PROPANE BUBBLE CHAMBER (in Italian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loria, A.; Mittner, P.; Scotoni, I.

1959-03-01

A propane bubble chamber of about two liters volume is described: details concerning the membrane expansion mechanism, the structure of the windows and the illuminating system are given. Some features of the use of it, recently made at the CERN synchrocyclotron, are indicated. (auth)

28. Photocopy of photograph (original print located in LBNL Photo ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. Photocopy of photograph (original print located in LBNL Photo Lab Collection). Photographer unknown. April 1, 1959. Bubble Chamber 722. BUBBLE CHAMBER, WIDE-ANGLE INTERIOR VIEW OF BUILDING 59 - University of California Radiation Laboratory, Bevatron, 1 Cyclotron Road, Berkeley, Alameda County, CA

Dark Matter Limits From a 2L C3F8 Filled Bubble Chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Alan Edward

2015-12-01

The PICO-2L C3F8 bubble chamber search forWeakly Interacting Massive Particle (WIMP) dark matter was operated in the SNOLAB underground laboratory at the same location as the previous CF3I lled COUPP-4kg detector. Neutron calibrations using photoneutron sources in C3F8 and CF3I lled calibration bubble chambers were performed to verify the sensitivity of these target uids to dark matter scattering. This data was combined with similar measurements using a low-energy neutron beam at the University of Montreal and in situ calibrations of the PICO-2L and COUPP-4kg detectors. C3F8 provides much greater sensitivity to WIMP-proton scattering than CF3I in bubble chamber detectors. PICO-2Lmore » searched for dark matter recoils with energy thresholds below 10 keV. Radiopurity assays of detector materials were performed and the expected neutron recoil background was evaluated to be 1.6+0:3« less

Neutron imaging with bubble chambers for inertial confinement fusion

NASA Astrophysics Data System (ADS)

Ghilea, Marian C.

One of the main methods to obtain energy from controlled thermonuclear fusion is inertial confinement fusion (ICF), a process where nuclear fusion reactions are initiated by heating and compressing a fuel target, typically in the form of a pellet that contains deuterium and tritium, relying on the inertia of the fuel mass to provide confinement. In inertial confinement fusion experiments, it is important to distinguish failure mechanisms of the imploding capsule and unambiguously diagnose compression and hot spot formation in the fuel. Neutron imaging provides such a technique and bubble chambers are capable of generating higher resolution images than other types of neutron detectors. This thesis explores the use of a liquid bubble chamber to record high yield 14.1 MeV neutrons resulting from deuterium-tritium fusion reactions on ICF experiments. A design tool to deconvolve and reconstruct penumbral and pinhole neutron images was created, using an original ray tracing concept to simulate the neutron images. The design tool proved that misalignment and aperture fabrication errors can significantly decrease the resolution of the reconstructed neutron image. A theoretical model to describe the mechanism of bubble formation was developed. A bubble chamber for neutron imaging with Freon 115 as active medium was designed and implemented for the OMEGA laser system. High neutron yields resulting from deuterium-tritium capsule implosions were recorded. The bubble density was too low for neutron imaging on OMEGA but agreed with the model of bubble formation. The research done in here shows that bubble detectors are a promising technology for the higher neutron yields expected at National Ignition Facility (NIF).

Acoustic Cluster Therapy: In Vitro and Ex Vivo Measurement of Activated Bubble Size Distribution and Temporal Dynamics.

PubMed

Healey, Andrew John; Sontum, Per Christian; Kvåle, Svein; Eriksen, Morten; Bendiksen, Ragnar; Tornes, Audun; Østensen, Jonny

2016-05-01

Acoustic cluster technology (ACT) is a two-component, microparticle formulation platform being developed for ultrasound-mediated drug delivery. Sonazoid microbubbles, which have a negative surface charge, are mixed with micron-sized perfluoromethylcyclopentane droplets stabilized with a positively charged surface membrane to form microbubble/microdroplet clusters. On exposure to ultrasound, the oil undergoes a phase change to the gaseous state, generating 20- to 40-μm ACT bubbles. An acoustic transmission technique is used to measure absorption and velocity dispersion of the ACT bubbles. An inversion technique computes bubble size population with temporal resolution of seconds. Bubble populations are measured both in vitro and in vivo after activation within the cardiac chambers of a dog model, with catheter-based flow through an extracorporeal measurement flow chamber. Volume-weighted mean diameter in arterial blood after activation in the left ventricle was 22 μm, with no bubbles >44 μm in diameter. After intravenous administration, 24.4% of the oil is activated in the cardiac chambers. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

CONTINUOUSLY SENSITIVE BUBBLE CHAMBER

DOEpatents

Good, R.H.

1959-08-18

A radiation detector of the bubble chamber class is described which is continuously sensitive and which does not require the complex pressure cycling equipment characteristic of prior forms of the chamber. The radiation sensitive element is a gas-saturated liquid and means are provided for establishing a thermal gradient across a region of the liquid. The gradient has a temperature range including both the saturation temperature of the liquid and more elevated temperatures. Thus a supersaturated zone is created in which ionizing radiations may give rise to visible gas bubbles indicative of the passage of the radiation through the liquid. Additional means are provided for replenishing the supply of gas-saturated liquid to maintaincontinuous sensitivity.

A Measurement of the holographic minimum observable beam branching ratio in the Fermilab 15-foot bubble chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aderholz, M.; Aggarwal, M.M.; Akbari, H.

1997-01-01

Holography has been used successfully in combination with conventional optics for the first time in a large cryogenic bubble chamber, the 15-Foot Bubble Chamber at Fermilab, during a physics run. The innovative system combined the reference beam with the object beam, illuminating a conical volume of {approx} 1.4 m{sup 3}. Bubble tracks from neutrino interactions with a width of {approx} 120 {micro}m have been recorded with good contrast. The ratio of intensities of the object light to the reference light striking the film is called the Beam Branching Ratio. We obtained in our experiment an exceedingly small minimum-observable ratio ofmore » (0.54 {+-} 0.21) x 10{sup -7}. The technology has the potential for a wide range of applications.« less

Demonstration of a light-redirecting skylight system at the Palm Springs Chamber of Commerce

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, E.S.; Beltran, L.O.; Selkowitz, S.E.

1996-05-01

As part of a demonstration project to provide a comprehensive energy upgrade to a 294 m{sup 2} (3168 ft{sup 2}) commercial building, an advanced skylight design was developed using optical light control materials and geometry to provide daylight to two adjoining offices. The skylight system was developed using outdoor physical model tests and simulation tools Limited on-site measurements and occupant polls were conducted. Market issues were addressed. The skylight systems were found to improve lighting quality and to control excessive daylight illuminance levels compared to a conventional diffusing bubble skylight. Daylighting principles developed in earlier work for vertical glazing systemsmore » (light shelves and light pipes) were shown to be applicable in skylight designs at full-scale.« less

The relationship of intravascular bubbles to bends at altitude

NASA Technical Reports Server (NTRS)

Krutz, R. W.; Dixon, G. A.; Olson, R. M.; Moore, A. A.

1986-01-01

In response to recent findings attesting to a correlation between intravehicular bubbling and decompression sickness at intermediate altitudes, an attempt was made to define a minimum pressure for a pressure suit which would obviate the need for prebreathing 100 percent oxygen prior to extravehicular activity (EVA). Fifty-seven male subjects were exposed to altitudes ranging from 16,000 to 30,000 ft in two separate protocols. The first was designed to determine a pressure at which no bends occurred if a crewmember were decompressed from a sea level space station pressure just prior to EVA without prebreathing 100 percent oxygen. The other study was designed to define an altitude and exercise regimen at which bends-susceptible and bends-resistant crewmembers could be separated. It is shown that the close association which exists between severe bubbling and bends at a pressure altitude of 4.3 psia (30,000 ft) decreases as pressure is increased and essentially disappears at pressures less than or equal to 7.8 psia (16,000 ft).

Technical Capability Upgrades to the NASA Langley Research Center 8 ft. by 15 ft. Thermal Vacuum Chamber

NASA Technical Reports Server (NTRS)

Thornblom, Mark N.; Beverly, Joshua; O'Connell, Joseph J.; Duncan, Dwight L.

2016-01-01

The 8 ft. by 15 ft. thermal vacuum chamber (TVAC), housed in Building 1250 at the NASA Langley Research Center (LaRC), and managed by the Systems Integration and Test Branch within the Engineering Directorate, has undergone several significant modifications to increase testing capability, safety, and quality of measurements of articles under environmental test. Significant modifications include: a new nitrogen distribution manifold for supplying the shroud and other cold surfaces to liquid nitrogen temperatures; a new power supply and distribution system for accurately controlling a quartz IR lamp suite; a suite of contamination monitoring sensors for outgassing measurements and species identification; a new test article support system; signal and power feed-throughs; elimination of unnecessary penetrations; and a new data acquisition and control commanding system including safety interlocks. This paper will provide a general overview of the LaRC 8 ft. by 15 ft. TVAC chamber, an overview of the new technical capabilities, and will illustrate each upgrade in detail, in terms of mechanical design and predicted performance. Additionally, an overview of the scope of tests currently being performed in the chamber will be documented, and sensor plots from tests will be provided to show chamber temperature and pressure performance with actual flight hardware under test.

Technical Capability Upgrades to the NASA Langley Research Center 6 ft. by 6 ft. Thermal Vacuum Chamber

NASA Technical Reports Server (NTRS)

Thornblom, Mark N.; Beverly, Joshua; O'Connell, Joseph J.; Mau, Johnny C.; Duncan, Dwight L.

2014-01-01

The 6 ft. by 6 ft. thermal vacuum chamber (TVAC), housed in Building 1250 at the NASA Langley Research Center (LaRC), and managed by the Systems Integration and Test Branch within the Engineering Directorate, has undergone several significant modifications to increase testing capability, safety, and quality of measurements of articles under environmental test. Significant modifications include: a new nitrogen thermal conditioning unit for controlling shroud temperatures from -150degC to +150degC; two horizontal auxiliary cold plates for independent temperature control from -150degC to +200degC; a suite of contamination monitoring sensors for outgassing measurements and species identification; signal and power feed-throughs; new pressure gauges; and a new data acquisition and control commanding system including safety interlocks. This presentation will provide a general overview of the LaRC 6 ft. by 6 ft. TVAC chamber, an overview of the new technical capabilities, and illustrate each upgrade in detail, in terms of mechanical design and predicted performance. Additionally, an overview of the scope of tests currently being performed in the chamber will be documented, and sensor plots from tests will be provided to show chamber temperature and pressure performance with actual flight hardware under test.

Acoustic Sensor Design for Dark Matter Bubble Chamber Detectors.

PubMed

Felis, Ivan; Martínez-Mora, Juan Antonio; Ardid, Miguel

2016-06-10

Dark matter bubble chamber detectors use piezoelectric sensors in order to detect and discriminate the acoustic signals emitted by the bubbles grown within the superheated fluid from a nuclear recoil produced by a particle interaction. These sensors are attached to the outside walls of the vessel containing the fluid. The acoustic discrimination depends strongly on the properties of the sensor attached to the outer wall of the vessel that has to meet the requirements of radiopurity and size. With the aim of optimizing the sensor system, a test bench for the characterization of the sensors has been developed. The sensor response for different piezoelectric materials, geometries, matching layers, and backing layers have been measured and contrasted with FEM simulations and analytical models. The results of these studies lead us to have a design criterion for the construction of specific sensors for the next generation of dark matter bubble chamber detectors (250 L).

High-energy Physics with Hydrogen Bubble Chambers

DOE R&D Accomplishments Database

Alvarez, L. W.

1958-03-07

Recent experience with liquid hydrogen bubble chambers of 25 and 40 cm dia. in high-energy physics experiments is discussed. Experiments described are: interactions of K{sup -} mesons with protons, interactions of antiprotons with protons, catalysis of nuclear fusion reactions by muons, and production and decay of hyperons from negative pions. (W.D.M.)

Constraining the GENIE model of neutrino-induced single pion production using reanalyzed bubble chamber data

DOE PAGES

Rodrigues, Philip; Wilkinson, Callum; McFarland, Kevin

2016-08-24

The longstanding discrepancy between bubble chamber measurements of ν μ-induced single pion production channels has led to large uncertainties in pion production cross section parameters for many years. We extend the reanalysis of pion production data in deuterium bubble chambers where this discrepancy is solved to include the ν μn → μ –pπ 0 and ν μn→μ –nπ + channels, and use the resulting data to fit the parameters of the GENIE pion production model. We find a set of parameters that can describe the bubble chamber data better than the GENIE default parameters, and provide updated central values andmore » reduced uncertainties for use in neutrino oscillation and cross section analyses which use the GENIE model. Here, we find that GENIE’s non-resonant background prediction has to be significantly reduced to fit the data, which may help to explain the recent discrepancies between simulation and data observed by the MINERνA coherent pion and NOνA oscillation analyses.« less

Separated two-phase flow and basaltic eruptions

NASA Astrophysics Data System (ADS)

Vergniolle, Sylvie; Jaupart, Claude

1986-11-01

Fluid dynamical models of volcanic eruptions are usually made in the homogeneous approximation where gas and liquid are constrained to move at the same velocity. Basaltic eruptions exhibit the characteristics of separated flows, including transitions in their flow regime, from bubbly to slug flow in Strombolian eruptions and from bubbly to annular flow in Hawaiian ones. These regimes can be characterized by a parameter called the melt superficial velocity, or volume flux per unit cross section, which takes values between 10-3 and 10-2 m/s for bubbly and slug flow, and about 1 m/s for annular flow. We use two-phase flow equations to determine under which conditions the homogeneous approximation is not valid. In the bubbly regime, in which many bubbles rise through the moving liquid, there are large differences between the two-phase and homogeneous models, especially in the predictions of gas content and pressure. The homogeneous model is valid for viscous lavas such as dacites because viscosity impedes bubble motion. It is not valid for basaltic lavas if bubble sizes are greater than 1 cm, which is the case. Accordingly, basaltic eruptions should be characterized by lower gas contents and lower values of the exit pressure, and they rarely erupt in the mist and froth regimes, which are a feature of more viscous lavas. The two-phase flow framework allows for the treatment of different bubble populations, including vesicles due to exsolution by pressure release in the volcanic conduit and bubbles from the magma chamber. This yields information on poorly constrained parameters including the effective friction coefficient for the conduit, gas content, and bubble size in the chamber. We suggest that the observed flow transitions record changes in the amount and size of gas bubbles in the magma chamber at the conduit entry.

A Bubble Chamber Simulator: A New Tool for the Physics Classroom

ERIC Educational Resources Information Center

Gagnon, Michel

2011-01-01

Mainly used in the 1960s, bubble chambers played a major role in particle physics. Now replaced with modern electronic detectors, we believe they remain an important didactic tool to introduce particle physics as they provide visual, appealing and insightful pictures. Sadly, this rare type of detector is mostly accessible through open-door events…

Cleaning of a thermal vacuum chamber with shrouds in place

NASA Technical Reports Server (NTRS)

Bond, William R.

1992-01-01

In February, 1991, a failure of a rotary booster pump caused the diffusion pumps to backstream into a 10 ft x 15 ft thermal vacuum chamber. Concerns existed about the difficulty of removing and reinstalling the shrouds without causing leaks. The time required for the shroud removal was also of concern. These concerns prompted us to attempt to clean the chamber without removing the shrouds.

Measurement of Aluminum Content In Reflector Materials For The PICO Dark Matter Detector

NASA Astrophysics Data System (ADS)

Borsodi, Haley; PICO Collaboration

2015-04-01

The PICO collaboration uses a bubble chamber technique to search for dark matter particles. Bubbles are registered with cameras, pressure sensors and acoustic transducers. To increase the visual contrast between bubbles and liquid, retro-reflectors are used to diffuse light from LEDs evenly throughout the inner chamber. One must, however, be careful that reflector materials not contribute radioactive background. Light nuclei, such as aluminum, can absorb alpha particles from radioactive contaminants and produce high energy neutron background in the inner volume of the chamber. Since aluminum oxides are a common reflector material and since commercial compositions are trade secrets, we had to demonstrate that the amounts of aluminum in the reflectors was small enough to allow them to be used in the chambers. After acid digesting candidate material strips, they were analyzed using Microwave Plasma Atomic Emission Spectroscopy. All of the proposed materials were found to have less than 1% Aluminum content (by mass), making them safe for use by the experiment. Indiana University South Bend.

Anterior Chamber Air Bubble to Achieve Graft Attachment After DMEK: Is Bigger Always Better?

PubMed

Ćirković, Aleksandar; Beck, Christina; Weller, Julia M; Kruse, Friedrich E; Tourtas, Theofilos

2016-04-01

To analyze the influence of the size of the air bubble subsequent to Descemet membrane endothelial keratoplasty (DMEK) surgery on the rate of graft detachment and need for rebubbling, the incidence of pupillary block, and the observed endothelial cell loss. This is a single-center, retrospective, consecutive case series of 74 cases undergoing DMEK and fulfilling the inclusion criteria concerning the size of the air bubble at the end of surgery. Based on the medical records, patients were divided into 2 groups (n = 37, respectively). The first group had an air bubble with a volume of approximately 50% and the second group of approximately 80% of the anterior chamber (AC) volume, respectively. Patients who did not comply with instructions to remain in the supine position until complete resorption of AC air or cases in which difficulties in graft preparation (eg, radial breaks) occurred were excluded from data analysis. The central corneal thickness and endothelial cell density were measured 6 months after surgery. Ten of 37 patients (27.0%) in the 50% air bubble group and 3 of 37 patients (8.1%) in the 80% air bubble group needed 1 rebubbling procedure (P = 0.032). There was no difference between the groups after 6 months regarding endothelial cell density and central corneal thickness. No pupillary block was observed. Larger air bubbles of 80% anterior chamber volume decrease the risk of graft detachment after DMEK with no detrimental effect on the outcome and risk for pupillary block.

A history of radiation detection instrumentation.

PubMed

Frame, Paul W

2004-08-01

A review is presented of the history of radiation detection instrumentation. Specific radiation detection systems that are discussed include the human senses, photography, calorimetry, color dosimetry, ion chambers, electrometers, electroscopes, proportional counters, Geiger Mueller counters, scalers and rate meters, barium platinocyanide, scintillation counters, semiconductor detectors, radiophotoluminescent dosimeters, thermoluminescent dosimeters, optically stimulated luminescent dosimeters, direct ion storage, electrets, cloud chambers, bubble chambers, and bubble dosimeters. Given the broad scope of this review, the coverage is limited to a few key events in the development of a given detection system and some relevant operating principles. The occasional anecdote is included for interest.

A history of radiation detection instrumentation.

PubMed

Frame, Paul W

2005-06-01

A review is presented of the history of radiation detection instrumentation. Specific radiation detection systems that are discussed include the human senses, photography, calorimetry, color dosimetry, ion chambers, electrometers, electroscopes, proportional counters, Geiger Mueller counters, scalers and rate meters, barium platinocyanide, scintillation counters, semiconductor detectors, radiophotoluminescent dosimeters, thermoluminescent dosimeters, optically stimulated luminescent dosimeters, direct ion storage, electrets, cloud chambers, bubble chambers, and bubble dosimeters. Given the broad scope of this review, the coverage is limited to a few key events in the development of a given detection system and some relevant operating principles. The occasional anecdote is included for interest.

Dark Matter Search Results from the PICO -60 C 3F8 Bubble Chamber

NASA Astrophysics Data System (ADS)

Amole, C.; Ardid, M.; Arnquist, I. J.; Asner, D. M.; Baxter, D.; Behnke, E.; Bhattacharjee, P.; Borsodi, H.; Bou-Cabo, M.; Campion, P.; Cao, G.; Chen, C. J.; Chowdhury, U.; Clark, K.; Collar, J. I.; Cooper, P. S.; Crisler, M.; Crowder, G.; Dahl, C. E.; Das, M.; Fallows, S.; Farine, J.; Felis, I.; Filgas, R.; Girard, F.; Giroux, G.; Hall, J.; Harris, O.; Hoppe, E. W.; Jin, M.; Krauss, C. B.; Laurin, M.; Lawson, I.; Leblanc, A.; Levine, I.; Lippincott, W. H.; Mamedov, F.; Maurya, D.; Mitra, P.; Nania, T.; Neilson, R.; Noble, A. J.; Olson, S.; Ortega, A.; Plante, A.; Podviyanuk, R.; Priya, S.; Robinson, A. E.; Roeder, A.; Rucinski, R.; Scallon, O.; Seth, S.; Sonnenschein, A.; Starinski, N.; Štekl, I.; Tardif, F.; Vázquez-Jáuregui, E.; Wells, J.; Wichoski, U.; Yan, Y.; Zacek, V.; Zhang, J.; PICO Collaboration

2017-06-01

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C3 F8 located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO -60 C 3F8 exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4 ×10-41 cm2 for a 30 -GeV c-2 WIMP, more than 1 order of magnitude improvement from previous PICO results.

Improved dark matter search results from PICO-2L Run 2

DOE PAGES

Amole, C.

2016-03-01

New data are reported from a second run of the 2-liter PICO-2L C 3F 8 bubble chamber with a total exposure of 129 kg-days at a thermodynamic threshold energy of 3.3 keV. These data show that measures taken to control particulate contamination in the superheated fluid resulted in the absence of the anomalous background events observed in the first run of this bubble chamber. One single nuclear-recoil event was observed in the data, consistent both with the predicted background rate from neutrons and with the observed rate of unambiguous multiple-bubble neutron scattering events. The chamber exhibits the same excellent electron-recoil and alphamore » decay rejection as was previously reported. These data provide the most stringent direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering to date for WIMP masses <50 GeV/c 2.« less

Around Marshall

NASA Image and Video Library

2002-10-01

This is a ground level view of Test Stand 300 at the east test area of the Marshall Space Flight Center. Test Stand 300 was constructed in 1964 as a gas generator and heat exchanger test facility to support the Saturn/Apollo Program. Deep-space simulation was provided by a 1960 modification that added a 20-ft thermal vacuum chamber and a 1981 modification that added a 12-ft vacuum chamber. The facility was again modified in 1989 when 3-ft and 15-ft diameter chambers were added to support Space Station and technology programs. This multiposition test stand is used to test a wide range of rocket engine components, systems, and subsystems. It has the capability to simulate launch thermal and pressure profiles. Test Stand 300 was designed for testing solid rocket booster (SRB) insulation panels and components, super-insulated tanks, external tank (ET) insulation panels and components, Space Shuttle components, solid rocket motor materials, and advanced solid rocket motor materials.

Continuous-wave laser generated jets for needle free applications

PubMed Central

Visser, Claas Willem; Schlautmann, Stefan

2016-01-01

We designed and built a microfluidic device for the generation of liquid jets produced by thermocavitation. A continuous wave (CW) laser was focused inside a micro-chamber filled with a light-absorbing solution to create a rapidly expanding vapor bubble. The chamber is connected to a micro-channel which focuses and ejects the liquid jet through the exit. The bubble growth and the jet velocity were measured as a function of the devices geometry (channel diameter D and chamber width A). The fastest jets were those for relatively large chamber size with respect to the channel diameter. Elongated and focused jets up to 29 m/s for a channel diameter of 250 μm and chamber size of 700 μm were obtained. The proposed CW laser-based device is potentially a compact option for a practical and commercially feasible needle-free injector. PMID:26858816

Temperature change rate actuated bubble mixing for homogeneous rehydration of dry pre-stored reagents in centrifugal microfluidics.

PubMed

Hin, S; Paust, N; Keller, M; Rombach, M; Strohmeier, O; Zengerle, R; Mitsakakis, K

2018-01-16

In centrifugal microfluidics, dead volumes in valves downstream of mixing chambers can hardly be avoided. These dead volumes are excluded from mixing processes and hence cause a concentration gradient. Here we present a new bubble mixing concept which avoids such dead volumes. The mixing concept employs heating to create a temperature change rate (TCR) induced overpressure in the air volume downstream of mixing chambers. The main feature is an air vent with a high fluidic resistance, representing a low pass filter with respect to pressure changes. Fast temperature increase causes rapid pressure increase in downstream structures pushing the liquid from downstream channels into the mixing chamber. As air further penetrates into the mixing chamber, bubbles form, ascend due to buoyancy and mix the liquid. Slow temperature/pressure changes equilibrate through the high fluidic resistance air vent enabling sequential heating/cooling cycles to repeat the mixing process. After mixing, a complete transfer of the reaction volume into the downstream fluidic structure is possible by a rapid cooling step triggering TCR actuated valving. The new mixing concept is applied to rehydrate reagents for loop-mediated isothermal amplification (LAMP). After mixing, the reaction mix is aliquoted into several reaction chambers for geometric multiplexing. As a measure for mixing efficiency, the mean coefficient of variation (C[combining macron]V[combining macron], n = 4 LabDisks) of the time to positivity (t p ) of the LAMP reactions (n = 11 replicates per LabDisk) is taken. The C[combining macron]V[combining macron] of the t p is reduced from 18.5% (when using standard shake mode mixing) to 3.3% (when applying TCR actuated bubble mixing). The bubble mixer has been implemented in a monolithic fashion without the need for any additional actuation besides rotation and temperature control, which are needed anyhow for the assay workflow.

A stable and convenient protein electrophoresis titration device with bubble removing system.

PubMed

Zhang, Qiang; Fan, Liu-Yin; Li, Wen-Lin; Cong, Feng-Song; Zhong, Ran; Chen, Jing-Jing; He, Yu-Chen; Xiao, Hua; Cao, Cheng-Xi

2017-07-01

Moving reaction boundary titration (MRBT) has a potential application to immunoassay and protein content analysis with high selectivity. However, air bubbles often impair the accuracy of MRBT, and the leakage of electrolyte greatly decreases the safety and convenience of electrophoretic titration. Addressing these two issues a reliable MRBT device with modified electrolyte chamber of protein titration was designed. Multiphysics computer simulation was conducted for optimization according to two-phase flow. The single chamber was made of two perpendicular cylinders with different diameters. After placing electrophoretic tube, the resident air in the junction next to the gel could be eliminated by a simple fast electrolyte flow. Removing the electrophoretic tube automatically prevented electrolyte leakage at the junction due to the gravity-induced negative pressure within the chamber. Moreover, the numerical simulation and experiments showed that the improved MRBT device has following advantages: (i) easy and rapid setup of electrophoretic tube within 20 s; (ii) simple and quick bubble dissipates from the chamber of titration within 2 s; (iii) no electrolyte leakage from the two chambers: and (iv) accurate protein titration and safe instrumental operation. The developed technique and apparatus greatly improves the performance of the previous MRBT device, and providing a new route toward practical application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Space shuttle orbit maneuvering engine reusable thrust chamber: Adverse operating conditions test report

NASA Technical Reports Server (NTRS)

Tobin, R. D.

1974-01-01

Test hardware, facilities, and procedures are described along with results of electrically heated tube and channel tests conducted to determine adverse operating condition limits for convectively cooled chambers typical of Space Shuttle Orbit Manuevering Engine designs. Hot-start tests were conducted with corrosion resistant steel and nickel tubes with both monomethylhydrazine and 50-50 coolants. Helium ingestion, in both bubble and froth form, was studied in tubular test sections. Helium bubble ingestion and burn-out limits in rectangular channels were also investigated.

Dark Matter Search Results from the PICO-60 C$$_3$$F$$_8$$ Bubble Chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amole, C.; et al.

2017-02-24

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of Cmore » $$_3$$F$$_8$$ located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C$$_3$$F$$_8$$ exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than 1 event per month. A blind analysis of an efficiency-corrected 1167-kg-day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the WIMP-proton spin-dependent cross section at 3.4 $$\\times$$ 10$$^{-41}$$ cm$^2$ for a 30-GeV$$\\thinspace$$c$$^{-2}$$ WIMP, more than one order of magnitude improvement from previous PICO results.« less

Microjet Penetrator - medical use of laser induced shock waves and bubbles

NASA Astrophysics Data System (ADS)

Yoh, Jack

2013-06-01

The laser-driven microjet penetrator system accelerates liquids drug and delivers them without a needle, which is shown to overcome the weaknesses of existing piston-driven jet injectors. The system consists of two back-to-back chambers separated by a rubber membrane, one containing ``driving'' water behind another of the liquid drug to be delivered. The laser pulse is sent once, and a bubble forms in the water chamber, which puts elastic strain on the membrane, causing the drug to be forcefully ejected from a miniature nozzle in a narrow jet of 150 micron in diameter. The impacting jet pressure is higher than the skin tensile strength and thus causes the jet to penetrate into the targeted depth underneath the skin. Multiple pulses of the laser increase the desired dosage. The experiments are performed with commercially available Nd:YAG and Er:YAG lasers for clinical applications in laser dermatology and dentistry. The difference in bubble behavior within the water chamber comes from pulse duration and wavelength. For Nd:YAG laser, the pulse duration is very short relative to the bubble lifetime making the bubble behavior close to that of a cavitation bubble (inertial), while in Er:YAG case the high absorption in water and the longer pulse duration change the initial behavior of the bubble making it close to a vapor bubble (thermal). The contraction and subsequent rebound for both cases were seen typical of cavitation bubble. The laser-induced microjet penetrators generate velocities which are sufficient for delivery of drug into a guinea-pig skin for both laser beams of different pulse duration and wavelength. We estimate the typical velocity within 30-80 m/s range and the breakup length to be larger than 1 mm, thus making it a contamination-free medical procedure. Hydrodynamic theory confirms the nozzle exit jet velocity obtained by the microjet system. A significant increase in the delivered dose of drugs is achieved with multiple pulses of a 2.9 μm Er:YAG laser at 250 μs pulse duration. At this wavelength, the beam is best absorbable by water. Further, to increase the bubble size, a sapphire based fiber tip is entered into a water chamber as a beam is gathered at the bottom of this fiber tip's conical end, which is polished at an angle graduated from 30° over the full core diameter. The power density at the exit of the conical fiber tip is increased in comparison with the direct radiation at water. The water superheats and thus a larger bubble forms right at the tip. The bubble is typically an elongated (stretched) shape in case of a direct laser irradiation in water, but when light is irradiated through a conical fiber tip, the resulting bubble is an enlarged spherical bubble which is several times larger in its volume when compared to the direct beam radiation in water. In this talk, a review of our recent research effort in achieving high-throughput injection of drug via the microjet penetrator is given with its potential medical applications. The financial support is provided by National Research Foundation of Korea (DOYAK-2010).

Tank fragmentation test

NASA Technical Reports Server (NTRS)

Daye, C. J.; Cooksey, D.; Walters, R. J.; Auble, A. E.

1973-01-01

A photographic study of a simulated tank fragmentation test was made. Sixteen disks and four spheres were ejected from a test article mounted in a vertical orientation 110 ft above a target installed on the test chamber floor. The test was performed at a chamber pressure of 25 microns. Velocities at impingement on the target ranged from 88 to 120 ft/sec; corresponding ejection velocities at the exit plane of the ejector assembly ranged from 29 to 87 ft/sec. Tumble axes of the disks were expected to be all in the north-south direction; the majority of those measured were, while some were skewed from this direction, the maximum observed being 90 deg. A typical measured tumble rate was 2.4 turns/sec. The dispersion pattern measured on the target was reasonably regular, and measured approximately 16 ft east-to-west by 11 ft north-to-south.

Anterior chamber gas bubble emergence pattern during femtosecond LASIK-flap creation.

PubMed

Robert, Marie-Claude; Khreim, Nour; Todani, Amit; Melki, Samir A

2015-09-01

To characterise the emergence pattern of cavitation bubbles into the anterior chamber (AC) following femtosecond laser-assisted in situ keratomileusis (LASIK)-flap creation Retrospective review of patients undergoing femtosecond LASIK surgery at Boston Laser, a private refractive surgery practice in Boston, Massachusetts, between December 2008 and February 2014. Patient charts were reviewed to identify all cases with gas bubble migration into the AC. Surgical videos were examined and the location of bubble entry was recorded separately for right and left eyes. Five thousand one hundred and fifty-eight patients underwent femtosecond LASIK surgery. Air bubble migration into the AC, presumably via the Schlemm's canal and trabecular meshwork, occurred in 1% of cases. Patients with AC bubbles had an average age of 33±8 years with a measured LASIK flap thickness of 96±21 μm. The occurrence of gas bubbles impaired iris registration in 64% of cases. Gas bubbles appeared preferentially in the nasal or inferior quadrants for right (92% of cases) and left (100% of cases) eyes. This bubble emergence pattern is significantly different from that expected with a random distribution (p<0.0001) and did not seem associated with decentration of the femtosecond laser docking system. The migration of gas bubbles into the AC is a rare occurrence during femtosecond laser flap creation. The preferential emergence of gas bubbles into the nasal and inferior quadrants of the AC may indicate a distinctive anatomy of the nasal Schlemm's canal. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Results of an On-Going Long Duration Ground Test of the DS1 Flight Spare Engine

NASA Technical Reports Server (NTRS)

Anderson, John R.; Goodfellow, Keith D.; Polk, James E.; Shotwell, Robert F.; Rawlin, Vincent K.; Sovey, James S.; Patterson, Michael J.

2000-01-01

Ground testing of the DS1 night spare thruster (FT2) is presently being conducted. To date, the thruster has accumulated over 4500 hours of operation. Comparison of FT2 with the performance of the engineering model thruster 2 (EMT2) during the 8.2 khr test shows a transient, lasting for about 3000 hours, during which the discharge chamber efficiency decreases for both thrusters. The flow rates are 2% lower for FT2 than for EMT2 and the discharge chamber performance is 4.5% lower for FT2 during the transient. Sensitivity data obtained during the test show that the lower flow rate accounts for about half of the observed difference. After the initial transients decay, the performance of both thrusters is comparable with the exception of the electron backstreaming margin--which is 6 V lower for FT2.

Experiments on the effects of nanoparticles on subcooled nucleate pool boiling

NASA Astrophysics Data System (ADS)

Kangude, Prasad; Bhatt, Dhairya; Srivastava, Atul

2018-05-01

The effect of nanoparticles on a single bubble-based nucleate pool boiling phenomenon under subcooled conditions has been studied. Water (as the base fluid) and two different concentrations of water-silica nanofluids (0.005% and 0.01% V/V) have been employed as the working fluids. The boiling experiments have been conducted in a specially designed chamber, wherein an ITO-coated heater substrate has been used to induce single bubble nucleation. Measurements have been performed in a completely non-intrusive manner using one of the refractive index-based diagnostics techniques, namely, rainbow schlieren deflectometry. Thus, the thermal gradients prevailing in the boiling chamber have directly been mapped as a two-dimensional distribution of hue values that are recorded in the form of rainbow schlieren images. The schlieren-based measurements clearly revealed the plausible influence of nanoparticles on the strength of temperature gradients prevailing in the boiling chamber. As compared to the base fluid, the experiments with dilute nanofluids showed that the suspended nanoparticles tend to diffuse (homogenize) the strength of temperature gradients, both in the vicinity of the heated substrate and in the thermal boundary layer enveloping the vapor bubble. An overall reduction in the bubble volume and dynamic contact angle was seen with increasing concentrations of dilute nanofluids. In addition, the vapor bubble was found to assume a more spherical shape at higher concentrations of dilute nanofluids in comparison to its shape with water-based experiments. Clear oscillations of the vapor bubble in the subcooled pool of liquids (water and/or nanofluids) were observed, the frequency of which was found to be significantly reduced as the nanoparticle concentration was increased from 0% (water) to 0.01% (V/V). A force balance analysis has been performed to elucidate the plausible mechanisms explaining the observed trends of the oscillation frequencies of the vapor bubble.

Pressure increases, the formation of chromite seams, and the development of the ultramafic series in the Stillwater Complex, Montana

USGS Publications Warehouse

Lipin, B.R.

1993-01-01

This paper explores the hypothesis that chromate seams in the Stillwater Complex formed in response to periodic increases in total pressure in the chamber. Total pressure increased because of the positive ??V of nucleation of CO2 bubbles in the melt and their subsequent rise through the magma chamber, during which the bubbles increased in volume by a factor of 4-6. By analogy with the pressure changes in the summit chambers of Kilauea and Krafla volcanoes, the maximum variation was 0.2-0.25 kbar, or 5-10% of the total pressure in the Stillwater chamber. An evaluation of the likelihood of fountaining and mixing of a new, primitive liquid that entered the chamber with the somewhat more evolved liquid already in the chamber is based upon calculations using observed and inferred velocities and flow rates of basaltic magmas moving through volcanic fissures. The calculations indicate that hot, dense magma would have oozed, rather than fountained into the chamber, and early mixing of the new and residual magmas that could have resulted in chromite crystallizing alone did not take place. -from Author

Current leakage for low altitude satellites - Modeling applications. [simulation of high voltage solar cell array in ionospheric plasma environment

NASA Technical Reports Server (NTRS)

Konradi, A.; Mccoy, J. E.; Garriott, O. K.

1979-01-01

To simulate the behavior of a high voltage solar cell array in the ionospheric plasma environment, the large (90 ft x 55 ft diameter) vacuum chamber was used to measure the high-voltage plasma interactions of a 3 ft x 30 ft conductive panel. The chamber was filled with Nitrogen and Argon plasma at electron densities of up to 1,000,000 per cu cm. Measurements of current flow to the plasma were made in three configurations: (a) with one end of the panel grounded, (b) with the whole panel floating while a high bias was applied between the ends of the panel, and (c) with the whole panel at high negative voltage with respect to the chamber walls. The results indicate that a simple model with a constant panel conductivity and plasma resistance can adequately describe the voltage distribution along the panel and the plasma current flow. As expected, when a high potential difference is applied to the panel ends more than 95% of the panel floats negative with respect to the plasma.

Layered storage of biogenic methane-enriched gas bubbles in peat: A lumped capacitance model controlled by soil structure

NASA Astrophysics Data System (ADS)

Chen, X.; Comas, X.; Binley, A. M.; Slater, L. D.

2017-12-01

Methane can accumulate in the gaseous phase in peats, and enter the atmosphere as gas bubbles with a mass flux higher than that via diffusion and plant-mediated pathways. A complete understanding of the mechanisms regulating bubble storage in peats remains incomplete. We developed a layered model to quantify the storage of gas bubbles over a peat column based on a general lumped capacitance model. This conceptual model was applied to explain the effects of peat structure on bubble storage at different depths observed in a laboratory experiment. A peat monolith was collected from the Everglades, a subtropical wetland located in Florida (USA), and kept submerged in a cuboid chamber over 102 days until gas bubble saturation was achieved. Time-lapse ground-penetrating radar (GPR) was used to estimate changes in gas content of each layer and the corresponding average dimensions of stored gas bubbles. The results highlight a hotspot layer of bubble accumulation at depths between 5 and 10 cm below the monolith surface. Bubbles in this shallow hotspot layer were larger relative to those in deeper layers, whilst the degree of decomposition of the upper layers was generally smaller than that of the lower layers based on von Post humification tests. X-ray Computer tomography (CT) was applied to resin-impregnated peat sections from different depths and the results showed that a higher porosity promotes bubbles storage. The stored gas bubbles were released by changing water levels and the air CH4 concentrations above the peat monolith were measured using a flow-through chamber system to confirm the high CH4 concentration in the stored bubbles. Our findings suggest that bubble capacitance is related to the difference in size between gas bubbles and peat pores. This work has implications for better understanding how changes in water table elevation associated with climate change and sea level rise (particularly for freshwater wetlands near coastal areas like the Everglades) may potentially alter bubble sizes, thus bubble storage in peats.

DESIGN OF A PATTERN RECOGNITION DIGITAL COMPUTER WITH APPLICATION TO THE AUTOMATIC SCANNING OF BUBBLE CHAMBER NEGATIVES

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCormick, B.H.; Narasimhan, R.

1963-01-01

The overall computer system contains three main parts: an input device, a pattern recognition unit (PRU), and a control computer. The bubble chamber picture is divided into a grid of st run. Concent 1-mm squares on the film. It is then processed in parallel in a two-dimensional array of 1024 identical processing modules (stalactites) of the PRU. The array can function as a two- dimensional shift register in which results of successive shifting operations can be accumulated. The pattern recognition process is generally controlled by a conventional arithmetic computer. (A.G.W.)

Evaluation of the Radar Stage Sensor manufactured by Forest Technology Systems—Results of laboratory and field testing

USGS Publications Warehouse

Kunkle, Gerald A.

2018-01-31

Two identical Radar Stage Sensors from Forest Technology Systems were evaluated to determine if they are suitable for U.S. Geological Survey (USGS) hydrologic data collection. The sensors were evaluated in laboratory conditions to evaluate the distance accuracy of the sensor over the manufacturer’s specified operating temperatures and distance to water ranges. Laboratory results were compared to the manufacturer’s accuracy specification of ±0.007 foot (ft) and the USGS Office of Surface Water (OSW) policy requirement that water-level sensors have a measurement uncertainty of no more than 0.01 ft or 0.20 percent of the indicated reading. Both of the sensors tested were within the OSW policy requirement in both laboratory tests and within the manufacturer’s specification in the distance to water test over tested distances from 3 to 15 ft. In the temperature chamber test, both sensors were within the manufacturer’s specification for more than 90 percent of the data points collected over a temperature range of –40 to +60 degrees Celsius at a fixed distance of 8 ft. One sensor was subjected to an SDI-12 communication test, which it passed. A field test was conducted on one sensor at a USGS field site near Landon, Mississippi, from February 5 to March 29, 2016. Water-level measurements made by the radar during the field test were in agreement with those made by the Sutron Accubar Constant Flow Bubble Gauge.Upon the manufacturer’s release of updated firmware version 1.09, additional SDI-12 and temperature testing was performed to evaluate added SDI-12 functions and verify that performance was unaffected by the update. At this time, an Axiom data logger is required to perform a firmware update on this sensor. The data confirmed the results of the original test. Based on the test results, the Radar Stage Sensor is a suitable choice for USGS hydrologic data collection.

High-resolution recording of particle tracks with in-line holography in a large cryogenic bubble chamber

NASA Astrophysics Data System (ADS)

Harigel, Gert G.

2000-10-01

Holography has been used successfully in combination with conventional optics for the first time in a large cryogenic bubble chamber, the 15-Foot Bubble Chamber at the Fermi National Accelerator Laboratory (FNAL), during a physics run in a high energy neutrino beam. The innovative system combined the reference beam with the object beam, irradiating a conical volume of approx1.5m3. Bubble tracks from neutrino interactions with a width of approx 120 micrometers have been recorded with good contrast. The ratio of intensities of the object light to the reference light striking the film is called the beam branching ratio (BBR). We obtained in our experiment an exceedingly small minimum- observable ration of BBR = (0.54 divided by 0.21) x 107. The technology has the potential for a wide range of applications. This paper describes the various difficulties in achieving the success. It required the development of laser pulse stretching via enhanced closed loop control with slow Q- switching, to overcome excessive heating of the cryogenic liquid by the powerful laser beam. A sophisticated system of light-absorbing baffles had to be installed to avoid stray light reaching the holographic film. Optical decoupling of classical and holographic illumination systems was required. Real and virtual image replay machines for holograms were built, tailored to our illumination technique.

Model investigation of inlet plenum flow straightening techniques for altitude test facility

NASA Technical Reports Server (NTRS)

Riddlebaugh, S. M.; Linke, H. G.

1976-01-01

An investigation was conducted to evaluate and improve the quality of the airflow to be supplied to the engine in altitude test chambers 3 and 4 of the Propulsion Systems Laboratory at the Lewis Research Center. One-twentieth-scale models of the inlet plenum chamber of the two test chambers were used in the investigation to minimize time and cost. It was possible to reduce the velocity spread in the inlet plenum from approximately 100 m/sec (330 ft/sec) to approximately 10 m/sec (30 ft/sec) through the combined use of flow diverters, multiple spaced screens, flow straighteners, and turning vanes.

National Program for Inspection of Non-Federal Dams. Reuben Hart Reservoir Dam (CT 00096), Naugatuck River Basin, Torrington, Connecticut. Phase I Inspection Report.

DTIC Science & Technology

1978-10-01

24 in. dia. pipe, which turns 90° about 100 ft. from the toe, where a valve controls discharges through an 18 in. dia. pipe into a small pond on Hart...tower to a chamber about 100 ft. beyond the downstream toe of the dam where a control valve is housed. Two 18 in. dia. pipes are carried under the...dam and then join into one 24 in. dia. pipe continuing to the valve chamber. The outlet pipe turns 90 degrees at the chamber and reduces to 18 in

Evaluation of a passenger mask modified with a rebreather bag for protection from smoke and fumes.

DOT National Transportation Integrated Search

1985-10-01

A series of experiments were conducted in an altitude chamber at ground level, 8,000 ft, 14,000 ft, and 21,500 ft, both with and without exercise, to evaluate the potential for providing protection from smoke and fumes for airline passengers while we...

Detecting cavitation in mercury exposed to a high-energy pulsed proton beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manzi, Nicholas J; Chitnis, Parag V; Holt, Ray G

2010-01-01

The Oak Ridge National Laboratory Spallation Neutron Source employs a high-energy pulsed proton beam incident on a mercury target to generate short bursts of neutrons. Absorption of the proton beam produces rapid heating of the mercury, resulting in the formation of acoustic shock waves and the nucleation of cavitation bubbles. The subsequent collapse of these cavitation bubbles promote erosion of the steel target walls. Preliminary measurements using two passive cavitation detectors (megahertz-frequency focused and unfocused piezoelectric transducers) installed in a mercury test target to monitor cavitation generated by proton beams with charges ranging from 0.041 to 4.1 C will bemore » reported on. Cavitation was initially detected for a beam charge of 0.082 C by the presence of an acoustic emission approximately 250 s after arrival of the incident proton beam. This emission was consistent with an inertial cavitation collapse of a bubble with an estimated maximum bubble radius of 0.19 mm, based on collapse time. The peak pressure in the mercury for the initiation of cavitation was predicted to be 0.6 MPa. For a beam charge of 0.41 C and higher, the lifetimes of the bubbles exceeded the reverberation time of the chamber (~300 s), and distinct windows of cavitation activity were detected, a phenomenon that likely resulted from the interaction of the reverberation in the chamber and the cavitation bubbles.« less

Isothermal gas-liquid flow at reduced gravity

NASA Technical Reports Server (NTRS)

Dukler, A. E.

1990-01-01

Research on adiabatic gas-liquid flows under reduced gravity condition is presented together with experimental data obtained using a NASA-Lewis RC 100-ft drop tower and in a LeRC Learjet. It is found that flow patterns and characteristics remain unchanged after the first 1.5 s into microgravity conditions and that the calculated time for a continuity wave to traverse the test section is less than 1.2 s. It is also found that the dispersed bubbles move at the same velocity as that of the front of the slug and that the transition between bubbly and slug flow is insensitive to diameter. Both the bubbly and the slug flows are suggested to represent a continuum of the same physical process. The characteristics of annular, slug, and bubbly flows are compared.

In vitro study of bovine oligodendroglia.

PubMed

Fewster, M E; Blackstone, S

1975-12-01

Oligodendroglia were prepared by 'Ficoll' density gradient centrifugation from the centrum ovale of fetal and adult bovine brains. When cultivated in Rose Chambers, and provided an air bubble was included in the chamber during the cultivation, processes developed on cells around the circumference of the bubble. A sizeable air phase seems to be important for process formation in isolated bovine glial preparations. Various culture systems, media and additions to the cultures were examined for their effect on the behavior of the cultures. Fibroblast overgrowth occurred in oligodendroglial cultures from fetal brains in media supplemented with fetal bovine serum (FBS) but not in medium 199 supplemented with 2.5% FBS.

PICASSO, COUPP and PICO - Search for dark matter with bubble chambers

DOE PAGES

Amole, C.; Ardid, M.; Asner, D. M.; ...

2015-05-29

The PICASSO and COUPP collaborations use superheated liquid detectors to search for cold dark matter through the direct detection of weakly interacting massive particles (WIMPs). These experiments, located in the underground laboratory of SNOLAB, Canada, detect phase transitions triggered by nuclear recoils in the keV range induced by interactions with WIMPs. We present details of the construction and operation of these detectors as well as the results, obtained by several years of observations. We also introduce PICO, which is a joint effort of the two collaborations to build a second generation ton-scale bubble chamber with 250 liters of active liquid.

Bubble chambers for experiments in nuclear astrophysics

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiGiovine, B.; Henderson, D.; Holt, R. J.

