to 70% accuracy. Finally, we employ a force-directed algorithm to construct the optimal helical packing arrangement which demonstrates success for proteins containing up to 13 transmembrane helices. This software is freely available as source code from http://bioinf.cs.ucl.ac.uk/memsat/mempack/.

  1. Predicting Transmembrane Helix Packing Arrangements using Residue Contacts and a Force-Directed Algorithm

    PubMed Central

    Nugent, Timothy; Jones, David T.

    2010-01-01

    Alpha-helical transmembrane proteins constitute roughly 30% of a typical genome and are involved in a wide variety of important biological processes including cell signalling, transport of membrane-impermeable molecules and cell recognition. Despite significant efforts to predict transmembrane protein topology, comparatively little attention has been directed toward developing a method to pack the helices together. Here, we present a novel approach to predict lipid exposure, residue contacts, helix-helix interactions and finally the optimal helical packing arrangement of transmembrane proteins. Using molecular dynamics data, we have trained and cross-validated a support vector machine (SVM) classifier to predict per residue lipid exposure with 69% accuracy. This information is combined with additional features to train a second SVM to predict residue contacts which are then used to determine helix-helix interaction with up to 65% accuracy under stringent cross-validation on a non-redundant test set. Our method is also able to discriminate native from decoy helical packing arrangements with up to 70% accuracy. Finally, we employ a force-directed algorithm to construct the optimal helical packing arrangement which demonstrates success for proteins containing up to 13 transmembrane helices. This software is freely available as source code from http://bioinf.cs.ucl.ac.uk/memsat/mempack/. PMID:20333233

  2. Analyzing and modeling the dynamic thermal behaviors of direct contact condensers packed with PCM spheres

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Hu, Tao; Hassabou, Abdel H.; Spinnler, Markus; Polifke, Wolfgang

    2013-01-01

    Condensers serve as important components for humidification-dehumidification (HDH) desalination plants. Based on the interpenetration continua approach with volume averaging technique, a mathematical dynamic model for analyzing the heat and mass transfer within direct contact condensers with co-current or countercurrent flow arrangement was developed. It was validated against the experimental data from a small scale HDH desalination system. Comparisons including the productivities and the temperature profiles of gas, liquid, and solid phases show good agreement with the measurements. Phase change material (PCM) melting processes have little effect on water production rate for co-current flow arrangement, but the condenser packed with PCM capsules have higher water production rates than that packed with air capsules packed under given conditions. The relative humidity profile of the bulk gas shows contrary trend with the gas temperature profile. The direct contact condenser with countercurrent flow arrangement can provide much better heat and mass transfer between gas and water and produce about 16.3% more fresh water than the same condenser with co-current flow arrangement in 4 h under given conditions.

  3. The Driving Force of Frost Boils and Hummocks Formation

    NASA Astrophysics Data System (ADS)

    Shur, Y.; Ping, C.

    2003-12-01

    Formation of frost boils has several aspects to be explained, including the bowl shape of boils, the formation of an organic layer at the periphery of the frost boils, the elevated center of the boils, and resistance of the soil surface to vegetation colonization. Genesis of frost boils and hummocks have been widely attributed to cryoturbation-a complex of seasonally interchanging processes of frost heave and thaw settlement. Existing hypotheses, however, do not consider changes in the upper permafrost as factors of frost boil and hummock formation. Most of features listed above cannot be explained by reversible seasonal changes in the active layer. Frost boils and inter-boil areas form a well-organized and long-term functioning system closely linked to upper permafrost dynamics. Formation of this system starts with the occurrence of vegetation in inter-boil areas in shallow thermal cracks limited by the thickness of the active layer. Vegetation and its decomposition change the thermal properties of the active layer that steadily decreases with formation of aggradational ice and perennial frost heave beneath vegetated inter-boils. Due to the three-dimensional nature of the freezing front, frost heave in inter-boil areas is not perpendicular to the soil surface but is inclined in the direction of the boils, thus forming the bowl shape of boils. The organic matter formed in inter-boil areas intrudes under boils due to formation of frost cracks and thawing of ice lenses and layers at the bottom of the active layer. Penetration of organics along the active layer - permafrost boundary from an inter-boil area leads to formation of additional aggradational ice in the intermediate layer at the top of the permafrost accompanying the intruding organics. This aggradational process reinforces the bowl shape of frost-boils. Accumulation of organic matter at the lower part of the active layer leads to a decrease in active-layer thickness under the boils, which in turn leads to

  4. Short Contact Time Direct Coal Liquefaction Using a Novel Batch Reactor

    SciTech Connect

    He Huang; Michael T. Klein; William H. Calkins

    1997-04-03

    The primary objective of this research is to optimize the design and operation of the bench scale batch reactor (SCTBR) for studying direct coal liquefaction at short contact times (.01 to 10 minutes or longer) . An additional objective is to study the kinetics of direct coal liquefaction particularly at short reaction times. Both of these objectives have been nearly achieved, however this work has shown the great importance of the liquefaction solvent characteristics and the solvent-catalyst interaction on the liquefaction process. This has prompted us to do a preliminary investigation of solvents and the solvent-catalyst systems in coal liquefaction. SUMMARY AND CONCLUSIONS 1) Conversion vs time data have been extended to 5 coals of ranks from lignite to low volatile bituminous coal. A broad range of reaction rates have been observed with a maximum in the high volatile bituminous range. 2) A series of direct coal liquefaction runs have been made using a range of nitrogen containing solvents that given high liquefaction conversions of coal. These runs are now being analyzed. 3) The coalification process has been shown by TGA to go through an intermediate stage which may account for the greater reactivity of bituminous coals in the direct coal liquefaction process. 4) It was shown that coal rank can be accurately determined by thermogravimetric analysis

  5. Steady State Vapor Bubble in Pool Boiling

    PubMed Central

    Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C.; Maroo, Shalabh C.

    2016-01-01

    Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics. PMID:26837464

  6. Steady State Vapor Bubble in Pool Boiling.

    PubMed

    Zou, An; Chanana, Ashish; Agrawal, Amit; Wayner, Peter C; Maroo, Shalabh C

    2016-02-03

    Boiling, a dynamic and multiscale process, has been studied for several decades; however, a comprehensive understanding of the process is still lacking. The bubble ebullition cycle, which occurs over millisecond time-span, makes it extremely challenging to study near-surface interfacial characteristics of a single bubble. Here, we create a steady-state vapor bubble that can remain stable for hours in a pool of sub-cooled water using a femtosecond laser source. The stability of the bubble allows us to measure the contact-angle and perform in-situ imaging of the contact-line region and the microlayer, on hydrophilic and hydrophobic surfaces and in both degassed and regular (with dissolved air) water. The early growth stage of vapor bubble in degassed water shows a completely wetted bubble base with the microlayer, and the bubble does not depart from the surface due to reduced liquid pressure in the microlayer. Using experimental data and numerical simulations, we obtain permissible range of maximum heat transfer coefficient possible in nucleate boiling and the width of the evaporating layer in the contact-line region. This technique of creating and measuring fundamental characteristics of a stable vapor bubble will facilitate rational design of nanostructures for boiling enhancement and advance thermal management in electronics.

  7. Microheater Array Boiling Experiment

    NASA Technical Reports Server (NTRS)

    Kim, Jungho; McQuillen, John; Balombin, Joe

    2002-01-01

    By conducting pool boiling tests in microgravity, the effect of buoyancy on the overall boiling process and the relative magnitude of other phenomena can be assessed. Data from KC-135 and sounding rocket experiments indicate little effect of gravity on boiling heat transfer at wall superheats below 25 C, despite vast differences in bubble behavior between gravity levels. In microgravity, a large primary bubble, surrounded by smaller satellite bubbles, moved over the surface, occasionally causing nucleation. Once formed, the primary bubble size remained constant for a given superheat, indicating evaporation at the bubble base is balanced with condensation on the bubble cap. The primary bubble's size increased with wall superheat. Most heaters under the primary bubble had low heat transfer rates, suggesting liquid dryout. Strong Marangoni convection developed in microgravity, forming a 'jet' into the bulk liquid that forced the bubble onto the heater. An experiment is being designed for the. Microgravity Science Glovebox. This experiment uses two 96 element microheater arrays, 2.7 and 7.0 mm in size. These heaters are individually controlled to operate at a constant temperature, measuring local heat fluxes as a function of time and space. Most boiling experiments operate at constant wall heat flux with larger heaters, allowing only time and space-averaged measurements. Each heater is about the bubble departure size in normal gravity, but significantly smaller than the bubble departure size in reduced gravity.

  8. The effect of direct and indirect force transmission on peri-implant bone stress - a contact finite element analysis.

    PubMed

    Rand, Annike; Stiesch, Meike; Eisenburger, Michael; Greuling, Andreas

    2017-08-01

    In almost all finite element (FE) studies in dentistry, virtual forces are applied directly to dentures. The purpose of this study was to develop a FE model with non-linear contact simulation using an antagonist as force transmitter and to compare this with a similar model that uses direct force transmission. Furthermore, five contact situations were created in order to examine their influence on the peri-implant bone stresses, which are relevant to the survival rate of implants. It was found that the peri-implant bone stresses were strongly influenced by the kind of force transmission and contact number.

  9. Fabrication of bioinspired composite nanofiber membranes with robust superhydrophobicity for direct contact membrane distillation.

    PubMed

    Liao, Yuan; Wang, Rong; Fane, Anthony G

    2014-06-03

    The practical application of membrane distillation (MD) for water purification is hindered by the absence of desirable membranes that can fulfill the special requirements of the MD process. Compared to the membranes fabricated by other methods, nanofiber membranes produced by electrospinning are of great interest due to their high porosity, low tortuosity, large surface pore size, and high surface hydrophobicity. However, the stable performance of the nanofiber membranes in the MD process is still unsatisfactory. Inspired by the unique structure of the lotus leaf, this study aimed to develop a strategy to construct superhydrophobic composite nanofiber membranes with robust superhydrophobicity and high porosity suitable for use in MD. The newly developed membrane consists of a superhydrophobic silica-PVDF composite selective skin formed on a polyvinylidene fluoride (PVDF) porous nanofiber scaffold via electrospinning. This fabrication method could be easily scaled up due to its simple preparation procedures. The effects of silica diameter and concentration on membrane contact angle, sliding angle, and MD performance were investigated thoroughly. For the first time, the direct contact membrane distillation (DCMD) tests demonstrate that the newly developed membranes are able to present stable high performance over 50 h of testing time, and the superhydrophobic selective layer exhibits excellent durability in ultrasonic treatment and a continuous DCMD test. It is believed that this novel design strategy has great potential for MD membrane fabrication.

  10. Sediment contact test with Potamopyrgus antipodarum in effect-directed analyses-challenges and opportunities.

    PubMed

    Schmitt, Claudia; Vogt, Christian; Machala, Miroslav; de Deckere, Eric

    2011-09-01

    Effect-directed analysis is increasingly used for the identification of key toxicants in environmental samples and there is a growing need for in vivo biotests as diagnostic tools. Within this study, we performed an in vivo sediment contact test, applicable on both native field samples and their extracts or fractions, in order to be able to compare the results from both field and laboratory studies. A sediment contact test with the prosobranch snail, Potamopyrgus antipodarum, was carried out on extracts and fractions of field sediments from three European river basins. The results were compared with previous results of the native field samples. In contrast to the native sediments, the extracts of the samples led to an overall decrease in reproduction. Even the chosen reference sites had an adverse effect on the snails' reproduction. It appeared that a higher bioavailability in the organic extracts, together with a changing composition of compounds could have lead to this change in effects. The fractionation of the extracts partly led to a more differentiated picture, but the resolution was not high enough to see any distinct effects on the snails' reproduction. Our results highlight the importance of the use of in vivo biotests and point out the relevance of bioavailability in native sediments. For further fractionation studies, a more realistic extraction procedure, together with a higher resolution fractionation, would be appropriate in order to separate individual bioavailable compounds more efficient.

  11. Direct cell-cell contact with the vascular niche maintains quiescent neural stem cells

    PubMed Central

    Ottone, Cristina; Krusche, Benjamin; Whitby, Ariadne; Clements, Melanie; Quadrato, Giorgia; Pitulescu, Mara E.; Adams, Ralf H.; Parrinello, Simona

    2014-01-01

    The vasculature is a prominent component of the subventricular zone neural stem cell niche. Although quiescent neural stem cells physically contact blood vessels at specialised endfeet, the significance of this interaction is not understood. In contrast, it is well established that vasculature-secreted soluble factors promote lineage progression of committed progenitors. Here we specifically investigated the role of cell-cell contact-dependent signalling in the vascular niche. Unexpectedly, we find that direct cell-cell interactions with endothelial cells enforces quiescence and promotes stem cell identity. Mechanistically, endothelial ephrinB2 and Jagged1 mediate these effects by suppressing cell-cycle entry downstream of mitogens and inducing stemness genes to jointly inhibit differentiation. In vivo, endothelial-specific ablation of either of the genes which encode these proteins, Efnb2 and Jag1 respectively, aberrantly activates quiescent stem cells, resulting in depletion. Thus, we identify the vasculature as a critical niche compartment for stem cell maintenance, furthering our understanding of how anchorage to the niche maintains stem cells within a pro-differentiative microenvironment. PMID:25283993

  12. Moisture Battery Formed by Direct Contact of Magnesium with Foamed Polyaniline.

    PubMed

    Xie, Pu; Rong, Min Zhi; Zhang, Ming Qiu

    2016-01-26

    The present communication reports a concept battery made by direct contact of magnesium foil with ultralight polyaniline (PANI) foam in the absence of additional electrolyte. Electrical current is allowed to be steadily released from the junction with a specific energy of 646 mWh g(-1) and specific capacity of 1247 mAh g(-1). Additionally, the battery offers an environmentally friendly route of hydrogen production along with discharging. Mechanistic studies indicated that the ubiquitous galvanic corrosion combined with decomposition of adsorbed trace water in the semi-conducting polymer foam enabled the generation of electricity, which overturns the traditional view. The higher moisture level is conducive to the discharge. This work is believed to open up new possibilities for the design of electrochemical batteries.

  13. Development of a Direct Contact Heat Exchanger, Phase 1 Study Report

    NASA Technical Reports Server (NTRS)

    Manvi, R.

    1978-01-01

    Electric power generation from geothermal brine requires, first, bringing the hot brine to the surface and then converting the heat to electric power. Binary conversion schemes were proposed, with the heat transfer between the brine and the working organic fluid taking place in a conventional tube and shell heat exchanger. If the brine is heavily laden with dissolved solids, however, solids buildup on the heat exchanger surfaces leads to a considerable degree of fouling and an accompanying drop in performance is experienced. A possible solution to this problem is the use of a direct contact exchanger with the secondary fluid power cycle. The proposed concept involves the formation of fluid sheets and bells as heat angles. Results of a study concerning the fluid mechanics of such surfaces are given.

  14. Atomic-Scale Engineering of Abrupt Interface for Direct Spin Contact of Ferromagnetic Semiconductor with Silicon

    NASA Astrophysics Data System (ADS)

    Averyanov, Dmitry V.; Karateeva, Christina G.; Karateev, Igor A.; Tokmachev, Andrey M.; Vasiliev, Alexander L.; Zolotarev, Sergey I.; Likhachev, Igor A.; Storchak, Vyacheslav G.

    2016-03-01

    Control and manipulation of the spin of conduction electrons in industrial semiconductors such as silicon are suggested as an operating principle for a new generation of spintronic devices. Coherent injection of spin-polarized carriers into Si is a key to this novel technology. It is contingent on our ability to engineer flawless interfaces of Si with a spin injector to prevent spin-flip scattering. The unique properties of the ferromagnetic semiconductor EuO make it a prospective spin injector into silicon. Recent advances in the epitaxial integration of EuO with Si bring the manufacturing of a direct spin contact within reach. Here we employ transmission electron microscopy to study the interface EuO/Si with atomic-scale resolution. We report techniques for interface control on a submonolayer scale through surface reconstruction. Thus we prevent formation of alien phases and imperfections detrimental to spin injection. This development opens a new avenue for semiconductor spintronics.

  15. Non-contact direct measurement of the magnetocaloric effect in thin samples

    SciTech Connect

    Cugini, F. Porcari, G.; Solzi, M.

    2014-07-15

    An experimental setup, based on a non-contact temperature sensor, is proposed to directly measure the magnetocaloric effect of samples few micrometers thick. The measurement of the adiabatic temperature change of foils and ribbons is fundamental to design innovative devices based on magnetocaloric thin materials or micro-structuring bulk samples. The reliability of the proposed setup is demonstrated by comparing the measurements performed on a bulk gadolinium sample with the results obtained by an experimental setup based on a Cernox bare chip thermoresistance and by in-field differential scanning calorimetry. We show that this technique can measure the adiabatic temperature variation on gadolinium sheets as thin as 27 μm. Heat transfer simulations are added to describe the capability of the presented technique.

  16. A numerical study of the direct contact condensation on a horizontal surface

    NASA Technical Reports Server (NTRS)

    Hasan, M. M.; Lin, C. S.

    1991-01-01

    The results of a numerical study of the direct contact condensation on a slowly moving horizontal liquid surface are presented. The geometrical configuration and the input conditions used to obtain numerical solutions are representative to those of experiments of Celata et al. The effects of Prandtl number (Pr), inflow Reynolds number, and Richardson number on the condensation rate are investigated. Numerical predictions of condensation rate for laminar flow are in good agreement with experimental data. The effect of buoyancy on the condensation rate is characterized by Richardson number. A correlation based on the numerical solutions is developed to predict the average condensation Nusselt number in terms of Richardson number, Peclet number, and inflow Reynolds number.

  17. Atomic-Scale Engineering of Abrupt Interface for Direct Spin Contact of Ferromagnetic Semiconductor with Silicon

    PubMed Central

    Averyanov, Dmitry V.; Karateeva, Christina G.; Karateev, Igor A.; Tokmachev, Andrey M.; Vasiliev, Alexander L.; Zolotarev, Sergey I.; Likhachev, Igor A.; Storchak, Vyacheslav G.

    2016-01-01

    Control and manipulation of the spin of conduction electrons in industrial semiconductors such as silicon are suggested as an operating principle for a new generation of spintronic devices. Coherent injection of spin-polarized carriers into Si is a key to this novel technology. It is contingent on our ability to engineer flawless interfaces of Si with a spin injector to prevent spin-flip scattering. The unique properties of the ferromagnetic semiconductor EuO make it a prospective spin injector into silicon. Recent advances in the epitaxial integration of EuO with Si bring the manufacturing of a direct spin contact within reach. Here we employ transmission electron microscopy to study the interface EuO/Si with atomic-scale resolution. We report techniques for interface control on a submonolayer scale through surface reconstruction. Thus we prevent formation of alien phases and imperfections detrimental to spin injection. This development opens a new avenue for semiconductor spintronics. PMID:26957146

  18. A topographically modified substrate-embedded MEA for directed myotube formation at electrode contact sites.

    PubMed

    Langhammer, Christopher G; Kutzing, Melinda K; Luo, Vincent; Zahn, Jeffrey D; Firestein, Bonnie L

    2013-02-01

    Myoblast fusion into functionally distinct myotubes, and their subsequent integration with the nervous system, is a poorly understood phenomenon with important applications in basic science research, skeletal muscle tissue engineering, and cell-based biosensor development. We have previously demonstrated the ability of microelectrode arrays (MEAs) to record the extracellular action potentials of myotubes, and we have shown that this information reveals the presence of multiple, electrophysiologically independent myotubes even in unstructured cultures where there is extensive physical contact between cells (Langhammer et al., Biotechnol Prog 27:891-895, 2011). In this paper, we explore the ability of microscale topographical trenches to guide the myoblast alignment and fusion processes and use our findings to create a substrate-embedded MEA containing topographical trenches that are able to direct myotube contractility to specific locations. By combining substrate-embedded MEA technology with topographical patterns, we have developed a lab-on-a-chip test bed for the non-invasive examination of myotubes.

  19. Dehumidification of Moist Air by Direct Contact Heat and Mass Transfer in Cold Water Solution

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Horibe, Akihiko; Haruki, Naoto; Ishioka, Tohru; Takeuchi, Yoshiyuki

    This paper has dealt with the direct contact heat and mass transfer characteristics of dehumidification of flowing moist air bubbles in a cold water solution (propylene glycoI). The saturated water-vapor humidity of propylene glycol water solution was measured under some conditions of temperature and mass concentration of the water solution. Experiments on dehumidification of air bubbles were performed by ascending air bubbles in the water absorbing solution for various parameters of air temperature, humidity and flow rate etc. The experimental data of air bubble diameter, dehumidification rate and apparent heat transfer coefficient were correlated by means of some experimental parameters such as air temperature, humidity, flow rate and height of water solution layer.

  20. Contact Hole Shrinking of Directed Self-Assembly and Its Application Based on Simulation Approach.

    PubMed

    Kim, Sang-Kon

    2015-10-01

    Directed self-assembly (DSA) of block copolymers (BCPs) has become an intense field of study as a complementary technique to conventional lithography for 1×-nm semiconductor patterning. DSA contact hole (C/H) shrinking is a possible implemental technique in the DSA process. In this paper, a DSA C/H shrinking is fully modeled and simulated by using a self-consistent field theory (SCFT). Simulation results show good agreement with experiment results. In terms of this simulation, the potential of DSA C/H shrinking with thermal reflow is integrated into the conventional CMOS lithography process in order to achieve high resolution and pattern density multiplication at a low cost. The optical proximity correction (OPC) of DSA C/H shrinking due to prepattern C/H and pitch can increase process window for DSA C/H shrinking.

  1. Direct contact membrane inoculation of yeasts and moulds for evaluating preservative efficacy in solid cosmetics.

    PubMed

    Tran, T T; Collier, S W

    1992-08-01

    Synopsis A direct contact membrane inoculation technique for yeasts and moulds was used to evaluate the preservation efficacy and antimicrobial activity of Germall 115 and Germall II in pressed eye shadows. Test organisms on membrane filters were placed in direct contact with cosmetics at room temperature under humid conditions. Growth on membranes was removed daily, or as appropriate, and cultured on potato dextrose agar containing lecithin and Tween 80. Linear regression analysis was used to determine product preservation efficacy. Average D values of 1 and 3 days for Candida albicans American Type Culture Collection (ATCC) 10231 and 17 and 29 days for Aspergillus niger ATCC 16404 were obtained on two eye shadows we prepared (in-house eye shadows) with parabens and either Germall II or Germall 115 as preservatives. A decimal reduction time (D value) of 6-7 days was calculated for the yeast on a commercial eye shadow preserved with parabens and Germall 115. A. niger multiplied on six of seven replicates of this commercial product to attain a nearly 3 log(10) increase in 20 days. On one replicate, A. niger showed a 1 log(10) increase in the first 10 days, and then decreased linearly (r =- 0.95) to <10 colony-forming units per membrane by day 24. The method used with C. albicans and A. niger was then used with bacteria. The method was sensitive enough to differentiate the antimicrobial activity of the Germall 115 and Germall II against fungi but not against bacteria. The in-house and commercial products were preserved most effectively against the three bacteria tested and least effectively against the mould.

  2. Direct visualization of tear film on soft contact lens using ultra-high resolution spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wang, Jianhua; Jiao, Shuliang; Ruggeri, Marco; Wehbe, Hassan M.

    2008-02-01

    The integrity of the tear film on the surface of contact lenses is essential to maintaining visual clarity and the overall health of the superficial structures of the eye (cornea and conjunctiva) for contact lens wearers. It is very critical to evaluate pre- and post-lens tear films in contact lens practice to make sure the lens is properly fitted. Improper lens fitting may cause ocular discomfort, visual distortion and ocular infection. It is very often for soft contact lens wearers to experience dry eye, especially in the afternoon after wearing the lens for a period of time. Dry eye has been a common cause of contact lens drop-off. There is currently no method available to directly visualize the tears on and underneath the contact lens in situ on human eye, mainly due to the extremely difficulty in imaging the micrometer-thin tear layer. An ultra-high resolution spectral domain optical coherence tomography has been developed with a telecentric light delivery system mounted with a slit-lamp. The system has a 3 micrometer depth resolution with a scan width up to 15 mm. The system was used to image soft contact lenses on the human eye. For the first time to our knowledge, tear films on the center and edge of the soft contact lens were directly visualized in vivo.

  3. Direct Measurement of Quantum Confinement and Environmental Pinning Effects on Metal/Nanostructure Schottky Contacts

    NASA Astrophysics Data System (ADS)

    Tivarus, Cristian

    2005-03-01

    I will discuss direct nm-resolution measurements of metal/quantum well (QW) Schottky contacts made using Cross- sectional Ballistic Electron Emission Microscopy (XBEEM), in order to quantify the influence of small-size effects on hot- carrier injection into semiconductor nanostructures. Molecular Beam Epitaxy was used to grow a sequence of GaAs QWs with width varying from 1nm to 15 nm, separated by thick Al0.3Ga0.7As barrier layers. The samples were cleaved ex-situ and polycrystalline Au contacts were electron-beam evaporated on the cleaved edge using shadow mask or photo-lithography. Samples were studied in ultra-high vacuum using Scanning Tunneling Microscopy and XBEEM. The Schottky barrier height over the QWs was found to systematically increase with decreasing QW width, by up to ˜140 meV for the 1 nm QW. This is mostly due to a large quantum-confinement increase ( up to ˜200 meV) of the QW conduction band minimum (CBM), as estimated by a simple 1D QW model. We also did finite element electrostatic modeling to estimate the ``environmental" effects of the surrounding metal/Al0.3Ga0.7As interface on the QW CBM. Excellent quantitative agreement over the full QW width range is obtained when both quantum confinement and electrostatic effects are considered.I will also discuss on-going measurements to use the metal/QW nanocontacts as unique ``nano-apertures" to directly image and quantify the lateral hot-electron spreading profile in the metal film. This profile is surprisingly large, with a FWHM of ˜15nm (˜21nm) for a 4nm (7nm) thick Au film. XBEEM images directly show that hot-electron spreading is strongly modified by the grain structure in the metal film. In collaboration with J.P. Pelz, M.K. Hudait, and S.A. Ringel. Work supported by NSF and ONR

  4. Geysering in boiling channels

    SciTech Connect

    Aritomi, Masanori; Takemoto, Takatoshi; Chiang, Jing-Hsien

    1995-09-01

    A concept of natural circulation BWRs such as the SBWR has been proposed and seems to be promising in that the primary cooling system can be simplified. The authors have been investigating thermo-hydraulic instabilities which may appear during the start-up in natural circulation BWRs. In our previous works, geysering was investigated in parallel boiling channels for both natural and forced circulations, and its driving mechanism and the effect of system pressure on geysering occurrence were made clear. In this paper, geysering is investigated in a vertical column and a U-shaped vertical column heated in the lower parts. It is clarified from the results that the occurrence mechanism of geysering and the dependence of system pressure on geysering occurrence coincide between parallel boiling channels in circulation systems and vertical columns in non-circulation systems.

  5. Cell damage in vitro following direct contact with fine particles of titanium, titanium alloy and cobalt-chrome-molybdenum alloy.

    PubMed

    Evans, E J

    1994-07-01

    Fibroblastic cells in vitro were exposed to powders of titanium, titanium-aluminium-vanadium alloy and cobalt-chrome-molybdenum (Co-Cr-Mo) alloy, either in direct contact with the cells or separated from the cells by a microporous membrane. Fine particles of all the materials reduced cell growth when in direct contact with cells, but only the finest particles of Co-Cr-Mo alloy caused cell damage through the microporous membrane. This provides further evidence that there is a mechanism of cell damage in vitro which depends on a direct interaction between cells and particles and is largely independent of the chemical nature of the particle.

  6. 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.

  7. 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.

  8. Oscillate boiling from microheaters

    NASA Astrophysics Data System (ADS)

    Li, Fenfang; Gonzalez-Avila, S. Roberto; Nguyen, Dang Minh; Ohl, Claus-Dieter

    2017-01-01

    We report about an intriguing boiling regime occurring for small heaters embedded on the boundary in subcooled water. The microheater is realized by focusing a continuous wave laser beam to about 10 μ m in diameter onto a 165-nm-thick layer of gold, which is submerged in water. After an initial vaporous explosion a single bubble oscillates continuously and repeatedly at several 100 kHz albeit with constant laser power input. The microbubble's oscillations are accompanied with bubble pinch-off, leading to a stream of gaseous bubbles in the subcooled water. The self-driven bubble oscillation is explained with a thermally kicked oscillator caused by surface attachment and by the nonspherical collapses. Additionally, Marangoni stresses induce a recirculating streaming flow which transports cold liquid towards the microheater, reducing diffusion of heat along the substrate and therefore stabilizing the phenomenon to many million cycles. We speculate that this oscillate boiling regime may overcome the heat transfer thresholds observed during the nucleate boiling crisis and offers a new pathway for heat transfer under microgravity conditions.

  9. Transition boiling heat transfer and the film transition regime

    NASA Technical Reports Server (NTRS)

    Ramilison, J. M.; Lienhard, J. H.

    1987-01-01

    The Berenson (1960) flat-plate transition-boiling experiment has been recreated with a reduced thermal resistance in the heater, and an improved access to those portions of the transition boiling regime that have a steep negative slope. Tests have been made in Freon-113, acetone, benzene, and n-pentane boiling on horizontal flat copper heaters that have been mirror-polished, 'roughened', or teflon-coated. The resulting data reproduce and clarify certain features observed by Berenson: the modest surface finish dependence of boiling burnout, and the influence of surface chemistry on both the minimum heat flux and the mode of transition boiling, for example. A rational scheme of correlation yields a prediction of the heat flux in what Witte and Lienhard (1982) previously identified as the 'film-transition boiling' region. It is also shown how to calculate the heat flux at the boundary between the pure-film, and the film-transition, boiling regimes, as a function of the advancing contact angle.

  10. Transition boiling heat transfer and the film transition regime

    NASA Technical Reports Server (NTRS)

    Ramilison, J. M.; Lienhard, J. H.

    1987-01-01

    The Berenson (1960) flat-plate transition-boiling experiment has been recreated with a reduced thermal resistance in the heater, and an improved access to those portions of the transition boiling regime that have a steep negative slope. Tests have been made in Freon-113, acetone, benzene, and n-pentane boiling on horizontal flat copper heaters that have been mirror-polished, 'roughened', or teflon-coated. The resulting data reproduce and clarify certain features observed by Berenson: the modest surface finish dependence of boiling burnout, and the influence of surface chemistry on both the minimum heat flux and the mode of transition boiling, for example. A rational scheme of correlation yields a prediction of the heat flux in what Witte and Lienhard (1982) previously identified as the 'film-transition boiling' region. It is also shown how to calculate the heat flux at the boundary between the pure-film, and the film-transition, boiling regimes, as a function of the advancing contact angle.

  11. Influence of direct or indirect contact for the cytotoxicity and blood compatibility of spider silk.

    PubMed

    Kuhbier, J W; Coger, V; Mueller, J; Liebsch, C; Schlottmann, F; Bucan, V; Vogt, P M; Strauss, S

    2017-08-01

    Spider silk became one of the most-researched biomaterials in the last years due to its unique mechanical strength and most favourable chemical composition for tissue engineering purposes. However, standardized analysis of cytocompatibility is missing. Therefore, the aim of this study was to investigate hemolysis, cytotoxicity of native spider silk as well as influences on the cell culture medium. Changes of cell culture medium composition, osmolarity as well as glucose and lactate content were determined via ELISA measurement. Possible hemolysis and cytotoxicity in vitro of spider silk were performed via measurement of hemoglobin release of human red blood cells or relative metabolic activity of L929 fibroblasts, respectively, according to international standard procedures. In ELISA measurement, no significant changes in medium composition could be found in this study. Spider silk was not hemolytic in direct and indirect testing. However, a borderline cytotoxicity according to definitions was found in indirect cytotoxicity testing. Nevertheless, in direct cytotoxicity testing, relative metabolic activity measurement revealed that spider silk is not cytotoxic under these conditions. This is the first study to conduct standardized tests regarding cytotoxicity and hemolysis of native spider silk, which might be considered inert in cell culture. As neither hemolysis nor cytotoxicity was found in direct contact in standardized procedures, safety in biomedical applications may be assumed. The indirect cytotoxicity seems to play a minor role in vivo. However, a borderline toxicity was revealed, suggesting potential leachables not yet identified. Displays one of the weaving frames used in this study after seeding with the single drop technique described herein.

  12. Short contact time direct coal liquefaction using a novel batch reactor. Progress report, September 27, 1993--December 31, 1993

    SciTech Connect

    Klein, M.T.; Calkins, W.H.

    1994-01-19

    The objective for this research is to optimize the design and operation of the bench scale batch reactor (STBR) for coat liquefaction at short contact times (0.01 to 10 minutes). This reactor is simple and low enough in cost to serve as a suitable replacement for the traditional tubing-bomb reactors for coal liquefaction and other high-pressure, high-temperature reaction studies. The details of the reactor system are shown in Figure 2. The heating bath used is a Techne IFB-52 industrial fluidized sand bath, which maintains a reaction temperature of {plus_minus}2{degrees}C. The 30 cm{sup 3} reactor is capable of containing up to 17 MPa (2500 psi) pressure at temperatures up to 550{degrees}C. The tubing used for preheater and precooler was 1/4in. 316 stainless steel with wall thickness of 0.035in. The lengths of the preheater and precooler are selected based on the particular process being studied. Since a gas (e.g. hydrogen or nitrogen) is bubbled through the reaction mixture under pressure and out through a letdown valve, a small water cooled condenser above the reactor before the let-down valve is added to avoid loss of solvent or other low boiling components. Coal liquefaction runs are made by preparing slurries of coal in reagent grade tetralin. Various ratios of tetralin to coal are used, and in some cases, a catalyst such as Ni/Mo on alumina is added.

  13. Boiling incipience and convective boiling of neon and nitrogen

    NASA Technical Reports Server (NTRS)

    Papell, S. S.; Hendricks, R. C.

    1977-01-01

    Forced convection and subcooled boiling heat transfer data for liquid nitrogen and liquid neon were obtained in support of a design study for a 30 tesla cryomagnet cooled by forced convection of liquid neon. The cryogen data obtained over a range of system pressures, fluid flow rates, and applied heat fluxes were used to develop correlations for predicting boiling incipience and convective boiling heat transfer coefficients in uniformly heated flow channels. The accuracy of the correlating equations was then evaluated. A technique was also developed to calculate the position of boiling incipience in a uniformly heated flow channel. Comparisons made with the experimental data showed a prediction accuracy of + or - 15 percent.

  14. Migration of selected hydrocarbon contaminants into dry pasta packaged in direct contact with recycled paperboard.

    PubMed

    Barp, Laura; Suman, Michele; Lambertini, Francesca; Moret, Sabrina

    2015-01-01

    This paper deals with the migration of selected hydrocarbon contaminants, namely mineral oil hydrocarbons (MOH), diisopropyl naphthalenes (DIPN) and polyalphaolefins (PAO) from adhesives into dry semolina and egg pasta packaged in direct contact with recycled paperboard. Migration was monitored during its shelf life (for up to two years) simulating storage in a supermarket (packs on shelves) and conditions preventing exchange with the surrounding environment (packs wrapped in aluminium foil). Migration from the secondary packaging (transport boxes of corrugated board) was also studied for semolina pasta. After 24 months of exposure, semolina pasta stored on shelves reached 3.2 and 0.6 mg kg(-1) of MOSH and MOAH, respectively, Migration from the adhesives used to close the boxes and from the transport boxes contributed about 30% and 25% of the total contamination, respectively. The highest contamination levels (14.5 and 2.0 mg kg(-1) of MOSH and MOAH, respectively, after 24 months) were found in egg pasta stored on shelves (no adhesives), and seemed due to the highest contribution from the external environment.

  15. Recovery of water and acid from leach solutions using direct contact membrane distillation.

    PubMed

    Kesieme, Uchenna K; Milne, Nicholas; Cheng, Chu Yong; Aral, Hal; Duke, Mikel

    2014-01-01

    This paper describes for the first time the use of direct contact membrane distillation (DCMD) for acid and water recovery from a real leach solution generated by a hydrometallurgical plant. The leach solutions considered contained H2SO4 or HCl. In all tests the temperature of the feed solution was kept at 60 °C. The test work showed that fluxes were within the range of 18-33 kg/m(2)/h and 15-35 kg/m(2)/h for the H2SO4 and HCl systems, respectively. In the H2SO4 leach system, the final concentration of free acid in the sample solution increased on the concentrate side of the DCMD system from 1.04 M up to 4.60 M. The sulfate separation efficiency was over 99.9% and overall water recovery exceeded 80%. In the HCl leach system, HCl vapour passed through the membrane from the feed side to the permeate. The concentration of HCl captured in the permeate was about 1.10 M leaving behind only 0.41 M in the feed from the initial concentration of 2.13 M. In all the experiments, salt rejection was >99.9%. DCMD is clearly viable for high recovery of high quality water and concentrated H2SO4 from spent sulfuric acid leach solution where solvent extraction could then be applied to recover the sulfuric acid and metals. While HCl can be recovered for reuse using only DCMD.

  16. Transient volumetric heat transfer coefficient prediction of a three-phase direct contact condenser

    NASA Astrophysics Data System (ADS)

    Mahood, Hameed B.; Sharif, Adel O.; Thorpe, Rex B.

    2015-02-01

    An experimental investigation for the time dependent volumetric heat transfer coefficient of the bubbles type, three-phase direct contact condenser has been carried out utilising a short column (70 cm in total height and 4 cm inner diameter). A 47 cm active height was chosen with five different mass flow rate ratios and three different initial dispersed phase temperatures. Vapour pentane and constant temperature tap water as dispersed and continuous phases were implemented. The results showed that the volumetric heat transfer coefficient decreases with increased time until it almost reaches its steady state conditions. A sharp decrease in the volumetric heat transfer coefficient was found at the beginning of the operation and, diminished over a short time interval. Furthermore, a positive effect of the mass flow rate ratios on the volumetric heat transfer coefficient was noted and this was more pronounced at the beginning of the operation. On the other hand, the volumetric heat transfer coefficient decreased with an increase in the continuous phase mass flow rate and there was no considerable effect of the initial dispersed phase temperatures, which confirms that latent heat transfer is dominant in the process.

  17. Genetic Analysis of Lice Supports Direct Contact between Modern and Archaic Humans

    PubMed Central

    Smith, Vincent S; Hammond, Shaless L; Rogers, Alan R; Clayton, Dale H

    2004-01-01

    Parasites can be used as unique markers to investigate host evolutionary history, independent of host data. Here we show that modern human head lice, Pediculus humanus, are composed of two ancient lineages, whose origin predates modern Homo sapiens by an order of magnitude (ca. 1.18 million years). One of the two louse lineages has a worldwide distribution and appears to have undergone a population bottleneck ca. 100,000 years ago along with its modern H. sapiens host. Phylogenetic and population genetic data suggest that the other lineage, found only in the New World, has remained isolated from the worldwide lineage for the last 1.18 million years. The ancient divergence between these two lice is contemporaneous with splits among early species of Homo, and cospeciation analyses suggest that the two louse lineages codiverged with a now extinct species of Homo and the lineage leading to modern H. sapiens. If these lice indeed codiverged with their hosts ca. 1.18 million years ago, then a recent host switch from an archaic species of Homo to modern H. sapiens is required to explain the occurrence of both lineages on modern H. sapiens. Such a host switch would require direct physical contact between modern and archaic forms of Homo. PMID:15502871

  18. Cold energy release characteristics of an ice/air direct contact heat exchanger

    SciTech Connect

    Ohira, Akiyoshi; Yanadori, Michio; Iwabuchi, Kunihiko; Kimura, Toshikatsu; Tsubota, Yuji

    1998-12-31

    This paper deals with the cold energy release characteristics of an ice/air direct contact heat exchanger in a refined cold energy conveyance system. Characteristics of the outlet temperature, the humidity, and time history of released heat are examined when the initial height of the ice-cube-packed bed in the heat exchanger is changed. The following are the results obtained in these experiments: (1) Inlet air of 30 C is lowered to about 0 C by passing the air through the heat exchanger, and absolute humidity of the outlet air is reduced to about a quarter of that of the inlet air. (2) There is an optimum height of the ice-cube-packed bed for maximizing the amount of cold energy released. (3) This heat exchange method can supply about twice the amount of cold energy released by an ordinary fin-tube-type heat exchanger even if the air velocity in the heat exchanger is reduced to about 0.38 times that of the fin-tube-type heat exchanger.

  19. Study of Direct-Contact HfO2/Si Interfaces

    PubMed Central

    Miyata, Noriyuki

    2012-01-01

    Controlling monolayer Si oxide at the HfO2/Si interface is a challenging issue in scaling the equivalent oxide thickness of HfO2/Si gate stack structures. A concept that the author proposes to control the Si oxide interface by using ultra-high vacuum electron-beam HfO2 deposition is described in this review paper, which enables the so-called direct-contact HfO2/Si structures to be prepared. The electrical characteristics of the HfO2/Si metal-oxide-semiconductor capacitors are reviewed, which suggest a sufficiently low interface state density for the operation of metal-oxide-semiconductor field-effect-transistors (MOSFETs) but reveal the formation of an unexpected strong interface dipole. Kelvin probe measurements of the HfO2/Si structures provide obvious evidence for the formation of dipoles at the HfO2/Si interfaces. The author proposes that one-monolayer Si-O bonds at the HfO2/Si interface naturally lead to a large potential difference, mainly due to the large dielectric constant of the HfO2. Dipole scattering is demonstrated to not be a major concern in the channel mobility of MOSFETs. PMID:28817060

  20. Conceptual design study for the HCRF direct contact heat exchanger modification

    SciTech Connect

    Wahl, E. F.

    1984-06-01

    The conceptual design of sieve trays for modifying the HCRF direct contact heat exchanger was developed as follows. The models of the prior work, EG&G subcontract No. K-7752, were extended and modified so the predicted heat transfer coincided with the experimental data of the 60 KW Raft River tests conducted by EG&G. Using these models, a hole diameter of 0.25 inches and a hole velocity of 1.3 ft/sec or greater was selected to accomplish the required heat transfer while minimizing mass transferred to the geothermal fluid. Using the above information, a conceptual design for a sieve tray column was developed. It was determined that the column should operate as a working fluid filled, working fluid dispersed column. This is accomplished by level control of the geothermal fluid below the bottom tray. The dimensions and configuration of the trays and downcomers, and the number of holes and their diameters is summarized in Wahl Company drawings 84144001 and 84144003 submitted with this report. The performance of this design is expected to be 12,000 lbs/hr of geothermal fluid for single component fluids and 11,800 to 12,000 lbs/hr for mixed fluids at a working fluid flow rate of 71% of the geothermal fluid flow rate. The flow rate limit of the geothermal fluid will vary from 9800 to 13,000 lbs/hr as the ratio varies from 83% to 62%.

  1. Direct contact membrane distillation for the concentration of saline dairy effluent.

    PubMed

    Kezia, Kezia; Lee, Judy; Weeks, Mike; Kentish, Sandra

    2015-09-15

    The ability of direct contact membrane distillation to concentrate the waste effluent from salty whey, a by-product from the cheese making industry has been investigated. The effect of trace protein in the feed, cross-flow velocity and feed acidity were the factors examined. Flat Sheet PTFE membranes of nominal pore sizes 0.05, 0.22 and 0.45 μm were utilised. A decline in feed flux in the presence of trace protein in the feed was observed, but liquid penetration through the membrane could still be prevented by utilization of a membrane of smaller pore size, to achieve a final total solids concentration of ±30% w/w with water recovery from 37 to 83 %. The pressure-drop across the channel length was also predicted accounting for the feed spacer. To increase the channel length up to 1 m will require operation using the smallest pore size of 0.05 μm, unless very low cross-flow velocities are used. The fouling of the membrane is primarily governed by precipitation of a calcium phosphate salt. However, operation at low pH does not improve the flux or the final salt concentration significantly.

  2. Treatment of high salinity brines by direct contact membrane distillation: Effect of membrane characteristics and salinity.

    PubMed

    Li, Jianfeng; Guan, Yunshan; Cheng, Fangqin; Liu, Yu

    2015-12-01

    Direct contact membrane distillation (DCMD) is one of the attractive technologies for high salinity brine treatment. In this study, four polytetrafluoroethylene (PTFE) membranes were examined in treating highly concentrated salt solutions. Results showed that non-supported membranes generally have a higher overall mass transfer coefficient but porosity seems to be the most important parameter controlling membrane flux and thermal efficiency. Supported membranes with large thickness had relatively higher thermal efficiency than small thickness. This can be attributed to their reduced heat loss through heat condition. In addition, KCl, NaCl and MgCl2 solutions showed distinct trends over flux decline at high salt concentrations (⩾2.0M). The difference in flux was largely due to the discrepancy in water activities of these solutions (KCl>NaCl>MgCl2). However, the effect of viscosity on permeate flux could not be neglected for MgCl2 at high salt concentrations as the suddenly increased viscosity could lead to serious temperature polarization. This study indicates that membrane distillation is a promising technology for high salinity brine treatment.

  3. Analytical model of an irrigated packed-bed direct-contact heat exchanger at high temperature

    SciTech Connect

    Bohn, M S

    1986-11-01

    This paper presents an analytical model of direct-contact heat exchange (DCHX) in an irrigated packed bed at high temperatures. The specific application is heat exchange between molten salt and air where the molten salt is a sensible heat storage medium and high temperature air is required for an end process. The model defines several heat transfer mechanisms between the three components in the bed - the liquid, the gas, and the packing. It also includes the effect of conduction in the packing. Correlations found in the literature are used to calculate the associated heat transfer coefficients. The model is restricted to liquids that wet the packing material and to gas/liquid flow rates below the loading point. Three dimensionless equations describe the heat balance between the three bed components. The resulting dimensionless parameters reveal that for commercial DCHX systems, radiation heat transfer is unimportant relative to the convective heat transfer, which is consistent with previous experimental results for air/mercury and nitrogen/molten lead systems. The model also predicts volumetric heat transfer coefficients of about 10,000 W/m/sup 3/K, which is consistent with experimental work.