A bubble chamber has been developed to be used as an active target system for low energy nuclear astrophysics experiments. Adopting ideas from dark matter detection with superheated liquids, a detector system compatible with gamma-ray beams has been developed. This detector alleviates some of the limitations encountered in standard measurements of the minute cross sections of interest to stellar environments. While the astrophysically relevant nuclear reaction processes at hydrostatic burning temperatures are dominated by radiative captures, in this experimental scheme we measure the time reversed processes. Such photodisintegrations allow us to compute the radiative capture cross sections when transitions tomore » excited states of the reaction products are negligible. Due to the transformation of phase space, the photodisintegration cross-sections are up to two orders of magnitude higher. The main advantage of the new target-detector system is a density several orders of magnitude higher than conventional gas targets. Also, the detector is virtually insensitive to the gamma-ray beam itself, thus allowing us to detect only the products of the nuclear reaction of interest. The development and the operation as well as the advantages and disadvantages of the bubble chamber are discussed.« less

Electrohydrodynamic bubbling: an alternative route to fabricate porous structures of silk fibroin based materials.

PubMed

Ekemen, Zeynep; Ahmad, Zeeshan; Stride, Eleanor; Kaplan, David; Edirisinghe, Mohan

2013-05-13

Conventional fabrication techniques and structures employed in the design of silk fibroin (SF) based porous materials provide only limited control over pore size and require several processing stages. In this study, it is shown that, by utilizing electrohydrodynamic bubbling, not only can new hollow spherical structures of SF be formed in a single step by means of bubbles, but the resulting bubbles can serve as pore generators when dehydrated. The bubble characteristics can be controlled through simple adjustments to the processing parameters. Bubbles with diameters in the range of 240-1000 μm were fabricated in controlled fashion. FT-IR characterization confirmed that the rate of air infused during processing enhanced β-sheet packing in SF at higher flow rates. Dynamic mechanical analysis also demonstrated a correlation between air flow rate and film tensile strength. Results indicate that electrohydrodynamically generated SF and their composite bubbles can be employed as new tools to generate porous structures in a controlled manner with a range of potential applications in biocoatings and tissue engineering scaffolds.

Oscillating microbubbles for selective particle sorting in acoustic microfluidic devices

NASA Astrophysics Data System (ADS)

Rogers, Priscilla; Xu, Lin; Neild, Adrian

2012-05-01

In this study, acoustic waves were used to excite a microbubble for selective particle trapping and sorting. Excitation of the bubble at its volume resonance, as necessary to drive strong fluid microstreaming, resulted in the particles being either selectively attracted to the bubble or continuing to follow the local microstreamlines. The operating principle exploited two acoustic phenomena acting on the particle suspension: the drag force arising from the acoustic microstreaming and the secondary Bjerknes force, i.e. the attractive radiation force produced between an oscillating bubble and a non-buoyant particle. It was also found that standing wave fields within the fluid chamber could be used to globally align bubbles and particles for local particle sorting by the bubble.

The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR 1000 plus.

PubMed

Bohm, Tim D; Griffin, Sheridan L; DeLuca, Paul M; DeWerd, Larry A

2005-04-01

The determination of the air kerma strength of a brachytherapy seed is necessary for effective treatment planning. Well ionization chambers are used on site at therapy clinics to determine the air kerma strength of seeds. In this work, the response of the Standard Imaging HDR 1000 Plus well chamber to ambient pressure is examined using Monte Carlo calculations. The experimental work examining the response of this chamber as well as other chambers is presented in a companion paper. The Monte Carlo results show that for low-energy photon sources, the application of the standard temperature pressure PTP correction factor produces an over-response at the reduced air densities/pressures corresponding to high elevations. With photon sources of 20 to 40 keV, the normalized PTP corrected chamber response is as much as 10% to 20% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. At air densities corresponding to an elevation of 1524 m (5000 ft), the normalized PTP-corrected chamber response is 5% to 10% over unity for these photon sources. With higher-energy photon sources (>100 keV), the normalized PTP corrected chamber response is near unity. For low-energy beta sources of 0.25 to 0.50 MeV, the normalized PTP-corrected chamber response is as much as 4% to 12% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. Higher-energy beta sources (>0.75 MeV) have a normalized PTP corrected chamber response near unity. Comparing calculated and measured chamber responses for common 103Pd- and 125I-based brachytherapy seeds show agreement to within 2.7% and 1.9%, respectively. Comparing MCNP calculated chamber responses with EGSnrc calculated chamber responses show agreement to within 3.1% at photon energies of 20 to 40 keV. We conclude that Monte Carlo transport calculations accurately model the response of this well chamber. Further, applying the standard PTP correction factor for this well chamber is insufficient in accounting for the change in chamber response with air pressure for low-energy (<100 keV) photon and low-energy (<0.75 MeV)beta sources.

Evaluation of Gas Phase Dispersion in Flotation under Predetermined Hydrodynamic Conditions

NASA Astrophysics Data System (ADS)

Młynarczykowska, Anna; Oleksik, Konrad; Tupek-Murowany, Klaudia

2018-03-01

Results of various investigations shows the relationship between the flotation parameters and gas distribution in a flotation cell. The size of gas bubbles is a random variable with a specific distribution. The analysis of this distribution is useful to make mathematical description of the flotation process. The flotation process depends on many variable factors. These are mainly occurrences like collision of single particle with gas bubble, adhesion of particle to the surface of bubble and detachment process. These factors are characterized by randomness. Because of that it is only possible to talk about the probability of occurence of one of these events which directly affects the speed of the process, thus a constant speed of flotation process. Probability of the bubble-particle collision in the flotation chamber with mechanical pulp agitation depends on the surface tension of the solution, air consumption, degree of pul aeration, energy dissipation and average feed particle size. Appropriate identification and description of the parameters of the dispersion of gas bubbles helps to complete the analysis of the flotation process in a specific physicochemical conditions and hydrodynamic for any raw material. The article presents the results of measurements and analysis of the gas phase dispersion by the size distribution of air bubbles in a flotation chamber under fixed hydrodynamic conditions. The tests were carried out in the Laboratory of Instrumental Methods in Department of Environmental Engineering and Mineral Processing, Faculty of Mining and Geoengineerin, AGH Univeristy of Science and Technology in Krakow.

Characteristics of hardron-nucleus interactions at 100 GeV/c

NASA Astrophysics Data System (ADS)

Toothacker, W. S.; Whitmore, J.; Elcombe, P. A.; Hill, J. C.; Neale, W. W.; Kowald, W.; Walker, W. D.; Lucas, P.; Voyvodic, L.; Ammar, R.; Coppage, D.; Davis, R.; Gress, J.; Kanekal, S.; Kwak, N.; Bishop, J. M.; Biswas, N. N.; Cason, N. M.; Kenney, V. P.; Mattingly, M. C. K.; Ruchti, R. C.; Shepard, W. D.; Ting, S. J. Y.

1988-11-01

We report on 100 GeV/c interactions of p and p¯ with Ag and Au targets. This is a subset of the data from Fermilab experiment E597 and was performed with the 30-inch bubble chamber and Downstream Particle Identifier. Final state protons with laboratory momentum less than 1.4 GeV/c have been identified by their ionization in the bubble chamber. Final state protons/antiprotons with laboratory momentum greater than 10 GeV/c have been identified using CRISIS, an ionization sampling drift chamber. The cross section and mean transverse momentum squared of the leading baryon from the reactions p+(Ag,Au)→p+X and p¯+(Ag,Au)→p¯+X are presented as a function of the rapidity loss of the leading baryon. The laboratory rapidity and transverse momentum squared of the associated pions are also presented.

Development of the AFRL Aircrew Perfomance and Protection Data Bank

DTIC Science & Technology

2007-12-01

Growth model and statistical model of hypobaric chamber simulations. It offers a quick and readily accessible online DCS risk assessment tool for...are used for the DCS prediction instead of the original model. ADRAC is based on more than 20 years of hypobaric chamber studies using human...prediction based on the combined Bubble Growth model and statistical model of hypobaric chamber simulations was integrated into the Data Bank. It

Residual corneal stroma in big-bubble deep anterior lamellar keratoplasty: a histological study in eye-bank corneas.

PubMed

McKee, Hamish D; Irion, Luciane C D; Carley, Fiona M; Jhanji, Vishal; Brahma, Arun K

2011-10-01

To determine if residual corneal stroma remains on the recipient posterior lamella in big-bubble deep anterior lamellar keratoplasty (DALK). Pneumodissection using the big-bubble technique was carried out on eye-bank corneas mounted on an artificial anterior chamber. Samples that had a successful big-bubble formation were sent for histological evaluation to determine if any residual stroma remained on the Descemet membrane (DM). Big-bubble formation was achieved in 32 donor corneas. Two distinct types of big-bubble were seen: the bubble had either a white margin (30 corneas) or a clear margin (two corneas). The posterior lamellae of all the white margin corneas showed residual stroma on DM with a mean central thickness of 7.0 μm (range 2.6-17.4 μm). The clear margin corneas showed no residual stroma on DM. It should no longer be assumed that big-bubble DALK, where the bubble has a white margin, routinely bares DM. True baring of DM may only occur with the less commonly seen clear margin bubble.

A targeted ferritin-microplasmin based thrombolytic nanocage selectively dissolves blood clots.

PubMed

Seo, Junyoung; Al-Hilal, Taslim A; Jee, Jun-Goo; Kim, Yong-Lim; Kim, Ha-Jeong; Lee, Byung-Heon; Kim, Soyoun; Kim, In-San

2018-04-01

The use of thrombolytic therapies is limited by an increased risk of systemic hemorrhage due to lysis of hemostatic clots. We sought to develop a plasmin-based thrombolytic nanocage that efficiently dissolves the clot without causing systemic fibrinolysis or disrupting hemostatic clots. Here, we generated a double chambered short-length ferritin (sFt) construct that has an N-terminal region fused to multivalent clot targeting peptides (CLT: CNAGESSKNC) and a C-terminal end fused to a microplasmin (μPn); CLT recognizes fibrin-fibronectin complexes in clots, μPn efficiently dissolves clots, and the assembly of double chambered sFt (CLT-sFt-μPn) into nanocage structure protects the activated-μPn from its circulating inhibitors. Importantly, activated CLT-sFt-μPn thrombolytic nanocage showed a prolonged circulatory life over activated-μPn and efficiently lysed the preexisting clots in both arterial and venous thromboses models. Thus, CLT-sFt-μPn thrombolytic nanocage platform represents the prototype of a targeted clot-busting agent with high efficacy and safety over existing thrombolytic therapies. Copyright © 2018 Elsevier Inc. All rights reserved.

Increase in Blood-Brain Barrier Perrmeability, Oxidative Stress, and Activated Microglia in a Rat Model of Blast-Induced Traumatic Brain Injury

DTIC Science & Technology

2010-01-01

a critical role in the secondary it~ury process following TBI. In recent work, our coiJeagues demonstrated that, in both controlled cortical...Animals were then placed inco the end of the expansion chamber of an air-driven shock tube (2.5 ft com- pression chamber conn!:cted to a 15 ft expansion...Significance with A NOVA fo llowed by post hoc analysis (SNK) as follows: * P < 0.05. progression of neuropatho logical processes tha t could be relevant to

A large high vacuum, high pumping speed space simulation chamber for electric propulsion

NASA Technical Reports Server (NTRS)

Grisnik, Stanley P.; Parkes, James E.

1994-01-01

Testing high power electric propulsion devices poses unique requirements on space simulation facilities. Very high pumping speeds are required to maintain high vacuum levels while handling large volumes of exhaust products. These pumping speeds are significantly higher than those available in most existing vacuum facilities. There is also a requirement for relatively large vacuum chamber dimensions to minimize facility wall/thruster plume interactions and to accommodate far field plume diagnostic measurements. A 4.57 m (15 ft) diameter by 19.2 m (63 ft) long vacuum chamber at NASA Lewis Research Center is described. The chamber utilizes oil diffusion pumps in combination with cryopanels to achieve high vacuum pumping speeds at high vacuum levels. The facility is computer controlled for all phases of operation from start-up, through testing, to shutdown. The computer control system increases the utilization of the facility and reduces the manpower requirements needed for facility operations.

Methane emission by bubbling from Gatun Lake, Panama

NASA Technical Reports Server (NTRS)

Keller, Michael; Stallard, Robert F.

1994-01-01

We studied methane emission by bubbling from Gatun Lake, Panama, at water depths of less than 1 m to about 10 m. Gas bubbles were collected in floating traps deployed during 12- to 60-hour observation periods. Comparison of floating traps and floating chambers showed that about 98% of methane emission occurred by bubbling and only 2% occurred by diffusion. Average methane concentration of bubbles at our sites varied from 67% to 77%. Methane emission by bubbling occurred episodically, with greatest rates primarily between the hours of 0800 and 1400 LT. Events appear to be triggered by wind. The flux of methane associated with bubbling was strongly anticorrelated with water depth. Seasonal changes in water depth caused seasonal variation of methane emission. Bubble methane fluxes through the lake surface into the atmosphere measured during 24-hour intervals were least (10-200 mg/m2/d) at deeper sites (greater than 7 m) and greatest (300-2000 mg/m2/d) at shallow sites (less than 2 m).

Transient Flow Dynamics in Optical Micro Well Involving Gas Bubbles

NASA Technical Reports Server (NTRS)

Johnson, B.; Chen, C. P.; Jenkins, A.; Spearing, S.; Monaco, L. A.; Steele, A.; Flores, G.

2006-01-01

The Lab-On-a-Chip Application Development (LOCAD) team at NASA s Marshall Space Flight Center is utilizing Lab-On-a-Chip to support technology development specifically for Space Exploration. In this paper, we investigate the transient two-phase flow patterns in an optic well configuration with an entrapped bubble through numerical simulation. Specifically, the filling processes of a liquid inside an expanded chamber that has bubbles entrapped. Due to the back flow created by channel expansion, the entrapped bubbles tend to stay stationary at the immediate downstream of the expansion. Due to the huge difference between the gas and liquid densities, mass conservation issues associated with numerical diffusion need to be specially addressed. The results are presented in terms of the movement of the bubble through the optic well. Bubble removal strategies are developed that involve only pressure gradients across the optic well. Results show that for the bubble to be moved through the well, pressure pulsations must be utilized in order to create pressure gradients across the bubble itself.

Phase change liquid purifier and pump

DOEpatents

Steinhour, Leif Alexi

2017-05-23

Systems, methods, and apparatus are provided for purifying and pumping liquids, and more particularly, for purifying and pumping water. The apparatus includes a chamber including a top portion and a bottom portion. A surface configured to be heated is proximate the bottom portion of the chamber. A baffle is disposed within the chamber and above the surface. The baffle is disposed at an angle relative to a vertical direction. The chamber further includes an inlet and a first outlet. The surface heats a liquid in the chamber, causing the liquid to boil. In operation, bubbles rise from the surface and are forced in a horizontal direction by the baffle disposed in the chamber.

Trypan blue staining of the anterior capsule under an air bubble with a modified cannula.

PubMed

Toprak, Ahmet Baris; Erkin, Esin Fatma; Guler, Cenap

2003-01-01

To attain good visibility of the anterior capsule in the advanced or white cataract, trypan blue 0.1% is used to stain the anterior capsule. The dye is usually injected under an air bubble. However, it is difficult to inject the dye properly due to capillary forces. An ordinary anterior chamber cannula was modified and its coverage area increased to facilitate the staining of the anterior capsule under an air bubble. The anterior capsule was stained properly by using the modified cannula in all of the cases.

Dynamics of degassing at Kilauea Volcano, Hawaii

NASA Astrophysics Data System (ADS)

Vergniolle, Sylvie; Jaupart, Claude

1990-03-01

At Kilauea volcano, Hawaii, the recent long-lived eruptions of Mauna Ulu and Pu'u O'o have occurred in two major stages, defining a characteristic eruptive pattern. The first stage consists of cyclic changes of activity between episodes of "fire fountaining" and periods of quiescence or effusion of vesicular lava. The second stage consists only of continuous effusion of lava. We suggest that these features reflect the dynamics of magma degassing in a chamber which empties into a narrow conduit. In the volcano chamber, gas bubbles rise through magma and accumulate at the roof in a foam layer. The foam flows toward the conduit, and its shape is determined by a dynamic balance between the input of bubbles from below and the output into the conduit. The foam thickness is proportional to (μlQ/ɛ2 ρl g)1/4, where μ l and ρl are the viscosity and density of magma, ɛ is the gas volume fraction in the foam, g is the acceleration of gravity, and Q is the gas flux. The bubbles in the foam deform under the action of buoyancy, and the maximum permissible foam thickness is hc = 2σ/ɛρlgR, where σ is the coefficient of surface tension and R is the original bubble radius. If this critical thickness is reached, the foam collapses into a large gas pocket which erupts into the conduit. Foam accumulation then resumes, and a new cycle begins. The attainment of the foam collapse threshold requires a gas flux in excess of a critical value which depends on viscosity, surface tension, and bubble size. Hence two different eruption regimes are predicted: (1) alternating regimes of foam buildup and collapse leading to the periodic eruption of large gas volumes and (2) steady foam flow at the roof leading to continuous bubbly flow in the conduit. The essential result is that the continuous process of degassing can lead to discontinuous eruptive behavior. Data on eruption rates and repose times between fountaining phases from the 1969 Mauna UIu and the 1983-1986 Pu'u O'o eruptions yield constraints on three key variables. The area of the chamber roof must be a few tens of square kilometers, with a minimum value of about 8 km2. Magma reservoirs of similar dimensions are imaged by seismic attenuation tomography below the east rift zone. Close to the roof, the gas volume fraction is a few percent, and the gas bubbles have diameters lying between 0.1 and 0.6 mm. These estimates are close to the predictions of models for bubble nucleation and growth in basaltic melts, as well as to the observations on deep submarine basalts. The transition between cyclic and continuous activity occurs when the mass flux of gas becomes lower than a critical value of the order of 103 kg/s. In this model, changes of eruptive regime reflect changes in the amount and size of bubbles which reach the chamber roof.

A new thermal vacuum facility at the Martin Marietta Waterton plant

NASA Technical Reports Server (NTRS)

Watson, Robert N.; Bonn, John W.

1992-01-01

A new thermal-vacuum facility has been recently completed at the Martin Marietta Waterton plant near Denver, Colorado. The facility was designed, fabricated, installed, and tested as a turn-key project by Pitt-Des Moines Inc. and CVI Inc. The chamber has a 5.49 M by 6.10 M (18 ft by 20 ft) flat floor and a half-cylindrical roof with a diameter of 5.49 M (18 ft). Both ends of the chamber have full cross section doors, with one equipped with translating motors for horizontal motion. The chamber is provided with four 0.91 M (36 inches) cryopumps to obtain an ultimate pressure of 9 x 10(exp -8) Torr (Clean-Dry-Empty). The thermal shroud is designed to operate at a maximum of -179 C (-290 F) with an internal heat input of 316 MJ/Hr (300,000 BTU/Hr) using liquid nitrogen. The shroud is also designed to operate at any temperature between -156 C (-250 F) and 121 C (+250 F) using gaseous nitrogen, and heat or cool at a rate of 1.1 C (2 F) per minute.

Using a Novel Optical Sensor to Characterize Methane Ebullition Processes

NASA Astrophysics Data System (ADS)

Delwiche, K.; Hemond, H.; Senft-Grupp, S.

2015-12-01

We have built a novel bubble size sensor that is rugged, economical to build, and capable of accurately measuring methane bubble sizes in aquatic environments over long deployment periods. Accurate knowledge of methane bubble size is important to calculating atmospheric methane emissions from in-land waters. By routing bubbles past pairs of optical detectors, the sensor accurately measures bubbles sizes for bubbles between 0.01 mL and 1 mL, with slightly reduced accuracy for bubbles from 1 mL to 1.5 mL. The sensor can handle flow rates up to approximately 3 bubbles per second. Optional sensor attachments include a gas collection chamber for methane sampling and volume verification, and a detachable extension funnel to customize the quantity of intercepted bubbles. Additional features include a data-cable running from the deployed sensor to a custom surface buoy, allowing us to download data without disturbing on-going bubble measurements. We have successfully deployed numerous sensors in Upper Mystic Lake at depths down to 18 m, 1 m above the sediment. The resulting data gives us bubble size distributions and the precise timing of bubbling events over a period of several months. In addition to allowing us to characterize typical bubble size distributions, this data allows us to draw important conclusions about temporal variations in bubble sizes, as well as bubble dissolution rates within the water column.

Technology development for cobalt F-T catalysts. Quarterly technical progress report number 10, January 1--March 31, 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singleton, A.H.

1995-06-28

The goal of this project is the development of a commercially-viable, cobalt-based Fischer-Tropsch (F-T) catalyst for use in a slurry bubble column reactor. The major objectives of this work are (1) to develop a cobalt-based F-T catalyst with low (< 5%) methane selectivity, (2) to develop a cobalt-based F-T catalyst with water-gas shift activity, and (3) to combine both these improvements into one catalyst. The project consists of five major tasks: catalyst development; catalyst testing; catalyst reproducibility tests; catalyst aging tests; and preliminary design and cost estimate for a demonstrate scale catalyst production facility. Technical accomplishments during this reporting periodmore » include the following. It appears that the higher activity obtained for the catalysts prepared using an organic solution and reduced directly without prior calcination was the result of higher dispersions obtained under such pretreatment. A Ru-promoted Co catalyst on alumina with 30% Co loading exhibited a 4-fold increase in dispersion and a 2-fold increase in activity in the fixed-bed reactor from that obtained with the non-promoted catalyst. Several reactor runs have again focused on pushing conversion to higher levels. The maximum conversion obtained has been 49.7% with 26g catalyst. Further investigations of the effect of reaction temperature on the performance of Co catalysts during F-T synthesis were started using a low activity catalyst and one of the most active catalysts. The three 1 kg catalyst batches prepared by Calsicat for the reproducibility and aging studies were tested in both the fixed-bed and slurry bubble column reactors under the standard reaction conditions. The effects of adding various promoters to some cobalt catalysts have also been addressed. Results are presented and discussed.« less

The effect of surface wettability on the performance of a piezoelectric membrane pump

NASA Astrophysics Data System (ADS)

Wang, Jiantao; Yang, Zhigang; Liu, Yong; Shen, Yanhu; Chen, Song; Yu, Jianqun

2018-04-01

In this paper, we studied the effect of surface wettability on the bubble tolerance of a piezoelectric membrane pump, by applying the super-hydrophilic or super-hydrophobic surface to the key elements on the pump. Wettability for the flow passage surface has a direct influence on the air bubbles flowing in the fluid. Based on the existing research results, we first analyzed the relationship between the flow passage surface of the piezoelectric pump and the bubbles in the fluid. Then we made three prototypes where pump chamber walls and valve plate surfaces were given different wettability treatments. After the output performance test, results demonstrate that giving super-hydrophilic treatment on the surface of key elements can improve the bubble tolerance of piezoelectric pump; in contrast, giving super-hydrophobic treatment will reduce the bubble tolerance.

Exploding microbubbles driving a simple electrochemical micropump

NASA Astrophysics Data System (ADS)

Uvarov, Ilia V.; Lemekhov, Sergey S.; Melenev, Artem E.; Svetovoy, Vitaly B.

2017-10-01

Electrochemical microactuators and micropumps are too slow for many applications. The use of the alternating polarity electrolysis can strongly reduce the response time of such devices. We investigate a powerful pumping regime of a simple valveless micropump made from polydimethylsiloxane on a glass substrate. Microsecond dynamics of the gas bubbles in the chamber is monitored with fast cameras. After an incubation period of 10-100 ms a microbubble filling the entire chamber pops up in less than 100~μ s and disappears in 10 ms. This bubble pushes liquid out and drives the pump. The phenomenon is interpreted as an explosion of the microbubble containing a mixture of H2 and O2 gases. For higher amplitude of the driving pulses the incubation time can be as short as 1-2 ms but many uncorrelated microbubbles are formed in the chamber, and disappear in 1 ms. As the result a less powerful but faster pumping is possible. A few principles allowing further improve the micropump characteristics are formulated.

The mechanisms of fine particle generation and electrification during Mount St. Helens volcanic eruption

NASA Technical Reports Server (NTRS)

Cheng, R. J.

1982-01-01

Microscopical investigation of volcanic ash collected from ground stations during Mount St. Helens eruptions reveal a distinctive bimodel size distribution with high concentrations of particle ranges at (1) 200-100 microns and (2) 20-0.1 microns. Close examination of individual particles shows that most larger ones are solidified magma particles of porous pumice with numerous gas bubbles in the interior and the smaller ones are all glassy fragments without any detectable gas bubbles. Elemental analysis demonstrates that the fine fragments all have a composition similar to that of the larger pumice particles. Laboratory experiments suggest that the formation of the fine fragments is by bursting of glassy bubbles from a partially solidified surface of a crystallizing molten magma particle. The production of gas bubbles is due to the release of absorbed gases in molten magma particles when solubility decreases during phase transition. Diffusion cloud chamber experiments strongly indicate that sub-micron volcanic fragments are highly hygroscopic and extremely active as cloud condensation nuclei. Ice crystals also are evidently formed on those fragments in a supercooled (-20 C) cloud chamber. It has been reported that charge generation from ocean volcanic eruptions is due to contact of molten lava with sea water. This seems to be insufficient to explain the observed rapid and intense lightning activities over Mount St. Helens eruptions. Therefore, a hypothesis is presented here that highly electrically charged fine solid fragments are ejected by bursting of gas bubbles from the surface of a crystallizing molten magma particles.

The effect of vitrectomy with silicone oil tamponade on intraocular pressure and anterior chamber morphology.

PubMed

Suic, S P; Sikić, J

2001-01-01

We measured the tamponading effect of silicone oil, saline and air after vitrectomy, on intraocular pressure and aqueous humor outflow in 85 patients with highly proliferative retina and vitreous changes. Silicone oil as retinal tamponading agent after vitrectomy was used in 45 patients, and saline or air in 39 patients. The mean intraocular pressure measured at one month after treatment was greatly elevated in patients with silicone oil tamponade as compared to those with saline or air tamponade. At 6 and 12 months examinations, mean intraocular pressures were compared in these two groups of patients. Gonioscopy revealed silicone oil emulsification and presence of emulsified bubbles in the anterior chamber in 22.22% of patients, and narrowing of the chamber angle in several patients with silicone oil tamponade. Intraocular pressure elevation following vitrectomy with silicone oil tamponade was found to be of transient rather than permanent nature, since it regressed after silicone oil removal. This transient elevation was due to silicone oil tendency to emulsify. Silicone oil bubbles changed the morphology of the anterior chamber angle and fine trabecular structures by creating a barrier to aqueous humor outflow.

Advanced Expander Test Bed Program

DTIC Science & Technology

1991-04-01

CHAMBER COOLANT DP 503. CHAMBER COOLANT DT 896. ETA C* 0.993 CHAMBER Q 12371. ENGINE STATION CONDITIONS FUEL SYSTEM CONDITIONS STATION PRESS TEMP FLOW...1597.3 452.5 7.44 1507.1 0.62 CHAMBER 1500.0 * OXYGEN SYSTEM CONDITIONS STATION PRESS TEMP FLOW ENTHALPY DENSITY ENGINE INLET 70.0 163.0- 44.64 61.2...FUEL SYSTEM CONOITIONS PRESS TEMP FLOM ENTHALPY OENSITY STATION (PSIA) (DEG R) (LB/SEC) [(BTU/LB) (LB/FT31 ENGINE INLET 73.0 38.0 7.440 -104.8 4.389

The use of FT-IR reflection-absorbance spectroscopy to study photochemical degradation of polymeric coatings on mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Webb, J.D.; Chughtai, A.R.; Czanderna, A.W.

1981-10-01

A technique is presented for in situ study of degradative changes in polymeric coatings on metallic substrates. The technique uses a controlled environment chamber in conjunction with a Fourier-transform infrared (FT-IR) spectrophotometer. The chamber design permits collection of IR reflection-absorbance spectra from a sample undergoing exposure to controlled ultraviolet (UV) radiation, gas mixtures, and temperatures. Initial data presented confirm the ability of the technique to provide information regarding the bulk photochemistry of bisphenol-A polycarbonate coatings on gold and aluminum substrates. Refinements of this technique should allow a detailed kinetic study of degradative reactions at the polymer/metal interface.

Use of FT-IR reflection-absorbance spectroscopy to study photochemical degradation of polymeric coatings on mirrors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Webb, J D; Schissel, P; Czanderna, A W

1981-01-01

A technique is presented for in situ study of degradative changes in polymeric coatings on metallic substrates. The technique uses a controlled environment chamber in conjunction with a Fourier-transform infrared (FT-IR) spectrophotometer. The chamber design permits collection of IR reflection-absorbance spectra from a sample undergoing exposure to controlled ultraviolet (uv) radiation, gas mixtures, and temperatures. Initial data presented confirm the ability of the technique to provide information regarding the bulk photochemistry of bisphenol-A polycarbonate coatings on gold and aluminum substrates. Refinements of this technique should allow a detailed kinetic study of degradative reactions at the polymer/metal interface.

A Controlled-Environment Chamber for Atmospheric Chemistry Studies Using FT-IR Spectroscopy

DTIC Science & Technology

1990-06-01

necessary and identify by block number) FELD GROUP SUB-GROUP i >Chamber, controlled environment; long-path cell ; 07 04 FT-IR; Hydrazine decay...modification doubles the useable path length of the original multipass cell described by White (Reference 8). The pattern of images formed on the nesting...system is shown in Figure 13. 24 z C C02, Ibm, El4 944 C3 ta) caC E-4- 252 14 $4 41) 41) 0. 0 04 04 4 41) ~0 to 0.0 V-4 (A q14 0~ 1% 4-r4 $4 0 u P416 4 4

[Theoretical analysis of recompression-based therapies of decompression illness].

PubMed

Nikolaev, V P; Sokolov, G M; Komarevtsev, V N

2011-01-01

Theoretical analysis is concerned with the benefits of oxygen, air and nitrogen-helium-oxygen recompression schedules used to treat decompression illness in divers. Mathematical modeling of tissue bubbles dynamics during diving shows that one-hour oxygen recompression to 200 kPa does not diminish essentially the size of bubble enclosed in a layer that reduces tenfold the intensity of gas diffusion from bubbles. However, these bubbles dissolve fully in all the body tissues equally after 2-hr. air compression to 800 kPa and ensuing 2-d decompression by the Russian navy tables, and 1.5-hr. N-He-O2 compression to this pressure followed by 5-day decompression. The overriding advantage of the gas mixture recompression is that it obviates the narcotic action of nitrogen at the peak of chamber pressure and does not create dangerous tissue supersaturation and conditions for emergence of large bubbles at the end of decompression.

Characteristics of carbon nanotubes based micro-bubble generator for thermal jet printing.

PubMed

Zhou, Wenli; Li, Yupeng; Sun, Weijun; Wang, Yunbo; Zhu, Chao

2011-12-01

We propose a conceptional thermal printhead with dual microbubble generators mounted parallel in each nozzle chamber, where multiwalled carbon nanotubes are adopted as heating elements with much higher energy efficiency than traditional approaches using noble metals or polysilicon. Tailing effect of droplet can be excluded by appropriate control of grouped bubble generations. Characteristics of the corresponding micro-fabricated microbubble generators were comprehensively studied before the formation of printhead. Electrical properties of the microheaters on glass substrate in air and performance of bubble generation underwater focusing on the relationships between input power, device resistance and bubble behavior were probed. Proof-of-concept bubble generations grouped to eliminate the tailing effect of droplet were performed indicating precise pattern with high resolution could be realized by this kind of printhead. Experimental results revealed guidance to the geometric design of the printhead as well as its fabrication margin and the electrical control of the microbubble generators.

Calibration and Use of B Dot Probes for Electromagnetic Measuring

DTIC Science & Technology

1977-08-09

response. E. Time Domain Reflectometry Measurements Pulse impedance measurements for the 1.75-in. diameter double-gap probe design were first performed...Far Field (Radiation) Patterns of a B Dot Probe 1. Anechoic Chamber The facility utilized for the probe patterns was the NASA 120-ft chamber at

Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial.

PubMed

Souday, Vincent; Koning, Nick J; Perez, Bruno; Grelon, Fabien; Mercat, Alain; Boer, Christa; Seegers, Valérie; Radermacher, Peter; Asfar, Pierre

2016-01-01

To test the hypothesis whether enriched air nitrox (EAN) breathing during simulated diving reduces decompression stress when compared to compressed air breathing as assessed by intravascular bubble formation after decompression. Human volunteers underwent a first simulated dive breathing compressed air to include subjects prone to post-decompression venous gas bubbling. Twelve subjects prone to bubbling underwent a double-blind, randomized, cross-over trial including one simulated dive breathing compressed air, and one dive breathing EAN (36% O2) in a hyperbaric chamber, with identical diving profiles (28 msw for 55 minutes). Intravascular bubble formation was assessed after decompression using pulmonary artery pulsed Doppler. Twelve subjects showing high bubble production were included for the cross-over trial, and all completed the experimental protocol. In the randomized protocol, EAN significantly reduced the bubble score at all time points (cumulative bubble scores: 1 [0-3.5] vs. 8 [4.5-10]; P < 0.001). Three decompression incidents, all presenting as cutaneous itching, occurred in the air versus zero in the EAN group (P = 0.217). Weak correlations were observed between bubble scores and age or body mass index, respectively. EAN breathing markedly reduces venous gas bubble emboli after decompression in volunteers selected for susceptibility for intravascular bubble formation. When using similar diving profiles and avoiding oxygen toxicity limits, EAN increases safety of diving as compared to compressed air breathing. ISRCTN 31681480.

Pressure increases, the for­mation of chromite seams, and the development of the ultramafic series in the Stillwater Complex, Montana

USGS Publications Warehouse

Lipin, Bruce R.

1993-01-01

This paper explores the hypothesis that chromite seams in the Stillwater Complex formed in response to periodic increases in total pressure in the chamber. Total pressure increased because of the positive δV of nucleation of CO2 bubbles in the melt and their subsequent rise through the magma chamber, during which the bubbles increased in volume by a factor of 4–6. By analogy with the pressure changes in the summit chambers of Kilauea and Krafla volcanoes, the maximum variation was 0⋅2–0⋅25 kbar, or 5–10% of the total pressure in the Stillwater chamber. An evaluation of the likelihood of fountaining and mixing of a new, primitive liquid that entered the chamber with the somewhat more evolved liquid already in the chamber is based upon calculations using observed and inferred velocities and flow rates of basaltic magmas moving through volcanic fissures. The calculations indicate that hot, dense magma would have oozed, rather than fountained into the chamber, and early mixing of the new and residual magmas that could have resulted in chromite crystallizing alone did not take place.Mixing was an important process in the Stillwater magma chamber, however. After the new magma in the chamber underwent ˜5% fractional crystallization, its composition, temperature, and density approached those of the overlying liquid in the chamber and the liquids then mixed. If this process occurred many times over the course of the development of the Ultramafic series, a thick column of magma with orthopyroxene on its liquidus would have been the result. Thus, the sequence of multiple injections, fractionation, and mixing with previously fractionated magma could have been the mechanism that produced the thick bronzite cumulate layer (the Bronzitite zone) above the cyclic units.

Air Bubble-Induced High Intraocular Pressure After Descemet Membrane Endothelial Keratoplasty.

PubMed

Röck, Daniel; Bartz-Schmidt, Karl Ulrich; Röck, Tobias; Yoeruek, Efdal

2016-08-01

To investigate the incidence and risk factors of pupillary block caused by an air bubble in the anterior chamber in the early postoperative period after Descemet membrane endothelial keratoplasty (DMEK). A retrospective review was conducted in 306 eyes that underwent DMEK from September 2009 through October 2014 at the Tübingen Eye Hospital. Intraocular pressure (IOP) elevation was defined as a spike above 30 mm Hg. In the first 190 eyes, an intraoperative peripheral iridectomy was performed at the 12-o'clock position and in the other 116 eyes at the 6-o'clock position. If possible, reasons for IOP elevation were identified. For all eyes, preoperative and postoperative slit-lamp examinations and IOP measurements were performed. Overall, 30 eyes (9.8%) showed a postoperative IOP elevation within the first postoperative day. The incidence of IOP elevation was 13.9% (5/36) in the triple DMEK group, and 2 of 5 phakic eyes (40%) developed an air bubble-induced IOP elevation. All eyes presented with a de novo IOP elevation, associated in 25 patients with pupillary block from air anterior to iris and in 5 patients with angle closure from air migration posterior to the iris. All of them had an iridectomy at the 12-o'clock position. A postoperative pupillary block with IOP elevation caused by the residual intraoperative air bubble may be an important complication that could be avoided by close and frequent observations, especially in the first postoperative hours and by an inferior peripheral iridectomy and an air bubble with a volume of ≤80% of the anterior chamber.

Dark matter search results from the PICO-2L C$$_3$$F$$_8$$ bubble chamber

DOE PAGES

Amole, C.

2015-06-11

New data are reported from the operation of a 2 liter C 3F 8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C 3F 8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of < 3.5 × 10 –10 and an alpha rejection factor of > 98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed duringmore » the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. Lastly, these data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.« less

Air-Operated Sump Pump

NASA Technical Reports Server (NTRS)

Nolt, Gary D.

1988-01-01

Pump removes liquid seepage from small, restricted area and against large pressure head. Developed for moving small amounts of water and oil from sump pit 85 ft (25.91 m) deep. Fits in space only 6 1/2 in. (16.5 cm) in diameter and 18 in. (45.7 cm) long. In discharge part of pumping cycle, air forces liquid out of pump chamber through pipe. During filling part of pumping cycle, water enters pump chamber from sump pit. Float in chamber next to pump chamber controls pressurization through timer and solenoid valve.

Influence of liquid medium on the activity of a low-alpha Fischer-Tropsch catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gormley, R.J.; Zarochak, M.F.; Deffenbaugh, P.W.

1995-12-31

The purpose of this research was to measure activity, selectivity, and the maintenance of these properties in slurry autoclave experiments with a Fischer-Tropsch (FT) catalyst that was used in the {open_quotes}FT II{close_quotes} bubble-column test, conducted at the Alternative Fuels Development Unit (AFDU) at LaPorte, Texas during May 1994. The catalyst contained iron, copper, and potassium and was formulated to produce mainly hydrocarbons in the gasoline range with lesser production of diesel-range products and wax. The probability of chain growth was thus deliberately kept low. Principal goals of the autoclave work have been to find the true activity of this catalystmore » in a stirred tank reactor, unhindered by heat or mass transfer effects, and to obtain a steady conversion and selectivity over the approximately 15 days of each test. Slurry autoclave testing of the catalyst in heavier waxes also allows insight into operation of larger slurry bubble column reactors. The stability of reactor operation in these experiments, particularly at loadings exceeding 20 weight %, suggests the likely stability of operations on a larger scale.« less

Acting Administrator Lightfoot Visits Ball Aerospace

NASA Image and Video Library

2017-04-06

Michael Dean, senior project engineer for the Joint Polar Satellite System (JPSS) program at Ball Aerospace, right, speaks with acting NASA Deputy Administrator Lesa Roe, second from left, and acting NASA Administrator Robert Lightfoot, center, about the 20ft. by 24 ft. vertical thermal vacuum chamber, Thursday, April 6, 2017 during a visit to Ball Aerospace in Boulder, Colo. Photo Credit: (NASA/Joel Kowsky)

Development and Evaluation of a Monte Carlo Code System for Analysis of Ionization Chamber Responses,

DTIC Science & Technology

1987-07-01

ft. ft 3 ORNL/TM- 10196 INTERNAL DISTRIBUTION 1. F. S. Alsmiller 32. R. T. Santoro 2. R. G. Alsmiller, Jr. 33. M. S. Smith 3. D. E. Bartine 34. J. S...W. Armstrong, Science Applications, Inc., P.O. Box 2807, La Jolla, CA 92038. 57. Miguel Awschalom, National Accelerator Laboratory, P. 0. Box 500

77 FR 35662 - Intent To Prepare a Draft Supplemental Environmental Impact Statement for the Greenup Locks and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-14

... project in April 2000. This study recommended a 600- foot (ft) extension of the existing auxiliary lock chamber to a length of 1200 ft. The project was authorized by Congress in 2000; however, no funds have been appropriated for project construction. Due to the amount of time that has elapsed since completion...

Devillier field, Chambers County, Texas: effects of growth faults and deltaic sedimentation on hydrocarbon accumulation in a stratigraphic trap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gordon, P.T.

Devillier field is an overpressured gas reservoir producing from upper Vicksburg (lower Oligocene) Loxostoma B Delicata-age sands which pinch-out near the crest of an anticline located on the downthrown side of the Vicksburg flexure. The field is located 50 miles (80 km) east of Houston in NE Chambers County, Texas. The first year's production per well has averaged 1.0 billion cu ft of gas and 13,000 bbl condensate, for the 7 wells completed since the field discovery in 1975. Calculated open flows have ranged as high as 600,000 MCFD of gas from an average net-sand interval of 25 ft (7.6more » m) at depths between 10,550 and 10,750 ft (3216 and 3277 m). The upper Vicksburg sediments are considered to have been deposited in a shallow-marine environment. The field pay, the Loxostoma sand, is interpreted to have been deposited in a delta distributary mouth bar.« less

Bubble Chamber : A novel technique for measuring thermonuclear rates at low energies

NASA Astrophysics Data System (ADS)

Talwar, R.; Benesh, J.; Digiovine, B.; Grames, J.; Holt, R. J.; Kharashvili, G.; Meekins, D.; Moser, D.; Poelkar, M.; Rehm, K. E.; Robinson, A.; Sonnenschein, A.; Stutzman, M.; Suleiman, R.; Tennant, C.; Ugalde, C.

2016-03-01

Adopting ideas from dark matter search experiments, we have found that a superheated liquid in a bubble detector is sensitive to recoils produced by γ-ray beams impinging on the nuclei in the liquid. Such a target-detector system has a density factor of four orders of magnitude higher than conventional gas targets and is practically insensitive to the γ-ray beam itself. Also, since photodisintegration reactions have approximately two orders of magnitude higher cross-sections than direct particle capture reactions, such a technique can pave the way towards measuring these reactions within the stellar Gamow window. In an effort to study the 16O(γ , α)12C system using the bubble chamber technique, the first test of the superheated N2O liquid with a low-energy bremsstrahlung beam at JLab has been completed. This test has been performed to understand the background contributions from 17O and 18O nuclei in N2O. The experimental technique, results and future plans will be presented. This work has been supported by US DOE (DE-AC02-06CH11357) and Jefferson Science Associations, LLC (DE-AC05-06OR23177).

Real-cinematographic visualization of droplet ejection in thermal ink jets

NASA Astrophysics Data System (ADS)

Rembe, Christian; Patzer, Joachim; Hofer, Eberhard P.; Krehl, Peter

1996-03-01

Although thermal ink jet printers have gained a high market share there are still open questions left in the understanding of the processes in ink jet firing chambers. The experimental investigation of these processes is difficult due to the extremely short time durations of the different phenomena. For example, the bubble life time amounts to approximately 20 microsecond(s) . A new experimental set-up is presented to record phenomena of very short time duration like the bubble nucleation process and the beginning of droplet ejection. This set-up allows realcinematographic visualization with a local resolution of less than 1 micrometers and a time resolution of 10 ns. This also offers the possibility to investigate transient processes like the droplet ejection at high printing frequencies. The essential part of the set-up is a new high speed camera. With an exact evaluation of the digitized images the locus, velocity, and acceleration distributions of the phase interface from liquid to vapor/air can be measured. In addition the results of a numerical model with realistic geometry of the firing chamber and the nozzle have been compared with the experimental results to draw conclusions for pressure propagation in the vapor bubble.

Period adding cascades: experiment and modeling in air bubbling.

PubMed

Pereira, Felipe Augusto Cardoso; Colli, Eduardo; Sartorelli, José Carlos

2012-03-01

Period adding cascades have been observed experimentally/numerically in the dynamics of neurons and pancreatic cells, lasers, electric circuits, chemical reactions, oceanic internal waves, and also in air bubbling. We show that the period adding cascades appearing in bubbling from a nozzle submerged in a viscous liquid can be reproduced by a simple model, based on some hydrodynamical principles, dealing with the time evolution of two variables, bubble position and pressure of the air chamber, through a system of differential equations with a rule of detachment based on force balance. The model further reduces to an iterating one-dimensional map giving the pressures at the detachments, where time between bubbles come out as an observable of the dynamics. The model has not only good agreement with experimental data, but is also able to predict the influence of the main parameters involved, like the length of the hose connecting the air supplier with the needle, the needle radius and the needle length.

Use of a "small-bubble technique" to increase the success of Anwar's "big-bubble technique" for deep lamellar keratoplasty with complete baring of Descemet's membrane.

PubMed

Parthasarathy, Anand; Por, Yong Ming; Tan, Donald T H

2007-10-01

To describe a quick and simple "small-bubble" technique to immediately determine the success of attaining complete Descemet's membrane (DM) separation from corneal stroma through Anwar's "big-bubble" technique of deep anterior lamellar keratoplasty (DALK) for complete stromal removal. A partial trephination was followed by a lamellar dissection of the anterior stroma. Deep stromal air injection was then attempted to achieve the big bubble to help separate the stroma from the DM. To confirm that a big bubble had been achieved, a small air bubble was injected into the anterior chamber (AC) through a limbal paracentesis. If the small bubble is then seen at the corneal periphery, it confirms that the big-bubble separation of DM was successful because the convex nature of the bubble will cause it to protrude posteriorly, forcing the small AC bubble to the periphery. If the small AC bubble is not seen in the corneal periphery, this means that it is present in the centre, beneath the opaque corneal stroma, and therefore the big bubble has not been achieved. We used the small-bubble technique to confirm the presence of the big bubble in three (one keratoconus, one interstitial keratitis and one dense corneal scar) out of 41 patients who underwent DALK. The small-bubble technique confirmed that the big bubble was achieved in the eye of all three patients. Complete stromal removal with baring of the DM was achieved, and postoperatively all three eyes achieved best corrected vision of 6/6. The small-bubble technique can be a useful surgical tool for corneal surgeons attempting lamellar keratoplasty using the big-bubble technique. It helps in confirming the separation of DM from the deep stroma, which is important in achieving total stromal replacement. It will help to make the transition to lamellar keratoplasty smoother, enhance corneal graft success and improve visual outcomes in patients.

Geyser preplay and eruption in a laboratory model with a bubble trap

NASA Astrophysics Data System (ADS)

Adelstein, Esther; Tran, Aaron; Saez, Carolina Muñoz; Shteinberg, Alexander; Manga, Michael

2014-09-01

We present visual observations and temperature measurements from a laboratory model of a geyser. Our model incorporates a bubble trap, a zone in which vapor can accumulate in the geyser's subsurface plumbing, in a vertical conduit connected to a basal chamber. Analogous features have been identified at several natural geysers. We observe three types of eruptions: 1) rising bubbles eject a small volume of liquid in a weak spout (small eruption); 2) boiling occurs in the conduit above the bubble trap (medium eruption); and 3) boiling occurs in the conduit and chamber (large eruption). In the last two cases, boiling in the conduit causes a rapid hydrostatic pressure drop that allows for the rise and eruption of liquid water in a vigorous spout. Boiling initiates at depth rather than propagating downward from the surface. In a single eruption cycle, multiple small eruptions precede every medium and large eruption. At least one eruption cycle that culminates in a medium eruption (i.e., a quiescent period followed by a series of small eruptions leading up to a medium eruption) precedes every eruption cycle that culminates in a large eruption. We find that the transfer of fluid with high enthalpy to the upper conduit during small and medium eruptions is necessary to heat the upper conduit and prepare the system for the full boiling required for a large eruption. The placement of the bubble trap midway up the conduit allows for more efficient heating of the upper conduit. Our model provides insight into the influence of conduit geometry on eruption style and the importance of heat transfer by smaller events in preparing the geyser system for eruption.

Optimization of Biomass Gasification Process for F-T Bio-Diesel Synthesys

NASA Astrophysics Data System (ADS)

Song, Jae Hun; Sung, Yeon Kyung; Yu, Tae U.; Choi, Young Tae; Lee, Uen Do

The characteristics of biomass steam gasification were investigated to make an optimum syngas for Fischer Tropsch (F-T) synthesis of bio-diesel. Korean pine wood chip was used as a fuel and the experiment was conducted in a lab scale bubbling fluidized bed (0.1m LD. x 3.Omheight). Gas composition was evaluated by changing operating parameters such as gasifier temperature, and steam to fuel ratio. Major syngas was monitored by on-line gas analyzer (ND-IR spectroscopy) and gas chromatography (GC). As the temperature of gasifier increases hydrogen in the syngas increases while CO in the product gas decreases. The low concentration of sulfur compound and nitrogen in the product gas shows the potential advantages in the purification process of the syngas for F-T process. Optimum operating condition of the gasifier was found concerning the following gas cleaning and F-T process; H2-CO ratio and total gas yield increase while decreasing methane and CO2 concentrations in the syngas.

The use of decompression to simulate the effect of extravehicular activity on human lymphocyte transformation

NASA Technical Reports Server (NTRS)

Meehan, R. T.; Duncan, U.; Neale, L.; Waligora, J.; Taylor, G. R.

1986-01-01

Lymphocytes from 35 subjects participating in a chamber study simulating extravehicular activity (EVA) conditions were studied. No significant differences in H3 thymidine uptake between pre chamber and post chamber response to any mitogens autologous plasma, or among circulating mononuclear cells by flow cytometry are observed. The studies could not identify the subjects who developed venous bubbles. Data from eight subjects suggests that acute stress associated with participating in the study augments in vitro lymphocyte proliferation. Results indicate EVA exposure does not greatly influence space-flight induced alterations in immune effector cell function.

Femtosecond laser–assisted cataract surgery in vitrectomized eye with posterior chamber phakic intraocular lens

PubMed Central

Anisimova, Natalia; Malyugin, Boris; Arbisser, Lisa B.; Sobolev, Nikolay

2017-01-01

Summary We describe a case of femtosecond laser–assisted cataract surgery (FLACS) in an eye with multiple comorbidities, including retinal detachment surgery, high myopia, posterior chamber phakic intraocular lens (PC pIOL) and residual, emulsified, silicone oil located in the anterior chamber. FLACS was affected by the optical blockage, but the incomplete capsular tear was recoverable. The case suggests that silicone oil bubbles concentrated at the dome of the posterior corneal surface, along with the PC pIOL optic edges and scars after corneal astigmatic relaxing incisions can lead to incomplete anterior capsulotomy. PMID:28924422

New approach on volatile contents determination in silicate melt inclusions: A coupling X-ray microtomography and geochemical approach in Los Humeros caldera complex (Eastern Mexican Volcanic Belt)

NASA Astrophysics Data System (ADS)

Creon, L.; Levresse, G.; Carrasco Nuñez, G.

2016-12-01

Volatile contents and magma degassing behavior are known to affect the style, frequency, and intensity of near-surface magmatic processes. For this reason, much effort have been devoted to characterize the volatile evolution of shallow magmatic systems to better constrain volcanic history. Silicate melt inclusions (SMI) represent samples of melt that were isolated from the bulk magma at depth, thus preserving the PTX conditions of the pre-eruptive material. SMI are often affected by the formation of a bubble after trapping; this is a natural consequence of the PVTX properties of crystal-melt-volatile systems. Previous workers have recognized that bubble formation is an obstacle, which affects the interpretation of SMI trapping conditions based only on analysis of the glass phase. Indeed, they explained that bubbles can contain a significant percentage of the volatiles, particularly for those with low solubility in the melt (e.g. CO2). In this study, we propose to define the pre-eruptive PTX conditions of Los Humeros magma chamber using SMI from the various eruption events within 460 and 30 Ka. An innovative analytical coupling has been used in order to determine: (1) the volume of the SMI glass and bubble, using high resolution 3D X-ray microtomography; (2) the density and composition of the bubbles, using Raman spectroscopy; (3) the volatile element contents in glass, using NanoSIMS; and, (4) the major elements composition of the glass, using EPMA. The recalculated volatile concentrations of the total SMI (glass + bubble), illustrate clearly that the volatile content determinations using only the glass phase, underestimate drastically the total volatile content and therefore induce significant error on the determination of the pre-eruptive volcanic budget and on the constrain on the volcanic and thermal history. This study had moreover highlighted the complex evolution of Los Humeros composite magma chamber and, gave constrains for geothermal exploration purpose.

Density functional theory of gas-liquid phase separation in dilute binary mixtures

NASA Astrophysics Data System (ADS)

Okamoto, Ryuichi; Onuki, Akira

2016-06-01

We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas Δ {μ\\text{s}} (the Gibbs energy of transfer) is considerably larger than the thermal energy {{k}\\text{B}}T for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by {{k}\\text{B}}Tn2\\ell\\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right) , where n2\\ell is the solute density added in liquid. For \\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right)\\gg 1 , phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

CFD analysis of hydrodynamic studies of a bubbling fluidized bed

NASA Astrophysics Data System (ADS)

Rao, B. J. M.; Rao, K. V. N. S.; Ranga Janardhana, G.

2018-03-01

Fluidization velocity is one of the most important parameter to characterize the hydrodynamic studies of fluidized bed asit determines different flow regimes. Computational Fluid Dynamics simulations are carriedfor a cylindrical bubbling fluidized bed with a static bed height 1m with 0.150m diameter of gasification chamber. The parameter investigated is fluidization velocity in range of 0.05m/s to 0.7m/s. Sand with density 2600kg/m3 and with a constant particle diameter of sand 385μm is employed for all the simulations. Simulations are conducted using the commercial Computational Fluid Dynamics software, ANSYS-FLUENT.The bubbling flow regime is appeared above the air inlet velocity of 0.2m/s. Bubbling character is increased with increase in inlet air velocities indicated by asymmetrical fluctuations of volume fractions in radial directions at different bed heights

Sidewall crystallization and saturation front formation in silicic magma chambers

NASA Astrophysics Data System (ADS)

Lake, E. T.

2012-12-01

The cooling and crystallization style of silicic magma bodies in the upper crust falls on a continuum between whole-chamber processes of convection, crystal settling, and cumulate formation and interface driven processes of conduction and crystallization front migration. In the former case, volatile saturation occurs uniformly chamber wide, in the latter volatile saturation occurs along an inward propagating front. Ambient thermal gradient primarily controls the propagation rate; warm (> 30 °C / km) geothermal gradients promote 1000m+ thick crystal mush zones but slow crystallization front propagation. Cold geothermal gradients support the opposite. Magma chamber geometry plays a second order role in controlling propagation rates; bodies with high surface to magma ratio and large Earth's surface parallel faces exhibit more rapid propagation and smaller mush zones. Crystallization front propagation occurs at speeds of up to 6 cm/year (rhyolitic magma, thin sill geometry, 10 °C / km geotherm), far faster than diffusion of volatiles in magma and faster than bubbles can nucleate and ascend under certain conditions. Saturation front propagation is fixed by pressure and magma crystal content; above certain modest initial water contents (4.4 wt% in a dacite) mobile magma above 10 km depth always contains a saturation front. Saturation fronts propagate down from the magma chamber roof at lower water contents (3.3 wt% in a dacite at 5 km depth), creating an upper saturated interface for most common (4 - 6 wt%) magma water contents. This upper interface promotes the production of a fluid pocket underneath the apex of the magma chamber. Magma de-densification by bubble nucleation promotes convection and homogenization in dacitic systems. If the fluid pocket grew rapidly without draining, hydro-fracturing and eruption would result. The combination of fluid escape pathways and metal scavenging would generate economic vein or porphyry deposits.

Creating the Thermal Environment for Safely Testing the James Webb Space Telescope at the Johnson Space Center's Chamber A

NASA Technical Reports Server (NTRS)

Homan, Jonathan L.; Lauterbach, John; Garcia, Sam

2016-01-01

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. The chamber was originally built to support testing of the Apollo Service and Command Module for lunar missions, but underwent major modifications to be able to test the James Webb Space Telescope in a simulated deep space environment. To date seven tests have been performed in preparation of testing the flight optics for the James Webb Space Telescope (JWST). Each test has had a uniquie thermal profile and set of thermal requirements for cooling down and warming up, controlling contamination, and releasing condensed air. These range from temperatures from 335K to 15K, with tight uniformity and controllability for maintining thermal stability and pressure control. One unique requirement for two test was structurally proof loading hardware by creating thermal gradients at specific temperatures. This paper will discuss the thermal requirements and goals of the tests, the original requirements of the chamber thermal systems for planned operation, and how the new requirements were met by the team using the hardware, system flexiblilty, and engineering creativity. It will also discuss the mistakes and successes to meet the unique goals, especially when meeting the thermal proof load.

Analysis of dynamic characteristics of fluid force induced by labyrinth seal

NASA Technical Reports Server (NTRS)

Iwatsubo, T.; Kawai, R.; Kagawa, N.; Kakiuchi, T.; Takahara, K.

1984-01-01

Flow patterns of the labyrinth seal are experimentally investigated for making a mathematical model of labyrinth seal and to obtain the flow induced force of the seal. First, the flow patterns in the labyrinth chamber are studied on the circumferential flow using bubble and on the cross section of the seal chamber using aluminum powder as tracers. And next, the fluid force and its phase angle are obtained from the measured pressure distribution in the chamber and the fluid force coefficients are derived from the fluid force and the phase angle. Those are similar to the expression of oil film coefficients. As a result, it is found that the vortices exist in the labyrinth chambers and its center moves up and down periodically. The pressure drop is biggest in the first stage of chambers and next in the last stage of chambers.

Fuel composition and secondary organic aerosol formation: gas-turbine exhaust and alternative aviation fuels.

PubMed

Miracolo, Marissa A; Drozd, Greg T; Jathar, Shantanu H; Presto, Albert A; Lipsky, Eric M; Corporan, Edwin; Robinson, Allen L

2012-08-07

A series of smog chamber experiments were performed to investigate the effects of fuel composition on secondary particulate matter (PM) formation from dilute exhaust from a T63 gas-turbine engine. Tests were performed at idle and cruise loads with the engine fueled on conventional military jet fuel (JP-8), Fischer-Tropsch synthetic jet fuel (FT), and a 50/50 blend of the two fuels. Emissions were sampled into a portable smog chamber and exposed to sunlight or artificial UV light to initiate photo-oxidation. Similar to previous studies, neat FT fuel and a 50/50 FT/JP-8 blend reduced the primary particulate matter emissions compared to neat JP-8. After only one hour of photo-oxidation at typical atmospheric OH levels, the secondary PM production in dilute exhaust exceeded primary PM emissions, except when operating the engine at high load on FT fuel. Therefore, accounting for secondary PM production should be considered when assessing the contribution of gas-turbine engine emissions to ambient PM levels. FT fuel substantially reduced secondary PM formation in dilute exhaust compared to neat JP-8 at both idle and cruise loads. At idle load, the secondary PM formation was reduced by a factor of 20 with the use of neat FT fuel, and a factor of 2 with the use of the blend fuel. At cruise load, the use of FT fuel resulted in no measured formation of secondary PM. In every experiment, the secondary PM was dominated by organics with minor contributions from sulfate when the engine was operated on JP-8 fuel. At both loads, FT fuel produces less secondary organic aerosol than JP-8 because of differences in the composition of the fuels and the resultant emissions. This work indicates that fuel reformulation may be a viable strategy to reduce the contribution of emissions from combustion systems to secondary organic aerosol production and ultimately ambient PM levels.

THE ANGULAR DISTRIBUTION OF POSITRONS IN $pi$$sup +$-$mu$$sup +$-e$sup +$ DECAY IN PROPANE (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alikhanyan, A.I.; Kirillov-Ugryumov, V.G.; Kotenko, L.P.

1958-01-01

In consideration of the wide use of propane bubble cameras, investigations were made of the angular distribution of electrons from pi /sup +/ -- mu /sup +/--e/sup +/ decay in propane to determine the possibility of using propane in angular correlation measurements of processes simlar to mu --e decay. The scheme of the experiment made with a bubble chamber of (7.2 x 6.5 x 16)cm/ dmensions bombarded by a 175-Mev pi -meson beam from a phasotron is described. (R.V.J.)

Relating Venous Gas Emboli (VGE) Scores to Altitude Decompression Sickness (DCS) Symptoms

NASA Technical Reports Server (NTRS)

Pilmanis, A. A.; Kannan, N.; Krause, K. M.; Webb, J. T.

1999-01-01

Purpose. It is generally accepted that DCS symptoms are caused by gas bubbles in tissues. However, current technology of bubble detection only permits monitoring of circulating bubbles, primarily intracardiac. Since the majority of DCS symptoms appear to be caused by extravascular bubbles, it has been suggested that current bubble detection techniques target bubbles that are of importance in only a minority of DCS cases. The purpose of this study is to determine the relationships between measured VGE and DCS symptoms in human subjects exposed to altitude. Methods. The AFRL DCS Research Database contains records on 2044 subject-exposures to simulated altitudes in a hypobaric chamber. VGE monitoring was accomplished using Doppler/Echo Imaging techniques. The Spencer Scale was used to score the VGE. Reporting of DCS symptoms by the subject was the primary end-point of the exposures. Results: The Mantel- Haenzel test indicated a strong correlation between DCS and bubble grade (p-value =0.001). Conclusions. A positive correlation between increasing VGE scores and DCS symptoms, does not imply causatinn. If all non-zero VGE grades are considered, 45.9% of the cases had VGE, but no DCS symptoms. Conversely, almost 1 in 5 subject-exposures resulted in DCS with NO VGE detected. VGE scores are not . good predictors of altitude DCS symptoms and field use of bubble detection for DCS prevention is not supported by this study.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zissa, D.E.; Barnes, V.E.; Carmony, D.D.

The elastic and topological p-barp cross sections have been measured at 48.9 GeV/c in the Fermilab proportional-wire-chamber--30-in.-bubble-chamber hybrid spectrometer. The elastic cross section is 7.81 +- 0.24 mb and the slope of the elastic differential cross section at t=0 is 13.4 +- 0.8 GeV/sup -2/. Further, the moments of the inelastic topological-cross-section distribution are =5.69 +- 0.03, /D=2.10 +- 0.02, and f/sup c/c/sub 2/=1.67 +- 0.12.

Durability and Damage Tolerance of Bismaleimide Composites. Volume 1. Technical Report

DTIC Science & Technology

1988-06-01

Test Setup Figure 1-14, Failed Loaded Holo Static Spoifton 106 mru FaJIus Stma. FuMr Materal Spwima anT VPIU h Kok Fo Faflurep t PldN Stromsym EVIM hm...Environrnental Chamber tot ETW TesI $ 1 36 12.5 x lOft.Ibs x 7ft-lbsI- __ 8.5 14ft-bs Figure 146. Outer Mold Une Impact Locations and Eery -Levela 5.3.5

Gender Consideration in Experiment Design for Air Break in Prebreathe

NASA Technical Reports Server (NTRS)

Conkin, Johnny; Dervay, Joseph P.; Gernhardt, Michael L.

2007-01-01

If gender is a confounder of the decompression sickness (DCS) or venous gas emboli (VGE) outcomes of a proposed air break in oxygen prebreathe (PB) project, then decisions about the final experiment design must be made. We evaluated if the incidence of DCS and VGE from tests in altitude chambers over 20 years were different between men and women after resting and exercise PB protocols. Nitrogen washout during PB is our primary risk mitigation strategy to prevent subsequent DCS and VGE in subjects. Bubbles in the pulmonary artery (venous blood) were detected from the precordial position using Doppler ultrasound bubble detectors. The subjects were monitored for VGE for four min at about 15 min intervals for the duration of the altitude exposure, with maximum bubble grade assigned a Spencer Grade of IV.

Optical Interferometry Motivation and History

NASA Technical Reports Server (NTRS)

Lawson, Peter

2006-01-01

A history and motivation of stellar interferometry is presented. The topics include: 1) On Tides, Organ Pipes, and Soap Bubbles; 2) Armand Hippolyte Fizeau (1819-1896); 3) Fizeau Suggests Stellar Interferometry 1867; 4) Edouard Stephan (1837-1923); 5) Foucault Refractor; 6) Albert A. Michelson (1852-1931); 7) On the Application of Interference Methods to Astronomy (1890); 8) Moons of Jupiter (1891); 9) Other Applications in 19th Century; 10) Timeline of Interferometry to 1938; 11) 30 years goes by; 12) Mount Wilson Observatory; 13) Michelson's 20 ft Interferometer; 14) Was Michelson Influenced by Fizeau? 15) Work Continues in the 1920s and 30s; 16) 50 ft Interferometer (1931-1938); 17) Light Paths in the 50 ft Interferometer; 18) Ground-level at the 50 ft; 19) F.G. Pease (1881-1938); 20) Timeline of Optical Interferometry to 1970; 21) A New Type of Stellar Interferometer (1956); 22) Intensity Interferometer (1963- 1976; 23) Robert Hanbury Brown; 24) Interest in Optical Interferometry in the 1960s; 25) Interferometry in the Early 1970s; and 26) A New Frontier is Opened up in 1974.

A Study of the Momentum Distributions of the Final State Hadrons in Neutrino - Nucleus Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swider, Gregory M.

1980-12-01

In an experiment using the Fermilab 15-foot Bubble Chamber/Two-Plane EMI with a 47 percent (atomic) neon-in-hydrogen fill exposed to the quadrupole-triplet neutrino beam, we have identified some 9600 neutrino charged-current events....

Unprecedented pressure increase in deep magma reservoir triggered by lava-dome collapse

NASA Astrophysics Data System (ADS)

Voight, B.; Linde, A. T.; Sacks, I. S.; Mattioli, G. S.; Sparks, R. S. J.; Elsworth, D.; Hidayat, D.; Malin, P. E.; Shalev, E.; Widiwijayanti, C.; Young, S. R.; Bass, V.; Clarke, A.; Dunkley, P.; Johnston, W.; McWhorter, N.; Neuberg, J.; Williams, P.

2006-02-01

The collapse of the Soufrière Hills Volcano lava dome on Montserrat in July 2003 is the largest such event worldwide in the historical record. Here we report on borehole dilatometer data recording a remarkable and unprecedented rapid (~600s) pressurisation of a magma chamber, triggered by this surface collapse. The chamber expansion is indicated by an expansive offset at the near dilatometer sites coupled with contraction at the far site. By analyzing the strain data and using added constraints from experimental petrology and long-term edifice deformation from GPS geodesy, we prefer a source centered at approximately 6 km depth below the crater for an oblate spheroid with overpressure increase of order 1 MPa and average radius ~1 km. Pressurisation is attributed to growth of 1-3% of gas bubbles in supersaturated magma, triggered by the dynamics of surface unloading. Recent simulations demonstrate that pressure recovery from bubble growth can exceed initial pressure drop by nearly an order of magnitude.

Method for nanoencapsulation of aerogels and nanoencapsulated aerogels produced by such method

NASA Technical Reports Server (NTRS)

Sullivan, Thomas A. (Inventor)

2007-01-01

A method for increasing the compressive modulus of aerogels comprising: providing aerogel substrate comprising a bubble matrix in a chamber; providing monomer to the chamber, the monomer comprising vapor phase monomer which polymerizes substantially free of polymerization byproducts; depositing monomer from the vapor phase onto the surface of the aerogel substrate under deposition conditions effective to produce a vapor pressure sufficient to cause the vapor phase monomer to penetrate into the bubble matrix and deposit onto the surface of the aerogel substrate, producing a substantially uniform monomer film; and, polymerizing the substantially uniform monomer film under polymerization conditions effective to produce polymer coated aerogel comprising a substantially uniform polymer coating substantially free of polymerization byproducts.Polymer coated aerogel comprising aerogel substrate comprising a substantially uniform polymer coating, said polymer coated aerogel comprising porosity and having a compressive modulus greater than the compressive modulus of the aerogel substrate, as measured by a 100 lb. load cell at 1 mm/minute in the linear range of 20% to 40% compression.

Pressure gradient induced generation of microbubbles

NASA Astrophysics Data System (ADS)

Evangelio, Alvaro; Campo-Cortes, Francisco; Gordillo, Jose Manuel

2015-11-01

It is well known that the controlled production of monodisperse bubbles possesses uncountable applications in medicine, pharmacy and industry. Here we provide with a detailed physical description of the bubble formation processes taking place in a type of flow where the liquid pressure gradient can be straightforwardly controlled. In our experiments, a gas flow rate discharges through a cylindrical needle into a pressurized chamber. The pressure gradient created from the exit of the injection needle towards the entrance of a extraction duct promotes the stretching of the gas ligament downstream. In our analysis, which is supported by an exhaustive experimental study in which the liquid viscosity is varied by three orders of magnitude, different regimes can be distinguished depending mainly on the Reynolds number. Through our physical modeling, we provide closed expressions for both the bubbling frequencies and for the bubble diameters as well as the conditions under which a monodisperse generation is obtained in all regimes found. The excellent agreement between our expressions and the experimental data fully validates our physical modeling.

Analysis of Bacterial Detachment from Substratum Surfaces by the Passage of Air-Liquid Interfaces

PubMed Central

Gómez-Suárez, Cristina; Busscher, Henk J.; van der Mei, Henny C.

2001-01-01

A theoretical analysis of the detachment of bacteria adhering to substratum surfaces upon the passage of an air-liquid interface is given, together with experimental results for bacterial detachment in the absence and presence of a conditioning film on different substratum surfaces. Bacteria (Streptococcus sobrinus HG1025, Streptococcus oralis J22, Actinomyces naeslundii T14V-J1, Bacteroides fragilis 793E, and Pseudomonas aeruginosa 974K) were first allowed to adhere to hydrophilic glass and hydrophobic dimethyldichlorosilane (DDS)-coated glass in a parallel-plate flow chamber until a density of 4 × 106 cells cm−2 was reached. For S. sobrinus HG1025, S. oralis J22, and A. naeslundii T14V-J1, the conditioning film consisted of adsorbed salivary components, while for B. fragilis 793E and P. aeruginosa 974K, the film consisted of adsorbed human plasma components. Subsequently, air bubbles were passed through the flow chamber and the bacterial detachment percentages were measured. For some experimental conditions, like with P. aeruginosa 974K adhering to DDS-coated glass and an air bubble moving at high velocity (i.e., 13.6 mm s−1), no bacteria detached upon passage of an air-liquid interface, while for others, detachment percentages between 80 and 90% were observed. The detachment percentage increased when the velocity of the passing air bubble decreased, regardless of the bacterial strain and substratum surface hydrophobicity involved. However, the variation in percentages of detachment by a passing air bubble depended greatly upon the strain and substratum surface involved. At low air bubble velocities the hydrophobicity of the substratum had no influence on the detachment, but at high air bubble velocities all bacterial strains were more efficiently detached from hydrophilic glass substrata. Furthermore, the presence of a conditioning film could either inhibit or stimulate detachment. The shape of the bacterial cell played a major role in detachment at high air bubble velocities, and spherical strains (i.e., streptococci) detached more efficiently than rod-shaped organisms. The present results demonstrate that methodologies to study bacterial adhesion which include contact with a moving air-liquid interface (i.e., rinsing and dipping) yield detachment of an unpredictable number of adhering microorganisms. Hence, results of studies based on such methodologies should be referred as “bacterial retention” rather than “bacterial adhesion”. PMID:11375160

Analysis of bacterial detachment from substratum surfaces by the passage of air-liquid interfaces.

PubMed

Gómez-Suárez, C; Busscher, H J; van der Mei, H C

2001-06-01

A theoretical analysis of the detachment of bacteria adhering to substratum surfaces upon the passage of an air-liquid interface is given, together with experimental results for bacterial detachment in the absence and presence of a conditioning film on different substratum surfaces. Bacteria (Streptococcus sobrinus HG1025, Streptococcus oralis J22, Actinomyces naeslundii T14V-J1, Bacteroides fragilis 793E, and Pseudomonas aeruginosa 974K) were first allowed to adhere to hydrophilic glass and hydrophobic dimethyldichlorosilane (DDS)-coated glass in a parallel-plate flow chamber until a density of 4 x 10(6) cells cm(-2) was reached. For S. sobrinus HG1025, S. oralis J22, and A. naeslundii T14V-J1, the conditioning film consisted of adsorbed salivary components, while for B. fragilis 793E and P. aeruginosa 974K, the film consisted of adsorbed human plasma components. Subsequently, air bubbles were passed through the flow chamber and the bacterial detachment percentages were measured. For some experimental conditions, like with P. aeruginosa 974K adhering to DDS-coated glass and an air bubble moving at high velocity (i.e., 13.6 mm s(-1)), no bacteria detached upon passage of an air-liquid interface, while for others, detachment percentages between 80 and 90% were observed. The detachment percentage increased when the velocity of the passing air bubble decreased, regardless of the bacterial strain and substratum surface hydrophobicity involved. However, the variation in percentages of detachment by a passing air bubble depended greatly upon the strain and substratum surface involved. At low air bubble velocities the hydrophobicity of the substratum had no influence on the detachment, but at high air bubble velocities all bacterial strains were more efficiently detached from hydrophilic glass substrata. Furthermore, the presence of a conditioning film could either inhibit or stimulate detachment. The shape of the bacterial cell played a major role in detachment at high air bubble velocities, and spherical strains (i.e., streptococci) detached more efficiently than rod-shaped organisms. The present results demonstrate that methodologies to study bacterial adhesion which include contact with a moving air-liquid interface (i.e., rinsing and dipping) yield detachment of an unpredictable number of adhering microorganisms. Hence, results of studies based on such methodologies should be referred as "bacterial retention" rather than "bacterial adhesion".

Elimination of CT-detected gas bubbles derived from decompression illness with abdominal symptoms after a short hyperbaric oxygen treatment in a monoplace chamber: a case report.

PubMed

Oyaizu, Takuya; Enomoto, Mitsuhiro; Tsujimoto, Toshihide; Kojima, Yasushi; Okawa, Atsushi; Yagishita, Kazuyoshi

2017-01-01

We report the case of a 54-year-old male compressed-air worker with gas bubbles detected by computed tomography (CT). He had complained of strong abdominal pain 30 minutes after decompression after working at a pressure equivalent to 17 meters of sea water for three hours. The initial CT images revealed gas bubbles in the intrahepatic portal vein, pulmonary artery and bilateral femoral vein. After the first hyperbaric oxygen treatment (HBO₂ at 2.5 atmospheres absolute/ATA for 150 minutes), no bubbles were detected on repeat CT examination. The patient still exhibited abdominal distension, mild hypesthesia and slight muscle weakness in the upper extremities. Two sessions of U.S. Navy Treatment Table 6 (TT6) were performed on Days 6 and 7 after onset. The patient recovered completely on Day 7. This report describes the important role of CT imaging in evaluating intravascular gas bubbles as well as eliminating the diagnosis of other conditions when divers or compressed-air workers experience uncommon symptoms of decompression illness. In addition, a short treatment table of HBO₂ using non-TT6 HBO₂ treatment may be useful to reduce gas bubbles and the severity of decompression illness in emergent cases. Copyright© Undersea and Hyperbaric Medical Society.

Coarsening Dynamics and Marangoni Effects in Thin Liquid Crystal Bubbles in Microgravity

NASA Technical Reports Server (NTRS)

Clark, Noel; Glaser, Matthew; Maclennan, Joseph; Park, Cheol; Tin, Padetha; Hall, Nancy R.; Sheehan, Christopher; Storck, Jennifer

2015-01-01

The Observation and Analysis of Smectic Islands in Space (OASIS) flight hardware was successfully launched on SpaceX-6 on April 15, 2015 and was operated in the Microgravity Science Glovebox (MSG) on board the International Space Station (ISS). The OASIS project comprises a series of experiments that probe the interfacial and hydrodynamic behavior of spherical-bubble freely suspended liquid crystal (FSLC) membranes in space. These are the thinnest known stable condensed phase structures, making them ideal for studies of two-dimensional (2D) coarsening dynamics and thermocapillary phenomena in microgravity. The OASIS experimental investigation was carried out using four different smectic A and C liquid crystal materials in four separate sample chambers housed inside the MSG. In this report, we present the behavior of collective dynamics on 2D bubble surface, including the equilibrium spatial organization and interaction of islands in electric fields and temperature gradients, and the diffusion and coalescence-driven coarsening dynamics of island emulsions in microgravity. We have observed spontaneous bubble thickening behavior caused by gradients between the bubble-blowing needle and ambient air temperatures. A uniform, thicker band forms during coarsening as a result of non-uniform heating by the LED illumination panels. These are proposed to be a result of Marangoni convection on the bubble surface.

'Blue bubble' technique: an ab interno approach for Descemet separation in deep anterior lamellar keratoplasty using trypan blue stained viscoelastic device.

PubMed

Livny, Eitan; Bahar, Irit; Hammel, Naama; Nahum, Yoav

2018-04-01

In this study, we examined a novel variant of 'big-bubble' deep anterior lamellar keratoplasty using trypan-blue-stained viscoelastic device for the creation of a pre-descemetic bubble. Ten corneoscleral rims were mounted on an artificial anterior chamber (AC). The AC was filled with air through a limbal paracentesis. A Melles' triangulated spatula was inserted through the paracentesis, with its tip penetrating the AC, was then slightly retracted and pushed into the deep stroma above the roof of the paracentesis. A mixture of trypan blue and viscoelastic device (Healon, Abbott Medical Optics, Abbott Park, Illinois) was injected into this intra-stromal pocket using a 27-G cannula to create a pre-descemetic separation bubble. Bubble type and visualization of dyed viscoelastic device were noted. The method was later employed in three cases. In all 10 corneoscleral rims, the technique successfully created a visible pre-descemetic (type 1) bubble that could be expanded up to the predicted diameter of trephination. Subsequent trephination and the removal of corneal stroma were uneventful. In two out of four clinical cases, a type 1 bubble was created, while in two others, visco-dissection failed and dyed viscoelastic was seen in the AC. The presented technique holds promise of being a relatively easy to perform, predictable and well-controlled alternative for achieving a type 1 bubble during deep anterior lamellar keratoplasty surgery. The trypan-blue-stained viscoelastic device facilitates proper visualization and control of the separation bubble and assists in identifying the penetrance to the separation bubble prior to removal of the stromal cap. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

Electrolysis cell stimulation

NASA Technical Reports Server (NTRS)

Gordon, L. H.; Phillips, B. R.; Evangelista, J.

1978-01-01

Computer program represents attempt to understand and model characteristics of electrolysis cells. It allows user to determine how cell efficiency is affected by temperature, pressure, current density, electrolyte concentration, characteristic dimensions, membrane resistance, and electrolyte circulation rate. It also calculates ratio of bubble velocity to electrolyte velocity for anode and cathode chambers.

A Simple Estimate of the Mass of the Positron.

ERIC Educational Resources Information Center

Jones, Goronwy Tudor

1993-01-01

Discusses a small part of the final state of a high-energy neutrino interaction: a head-on collision of a positron and a stationary electron. Provides a bubble chamber picture and describes the resulting particle effects. Uses momentum to determine the mass of the positron. (MVL)

PDMS free-flow electrophoresis chips with integrated partitioning bars for bubble segregation.

PubMed

Köhler, Stefan; Weilbeer, Claudia; Howitz, Steffen; Becker, Holger; Beushausen, Volker; Belder, Detlev

2011-01-21

In this work, a microfluidic free-flow electrophoresis device with a novel approach for preventing gas bubbles from entering the separation area is presented. This is achieved by integrating partitioning bars to reduce the channel depth between electrode channels and separation chamber in order to obtain electrical contact and simultaneously prevent bubbles from entering the separation area. The three-layer sandwich chip features a reusable carrier plate with integrated ports for fluidic connection combined with a softlithographically cast microfluidic PDMS layer and a sealing glass slide. This design allows for a straightforward and rapid chip prototyping process. The performance of the device is demonstrated by free-flow zone electrophoretic separations of fluorescent dye mixtures as well as by the separation of labeled amines and amino acids with separation voltages up to 297 V.

Technical Review of the Laboratory Biosphere Closed Ecological System Facility

NASA Astrophysics Data System (ADS)

Dempster, W.; van Thillo, M.; Alling, A.; Allen, J.; Silverstone, S.; Nelson, M.

The "Laboratory Biosphere", a new closed ecological system facility in Santa Fe, New Mexico (USA) has been constructed and became operational in May 2002. Built and operated by the Global Ecotechnics consortium (Biosphere Technologies and Biosphere Foundation with Biospheric Design Inc., and the Institute of Ecotechnics), the research apparatus for intensive crop growth, biogeochemical cycle dynamics and recycling of inedible crop biomass comprises a sealed cylindrical steel chamber and attached variable volume chamber (lung) to prevent pressures caused by the expansion and contraction of the contained air. The cylindrical growing chamber is 3.7m (12 feet) long and 3.7m (12 foot) diameter, giving an internal volume of 34 m3 (1200 ft 3 ). The two crop growth beds cover 5.5 m2, with a soil depth of 0.3m (12 inches), with 12 x 1000 watt high-pressure sodium lights capable of variable lighting of 40-70 mol per m2 per day. A small soil bed reactor in the chamber can be activated to help with metabolism of chamber trace gases. The volume of the attached variable volume chamber (lung) can range between 0-11 m3 (0-400 ft 3 ). Evapotranspired and soil leachate water are collected, combined and recycled to water the planting beds. Sampling ports enable testing of water quality of leachate, condensate and irrigation water. Visual inspection windows provide views of the entire interior and growing beds. The chamber is also outfitted with an airlock to minimize air exchange when people enter and work in the chamber. Continuous sensors include atmospheric CO2 and oxygen, temperature, humidity, soil moisture, light level and water levels in reservoirs. Both "sniffer" (air ports) and "sipper" (water ports) will enable collection of water or air samples for detailed analysis. This paper reports on the development of this new soil-based bioregenerative life support closed system apparatus and its technical challenges and capabilities.

29. Photocopy of photograph (original print located in LBNL Photo ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

29. Photocopy of photograph (original print located in LBNL Photo Lab Collection). Photographer unknown. July, 1959. Morgue 1959-46 (P-1). ALVAREZ BUBBLE CHAMBER GROUP (L. TO R.) HERNANDEZ, McMILLAN, ALVAREZ, GOW - University of California Radiation Laboratory, Bevatron, 1 Cyclotron Road, Berkeley, Alameda County, CA

A parametrical study of disinfection with hydrodynamic cavitation.

PubMed

Arrojo, S; Benito, Y; Tarifa, A Martínez

2008-07-01

The physical and chemical conditions generated by cavitation bubbles can be used to destroy microorganisms and disinfect wastewater. The effect of different cavitation chamber designs and diverse operational parameters on the inactivation rate of Escherichia coli have been studied and used to understand the mechanisms involved in cell disruption.

Creating the Deep Space Environment for Testing the James Webb Space Telescope (JWST) at NASA Johnson Space Center's Chamber A

NASA Technical Reports Server (NTRS)

Homan, Jonathan L.; Cerimele, Mary P.; Montz, Michael E.; Bachtel, Russell; Speed, John; O'Rear, Patrick

2013-01-01

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. It was originally designed and built in the mid 1960 s to test the Apollo Command and Service Module and several manned tests were conducted on that spacecraft, contributing to the success of the program. The chamber has been used since that time to test spacecraft active thermal control systems, Shuttle DTO, DOD, and ESA hardware in simulated Low Earth Orbit (LEO) conditions. NASA is now moving from LEO towards exploration of locations with environments approaching those of deep space. Therefore, Chamber A has undergone major modifications to enable it to simulate these deeper space environments. Environmental requirements were driven, and modifications were funded by the James Webb Space Telescope program, and this telescope which will orbit Solar/Earth L2, will be the first test article to benefit from the chamber s new capabilities. To accommodate JWST, the Chamber A high vacuum system has been modernized, additional LN2 shrouds have been installed, the liquid nitrogen system has been modified to remove dependency on electrical power and increase its reliability, a new helium shroud/refrigeration system has been installed to create a colder more stable and uniform heat sink, and the controls have been updated to increase the level of automation and improve operator interfaces. Testing of these major modifications was conducted in August of 2012 and this initial test was very successful, with all major systems exceeding their performance requirements. This paper will outline the changes in overall environmental requirements, discuss the technical design data that was used in the decisions leading to the extensive modifications, and describe the new capabilities of the chamber.

Creating the Deep Space Environment for Testing the James Webb Space Telescope at NASA Johnson Space Center's Chamber A

NASA Technical Reports Server (NTRS)

Homan, Jonathan L.; Cerimele, Mary P.; Montz, Michael E.; Bachtel, Russell; Speed, John; O'Rear, Patrick

2013-01-01

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft.) in diameter and 36.6 m (120 ft.) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. It was originally designed and built in the mid 1960 s to test the Apollo Command and Service Module and several manned tests were conducted on that spacecraft, contributing to the success of the program. The chamber has been used since that time to test spacecraft active thermal control systems, Shuttle DTO, DOD, and ESA hardware in simulated Low Earth Orbit (LEO) conditions. NASA is now moving from LEO towards exploration of locations with environments approaching those of deep space. Therefore, Chamber A has undergone major modifications to enable it to simulate these deeper space environments. Environmental requirements were driven, and modifications were funded by the James Webb Space Telescope program, and this telescope, which will orbit Solar/Earth L2, will be the first test article to benefit from the chamber s new capabilities. To accommodate JWST, the Chamber A high vacuum system has been modernized, additional LN2 shrouds have been installed, the liquid nitrogen system has been modified to minimize dependency on electrical power and increase its reliability, a new helium shroud/refrigeration system has been installed to create a colder more stable and uniform heat sink, and the controls have been updated to increase the level of automation and improve operator interfaces. Testing of these major modifications was conducted in August of 2012 and this initial test was very successful, with all major systems exceeding their performance requirements. This paper will outline the changes in overall environmental requirements, discuss the technical design data that was used in the decisions leading to the extensive modifications, and describe the new capabilities of the chamber.

Creating the Deep Space Environment for Testing the James Webb Space Telescope at the Johnson Space Center's Chamber A

NASA Technical Reports Server (NTRS)

Homan, Jonathan L.; Cerimele, Mary P.; Montz, Michael E.

2012-01-01

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. It was originally designed and built in the mid 1960's to test the Apollo Command and Service Module and several manned tests were conducted on that spacecraft, contributing to the success of the program. The chamber has been used since that time to test spacecraft active thermal control systems, Shuttle DTO, DOD, and ESA hardware in simulated Low Earth Orbit (LEO) conditions. NASA is now moving from LEO towards exploration of locations with environments approaching those of deep space. Therefore, Chamber A has undergone major modifications to enable it to simulate these deeper space environments. Environmental requirements were driven, and the modifications were funded, by the James Webb Space Telescope program, and this telescope which will orbit Solar/Earth L2, will be the first test article to benefit from the chamber s new capabilities. To accommodate JWST, the Chamber A high vacuum system has been modernized, additional LN2 shrouds have been installed, the liquid nitrogen system has been modified to remove dependency on electrical power and increase its reliability, a new helium shroud/refrigeration system has been installed to create a colder more stable and uniform heat sink and, the controls have been updated to increase the level of automation and improve operator interfaces. Testing of these major modifications was conducted in August 2012 and this initial test was very successful, with all major systems exceeding their performance requirements. This paper will outline the changes in the overall environmental requirements, discuss the technical design data that was used in the decisions leading to the extensive modifications, and describe the new capabilities of the chamber.

An Examination of Ultrasound Measured Tissue Perfusion on Breast Cancer

DTIC Science & Technology

1998-12-01

is similar to those of the study by Ivey et al. [9] in which high intensity fields were used to produce cavitation bubbles for ultrasound contrast...ft * * AD AWARD NUMBER DAMD17-94-J-4144 TITLE: ^ Examination of Ultrasound Measured Tissue Perfusion on Breast Cancer...Examination of Ultrasound Measured Tissue Perfusion on Breast Cancer 3. REPORT TYPE AND DATES COVERED Final (1 Jun 94 - 30 Nov 98) 5. FUNDING

Molecular dynamics simulations of bubble nucleation in dark matter detectors.

PubMed

Denzel, Philipp; Diemand, Jürg; Angélil, Raymond

2016-01-01

Bubble chambers and droplet detectors used in dosimetry and dark matter particle search experiments use a superheated metastable liquid in which nuclear recoils trigger bubble nucleation. This process is described by the classical heat spike model of F. Seitz [Phys. Fluids (1958-1988) 1, 2 (1958)PFLDAS0031-917110.1063/1.1724333], which uses classical nucleation theory to estimate the amount and the localization of the deposited energy required for bubble formation. Here we report on direct molecular dynamics simulations of heat-spike-induced bubble formation. They allow us to test the nanoscale process described in the classical heat spike model. 40 simulations were performed, each containing about 20 million atoms, which interact by a truncated force-shifted Lennard-Jones potential. We find that the energy per length unit needed for bubble nucleation agrees quite well with theoretical predictions, but the allowed spike length and the required total energy are about twice as large as predicted. This could be explained by the rapid energy diffusion measured in the simulation: contrary to the assumption in the classical model, we observe significantly faster heat diffusion than the bubble formation time scale. Finally we examine α-particle tracks, which are much longer than those of neutrons and potential dark matter particles. Empirically, α events were recently found to result in louder acoustic signals than neutron events. This distinction is crucial for the background rejection in dark matter searches. We show that a large number of individual bubbles can form along an α track, which explains the observed larger acoustic amplitudes.

Data reduction and analysis of graphite fiber release experiments

NASA Technical Reports Server (NTRS)

Lieberman, P.; Chovit, A. R.; Sussholz, B.; Korman, H. F.

1979-01-01

The burn and burn/explode effects on aircraft structures were examined in a series of fifteen outdoor tests conducted to verify the results obtained in previous burn and explode tests of carbon/graphite composite samples conducted in a closed chamber, and to simulate aircraft accident scenarios in which carbon/graphite fibers would be released. The primary effects that were to be investigaged in these tests were the amount and size distribution of the conductive fibers released from the composite structures, and how these various sizes of fibers transported downwind. The structures included plates, barrels, aircraft spoilers and a cockpit. The heat sources included a propane gas burner and 20 ft by 20 ft and 40 ft by 60 ft JP-5 pool fires. The larger pool fire was selected to simulate an aircraft accident incident. The passive instrumentation included sticky paper and sticky bridal veil over an area 6000 ft downwind and 3000 ft crosswind. The active instrumentation included instrumented meteorological towers, movies, infrared imaging cameras, LADAR, high voltage ball gages, light emitting diode gages, microwave gages and flame velocimeter.

Surface activity of lipid extract surfactant in relation to film area compression and collapse.

PubMed

Schürch, S; Schürch, D; Curstedt, T; Robertson, B

1994-08-01

The physical properties of modified porcine surfactant (Curosurf), isolated from minced lungs by extraction with chloroform-methanol and further purified by liquid-gel chromatography, were investigated with the captive bubble technique. Bubble size, and thus the surface tension of an insoluble film at the bubble surface, is altered by changing the pressure within the closed bubble chamber. The film surface tension and area are determined from the shape (height and diameter) of the bubble. Adsorption of fresh Curosurf is characterized by stepwise decreases in surface tension, which can easily be observed by sudden quick movements of the bubble apex. These "adsorption clicks" imply a cooperative movement of large collective units of molecules, approximately 10(14) (corresponding to approximately 120 ng of phospholipid) or approximately 10(18) molecules/m2, into the interface during adsorption. Films formed in this manner are already highly enriched in dipalmitoyl phosphatidylcholine, as seen by the extremely low compressibility, close to that of dipalmitoyl phosphatidylcholine. Near-zero minimum tensions are obtained, even at phospholipid concentrations as low as 50 micrograms/ml. During dynamic cycling (20-50 cycles/min), low minimum surface tensions, good film stability, low compressibility, and maximum surface tensions between 30 and 40 mN/m are possible only if the films are not overcompressed near zero surface tension; i.e., the overall film area compression should not substantially exceed 30%.

Coarsening Dynamics of Inclusions and Thermocapillary Phenomena in Smectic Liquid Crystal Bubbles

NASA Astrophysics Data System (ADS)

Park, Cheol; Maclennan, Joseph; Glaser, Matthew; Clark, Noel; Trittel, Torsten; Eremin, Alexey; Stannarius, Ralf; Tin, Padetha; Hall, Nancy

The Observation and Analysis of Smectic Islands in Space (OASIS) project comprises a series of experiments that probe interfacial and hydrodynamic behavior of thin spherical-bubbles of smectic liquid crystal in microgravity. Smectic films are the thinnest known stable condensed phase structures, making them ideal for studies of two-dimensional (2D) coarsening dynamics and thermocapillary phenomena in microgravity. The OASIS flight hardware was launched on SpaceX-6 in April 2015 and experiments were carried out on the International Space Station using four different smectic A and C liquid crystal materials in separate sample chambers. We will describe the behavior of collective island dynamics on the bubbles, including temperature gradient-induced themomigration, and the diffusion and coalescence-driven coarsening dynamics of island emulsions in microgravity. This work was supported by NASA Grant No. NNX-13AQ81G, and NSF MRSEC Grants No. DMR-0820579 and DMR-1420736.

Bubble Combustion

NASA Technical Reports Server (NTRS)

Corrigan, Jackie

2004-01-01

A method of energy production that is capable of low pollutant emissions is fundamental to one of the four pillars of NASA s Aeronautics Blueprint: Revolutionary Vehicles. Bubble combustion, a new engine technology currently being developed at Glenn Research Center promises to provide low emissions combustion in support of NASA s vision under the Emissions Element because it generates power, while minimizing the production of carbon dioxide (CO2) and nitrous oxides (NOx), both known to be Greenhouse gases. and allows the use of alternative fuels such as corn oil, low-grade fuels, and even used motor oil. Bubble combustion is analogous to the inverse of spray combustion: the difference between bubble and spray combustion is that spray combustion is spraying a liquid in to a gas to form droplets, whereas bubble combustion involves injecting a gas into a liquid to form gaseous bubbles. In bubble combustion, the process for the ignition of the bubbles takes place on a time scale of less than a nanosecond and begins with acoustic waves perturbing each bubble. This perturbation causes the local pressure to drop below the vapor pressure of the liquid thus producing cavitation in which the bubble diameter grows, and upon reversal of the oscillating pressure field, the bubble then collapses rapidly with the aid of the high surface tension forces acting on the wall of the bubble. The rapid and violent collapse causes the temperatures inside the bubbles to soar as a result of adiabatic heating. As the temperatures rise, the gaseous contents of the bubble ignite with the bubble itself serving as its own combustion chamber. After ignition, this is the time in the bubble s life cycle where power is generated, and CO2, and NOx among other species, are produced. However, the pollutants CO2 and NOx are absorbed into the surrounding liquid. The importance of bubble combustion is that it generates power using a simple and compact device. We conducted a parametric study using CAVCHEM, a computational model developed at Glenn, that simulates the cavitational collapse of a single bubble in a liquid (water) and the subsequent combustion of the gaseous contents inside the bubble. The model solves the time-dependent, compressible Navier-Stokes equations in one-dimension with finite-rate chemical kinetics using the CHEMKIN package. Specifically, parameters such as frequency, pressure, bubble radius, and the equivalence ratio were varied while examining their effect on the maximum temperature, radius, and chemical species. These studies indicate that the radius of the bubble is perhaps the most critical parameter governing bubble combustion dynamics and its efficiency. Based on the results of the parametric studies, we plan on conducting experiments to study the effect of ultrasonic perturbations on the bubble generation process with respect to the bubble radius and size distribution.

Fixed dilated pupil (Urrets-Zavalia syndrome) after air/gas injection after deep lamellar keratoplasty for keratoconus.

PubMed

Maurino, Vincenzo; Allan, Bruce D S; Stevens, Julian D; Tuft, Stephen J

2002-02-01

To describe three cases of fixed dilated pupil and presumed iris ischemia (Urrets-Zavalia syndrome) after anterior chamber air/gas injection after deep lamellar keratoplasty for keratoconus. Interventional case series. Three eyes of three patients with keratoconus underwent deep lamellar keratoplasty and intraoperative or postoperative injection of air/gas in the anterior chamber to appose the host-donor lamellar graft interface. Urrets-Zavalia syndrome was diagnosed on clinical grounds in three cases and was associated with the Descemet membrane microperforation intraoperatively and introduction of air/gas into the anterior chamber intraoperatively or postoperatively. A fixed dilated pupil is an uncommon complication of penetrating keratoplasty for keratoconus that can also develop after deep lamellar keratoplasty. Leaving an air or gas bubble in the anterior chamber of a phakic eye after deep lamellar keratoplasty is a risk factor and should therefore be avoided.

Paving the way for space gardens

NASA Technical Reports Server (NTRS)

Phillips, Patricia

1990-01-01

The Ecological Life Support System, a plant growth experiment now in its third year of closed chamber production at the NASA Kennedy Space Center, is discussed. Possible spin-off applications of hydrophonics experiments are noted. It is projected that long-term goals will include the integration of this garden system into the process of waste recycling for fertilization, air refreshment, and potable water recovery in a closed environment. The Biomass Production Chamber, a two-story bubble-shape steel biosphere modified from a Mercury/Gemini program attitude chamber provides a usable volume of 7.3 m x 3.6 m in diameter containing growing racks, piping for nutrient solutions, specialized lighting and sensors that provide information to the computers controlling the chamber and its functions. Computer programs provide highly sensitive monitoring and regulation of the system. Crops successfully harvested to date include dwarf wheat, lettuce, and soybeans.

A microfluidic sub-critical water extraction instrument

NASA Astrophysics Data System (ADS)

Sherrit, Stewart; Noell, Aaron C.; Fisher, Anita; Lee, Mike C.; Takano, Nobuyuki; Bao, Xiaoqi; Kutzer, Thomas C.; Grunthaner, Frank

2017-11-01

This article discusses a microfluidic subcritical water extraction (SCWE) chip for autonomous extraction of amino acids from astrobiologically interesting samples. The microfluidic instrument is composed of three major components. These include a mixing chamber where the soil sample is mixed and agitated with the solvent (water), a subcritical water extraction chamber where the sample is sealed with a freeze valve at the chip inlet after a vapor bubble is injected into the inlet channels to ensure the pressure in the chip is in equilibrium with the vapor pressure and the slurry is then heated to ≤200 °C in the SCWE chamber, and a filter or settling chamber where the slurry is pumped to after extraction. The extraction yield of the microfluidic SCWE chip process ranged from 50% compared to acid hydrolysis and 80%-100% compared to a benchtop microwave SCWE for low biomass samples.