  4. A novel multi-stage direct contact membrane distillation module: Design, experimental and theoretical approaches.

    PubMed

    Lee, Jung-Gil; Kim, Woo-Seung; Choi, June-Seok; Ghaffour, Noreddine; Kim, Young-Deuk

    2016-12-15

    An economic desalination system with a small scale and footprint for remote areas, which have a limited and inadequate water supply, insufficient water treatment and low infrastructure, is strongly demanded in the desalination markets. Here, a direct contact membrane distillation (DCMD) process has the simplest configuration and potentially the highest permeate flux among all of the possible MD processes. This process can also be easily instituted in a multi-stage manner for enhanced compactness, productivity, versatility and cost-effectiveness. In this study, an innovative, multi-stage, DCMD module under countercurrent-flow configuration is first designed and then investigate both theoretically and experimentally to identify its feasibility and operability for desalination application. Model predictions and measured data for mean permeate flux are compared and shown to be in good agreement. The effect of the number of module stages on the mean permeate flux, performance ratio and daily water production of the MDCMD system has been theoretically identified at inlet feed and permeate flow rates of 1.5 l/min and inlet feed and permeate temperatures of 70 °C and 25 °C, respectively. The daily water production of a three-stage DCMD module with a membrane area of 0.01 m(2) at each stage is found to be 21.5 kg. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Genetic analysis of lice supports direct contact between modern and archaic humans.

    PubMed

    Reed, David L; Smith, Vincent S; Hammond, Shaless L; Rogers, Alan R; Clayton, Dale H

    2004-11-01

    Parasites can be used as unique markers to investigate host evolutionary history, independent of host data. Here we show that modern human head lice, Pediculus humanus, are composed of two ancient lineages, whose origin predates modern Homo sapiens by an order of magnitude (ca. 1.18 million years). One of the two louse lineages has a worldwide distribution and appears to have undergone a population bottleneck ca. 100,000 years ago along with its modern H. sapiens host. Phylogenetic and population genetic data suggest that the other lineage, found only in the New World, has remained isolated from the worldwide lineage for the last 1.18 million years. The ancient divergence between these two lice is contemporaneous with splits among early species of Homo, and cospeciation analyses suggest that the two louse lineages codiverged with a now extinct species of Homo and the lineage leading to modern H. sapiens. If these lice indeed codiverged with their hosts ca. 1.18 million years ago, then a recent host switch from an archaic species of Homo to modern H. sapiens is required to explain the occurrence of both lineages on modern H. sapiens. Such a host switch would require direct physical contact between modern and archaic forms of Homo.

  6. Design and economics of direct-contact salt hydrate storage systems

    SciTech Connect

    Wright, J. D.

    1981-05-01

    A salt-hydrate latent heat storage system is described in which oil is injected at the bottom of the container and exchanges heat as it floats to the top where it is pumped back to the heat source. Experiments are described which are meant to solve two problems. The first problem is to reliably inject the oil into the salt phase. The second is to minimize the carryover of salt hydrate into the oil, which can be done using two-stage coalescer-filters. Three systems are described and compared: a standard liquid-based sensible heat storage system, a latent heat storage design where oil is the heat-transfer fluid throughout the system, and a latent heat storage system where ethylene glycol/water is used in the collectors and oil in the storage tank. Direct-contact latent heat systems have overall costs roughly equal to those for water thermal storage tanks. The primary advantage of latent heat storage is its substantially smaller volume requirement. (LEW)

  7. Evaluation of antibacterial effects of pulp capping agents with direct contact test method

    PubMed Central

    Yalcin, Muhammet; Arslan, Ugur; Dundar, Ayse

    2014-01-01

    Objectives: Calcium hydroxide has been used in dentistry as a major capping material having the capacity to introduce the formation of a mineralized dentin bridge, but it has no direct inducing effect to the pulp cells. The purpose of this study was to evaluate the antibacterial properties of three different pulp capping agents using a direct contact test (DCT). Materials and Methods: The antibacterial properties of three pulp capping agents were evaluated a DCT. For the DCT, wells (n = 12) of 96-microtiter plates were coated with the tested cements (Dycal, Dentsply, USA; DiaRoot BioAggregate, Diadent, Holland; Calcimol LC, Voco, Germany) and Kalzinol (zinc oxide/eugenol cement, Dentsply, USA) was used as control material. A Lactobacillus casei suspension was placed on the surface of each specimen for 1 h at 37°C. Bacterial growth was monitored for 16 h with a temperature-controlled microplate spectrophotometer. The kinetics of the outgrowth in each well were recorded continuously at 650 nm every 30 min. The data were analyzed by one-way ANOVA, and Tamhane's T2 multiple comparison test. The level of significance was determined as P < 0.05. Results: All pulp capping agents showed an increase in the logarithmic growth rate of L. casei when compared with the control group (P < 0.05). Therefore, all pulp capping agents did not show antibacterial activity. Conclusions: The tested pulp capping agents haven't got antibacterial properties. Therefore, they should be used carefully when pulp is exposed or only very thin dentin remained over the pulp to avoid bacterial contamination. PMID:24966754

  8. Direct contact and environmental contaminations are responsible for HEV transmission in pigs.

    PubMed

    Andraud, Mathieu; Dumarest, Marine; Cariolet, Roland; Aylaj, Bouchra; Barnaud, Elodie; Eono, Florent; Pavio, Nicole; Rose, Nicolas

    2013-10-28

    Hepatitis E virus (HEV) can cause enterically-transmitted hepatitis in humans. The zoonotic nature of Hepatitis E infections has been established in industrialized areas and domestic pigs are considered as the main reservoir. The dynamics of transmission in pig herds therefore needs to be understood to reduce the prevalence of viremic pigs at slaughter and prevent contaminated pig products from entering the food chain. An experimental trial was carried out to study the main characteristics of HEV transmission between orally inoculated pigs and naïve animals. A mathematical model was used to investigate three transmission routes, namely direct contact between pigs and two environmental components to represent within-and between-group oro-fecal transmission. A large inter-individual variability was observed in response to infection with an average latent period lasting 6.9 days (5.8; 7.9) in inoculated animals and an average infectious period of 9.7 days (8.2; 11.2). Our results show that direct transmission alone, with a partial reproduction number of 1.41 (0.21; 3.02), can be considered as a factor of persistence of infection within a population. However, the quantity of virus present in the environment was found to play an essential role in the transmission process strongly influencing the probability of infection with a within pen transmission rate estimated to 2 · 10(-6)g ge(-1)d(-1)(1 · 10(-7); 7 · 10(-6)). Between-pen environmental transmission occurred to a lesser extent (transmission rate: 7 · 10(-8)g ge(-1) d(-1)(5 · 10(-9); 3 · 10(-7)) but could further generate a within-group process. The combination of these transmission routes could explain the persistence and high prevalence of HEV in pig populations.

  9. Direct measurement of asperity contact growth in quartz at hydrothermal conditions

    USGS Publications Warehouse

    Beeler, Nicholas M.; Hickman, Stephen H.

    2015-01-01

    Earthquake recurrence requires interseismic fault restrengthening which results from solid state deformation in room-temperature friction and indentation experiments. In contrast exhumed fault zones show solution-transport processes such as pressure solution and contact overgrowths influence fault zone properties . In the absence of fluid flow, overgrowths are driven by gradients in surface curvature where material is dissolved, diffuses, and precipitates at the contact without convergence normal to the contact. To determine the rate of overgrowth for quartz, we conducted single contact experiments in an externally heated pressure vessel. Convergence was continuously monitored using reflected-light interferometry through a long-working-distance microscope. Contact normal force was constant with an initial effective normal stress of 1.7 MPa, temperature was between 350 and 530{degree sign}C, and water pressure was constant at 150 MPa. Two control experiments were conducted: one dry at 425{degree sign}C and one bi-material (sapphire) at 425{degree sign}C and 150 MPa water pressure. No contact growth or convergence was observed in the controls. For wet single-phase contacts, growth was initially rapid and then decreased with time. No convergence was observed. Fluid inclusions indicate that the contact is not uniformly wetted. The contact is bounded by small regions of high aperture, reflecting local free-face dissolution as the source for the overgrowth. The apparent activation energy is ~125 kJ/mol. Extrapolation predicts rates of contact area increase orders of magnitude faster than in dry, room-temperature and hydrothermal friction experiments, suggesting that natural strength recovery near the base of the seismogenic zone could be dominated by contact overgrowth.

  10. Three-dimensional culture of dental pulp stem cells in direct contact to tricalcium silicate cements.

    PubMed

    Widbiller, M; Lindner, S R; Buchalla, W; Eidt, A; Hiller, K-A; Schmalz, G; Galler, K M

    2016-03-01

    Calcium silicate cements are biocompatible dental materials applicable in contact with vital tissue. The novel tricalcium silicate cement Biodentine™ offers properties superior to commonly used mineral trioxide aggregate (MTA). Objective of this study was to evaluate its cytocompatibility and ability to induce differentiation and mineralization in three-dimensional cultures of dental pulp stem cells after direct contact with the material. Test materials included a new tricalcium silicate (Biodentine™, Septodont, Saint-Maur-des-Fossés, France), MTA (ProRoot® MTA, DENSPLY Tulsa Dental Specialities, Johnson City, TN, USA), glass ionomer (Ketac™ Molar Aplicap™, 3M ESPE, Seefeld, Germany), human dentin disks and polystyrene. Magnetic activated cell sorting for to the surface antigen STRO-1 was performed to gain a fraction enriched with mesenchymal stem cells. Samples were allowed to set and dental pulp stem cells in collagen carriers were placed on top. Scanning electron microscopy of tricalcium silicate cement surfaces with and without cells was conducted. Cell viability was measured for 14 days by MTT assay. Alkaline phosphatase activity was evaluated (days 3, 7, and 14) and expression of mineralization-associated genes (COL1A1, ALP, DSPP, and RUNX2) was quantified by real-time quantitative PCR. Nonparametric statistical analysis for cell viability and alkaline phosphatase data was performed to compare different materials as well as time points (Mann-Whitney U test, α = 0.05). Cell viability was highest on tricalcium silicate cement, followed by MTA. Viability on glass ionomer cement and dentin disks was significantly lower. Alkaline phosphatase activity was lower in cells on new tricalcium silicate cement compared to MTA, whereas expression patterns of marker genes were alike. Increased cell viability and similar levels of mineralization-associated gene expression in three-dimensional cell cultures on the novel tricalcium silicate cement and mineral

  11. How Does Water Boil?

    NASA Astrophysics Data System (ADS)

    Zahn, Dirk

    2004-11-01

    Insight into the boiling of water is obtained from molecular dynamics simulations. The process is initiated by the spontaneous formation of small vacuum cavities in liquid water. By themselves, these defects are very short lived. If, however, several cavities occur at close distances, they are likely to merge into larger vacuum holes. At the liquid-vapor interfaces, single or small groups of water molecules tend to leave the liquid surface. Once the system is propagated beyond the transition state, these evaporation events outnumber the competing reintegration into the hydrogen-bonded network.

  12. Computations of Boiling in Microgravity

    NASA Technical Reports Server (NTRS)

    Tryggvason, G.; Jacqmin, Dave

    2000-01-01

    The absence (or reduction) of gravity, can lead to major changes in boiling heat transfer. On Earth, convection has a major effect on the heat distribution ahead of an evaporation front, and buoyancy determines the motion of the growing bubbles. In microgravity, convection and buoyancy are absent or greatly reduced and the dynamics of the growing vapor bubbles can change in a fundamental way. In particular, the lack of redistribution of heat can lead to a large superheat and explosive growth of bubbles once they form. While considerable efforts have been devoted to examining boiling experimentally, including the effect of microgravity, theoretical and computational work have been limited. Here, the growth of boiling bubbles is studied by direct numerical simulations where the flow field is fully resolved and the effects of inertia, viscosity, surface deformation, heat conduction and convection, as well as the phase change, are fully accounted for. Boiling involves both fluid flow and heat transfer and thus requires the solution of the Navier-Stokes and the energy equations. The numerical method is based on writing one set of governing transport equations which is valid in both the liquid and vapor phases. This local, single-field formulation incorporates the effect of the interface in the governing equations as source terms acting only at the interface. These sources account for surface tension and latent heat in the equations for conservation of momentum and energy as well as mass transfer across the interface due to phase change. The single-field formulation naturally incorporates the correct mass, momentum and energy balances across the interface. Integration of the conservation equations across the interface directly yields the jump conditions derived in the local instant formulation for two-phase systems. In the numerical implementation, the conservation equations for the whole computational domain (both vapor and liquid) are solved using a stationary grid and

  13. Stabilization of freon 113 subcooled boiling in forced convection

    SciTech Connect

    Gentile, D.; Benejean, R.; Llory, M.

    1985-09-01

    A simple electronic feedback system allowing to perform tests in subcooled boiling of Freon 113 in the transition region, where systems directly heated by Joule effect are unstable, is presented. A short, electrically heated tube is used where the current is controlled by the measure of the wall temperature. First experiments highlight a hysteresis phenomenon depending on whether the temperature difference between the wall and the boiling liquid is increased or decreased, and the influence of surface conditions on the shape of the boiling curve.

  14. Direkte Kontakte zu Deutschland aus und in der Ferne (Direct Contact with Germany from and at a Distance).

    ERIC Educational Resources Information Center

    Wicke, Rainer E.

    This guide is a summary of ideas for enhancing the teaching of German through direct contact with Germany or German people without traveling abroad. The following ideas are highlighted: (1) correspondence (pen pals) with students in Germany; (2) audiotape recordings as an alternative to letter writing; (3) the exchange of videotape recordings with…

  15. Pseudophakodonesis and corneal endothelial contact: direct observations by high-speed cinematography.

    PubMed

    Jacobs, P M; Cheng, H; Price, N C

    1983-10-01

    High-speed cinematography was used to observe the movement of Federov type I lens implants within the anterior chamber. Our measurements suggest that in most patients contact between the lens implant and corneal endothelium does not occur.

  16. Boiling Fluids Behave Quite Differently in Space

    NASA Image and Video Library

    The boiling process is really different in space, since the vapor phase of a boiling liquid does not rise via buoyancy. Spacecraft and Earth-based systems use boiling to efficiently remove large am...

  17. Boiling liquid cauldron status report

    SciTech Connect

    Hoffman, M.A.

    1980-12-28

    The progress made over the past year in assessing the feasibility of the high-temperature, boiling cauldron blanket concept for the tanden mirror reactor is reviewed. The status of the proposed experiments and recently revised estimates of the vapor void fraction in the boiling pool are discussed.

  18. Impact of the collective diffusion of charged nanoparticles in the convective/capillary deposition directed by receding contact lines.

    PubMed

    Noguera-Marín, Diego; Moraila-Martínez, Carmen Lucía; Cabrerizo-Vílchez, Miguel; Rodríguez-Valverde, Miguel Angel

    2016-02-01

    The motion of electrically charged particles under crowding conditions and subjected to evaporation-driven capillary flow might be ruled by collective diffusion. The concentration gradient developed inside an evaporating drop of colloidal suspension may reduce by diffusion the number of particles transported toward the contact line by convection. Unlike self-diffusion coefficient, the cooperative diffusion coefficient of interacting particles becomes more pronounced in crowded environments. In this work, we examined experimentally the role of the collective diffusion of charge-stabilized nanoparticles in colloidal patterning. To decouple the sustained evaporation from the contact line motion, we conducted evaporating menisci experiments with driven receding contact lines at low capillary number. This allowed us to explore convective assembly at fixed and low bulk concentration, which enabled to develop high concentration gradients. At fixed velocity of receding contact line, we explored a variety of substrate-particle systems where the particle-particle electrostatic interaction was changed (via p H) as well as the substrate receding contact angle and the relative humidity. We found that the particle deposition directed by receding contact lines may be controlled by the interplay between evaporative convection and collective diffusion, particularly at low particle concentration.

  19. Analysis of gene expression profiles of Lactobacillus paracasei induced by direct contact with Saccharomyces cerevisiae through recognition of yeast mannan

    PubMed Central

    YAMASAKI-YASHIKI, Shino; SAWADA, Hiroshi; KINO-OKA, Masahiro; KATAKURA, Yoshio

    2016-01-01

    Co-culture of lactic acid bacteria (LAB) and yeast induces specific responses that are not observed in pure culture. Gene expression profiles of Lactobacillus paracasei ATCC 334 co-cultured with Saccharomyces cerevisiae IFO 0216 were analyzed by DNA microarray, and the responses induced by direct contact with the yeast cells were investigated. Coating the LAB cells with recombinant DnaK, which acts as an adhesive protein between LAB and yeast cells, enhanced the ratio of adhesion of the LAB cells to the yeast cells. The signals induced by direct contact were clarified by removal of the LAB cells unbound to the yeast cells. The genes induced by direct contact with heat-inactivated yeast cells were very similar to both those induced by the intact yeast cells and those induced by a soluble mannan. The top 20 genes upregulated by direct contact with the heat-inactivated yeast cells mainly encoded proteins related to exopolysaccharide synthesis, modification of surface proteins, and transport systems. In the case of the most upregulated gene, LSEI_0669, encoding a protein that has a region homologous to polyprenyl glycosylphosphotransferase, the expression level was upregulated 7.6-, 11.0-, and 8.8-fold by the heat-inactivated yeast cells, the intact yeast cells, and the soluble mannan, respectively, whereas it was only upregulated 1.8-fold when the non-adherent LAB cells were not removed before RNA extraction. Our results indicated that the LAB responded to direct contact with the yeast cells through recognition of mannan on the surface of the yeast. PMID:28243547

  20. Direct synaptic contacts on the myenteric ganglia of the rat stomach from the dorsal motor nucleus of the vagus.

    PubMed

    Hayakawa, Tetsu; Kuwahara, Sachi; Maeda, Seishi; Tanaka, Koichi; Seki, Makoto

    2006-09-20

    The myenteric ganglia regulate not only gastric motility but also secretion, because a submucous plexus is sparsely developed in the rodent stomach. We have examined whether the neurons of the dorsal motor nucleus of the vagus (DMV) have direct synaptic contacts on the myenteric ganglia and the ultrastructure of the vagal efferent terminals by using wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). The myenteric ganglia of the rat were composed of four types of neurons, i.e., small, medium-sized, large, and elongated neurons. The average numbers of axosomatic terminals per profile were 2.0 on the small neurons, 3.1 on the medium-sized neurons, 1.2 on the large neurons, and 4.2 on the elongated neuron. More than half of the axosomatic terminals contained round vesicles and formed asymmetric synaptic contacts on the small, medium-sized, and large neurons. About 80% of the axosomatic terminals on the elongated neurons contained pleomorphic vesicles and formed asymmetric synaptic contacts. When WGA-HRP was injected into the DMV, many anterogradely labeled terminals were found around the myenteric neurons. The labeled terminals were large (3.16 +/- 0.10 microm) and contacted exclusively the somata. Most of them (about 90%) contained round vesicles and formed asymmetric synaptic contacts. Serial ultrathin sections revealed that almost all neurons in a ganglion received projections from the DMV. The vagal axon terminals generally contacted the medium-sized or the elongated neurons, whereas a few labeled terminals contacted the small and the large neurons. The present results indicate that the DMV projects to all types of neurons and that their axon terminals contain mostly round synaptic vesicles and form asymmetric synaptic contacts.

  1. Direct measurement of asperity contact growth in quartz at hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Beeler, N. M.; Hickman, S. H.

    2008-12-01

    Room-temperature friction and indentation experiments suggest fault strengthening during the interseismic period results from increases in asperity contact area due to solid-state deformation. However, field observations on exhumed fault zones indicate that solution-transport processes, pressure solution, crack healing and contact overgrowth, influence fault zone rheology near the base of the seismogenic zone. Contact overgrowths result from gradients in surface curvature, where material is dissolved from the pore walls, diffuses through the fluid and precipitates at the contact between two asperities, cementing the asperities together without convergence normal to the contact. To determine the mechanisms and kinetics of asperity cementation, we conducted laboratory experiments in which convex and flat lenses prepared from quartz single crystals were pressed together in an externally heated pressure vessel equipped with an optical observation port. Convergence between the two lenses and contact morphology were continuously monitored during these experiments using reflected-light interferometry through a long-working-distance microscope. Contact normal force is constant with an initial effective normal stress of 1.7 MPa. Four single-phase experiments were conducted at temperatures between 350 and 530C at 150 MPa water pressure, along with two controls: one single phase, dry at 425C and one bimaterial (qtz/sapphire) at 425C and 150 MPa water pressure. No contact growth or convergence was observed in either of the controls. For wet single-phase contacts, however, growth was initially rapid and then decreased with time following an inverse squared dependence of contact radius on aperture. No convergence was observed over the duration of these experiments, suggesting that neither significant pressure solution nor crystal plasticity occurred at these stresses and temperatures. The formation of fluid inclusions between the lenses indicate that the contact is not uniformly

  2. Radial Glial Cell-Neuron Interaction Directs Axon Formation at the Opposite Side of the Neuron from the Contact Site.

    PubMed

    Xu, Chundi; Funahashi, Yasuhiro; Watanabe, Takashi; Takano, Tetsuya; Nakamuta, Shinichi; Namba, Takashi; Kaibuchi, Kozo

    2015-10-28

    How extracellular cues direct axon-dendrite polarization in mouse developing neurons is not fully understood. Here, we report that the radial glial cell (RGC)-cortical neuron interaction directs axon formation at the opposite side of the neuron from the contact site. N-cadherin accumulates at the contact site between the RGC and cortical neuron. Inhibition of the N-cadherin-mediated adhesion decreases this oriented axon formation in vitro, and disrupts the axon-dendrite polarization in vivo. Furthermore, the RGC-neuron interaction induces the polarized distribution of active RhoA at the contacting neurite and active Rac1 at the opposite neurite. Inhibition of Rho-Rho-kinase signaling in a neuron impairs the oriented axon formation in vitro, and prevents axon-dendrite polarization in vivo. Collectively, these results suggest that the N-cadherin-mediated radial glia-neuron interaction determines the contacting neurite as the leading process for radial glia-guided neuronal migration and directs axon formation to the opposite side acting through the Rho family GTPases.

  3. Some parameter boundaries governing microgravity pool boiling modes.

    PubMed

    Merte, Herman

    2006-09-01

    Pool boiling experiments were conducted in microgravity on five space shuttle flights, using a flat plate heater consisting of a semitransparent thin gold film deposited on a quartz substrate that also acted as a resistance thermometer. The test fluid was R-113, and the vapor bubble behavior at the heater surface was photographed from beneath as well as from the side. Each flight consisted of a matrix of three levels of imposed heat flux and three levels of initial bulk liquid subcooling. In many of the total of 45 experiments, steady nucleate boiling was observed from 16-mm movie films, where a large vapor bubble formed and remained slightly removed from the heater surface, with small vapor bubbles growing on the heater surface, and on contact coalescing with the large bubble. Computations of the forces associated with the momentum transfer in this process, which counters the Marangoni convection effects tending to impel the large bubble toward the heater surface, have been completed for all cases where applicable. The modes of pool boiling observed with successive increases in levels of heat flux in microgravity are categorized as: (i) minimum or incipient nucleate boiling; (ii) nucleate boiling with vigorous motion of the bubbles adjacent and parallel to the heater surface, impelled by Marangoni convection effects; (iii) nucleate boiling followed by coalescence with a neighboring large vapor bubble; (iv) partial dryout of the heater surface, in parallel with nucleate boiling; (v) complete dryout. The boundaries between these modes are delineated graphically as a function of the imposed heat flux and initial bulk liquid subcooling, together with the levels of the forces holding the large bubbles, acting as vapor reservoirs, away from the heater surface for the steady nucleate boiling mode.

  4. HORIZONTAL BOILING REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1958-11-18

    Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

  5. When water does not boil at the boiling point.

    PubMed

    Chang, Hasok

    2007-03-01

    Every schoolchild learns that, under standard pressure, pure water always boils at 100 degrees C. Except that it does not. By the late 18th century, pioneering scientists had already discovered great variations in the boiling temperature of water under fixed pressure. So, why have most of us been taught that the boiling point of water is constant? And, if it is not constant, how can it be used as a 'fixed point' for the calibration of thermometers? History of science has the answers.

  6. Human exposure to trace elements through the skin by direct contact with clothing: Risk assessment

    SciTech Connect

    Rovira, Joaquim; Nadal, Martí; Schuhmacher, Marta; Domingo, José L.

    2015-07-15

    Metals in textile products and clothing are used for many purposes, such as metal complex dyes, pigments, mordant, catalyst in synthetic fabrics manufacture, synergists of flame retardants, antimicrobials, or as water repellents and odour-preventive agents. When present in textile materials, heavy metals may mean a potential danger to human health. In the present study, the concentrations of a number of elements (Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Sc, Se, Sm, Sn, Sr, Tl, V, and Zn) were determined in skin-contact clothes. Analysed clothes were made of different materials, colours, and brands. Interestingly, we found high levels of Cr in polyamide dark clothes (605 mg/kg), high Sb concentrations in polyester clothes (141 mg/kg), and great Cu levels in some green cotton fabrics (around 280 mg/kg). Dermal contact exposure and human health risks for adult males, adult females, and for <1-year-old children were assessed. Non-carcinogenic and carcinogenic risks were below safe (HQ<1) and acceptable (<10{sup −6}) limits, respectively, according to international standards. However, for Sb, non-carcinogenic risk was above 10% of the safety limit (HQ>0.1) for dermal contact with clothes. - Highlights: • We determined in skin-contact clothes the concentrations of a number of metals. • Dermal contact exposure and health risks for adults and for 1-year-old children were assessed. • Carcinogenic risks were considered as acceptable (<10{sup −6}). • For non-carcinogenic risks, only Sb exceeded a 10% of the HQ for dermal contact with clothes.

  7. Development of a direct contact astrocyte-human cerebral microvessel endothelial cells blood-brain barrier coculture model.

    PubMed

    Kulczar, Chris; Lubin, Kelsey E; Lefebvre, Sylvia; Miller, Donald W; Knipp, Gregory T

    2017-09-05

    In conventional in-vitro blood-brain barrier (BBB) models, primary and immortalized brain microvessel endothelial cell (BMEC) lines are often cultured in a monolayer or indirect coculture or triculture configurations with astrocytes or pericytes, for screening permeation of therapeutic or potentially neurotoxic compounds. In each of these cases, the physiological relevancy associated with the direct contact between the BMECs, pericytes and astrocytes that form the BBB and resulting synergistic interactions are lost. We look to overcome this limitation with a direct contact coculture model. We established and optimized a direct interaction coculture system where primary human astrocytes are cultured on the apical surface of a Transwell® filter support and then human cerebral microvessel endothelial cells (hCMEC/D3) seeded directly on the astrocyte lawn. The studies suggest the direct coculture model may provide a more restrictive and physiologically relevant model through a significant reduction in paracellular transport of model compounds in comparison with monoculture and indirect coculture. In comparison with existing methods, the indirect coculture and monoculture models utilized may limit cell-cell signaling between human astrocytes and BMECs that are possible with direct configurations. Paracellular permeability reductions with the direct coculture system may enhance therapeutic agent and potential neurotoxicant screening for BBB permeability better than the currently available monoculture and indirect coculture in-vitro models. © 2017 Royal Pharmaceutical Society.

  8. A new technique for direct traceability of contact thermometry Co-C eutectic cells to the ITS-90

    SciTech Connect

    Failleau, G.; Deuzé, T.; Bourson, F.; Briaudeau, S.; Sadli, M.

    2013-09-11

    The eutectic Co-C melting point is a promising system to serve as a thermometric fixed-point in the temperature range above 1084.62 °C (copper freezing point). During the last decade, LNE-Cnam has developed and characterized some fixed-point devices, based on eutectic Co-C alloy, for applications to contact and radiation thermometry. Above 962 °C, the ITS-90 is realized by radiation thermometry by the extrapolation from a Ag, Au or Cu fixed point using the Planck law for radiation. So the only way for assigning a temperature in the scale to a Co-C cell (∼1324 °C) is by radiation thermometry. An indirect method is commonly used to assign a temperature to a high-temperature fixed point (HTFP) cell designed for contact thermometry is to fill a pyrometric cell with the same mixture as the contact thermometry cell. In this case, the temperature assigned to the pyrometric cell is attributed to the contact cell. This paper describes a direct method allowing the determination of the melting temperature realized by a 'contact thermometry' Co-C cell by comparison to a 'radiation thermometry' Co-C cell whose melting temperature was assigned in accordance to the scale by extrapolation from the Cu point. In addition, the same Co-C cell is studied with a standard Pt/Pd thermocouple.

  9. Radial Glial Cell–Neuron Interaction Directs Axon Formation at the Opposite Side of the Neuron from the Contact Site

    PubMed Central

    Xu, Chundi; Funahashi, Yasuhiro; Watanabe, Takashi; Takano, Tetsuya; Nakamuta, Shinichi; Namba, Takashi

    2015-01-01

    How extracellular cues direct axon–dendrite polarization in mouse developing neurons is not fully understood. Here, we report that the radial glial cell (RGC)–cortical neuron interaction directs axon formation at the opposite side of the neuron from the contact site. N-cadherin accumulates at the contact site between the RGC and cortical neuron. Inhibition of the N-cadherin-mediated adhesion decreases this oriented axon formation in vitro, and disrupts the axon–dendrite polarization in vivo. Furthermore, the RGC–neuron interaction induces the polarized distribution of active RhoA at the contacting neurite and active Rac1 at the opposite neurite. Inhibition of Rho–Rho-kinase signaling in a neuron impairs the oriented axon formation in vitro, and prevents axon–dendrite polarization in vivo. Collectively, these results suggest that the N-cadherin-mediated radial glia–neuron interaction determines the contacting neurite as the leading process for radial glia-guided neuronal migration and directs axon formation to the opposite side acting through the Rho family GTPases. SIGNIFICANCE STATEMENT Neurons are highly polarized cell lines typically with a single axon and multiple dendrites, which underlies the ability of integrating and transmitting the information in the brain. How is the axon–dendrite polarity of neurons established in the developing neocortex? Here we show that the N-cadherin-mediated radial glial cell–neuron interaction directs axon–dendrite polarization, the radial glial cell–neuron interaction induces polarized distribution of active RhoA and active Rac1 in neurons, and Rho–Rho-kinase signaling is required for axon–dendrite polarization. Our work advances the overall understanding of how extracellular cues direct axon–dendrite polarization in mouse developing neurons. PMID:26511243

  10. Enhanced Droplet Control by Transition Boiling

    PubMed Central

    Grounds, Alex; Still, Richard; Takashina, Kei

    2012-01-01

    A droplet of water on a heated surface can levitate over a film of gas produced by its own evaporation in the Leidenfrost effect. When the surface is prepared with ratchet-like saw-teeth topography, these droplets can self-propel and can even climb uphill. However, the extent to which the droplets can be controlled is limited by the physics of the Leidenfrost effect. Here, we show that transition boiling can be induced even at very high surface temperatures and provide additional control over the droplets. Ratchets with acute protrusions enable droplets to climb steeper inclines while ratchets with sub-structures enable their direction of motion to be controlled by varying the temperature of the surface. The droplets' departure from the Leidenfrost regime is assessed by analysing the sound produced by their boiling. We anticipate these techniques will enable the development of more sophisticated methods for controlling small droplets and heat transfer. PMID:23056912

  11. Enhanced droplet control by transition boiling.

    PubMed

    Grounds, Alex; Still, Richard; Takashina, Kei

    2012-01-01

    A droplet of water on a heated surface can levitate over a film of gas produced by its own evaporation in the Leidenfrost effect. When the surface is prepared with ratchet-like saw-teeth topography, these droplets can self-propel and can even climb uphill. However, the extent to which the droplets can be controlled is limited by the physics of the Leidenfrost effect. Here, we show that transition boiling can be induced even at very high surface temperatures and provide additional control over the droplets. Ratchets with acute protrusions enable droplets to climb steeper inclines while ratchets with sub-structures enable their direction of motion to be controlled by varying the temperature of the surface. The droplets' departure from the Leidenfrost regime is assessed by analysing the sound produced by their boiling. We anticipate these techniques will enable the development of more sophisticated methods for controlling small droplets and heat transfer.

  12. Enhanced Droplet Control by Transition Boiling

    NASA Astrophysics Data System (ADS)

    Grounds, Alex; Still, Richard; Takashina, Kei

    2012-10-01

    A droplet of water on a heated surface can levitate over a film of gas produced by its own evaporation in the Leidenfrost effect. When the surface is prepared with ratchet-like saw-teeth topography, these droplets can self-propel and can even climb uphill. However, the extent to which the droplets can be controlled is limited by the physics of the Leidenfrost effect. Here, we show that transition boiling can be induced even at very high surface temperatures and provide additional control over the droplets. Ratchets with acute protrusions enable droplets to climb steeper inclines while ratchets with sub-structures enable their direction of motion to be controlled by varying the temperature of the surface. The droplets' departure from the Leidenfrost regime is assessed by analysing the sound produced by their boiling. We anticipate these techniques will enable the development of more sophisticated methods for controlling small droplets and heat transfer.

  13. Film boiling of mercury droplets

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Schoessow, G. J.; Chmielewski, C. E.

    1975-01-01

    Vaporization times of mercury droplets in Leidenfrost film boiling on a flat horizontal plate are measured in an air atmosphere. Extreme care was used to prevent large amplitude droplet vibrations and surface wetting; therefore, these data can be compared to film boiling theory. For these data, diffusion from the upper surface of the drop is a dominant mode of mass transfer from the drop. A closed-form analytical film boiling theory is developed to account for the diffusive evaporation. Reasonable agreement between data and theory is seen.

  14. Film boiling of mercury droplets

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Schoessow, G. J.; Chmielewski, C. E.

    1975-01-01

    Vaporization times of mercury droplets in Leidenfrost film boiling on a flat horizontal plate are measured in an air atmosphere. Extreme care was used to prevent large amplitude droplet vibrations and surface wetting; therefore, these data can be compared to film boiling theory. Diffusion from the upper surface of the drop appears as a dominant mode of mass transfer from the drop. A closed-form analytical film boiling theory is developed to account for the diffusive evaporation. Reasonable agreement between data and theory is seen.

  15. Film boiling of mercury droplets

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J.; Schoessow, G. J.; Chmielewski, C. E.

    1975-01-01

    Vaporization times of mercury droplets in Leidenfrost film boiling on a flat horizontal plate are measured in an air atmosphere. Extreme care was used to prevent large amplitude droplet vibrations and surface wetting; therefore, these data can be compared to film boiling theory. For these data, diffusion from the upper surface of the drop is a dominant mode of mass transfer from the drop. A closed-form analytical film boiling theory is developed to account for the diffusive evaporation. Reasonable agreement between data and theory is seen.

  16. Boils and Carbuncles

    MedlinePlus

    ... Close contact with a person who has a staph infection. You're more likely to develop an infection ... But the following measures may help you avoid staph infections: Wash your hands regularly with mild soap. Or ...

  17. Direct evidence for two-band superconductivity in MgB2 single crystals from directional point-contact spectroscopy in magnetic fields.

    PubMed

    Gonnelli, R S; Daghero, D; Ummarino, G A; Stepanov, V A; Jun, J; Kazakov, S M; Karpinski, J

    2002-12-09

    We present the results of the first directional point-contact spectroscopy experiments in high-quality MgB2 single crystals. Because of the directionality of the current injection into the samples, the application of a magnetic field allowed us to separate the contributions of the sigma and pi bands to the total conductance of our point contacts. By using this technique, we were able to obtain the temperature dependency of each gap independent of the other. The consequent, strong reduction of the error on the value of the gap amplitude as a function of temperature allows a stricter test of the predictions of the two-band model for MgB2.

  18. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    DOEpatents

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1988-01-05

    A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  19. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    DOEpatents

    Berry, G.F.; Minkov, V.; Petrick, M.

    1981-11-02

    A magnetohydrodynamic (MHD) power generating system is described in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  20. Open-cycle magnetohydrodynamic power plant based upon direct-contact closed-loop high-temperature heat exchanger

    DOEpatents

    Berry, Gregory F.; Minkov, Vladimir; Petrick, Michael

    1988-01-01

    A magnetohydrodynamic (MHD) power generating system in which ionized combustion gases with slag and seed are discharged from an MHD combustor and pressurized high temperature inlet air is introduced into the combustor for supporting fuel combustion at high temperatures necessary to ionize the combustion gases, and including a heat exchanger in the form of a continuous loop with a circulating heat transfer liquid such as copper oxide. The heat exchanger has an upper horizontal channel for providing direct contact between the heat transfer liquid and the combustion gases to cool the gases and condense the slag which thereupon floats on the heat transfer liquid and can be removed from the channel, and a lower horizontal channel for providing direct contact between the heat transfer liquid and pressurized air for preheating the inlet air. The system further includes a seed separator downstream of the heat exchanger.

  1. Performance of a new 915 mhz direct contact applicator with reduced leakage. A detailed analysis. Final report

    SciTech Connect

    Kantor, G.; Witters, D.M. Jr.

    1983-04-01

    The paper demonstrates the feasibility of a direct contact diathermy applicator operating at 915 MHz. The design is a circular waveguide internally loaded with two orthogonal pairs of forward ridges to obtain circular polarization and two rear ridges with a probe to excite the guide. Two designs were tested: a 15-cm diameter applicator with one annular choke covered with a microwave absorber and a 25-cm diameter applicator with two additional concentric chokes to limit radiation leakage. In delivering a thermally effective specific absorption rate to a planar phantom, leakage levels were less than 5 mW/sq. cm for applicators in direct contact with the phantom. If there is a small spacing between these applicators and planar phantoms, the net power and associated leakage is excessive.

  2. Pool and flow boiling in variable and microgravity

    NASA Technical Reports Server (NTRS)

    Merte, Herman, Jr.

    1994-01-01

    effects become significant to the boiling process (2) the effect of lower liquid flow velocities on the Critical Heat Flux when buoyancy is removed. Results of initial efforts in these directions are presented, albeit restricted currently to the ever present earth gravity.

  3. Direct stamp of technology or origin on the genotypic and phenotypic variation of indigenous Saccharomyces cerevisiae population in a natural model of boiled grape juice fermentation into traditional Msalais wine in China.

    PubMed

    Zhu, Li-Xia; Wang, Guan-Qiong; Xue, Ju-Lan; Gou, Dong-Qi; Duan, Chang-Qing

    2017-08-01

    Saccharomyces cerevisiae strains worldwide show genetic and phenotypic diversity and their population substructures are greatly affected by their technological application or geographical origins. Msalais is a traditional wine obtained via a unique method of spontaneous fermentation of local boiled grape juice in Southern Xinjiang. We analyzed 436 indigenous S. cerevisiae strains associated with Msalais fermentation. These strains were highly diverse with respect to the interdelta region and 24 phenotypic traits, with apparent differentiation according to strain origins and technologies used to produce Msalais. The genetic and phenotypic diversity of strains from traditional workshops was higher than in strains from modern plants. These local strains had different origin- or technology-specific fermentative characteristics. Strains growing in large-scale fermentation tanks tolerated high temperature, whereas strains from traditional workshops tolerated high alcohol content (16%) and low temperature (13°C). Almost all the strains were characterized by the highest fermenting vigor, with weak H2S production and no histamine, cadaverine, phenethylamine and tryptamine production. Majority of strains had pronounced autolytic activity with high β-glucosidase and polygalacturonase activity and alcohol production. Our study reveals a direct stamp of technology or origin on genotypic and phenotypic variation of an indigenous S. cerevisiae population. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. What keeps family physicians busy in Portugal? A multicentre observational study of work other than direct patient contacts

    PubMed Central

    Granja, Mónica; Ponte, Carla; Cavadas, Luís Filipe

    2014-01-01

    Objectives To quantify the time spent by family physicians (FP) on tasks other than direct patient contact, to evaluate job satisfaction, to analyse the association between time spent on tasks and physician characteristics, the association between the number of tasks performed and physician characteristics and the association between time spent on tasks and job satisfaction. Design Cross-sectional, using time-and-motion techniques. Two workdays were documented by direct observation. A significance level of 0.05 was adopted. Setting Multicentric in 104 Portuguese family practices. Participants A convenience sample of FP, with lists of over 1000 patients, teaching senior medical students and first-year family medicine residents in 2012, was obtained. Of the 217 FP invited to participate, 155 completed the study. Main outcomes measured Time spent on tasks other than direct patient contact and on the performance of more than one task simultaneously, the number of direct patient contacts in the office, the number of indirect patient contacts, job satisfaction, demographic and professional characteristics associated with time spent on tasks and the number of different tasks performed, and the association between time spent on tasks and job satisfaction. Results FP (n=155) spent a mean of 143.6 min/day (95% CI 135.2 to 152.0) performing tasks such as prescription refills, teaching, meetings, management and communication with other professionals (33.4% of their workload). FP with larger patient lists spent less time on these tasks (p=0.002). Older FP (p=0.021) and those with larger lists (p=0.011) performed fewer tasks. The mean job satisfaction score was 3.5 (out of 5). No association was found between job satisfaction and time spent on tasks. Conclusions FP spent one-third of their workday in coordinating care, teaching and managing. Time devoted to these tasks decreases with increasing list size and physician age. PMID:24934208

  5. Extracellular Electron Transfer to Fe(III) Oxides by the Hyperthermophilic Archaeon Geoglobus ahangari via a Direct Contact Mechanism

    PubMed Central

    Manzella, Michael P.; Reguera, Gemma

    2013-01-01

    The microbial reduction of Fe(III) plays an important role in the geochemistry of hydrothermal systems, yet it is poorly understood at the mechanistic level. Here we show that the obligate Fe(III)-reducing archaeon Geoglobus ahangari uses a direct-contact mechanism for the reduction of Fe(III) oxides to magnetite at 85°C. Alleviating the need to directly contact the mineral with the addition of a chelator or the electron shuttle anthraquinone-2,6-disulfonate (AQDS) stimulated Fe(III) reduction. In contrast, entrapment of the oxides within alginate beads to prevent cell contact with the electron acceptor prevented Fe(III) reduction and cell growth unless AQDS was provided. Furthermore, filtered culture supernatant fluids had no effect on Fe(III) reduction, ruling out the secretion of an endogenous mediator too large to permeate the alginate beads. Consistent with a direct contact mechanism, electron micrographs showed cells in intimate association with the Fe(III) mineral particles, which once dissolved revealed abundant curled appendages. The cells also produced several heme-containing proteins. Some of them were detected among proteins sheared from the cell's outer surface and were required for the reduction of insoluble Fe(III) oxides but not for the reduction of the soluble electron acceptor Fe(III) citrate. The results thus support a mechanism in which the cells directly attach and transfer electrons to the Fe(III) oxides using redox-active proteins exposed on the cell surface. This strategy confers on G. ahangari a competitive advantage for accessing and reducing Fe(III) oxides under the extreme physical and chemical conditions of hot ecosystems. PMID:23728807

  6. Extracellular electron transfer to Fe(III) oxides by the hyperthermophilic archaeon Geoglobus ahangari via a direct contact mechanism.

    PubMed

    Manzella, Michael P; Reguera, Gemma; Kashefi, Kazem

    2013-08-01

    The microbial reduction of Fe(III) plays an important role in the geochemistry of hydrothermal systems, yet it is poorly understood at the mechanistic level. Here we show that the obligate Fe(III)-reducing archaeon Geoglobus ahangari uses a direct-contact mechanism for the reduction of Fe(III) oxides to magnetite at 85°C. Alleviating the need to directly contact the mineral with the addition of a chelator or the electron shuttle anthraquinone-2,6-disulfonate (AQDS) stimulated Fe(III) reduction. In contrast, entrapment of the oxides within alginate beads to prevent cell contact with the electron acceptor prevented Fe(III) reduction and cell growth unless AQDS was provided. Furthermore, filtered culture supernatant fluids had no effect on Fe(III) reduction, ruling out the secretion of an endogenous mediator too large to permeate the alginate beads. Consistent with a direct contact mechanism, electron micrographs showed cells in intimate association with the Fe(III) mineral particles, which once dissolved revealed abundant curled appendages. The cells also produced several heme-containing proteins. Some of them were detected among proteins sheared from the cell's outer surface and were required for the reduction of insoluble Fe(III) oxides but not for the reduction of the soluble electron acceptor Fe(III) citrate. The results thus support a mechanism in which the cells directly attach and transfer electrons to the Fe(III) oxides using redox-active proteins exposed on the cell surface. This strategy confers on G. ahangari a competitive advantage for accessing and reducing Fe(III) oxides under the extreme physical and chemical conditions of hot ecosystems.

  7. Direct contact between dust and HBCD-treated fabrics is an important pathway of source-to-dust transfer.

    PubMed

    Rauert, Cassandra; Kuribara, Isamu; Kataoka, Toshiyuki; Wada, Takeharu; Kajiwara, Natsuko; Suzuki, Go; Takigami, Hidetaka; Harrad, Stuart

    2016-03-01

    Hexabromocyclododecanes (HBCDs) are a class of brominated flame retardant that have found extensive application in consumer products used widely in indoor environments. Although uncertainty remains about the human health impacts of HBCDs, ingestion of HBCD-contaminated indoor dust has been shown to be a particularly significant exposure pathway for young children. Despite this, understanding of the mechanisms via which HBCD transfer from products to indoor dust remains incomplete. In this study, an in-house test chamber was used to investigate transfer of HBCDs from a treated textile sample to indoor dust via direct textile:dust contact. Results were compared with previous data using the same test chamber to examine other pathways via which HBCDs transfer from products to dust, and highlighted HBCD transfer via direct source:dust contact as being particularly important. This novel finding was corroborated by complementary experiments that examined HBCD transfer via direct contact, from other treated textiles to three major components of indoor dust: artificial indoor dust, soil particles, and cotton linters.

  8. Comparison of the cytotoxicity of high-level disinfectants by the MTT assay and direct contact assay.

    PubMed

    Ryu, Mizuyuki; Matsumura, Reiko; Quan, Glenlelyn; Furuta, Taro

    2013-01-01

    Most critical instruments are not designed for heat sterilization and autoclaving. These items are usually treated with chemical agents such as peracetic acid(PAA), glutaraldehyde (GA) and ortho-phthalaldehyde (OPA). MTT assay is often used to evaluate the in vitro cytotoxicity of these chemical agents. In this study, disinfectants were allowed to come in direct contact with cells. Their cytotoxicity was evaluated based on cell viability and adhesive properties. The results obtained from the direct contact method were compared with those obtained from the conventional MTT assay wherein the disinfectants were added into a nutrient medium. It was found that the two methods yielded very different results, especially when aldehyde- and halogen-containing disinfectants were tested, and that toxicity may be underestimated in the MTT assay. Hence, it can be assumed that the direct contact assay is more accurate when evaluating the cytotoxicity of residual chemicals. It was also observed that the cytotoxicity of PAA was lower than that of GA and OPA.

  9. A scale-dependent model for direct computation of dynamic contact lines

    NASA Astrophysics Data System (ADS)

    Zaleski, S.; Afkhami, S.; Guion, A.; Buongiorno, J.