Luis Alvarez, the Hydrogen Bubble Chamber, Tritium, and Dinosaurs

Science.gov Websites

linear accelerator, patented three types of radar still used today, designed an instrument that for 15 is available in documents and on the Web. Documents: Berkeley Proton Linear Accelerator, DOE Technical Report Download Adobe PDF Reader , June 1985 History of Proton Linear Accelerators, DOE Technical

Soap film gas flowmeter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalin, H.S.; Bermudez, J.E.; Fleming, W.T.

1987-09-08

A soap film gas flowmeter is described comprising: a flow tube having a hollow body with opposite open ends through which a soap film is propelled and a first closed chamber housing a soap solution. It also includes means for supporting the flow tube in a substantially vertical position with the open bottom end of the flow tube disposed in the first chamber above the soap solution; a second closed chamber into which the open top end of the flow tube extends and gas inlet means for introducing gas into the first chamber at a flow rate to be measuredmore » using the flowmeters. A gas exit means is included for discharging the gas introduced into the first chamber through the second chamber. Plus there are means for generating a single soap bubble from the soap solution substantially at the bottom end of the flow tube and a relatively large opening in the flowtube for providing an open passageway for inlet gas to pass through the flowtube when the bottom open end of the flowtube is covered by the soap solution.« less

A laser based reusable microjet injector for transdermal drug delivery

NASA Astrophysics Data System (ADS)

Han, Tae-hee; Yoh, Jack J.

2010-05-01

A laser based needle-free liquid drug injection device has been developed. A laser beam is focused inside the liquid contained in the rubber chamber of microscale. The focused laser beam causes explosive bubble growth, and the sudden volume increase in a sealed chamber drives a microjet of liquid drug through the micronozzle. The exit diameter of a nozzle is 125 μm and the injected microjet reaches an average velocity of 264 m/s. This device adds the time-varying feature of microjet to the current state of liquid injection for drug delivery.

Rigorous buoyancy driven bubble mixing for centrifugal microfluidics.

PubMed

Burger, S; Schulz, M; von Stetten, F; Zengerle, R; Paust, N

2016-01-21

We present batch-mode mixing for centrifugal microfluidics operated at fixed rotational frequency. Gas is generated by the disk integrated decomposition of hydrogen peroxide (H2O2) to liquid water (H2O) and gaseous oxygen (O2) and inserted into a mixing chamber. There, bubbles are formed that ascent through the liquid in the artificial gravity field and lead to drag flow. Additionaly, strong buoyancy causes deformation and rupture of the gas bubbles and induces strong mixing flows in the liquids. Buoyancy driven bubble mixing is quantitatively compared to shake mode mixing, mixing by reciprocation and vortex mixing. To determine mixing efficiencies in a meaningful way, the different mixers are employed for mixing of a lysis reagent and human whole blood. Subsequently, DNA is extracted from the lysate and the amount of DNA recovered is taken as a measure for mixing efficiency. Relative to standard vortex mixing, DNA extraction based on buoyancy driven bubble mixing resulted in yields of 92 ± 8% (100 s mixing time) and 100 ± 8% (600 s) at 130g centrifugal acceleration. Shake mode mixing yields 96 ± 11% and is thus equal to buoyancy driven bubble mixing. An advantage of buoyancy driven bubble mixing is that it can be operated at fixed rotational frequency, however. The additional costs of implementing buoyancy driven bubble mixing are low since both the activation liquid and the catalyst are very low cost and no external means are required in the processing device. Furthermore, buoyancy driven bubble mixing can easily be integrated in a monolithic manner and is compatible to scalable manufacturing technologies such as injection moulding or thermoforming. We consider buoyancy driven bubble mixing an excellent alternative to shake mode mixing, in particular if the processing device is not capable of providing fast changes of rotational frequency or if the low average rotational frequency is challenging for the other integrated fluidic operations.

Attrition resistant catalysts for slurry-phase Fischer-Tropsch process

DOE Office of Scientific and Technical Information (OSTI.GOV)

K. Jothimurugesan

1999-11-01

The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H{sub 2}) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. Iron-based (Fe) catalysts are preferred catalysts for F-T because they are relatively inexpensive and possess reasonable activity for F-T synthesis (FTS). Their most advantages trait is their high water-gas shift (WGS) activity compared to their competitor, namely cobalt. This enables Fe F-T catalysts to process lowmore » H{sub 2}/CO ratio synthesis gas without an external shift reaction step. However, a serious problem with the use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, make the separation of catalyst from the oil/wax product very difficult if not impossible, an d result in a steady loss of catalyst from the reactor. The objectives of this research were to develop a better understanding of the parameters affecting attrition of Fe F-T catalysts suitable for use in SBCRs and to incorporate this understanding into the design of novel Fe catalysts having superior attrition resistance.« less

Electromagnetically actuated micromanipulator using an acoustically oscillating bubble

NASA Astrophysics Data System (ADS)

Kwon, J. O.; Yang, J. S.; Lee, S. J.; Rhee, K.; Chung, S. K.

2011-11-01

A novel non-invasive micromanipulation technique has been developed where a microrobot swimming in an aqueous medium manipulates micro-objects, through electromagnetic actuation using an acoustically oscillating bubble attached to the microrobot as a grasping tool. This micromanipulation concept was experimentally verified; an investigation of electromagnetic actuation and acoustic excitation was also performed. Two-dimensional propulsion of a magnetic piece was demonstrated through electromagnetic actuation, using three pairs of electric coils surrounding the water chamber, and confirming that the propulsion speed of the magnetic piece was linearly proportional to the applied current intensity. Micro-object manipulation was separately demonstrated using an air bubble with glass beads (80 µm diameter) and a steel ball (800 µm diameter) in an aqueous medium. Upon acoustic excitation of the bubble by a piezo-actuator around its resonant frequency, the generated radiation force attracted and captured the neighboring glass beads and steel ball. The grasping force was indirectly measured by exposing the glass beads captured by the oscillating bubble to a stream generated by an auto-syringe pump in a mini-channel. By measuring the maximum speed of the streaming flow when the glass beads detached from the oscillating bubble and flowed downstream, the grasping force was calculated as 50 nN, based on Stokes' drag approximation. Finally, a fish egg was successfully manipulated with the integration of electromagnetic actuation and acoustic excitation, using a mini-robot consisting of a millimeter-sized magnetic piece with a bubble attached to its bottom. This novel micromanipulation may be an efficient tool for both micro device assembly and single-cell manipulation.

Altitude Decompression Illness - The Operational Risk at Sustained Altitudes up to 35,000 ft.

DTIC Science & Technology

2001-06-01

TITLE: Operational Medical Issues in Hypo-and Hyperbaric Conditions [les Questions medicales a caractere oprationel liees aux conditions hypobares ou... hyperbares ] To order the complete compilation report, use: ADA395680 The component part is provided here to allow users access to individually authored... Hyperbaric Conditions", held in Toronto, Canada, 16-19 October 2000, and published in RTO MP-062. 37-2 by a tissue response to the presence of bubbles

Sea spray as a source of ice nucleating particles - results from the AIDA Ocean03 campaign

NASA Astrophysics Data System (ADS)

Salter, M. E.; Ickes, L.; Adams, M.; Bierbauer, S.; Bilde, M.; Christiansen, S.; Ekman, A.; Gorokhova, E.; Höhler, K.; Kiselev, A. A.; Leck, C.; Mohr, C.; Mohler, O.; Murray, B. J.; Porter, G.; Ullrich, R.; Wagner, R.

2017-12-01

Clouds and their radiative effects are one of the major influences on the radiative fluxes in the atmosphere, but at the same time they remain the largest uncertainty in climate models. This lack of understanding is especially pronounced in the high Arctic. Summertime clouds can persist over long periods in this region, which is difficult to replicate in models based on our current understanding. The clouds most often encountered in the summertime high Arctic consist of a mixture of ice crystals and super-cooled water droplets, so-called mixed-phase clouds. This cloud type is sensitive to the availability of aerosol particles, which can act as cloud condensation nuclei and ice nuclei. However, since the high Arctic is a pristine region, aerosol particles are not very abundant, and the hypothesis of open leads in the Arctic as a potentially important source of cloud and ice nucleating particles via bubble bursting has emerged. In this context, we have conducted a series of experiments at the AIDA chamber at KIT, designed to investigate the mechanisms linking marine biology, seawater chemistry and aerosol physics/potential cloud impacts. During this campaign, two marine diatom species (Melosira arctica and Skeletonema marinoi) as well as sea surface microlayer samples collected during several Arctic Ocean research cruises were investigated. To aerosolize the samples, a variety of methods were used including a sea spray simulation chamber to mimic the process of bubble-bursting. The ice nucleating efficiency (mixed-phase cloud regime) of the samples was determined either directly in the AIDA chamber during adiabatic expansions, or using the INKA continuous flow diffusion chamber, or a cold stage. Results from the campaign along with the potential implications are presented.

Attrition Resistant Iron-Based Fischer-Tropsch Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jothimurugesan, K.; Goodwin, J.G.; Spivey, J.J.

1997-03-26

The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H{sub 2}) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRS) can largely solve this problem. Iron-based (Fe) catalysts are preferred catalysts for F-T when using low CO/H{sub 2} ratio synthesis gases derived from modem coal gasifiers. This is because in addition to reasonable F-T activity, the FT catalysts also possess high water gas shift (WGS) activity. However, a serious problem withmore » the use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, making the separation of catalyst from the oil/wax product very difficult if not impossible, and results in a steady loss of catalyst from the reactor. The objectives of this research are to develop a better understanding of the parameters affecting attrition resistance of Fe F-T catalysts suitable for use in SBCRs and to incorporate this understanding into the design of novel Fe catalysts having superior attrition resistance. Catalyst preparations will be based on the use of spray drying and will be scalable using commercially available equipment. The research will employ among other measurements, attrition testing and F-T synthesis, including long duration slurry reactor runs in order to ascertain the degree of success of the various preparations. The goal is to develop an Fe catalyst which can be used in a SBCR having only an internal filter for separation of the catalyst from the liquid product, without sacrificing F-T activity and selectivity.« less

Attrition Resistant Iron-Based Fischer-Tropsch Catalysts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jothimurugesan, K.; Goodwin, J.S.; Spivey, J.J.

1997-09-22

The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO and H{sub 2}) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. Iron-based (Fe) catalysts are preferred catalysts for F-T when using low CO/H{sub 2} ratio synthesis gases derived from modern coal gasifiers. This is because in addition to reasonable F-T activity, the F-T catalysts also possess high water gas shift (WGS) activity. However, a seriousmore » problem with the use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, making the separation of catalyst from the oil/wax product very difficult if not impossible, and results in a steady loss of catalyst from the reactor. The objectives of this research are to develop a better understanding of the parameters affecting attrition resistance of Fe F-T catalysts suitable for use in SBCRs and to incorporate this understanding into the design of novel Fe catalysts having superior attrition resistance. Catalyst preparations will be based on the use of spray drying and will be scalable using commercially available equipment. The research will employ among other measurements, attrition testing and F-T synthesis, including long duration slurry reactor runs in order to ascertain the degree of success of the various preparations. The goal is to develop an Fe catalyst which can be used in a SBCR having only an internal filter for separation of the catalyst from the liquid product, without sacrificing F-T activity and selectivity.« less

Fermilab Center for Particle Astrophysics | FCPA

Science.gov Websites

Us About Us Contact Science Dark Matter Dark Energy Cosmic Microwave Background Radiation (CMBR) New detection and detailed study of the properties of cosmic dark matter particles in the laboratory » Hunting for Light Dark Matter in a Bubble Chamber September 18, 2013 | Hugh Lippincott The

The Investigation of the Effects of Gravity on Single Bubble Sonoluminescence

NASA Technical Reports Server (NTRS)

Dzikowicz, Ben; Thiessen, David B.; Marston, Philip

2000-01-01

In single bubble following it's rapid collapse each cycle of oscillation of an ultrasonic field. Since widely varying length and time scales affect the bubble dynamics and optical emission processes, it is difficult to anticipate the importance of the effects of gravity present for observations on earth. Our bubble is driven in an acoustically resonating cavity at it's first harmonic mode. The acoustical radiation pressure (Bjerknes force) will then keep it suspended in the center near the pressure antinode. When driven in a region where the diffusive processes balance the bubble it acts in a nonlinear but regular way, emitting a short (approx. 200ps) burst of light each acoustic cycle. Balancing the Bjerknes force with buoyancy, as in, we can see that the bubble should be displaced from the velocity node approximately 20m at normal gravity. Therefore, water flows past the bubble at the time of collapse. Gravitation also changes the ambient pressure at the bubble's location, as Delta.P = rho.g.h this gives a change of approximately -0.5% in our experiment when going from 1.8g to 0g. Studies of ambient pressure changes were also done in order to assess these effects. Inside a pressure sealed chamber a spherical glass cell is filled with distilled water which has been degassed to 120mmHg. A bubble is then trapped in the center and driven by a piezoelectric transducer at 32.2kHz attached to the side of the cell. An optical system is then set up to take strobbed video images along and light emission data simultaneously. Temperature, pressure, drive voltage, and listener voltage are also monitored. PMT output in Volts The radii of the bubbles for both experiment s are fit using the Rayleigh-Plesset equation and the acoustic drive amplitude and the ambient bubble radius are found. There is little change in the acoustic drive amplitude as we expect, since we are not varying the drive voltage. However. the ambient bubble radius goes up considerably. These changes (increased light output, increased maximum bubble radius, and increased ambient bubble radius) are also observed when the ambient pressure is varied in the laboratory by an amount similar to that due to gravitation. The changes in the ambient bubble radius and light output with a change in ambient pressure are predicted by the "dissociation hypothesis" and have been observed by other groups in the laboratory. It seems clear that buoyancy's effect on light output and bubble radius, are at best on the same order as the effects of ambient pressure.

Focal Point Inside the Vacuum Chamber for Solar Thermal Propulsion

NASA Technical Reports Server (NTRS)

1999-01-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. The 20- by 24-ft heliostat mirror (not shown in this photograph) has dual-axis control that keeps a reflection of the sunlight on an 18-ft diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. This photograph is a close-up view of a 4-in focal point inside the vacuum chamber at the MSFC Solar Thermal Propulsion Test facility. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Decompression sickness rates for chamber personnel: case series from one facility.

PubMed

Brandt, Megan S; Morrison, Thomas O; Butler, William P

2009-06-01

During 2004, a case series of decompression sickness (DCS) meeting the definition of epidemic DCS was observed in the Shaw AFB Physiological Training Program. There were 10 cases of chamber-induced altitude DCS observed. Internal and external investigations focused on time, place, person, and environment. No temporal trend was observed. Chamber, masks, regulators, crew positions, and oxygen sources revealed no defects. Among the cases, mean age was 27 yr. Peak altitude in four cases was 35,000 ft and in the other six cases was 25,000 ft. Six had joint pain, one skin symptoms, and three neurological findings. Four were treated with 100% ground-level oxygen and six with hyperbaric oxygen. Four were students and six were inside observers (IO). Four were women and six men. In the IO, where four of the six were women, no gender effect was seen. Examining the IO monthly exposure load (exposures per month) against DCS suggested a dose-response relationship. This relationship held true when 4 yr of Shaw AFB IO data was studied. Indeed, Poisson regression analysis demonstrated a statistically significant 2.1-fold rise in DCS risk with each monthly exposure. Consequently, the number of exposures per month may need to be considered when devising IO schedules.

Nanobubbles Form at Active Hydrophobic Spots on the Luminal Aspect of Blood Vessels: Consequences for Decompression Illness in Diving and Possible Implications for Autoimmune Disease-An Overview.

PubMed

Arieli, Ran

2017-01-01

Decompression illness (DCI) occurs following a reduction in ambient pressure. Decompression bubbles can expand and develop only from pre-existing gas micronuclei. The different hypotheses hitherto proposed regarding the nucleation and stabilization of gas micronuclei have never been validated. It is known that nanobubbles form spontaneously when a smooth hydrophobic surface is submerged in water containing dissolved gas. These nanobubbles may be the long sought-after gas micronuclei underlying decompression bubbles and DCI. We exposed hydrophobic and hydrophilic silicon wafers under water to hyperbaric pressure. After decompression, bubbles appeared on the hydrophobic but not the hydrophilic wafers. In a further series of experiments, we placed large ovine blood vessels in a cooled high pressure chamber at 1,000 kPa for about 20 h. Bubbles evolved at definite spots in all the types of blood vessels. These bubble-producing spots stained positive for lipids, and were henceforth termed "active hydrophobic spots" (AHS). The lung surfactant dipalmitoylphosphatidylcholine (DPPC), was found both in the plasma of the sheep and at the AHS. Bubbles detached from the blood vessel in pulsatile flow after reaching a mean diameter of ~1.0 mm. Bubble expansion was bi-phasic-a slow initiation phase which peaked 45 min after decompression, followed by fast diffusion-controlled growth. Many features of decompression from diving correlate with this finding of AHS on the blood vessels. (1) Variability between bubblers and non-bubblers. (2) An age-related effect and adaptation. (3) The increased risk of DCI on a second dive. (4) Symptoms of neurologic decompression sickness. (5) Preconditioning before a dive. (6) A bi-phasic mechanism of bubble expansion. (7) Increased bubble formation with depth. (8) Endothelial injury. (9) The presence of endothelial microparticles. Finally, constant contact between nanobubbles and plasma may result in distortion of proteins and their transformation into autoantigens.

Nanobubbles Form at Active Hydrophobic Spots on the Luminal Aspect of Blood Vessels: Consequences for Decompression Illness in Diving and Possible Implications for Autoimmune Disease—An Overview

PubMed Central

Arieli, Ran

2017-01-01

Decompression illness (DCI) occurs following a reduction in ambient pressure. Decompression bubbles can expand and develop only from pre-existing gas micronuclei. The different hypotheses hitherto proposed regarding the nucleation and stabilization of gas micronuclei have never been validated. It is known that nanobubbles form spontaneously when a smooth hydrophobic surface is submerged in water containing dissolved gas. These nanobubbles may be the long sought-after gas micronuclei underlying decompression bubbles and DCI. We exposed hydrophobic and hydrophilic silicon wafers under water to hyperbaric pressure. After decompression, bubbles appeared on the hydrophobic but not the hydrophilic wafers. In a further series of experiments, we placed large ovine blood vessels in a cooled high pressure chamber at 1,000 kPa for about 20 h. Bubbles evolved at definite spots in all the types of blood vessels. These bubble-producing spots stained positive for lipids, and were henceforth termed “active hydrophobic spots” (AHS). The lung surfactant dipalmitoylphosphatidylcholine (DPPC), was found both in the plasma of the sheep and at the AHS. Bubbles detached from the blood vessel in pulsatile flow after reaching a mean diameter of ~1.0 mm. Bubble expansion was bi-phasic—a slow initiation phase which peaked 45 min after decompression, followed by fast diffusion-controlled growth. Many features of decompression from diving correlate with this finding of AHS on the blood vessels. (1) Variability between bubblers and non-bubblers. (2) An age-related effect and adaptation. (3) The increased risk of DCI on a second dive. (4) Symptoms of neurologic decompression sickness. (5) Preconditioning before a dive. (6) A bi-phasic mechanism of bubble expansion. (7) Increased bubble formation with depth. (8) Endothelial injury. (9) The presence of endothelial microparticles. Finally, constant contact between nanobubbles and plasma may result in distortion of proteins and their transformation into autoantigens. PMID:28861003

Study of Thermodynamic Vent and Screen Baffle Integration for Orbital Storage and Transfer of Liquid Hydrogen

NASA Technical Reports Server (NTRS)

Cady, E. C.

1973-01-01

A comprehensive analytical and experimental program was performed to determine the feasibility of integrating an internal thermodynamic vent system and a full wall-screen liner for the orbital storage and transfer of liquid hydrogen (LH2). Ten screens were selected from a comprehensive screen survey. The experimental study determined the screen bubble point, flow-through pressure loss, and pressure loss along rectangular channels lined with screen on one side, for the 10 screens using LH2 saturated at 34.5 N/cm2 (50 psia). The correlated experimental data were used in an analysis to determine the optimum system characteristics in terms of minimum weight for 6 tanks ranging from 141.6 m3 (5,000 ft3) to 1.416 m3 (50 ft3) for orbital storage times of 30 and 300 days.

Evaluations of HRI (Heat Recovery Incinerators) at NS (Naval Station) Mayport and NAS (Naval Air Station) Jacksonville, Florida-Lessons Learned Report.

DTIC Science & Technology

1984-07-01

primary chamber is lined with 2 in. of insulating mineral wool and 4 in. of castable refractory with a service temperature of 2500*F. 5.5.5.4...material. The refractory should be air cooled by circulating combustion air between it and the outer shell. A minimum of 2-in.-high density mineral wool or...passes through the roof. The 50-ft-high and 6-ft-4-in.-O.D. stack is constructed of steel and lined with 4 in. of refractory and 2 in. of mineral

NASA Glenn Propulsion Systems Lab (PSL) Icing Facility Update

NASA Technical Reports Server (NTRS)

Thomas, Queito P.

2015-01-01

The NASA Glenn Research Center Propulsion Systems Lab (PSL) was recently upgraded to perform engine inlet ice crystal testing in an altitude environment. The system installed 10 spray bars in the inlet plenum for ice crystal generation using 222 spray nozzles. As an altitude test chamber, PSL is capable of simulation of in-flight icing events in a ground test facility. The system was designed to operate at altitudes from 4,000 ft. to 40,000 ft. at Mach numbers up to 0.8M and inlet total temperatures from -60F to +15F.

Volatile dynamics in crystal-rich magma bodies, perspectives from laboratory experiments and theory

NASA Astrophysics Data System (ADS)

Faroughi, S.; Parmigiani, A.; Huber, C.

2013-12-01

The amount of volatiles and the dynamics of bubbles play a significant role on the transition between different volcanic eruption behaviors. The transport of exsolved volatiles through zoned magma chambers is complex and remains poorly constrained. Here we focus on the different transport of volatiles under two end member regimes: crystal-poor systems (bubbles form a suspension) versus crystal-rich reservoirs (multiphase porous media flow). We present a combination of multiphase flow laboratory experiments (using silicon oil and water) and a theoretical argument based on Stokes flow streamfunctions to contrast the differences between the transport of exsolved volatiles in both regimes. The first set of experiments involves the buoyant migration of water droplets in silicon oil in the absence of glass beads. We measure the non-linear hydrodynamic interaction between bubbles and its effect on slowing down the average flux of water droplets as the water volume fraction increases. Our experimental results are compared to a theoretical argument in which a streamfunction formulation is used to estimate the effect of a suspension on bubble migration. We find a good agreement between the new theory and our experimental results. The second set of experiments focuses on the transport of water (non-wetting fluid) in porous media saturated with viscous silicon oils. Contrary to suspension dynamics, in multiphase porous media, an increase in the saturation of non-wetting fluid leads to a non-linear increase in its volumetric flux. The steady-state migration of non-wetting fluid is controlled by the formation of viscous fingering instability that greatly enhances transport. We propose that the regime of energy dissipation during the migration of bubbles in heterogeneous magma reservoirs can change, leading to bubble accumulation in crystal-poor regions as fingering becomes unstable and volatiles form a disperse bubble suspension.

Acousto-fluidic system assisting in-liquid self-assembly of microcomponents

NASA Astrophysics Data System (ADS)

Goldowsky, J.; Mastrangeli, M.; Jacot-Descombes, L.; Gullo, M. R.; Mermoud, G.; Brugger, J.; Martinoli, A.; Nelson, B. J.; Knapp, Helmut F.

2013-12-01

In this paper, we present the theoretical background, design, fabrication and characterization of a micromachined chamber assisting the fluidic self-assembly of micro-electro-mechanical systems in a bulk liquid. Exploiting bubble-induced acoustic microstreaming, several structurally-robust driving modes are excited inside the chamber. The modes promote the controlled aggregation and disaggregation of microcomponents relying on strong and reproducible fluid mixing effects achieved even at low Reynolds numbers. The functionality of the microfluidic chamber is demonstrated through the fast and repeatable geometrical pairing and subsequent unpairing of polymeric microcylinders. Relying only on drag and radiation forces and on the natural hydrophobicity of SU-8 in aqueous solutions, assembly yields of approximately 50% are achieved in no longer than ten seconds of agitation. The system can stochastically control the assembly process and significantly reduce the time-to-assembly of building blocks.

REACTION $pi$$sup -$ + p $Yields$ $pi$$sup -$ + $pi$$sup +$ + n FROM 360 TO 800 Mev

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirz, J.; Schwartz, J.; Tripp, R.D.

1963-10-31

The reaction ceramic materia /sup -/ + p ons in pyrolyti ceramic materia /sup -/ + ceramic materia /sup +/ + n is sLLawrence Radiation Laboratory's 72-in. hydrogen bubble chamber. Events are located by scanning the pictures for ceramic materia /sup +/ tracks. Cross sections, Dalitz plots, and ceramic materia /sup +/ ceramic materia /sup -/ d please delete abstract 26339

The Proton Synchrotron (PS): At the Core of the CERN Accelerators

NASA Astrophysics Data System (ADS)

Cundy, Donald; Gilardoni, Simone

The following sections are included: * Introduction * Extraction: Getting the Beam to Leave the Accelerator * Acceleration and Bunch Gymnastics * Boosting PS Beam Intensity * Capacitive Energy Storage Replaces Flywheel * Taking the Neutrinos by the Horns * OMEGA: Towards the Electronic Bubble Chamber * ISOLDE: Targeting a New Era in Nuclear Physics * The CERN n_TOF Facility: Catching Neutrons on the Fly * References

Preferential aerosolization of bacteria in bioaerosols generated in vitro.

PubMed

Perrott, P; Turgeon, N; Gauthier-Levesque, L; Duchaine, C

2017-09-01

Little is known about how bacteria are aerosolized in terms of whether some bacteria will be found in the air more readily than others that are present in the source. This report describes in vitro experiments to compare aerosolization rates (also known as preferential aerosolization) of Gram-positive and Gram-negative bacteria as well as rod- and coccus-shaped bacteria, using two nebulization conditions. A consortium of five bacterial species was aerosolized in a homemade chamber. Aerosols generated with a commercial nebulizer and a homemade bubble-burst aerosol generator were compared. Data suggest that Pseudomonas aeruginosa was preferentially aerosolized in comparison to Moraxella catarrhalis, Lactobacillus paracasei, Staphylococcus aureus and Streptococcus suis, independently of the method of aerosolization. Bacterial integrity of Strep. suis was more preserved compared to other bacteria studied as revealed with PMA-qPCR. We reported the design of an aerosol chamber and bubble-burst generator for the in vitro study of preferential aerosolization. In our setting, preferential aerosolization was influenced by bacterial properties instead of aerosolization mechanism. These findings could have important implications for predicting the composition of bioaerosols in various locations such as wastewater treatment plants, agricultural settings and health care settings. © 2017 The Society for Applied Microbiology.

Observations and modeling of magnetized plasma jets and bubbles launched into a transverse B-field

NASA Astrophysics Data System (ADS)

Fisher, Dustin M.; Zhang, Yue; Wallace, Ben; Gilmore, Mark; Manchester, Ward B., IV; van der Holst, Bart; Rogers, Barrett N.; Hsu, Scott C.

2017-10-01

Hot, dense, plasma structures launched from a coaxial plasma gun on the HelCat dual-source plasma device at the University of New Mexico drag frozen-in magnetic flux into the chamber's background magnetic field providing a rich set of dynamics to study magnetic turbulence, force-free magnetic spheromaks, shocks, as well as CME-like dynamics possibly relevant to the solar corona. Vector magnetic field data from an eleven-tipped B-dot rake probe and images from an ultra-fast camera will be presented in comparison with ongoing MHD modeling using the 3-D MHD BATS-R-US code developed at the University of Michigan. BATS-R-US employs an adaptive mesh refinement grid (AMR) that enables the capture and resolution of shock structures and current sheets and is uniquely suited for flux-rope expansion modeling. Recent experiments show a possible magnetic Rayleigh-Taylor (MRT) instability that appears asymmetrically at the interface between launched spheromaks (bubbles) and their entraining background magnetic field. Efforts to understand this instability using in situ measurements, new chamber boundary conditions, and ultra-fast camera data will be presented. Work supported by the Army Research Office Award No. W911NF1510480.

Moderation of near-field pressure over a supersonic flight model using laser-pulse energy deposition

NASA Astrophysics Data System (ADS)

Furukawa, D.; Aoki, Y.; Iwakawa, A.; Sasoh, A.

2016-05-01

The impact of a thermal bubble produced by energy deposition on the near-field pressure over a Mach 1.7 free-flight model was experimentally investigated using an aeroballistic range. A laser pulse from a transversely excited atmospheric (TEA) CO2 laser was sent into a test chamber with 68 kPa ambient pressure, focused 10 mm below the flight path of a conically nosed cylinder with a diameter of 10 mm. The pressure history, which was measured 150 mm below the flight path along the acoustic ray past the bubble, exhibited precursory pressure rise and round-off peak pressure, thereby demonstrating the proof-of-concept of sonic boom alleviation using energy deposition.

Preliminary measurements of neutrons from the D-D reaction in the COMPASS tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dankowski, J., E-mail: jan.dankowski@ifj.edu.pl; Kurowski, A.; Twarog, D.

Recent results of measured fast neutrons created in the D-D reaction on the COMPASS tokamak during ohmic discharges are presented in this paper. Two different type detectors were used during experiment. He-3 detectors and bubble detectors as a support. The measurements are an introduction for neutron diagnostic on tokamak COMPASS and monitoring neutrons during discharges with Neutral Beam Injection (NBI). The He-3 counters and bubble detectors were located in two positions near tokamak vacuum chamber at a distance less than 40 cm to the centre of plasma. The neutrons flux was observed in ohmic discharges. However, analysis of our resultsmore » does not indicate any clear source of neutrons production during ohmic discharges.« less

BDPU, Favier places new test chamber into experiment module in LMS-1 Spacelab

NASA Image and Video Library

1996-07-09

STS078-301-021 (20 June - 7 July 1996) --- Payload specialist Jean-Jacques Favier, representing the French Space Agency (CNES), holds up a test container to a Spacelab camera. The test involves the Bubble Drop Particle Unit (BDPU), which Favier is showing to ground controllers at the Marshall Space Flight Center (MSFC) in order to check the condition of the unit prior to heating in the BDPU facility. The test container holds experimental fluid and allows experiment observation through optical windows. BDPU contains three internal cameras that are used to continuously downlink BDPU activity so that behavior of the bubbles can be monitored. Astronaut Richard M. Linnehan, mission specialist, conducts biomedical testing in the background.

Plum (Prunus domestica) Trees Transformed with Poplar FT1 Result in Altered Architecture, Dormancy Requirement, and Continuous Flowering

PubMed Central

Callahan, Ann; Scorza, Ralph

2012-01-01

The Flowering Locus T1 (FT1) gene from Populus trichocarpa under the control of the 35S promoter was transformed into European plum (Prunus domestica L). Transgenic plants expressing higher levels of FT flowered and produced fruits in the greenhouse within 1 to 10 months. FT plums did not enter dormancy after cold or short day treatments yet field planted FT plums remained winter hardy down to at least −10°C. The plants also displayed pleiotropic phenotypes atypical for plum including shrub-type growth habit and panicle flower architecture. The flowering and fruiting phenotype was found to be continuous in the greenhouse but limited to spring and fall in the field. The pattern of flowering in the field correlated with lower daily temperatures. This apparent temperature effect was subsequently confirmed in growth chamber studies. The pleitropic phenotypes associated with FT1 expression in plum suggests a fundamental role of this gene in plant growth and development. This study demonstrates the potential for a single transgene event to markedly affect the vegetative and reproductive growth and development of an economically important temperate woody perennial crop. We suggest that FT1 may be a useful tool to modify temperate plants to changing climates and/or to adapt these crops to new growing areas. PMID:22859952

Neutral strange particle production in neutrino and antineutrino charged-current interactions on neon

NASA Astrophysics Data System (ADS)

Deprospo, D.; Kalelkar, M.; Aderholz, M.; Akbari, H.; Allport, P. P.; Ammosov, V. V.; Andryakov, A.; Asratyan, A.; Badyal, S. K.; Ballagh, H. C.; Baton, J.-P.; Barth, M.; Bingham, H. H.; Brucker, E. B.; Burnstein, R. A.; Cence, R. J.; Chatterjee, T. K.; Clayton, E. F.; Corrigan, G.; Coutures, C.; Devanand; de Wolf, E.; Ermolov, P.; Erofeeva, I.; Faulkner, P. J.; Foeth, H.; Fretter, W. B.; Gapienko, G.; Gupta, V. K.; Hanlon, J.; Harigel, G.; Harris, F. A.; Ivanilov, A.; Jabiol, M.; Jacques, P.; Jain, V.; Jones, G. T.; Jones, M. D.; Kafka, T.; Kaftanov, V.; Kasper, P.; Kobrin, V.; Kohli, J. M.; Koller, E. L.; Korablev, V.; Kubantsev, M.; Lauko, M.; Lukina, O.; Lys, J. E.; Lyutov, S.; Marage, P.; Milburn, R. H.; Mittra, I. S.; Mobayyen, M. M.; Moreels, J.; Morrison, D. R.; Moskalev, V.; Murzin, V.; Myatt, G.; Nailor, P.; Naon, R.; Napier, A.; Neveu, M.; Passmore, D.; Peters, M. W.; Peterson, V. Z.; Plano, R.; Rao, N. K.; Rubin, H. A.; Ryasakov, S.; Sacton, J.; Sambyal, S. S.; Schmitz, N.; Schneps, J.; Singh, J. B.; Singh, S.; Sivoklokov, S.; Smart, W.; Smirnova, L.; Stamer, P.; Varvell, K. E.; Verluyten, L.; Wachsmuth, H.; Wainstein, S.; Willocq, S.; Yost, G. P.

1994-12-01

A study has been made of neutral strange particle production in νμNe and ν¯μNe charged-current interactions at a higher energy than any previous study. The experiment was done at the Fermilab Tevatron using the 15-ft. bubble chamber, and the data sample consists of 814(154) observed neutral strange particles from 6263(1115) ν(ν¯) charged-current events. For the ν beam (average event energy =150 GeV), the average multiplicities per charged-current event have been measured to be 0.408+/-0.048 for K0, 0.127+/-0.014 for Λ, and 0.015+/-0.005 for Λ¯, which are significantly greater than for lower-energy experiments. The dependence of rates on kinematical variables has been measured, and shows that both K0 and Λ production increase strongly with Eν, W2, Q2, and yB. Compared to lower-energy experiments, single-particle distributions indicate that there is much more K0 production for xF>-0.2, and the enhanced Λ production spans most of the kinematic region. Λ¯ production is mostly in the region ||xF||<0.3. The Lund model is shown to be in qualitative agreement with the data, but does not reproduce single-particle distributions in detail. For xF>-0.2 there is a significant excess of Λ production over the model's prediction. The Λ hyperons are found to be polarized in the production plane.

Oxygen transfer in a full-depth biological aerated filter.

PubMed

Stenstrom, Michael K; Rosso, Diego; Melcer, Henryk; Appleton, Ron; Occiano, Victor; Langworthy, Alan; Wong, Pete

2008-07-01

The City of San Diego, California, evaluated the performance capabilities of biological aerated filters (BAFs) at the Point Loma Wastewater Treatment Plant. The City conducted a 1-year pilot-plant evaluation of BAF technology supplied by two BAF manufacturers. This paper reports on the first independent oxygen-transfer test of BAFs at full depth using the offgas method. The tests showed process-water oxygen-transfer efficiencies of 1.6 to 5.8%/m (0.5 to 1.8%/ft) and 3.9 to 7.9%/m (1.2 to 2.4%/ft) for the two different pilot plants, at their nominal design conditions. Mass balances using chemical oxygen demand and dissolved organic carbon corroborated the transfer rates. Rates are higher than expected from fine-pore diffusers for similar process conditions and depths and clean-water conditions for the same column and are mostly attributed to extended bubble retention time resulting from interactions with the media and biofilm.

Plasma ion implantation technology at Hughes Research Laboratories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matossian, J.N.

1994-03-01

The plasma ion implantation (PII) project at Hughes Research Laboratories (HRL) has as its main objective the evaluation and application of PII technology to improve the tribological properties of metal and nonmetal materials used in aerospace, defense, and commercial applications. The HRL PII facility consists of a 4-ft-diam[times]8-ft-long vacuum chamber capable of implanting objects weighing up to 7000 lbs, and a high-power (100-kW), high-voltage (100-kV) pulse modulator to provide voltage pulses for implantation. Advanced plasma sources have been developed to produce atomic, as well as molecular, nitrogen and oxygen ions, and PII processes have been developed to treat metal andmore » nonmetal materials. The HRL PII facility has been operational since 1989 and has been used for prototype demonstrations of PII technology to achieve (1) a 2--3[times] improved wear life of Co/WC drill bits used for printed-wiring-board fabrication, (2) an 8[times] reduced wear rate for TiN-coated cutting tools, and (3) a 2[times] increased surface hardness for a 7000-lb polymer object, 3 ft by 5 ft by 1 ft.« less

Press Release | News | Page 3

Science.gov Websites

, technology, engineering and math fields. New world-leading limit on dark matter search from PICO experiment February 27, 2017 The PICO-60 dark matter bubble chamber experiment has produced a new dark matter limit . Construction of world's most sensitive dark matter detector moves forward September 26, 2016 LUX-ZEPLIN (LZ), a

Fabrication of microelectromechanical systems (MEMS) cantilevers for photoacoustic (PA) detection of terahertz (THz) radiation

NASA Astrophysics Data System (ADS)

Newberry, R.; Glauvitz, N.; Coutu, R. A.; Medvedev, I. R.; Petkie, D.

2014-03-01

Historically, spectroscopy has been a cumbersome endeavor due to the relatively large sizes (3ft - 100ft in length) of modern spectroscopy systems. Taking advantage of the photoacoustic effect would allow for much smaller absorption chambers since the photoacoustic (PA) effect is independent of the absorption path length. In order to detect the photoacoustic waves being generated, a photoacoustic microphone would be required. This paper reports on the fabrication efforts taken in order to create microelectromechanical systems (MEMS) cantilevers for the purpose of sensing photoacoustic waves generated via terahertz (THz) radiation passing through a gaseous sample. The cantilevers are first modeled through the use of the finite element modeling software, CoventorWare®. The cantilevers fabricated with bulk micromachining processes and are 7x2x0.010mm on a silicon-on-insulator (SOI) wafer which acts as the physical structure of the cantilever. The devices are released by etching through the wafer's backside and etching through the buried oxide with hydrofluoric acid. The cantilevers are placed in a test chamber and their vibration and deflection are measured via a Michelson type interferometer that reflects a laser off a gold tip evaporated onto the tip of the cantilever. The test chamber is machined from stainless steel and housed in a THz testing environment at Wright State University. Fabricated devices have decreased residual stress and larger radii of curvatures by approximately 10X.

Chamber for the optical manipulation of microscopic particles

DOEpatents

Buican, Tudor N.; Upham, Bryan D.

1992-01-01

A particle control chamber enables experiments to be carried out on biological cells and the like using a laser system to trap and manipulate the particles. A manipulation chamber provides a plurality of inlet and outlet ports for the particles and for fluids used to control or to contact the particles. A central manipulation area is optically accessible by the laser and includes first enlarged volumes for containing a selected number of particles for experimentation. A number of first enlarged volumes are connected by flow channels through second enlarged volumes. The second enlarged volumes act as bubble valves for controlling the interconnections between the first enlarged volumes. Electrode surfaces may be applied above the first enlarged volumes to enable experimentation using the application of electric fields within the first enlarged volumes. A variety of chemical and environmental conditions may be established within individual first enlarged volumes to enable experimental conditions for small scale cellular interactions.

The effect of exercise and rest duration on the generation of venous gas bubbles at altitude

NASA Technical Reports Server (NTRS)

Dervay, Joseph P.; Powell, Michael R.; Butler, Bruce; Fife, Caroline E.

2002-01-01

BACKGROUND: Decompression, as occurs with aviators and astronauts undergoing high altitude operations or with deep-sea divers returning to surface, can cause gas bubbles to form within the organism. Pressure changes to evoke bubble formation in vivo during depressurization are several orders of magnitude less than those required for gas phase formation in vitro in quiescent liquids. Preformed micronuclei acting as "seeds" have been proposed, dating back to the 1940's. These tissue gas micronuclei have been attributed to a minute gas phase located in hydrophobic cavities, surfactant-stabilized microbubbles, or arising from musculoskeletal activity. The lifetimes of these micronuclei have been presumed to be from a few minutes to several weeks. HYPOTHESIS: The greatest incidence of venous gas emboli (VGE) will be detected by precordial Doppler ultrasound with depressurization immediately following lower extremity exercise, with progressively reduced levels of VGE observed as the interval from exercise to depressurization lengthens. METHODS: In a blinded cross-over design, 20 individuals (15 men, 5 women) at sea level exercised by performing knee-bend squats (150 knee flexes over 10 min, 235-kcal x h(-1)) either at the beginning, middle, or end of a 2-h chair-rest period without an oxygen prebreathe. Seated subjects were then depressurized to 6.2 psia (6,706 m or 22,000 ft altitude equivalent) for 120 min with no exercise performed at altitude. RESULTS: Of the 20 subjects with VGE in the pulmonary artery, 10 demonstrated a greater incidence of bubbles with exercise performed just prior to depressurization, compared with decreasing bubble grades and incidence as the interval of rest increased prior to depressurization. No decompression illness was reported. CONCLUSIONS: There is a significant increase in decompression-induced bubble formation at 6.2 psia when lower extremity exercise is performed just prior to depressurization as compared with longer rest intervals. Analysis indicated that micronuclei half-life is on the order of an hour under these hypobaric conditions.

Body and organ weights of rats exposed to carbon monoxide at high altitude

DOE Office of Scientific and Technical Information (OSTI.GOV)

McGrath, J.J.

1988-01-01

Male, laboratory rats were exposed for 6 wk in steel barometric chambers to (1) 100 ppm CO, (2) 15,000 ft simulated high altitude (SHA), and (3) CO at SHA. Altitude was simulated by a system of gate valves and a vacuum pump, and measured by an altimeter. CO, from high-pressure cylinders, was introduced into the air supplying each chamber through a mass flow controller and measured by a nondispersive infrared (NDIR) analyzer. Although SHA had no affect on left ventricle plus septum (LV + S), adrenal, spleen, or kidney weights, SHA decreased body weights, and increased hematocrit ratios, as wellmore » as right ventricle (RV), total heart (HT), and pituitary weights. CO had no affect on body weights, RV, HT, adrenal, spleen, or kidney weights, but CO increased hematocrit ratios and LV + S weights. There was no significant interaction between SHA and CO on any parameter except kidney weight. These results indicate that, in general, the effects produced by 15,000 ft SHA are not intensified by exposure to 100 ppm CO.« less

CFM technologies for space transportation: Multipurpose hydrogen testbed system definition and tank procurement

NASA Technical Reports Server (NTRS)

Fox, E. C.; Kiefel, E. R.; Mcintosh, G. L.; Sharpe, J. B.; Sheahan, D. R.; Wakefield, M. E.

1993-01-01

The development of a test bed tank and system for evaluating cryogenic fluid management technologies in a simulated upper stage liquid hydrogen tank is covered. The tank is 10 ft long and is 10 ft in diameter, and is an ASME certified tank constructed of 5083 aluminum. The tank is insulated with a combination of sprayed on foam insulation, covered by 45 layers of double aluminized mylar separated by dacron net. The mylar is applied by a continuous wrap system adapted from commercial applications, and incorporates variable spacing between the mylar to provide more space between those layers having a high delta temperature, which minimizes heat leak. It also incorporates a unique venting system which uses fewer large holes in the mylar rather than the multitude of small holes used conventionally. This significantly reduces radiation heat transfer. The test bed consists of an existing vacuum chamber at MSFC, the test bed tank and its thermal control system, and a thermal shroud (which may be heated) surrounding the tank. Provisions are made in the tank and chamber for inclusion of a variety of cryogenic fluid management experiments.

Experimental study of the flow pattern around a bubble confined in a microfluidic Hele-Shaw cell

NASA Astrophysics Data System (ADS)

Tsoumpas, Yannis; Fajolles, Christophe; Malloggi, Florent

2017-11-01

The flow field around a bubble moving with respect to a surrounding liquid in a Hele-Shaw cell can usually be characterized by a recirculating flow, which is typically attributed to a Marangoni effect due to surface tension gradients generated by a non-uniform distribution of surfactants (or temperature) along the liquid-gas interface. In the present study, we try to visualize such a flow employing 3D micro-particle tracking velocimetry. We perform experiments on an immobile flattened air bubble that is surrounded by a flow of aqueous solution of surfactant (SDS), in a microfluidic chamber described in the work of Sungyon Lee et al.. The suspending fluid is seeded with spherical micro-particles, with those captured by the recirculating flow orbiting in a three-dimensional trajectory in the vicinity of the liquid-air interface. We address the effect of velocity of the surrounding fluid, surfactant concentration and bubble radius on the recirculating flow pattern. The case of a liquid-liquid interface, with a hexadecane drop as the dispersed phase, is also discussed. The authors would like to acknowledge the financial support of Enhanced Eurotalents program (an FP7 Marie Skłodowska-Curie COFUND program) & ANR (ANR-13-BS09-0011).

Generating Singlet Oxygen Bubbles: A New Mechanism for Gas-Liquid Oxidations in Water

PubMed Central

Bartusik, Dorota; Aebisher, David; Ghafari, BiBi

2012-01-01

Laser-coupled microphotoreactors were developed to bubble singlet oxygen [1O2 (1Δg)] into an aqueous solution containing an oxidizable compound. The reactors consisted of custom-modified SMA fiber-optic receptacles loaded with 150-μm silicon phthalocyanine glass sensitizer particles, where the particles were isolated from direct contact with water by a membrane adhesively bonded to the bottom of each device. A tube fed O2 gas to the reactor chambers. In the presence of O2, singlet oxygen was generated by illuminating the sensitizer particles with 669-nm light from an optical fiber coupled to the top of the reactor. The generated 1O2 was transported through the membrane by the O2 stream and formed bubbles in solution. In solution, singlet oxygen reacted with probe compounds (either 9,10-anthracene dipropionate dianion, trans-2-methyl-2-pentanoate anion, N-benzoyl-D,L-methionine, and N-acetyl-D,L-methionine) to give oxidized products in two stages. The early stage was rapid and showed that 1O2 transfer occurred via bubbles mainly in the bulk water solution. The later stage was slow, it arose only from 1O2-probe molecule contact at the gas/liquid interface. A mechanism is proposed that involves 1O2 mass transfer and solvation, where smaller bubbles provide better penetration of 1O2 into the flowing stream due to higher surface-to-volume contact between the probe molecules and 1O2. PMID:22260325

Flowmeter for determining average rate of flow of liquid in a conduit

DOEpatents

Kennerly, J.M.; Lindner, G.M.; Rowe, J.C.

1981-04-30

This invention is a compact, precise, and relatively simple device for use in determining the average rate of flow of a liquid through a conduit. The liquid may be turbulent and contain bubbles of gas. In a preferred embodiment, the flowmeter includes an electrical circuit and a flow vessel which is connected as a segment of the conduit conveying the liquid. The vessel is provided with a valved outlet and is partitioned by a vertical baffle into coaxial chambers whose upper regions are vented to permit the escape of gas. The inner chamber receives turbulent downflowing liquid from the conduit and is sized to operate at a lower pressure than the conduit, thus promoting evolution of gas from the liquid. Lower zones of the two chambers are interconnected so that the downflowing liquid establishes liquid levels in both chambers. The liquid level in the outer chamber is comparatively calm, being to a large extent isolated from the turbulence in the inner chamber once the liquid in the outer chamber has risen above the liquid-introduction zone for that chamber. Lower and upper probes are provided in the outer chamber for sensing the liquid level therein at points above its liquid-introduction zone. An electrical circuit is connected to the probes to display the time required for the liquid level in the outer chamber to successively contact the lower and upper probes. The average rate of flow through the conduit can be determined from the above-mentioned time and the vessel volume filled by the liquid during that time.

Flowmeter for determining average rate of flow of liquid in a conduit

DOEpatents

Kennerly, John M.; Lindner, Gordon M.; Rowe, John C.