    2016-11-01

    When using numerical schemes for the simulation of moving contact lines with the classical "no-slip" boundary condition, the numerical solutions become dependent on grid spacing. Numerical approaches that account for the slip of the contact line avoid this difficulty; a numerically feasible slip length however can often be much larger than the physically "true" one. Afkhami et al. addressed this issue, where they proposed a numerical model for the implementation of contact angle based on the mesh size that resulted in mesh independent solutions. Here we refine and apply their numerical observation by studying the problem of coating a plate withdrawn from a viscous liquid reservoir. We consider a partially wetting liquid and show that depending on the capillary number, either a stationary meniscus is formed or a liquid film is deposited on the substrate, known as the transition to a Landau-Levich-Derjaguin film. We derive an effective numerical boundary condition model for the computation of the transition capillary number. The model can be thought of as a large scale solution in an asymptotic matching procedure.

  10. Method for analyzing the chemical composition of liquid effluent from a direct contact condenser

    DOEpatents

    Bharathan, Desikan; Parent, Yves; Hassani, A. Vahab

    2001-01-01

    A computational modeling method for predicting the chemical, physical, and thermodynamic performance of a condenser using calculations based on equations of physics for heat, momentum and mass transfer and equations of equilibrium thermodynamics to determine steady state profiles of parameters throughout the condenser. The method includes providing a set of input values relating to a condenser including liquid loading, vapor loading, and geometric characteristics of the contact medium in the condenser. The geometric and packing characteristics of the contact medium include the dimensions and orientation of a channel in the contact medium. The method further includes simulating performance of the condenser using the set of input values to determine a related set of output values such as outlet liquid temperature, outlet flow rates, pressures, and the concentration(s) of one or more dissolved noncondensable gas species in the outlet liquid. The method may also include iteratively performing the above computation steps using a plurality of sets of input values and then determining whether each of the resulting output values and performance profiles satisfies acceptance criteria.

  11. Human exposure to trace elements through the skin by direct contact with clothing: Risk assessment.

    PubMed

    Rovira, Joaquim; Nadal, Martí; Schuhmacher, Marta; Domingo, José L

    2015-07-01

    Metals in textile products and clothing are used for many purposes, such as metal complex dyes, pigments, mordant, catalyst in synthetic fabrics manufacture, synergists of flame retardants, antimicrobials, or as water repellents and odour-preventive agents. When present in textile materials, heavy metals may mean a potential danger to human health. In the present study, the concentrations of a number of elements (Al, As, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Sb, Sc, Se, Sm, Sn, Sr, Tl, V, and Zn) were determined in skin-contact clothes. Analysed clothes were made of different materials, colours, and brands. Interestingly, we found high levels of Cr in polyamide dark clothes (605 mg/kg), high Sb concentrations in polyester clothes (141 mg/kg), and great Cu levels in some green cotton fabrics (around 280 mg/kg). Dermal contact exposure and human health risks for adult males, adult females, and for <1-year-old children were assessed. Non-carcinogenic and carcinogenic risks were below safe (HQ<1) and acceptable (<10(-6)) limits, respectively, according to international standards. However, for Sb, non-carcinogenic risk was above 10% of the safety limit (HQ>0.1) for dermal contact with clothes.

  12. Pool boiling on a large horizontal flat resistance heater

    SciTech Connect

    Reguillot, F.; Witte, L.; Lienhard, J.; Poniewski, M. Kielce University of Technology, )

    1992-08-01

    Results are presented of experiments on n-pentane/Freon-113 system, carried out to investigate the film-transition boiling region where liquid-solid contacts contribute significantly to the local heat flux, using a large flat horizontal resistance heater mounted on a ceramic insulating substrate. After steady film boiling was reached, the heat flux was decreased and recorded simultaneously with the temperature measured by thermocouples attached to the lower side of the heater surface. It is shown that the observed data on the quasi-linear film boiling regime are better represented by Berenson's (1960) correlation than by Klimenko's (1981) correlation. Burnout values measured for Freon-113 compared reasonably well to available correlations for the flat plate geometry. 10 refs.

  13. Reduced Boil-Off System Sizing

    NASA Technical Reports Server (NTRS)

    Guzik, Monica C.; Plachta, David W.; Feller, Jeffrey R.

    2015-01-01

    NASA is currently developing cryogenic propellant storage and transfer systems for future space exploration and scientific discovery missions by addressing the need to raise the technology readiness level of cryogenic fluid management technologies. Cryogenic propellants are baselined in many propulsion systems due to their inherently high specific impulse; however, their low boiling points can cause substantial boil-off losses over time. Recent efforts such as the Reduced Boil-off Testing and the Active Thermal Control Scaling Study provide important information on the benefit of an active cooling system applied to LH2 propellant storage. Findings show that zero-boil off technologies can reduce overall mass in LH2 storage systems when low Earth orbit loiter periods extend beyond two months. A significant part of this mass reduction is realized by integrating two stages of cooling: a 20 K stage to intercept heat at the tank surface, and a 90 K stage to reduce the heat entering the less efficient 20 K stage. A missing element in previous studies, which is addressed in this paper, is the development of a direct method for sizing the 90 K cooling stage. Such a method requires calculation of the heat entering both the 90 K and 20 K stages as compared to the overall system masses, and is reliant upon the temperature distribution, performance, and unique design characteristics of the system in question. By utilizing the known conductance of a system without active thermal control, the heat being intercepted by a 90 K stage can be calculated to find the resultant lift and mass of each active thermal control stage. Integral to this is the thermal conductance of the cooling straps and the broad area cooling shield, key parts of the 90 K stage. Additionally, a trade study is performed to show the ability of the 90 K cooling stage to reduce the lift on the 20 K cryocooler stage, which is considerably less developed and efficient than 90 K cryocoolers.

  14. Calibration of non-contact ultrasound as an online sensor for wood characterization: Effects of temperature, moisture, and scanning direction

    NASA Astrophysics Data System (ADS)

    Vun, R. Y.; Hoover, K.; Janowiak, J.; Bhardwaj, M.

    2008-01-01

    Numerous handheld moisture meters are available for measuring moisture levels of wood and building materials for a vast range of quality control and moisture diagnosis applications. However, many methods currently available require physical contact of a probe with the test material to operate. The contact requirement of such devices has limited applications for these purposes. There is a tremendous demand for dynamic online quality assessment of in-process materials for moisture content (MC) measurements. In this paper, a non-destructive non-contact ultrasound technology was used to evaluate the effects of increasing temperature in two MC levels and of increasing MC in lumber. The results show that the ultrasonic absolute transmittance and velocity parameters are directly correlated very well (R2≥0.87) with temperature for the two moisture levels in wood. At constant temperature, however, the velocity is inversely correlated with MC. It was also found that the distribution of MC along the length is marginally insignificant to both ultrasonic measurements. The transmittance measurement along the orthogonal thickness direction is insignificant above the fiber saturation MC; similarly, the velocity measurement is marginally insignificant. The study concludes a positive correlation and a good fit for this technology to advance into the development of an automated device for determining wood moisture levels, which will in turn be used to control the dynamics of wood drying/sterilization processes. Further calibration research is recommended to ascertain the constraints and limitations of the technology to specific wood species and dimension.

  15. Development of an integrated direct-contacting optical-fiber microchip with light-emitting diode-induced fluorescence detection.

    PubMed

    Liu, Changchun; Cui, Dafu; Chen, Xing

    2007-11-02

    In this paper, one poly(dimethylsiloxane) (PDMS) sandwich microchip integrated with one direct-contacting optical fiber was fabricated by using a thin-casting method. This novel integrated PDMS sandwich microchip included top glass plate, PDMS membrane replica with microfluidic networks and optical fiber, flat PDMS membrane and bottom glass plate. As the tip of excitation optical fiber completely contacted with the separation microchannel in this integrated microchip, it not only increased the excitation light intensity to achieve the high sensitivity, but also reduced the diameter of excitation beam to obtain high resolution. In addition, we found that this rigid PDMS sandwich microchip structure effectively prevented PDMS microchannel distortion from rigid optical fiber, and provided a substantial convenience for microchips manipulating. A blue light-emitting diode (LED) was applied as excitation source by using optical fiber to couple excitation light into its direct-contacting microchannel for fluorescence detection. The performances of this integrated PDMS sandwich microchip was demonstrated by separating the mixture of sodium fluorescein (SF) and fluorescein isothiocyanate isomer I (FITC), and showed a higher sensitive and resolution than those obtained from the conventional integrated optical-fiber PDMS microchip with a 100-microm distance between fiber tip and separation microchannel. Additionally, the reproducibility of this integrated microchip with LED-induced fluorescence detection was also examined by separation of a mixture of FITC-labeled amino acids.

  16. Infrared thermometry study of nanofluid pool boiling phenomena

    PubMed Central

    2011-01-01

    Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement. PMID:21711754

  17. Infrared thermometry study of nanofluid pool boiling phenomena.

    PubMed

    Gerardi, Craig; Buongiorno, Jacopo; Hu, Lin-Wen; McKrell, Thomas

    2011-03-16

    Infrared thermometry was used to obtain first-of-a-kind, time- and space-resolved data for pool boiling phenomena in water-based nanofluids with diamond and silica nanoparticles at low concentration (<0.1 vol.%). In addition to macroscopic parameters like the average heat transfer coefficient and critical heat flux [CHF] value, more fundamental parameters such as the bubble departure diameter and frequency, growth and wait times, and nucleation site density [NSD] were directly measured for a thin, resistively heated, indium-tin-oxide surface deposited onto a sapphire substrate. Consistent with other nanofluid studies, the nanoparticles caused deterioration in the nucleate boiling heat transfer (by as much as 50%) and an increase in the CHF (by as much as 100%). The bubble departure frequency and NSD were found to be lower in nanofluids compared with water for the same wall superheat. Furthermore, it was found that a porous layer of nanoparticles built up on the heater surface during nucleate boiling, which improved surface wettability compared with the water-boiled surfaces. Using the prevalent nucleate boiling models, it was possible to correlate this improved surface wettability to the experimentally observed reductions in the bubble departure frequency, NSD, and ultimately to the deterioration in the nucleate boiling heat transfer and the CHF enhancement.

  18. Direct laser manipulation reveals the mechanics of cell contacts in vivo

    PubMed Central

    Bambardekar, Kapil; Clément, Raphaël; Blanc, Olivier; Chardès, Claire; Lenne, Pierre-François

    2015-01-01

    Cell-generated forces produce a variety of tissue movements and tissue shape changes. The cytoskeletal elements that underlie these dynamics act at cell–cell and cell–ECM contacts to apply local forces on adhesive structures. In epithelia, force imbalance at cell contacts induces cell shape changes, such as apical constriction or polarized junction remodeling, driving tissue morphogenesis. The dynamics of these processes are well-characterized; however, the mechanical basis of cell shape changes is largely unknown because of a lack of mechanical measurements in vivo. We have developed an approach combining optical tweezers with light-sheet microscopy to probe the mechanical properties of epithelial cell junctions in the early Drosophila embryo. We show that optical trapping can efficiently deform cell–cell interfaces and measure tension at cell junctions, which is on the order of 100 pN. We show that tension at cell junctions equilibrates over a few seconds, a short timescale compared with the contractile events that drive morphogenetic movements. We also show that tension increases along cell interfaces during early tissue morphogenesis and becomes anisotropic as cells intercalate during germ-band extension. By performing pull-and-release experiments, we identify time-dependent properties of junctional mechanics consistent with a simple viscoelastic model. Integrating this constitutive law into a tissue-scale model, we predict quantitatively how local deformations propagate throughout the tissue. PMID:25605934

  19. Direct investigation of colloid/micro-particle behavior near grain to grain contacts

    NASA Astrophysics Data System (ADS)

    Ochiai, N.; Dragila, M. I.

    2008-12-01

    Transport of micron-sized particles and microbes through porous media is typically modeled with colloid filtration theory (CFT), based on the advective-dispersive equation. Larger colloids and micro-particles, however, are consistently observed to travel through porous media at velocities greater than the average fluid velocity, with larger particles traveling faster than smaller particles. It is commonly posited that the particles' size causes them to be physically excluded from narrow pores or streamlines near pore walls. We suggest, however, that the reduced diffusivity of the particles and pore-scale flow field heterogeneities porous media conspire to keep particles on faster-moving streamlines. To test this hypothesis, we used epi- fluorescence microscopy and digital image analysis to investigate the 3-dimensional trajectories of 5 micron latex microspheres as they were transported at various flow rates (40~350μ ms-1) through a saturated micro-model consisting of pair of contacting 1mm glass beads. At all flow rates, particles appeared to be preferentially excluded from a given volume surrounding grain-to-grain contacts. At lower flow rates some microspheres were observed to enter this low-flow zone. At all flow rates, the average velocity of particles passing through the bead pair was slightly greater than predicted. In addition, after exiting the bead pair, the average velocity of particles did not immediately return to the pre-bead velocity. We discuss the potential of these observations to explain the continuum-scale enhanced velocity of particles.

  20. Primary bovine viral diarrhoea virus infection in calves following direct contact with a persistently viraemic calf.

    PubMed

    Tråvén, M; Alenius, S; Fossum, C; Larsson, B

    1991-08-01

    Six calves, aged 24 to 58 days and not previously exposed to bovine viral diarrhoea virus (BVDV), were infected with this agent by nose-to-nose contact with a persistently BVDV viraemic calf. The study was conducted in two trials, using 3 calves in each. All 6 calves showed a peak interferon level in serum at 4 days post infection (dpi), and they seroconverted to BVDV at 16-21 dpi. The calves in trial 1 had diarrhoea for 2 or 3 days between 2 and 6 dpi and one calf again from 9 to 11 dpi. During the periods of fever, the calves were slightly depressed. Those in trial 2 were more depressed and their oral and nasal mucous membranes were reddened but they never had diarrhoea. In both trials, fever (up to 41.3 degrees C) was a prominent symptom at 8 to 9 dpi and 2 calves showed a diphasic fever course. Respiratory affection was mild and no medical treatment was required. Haematological assessment demonstrated a transient but significant leukopenia and lymphopenia at 4 dpi (P less than 0.01 and P less than 0.05 respectively) and 11 dpi (P less than 0.05 and P less than 0.01 respectively). A significant decrease in thrombocyte count was seen at 4 dpi (P less than 0.05, n = 3). This study has demonstrated that nose-to-nose contact is an effective way of transmitting BVDV from persistently infected to susceptible cattle.

  1. Direct laser manipulation reveals the mechanics of cell contacts in vivo.

    PubMed

    Bambardekar, Kapil; Clément, Raphaël; Blanc, Olivier; Chardès, Claire; Lenne, Pierre-François

    2015-02-03

    Cell-generated forces produce a variety of tissue movements and tissue shape changes. The cytoskeletal elements that underlie these dynamics act at cell-cell and cell-ECM contacts to apply local forces on adhesive structures. In epithelia, force imbalance at cell contacts induces cell shape changes, such as apical constriction or polarized junction remodeling, driving tissue morphogenesis. The dynamics of these processes are well-characterized; however, the mechanical basis of cell shape changes is largely unknown because of a lack of mechanical measurements in vivo. We have developed an approach combining optical tweezers with light-sheet microscopy to probe the mechanical properties of epithelial cell junctions in the early Drosophila embryo. We show that optical trapping can efficiently deform cell-cell interfaces and measure tension at cell junctions, which is on the order of 100 pN. We show that tension at cell junctions equilibrates over a few seconds, a short timescale compared with the contractile events that drive morphogenetic movements. We also show that tension increases along cell interfaces during early tissue morphogenesis and becomes anisotropic as cells intercalate during germ-band extension. By performing pull-and-release experiments, we identify time-dependent properties of junctional mechanics consistent with a simple viscoelastic model. Integrating this constitutive law into a tissue-scale model, we predict quantitatively how local deformations propagate throughout the tissue.

  2. Couple relationship education: A randomized controlled trial of professional contact and self-directed tools.

    PubMed

    Zemp, Martina; Merz, Corina A; Nussbeck, Fridtjof W; Halford, W Kim; Schaer Gmelch, Marcel; Bodenmann, Guy

    2017-04-01

    The aim of this randomized controlled trial was to examine the efficacy of an evidence-based relationship distress prevention program, the Couples Coping Enhancement Training (CCET), in dual well-earning couples and to investigate whether effects vary by (a) hours of professional contact and (b) mode of delivery (face to face vs. self-learning DVD). N = 159 couples were randomly assigned to 1 of 4 intervention conditions: (1) standard CCET (15 hours face to face), (2) compact CCET (12 hr face to face), (3) short CCET (self-learning DVD + 8 hr face to face), or (4) wait-list control group. Relationship satisfaction and dyadic coping skills were assessed by means of questionnaires completed prior to and 2 weeks after completion of the treatment, at 3-month follow-up, and at 6-month follow-up. Baseline latent change models for 2 factors showed that the CCET enhanced relationship satisfaction and dyadic coping skills in couples relative to the wait-list control group, albeit effects were small. The standard format of the CCET was not more effective than the compact or the short format indicating that reduced amount of professional contact did not decrease the treatment's efficacy and that the self-learning DVD successfully replaced the psycho-educational part of the program. Since dual earner couples usually face multiple stressors, it is a promising finding that they can strengthen their relationship with a relatively short time investment. (PsycINFO Database Record

  3. Laser-induced boiling of biological liquids in medical technologies

    NASA Astrophysics Data System (ADS)

    Chudnovskii, V. M.; Yusupov, V. I.; Dydykin, A. V.; Nevozhai, V. I.; Kisilev, A. Yu.; Zhukov, S. A.; Bagratashvili, V. N.

    2017-05-01

    Using optical and acoustic methods we study thermal and transport processes related to the boiling of biological liquids under the action of continuous-wave laser radiation having moderate power (1 - 10 W) in the near-IR range (0.97 - 1.94 μm). These processes are investigated in the course of a few particular clinical procedures aimed at the modification and removal of pathological tissues (veins, mammary gland cyst, Baker’s cyst) and tissue regeneration (intervertebral discs). In the proposed approach, the modification and destruction of biotissues are due to the fast delivery of heat by two-phase jet flows, formed in the course of liquid boiling, rather than the direct laser heating. This provides the high rate of heat delivery to the pathological biotissue, avoiding its overheating (the temperature higher than 100 °C) and undesired heating of adjacent tissues. Two main regimes of laser-induced boiling near the optical fibre tip were revealed, namely, the heterogeneous jet boiling (arising when the fibre with a blackened tip is used) and the homogeneous boiling (with the radiation absorbed in the liquid volume). Both studied regimes allow one to obtain high specific heat flows, and the domination of one of the boiling regimes is determined by the presence of absorbing coating on the fibre tip, the tissue type, as well as by its shape (e.g., the presence of channels or cavities in the tissue). It is established that the heterogeneous jet boiling at the fibre tip corresponds to the regime of superintensive bubble boiling.

  4. Uniformly valid asymptotic solutions of rod eutectic growth in directional solidification for contact angles being the normal order

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Ming; Xu, Fei

    2017-06-01

    We consider system of rod eutectic growth under directional solidification for the normal amplitude of the contact angles. The objective of this work is to obtain the uniformly valid asymptotic solutions for steady growth of rod eutectics using the asymptotic expansion method. For the contact angles being the normal order, system of rod eutectic growth will exist a boundary layer at the triple phase junction. According to different length scales, we divide the whole liquid region into three subregions. Solutions in every subregion are derived by asymptotic expansion method. Finally, all the asymptotic expansion solutions are matched in the intermediate regions and the composite solutions are obtained. Results show that the average undercooling in front of both phases are not equal. The dimensional average undercooling exhibits a minimum at the critical eutectic spacing. The critical spacing of SCN-DC is predicted and it is in agreement with the small-spacing stability limit.

  5. Organic light-emitting diodes with direct contact-printed red, green, blue, and white light-emitting layers

    NASA Astrophysics Data System (ADS)

    Chen, Sun-Zen; Peng, Shiang-Hau; Ting, Tzu-Yu; Wu, Po-Shien; Lin, Chun-Hao; Chang, Chin-Yeh; Shyue, Jing-Jong; Jou, Jwo-Huei

    2012-10-01

    We demonstrate the feasibility of using direct contact-printing in the fabrication of monochromatic and polychromatic organic light-emitting diodes (OLEDs). Bright devices with red, green, blue, and white contact-printed light-emitting layers with a respective maximum luminance of 29 000, 29 000, 4000, and 18 000 cd/m2 were obtained with sound film integrity by blending a polymeric host into a molecular host. For the red OLED as example, the maximum luminance was decreased from 29 000 to 5000 cd/m2 as only the polymeric host was used, or decreased to 7000 cd/m2 as only the molecular host was used. The markedly improved device performance achieved in the devices with blended hosts may be attributed to the employed polymeric host that contributed a good film-forming character, and the molecular host that contributed a good electroluminescence character.

  6. Chemical Composition, Modulatory Bacterial Resistance and Antimicrobial Activity of Essential Oil the Hyptis martiusii Benth by Direct and Gaseous Contact

    PubMed Central

    de Oliveira, Allan Demetrius Leite; Galvao Rodrigue, Fabiola Fernandes; Douglas Melo Coutinho, Henrique; da Costa, Jose Galberto Martins; de Menezes, Irwin Rose Alencar

    2014-01-01

    Background: Several studies have shown that species of the genus Hyptis, have promising antimicrobial and antifungal effects. Objectives: Identify of chemical constituents of essential oil from leaves of Hyptis martiusii and evaluate its effect against bacterial strains by direct and gaseous contact. Materials and Methods: Essential oil was extracted from leaves of Hyptis martiusii Benth using hydro-distillation, and its composition was determined using gas chromatography–mass spectrometry (GC-MS). Chemical analysis showed that there was a predominance of sesquiterpenes. The leaf essential oil was screened for its minimal inhibitory concentration and modulatory effect of aminoglycoside by the direct (MIC) and gaseous (MID) micro-dilution assays for various pathogenic microorganisms. The essential oil remarkably inhibited the growth of all of the tested bacteria (MIC < 512 μg/mL) except S. aureus (SA358) multidrug resistant (MRSA) by direct contact. Results: Twenty-four compounds representing 92.13% of the essential oil of leaves were characterized; δ -3-carene (6.88%), 1, 8-cineole (7.01%), trans-caryophyllene (9.21%), Cariophyllene oxide (7.47%) and bicyclogermacrene (10.61%) were found as the major components. Modulatory aminoglycoside effect, by direct contact, was showed antagonistic relationship with antimicrobial activity. The gaseous component of the oil inhibited the bacterial growth of all of the tested bacteria in 50% and 25% of oil concentration and demonstrated synergistic interactions can be attributed to the constituting the oil compounds. Conclusions: These results show that this oil influences the activity of the antibiotic and may be used as an adjuvant in the antibiotic therapy of respiratory tract bacterial pathogens. PMID:25237640

  7. An evaluation of the appropriateness of advice and healthcare contacts made following calls to NHS Direct Wales

    PubMed Central

    Snooks, Helen; Peconi, Julie; Munro, James; Cheung, Wai-Yee; Rance, Jaynie; Williams, Anne

    2009-01-01

    Background An evaluation of NHS Direct Wales (NHSDW), a national telephone-based healthcare advice and information service, was undertaken. A key objective was to describe the actions of callers and assess the appropriateness of advice and healthcare contacts made following calls, results of which are reported here. Methods Postal questionnaires were sent to consecutive callers to NHSDW in May 2002 and February 2004 to determine 1) callers' actions following calls and 2) their views about the appropriateness of: advice given; and when to seek further care. An independent clinical panel agreed and applied a set of rules about healthcare sites where examinations, investigations, treatments and referrals could be obtained. The rules were then applied to the subsequent contacts to healthcare services reported by respondents and actions were classified in terms of whether they had been necessary and sufficient for the care received. Results Response rates were similar in each survey: 1033/1897 (54.5%); 606/1204 (50.3%), with 75% reporting contacting NHSDW. In both surveys, nearly half of all callers reported making no further healthcare contact after their call to NHSDW. The most frequent subsequent contacts made were with GPs. More than four fifths of callers rated the advice given - concerning any further care needed and when to seek it - as appropriate (further care needed: survey 1: 673/729, 82.3%; survey 2: 389/421, 92.4%; when to seek further care - survey 1: 462/555, 83.2%; survey 2: n = 295/346, 85.3%). A similar proportion of cases was also rated through the rule set and backed up by the clinical panel as having taken necessary and sufficient actions following their calls to NHSDW (survey 1: 624/729, 80.6%; survey 2: 362/421, 84.4%), with more unnecessary than insufficient actions identified at each survey (survey 1: unnecessary 132/729, 17.1% versus insufficient 11/729, 1.4%; survey 2: unnecessary 47/421, 11.0% versus insufficient 14/421, 3.3%). Conclusion

  8. An evaluation of the appropriateness of advice and healthcare contacts made following calls to NHS Direct Wales.

    PubMed

    Snooks, Helen; Peconi, Julie; Munro, James; Cheung, Wai-Yee; Rance, Jaynie; Williams, Anne

    2009-09-30

    An evaluation of NHS Direct Wales (NHSDW), a national telephone-based healthcare advice and information service, was undertaken. A key objective was to describe the actions of callers and assess the appropriateness of advice and healthcare contacts made following calls, results of which are reported here. Postal questionnaires were sent to consecutive callers to NHSDW in May 2002 and February 2004 to determine 1) callers' actions following calls and 2) their views about the appropriateness of: advice given; and when to seek further care. An independent clinical panel agreed and applied a set of rules about healthcare sites where examinations, investigations, treatments and referrals could be obtained. The rules were then applied to the subsequent contacts to healthcare services reported by respondents and actions were classified in terms of whether they had been necessary and sufficient for the care received. Response rates were similar in each survey: 1033/1897 (54.5%); 606/1204 (50.3%), with 75% reporting contacting NHSDW. In both surveys, nearly half of all callers reported making no further healthcare contact after their call to NHSDW. The most frequent subsequent contacts made were with GPs.More than four fifths of callers rated the advice given - concerning any further care needed and when to seek it - as appropriate (further care needed: survey 1: 673/729, 82.3%; survey 2: 389/421, 92.4%; when to seek further care - survey 1: 462/555, 83.2%; survey 2: n = 295/346, 85.3%). A similar proportion of cases was also rated through the rule set and backed up by the clinical panel as having taken necessary and sufficient actions following their calls to NHSDW (survey 1: 624/729, 80.6%; survey 2: 362/421, 84.4%), with more unnecessary than insufficient actions identified at each survey (survey 1: unnecessary 132/729, 17.1% versus insufficient 11/729, 1.4%; survey 2: unnecessary 47/421, 11.0% versus insufficient 14/421, 3.3%). Based on NHSDW caller surveys responses

  9. Direct determination of contact angles of model soils in comparison with wettability characterization by capillary rise

    NASA Astrophysics Data System (ADS)

    Ramírez-Flores, Juan Carlos; Bachmann, Jörg; Marmur, Abraham

    2010-03-01

    SummaryAn accurate method to determine contact angles (CA) of soils as a measure of water repellency is still missing. In the present research, we evaluated and compared different methods to determine the CA of dry soil samples. Experiments were made by using a set of porous materials (silt, sand and glass beads) with different levels of water repellency. The CAs were measured with the Capillary Rise Method ( θCRM; liquid penetration into a 3-d system), the Wilhelmy plate method ( θWPM; measurement of capillary forces acting on a plane sample) and the Sessile Drop Method ( θSDM; optical CA analysis of drop contour on a plane sample). Results were compared with the CAs calculated from capillary rise in long vertical columns ( θECR), where liquid profiles of the final capillary rise of water and ethanol, respectively, were used to derive the contact angle under the assumed equilibrium conditions. The results showed the overestimation of the CA by using the well established bi-liquid CRM technique for porous materials, in particular for material with a low degree of water repellency (CA < 40°) and for the finer textured materials. In contrast, a variant of the Wilhelmy plate method, i.e. the cosine-averaged advancing CA and receding CA ( θEWPM), as well as the Sessile Drop CA, θSDM, were close to the ones of θECR. We concluded that θEWPM and θSDM are apparent CA, but nevertheless able to predict the impact of wettability on the final capillary rise which is affected by pore topology as well as by wettability.

  10. Collagen-nanofiber hydrogel composites promote contact guidance of human lymphatic microvascular endothelial cells and directed capillary tube formation.

    PubMed

    Laco, Filip; Grant, M Helen; Black, Richard A

    2013-06-01

    Collagen and fibronectin matrices are known to stimulate migration of microvascular endothelial cells and the process of tubulogenesis, but the physical, chemical, and topographical cues for directed vessel formation have yet to be determined. In this study, growth, migration, elongation, and tube formation of human lymphatic microvascular endothelial cells (LECs) were investigated on electrospun poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(L-lactic-co-D-lactic acid) (PLDL) nanofiber-coated substrates, and correlated with fiber density and diameter. Directed migration of LECs was observed in the presence of aligned nanofibers, whereas random fiber alignment slowed down migration and growth of LECs. Cell guidance was significantly enhanced in the presence of more hydrophobic PLDL polymer nanofibers compared to PLGA (10:90). Subsequent experiments with tube-forming assays reveal the ability of resorbable hydrophobic nanofibers >300 nm in diameter to promote cell guidance in collagen gels without direct cell-fiber contact, in contrast to the previously reported contact-guidance phenomena. Our results show that endothelial cell guidance is possible within nanofiber/collagen-gel constructs that mimic the native extracellular matrix in terms of size and orientation of fibrillar components.

  11. Noise analysis of nucleate boiling

    NASA Technical Reports Server (NTRS)

    Mcknight, R. D.; Ram, K. S.

    1971-01-01

    The techniques of noise analysis have been utilized to investigate nucleate pool boiling. A simple experimental setup has been developed for obtaining the power spectrum of a nucleate boiling system. These techniques were first used to study single bubbles, and a method of relating the two-dimensional projected size and the local velocity of the bubbles to the auto-correlation functions is presented. This method is much less time consuming than conventional methods of measurement and has no probes to disturb the system. These techniques can be used to determine the contribution of evaporation to total heat flux in nucleate boiling. Also, these techniques can be used to investigate the effect of various parameters upon the frequency response of nucleate boiling. The predominant frequencies of the power spectrum correspond to the frequencies of bubble generation. The effects of heat input, degree of subcooling, and liquid surface tension upon the power spectra of a boiling system are presented. It was found that the degree of subcooling has a more pronounced effect upon bubble size than does heat flux. Also the effect of lowering surface tension can be sufficient to reduce the effect of the degree of subcooling upon the size of the bubbles.

  12. Field test of two high-pressure, direct-contact downhole steam generators. Volume I. Air/diesel system

    SciTech Connect

    Marshall, B.W.

    1983-05-01

    As a part of the Project DEEP STEAM to develop technology to more efficiently utilize steam for the recovery of heavy oil from deep reservoirs, a field test of a downhole steam generator (DSG) was performed. The DSG burned No. 2 diesel fuel in air and was a direct-contact, high pressure device which mixed the steam with the combustion products and injected the resulting mixture directly into the oil reservoir. The objectives of the test program included demonstration of long-term operation of a DSG, development of operational methods, assessment of the effects of the steam/combustion gases on the reservoir and comparison of this air/diesel DSG with an adjacent oxygen/diesel direct contact generator. Downhole operation of the air/diesel DSG was started in June 1981 and was terminated in late February 1982. During this period two units were placed downhole with the first operating for about 20 days. It was removed, the support systems were slightly modified, and the second one was operated for 106 days. During this latter interval the generator operated for 70% of the time with surface air compressor problems the primary source of the down time. Thermal contact, as evidenced by a temperature increase in the production well casing gases, and an oil production increase were measured in one of the four wells in the air/diesel pattern. Reservoir scrubbing of carbon monoxide was observed, but no conclusive data on scrubbing of SO/sub x/ and NO/sub x/ were obtained. Corrosion of the DSG combustor walls and some other parts of the downhole package were noted. Metallurgical studies have been completed and recommendations made for other materials that are expected to better withstand the downhole combustion environment. 39 figures, 8 tables.

  13. The Degradation Interface of Magnesium Based Alloys in Direct Contact with Human Primary Osteoblast Cells

    PubMed Central

    Willumeit-Römer, Regine; Laipple, Daniel; Luthringer, Bérengère; Feyerabend, Frank

    2016-01-01

    Magnesium alloys have been identified as a new generation material of orthopaedic implants. In vitro setups mimicking physiological conditions are promising for material / degradation analysis prior to in vivo studies however the direct influence of cell on the degradation mechanism has never been investigated. For the first time, the direct, active, influence of human primary osteoblasts on magnesium-based materials (pure magnesium, Mg-2Ag and Mg-10Gd alloys) is studied for up to 14 days. Several parameters such as composition of the degradation interface (directly beneath the cells) are analysed with a scanning electron microscope equipped with energy dispersive X-ray and focused ion beam. Furthermore, influence of the materials on cell metabolism is examined via different parameters like active mineralisation process. The results are highlighting the influences of the selected alloying element on the initial cells metabolic activity. PMID:27327435

  14. The Degradation Interface of Magnesium Based Alloys in Direct Contact with Human Primary Osteoblast Cells.

    PubMed

    Ahmad Agha, Nezha; Willumeit-Römer, Regine; Laipple, Daniel; Luthringer, Bérengère; Feyerabend, Frank

    2016-01-01

    Magnesium alloys have been identified as a new generation material of orthopaedic implants. In vitro setups mimicking physiological conditions are promising for material / degradation analysis prior to in vivo studies however the direct influence of cell on the degradation mechanism has never been investigated. For the first time, the direct, active, influence of human primary osteoblasts on magnesium-based materials (pure magnesium, Mg-2Ag and Mg-10Gd alloys) is studied for up to 14 days. Several parameters such as composition of the degradation interface (directly beneath the cells) are analysed with a scanning electron microscope equipped with energy dispersive X-ray and focused ion beam. Furthermore, influence of the materials on cell metabolism is examined via different parameters like active mineralisation process. The results are highlighting the influences of the selected alloying element on the initial cells metabolic activity.

  15. Thermohydrodynamics of boiling in binary compressible fluids

    NASA Astrophysics Data System (ADS)

    Liu, Jiewei; Do-Quang, Minh; Amberg, Gustav

    2015-10-01

    We numerically study the thermohydrodynamics of boiling for a CO2 + ethanol mixture on lyophilic and lyophobic surfaces in both closed and open systems, based on a diffuse interface model for a two-component system. The corresponding wetting boundary conditions for an isothermal system are proposed and verified in this paper. New phenomena due to the addition of another component, mainly the preferential evaporation of the more volatile component, are observed. In the open system and the closed system, the physical process shows very different characteristics. In the open system, except for the movement of the contact line, the qualitative features are rather similar for lyophobic and lyophilic surfaces. In the closed system, the vortices that are observed on a lyophobic surface are not seen on a lyophilic surface. More sophisticated wetting boundary conditions for nonisothermal, two-component systems might need to be further developed, taking into account the variations of density, temperature, and surface tension near the wall, while numerical results show that the boundary conditions proposed here also work well even in boiling, where the temperature is nonuniform.

  16. Rapid Screening of Immobilized Amine CO2 Sorbents for Steam Stability by Their Direct Contact with Liquid H2 O.

    PubMed

    Wilfong, Walter Christopher; Kail, Brian W; Gray, McMahan L

    2015-06-22

    Rapid testing of hydrophilic and hydrophobic basic immobilized amine sorbents (BIAS) for CO2 capture stability under practical conditions was achieved by direct contact of the sorbents with flowing liquid water. Losses in both CO2 capture capacity and amine content of sorbents after exposure to 0.5 mL min(-1) of H2 O at 25 °C for 40 min followed similar trends as losses observed after exposure to N2 /steam (105 °C, 7 % H2 O) for 10 h. We also found that hydrophobic TMPED helped stabilize sorbents to H2 O, which was confirmed by DRIFTS and combined TGA-DSC.

  17. SHORT CONTACT TIME DIRECT COAL LIQUEFACTION USING A NOVEL BATCH REACTOR

    SciTech Connect

    Michael T. Klein; William H. Calkins

    1997-10-29

    The overall goal of this research is to develop an understanding of the Direct Coal Liquefaction process at the molecular level. Many approaches have been used to study this process including kinetic studies, study of the liquefaction products, study of the effect of reaction variables, such as temperature, solvent type and composition, the changing nature and composition of the coal during liquefaction, and the distribution in the liquefaction products of the hydrogen consumed. While all these studies have contributed to our growing knowledge of the liquefaction process, an adequate understanding of direct liquefaction still eludes us. This is due to many reasons including: the complexity and variable nature of coal itself and the many different chemical reactions which are occurring simultaneously during direct coal liquefaction. We believe that a study of the liquefaction process at the very early stages will avoid the complexities of secondary reactions associated with free radical high temperature processes that are clearly involved in direct coal liquefaction. This prompted us to devise a reactor system which avoids long heat up and cool-down times associated with previous kinetic studies, and allows kinetic measurements even at as short as the first few seconds of the liquefaction reaction.

  18. Cytotoxicity of dimethyl sulfoxide (DMSO) in direct contact with odontoblast-like cells.

    PubMed

    Hebling, J; Bianchi, L; Basso, F G; Scheffel, D L; Soares, D G; Carrilho, M R O; Pashley, D H; Tjäderhane, L; de Souza Costa, C A

    2015-04-01

    To evaluate the cytotoxicity of dimethyl sulfoxide (DMSO) on the repair-related activity of cultured odontoblast-like MDPC-23 cells. Solutions with different concentrations of DMSO (0.05, 0.1, 0.3, 0.5 and 1.0 mM), diluted in culture medium (DMEM), were placed in contact with MDPC-23 cells (5 × 104 cells/cm(2)) for 24 h. Eight replicates (n = 8) were prepared for each solutions for the following methods of analysis: violet crystal dye for cell adhesion (CA), quantification of total protein (TP), alizarin red for mineralization nodules formation (MN) and cell death by necrosis (flow cytometry); while twelve replicates (n = 12) were prepared for viable cell number (Trypan Blue) and cell viability (MTT assay). Data were analyzed by ANOVA and Tukey or Kruskal-Wallis and Mann-Whitney's tests (p < 0.05). Cell viability, adhesion and percentage of cell death by necrosis were not affected by DMSO at any concentration, with no statistical significant difference among the groups. A significant reduction in total protein production was observed for 0.5 and 1.0 mM of DMSO compared to the control while increased mineralized nodules formation was seen only for 1.0 mM DMSO. DMSO caused no or minor cytotoxic effects on the pulp tissue repair-related activity of odontoblast-like cells. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. The modes of physician remuneration and their effect on direct patient contact.

    PubMed

    Basu, Kisalaya; Mandelzys, David

    2008-01-01

    Initiatives such as primary care reform have allocated millions of dollars towards the Canadian health care system. The way physicians are remunerated affects the supply of physician services and as such is essential to these initiatives to facilitate policy goals. However, there exists a gap in understanding how different modes of remuneration affect physician-patient contact. This paper examines if there is a significant difference between the average full-time-equivalent (FTE) of family physicians (FPs) remunerated through fee-for-service (FFS), salary, and blended arrangements. We used Nova Scotia physician billings dataset which tracks every services performed by both FFS and salaried physicians over the fiscal year 2003 to 2004. We estimated two semi-logarithmic models to examine the relationship between (1) modes of remuneration and FTE, and (2) modes of remuneration and total services, using ordinary least squares method. The National Physician Survey shows a significant difference between the current modes of remuneration and the preferred modes of remuneration; thus ruling out the possibility of selectivity bias. The results show that compared to the FFS FPs, the salaried FPs and blended FPs produce on average 40.46% and 23.13% less FTE respectively. It also indicates that compared to the FFS FPs, the salaried FPs and blended FPs deliver 53.54% and 31.49% fewer services on average.

  20. Light-addressable amperometric electrodes for enzyme sensors based on direct quantum dot-electrode contacts

    NASA Astrophysics Data System (ADS)

    Riedel, M.; Göbel, G.; Parak, W. J.; Lisdat, F.

    2014-03-01

    Quantum dots allow the generation of charge carriers upon illumination. When these particles are attached to an electrode a photocurrent can be generated. This allows their use as a light-switchable layer on the surface. The QDs can not only exchange electronics with the electrode, but can also interact with donor or acceptor compounds in solution providing access to the construction of signal chains starting from an analytic molecule. The magnitude and the direction of the photocurrent depend on several factors such as electrode polarization, solution pH and composition. These defined dependencies have been evaluated with respect to the combination of QD-electrodes with enzyme reactions for sensorial purpose. CdSe/ZnS-QD-modified electrodes can be used to follow enzymatic reactions in solution based on the oxygen sensitivity. In order to develop a photoelectrochemical biosensor, e.g. glucose oxidase is immobilized on the CdSe/ZnS-electrode. One immobilization strategy applies the layer-by-layer-technique of GOD and a polyelectrolyte. Photocurrent measurements of such a sensor show a clear concentration dependent behavior. The principle of combing QD oxidase. The sensitivity of quantum dot electrodes can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be demonstrated that direct electron transfer from excited quantum dots can be achieved with the redox protein cytochrome c. This allows the detection of the protein, but also interaction partners such as a enzymes or superoxide.

  1. Fundamental Study of Direct Contact Cold Energy Release by Flowing Hot Air through Ice Particles Packed Layer

    NASA Astrophysics Data System (ADS)

    Aoyama, Sigeo; Inaba, Hideo

    This paper has dealt with the direct contact heat exchange characteristics between ice particles (average ice particle diameter : 3.10mm) packed in the rectangular cold energy storage vessel and flowing hot air as a heat transfer medium. The hot air bubbles ascended in the fluidized ice particles layer, and they were cooled down directly by melting ice particles. The temperature efficiency increased as Reynolds number Re increased because the hot air flowing in the layer became active. The dehumidity efficiency increased with an increase in modified Stefan number and Re, since the heat capacity of inlet air and heat transfer coefficient increased. Finally, some empirical correlations for temperature efficiency, dehumidity efficiency and the completion time of cold energy release were derived in terms of various nondimensional parameters.

  2. Glial-Restricted Precursors Protect Neonatal Brain Slices from Hypoxic-Ischemic Cell Death Without Direct Tissue Contact.

    PubMed

    Sweda, Romy; Phillips, Andre W; Marx, Joel; Johnston, Michael V; Wilson, Mary Ann; Fatemi, Ali

    2016-07-01

    Glial-Restricted Precursors (GRPs) are tripotential progenitors that have been shown to exhibit beneficial effects in several preclinical models of neurological disorders, including neonatal brain injury. The mechanisms of action of these cells, however, require further study, as do clinically relevant questions such as timing and route of cell administration. Here, we explored the effects of GRPs on neonatal hypoxia-ischemia during acute and subacute stages, using an in vitro transwell co-culture system with organotypic brain slices exposed to oxygen-glucose deprivation (OGD). OGD-exposed slices that were then co-cultured with GRPs without direct cell contact had decreased tissue injury and cortical cell death, as evaluated by lactate dehydrogenase (LDH) release and propidium iodide (PI) staining. This effect was more pronounced when cells were added during the subacute phase of the injury. Furthermore, GRPs reduced the amount of glutamate in the slice supernatant and changed the proliferation pattern of endogenous progenitor cells in brain slices. In summary, we show that GRPs exert a neuroprotective effect on neonatal hypoxia-ischemia without the need for direct cell-cell contact, thus confirming the rising view that beneficial actions of stem cells are more likely attributable to trophic or immunomodulatory support rather than to long-term integration.

  3. Direct Human Contact with Siloxanes (Silicones) – Safety or Risk Part 1. Characteristics of Siloxanes (Silicones)

    PubMed Central

    Mojsiewicz-Pieńkowska, Krystyna; Jamrógiewicz, Marzena; Szymkowska, Katarzyna; Krenczkowska, Dominika

    2016-01-01

    Siloxanes are commonly known as silicones. They belong to the organosilicon compounds and are exclusively obtained by synthesis. Their chemical structure determines a range of physicochemical properties which were recognized as unique. Due to the susceptibility to chemical modifications, ability to create short, long or complex polymer particles, siloxanes found an application in many areas of human life. Siloxanes differ in particle size, molecular weight, shape and chemical groups. As a result, this determines the different physico-chemical properties, that directly affect the safety or the risk of their use. The areas that can be a source of danger to human health will be commented in this paper. PMID:27303296

  4. Polymer Electrolyte Fuel Cells Membrane Hydration by Direct Liquid Water Contact

    SciTech Connect

    Wilson, M.S.; Zawodzinski, C.; Gottesfeld, S.

    1998-11-01

    An effective means of providing direct liquid hydration of the membrane tends to improve performance particularly of cells with thicker membranes or at elevated temperatures. Supplying the water to the membrane from the anode flow-field through the anode backing via wicks would appear to have advantages over delivering the water through the thickness of the membrane with regards to the uniformity and stability of the supply and the use of off-the-shelf membranes or MEAs. In addition to improving cell performance, an important contribution of direct liquid hydration approaches may be that the overall fuel cell system becomes simpler and more effective. The next steps in the evolution of this approach are a demonstration of the effectiveness of this technique with larger active area cells as well as the implementation of an internal flow-field water reservoir (to eliminate the injection method). Scale-up to larger cell sizes and the use of separate water channels within the anode flow-field is described.

  5. Modified Sagnac interferometer for contact-free length measurement of a direct absorption cell.

    PubMed

    Elandaloussi, Hadj; Rouillé, Christian; Marie-Jeanne, Patrick; Janssen, Christof

    2016-03-10

    Accurate path length measurements in absorption cells are recurrent requirements in quantitative molecular absorption spectroscopy. A new twin path laser interferometer for length measurements in a simple direct path absorption geometry is presented, along with a full uncertainty budget. The path in an absorption cell is determined by measuring the optical path length change due to the diminution of the refractive index when the cell originally filled with nitrogen gas is evacuated. The performance of the instrument based on a stabilized HeNe laser is verified by comparison with the results of direct mechanical length measurements of a roughly 45 mm long, specially designed absorption cell. Due to a resolution of about 1/300 of a HeNe fringe, an expanded (coverage factor k=2) uncertainty of 16 μm in the length measurement is achieved, providing an expanded relative uncertainty of 3.6·10⁻⁴ for the length of our test absorption cell. This value is about 8 times lower than what has been reported previously. The instrument will be useful for precision measurements of absorption cross sections of strong absorbers which require short light paths, such as ozone, halogen oxides, sulfur dioxide, and volatile organic compounds in the UV.

  6. Characteristics of Transient Boiling Heat Transfer

    SciTech Connect

    Liu, Wei; Monde, Masanori; Mitsutake, Y.

    2002-07-01

    In this paper, one dimensional inverse heat conduction solution is used for a measurement of pool boiling curve. The experiments are performed under atmospheric pressure for copper, brass, carbon steel and gold. Boiling curves, including unsteady transition boiling region, are found can be traced fairly well from a simple experiment system by solving inverse heat conduction solution. Boiling curves for steady heating and transient heating, for heating process and cooling process are compared. Surface behavior around CHF point, transition boiling and film-boiling regions are observed by using a high-speed camera. The results show the practicability of the inverse heat conduction solution in tracing boiling curve and thereby supply us a new way in boiling heat transfer research. (authors)

  7. Theoretical modeling of CHF for near-saturated pool boiling and flow boiling from short heaters using the interfacial lift-off criterion

    SciTech Connect

    Mudawar, I.; Galloway, J.E.; Gersey, C.O.