1982-01-01

This invention is a compact, precise, and relatively simple device for use in determining the average rate of flow of a liquid through a conduit. The liquid may be turbulent and contain bubbles of gas. In a preferred embodiment, the flowmeter includes an electrical circuit and a flow vessel which is connected as a segment of the conduit conveying the liquid. The vessel is provided with a valved outlet and is partitioned by a vertical baffle into coaxial chambers whose upper regions are vented to permit the escape of gas. The inner chamber receives turbulent downflowing liquid from the conduit and is sized to operate at a lower pressure than the conduit, thus promoting evolution of gas from the liquid. Lower zones of the two chambers are interconnected so that the downflowing liquid establishes liquid levels in both chambers. The liquid level in the outer chamber is comparatively calm, being to a large extent isolated from the turbulence in the inner chamber once the liquid in the outer chamber has risen above the liquid-introduction zone for that chamber. Lower and upper probes are provided in the outer chamber for sensing the liquid level therein at points above its liquid-introduction zone. An electrical circuit is connected to the probes to display the time required for the liquid level in the outer chamber to successively contact the lower and upper probes. The average rate of flow through the conduit can be determined from the above-mentioned time and the vessel volume filled by the liquid during that time.

Aerobic exercise before diving reduces venous gas bubble formation in humans

PubMed Central

Dujić, Željko; Duplančic, Darko; Marinovic-Terzić, Ivana; Baković, Darija; Ivančev, Vladimir; Valic, Zoran; Eterović, Davor; Petri, Nadan M; Wisløff, Ulrik; Brubakk, Alf O

2004-01-01

We have previously shown in a rat model that a single bout of high-intensity aerobic exercise 20h before a simulated dive reduces bubble formation and after the dive protects from lethal decompression sickness. The present study investigated the importance of these findings in man. Twelve healthy male divers were compressed in a hyperbaric chamber to 280kPa at a rate of 100kPamin−1 breathing air and remaining at pressure for 80min. The ascent rate was 9mmin−1 with a 7min stop at 130kPa. Each diver underwent two randomly assigned simulated dives, with or without preceding exercise. A single interval exercise performed 24h before the dive consisted of treadmill running at 90% of maximum heart rate for 3min, followed by exercise at 50% of maximum heart rate for 2min; this was repeated eight times for a total exercise period of 40min. Venous gas bubbles were monitored with an ultrasonic scanner every 20min for 80min after reaching surface pressure. The study demonstrated that a single bout of strenuous exercise 24h before a dive to 18 m of seawater significantly reduced the average number of bubbles in the pulmonary artery from 0.98 to 0.22 bubbles cm−2(P= 0.006) compared to dives without preceding exercise. The maximum bubble grade was decreased from 3 to 1.5 (P= 0.002) by pre-dive exercise, thereby increasing safety. This is the first report to indicate that pre-dive exercise may form the basis for a new way of preventing serious decompression sickness. PMID:14755001

Thermal Vacuum Integrated System Test at B-2

NASA Technical Reports Server (NTRS)

Kudlac, Maureen T.; Weaver, Harold F.; Cmar, Mark D.

2012-01-01

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Plum Brook Station (PBS) Space Propulsion Research Facility, commonly referred to as B-2, is NASA s third largest thermal vacuum facility. It is the largest designed to store and transfer large quantities of liquid hydrogen and liquid oxygen, and is perfectly suited to support developmental testing of chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing thermal-vacuum simulation services to support testing of large lightweight structures, Cryogenic Fluid Management (CFM) systems, electric propulsion test programs, and other In-Space propulsion programs. A recently completed integrated system test demonstrated the refurbished thermal vacuum capabilities of the facility. The test used the modernized data acquisition and control system to monitor the facility during pump down of the vacuum chamber, operation of the liquid nitrogen heat sink (or cold wall) and the infrared lamp array. A vacuum level of 1.3x10(exp -4)Pa (1x10(exp -6)torr) was achieved. The heat sink provided a uniform temperature environment of approximately 77 K (140deg R) along the entire inner surface of the vacuum chamber. The recently rebuilt and modernized infrared lamp array produced a nominal heat flux of 1.4 kW/sq m at a chamber diameter of 6.7 m (22 ft) and along 11 m (36 ft) of the chamber s cylindrical vertical interior. With the lamp array and heat sink operating simultaneously, the thermal systems produced a heat flux pattern simulating radiation to space on one surface and solar exposure on the other surface. The data acquired matched pretest predictions and demonstrated system functionality.

p-barp interactions at 2. 32 GeV/c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C.K.; Fields, T.; Rhines, D.S.

1978-01-01

A bubble-chamber experiment based on 304 000 events of p-barp interactions at 2.32 GeV/c is described. The film was automatically scanned and measured by the POLLY II system. Details of the data-analysis methods are given. We report results on cross sections for constrained final states, tests of C invariance, and inclusive pion and rho/sup 0/ multiplicity parameters for annihilation final states.

40 CFR Appendix A to Part 136 - Methods for Organic Chemical Analysis of Municipal and Industrial Wastewater

Code of Federal Regulations, 2014 CFR

2014-07-01

... bubbled through a 5-mL water sample contained in a specially-designed purging chamber at ambient... now commercially available. 5.2.1The purging device must be designed to accept 5-mL samples with a... design criteria. 5.2.2The trap must be at least 25 cm long and have an inside diameter of at least 0.105...

40 CFR Appendix A to Part 136 - Methods for Organic Chemical Analysis of Municipal and Industrial Wastewater

Code of Federal Regulations, 2013 CFR

2013-07-01

... bubbled through a 5-mL water sample contained in a specially-designed purging chamber at ambient... now commercially available. 5.2.1The purging device must be designed to accept 5-mL samples with a... design criteria. 5.2.2The trap must be at least 25 cm long and have an inside diameter of at least 0.105...

40 CFR Appendix A to Part 136 - Methods for Organic Chemical Analysis of Municipal and Industrial Wastewater

Code of Federal Regulations, 2012 CFR

2012-07-01

... bubbled through a 5-mL water sample contained in a specially-designed purging chamber at ambient... now commercially available. 5.2.1The purging device must be designed to accept 5-mL samples with a... design criteria. 5.2.2The trap must be at least 25 cm long and have an inside diameter of at least 0.105...

Quasi-Steady Acceleration Direction Indicator in Three Dimensions

NASA Technical Reports Server (NTRS)

DeLombard, Richard; Nelson, Emily S.; Jules, Kenol

2000-01-01

Many materials processing and fluids physics experiments conducted in a microgravity environment require knowledge of the orientation of the low-frequency acceleration vector. This need becomes especially acute for space experiments such as directional solidification of a molten semiconductor, which is extremely sensitive to orientation and may involve tens of hours of operations of a materials furnace. These low-frequency acceleration data have been measured for many Shuttle missions with the Orbital Acceleration Research Experiment. Previous attempts at using fluid chambers for acceleration measurements have met with limited success due to pointing and vehicle attitude complications. An acceleration direction indicator is described, which is comprised of two orthogonal short cylinders of fluid, each with a small bubble. The motion and the position of the bubble within the chamber will indicate the direction of the acceleration experienced at the sensor location. The direction of the acceleration vector may then be calculated from these data. The frequency response of such an instrument may be tailored for particular experiments with the proper selection of fluid and gas parameters, surface type, and geometry. A three-dimensional system for sensing and displaying the low-frequency acceleration direction via an innovative technique described in this paper has advantages in terms of size, mass, and power compared with electronic instrumentation systems.

Musculoskeletal-induced Nucleation in Altitude Decompression Sickness

NASA Technical Reports Server (NTRS)

Pollock, N. W.; Natoli, M. J.; Conkin, J.; Wessel, J. H., III; Gernhardt, M. L.

2014-01-01

Musculoskeletal activity has the potential to both improve and compromise decompression safety. Exercise enhances inert gas elimination during oxygen breathing prior to decompression (prebreathe), but it may also promote bubble nuclei formation (nucleation), which can lead to gas phase separation and bubble growth and increase the risk of decompression sickness (DCS). The timing, pattern and intensity of musculoskeletal activity and the level of tissue supersaturation may be critical to the net effect. There are limited data available to evaluate cost-benefit relationships. Understanding the relationship is important to improve our understanding of the underlying mechanisms of nucleation in exercise prebreathe protocols and to quantify risk in gravity and microgravity environments. Data gathered during NASA's Prebreathe Reduction Program (PRP) studies combined oxygen prebreathe and exercise followed by low pressure (4.3 psi; altitude equivalent of 30,300 ft [9,235 m]) microgravity simulation to produce two protocols used by astronauts preparing for extravehicular activity. Both the Phase II/CEVIS (cycle ergometer vibration isolation system) and ISLE (in-suit light exercise) trials eliminated ambulation to more closely simulate the microgravity environment. The CEVIS results (35 male, 10 female) serve as control data for this NASA/Duke study to investigate the influence of ambulation exercise on bubble formation and the subsequent risk of DCS.

Performance of the Satellite Test Assistant Robot in JPL's Space Simulation Facility

NASA Technical Reports Server (NTRS)

Mcaffee, Douglas; Long, Mark; Johnson, Ken; Siebes, Georg

1995-01-01

An innovative new telerobotic inspection system called STAR (the Satellite Test Assistant Robot) has been developed to assist engineers as they test new spacecraft designs in simulated space environments. STAR operates inside the ultra-cold, high-vacuum, test chambers and provides engineers seated at a remote Operator Control Station (OCS) with high resolution video and infrared (IR) images of the flight articles under test. STAR was successfully proof tested in JPL's 25-ft (7.6-m) Space Simulation Chamber where temperatures ranged from +85 C to -190 C and vacuum levels reached 5.1 x 10(exp -6) torr. STAR's IR Camera was used to thermally map the entire interior of the chamber for the first time. STAR also made several unexpected and important discoveries about the thermal processes occurring within the chamber. Using a calibrated test fixture arrayed with ten sample spacecraft materials, the IR camera was shown to produce highly accurate surface temperature data. This paper outlines STAR's design and reports on significant results from the thermal vacuum chamber test.

Monitoring and analysis of combined sewer overflows, Riverside and Evanston, Illinois, 1997-99

USGS Publications Warehouse

Waite, Andrew M.; Hornewer, Nancy J.; Johnson, Gary P.

2002-01-01

The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, collected and analyzed flow data in combined sewer systems in Riverside and Evanston, northeastern Illinois, from March 1997 to December 1999. Continuous 2- and 5-minute stage and velocity data were collected during surcharged and nonsurcharged conditions at 12 locations. Mass balances were calculated to determine the volume of water flowing through the tide-gate openings to the Des Plaines River and the North Shore Channel and to determine the volume of water flowing past the sluice gate to the deep tunnel. The sewer systems consist of circular pipes ranging in diameter from 0.83 feet to 10.0 feet, elliptical siphon pipes, ledges, and tide and sluice gates. Pipes were constructed of either brick and mortar or concrete, and ranged from having smooth surfaces to rough, pitted and crumbling surfaces. One pipe was noticeably affected by water infiltration from saturated ground. During data analysis, many assumptions were necessary because of the complexity of the flow data and sewer-system configurations. These assumptions included estimating the volume of water entering an interceptor sewer at the ''Gage Street pipe'' at Riverside, the effect of infiltration on the ''brick pipe'' at Riverside, and the minimum velocity required for the meter to make an accurate velocity determination. Other factors affecting the analysis of flow data included possible non-instrumented sources of inflow, and backwater conditions in some pipes, which could have caused error in the data analysis. Variations of these assumptions potentially could cause appreciable changes to the final massbalance calculations. Mass-balance analysis at Riverside indicated a total inflow volume into chamber 3 of approximately 721,000 cubic feet (ft3) during April 22-26, 1999. Outflow volume to the Des Plaines River at Riverside through the tide gate was approximately 132,000 ft3; outflow volume to the deep tunnel through the sluice gate was approximately 267,000 ft3. The mass-balance analysis at Evanston indicated a total inflow volume into chamber 3 of approximately 5,970,000 ft3 during April 21-26, 1999. The outflow volume to the North Shore Channel through the tide gates at Evanston was approximately 2,920,000 ft3; outflow volume to the deep tunnel through the sluice gates was approximately 3,050,000 ft3.

Spiral vane bioreactor

NASA Technical Reports Server (NTRS)

Morrison, Dennis R. (Inventor)

1991-01-01

A spiral vane bioreactor of a perfusion type is described in which a vertical chamber, intended for use in a microgravity condition, has a central rotating filter assembly and has flexible membranes disposed to rotate annularly about the filter assembly. The flexible members have end portions disposed angularly with respect to one another. A fluid replenishment medium is input from a closed loop liquid system to a completely liquid filled chamber containing microcarrier beads, cells and a fluid medium. Output of spent medium is to the closed loop. In the closed loop, the output and input parameters are sensed by sensors. A manifold permits recharging of the nutrients and pH adjustment. Oxygen is supplied and carbon dioxide and bubbles are removed and the system is monitored and controlled by a microprocessor.

Counter-current convection in a volcanic conduit

NASA Astrophysics Data System (ADS)

Fowler, A. C.; Robinson, Marguerite

2018-05-01

Volcanoes of Strombolian type are able to maintain their semi-permanent eruptive states through the constant convective recycling of magma within the conduit leading from the magma chamber. In this paper we study the form of this convection using an analytic model of degassing two-phase flow in a vertical channel. We provide solutions for the flow at small Grashof and large Prandtl numbers, and we suggest that permanent steady-state counter-current convection is only possible if an initial bubbly counter-current flow undergoes a régime transition to a churn-turbulent flow. We also suggest that the magma in the chamber must be under-pressured in order for the flow to be maintained, and that this compromises the assumed form of the flow.

DARK-FIELD ILLUMINATION SYSTEM

DOEpatents

Norgren, D.U.

1962-07-24

A means was developed for viewing objects against a dark background from a viewing point close to the light which illuminates the objects and under conditions where the back scattering of light by the objects is minimal. A broad light retro-directing member on the opposite side of the objects from the light returns direct light back towards the source while directing other light away from the viewing point. The viewing point is offset from the light and thus receives only light which is forwardly scattered by an object while returning towards the source. The object is seen, at its true location, against a dark background. The invention is particularly adapted for illuminating and viewing nuclear particle tracks in a liquid hydrogen bubble chamber through a single chamber window. (AEC)

Morphological and chemical changes in dentin after using endodontic agents: Fourier transform Raman spectroscopy, energy-dispersive x-ray fluorescence spectrometry, and scanning electron microscopy study

NASA Astrophysics Data System (ADS)

Pascon, Fernanda Miori; Kantovitz, Kamila Rosamilia; Soares, Luís Eduardo Silva; Santo, Ana Maria do Espírito; Martin, Airton Abraha~o.; Puppin-Rontani, Regina Maria

2012-07-01

We examine the morphological and chemical changes in the pulp chamber dentin after using endodontic agents by scanning electron microscopy (SEM), Fourier transform Raman spectroscopy (FT-Raman), and micro energy-dispersive x-ray fluorescence spectrometry (μEDXRF). Thirty teeth were sectioned exposing the pulp chamber and divided by six groups (n=5): NT-no treatment; CHX-2% chlorhexidine; CHXE-2% chlorhexidine+17% EDTA E-17% EDTA; SH5-5.25% NaOCl; SH5E-5.25% NaOCl+17% EDTA. The inorganic and organic content was analyzed by FT-Raman. μEDXRF examined calcium (Ca) and phosphorus (P) content as well as Ca/P ratio. Impressions of specimens were evaluated by SEM. Data were submitted to Kruskal-Wallis and Dunn tests (p<0.05). Differences were observed among groups for the 960 cm-1 peak. Ca and P content differences were significant (SH5>NT=SH5E>CHX>E>CHXE). CHXE and E presented the highest Ca/P ratio values compared to the other groups (p<0.05). The SEM images in the EDTA-treated groups had the highest number of open tubules. Erosion in the tubules was observed in CHX and SH5E groups. Endodontic agents change the inorganic and organic content of pulp chamber dentin. NaOCl used alone, or in association with EDTA, was the most effective agent considering chemical and morphological approaches.

Do volcanic gases represent equilibrium volatile concentrations? Some insights from a model of diffusive fractionation during rapid bubble growth

NASA Astrophysics Data System (ADS)

Baker, D. R.

2012-12-01

Measurements of volcanic gas compositions are often presumed to be directly related to equilibrium compositions of fluids exsolved at depth in magmatic systems that rapidly escape into the atmosphere. In particular, changes in the ratios of volatile species concentrations in volcanic gases have been interpreted to reflect influx of new magma batches or changes in the degassing depth. However, other mechanisms can also yield changes in volcanic gas compositions. One such mechanism is diffusive fractionation during rapid bubble growth. Such fractionation can occur because radial growth rates of bubbles in magmas are estimated to be in the range of 10-6 to 10-3 m s-1 and diffusion coefficients of minor volatiles (e.g., Cl, F, S, CO2) are orders of magnitude slower, 10-12 to 10-9 m2 s-1. Thus a bubble that rapidly grows and subsequently loses its volatiles to the surface may contribute a fluid sample whose concentration is affected by the interplay between the kinetics of bubble growth and volatile diffusion in the melt. A finite difference code was developed to calculate the effects of rapid bubble growth on the concentration of minor elements in the bubble for a spherical growth geometry. The bubble is modeled with a fixed growth rate and a constant equilibrium fluid-melt partition coefficient, KD. Bubbles were modeled to grow to a radius of 50 μm, the size at which the dominant bubble growth mechanism appears to change from diffusion to coalescence. The critical variables that control the departure from equilibrium behavior are the K D and the ratio of the growth velocity, V, to the diffusivity, D. Modeling bubble growth in a magma chamber at 100 MPa demonstrates that when KD is in the range of 10 to 1000 at low V/D values (e.g., 103 m-1) the composition of the fluid is at, or near, equilibrium with the melt. However, as V/D increases the bubble composition deviates increasingly from equilibrium. For V/D ratios of 105 and equilibrium KD's of either 50 or 100 (similar to estimates for S), a bubble with a 50 μm radius will contain a fluid whose concentration was apparently determined by a KD of less than 10. These models also demonstrate that the combination of rapid bubble growth with slow diffusion can deplete the melt in the volatile species only within the immediate neighborhood, on the order of 100 μm. If bubbles are spaced further apart the melts may retain significant concentrations of dissolved volatiles, which could lead to secondary and tertiary nucleation events. These models for diffusive fractionation during rapid bubble growth suggest that changes in the ratios of minor elements in volcanic gases may be influenced by bubble growth rate changes. Volatiles with lower diffusivities and volatiles with very high or very low partition coefficients will be more influenced by this process. Diffusive fractionation may be responsible for the drop in the CO2/SO2 ratios sometimes observed prior to large eruptions of Stromboli volcano.

Ocean foam generation and modeling

NASA Technical Reports Server (NTRS)

Porter, R. A.; Bechis, K. P.

1976-01-01

A laboratory investigation was conducted to determine the physical and microwave properties of ocean foam. Special foam generators were designed and fabricated, using porous glass sheets, known as glass frits, as the principal element. The glass frit was sealed into a water-tight vertical box, a few centimeters from the bottom. Compressed air, applied to the lower chamber, created ocean foam from sea water lying on the frit. Foam heights of 30 cm were readily achieved, with relatively low air pressures. Special photographic techniques and analytical procedures were employed to determine foam bubble size distributions. In addition, the percentage water content of ocean foam was determined with the aid of a particulate sampling procedure. A glass frit foam generator, with pore diameters in the range 70 - 100 micrometers, produced foam with bubble distributions very similar to those found on the surface of natural ocean foam patches.

Dynamics of cavitation clouds within a high-intensity focused ultrasonic beam

NASA Astrophysics Data System (ADS)

Lu, Yuan; Katz, Joseph; Prosperetti, Andrea

2013-07-01

In this experimental study, we generate a 500 kHz high-intensity focused ultrasonic beam, with pressure amplitude in the focal zone of up to 1.9 MPa, in initially quiescent water. The resulting pressure field and behavior of the cavitation bubbles are measured using high-speed digital in-line holography. Variations in the water density and refractive index are used for determining the spatial distribution of the acoustic pressure nonintrusively. Several cavitation phenomena occur within the acoustic partially standing wave caused by the reflection of sound from the walls of the test chamber. At all sound levels, bubbly layers form in the periphery of the focal zone in the pressure nodes of the partial standing wave. At high sound levels, clouds of vapor microbubbles are generated and migrate in the direction of the acoustic beam. Both the cloud size and velocity vary periodically, with the diameter peaking at the pressure nodes and velocity at the antinodes. A simple model involving linearized bubble dynamics, Bjerknes forces, sound attenuation by the cloud, added mass, and drag is used to predict the periodic velocity of the bubble cloud, as well as qualitatively explain the causes for the variations in the cloud size. The analysis shows that the primary Bjerknes force and drag dominate the cloud motion, and suggests that the secondary Bjerknes force causes the oscillations in the cloud size.

Modeling Explosive Eruptions at Kīlauea, Hawai'i

NASA Astrophysics Data System (ADS)

Gonnermann, H. M.; Ferguson, D. J.; Blaser, A. P.; Houghton, B. F.; Plank, T. A.; Hauri, E. H.; Swanson, D. A.

2014-12-01

We have modeled eruptive magma ascent during two explosive eruptions of Kīlauea volcano, Hawai'i. They are the Hawaiian style Kīlauea Iki eruption, 1959, and the subplinian Keanakāko'i eruption, 1650 CE. We have modeled combined magma ascent in the volcanic conduit and exsolution of H2O and CO2 from the erupting magma. To better assess the relative roles of conduit processes and magma chamber, we also coupled conduit flow and magma chamber through mass balance and pressure. We predict magma discharge rates, superficial gas velocities, H2O and CO2 concentrations of the melt, magma chamber pressure, surface deformation, and height of the volcanic jet. Models are in part constrained by H2O and CO2 measured in olivine-hosted melt inclusions and by decompression rates recorded in melt embayment diffusion profiles. We present a parametric analysis, indicating that the pressure within the chamber that fed the subplinian Keanakāko'i eruption was significantly higher than lithostatic pressure. In contrast, chamber pressure for the Hawaiian Kīlauea Iki eruption was close to lithostatic. In both cases the superficial gas velocity, which affects the geometrical distribution of gas-liquid mixtures during upward flow in conduits, may have exceeded values at which bubble coalescence did not affect the flow.

Solar Thermal Propulsion Test

NASA Technical Reports Server (NTRS)

1999-01-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. The 20- by 24-ft heliostat mirror (not shown in this photograph) has a dual-axis control that keeps a reflection of the sunlight on the 18-ft diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. This image, taken during the test, depicts the light being concentrated into the focal point inside the vacuum chamber. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Research Technology

NASA Image and Video Library

1999-03-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. The 20- by 24-ft heliostat mirror (not shown in this photograph) has a dual-axis control that keeps a reflection of the sunlight on the 18-ft diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. This image, taken during the test, depicts the light being concentrated into the focal point inside the vacuum chamber. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Research Technology

NASA Image and Video Library

1999-11-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. This photograph shows a fully assembled solar thermal engine placed inside the vacuum chamber at the test facility prior to testing. The 20- by 24-ft heliostat mirror (not shown in this photograph) has a dual-axis control that keeps a reflection of the sunlight on the 18-ft diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move theNation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth orbit, rapid travel throughout the solar system, and exploration of interstellar space.

A new field-laboratory methodology for assessing human response to noise

NASA Technical Reports Server (NTRS)

Borsky, P. N.

1973-01-01

Gross measures of community annoyance with intrusive noises have been made in a number of real environment surveys which indicate that aircraft noise may have to be reduced 30-40 EPNdb before it will generally be considered acceptable. Interview studies, however, cannot provide the precise information which is needed by noise abatement engineers of the variable human response to different types and degrees of noise exposure. A new methodological field-survey approach has been developed to provide such information. The integrated attitudes and experiences of a random sample of subjects in the real environment are obtained by a prior field survey. Then these subjects record their more precise responses to controlled noise exposures in a new realistic laboratory. The laboratory is a sound chamber furnished as a typical living room (18 ft x 14 ft) and subjects watch a color TV program while they judge simulated aircraft flyovers that occur at controlled levels and intervals. Methodological experiments indicate that subjects in the laboratory have the sensation that the airplanes are actually moving overhead across the ceiling of the chamber. It was also determined that annoyance judgments in the laboratory stabilize after three flyovers are heard prior to a judgment of annoyance.

Vortex Formation Time is Not an Index of Ventricular Function

PubMed Central

Vlachos, Pavlos P.; Little, William C.

2015-01-01

The diastolic intraventricular ring vortex formation and pinch-off process may provide clinically useful insights into diastolic function in health and disease. The vortex ring formation time (FT) concept, based on hydrodynamic experiments dealing with unconfined (large tank) flow, has attracted considerable attention and popularity. Dynamic conditions evolving within the very confined space of a filling, expansible ventricular chamber with relaxing and rebounding viscoelastic muscular boundaries, diverge from unconfined (large tank) flow and encompass rebounding walls’ suction and myocardial relaxation. Indeed, clinical/physiological findings seeking validation in vivo failed to support the notion that FT is an index of normal/abnormal diastolic ventricular function. Therefore, FT as originally proposed cannot and should not be utilized as such an index. Evidently, physiologically accurate models accounting for coupled hydrodynamic and (patho)physiological myocardial wall interactions with the intraventricular flow are still needed to enhance our understanding and yield diastolic function indices useful and reliable in the clinical setting. PMID:25609509

Evidence for extreme partitioning of copper into a magmatic vapor phase.

PubMed

Lowenstern, J B; Mahood, G A; Rivers, M L; Sutton, S R

1991-06-07

The discovery of copper sulfides in carbon dioxide- and chlorine-bearing bubbles in phenocryst-hosted melt inclusions shows that copper resides in a vapor phase in some shallow magma chambers. Copper is several hundred times more concentrated in magmatic vapor than in coexisting pantellerite melt. The volatile behavior of copper should be considered when modeling the volcanogenic contribution of metals to the atmosphere and may be important in the formation of copper porphyry ore deposits.

Holographic Methods Of Dynamic Particulate Measurements ¬â€?Current Status

NASA Astrophysics Data System (ADS)

Thompson, Brian J.

1983-03-01

The field of holographic particulate measurements continues to be very active with many new applications in such diverse fields as bubble chamber recording and contaminant measurements in small vials. The methods have also been extended to measure velocity distributions of particles within a volume, particularly by the application of subsequent image processing methods. These techniques could be coupled with hybrid systems to become near real time. The current status of these more recent developments is reviewed.

High Pressure Windowed Chamber Burned Rate Determination of Liquid Propellant XM46

DTIC Science & Technology

1994-06-01

being produced. Kelzan. sold by the Kelco Company, is a gum or polysaccharide obtaincd from a fermentation process of the bacteria which occurs naturally...mixture (gel) started forming small bubbles and changing color from clear to slightly yellow. When opening the plastic bag an odor similar to vinegar was...These results were not satisfactory and another Kelco product, Rhamsam gum KIAIl2, was iavestigated. This gel is also a fermentation polysaccharide which

Evaluation of contrast-enhanced power Doppler imaging for measuring blood flow

NASA Astrophysics Data System (ADS)

Ansaloni, Sara; Arger, Peter H.; Cary, Ted W.; Sehgal, Chandra M.

2005-04-01

Power Doppler ultrasound enhanced by microbubble contrast agent has been used to image tissue vascularity and blood flow for the assessment of antivascular therapies. We have proposed a multigating technique that measures bubble concentration as a function of ultrasound exposure for deriving tumor blood flow and vascularity.1 Techniques using ultrasound contrast agent are known to be sensitive to the choice of imaging parameters like mechanical index and tissue attenuation. In this paper, the roles of mechanical index (MI) and tissue attenuation were evaluated experimentally in a rubber tubing flow phantom connected to a mixing chamber and a variable speed pump. The contrast was injected in the mixing chamber and the flow rate was measured using power Doppler imaging. The measurements were repeated at different MIs (0.1 to 1.3), and at different levels of attenuation, obtained with solutions of glycerol-water (10-20%). True flow was measured by collecting liquid flowing out of the phantom over a fixed duration. At low MI (<0.5), the grayscale and Doppler signal were weak, making these images unsuitable for analysis. At higher MI (> 0.8), there was a well-defined enhancement by contrast agent resulting in reproducible flow measurements at variable MIs. A balance between the number of bubbles destroyed and the echo they generate must be achieved for optimal imaging. The increased attenuation of ultrasound by the overlying medium did not influence the flow measurements.

Plasma Propulsion Testing Capabilities at Arnold Engineering Development Center

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Dawbarn, Albert; Moeller, Trevor

2007-01-01

This paper describes the results of a series of experiments aimed at quantifying the plasma propulsion testing capabilities of a 12-ft diameter vacuum facility (12V) at USAF-Arnold Engineering Development Center (AEDC). Vacuum is maintained in the 12V facility by cryogenic panels lining the interior of the chamber. The pumping capability of these panels was shown to be great enough to support plasma thrusters operating at input electrical power >20 kW. In addition, a series of plasma diagnostics inside the chamber allowed for measurement of plasma parameters at different spatial locations, providing information regarding the chamber's effect on the global plasma thruster flowfield. The plasma source used in this experiment was Hall thruster manufactured by Busek Co. The thruster was operated at up to 20 kW steady-state power in both a lower current and higher current mode. The vacuum level in the chamber never rose above 9 x 10(exp -6) torr during the course of testing. Langmuir probes, ion flux probes, and Faraday cups were used to quantify the plasma parameters in the chamber. We present the results of these measurements and estimates of pumping speed based on the background pressure level and thruster propellant mass flow rate.

A theoretical study of hydrodynamic cavitation.

PubMed

Arrojo, S; Benito, Y

2008-03-01

The optimization of hydrodynamic cavitation as an AOP requires identifying the key parameters and studying their effects on the process. Specific simulations of hydrodynamic bubbles reveal that time scales play a major role on the process. Rarefaction/compression periods generate a number of opposing effects which have demonstrated to be quantitatively different from those found in ultrasonic cavitation. Hydrodynamic cavitation can be upscaled and offers an energy efficient way of generating cavitation. On the other hand, the large characteristic time scales hinder bubble collapse and generate a low number of cavitation cycles per unit time. By controlling the pressure pulse through a flexible cavitation chamber design these limitations can be partially compensated. The chemical processes promoted by this technique are also different from those found in ultrasonic cavitation. Properties such as volatility or hydrophobicity determine the potential applicability of HC and therefore have to be taken into account.

V&V Of CFD Modeling Of The Argonne Bubble Experiment: FY15 Summary Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoyt, Nathaniel C.; Wardle, Kent E.; Bailey, James L.

2015-09-30

In support of the development of accelerator-driven production of the fission product Mo 99, computational fluid dynamics (CFD) simulations of an electron-beam irradiated, experimental-scale bubble chamber have been conducted in order to aid in interpretation of existing experimental results, provide additional insights into the physical phenomena, and develop predictive thermal hydraulic capabilities that can be applied to full-scale target solution vessels. Toward that end, a custom hybrid Eulerian-Eulerian-Lagrangian multiphase solver was developed, and simulations have been performed on high-resolution meshes. Good agreement between experiments and simulations has been achieved, especially with respect to the prediction of the maximum temperature ofmore » the uranyl sulfate solution in the experimental vessel. These positive results suggest that the simulation methodology that has been developed will prove to be suitable to assist in the development of full-scale production hardware.« less

Cavitation-based hydro-fracturing technique for geothermal reservoir stimulation

DOEpatents

Wang, Jy-An John; Wang, Hong; Ren, Fei; Cox, Thomas S.

2017-02-21

A rotary shutter valve 500 is used for geothermal reservoir stimulation. The valve 500 includes a pressure chamber 520 for holding a working fluid (F) under pressure. A rotatable shutter 532 is turned with a powering device 544 to periodically align one or more windows 534 with one or more apertures 526 in a bulkhead 524. When aligned, the pressurized working fluid (F) flows through the bulkhead 524 and enters a pulse cavity 522, where it is discharged from the pulse cavity 522 as pressure waves 200. The pressure wave propagation 200 and eventual collapse of the bubbles 202 can be transmitted to a target rock surface 204 either in the form of a shock wave 206, or by micro jets 208, depending on the bubble-surface distance. Once cavitation at the rock face begins, fractures are initiated in the rock to create a network of micro-fissures for enhanced heat transfer.

Dynamic Multivariate Accelerated Corrosion Test Protocol

DTIC Science & Technology

2014-10-01

atmospheric, accelerated, AA2024-T3, AA6061-T6, AA7075-T3, 1010 steel, AgCl, rare earth conversion coat, magnesium rich primer, polyurethane , Eyring, Monte...morphology and elemental analysis by scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and electrochemical determinations of...in the FT-IR analysis; degradation of the components of the high performance polyurethane coatings exposed in the UV/ozone chamber were more

Observation of excess flux for negative cosmic ray penetrating particles in bubble chamber "SKAT" for momentum range (30GeV/c

NASA Astrophysics Data System (ADS)

Bazhutov, Yu. N.; Baranov, D. S.

2001-08-01

There are presented the first results of the new heavy stable cosmic ray particles search in the bubble chamber "SKAT" (450 x 160 x 90 cm3 ), which was exposed in the neutrino beam of Serpukhov Accelerator during 1976 - 1992 years and was viewed along the horizontal direction so as the magnet field direction (MDM > 150 GeV/c). From looking over 1,270 stills (1 roll for April 23, 1979) it was selected 757 tracks of cosmic ray particles with zenith angle θ < 45°, track length - L > 50 cm and momentum P>2.0GeV/c. From this events there were constructed momentum spectrums for both negative and positive vertical cosmic ray penetrating particles in the (2.0 - 126) GeV/c range and calculated their charge ratio. For positive particles the momentum spectrum has normal shape in all studied range the same as for negative particles but only for momentum range (2.0 - 32) GeV/c and charge ratio for this range is normal and the same as for cosmic muons. But for momentum P>32GeV/c it was observed negative particles excess flux (~10-5 cm-2 s-1 sr-1 ) with changed charge ratio - R = 0.62 +/0.18 (˜>3.5σ) for momentum range (32GeV/c3σ) and for momentum range (3.6GeV/c107 cm2 ṡsṡsr); 2) the installation place must be on the Earth surface or small underground (< 100 m.w.e.); 3) it is desirable to use track detector for event and particle charge viewing. One of the largest Bubble Chamber "SKAT" (BC), operated from 1976 to 1992 on the Serpukhov Accelerator neutrino beam had satisfied to all these demands. Its operation on the neutrino beam could provide a small background from Accelerator fo r our researches. Accumulated ~ 4 x 2,000,000 stills inside ~ 4 x 1660 rolls during this long period were conserved until now and were ready to analysis. The large Bubble Chamber (450 x 160 x 90 cm3 ) had been placed in greatest magnetic field (17 kG) horizontally directed so as coaxial to it view of 4 stereo photo chambers. So near vertical penetrating cosmic rays could be registered the same as near horizontal neutrino beam events. Full "SKAT" exposition is S-T ~ 4ṡ109 cm2 ṡsṡsr , that is rather more demanded one. It provides us for charge and momentum (MDM > 150 GeV/c) measurements. BC had been placed on the Earth surface, but had large magnetic iron screen (d ~ 2500 g/cm2 = 25m.w.e., Fig.1).

Atomistic simulation of the trapping capability of He-vacancy defects at Ni {\\sum}^{}3\\left(1\\bar{1}2\\right)[110] grain boundary

NASA Astrophysics Data System (ADS)

Gong, Hengfeng; Wang, Chengbin; Zhang, Wei; Huai, Ping; Lu, Wei; Zhu, Zhiyuan

2016-12-01

He atoms tend to cluster and precipitate into bubbles that prefer to grow in the grain boundaries, resulting in high temperature He embrittlement with significantly degraded material properties. This is a major bottleneck in employing Ni-based alloys for applications such as molten salt reactors (MSRs). This paper focuses on understanding how the local grain boundary structure interacts with He atoms and how the local atomistic environment in the grain boundary influences the binding energy of He defects. Using molecular dynamics simulations, we have investigated the trapping capability of the Ni {\\sum}3≤ft(1 \\bar{1} 2\\right)≤ft[1 1 0\\right] grain boundary to He defects (He N ) and to He-vacancy defects (He N V M ). The two defects in the Ni grain boundary exhibit geometries with high symmetry. The binding energy of an interstitial He atom to He N V M defects is found to be generally larger in pure Ni than that in the grain boundary. We compared the binding energy of He N defects to the Ni vacancy and to the Ni grain boundary, finding that the Ni vacancy possesses a higher trapping strength to He N . We also found that the binding strength of He N to the grain boundary is stronger than that of He N V M to the grain boundary. The He-vacancy ratio in He N V M defects does not significantly affect the binding energy in the grain boundary plane. The current work will provide insight in understanding the experimentally observed He bubble formation in Ni-based alloys and bridge atomic scale events and damage with macroscopic failure.

Electromagnetic stirring in a microbioreactor with non-conventional chamber morphology and implementation of multiplexed mixing.

PubMed

Tan, Christabel Kl; Davies, Matthew J; McCluskey, Daniel K; Munro, Ian R; Nweke, Mauryn C; Tracey, Mark C; Szita, Nicolas

2015-10-01

Microbioreactors have emerged as novel tools for early bioprocess development. Mixing lies at the heart of bioreactor operation (at all scales). The successful implementation of micro-stirring methods is thus central to the further advancement of microbioreactor technology. The aim of this study was to develop a micro-stirring method that aids robust microbioreactor operation and facilitates cost-effective parallelization. A microbioreactor was developed with a novel micro-stirring method involving the movement of a magnetic bead by sequenced activation of a ring of electromagnets. The micro-stirring method offers flexibility in chamber designs, and mixing is demonstrated in cylindrical, diamond and triangular shaped reactor chambers. Mixing was analyzed for different electromagnet on/off sequences; mixing times of 4.5 s, 2.9 s, and 2.5 s were achieved for cylindrical, diamond and triangular shaped chambers, respectively. Ease of micro-bubble free priming, a typical challenge of cylindrical shaped microbioreactor chambers, was obtained with a diamond-shaped chamber. Consistent mixing behavior was observed between the constituent reactors in a duplex system. A novel stirring method using electromagnetic actuation offering rapid mixing and easy integration with microbioreactors was characterized. The design flexibility gained enables fabrication of chambers suitable for microfluidic operation, and a duplex demonstrator highlights potential for cost-effective parallelization. Combined with a previously published cassette-like fabrication of microbioreactors, these advances will facilitate the development of robust and parallelized microbioreactors. © 2015 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Ozone suppression of oat crown rust uredia development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heagle, A.S.

1969-01-01

First foliage leaves of 10-day-old crown rust differential varieties of Avena sativa were inoculated with urediospores of race 264 of Puccinia coronata var. avenae and placed for 16 hr in a mist chamber at 23 C. Infected plants were then placed in two separate chambers at 25C, 80% relative humidity, 3000 ft-c, and a 16-hr photoperiod. Plants in one chamber were exposed to 10 pphm ozone (KI corrected Mast value) for 6 hr daily in the light for 10 days. Plants in the other chamber were not exposed to ozone. Visible ozone injury was restricted to minor flecking. In severalmore » varieties, a slight reddening appeared on inoculated leaves near the end of the experiment. The reaction to rust on ozone-exposed plants of all varieties was resistant, whereas the reaction on nonexposed plants of all differentials except 8, 9, and 10 was susceptible. The level of ozone used in this experiment is often surpassed in rural areas near urban centers, indicating that air pollution can influence rust development in the field.« less

Issues Related to Large Flight Hardware Acoustic Qualification Testing

NASA Technical Reports Server (NTRS)

Kolaini, Ali R.; Perry, Douglas C.; Kern, Dennis L.

2011-01-01

The characteristics of acoustical testing volumes generated by reverberant chambers or a circle of loudspeakers with and without large flight hardware within the testing volume are significantly different. The parameters attributing to these differences are normally not accounted for through analysis or acoustic tests prior to the qualification testing without the test hardware present. In most cases the control microphones are kept at least 2-ft away from hardware surfaces, chamber walls, and speaker surfaces to minimize the impact of the hardware in controlling the sound field. However, the acoustic absorption and radiation of sound by hardware surfaces may significantly alter the sound pressure field controlled within the chamber/speaker volume to a given specification. These parameters often result in an acoustic field that may provide under/over testing scenarios for flight hardware. In this paper the acoustic absorption by hardware surfaces will be discussed in some detail. A simple model is provided to account for some of the observations made from Mars Science Laboratory spacecraft that recently underwent acoustic qualification tests in a reverberant chamber.

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

DOE PAGES

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

2017-05-26

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Coarse-grained discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers [Discrete particle simulations of particle segregation in rotating fluidized beds in vortex chambers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Vikrant; Li, Tingwen; De Wilde, Juray

Vortex chambers allow the generation of rotating fluidized beds, offering high-G intensified gas-solid contact, gas-solids separation and solids-solids segregation. Focusing on binary particle mixtures and fixing the density and diameter of the heavy/large particles, transient batch CFD-coarse-grained DPM simulations were carried out with varying densities or sizes of the light/small particles to evaluate to what extent combining these three functionalities is possible within a vortex chamber of given design. Both the rate and quality of segregation were analyzed. Within a relatively wide density and size range, fast and efficient segregation takes place, with an inner and slower rotating bed ofmore » the lighter/small particles forming within the outer and faster rotating bed of the heavier/large particles. Simulations show that the contamination of the outer bed with lighter particles occurs more easily than contamination of the inner bed with heavier particles and increases with decreasing difference in size or density of the particles. Bubbling in the inner bed is observed with an inner bed of very low density or small particles. Porosity plots show that vortex chambers with a sufficient number of gas inlet slots have to be used to guarantee a uniform gas distribution and particle bed. Lastly, the flexibility of particle segregation in vortex chambers with respect to the gas flow rate is demonstrated.« less

Factors influencing the shear rate acting on silicone oil to cause silicone oil emulsification.

PubMed

Chan, Yau Kei; Cheung, Ning; Wong, David

2014-10-30

The shear force between silicone oil (SO) bubble and aqueous during eye movements may underlie the development of SO emulsification. This study examines factors that may affect such shear force induced by eye movements. A surface-modified model eye chamber was put under large-amplitude eye movements (amplitude 90°, angular velocity 360°/s, and a duration 300 ms). Agarose-made indentations were introduced to mimic the effect of encircling scleral buckle. Two SOs (1300 and 5000 centistokes [cSt]), three volumes (3, 4, and 5 mL), and two eye chambers (with and without indentation) were tested. Video recording was used to capture the movements of SO inside the model chamber under various conditions. The presence of indentation within the eye chamber significantly reduced the velocity of SO movements relative to the eye chamber movements (P < 0.001). To a lesser extent, an increase in viscosity also had a significant effect in reducing the relative movements. No significant effect was observed for the extent of SO fill in the chamber. Our experimental model suggests indentation within an eye, such as that created by scleral buckling, may have the greatest influence in reducing shear force induced by eye movements. Therefore, using an encircling scleral buckle may be similarly or more effective than using SO with higher viscosity in lowering the propensity to SO emulsification. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Sterilization Effect of Wet Oxygen Plasma in the Bubbling Method.

PubMed

Tamazawa, Kaoru; Shintani, Hideharu; Tamazawa, Yoshinori; Shimauchi, Hidetoshi

2015-01-01

A new low-temperature sterilization method to replace the ethylene oxide gas sterilization is needed. Strong bactericidal effects of OH and O2H radicals are well known. The purpose of this study was to evaluate the sterilization effect of wet oxygen ("O2+H2O") plasma in the bubbling method, confirming the effect of humidity. Sterility assurance was confirmed by using a biological indicator (Geobacillus stearothermophilus ATCC7953, Namsa, USA). One hundred and eight samples (10(5) spores/carrier) were divided into three groups of 36 in each for treatment with a different type of gas (O2, O2+H2O, Air+H2O). Plasma processing was conducted using a plasma ashing apparatus (13.56 MHz, PACK-3(®), Y. A. C., Japan) under various gas pressures (13, 25, 50 Pa) and gas flows (50, 100, 200 sccm). Fixed plasma treatment parameters were power at 150 W, temperature of 60 ℃, treatment time of 10 min. The samples after treatment were incubated in trypticase soy broth at 58 ℃ for 72 h. The negative culture rate in the "O2+H2O" group was significantly (Mantel-Haenszel procedure, p<0.001) higher than in the other gas groups. It is suggested that the significant sterilization effect of the "O2+H2O" group depends on the bubbling method which is the method of introducing vapor into the chamber. The bubbling method seems able to generate OH and O2H radicals in a stable way.

Radiation-induced grain subdivision and bubble formation in U3Si2 at LWR temperature

NASA Astrophysics Data System (ADS)

Yao, Tiankai; Gong, Bowen; He, Lingfeng; Harp, Jason; Tonks, Michael; Lian, Jie

2018-01-01

U3Si2, an advanced fuel form proposed for light water reactors (LWRs), has excellent thermal conductivity and a high fissile element density. However, limited understanding of the radiation performance and fission gas behavior of U3Si2 is available at LWR conditions. This study explores the irradiation behavior of U3Si2 by 300 keV Xe+ ion beam bombardment combining with in-situ transmission electron microscopy (TEM) observation. The crystal structure of U3Si2 is stable against radiation-induced amorphization at 350 °C even up to a very high dose of 64 displacements per atom (dpa). Grain subdivision of U3Si2 occurs at a relatively low dose of 0.8 dpa and continues to above 48 dpa, leading to the formation of high-density nanoparticles. Nano-sized Xe gas bubbles prevail at a dose of 24 dpa, and Xe bubble coalescence was identified with the increase of irradiation dose. The volumetric swelling resulting from Xe gas bubble formation and coalescence was estimated with respect to radiation dose, and a 2.2% volumetric swelling was observed for U3Si2 irradiated at 64 dpa. Due to extremely high susceptibility to oxidation, the nano-sized U3Si2 grains upon radiation-induced grain subdivision were oxidized to nanocrystalline UO2 in a high vacuum chamber for TEM observation, eventually leading to the formation of UO2 nanocrystallites stable up to 80 dpa.

Extreme ultraviolet (EUV) and FUV calibration facility for special sensor ultraviolet limb imager (SSULI)

NASA Astrophysics Data System (ADS)

Boyer, Craig N.; Osterman, Steven N.; Thonnard, Stefan E.; McCoy, Robert P.; Williams, J. Z.; Parker, S. E.

1994-09-01

A facility for calibrating far ultraviolet and extreme ultraviolet instruments has recently been completed at the Naval Research Laboratory. Our vacuum calibration vessel is 2-m in length, 1.67-m in diameter, and can accommodate optical test benches up to 1.2-m wide by 1.5-m in length. A kinematically positioned frame with four axis precision pointing capability of 10 microns for linear translation and .01 degrees for rotation is presently used during vacuum optical calibration of SSULI. The chamber was fabricated from 304 stainless steel and polished internally to reduce surface outgassing. A dust-free environment is maintained at the rear of the vacuum chamber by enclosing the 2-m hinged vacuum access door in an 8 ft. by 8 ft. class 100 clean room. Every effort was made to obtain an oil-free environment within the vacuum vessel. Outgassing products are continually monitored with a 1 - 200 amu residual gas analyzer. An oil-free claw and vane pump evacuates the chamber to 10-2 torr through 4 in. diameter stainless steel roughing lines. High vacuum is achieved and maintained with a magnetically levitated 480 l/s turbo pump and a 3000 l/s He4 cryopump. Either of two vacuum monochrometers, a 1-m f/10.4 or a 0.2-m f/4.5 are coaxially aligned with the optical axis of the chamber and are used to select single UV atomic resonance lines from a windowless capillary or penning discharge UV light source. A calibrated channeltron detector is coaxially mounted with the SSULI detector during calibration. All vacuum valves, the cooling system for the cryopump compressor, and the roughing pump are controlled through optical fibers which are interfaced to a computer through a VME board. Optical fibers were chosen to ensure that complete electrical isolation is maintained between the computer and the vacuum system valves-solenoids and relays.

Design and optimization of a deflagration to detonation transition (ddt) section

NASA Astrophysics Data System (ADS)

Romo, Francisco X.