    1995-12-31

    Pool boiling and flow boiling were examined for near-saturated bulk conditions in order to determine the critical heat flux (CHF) trigger mechanism for each. Photographic studies of the wall region revealed features common to both situations. At fluxes below CHF, the vapor coalesces into a wavy layer which permits wetting only in wetting fronts, the portions of the liquid-vapor interface which contact the wall as a result of the interfacial waviness. Close examination of the interfacial features revealed the waves are generated from the lower edge of the heater in pool boiling and the heater`s upstream region in flow boiling. Wavelengths follow predictions based upon the Kelvin-Helmholtz instability criterion. Critical heat flux in both cases occurs when the pressure force exerted upon the interface due to interfacial curvature, which tends to preserve interfacial contact with the wall prior to CHF, is overcome by the momentum of vapor at the site of the first wetting front, causing the interface to lift away from the wall. It is shown this interfacial lift-off criterion facilitates accurate theoretical modeling of CHF in pool boiling and in flow boiling in both straight and curved channels.

  8. Boiling heat transfer during flow of distilled water in an asymmetrically heated rectangular minichannel

    NASA Astrophysics Data System (ADS)

    Strąk, Kinga; Piasecka, Magdalena

    This paper discusses test results concerning flow boiling heat transfer in a minichannel 1.7 mm in depth, 16 mm in width and 180 mm in length. The essential part of the experimental stand was a vertically oriented rectangular minichannel, which was heated asymmetrically with a plate made of Haynes-230 alloy. Distilled water was used as the cooling fluid. Changes in the temperature on the outer side of the heated plate in the central, axially symmetric part of the channel were measured using infrared thermography. Simultaneously, the other side of the heated plate in contact with the fluid was observed through a glass pane to identify the two-phase flow patterns. The one-dimensional model used for the heat transfer analysis took into account the heat flow direction, which was perpendicular to the direction of the fluid flow in the minichannel. The study involved determining local values of the heat transfer coefficient and generating boiling curves. The data for water were compared with the findings reported for the FC-72 fluid.

  9. Strategies to enable directed self-assembly contact hole shrink for tight pitches

    NASA Astrophysics Data System (ADS)

    Schmidt, Kristin; Osaki, Hitoshi; Nishino, Kota; Sanchez, Martha; Liu, Chi-Chun; Furukawa, Tsuyoshi; Chi, Cheng; Pitera, Jed; Felix, Nelson; Sanders, Daniel

    2016-04-01

    In recent years major advancements have been made in the directed self-assembly (DSA) of block copolymers (BCP). DSA is now widely regarded as a leading complementary patterning technique for future node integrated circuit (IC) device manufacturing and is considered for the 7 nm node. One of the most straightforward approaches for implementation of DSA is via patterning by graphoepitaxy. In this approach, the guiding pattern dictates the location and pitch of the resulting hole structures while the material properties of the BCP control the feature size and uniformity. Tight pitches need to be available for a successful implementation of DSA for future node via patterning which requires DSA in small guiding pattern CDs. Here, we show strategies how to enable the desired CD shrink in these small guiding pattern vias by utilizing high χ block copolymers and/or controlling the surface properties of the template, i.e. sidewall and bottom affinity to the blocks.

  10. Experiments and analysis on the molten-salt direct-contact absorption receiver concept

    SciTech Connect

    Bohn, M S; Wang, K Y

    1986-11-01

    This paper presents results of recent experiments on the Direct Absorption Receiver (DAR) concept using molten salt as the working fluid. The DAR concept may result in a solar central receiver that costs 50% less than the current tube receiver and has significantly lower operational and maintenance costs. These experiments were aimed at determining whether the DAR concept is technically feasible and were carried out at the Advanced Components Test Facility, Atlanta, GA. Results are based on several days of operating with solar flux ranging up to 50 W/cm/sup 2/ and also on a numerical model that is capable of predicting the thermal performance of the DAR salt film. Issues relating to thermal efficiency, absorber-to-salt heat transfer, and salt film stability are addressed.

  11. Direct contact liquid-liquid heat exchanger for solar heated and cooled buildings

    NASA Astrophysics Data System (ADS)

    Karaki, S.; Brothers, P.

    1980-06-01

    The technical and economic feasibility of using a direct contract liquid-liquid heat exchanger (DCLLHE) storage unit in a solar heating and cooling system is established. Experimental performance data were obtained from the CSU Solar House I using a DCLLHE for both heating and cooling functions. A simulation model for the system was developed. The model was validated using the experimental data and applied in five different climatic regions of the country for a complete year. The life-cycle cost of the system was estimated for each application. The results are compared to a conventional solar system, using a standard shell-and-tube heat exchanger. It is concluded that while there is a performance advantage with a DCLLHE system over a conventional solar system, the advantage is not sufficiently large to overcome slightly higher capital and operating costs for the DCLLHE system.

  12. Droplet impingement dynamics: effect of surface temperature during boiling and non-boiling conditions

    NASA Astrophysics Data System (ADS)

    Shen, Jian; Liburdy, James A.; Pence, Deborah V.; Narayanan, Vinod

    2009-11-01

    This study investigates the hydrodynamic characteristics of droplet impingement on heated surfaces and compares the effect of surface temperature when using water and a nanofluid on a polished and nanostructured surface. Results are obtained for an impact Reynolds number and Weber number of approximately 1700 and 25, respectively. Three discs are used: polished silicon, nanostructured porous silicon and gold-coated polished silicon. Seven surface temperatures, including single-phase (non-boiling) and two-phase (boiling) conditions, are included. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. Results of water and a water-based single-wall carbon-nanotube nanofluid impinging on a polished silicon surface are compared to determine the effects of nanoparticles on impinging dynamics. The nanofluid results in larger spreading velocities, larger spreading diameters and an increase in early-stage dynamic contact angle. Results of water impinging on both polished silicon and nanostructured silicon show that the nanostructured surface enhances the heat transfer for evaporative cooling at lower surface temperatures, which is indicated by a shorter evaporation time. Using a nanofluid or a nanostructured surface can reduce the total evaporation time up to 20% and 37%, respectively. Experimental data are compared with models that predict dynamic contact angle and non-dimensional maximum spreading diameter. Results show that the molecular-kinetic theory's dynamic contact angle model agrees well with current experimental data for later times, but over-predicts at early times. Predictions of maximum spreading diameter based on surface energy analyses indicate that these models over-predict unless empirical coefficients are adjusted to fit the test conditions. This is a consequence of underestimates of the dissipative energy for the conditions studied.

  13. Subcooled forced convection boiling of trichlorotrifluoroethane

    NASA Technical Reports Server (NTRS)

    Dougall, R. S.; Panian, D. J.

    1972-01-01

    Experimental heat-transfer data were obtained for the forced-convection boiling of trichlorotrifluoroethane (R-113 or Freon-113) in a vertical annular test annular test section. The 97 data points obtained covered heat transfer by forced convection, local boiling, and fully-developed boiling. Correlating methods were obtained which accurately predicted the heat flux as a function of wall superheat (boiling curve) over the range of parameters studied.

  14. Contact corrosion measurements on the pair UO 2+ x and carbon steel 1.0330 in brines and bentonite porewater with respect to direct waste disposal

    NASA Astrophysics Data System (ADS)

    Engelhardt, J.; Marx, G.

    1999-01-01

    Contact corrosion between carbon steel and UO 2 was studied in the MgCl 2 rich Q-brine, in bentonite porewater and in saturated NaCl solution by use of contact potential and contact current measurements. In all solutions the carbon steel dominates the contact potential, so that this potential is near to the rest potential of the carbon steel. Only in solutions without precipitation of iron corrosion products, the presence of metallic iron slightly reduces the UO 2 corrosion rate. If iron corrosion products precipitate, the relevant adsorption of the uranium species will be more effective than any direct cathodic corrosion protection.

  15. Different cytotoxicity responses to antimicrobial nanosilver coatings when comparing extract-based and direct-contact assays.

    PubMed

    Sussman, Eric M; Casey, Brendan J; Dutta, Debargh; Dair, Benita J

    2015-06-01

    This study was performed to understand how the choice of cytotoxicity assay format affects the observed biocompatibility of nanosilver (nAg). nAg coatings are physical coatings containing silver (Ag) that have feature sizes of 100 nm or less, often in the form of nanoparticles or grains. They are used on medical devices to prevent infection, but in spite of this intended benefit, observations of potential cytotoxicity from nAg have been reported in numerous published studies. For medical device regulation, cytotoxicity testing is part of a biocompatibility evaluation, in which specific test methods are chosen based on the technological characteristics and intended use of a device. For this study, nAg-coated tissue culture polystyrene surfaces were prepared using magnetron sputter coating, resulting in nAg films of 0.2 to 311 µg cm(-2) Ag. These coatings exhibited nanometer-scale morphologies and demonstrated a > 4log10 reduction in Escherichia coli viability. It was observed that extracts of nAg caused no cytotoxicity to L929 mouse fibroblasts, but cells cultured directly on nAg coatings (direct-contact assay format) showed a dose-dependent reduction in viability by up to 100% (P < 0.001). Results using inductively coupled plasma mass spectrometry to measure Ag release suggested that extracts of nAg are not toxic because the dissolved Ag in those samples becomes less cytotoxic over time, probably owing to the reaction with cell culture media and serum (six-fold cytotoxicity reductions observed over a 24-h period). These findings highlight the potential value of direct-contact cytotoxicity testing for nAg in predicting biological interactions with cells or tissue in vivo. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

  16. Migration by 'direct' or 'indirect' food contact? 'Dry' and 'wetting' foods? Experimental data for 'touching' contact of dry foods with paper and board.

    PubMed

    Eicher, Angela; Biedermann, Maurus; Zurfluh, Michael; Grob, Koni

    2015-01-01

    Food contact is characterised in various terms, all of which are somewhat ill-defined. This work investigated the simplification that migration from food contact materials into dry food virtually exclusively proceeds through the gas phase, which would imply that the migration of essentially non-volatile components is negligible. It is shown here that this is not necessarily appropriate: for newspaper printed with an ink based on essentially non-volatile polyalphaolefins (PAO) as the main solvent, the migration into polenta and a baking mix reached 64% and 66% respectively of the content in the paper in merely 20 days at ambient temperature. Migration of involatile substances into dry foods implies diffusion through the paper to the small contact points. It depended on particle size, as this determines the density of the contacts. The diffusion rates within the food contact material and the food, including the transfer from one particle to the next, are other determining factors. This leaves the question whether such migration can be modelled or tested in a systematic manner (simulation), or whether it needs to be determined on a case-by-case basis.

  17. Boiling process modelling peculiarities analysis of the vacuum boiler

    NASA Astrophysics Data System (ADS)

    Slobodina, E. N.; Mikhailov, A. G.

    2017-06-01

    The analysis of the low and medium powered boiler equipment development was carried out, boiler units possible development directions with the purpose of energy efficiency improvement were identified. Engineering studies for the vacuum boilers applying are represented. Vacuum boiler heat-exchange processes where boiling water is the working body are considered. Heat-exchange intensification method under boiling at the maximum heat- transfer coefficient is examined. As a result of the conducted calculation studies, heat-transfer coefficients variation curves depending on the pressure, calculated through the analytical and numerical methodologies were obtained. The conclusion about the possibility of numerical computing method application through RPI ANSYS CFX for the boiling process description in boiler vacuum volume was given.

  18. Heat transfer research on enhanced heating surfaces in pool boiling

    NASA Astrophysics Data System (ADS)

    Kalawa, Wojciech; Wójcik, Tadeusz M.; Piasecka, Magdalena

    The paper focuses on the analysis of the enhanced surfaces in such applications as boiling heat transfer. The testing measurement module with enhanced heating surfaces was used for pool boiling research. Pool boiling experiments were conducted with distilled water at atmospheric pressure in the vessel using an enhanced sample as the bottom heating surface. The samples are soldered to a copper heating block of the round cross-section .They were placed: in the fluid (saturation temperature measurement), under the sample for temperature determination. A vessel made of four flat glass panes was used for visualization. The heated surfaces in contact with the fluid differed in roughness were smooth or enhanced. This paper analyzes the effects of the microstructured heated surface on the heat transfer coefficient. The results are presented as relationships between the heat transfer coefficient and the heat flux and as boiling curves. The experimental data obtained for the two types of enhanced heated surfaces was compared with the results recorded for the smooth heated surface. The highest local values of the heat transfer coefficient were reported for the enhanced surfaces.

  19. Modeling 3D conjugate heat and mass transfer for turbulent air drying of Chilean papaya in a direct contact dryer

    NASA Astrophysics Data System (ADS)

    Lemus-Mondaca, Roberto A.; Vega-Gálvez, Antonio; Zambra, Carlos E.; Moraga, Nelson O.

    2017-01-01

    A 3D model considering heat and mass transfer for food dehydration inside a direct contact dryer is studied. The k- ɛ model is used to describe turbulent air flow. The samples thermophysical properties as density, specific heat, and thermal conductivity are assumed to vary non-linearly with temperature. FVM, SIMPLE algorithm based on a FORTRAN code are used. Results unsteady velocity, temperature, moisture, kinetic energy and dissipation rate for the air flow are presented, whilst temperature and moisture values for the food also are presented. The validation procedure includes a comparison with experimental and numerical temperature and moisture content results obtained from experimental data, reaching a deviation 7-10 %. In addition, this turbulent k- ɛ model provided a better understanding of the transport phenomenon inside the dryer and sample.

  20. Direct-contact condensers for open-cycle OTEC applications: Model validation with fresh water experiments for structured packings

    SciTech Connect

    Bharathan, D.; Parsons, B.K.; Althof, J.A.

    1988-10-01

    The objective of the reported work was to develop analytical methods for evaluating the design and performance of advanced high-performance heat exchangers for use in open-cycle thermal energy conversion (OC-OTEC) systems. This report describes the progress made on validating a one-dimensional, steady-state analytical computer of fresh water experiments. The condenser model represents the state of the art in direct-contact heat exchange for condensation for OC-OTEC applications. This is expected to provide a basis for optimizing OC-OTEC plant configurations. Using the model, we examined two condenser geometries, a cocurrent and a countercurrent configuration. This report provides detailed validation results for important condenser parameters for cocurrent and countercurrent flows. Based on the comparisons and uncertainty overlap between the experimental data and predictions, the model is shown to predict critical condenser performance parameters with an uncertainty acceptable for general engineering design and performance evaluations. 33 refs., 69 figs., 38 tabs.

  1. Direct measurement on the geometric phase of a double quantum dot qubit via quantum point contact device

    PubMed Central

    Liu, Bao; Zhang, Feng-Yang; Song, Jie; Song, He-Shan

    2015-01-01

    We propose a direct measurement scheme to read out the geometric phase of a coupled double quantum dot system via a quantum point contact(QPC) device. An effective expression of the geometric phase has been derived, which relates the geometric phase of the double quantum dot qubit to the current through QPC device. All the parameters in our expression are measurable or tunable in experiment. Moreover, since the measurement process affects the state of the qubit slightly, the geometric phase can be protected. The feasibility of the scheme has been analyzed. Further, as an example, we simulate the geometrical phase of a qubit when the QPC device is replaced by a single electron transistor(SET). PMID:26121538

  2. Direct-contact condensers for open-cycle OTEC applications: Model validation with fresh water experiments for structured packings

    NASA Astrophysics Data System (ADS)

    Bharathan, D.; Parsons, B. K.; Althof, J. A.

    1988-10-01

    The objective of the reported work was to develop analytical methods for evaluating the design and performance of advanced high-performance heat exchangers for use in open-cycle thermal energy conversion (OC-OTEC) systems. This report describes the progress made on validating a one-dimensional, steady-state analytical computer of fresh water experiments. The condenser model represents the state of the art in direct-contact heat exchange for condensation for OC-OTEC applications. This is expected to provide a basis for optimizing OC-OTEC plant configurations. Using the model, we examined two condenser geometries, a cocurrent and a countercurrent configuration. This report provides detailed validation results for important condenser parameters for cocurrent and countercurrent flows. Based on the comparisons and uncertainty overlap between the experimental data and predictions, the model is shown to predict critical condenser performance parameters with an uncertainty acceptable for general engineering design and performance evaluations.

  3. Direct contact cytotoxicity assays for filter-collected, carbonaceous (soot) nanoparticulate material and observations of lung cell response

    NASA Astrophysics Data System (ADS)

    Soto, K. F.; Garza, K. M.; Shi, Y.; Murr, L. E.

    A simple, direct contact, cytotoxicity (in vitro) assay has been developed where particulate matter (PM) collected on glass fiber filters was exposed to human epithelial (lung) cells. Carbonaceous (soot) PM included tire, wood, diesel, candle, and variously combusted natural gas PM from a kitchen stove range. Black carbon PM and a commercial multiwall carbon nanotube aggregate PM was also examined in vitro as surrogate materials, and all experimental PM was characterized by field emission scanning electron microscopy and transmission electron microscopy. Assay results for 48 h cultures showed toxicity for all carbonaceous PM with various natural gas PM being the most toxic; this was comparable to the toxicity induced by the surrogate PM. Light microscopy examination of affected epithelial cells confirmed the semi-quantitative results. Comparison of polycyclic aromatic hydrocarbon (PAH) content and concentration for the carbonaceous PM showed no PAH correlation with relative cell viability (cell death) after 48 h.

  4. Waveguide Plasmon Resonance of Arrayed Metallic Nanostructures Patterned on a Soft Substrate by Direct Contact Printing Lithography.

    PubMed

    Su, Wei-Xiang; Wu, Chun-Ying; Lee, Yung-Chun

    2017-08-13

    This paper presents a direct contact printing method to obtain arrayed metallic nanostructures on a soft polymer substrate. It utilizes a polydimethylsiloxane (PDMS) mold replicated from silicon molds to transfer metallic nanopatterns onto a polymer substrate based on differences in interfacial bonding energy. Arrayed metallic nanodisks with a disk diameter down to 180 nm and a center-to-center pitch around 400 nm are experimentally patterned on a PET substrate. The patterned metallic nanostructures are then spin-coated with a polymer layer; which mechanically secures the patterned nanostructures and optically allows waveguide plasmon resonance being excited by incident EM waves. Both experimental works and theoretical modeling are given to illustrate the behaviors of different types of plasmon resonance. These arrayed metallic nanostructures patterned on a soft polymer substrate and their tunable optical characteristics open up many possibilities in future engineering applications.

  5. The myth of the boiling point.

    PubMed

    Chang, Hasok

    2008-01-01

    Around 1800, many reputable scientists reported significant variations in the temperature of pure water boiling under normal atmospheric pressure. The reported variations included a difference of over 1 degree C between boiling in metallic and glass vessels (Gay-Lussac), and "superheating" up to 112 degrees C on extracting dissolved air out of water (De Luc). I have confirmed most of these observations in my own experiments, many of which are described in this paper. Water boils at the "boiling point" only under very particular circumstances. Our common-sense intuition about the fixedness of the boiling point is only sustained by our limited experience.

  6. Characterization of toxicants in urban road dust by Toxicity Identification Evaluation using ostracod Heterocypris incongruens direct contact test.

    PubMed

    Khanal, Rajendra; Furumai, Hiroaki; Nakajima, Fumiyuki

    2015-10-15

    The current study involves characterization of organic compounds, heavy metals, and ammonia as potential toxicants in one arterial road (St. 3) and two highway (St. 7 and 8) urban road dust (URD) collected in Tokyo, Japan. URD toxicity was evaluated by Toxicity Identification Evaluation using the ostracod Heterocypris incongruens direct contact test. URDs were treated with resins (10% XAD-4, 20% SIR-300 and 20% SIR-600) to determine the reduction in mortality after treatment. The mortality of ostracods exposed to St. 3 URD (baseline 80%) was significantly (p<0.05) reduced to 0% and 47% after XAD-4 and SIR-300 treatment respectively. This reduction led us to suspect hydrophobic organic compounds and heavy metals as potential toxicants. Subsequent elution of the recovered XAD-4 with polar (methanol, acetone) and non-polar (dichloromethane) solvents confirmed the dominance of relatively polar hydrophobic organic toxicants. The dissolved concentration of Cu and Zn after SIR-300 treatment exceeded the 50% lethal concentration (LC50) for ostracods, which led us to suspect Cu and Zn as other probable toxicants. The concentration of Zn in a SIR-300 acidic elutriate, recovered after the termination of toxicity test, confirmed Zn as one of the toxicants in St. 3. The baseline mortality (100%) of St. 7 was significantly reduced (23%) by SIR-300 treatment. This indicated the presence of heavy metals as the probable toxicant. However, the concentration of dissolved heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the overlying water was below previously reported LC50 values for each metal in St. 7. Recovery of Zn concentrations exceeding the LC50 in the St. 7 SIR-300 elutriate led us to suspect a dietary exposure route of Zn to the ostracod during the direct contact test. The overall results indicate that the toxicant types can vary widely depending on the road sampled.

  7. No previous isolation of female goats is required for novel males to induce a male effect, especially if direct physical contact is established.

    PubMed

    Gallego-Calvo, L; Gatica, M C; Celi, I; Guzmán, J L; Delgadillo, J A; Zarazaga, L A

    2014-12-01

    Goat does supposedly need to be separated from bucks before male stimuli can induce reproductive activity, ovulation, and estrous. The present study examined the reproductive response (ovulation and estrous) of does to "novel" bucks in direct contact with them and when separated from them by a fence. One hundred fourteen does were distributed into three groups: (1) ISOL group (N = 31): females that had been completely isolated from males for 46 days, and thereafter placed in direct contact with "novel" males during the breeding period; (2) NOTISOL-CONTACT group (N = 29): females that had been in contact with "familiar" vasectomized males for 46 days and thereafter placed in direct contact with novel males during the breeding period; (3) NOTISOL-NO CONTACT group (N = 54): females that were in contact with familiar vasectomized males for 46 days and thereafter introduced to novel males, but separated by a fence, during the breeding period. All the males were treated with melatonin to ensure that they were sexually active. Estrous activity was recorded daily by direct visual observation of the marks left by marking harnesses worn by the males. Ovulation was confirmed via the plasma progesterone concentration (measured in weekly blood samples). The ovulation rate was assessed by transrectal ultrasonography. Fecundity, fertility, prolificacy, and productivity were also determined for the ISOL and NOTISOL-CONTACT groups (naturally, in the NOTISOL-NO CONTACT group, no pregnancies were possible). The introduction of novel males induced the same ovarian response in each group (P > 0.05), but the percentage of females that showed estrous and ovulation was lower in the NOTISOL-NO CONTACT group (P < 0.05). No differences were seen between the ISOL and NOTISOL-CONTACT groups (P > 0.05) in terms of fecundity, fertility, prolificacy, and productivity. These results show that the introduction of novel males to females already in contact with familiar males induces ovarian activity

  8. Radial basis functions in mathematical modelling of flow boiling in minichannels

    NASA Astrophysics Data System (ADS)

    Hożejowska, Sylwia; Hożejowski, Leszek; Piasecka, Magdalena

    The paper addresses heat transfer processes in flow boiling in a vertical minichannel of 1.7 mm depth with a smooth heated surface contacting fluid. The heated element for FC-72 flowing in a minichannel was a 0.45 mm thick plate made of Haynes-230 alloy. An infrared camera positioned opposite the central, axially symmetric part of the channel measured the plate temperature. K-type thermocouples and pressure converters were installed at the inlet and outlet of the minichannel. In the study radial basis functions were used to solve a problem concerning heat transfer in a heated plate supplied with the controlled direct current. According to the model assumptions, the problem is treated as twodimensional and governed by the Poisson equation. The aim of the study lies in determining the temperature field and the heat transfer coefficient. The results were verified by comparing them with those obtained by the Trefftz method.

  9. Human ADA3 regulates RARα transcriptional activity through direct contact between LxxLL motifs and the receptor coactivator pocket

    PubMed Central

    Li, Chia-Wei; Ai, Ni; Dinh, Gia Khanh; Welsh, William J.; Chen, J. Don

    2010-01-01

    The alternation/deficiency in activation-3 (ADA3) is an essential component of the human p300/CBP-associated factor (PCAF) and yeast Spt-Ada-Gcn5-acetyltransferase (SAGA) histone acetyltransferase complexes. These complexes facilitate transactivation of target genes by association with transcription factors and modification of local chromatin structure. It is known that the yeast ADA3 is required for nuclear receptor (NR)-mediated transactivation in yeast cells; however, the role of mammalian ADA3 in NR signaling remains elusive. In this study, we have investigated how the human (h) ADA3 regulates retinoic acid receptor (RAR) α-mediated transactivation. We show that hADA3 interacts directly with RARα in a hormone-dependent manner and this interaction contributes to RARα transactivation. Intriguingly, this interaction involves classical LxxLL motifs in hADA3, as demonstrated by both ‘loss’ and ‘gain’ of function mutations, as well as a functional coactivator pocket of the receptor. Additionally, we show that hADA3 associates with RARα target gene promoter in a hormone-dependent manner and ADA3 knockdown impairs RARβ2 expression. Furthermore, a structural model was established to illustrate an interaction network within the ADA3/RARα complex. These results suggest that hADA3 is a bona fide transcriptional coactivator for RARα, acting through a conserved mechanism involving direct contacts between NR boxes and the receptor’s co-activator pocket. PMID:20413580

  10. Solid-contact potentiometric aptasensor based on aptamer functionalized carbon nanotubes for the direct determination of proteins.

    PubMed

    Düzgün, Ali; Maroto, Alicia; Mairal, Teresa; O'Sullivan, Ciara; Rius, F Xavier

    2010-05-01

    A facile, solid-contact selective potentiometric aptasensor exploiting a network of single-walled carbon nanotubes (SWCNT) acting as a transducing element is described in this work. The molecular properties of the SWCNT surface have been modified by covalently linking aptamers as biorecognition elements to the carboxylic groups of the SWCNT walls. As a model system to demonstrate the generic application of the approach, a 15-mer thrombin aptamer interacts with thrombin and the affinity interaction gives rise to a direct potentiometric signal that can be easily recorded within 15 s. The dynamic linear range, with a sensitivity of 8.0 mV/log a(Thr) corresponds to the 10(-7)-10(-6) M range of thrombin concentrations, with a limit of detection of 80 nM. The aptasensor displays selectivity against elastase and bovine serum albumin and is easily regenerated by immersion in 2 M NaCl. The aptasensor demonstrates the capacity of direct detection of the recognition event avoiding the use of labels, mediators, or the addition of further reagents or analyte accumulation.

  11. Helicobacter pylori dwelling on the apical surface of gastrointestinal epithelium damages the mucosal barrier through direct contact.

    PubMed

    Zhang, Chen; Zhang, Hongyu; Yu, Lu; Cao, Yi

    2014-10-01

    Epithelial junctions and mucins compose a major portion of the mucosal barrier. Helicobacter pylori (H. pylori) infections induce alterations of the tight junctions and adherens junctions in epithelial cells, although the precise mechanisms underlying this process are not fully understood. The expression of adhesion molecules and MUC1 was systematically investigated in gastrointestinal epithelial cells infected with H. pylori in vitro and in vivo. Furthermore, we developed several new in vitro methods to study the relationships between the bacterium and the dysfunction of tight junctions using Boyden Chambers. The expression of a series of junctional molecules and MUC1 decreased in the cultured cells that were infected with H. pylori. According to the degree of damage at the tight junctions, direct contact of H. pylori with the apical membrane of the cells resulted in the greatest increase in permeability compared to basal membrane binding or non-binding of H. pylori to the cells. Similarly, we noted that H. pylori infection could reduce the expression and glycosylation of MUC1. Helicobacter pylori dwelling on the apical surface of the gastrointestinal epithelium could directly induce serious injury of the mucosal barrier, and the new methods outlined here, based on the Boyden Chamber system, could be very useful for studying the relationships between bacteria and their target cells. © 2014 John Wiley & Sons Ltd.

  12. Bone-to-implant contact around immediately loaded direct laser metal-forming transitional implants in human posterior maxilla.

    PubMed

    Shibli, Jamil A; Mangano, Carlo; Mangano, Francesco; Rodrigues, José A; Cassoni, Alessandra; Bechara, Karen; Ferreia, Jose Divino B; Dottore, Alexandre M; Iezzi, Giovanna; Piattelli, Adriano

    2013-06-01

    Direct laser metal forming (DLMF) is a procedure in which a high-power laser beam is directed onto a metal powder bed and programmed to fuse particles according to a computer-aided design file, generating a thin metal layer. This histologic study evaluated the bone-to-implant contact (BIC%) around immediately loaded DLMF transitional implants retrieved after 2 months from posterior human maxillae. Twelve totally edentulous individuals (mean age, 66.14 ± 2.11 years) received DLMF transitional implants divided in twelve immediately loaded (IL) and twelve unloaded (UI) implants. These transitional implants were placed between conventional implants to support the interim complete maxillary denture during the healing period. After 8 weeks, the transitional implants and the surrounding tissue were removed and prepared for histomorphometric analysis. Mature woven preexisting bone lined by newly formed bone in early stages of maturation were found around all retrieved implants. Histometric evaluation indicated that the mean BIC% was 45.20 ± 7.68% and 34.10 ± 7.85% for IL and UI, respectively (P <0.05). The present data obtained in humans showed that, although both IL and UI presented good BIC%, IL DLMF implants had a higher BIC% in the posterior maxilla.

  13. The pathogenesis of highly virulent African Swine Fever virus in domestic pigs exposed via intraoropharyngeal, intranasopharyngeal, and intramuscular inoculation, and by direct contact with infected pigs

    USDA-ARS?s Scientific Manuscript database

    In order to optimize novel systems for African Swine Fever Virus (ASFV) vaccine development, domestic pigs were challenged with the highly virulent ASFV-Malawi strain via intraoropharyngeal (IOP), intranasopharyngeal (INP), intramuscular (IM), and direct contact (DC) routes. Direct challenge doses ...

  14. Direct contact between sympathetic neurons and rat cardiac myocytes in vitro increases expression of functional calcium channels.

    PubMed Central

    Ogawa, S; Barnett, J V; Sen, L; Galper, J B; Smith, T W; Marsh, J D

    1992-01-01

    To test the hypothesis that direct contact between sympathetic neurons and myocytes regulates expression and function of cardiac Ca channels, we prepared cultures of neonatal rat ventricular myocytes with and without sympathetic ganglia. Contractile properties of myocytes were assessed by an optical-video system. Contractility-pCa curves showed a 60% greater increase in contractility for innervated myocytes compared with control cells at 6.3 mM [Ca]0 (n = 8, P less than 0.05). Cells grown in medium conditioned by growth of ganglia and myocytes were indistinguishable physiologically from control cells. [Bay K 8644]-contractility curves revealed a 60 +/- 10% enhancement of the contractility response at 10(-6) M for innervated cells compared with control cells. The increased response to Bay K 8644 was not blocked by alpha- or beta-adrenergic antagonists. Moreover, increased efficacy of Bay K 8644 was maintained for at least 24 h after denervation produced by removal of ganglia from the culture. Dihydropyridine binding sites were assessed with the L channel-specific radioligand 3[H]PN200-110. PN200-110 binding sites were increased by innervation (51 +/- 5 to 108 +/- 20 fmol/mg protein, P less than 0.01), with no change in KD. Peak current-voltage curves were determined by whole-cell voltage clamp techniques for myocytes contacted by a neuron, control myocytes, and myocytes grown in conditioned medium. Current density of L-type Ca channels was significantly higher in innervated myocytes (10.5 +/- 0.4 pA/pF, n = 5) than in control myocytes (5.9 +/- 0.3 pA/pF, n = 8, P less than 0.01) or myocytes grown in conditioned medium (6.2 +/- 0.2 pA/pF, n = 10, P less than 0.01). Thus, physical contact between a sympathetic neuron and previously uninnervated neonatal rat ventricular myocytes increases expression of functional L-type calcium channels as judged by contractile responses to Ca0 and Bay K 8644, as well as by electrophysiological and radioligand binding properties

  15. The Boiling eXperiment Facility (BXF) for the Microgravity Science Glovebox (MSG)

    NASA Technical Reports Server (NTRS)

    McQuillen, John; Chao, David; Vergilii, Frank

    2006-01-01

    Boiling is an effective means of cooling by removing heat from surfaces through vaporization of a working fluid. It is also affected by both the magnitude and direction of gravity. By conducting pool boiling tests in microgravity, the effect of buoyancy n the overall boiling process and the relative magnitude of other phenomena can be assessed. The Boiling eXperiment Facility (BXF) is being built for the Microgravity Science Glovebox. This facility will conduct two pool boiling studies. The first study the Microheater Array Boiling Experiment (MABE) uses two 96 element microheater arrays, 2.7 mm and 7.0 mm in size, to measure localized hear fluxes while operating at a constant temperature. The other experiment, the Nucleate Pool Boiling eXperiment (NPBX) uses a 85 mm diameter heater wafer that has been "seeded" with five individually-controlled nucleation sites to study bubble nucleation, growth, coalescence and departure. The BXF uses normal-perfluorohexane as the test fluid and will operate between pressures of 60 to 244 Pa. and temperatures of 35 to 60 C. Both sets of experimental heaters are highly instrumented. Pressure and bulk fluid temperature measurements will be made with standard rate video. A high speed video system will be used to visualize the boiling process through the bottom of the MABE heater arrays. The BXF is currently scheduled to fly on Utilization Flight-13A.1 to the ISS with facility integration into the MSG and operation during Increment 15

  16. EHD enhancement of nucleate boiling. [Electrohydrodynamic

    SciTech Connect

    Cooper, P. )

    1990-05-01

    This paper describes: (a) an experimental investigation into the effect of an electric field applied to pool boiling of Freon (R114) on a finned tube and (b) a theoretical model of electrically enhanced nucleate boiling applicable to simple surfaces only. Experimental results have shown electrohydrodynamic (EHD) enhancement of heat transfer to be manifest in two ways: (1) elimination of boiling hysteresis, (2) augmentation of nulceate boiling heat transfer coefficients by up to an order of magnitude. These effects were also observed in electrically enhanced boiling of Freon/oil mixtures. A new analytical model is described whereby EHD nucleate boiling data from previous studies (employing simple apparatus comprising heated wires with concentric cylinder electrodes) have been correlated for the first time using the concept of an electrical influence number. This dimensionless parameter is based upon the relationship between applied electric field intensity and changes in bubble departure diameter at a heat transfer surface.

  17. Direct release of the allergen tulipalin A from Alstroemeria cut flowers: a possible source of airborne contact dermatitis?

    PubMed

    Christensen, L P

    1999-12-01

    The allergen tulipalin A was collected by dynamic headspace technique from cut flowers of 2 Alstroemeria hybrids and quantified and identified by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The amounts of tulipalin A released into the air were correlated with the tulipalin A and the total allergen content (tulipalin A and tuliposides) in the plant tissue, respectively. Tulipalin A was released primarily from the wounded areas, i.e. the stems, although small amounts were also emitted from the undamaged flowers in one of the hybrids. The tulipalin A concentrations in the stems of the Alstroemeria hybrids investigated were 0.06% and 0.13% of fresh weight, respectively, and the amounts directly released from the cut flowers were 0.4 and 2.2 microg (cut flower)(-1) h(-1), respectively. The content of tulipalin A exceeded that of tuliposides in leaves and flowers of both hybrids, whereas the content of tulipalin A in stems (in % fresh weight) was slightly lower than the content of tuliposides. The possibility that airborne tulipalin A from Alstroemeria could be a source of airborne contact dermatitis is discussed.

  18. Preliminary report on the baseline thermal and hydraulic performance tests of a sieve tray direct contact heat exchanger

    SciTech Connect

    Mines, G.L.

    1982-11-01

    A sieve tray direct contact heat exchanger was designed, built and then tested in a binary power cycle at the Raft River geothermal test site. A series of baseline thermal and hydraulic tests were conducted with an isobutane working fluid. The evaluation of these tests is reported. The testing of the DCHX confirmed that the repeated forming and coalescence of the working fluid drops in the sieve tray column produce excellent heat transfer performance. Tray thermal efficiencies were at or above the design value of 70% and the pinch points were well under the design goal of 1/sup 0/F (too small to be measured with installed instrumentation). From a hydraulic standpoint, the column operated at the working fluid velocities from the plate holes corresponding to the predicted condition of maximum total drop surface area (or minimum drop size) when the unit was operating near the flooding limits, or throughputs. This is the recommended working fluid hole velocity for use in designing sieve tray columns. The geothermal flow limits encountered (at flooding) corresponded roughly to the thermal rise velocity of a 1/32-inch drop. This is a drop size commonly used for specifying the terminal velocity (or continuous fluid velocity) in the design of columns for mass transfer applications.

  19. Direct electrical contact of slanted ITO film on axial p-n junction silicon nanowire solar cells.

    PubMed

    Lee, Ya-Ju; Yao, Yung-Chi; Yang, Chia-Hao

    2013-01-14

    A novel scheme of direct electrical contact on vertically aligned silicon nanowire (SiNW) axial p-n junction is demonstrated by means of oblique-angle deposition of slanted indium-tin-oxide (ITO) film for photovoltaic applications. The slanted ITO film exhibits an acceptable resistivity of 1.07 x 10⁻³Ω-cm underwent RTA treatment of T = 450°C, and the doping concentration and carrier mobility by Hall measurement amount to 3.7 x 10²⁰ cm⁻³ and 15.8 cm²/V-s, respectively, with an n-type doping polarity. Because of the shadowing effect provided by the SiNWs, the incident ITO vapor-flow is deposited preferentially on the top of SiNWs, which coalesces and eventually forms a nearly continuous film for the subsequent fabrication of grid electrode. Under AM 1.5 G normal illumination, our axial p-n junction SiNW solar cell exhibits an open circuit voltage of VOC = 0.56 V, and a short circuit current of JSC = 1.54 mA/cm² with a fill factor of FF = 30%, resulting in a total power conversion efficiency of PEC = 0.26%.

  20. In vitro biocompatibility of degradable biopolymers in cell line cultures from various ocular tissues: direct contact studies.

    PubMed

    Huhtala, A; Pohjonen, T; Salminen, L; Salminen, A; Kaarniranta, K; Uusitalo, H

    2007-11-01

    Synthetic biodegradable polymers have many potential therapeutic applications. In ophthalmology, biodegradable polymers have been used as viscoelastic agents and surgical implants. Other potential applications include controlled release of drugs and growth factors, gene therapy, and tissue engineering. In the present study, in vitro biocompatibility of three biodegradable polymers, 50:50 PDLGA, 85:15 PDLGA, and Inion GTR membrane was evaluated in comparison to tissue culture polystyrene by investigating cell proliferation and potential acute toxicity by the WST-1 cytotoxicity/cell proliferation test, the ATP test, and the lactate dehydrogenase (LDH) test. Evaluations were conducted with cell line cultures from various ocular tissues, human corneal epithelial cells (HCE), rabbit stromal fibroblasts (SIRC), bovine corneal endothelial cells (BCE), human conjunctival epithelial cells (IOBA-NHC), and human retinal pigment epithelial cells (ARPE-19) by direct contact studies by plating the cells on the polymer film specimens in 96-wells. The proliferation results show that cell lines from various ocular tissues attached and grew on PDLGA 50:50, PDLGA 85:15, and Inion GTR membrane. Cytotoxicity experiments with the LDH and ATP tests showed no or extremely slight toxic adverse effects. These polymers have potential to be used as scaffolds in cell transplantation devices or as surgical implants. Copyright (c) 2007 Wiley Periodicals, Inc.

  1. Numerical Modeling of Frictional Stress in the Contact Zone of Direct Extrusion of Aluminum Alloys under Starved Lubrication

    NASA Astrophysics Data System (ADS)

    Tomar, P.; Pandey, R. K.; Nath, Y.

    2013-11-01

    The objective of this article is to investigate numerically frictional stress in the contact zone at the die/billet interface in the direct extrusion of aluminum alloys considering starved lubricated conditions. In the modeling, both the inlet and work zones have been investigated by coupled solution of the governing equations. The influences of the billet material's strain hardening and its heating due to the plastic deformation are accounted for in the numerical computation. The frictional shear stress at the die/billet interface is computed using three different lubricating oils. Numerical results have been presented herein for the various operating parameters viz. starvation factor ( ψ = 0.2-0.6), lubricants' viscosities ( η 0 = 0.05 Pa s-0.2 Pa s), semi die angle ( β = 10°-20°), and material parameter ( G = 0.56-2.25). It has been observed that the frictional stress increases with an increase in the severity of the lubricant's starvation for the given values of semi-die angle, extrusion speed, and material parameter.

  2. Computer simulation of noncondensible gas behavior in geothermal power plants utilizing direct contact heat exchange. Report of work, February 1, 1980-February 28, 1981

    SciTech Connect

    Perona, J.J.

    1981-01-01

    A computer model was developed to simulate the behavior of carbon dioxide and hydrogen sulfide in a geothermal power plant using direct contact heat exchange with isobutane as a working fluid. This computer program was modified to simulate the particular equipment characteristics of the 500 kW direct contact pilot plant at East Mesa. Vapor and liquid compositions and temperatures can be calculated throughout the heat exchangers in the pilot plant. The program is now available for analysis of the pilot plant operation and for design of similar plants.

  3. Boiling significantly promotes photodegradation of perfluorooctane sulfonate.

    PubMed

    Lyu, Xian-Jin; Li, Wen-Wei; Lam, Paul K S; Yu, Han-Qing

    2015-11-01

    The application of photochemical processes for perfluorooctane sulfonate (PFOS) degradation has been limited by a low treatment efficiency. This study reports a significant acceleration of PFOS photodegradation under boiling condition compared with the non-boiling control. The PFOS decomposition rate increased with the increasing boiling intensity, but declined at a higher hydronium level or under oxygenation. These results suggest that the boiling state of solution resulted in higher effective concentrations of reactants at the gas-liquid interface and enhanced the interfacial mass transfer, thereby accelerating the PFOS decomposition. This study broadens our knowledge of PFOS photodegradation process and may have implications for development of efficient photodegradation technologies.

  4. CHIMNEY FOR BOILING WATER REACTOR

    DOEpatents

    Petrick, M.

    1961-08-01

    A boiling-water reactor is described which has vertical fuel-containing channels for forming steam from water. Risers above the channels increase the head of water radially outward, whereby water is moved upward through the channels with greater force. The risers are concentric and the radial width of the space between them is somewhat small. There is a relatively low rate of flow of water up through the radially outer fuel-containing channels, with which the space between the risers is in communication. (AE C)

  5. The colony environment, but not direct contact with conspecifics, influences the development of circadian rhythms in honey bees.

    PubMed

    Eban-Rothschild, Ada; Shemesh, Yair; Bloch, Guy

    2012-06-01

    Honey bee (Apis mellifera) workers emerge from the pupae with no circadian rhythms in behavior or brain clock gene expression but show strong rhythms later in life. This postembryonic development of circadian rhythms is reminiscent of that of infants of humans and other primates but contrasts with most insects, which typically emerge from the pupae with strong circadian rhythms. Very little is known about the internal and external factors regulating the ontogeny of circadian rhythms in bees or in other animals. We tested the hypothesis that the environment during early life influences the later expression of circadian rhythms in locomotor activity in young honey bees. We reared newly emerged bees in various social environments, transferred them to individual cages in constant laboratory conditions, and monitored their locomotor activity. We found that the percentage of rhythmic individuals among bees that experienced the colony environment for their first 48 h of adult life was similar to that of older sister foragers, but their rhythms were weaker. Sister bees isolated individually in the laboratory for the same period were significantly less likely to show circadian rhythms in locomotor activity. Bees experiencing the colony environment for only 24 h, or staying for 48 h with 30 same-age sister bees in the laboratory, were similar to bees individually isolated in the laboratory. By contrast, bees that were caged individually or in groups in single- or double-mesh enclosures inside a field colony were as likely to exhibit circadian rhythms as their sisters that were freely moving in the same colony. These findings suggest that the development of the circadian system in young adult honey bees is faster in the colony than in isolation. Direct contact with the queen, workers, or the brood, contact pheromones, and trophallaxis, which are all important means of communication in honey bees, cannot account for the influence of the colony environment, since they were all

  6. Boiling on fins with wire screen of variable effective conductivity

    NASA Astrophysics Data System (ADS)

    Orzechowski, Tadeusz

    The high scale of integration of modern equipment used for medical, military and other purposes puts heavy demands as regards the removal of great heat fluxes. This can be achieved only in exchangers that apply the phase change phenomena. Among many methods to improve boiling heat transfer, the wire mesh covering demonstrates some advantages due to the possibilities of designing the desired microstructure parameters, availability on the market, and low cost. The wire mesh microstucture with specified geometrical parameters produces anisotropy in conductivity. The different arrangement of the mesh layers relative to the direction of the heat flux is a cause of the change of temperature distribution within the layer. The consequence is a respective change in the discharge conditions of the gas phase and liquid feed. The experiments were conducted on fins covered with a single layer of copper mesh with lumen of 38 % and boiling FC-72 at ambient pressure. Compared with the smooth surface, the wire mesh structures yield an increase in the heat transfer rate at boiling. It is also shown that nucleate boiling is initiated at lower wall superheat. Formulas for longitudinal and perpendicular thermal conductivity are given for different mesh structure arrangements.

  7. Boiling on fins with wire screen of variable effective conductivity

    NASA Astrophysics Data System (ADS)

    Orzechowski, Tadeusz

    2016-11-01

    The high scale of integration of modern equipment used for medical, military and other purposes puts heavy demands as regards the removal of great heat fluxes. This can be achieved only in exchangers that apply the phase change phenomena. Among many methods to improve boiling heat transfer, the wire mesh covering demonstrates some advantages due to the possibilities of designing the desired microstructure parameters, availability on the market, and low cost. The wire mesh microstucture with specified geometrical parameters produces anisotropy in conductivity. The different arrangement of the mesh layers relative to the direction of the heat flux is a cause of the change of temperature distribution within the layer. The consequence is a respective change in the discharge conditions of the gas phase and liquid feed. The experiments were conducted on fins covered with a single layer of copper mesh with lumen of 38 % and boiling FC-72 at ambient pressure. Compared with the smooth surface, the wire mesh structures yield an increase in the heat transfer rate at boiling. It is also shown that nucleate boiling is initiated at lower wall superheat. Formulas for longitudinal and perpendicular thermal conductivity are given for different mesh structure arrangements.

  8. The relative importance of frequency of contacts and duration of exposure for the spread of directly transmitted infections.

    PubMed

    De Cao, Elisabetta; Zagheni, Emilio; Manfredi, Piero; Melegaro, Alessia

    2014-07-01

    The recent availability of survey data on social contact patterns has made possible important advances in the understanding of the social determinants of the spread of close-contact infections, and of the importance of long-lasting contacts for effective transmission to occur. Still, little is known about the relationship between two of the most critical identified factors (frequency of contacts and duration of exposure) and how this relationship applies to different types of infections. By integrating data from two independently collected social surveys (Polymod and time use), we propose a model that combines these two transmission determinants into a new epidemiologically relevant measure of contacts: the number of "suitable" contacts, which is the number of contacts that involve a sufficiently long exposure time to allow for transmission. The validity of this new epidemiological measure is tested against Italian serological data for varicella and parvovirus-B19, with uncertainty evaluated using the Bayesian melding technique. The model performs quite well, indicating that the interplay between time of exposure and contacts is critical for varicella transmission, while for B19 it is the duration of exposure that matters for transmission. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  9. Can multiple flow boiling regimes be reduced into a single one in microchannels?

    NASA Astrophysics Data System (ADS)

    Yang, Fanghao; Dai, Xianming; Peles, Yoav; Cheng, Ping; Li, Chen

    2013-07-01

    We report that multiple and transitional flow boiling regimes in microchannels can be reduced into a single annular flow from the onset of nucleate boiling to the critical heat flux condition. Hydrophilic silicon nanowires directly grown on inner walls of microchannels were tailored to create boiling surfaces with optimal submicron pores surrounded by nanogaps through controlling the height and density of silicon nanowires using the nanocarpet effect. A single two-phase regime can be realized by controlling the flow structure in two aspects: reducing bubble size and transforming the dominant surface tension force from the cross-sectional plane to the inner-wall plane.

  10. QSPR using MOLGEN-QSPR: the challenge of fluoroalkane boiling points.

    PubMed

    Rücker, Christoph; Meringer, Markus; Kerber, Adalbert

    2005-01-01

    By means of the new software MOLGEN-QSPR, a multilinear regression model for the boiling points of lower fluoroalkanes is established. The model is based exclusively on simple descriptors derived directly from molecular structure and nevertheless describes a broader set of data more precisely than previous attempts that used either more demanding (quantum chemical) descriptors or more demanding (nonlinear) statistical methods such as neural networks. The model's internal consistency was confirmed by leave-one-out cross-validation. The model was used to predict all unknown boiling points of fluorobutanes, and the quality of predictions was estimated by means of comparison with boiling point predictions for fluoropentanes.

  11. Field test of two high-pressure direct-contact downhole steam generators. Volume II. Oxygen/diesel system

    SciTech Connect

    Moreno, J.B.

    1983-07-01

    A field test of an oxygen/diesel fuel, direct contact steam generator has been completed. The field test, which was a part of Project DEEP STEAM and was sponsored by the US Department of Energy, involved the thermal stimulation of a well pattern in the Tar Zone of the Wilmington Oil Field. The activity was carried out in cooperation with the City of Long Beach and the Long Beach Oil Development Company. The steam generator was operated at ground level, with the steam and combustion products delivered to the reservoir through 2022 feet of calcium-silicate insulated tubing. The objectives of the test included demonstrations of safety, operational ease, reliability and lifetime; investigations of reservoir response, environmental impact, and economics; and comparison of those points with a second generator that used air rather than oxygen. The test was extensively instrumented to provide the required data. Excluding interruptions not attributable to the oxygen/diesel system, steam was injected 78% of the time. System lifetime was limited by the combustor, which required some parts replacement every 2 to 3 weeks. For the conditions of this particular test, the use of trucked-in LOX resulted in liess expense than did the production of the equivalent amount of high pressure air using on site compressors. No statistically significant production change in the eight-acre oxygen system well pattern occurred during the test, nor were any adverse effects on the reservoir character detected. Gas analyses during the field test showed very low levels of SOX (less than or equal to 1 ppM) in the generator gaseous effluent. The SOX and NOX data did not permit any conclusion to be drawn regarding reservoir scrubbing. Appreciable levels of CO (less than or equal to 5%) were measured at the generator, and in this case produced-gas analyses showed evidence of significant gas scrubbing. 64 figures, 10 tables.

  12. Effect of Virtual Reality Exposure and Aural Stimuli on Eye Contact, Directional Focus, and Focus of Attention of Novice Wind Band Conductors

    ERIC Educational Resources Information Center

    Orman, Evelyn K.

    2016-01-01

    This study examined the effects of virtual reality immersion with audio on eye contact, directional focus and focus of attention for novice wind band conductors. Participants (N = 34) included a control group (n = 12) and two virtual reality groups with (n = 10) and without (n = 12) head tracking. Participants completed conducting/score study…

  13. Effect of Virtual Reality Exposure and Aural Stimuli on Eye Contact, Directional Focus, and Focus of Attention of Novice Wind Band Conductors

    ERIC Educational Resources Information Center

    Orman, Evelyn K.

    2016-01-01

    This study examined the effects of virtual reality immersion with audio on eye contact, directional focus and focus of attention for novice wind band conductors. Participants (N = 34) included a control group (n = 12) and two virtual reality groups with (n = 10) and without (n = 12) head tracking. Participants completed conducting/score study…

  14. Forced-convective boiling in small diameter tube

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yoshiro; Kuriyma, Yoshio; Furukawa, Masao

    1988-03-01

    A straight bare tube type evaporator was tested in order to evaluate its feasibility on space applications. Two categories of flow regimes were observed during the test. One flow regime indicated a high pressure loss and a slight temperature decrease along the flow direction, and the test results showed a fairly good agreement with the analytical results obtained using a nucleat boiling model. Whereas, the other flow regime showed a contrasting feature of low pressure loss and abrupt temperature rise along the flow direction. In this case also the results obtained on the basis of the analytical model of film boiling showed a fairly good agreement with the experimental results of heat transfer characteristics.

  15. Pool boiling inversion through bubble induced macroconvection

    NASA Astrophysics Data System (ADS)

    Jaikumar, A.; Kandlikar, S. G.

    2017-02-01

    While numerous surface geometries have been explored to achieve enhancements in pool boiling critical heat flux and heat transfer coefficient (HTC), their mechanistic contributions towards the characteristics of the pool boiling curve are not clear. Recently reported pool boiling curves in literature have shown a trend where an increase in heat flux leads to a decrease in wall superheat. Consequently, a negative slope in the pool boiling curve accompanied by a sharp increase in HTC, termed here as boiling inversion, is observed. We demonstrate that this inversion is due to vapor stream induced reinforcement of an impinging liquid jet over the non-boiling regions. This behavior is characteristic of surfaces developed using separate liquid-vapor pathways and macroconvection enhancement mechanism resulting in a highly efficient self-sustained boiling configuration. The increased jet impingement velocities lead to higher HTCs with lower wall superheats. The analytical models available in literature are employed to quantitatively explain this trend. Furthermore, a self-adjusting boiling mechanism is seen at play wherein a reduction in nucleation activity due to lowering of wall superheat counters the increase in HTC induced by the macroconvective currents.

  16. A magnetic field-directed self-assembly solid contact for construction of an all-solid-state polymeric membrane Ca(2+)-selective electrode.

    PubMed

    Yin, Tanji; Jiang, Xiaojing; Qin, Wei

    2017-10-09

    A magnetic field-directed self-assembly solid contact has been proposed for developing an all-solid-state polymeric membrane Ca(2+)-selective electrode. The solid contact is prepared by physically adsorbing magnetic graphene powder on a magnetic gold electrode under the direction of the magnetic field. The proposed method for preparing solid contact avoids using the aqueous solutions and is simple, fast and general as compared to the multilayer drop-casting and electrodeposition methods. The all-solid-state Ca(2+)-selective electrode based on magnetic graphene as solid contact shows a stable potential response in the linear range of 1.0 × 10(-6)-1.0 × 10(-3) M with a slope of 28.2 mV/decade, and the detection limit is about 4.0 × 10(-7) M. Additionally, the magnetic graphene-based electrode shows a comparable potential stability performance to other graphene-based all-solid-state ion-selective electrodes, such as reduced undesirable water layer and insensitive to the interferences of O2, CO2 and light. This work provides a favorable way to prepare solid contact for use in the field of all-solid-state ion-selective electrodes. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Marangoni Effects on Near-Bubble Microscale Transport During Boiling of Binary Fluid Mixtures

    NASA Technical Reports Server (NTRS)

    V. Carey; Sun, C.; Carey, V. P.

    2000-01-01

    regime and the bubble shape is cylindrical in appearance. In some instances, the bubble interface appeared to oscillate. At higher applied heat flux levels, the top of the bubble became larger, apparently to provide more condensing interface area adjacent to the cold plate. Increasing the applied heat flux ultimately led to dry-out of the heated surface, with conditions just prior to dryout corresponding to the maximum heat flux (CHF). A more stable bubble was observed when the system attained the minimum heat flux (for film boiling). In this regime, most of the surface under the bottom of the bubble was dry with nucleate boiling sometimes occuring around the contact perimeter of the bubble at heated surface. Different variations (e.g. gap between two plates, molar concentration of the liquid mixture) of the experiments were examined to determine parametric effects on the boiling process and to determine the best conditions for the KC135 reduced gravity tests. Variation of the gap was found to have a minor impact on the CHF. However, reducing the gap between the hot and cold surface was observed to significantly reduce the minimum heat flux for fixed molar concentration of 2-propanol. In the reduced gravity experiments aboard the KC135 aircraft, the bubble formed in the 6.4 mm gap was generally cylindrical or barrel shaped and it increased its extent laterally as the surface superheat increased. In reduced gravity experiments, dryout of the heated surface under the bubble was observed to occur at a lower superheated temperature than for 1g conditions. Observed features of the boiling process and heat transfer data under reduced gravity will be discussed in detail. The results of the reduced gravity experiments will also be compared to those obtained in comparable 1g experiments. In tandem with the experiments we are also developing a computational model of the transport in the liquid surrounding the bubble during the boiling process. The computational model uses a level

  18. Criticality in the slowed-down boiling crisis at zero gravity.

    PubMed

    Charignon, T; Lloveras, P; Chatain, D; Truskinovsky, L; Vives, E; Beysens, D; Nikolayev, V S

    2015-05-01

    Boiling crisis is a transition between nucleate and film boiling. It occurs at a threshold value of the heat flux from the heater called CHF (critical heat flux). Usually, boiling crisis studies are hindered by the high CHF and short transition duration (below 1 ms). Here we report on experiments in hydrogen near its liquid-vapor critical point, in which the CHF is low and the dynamics slow enough to be resolved. As under such conditions the surface tension is very small, the experiments are carried out in the reduced gravity to preserve the conventional bubble geometry. Weightlessness is created artificially in two-phase hydrogen by compensating gravity with magnetic forces. We were able to reveal the fractal structure of the contour of the percolating cluster of the dry areas at the heater that precedes the boiling crisis. We provide a direct statistical analysis of dry spot areas that confirms the boiling crisis at zero gravity as a scale-free phenomenon. It was observed that, in agreement with theoretical predictions, saturated boiling CHF tends to zero (within the precision of our thermal control system) in zero gravity, which suggests that the boiling crisis may be observed at any heat flux provided the experiment lasts long enough.

  19. Direct Numerical Simulation of the Leidenfrost Effect

    NASA Astrophysics Data System (ADS)

    Tanguy, Sebastien; Rueda Villegas, Lucia; Fluid Mechanics Institute of Toulouse Team

    2015-11-01

    The development of numerical methods for the direct numerical simulation of two-phase flows with phase changes, is the main topic of this study. We propose a novel numerical method which allows dealing with both evaporation and boiling at the interface between a liquid and a gas. For instance it can occur for a Leidenfrost droplet; a water drop levitating above a hot plate which temperature is much higher than the boiling temperature. In this case, boiling occurs in the film of saturated vapor which is entrapped between the bottom of the drop and the plate, whereas the top of the water droplet evaporates in contact of ambient air. Thus, boiling and evaporation can occur simultaneously on different regions of the same liquid interface or occur successively at different times of the history of an evaporating droplet. Usual numerical methods are not able to perform computations in these transient regimes, therefore, we propose in this paper a novel numerical method to achieve this challenging task. Finally, we present several accurate validations against experimental results on Leidenfrost Droplets to strengthen the relevance of this new method.

  20. Adaptation of H9N2 AIV in guinea pigs enables efficient transmission by direct contact and inefficient transmission by respiratory droplets.

    PubMed

    Sang, Xiaoyu; Wang, Airong; Ding, Jie; Kong, Huihui; Gao, Xiaolong; Li, Lin; Chai, Tongjie; Li, Yuanguo; Zhang, Kun; Wang, Chengyu; Wan, Zhonghai; Huang, Geng; Wang, Tiecheng; Feng, Na; Zheng, Xuexing; Wang, Hualei; Zhao, Yongkun; Yang, Songtao; Qian, Jun; Hu, Guixue; Gao, Yuwei; Xia, Xianzhu

    2015-11-10

    H9N2 avian influenza viruses circulate worldwide in poultry and have sporadically infected humans, raising concern whether H9N2 viruses have pandemic potential. Here, we use a guinea pig model to examine whether serial passage results in adaptive viral changes that confer a transmissible phenotype to a wild-type H9N2 virus. After nine serial passages of an H9N2 virus through guinea pigs, productive transmission by direct contact occurred in 2/3 guinea pig pairs. The efficiency of transmission by direct contact increased following the fifteenth passage and occurred in 3/3 guinea pig pairs. In contrast, airborne transmission of the passaged virus was less efficient and occurred in 1/6 guinea pig pairs and 0/6 ferret pairs after the fifteenth passage. Three amino acid substitutions, HA1-Q227P, HA2-D46E, and NP-E434K, were sufficient for contact transmission in guinea pigs (2/3 pairs). The two HA amino acid substitutions enhanced receptor binding to α2,3-linked sialic acid receptors. Additionally, the HA2-D46E substitution increased virus thermostability whereas the NP-E434K mutation enhanced viral RNA polymerase activity in vitro. Our findings suggest that adaptive changes that enhance viral receptor binding, thermostability, and replicative capacity in mammalian cells can collectively enhance the transmissibility of H9N2 AIVs by direct contact in the guinea pig model.

  1. Adaptation of H9N2 AIV in guinea pigs enables efficient transmission by direct contact and inefficient transmission by respiratory droplets

    PubMed Central

    Sang, Xiaoyu; Wang, Airong; Ding, Jie; Kong, Huihui; Gao, Xiaolong; Li, Lin; Chai, Tongjie; Li, Yuanguo; Zhang, Kun; Wang, Chengyu; Wan, Zhonghai; Huang, Geng; Wang, Tiecheng; Feng, Na; Zheng, Xuexing; Wang, Hualei; Zhao, Yongkun; Yang, Songtao; Qian, Jun; Hu, Guixue; Gao, Yuwei; Xia, Xianzhu

    2015-01-01

    H9N2 avian influenza viruses circulate worldwide in poultry and have sporadically infected humans, raising concern whether H9N2 viruses have pandemic potential. Here, we use a guinea pig model to examine whether serial passage results in adaptive viral changes that confer a transmissible phenotype to a wild-type H9N2 virus. After nine serial passages of an H9N2 virus through guinea pigs, productive transmission by direct contact occurred in 2/3 guinea pig pairs. The efficiency of transmission by direct contact increased following the fifteenth passage and occurred in 3/3 guinea pig pairs. In contrast, airborne transmission of the passaged virus was less efficient and occurred in 1/6 guinea pig pairs and 0/6 ferret pairs after the fifteenth passage. Three amino acid substitutions, HA1-Q227P, HA2-D46E, and NP-E434K, were sufficient for contact transmission in guinea pigs (2/3 pairs). The two HA amino acid substitutions enhanced receptor binding to α2,3-linked sialic acid receptors. Additionally, the HA2-D46E substitution increased virus thermostability whereas the NP-E434K mutation enhanced viral RNA polymerase activity in vitro. Our findings suggest that adaptive changes that enhance viral receptor binding, thermostability, and replicative capacity in mammalian cells can collectively enhance the transmissibility of H9N2 AIVs by direct contact in the guinea pig model. PMID:26552719

  2. Who is the Usual Suspect? Evidence of a Selection Bias Toward Faces That Make Direct Eye Contact in a Lineup Task.

    PubMed

    Taubert, Jessica; van Golde, Celine; Verstraten, Frans A J

    2017-01-01

    The speed and ease with which we recognize the faces of our friends and family members belies the difficulty we have recognizing less familiar individuals. Nonetheless, overconfidence in our ability to recognize faces has carried over into various aspects of our legal system; for instance, eyewitness identification serves a critical role in criminal proceedings. For this reason, understanding the perceptual and psychological processes that underlie false identification is of the utmost importance. Gaze direction is a salient social signal and direct eye contact, in particular, is thought to capture attention. Here, we tested the hypothesis that differences in gaze direction may influence difficult decisions in a lineup context. In a series of experiments, we show that when a group of faces differed in their gaze direction, the faces that were making eye contact with the participants were more likely to be misidentified. Interestingly, this bias disappeared when the faces are presented with their eyes closed. These findings open a critical conversation between social neuroscience and forensic psychology, and imply that direct eye contact may (wrongly) increase the perceived familiarity of a face.

  3. Who is the Usual Suspect? Evidence of a Selection Bias Toward Faces That Make Direct Eye Contact in a Lineup Task

    PubMed Central

    van Golde, Celine; Verstraten, Frans A. J.

    2017-01-01

    The speed and ease with which we recognize the faces of our friends and family members belies the difficulty we have recognizing less familiar individuals. Nonetheless, overconfidence in our ability to recognize faces has carried over into various aspects of our legal system; for instance, eyewitness identification serves a critical role in criminal proceedings. For this reason, understanding the perceptual and psychological processes that underlie false identification is of the utmost importance. Gaze direction is a salient social signal and direct eye contact, in particular, is thought to capture attention. Here, we tested the hypothesis that differences in gaze direction may influence difficult decisions in a lineup context. In a series of experiments, we show that when a group of faces differed in their gaze direction, the faces that were making eye contact with the participants were more likely to be misidentified. Interestingly, this bias disappeared when the faces are presented with their eyes closed. These findings open a critical conversation between social neuroscience and forensic psychology, and imply that direct eye contact may (wrongly) increase the perceived familiarity of a face. PMID:28203355

  4. Two-phase structure above hot surfaces in jet impingement boiling

    NASA Astrophysics Data System (ADS)

    Bogdanic, L.; Auracher, H.; Ziegler, F.

    2009-05-01

    Jet impingement boiling is very efficient in cooling of hot surfaces as a part of the impinging liquid evaporates. Several studies have been carried out to measure and correlate the heat transfer to impinging jets as a function of global parameters such as jet subcooling, jet velocity, nozzle size and distance to the surface, etc. If physically based mechanistic models are to be developed, studies on the fundamentals of two-phase dynamics near the hot surface are required. In the present study the vapor-liquid structures underneath a subcooled (20 K) planar (1 mm × 9 mm) water jet, impinging the heated plate vertically with a velocity of 0.4 m/s, were analyzed by means of a miniaturized optical probe. It has a tip diameter of app. 1.5 μm and is moved toward the plate by a micrometer device. The temperature controlled experimental technique enabled steady-state experiments in all boiling regimes. The optical probe data provides information about the void fraction, the contact frequencies and the distribution of the vapor and liquid contact times as a function of the distance to the surface. The measured contact frequencies range from 40 Hz at the onset of nucleate boiling to nearly 20,000 Hz at the end of the transition boiling regime. Due to condensation in the subcooled jet vapor disappears at a distance to the surface of app. 1.2 mm in nucleate boiling. This vapor layer becomes smaller with increasing wall superheat. In film boiling a vapor film thickness of 8 ± 2 μm was found.

  5. Direct contact between dendritic cells and bronchial epithelial cells inhibits T cell recall responses towards mite and pollen allergen extracts in vitro.

    PubMed

    Papazian, D; Wagtmann, V R; Hansen, S; Würtzen, P A

    2015-08-01

    Airway epithelial cells (AECs) form a polarized barrier along the respiratory tract. They are the first point of contact with airborne antigens and are able to instruct resident immune cells to mount appropriate immune responses by either soluble or contact-dependent mechanisms. We hypothesize that a healthy, polarized epithelial cell layer inhibits inflammatory responses towards allergens to uphold homeostasis. Using an in-vitro co-culture model of the airway epithelium, where a polarized cell layer of bronchial epithelial cells can interact with dendritic cells (DCs), we have investigated recall T cell responses in allergic patients sensitized to house dust mite, grass and birch pollen. Using allergen extract-loaded DCs to stimulate autologous allergen-specific T cell lines, we show that AEC-imprinted DCs inhibit T cell proliferation significantly of Bet v 1-specific T cell lines as well as decrease interleukin (IL)-5 and IL-13 production, whereas inhibition of Phl p 5-specific T cells varied between different donors. Stimulating autologous CD4(+) T cells from allergic patients with AEC-imprinted DCs also inhibited proliferation significantly and decreased production of both T helper type 1 (Th1) and Th2 cytokines upon rechallenge. The inhibitory effects of AECs' contact with DCs were absent when allergen extract-loaded DCs had been exposed only to AECs supernatants, but present after direct contact with AECs. We conclude that direct contact between DCs and AECs inhibits T cell recall responses towards birch, grass and house dust mite allergens in vitro, suggesting that AECs-DC contact in vivo constitute a key element in mucosal homeostasis in relation to allergic sensitisation.

  6. Effect of direct eye contact in women with PTSD related to interpersonal trauma: Psychophysiological interaction analysis of connectivity of an innate alarm system.

    PubMed

    Steuwe, Carolin; Daniels, Judith K; Frewen, Paul A; Densmore, Maria; Theberge, Jean; Lanius, Ruth A

    2015-05-30

    In healthy individuals, direct eye contact is thought to modulate a cortical route eliciting social cognitive processes via activation of a fast subcortical pathway. This study aimed to examine functional brain connectivity during direct eye contact in women with posttraumatic stress disorder (PTSD) related to childhood abuse as compared with healthy controls. We conducted psychophysiological interaction (PPI) analyses in Statistical Parametric Mapping-8 (SPM8) using the superior colliculus (SC) and locus coeruleus (LC) as seed regions while 16 healthy subjects and 16 patients with a primary diagnosis of PTSD related to childhood maltreatment viewed a functional magnetic resonance imaging (fMRI) paradigm involving direct (D) versus averted (A) gaze (happy, sad, neutral). The PTSD group showed a significantly enhanced connectivity between the SC and the anterior cingulate, and between the LC and the thalamus, caudate, putamen, insula, cingulate gyrus, and amygdala, as compared with healthy individuals. Symptom severity scores on the Clinician-Administered PTSD Scale (CAPS) showed significant positive correlations with superior colliculus connectivity with the perigenual and posterior cingulate, insula, and sublenticular extended amygdala. Functional connectivity data suggest increased recruitment of brain regions involved in emotion processing during direct gaze in PTSD in association with the fast subcortical pathway. The interpretation of eye contact as a signal of threat may require more emotion regulatory capacities in patients with PTSD. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  7. Flow visualization and void fraction measurement in liquid-metal/water direct contact heat exchange by X-ray attenuation technique

    NASA Astrophysics Data System (ADS)

    Liu, Xin

    One concept being considered for steam generation in particular next generation nuclear reactor designs, involves water coming into direct contact with a circulating molten metal. To optimize the design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability. With the development of high performance digital detectors, radiography using X-rays or neutrons maybe a suitable technique to obtain information about that direct-contact interaction; i.e., void volume fractions, length scales and dynamic behavior. Under the basis of previous investigations, a complete methodology of the X-ray radiography for two-phase flow measurement has been developed from the facility and imaging analysis aspects. Through this developed methodology, a high energy X-ray imaging system is optimized for the direct-contact heat exchange experiment. Beside an on-line calibration procedure which practically quantifies the imaging system's performance, the extended linear system theory and Rose's model have also been used to evaluate the imaging system's performance, respectively. The bottleneck of the current imaging system and the future of system improvement direction have been pointed out. With our real-time, large-area high energy X-ray imaging system, the two-phase flow was visualized and stored digitally. An efficient image processing strategy has also been established by combining several optimal digital image processing algorithms. The approach has been implemented into a software computational tool written in MATLAB called T-XIP. Time-dependent heat transfer related variables, such as void fraction (void volume), local heat transfer coefficient, etc., were calculated using this software tool. Finally, an error analysis associated with the void fraction measurement has been given based on two procedures.

  8. Characteristics of Pool Boiling on Graphite-Copper Composite Surfaces

    NASA Technical Reports Server (NTRS)

    Zhang, Nengli; Chao, David F.; Yang, Wen-Jei

    2002-01-01

    significant augmentation in nucleate boiling heat transfer on the composite surfaces. A physical model is developed to describe the phenomenon of bubble departure from the composite surface: The preferred site of bubble nucleation is the fiber tip because of higher tip temperature than the surrounding copper base and poor wettability of the graphite tip compared with that of the base material (copper). The high evaporation rate near the contact line produces the vapor cutback due to the vapor recoil pushing the three-phase line outwards from the fiber tip, and so a neck of the bubble is formed near the bubble bottom. Evaporation and surface tension accelerate the necking process and finally result in the bubble departure while a new small bubble is formed at the tip when the surface tension pushes the three-phase line back to the tip. The process is schematically shown. The proposed model is based on and confirmed by experimental results.

  9. Characteristics of Pool Boiling on Graphite-Copper Composite Surfaces

    NASA Technical Reports Server (NTRS)

    Zhang, Nengli; Chao, David F.; Yang, Wen-Jei

    2002-01-01

    significant augmentation in nucleate boiling heat transfer on the composite surfaces. A physical model is developed to describe the phenomenon of bubble departure from the composite surface: The preferred site of bubble nucleation is the fiber tip because of higher tip temperature than the surrounding copper base and poor wettability of the graphite tip compared with that of the base material (copper). The high evaporation rate near the contact line produces the vapor cutback due to the vapor recoil pushing the three-phase line outwards from the fiber tip, and so a neck of the bubble is formed near the bubble bottom. Evaporation and surface tension accelerate the necking process and finally result in the bubble departure while a new small bubble is formed at the tip when the surface tension pushes the three-phase line back to the tip. The process is schematically shown. The proposed model is based on and confirmed by experimental results.

  10. Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

    NASA Astrophysics Data System (ADS)

    Yoshida, Suguru; Fujita, Yasunobu

    The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

  11. Contact dermatitis

    MedlinePlus

    Dermatitis - contact; Allergic dermatitis; Dermatitis - allergic; Irritant contact dermatitis; Skin rash - contact dermatitis ... There are 2 types of contact dermatitis. Irritant dermatitis: This ... can be by contact with acids, alkaline materials such as soaps ...

  12. Boiling point measurement of a small amount of brake fluid by thermocouple and its application.

    PubMed

    Mogami, Kazunari

    2002-09-01

    This study describes a new method for measuring the boiling point of a small amount of brake fluid using a thermocouple and a pear shaped flask. The boiling point of brake fluid was directly measured with an accuracy that was within approximately 3 C of that determined by the Japanese Industrial Standards method, even though the sample volume was only a few milliliters. The method was applied to measure the boiling points of brake fluid samples from automobiles. It was clear that the boiling points of brake fluid from some automobiles dropped to approximately 140 C from about 230 C, and that one of the samples from the wheel cylinder was approximately 45 C lower than brake fluid from the reserve tank. It is essential to take samples from the wheel cylinder, as this is most easily subjected to heating.

  13. Direct growth of carbon nanofibers to generate a 3D porous platform on a metal contact to enable an oxygen reduction reaction.

    PubMed

    Pan, David; Ombaba, Matthew; Zhou, Zhi-You; Liu, Yang; Chen, Shaowei; Lu, Jennifer

    2012-12-21

    For carbon nanotube-based electronics to achieve their full performance potential, it is imperative to minimize the contact resistance between macroscale metal contacts and the carbon nanotube (CNT) nanoelectrodes. We have developed a three-dimensional electrode platform that consists of carbon nanofibers (CNFs) that are directly grown on a metal contact, such as copper (Cu). Carbon nanofiber morphology can be tailored by adjusting the annealing time of a thin electrochemically deposited nickel catalyst layer on copper. We demonstrate that increasing the annealing time increases the amount of copper infused into the nickel catalyst layer. This reduces the carbon deposition rate, and consequently a more well-defined CNF 3D architecture can be fabricated. This direct growth of CNFs on a Cu substrate yields an excellent electron transfer pathway, with contact resistance between CNFs and Cu being comparable to that of a Cu-Cu interface. Furthermore, the excellent bonding strength between CNFs and Cu can be maintained over prolonged periods of ultrasonication. The porous 3D platform affixed with intertwined CNFs allows facile surface functionalization. Using a simple solution soaking procedure, the CNF surface has been successfully functionalized with iron(II) phthalocyanine (FePc). FePc functionalized CNFs exhibit excellent oxygen reduction capability, equivalent to platinum-carbon electrodes. This result demonstrates the technological promise of this new 3D electrode platform that can be exploited in other applications that include sensing, battery, and supercapacitors.

  14. Single-bubble dynamics in pool boiling of one-component fluids.

    PubMed

    Xu, Xinpeng; Qian, Tiezheng

    2014-06-01

    We numerically investigate the pool boiling of one-component fluids with a focus on the effects of surface wettability on the single-bubble dynamics. We employed the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)], a diffuse-interface model for liquid-vapor flows involving liquid-vapor transition in nonuniform temperature fields. We first perform simulations for bubbles on homogeneous surfaces. We find that an increase in either the contact angle or the surface superheating can enhance the bubble spreading over the heating surface and increase the bubble departure diameter as well and therefore facilitate the transition into film boiling. We then examine the dynamics of bubbles on patterned surfaces, which incorporate the advantages of both hydrophobic and hydrophilic surfaces. The central hydrophobic region increases the thermodynamic probability of bubble nucleation while the surrounding hydrophilic region hinders the continuous bubble spreading by pinning the contact line at the hydrophobic-hydrophilic intersection. This leads to a small bubble departure diameter and therefore prevents the transition from nucleate boiling into film boiling. With the bubble nucleation probability increased and the bubble departure facilitated, the efficiency of heat transfer on such patterned surfaces is highly enhanced, as observed experimentally [Int. J. Heat Mass Transfer 57, 733 (2013)]. In addition, the stick-slip motion of contact line on patterned surfaces is demonstrated in one-component fluids, with the effect weakened by surface superheating.

  15. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Boiling water sterilizer. 872.6710 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered device that consists of a container for boiling...

  16. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Boiling water sterilizer. 872.6710 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered device that consists of a container for boiling...

  17. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Boiling water sterilizer. 872.6710 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered device that consists of a container for boiling...

  18. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Boiling water sterilizer. 872.6710 Section 872...) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an AC-powered device that consists of a container for boiling...

  19. Analysis of boiling flat-plate collectors

    SciTech Connect

    Price, H.W.; Klein, S.A.; Beckman, W.A.

    1986-05-01

    A detailed model for use with TRNSYS, capable of modelling a wide range of boiling collector types, was used to analyze boiling flat-plate collector systems. This model can account for a subcooled liquid entering the collector, heat losses in the vapor and the liquid return line, pressure drops due to friction in the collector and piping, and pressure drops due to the hydrostatic head of the fluid. The model has been used to determine the yearly performance of boiling flat-plate solar collector systems. A simplified approach was also developed which can be used with the f-Chart method to predict yearly performance of boiling flat-plate collector systems.

  20. Conceptual design for spacelab pool boiling experiment

    NASA Technical Reports Server (NTRS)

    Lienhard, J. H.; Peck, R. E.

    1978-01-01

    A pool boiling heat transfer experiment to be incorporated with a larger two-phase flow experiment on Spacelab was designed to confirm (or alter) the results of earth-normal gravity experiments which indicate that the hydrodynamic peak and minimum pool boiling heat fluxes vanish at very low gravity. Twelve small sealed test cells containing water, methanol or Freon 113 and cylindrical heaters of various sizes are to be built. Each cell will be subjected to one or more 45 sec tests in which the surface heat flux on the heaters is increased linearly until the surface temperature reaches a limiting value of 500 C. The entire boiling process will be photographed in slow-motion. Boiling curves will be constructed from thermocouple and electric input data, for comparison with the motion picture records. The conduct of the experiment will require no more than a few hours of operator time.

  1. Microlayer during boiling in narrow slot channels

    NASA Astrophysics Data System (ADS)

    Diev, Mikhail D.; Leontiev, Alexander I.

    1997-01-01

    An international space station Alpha will have a two-phase thermal control system. Boiling of a liquid ammonia will be a process of heat collection in evaporative heat exchangers. Unfortunately, only little data is available for boiling heat transfer in microgravity. Geometries of boiling channels working good in normal gravity are not appropriate in microgravity, and special means should be worked out to avoid some undesired events. From this point of view, the narrow slot channels may be assumed as a promising geometry for microgravity operation. During boiling in narrow slots, the vapor bubbles are flattened between the channel walls. The vapor phase and the channel wall are separated by a thin liquid film which is known as a microlayer. The paper presents the experimental results compared to the theoretical analysis, the paper also shows the narrow slot channels as a perspective configuration for microgravity applications.

  2. Why Is NASA Boiling Fluids in Space?

    NASA Image and Video Library

    Convection and buoyancy work differently in space than on Earth. Learn how NASA uses this information and applies it to everyday life. Boiling fluids in space is easier than it is on Earth. Learn m...

  3. Direct contact transmission of three different foot-and-mouth disease virus strains in swine demonstrates important strain-specific differences.

    PubMed

    Pacheco, Juan M; Tucker, Meghan; Hartwig, Ethan; Bishop, Elizabeth; Arzt, Jonathan; Rodriguez, Luis L

    2012-08-01

    A novel direct contact transmission model for the study of foot-and-mouth disease virus (FMDV) infection of swine was utilized to investigate transmission characteristics of three FMDV strains belonging to serotypes A, O and Asia1. Each strain demonstrated distinct transmission characteristics and required different exposure times to achieve successful contact transmission. While a 4h exposure was sufficient for strain A24 Cruzeiro (A24Cru), both O1 Manisa and Asia1 Shamir transmission required 18 h or more. Viral excretion levels from donors (for all three strains) and virus present in room air (for A24Cru and O1 Manisa) were evaluated and associated with clinical signs and observed transmission pattern. Although all directly inoculated donor animals showed acute FMD, A24Cru had the highest levels of viral shedding in saliva and nasal swabs followed by O1 Manisa and Asia1 Shamir. Virus levels in room air were higher and were detected longer for A24Cru than for O1 Manisa. These results provide direct evidence for important strain-specific variation in transmission characteristics and emphasize the need for thorough evaluation of different FMDV viral strains using a well defined contact transmission methodology. This information is critical for vaccine and biotherapeutic efficacy testing, pathogenesis and disease modeling of FMDV transmission. Published by Elsevier Ltd.

  4. LRIG1 regulates cadherin-dependent contact inhibition directing epithelial homeostasis and pre-invasive squamous cell carcinoma development

    PubMed Central

    Lu, Liwen; Teixeira, Vitor H; Yuan, ZhengQiang; Graham, Trevor A; Endesfelder, David; Kolluri, Krishna; Al-Juffali, Noura; Hamilton, Nicholas; Nicholson, Andrew G; Falzon, Mary; Kschischo, Maik; Swanton, Charles; Wright, Nicholas A; Carroll, Bernadette; Watt, Fiona M; George, Jeremy P; Jensen, Kim B; Giangreco, Adam; Janes, Sam M

    2013-01-01

    Epidermal growth factor receptor (EGFR) pathway activation is a frequent event in human carcinomas. Mutations in EGFR itself are, however, rare, and the mechanisms regulating EGFR activation remain elusive. Leucine-rich immunoglobulin repeats-1 (LRIG1), an inhibitor of EGFR activity, is one of four genes identified that predict patient survival across solid tumour types including breast, lung, melanoma, glioma, and bladder. We show that deletion of Lrig1 is sufficient to promote murine airway hyperplasia through loss of contact inhibition and that re-expression of LRIG1 in human lung cancer cells inhibits tumourigenesis. LRIG1 regulation of contact inhibition occurs via ternary complex formation with EGFR and E-cadherin with downstream modulation of EGFR activity. We find that LRIG1 LOH is frequent across cancers and its loss is an early event in the development of human squamous carcinomas. Our findings imply that the early stages of squamous carcinoma development are driven by a change in amplitude of EGFR signalling governed by the loss of contact inhibition. PMID:23208928

  5. Direct Contacts Between Extracellular Membrane-Proximal Domains are Required for VEGF Receptor Activation and Cell Signaling

    SciTech Connect

    Yang, Y.; Xie, P; Opatowsky, Y; Schlessinger, J

    2010-01-01

    Structural analyses of the extracellular region of stem cell factor (SCF) receptor (also designated KIT) in complex with SCF revealed a sequence motif in a loop in the fourth Ig-like domain (D4) that is responsible for forming homotypic receptor contacts and for ligand-induced KIT activation and cell signaling. An identical motif was identified in the most membrane-proximal seventh Ig-like domain (D7) of vascular endothelial growth factor receptor 1 (VEGFR1), VEGFR2, and VEGFR3. In this report we demonstrate that ligand-induced tyrosine autophosphorylation and cell signaling via VEGFR1 or VEGFR2 harboring mutations in critical residues (Arg726 or Asp731) in D7 are strongly impaired. We also describe the crystal structure of D7 of VEGFR2 to a resolution of 2.7 {angstrom}. The structure shows that homotypic D7 contacts are mediated by salt bridges and van der Waals contacts formed between Arg726 of one protomer and Asp731 of the other protomer. The structure of D7 dimer is very similar to the structure of D4 dimers seen in the crystal structure of KIT extracellular region in complex with SCF. The high similarity between VEGFR D7 and KIT D4 in both structure and function provides further evidence for common ancestral origins of type III and type V RTKs. It also reveals a conserved mechanism for RTK activation and a novel target for pharmacological intervention of pathologically activated RTKs.

  6. Cross Flow Boiling in Tube Bundles.

    DTIC Science & Technology

    1982-10-01

    subsequent corrosion induced failure of the heating tube , an understanding of the fluid motion and heat transfer behavior in confined spaces will be...1-1982A U Cross Flowing Boiling in Tube Bundles Annual Technical Report October 1982 LOD S.C. Yao Associate Professor Department of Mechanical...Subtitle) S. TYPE OF REPORT & PERIOD COVERED Annual Technical Report CROSS FLOW BOILING IN TUBE BUNDLES Aug. 1, 1981 to Aug. 1, 1982 - 6. PERFORMING ORG

  7. Experimental investigation on the phenomena around the onset nucleate boiling during the impacting of a droplet on the hot surface

    NASA Astrophysics Data System (ADS)

    Mitrakusuma, Windy H.; Deendarlianto, Kamal, Samsul; Indarto, Nuriyadi, M.

    2016-06-01

    Onset of nucleate boiling of a droplet when impacted onto hot surface was investigated. Three kinds of surfaces, normal stainless steel (NSS), stainless steel with TiO2 coating (UVN), and stainless steel with TiO2 coating and radiated by ultraviolet ray were employed to examine the effect of wettability. The droplet size was 2.4 mm diameter, and dropped under different We number. The image is generated by high speed camera with the frame speed of 1000 fps. The boiling conditions are identified as natural convection, nucleate boiling, critical heat flux, transition, and film boiling. In the present report, the discussion will be focused on the beginning of nucleate boiling on the droplet. Nucleate boiling occurs when bubbles are generated. These bubbles are probably caused by nucleation on the impurities within the liquid rather than at nucleation sites on the heated surface because the bubbles appear to be in the bulk of the liquid instead of at the liquid-solid interface. In addition, the smaller the contact angle, the fastest the boiling.

  8. Experimental investigation on the phenomena around the onset nucleate boiling during the impacting of a droplet on the hot surface

    SciTech Connect

    Mitrakusuma, Windy H.; Deendarlianto,; Kamal, Samsul; Indarto; Nuriyadi, M.

    2016-06-03

    Onset of nucleate boiling of a droplet when impacted onto hot surface was investigated. Three kinds of surfaces, normal stainless steel (NSS), stainless steel with TiO{sub 2} coating (UVN), and stainless steel with TiO{sub 2} coating and radiated by ultraviolet ray were employed to examine the effect of wettability. The droplet size was 2.4 mm diameter, and dropped under different We number. The image is generated by high speed camera with the frame speed of 1000 fps. The boiling conditions are identified as natural convection, nucleate boiling, critical heat flux, transition, and film boiling. In the present report, the discussion will be focused on the beginning of nucleate boiling on the droplet. Nucleate boiling occurs when bubbles are generated. These bubbles are probably caused by nucleation on the impurities within the liquid rather than at nucleation sites on the heated surface because the bubbles appear to be in the bulk of the liquid instead of at the liquid-solid interface. In addition, the smaller the contact angle, the fastest the boiling.

  9. Fundamental Boiling and RP-1 Freezing Experiments

    NASA Technical Reports Server (NTRS)

    Goode, Brian

    2002-01-01

    The prestart thermal conditioning of the hardware in LOX (liquid oxygen) systems involve heat transfer between LOX and metal where boiling plays a large role. Information is easily found on nucleate boiling, maximum heat flux, minimum heat flux and film boiling for common fluids like water. After looking at these standard correlations it was felt more data was needed for the cool down side transition boiling for the LN2 and LOX. In particular interest is the film boiling values, the temperature at which transition begins and the slope as peak heat flux is approached. The ultimate goal is an array of boiling heat transfer coefficient as a function of surface temperature which can be used in the chilldown model of the feed system, engine and bleed system for X-34. The first experiment consisted of an actual MC-1 LOX Impeller which had been machined backwards, that was instrumented with 17 surface thermocouples and submerged in liquid nitrogen. The thermocouples were installed on metal thicknesses varying from the thin inducer to the thick hub.

  10. High flux film and transition boiling

    SciTech Connect

    Witte, L.C.

    1993-02-01

    An investigation was conducted on the potential for altering the boiling curve through effects of high velocity and high subcooling. Experiments using water and Freon-113 flowing over cylindrical electrical heaters in crossflow were made to see how velocity and subcooling affect the boiling curve, especially the film and transition boiling regions. We sought subcooling levels down to near the freezing points of these two liquids to prove the concept that the critical heat flux and the minimum heat flux could be brought together, thereby averting the transition region altogether. Another emphasis was to gain insight into how the various boiling regions could be represented mathematically on various parts of heating surface. Motivation for the research grew out of a realization that the effects of very high subcooling and velocity might be to avert the transition boiling altogether so that the unstable part of the boiling curve would not limit the application of high flux devices to temperatures less than the burnout temperatures. Summaries of results from the study are described. It shows that the potential for averting, the transition region is good, and points the way to further research that is needed to demonstrate the potential.

  11. An investigation of vapor concentration during boiling of liquid mixtures

    SciTech Connect

    Utaka, Yoshio; Takahashi, Katsuaki; Tsuboi, Takao

    1999-07-01

    The objective of the study is to clarify experimentally the variation of the vapor concentration of binary mixture generated during nucleate boiling in a saturated pool under various boiling conditions. The generated vapor concentrations in the bulk vapor layer were measured for the binary mixtures of water-ethanol and ethanol-acetone under various liquid concentrations, the heat fluxes and the liquid layer heights from the heated thin wires at the atmospheric pressure. The main experimental apparatus for measuring concentration of bulk vapor in the boiling and condensation system is shown. Two methods of measuring concentration, i.e., the dew point method and the laser absorption method were adopted. The dew point measurement was carried out by utilizing the copper heat transfer block installed in the central part of the vapor layer in the vessel. The commencement of the condensation was observed directly for determining the dew point by controlling its temperature. The laser light having wavelength of 3.39 micron meters was used for the laser light absorption method utilizing its absorptive property against ethanol vapor. The measured results by using both methods coincided well with each other. The measured concentrations of the bulk vapor for various superheatings of heated wires, the depth of liquid mixture layer and liquid concentrations were almost independent of those parameters and were almost in equilibrium with bulk liquid conditions even under the higher surface superheating and the lower liquid heights.

  12. Pool Boiling Enhancement on Textured Surfaces using Acoustic Actuation

    NASA Astrophysics Data System (ADS)

    Boziuk, Thomas; Smith, Marc; Glezer, Ari

    2015-11-01

    Boiling heat transfer on submerged textured heated surfaces is enhanced using ultrasound actuation. The heated surface is textured using an array of open microchannels that advantageously separate the nucleation sites on the surface and inhibit the transition to film boiling, which significantly increases the critical heat flux compared to a smooth surface of the same planform dimensions. The present investigation shows that the formation and evolution of vapor bubbles on the heated surface can be substantially altered by a highly directional ultrasound (1.7 MHz) beam, and leads to significant enhancement in heat transfer, including reduced surface superheat and increased critical heat flux (exceeding 55%). The effects of the beam incidence and azimuthal angle on vapor formation, advection, and resulting effect on surface superheat are investigated experimentally in a liquid test cell. Heat transfer enhancement characterized by changes in the boiling curve (i.e., superheat and CHF) varies with surface texturing and is also dependent on acoustic beam orientation relative to the surface texture pattern.

  13. A decade of occupational accidents due to direct or indirect electrical contact in the primary, secondary and tertiary sectors in Spain (2003-2012).

    PubMed

    Castillo-Rosa, Juan; Suárez-Cebador, Manuel; Rubio-Romero, Juan Carlos; Aguado, Jose Antonio

    2017-03-01

    Occupational accidents caused by electrical contact are a major concern worldwide due to their severe consequences. The study conducted is based on an analysis of the evolution of incidence rates and dependence between variables for 14,022 electrical accidents occurring in Spain between 2003 and 2012. The results show that electrical accidents as a whole are 3.6 times more likely to have severe consequences than the rest of the accidents in the country. This proportion is even nine times greater in the case of fatal accidents. They also confirm a significant relationship between the severity of this type of accidents and the economic sector in which they occur. On the other hand, there is a positive trend in the reduction of the incidence rate, especially in relation to direct contact, although unexpectedly the rate of accidents due to indirect contact is on the rise. Thus, preventing electrical occupational accidents requires efforts to guarantee adequate training adapted to the needs of workers in the various economic sectors. Furthermore, those responsible for safety should work to implement mechanisms to monitor and control compliance with efficient protective measures against electrical contact.

  14. Migration of selected hydrocarbon contaminants into dry semolina and egg pasta packed in direct contact with virgin paperboard and polypropylene film.