Throughout the previous century, hydrocarbon-fueled engines have used and optimized the `traditional' combustion process called deflagration (subsonic combustion). An alternative form of combustion, detonation (supersonic combustion), can increase the thermal efficiency of the process by anywhere from 20 - 50%. Even though several authors have studied detonation waves since the 1890's and a plethora of papers and books have been published, it was not until 2008 that the first detonation-powered flight took place. It lasted for 10 seconds at 100 ft. altitude. Achieving detonation presents its own challenges: some fuels are not prone to detonate, severe vibrations caused by the cyclic nature of the engine and its intense noise are some of the key areas that need further research. Also, to directly achieve detonation either a high-energy, bulky, ignition system is required, or the combustion chamber must be fairly long (5 ft. or more in some cases). In the latter method, a subsonic flame front accelerates within the combustion chamber until it reaches supersonic speeds, thus detonation is attained. This is called deflagration-todetonation transition (DDT). Previous papers and experiments have shown that obstacles, such as discs with an orifice, located inside the combustion chamber can shorten the distance required to achieve detonation. This paper describes a hands-on implementation of a DDT device. Different disc geometries inside the chamber alter the wave characteristics at the exit of the tube. Although detonation was reached only when using pure oxygen, testing identified an obstacle configuration for LPG and air mixtures that increased pressure and wave speed significantly when compared to baseline or other obstacle configurations. Mixtures of LPG and air were accelerated to Mach 0.96 in the downstream frame of reference, which would indicate a transition to detonation was close. Reasons for not achieving detonation may include poor fuel and oxidizer mixing, and/or the need for a longer DDT section.

Coherent production of ρ - mesons in charged current antineutrino-neon interactions in BEBC

NASA Astrophysics Data System (ADS)

Marage, P.; Aderholz, M.; Allport, P.; Armenise, N.; Baton, J. P.; Berggren, M.; Bertrand, D.; Brisson, V.; Bullock, F. W.; Burkot, W.; Calicchio, M.; Clayton, E. F.; Coghen, T.; Cooper-Sarkar, A. M.; Erriquez, O.; Fitch, P. J.; Guy, J.; Hamisi, F.; Hulth, P. O.; Jones, G. T.; Kasper, P.; Katz, U. F.; Klein, H.; Matsinos, E.; Middleton, R. P.; Miller, D. B.; Mobayyen, M. M.; Morrison, D. R. O.; Neveu, M.; O'Neale, S. W.; Parker, M. A.; Petiau, P.; Sacton, J.; Sansum, R. A.; Schmitz, N.; Simopoulou, E.; Vallée, C.; Varvell, K.; Vayaki, A.; Venus, W.; Wachsmuth, H.; Wells, J.; Wittek, W.

1987-09-01

Coherent production of ρ - mesons in charged current antineutrino interactions on neon nuclei is studied in the BEBC bubble chamber exposed to the CERN SPS wide band beam. The cross section is measured to be (95±25)·10-40 cm2 per neon nucleus, averaged over the beam energy spectrum. The distributions of kinematical variables and the absolute value of the cross section are in agreement with theoretical predictions based on the CVC hypothesis and the vector meson dominance model.

Preliminary Feasibility and Risk Analysis of a Carbon Dioxide Barrier at Brandon Road Lock and Dam

DTIC Science & Technology

2017-09-01

designed bubble plume must be maintained. Wuest and Lorke (2003) describe this as natural (i.e., wind induced) turbulent mixing in lakes. Their study is...elevated CO2 concentrations in areas sheltered from wind and wave action (much like the approach channel and immediately upstream of the lock chamber) may...or kill them. As part of the development of fish barriers to prevent entrainment of fish into a pump turbine hydropower system, Nestler et al

The Removal of NOx Using a Pulsed Streamer Corona Discharge in the Presence of Ethylene

DTIC Science & Technology

1996-07-25

be a stratospheric ozone destructor and a greenhouse gas (U.S EPA, 1993). Nitric oxide (NO) is an odorless gas and is only slightly soluble in water...gas can be bubbled for humidification , 5) flow meters, valves, and mass flow controllers, and 6) a stainless steel mixing chamber upstream from the...Reduction of Acid and Greenhouse Gases in Combustion of Flue Gases", Non-Thermal Plasma Techniques for Pollution Control, Part A, Eds: Penetrante

Ambulation During Periods of Supersaturation Increase Decompression Stress in Spacewalk Simulations

NASA Technical Reports Server (NTRS)

Pollock, N. W.; Natoli, M. J.; Martina, S. D.; Conkin, J.; Wessel, J. H., III; Gernhardt, M. L.

2016-01-01

Musculoskeletal activity accelerates inert gas elimination during oxygen breathing prior to decompression (prebreathe), but may also promote bubble formation (nucleation) and increase the risk of decompression sickness (DCS). The timing, pattern and intensity of musculoskeletal activity and the level of tissue supersaturation are likely critical to the net effect. Understanding the relationships is important to evaluate exercise prebreathe protocols and quantify decompression risk in gravity and microgravity environments. The NASA Prebreathe Reduction Program (PRP) combined oxygen prebreathe and exercise preceding a low pressure (4.3 psia; altitude equivalent of 30,300 ft [9,235 m]) simulation exposure of non-ambulatory subjects (a microgravity analog) to produce two protocols now used by astronauts preparing for extravehicular activity. One protocol included both upright cycling and non-cycling exercise (CEVIS: 'cycle ergometer vibration isolation system') and one protocol relied on non-cycling exercise only (ISLE: 'in-suit light exercise'). CEVIS trial data serve as control data for the current study to investigate the influence of ambulation exercise in 1G environments on bubble formation and the subsequent risk of DCS.

Liquid phase fluid dynamic (methanol) run in the LaPorte alternative fuels development unit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bharat L. Bhatt

1997-05-01

A fluid dynamic study was successfully completed in a bubble column at DOE's Alternative Fuels Development Unit (AFDU) in LaPorte, Texas. Significant fluid dynamic information was gathered at pilot scale during three weeks of Liquid Phase Methanol (LPMEOJP) operations in June 1995. In addition to the usual nuclear density and temperature measurements, unique differential pressure data were collected using Sandia's high-speed data acquisition system to gain insight on flow regime characteristics and bubble size distribution. Statistical analysis of the fluctuations in the pressure data suggests that the column was being operated in the churn turbulent regime at most of themore » velocities considered. Dynamic gas disengagement experiments showed a different behavior than seen in low-pressure, cold-flow work. Operation with a superficial gas velocity of 1.2 ft/sec was achieved during this run, with stable fluid dynamics and catalyst performance. Improvements included for catalyst activation in the design of the Clean Coal III LPMEOH{trademark} plant at Kingsport, Tennessee, were also confirmed. In addition, an alternate catalyst was demonstrated for LPMEOH{trademark}.« less

Space shuttle orbital maneuvering engine platelet injector program

NASA Technical Reports Server (NTRS)

1975-01-01

A platelet-face injector for the fully reusable orbit maneuvering system OMS on the space shuttle was evaluated as a means of obtaining additional design margin and low cost. Performance, heat transfer, and combustion stability were evaluated over the anticipated range of OMS operating conditions. The effects of acoustic cavity configuration on combustion stability, including cavity depth, open area, inlet contour, and other parameters, were investigated using sea level bomb tests. Prototype injector and chamber behavior was evaluated for a variety of conditions; these tests examined the effects of film cooling, helium saturated propellants, chamber length, inlet conditions, and operating point, on performance, heat transfer and engine transient behavior. Helium bubble ingestion into both propellant circuits was investigated, as was chugging at low pressure operation, and hot and cold engine restart with and without a purge.

Research Technology

NASA Image and Video Library

1999-08-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. The 20- by 24-ft heliostat mirror (not shown in this photograph) has dual-axis control that keeps a reflection of the sunlight on an 18-ft diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. This photograph is a close-up view of a 4-in focal point inside the vacuum chamber at the MSFC Solar Thermal Propulsion Test facility. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Research Technology

NASA Image and Video Library

1999-08-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. This photograph, taken at MSFC's Solar Thermal Propulsion Test Facility, shows a concentrator mirror, a combination of 144 mirrors forming this 18-ft diameter concentrator, and a vacuum chamber that houses the focal point. The 20- by 24-ft heliostat mirror (not shown in this photograph) has a dual-axis control that keeps a reflection of the sunlight on the 18-foot diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth-orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Solar Thermal Propulsion Test Facility

NASA Technical Reports Server (NTRS)

1999-01-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. This photograph shows a fully assembled solar thermal engine placed inside the vacuum chamber at the test facility prior to testing. The 20- by 24-ft heliostat mirror (not shown in this photograph) has a dual-axis control that keeps a reflection of the sunlight on the 18-ft diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move theNation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Solar Thermal Propulsion Test Facility

NASA Technical Reports Server (NTRS)

1999-01-01

Researchers at the Marshall Space Flight Center (MSFC) have designed, fabricated and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than a chemical combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propellant. This photograph, taken at MSFC's Solar Thermal Propulsion Test Facility, shows a concentrator mirror, a combination of 144 mirrors forming this 18-ft diameter concentrator, and a vacuum chamber that houses the focal point. The 20- by 24-ft heliostat mirror (not shown in this photograph) has a dual-axis control that keeps a reflection of the sunlight on the 18-foot diameter concentrator mirror, which then focuses the sunlight to a 4-in focal point inside the vacuum chamber. The focal point has 10 kilowatts of intense solar power. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth-orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Testing Air-Filtering Systems

PubMed Central

Songer, Joseph R.; Sullivan, James F.; Hurd, James W.

1963-01-01

A procedure was developed for evaluating high-efficiency filters mounted in exhaust ducts at the National Animal Disease Laboratory. An aerosol of the test organism, Escherichia coli B T3 bacteriophage, was generated in a chamber attached to a ceiling exhaust register in concentrations of at least 1000 viable organisms per ft3 of air. Samples were collected from both the pre- and postfilter areas, and the number of organisms per ft3 of air was determined. The efficiency of the filter was calculated from these figures. A total of 269 high-efficiency filters were tested. Of these, 249 had efficiencies of 98% or greater. The remaining 20, with efficiencies of less than 98%, were repaired and retested. No filter was accepted with an efficiency of less than 98%. Images Fig. 2 PMID:14063779

An analysis of sound absorbing linings for the interior of the NASA Ames 80 x 120-foot wind tunnel

NASA Technical Reports Server (NTRS)

Wilby, J. F.; White, P. H.

1985-01-01

It is desirable to achieve low frequency sound absorption in the tests section of the NASA Ames 80X120-ft wind tunnel. However, it is difficult to obtain information regarding sound absorption characteristics of potential treatments because of the restrictions placed on the dimensions of the test chambers. In the present case measurements were made in a large enclosure for aircraft ground run-up tests. The normal impedance of the acoustic treatment was measured using two microphones located close to the surface of the treatment. The data showed reasonably good agreement with analytical methods which were then used to design treatments for the wind tunnel test section. A sound-absorbing lining is proposed for the 80X120-ft wind tunnel.

Laboratory Characterization Tests for Antimisting Fuel.

DTIC Science & Technology

1987-03-01

Por hdi cal lv, clean wtith chromic acid to reTove traces r! rt c ,t r al e t 1t,’ t t I irt ft tf,(- viscomter C t! tC. ’o( +( .fl50( ,r,, .. , i:t...bath to bel ow 3.9o C. Bubbl e gaseous sul1fur dioxid’e (SO-) through rocetatdsul furic acid (S( 4 ,sp gr 1 .84-) into th, coo led mixture . (’out :oue...qeyce. .t d ’ŕ X oku.4 ict t ,Avenue., NW 3034 W! I. Mr. ,. Thris Meldrum Mr. James H. O’Mara Texdao Company Rohm and Haas P.O. Box 430 727

High-power laser phosphor light source with liquid cooling for digital cinema applications

NASA Astrophysics Data System (ADS)

Li, Kenneth

2014-02-01

Laser excited phosphor has been used to excite phosphor material, producing high intensity light output with smaller etendue than that of LEDs with the same long lifetime. But due to the high intensity of the laser light, phosphor with organic binder burns at low power, which requires the phosphor to be deposited on a rotating wheel in practical applications. Phosphor with inorganic binders, commonly known as ceramic phosphor, on the other hand, does not burn, but efficiency goes down as temperature goes up under high power excitation. This paper describes cooling schemes in sealed chambers such that the phosphor materials using organic or inorganic binders can be liquid cooled for high efficiency operations. Confined air bubbles are introduced into the sealed chamber accommodating the differential thermal expansion of the liquid and the chamber. For even higher power operation suitable for digital cinema, a suspension of phosphor in liquid is described suitable for screen brightness of over 30,000 lumens. The aging issues of phosphor can also be solved by using replaceable phosphor cartridges.

Modeling study on the flow patterns of gas-liquid flow for fast decarburization during the RH process

NASA Astrophysics Data System (ADS)

Li, Yi-hong; Bao, Yan-ping; Wang, Rui; Ma, Li-feng; Liu, Jian-sheng

2018-02-01

A water model and a high-speed video camera were utilized in the 300-t RH equipment to study the effect of steel flow patterns in a vacuum chamber on fast decarburization and a superior flow-pattern map was obtained during the practical RH process. There are three flow patterns with different bubbling characteristics and steel surface states in the vacuum chamber: boiling pattern (BP), transition pattern (TP), and wave pattern (WP). The effect of the liquid-steel level and the residence time of the steel in the chamber on flow patterns and decarburization reaction were investigated, respectively. The liquid-steel level significantly affected the flow-pattern transition from BP to WP, and the residence time and reaction area were crucial to evaluate the whole decarburization process rather than the circulation flow rate and mixing time. A superior flow-pattern map during the practical RH process showed that the steel flow pattern changed from BP to TP quickly, and then remained as TP until the end of decarburization.

Runaway electron studies with hard x-ray and microwave diagnostics in the FT-2 lower hybrid current drive discharges

NASA Astrophysics Data System (ADS)

Shevelev, A. E.; Khilkevitch, E. M.; Lashkul, S. I.; Rozhdestvensky, V. V.; Pandya, S. P.; Plyusnin, V. V.; Altukhov, A. B.; Kouprienko, D. V.; Chugunov, I. N.; Doinikov, D. N.; Esipov, L. A.; Gin, D. B.; Iliasova, M. V.; Naidenov, V. O.; Polunovsky, I. A.; Sidorov, A. V.; Kiptily, V. G.

2018-01-01

Studies of the super-thermal and runaway electron behavior in ohmic and lower hybrid current drive FT-2 tokamak plasmas have been carried out using information obtained from measurements of hard x-ray spectra and non-thermal microwave radiation intensity at the frequency of 10 GHz and in the range of (53 ÷ 78) GHz. A gamma-ray spectrometer based on a scintillation detector with a LaBr3(Ce) crystal was used, which provides measurements at counting rates up to 107 s-1. Reconstruction of the energy distribution of RE interacting with the poloidal limiter of the tokamak chamber was made with application of the DeGaSum code. Super-thermal electrons accelerated up to 2 MeV by the LH waves at the high-frequency pumping of the plasma with low density ≤ft< {{n}e} \\right> ~ 2  ×  1013 cm-3 and then up to 7 MeV by vortex electric field have been found. Experimental analysis of the runaway electron beam generation and evolution of their energy distribution in the FT-2 plasmas is presented in the article and compared with the numerical calculation of the maximum energy gained by runaway electrons for given plasma parameters. In addition, possible mechanisms for limiting the maximum energy gained by the runaway electrons are also calculated and described for a FT-2 plasma discharge.

Solar Collector With Image-Forming Mirror Cavity to Irradiate Small Central Volume

NASA Technical Reports Server (NTRS)

Buchele, Don; Castle, Charles; Bonoetti, Joseph A.

2001-01-01

A unique solar thermal chamber has been designed and fabricated to produce the maximum concentration of solar energy and higher temperature possible. Its primary purpose was for solar plasma propulsion experiments and related material specimen testing above 3000 K. The design not only maximized solar concentration, but also, minimized infrared heat loss. This paper provides the underlying theory and operation of the chamber and initial optical correlation to the actual fabricated hardware. The chamber is placed at the focal point of an existing primary concentrator with a 2.74 m (9 ft) focal length. A quartz lens focuses a small sun image at the inlet hole of the mirrored cavity. The lens focuses two image planes at prescribed positions; the sun at the cavity's entrance hole and the primary concentrator at the junction plane of two surfaces that form the cavity chamber. The back half is an ellipsoid reflector that produces a 1.27 cm diameter final sun image. The image is "suspended in space," 7.1 cm away from the nearest cavity surface, to minimize thermal and contaminate damage to the mirror surfaces. A hemisphere mirror makes up the front chamber and has its center of curvature at the target image, where rays leaving the target are reflected back upon themselves, minimizing radiation losses.

Working (And Sparring) With Luis: Some Personal Recollections

NASA Astrophysics Data System (ADS)

Pripstein, Moishe

2011-04-01

Luis Alvarez was the most remarkable physicist I have ever worked with. As a member of his bubble chamber group at the Lawrence Radiation Laboratory in Berkeley and subsequently as a leader of that group for several years, I could appreciate his outstanding attributes as a physicist and his forceful and colorful personality. Each day at the lab seemed exciting. Although he created the largest research group in particle physics in the world at the time, Luis was an ardent foe of group-think, which he characterized as ``intellectual phase-lock''. He had an uncanny intuition about physics and technology, coupled with an insatiable curiosity about the world around him. He is justly renowned as a member of the Inventors Hall of Fame for his myriad inventions and as a Nobel Laureate in physics for his contributions to particle physics through his development of the hydrogen bubble chamber technique, leading to the discovery of a large number of resonance states. However, it was his wide-ranging curiosity which led him to one of his finest achievements, while working with his son Walter - developing the asteroid impact theory as the explanation of the extinction of the dinosaurs. I will offer some personal recollections of Luis and the group in this period, including some of his other intriguing efforts which illustrate the breadth of his interests, pertaining to the Kennedy assassination and x-raying the pyramids, among them. All in all, a brilliant and most unusual scientist and stimulating colleague.

Verification of an altitude decompression sickness prevention protocol for Shuttle operations utilizing a 10.s psi pressure stage

NASA Technical Reports Server (NTRS)

Waligora, J. M.; Horrigan, D. J., Jr.; Conkin, J.; Hadley, A. T., III

1984-01-01

Three test series involving 173-man tess were conducted to define and verify a pre-extravehicular activity (EVA) denitrogenation procedure that would provide acceptable protection against altitude decompression sickness while minimizing the required duration of oxygen (O2) prebreathe in the suit prior to EVA. The tests also addressed the safety, in terms of incidence of decompression sickness, of conducting EVA's on consecutive days rather than on alternate days. The tests were conducted in an altitude chamber, subjects were selected as representative of the astronaut population, and EVA periods were simulated by reducing the chamber pressure to suit pressure while the subjects breathed O2 with masks and worked at EVA representative work rates. A higher than anticipated incidence of both venous bubbles (55%) and symptoms (26%) was measured following all denitrogenation protocols in this test. For the most part, symptoms were very minor and stabilized, diminished, or disappeared in the six-hour tests. Instances of clear, possible, or potential systemic symptoms were encountered only after use of the unmodified 10.2 psi protocol and not after the modified 10.2 psi protocol, the 3.5-hour O2 prebreathed protocol, or the 4.0-hour O2 prebreathe protocol. The high incidence of symptoms is ascribed to the type and duration of exercise and the sensitivity of the reporting technique to minor symptoms. Repeated EVA exposures after only 17 hours did not increase symptom or bubble incidence.

Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces.

PubMed

Boks, Niels P; Norde, Willem; van der Mei, Henny C; Busscher, Henk J

2008-10-01

Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F(prev)) and to detach adhering bacteria (F(det)) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the following three hypotheses. 1. A strong hydrodynamic shear force to prevent adhesion relates to a strong hydrodynamic shear force to detach an adhering organism. 2. A weak hydrodynamic shear force to detach adhering bacteria implies that more bacteria will be stimulated to detach by passing an air-liquid interface (an air bubble) through the flow chamber. 3. DLVO (Derjaguin, Landau, Verwey, Overbeek) interactions determine the characteristic hydrodynamic shear forces to prevent adhesion and to detach adhering micro-organisms as well as the detachment induced by a passing air-liquid interface. F(prev) varied from 0.03 to 0.70 pN, while F(det) varied from 0.31 to over 19.64 pN, suggesting that after initial contact, strengthening of the bond occurs. Generally, it was more difficult to detach bacteria from DDS-coated glass than from hydrophilic glass, which was confirmed by air bubble detachment studies. Calculated attractive forces based on the DLVO theory (F(DLVO)) towards the secondary interaction minimum were higher on glass than on DDS-coated glass. In general, all three hypotheses had to be rejected, showing that it is important to distinguish between forces acting parallel (hydrodynamic shear) and perpendicular (DLVO, air-liquid interface passages) to the substratum surface.

Erzion interpretation of negative penetrating cosmic ray particles excess flux observed in bubble chamber "SKAT"

NASA Astrophysics Data System (ADS)

Bazhutov, Yu. N.

2001-08-01

It is discussed the interpretation of negative penetrating cosmic ray particles excess flux observed in bubble chamber "SKAT" for the momentum range P > P0 = 30 GeV/c by Erzions, hypothetical heavy stable penetrating hadrons, proposed to explain the anomalous vertical muons energy spectrum at small depth underground. Here it is shown that negative charge of p articles observed in "SKAT" is the same as predicted by theoretical Erzion model. The excess particles flux ( J ˜ 10-5 cm-2 s-1 sr-1 ) corresponds to the Erzion intensity observed by scintillation telescope in our previous experiment. The threshold momentum ( P0 ) and the track length threshold ( L0 = 50 cm of liquid BrF3C) are in good accordance with Erzion stop path as for the single charged particle with mass M ≅ 200 GeV/c2 . But to don't contradict with all previous charge ratio results for cosmic ray muons in 30 - 100 GeV/c momentum range it is necessary to propose for such particles the Solar sporadic origin taking to account that both Erzion observations were in the active Sun years (April 23,1979 & July, 1999). INTRODUCTION. 20 years ago to explain anomalous energy spectrum of vertical cosmic ray muons, observed at sea level and small depth underground (<100 m.w.e.) [1,2], it was proposed hypothesis of existing in cosmic rays new heavy stable penetrating hadrons [3]. From that time our experiments to search such particles were started [4,5,6]. Later the theoretical model U(1)xSUl(2)xSU r(2)xSU(3) of such particles (Erzions) has been created in framework of "mirror" models [7,8], which without contradictions to elementary particles Standard Model has explained large kind of another anomalous results in cosmic rays and nuclear physics [9-19]. At last after almost 20 years Erzions search they have been observed due to small vertical original scintillation telescope "Doch-4" [20,21,22]. The observed Erz ions mass was ME = (175+/-25) GeV/c2 and intensity at sea level - JE = (1.8+/-0.4)ṡ10-6 cm-2 sr-1 s-1 (at EE ≤ 6 GeV, PE ≤ 50 GeV/c2 ). To confirm such Erzion discovery it was undertook the attempt of Erzions search on one of the largest bubble chamber (BC) "SKAT", exposed 16 years (19761992) on the neutrino beam of Serpukhov Proton Accelerator.

Impact of 10% SF6 Gas Compared to 100% Air Tamponade in Descemet's Membrane Endothelial Keratoplasty.

PubMed

Rickmann, Annekatrin; Szurman, Peter; Jung, Sacha; Boden, Karl Thomas; Wahl, Silke; Haus, Arno; Boden, Katrin; Januschowski, Kai

2018-04-01

To compare the clinical outcomes following Descemet's membrane endothelial keratoplasty (DMEK) with 100% air tamponade versus 10% sulfur hexafluoride (SF 6 ) tamponade. Retrospective analysis of 108 consecutive DMEK cases subdivided by anterior chamber tamponade with 54 eyes receiving 10% SF 6 and 54 eyes receiving 100% air injection. A post-hoc matched analysis revealed no statistically significant differences between the groups. The main outcome measurements were the complication rate, including intra- and postoperative complications and graft detachment rate requiring re-bubbling. Clinical outcome included best-corrected visual acuity (BCVA), endothelial cell count (ECC), and central corneal thickness (CCT) measured 1, 3, and 6 months after DMEK surgery. The graft detachment rate with consecutive re-bubbling was 18.5% in the air group and 22.2% in the SF 6 group (p = 0.2). Remaining small peripheral graft detachments with a clear cornea occurred more often in the 100% air group (air: 22.2%; 12/54, 6/12 inferior compared to SF 6 : 7.4%; 4/54, 2/4 inferior; p = 0.06). The primary graft failure rate was comparable between the two groups. No complete graft detachment occurred. Outcome results for BCVA, ECC, and CCT at all follow-up time points were comparable between the two groups. The clinical outcomes (including re-bubbling rate, primary graft failure rate, and endothelial cell loss) were comparable with 100% air versus 10% SF 6 tamponade, whereas other studies suggest that a higher SF 6 concentration (20%) may result in a lower re-bubbling rate.

Recent Improvements to the Acoustical Testing Laboratory at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Podboy, Devin M.; Mirecki, Julius H.; Walker, Bruce E.; Sutliff, Daniel L.

2014-01-01

The Acoustical Testing Laboratory (ATL) consists of a 27- by 23- by 20-ft (height) convertible hemi/anechoic chamber and separate sound-attenuating test support enclosure. Absorptive fiberglass wedges in the test chamber provide an anechoic environment down to 100 Hz. A spring-isolated floor system affords vibration isolation above 3 Hz. These specifications, along with very low design background levels, enable the acquisition of accurate and repeatable acoustical measurements on test articles that produce very low sound pressures. Removable floor wedges allow the test chamber to operate in either a hemi-anechoic or anechoic configuration, depending on the size of the test article and the specific test being conducted. The test support enclosure functions as a control room during normal operations. Recently improvements were accomplished in support of continued usage of the ATL by NASA programs including an analysis of the ultra-sonic characteristics. A 3-D traverse system inside the chamber was utilized for acquiring acoustic data for these tests. The traverse system drives a linear array of 13, 1/4 in.-microphones spaced 3 in. apart (36 in. span). An updated data acquisition system was also incorporated into the facility.

Recent Improvements to the Acoustical Testing Laboratory at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Podboy, Devin M.; Mirecki, Julius H.; Walker, Bruce E.; Sutliff, Daniel L.

2014-01-01

The Acoustical Testing Laboratory (ATL) consists of a 27 by 23 by 20 ft (height) convertible hemi/anechoic chamber and separate sound-attenuating test support enclosure. Absorptive fiberglass wedges in the test chamber provide an anechoic environment down to 100 Hz. A spring-isolated floor system affords vibration isolation above 3 Hz. These specifications, along with very low design background levels, enable the acquisition of accurate and repeatable acoustical measurements on test articles that produce very low sound pressures. Removable floor wedges allow the test chamber to operate in either a hemi-anechoic or anechoic configuration, depending on the size of the test article and the specific test being conducted. The test support enclosure functions as a control room during normal operations. Recently improvements were accomplished in support of continued usage of the ATL by NASA programs including an analysis of the ultra-sonic characteristics. A 3 dimensional traverse system inside the chamber was utilized for acquiring acoustic data for these tests. The traverse system drives a linear array of 13, 1/4"-microphones spaced 3" apart (36" span). An updated data acquisition system was also incorporated into the facility.

Results from the irradiation of stainless steel and copper by 23 MeV γ-quanta in the atmosphere of molecular deuterium at a pressure of 2 kbar

NASA Astrophysics Data System (ADS)

Didyk, A. Yu.; Wisniewski, R.

2014-05-01

Metal samples were arranged inside a "finger-type" high-pressure chamber (DHPC-FT) filled by deuterium. They were two aluminum rods, a copper rod, two specimens of homogeneous YMn2 alloy, and a stainless steel wire. The pressure of molecular deuterium in DHPC-FT was about 2 kbar. The samples were irradiated by braking γ-quanta at a threshold energy of 23 MeV. All the samples were studied using scanning electron microscopy (SEM) and X-ray (roentgen) microelement probe analysis (RMPA). Considerable changes in the surface structure and elemental composition were found for the samples of copper, aluminum, YMn2 alloy, and stainless steel. Unusual results were analyzed in detail and compared with the earlier data.

Efficient generation of cavitation bubbles and reactive oxygen species using triggered high-intensity focused ultrasound sequence for sonodynamic treatment

NASA Astrophysics Data System (ADS)

Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

2016-07-01

Sonodynamic treatment is a method of treating cancer using reactive oxygen species (ROS) generated by cavitation bubbles in collaboration with a sonosensitizer at a target tissue. In this treatment method, both localized ROS generation and ROS generation with high efficiency are important. In this study, a triggered high-intensity focused ultrasound (HIFU) sequence, which consists of a short, extremely high intensity pulse immediately followed by a long, moderate-intensity burst, was employed for the efficient generation of ROS. In experiments, a solution sealed in a chamber was exposed to a triggered HIFU sequence. Then, the distribution of generated ROS was observed by the luminol reaction, and the amount of generated ROS was quantified using KI method. As a result, the localized ROS generation was demonstrated by light emission from the luminol reaction. Moreover, it was demonstrated that the triggered HIFU sequence has higher efficiency of ROS generation by both the KI method and the luminol reaction emission.

Possibility of measuring Adler angles in charged current single pion neutrino-nucleus interactions

NASA Astrophysics Data System (ADS)

Sánchez, F.

2016-05-01

Uncertainties in modeling neutrino-nucleus interactions are a major contribution to systematic errors in long-baseline neutrino oscillation experiments. Accurate modeling of neutrino interactions requires additional experimental observables such as the Adler angles which carry information about the polarization of the Δ resonance and the interference with nonresonant single pion production. The Adler angles were measured with limited statistics in bubble chamber neutrino experiments as well as in electron-proton scattering experiments. We discuss the viability of measuring these angles in neutrino interactions with nuclei.

Performance Increase Verification for a Bipropellant Rocket Engine

NASA Technical Reports Server (NTRS)

Alexander, Leslie; Chapman, Jack; Wilson, Reed; Krismer, David; Lu, Frank; Wilson, Kim; Miller, Scott; England, Chris

2008-01-01

Component performance assessment testing for a, pressure-fed earth storable bipropellant rocket engine was successfully completed at Aerojet's Redmond test facility. The primary goal of the this development project is to increase the specific impulse of an apogee class bi-propellant engine to greater than 330 seconds with nitrogen tetroxide and monomethylhydrazine propellants and greater than 335 seconds with nitrogen tetroxide and hydrazine. The secondary goal of the project is to take greater advantage of the high temperature capabilities of iridium/rhenium chambers. In order to achieve these goals, the propellant feed pressures were increased to 400 psia, nominal, which in turn increased the chamber pressure and temperature, allowing for higher c*. The tests article used a 24-on-24 unlike doublet injector design coupled with a copper heat sink chamber to simulate a flight configuration combustion chamber. The injector is designed to produce a nominal 200 lbf of thrust with a specific impulse of 335 seconds (using hydrazine fuel). Effect of Chamber length on engine C* performance was evaluated with the use of modular, bolt-together test hardware and removable chamber inserts. Multiple short duration firings were performed to characterize injector performance across a range of thrust levels, 180 to 220 lbf, and mixture ratios, from 1.1 to 1.3. During firing, ignition transient, chamber pressure, and various temperatures were measured in order to evaluate the performance of the engine and characterize the thermal conditions. The tests successfully demonstrated the stable operation and performance potential of a full scale engine with a measured c* of XXXX ft/sec (XXXX m/s) under nominal operational conditions.

Orbital Maneuvering system design evolution

NASA Technical Reports Server (NTRS)

Gibson, C.; Humphries, C.

1985-01-01

Preliminary design considerations and changes made in the baseline space shuttle orbital maneuvering system (OMS) to reduce cost and weight are detailed. The definition of initial subsystem requirements, trade studies, and design approaches are considered. Design features of the engine, its injector, combustion chamber, nozzle extension and bipropellant valve are illustrated and discussed. The current OMS consists of two identical pods that use nitrogen tetroxide (NTO) and monomethylhydrazine (MMH) propellants to provide 1000 ft/sec of delta velocity for a payload of 65,000 pounds. Major systems are pressurant gas storage and control, propellant storage supply and quantity measurement, and the rocket engine, which includes a bipropellant valve, an injector/thrust chamber, and a nozzle. The subsystem provides orbit insertion, circularization, and on orbit and deorbit capability for the shuttle orbiter.

Development and performance evaluation of air fine bubbles on water quality of thai catfish rearing

NASA Astrophysics Data System (ADS)

Subhan, Ujang; Muthukannan, Vanitha; Azhary, Sundoro Yoga; Mulhadi, Muhammad Fakhri; Rochima, Emma; Panatarani, Camellia; Joni, I. Made

2018-02-01

The efficiency and productivity of aquaculture strongly depends on the development of advanced technology for water quality management system. The most important factor for the success of intensive aquaculture system is controlling the water quality of fish rearing media. This paper reports the design of fine bubbles (FBs) generator and performance evaluation of the system to improve water quality in thai catfish media (10 g/ind) with density (16.66 ind./L). The FBs generator was designed to control the size distribution of bubble by controlling its air flow rate entry to the mixing chamber of the generator. The performance of the system was evaluated based on the produced debit, dissolved oxygen rate and ammonia content in the catfish medium. The size distribution was observed by using a high speed camera image followed by processing using ImageJ. freeware application. The results show that air flow rate 0.05 L/min and 0.1 L/min received average bubble size of 29 µm and 31 µm respectively. The generator produced bubbles with capacity of 6 L/min and dissolved oxygen rate 0.2 ppm/min/L. The obtained DO growth was 0.455 ppm/second/L while the average decay rate was 0.20 ppm/second/L. (0.011/0.005 fold). In contrast, the recieved DO growth rate is faster compared to the DO consumption rate of the Thai catfish. This results indicated that the potential application of FBs enhanced the density of thai catfish seed rearing. In addition, ammonia can be reduced at 0.0358 ppm/hour/L and it is also observed that the inhibition of bacterial growth of air FBs is postive to Aeromonas hydrophila bacteria compared to the negative control. It is concluded that as-developed FBs system can be potentially applied for intensive thai catfish culture and expected to improve the feeding efficiency rate.

Design and Predictions for High-Altitude (Low Reynolds Number) Aerodynamic Flight Experiment

NASA Technical Reports Server (NTRS)

Greer, Donald; Harmory, Phil; Krake, Keith; Drela, Mark

2000-01-01

A sailplane being developed at NASA Dryden Flight Research Center will support a high-altitude flight experiment. The experiment will measure the performance parameters or an airfoil at high altitudes (70,000 - 100,000 ft), low Reynolds numbers (2 x 10(exp 5) - 7 x 10(exp 5)), and high subsonic Mach numbers (0.5 and 0.65). The airfoil section lift and drag are determined from pilot and static pressure measurements. The locations of the separation bubble, Tollmien-Schlichting boundary-layer instability frequencies, and vortex shedding are measured from a hot-film strip. The details of the planned flight experiment are presented as well as several predictions of the airfoil performance.

Complementary online aerosol mass spectrometry and offline FT-IR spectroscopy measurements: Prospects and challenges for the analysis of anthropogenic aerosol particle emissions

NASA Astrophysics Data System (ADS)

Faber, Peter; Drewnick, Frank; Bierl, Reinhard; Borrmann, Stephan

2017-10-01

The aerosol mass spectrometer (AMS) is well established in investigating highly time-resolved dynamics of submicron aerosol chemical composition including organic aerosol (OA). However, interpretation of mass spectra on molecular level is limited due to strong fragmentation of organic substances and potential reactions inside the AMS ion chamber. Results from complementary filter-based FT-IR absorption measurements were used to explain features in high-resolution AMS mass spectra of different types of OA (e.g. cooking OA, cigarette smoking OA, wood burning OA). Using this approach some AMS fragment ions were validated in this study as appropriate and rather specific markers for a certain class of organic compounds for all particle types under investigation. These markers can therefore be used to get deeper insights in the chemical composition of OA based on AMS mass spectra in upcoming studies. However, the specificity of other fragment ions such as C2H4O2+ (m/z 60.02114) remains ambiguous. In such cases, complementary FT-IR measurements allow the interpretation of highly time-resolved AMS mass spectra at the level of molecular functional groups. Furthermore, this study discusses the challenges in reducing inorganic interferences (e.g. from water and ammonium salts) in FT-IR spectra of atmospheric aerosols to decrease spectral uncertainties for better comparisons and, thus, to get more robust results.

Different Recovery Profiles of Coagulation Factors, Thrombin Generation, and Coagulation Function After Hemorrhagic Shock in Pigs

DTIC Science & Technology

2012-06-06

Different recovery profiles of coagulation factors, thrombin generation, and coagulation function after hemorrhagic shock in pigs Wenjun Z. Martini ...Defense. Address for reprints: Wenjun Z. Martini , PhD, The US Army Institute of Surgical Research, 3698 Chambers Pass, Ft. Sam Houston, San Antonio, TX...control number 1. REPORT DATE 01 SEP 2015 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Different recovery profiles of

Propulsion Requirements for Space-Station Erection

DTIC Science & Technology

1959-01-26

CUO%N2,Q+lO%NO) U-OETA ha-iktcnqewudb naifcoy Pevchloryi fluoride Ilydrazine hetsn tehiu wol eusaifcoy Chlorine Trifluoride tHydra~ine m*U- The third...thereby altering the enthalpy Probably the most widely used technique change of the reaction . The pressure also influ- for chamber-wall cooling is...a small amount of hydrazine is decomposed, 15 Btu/ft 2 -hr-degF for the heat-transfer coef- and the hot decomposition gases are passed ficient, and a

A Measurement of the Energy Spectra of Cosmic Rays from 20 to 1000 GeV Per Amu

NASA Technical Reports Server (NTRS)

Gregory, J. C.; Thoburn, C.; Smith, A. E.; Petruzzo, J. J., III; Austin, R. W.; Derrickson, J. H.; Parnell, T. A.; Masheder, M. R. W.; Fowler, P. H.

1997-01-01

The design features and operational performance from the test flight of the fourth generation of spherical geometry cosmic ray detectors developed at Bristol University (Bristol University Gas Scintillator 4 - BUGS-4) are presented. The flight from Ft. Sumner (NM) in Sept. 1993 was the premier flight of a large (1m radius) spherical drift chamber which also gave gas scintillation and Cerenkov signals. The combinations of this chamber with one gas and two solid Cerenkov radiators lead to a large aperture factor (4.5 m2sr), but low (approximately 3.5 g/sq cm) instrument mass over the energy sensitive range 1 to several hundred GeV/a. Moreover, one simple timing measurement determined the impact parameter which provided a trajectory (path length) correction for all detector elements. This innovative and efficient design will be of interest to experimental groups engaged in studies of energetic charged particles. Although there were technical problems on the flight, which were compounded by the total destruction of BUGS-4 by fire while landing in Oklahoma, there was a period of stable operation during which the instrument was exposed at float altitude (approximately 125,000 ft.) to high energy cosmic rays. We present the performance of the instrument as determined from the analysis of these data and an appraisal of its novel design features. Suggestions for design improvements in a future instrument are made.

An experimental tool to look in a magma chamber

NASA Astrophysics Data System (ADS)

Gonde, C.; Massare, D.; Bureau, H.; Martel, C.; Pichavant, M.; Clocchiatti, R.

2005-12-01

Understanding the physical and geochemical processes occurring in the volcanoes roots is one of the fundamental tasks of research in the experimental petrology community. This requires experimental tools able to create confining conditions appropriate for magma chambers and conduits. However, the characterization of some natural magmatic processes requires more than a blink experimental approach, to be rigorously studied. In some cases, the in situ approach is the only one issue, because it permits the observation of processes (crystallization of mineral phases, bubble growth.) and their kinetic studies. Here we present a powerful tool, a transparent internally heated autoclave. With this apparatus, pressures (up to 0.3 GPa) and temperatures (up to 900°C) appropriate for subvolcanic magma reservoirs can be obtained. Because it is equipped with transparent sapphire windows, either images or movies can be recorded during an experiment. The pressure medium is Argon, and heating is achieved by a W winding placed into the pressure vessel. Pressure and temperature are calibrated using both well known melting points (eg. salts, metals) and phase transitions (AgI), either at room temperature or at medium and high temperatures. During an experiment, the experimental charge is held between two thick windows of diamond, placed in the furnace cylinder. The experimental volume is about 1 mm3. The observation and numeric record are made along the horizontal axis, through the windows. This apparatus is currently used for studies of nucleation and growth of gas bubbles in a silicate melt. The first results will be presented at the meeting.

Presentation of an experimental method to induce in vitro ("organ chambers") respiratory acidosis and its effect on vascular reactivity.

PubMed

Nadai, Tales Rubens de; Silveira, Ana Paula Cassiano; Monteiro, Ariadne Santana e Neves; Campos, Debora Ribeiro; Carvalho, Marco Tulio Rezende de; Albuquerque, Agnes Afrodite Sumarelli; Celotto, Andrea Carla; Evora, Paulo Roberto Barbosa

2014-11-01

To create in vitro a model to generate acidosis by CO2 bubbling "organ chambers", which would be useful for researchers that aim to study the effects of acid-base disturbs on the endothelium-dependent vascular reactivity. Eighteen male Wistar rats (230-280 g) were housed, before the experiments, under standard laboratory conditions (12h light/dark cycle at 21°C), with free access to food and water. The protocol for promoting in vitro respiratory acidosis was carried out by bubbling increased concentrations of CO2. The target was to achieve an ideal way to decrease the pH gradually to a value of approximately 6.6.It was used, initially, a gas blender varying concentrations of the carbogenic mixture (95% O2 + 5% CO2) and pure CO2. 1) 100% CO2, pH variation very fast, pH minimum 6.0; 2) 90%CO2 pH variation bit slower, pH minimum 6.31; 3) 70%CO2, pH variation slower, pH minimum 6.32; 4) 50% CO2, pH variation slower, pH minimum 6:42; 5) 40 %CO2, Adequate record, pH minimum 6.61, and; 6) 30 %CO2 could not reach values below pH minimum 7.03. Based on these data the gas mixture (O2 60% + CO2 40%) was adopted. This gas mixture (O2 60% + CO2 40%) was effective in inducing respiratory acidosis at a speed that made, possible the recording of isometric force.

Impact of OH Heterogenous Oxidation on the Evolution of Brown Carbon Aerosol Optical Properties

NASA Astrophysics Data System (ADS)

Schnitzler, E.; Abbatt, J.

2017-12-01

The effects of varying relative humidity (RH) on the evolution of brown carbon (BrC) optical properties induced by heterogeneous OH oxidation were investigated in a series of photooxidation chamber experiments. A BrC surrogate was generated from aqueous 1,3-dihydroxybenzene (10 mM) and H2O2 (10 mM) exposed to >300 nm radiation, atomized, passed through a series of trace gas denuders, and injected into the chamber, which was conditioned to about 10 or 60% RH. Following aerosol injection, H2O2 was continuously bubbled into the chamber; an hour later, the chamber was irradiated with black-lights (UV-B) to produce OH. Before irradiation, aerosol absorption and scattering at 405 nm, measured using a photoacoustic spectrometer, decreased due only to deposition and dilution, and single scattering albedo (SSA) was relatively steady. In the presence of gas-phase OH, absorption first increased, despite continued particle losses, and SSA decreased. Subsequently, absorption decreased faster than scattering, and SSA increased uniformly. At 60% RH, colour enhancement, likely associated with functionalization, was greatest after only minutes of reaction. In contrast, at 10% RH, peak colour enhancement occurred after about two hours of reaction, indicating that the decrease in RH and the attendant increase in particle viscosity significantly impeded heterogeneous OH oxidation of the BrC surrogate.

Study of Electromagnetic Interactions in the MicroBooNE Liquid Argon Time Projection Chamber

NASA Astrophysics Data System (ADS)

Caratelli, David

This thesis presents results on the study of electromagnetic (EM) activity in the MicroBooNE Liquid Argon Time Projection Chamber (LArTPC) neutrino detector. The LArTPC detector technology provides bubble-chamber like information on neutrino interaction final states, necessary to perform precision measurements of neutrino oscillation parameters. Accelerator-based oscillation experiments heavily rely on the appearance channel numu → nu e to make such measurements. Identifying and reconstructing the energy of the outgoing electrons from such interactions is therefore crucial for their success. This work focuses on two sources of EM activity: Michel electrons in the 10-50 MeV energy range, and photons from pi 0 decay in the ˜30-300 MeV range. Studies of biases in the energy reconstruction measurement, and energy resolution are performed. The impact of shower topology at different energies is discussed, and the importance of thresholding and other reconstruction effects on producing an asymmetric and biased energy measurement are highlighted. This work further presents a study of the calorimetric separation of electrons and photons with a focus on the shower energy dependence of the separation power.

Study of Electromagnetic Interactions in the MicroBooNE Liquid Argon Time Projection Chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caratelli, David

This thesis presents results on the study of electromagnetic (EM) activity in the MicroBooNE Liquid Argon Time Projection Chamber (LArTPC) neutrino detector. The LArTPC detector technology provides bubble-chamber like information on neutrino interaction final states, necessary to perform precision measurements of neutrino oscillation parameters. Accelerator-based oscillation experiments heavily rely on the appearance channel ! e to make such measurements. Identifying and reconstructing the energy of the outgoing electrons from such interactions is therefore crucial for their success. This work focuses on two sources of EM activity: Michel electrons in the 10-50 MeV energy range, and photons from 0 decay inmore » the 30-300 MeV range. Studies of biases in the energy reconstruction measurement, and energy resolution are performed. The impact of shower topology at different energies is discussed, and the importance of thresholding and other reconstruction effects on producing an asymmetric and biased energy measurement are highlighted. This work further presents a study of the calorimetric separation of electrons and photons with a focus on the shower energy dependence of the separation power.« less

Ultrasonic atomization of liquids in drop-chain acoustic fountains

PubMed Central

Simon, Julianna C.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Crum, Lawrence A.; Bailey, Michael R.

2015-01-01

When focused ultrasound waves of moderate intensity in liquid encounter an air interface, a chain of drops emerges from the liquid surface to form what is known as a drop-chain fountain. Atomization, or the emission of micro-droplets, occurs when the acoustic intensity exceeds a liquid-dependent threshold. While the cavitation-wave hypothesis, which states that atomization arises from a combination of capillary-wave instabilities and cavitation bubble oscillations, is currently the most accepted theory of atomization, more data on the roles of cavitation, capillary waves, and even heat deposition or boiling would be valuable. In this paper, we experimentally test whether bubbles are a significant mechanism of atomization in drop-chain fountains. High-speed photography was used to observe the formation and atomization of drop-chain fountains composed of water and other liquids. For a range of ultrasonic frequencies and liquid sound speeds, it was found that the drop diameters approximately equalled the ultrasonic wavelengths. When water was exchanged for other liquids, it was observed that the atomization threshold increased with shear viscosity. Upon heating water, it was found that the time to commence atomization decreased with increasing temperature. Finally, water was atomized in an overpressure chamber where it was found that atomization was significantly diminished when the static pressure was increased. These results indicate that bubbles, generated by either acoustic cavitation or boiling, contribute significantly to atomization in the drop-chain fountain. PMID:25977591

Temperature-gradient-induced

NASA Astrophysics Data System (ADS)

Park, Cheol; Glaser, Matt; Maclennan, Joe; Clark, Noel; Trittel, Torsten; Stannarius, Ralf

Freely-suspended smectic films of sub-micrometer thickness and lateral extensions of several millimeters were used to study thermally driven migration and convection in the film plane. Film experiments were performed during the 6 minute microgravity phase of a TEXUS suborbital rocket flight (Texus 52, launched April 27, 2015). We have found an attraction of the smectic material towards the cold edge of the film in a temperature gradient, similar to the Soret effect. This process is reversed when this edge is heated up again. Thermal convection driven by two thermocontacts in the film is practically absent, even at temperature gradients up to 10 K/mm, with thermally driven convection only setting in when the hot post reaches the transition temperature to the nematic phase. The Observation and Analysis of Smectic Islands in Space (OASIS) flight hardware was launched on SpaceX-6 in April 2015 and experiments on smectic bubbles were carried out on the International Space Station using four different smectic A and C liquid crystal materials in separate sample chambers. We observed that smectic islands on the surface of the bubbles migrated towards the colder part of the bubble in a temperature gradient. This work was supported by NASA Grant No. NNX-13AQ81G, by the Soft Materials Research Center under NSF MRSEC Grants No. DMR-0820579 and No. DMR-1420736, and by DLR Grants 50WM1127 and 50WM1430.

Comparison of three different prehospital wrapping methods for preventing hypothermia - a crossover study in humans

PubMed Central

2011-01-01

Background Accidental hypothermia increases mortality and morbidity in trauma patients. Various methods for insulating and wrapping hypothermic patients are used worldwide. The aim of this study was to compare the thermal insulating effects and comfort of bubble wrap, ambulance blankets / quilts, and Hibler's method, a low-cost method combining a plastic outer layer with an insulating layer. Methods Eight volunteers were dressed in moistened clothing, exposed to a cold and windy environment then wrapped using one of the three different insulation methods in random order on three different days. They were rested quietly on their back for 60 minutes in a cold climatic chamber. Skin temperature, rectal temperature, oxygen consumption were measured, and metabolic heat production was calculated. A questionnaire was used for a subjective evaluation of comfort, thermal sensation, and shivering. Results Skin temperature was significantly higher 15 minutes after wrapping using Hibler's method compared with wrapping with ambulance blankets / quilts or bubble wrap. There were no differences in core temperature between the three insulating methods. The subjects reported more shivering, they felt colder, were more uncomfortable, and had an increased heat production when using bubble wrap compared with the other two methods. Hibler's method was the volunteers preferred method for preventing hypothermia. Bubble wrap was the least effective insulating method, and seemed to require significantly higher heat production to compensate for increased heat loss. Conclusions This study demonstrated that a combination of vapour tight layer and an additional dry insulating layer (Hibler's method) is the most efficient wrapping method to prevent heat loss, as shown by increased skin temperatures, lower metabolic rate and better thermal comfort. This should then be the method of choice when wrapping a wet patient at risk of developing hypothermia in prehospital environments. PMID:21699720

A Fiber-Optic Probe Design for Combustion Chamber Flame Detection Applications-Design Criteria, Performance Specifications, and Fabrication Technique

NASA Technical Reports Server (NTRS)

Borg, Stephen E.; Harper, Samuel E.