    PubMed

    Barp, Laura; Suman, Michele; Lambertini, Francesca; Moret, Sabrina

    2015-01-01

    Migration of mineral oil saturated hydrocarbons (MOSH), polyolefin oligomeric saturated hydrocarbons (POSH), and polyalphaolefins (PAO from hot melts) into dry semolina and egg pasta packed in direct contact with virgin paperboard or polypropylene (PP) flexible film was studied. Migration was monitored during shelf life (up to 24 months), through storage in a real supermarket (packs kept on shelves), conditions preventing exchange with the surrounding environment (packs wrapped in aluminium foil), and storage in a warehouse (packs inside of the transport box of corrugated board). Semolina pasta packed in virgin paperboard (without hot melts) had a MOSH content lower than 1.0 mg kg(-1). An increasing contamination with PAO belonging to the adhesives used to close the boxes was detected in egg pasta, wrapped in aluminium (1.5 and 5 mg kg(-1) after 3 and 24 months, respectively). An environmental contribution to total hydrocarbon contamination was observed in egg pasta kept on shelves that, after 3 and 24 months, showed levels of PAO/MOSH < C25 around 3 and 10 mg kg(-1), respectively. The migration of POSH from PP film into egg pasta wrapped in aluminium was around 0.6 mg kg(-1) after 3 months of contact and reached 1.7 mg kg(-1) after 24 months of contact. After 9 months of contact, semolina pasta packed in PP film and stored in the transport box showed that some MOSH migrated into the pasta from the board of the transport box (through the plastic film).

  15. Boiling phenomenon due to quasi-steadily and rapidly increasing heat inputs in LN 2 and LHe I

    NASA Astrophysics Data System (ADS)

    Sakurai, A.; Shiotsu, M.; Hata, K.

    Dynamic boiling processes, including the transition from a single-phase non-boiling regime to film boiling caused by exponentially increasing heat inputs, Q 0e t/τ for a wide range of periods and pressures on horizontal wires in LN 2 and LHe I were investigated. The main problem is that there are no active cavities on the wire surfaces for initial boiling in the liquids. The heat transfer processes due to increasing heat inputs with increasing rates ranging from quasi-steady to rapidly increasing ones in LN 2 were classified into three types for the pressures. The dynamic boiling processes in LHe I due to rapidly increasing heat inputs at the pressures tested here correspond to Type 3 processes including semi-direct transitions in LN 2 at pressures higher than about 1 MPa. The lower limit temperatures of boiling initiation on the wire surfaces for initial boiling in liquids at pressures due to quasi-steadily increasing heat inputs are clearly lower than the homogeneous spontaneous nucleation temperatures corresponding to these pressures. Liquid superheat close to the solid surface in LHe I was evaluated from the value of the wire surface temperature, taking off the temperature drop due to Kapitza resistance. The initial boiling temperatures due to quasi-steady heat inputs at pressures in saturated LN 2 and LHe I agreed with the values derived from the theoretical model based on the heterogeneous spontaneous nucleation in flooded cavities on the solid surface.

  16. Gas bubbling-enhanced film boiling of Freon-11 on liquid metal pools. [PWR; BWR

    SciTech Connect

    Greene, G.A.

    1985-01-01

    In the analysis of severe core damage accidents in LWRs, a major driving force which must be considered in evaluating containment loading and fission product transport is the ex-vessel interaction between molten core debris and structural concrete. Two computer codes have been developed for this purpose, the CORCON-MOD2 model of ex-vessel, core concrete interactions and the VANESA model for aerosol generation and fission product release as a result of molten core-concrete interactions. Under a wide spectrum of reactor designs and accident sequences, it is possible for water to come into contact with the molten core debris and form a coolant pool overlying the core debris which is attacking the concrete. As the concrete decomposes, noncondensable gases are released, which bubble through the melt and across the boiling interface, affecting the liquid-liquid boiling process. Currently, the CORCON code includes the classical Berenson model for film boiling over a horizontal flat plate for this phenomenon. The objectives of this activity are to investigate the influence of transverse noncondensable gas flux on the magnitude of the stable liquid-liquid film boiling heat flux and develop a gas flux-enhanced, liquid-liquid film boiling model for incorporation into the CORCON-MOD2 computer code to replace or modify the Berenson model.

  17. Drop collision with a hot, dry solid substrate: Heat transfer during nucleate boiling

    NASA Astrophysics Data System (ADS)

    Breitenbach, Jan; Roisman, Ilia V.; Tropea, Cameron

    2017-07-01

    Outcomes from an isothermal drop impact onto a surface (rebound, deposition, or splash) are determined by the impact parameters, liquid material properties, substrate morphology, and wettability. Drop impact onto a hot surface can be accompanied by Marangoni effects, nucleate or film boiling, and evaporation. The main focus of this experimental study is the characterization of the hydrodynamic outcome of a single-drop impact onto a hot surface. Drop impact phenomena have been observed and characterized using a high-speed video system. The impact parameters of the drop and the surface temperature have been varied. The observations lead to a classification of impact outcomes into several regimes: evaporation, nucleate boiling, foaming, transitional boiling, and film boiling. The contact time of the impinging droplet on the surface has been measured, and a model for this time and for the heat flux from the substrate to the drop has been proposed for the nucleate boiling regime. Comparison of model predictions to existing literature data is good.

  18. Multifunctional bowtie-shaped ridge aperture for overlay alignment in plasmonic direct writing lithography using a contact probe.

    PubMed

    Oh, Seonghyeon; Lee, Taekyong; Hahn, Jae W

    2013-07-01

    We propose a scheme of overlay alignment for plasmonic lithography using a scanning contact probe. Using two resonances of a ridge aperture in a metal film, we introduce the aperture's multifunctional characteristics for patterning and alignment at different wavelengths. To verify this idea, we measure an image of an alignment mark using a scanning ridge aperture and determine the reference point for the alignment. We then analyze the uncertainty of the alignment method with respect to the image data noise and compare the numerical results with the experimental results. The uncertainty of the overlay alignment method is shown to be less than approximately 2 nm.

  19. Initiation of explosive boiling of a droplet with a shock wave

    NASA Astrophysics Data System (ADS)

    Frost, D. L.

    1989-12-01

    The role of incident shock waves in the initiation of vapor explosions in volatile liquid hydrocarbons has been investigated. Experiments were carried out on single droplets (1 2 mm diameter) immersed in a host fluid and heated to temperatures at or near the limit of superheat. Shocks generated by spark discharge were directed at previously nonevaporating drops as well as at drops boiling stably at high pressure. Explosive boiling is triggered in previously nonevaporating drops only if the drop temperature is above a threshold temperature that is near the superheat limit. Interaction of a shock with a stably boiling drop immediately causes a transition to violent unstable boiling in which fine droplets are torn from the evaporating interface, generating a two-phase flow downstream. On the previously nonevaporating interface between the drop and the host liquid, multiple nucleation sites appear which grow rapidly and coalesce. Overpressures generated in the surrounding fluid during bubble collapse may reach values on the same level as the pressure jump across the shock wave that initiated the explosive boiling. A simple calculation is given, which suggests that shock focusing may influence the location at which unstable boiling is initiated.

  20. The effects of self-directed home exercise with serial telephone contacts on physical functions and quality of life in elderly people at high risk of locomotor dysfunction.

    PubMed

    Aoki, Kana; Sakuma, Mayumi; Ogisho, Noriyuki; Nakamura, Kozo; Chosa, Etsuo; Endo, Naoto

    2015-01-01

    Exercise is essential for maintaining quality of life (QOL) in elderly individuals. However, adherence to exercise programs is low. Here, we assessed the effectiveness of a self-directed home exercise program with serial telephone contacts to encourage exercise adherence among elderly individuals at high risk of locomotor dysfunction. We recruited community-dwelling adults (ァ65 years) in Niigata, Japan, who were targets of the long-term care prevention project for locomotor dysfunction but did not participate in the government-sponsored prevention programs. The study was conducted from November 2011 to October 2012. Participants received exercise instruction and performed exercises independently for 3 months with serial telephone contacts. The single-leg stance and five-times sit-to-stand tests were used to assess physical function. The SF-8 was used to measure health-related QOL. Ninety-seven participants were enrolled in the study, representing 2.5% of eligible people;87 completed the intervention. Scores from physical function tests were significantly improved by the intervention, as were 7 of eight SF-8 subscales. Adherence was 85.4% for the single-leg standing exercise and 82.1% for squatting. Thus, self-directed home exercise with serial telephone contacts improved physical function and health-related QOL, representing a promising model for preventing the need for long-term care due to locomotor dysfunction.

  1. A numerical approach for the direct computation of flows including fluid-solid interaction: Modeling contact angle, film rupture, and dewetting

    NASA Astrophysics Data System (ADS)

    Mahady, K.; Afkhami, S.; Kondic, L.

    2016-06-01

    In this paper, we present a computationally efficient method for including fluid-solid interactions into direct numerical simulations of the Navier-Stokes equations. This method is found to be as powerful as our earlier formulation [K. Mahady et al., "A volume of fluid method for simulating fluid/fluid interfaces in contact with solid boundaries," J. Comput. Phys. 294, 243 (2015)], while outperforming the earlier method in terms of computational efficiency. The performance and efficacy of the presented method are demonstrated by computing contact angles of droplets at equilibrium. Furthermore, we study the instability of films due to destabilizing fluid-solid interactions, and discuss the influence of contact angle and inertial effects on film breakup. In particular, direct simulation results show an increase in the final characteristic length scales when compared to the predictions of a linear stability analysis, suggesting significant influence of nonlinear effects. Our results also show that emerging length scales differ, depending on a number of physical dimensions considered.

  2. Cryogenic Boil-Off Reduction System

    NASA Astrophysics Data System (ADS)

    Plachta, David W.; Guzik, Monica C.

    2014-03-01

    A computational model of the cryogenic boil-off reduction system being developed by NASA as part of the Cryogenic Propellant Storage and Transfer technology maturation project has been applied to a range of propellant storage tanks sizes for high-performing in-space cryogenic propulsion applications. This effort focuses on the scaling of multi-layer insulation (MLI), cryocoolers, broad area cooling shields, radiators, solar arrays, and tanks for liquid hydrogen propellant storage tanks ranging from 2 to 10 m in diameter. Component scaling equations were incorporated into the Cryogenic Analysis Tool, a spreadsheet-based tool used to perform system-level parametric studies. The primary addition to the evolution of this updated tool is the integration of a scaling method for reverse turbo-Brayton cycle cryocoolers, as well as the development and inclusion of Self-Supporting Multi-Layer Insulation. Mass, power, and sizing relationships are traded parametrically to establish the appropriate loiter period beyond which this boil-off reduction system application reduces mass. The projected benefit compares passive thermal control to active thermal control, where active thermal control is evaluated for reduced boil-off with a 90 K shield, zero boil-off with a single heat interception stage at the tank wall, and zero boil-off with a second interception stage at a 90 K shield. Parametric studies show a benefit over passive storage at loiter durations under one month, in addition to showing a benefit for two-stage zero boil-off in terms of reducing power and mass as compared to single stage zero boil-off. Furthermore, active cooling reduces the effect of varied multi-layer insulation performance, which, historically, has been shown to be significant.

  3. Enhancements of Nucleate Boiling Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Zhang, Nengli; Chao, David F.; Yang, W. J.

    2000-01-01

    This paper presents two means for enhancing nucleate boiling and critical heat flux under microgravity conditions: using micro-configured metal-graphite composites as the boiling surface and dilute aqueous solutions of long-chain alcohols as the working fluid. In the former, thermocapillary force induced by temperature difference between the graphite-fiber tips and the metal matrix plays an important role in bubble detachment. Thus boiling-heat transfer performance does not deteriorate in a reduced-gravity environment. In the latter cases, the surface tension-temperature gradient of the long-chain alcohol solutions turns positive as the temperature exceeds a certain value. Consequently, the Marangoni effect does not impede, but rather aids in bubble departure from the heating surface. This feature is most favorable in microgravity. As a result, the bubble size of departure is substantially reduced at higher frequencies. Based on the existing experimental data, and a two-tier theoretical model, correlation formulas are derived for nucleate boiling on the copper-graphite and aluminum-graphite composite surfaces, in both the isolated and coalesced bubble regimes. In addition, performance equations for nucleate boiling and critical heat flux in dilute aqueous solutions of long-chain alcohols are obtained.

  4. Structural changes of malt proteins during boiling.

    PubMed

    Jin, Bei; Li, Lin; Liu, Guo-Qin; Li, Bing; Zhu, Yu-Kui; Liao, Liao-Ning

    2009-03-09

    Changes in the physicochemical properties and structure of proteins derived from two malt varieties (Baudin and Guangmai) during wort boiling were investigated by differential scanning calorimetry, SDS-PAGE, two-dimensional electrophoresis, gel filtration chromatography and circular dichroism spectroscopy. The results showed that both protein content and amino acid composition changed only slightly during boiling, and that boiling might cause a gradual unfolding of protein structures, as indicated by the decrease in surface hydrophobicity and free sulfhydryl content and enthalpy value, as well as reduced alpha-helix contents and markedly increased random coil contents. It was also found that major component of both worts was a boiling-resistant protein with a molecular mass of 40 kDa, and that according to the two-dimensional electrophoresis and SE-HPLC analyses, a small amount of soluble aggregates might be formed via hydrophobic interactions. It was thus concluded that changes of protein structure caused by boiling that might influence beer quality are largely independent of malt variety.

  5. A depletable micro-layer model for nucleate pool boiling

    NASA Astrophysics Data System (ADS)

    Sato, Yohei; Niceno, Bojan

    2015-11-01

    A depletable micro-layer model has been developed for the simulation of nucleate pool boiling within the framework of Computational Fluid Dynamics (CFD) modeling using an interface-tracking method. A micro-layer model is required for the CFD simulation to take into account vaporization from the thin liquid film - called the micro-layer - existing beneath a growing vapor bubble on a hot surface. In our model, the thickness of the micro-layer is a variable defined at each discretized fluid cell adjacent to the heat-transfer surface; the layer decreases due to vaporization, and can finally disappear. Compared to existing micro-region models, most of them based on the concept of contact-line evaporation, as originally proposed by Stephan and Busse, and by Lay and Dhir, our model incorporates simplified modeling ideas, but can nonetheless predict the temperature field beneath the growing bubble accurately. The model proposed in this paper has been validated against measurements of pool boiling in water at atmospheric pressure. Specifically, the bubble principal dimensions and the temperature distribution over the heat-transfer surface are in good agreement with experimental data.

  6. Boiling water neutronic reactor incorporating a process inherent safety design

    DOEpatents

    Forsberg, C.W.

    1985-02-19

    A boiling-water reactor core is positioned within a prestressed concrete reactor vessel of a size which will hold a supply of coolant water sufficient to submerge and cool the reactor core by boiling for a period of at least one week after shutdown. Separate volumes of hot, clean (nonborated) water for cooling during normal operation and cool highly borated water for emergency cooling and reactor shutdown are separated by an insulated wall during normal reactor operation with contact between the two water volumes being maintained at interfaces near the top and bottom ends of the reactor vessel. Means are provided for balancing the pressure of the two water volumes at the lower interface zone during normal operation to prevent entry of the cool borated water into the reactor core region, for detecting the onset of excessive power to coolant flow conditions in the reactor core and for detecting low water levels of reactor coolant. Cool borated water is permitted to flow into the reactor core when low reactor coolant levels or excessive power to coolant flow conditions are encountered.

  7. Boiling water neutronic reactor incorporating a process inherent safety design

    DOEpatents

    Forsberg, Charles W.

    1987-01-01

    A boiling-water reactor core is positioned within a prestressed concrete reactor vessel of a size which will hold a supply of coolant water sufficient to submerge and cool the reactor core by boiling for a period of at least one week after shutdown. Separate volumes of hot, clean (non-borated) water for cooling during normal operation and cool highly borated water for emergency cooling and reactor shutdown are separated by an insulated wall during normal reactor operation with contact between the two water volumes being maintained at interfaces near the top and bottom ends of the reactor vessel. Means are provided for balancing the pressure of the two volumes at the lower interface zone during normal operation to prevent entry of the cool borated water into the reactor core region, for detecting the onset of excessive power to coolant flow conditions in the reactor core and for detecting low water levels of reactor coolant. Cool borated water is permitted to flow into the reactor core when low reactor coolant levels or excessive power to coolant flow conditions are encountered.

  8. Momentum effects in steady nucleate pool boiling during microgravity.

    PubMed

    Merte, Herman

    2004-11-01

    Pool boiling experiments were conducted in microgravity on five space shuttle flights, using a flat plate heater consisting of a semitransparent thin gold film deposited on a quartz substrate that also acted as a resistance thermometer. The test fluid was R-113, and the vapor bubble behavior at the heater surface was photographed from beneath as well as from the side. Each flight consisted of a matrix of three levels of heat flux and three levels of subcooling. In 26 of the total of 45 experiments conditions of steady-state pool boiling were achieved under certain combinations of heat flux and liquid subcooling. In many of the 26 cases, it was observed from the 16-mm movie films that a large vapor bubble formed, remaining slightly removed from the heater surface, and that subsequent vapor bubbles nucleate and grow on the heater surface. Coalescence occurs upon making contact with the large bubble, which thus acts as a vapor reservoir. Recently, measurements of the frequencies and sizes of the small vapor bubbles as they coalesced with the large bubble permitted computation of the associated momentum transfer. The transient forces obtained are presented here. Where these arise from the conversion of the surface energy in the small vapor bubble to kinetic energy acting away from the solid heater surface, they counter the Marangoni convection due to the temperature gradients normal to the heater surface. This Marangoni convection would otherwise impel the large vapor bubble toward the heater surface and result in dryout and unsteady heat transfer.

  9. Experimental Study on the Effect of Liquid Contact Angle on Bubble Movement under Microgravity

    NASA Astrophysics Data System (ADS)

    Yanjie, Yang; Li, Shiyou; Yiyong, Huang; Guangyu, Li

    2016-07-01

    The experimental study of bubble dynamics under microgravity has been conducted utilizing the Drop Tower Beijing(NMLC). A pottery sized of 20mm in length, 10mm in width and 1.2mm in height was used as the heater. The fluid was HFE7500 and distilled water. During the experiment under microgravity the nucleate boiling and film boiling were observed. At the same heating power the bubble of HFE7500 whose contact angle is smaller grew faster and bigger, moved quickly on the heating surface, combined into center big bubble by colliding and reached its CHF earlier to film boiling. The bubble of distilled water whose contact angle is bigger didn't move obviously on heating surface, and it transferred from nucleate boiling to film boiling at its original place meanwhile it absorbed smaller bubble around. Key words: microgravity; bubble movement; contact angle; drop tower

  10. Effect of emergency FMD vaccine antigen payload on protection, sub-clinical infection and persistence following direct contact challenge of cattle.

    PubMed

    Cox, S J; Voyce, C; Parida, S; Reid, S M; Hamblin, P A; Hutchings, G; Paton, D J; Barnett, P V

    2006-04-12

    Previous work, in sheep vaccinated with emergency foot-and-mouth disease (FMD) vaccine, indicated the benefit of increasing the antigen payload in inhibiting local virus replication and consequently persistence following an indirect aerosol challenge with a virus homologous to the vaccine strain. The work presented here investigates this possibility further using cattle and a more severe semi-heterologous direct contact challenge. The quantitative dynamics of virus replication and excretion in both vaccinated and non-vaccinated cattle following challenge are examined. Two experiments were carried out each involving 20 vaccinated and 5 non-vaccinated cattle. An O(1) Manisa vaccine (18 PD(50)) was used for the first, previously reported experiment [Cox SJ, Voyce C, Parida S, Reid SM, Hamblin PA, Paton DJ, et al. Protection against direct contact challenge following emergency FMD vaccination of cattle and the effect on virus excretion from the oropharynx. Vaccine 2005;23:1106-13]. The same vaccine was used for the second experiment described in this paper except the antigen payload was increased 10-fold per bovine dose, resulting in significantly higher FMD virus neutralising antibody titres prior to challenge. Twenty-one days post-vaccination the cattle received a 5-day direct contact challenge with FMD virus from five further non-vaccinated cattle infected 24h earlier with O UKG 34/2001. All vaccinated cattle regardless of antigen payload were protected against clinical disease. Sub-clinical oropharyngeal infection was detected in animals from both experiments but the level of virus replication shortly after direct contact challenge was significantly reduced in vaccinated animals. Cattle immunised with the 10-fold antigen payload cleared the virus more readily and consequently at 28 days post-challenge fewer animals were persistently infected compared to the single strength vaccine. Following a severe challenge, the results from both experiments show that use of

  11. NUCLEAR SUPERHEATER FOR BOILING WATER REACTOR

    DOEpatents

    Holl, R.J.; Klecker, R.W.; Graham, C.B.

    1962-05-15

    A description is given of a boiling water reactor having a superheating region integral with the core. The core consists essentially of an annular boiling region surrounding an inner superheating region. Both regions contain fuel elements and are separated by a cylindrical wall, perforations being provided in the lower portion of the cylindrical wall to permit circulation of a common water moderator between the two regions. The superheater region comprises a plurality of tubular fuel assemblies through which the steam emanating from the boiling region passes to the steam outlet. Each superheater fuel assembly has an outer double-walled cylinder, the double walls being concentrically spaced and connected together at their upper ends but open at the bottom to provide for differential thermal expansion of the inner and outer walls. Gas is entrapped in the annulus between the walls which acts as an insulating space between the fissionable material inside and the moderator outside. (AEC)

  12. Axon terminals from the nucleus isthmi pars parvocellularis control the ascending retinotectofugal output through direct synaptic contact with tectal ganglion cell dendrites.

    PubMed

    González-Cabrera, Cristian; Garrido-Charad, Florencia; Mpodozis, Jorge; Bolam, J Paul; Marín, Gonzalo J

    2016-02-01

    The optic tectum in birds and its homologue the superior colliculus in mammals both send major bilateral, nontopographic projections to the nucleus rotundus and caudal pulvinar, respectively. These projections originate from widefield tectal ganglion cells (TGCs) located in layer 13 in the avian tectum and in the lower superficial layers in the mammalian colliculus. The TGCs characteristically have monostratified arrays of brush-like dendritic terminations and respond mostly to bidimensional motion or looming features. In birds, this TGC-mediated tectofugal output is controlled by feedback signals from the nucleus isthmi pars parvocellularis (Ipc). The Ipc neurons display topographically organized axons that densely ramify in restricted columnar terminal fields overlapping various neural elements that could mediate this tectofugal control, including the retinal terminals and the TGC dendrites themselves. Whether the Ipc axons make synaptic contact with these or other tectal neural elements remains undetermined. We double labeled Ipc axons and their presumptive postsynaptic targets in the tectum of chickens (Gallus gallus) with neural tracers and performed an ultrastructural analysis. We found that the Ipc terminal boutons form glomerulus-like structures in the superficial and intermediate tectal layers, establishing asymmetric synapses with several dendritic profiles. In these glomeruli, at least two of the postsynaptic dendrites originated from TGCs. We also found synaptic contacts between retinal terminals and TGC dendrites. These findings suggest that, in birds, Ipc axons control the ascending tectal outflow of retinal signals through direct synaptic contacts with the TGCs. © 2015 Wiley Periodicals, Inc.

  13. Direct contact with perivascular tumor cells enhances integrin αvβ3 signaling and migration of endothelial cells

    PubMed Central

    Burgett, Monica E.; Lathia, Justin D.; Roth, Patrick; Nowacki, Amy S.; Galileo, Deni S.; Pugacheva, Elena; Huang, Ping; Vasanji, Amit; Li, Meizhang; Byzova, Tatiana; Mikkelsen, Tom; Bao, Shideng; Rich, Jeremy N.; Weller, Michael; Gladson, Candece L.

    2016-01-01

    The secretion of soluble pro-angiogenic factors by tumor cells and stromal cells in the perivascular niche promotes the aggressive angiogenesis that is typical of glioblastoma (GBM). Here, we show that angiogenesis also can be promoted by a direct interaction between brain tumor cells, including tumor cells with cancer stem-like properties (CSCs), and endothelial cells (ECs). As shown in vitro, this direct interaction is mediated by binding of integrin αvβ3 expressed on ECs to the RGD-peptide in L1CAM expressed on CSCs. It promotes both EC network formation and enhances directed migration toward basic fibroblast growth factor. Activation of αvβ3 and bone marrow tyrosine kinase on chromosome X (BMX) is required for migration stimulated by direct binding but not for migration stimulated by soluble factors. RGD-peptide treatment of mice with established intracerebral GBM xenografts significantly reduced the percentage of Sox2-positive tumor cells and CSCs in close proximity to ECs, decreased integrin αvβ3 and BMX activation and p130CAS phosphorylation in the ECs, and reduced the vessel surface area. These results reveal a previously unrecognized aspect of the regulation of angiogenesis in GBM that can impact therapeutic anti-angiogenic targeting. PMID:27270311

  14. Direct evidence of phospholipids in gecko footprints and spatula-substrate contact interface detected using surface-sensitive spectroscopy.

    PubMed

    Hsu, Ping Yuan; Ge, Liehui; Li, Xiaopeng; Stark, Alyssa Y; Wesdemiotis, Chrys; Niewiarowski, Peter H; Dhinojwala, Ali

    2012-04-07

    Observers ranging from Aristotle to young children have long marvelled at the ability of geckos to cling to walls and ceilings. Detailed studies have revealed that geckos are 'sticky' without the use of glue or suction devices. Instead, a gecko's stickiness derives from van der Waals interactions between proteinaceous hairs called setae and substrate. Here, we present surprising evidence that although geckos do not use glue, a residue is transferred on surfaces as they walk-geckos leave footprints. Using matrix-free nano-assisted laser desorption-ionization mass spectrometry, we identified the residue as phospholipids with phosphocholine head groups. Moreover, interface-sensitive sum-frequency generation spectroscopy revealed predominantly hydrophobic methyl and methylene groups and the complete absence of water at the contact interface between a gecko toe pad and the substrate. The presence of lipids has never been considered in current models of gecko adhesion. Our analysis of gecko footprints and the toe pad-substrate interface has significant consequences for models of gecko adhesion and by extension, the design of synthetic mimics.

  15. Non-contact small animal fluorescence imaging system for simultaneous multi-directional angular-dependent data acquisition

    PubMed Central

    Lee, Jong Hwan; Kim, Hyun Keol; Chandhanayingyong, Chandhanarat; Lee, Francis Young-In; Hielscher, Andreas H.

    2014-01-01

    We present a novel non-contact small animal fluorescent molecular tomography (FMT) imaging system. At the heart of the system is a new mirror-based imaging head that was designed to provide 360-degree measurement data from an entire animal surface in one step. This imaging head consists of two conical mirrors, which considerably reduce multiple back reflections between the animal and mirror surfaces. These back reflections are common in existing mirror-based imaging heads and tend to degrade the quality of raw measurement data. In addition, the introduction of a novel ray-transfer operator allows for the inclusion of the angular dependent data in the image reconstruction process, which results in higher image resolution. We describe in detail the system design and implementation of the hardware components as well as the transport-theory-based image reconstruction algorithm. Using numerical simulations, measurements on a well-defined phantom and a live animal, we evaluate the system performance and show the advantages of our approach. PMID:25071965

  16. Non-contact small animal fluorescence imaging system for simultaneous multi-directional angular-dependent data acquisition.

    PubMed

    Lee, Jong Hwan; Kim, Hyun Keol; Chandhanayingyong, Chandhanarat; Lee, Francis Young-In; Hielscher, Andreas H

    2014-07-01

    We present a novel non-contact small animal fluorescent molecular tomography (FMT) imaging system. At the heart of the system is a new mirror-based imaging head that was designed to provide 360-degree measurement data from an entire animal surface in one step. This imaging head consists of two conical mirrors, which considerably reduce multiple back reflections between the animal and mirror surfaces. These back reflections are common in existing mirror-based imaging heads and tend to degrade the quality of raw measurement data. In addition, the introduction of a novel ray-transfer operator allows for the inclusion of the angular dependent data in the image reconstruction process, which results in higher image resolution. We describe in detail the system design and implementation of the hardware components as well as the transport-theory-based image reconstruction algorithm. Using numerical simulations, measurements on a well-defined phantom and a live animal, we evaluate the system performance and show the advantages of our approach.

  17. Boiling on Microconfigured Composite Surfaces Enhanced

    NASA Technical Reports Server (NTRS)

    Chao, David F.

    2000-01-01

    Boiling heat transfer is one of the key technologies for the two-phase active thermal-control system used on space platforms, as well as for the dynamic power systems aboard the International Space Station. Because it is an effective heat transfer mode, boiling is integral to many space applications, such as heat exchangers and other cooling devices. Nucleate boiling near the critical heat flux (CHF) can transport very large thermal loads with a much smaller device and much lower pumping power than for single-phase heat exchangers. However, boiling performance sharply deteriorates in a reduced-gravity environment, and operation in the CHF regime is somewhat perilous because of the risk of burnout to the device surface. New materials called microconfigured metal-graphite composites can enhance boiling. The photomicrograph shows the microconfiguration (x3000) of the copper-graphite (Cu-Gr) surface as viewed by scanning electronic microscope. The graphite fiber tips appear as plateaus with rugged surfaces embedded in the copper matrix. It has been experimentally demonstrated that this type of material manifests excellent boiling heat transfer performance characteristics and an increased CHF. Nonisothermal surfaces were less sensitive to variations of wall superheat in the CHF regime. Because of the great difference in conductivity between the copper base and the graphite fiber, the composite surfaces have a nonisothermal surface characteristic and, therefore, will have a much larger "safe" operating region in the CHF regime. In addition, the thermocapillary forces induced by the temperature differences between the fiber tips and the metal matrix play an important role in bubble detachment, and may not be adversely affected in a reduced-gravity environment. All these factors indicate that microconfigured composites may improve the reliability and economy (dominant factors in all space applications) of various thermal components found on spacecraft during future

  18. Experimental Investigation of Pool Boiling Heat Transfer Enhancement in Microgravity in the Presence of Electric Fields

    NASA Technical Reports Server (NTRS)

    Herman, Cila

    1996-01-01

    Boiling is an effective mode of heat transfer since high heat flux levels are possible driven by relatively small temperature differences. The high heat transfer coefficients associated with boiling have made the use of these processes increasingly attractive to aerospace engineering. Applications of this type include compact evaporators in the thermal control of aircraft avionics and spacecraft environments, heat pipes, and use of boiling to cool electronic equipment. In spite of its efficiency, cooling based on liquid-vapor phase change processes has not yet found wide application in aerospace engineering due to specific problems associated with the low gravity environment. After a heated surface has reached the superheat required for the initiation of nucleate boiling, bubbles will start forming at nucleation sites along the solid interface by evaporation of the liquid. Bubbles in contact with the wall will continue growing by this mechanism until they detach. In terrestrial conditions, bubble detachment is determined by the competition between body forces (e.g. buoyancy) and surface tension forces that act to anchor the bubble along the three phase contact line. For a given body force potential and a balance of tensions along the three phase contact line, bubbles must reach a critical size before the body force can cause them to detach from the wall. In a low gravity environment the critical bubble size for detachment is much larger than under terrestrial conditions, since buoyancy is a less effective means of bubble removal. Active techniques of heat transfer enhancement in single phase and phase change processes by utilizing electric fields have been the subject of intensive research during recent years. The field of electrohydrodynamics (EHD) deals with the interactions between electric fields, flow fields and temperature fields. Previous studies indicate that in terrestrial applications nucleate boiling heat transfer can be increased by a factor of 50 as

  19. Boiling as household water treatment in Cambodia: a longitudinal study of boiling practice and microbiological effectiveness.

    PubMed

    Brown, Joseph; Sobsey, Mark D

    2012-09-01

    This paper focuses on the consistency of use and microbiological effectiveness of boiling as it is practiced in one study site in peri-urban Cambodia. We followed 60 randomly selected households in Kandal Province over 6 months to collect longitudinal data on water boiling practices and effectiveness in reducing Escherichia coli in household drinking water. Despite > 90% of households reporting that they used boiling as a means of drinking water treatment, an average of only 31% of households had boiled water on hand at follow-up visits, suggesting that actual use may be lower than self-reported use. We collected 369 matched untreated and boiled water samples. Mean reduction of E. coli was 98.5%; 162 samples (44%) of boiled samples were free of E. coli (< 1 colony-forming unit [cfu]/100 mL), and 270 samples (73%) had < 10 cfu/100 mL. Storing boiled water in a covered container was associated with safer product water than storage in an uncovered container.

  20. Boiling as Household Water Treatment in Cambodia: A Longitudinal Study of Boiling Practice and Microbiological Effectiveness

    PubMed Central

    Brown, Joseph; Sobsey, Mark D.

    2012-01-01

    This paper focuses on the consistency of use and microbiological effectiveness of boiling as it is practiced in one study site in peri-urban Cambodia. We followed 60 randomly selected households in Kandal Province over 6 months to collect longitudinal data on water boiling practices and effectiveness in reducing Escherichia coli in household drinking water. Despite > 90% of households reporting that they used boiling as a means of drinking water treatment, an average of only 31% of households had boiled water on hand at follow-up visits, suggesting that actual use may be lower than self-reported use. We collected 369 matched untreated and boiled water samples. Mean reduction of E. coli was 98.5%; 162 samples (44%) of boiled samples were free of E. coli (< 1 colony-forming unit [cfu]/100 mL), and 270 samples (73%) had < 10 cfu/100 mL. Storing boiled water in a covered container was associated with safer product water than storage in an uncovered container. PMID:22826487

  1. Advances in shell side boiling of refrigerants

    NASA Astrophysics Data System (ADS)

    Webb, Ralph L.

    The design of shell and tube evaporators used in air conditioning and refrigeration applications is discussed. The heat exchanger geometry of interest involves evaporation or condensation on the shell side of a horizontal tube bundle. Enhanced heat transfer geometries are typically used for shell side evaporation and for forced convection to water on the tube side. Refrigerant boiling data and forced convection refrigerant boiling correlations are described. The refrigerants of interest include R-11, 12, 22, 123, and 134a. Thermal design methods for sizing of the evaporator and condenser are outlined. A computer model for prediction of the evaporator performance is described.

  2. The boiling point of stratospheric aerosols.

    NASA Technical Reports Server (NTRS)

    Rosen, J. M.

    1971-01-01

    A photoelectric particle counter was used for the measurement of aerosol boiling points. The operational principle involves raising the temperature of the aerosol by vigorously heating a portion of the intake tube. At or above the boiling point, the particles disintegrate rather quickly, and a noticeable effect on the size distribution and concentration is observed. Stratospheric aerosols appear to have the same volatility as a solution of 75% sulfuric acid. Chemical analysis of the aerosols indicates that there are other substances present, but that the sulfate radical is apparently the major constituent.

  3. Nucleate pool boiling of hydrocarbon mixtures

    SciTech Connect

    Sardesai, R.G.; Palen, J.W.; Thome, J.

    1986-01-01

    The Schlunder method can be correctly used to predict boiling heat transfer coefficient of multicomponent hydrocarbon mixtures. The method was tested against experimental mixtures containing up to five components. The Stephan-Abdelsalam correlation can be used to calculate a ''pseudo-single component'' boiling heat transfer coefficient for a mixture using weighted properties. The effective temperature driving force term and the high mass flux correction term in the Schlunder formulation are empirically adjusted to improve the accuracy of prediction. Predictions of the Schlunder method are sensitive to the VLE calculations. The UNIFAC method is used in this study for reasons discussed in the paper.

  4. BOILING SLURRY REACTOR AND METHOD FO CONTROL

    DOEpatents

    Petrick, M.; Marchaterre, J.F.

    1963-05-01

    The control of a boiling slurry nuclear reactor is described. The reactor consists of a vertical tube having an enlarged portion, a steam drum at the top of the vertical tube, and at least one downcomer connecting the steam drum and the bottom of the vertical tube, the reactor being filled with a slurry of fissionabie material in water of such concentration that the enlarged portion of the vertical tube contains a critical mass. The slurry boils in the vertical tube and circulates upwardly therein and downwardly in the downcomer. To control the reactor by controlling the circulation of the slurry, a gas is introduced into the downcomer. (AEC)

  5. Pool boiling of nanoparticle-modified surface with interlaced wettability

    PubMed Central

    2012-01-01

    This study investigated the pool boiling heat transfer under heating surfaces with various interlaced wettability. Nano-silica particles were used as the coating element to vary the interlaced wettability of the surface. The experimental results revealed that when the wettability of a surface is uniform, the critical heat flux increases with the more wettable surface; however, when the wettability of a surface is modified interlacedly, regardless of whether the modified region becomes more hydrophilic or hydrophobic, the critical heat flux is consistently higher than that of the isotropic surface. In addition, this study observed that critical heat flux was higher when the contact angle difference between the plain surface and the modified region was smaller. PMID:22607462

  6. Investigating the Dendritic Growth during Full Cell Cycling of Garnet Electrolyte in Direct Contact with Li Metal.

    PubMed

    Aguesse, Frederic; Manalastas, William; Buannic, Lucienne; Lopez Del Amo, Juan Miguel; Singh, Gurpreet; Llordés, Anna; Kilner, John

    2017-02-01

    All-solid-state batteries including a garnet ceramic as electrolyte are potential candidates to replace the currently used Li-ion technology, as they offer safer operation and higher energy storage performances. However, the development of ceramic electrolyte batteries faces several challenges at the electrode/electrolyte interfaces, which need to withstand high current densities to enable competing C-rates. In this work, we investigate the limits of the anode/electrolyte interface in a full cell that includes a Li-metal anode, LiFePO4 cathode, and garnet ceramic electrolyte. The addition of a liquid interfacial layer between the cathode and the ceramic electrolyte is found to be a prerequisite to achieve low interfacial resistance and to enable full use of the active material contained in the porous electrode. Reproducible and constant discharge capacities are extracted from the cathode active material during the first 20 cycles, revealing high efficiency of the garnet as electrolyte and the interfaces, but prolonged cycling leads to abrupt cell failure. By using a combination of structural and chemical characterization techniques, such as SEM and solid-state NMR, as well as electrochemical and impedance spectroscopy, it is demonstrated that a sudden impedance drop occurs in the cell due to the formation of metallic Li and its propagation within the ceramic electrolyte. This degradation process is originated at the interface between the Li-metal anode and the ceramic electrolyte layer and leads to electromechanical failure and cell short-circuit. Improvement of the performances is observed when cycling the full cell at 55 °C, as the Li-metal softening favors the interfacial contact. Various degradation mechanisms are proposed to explain this behavior.

  7. The dryout region in frictionally heated sliding contacts

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Braun, J.; Arp, V.; Giarratano, P. J.

    1982-01-01

    Some conditions under which boiling and two-phase flow can occur in or near a wet sliding contact are determined and illustrated. The experimental apparatus consisted of a tool pressed against an instrumented slider plate and motion picture sequences at 4000 frames/sec. The temperature and photographic data demonstrated surface conditions of boiling, drying, trapped gas evolution (solutions), and volatility of fluid mixture components. The theoretical modeling and analysis are in reasonable agreement with experimental data.

  8. Composition, diffusion, and antifungal activity of black mustard (Brassica nigra) essential oil when applied by direct addition or vapor phase contact.

    PubMed

    Mejía-Garibay, Beatriz; Palou, Enrique; López-Malo, Aurelio

    2015-04-01

    In this study, we characterized the essential oil (EO) of black mustard (Brassica nigra) and quantified its antimicrobial activity, when applied by direct contact into the liquid medium or by exposure in the vapor phase (in laboratory media or in a bread-type product), against the growth of Aspergillus niger, Aspergillus ochraceus, or Penicillium citrinum. Allyl-isothiocyanate (AITC) was identified as the major component of B. nigra EO with a concentration of 378.35 mg/ml. When B. nigra EO was applied by direct contact into the liquid medium, it inhibited the growth of A. ochraceus and P. citrinum when the concentration was 2 μl/ml of liquid medium (MIC), while for A. niger, a MIC of B. nigra EO was 4 μl/ml of liquid medium. Exposure of molds to B. nigra EO in vapor phase showed that 41.1 μl of B. nigra EO per liter of air delayed the growth of P. citrinum and A. niger by 10 days, while A. ochraceus growth was delayed for 20 days. Exposure to concentrations ≥ 47 μl of B. nigra EO per liter of air (MIC) inhibited the growth of tested molds by 30 days, and they were not able to recover after further incubation into an environment free of EO (fungicidal effect). Adsorbed AITC was quantified by exposing potato dextrose agar to B. nigra EO in a vapor phase, exhibiting that AITC was retained at least 5 days when testing EO at its MIC or with higher concentrations. Mustard EO MIC was also effective against the evaluated molds inhibiting their growth for 30 days in a bread-type product when exposed to EO by vapor contact, demonstrating its antifungal activity.

  9. Contact hysteroscopy.

    PubMed

    Baggish, M S; Barbot, J

    1983-06-01

    the menstrual cycle may be identified on the basis of the endometrial pattern. This pattern diagnosis is dependent on color, contour, and physical adhesiveness of the tissue. Cervical intraepithelial neoplasia (CIN) is the most common neoplastic lesion of the cervix. When atypical epithelium extends into the cervical canal beyond the view of the colposcope, the 6 mm contact hysteroscope has been helpful in determining the extent and severity of the lesion as well as to direct biopsy equipment to the site of the pathologic condition.

  10. An Investigation of Graduate Scientists' Understandings of Evaporation and Boiling.

    ERIC Educational Resources Information Center

    Goodwin, Alan; Orlik, Yuri

    2000-01-01

    Uses a video presentation of six situations relating to the evaporation and boiling of liquids and the escape of dissolved gases from solution and investigates graduate scientists' understanding of the concepts of boiling and evaporation. (Author/YDS)

  11. An Investigation of Graduate Scientists' Understandings of Evaporation and Boiling.

    ERIC Educational Resources Information Center

    Goodwin, Alan; Orlik, Yuri

    2000-01-01

    Uses a video presentation of six situations relating to the evaporation and boiling of liquids and the escape of dissolved gases from solution and investigates graduate scientists' understanding of the concepts of boiling and evaporation. (Author/YDS)

  12. Direct and quantitative AFM measurements of the concentration and temperature dependence of the hydrophobic force law at nanoscopic contacts.

    PubMed

    Stock, Philipp; Utzig, Thomas; Valtiner, Markus

    2015-05-15

    By virtue of its importance for self-organization of biological matter the hydrophobic force law and the range of hydrophobic interactions (HI) have been debated extensively over the last 40 years. Here, we directly measure and quantify the hydrophobic force-distance law over large temperature and concentration ranges. In particular, we study the HI between molecularly smooth hydrophobic self-assembled monolayers, and similarly modified gold-coated AFM tips (radii∼8-50 nm). We present quantitative and direct evidence that the hydrophobic force is both long-ranged and exponential down to distances of about 1-2 nm. Therefore, we introduce a self-consistent radius-normalization for atomic force microscopy data. This approach allows quantitative data fitting of AFM-based experimental data to the recently proposed Hydra-model. With a statistical significance of r(2)⩾0.96 our fitting and data directly reveal an exponential HI decay length of 7.2±1.2 Å that is independent of the salt concentration up to 750 mM. As such, electrostatic screening does not have a significant influence on the HI in electrolyte concentrations ranging from 1 mM to 750 mM. In 1 M solutions the observed instability during approach shifts to longer distances, indicating ion correlation/adsorption effects at high salt concentrations. With increasing temperature the magnitude of HI decreases monotonically, while the range increases slightly. We compare our results to the large body of available literature, and shed new light into range and magnitude of hydrophobic interactions at very close distances and over wide temperature and concentration regimes. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Cryogenic Propellant Boil-Off Reduction System

    NASA Astrophysics Data System (ADS)

    Plachta, D. W.; Christie, R. J.; Carlberg, E.; Feller, J. R.

    2008-03-01

    Lunar missions under consideration would benefit from incorporation of high specific impulse propellants such as LH2 and LO2, even with their accompanying boil-off losses necessary to maintain a steady tank pressure. This paper addresses a cryogenic propellant boil-off reduction system to minimize or eliminate boil-off. Concepts to do so were considered under the In-Space Cryogenic Propellant Depot Project. Specific to that was an investigation of cryocooler integration concepts for relatively large depot sized propellant tanks. One concept proved promising—it served to efficiently move heat to the cryocooler even over long distances via a compressed helium loop. The analyses and designs for this were incorporated into NASA Glenn Research Center's Cryogenic Analysis Tool. That design approach is explained and shown herein. Analysis shows that, when compared to passive only cryogenic storage, the boil-off reduction system begins to reduce system mass if durations are as low as 40 days for LH2, and 14 days for LO2. In addition, a method of cooling LH2 tanks is presented that precludes development issues associated with LH2 temperature cryocoolers.

  14. Cryogenic Boil-Off Reduction System Testing

    NASA Technical Reports Server (NTRS)

    Plachta, David W.; Johnson, Wesley L.; Feller, Jeffery

    2014-01-01

    The Cryogenic Boil-Off Reduction System was tested with LH2 and LOX in a vacuum chamber to simulate space vacuum and the temperatures of low Earth orbit. Testing was successful and results validated the scaling study model that predicts active cooling reduces upper stage cryogenic propulsion mass for loiter periods greater than 2 weeks.

  15. Electrically Driven Liquid Film Boiling Experiment

    NASA Technical Reports Server (NTRS)

    Didion, Jeffrey R.

    2016-01-01

    This presentation presents the science background and ground based results that form the basis of the Electrically Driven Liquid Film Boiling Experiment. This is an ISS experiment that is manifested for 2021. Objective: Characterize the effects of gravity on the interaction of electric and flow fields in the presence of phase change specifically pertaining to: a) The effects of microgravity on the electrically generated two-phase flow. b) The effects of microgravity on electrically driven liquid film boiling (includes extreme heat fluxes). Electro-wetting of the boiling section will repel the bubbles away from the heated surface in microgravity environment. Relevance/Impact: Provides phenomenological foundation for the development of electric field based two-phase thermal management systems leveraging EHD, permitting optimization of heat transfer surface area to volume ratios as well as achievement of high heat transfer coefficients thus resulting in system mass and volume savings. EHD replaces buoyancy or flow driven bubble removal from heated surface. Development Approach: Conduct preliminary experiments in low gravity and ground-based facilities to refine technique and obtain preliminary data for model development. ISS environment required to characterize electro-wetting effect on nucleate boiling and CHF in the absence of gravity. Will operate in the FIR - designed for autonomous operation.

  16. Boiling heat transfer characteristics of liquid xenon

    NASA Astrophysics Data System (ADS)

    Haruyama, T.