2001-01-01

This paper documents the design and development of the fiber-optic probes utilized in the flame detection systems used in NASA Langley Research Center's 8-Foot High Temperature Tunnel (8-ft HTT). Two independent flame detection systems are utilized to monitor the presence and stability of the main-burner and pilot-level flames during facility operation. Due to the harsh environment within the combustor, the successful development of a rugged and efficient fiber-optic probe was a critical milestone in the development of these flame detection systems. The final optical probe design for the two flame detection systems resulted from research that was conducted in Langley's 7-in High Temperature Pilot Tunnel (7-in HTT). A detailed description of the manufacturing process behind the optical probes used in the 8-ft HTT is provided in Appendix A of this report.

Subjective and objective convergence of the eyes at simulated altitude of 18,000 feet preceded by short-term exposure to heat stress.

PubMed

Sinha, Biswajit; Dubey, D K

2014-01-01

Armed forces personnel including military aviators are quite often exposed concurrently to various environmental stressors like high environmental temperature and hypoxia. Literatures have suggested that exposure to one environmental stressor may modify the physiological response on subsequent exposure to same or different stressor. The present study was undertaken to investigate the impact of cross tolerance between two environmental stressors of aviation (heat and hypoxia) in ten healthy adult males in a simulated altitude chamber in a within subject experimental study. They were assessed for their convergence ability of the eyes at ground and at simulated altitude of 18,000 ft with or without pre-exposure to heat stress. Subjective convergence at simulated altitude of 18,000 ft did not show any improvement following pre-exposure to heat stress. Objective convergence was improved following pre-exposure to heat stress and was found to be 10.76 cm and 9.10 cm without and with heat stress respectively at simulated altitude of 18,000 ft. Improved objective convergence at high altitude as a result of pre-exposure to heat stress is indicative of better ocular functions. This might benefit aviators while flying at hypoxic condition.

Development of attrition resistant iron-based Fischer-Tropsch catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2000-09-20

The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H{sub 2}) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. The use of iron-based catalysts is attractive not only due to their low cost and ready availability, but also due to their high water-gas shift activity which makes it possible to use these catalysts with low H{sub 2}/CO ratios. However, a serious problem with use ofmore » Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, makes the separation of catalyst from the oil/wax product very difficult if not impossible, and results a steady loss of catalyst from the reactor. The objective of this research is to develop robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry bubble column reactor. Specifically we aim to develop to: (1) improve the performance and preparation procedure of the high activity, high attrition resistant, high alpha iron-based catalysts synthesized at Hampton University (2) seek improvements in the catalyst performance through variations in process conditions, pretreatment procedures and/or modifications in catalyst preparation steps and (3) investigate the performance in a slurry reactor. The effort during the reporting period has been devoted to effects of pretreating procedures, using H{sub 2}, CO and syngas (H{sub 2}/CO = 0.67) as reductants, on the performance (activity, selectivity and stability with time) of a precipitated iron catalyst (100Fe/5Cu/4.2K/10SiO{sub 2} on a mass basis ) during F-T synthesis were studied in a fixed-bed reactor.« less

Dynamical Behavior of Discrete Bubble and Heat Transfer of Nucleate Pool Boiling in Short-Term Microgravity

NASA Astrophysics Data System (ADS)

Zhao, Jian-Fu

2012-07-01

Boiling in microgravity is an increasing significant subject of investigation. Motivation for the study comes not only from many potential space applications due to its high efficiency to transfer high heat flux with liquid-vapor phase change, but also from powerful platform of microgravity to reveal the mechanism of heat transfer underneath the phenomenon of boiling. In the present paper, the growth of a discrete bubble during nucleate pool boiling and heat transfer in short-term microgravity is studied experimentally utilizing the drop tower Beijing. A P-doped N-type square silicon chip with the dimensions of 10x10x0.5 mm ^{3} was used as the heater. Two 0.25-mm diameters copper wires for power supply was soldered to the side surfaces of the chip at the opposite ends. The normal resistant of the chip is 75 Ω. The chip was heated by using Joule effect. A D.C. power supply of constant current was used to input energy to the heater element. A 0.12-mm diameter, T-type thermocouple adhered on the centre of the backside of the chip was used for the measurement of wall temperature, while two other T-type thermocouples were used for the bulk liquid temperature. FC-72 was used as working fluid. The concentration of air was determined by using Henry law as 0.0046 moles gas/mole liquid. The pressure and the bulk liquid temperature in the boiling chamber were nominally 102.0 kPa and 12.0 °C, respectively. The shapes of the bubbles were recorded using a high speed camera at a speed of 250 fps with a shutter speed of 1/2000 s. Based on the image manipulation, the effective diameter of the discrete bubble is obtained. The experiments were conducted utilizing the drop tower Beijing, which can provide a short-term microgravity condition. The residual gravity of 10 ^{-2 ... -3} g _{0} can be maintained throughout the short duration of 3.6 s. To avoid the influence of natural convection in normal gravity environment, the heating switched on at the release of the drop capsule. Moreover, careful choice of the experimental parameters was made to keep the boiling delay time, namely the duration from the beginning of heating to that of steady boiling, no more than 3.0 s. A typical growth of discrete bubble was observed with the heating current of 0.33 A. A discrete bubble appeared at the center of heater surface at 0.644 s after the heating current switched on. It grew gradually at first, and then stayed constantly, even decreases. Finally, it coalesced with other bubbles, and formed a larger coalesced bubble at 0.944 s. It is found that the bubble effective diameter is proportional to the square root of the time at the first stage, which is consistent with the bubble growth model based on classical thermal-controlled mechanism. The proportional coefficient is estimates as 5.6, which is located inside the range reported in the literature, indicating that gravity has a much slight influence on the early period of bubble growth. Large bubble size in microgravity, however, can provide much accurate measurement.

Slug Flow Analysis in Vertical Large Diameter Pipes

NASA Astrophysics Data System (ADS)

Roullier, David

The existence of slug flow in vertical co-current two-phase flow is studied experimentally and theoretically. The existence of slug flow in vertical direction implies the presence of Taylor bubbles separated by hydraulically sealed liquid slugs. Previous experimental studies such as Ombere-Ayari and Azzopardi (2007) showed the evidence of the non-existence of Taylor bubbles for extensive experimental conditions. Models developed to predict experimental behavior [Kocamustafaogullari et al. (1984), Jayanti and Hewitt. (1990) and Kjoolas et al. (2017)] suggest that Taylor bubbles may disappear at large diameters and high velocities. A 73-ft tall and 101.6-mm internal diameter test facility was used to conduct the experiments allowing holdup and pressure drop measurements at large L/D. Superficial liquid and gas velocities varied from 0.05-m/s to 0.2 m/s and 0.07 m/s to 7.5 m/s, respectively. Test section pressure varied from 38 psia to 84 psia. Gas compressibility effect was greatly reduced at 84 psia. The experimental program allowed to observe the flow patterns for flowing conditions near critical conditions predicted by previous models (air-water, 1016 mm ID, low mixture velocities). Flow patterns were observed in detail using wire-mesh sensor measurements. Slug-flow was observed for a narrow range of experimental conditions at low velocities. Churn-slug and churn-annular flows were observed for most of the experimental data-points. Cap-bubble flow was observed instead of bubbly flow at low vSg. Wire-mesh measurements showed that the liquid has a tendency to remain near to the walls. The standard deviation of radial holdup profile correlates to the flow pattern observed. For churn-slug flow, the profile is convex with a single maximum near the pipe center while it exhibits a concave shape with two symmetric maxima close to the wall for churn-annular flow. The translational velocity was measured by two consecutive wire-mesh sensor crosscorrelation. The results show linear trends at low mixture velocities and non-linear behaviors at high mixture velocities. The translational velocity trends seem to be related to the flow-pattern observed, namely to the ability of the gas to flow through the liquid structures. A simplified Taylor bubble stability model is proposed. The model allows to estimate under which conditions Taylor bubbles disappear, properly accounting for the diameter effect and velocity effect observed experimentally. In addition, annular flow distribution coefficient relating true holdup to centerline holdup in vertical flow is proposed. The proposed coefficient defines the tendency of the liquid to remain near the walls. This coefficient increases linearly with the void fraction.

An Annotated Bibliography of Hypobaric Decompression Sickness Research Conducted at the Crew Technology Division, USAF School of Aerospace Medicine, Brooks AFB, Texas from 1983 to 1988

DTIC Science & Technology

1990-06-01

AN ANNOTATED BIBLIOGRAPHY OF HYPOBARIC DECOMPRESSION SICKNESS RESEARCH CONDUCTED AT THE CREW TECHNOLOGY DIVISION, USAF SCHOOL OF AEROSPACE MEDICINE...190 man-flights to four selected altitudes (30000, 27500, 25000, and 22500 ft pressure equivalent) in a hypobaric chamber. The subjects’ ages ranged...conditions and two of these developed delayed sy~rtcms. Three of these five subjects underwent hyperbaric oxygen treatment. Conclusion. Female subjects

Residual herbicide study on selected Hanford Site roadsides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, J.L.; Kemp, C.J.; Sackschewsky, M.R.

Westinghouse Hanford Company routinely treats roadsides with herbicides to control undesirable plant growth. An experiment was conducted to test perennial grass germination in soils adjacent to roadways of the Hanford Site. The primary variable was the distance from the roadside. A simple germination test was executed in a controlled-environment chamber to determine the residual effects of these applications. As expected, the greatest herbicide activity was found directly adjacent to the roadway, approximately 0 to 20 ft (0 to 6.3 m) from the roadway.

Results of Tests Performed on the Acoustic Quiet Flow Facility Three-Dimensional Model Tunnel

NASA Technical Reports Server (NTRS)

Barna, P. S.

1995-01-01

The test results briefly described in this report were obtained on the three-dimensional 1:48 scale tunnel modeled on the design proposed by Messrs. D.S.M.A. Corporation. More particularly, while the test chamber dimensions were indeed scaled down in the ration of 1:48, including the contraction and the collector as well, the duct system itself leading to and from the chamber was adapted to suit laboratory conditions and space limitations. Earlier tests with the two-dimensional model showed that blowing mode was preferred as against the suction mode, hence all tests were performed with blowing only. At the exit of the contraction the maximum airspeed attained with the 1 HP blower unit was about 200 ft/sec. This airspeed may be increased in future if desired. The test results show that pressure recovery in the diffuser was about 34 percent due to the large blockage at its entrance. Velocity traverses taken across the diffuser entrance explain the reason for this blockage. Recirculation, studied with both, hot-wire anemometry and flow-visualization techniques, was largely affected by the design of the test chamber itself and the amount of vent-air admitted to the chamber. Vent-air helped to decrease the level of turbulence.

Spin alignment of ρ0 mesons produced in antineutrino and neutrino neon charged-current interactions

NASA Astrophysics Data System (ADS)

Wittek, W.; Guy, J.; Adeholz, M.; Allport, P.; Baton, J. P.; Berggren, M.; Bertrand, D.; Brisson, V.; Bullock, F. W.; Burkot, W.; Calicchio, M.; Clayton, E. F.; Coghen, T.; Cooper-Sarkar, A. M.; Erriquez, O.; Fitch, P. J.; Fogli-Muciaccia, M. T.; Hulth, P. O.; Jones, G. T.; Kasper, P.; Klein, H.; Marage, P.; Middleton, R. P.; Miller, D. B.; Mobayyen, M. M.; Morrison, D. R. O.; Neveu, M.; O'Neale, S. W.; Parker, M. A.; Petiau, P.; Sacton, J.; Sansum, R. A.; Schmitz, N.; Simopoulou, E.; Vallee, C.; Varvell, K.; Vayaki, A.; Venus, W.; Wachsmuth, H.; Wells, J.

1987-03-01

In a bubble chamber experiment with BEBC the spin alignment parameter η=1/2 (2ϱ00 - ϱ11 - ϱ-1-1) is measured for ϱ0 mesons produced in deep inelastic charged-current antineutrino and neutrono interactions on neon. In the current fragmentation region η is found to be ηv=0.48+/-0.27 (stat.)+/-0.15 (syst.) for vNe and ηv=0.12+/-0.20 (stat.)+/-0.10 (syst.) for vNe interactions Present address: University College London, London WC1E 6BT, UK.

Neutral strange particle production in antineutrino-neon charged current interactions

NASA Astrophysics Data System (ADS)

Willocq, S.; Marage, P.; Aderholz, M.; Allport, P.; Baton, J. P.; Berggren, M.; Clayton, E. F.; Cooper-Sarkar, A. M.; Erriquez, O.; Faulkner, P. J. W.; Guy, J.; Hulth, P. O.; Jones, G. T.; Mobayyen, M. M.; Morrison, D. R. O.; Neveu, M.; O'Neale, S.; Sacton, J.; Sansum, R. A.; Varvell, K.; Venus, W.; Wells, J.; Wittek, W.

1992-06-01

Neutral strange particle production inbar v Ne charged current interactions is studied using the bubble chamber BEBC, exposed to the CERN SPS antineutrino wide band beam. From a sample of 1191 neutral strange particles, the inclusive production rates are determined to be (15.7±0.8)% for K 0 mesons, (8.2±0.5)% for Λ, (0.4±0.2)% forbar Λ and (0.6±0.3)% for Σ0 hyperons. The inclusive production properties of K 0 mesons and Λ hyperons are investigated. The Λ hyperons are found to be polarized in the production plane.

MEASURING PROJECTOR

DOEpatents

Franck, J.V.; Broadhead, P.S.; Skiff, E.W.

1959-07-14

A semiautomatic measuring projector particularly adapted for measurement of the coordinates of photographic images of particle tracks as prcduced in a bubble or cloud chamber is presented. A viewing screen aids the operator in selecting a particle track for measurement. After approximate manual alignment, an image scanning system coupled to a servo control provides automatic exact alignment of a track image with a reference point. The apparatus can follow along a track with a continuous motion while recording coordinate data at various selected points along the track. The coordinate data is recorded on punched cards for subsequent computer calculation of particle trajectory, momentum, etc.

Stability test and analysis of the Space Shuttle Primary Reaction Control Subsystem thruster

NASA Technical Reports Server (NTRS)

Applewhite, John; Hurlbert, Eric; Krohn, Douglas; Arndt, Scott; Clark, Robert

1992-01-01

The results are reported of a test program conducted on the Space Shuttle Primary Reaction Control Subsystem thruster in order to investigate the effects of trapped helium bubbles and saturated propellants on stability, determine if thruster-to-thruster stability variations are significant, and determine stability under STS-representative conditions. It is concluded that the thruster design is highly reliable in flight and that burn-through has not occurred. Significantly unstable thrusters are screened out, and wire wrap is found to protect against chamber burn-throughs and to provide a fail-safe thruster for this situation.

ATTRITION RESISTANT IRON-BASED FISCHER-TROPSCH CATALYSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

JAMES G. GOODWIN, JR.; JAMES J. SPIVEY; K. JOTHIMURUGESAN

1998-09-17

The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H{sub 2}) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. Iron-based (Fe) catalysts are preferred catalysts for F-T when using low CO/H{sub 2} ratio synthesis gases derived from modern coal gasifiers. This is because in addition to reasonable F-T activity, the F-T catalysts also possess high water gas shift (WGS) activity. However, a serious problem withmore » the use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, making the separation of catalyst from the oil/wax product very difficult if not impossible, and results in a steady loss of catalyst from the reactor. The objectives of this research are to develop a better understanding of the parameters affecting attrition resistance of Fe F-T catalysts suitable for use in SBCRs and to incorporate this understanding into the design of novel Fe catalysts having superior attrition resistance. Catalyst preparations will be based on the use of spray drying and will be scalable using commercially available equipment. The research will employ among other measurements, attrition testing and F-T synthesis, including long duration slurry reactor runs in order to ascertain the degree of success of the various preparations. The goal is to develop an Fe catalyst which can be used in a SBCR having only an internal filter for separation of the catalyst from the liquid product, without sacrificing F-T activity and selectivity. The effect of silica addition via coprecipitation and as a binder to a doubly promoted Fischer-Tropsch synthesis iron catalyst (100 Fe/5 Cu/4.2 K) was studied. The catalysts were prepared by coprecipitation, followed by binder addition and drying in a 1 m diameter, 2 m tall spray dryer. The binder silica content was varied from 0 to 20 wt %. A catalyst with 12 wt % binder silica was found to have the highest attrition resistance. F-T reaction studies over 100 hours in a fixed-bed reactor showed that this catalyst maintained around 95 % CO conversion with a methane selectivity of less than 7 wt % and a C{sub 5}{sup +} selectivity of greater than 73 wt %. The effect of adding precipitated silica from 0 to 20 parts by weight to this catalyst (containing 12 wt % binder silica) was also studied. Addition of precipitated silica was found to be detrimental to attrition resistance and resulted in increased methane and reduced wax formation.« less

Transpiring Cooling of a Scram-Jet Engine Combustion Chamber

NASA Technical Reports Server (NTRS)

Choi, Sang H.; Scotti, Stephen J.; Song, Kyo D.; Ries,Heidi

1997-01-01

The peak cold-wall heating rate generated in a combustion chamber of a scram-jet engine can exceed 2000 Btu/sq ft sec (approx. 2344 W/sq cm). Therefore, a very effective heat dissipation mechanism is required to sustain such a high heating load. This research focused on the transpiration cooling mechanism that appears to be a promising approach to remove a large amount of heat from the engine wall. The transpiration cooling mechanism has two aspects. First, initial computations suggest that there is a reduction, as much as 75%, in the heat flux incident on the combustion chamber wall due to the transpirant modifying the combustor boundary layer. Secondly, the heat reaching the combustor wall is removed from the structure in a very effective manner by the transpirant. It is the second of these two mechanisms that is investigated experimentally in the subject paper. A transpiration cooling experiment using a radiant heating method, that provided a heat flux as high as 200 Btu/sq ft sec ( approx. 234 W/sq cm) on the surface of a specimen, was performed. The experiment utilized an arc-lamp facility (60-kW radiant power output) to provide a uniform heat flux to a test specimen. For safety reasons, helium gas was used as the transpirant in the experiments. The specimens were 1.9-cm diameter sintered, powdered-stainless-steel tubes of various porosities and a 2.54cm square tube with perforated multi-layered walls. A 15-cm portion of each specimen was heated. The cooling effectivenes and efficiencies by transpiration for each specimen were obtained using the experimental results. During the testing, various test specimens displayed a choking phenomenon in which the transpirant flow was limited as the heat flux was increased. The paper includes a preliminary analysis of the transpiration cooling mechanism and a scaling conversion study that translates the results from helium tests into the case when a hydrogen medium is used.

Acceleration Techniques for Recombination of Gases in Electrolysis Microactuators with Nafion®-Coated Electrocatalyst

PubMed Central

Sheybani, Roya; Meng, Ellis

2015-01-01

Recombination of electrolysis gases (oxidation of hydrogen and reduction of oxygen) is an important factor in operation efficiency of devices employing electrolysis such as actuators and also unitized regenerative fuel cells. Several methods of improving recombination speed and repeatability were developed for application to electrolysis microactuators with Nafion®-coated catalytic electrodes. Decreasing the electrolysis chamber volume increased the speed, consistency, and repeatability of the gas recombination rate. To further improve recombination performance, methods to increase the catalyst surface area, hydrophobicity, and availability were developed and evaluated. Of these, including in the electrolyte pyrolyzed-Nafion®-coated Pt segments contained in the actuator chamber accelerated recombination by increasing the catalyst surface area and decreasing the gas transport diffusion path. This approach also reduced variability in recombination encountered under varying actuator orientation (resulting in differing catalyst/gas bubble proximity) and increased the rate of recombination by 2.3 times across all actuator orientations. Repeatability of complete recombination for different generated gas volumes was studied through cycling. PMID:26251561

Physics with gamma-beams and charged particle detectors: I) Nuclear structure II) Nuclear astrophysics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gai, Moshe

The Charged Particle Working Group (CPWG) is proposing to construct large area Silicon Strip Detector (SSD), a gas Time Projection Chamber detector read by an electronic readout system (eTPC) and a Bubble Chamber (BC) containing superheated high purity water to be used in measurements utilizing intense gamma-ray beams from the newly constructed ELI-NP facility at Magurele, Bucharest in Romania. We intend to use the SSD and eTPC detectors to address essential problems in nuclear structure physics, such as clustering and the many alpha-decay of light nuclei such as {sup 12}C and {sup 16}O. All three detectors (SSD, eTPC and BC)more » will be used to address central problems in nuclear astrophysics such as the astrophysical cross section factor of the {sup 12}C(α,γ) reaction and other processes central to stellar evolution. The CPWG intends to submit to the ELI-NP facility a Technical Design Report (TDR) for the proposed detectors.« less

High-Frequency Measurements of Methane Ebullition Over a Growing Season at a Temperate Peatland Site

NASA Technical Reports Server (NTRS)

Goodrich, Jordan P.; Varner, Ruth K.; Frolking, Steve; Duncan, Bryan N.; Crill, Patrick M.

2011-01-01

Bubbles can contribute a significant fraction of methane emissions fr om wetlands; however the range of reported fractions is very large an d accurate characterization of this pathway has proven difficult. Her e we show that continuous automated flux chambers combined with an in tegrated cavity output spectroscopy (ICOS) instrument allow us to qua ntify both CH4 ebullition rate and magnitude. For a temperate poor f en in 2009, ebullition rate varied on hourly to seasonal time scales. A diel pattern in ebullition was identified with peak release occurr ing between 20:00 and 06:00 local time, though steady fluxes (i.e., t hose with a linear increase in chamber headspace CH4 concentration) d id not exhibit diel variability. Seasonal mean ebullition rates peake d at 843.5 +/- 384.2 events m(exp -2)/d during the summer, with a me an magnitude of 0.19 mg CH4 released in each event.

New flavor production in. gamma. ,. mu. ,. nu. , and hadron beams. [Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wojcicki, S.

1980-01-01

During the last few years the main emphasis in the study of heavy particle production (mainly charm) by means other than e/sup +/e/sup -/ annihilation has been on the production mechanisms. This review concentrates mainly on the production data in ..gamma.., ..mu.., ..nu.., and hadron beams. The heavy flavor searches divide themselves naturally into three categories, each one characterized by its own peculiar advantages and shortcomings; these are summarized briefly. Then the following topics are taken up: charm production by hadrons (central production, forward production - ..lambda../sub c/ and D production, anomalies and discrepancies), charm production by photons and muons,more » new flavor production by neutrinos, status of heavier flavors, and production bound flavors (eta/sub c/ search, UPSILON muoproduction, J/psi and UPSILON hadroproduction, J/psi muoproduction). In his outlook for the future, the author presents a few words concerning the status of detectors: emulsions, high-resolution streamer chambers, high-resolution bubble chambers, and solid-state detectors. 83 references, 36 figures, 4 tables. (RWR)« less

DEVELOPMENT OF ATTRITION RESISTANT IRON-BASED FISCHER-TROPSCH CATALYSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adeyinka A. Adeyiga

2003-12-01

Fischer-Tropsch (FT) synthesis to convert syngas (CO + H{sub 2}) derived from natural gas or coal to liquid fuels and wax is a well-established technology. For low H{sub 2} to CO ratio syngas produced from CO{sub 2} reforming of natural gas or from gasification of coal, the use of Fe catalysts is attractive because of their high water gas shift activity in addition to their high FT activity. Fe catalysts are also attractive due to their low cost and low methane selectivity. Because of the highly exothermic nature of the FT reaction, there has been a recent move away frommore » fixed-bed reactors toward the development of slurry bubble column reactors (SBCRs) that employ 30 to 90 {micro}m catalyst particles suspended in a waxy liquid for efficient heat removal. However, the use of Fe FT catalysts in an SBCR has been problematic due to severe catalyst attrition resulting in fines that plug the filter employed to separate the catalyst from the waxy product. Fe catalysts can undergo attrition in SBCRs not only due to vigorous movement and collisions but also due to phase changes that occur during activation and reaction. The objectives of this research were to develop a better understanding of the parameters affecting attrition of Fe F-T catalysts suitable for use in SBCRs and to incorporate this understanding into the design of novel Fe catalysts having superior attrition resistance. The catalysts were prepared by co-precipitation, followed by binder addition and spray drying at 250 C in a 1 m diameter, 2 m tall spray dryer. The binder silica content was varied from 0 to 20 wt %. The results show that use of small amounts of precipitated SiO{sub 2} alone in spray-dried Fe catalysts can result in good attrition resistance. All catalysts investigated with SiO{sub 2} wt% {le} 12 produced fines less than 10 wt% during the jet cup attrition test, making them suitable for long-term use in a slurry bubble column reactor. Thus, concentration rather than type of SiO{sub 2} incorporated into catalyst has a more critical impact on catalyst attrition resistance of spray-dried Fe catalysts. Lower amounts of SiO{sub 2} added to a catalyst give higher particle densities and therefore higher attrition resistances. In order to produce a suitable SBCR catalyst, however, the amount of SiO{sub 2} added has to be optimized to provide adequate surface area, particle density, and attrition resistance. Two of the catalysts with precipitated and binder silica were tested in Texas A&M University's CSTR (Autoclave Engineers). Spray-dried catalysts with compositions 100 Fe/5 Cu/4.2 K/11 (P) SiO{sub 2} and 100 Fe/5 Cu/4.2 K/1.1 (B) SiO{sub 2} have excellent selectivity characteristics (low methane and high C{sub 5}{sup +} yields), but their productivity and stability (deactivation rate) need to be improved. Mechanical integrity (attrition strength) of these two catalysts was markedly dependent upon their morphological features. The attrition strength of the catalyst made out of largely spherical particles (1.1 (B) SiO{sub 2}) was considerably higher than that of the catalyst consisting of irregularly shaped particles (11 (P) SiO{sub 2}).« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, S.J.; Underwood, D.E.

A series of tests has been conducted to correlate the torque applied to the packing nut of 1-in. uranium hexafluoride (UF{sub 6}) cylinder valves versus the stem seal leak rate and material strain. The tests were initiated as a result of discussions held at the 1989 spring meeting of the American National Standards Institute (ANSI) N14.1 committee. The packing nut has been observed to fail due to stress corrosion cracking. The specified level of torque applied to the packing nut to seal the stem packing has been suspected to be a contributor to the failures. The ANSI standard specifies torquemore » of 120 to 150 ft-lb to compact the PTFE packing rings. One series of tests measured the effects of reduced levels of packing nut torque to the stem seal leak rate. The bubble leak rate of the stem was measured at ambient and 225{degree}F temperature with the body interior at 75 psig. Results from the laboratory tests indicate that the stem seal will perform acceptably through multiple thermal excursions at a torque level as low as 50 ft-lb. The second series of tests measured the effect of thermal expansion and increased hydrostatic force of the PTFE rings on the packing nut strain. The strain at certain exterior locations on a packing nut was measured at ambient and elevated temperatures for various assembly torques. The net increase in material strain is significant and is nearly equal at torque levels of 55, 85, and 115 ft-lb, being {minus}479, {minus}463, and {minus}469 {mu}in. respectively.« less

Identification of a dynamic temperature threshold for soil moisture freeze/thaw (F/T) state classification using soil real dielectric constant derivatives.

NASA Astrophysics Data System (ADS)

Pardo, R.; Berg, A. A.; Warland, J. S.

2017-12-01

The use of microwave remote sensing for surface ground ice detection has been well documented using both active and passive systems. Typical validation of these remotely sensed F/T state products relies on in-situ air or soil temperature measurements and a threshold of 0°C to identify frozen soil. However, in soil pores, the effects of capillary and adsorptive forces combine with the presence of dissolved salts to depress the freezing point. This is further confounded by the fact that water over this temperature range releases/absorbs latent heat of freezing/fusion. Indeed, recent results from SLAPEx2015, a campaign conducted to evaluate the ability to detect F/T state and examine the controls on F/T detection at multiple resolutions, suggest that using a soil temperature of 0°C as a threshold for freezing may not be appropriate. Coaxial impedance sensors, like Steven's HydraProbeII (HP), are the most widely used soil sensor in water supply forecast and climatological networks. These soil moisture probes have recently been used to validate remote sensing F/T products. This kind of validation is still relatively uncommon and dependent on categorical techniques based on seasonal reference states of frozen and non-frozen soil conditions. An experiment was conducted to identify the correlation between the phase state of the soil moisture and the probe measurements. Eight soil cores were subjected to F/T transitions in an environmental chamber. For each core, at a depth of 2.5 cm, the temperature and real dielectric constant (rdc) were measured every five minutes using HPs while two heat pulse probes captured the apparent heat capacity 24 minutes apart. Preliminary results show the phase transition of water is bounded by inflection points in the soil temperature, attributed to latent heat. The rdc, however, appears to be highly sensitive to changes in the water preceding the phase change. This opens the possibility of estimating a dynamic temperature threshold for soil F/T by identifying the soil temperatures at the times during which these inflection points in the soil rdc occur. This technique provides a more accurate threshold for F/T product than the static reference temperature currently established.

Identifying organic aerosol sources by comparing functional group composition in chamber and atmospheric particles

PubMed Central

Russell, Lynn M.; Bahadur, Ranjit; Ziemann, Paul J.

2011-01-01

Measurements of submicron particles by Fourier transform infrared spectroscopy in 14 campaigns in North America, Asia, South America, and Europe were used to identify characteristic organic functional group compositions of fuel combustion, terrestrial vegetation, and ocean bubble bursting sources, each of which often accounts for more than a third of organic mass (OM), and some of which is secondary organic aerosol (SOA) from gas-phase precursors. The majority of the OM consists of alkane, carboxylic acid, hydroxyl, and carbonyl groups. The organic functional groups formed from combustion and vegetation emissions are similar to the secondary products identified in chamber studies. The near absence of carbonyl groups in the observed SOA associated with combustion is consistent with alkane rather than aromatic precursors, and the absence of organonitrate groups can be explained by their hydrolysis in humid ambient conditions. The remote forest observations have ratios of carboxylic acid, organic hydroxyl, and nonacid carbonyl groups similar to those observed for isoprene and monoterpene chamber studies, but in biogenic aerosols transported downwind of urban areas the formation of esters replaces the acid and hydroxyl groups and leaves only nonacid carbonyl groups. The carbonyl groups in SOA associated with vegetation emissions provides striking evidence for the mechanism of esterification as the pathway for possible oligomerization reactions in the atmosphere. Forest fires include biogenic emissions that produce SOA with organic components similar to isoprene and monoterpene chamber studies, also resulting in nonacid carbonyl groups in SOA. PMID:21317360

Estimation of air-to-grass mass interception factors for iodine.

PubMed

Karunakara, N; Ujwal, P; Yashodhara, I; Sudeep Kumara, K; Mohan, M P; Bhaskar Shenoy, K; Geetha, P V; Dileep, B N; James, Joshi P; Ravi, P M

2018-06-01

Air-to-grass mass interception factors for radionuclide are important basic input parameter for the estimation of radiation dose to the public around a nuclear power plant. In this paper, we present the determination of air-to- grass mass interception factors for iodine using a 2 m × 2 m × 2 m (l × b × h) size environmental chamber. The temperature, humidity, and rainfall inside the environmental chamber was controlled to required values to simulate different environmental conditions. Grass (Pennisetum purpureum, Schum), grown in pots, was kept inside the environmental chamber and stable iodine in elemental form was sublimed quickly inside the chamber to simulate an accidental release of iodine to the environment. The concentration of iodine in the air was measured periodically by drawing air through a bubbling setup, containing 1% sodium carbonate solution. The mass interception factor for dry deposition varied in the range of 0.25-7.7 m 2  kg -1 with mean value of 2.2 m 2  kg -1 with respect to fresh weight of grass, and that due to wet deposition varied in the range of 0.6-4.8 m 2  kg -1 with mean value of 2.3 m 2  kg -1 . The mass interception factor was inversely correlated with the total iodine deposited through dry deposition as well as with the rainfall. Copyright © 2017. Published by Elsevier Ltd.

Effects of crystallization and bubble nucleation on the elastic properties of magmas

NASA Astrophysics Data System (ADS)

Tripoli, B. A.; Ulmer, P.; Eric, R.; Cordonnier, B.; Burg, J.

2012-12-01

Seismic tomography of potentially hazardous volcanoes is a prime tool to assess the physical state of magma reservoirs. Processes occurring in the conduit or in the chamber, such as crystallization and bubble exsolution, control the magma rheology, hence the style of volcanic eruption. Elastic parameters of vapor-saturated, partially molten systems are thus providing fundamental information for the identification of such reservoirs under active and seemingly dormant volcanoes. This knowledge will potentially serve to assess their risk. We present preliminary data on compression and shear wave propagation velocities of a chemically simplified melt analogous to andesite and trachyte, in the system CaO-Na2O-Al2O3-SiO2-H2O-CO2. These ultrasonic velocities are measured simultaneously in a Paterson-type internally-heated gas pressure apparatus at confining pressures up to 300 MPa and temperatures up to 1000°C. Using the pulse transmission technique, the experiments are performed at frequencies ranging from 0.1 to 3 MHz. Variations in the elastic parameters induced by the presence of bubbles or dissolved water in glassy samples are discussed for various pressures and temperatures. As the investigated melt undergoes plagioclase crystallization, a thermal plateau is maintained over specific time duration in order to measure the changes in seismic properties of in-situ crystallizing magmas. This maintained temperature varies between 800° and 1000°C depending on the amount of dissolved water in the system.

Analysis and Evaluation of German Attainments and Research in the Liquid Rocket Engine Field. Volume 4. Propellant Injectors

DTIC Science & Technology

1951-02-01

they were ob- served at a given pressure drop in "cold" testing with water or unreacted propellants. heat-transfer considerations and the location of... water as a coolant in the main chamber. The Winkler injector was used.on a test unit developing a thrust of 220 lb and an exhaust ve- locity of 6370 ft... water . Provision was made for an igniter in the center of the injector. The relatively high performance reported for this unit does not seem to be

New results obtained by the Rome data on {bar p}d annihilation at rest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaspero, M.

1994-10-01

The reanalysis of the {bar p}n annihilations at rest made using the Rome bubble-chamber data has shown a better way for writing the amplitude of the S{sub 0}(1390){pi}{sup {minus}} channel in the 2{pi}{sup +}3{pi}{sup {minus}} final state, has given a new evaluation of the {pi}{sup {minus}}{pi}{sup 0} and {pi}{sup {minus}}{omega} frequencies, and has found no evidence of the S{sub 0}(1390) decay into {omega}{omega} and K{sup 0}{bar K}{sup 0}{pi}{sup +}{pi}{sup {minus}}. 14 refs., 4 figs., 1 tab.

Cloud physics laboratory project science and applications working group

NASA Technical Reports Server (NTRS)

Hung, R. J.

1977-01-01

The conditions of the expansion chamber under zero gravity environment were simulated. The following three branches of fluid mechanics simulation under low gravity environment were accomplished: (1) oscillation of the water droplet which characterizes the nuclear oscillation in nuclear physics, bubble oscillation of two phase flow in chemical engineering, and water drop oscillation in meteorology; (2) rotation of the droplet which characterizes nuclear fission in nuclear physics, formation of binary stars and rotating stars in astrophysics, and breakup of the water droplet in meteorology; and (3) collision and coalescence of the water droplets which characterizes nuclear fusion in nuclear physics and processes of rain formation in meteorology.

Investigations of flowfields found in typical combustor geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.; Mclaughlin, D. K.

1981-01-01

The flowfields of gas turbine combustion chambers were investigated. Six flowfield configurations with sidewall angles alpha = 90 and 45 deg. and swirl vane angles phi = 0, 45 and 70 deg. are characterized. Photography of neutrally-buoyant helium-filled soap bubbles, tufts, and injected smoke helps to characterize the time-mean streamlines, recirculation zones and regions of highly turbulent flow. Five-hole pitot probe pressure measurements allow the determination of time-mean velocities u, v and w. An advanced computer code equipped with a standard two-equation kappa-epsilon turbulence model was used to predict corresponding flow situations and to compare results with the experimental data.

Reaction. pi. /sup -/p. --> pi. /sup -/. pi. /sup +/. pi. /sup -/p at 8 GeV/c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitagaki, T.; Tanaka, S.; Yuta, H.

1982-10-01

Results from a high-statistics experiment involving an exposure of the SLAC 82-in. hydrogen bubble chamber to a beam of 8-GeV/c ..pi../sup -/ yielding a final state of ..pi../sup -/..pi../sup +/..pi../sup -/p are presented. Copious production of rho, ..delta../sup + +/, and f is found. Considerable quasi-two-body production in which one particle decays to one of the above resonances is also observed. Some double-resonance production involving baryon and meson resonances is also seen. The production properties of rho, ..delta../sup + +/, and f mesons are well described by a double-Regge model.

Measurement of Charged Pions from Neutrino-produced Nuclear Resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simon, Clifford N.

2014-01-01

A method for identifying stopped pions in a high-resolution scintillator bar detector is presented. I apply my technique to measure the axial mass M Δ Afor production of the Δ(1232) resonance by neutrino, with the result M Δ A = 1.16±0.20 GeV (68% CL) (limited by statistics). The result is produced from the measured spectrum of reconstructed momentum-transfer Q 2. I proceed by varying the value of M Δ A in a Rein-Sehgal-based Monte Carlo to produce the best agreement, using shape only (not normalization). The consistency of this result with recent reanalyses of previous bubble-chamber experiments is discussed.

The Parity of the Neutral Pion and the Decay pi{sup 0} Yields 2e{sup +} + 2e{sup -}

DOE R&D Accomplishments Database

Samios, N. P.; Plano, R.; Prodell, A.; Schwartz, M.; Steinberger, J.

1962-01-01

Two hundred and six electronic decays of the pi{sup 0}, pi{sup 0} yields e{sup +} + e{sup -} + e{sup +} + e{sup -}, were observed in a hydrogen bubble chamber. The decay distributions of the electron pairs and the total rate for this process are shown to be in good agreement with theory. An examination of correlations of the e{sup +}e{sup -} pair decay planes on the basis of electrodynamic predictions is in agreement with the hypothesis that the pi{sup 0} is pseudoscalar, but disagrees for scalar pions by 3.6 standard deviations. (auth)

Formation of a narrow baryon resonance with positive strangeness in K{sup +} collisions with Xe nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barmin, V. V.; Asratyan, A. E.; Borisov, V. S.

2010-07-15

The data on the charge-exchange reaction K{sup +}Xe {sup {yields}}K{sup 0}pXe', obtained with the bubble chamber DIANA, are reanalyzed using increased statistics and updated selections. Our previous evidence for formation of a narrow pK{sup 0} resonance with mass near 1538 MeV is confirmed. The statistical significance of the signal reaches some 8{sigma} (6{sigma}) standard deviations when estimated as S/{radical}B (S/{radical}B + S. The mass and intrinsic width of the {Theta}{sup +} baryon are measured as m = 1538 {+-} 2 MeV and {Gamma} = 0.39 {+-} 0.10 MeV.

Airborne measurements of cloud forming nuclei and aerosol particles at Kennedy Space Center, Florida

NASA Technical Reports Server (NTRS)

Radke, L. F.; Langer, G.; Hindman, E. E., II

1978-01-01

Results of airborne measurements of the sizes and concentrations of aerosol particles, ice nuclei, and cloud condensation nuclei that were taken at Kennedy Space Center, Florida, are presented along with a detailed description of the instrumentation and measuring capabilities of the University of Washington airborne measuring facility (Douglas B-23). Airborne measurements made at Ft. Collins, Colorado, and Little Rock, Arkansas, during the ferry of the B-23 are presented. The particle concentrations differed significantly between the clean air over Ft. Collins and the hazy air over Little Rock and Kennedy Space Center. The concentrations of cloud condensation nuclei over Kennedy Space Center were typical of polluted eastern seaboard air. Three different instruments were used to measure ice nuclei: one used filters to collect the particles, and the others used optical and acoustical methods to detect ice crystals grown in portable cloud chambers. A comparison of the ice nucleus counts, which are in good agreement, is presented.

Geologic and hydrologic considerations for various concepts of high-level radioactive waste disposal in conterminous United States

USGS Publications Warehouse

Ekren, E.B.; Dinwiddie, G.A.; Mytton, J.W.; Thordarson, William; Weir, J.E.; Hinrichs, E.N.; Schroder, L.J.

1974-01-01

The purpose of this investigation is to evaluate and identify which geohydrologic environments in conterminous United States are best suited for various concepts or methods of underground disposal of high-level radioactive wastes and to establish geologic and hydrologic criteria that are pertinent to high-level waste disposal. The unproven methods of disposal include (1) a very deep drill hole (30,000-50,000 ft or 9,140-15,240 m), (2) a matrix of (an array of multiple) drill holes (1,000-20,000 ft or 305-6,100 m), (3) a mined chamber (1,000-10,000 ft or 305-3,050 m), (4) a cavity with separate manmade structures (1,000-10,000 ft or 305-3,050 m), and (5) an exploded cavity (2,000-20,000 ft or 610-6,100 m) o The geohydrologic investigation is made on the presumption that the concepts or methods of disposal are technically feasible. Field and laboratory experiments in the future may demonstrate whether or not any of the methods are practical and safe. All the conclusions drawn are tentative pending experimental confirmation. The investigation focuses principally on the geohydrologic possibilities of several methods of disposal in rocks other than salt. Disposal in mined chambers in salt is currently under field investigation, and this disposal method has been intensely investigated and evaluated by various workers under the sponsorship of the Atomic Energy Commission. Of the various geohydrologic factors that must be considered in the selection of optimum waste-disposal sites, the most important is hydrologic isolation to assure that the wastes will be safely contained within a small radius of the emplacement zone. To achieve this degree of hydrologic isolation, the host rock for the wastes must have very low permeability and the site must be virtually free of faults. In addition, the locality should be in (1) an area of low seismic risk where the possibility of large earthquakes rupturing the emplacement zone is very low, (2) where the possibility- of flooding by rise is very low, (3) where a possible return of glacial or pluvial climate will not cause potentially hazardous changes in surface- or ground-water regimens, and (4) where danger of exhumation by erosion is nil. The geographic location for an optimum site is one that is far removed from major drainages, lakes, and oceans, where population density is low, and where the topographic relief is gentle in order to avoid steep surface-water drainage gradients that would allow rapid distribution of contaminants in case of accident. The most suitable medium for the unproven deep drill-hole, matrix-holes, and exploded-cavity methods appears to be crystalline rocks, either intrusive igneous or metamorphic because of their potentially low permeabilities and high mechanical strengths. Salt (either in thick beds or stable domes), tuff, and possibly shale appear to be suitable for mined chambers and cavities with separate manmade structures. Salt appears to be suitable because of its very low permeability, high thermal conductivity, and natural plasticity. Tuff and shale appear suitable because of their very low permeabilities and high ion-exchange capacities. Sedimentary rocks other than shale and volcanic rocks, exclusive of tuff, are considered to be generally unsuitable for waste emplacement because of their potentially high permeabilities. Areas that appear to satisfy most geohydrologic requirements for the deep drill hole and the matrix holes include principally (1) the stable continental interior where the sedimentary cover is thin or absent, (2) the shield area of the North-Central States, and (3) the metamorphic belt of Eastern United States--primarily the Piedmont. These areas are possibly suitable also for the exploded cavity and the mined chamber because the possibility of finding rock with very- permeability at depths from 1,000? feet (305? m) to 20,000 feet (6,100 m) appears to be high. The Basin and Range province of Western United States, particula

Temporal evolution of micro-eruptions within the crater lake of White Island (Whakaari) during January/February 2013

NASA Astrophysics Data System (ADS)

Edwards, Matt; Kennedy, Ben; Jolly, Art; Scheu, Bettina; Taddeucci, Jacopo; Jousset, Philippe; Schmid, Di

2015-04-01

Micro-eruptions are potentially modulated by hydrothermal systems and crater lakes but to date have not been well studied. In January/February 2013 White Island (Whakaari), New Zealand, experienced an about three week long period of atypical, frequent micro-eruptions within its crater lake. Many of these micro-eruptions were recorded by tour operators and GNS personnel monitoring the lake activity. Analysis of this video footage reveals an increasingly energetic eruption style. Deformation of the muddy lake surface by ascending bubbles begins as irregularly shaped bursts, producing liquid strings of mud ejected to heights of less than 10m at 10-15m/s. As the episode progresses, eruption frequency is maintained at semi-regular <10s intervals. Each eruption however starts with an increasingly hemispheric surface deformation ~6m in diameter, and bursts occur as "star-bursts" with ejection of less fluidal ash/mud clots. In addition, these bursts are commonly followed within 2s by a more vertical and energetic secondary ejection of material, which occasionally ejects through the deformed hemispheric surface up to >100m high, and reaches ejection velocities up to 45m/s. The period of frequent "star-bursts" is then followed by a two day phase of constant ~30-75m high ash ejection resulting in the formation of a tuff cone with a central open conduit of 6m within the former crater lake. We theorise that this behaviour is influenced by evolving bubble overpressure/volume, including the presence or absence of a trailing wake of smaller bubbles and is modulated over the eruption episode by the viscosity of the crater lake. In the early stages of the episode a lower viscosity lake provides little resistance to rising gas/ash mixtures. Bubble coalescence and/or overpressure development is therefore minimised, resulting in low energy bursts. Over the course of this episode the viscosity of the lake increases due to addition of ash from ash-carrying gas flux and fluid loss by boiling. Thus higher pressurized gas bubbles can form within the conduit which burst with increasing explosivity. Two experiments are planned simulating this evolving eruption style. In the first, controlled cold volumes of pressurized gas bubbles within a vertical pipe will be released into an overlying chamber filled with varying viscosity fluids, to investigate energy and acoustics of bubble bursts. The second will involve sudden depressurisation of a mud-filled autoclave at elevated temperature (>100°C) to provide eruption metrics. Comparing the eruption styles generated in the lab with those identified at White Island in video analysis will allow us to investigate the dominant controls on the eruption style.

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The original concept envisioned for the use of Fischer-Tropsch processing (FTP) of United States associated natural gas in this study was to provide a way of utilizing gas which could not be brought to market because a pipeline was not available or for which there was no local use. Conversion of gas by FTP could provide a means of utilizing offshore associated gas which would not require installation of a pipeline or re-injection. The premium quality F-T hydrocarbons produced by conversion of the gas can be transported in the same way as the crude oil or in combination (blended) withmore » it, eliminating the need for a separate gas transport system. FTP will produce a synthetic crude oil, thus increasing the effective size of the resource. The two conventional approaches currently used in US territory for handling of natural gas associated with crude petroleum production are re-injection and pipelining. Conversion of natural gas to a liquid product which can be transported to shore by tanker can be accomplished by FTP to produce hydrocarbons, or by conversion to chemical products such as methanol or ammonia, or by cryogenic liquefaction (LNG). This study considers FTP and briefly compares it to methanol and LNG. The Energy International Corporation cobalt catalyst, ratio adjusted, slurry bubble column F-T process was used as the basis for the study and the comparisons. An offshore F-T plant can best be accommodated by an FPSO (Floating Production, Storage, Offloading vessel) based on a converted surplus tanker, such as have been frequently used around the world recently. Other structure types used in deep water (platforms) are more expensive and cannot handle the required load.« less

X-1 research aircraft landing on lakebed

NASA Technical Reports Server (NTRS)

1947-01-01

The first of the rocket-powered research aircraft, the X-1 (originally designated the XS-1), was a bullet-shaped airplane that was built by the Bell Aircraft Company for the US Air Force and the National Advisory Committee on Aeronautics (NACA). The mission of the X-1 was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier'. The first of the three X-1s was glide-tested at Pinecastle Air Force Base, FL, in early 1946. The first powered flight of the X-1 was made on Dec. 9, 1946, at Edwards Air Force Base with Chalmers Goodlin, a Bell test pilot, at the controls. On Oct. 14, 1947, with USAF Captain Charles 'Chuck' Yeager as pilot, the aircraft flew faster than the speed of sound for the first time. Captain Yeager ignited the four-chambered XLR-11 rocket engines after being air-launched from under the bomb bay of a B-29 at 21,000 ft. The 6,000-lbthrust ethyl alcohol/liquid oxygen burning rockets, built by Reaction Motors, Inc., pushed him up to a speed of 700 mph in level flight. Captain Yeager was also the pilot when the X-1 reached its maximum speed of 957 mph. Another USAF pilot. Lt. Col. Frank Everest, Jr., was credited with taking the X-1 to its maximum altitude of 71,902 ft. Eighteen pilots in all flew the X-1s. The number three plane was destroyed in a fire before ever making any powered flights. A single-place monoplane, the X-1 was 31 ft long, 10 ft high, and had a wingspan of 29 ft. It weighed 4,900 lb and carried 8,200 lb of fuel. It had a flush cockpit with a side entrance and no ejection seat. This roughly 30-second video clip shows the X-1 landing on Rogers Dry Lakebed followed by the safety chase aircraft.