    2002-05-01

    Liquid xenon is one of the excellent media for high-energy particle calorimeter. In order to detect a scintillation light effectively, a large number of photo-multipliers (PMTs) will be immersed in liquid xenon. Many chip-resistors equipped with the PMTs dissipate heat into liquid and possibly generate thermal turbulence, such as bubbles, convection flow under a certain operating condition. There is, however, no heat transfer curve (q-ΔT curve) in the literature. Boiling heat transfer characteristics of liquid xenon were measured at a saturated pressure of 0.1 MPa for the first time by using a small pulse tube refrigerator. The heat transfer surface is a thin platinum wire of 0.1 mm diameter and 25 mm long. The measured results were in good agreement with the calculated values both in natural convection and nucleate boiling condition. The film boiling state was difficult to obtain due to its poor reproducibility, and only one data was obtained. The relationship between the heat flux q and temperature difference ΔT was in good agreement with the Morgan's empirical equation in the natural convection region, and with the Kutateladze's equation in the nucleate boiling region.

  17. Big Bubbles in Boiling Liquids: Students' Views

    ERIC Educational Resources Information Center

    Costu, Bayram

    2008-01-01

    The aim of this study was to elicit students' conceptions about big bubbles in boiling liquids (water, ethanol and aqueous CuSO[subscript 4] solution). The study is based on twenty-four students at different ages and grades. The clinical interviews technique was conducted to solicit students' conceptions and the interviews were analyzed to…

  18. The Plausibility of Boiling Geysers on Triton

    NASA Technical Reports Server (NTRS)

    Duxbury, N. S.; Brown, R. H.

    1995-01-01

    A mechanism is suggested and modeled whereby there may be boiling geysers on Triton. The geysers would be of nitrogen considering that Voyager detected cryovolcanic activity, that solid nitrogen conducts heat much less than water ice, and that there is internal heat on Triton.

  19. Big Bubbles in Boiling Liquids: Students' Views

    ERIC Educational Resources Information Center

    Costu, Bayram

    2008-01-01

    The aim of this study was to elicit students' conceptions about big bubbles in boiling liquids (water, ethanol and aqueous CuSO[subscript 4] solution). The study is based on twenty-four students at different ages and grades. The clinical interviews technique was conducted to solicit students' conceptions and the interviews were analyzed to…

  20. Electrohydrodynamic Pool Boiling in Reduced Gravity

    NASA Technical Reports Server (NTRS)

    Shaw, Benjamin D.; Stahl, S. L.

    1996-01-01

    This research is concerned with studying the effects of applied electric fields on pool boiling in a reduced-gravity environment. Experiments are conducted at the NASA Lewis 2.2 sec Drop tower using a drop rig constructed at UC Davis. In the experiments, a platinum wire is heated while immersed in saturated liquid refrigerants (FC-72 and FC-87), or water, causing vapor formation at the wire surface. Electric fields are applied between the wire surface and an outer screen electrode that surrounds the wire. Preliminary normal-gravity experiments with water have demonstrated that applied electric fields generated by the rig electronics can influence boiling characteristics. Reduced-gravity experiments will be performed in the summer of 1996. The experiments will provide fundamental data on electric field strengths required to disrupt film boiling (for various wire heat generation input rates) in reduced gravity for a cylindrical geometry. The experiments should also shed light on the roles of characteristic bubble generation times and charge relaxation times in determining the effects of electric fields on pool boiling. Normal-gravity comparison experiments will also be performed.

  1. Contact hole multiplication using grapho-epitaxy directed self-assembly: process choices, template optimization, and placement accuracy

    NASA Astrophysics Data System (ADS)

    Bekaert, Joost; Doise, Jan; Murugesan Kuppuswamy, Vijaya-Kumar; Gronheid, Roel; Chan, Boon Teik; Vandenberghe, Geert; Cao, Yi; Her, YoungJun

    2014-10-01

    Directed Self Assembly (DSA) of Block Co-Polymers (BCP) has become an intense field of study as a potential patterning solution for future generation devices. The most critical challenges that need to be understood and controlled include pattern placement accuracy, achieving low defectivity in DSA patterns and how to implement this process as a patterning solution. The DSA program at imec includes efforts on these three major topics. Specifically, in this paper the progress for the templated DSA flow within the imec program will be discussed. An experimental assessment is made based on a 37 nm BCP pitch material. In particular, the impact of different process options is illustrated, and data for CD and placement accuracy of the DSA holes in their template is provided.

  2. Direct contacts with colon cancer cells regulate the differentiation of bone marrow mesenchymal stem cells into tumor associated fibroblasts.

    PubMed

    Peng, Yanan; Li, Zongwei; Yang, Peng; Newton, Ian P; Ren, Hua; Zhang, Lichao; Wu, Haili; Li, Zhuoyu

    2014-08-15

    Tumor-stroma interactions are referred to as essential events in tumor progression. There has been growing attention that bone marrow-derived mesenchymal stem cells (BMSCs) can travel to tumor stroma, where they differentiate into tumor-associated fibroblast (TAF)-like cells, a predominant tumor-promoting stromal cell. However, little is definitively known about the contributors for this transition. Here, using an in vitro direct co-culture model of colon cancer cells and BMSCs, we identify that colon cancer cells can induce adjoining BMSCs to exhibit the typical characteristic of TAFs, with increased expression of α-smooth muscle actin (α-SMA). Importantly, the present data also reveals that activated Notch signaling mediates transformation of BMSCs to TAFs through the downstream TGF-β/Smad signaling pathway.

  3. A new regime of nucleate boiling in microsphere mesostructures: Jumping pool boiling

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. S.; Makarov, P. G.; El Bouz, M. A.

    2015-03-01

    We have studied a new regime of nucleate boiling in distilled water on substrates representing mesostructures of monodisperse and/or polydisperse microspheres made of various materials. It is experimentally established that, under some conditions of nucleate boiling, there appear "jumping pool boiling" regimes in which bubbles do not reach the surface of underheated liquid. In addition, bubbles may capture a certain number of microspheres, lift them up to some height, and then sink together down to the vessel bottom. Alternatively, microspheres may trap a certain number of bubbles, float up toward the evaporating surface, and then (without reaching the surface) sink back to the bottom layer where the nucleate bubbling takes place. Subregimes of this boiling mechanism involving microspheres of various densities and dimensions have also been observed.

  4. 21 CFR 872.6710 - Boiling water sterilizer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Boiling water sterilizer. 872.6710 Section 872.6710 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6710 Boiling water sterilizer. (a) Identification. A boiling water sterilizer is an...

  5. Cryogenic Boil-Off Reduction System Testing

    NASA Technical Reports Server (NTRS)

    Plachta, David W.; Johnson, Wesley L.; Feller, Jeffrey R.

    2014-01-01

    Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASA's future space exploration due to the high specific impulse that can be achieved using engines suitable for moving 10's to 100's of metric tons of payload mass to destinations outside of low earth orbit. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several days. The losses can be greatly reduced by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and by the integration of self-supporting multi-layer insulation. The active thermal control technology under development is the integration of the reverse turbo- Brayton cycle cryocooler to the propellant tank through a distributed cooling network of tubes coupled to a shield in the tank insulation and to the tank wall itself. Also, the self-supporting insulation technology was utilized under the shield to obtain needed tank applied LH2 performance. These elements were recently tested at NASA Glenn Research Center in a series of three tests, two that reduced LH2 boil-off and one to eliminate LO2 boil-off. This test series was conducted in a vacuum chamber that replicated the vacuum of space and the temperatures of low Earth orbit. The test results show that LH2 boil-off was reduced 60% by the cryocooler system operating at 90K and that robust LO2 zero boil-off storage, including full tank pressure control was achieved.

  6. Estimation of boiling points using density functional theory with polarized continuum model solvent corrections.

    PubMed

    Chan, Poh Yin; Tong, Chi Ming; Durrant, Marcus C

    2011-09-01

    An empirical method for estimation of the boiling points of organic molecules based on density functional theory (DFT) calculations with polarized continuum model (PCM) solvent corrections has been developed. The boiling points are calculated as the sum of three contributions. The first term is calculated directly from the structural formula of the molecule, and is related to its effective surface area. The second is a measure of the electronic interactions between molecules, based on the DFT-PCM solvation energy, and the third is employed only for planar aromatic molecules. The method is applicable to a very diverse range of organic molecules, with normal boiling points in the range of -50 to 500 °C, and includes ten different elements (C, H, Br, Cl, F, N, O, P, S and Si). Plots of observed versus calculated boiling points gave R²=0.980 for a training set of 317 molecules, and R²=0.979 for a test set of 74 molecules. The role of intramolecular hydrogen bonding in lowering the boiling points of certain molecules is quantitatively discussed.

  7. Analysis and Measurement of Bubble Dynamics and Associated Flow Field in Subcooled Nucleate Boiling Flows

    SciTech Connect

    Barclay G. Jones

    2008-10-01

    In recent years, subooled nucleate boiling (SNB) has attrcted expanding research interest owing to the emergence of axial offset anomaly (AOA) or crud-induced power shigt (CIPS) in many operating US PWRs, which is an unexpected deviation in the core axial power distribution from the predicted power curves. Research indicates that the formation of the crud, which directly leads to AOA phenomena, results from the presence of the subcooled nucleate boiling, and is especially realted to bubble motion occurring in the core region.

  8. High Frequency Stable Oscillate boiling

    NASA Astrophysics Data System (ADS)

    Li, Fenfang; Gonzalez-Avila, Silvestre Roberto; Ohl, Claus Dieter

    2015-11-01

    We present an unexpected regime of resonant bubble oscillations on a thin metal film submerged in water, which is continuously heated with a focused CW laser. The oscillatory bubble dynamics reveals a remarkably stable frequency of several 100 kHz and is resolved from the side using video recordings at 1 million frames per second. The emitted sound is measured simultaneously and shows higher harmonics. Once the laser is switched on the water in contact with the metal layer is superheated and an explosively expanding cavitation bubble is generated. However, after the collapse a microbubble is nucleated from the bubble remains which displays long lasting oscillations. Generally, pinch-off from of the upper part of the microbubble is observed generating a continuous stream of small gas bubbles rising upwards. The cavitation expansion, collapse, and the jetting of gas bubbles are detected by the hydrophone and are correlated to the high speed video. We find the bubble oscillation frequency is dependent on the bubble size and surface tension. A preliminary model based on Marangoni flow and heat transfer can explain the high flow velocities observed, yet the origin of bubble oscillation is currently not well understood.

  9. Guanosine 2-NH2 groups of Escherichia coli RNase P RNA involved in intramolecular tertiary contacts and direct interactions with tRNA.

    PubMed Central

    Heide, C; Pfeiffer, T; Nolan, J M; Hartmann, R K

    1999-01-01

    We have identified by nucleotide analog interference mapping (NAIM) exocyclic NH2 groups of guanosines in RNase P RNA from Escherichia coli that are important for tRNA binding. The majority of affected guanosines represent phylogenetically conserved nucleotides. Several sites of interference could be assigned to direct contacts with the tRNA moiety, whereas others were interpreted as reflecting indirect effects on tRNA binding due to the disruption of tertiary contacts within the catalytic RNA. Our results support the involvement of the 2-NH2 groups of G292/G293 in pairing with C74 and C75 of tRNA CCA-termini, as well as formation of two consecutive base triples involving C75 and A76 of CCA-ends interacting with G292/A258 and G291/G259, respectively. Moreover, we present first biochemical evidence for two tertiary contacts (L18/P8 and L8/P4) within the catalytic RNA, whose formation has been postulated previously on the basis of phylogenetic comparative analyses. The tRNA binding interference data obtained in this and our previous studies are consistent with the formation of a consecutive nucleotide triple and quadruple between the tetraloop L18 and helix P8. Formation of the nucleotide triple (G316 and A94:U104 in wild-type E. coli RNase P RNA) is also supported by mutational analysis. For the mutant RNase P RNA carrying a G94:C104 double mutation, an additional G316-to-A mutation resulted in a restoration of binding affinity for mature and precursor tRNA. PMID:9917070

  10. γ-Aminobutyric Acid Type A (GABAA) Receptor Subunits Play a Direct Structural Role in Synaptic Contact Formation via Their N-terminal Extracellular Domains*

    PubMed Central

    Brown, Laura E.; Nicholson, Martin W.; Arama, Jessica E.; Thomson, Alex M.

    2016-01-01

    The establishment of cell-cell contacts between presynaptic GABAergic neurons and their postsynaptic targets initiates the process of GABAergic synapse formation. GABAA receptors (GABAARs), the main postsynaptic receptors for GABA, have been recently demonstrated to act as synaptogenic proteins that can single-handedly induce the formation and functional maturation of inhibitory synapses. To establish how the subunit composition of GABAARs influences their ability to induce synaptogenesis, a co-culture model system incorporating GABAergic medium spiny neurons and the HEK293 cells, stably expressing different combinations of receptor subunits, was developed. Analyses of HEK293 cell innervation by medium spiny neuron axons using immunocytochemistry, activity-dependent labeling, and electrophysiology have indicated that the γ2 subunit is required for the formation of active synapses and that its effects are influenced by the type of α/β subunits incorporated into the functional receptor. To further characterize this process, the large N-terminal extracellular domains (ECDs) of α1, α2, β2, and γ2 subunits were purified using the baculovirus/Sf9 cell system. When these proteins were applied to the co-cultures of MSNs and α1/β2/γ2-expressing HEK293 cells, the α1, β2, or γ2 ECD each caused a significant reduction in contact formation, in contrast to the α2 ECD, which had no effect. Together, our experiments indicate that the structural role of GABAARs in synaptic contact formation is determined by their subunit composition, with the N-terminal ECDs of each of the subunits directly participating in interactions between the presynaptic and postsynaptic elements, suggesting the these interactions are multivalent and specific. PMID:27129275

  11. Performance of Hepatitis E Virus (HEV)-antibody tests: a comparative analysis based on samples from individuals with direct contact to domestic pigs or wild boar in Germany.

    PubMed

    Sommerkorn, Frauke Mara; Schauer, Birgit; Schreiner, Thomas; Fickenscher, Helmut; Krumbholz, Andi

    2017-04-10

    In Europe, Hepatitis E virus (HEV) genotype 3 causes most human infections, and domestic pigs and wild boar represent the main reservoirs. Contact to these animals represents one source of human infection. However, interpretation of studies is challenged in the absence of a serological gold standard. Hence, this study compared results of different HEV immunoassays. Plasma samples from 139 individuals who had professional contact to pigs (veterinarians, meat inspectors, slaughterhouse workers; n = 114) or hunted regularly (n = 25) were tested with assays specific for HEV IgG, HEV IgM, HEV IgA, and total HEV immunoglobulin as well as for viral RNA. Furthermore, overall HEV IgG was defined (i.e., two of three IgG assays reveal the same result) to compare serological findings. Borderline results were always quoted as positive. For IgG, apparent prevalence was higher in Wantai (48.2%) compared to Euroimmun (11.5%) and Mikrogen assays (17.3%) (p = 0.0001). The overall IgG prevalence was estimated to be 18.7%. For total Ig, Wantai (40.3%) also yielded higher prevalence than Euroimmun (15.8%) (p = 0.0001). The HEV IgM prevalence ranged from 0% (Euroimmun) to 4.3% (Mikrogen). Four percent of individuals tested IgA positive, whilst none harboured HEV RNA. Our results support previous studies that the higher IgG prevalence estimated with the Wantai assay result from a higher sensitivity of this test. However, further studies are needed to verify specificity given the challenge of defining true negative samples. The high percentage of individuals with HEV IgG observed in this study underlines that direct contact to pigs represents a risk factor for HEV infection.

  12. Nucleate boiling performance on nano/microstructures with different wetting surfaces

    NASA Astrophysics Data System (ADS)

    Jo, HangJin; Kim, SeolHa; Kim, Hyungmo; Kim, Joonwon; Kim, Moo Hwan

    2012-05-01

    A study of nucleate boiling phenomena on nano/microstructures is a very basic and useful study with a view to the potential application of modified surfaces as heating surfaces in a number of fields. We present a detailed study of boiling experiments on fabricated nano/microstructured surfaces used as heating surfaces under atmospheric conditions, employing identical nanostructures with two different wettabilities (silicon-oxidized and Teflon-coated). Consequently, enhancements of both boiling heat transfer (BHT) and critical heat flux (CHF) are demonstrated in the nano/microstructures, independent of their wettability. However, the increment of BHT and CHF on each of the different wetting surfaces depended on the wetting characteristics of heating surfaces. The effect of water penetration in the surface structures by capillary phenomena is suggested as a plausible mechanism for the enhanced CHF on the nano/microstructures regardless of the wettability of the surfaces in atmospheric condition. This is supported by comparing bubble shapes generated in actual boiling experiments and dynamic contact angles under atmospheric conditions on Teflon-coated nano/microstructured surfaces.

  13. Nucleate boiling performance on nano/microstructures with different wetting surfaces

    PubMed Central

    2012-01-01

    A study of nucleate boiling phenomena on nano/microstructures is a very basic and useful study with a view to the potential application of modified surfaces as heating surfaces in a number of fields. We present a detailed study of boiling experiments on fabricated nano/microstructured surfaces used as heating surfaces under atmospheric conditions, employing identical nanostructures with two different wettabilities (silicon-oxidized and Teflon-coated). Consequently, enhancements of both boiling heat transfer (BHT) and critical heat flux (CHF) are demonstrated in the nano/microstructures, independent of their wettability. However, the increment of BHT and CHF on each of the different wetting surfaces depended on the wetting characteristics of heating surfaces. The effect of water penetration in the surface structures by capillary phenomena is suggested as a plausible mechanism for the enhanced CHF on the nano/microstructures regardless of the wettability of the surfaces in atmospheric condition. This is supported by comparing bubble shapes generated in actual boiling experiments and dynamic contact angles under atmospheric conditions on Teflon-coated nano/microstructured surfaces. PMID:22559173

  14. Nucleate boiling performance on nano/microstructures with different wetting surfaces.

    PubMed

    Jo, Hangjin; Kim, Seolha; Kim, Hyungmo; Kim, Joonwon; Kim, Moo Hwan

    2012-05-06

    A study of nucleate boiling phenomena on nano/microstructures is a very basic and useful study with a view to the potential application of modified surfaces as heating surfaces in a number of fields. We present a detailed study of boiling experiments on fabricated nano/microstructured surfaces used as heating surfaces under atmospheric conditions, employing identical nanostructures with two different wettabilities (silicon-oxidized and Teflon-coated). Consequently, enhancements of both boiling heat transfer (BHT) and critical heat flux (CHF) are demonstrated in the nano/microstructures, independent of their wettability. However, the increment of BHT and CHF on each of the different wetting surfaces depended on the wetting characteristics of heating surfaces. The effect of water penetration in the surface structures by capillary phenomena is suggested as a plausible mechanism for the enhanced CHF on the nano/microstructures regardless of the wettability of the surfaces in atmospheric condition. This is supported by comparing bubble shapes generated in actual boiling experiments and dynamic contact angles under atmospheric conditions on Teflon-coated nano/microstructured surfaces.

  15. Contact allergy to the 26 specific fragrance ingredients to be declared on cosmetic products in accordance with the EU cosmetics directive.

    PubMed

    Heisterberg, Maria V; Menné, Torkil; Johansen, Jeanne D

    2011-11-01

    Fragrance ingredients are a frequent cause of allergic contact dermatitis. The EU Cosmetics Directive states that 26 specific fragrance ingredients, known to cause allergic contact dermatitis, must be declared on the ingredient lists of cosmetic products. To investigate frequencies of sensitization to the 26 individual fragrances and evaluate their importance as screening markers of fragrance allergy. This was a retrospective study based on data from the Department of Dermato-Allergology, Copenhagen University Hospital Gentofte. Eczema patients (n = 1508) were patch tested (January 2008 to July 2010) with the 26 fragrance ingredients. Sensitization to the 26 fragrances was identified in 115 (7.6%) subjects. The most frequent allergens were Evernia furfuracea (n = 50), Evernia prunastri (n = 31), and hydroxyisohexyl 3-cyclohexene carboxaldehyde (n = 24). Including fragrance mix I, fragrance mix II and Myroxylon pereirae, 196 (13.0%) had a fragrance allergy. Testing with the 26 fragrances additionally identified 23 subjects who would otherwise have gone undetected. The majority (75.7%) of positive reactions to the 26 fragrances were of clinical relevance. Sensitization to the 26 individual fragrance ingredients was identified in 7.6% of the subjects patch tested. Most reactions were of clinical relevance. Fragrance-allergic subjects would be missed if testing with the individual fragrance ingredients was not performed. © 2011 John Wiley & Sons A/S.

  16. Pathogenesis of highly virulent African swine fever virus in domestic pigs exposed via intraoropharyngeal, intranasopharyngeal, and intramuscular inoculation, and by direct contact with infected pigs.

    PubMed

    Howey, Erin B; O'Donnell, Vivian; de Carvalho Ferreira, Helena C; Borca, Manuel V; Arzt, Jonathan

    2013-12-26

    To investigate the pathogenesis of African swine fever virus (ASFV), domestic pigs (n=18) were challenged with a range (10(2)-10(6) 50% hemadsorbing doses (HAD50)) of the highly virulent ASFV-Malawi strain by inoculation via the intraoropharyngeal (IOP), intranasopharyngeal (INP), or intramuscular (IM) routes. A subsequent contact challenge experiment was performed in which six IOP-inoculated donor pigs were allowed to have direct contact (DC) with six naïve pigs for exposure times that varied from 24 to 72 h. All challenge routes resulted in clinical progression and postmortem lesions similar to those previously described in experimental and natural infection. The onset of clinical signs occurred between 1 and 7 days post inoculation (dpi) and included pyrexia with variable progression to obtundation, hematochezia, melena, moribundity and death with a duration of 4-11 days. Viremia was first detected between 4 and 5 dpi in all inoculation groups whereas ASFV shedding from the nasal cavity and tonsil was first detected at 3-9 dpi. IM and DC were the most consistent modes of infection, with 12/12 (100%) of pigs challenged by these routes becoming infected. Several clinical and virological parameters were significantly different between IM and DC groups indicating dissimilarity between these modes of infection. Amongst the simulated natural routes, INP inoculation resulted in the most consistent progression of disease across the widest range of doses whilst preserving simulation of natural exposure and therefore may provide a superior system for pathogenesis and vaccine efficacy investigation.

  17. Linearizing the joint torque characteristics of an electric direct-drive robot for high performance control of in-contact operations

    SciTech Connect

    Muir, P.F.

    1992-01-01

    Many robot control algorithms for high performance in-contact operations including hybrid force/position, stiffness control and impedance control approaches require the command of the joint torques. However, most commercially available robots do not provide joint torque command capabilities. The joint command at the user level is typically position or velocity and at the control developer level is voltage current, or pulse-width, and the torque generated is a nonlinear function of the command and joint position. To enable the application of high performance in-contact control algorithms to commercially available robots, and thereby facilitate technology transfer from the robot control research community to commercial applications, a practical methodology has been developed to linearize the torque characteristics of electric motor-amplifier combinations. A four degree-of-freedom Adept 2 robot, having pulse-width modulation amplifiers and both variable reluctance and brushless DC motors, is converted to operate from joint torque commands to demonstrate the methodology. The average percentage torque deviation over the command and position ranges is reduced from as much as 76% to below 5% for the direct-drive joints 1, 2 and 4 and is cut by one half in the remaining ball-screw driven joint 3. 16 refs., 16 figs., 2 tabs.

  18. Phage φ29 Regulatory Protein p4 Stabilizes the Binding of the RNA Polymerase to the Late Promoter in a Process Involving Direct Protein-Protein Contacts

    NASA Astrophysics Data System (ADS)

    Nuez, Beatriz; Rojo, Fernando; Salas, Margarita

    1992-12-01

    Transcription from the late promoter, PA3, of Bacillus subtilis phage φ29 is activated by the viral regulatory protein p4. A kinetic analysis of the activation process has revealed that the role of protein p4 is to stabilize the binding of RNA polymerase to the promoter as a closed complex without significantly affecting further steps of the initiation process. Electrophoretic band-shift assays performed with a DNA fragment spanning only the protein p4 binding site showed that RNA polymerase could efficiently retard the complex formed by protein p4 bound to the DNA. Similarly, when a DNA fragment containing only the RNA polymerase-binding region of PA3 was used, p4 greatly stimulated the binding of RNA polymerase to the DNA. These results strongly suggest that p4 and RNA polymerase contact each other at the PA3 promoter. In the light of current knowledge of the p4 activation mechanism, we propose that direct contacts between the two proteins participate in the activation process.

  19. Alanine scanning site-directed mutagenesis of the zinc fingers of transcription factor ADR1: residues that contact DNA and that transactivate.

    PubMed Central

    Thukral, S K; Morrison, M L; Young, E T

    1991-01-01

    To identify functionally important amino acids in the two zinc fingers of transcription factor ADR1 [alcohol dehydrogenase (ADH) II synthesis regulator], oligonucleotide-directed mutagenesis was used to substitute alanine for the original amino acid at each position in both fingers. The effects of these mutations on DNA binding and thermal stability of ADR1 in vitro and on activation of ADH2 expression in vivo were measured. The DNA binding activity was remarkably heatstable. Amino acids that are candidates for DNA contact sites were identified in the finger-tip and alpha-helical region of each finger, three in the first finger and two in the second. Unexpectedly, an acidic residue in the first finger was essential for transactivation, but its replacement by alanine had no effect on DNA binding. Substitution at several highly conserved positions did not affect ADR1 functions. The ADR1 zinc fingers appear to make relatively few energetically significant contacts to DNA, perhaps as few as three in the first finger and one in the second. Images PMID:1924382

  20. Phage phi 29 regulatory protein p4 stabilizes the binding of the RNA polymerase to the late promoter in a process involving direct protein-protein contacts.

    PubMed

    Nuez, B; Rojo, F; Salas, M

    1992-12-01

    Transcription from the late promoter, PA3, of Bacillus subtilis phage phi 29 is activated by the viral regulatory protein p4. A kinetic analysis of the activation process has revealed that the role of protein p4 is to stabilize the binding of RNA polymerase to the promoter as a closed complex without significantly affecting further steps of the initiation process. Electrophoretic band-shift assays performed with a DNA fragment spanning only the protein p4 binding site showed that RNA polymerase could efficiently retard the complex formed by protein p4 bound to the DNA. Similarly, when a DNA fragment containing only the RNA polymerase-binding region of PA3 was used, p4 greatly stimulated the binding of RNA polymerase to the DNA. These results strongly suggest that p4 and RNA polymerase contact each other at the PA3 promoter. In the light of current knowledge of the p4 activation mechanism, we propose that direct contacts between the two proteins participate in the activation process.

  1. Direct contact liquid-liquid heat exchanger for solar heated and cooled buildings. Final report, January 1, 1979-May 30, 1980

    SciTech Connect

    Karaki, S.; Brothers, P.

    1980-06-01

    The technical and economic feasibility of using a direct contact liquid-liquid heat exchanger (DCLLHE) storage unit in a solar heating and cooling system is established. Experimental performance data were obtained from the CSU Solar House I using a DCLLHE for both heating and cooling functions. A simulation model for the system was developed. The model was validated using the experimental data and applied in five different climatic regions of the country for a complete year. The life-cycle cost of the system was estimated for each application. The results are compared to a conventional solar system, using a standard shell-and-tube heat exchanger. It is concluded that while thare is a performance advantage with a DCLLHE system over a conventional solar system, the advantage is not sufficiently large to overcome slightly higher capital and operating costs for the DCLLHE system.

  2. Direct observation of both contact and remote oxygen scavenging of GeO{sub 2} in a metal-oxide-semiconductor stack

    SciTech Connect

    Fadida, S. Shekhter, P.; Eizenberg, M.; Cvetko, D.; Floreano, L.; Verdini, A.; Kymissis, I.

    2014-10-28

    In the path to incorporating Ge based metal-oxide-semiconductor into modern nano-electronics, one of the main issues is the oxide-semiconductor interface quality. Here, the reactivity of Ti on Ge stacks and the scavenging effect of Ti were studied using synchrotron X-ray photoelectron spectroscopy measurements, with an in-situ metal deposition and high resolution transmission electron microscopy imaging. Oxygen removal from the Ge surface was observed both in direct contact as well as remotely through an Al{sub 2}O{sub 3} layer. The scavenging effect was studied in situ at room temperature and after annealing. We find that the reactivity of Ti can be utilized for improved scaling of Ge based devices.

  3. Two-dimensional simulation of a two-phase, regenerative pumped radiator loop utilizing direct contact heat transfer with phase change

    NASA Astrophysics Data System (ADS)

    Rhee, Hyop S.; Begg, Lester L.; Wetch, Joseph R.; Jang, Jong H.; Juhasz, Albert J.

    An innovative pumped loop concept for 600 K space power system radiators utilizing direct contact heat transfer, which facilitates repeated startup/shutdown of the power system without complex and time-consuming coolant thawing during power startup, is under development. The heat transfer process with melting/freezing of Li in an NaK flow was studied through two-dimensional time-dependent numerical simulations to characterize and predict the Li/NaK radiator performance during startup (thawing) and shutdown (cold-trapping). Effects of system parameters and the criteria for the plugging domain are presented together with temperature distribution patterns in solid Li and subsequent melting surface profile variations in time.

  4. Direct contacts between conserved motifs of different subunits provide major contribution to active site organization in human and mycobacterial dUTPases

    PubMed Central

    Takács, Enikő; Nagy, Gergely; Leveles, Ibolya; Harmat, Veronika; Lopata, Anna; Tóth, Judit; Vértessy, Beáta G.

    2010-01-01

    dUTPases are essential for genome integrity. Recent results allowed characterization of the role of conserved residues. Here we analyzed the Asp/Asn mutation within conserved Motif I of human and mycobacterial dUTPases, wherein the Asp residue was previously implicated in Mg2+-coordination. Our results on transient/steady-state kinetics, ligand-binding and a 1.80 Å-resolution structure of the mutant mycobacterial enzyme, in comparison with wild type and C-terminally truncated structures, argue that this residue has a major role in providing intra- and intersubunit contacts, but is not essential for Mg2+ accommodation. We conclude that in addition to the role of conserved motifs in substrate accommodation, direct subunit interaction between protein atoms of active site residues from different conserved motifs are crucial for enzyme function. PMID:20493855

  5. Wound closure after split-thickness skin grafting is accelerated with the use of continuous direct anodal microcurrent applied to silver nylon wound contact dressings.

    PubMed

    Huckfeldt, Roger; Flick, A Bart; Mikkelson, Debbie; Lowe, Cindy; Finley, Phillip J

    2007-01-01

    Wound healing after graft closure of excised burn wounds is a critical factor in the recovery process after thermal injury. Processes that speed time to stable wound closure should lead to improved outcomes, shorter lengths of hospital stays, and decreased complications. A randomized clinical trial to test the ability of continuous direct anodal microcurrent application to silver nylon wound contact dressings was designed. Time for wound closure after split-thickness skin grafting was observed. Thirty patients with full-thickness thermal burns were randomized into two groups. The control group received postoperative dressing care using moistened silver nylon fabric covered with gauze after tangential burn wound excision and split-thickness skin grafting. The study group received an identical protocol with the addition of continuous direct anodal microcurrent application. Time to 95% wound closure was measured using digital photography. The digital photographs were evaluated by a burn surgeon blinded to the patient's randomization. An independent t-test was used to analyze the data. The study group experienced a 36% reduction in time to wound closure (mean of 4.6 days) as compared to the control group (mean of 7.2 days). This was statistically significant at a P value of <.05. The use of continuous direct anodal microcurrent decreased time to wound closure after split-thickness skin grafting.

  6. Quantitative determination of some volatile suspected allergens in cosmetic creams spread on skin by direct contact sorptive tape extraction-gas chromatography-mass spectrometry.

    PubMed

    Sgorbini, B; Ruosi, M R; Cordero, C; Liberto, E; Rubiolo, P; Bicchi, C

    2010-04-16

    This study describes a method based on direct contact sorptive tape extraction followed by on-line thermal desorption gas chromatography-mass spectrometry (DC-STE-GC-MS) to detect and quantify a group of suspected volatile allergens on the European Union (E.U.) list and a related compound on the skin (the stratum corneum) of volunteers treated with a cream of known composition fortified with the reference allergens. The following compounds were tested: citronellol, Z-citral (neral), geraniol, cinnamaldehyde, anisyl alcohol, cinnamyl alcohol, eugenol, methyleugenol, coumarin, isoeugenol, alpha-isomethylionone, 2-(4-tert-butylbenzyl)propionaldehyde (lilial), alpha-amylcinnamaldehyde, alpha-hexylcinnamaldehyde. Sorptive tape extraction (STE) is a sorption-based sampling technique in which a flexible polydimethylsiloxane (PDMS) tape is used to recover analytes by direct contact with the surface of a solid matrix or from the headspace in equilibrium with it. The reliability of the method was confirmed by: (i) allergen recoveries varying from 52.3% for lilial to 95.7% for neral, (ii) linearity in the range 10-150ppm, with regression coefficient R(2) always above 0.97, (iii) repeatability of each analyte, RSD% never exceeding 10%, (iv) intermediate precision, always below 15%, and (v) LOD and LOQ in the ppb range, therefore fully compatible with E.U. prescriptions (ppm). Other parameters such as substantivity analyte, approximate permeation through skin and influence of different nature of stratum corneum on recovery were also investigated. The method was also successfully applied to five commercially available creams declared to contain some of the allergens in question spread on the skin of the same volunteers. Copyright 2010 Elsevier B.V. All rights reserved.

  7. Enhanced Boiling on Micro-Configured Composite Surfaces Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    Zhang, Nengli; Chai, An-Ti

    1999-01-01

    In order to accommodate the growing thermal management needs of future space platforms, several two-phase active thermal control systems (ATCSs) have evolved and were included in the designs of space stations. Compared to the pumped single-phase liquid loops used in the conventional Space Transportation System and Spacelab, ATCSs offer significant benefits that may be realized by adopting a two-phase fluid-loop system. Alternately, dynamic power systems (DPSs), based on the Rankine cycle, seem inevitably to be required to supply the electrical power requirements of expanding space activities. Boiling heat transfer is one of the key technologies for both ATCSs and DPSs. Nucleate boiling near critical heat flux (CHF) can transport very large thermal loads with much smaller device size and much lower pumping power. However, boiling performance deteriorates in a reduced gravity environment and operation in the CHF regime is precarious because any slight overload will cause the heat transfer to suddenly move to the film boiling regime, which in turn, will result in burnout of the heat transfer surfaces. New materials, such as micro-configured metal-graphite composites, can provide a solution for boiling enhancement. It has been shown experimentally that this type of material manifests outstanding boiling heat transfer performance and their CHF is also extended to higher values. Due to the high thermal conductivity of graphite fiber (up to 1,200 W/m-K in the fiber direction), the composite surfaces are non-isothermal during the boiling process. The composite surfaces are believed to have a much wider safe operating region (a more uniform boiling curve in the CHF regime) because non-isothermal surfaces have been found to be less sensitive to variations of wall superheat in the CHF regime. The thermocapillary forces formed by the temperature difference between the fiber tips and the metal matrix play a more important role than the buoyancy in the bubble detachment, for the

  8. Effect of boiling regime on melt stream breakup in water

    SciTech Connect

    Spencer, B.W.; Gabor, J.D.; Cassulo, J.C.

    1986-01-01

    A study has been performed examining the breakup and mixing behavior of an initially coherent stream of high-density melt as it flows downward through water. This work has application to the quenching of molten core materials as they drain downward during a postulated severe reactor accident. The study has included examination of various models of breakup distances based upon interfacial instabilities dominated either by liquid-liquid contact or by liquid-vapor contact. A series of experiments was performed to provide a data base for assessment of the various modeling approaches. The experiments involved Wood's metal (T/sub m/ = 73/sup 0/C, rho = 9.2 g/cm/sup 3/, d/sub j/ = 20 mm) poured into a deep pool of water. The temperature of the water and wood's metal were varied to span the range from single-phase, liquid-liquid contact to the film boiling regime. Experiment results showed that breakup occurred largely as a result of the spreading and entrainment from the leading edge of the jet. However, for streams of sufficient lengths a breakup length could be discerned at which there was no longer a coherent central core of the jet to feed the leading edge region. The erosion of the vertical trailing column is by Kelvin-Helmoltz instabilities and related disengagement of droplets from the jet into the surrounding fluid. For conditions of liquid-liquid contact, the breakup length has been found to be about 20 jet diameters; when substantial vapor is produced at the interface due to heat transfer from the jet to the water, the breakup distance was found to range to as high as 50 jet diameters. The former values are close to the analytical prediction of Taylor, whereas the latter values are better predicted by the model of Epstein and Fauske.

  9. Nucleate boiling pressure drop in an annulus: Book 5

    SciTech Connect

    Not Available

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux. This document consists solely of the plato file index from 11/87 to 11/90.

  10. Induction of mucosal immune responses and protection of cattle against direct-contact challenge by intranasal delivery with foot-and-mouth disease virus antigen mediated by nanoparticles

    PubMed Central

    Pan, Li; Zhang, Zhongwang; Lv, Jianliang; Zhou, Peng; Hu, Wenfa; Fang, Yuzhen; Chen, Haotai; Liu, Xinsheng; Shao, Junjun; Zhao, Furong; Ding, Yaozhong; Lin, Tong; Chang, Huiyun; Zhang, Jie; Zhang, Yongguang; Wang, Yonglu

    2014-01-01

    The aim of this study was to enhance specific mucosal, systemic, and cell-mediated immunity and to induce earlier onset of protection against direct-contact challenge in cattle by intranasal delivery of a nanoparticle-based nasal vaccine against type A foot-and-mouth disease (FMD). In this study, two kinds of nanoparticle-based nasal vaccines against type A FMD were designed: (1) chitosan-coated poly(lactic-co-glycolic acid) (PLGA) loaded with plasmid DNA (Chi-PLGA-DNA) and (2) chitosan-trehalose and inactivated foot-and-mouth disease virus (FMDV) (Chi-Tre-Inactivated). Cattle were immunized by an intranasal route with nanoparticles and then challenged for 48 hours by direct contact with two infected donor cattle per pen. Donors were inoculated intradermally in the tongue 48 hours before challenge, with 0.2 mL cattle-passaged FMDV. Serological and mucosal antibody responses were evaluated, and virus excretion and the number of contact infections were quantified. FMDV-specific secretory immunoglobulin (Ig)A (sIgA) antibodies in nasal washes were initially detected at 4 days postvaccination (dpv) with two kinds of nanoparticles. The highest levels of sIgA expression were observed in nasal washes, at 10 dpv, from animals with Chi-PLGA-DNA nanoparticles, followed by animals immunized once by intranasal route with a double dose of Chi-Tre-Inactivated nanoparticles and animals immunized by intranasal route three times with Chi-Tre-Inactivated nanoparticles (P<0.05). FMDV-specific IgA antibodies in serum showed a similar pattern. All animals immunized by intranasal route developed low levels of detectable IgG in serum at 10 dpv. Following stimulation with FMDV, the highest levels of proliferation were observed in splenocytes harvested from Chi-PLGA-DNA-immunized animals, followed by proliferation of cells harvested from Chi-Tre-Inactivated nanoparticle-immunized animals (P<0.05). Higher protection rates were associated with the highest sIgA antibody responses induced in

  11. Induction of mucosal immune responses and protection of cattle against direct-contact challenge by intranasal delivery with foot-and-mouth disease virus antigen mediated by nanoparticles.

    PubMed

    Pan, Li; Zhang, Zhongwang; Lv, Jianliang; Zhou, Peng; Hu, Wenfa; Fang, Yuzhen; Chen, Haotai; Liu, Xinsheng; Shao, Junjun; Zhao, Furong; Ding, Yaozhong; Lin, Tong; Chang, Huiyun; Zhang, Jie; Zhang, Yongguang; Wang, Yonglu

    2014-01-01

    The aim of this study was to enhance specific mucosal, systemic, and cell-mediated immunity and to induce earlier onset of protection against direct-contact challenge in cattle by intranasal delivery of a nanoparticle-based nasal vaccine against type A foot-and-mouth disease (FMD). In this study, two kinds of nanoparticle-based nasal vaccines against type A FMD were designed: (1) chitosan-coated poly(lactic-co-glycolic acid) (PLGA) loaded with plasmid DNA (Chi-PLGA-DNA) and (2) chitosan-trehalose and inactivated foot-and-mouth disease virus (FMDV) (Chi-Tre-Inactivated). Cattle were immunized by an intranasal route with nanoparticles and then challenged for 48 hours by direct contact with two infected donor cattle per pen. Donors were inoculated intradermally in the tongue 48 hours before challenge, with 0.2 mL cattle-passaged FMDV. Serological and mucosal antibody responses were evaluated, and virus excretion and the number of contact infections were quantified. FMDV-specific secretory immunoglobulin (Ig)A (sIgA) antibodies in nasal washes were initially detected at 4 days postvaccination (dpv) with two kinds of nanoparticles. The highest levels of sIgA expression were observed in nasal washes, at 10 dpv, from animals with Chi-PLGA-DNA nanoparticles, followed by animals immunized once by intranasal route with a double dose of Chi-Tre-Inactivated nanoparticles and animals immunized by intranasal route three times with Chi-Tre-Inactivated nanoparticles (P<0.05). FMDV-specific IgA antibodies in serum showed a similar pattern. All animals immunized by intranasal route developed low levels of detectable IgG in serum at 10 dpv. Following stimulation with FMDV, the highest levels of proliferation were observed in splenocytes harvested from Chi-PLGA-DNA-immunized animals, followed by proliferation of cells harvested from Chi-Tre-Inactivated nanoparticle-immunized animals (P<0.05). Higher protection rates were associated with the highest sIgA antibody responses induced in

  12. Unorthodox bubbles when boiling in cold water

    NASA Astrophysics Data System (ADS)

    Parker, Scott; Granick, Steve

    2014-01-01

    High-speed movies are taken when bubbles grow at gold surfaces heated spotwise with a near-infrared laser beam heating water below the boiling point (60-70 °C) with heating powers spanning the range from very low to so high that water fails to rewet the surface after bubbles detach. Roughly half the bubbles are conventional: They grow symmetrically through evaporation until buoyancy lifts them away. Others have unorthodox shapes and appear to contribute disproportionately to heat transfer efficiency: mushroom cloud shapes, violently explosive bubbles, and cavitation events, probably stimulated by a combination of superheating, convection, turbulence, and surface dewetting during the initial bubble growth. Moreover, bubbles often follow one another in complex sequences, often beginning with an unorthodox bubble that stirs the water, followed by several conventional bubbles. This large dataset is analyzed and discussed with emphasis on how explosive phenomena such as cavitation induce discrepancies from classical expectations about boiling.

  13. Pool Boiling Heat Transfer on structured Surfaces

    NASA Astrophysics Data System (ADS)

    Addy, J.; Olbricht, M.; Müller, B.; Luke, A.

    2016-09-01

    The development in the process and energy sector shows the importance of efficient utilization of available resources to improve thermal devices. To achieve this goal, all thermal components have to be optimized continuously. Various applications of multi-phase heat and mass transfer have to be improved. Therefore, the heat transfer and the influence of surface roughness in nucleate boiling with the working fluid propane is experimentally investigated on structured mild steel tubes, because only few data are available in the literature. The mild steel tube is sandblasted to obtain different surface roughness. The measurements are carried out over wide ranges of heat flux and pressure. The experimental results are compared with correlations from literature and the effect of surface roughness on the heat transfer is discussed. It is shown that the heat transfer coefficient increases with increasing surface roughness, heat flux and reduced pressure at nucleate pool boiling.

  14. Unorthodox bubbles when boiling in cold water.

    PubMed

    Parker, Scott; Granick, Steve

    2014-01-01

    High-speed movies are taken when bubbles grow at gold surfaces heated spotwise with a near-infrared laser beam heating water below the boiling point (60-70 °C) with heating powers spanning the range from very low to so high that water fails to rewet the surface after bubbles detach. Roughly half the bubbles are conventional: They grow symmetrically through evaporation until buoyancy lifts them away. Others have unorthodox shapes and appear to contribute disproportionately to heat transfer efficiency: mushroom cloud shapes, violently explosive bubbles, and cavitation events, probably stimulated by a combination of superheating, convection, turbulence, and surface dewetting during the initial bubble growth. Moreover, bubbles often follow one another in complex sequences, often beginning with an unorthodox bubble that stirs the water, followed by several conventional bubbles. This large dataset is analyzed and discussed with emphasis on how explosive phenomena such as cavitation induce discrepancies from classical expectations about boiling.

  15. Direct and indirect contact rates among beef, dairy, goat, sheep, and swine herds in three California counties, with reference to control of potential foot-and-mouth disease transmission.

    PubMed

    Bates, T W; Thurmond, M C; Carpenter, T E

    2001-07-01

    To estimate direct and indirect contact rates on livestock facilities and distance traveled between herd contacts. 320 beef, dairy, goat, sheep, and swine herds, 7 artificial insemination technicians, 6 hoof trimmers, 15 veterinarians, 4 sales yard owners, and 7 managers of livestock-related companies within a 3-county region of California. A questionnaire was mailed to livestock producers, and personal and telephone interviews were conducted with individuals. Mean monthly direct contact rates were 2.6, 1.6, and 2.0 for dairies with < 1,000, 1,000 to 1,999, and > or = 2,000 cattle, respectively. Mean indirect contact rates on dairies ranged from 234 to 743 contacts/mo and increased by 1 contact/mo as herd size increased by 4.3. Mean direct monthly contact rate for beef herds was 0.4. Distance traveled by personnel and vehicles during a 3-day period ranged from 58.4 to 210.4 km. Of livestock arriving at sales yards, 7% (500/7,072) came from > or = 60 km away, and of those sold, 32% (1,180/3,721) were destined for a location > or = 60 km away. Fifty-five percent (16/29) of owners of large beef herds observed deer or elk within 150 m of livestock at least once per month. Direct and indirect contacts occur on livestock facilities located over a wide geographic area and at a higher frequency on larger facilities. Knowledge of contact rates may be useful for planning biosecurity programs at the herd, state, and national levels and for modeling transmission potential for foot-and-mouth disease virus.

  16. Flow boiling in vertical down-flow

    SciTech Connect

    Dougherty, T.; Fighetti, C.; Reddy, G.; Yang, B.; Jafri, T.; McAssey, E.; Qureshi, Z.

    1989-12-31

    An experimental program has been conducted to investigate the onset of Ledinegg instability in vertical down-flow. For three size uniformly heated test sections with L/D ratios from 100 to 150, the pressure drop under subcooled boiling conditions has been obtained for a wide range of operating parameters. The results are presented in non-dimensional forms which correlate the important variables and provide techniques for predicting the onset of flow instability. 3 refs.

  17. Flow boiling in vertical down-flow

    SciTech Connect

    Dougherty, T.; Fighetti, C.; Reddy, G.; Yang, B.; Jafri, T. ); McAssey, E. ); Qureshi, Z. )

    1989-01-01

    An experimental program has been conducted to investigate the onset of Ledinegg instability in vertical down-flow. For three size uniformly heated test sections with L/D ratios from 100 to 150, the pressure drop under subcooled boiling conditions has been obtained for a wide range of operating parameters. The results are presented in non-dimensional forms which correlate the important variables and provide techniques for predicting the onset of flow instability. 3 refs.

  18. Numerical Simulation on Single Bubble Pool Boiling with Influence of Heater Thermal Capacity

    NASA Astrophysics Data System (ADS)

    Zhao, Jian-Fu; Zhang, Liang; Li, Zhen-Dong

    The model of single bubble pool boiling is used to simulate nucleate pool boiling phenomenon in the present paper. Local convection and heat transfer around a single vapour bubble which is growing from a nucleus bubble planted artificially on the surface of heaters with different thicknesses, as well as transient heat conduction inside the heater’s wall, are simulated numerically with sharp interface representation. Multi-cycle simulation is adopted to eliminate the effect of un-physical initial conditions. It’s found that the thermal response of wall is found to affect the bubble growth and boiling heat transfer. During the process of bubble growth, a sharp temperature drop inside the solid wall is evident near the contact line underneath the growing bubble because of the strong evaporation in micro-region. The temperature and heat flux profiles change with the move of the contact line, and twice sharp temperature drops at a certain location are observed, which correspond to the expanding and recoiling processes, respectively. During the waiting period after the bubble detached from the wall, the temperature field is recovered by heat conduction inside the solid wall. As a part of preparation of the SOBER project onboard the Chinese recoverable satellite SJ-10, which will be launched in the end of 2015, the gravity influence is also studied.

  19. Experimental investigation of film boiling on spheres using high-speed video

    NASA Astrophysics Data System (ADS)

    Agaltsov, Andrey; Fedoseenko, Ivan

    2012-04-01

    The experimental investigation of saturated Freon-113 film boiling on spheres with different diameters at atmospheric pressure under conditions of free convection is executed. It was found that with increasing diameter of the sphere and the temperature difference is changing the wave motion of the vapor film with two-dimensional to three-dimensional mode. Also, found that in a range of regime parameters at which observed a three-dimensional interface motion, the destruction method of two-dimensional wave is similar to a series of three or more waves. I.e. was some system memory. When the temperature difference close to critical after the passage of a wave are possible the local contacts of liquid with a heated surface of the sphere. However, these contacts do not lead to degradation of the wave motion of the interface, and the film boiling crisis of saturated Freon-113 occurs smoothly in contrast to the crisis at boiling of saturated and subcooled water.

  20. Flow boiling test of GDP replacement coolants

    SciTech Connect

    Park, S.H.

    1995-08-01

    The tests were part of the CFC replacement program to identify and test alternate coolants to replace CFC-114 being used in the uranium enrichment plants at Paducah and Portsmouth. The coolants tested, C{sub 4}F{sub 10} and C{sub 4}F{sub 8}, were selected based on their compatibility with the uranium hexafluoride process gas and how well the boiling temperature and vapor pressure matched that of CFC-114. However, the heat of vaporization of both coolants is lower than that of CFC-114 requiring larger coolant mass flow than CFC-114 to remove the same amount of heat. The vapor pressure of these coolants is higher than CFC-114 within the cascade operational range, and each coolant can be used as a replacement coolant with some limitation at 3,300 hp operation. The results of the CFC-114/C{sub 4}F{sub 10} mixture tests show boiling heat transfer coefficient degraded to a minimum value with about 25% C{sub 4}F{sub 10} weight mixture in CFC-114 and the degree of degradation is about 20% from that of CFC-114 boiling heat transfer coefficient. This report consists of the final reports from Cudo Technologies, Ltd.

  1. Fundamental Boiling and RP-1 Freezing Experiments

    NASA Technical Reports Server (NTRS)

    Goode, Brian; Turner, Larry D. (Technical Monitor)

    2001-01-01

    This paper describes results from experiments performed to help understand certain aspects of the MC-1 engine prestart thermal conditioning procedure. The procedure was constrained by the fact that the engine must chill long enough to get quality LOX at the LOX pump inlet but must be short enough to prevent freezing of RP-1 in the fuel pump. A chill test of an MC-1 LOX impeller was performed in LN2 to obtain data on film boiling, transition boiling and impeller temperature histories. The transition boiling data was important to the chill time so a subsequent experiment was performed chilling simple steel plates in LOX to obtain similar data for LOX. To address the fuel freezing concern, two experiments were performed. First, fuel was frozen in a tray and its physical characteristics were observed and temperatures of the fuel were measured. The result was physical characteristics as a function of temperature. Second was an attempt to measure the frozen thickness of RP-1 on a cold wall submerged in warm RP-1 and to develop a method for calculating that thickness for other conditions.

  2. Boiling incipience in a reboiler tube

    SciTech Connect

    Ali, H.; Alam, S.S. )

    1991-03-01

    This heating surface and liquid temperature distributions were experimentally obtained to identify the boiling incipience conditions in a single vertical tube thermosiphon reboiler with water, acetone, ethanol, and ethylene glycol as test liquids. The test section was an electrically heated stainless steel tube of 25.56-mm i.d. and 1900 mm long. The uniform heat flux values were used in the range of 3800--40 000 W/m{sup 2}, while inlet liquid subcooling were varied from 0.2 to 45.5{degrees} C. The liquid submergence was maintained around 100, 75, 50 and 30%. All the data were generated at 1-atm pressure. The maximum superheats attained around boiling incipience were taken from the wall temperature distributions and correlated with heat flux and physical properties of liquids using the expression of Yin and Abdelmessih. The heated sections required for onset of fully developed boiling with net vapor generation were determined assuming a thermal equilibrium model. In this paper a dimensionless correlation relating these values with heat flux, liquid subcooling, and submergence is proposed.

  3. Experimental study of nucleate boiling heat transfer under low gravity conditions using TLCs for high resolution temperature measurements

    NASA Astrophysics Data System (ADS)

    Wagner, Enno; Sodtke, Christof; Schweizer, Nils; Stephan, Peter

    2006-08-01

    Heat transfer in nucleate boiling is strongly influenced by a very small circular area in the vicinity of the three phase contact line where a thin liquid film approaches the heated wall. This area is characterised by high evaporation rates which trigger a local temperature drop in the wall. The wall temperature drop can be computed using an existing nucleate boiling model. To verify the complex model and the underlying assumptions, an experiment was designed with an artificial nucleation site in a thin electrically heated wall featuring a two-dimensional, high resolution temperature measurement technique using unencapsulated thermochromic liquid crystals and a high speed colour camera. The shape of the bubble is observed simultaneously with a second high speed camera. Experiments were conducted in a low gravity environment of a parabolic flight, causing larger bubble departure diameters than in normal gravity environments. Thus, it was possible to measure the evolution of the predicted temperature drop in a transient boiling process.

  4. Self-Directed Contact Desensitization

    ERIC Educational Resources Information Center

    Moss, Martin K.; Arend, Richard A.

    1977-01-01

    College-student snake phobics received one of four treatments to reduce their snake avoidance behavior. Behavioral and self-report assessment showed all three treatments relative to the control to be highly and equally effective in reducing snake avoidance behavior. (Author)

  5. Full evaporation headspace gas chromatography for sensitive determination of high boiling point volatile organic compounds in low boiling matrices.

    PubMed

    Mana Kialengila, Didi; Wolfs, Kris; Bugalama, John; Van Schepdael, Ann; Adams, Erwin

    2013-11-08

    Determination of volatile organic components (VOC's) is often done by static headspace gas chromatography as this technique is very robust and combines easy sample preparation with good selectivity and low detection limits. This technique is used nowadays in different applications which have in common that they have a dirty matrix which would be problematic in direct injection approaches. Headspace by nature favors the most volatile compounds, avoiding the less volatile to reach the injector and column. As a consequence, determination of a high boiling solvent in a lower boiling matrix becomes challenging. Determination of VOCs like: xylenes, cumene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), benzyl alcohol (BA) and anisole in water or water soluble products are an interesting example of the arising problems. In this work, a headspace variant called full evaporation technique is worked out and validated for the mentioned solvents. Detection limits below 0.1 μg/vial are reached with RSD values below 10%. Mean recovery values ranged from 92.5 to 110%. The optimized method was applied to determine residual DMSO in a water based cell culture and DMSO and DMA in tetracycline hydrochloride (a water soluble sample).

  6. Nucleate Pool Boiling of Surface-Modified Nano-Porous Alumina

    NASA Astrophysics Data System (ADS)

    Zhang, Bong June

    In nucleate pool boiling, heat transfer augment is an important issue. Among various techniques for enhancement, porous surfaces with millimeter to micron-sized diameter have been studied in the past few decades. In this study, the nano porous surface (NPS) of alumina was created to address technical issues in submicron regime pool boiling. Especially, influence of surface modifications (structural and chemical treatments) of the NPS over heat transfer enhancement was the subject of the reported research. There are a few important aspects of the research reported in this dissertation: to develop the optimal NPS to increase heat transfer in nucleate pool boiling, to suggest the mechanistic model to explain heat transfer augment in submicron regime, and to assess the feasibility of the NPS for nucleate pool boiling enhancement. First of all, an optimal NPS with surface modifications for heat transfer in nucleate pool boiling was developed. The surface-modified NPS provides enlarged heating surface area, active nucleation site enhancement, and improvement of vapor-liquid menisci through reentrant-shaped cavities. Secondly, the mechanistic model suggested in this study explained that the combination of convection-driven and phase change-induced heat transfers and liquid thin film evaporation (LTFE) achieves heat transfer augment. Especially, the model supported the hypothesis that the NPS is appropriate to dissipate heat through the LTFE at lower heat flux regime. Lastly, this study shows that heat transfer enhancement phenomena of the NPS that was evaluated and quantified by using various physical and electrochemical methods. For instance, most contributing factor of the CHF enhancement was assumed the liquid spreading and the absorption-induced capillary pressure. They were assessed by using Apparent Water Contact Angle (AWCA) and Electrochemical Impedance Spectroscopy (EIS) measurements of which trends were well matched with CHF experimental data.

  7. An assessment of antibacterial activity of three pulp capping materials on Enterococcus faecalis by a direct contact test: An in vitro study.

    PubMed

    Koruyucu, Mine; Topcuoglu, Nursen; Tuna, E Bahar; Ozel, Sevda; Gencay, Koray; Kulekci, Guven; Seymen, Figen

    2015-01-01

    The aim of this in vitro study was to evaluate antimicrobial activities of three different pulp capping materials; Biodentine, mineral trioxide aggregate (MTA) Angelus, and Dycal against Enterococcus faecalis and their durability with time. Direct contact test was used for the assessment. Three sets of sealers were mixed and placed on microtiter plate wells: One set was used within 20 min of recommended setting time while others were used after 24-h and 1-week. E. faecalis suspension was placed directly on the materials for 1 h and then transferred to another plate with fresh media. Nine wells of bacteria without the tested cements served as the positive control. One well of the tested cements without bacteria served as the negative control. Bacterial growth was evaluated by a temperature-controlled microplate spectrophotometer for 1-h intervals among 24 h. Data were analyzed using Kruskal-Wallis test. All tested materials showed less bacterial density than the control group. MTA, Biodentine, and Dycal showed significantly higher bacterial density than the control group in freshly mixed samples (P < 0.05). And MTA showed significantly higher antibacterial activity than Dycal (P < 0.05). In 24 h, materials did not show any differences (P > 0.05). MTA and Biodentine samples showed significant differences than Dycal; MTA also showed higher antibacterial activity than control in 1-week samples (P < 0.05). While freshly mixed MTA showed the best antibacterial activity over time, Biodentine had shown similar antibacterial activity to MTA.

  8. An experimental investigation of rapid boiling of

    NASA Astrophysics Data System (ADS)

    Tosse, S.; Vaagsaether, K.; Bjerketvedt, D.

    2015-05-01

    Storage of pressurized liquified gases is a growing safety concern in many industries. Knowledge of the thermodynamics and kinetics involved in the rapid depressurization and evaporation of such substances is key to the design and implementation of effective safety measures in storage and transportation situations. In the present study, experiments on the rapid depressurization of liquid are conducted in a vertical transparent shock tube which enables the observation of evaporation waves and other structures. The depressurization was initiated by puncturing a membrane in one end of the tube. The thermodynamic mechanisms that govern the evaporation process are not unique to , and the same principles can be applied to any liquified gas. The experiments were photographed by a high-speed camera. Evaporation waves propagating into the liquid were observed, traveling at a near constant velocity on the order of 20-30 m/s. A contact surface between the vapor and the liquid-vapor mixture was also observed, accelerating out of the tube. Pressure readings in the tube suggest that the evaporation wave could be similar to a spinodal decomposition wave, but further experiments are needed to confirm this. When the membrane was in direct contact with the liquified , some indications of homogeneous nucleation were observed.

  9. Boiling radial flow in fractures of varying wall porosity

    SciTech Connect

    Barnitt, Robb Allan

    2000-06-01

    The focus of this report is the coupling of conductive heat transfer and boiling convective heat transfer, with boiling flow in a rock fracture. A series of experiments observed differences in boiling regimes and behavior, and attempted to quantify a boiling convection coefficient. The experimental study involved boiling radial flow in a simulated fracture, bounded by a variety of materials. Nonporous and impermeable aluminum, highly porous and permeable Berea sandstone, and minimally porous and permeable graywacke from The Geysers geothermal field. On nonporous surfaces, the heat flux was not strongly coupled to injection rate into the fracture. However, for porous surfaces, heat flux, and associated values of excess temperature and a boiling convection coefficient exhibited variation with injection rate. Nucleation was shown to occur not upon the visible surface of porous materials, but a distance below the surface, within the matrix. The depth of boiling was a function of injection rate, thermal power supplied to the fracture, and the porosity and permeability of the rock. Although matrix boiling beyond fracture wall may apply only to a finite radius around the point of injection, higher values of heat flux and a boiling convection coefficient may be realized with boiling in a porous, rather than nonporous surface bounded fracture.

  10. Wettability influence on the onset temperature of pool boiling: Experimental evidence onto ultra-smooth surfaces.

    PubMed

    Bourdon, B; Bertrand, E; Di Marco, P; Marengo, M; Rioboo, R; De Coninck, J

    2015-07-01

    In this article we study systematically the effect of wettability on the onset of boiling on the same nanometrically smooth surface. By grafting different monolayers of molecules, we were able to explore the wettability from the equilibrium static contact angle, θ0=0° to θ0=110°, without changing the surface topography. The superheat temperature at the onset of pool boiling was measured and eventually a non-classical trend of TONB as a function of wettability was observed. The nucleation site densities for the different grafting cases were also measured by image analysis. Moreover, we propose a novel theoretical interpretation to this phenomenon linking nucleation and the molecular diffusion coefficient. MD simulation results support this approach.

  11. Transient Pool Boiling Critical Heat Flux of FC-72 Under Saturated Conditions

    SciTech Connect

    Fitri, Sutopo P.; Katsuya Fukuda; Qiusheng Liu; Jongdoc Park

    2006-07-01

    In this study, the steady-state and transient critical heat fluxes (CHFs) in pool boiling were measured on 1.0 mm diameter horizontal cylinders of gold and platinum heaters under saturated conditions due to transient heat inputs, Q{sub 0}exp(t/t), in a pool of Fluorinert FC-72. Heaters were heated by electric current with the periods, t, ranged from 10 ms to 20 s, and the pressures ranged from atmospheric up to around 1.2 MPa. The steady-state CHFs measured are dependent on pressure and almost agree with the values obtained by Kutateladze's correlation based on hydrodynamic instability (HI) model. It was considered that the boiling inception and the direct transition during the steady-state period occur by the pre-pressure of {approx}1.2 MPa. The trend of typical transient CHFs were clearly divided into the first, second, and third groups for long, short, and intermediate periods, respectively. The direct transition processes to film boiling without nucleate boiling for the short periods obtained from both heaters were confirmed due to the heterogeneous spontaneous nucleation (HSN) in flooded cavities on the cylinder surface. The empirical correlations to express each of corresponding CHFs measured on both heaters for the short periods are presented in this paper. (authors)

  12. Head and rod 1 interactions in vimentin: identification of contact sites, structure, and changes with phosphorylation using site-directed spin labeling and electron paramagnetic resonance.

    PubMed

    Aziz, Atya; Hess, John F; Budamagunta, Madhu S; FitzGerald, Paul G; Voss, John C

    2009-03-13

    We have used site-directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) to identify residues 17 and 137 as sites of interaction between the head domain and rod domain 1A of the intermediate filament protein vimentin. This interaction was maximal when compared with the spin labels placed at up- and downstream positions in both head and rod regions, indicating that residues 17 and 137 were the closest point of interaction in this region. SDSL EPR characterization of residues 120-145, which includes the site of head contact with rod 1A, reveals that this region exhibits the heptad repeat pattern indicative of alpha-helical coiled-coil structure, but that this heptad repeat pattern begins to decay near residue 139, suggesting a transition out of coiled-coil structure. By monitoring the spectra of spin labels placed at the 17 and 137 residues during in vitro assembly, we show that 17-137 interaction occurs early in the assembly process. We also explored the effect of phosphorylation on the 17-137 interaction and found that phosphorylation-induced changes affected the head-head interaction (17-17) in the dimer, without significantly influencing the rod-rod (137-137) and head-rod (17-137) interactions in the dimer. These data provide the first direct evidence for, and location of, head-rod interactions in assembled intermediate filaments, as well as direct evidence of coiled-coil structure in rod 1A. Finally, the data identify changes in the structure in this region following in vitro phosphorylation.

  13. Effect of bending direction on the mechanical behaviour of 3.5 mm String-of-Pearls and Limited Contact Dynamic Compression Plate constructs.

    PubMed

    Benamou, J; Demianiuk, R M; Rutherford, S; Beckett, C; Ness, M G; Haut, R C; Déjardin, L M

    2015-01-01

    To compare the bending properties of String-of-Pearls® (SOP) and Limited Contact Dynamic Compression Plate® (LC-DCP) constructs in orthogonal bending directions. 3.5 mm SOP and LC-DCP plates were fixed to a bone model simulating a comminuted tibial fracture. Specimens were non-destructively tested in both mediolateral and craniocaudal bending for 10 cycles. Bending stiffness and total angular deformation were compared using parametric analyses (p <0.05). For both constructs, stiffness was significantly less when bending moments were applied against the thickness of the plates (mediolateral bending) than against the width (craniocaudal bending). When compared to the mediolateral plane, bending constructs in the craniocaudal plane resulted in a 49% (SOP group) and 370% (LC-DCP group) increase in stiffness (p <0.001). Mediolateral bending stiffness was significantly greater in the SOP than the LC-DCP constructs. Conversely, in craniocaudal bending, SOP constructs stiffness was significantly less than that of the LC-DCP constructs. The differences between the two constructs in total angular deformation had an identical pattern of significance. This study found that SOP showed less variability between the orthogonal bending directions than LC-DCP in a comminuted fracture model, and also described the bi-planar bending behaviour of both constructs. Although not exhibiting identical bending properties in both planes, SOP constructs had a more homogenous bending behaviour in orthogonal loading directions. The difference between the SOP with a circular cross sectional shape compared to the rectangular shape of standard plates is probably responsible for this difference.

  14. Enhanced Boiling on Micro-Configured Composite Surfaces Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Two experimental setups: High Heat Flux Pool Boiling Setup and Optical system of Measuring Contact Angle and Spreading Parameters were established and a series of experiments was conducted. The experimental work on the nucleate boiling performance of both Freon-113 and water on the composite surfaces has been finished and the results show that the composite surface with 25% volume fraction of graphite fibers in the copper matrix has the best enhancing performance. Stronger enhancement was obtained for water compared to Freon-113. The wall superheat initiating boiling was reduced 40% and 35% and the heat flux of the nucleate boiling was augmented up to ten times and 6.7 times, respectively. A bubble departure model has been presented to explain the enhancement mechanism of the boiling heat transfer on the composite surfaces. A powerful optical method to measure contact angle and spreading parameters of liquids on solid surfaces, including both transparent and non-transparent substrates, has been developed and successfully used in the measurements for various liquid-solid systems. The experimental work on identification of profiles near three-phase line by laser shadowgraphy method has been finished and the characteristics of the three-phase line for different liquid-solid systems were unveiled, which is very important to understand the mechanism of boiling under microgravity conditions. The four basic patterns of sessile profile were discovered through caustics and caustic-diffraction analysis by applying wave theory in shadowgraphy technology, which contributes to clearly explain the different characteristics of wetting and spreading of various liquids on a solid surface, and therefore to further understand the bubble departure mechanisms. A new working pattern of heat pipes using working fluids with positive surface-tension gradient against temperature was discovered and analyzed, and then the new heat pipe systems using this kind of working fluids have been

  15. Enhanced Boiling on Micro-Configured Composite Surfaces Under Microgravity Conditions

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Two experimental setups: High Heat Flux Pool Boiling Setup and Optical system of Measuring Contact Angle and Spreading Parameters were established and a series of experiments was conducted. The experimental work on the nucleate boiling performance of both Freon-113 and water on the composite surfaces has been finished and the results show that the composite surface with 25% volume fraction of graphite fibers in the copper matrix has the best enhancing performance. Stronger enhancement was obtained for water compared to Freon-113. The wall superheat initiating boiling was reduced 40% and 35% and the heat flux of the nucleate boiling was augmented up to ten times and 6.7 times, respectively. A bubble departure model has been presented to explain the enhancement mechanism of the boiling heat transfer on the composite surfaces. A powerful optical method to measure contact angle and spreading parameters of liquids on solid surfaces, including both transparent and non-transparent substrates, has been developed and successfully used in the measurements for various liquid-solid systems. The experimental work on identification of profiles near three-phase line by laser shadowgraphy method has been finished and the characteristics of the three-phase line for different liquid-solid systems were unveiled, which is very important to understand the mechanism of boiling under microgravity conditions. The four basic patterns of sessile profile were discovered through caustics and caustic-diffraction analysis by applying wave theory in shadowgraphy technology, which contributes to clearly explain the different characteristics of wetting and spreading of various liquids on a solid surface, and therefore to further understand the bubble departure mechanisms. A new working pattern of heat pipes using working fluids with positive surface-tension gradient against temperature was discovered and analyzed, and then the new heat pipe systems using this kind of working fluids have been

  16. Telocyte's contacts.

    PubMed

    Faussone-Pellegrini, Maria-Simonetta; Gherghiceanu, Mihaela

    2016-07-01

    Telocytes (TC) are an interstitial cell type located in the connective tissue of many organs of humans and laboratory mammals. By means of homocellular contacts, TC build a scaffold whose meshes integrity and continuity are guaranteed by those contacts having a mechanical function; those contacts acting as sites of intercellular communication allow exchanging information and spreading signals. Heterocellular contacts between TC and a great variety of cell types give origin to mixed networks. TC, by means of all these types of contacts, their interaction with the extracellular matrix and their vicinity to nerve endings, are part of an integrated system playing tissue/organ-specific roles.

  17. Comparison of an alternative schedule of extended care contacts to a self-directed control: a randomized trial of weight loss maintenance.

    PubMed

    Dutton, Gareth R; Gowey, Marissa A; Tan, Fei; Zhou, Dali; Ard, Jamy; Perri, Michael G; Lewis, Cora E

    2017-08-15

    Behavioral interventions for obesity produce clinically meaningful weight loss, but weight regain following treatment is common. Extended care programs attenuate weight regain and improve weight loss maintenance. However, less is known about the most effective ways to deliver extended care, including contact schedules. We compared the 12-month weight regain of an extended care program utilizing a non-conventional, clustered campaign treatment schedule and a self-directed program among individuals who previously achieved ≥5% weight reductions. Participants (N = 108; mean age = 51.6 years; mean weight = 92.6 kg; 52% African American; 95% female) who achieved ≥5% weight loss during an initial 16-week behavioral obesity treatment were randomized into a 2-arm, 12-month extended care trial. A clustered campaign condition included 12 group-based visits delivered in three, 4-week clusters. A self-directed condition included provision of the same printed intervention materials but no additional treatment visits. The study was conducted in a U.S. academic medical center from 2011 to 2015. Prior to randomization, participants lost an average of -7.55 ± 3.04 kg. Participants randomized to the 12-month clustered campaign program regained significantly less weight (0.35 ± 4.62 kg) than self-directed participants (2.40 ± 3.99 kg), which represented a significant between-group difference of 2.28 kg (p = 0.0154) after covariate adjustments. This corresponded to maintaining 87% and 64% of lost weight in the clustered campaign and self-directed conditions, respectively, which was a significant between-group difference of 29% maintenance of lost weight after covariate adjustments, p = 0.0396. In this initial test of a clustered campaign treatment schedule, this novel approach effectively promoted 12-month maintenance of lost weight. Future trials should directly compare the clustered campaigns with conventional (e.g., monthly) extended care schedules

  18. Direct Contact - Sorptive Tape Extraction coupled with Gas Chromatography - Mass Spectrometry to reveal volatile topographical dynamics of lima bean (Phaseolus lunatus L.) upon herbivory by Spodoptera littoralis Boisd.

    PubMed

    Boggia, Lorenzo; Sgorbini, Barbara; Bertea, Cinzia M; Cagliero, Cecilia; Bicchi, Carlo; Maffei, Massimo E; Rubiolo, Patrizia

    2015-04-12

    The dynamics of plant volatile (PV) emission, and the relationship between damaged area and biosynthesis of bioactive molecules in plant-insect interactions, remain open questions. Direct Contact-Sorptive Tape Extraction (DC-STE) is a sorption sampling technique employing non adhesive polydimethylsiloxane tapes, which are placed in direct contact with a biologically-active surface. DC-STE coupled to Gas Chromatography - Mass Spectrometry (GC-MS) is a non-destructive, high concentration-capacity sampling technique able to detect and allow identification of PVs involved in plant responses to biotic and abiotic stresses. Here we investigated the leaf topographical dynamics of herbivory-induced PV (HIPV) produced by Phaseolus lunatus L. (lima bean) in response to herbivory by larvae of the Mediterranean climbing cutworm (Spodoptera littoralis Boisd.) and mechanical wounding by DC-STE-GC-MS. Time-course experiments on herbivory wounding caused by larvae (HW), mechanical damage by a pattern wheel (MD), and MD combined with the larvae oral secretions (OS) showed that green leaf volatiles (GLVs) [(E)-2-hexenal, (Z)-3-hexen-1-ol, 1-octen-3-ol, (Z)-3-hexenyl acetate, (Z)-3-hexenyl butyrate] were associated with both MD and HW, whereas monoterpenoids [(E)-β-ocimene], sesquiterpenoids [(E)-nerolidol] and homoterpenes (DMNT and TMTT) were specifically associated with HW. Up-regulation of genes coding for HIPV-related enzymes (Farnesyl Pyrophosphate Synthase, Lipoxygenase, Ocimene Synthase and Terpene Synthase 2) was consistent with HIPV results. GLVs and sesquiterpenoids were produced locally and found to influence their own gene expression in distant tissues, whereas (E)-β-ocimene, TMTT, and DMNT gene expression was limited to wounded areas. DC-STE-GC-MS was found to be a reliable method for the topographical evaluation of plant responses to biotic and abiotic stresses, by revealing the differential distribution of different classes of HIPVs. The main advantages of this

  19. A review on boiling heat transfer enhancement with nanofluids

    PubMed Central

    2011-01-01

    There has been increasing interest of late in nanofluid boiling and its use in heat transfer enhancement. This article covers recent advances in the last decade by researchers in both pool boiling and convective boiling applications, with nanofluids as the working fluid. The available data in the literature is reviewed in terms of enhancements, and degradations in the nucleate boiling heat transfer and critical heat flux. Conflicting data have been presented in the literature on the effect that nanofluids have on the boiling heat-transfer coefficient; however, almost all researchers have noted an enhancement in the critical heat flux during nanofluid boiling. Several researchers have observed nanoparticle deposition at the heater surface, which they have related back to the critical heat flux enhancement. PMID:21711794

  20. Heat Transfer For Subcooled Flow Boiling In Hypervapotron Configuration

    SciTech Connect

    Chena, Peipei; Wua, Wen; Jonesa, Barclay G.; Newell, Ty A

    2006-07-01

    This work reports on experimental studies that examine subcooled boiling on the enhanced heat transfer surface of hypervapotron structures. The use of simulant fluid (refrigerant R134a) instead of prototypic water allows examination of a full range of subcooled boiling, including up to critical heat flux (CHF). The experimental results are compared to Bjorge's model and Kandlikar's heat transfer correlation in the subcooled boiling region. It is found that the fully developed boiling curve has a slope of about 2.96 (q{sup {approx}} {delta}{sub sat} {sup 2}.{sup 96}), which shows good agreement with Bjorge's recognition for flat surface channels. In addition, Kandlikar's correlation is also able to predict the heat transfer coefficient for the range from net vapor generation (NVG) to the fully developed boiling region with acceptable accuracy. However, the heat transfer curve shows a significant deviation when subcooled boiling approaches CHF. (authors)

  1. Water boiling inside carbon nanotubes: toward efficient drug release.

    PubMed

    Chaban, Vitaly V; Prezhdo, Oleg V

    2011-07-26

    We show using molecular dynamics simulation that spatial confinement of water inside carbon nanotubes (CNTs) substantially increases its boiling temperature and that a small temperature growth above the boiling point dramatically raises the inside pressure. Capillary theory successfully predicts the boiling point elevation down to 2 nm, below which large deviations between the theory and atomistic simulation take place. Water behaves qualitatively different inside narrow CNTs, exhibiting transition into an unusual phase, where pressure is gas-like and grows linearly with temperature, while the diffusion constant is temperature-independent. Precise control over boiling by CNT diameter, together with the rapid growth of inside pressure above the boiling point, suggests a novel drug delivery protocol. Polar drug molecules are packaged inside CNTs; the latter are delivered into living tissues and heated by laser. Solvent boiling facilitates drug release.

  2. A review on boiling heat transfer enhancement with nanofluids.

    PubMed

    Barber, Jacqueline; Brutin, David; Tadrist, Lounes

    2011-04-04

    There has been increasing interest of late in nanofluid boiling and its use in heat transfer enhancement. This article covers recent advances in the last decade by researchers in both pool boiling and convective boiling applications, with nanofluids as the working fluid. The available data in the literature is reviewed in terms of enhancements, and degradations in the nucleate boiling heat transfer and critical heat flux. Conflicting data have been presented in the literature on the effect that nanofluids have on the boiling heat-transfer coefficient; however, almost all researchers have noted an enhancement in the critical heat flux during nanofluid boiling. Several researchers have observed nanoparticle deposition at the heater surface, which they have related back to the critical heat flux enhancement.

  3. Stability monitor experience in German BWRs (boiling water reactor)

    SciTech Connect

    Goldstein, L. ); Fuge, R. ); Seepolt, R. ); Frank, M. )

    1989-11-01

    A digital stability monitor developed by NIS Ingenieurgesellschaft MBH, operable on a personal computer, is in use at three boiling water reactor (BWR) plants in the Federal Republic of Germany (FRG). The device has received the approval of an FRG licensing authority. It has been in operation for 5 yr. The stability monitor is a measurement device used to accurately determine and confirm the boundaries of the exclusion region on the operating power-flow map, and to permit controlled operation through such regions. This is achieved via neutron noise measurements converted to direct readout of decay ratios. It has satisfied regulatory requirements by defining potential unstable operating regions at Kernkraftwerk Isar in the FRG and the high power density Gundremmingen (KRB Units B and C) BWRs.

  4. BOILING WATER REACTOR WITH FEED WATER INJECTION NOZZLES

    DOEpatents

    Treshow, M.

    1963-04-30

    This patent covers the use of injection nozzles for pumping water into the lower ends of reactor fuel tubes in which water is converted directly to steam. Pumping water through fuel tubes of this type of boiling water reactor increases its power. The injection nozzles decrease the size of pump needed, because the pump handles only the water going through the nozzles, additional water being sucked into the tubes by the nozzles independently of the pump from the exterior body of water in which the fuel tubes are immersed. The resulting movement of exterior water along the tubes holds down steam formation, and thus maintains the moderator effectiveness, of the exterior body of water. (AEC)

  5. Quantifying the evolution of flow boiling bubbles by statistical testing and image analysis: toward a general model

    PubMed Central

    Xiao, Qingtai; Xu, Jianxin; Wang, Hua

    2016-01-01

    A new index, the estimate of the error variance, which can be used to quantify the evolution of the flow patterns when multiphase components or tracers are difficultly distinguishable, was proposed. The homogeneity degree of the luminance space distribution behind the viewing windows in the direct contact boiling heat transfer process was explored. With image analysis and a linear statistical model, the F-test of the statistical analysis was used to test whether the light was uniform, and a non-linear method was used to determine the direction and position of a fixed source light. The experimental results showed that the inflection point of the new index was approximately equal to the mixing time. The new index has been popularized and applied to a multiphase macro mixing process by top blowing in a stirred tank. Moreover, a general quantifying model was introduced for demonstrating the relationship between the flow patterns of the bubble swarms and heat transfer. The results can be applied to investigate other mixing processes that are very difficult to recognize the target. PMID:27527065

  6. Quantifying the evolution of flow boiling bubbles by statistical testing and image analysis: toward a general model

    NASA Astrophysics Data System (ADS)

    Xiao, Qingtai; Xu, Jianxin; Wang, Hua

    2016-08-01

    A new index, the estimate of the error variance, which can be used to quantify the evolution of the flow patterns when multiphase components or tracers are difficultly distinguishable, was proposed. The homogeneity degree of the luminance space distribution behind the viewing windows in the direct contact boiling heat transfer process was explored. With image analysis and a linear statistical model, the F-test of the statistical analysis was used to test whether the light was uniform, and a non-linear method was used to determine the direction and position of a fixed source light. The experimental results showed that the inflection point of the new index was approximately equal to the mixing time. The new index has been popularized and applied to a multiphase macro mixing process by top blowing in a stirred tank. Moreover, a general quantifying model was introduced for demonstrating the relationship between the flow patterns of the bubble swarms and heat transfer. The results can be applied to investigate other mixing processes that are very difficult to recognize the target.

  7. Quantifying the evolution of flow boiling bubbles by statistical testing and image analysis: toward a general model.

    PubMed

    Xiao, Qingtai; Xu, Jianxin; Wang, Hua

    2016-08-16

    A new index, the estimate of the error variance, which can be used to quantify the evolution of the flow patterns when multiphase components or tracers are difficultly distinguishable, was proposed. The homogeneity degree of the luminance space distribution behind the viewing windows in the direct contact boiling heat transfer process was explored. With image analysis and a linear statistical model, the F-test of the statistical analysis was used to test whether the light was uniform, and a non-linear method was used to determine the direction and position of a fixed source light. The experimental results showed that the inflection point of the new index was approximately equal to the mixing time. The new index has been popularized and applied to a multiphase macro mixing process by top blowing in a stirred tank. Moreover, a general quantifying model was introduced for demonstrating the relationship between the flow patterns of the bubble swarms and heat transfer. The results can be applied to investigate other mixing processes that are very difficult to recognize the target.

  8. Heat transfer from aluminum surfaces to pool boiling He I

    SciTech Connect

    Huang, Y.; Van Sciver, S.W.

    1996-12-31

    Heat transfer measurements between different aluminum surfaces and pool boiling He I at 4.21 K are reported. The samples are contained in a channel configuration similar to what might be found in a large bath cooled superconducting magnet. Results include heat transfer coefficients in the nucleate and film boiling regimes as well as values for the peak nucleate and minimum film boiling heat flux. The effects of sample orientation and surface condition are also studied.

  9. Heat exchange units boiling process numerical modeling at subatmospheric pressure

    NASA Astrophysics Data System (ADS)

    Slobodina, E. N.; Mikhailov, A. G.

    2017-08-01

    The paper deals with the boiling process mechanism, the results of the boiling intensification methods analysis at subatmospheric pressure are presented. The calculation methodology for the boiling process on the surface performed in the form of capillary slotted channels is represented. Heat transfer coefficients variations calculation dependences defined by analytical and numerical methods applying are described. The heat exchange surface geometrical characteristics impact on the heat exchange capacity in vacuum conditions was investigated.

  10. Nucleate boiling pressure drop in an annulus: Book 4

    SciTech Connect

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of data plots and summary files of temperature measurements.

  11. Nucleate boiling pressure drop in an annulus: Book 8

    SciTech Connect

    Not Available

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of tables of temperature measurements.

  12. Nucleate boiling pressure drop in an annulus: Book 3

    SciTech Connect

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. This document consists of data plots and summary files of temperature measurements.

  13. Nucleate boiling pressure drop in an annulus: Book 2

    SciTech Connect

    Block, J.A.; Crowley, C.; Dolan, F.X.; Sam, R.G.; Stoedefalke, B.H.

    1992-11-01

    The application of the work described in this report is the production reactors at the Savannah River Site, and the context is nuclear reactor safety. The Loss of Coolant Accident (LOCA) scenario considered involves a double-ended break of a primary coolant pipe in the reactor. During a LOCA, the flow through portions of the reactor may reverse direction or be greatly reduced, depending upon the location of the break. The reduced flow rate of coolant (D{sub 2}O) through the fuel assembly channels of the reactor -- downflow in this situation -- can lead to boiling and to the potential for flow instabilities which may cause some of the fuel assembly channels to overheat and melt. That situation is to be avoided. The experimental approach is to provide a test annulus which simulates geometry, materials, and flow conditions in a Mark-22 fuel assembly (Coolant Channel 3) to the extent possible. The annulus has a full-scale geometry, and in fat uses SRL dummy hardware for the inner annulus wall in the ribbed geometry. The materials aluminum. The annulus is uniformly heated in the axial direction, but the circumferential heat flux can be varied to provide ``power tilt`` or asymmetric heating of the inner and outer annulus walls. The test facility uses H{sub 2}O rather than D{sub 2}O, but it includes the effects of dissolved helium gas present in the reactor. The key analysis approaches are: To compare the minima in the measured demand curves with analytical criteria, in particular the Saha-Zuber (1974) model; and to compare the pressure and temperature as a function of length in the annulus with an integral model for flow boiling in a heated channel. Nineteen test series and a total of 178 tests were performed. Testing addressed the effects of: Heat flux; pressure; helium gas; power tilt; ribs; asymmetric heat flux.

  14. Ulceration of the oral mucosa following direct contact with ferrous sulfate in elderly patients: a case report and a review of the French National Pharmacovigilance Database.

    PubMed

    Liabeuf, Sophie; Gras, Valérie; Moragny, Julien; Laroche, Marie-Laure; Andrejak, Michel

    2014-01-01

    To report a series of cases of ulceration of the oral mucosa linked to direct contact with ferrous sulfate in elderly patients. The first case report concerns the occurrence of widespread oral ulceration in an 87-year-old woman with Alzheimer's disease. The ulceration extended from the side of the tongue to the floor of the mouth. No clear explanation was found and various local treatments were ineffective. Once it was realized that the ferrous sulfate tablets (given as an iron supplement) were crushed prior to administration (due to the patient's deglutition disorder), withdrawal of this treatment led to rapid resolution of the ulceration. Nine other cases of oral ulcerations associated with ferrous sulfate were identified in the French National Pharmacovigilance Database. All but one of the patients were over 80 years of age and the youngest patient (a 54-year-old) had dysphagia associated with facial paralysis. Only two other reports of oral ulceration due to ferrous sulfate have been published to date. Mucosal toxicity of ferrous sulfate (which is probably related to oxidative stress) has previously been reported for the hypopharynx, the esophageal lumen, and (after inhalation of a tablet) the tracheobronchial tree. The mucosal toxicity of ferrous sulfate must be taken into account when deglutition disorders are present (as in elderly patients) and appropriate pharmaceutical formulations (such as syrups) should be administered to at-risk patients. The use of iron salts other than ferrous sulfate could be considered.

  15. A theoretical study of a direct contact membrane distillation system coupled to a salt-gradient solar pond for terminal lakes reclamation.

    PubMed

    Suárez, Francisco; Tyler, Scott W; Childress, Amy E

    2010-08-01

    Terminal lakes are water bodies that are located in closed watersheds with the only output of water occurring through evaporation or infiltration. The majority of these lakes, which are commonly located in the desert and influenced by human activities, are increasing in salinity. Treatment options are limited, due to energy costs, and many of these lakes provide an excellent opportunity to test solar-powered desalination systems. This paper theoretically investigates utilization of direct contact membrane distillation (DCMD) coupled to a salt-gradient solar pond (SGSP) for sustainable freshwater production at terminal lakes. A model for heat and mass transport in the DCMD module and a thermal model for an SGSP were developed and coupled to evaluate the feasibility of freshwater production. The construction of an SGSP outside and inside of a terminal lake was studied. As results showed that freshwater flows are on the same order of magnitude as evaporation, these systems will only be successful if the SGSP is constructed inside the terminal lake so that there is little or no net increase in surface area. For the study site of this investigation, water production on the order of 2.7 x 10(-3) m(3) d(-1) per m(2) of SGSP is possible. The major advantages of this system are that renewable thermal energy is used so that little electrical energy is required, the coupled system requires low maintenance, and the terminal lake provides a source of salts to create the stratification in the SGSP.

  16. Zero Boil-Off System Testing

    NASA Technical Reports Server (NTRS)

    Plachta, David W.; Johnson, Wesley L.; Feller, Jeffrey R.

    2015-01-01

    Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASA's future space exploration due to their high specific impulse for rocket motors of upper stages suitable for transporting 10s to 100s of metric tons of payload mass to destinations outside of low earth orbit and for their return. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several months. These losses can be eliminated by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and modulating the cryocooler to control tank pressure. The active thermal control technology being developed by NASA is the reverse turbo-Brayton cycle cryocooler and its integration to the propellant tank through a distributed cooling tubing network coupled to the tank wall. This configuration was recently tested at NASA Glenn Research Center, in a vacuum chamber and cryoshroud that simulated the essential thermal aspects of low Earth orbit, its vacuum and temperature. Testing consisted of three passive tests with the active cryocooler system off, and 7 active tests, with the cryocooler powered up. The test matrix included zero boil-off tests performed at 90 full and 25 full, and several demonstrations at excess cooling capacity and reduced cooling capacity. From this, the tank pressure response with varied cryocooler power inputs was determined. This test series established that the active cooling system integrated with the propellant tank eliminated boil-off and robustly controlled tank pressure.

  17. Boiling Experiment Facility for Heat Transfer Studies in Microgravity

    NASA Technical Reports Server (NTRS)

    Delombard, Richard; McQuillen, John; Chao, David

    2008-01-01

    Pool boiling in microgravity is an area of both scientific and practical interest. By conducting tests in microgravity, it is possible to assess the effect of buoyancy on the overall boiling process and assess the relative magnitude of effects with regards to other "forces" and phenomena such as Marangoni forces, liquid momentum forces, and microlayer evaporation. The Boiling eXperiment Facility is now being built for the Microgravity Science Glovebox that will use normal perfluorohexane as a test fluid to extend the range of test conditions to include longer test durations and less liquid subcooling. Two experiments, the Microheater Array Boiling Experiment and the Nucleate Pool Boiling eXperiment will use the Boiling eXperiment Facility. The objectives of these studies are to determine the differences in local boiling heat transfer mechanisms in microgravity and normal gravity from nucleate boiling, through critical heat flux and into the transition boiling regime and to examine the bubble nucleation, growth, departure and coalescence processes. Custom-designed heaters will be utilized to achieve these objectives.

  18. An assessment of antibacterial activity of three pulp capping materials on Enterococcus faecalis by a direct contact test: An in vitro study

    PubMed Central

    Koruyucu, Mine; Topcuoglu, Nursen; Tuna, E. Bahar; Ozel, Sevda; Gencay, Koray; Kulekci, Guven; Seymen, Figen

    2015-01-01

    Objective: The aim of this in vitro study was to evaluate antimicrobial activities of three different pulp capping materials; Biodentine, mineral trioxide aggregate (MTA) Angelus, and Dycal against Enterococcus faecalis and their durability with time. Materials and Methods: Direct contact test was used for the assessment. Three sets of sealers were mixed and placed on microtiter plate wells: One set was used within 20 min of recommended setting time while others were used after 24-h and 1-week. E. faecalis suspension was placed directly on the materials for 1 h and then transferred to another plate with fresh media. Nine wells of bacteria without the tested cements served as the positive control. One well of the tested cements without bacteria served as the negative control. Bacterial growth was evaluated by a temperature-controlled microplate spectrophotometer for 1-h intervals among 24 h. Data were analyzed using Kruskal–Wallis test. Results: All tested materials showed less bacterial density than the control group. MTA, Biodentine, and Dycal showed significantly higher bacterial density than the control group in freshly mixed samples (P < 0.05). And MTA showed significantly higher antibacterial activity than Dycal (P < 0.05). In 24 h, materials did not show any differences (P > 0.05). MTA and Biodentine samples showed significant differences than Dycal; MTA also showed higher antibacterial activity than control in 1-week samples (P < 0.05). Conclusion: While freshly mixed MTA showed the best antibacterial activity over time, Biodentine had shown similar antibacterial activity to MTA. PMID:26038657

  19. Optimizing the Combination of Smoking and Boiling on Quality of Korean Traditional Boiled Loin (M. longissimus dorsi)

    PubMed Central

    Choi, Yun-Sang; Kim, Hyun-Wook; Kim, Young-Boong; Kim, Cheon-Jei

    2015-01-01

    The combined effects of smoking and boiling on the proximate composition, technological quality traits, shear force, and sensory characteristics of the Korean traditional boiled loin were studied. Cooking loss, processing loss, and shear force were lower in the smoked/boiled samples than those in the control (without smoking treatment) (p<0.05). The results showed that the boiled loin samples between the control and treatment did not differ significantly in protein, fat, or ash contents, or pH values (p>0.05). The treated samples had higher score for overall acceptability than the control (p<0.05). Thus, these results show that the Korean traditional boiled loin treated with smoking for 60 min before boiling had improved physicochemical properties and sensory characteristics. PMID:26761822

  20. Optimizing the Combination of Smoking and Boiling on Quality of Korean Traditional Boiled Loin (M. longissimus dorsi).

    PubMed

    Choi, Yun-Sang; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Kim, Yong-Jae; Jung, Tae-Jun; Kim, Young-Boong; Kim, Cheon-Jei

    2015-01-01

    The combined effects of smoking and boiling on the proximate composition, technological quality traits, shear force, and sensory characteristics of the Korean traditional boiled loin were studied. Cooking loss, processing loss, and shear force were lower in the smoked/boiled samples than those in the control (without smoking treatment) (p<0.05). The results showed that the boiled loin samples between the control and treatment did not differ significantly in protein, fat, or ash contents, or pH values (p>0.05). The treated samples had higher score for overall acceptability than the control (p<0.05). Thus, these results show that the Korean traditional boiled loin treated with smoking for 60 min before boiling had improved physicochemical properties and sensory characteristics.