Application of salicylic acid dosimetry to evaluate hydrodynamic cavitation as an advanced oxidation process.

PubMed

Arrojo, S; Nerín, C; Benito, Y

2007-03-01

The generation of OH* radicals inside hydrodynamic cavitation bubbles was monitored using a salicylic acid dosimeter. The reaction of this scavenger with OH* produces 2,5-dihydroxybenzoic acid (2,5-DHB) and, to a lesser degree, 2,3-DHB. The former, is a specific reaction product that can be determined with a very high sensitivity using HPLC-IF. This method has been applied to study the influence of the flow-rate and the solution pH for a given cavitation chamber geometry. The salicylic dosimetry has proven especially suitable for the characteristic time scales of hydrodynamic cavitation (higher than those of ultrasonic cavitation), which usually gives rise to recombination of radicals before they can reach the liquid-phase. Working at low pH the hydrophobic salicylic acid migrates to the gas-liquid interface and reacts with the OH* radicals, increasing the trapping efficiency of the dosimeter. Hydrodynamic cavitation works as a very low frequency sonochemical reactor, and therefore its potential as an Advanced Oxidation Process might be limited to reactions at the gas-liquid interface and inner bubble (i.e. with volatiles and/or hydrophobic substances).

Enceladus and Europa: How Does Hydrothermal Activity Begin at the Surface?

NASA Technical Reports Server (NTRS)

Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

2011-01-01

The question of how the surface hydrothermal activity (e.g., eruptive plumes and heat flow) is initiated can be addressed within the frame-work of our "Perrier Ocean" model. This model delivers the necessary heat and chemicals to support the heat flow and plumes observed by Cassini in Enceladus' South Polar Region. The model employs closed-loop circulation of water from a sub-surface ocean. The ocean is the main reservoir of heat and chemicals, including dissolved gases. As ocean water moves up toward the surface, pressure is re-duced and gases exsolve forming bubbles. This bub-bly mixture is less dense than the icy crust and the buoyant ocean-water mixture rises toward the surface. Near the surface, heat and chemicals, including some volatiles, are delivered to the chambers in which plumes form and also to shallow reservoirs that keep the surface ice "warm". (Plume operations, per se, are as described by Schmidt et al. and Postberg et al. and are adopted by us.) After transferring heat, the water cools, bubbles contract and dissolve, and the mixture is now relatively dense. It descends through cracks in the crust and returns to the ocean. Once the closed-loop circulation has started it is self-sustaining. Loss of water via the erupting plumes is relatively negligible compared to the amount needed to maintain the heat flow.We note that the activity described herein for the the "Perrier-Ocean" model could, a priori, apply to all small icy bodies that sheltered an interior ocean at some point in their history.

Measurement of the neutral to charged current cross section ratios for neutrino and and antineutrino interactions on protons

NASA Astrophysics Data System (ADS)

Jones, G. T.; Jones, R. W. L.; Kennedy, B. W.; O'Neale, S. W.; Hoffmann, E.; Haidt, D.; Klein, H.; Mittendorfer, J.; Morrison, D. R. O.; Schmid, P.; Wachsmuth, H.; Hamisi, F.; Miller, D. B.; Mobayyen, M. M.; Aderholz, M.; Deck, L.; Schmitz, N.; Wittek, W.; Corrigan, G.; Myatt, G.; Radojicic, D.; Retter, M. L.; Saitta, B.; Shotton, P. N.; Towers, S. J.; Bullock, F. W.; Burke, S.; Fitch, P. J.; Birmingham-Bonn-CERN-Imperial College-München(MPI)-Oxford-University College Collaboration

1986-10-01

The ratios Rvp and Rvp of the neutral current to charged current cross sections for neutrino and antineutrino interactions on protons have been measured in BEBC. The beam was the CERN SPS 400 GeV wideband beam. The bubble chamber, equipped with the standard External Muon Identifier, was surrounded with an additional plane of wire chambers (Internal Picket Fence), which was added to improve neutral current event identification. For a total transverse momentum of the charged hadrons above 0.45 GeV/ c and a charged multiplicity of at least 3, it was found that R vp = 0.384 ± 0.015 and R vp = 0.338 ± 0.014 ± 0.016, corresponding to a value of sin 2θ w(M woverlineMSof 0.225 ± 0.030 . Combining the results from hydrogen and an isoscalar target, the differences of the neutral current chiral coupling constants were found to be u2l- d2L = -0.080 ± 0.043 ± 0.012 and u2R- d2R = 0.021±0.055±0.028.

Study of collective flows of protons and π^{{-}}_{} -mesons in p+C, Ta and He+Li, C collisions at momenta of 4.2, 4.5 and 10 AGeV/c

NASA Astrophysics Data System (ADS)

Chkhaidze, L.; Chlachidze, G.; Djobava, T.; Galoyan, A.; Kharkhelauri, L.; Togoo, R.; Uzhinsky, V.

2016-11-01

Collective flows of protons and π- -mesons are studied at the momenta of 4.2, 4.5 and 10AGeV/ c for p+C, Ta and He+Li, C interactions. The data were obtained from the streamer chamber (SKM-200-GIBS) and from the Propane Bubble Chamber (PBC-500) systems utilized at JINR. A method of Danielewicz and Odyniec has been employed in determining a directed transverse flow of particles. The values of the transverse flow parameter and the strength of the anisotropic emission were defined for each interacting nuclear pair. It is found that the directed flows of protons and pions decrease with increasing the energy and the mass numbers of colliding nucleus pairs. The π^{{-}}_{} -meson and proton flows exhibit opposite directions in all studied interactions, and the flows of protons are directed in the reaction plane. The Ultra-relativistic Quantum Molecular Dynamical Model (UrQMD) coupled with the Statistical Multi-fragmentation Model (SMM), satisfactorily describes the obtained experimental results.

Darwin's triggering mechanism of volcano eruptions

NASA Astrophysics Data System (ADS)

Galiev, Shamil

2010-05-01

Charles Darwin wrote that ‘… the elevation of many hundred square miles of territory near Concepcion is part of the same phenomenon, with that splashing up, if I may so call it, of volcanic matter through the orifices in the Cordillera at the moment of the shock;…' and ‘…a power, I may remark, which acts in paroxysmal upheavals like that of Concepcion, and in great volcanic eruptions,…'. Darwin reports that ‘…several of the great chimneys in the Cordillera of central Chile commenced a fresh period of activity ….' In particular, Darwin reported on four-simultaneous large eruptions from the following volcanoes: Robinson Crusoe, Minchinmavida, Cerro Yanteles and Peteroa (we cite the Darwin's sentences following his The Voyage of the Beagle and researchspace. auckland. ac. nz/handle/2292/4474). Let us consider these eruptions taking into account the volcano shape and the conduit. Three of the volcanoes (Minchinmavida (2404 m), Cerro Yanteles (2050 m), and Peteroa (3603 m)) are stratovolcanos and are formed of symmetrical cones with steep sides. Robinson Crusoe (922 m) is a shield volcano and is formed of a cone with gently sloping sides. They are not very active. We may surmise, that their vents had a sealing plug (vent fill) in 1835. All these volcanoes are conical. These common features are important for Darwin's triggering model, which is discussed below. The vent fill material, usually, has high level of porosity and a very low tensile strength and can easily be fragmented by tension waves. The action of a severe earthquake on the volcano base may be compared with a nuclear blast explosion of the base. It is known, that after a underground nuclear explosion the vertical motion and the surface fractures in a tope of mountains were observed. The same is related to the propagation of waves in conical elements. After the explosive load of the base. the tip may break and fly off at high velocity. Analogous phenomenon may be generated as a result of a severe earthquake. The volcano base obtains the great earthquake-induced vertical acceleration, and the compression wave begins to propagate through the volcano body. Since we are considering conic volcano, the interaction of this wave with the free surface of the volcano may be easily analysed. It is found that the reflection of the upward-going wave from the volcano slope produces tensile stresses within the volcano and bubbles in conduit magma. The conduit magma is held at high pressure by the weight and the strength of the vent fill. This fill may be collapsed and fly off , when the upward wave is reflected from the volcano crater as a decompression wave. After this collapse the pressure on the magma surface drops to atmospheric, and the decompression front begins to move downward in the conduit. In particular, large gas bubbles can begin to form in the magma within the conduit. The resulting bubble growth provides the driving force at the beginning of the eruption. Thus, the earthquake-induced nonlinear wave phenomena can qualitatively explain the spectacular simultaneity of large eruptions after large earthquakes. The pressure difference between a region of low pressure (atmosphere) and the magma chamber can cause the large-scale eruption. The beginning and the process of the eruption depend on many circumstances: conduit system and its dimension, chamber size and pressure, magma viscosity and gas concentration in it may be the main variables . The resonant free oscillations in the conduit may continue for a long time, since they are fed by the magma chamber pressure (Galiev, Sh. U., 2003. The theory of nonlinear trans-resonant wave phenomena and an examination of Charles Darwin's earthquake reports. Geophys. J. Inter., 154, 300-354.). The behaviour of the system strongly depends on the magma viscosity. The gas can escape from the bubbles more easily in the case of low viscous magma. However, if the magma is very viscous, so the gas cannot escape so easily, then the bubbles grow very quickly near the vent only. Effects of this growth can resemble an explosion.

The evolution of space simulation

NASA Technical Reports Server (NTRS)

Edwards, Arthur A.

1992-01-01

Thirty years have passed since the first large (more than 15 ft diameter) thermal vacuum space simulation chambers were built in this country. Many changes have been made since then, and the industry has learned a great deal as the designs have evolved in that time. I was fortunate to have been part of that beginning, and have participated in many of the changes that have occurred since. While talking with vacuum friends recently, I realized that many of the engineers working in the industry today may not be aware of the evolution of space simulation because they did not experience the changes that brought us today's technology. With that in mind, it seems to be appropriate to take a moment and review some of the events that were a big part of the past thirty years in the thermal vacuum business. Perhaps this review will help to understand a little of the 'why' as well as the 'how' of building and operating large thermal vacuum chambers.

Topological, total, and elastic cross sections for K/sup +/p,. pi. /sup +/p, and pp interactions at 147 GeV/c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brick, D.; Rudnicka, H.; Shapiro, A.M.

1982-06-01

The Fermilab hybrid 30-in. bubble-chamber spectrometer was exposed to a tagged 147-GeV/c positive beam containing ..pi../sup +/, K/sup +/, and p. A sample of 3003 K/sup +/p, 19 410 pp, and 20 745 ..pi../sup +/p interactions is used to derive sigma/sub n/, , f/sub 2//sup tsc/c, and /D for each beam particle. These values are compared to values obtained at other, mostly lower, beam momenta. The overall dependence of on E/sub a/, the available center-of-mass energy, for these three reactions as well as ..pi../sup -/p and pp interactions has been determined.

ATTRITION RESISTANT IRON-BASED FISCHER-TROPSCH CATALYSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

James G. Goodwin, Jr.; James J. Spivey; K. Jothimurugesan

1999-03-29

The Fischer-Tropsch (F-T) reaction provides a way of converting coal-derived synthesis gas (CO+H{sub 2}) to liquid fuels. Since the reaction is highly exothermic, one of the major problems in control of the reaction is heat removal. Recent work has shown that the use of slurry bubble column reactors (SBCRs) can largely solve this problem. Iron-based (Fe) catalysts are preferred catalysts for F-T when using low CO/H2 ratio synthesis gases derived from modern coal gasifiers. This is because in addition to reasonable F-T activity, the F-T catalysts also possess high water gas shift (WGS) activity. However, a serious problem with themore » use of Fe catalysts in a SBCR is their tendency to undergo attrition. This can cause fouling/plugging of downstream filters and equipment, making the separation of catalyst from the oil/wax product very difficult if not impossible, and results in a steady loss of catalyst from the reactor. The objectives of this research are to develop a better understanding of the parameters affecting attrition resistance of Fe F-T catalysts suitable for use in SBCRs and to incorporate this understanding into the design of novel Fe catalysts having superior attrition resistance. Catalyst preparations will be based on the use of spray drying and will be scalable using commercially available equipment. The research will employ among other measurements, attrition testing and F-T synthesis, including long duration slurry reactor runs in order to ascertain the degree of success of the various preparations. The goal is to develop an Fe catalyst which can be used in a SBCR having only an internal filter for separation of the catalyst from the liquid product, without sacrificing F-T activity and selectivity. The effect of silica addition via coprecipitation and as a binder to a doubly promoted Fischer-Tropsch synthesis iron catalyst (100 Fe/5 Cu/4.2 K) was studied. The catalysts were prepared by coprecipitation, followed by binder addition and drying in a 1 m diameter, 2 m tall spray dryer. The binder silica content was varied from 0 to 20 wt %. A catalyst with 12 wt % binder silica was found to have the highest attrition resistance. F-T reaction studies over 100 hours in a fixed-bed reactor showed that this catalyst maintained around 95 % CO conversion with a methane selectivity of less than 7 wt % and a C5 + selectivity of greater than 73 wt %. The effect of adding precipitated silica from 0 to 20 parts by weight to this catalyst (containing 12 wt % binder silica) was also studied. Addition of precipitated silica was found to be detrimental to attrition resistance and resulted in increased methane and reduced wax formation. An HPR series of proprietary catalysts was prepared to further improve the attrition resistance. Based on the experience gained, a proprietary HPR-43 catalyst has been successfully spray dried in 500 g quantity. This catalyst showed 95 % CO conversion over 125 h and had less than 4 % methane selectivity. Its attrition resistance was one of the highest among the catalyst tested.« less

Design and demonstration of a pumpless 14 compartment microphysiological system.

PubMed

Miller, Paula G; Shuler, Michael L

2016-10-01

We describe a human "Body-on-a-chip" device (or microphysiological system) that could be used to emulate drug distribution, metabolism, and action in the body. It is based upon a physiologically based pharmacokinetic-pharmacodynamic (PBPK-PD) model, where multiple chambers representing different organs are connected with fluidic channels to mimic multi-organ interactions within the body. Here we describe a pumpless 14 chamber (13 organs) microfluidic cell culture device that provides a separation between barrier and nonbarrier types of cell cultures. Our barrier chamber layer (skin, GI tract, and lung) allows for direct access and/or exposures to chemical or biological reagents forcing these reagents to pass through a barrier of cells established on a microfabricated membrane before exposing the nonbarrier tissue chambers (fat, kidney, heart, adrenal glands, liver, spleen, pancreas, bone marrow, brain, muscle) or entering the microfluidic circulation within the device. Our nonbarrier tissue chambers were created as three-dimensional configurations by resuspending cells in hydrogel (PGMatrix). We used cell lines to represent five of these organs (barrier lines-A549 [lung] and Caco2 [GI]) (nonbarrier lines-HepG2 C3A [liver], Meg01 [bone marrow], and HK2 [kidney]). The dimensions of our straight duct-like channels to each organ chamber were designed to provide the appropriate flow of a culture medium. The organ volumes and organ flow rates that have been reported for an average human male were used to estimate the desired fluid retention times in each organ chamber. The flow through the channels was induced by gravity on a custom programmed rocker platform which enabled pumpless operation and minimized bubble entrapment. The purpose of this paper is to describe the design and operation of a 14 chamber multi-organ system representing 13 tissues/organs with both barrier and nonbarrier tissue chambers and to study the interactive responses among the various cell lines. We demonstrate that five different cell lines survived with high viability (above 85%) for 7 days. We compared the individual observed flow rates to the compartments to the desired or estimated flow rates. This work demonstrates the feasibility of constructing, operating and maintaining a simple, gravity-driven, multi-organ microphysiological system with the capability of measuring cellular functions such as CYP1A1 and CYP3A4 activities, albumin release, urea, maintenance of tight junctions, and presence of surfactant for a sustained period. Biotechnol. Bioeng. 2016;113: 2213-2227. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

A test of flushing procedures to control salt-water intrusion at the W. P. Franklin Dam near Ft. Myers, Florida and The magnitude and extent of salt-water contamination in the Caloosahatchee River between La Belle and Olga, Florida

USGS Publications Warehouse

Boggess, Durward H.

1970-01-01

During low-flow periods, salty water from the tidal part of the Caloosahatchee River moves upstream during boat lockages at the W. P. Franklin Darn near Ft. Myers, Florida, as shown on figure L Salty water enters the lock chamber through openings of the downstream sector gates which separate tidal and fresh water; when the upstream gates open, some of the salty water moves into the upper pool, probably as a density current. Repeated injections of salty water cause a progressive increase in the salinity of the upstream water. The salty water moves upstream within the deeper parts of the river channel as far as 5 or more miles above the lock. Some mixing of the high-chloride deeper water and the fresher shallow water occurs in the affected reach above the lock, probably as a result of wind and waves, and turbulence created by boat traffic.

Transpiration Cooling Experiment

NASA Technical Reports Server (NTRS)

Song, Kyo D.; Ries, Heidi R.; Scotti, Stephen J.; Choi, Sang H.

1997-01-01

The transpiration cooling method was considered for a scram-jet engine to accommodate thermally the situation where a very high heat flux (200 Btu/sq. ft sec) from hydrogen fuel combustion process is imposed to the engine walls. In a scram-jet engine, a small portion of hydrogen fuel passes through the porous walls of the engine combustor to cool the engine walls and at the same time the rest passes along combustion chamber walls and is preheated. Such a regenerative system promises simultaneously cooling of engine combustor and preheating the cryogenic fuel. In the experiment, an optical heating method was used to provide a heat flux of 200 Btu/sq. ft sec to the cylindrical surface of a porous stainless steel specimen which carried helium gas. The cooling efficiencies by transpiration were studied for specimens with various porosity. The experiments of various test specimens under high heat flux have revealed a phenomenon that chokes the medium flow when passing through a porous structure. This research includes the analysis of the system and a scaling conversion study that interprets the results from helium into the case when hydrogen medium is used.

Study of. nu. d r arrow. mu. sup minus pp sub s and. nu. d r arrow. mu. sup minus. Delta. sup ++ (1232) n sub s using the BNL 7-foot deuterium-filled bubble chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kitagaki, T.; Yuta, H.; Tanaka, S.

1990-09-01

The weak nucleon axial-vector ({ital F}{sub {ital A}}) and vector ({ital F}{sub {ital V}}) form factors are determined from the momentum-transfer-squared ({ital Q}{sup 2}) distributions using 2538 {mu}{sup {minus}} {ital p} and 1384 {mu}{sup {minus}}{Delta}{sup ++} events. The data were obtained from 1 800 000 pictures taken in the BNL 7-foot deuterium-filled bubble chamber exposed to a wide-band neutrino beam with a mean energy {ital E}{sub {nu}}=1.6 GeV. In the framework of the conventional {ital V}{minus}{ital A} theory with standard assumptions, the value obtained from the {mu}{sup {minus}}{ital p} events for the axial-vector mass {ital M}{sub {ital A}} in themore » pure dipole parameterization is 1.070{sub {minus}0.045}{sup +0.040} GeV and from the {mu}{sup {minus}}{Delta}{sup ++} events is 1.28{sub {minus}0.10}{sup +0.08} GeV. These results are in good agreement with an earlier measurement from this experiment and other recent results. The reaction mechanisms for both processes are compared and found to be very similar. A two-parameter fit for the quasielastic reaction, using dipole forms for {ital F}{sub {ital V}} and {ital F}{sub {ital A}}, yields {ital M}{sub {ital A}}=0.97{sub {minus}0.11}{sup +0.14} GeV and {ital M}{sub {ital V}}=0.89{sub {minus}0.07}{sup +0.04} GeV, which is in good agreement with the conserved-vector-current value of {ital M}{sub {ital V}}=0.84 GeV. Possible deviations from the standard assumptions are also discussed.« less

EUPHORE: Research facility to study tropospheric transformation processes

NASA Astrophysics Data System (ADS)

Wirtz, K.

2003-04-01

The EUPHORE simulation chamber consists of two half-spherical Teflon bags, each with a volume of 200 m^3 and a base diameter of 9.2 m. The FEP Teflon has a transmission of about 75% at 280 nm and of more than 80% above 300 nm. Purified and dried ambient air is used to fill the chamber and flush it between experiments. The humidity in the chamber is measured by a dew point hygrometer, and the temperature is monitored by several thermocouples located at different positions inside the chamber. The solar flux is monitored with spectral resolution in the photochemically active spectral region. The simulation chamber is equipped with a number of analytical instruments for the measurement of single VOC components, NO, NO_2, O_3 and other species. In-situ measurements in the ppb range are performed using long-path absorption spectroscopy, in the UV/VIS by DOAS and in the IR by FT-IR. A GC-MS system is used for the sensitive analysis of a variety of reaction products. A newly installed LIF technique allows the in situ measurement of OH and HO_2 radicals during the reaction processes. The technological concept and the organisation structure of the EUPHORE facility will be presented. The integration of quality control measures is an obvious and necessary second step for the successful exploitation of the technically advanced outdoor smog chamber EUPHORE as a research tool. This will underline the leadership of the European scientific community in the important research areas of investigating transformation processes in the troposphere and tracking the influence of human activities on photooxidant formation and its interaction with processes related to global change. In the coming years the main scientific focus will be on testing chemical mechanisms in order to improve the models which describe the atmospheric processes of complex chemical systems. The collaborative work at the EUPHORE outdoor simulation chamber will provide all the users of the installation with a basic platform to exchange analytical technology, sampling procedures, methods of data treatment, and know-how that can also be applied in field campaigns.

Magma Dynamics at Mid-Ocean Ridges by Noble Gas Kinetic Fractionation: Assessment of Magmatic Ascent Rates and Mantle Composition

NASA Astrophysics Data System (ADS)

Paonita, A.; Martelli, M.

2007-12-01

Topical scientific literature on magma degassing at mid-ocean ridges more and more focuses on exsolution processes occurring under conditions that are far from thermodynamic equilibrium between bubbles and silicate melt. Indeed, the dynamics of magma ascent and decompression can be faster than that of CO2 diffusion into bubbles, in which case the diffusivity ratios among volatiles are the main control of the composition of the exsolving gas phase. We have developed a model of bubble growth in silicate melts that calculates the extent of both CO2 supersaturation and kinetic fractionation among noble gases in vesicles in relation to the decompressive rate of basaltic melts. The model predicts that, due to comparable Ar and CO2 diffusivity, magma degassing at low pressure fractionates both He/Ar and He/CO2 ratios by a similar extent, while the slower CO2 diffusion at high pressure causes early kinetic effects on Ar/CO2 ratio and dramatically changes the degassing paths. By using this tool, we have reviewed the global He-Ar-CO2 dataset of fluid inclusions in mid-ocean-ridge glasses. We display that non-equilibrium fractionations among He, Ar and CO2, driven by their different diffusivities in silicate melts, are common in most of the natural conditions of magma decompression and their signature strongly depends on pressure of degassing. The different geochemical signatures among suites of data coming from different ridge segments mainly depend on the depth of the magma chamber where the melt was stored. Moreover, variations inside a single suite emerge due to the interplay between variable ascent speed of magma and cooling rate of the emplaced lava. As a result, two data groups coming from the Pito Seamount suite (Easter Microplate East ridge), showing different degree of CO2 supersaturation and He/Ar fractionation, provide ascent rates which differ by ten folds or even more. The large variations in both the He/CO2 and Ar/CO2 ratios at almost constant He/Ar, displayed in products coming from the Mid-Atlantic Ridge 24°N segment and the Rodriguez Triple Junction, require magma storage and degassing processes occurring at high-pressure conditions. In contrast, the simultaneous increase in both He/CO2 and He/Ar of the East Pacific Rise and South-East Indian Ridge data sets suggests the dominance of low-pressure fractionation, implying that the shallow magma chambers are at a lower depth than those of the Mid-Atlantic Ridge 24°N and Rodriguez Triple Junction. Our conclusions support the presence of a relationship between spreading rate and depth of high-temperature zones below ridges, and are consistent with the depth of magma chambers as suggested from seismic studies. Finally, the non-equilibrium degassing model provides striking constraints on the compositions of noble gases and carbon in mantle-derived magmas. Our results dispense in fact with the supposed need for He-Ar-CO2 heterogeneities in the upper mantle, because the degassing of a single, popping-rock-like primary magma is able to explain all the available data.

CAPRICE98: A balloon borne magnetic spectrometer to study cosmic ray antimatter and composition at different atmospheric depths

NASA Astrophysics Data System (ADS)

Ambriola, M. L.; Barbiellini, G.; Bartalucci, S.; Basini, G.; Bellotti, R.; Bergstroem, D.; Bocciolini, M.; Boezio, M.; Bravar, U.; Cafagna, F.; Carlson, P.; Casolino, M.; Castellano, M.; Ciacio, F.; Circella, M.; de Marzo, C.; de Pascale, M. P.; Finetti, N.; Francke, T.; Hof, M.; Kremer, J.; Menn, W.; Mitchell, J. W.; Morselli, A.; Ormes, J. F.; Papini, P.; Perego, A.; Piccardi, S.; Picozza, P.; Ricci, M.; Schiavon, P.; Simon, M.; Sparvoli, R.; Spillantini, P.; Stephens, S. A.; Stochaj, S. J.; Streitmatter, R. E.; Suffert, M.; Vacchi, A.; Weber, N.; Zampa, N.

1999-08-01

CAPRICE98 is a superconducting magnetic spectrometer built by the WiZard collaboration. It was launched from Ft. Sumner, NM, USA on the 28th of May 1998. For the first time a gas RICH detector has been flown together with a silicon electromagnetic calorimeter. The instrument configuration included a time of flight detector and a drift chamber stack, which were placed in the region of a magnet field, for rigidity measurement. Science objectives for this experiment include the study of antimatter in cosmic rays and that of cosmic ray composition in the atmosphere with special focus on muons.

Electromagnetic compatibility (EMC) standard test chamber upgrade requirements for spacecraft design verification tests

NASA Technical Reports Server (NTRS)

Dyer, Edward F.

1992-01-01

In view of the serious performance deficiencies inherent in conventional modular and welded shielding EMC test enclosures, in which multipath reflections and resonant standing waves can damage flight hardware during RF susceptibility tests, NASA-Goddard has undertaken the modification of a 20 x 24 ft modular-shielded enclosure through installation of steel panels to which ferrite tiles will be mounted with epoxy. The internally reflected RF energy will thereby be absorbed, and exterior power-line noise will be reduced. Isolation of power-line filters and control of 60-Hz ground connections will also be undertaken in the course of upgrading.

From Supercomputer Modeling to Highest Mass Resolution in FT-ICR.

PubMed

N Nikolaev, Evgene; N Vladimirov, Gleb; Jertz, Roland; Baykut, Gökhan

2013-01-01

Understanding of behavior of ion ensembles inside FT-ICR cell based on the computer simulation of ion motion gives rise to the new ideas of cell designs. The recently introduced novel FT-ICR cell based on a Penning ion trap with specially shaped excitation and detection electrodes prevents distortion of ion cyclotron motion phases (normally caused by non-ideal electric trapping fields) by averaging the trapping DC electric field during the ion motion in the ICR cell. Detection times of 5 min resulting in resolving power close to 40,000,000 have been reached for reserpine at m/z 609 at a magnetic field of only 7 Tesla. Fine structures of resolved 13Cn isotopic cluster groups could be measured for molecular masses up to 5.7 kDa (insulin) with resolving power of 4,000,000 at 7 Tesla. Based on resolved fine structure patterns atomic compositions can be directly determined using a new developed algorithm for fine structure processing. Mass spectra of proteins and multimers of proteins reaching masses up to 186 kDa (enolase tetramer) could be measured with isotopic resolution. For instance, at 7 Tesla resolving power of 800,000 was achieved for enolase dimer (96 kDa) and 500,000 for molecular masses above 100 kDa. Experimental data indicate that there is practically no limit for the resolving power of this ICR cell except by collisional damping in the ultrahigh vacuum chamber.

A Multiple-Scales Partial Solution of the Pulse-Forced Rayleigh-Plesset Equation of Cavitation Bubble Dynamics

DTIC Science & Technology

1988-02-01

d 3 ’iN3131iJ303 HiJnSSjHd QBOV^AV fcmwt^flomsx^^ <lNWWlWW\\’WWlWVNWiy»UVVTiniinilf^»1lll>Wf%|rrw<rv*rviiV"jw- j »-,w\\iW¥ *« ■ \\ iLn mit...0) T3 U 0 -0 0) CQ 0) £ u 9 <U « Ä f-t * J 4J 0 0 (0 .H U-t H PL, 0 • cn 0J l-l 3 00 d D ’iN3101dJ3O3 HanSSBHd QBOVHJAV...34dTdT • (2.3) where dS D J „ dx 57" 2 or ds" r ’ (2.4) from Eq. (2.1). By substitution of Eq. (2.2) and Eq. (2.4) into Eq. (2.3)

Design and Predictions for a High-Altitude (Low-Reynolds-Number) Aerodynamic Flight Experiment

NASA Technical Reports Server (NTRS)

Greer, Donald; Hamory, Phil; Krake, Keith; Drela, Mark

1999-01-01

A sailplane being developed at NASA Dryden Flight Research Center will support a high-altitude flight experiment. The experiment will measure the performance parameters of an airfoil at high altitudes (70,000 to 100,000 ft), low Reynolds numbers (200,000 to 700,000), and high subsonic Mach numbers (0.5 and 0.65). The airfoil section lift and drag are determined from pitot and static pressure measurements. The locations of the separation bubble, Tollmien-Schlichting boundary layer instability frequencies, and vortex shedding are measured from a hot-film strip. The details of the planned flight experiment are presented. Several predictions of the airfoil performance are also presented. Mark Drela from the Massachusetts Institute of Technology designed the APEX-16 airfoil, using the MSES code. Two-dimensional Navier-Stokes analyses were performed by Mahidhar Tatineni and Xiaolin Zhong from the University of California, Los Angeles, and by the authors at NASA Dryden.

Irregular-regular mode oscillations inside plasma bubble and its fractal analysis in glow discharge magnetized plasma

NASA Astrophysics Data System (ADS)

Megalingam, Mariammal; Hari Prakash, N.; Solomon, Infant; Sarma, Arun; Sarma, Bornali

2017-04-01

Experimental evidence of different kinds of oscillations in floating potential fluctuations of glow discharge magnetized plasma is being reported. A spherical gridded cage is inserted into the ambient plasma volume for creating plasma bubbles. Plasma is produced between a spherical mesh grid and chamber. The spherical mesh grid of 80% optical transparency is connected to the positive terminal of power supply and considered as anode. Two Langmuir probes are kept in the ambient plasma to measure the floating potential fluctuations in different positions within the system, viz., inside and outside the spherical mesh grid. At certain conditions of discharge voltage (Vd) and magnetic field, irregular to regular mode appears, and it shows chronological changes with respect to magnetic field. Further various nonlinear analyses such as Recurrence Plot, Hurst exponent, and Lyapunov exponent have been carried out to investigate the dynamics of oscillation at a range of discharge voltages and external magnetic fields. Determinism, entropy, and Lmax are important measures of Recurrence Quantification Analysis which indicate an irregular to regular transition in the dynamics of the fluctuations. Furthermore, behavior of the plasma oscillation is characterized by the technique called multifractal detrended fluctuation analysis to explore the nature of the fluctuations. It reveals that it has a multifractal nature and behaves as a long range correlated process.

Dark sequential Z ' portal: Collider and direct detection experiments

NASA Astrophysics Data System (ADS)

Arcadi, Giorgio; Campos, Miguel D.; Lindner, Manfred; Masiero, Antonio; Queiroz, Farinaldo S.

2018-02-01

We revisit the status of a Majorana fermion as a dark matter candidate when a sequential Z' gauge boson dictates the dark matter phenomenology. Direct dark matter detection signatures rise from dark matter-nucleus scatterings at bubble chamber and liquid xenon detectors, and from the flux of neutrinos from the Sun measured by the IceCube experiment, which is governed by the spin-dependent dark matter-nucleus scattering. On the collider side, LHC searches for dilepton and monojet + missing energy signals play an important role. The relic density and perturbativity requirements are also addressed. By exploiting the dark matter complementarity we outline the region of parameter space where one can successfully have a Majorana dark matter particle in light of current and planned experimental sensitivities.

Toward jet injection by continuous-wave laser cavitation

NASA Astrophysics Data System (ADS)

Berrospe-Rodriguez, Carla; Visser, Claas Willem; Schlautmann, Stefan; Rivas, David Fernandez; Ramos-Garcia, Ruben

2017-10-01

This is a study motivated by the need to develop a needle-free device for eliminating major global healthcare problems caused by needles. The generation of liquid jets by means of a continuous-wave laser, focused into a light absorbing solution, was studied with the aim of developing a portable and affordable jet injector. We designed and fabricated glass microfluidic devices, which consist of a chamber where thermocavitation is created and a tapered channel. The growth of a vapor bubble displaces and expels the liquid through the channel as a fast traveling jet. Different parameters were varied with the purpose of increasing the jet velocity. The velocity increases with smaller channel diameters and taper ratios, whereas larger chambers significantly reduce the jet speed. It was found that the initial position of the liquid-air meniscus interface and its dynamics contribute to increased jet velocities. A maximum velocity of 94±3 m/s for a channel diameter of D=120 μm, taper ratio n=0.25, and chamber length E=200 μm was achieved. Finally, agarose gel-based skin phantoms were used to demonstrate the potential of our devices to penetrate the skin. The maximum penetration depth achieved was ˜1 mm, which is sufficient to penetrate the stratum corneum and for most medical applications. A meta-analysis shows that larger injection volumes will be required as a next step to medical relevance for laser-induced jet injection techniques in general.

In-flight hypoxia incidents in military aircraft: causes and implications for training.

PubMed

Cable, Gordon G

2003-02-01

Hypoxia has long been recognized as a significant physiological threat at altitude. Aircrew have traditionally been trained to recognize the symptoms of hypoxia using hypobaric chamber training at simulated altitudes of 25,000 ft or more. The aim of this study was to analyze incidents of hypoxia reported to the Directorate of Flying Safety of the Australian Defence Force (DFS-ADF) for the period 1990-2001, as no previous analysis of these incidents has been undertaken. The data will be useful in planning future training strategies for aircrew in aviation physiology. A search was requested of the DFS-ADF database, for all Aircraft Safety Occurrence Reports (ASOR) listing hypoxia as a factor. These cases were reviewed and the following data analyzed: aircraft type, number of persons on board (POB), number of hypoxic POB, any fatalities, whether the victims were trained or untrained as aircrew, if the symptoms were recognized as hypoxia, symptoms experienced, the altitude at which the incident occurred, and the likely cause. During the period studied. 27 reports of hypoxia were filed, involving 29 aircrew. In only two cases was consciousness lost, and one of these resulted in a fatality. Most incidents (85.1%) occurred in fighter or training aircraft with aircrew who use oxygen equipment routinely. The majority of symptoms occurred between 10,000 and 19,000 ft. The most common cause of hypoxia (63%) in these aircraft was the failure of the mask or regulator, or a mask leak. Rapid accidental decompression did not feature as a cause of hypoxia. Symptoms were subtle and often involved cognitive impairment or light-headedness. The vast majority (75.8%) of these episodes were recognized by the aircrew themselves, reinforcing the importance and benefit of hypoxia training. This study confirms the importance and effectiveness of hypoxia training for aircrew. Hypoxia incidents occur most commonly at altitudes less than 19,000 ft. This should be emphasized to aircrew, whose expectation may be that it is only a problem of high altitude. Proper fitting of masks, leak checks, and equipment checks should be taught to all aircrew and reinforced regularly. Current hypobaric chamber training methods should be reviewed for relevance to the most at-risk aircrew population. Methods that can simulate subtle incapacitation while wearing oxygen equipment should be explored. Hypoxia in flight still remains a serious threat to aviators, and can result in fatalities.

X-1 launch from B-29 mothership

NASA Technical Reports Server (NTRS)

1947-01-01

The first of the rocket-powered research aircraft, the X-1 (originally designated the XS-1), was a bullet-shaped airplane that was built by the Bell Aircraft Company for the US Air Force and the National Advisory Committee on Aeronautics (NACA). The mission of the X-1 was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier'. The first of the three X-1s was glide-tested at Pinecastle Air Force Base, FL, in early 1946. The first powered flight of the X-1 was made on Dec. 9, 1946, at Edwards Air Force Base with Chalmers Goodlin, a Bell test pilot, at the controls. On Oct. 14, 1947, with USAF Captain Charles 'Chuck' Yeager as pilot, the aircraft flew faster than the speed of sound for the first time. Captain Yeager ignited the four-chambered XLR-11 rocket engines after being air-launched from under the bomb bay of a B-29 at 21,000 ft. The 6,000-lb thrust ethyl alcohol/liquid oxygen burning rockets, built by Reaction Motors, Inc., pushed him up to a speed of 700 mph in level flight. Captain Yeager was also the pilot when the X-1 reached its maximum speed of 957 mph. Another USAF pilot. Lt. Col. Frank Everest, Jr., was credited with taking the X-1 to its maximum altitude of 71,902 ft. Eighteen pilots in all flew the X-1s. The number three plane was destroyed in a fire before ever making any powered flights. A single-place monoplane, the X-1 was 31 ft long, 10 ft high, and had a wingspan of 29 ft. It weighed 4,900 lb and carried 8,200 lb of fuel. It had a flush cockpit with a side entrance and no ejection seat. This roughly 30-second video clip shows the X-1 launched from a B-29, ignition of the XLR-11 rocket engine, and the succeeding flight, including a roll. At one point, the video shows observers of the flight from the ground.

Biological Control of Lettuce Drop and Host Plant Colonization by Rhizospheric and Endophytic Streptomycetes

PubMed Central

Chen, Xiaoyulong; Pizzatti, Cristina; Bonaldi, Maria; Saracchi, Marco; Erlacher, Armin; Kunova, Andrea; Berg, Gabriele; Cortesi, Paolo

2016-01-01

Lettuce drop, caused by the soil borne pathogen Sclerotinia sclerotiorum, is one of the most common and serious diseases of lettuce worldwide. Increased concerns about the side effects of chemical pesticides have resulted in greater interest in developing biocontrol strategies against S. sclerotiorum. However, relatively little is known about the mechanisms of Streptomyces spp. as biological control agents against S. sclerotiorum on lettuce. Two Streptomyces isolates, S. exfoliatus FT05W and S. cyaneus ZEA17I, inhibit mycelial growth of Sclerotinia sclerotiorum by more than 75% in vitro. We evaluated their biocontrol activity against S. sclerotiorum in vivo, and compared them to Streptomyces lydicus WYEC 108, isolated from Actinovate®. When Streptomyces spp. (106 CFU/mL) were applied to S. sclerotiorum inoculated substrate in a growth chamber 1 week prior lettuce sowing, they significantly reduced the risk of lettuce drop disease, compared to the inoculated control. Interestingly, under field conditions, S. exfoliatus FT05W and S. cyaneus ZEA17I protected lettuce from drop by 40 and 10% respectively, whereas S. lydicus WYEC 108 did not show any protection. We further labeled S. exfoliatus FT05W and S. cyaneus ZEA17I with the enhanced GFP (EGFP) marker to investigate their rhizosphere competence and ability to colonize lettuce roots using confocal laser scanning microscopy (CLSM). The abundant colonization of young lettuce seedlings by both strains demonstrated Streptomyces' capability to interact with the host from early stages of seed germination and root development. Moreover, the two strains were detected also on 2-week-old roots, indicating their potential of long-term interactions with lettuce. Additionally, scanning electron microscopy (SEM) observations showed EGFP-S. exfoliatus FT05W endophytic colonization of lettuce root cortex tissues. Finally, we determined its viability and persistence in the rhizosphere and endorhiza up to 3 weeks by quantifying its concentration in these compartments. Based on these results we conclude that S. exfoliatus FT05W has high potential to be exploited in agriculture for managing soil borne diseases barely controlled by available plant protection products. PMID:27242735

Wavelength-Agile Optical Sensor for Exhaust Plume and Cryogenic Fluid Interrogation

NASA Technical Reports Server (NTRS)

Sanders, Scott T.; Chiaverini, Martin J.; Gramer, Daniel J.

2004-01-01

Two optical sensors developed in UW-Madison labs were evaluated for their potential to characterize rocket engine exhaust plumes and liquid oxygen (LOX) fluid properties. The plume sensor is based on wavelength-agile absorption spectroscopy A device called a chirped white pulse emitter (CWPE) is used to generate the wavelength agile light, scanning, for example, 1340 - 1560 nm every microsecond. Properties of the gases in the rocket plume (for example temperature and water mole fraction) can be monitored using these wavelength scans. We have performed preliminary tests in static gas cells, a laboratory GOX/GH2 thrust chamber, and a solid-fuel hybrid thrust chamber, and these initial tests demonstrate the potential of the CWPE for monitoring rocket plumes. The LOX sensor uses an alternative to wavelength agile sensing: two independent, fixed-wavelength lasers are combined into a single fiber. One laser is absorbed by LOX and the other not: by monitoring the differential transmission the LOX concentration in cryogenic feed lines can be inferred. The sensor was successful in interrogating static LOX pools in laboratory tests. Even in ice- and bubble-laden cryogenic fluids, LOX concentrations were measured to better than 1% with a 3 microsec time constant.

Neutron Activation Diagnostics in Deuterium Gas-Puff Experiments on the 3 MA GIT-12 Z-Pinch

NASA Astrophysics Data System (ADS)

Cikhardt, J.; Klir, D.; Rezac, K.; Cikhardtova, B.; Kravarik, J.; Kubes, P.; Sila, O.; Shishlov, A. V.; Cherdizov, R. K.; Fursov, F. I.; Kokshenev, V. A.; Kurmaev, N. E.; Labetsky, A. Yu; Ratakhin, N. A.; Dudkin, G. N.; Garapatsky, A. A.; Padalko, V. N.; Varlachev, V. A.; Turek, K.

2016-10-01

The experiments with a deuterium z-pinch on the GIT-12 generator at IHCE in Tomsk were performed in the frame of the Czech-Russian agreement. A set of neutron diagnostics included scintillation time-of-flight detectors, bubble detectors, and several kinds of threshold nuclear activation detectors in the order to obtain information about the yield, anisotropy, and spectrum of the neutrons produced by a deuterium gas-puff. The average neutron yield in these experiments was of the order of 1012 neutrons per a single shot. The energy spectrum of the produced neutrons was evaluated using neutron time-of-flight detectors and a set of neutron activation detectors. Because the deuterons in the pinch achieve multi-MeV energies, non-DD neutrons are produced by nuclear reactions of deuterons with a stainless steel vacuum chamber and aluminum components of diagnostics inside the chamber. An estimated number of the non-DD was of the order of 1011. GACR (Grant No. 16-07036S), CME (Grant Nos. LD14089, LG13029, and LH13283), MESRF (Grant No. RFMEFI59114X0001), IAEA (Grant No. RC17088), CTU (Grant No. SGS 16/223/OHK3/3T/13).

Study of collective flows of protons and $$ \\pi^{{-}}_{}$$ π - -mesons in p+C, Ta and He+Li, C collisions at momenta of 4.2, 4.5 and 10 AGeV/c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chkhaidze, L.; Chlachidze, G.; Djobava, T.

Collective flows of protons andmore » $$\\pi^{-}$$ -mesons are studied at the momenta of 4.2, 4.5 and 10AGeV/c for p+C, Ta and He+Li, C interactions. The data were obtained from the streamer chamber (SKM-200-GIBS) and from the Propane Bubble Chamber (PBC-500) systems utilized at JINR. A method of Danielewicz and Odyniec has been employed in determining a directed transverse flow of particles. The values of the transverse flow parameter and the strength of the anisotropic emission were defined for each interacting nuclear pair. It is found that the directed flows of protons and pions decrease with increasing the energy and the mass numbers of colliding nucleus pairs. The $$ \\pi^{{-}}_{}$$ -meson and proton flows exhibit opposite directions in all studied interactions, and the flows of protons are directed in the reaction plane. Lastly, the Ultra-relativistic Quantum Molecular Dynamical Model (UrQMD) coupled with the Statistical Multi-fragmentation Model (SMM), satisfactorily describes the obtained experimental results.« less

Energy conversion system involving change in the density of an upwardly moving liquid

DOEpatents

Petrick, Michael

1989-01-01

A system for converting thermal energy into electrical energy includes a fluid reservoir, a relatively high boiling point fluid such as lead or a lead alloy within the reservoir, a downcomer defining a vertical fluid flow path communicating at its upper end with the reservoir and an upcomer defining a further vertical fluid flow path communicating at its upper end with the reservoir. A variable area nozzle of rectangular section may terminate the upper end of the upcomer and the lower end of the of the downcomer communicates with the lower end of the upcomer. A mixing chamber is located at the lower end portion of the upcomer and receives a second relatively low boiling point fluid such as air, the mixing chamber serving to introduce the low boiling point fluid into the upcomer so as to produce bubbles causing the resultant two-phase fluid to move at high velocity up the upcomer. Means are provided for introducing heat into the system preferably between the lower end of the downcomer and the lower end of the upcomer. Power generating means are associated with the one of the vertical fluid flow paths one such power generating means being a magneto hydrodynamic electrical generator.

Technical Note: A minimally invasive experimental system for pCO2 manipulation in plankton cultures using passive gas exchange (atmospheric carbon control simulator)

NASA Astrophysics Data System (ADS)

Love, Brooke A.; Olson, M. Brady; Wuori, Tristen

2017-05-01

As research into the biotic effects of ocean acidification has increased, the methods for simulating these environmental changes in the laboratory have multiplied. Here we describe the atmospheric carbon control simulator (ACCS) for the maintenance of plankton under controlled pCO2 conditions, designed for species sensitive to the physical disturbance introduced by the bubbling of cultures and for studies involving trophic interaction. The system consists of gas mixing and equilibration components coupled with large-volume atmospheric simulation chambers. These chambers allow gas exchange to counteract the changes in carbonate chemistry induced by the metabolic activity of the organisms. The system is relatively low cost, very flexible, and when used in conjunction with semi-continuous culture methods, it increases the density of organisms kept under realistic conditions, increases the allowable time interval between dilutions, and/or decreases the metabolically driven change in carbonate chemistry during these intervals. It accommodates a large number of culture vessels, which facilitate multi-trophic level studies and allow the tracking of variable responses within and across plankton populations to ocean acidification. It also includes components that increase the reliability of gas mixing systems using mass flow controllers.

Study of collective flows of protons and $$ \\pi^{{-}}_{}$$ π - -mesons in p+C, Ta and He+Li, C collisions at momenta of 4.2, 4.5 and 10 AGeV/c

DOE PAGES

Chkhaidze, L.; Chlachidze, G.; Djobava, T.; ...

2016-11-01

Collective flows of protons andmore » $$\\pi^{-}$$ -mesons are studied at the momenta of 4.2, 4.5 and 10AGeV/c for p+C, Ta and He+Li, C interactions. The data were obtained from the streamer chamber (SKM-200-GIBS) and from the Propane Bubble Chamber (PBC-500) systems utilized at JINR. A method of Danielewicz and Odyniec has been employed in determining a directed transverse flow of particles. The values of the transverse flow parameter and the strength of the anisotropic emission were defined for each interacting nuclear pair. It is found that the directed flows of protons and pions decrease with increasing the energy and the mass numbers of colliding nucleus pairs. The $$ \\pi^{{-}}_{}$$ -meson and proton flows exhibit opposite directions in all studied interactions, and the flows of protons are directed in the reaction plane. Lastly, the Ultra-relativistic Quantum Molecular Dynamical Model (UrQMD) coupled with the Statistical Multi-fragmentation Model (SMM), satisfactorily describes the obtained experimental results.« less

Combustion performance and heat transfer characterization of LOX/hydrocarbon type propellants, volume 1

NASA Technical Reports Server (NTRS)

Michel, R. W.

1983-01-01

A program to evaluate liquid oxygen and various hydrocarbon fuel as low cost alternative propellants suitable for future space transportation system applications is discussed. The emphasis of the program is directed toward low earth orbit maneuvering engine and reaction control engine systems. The feasibility of regeneratively cooling an orbit maneuvering thruster was analytically determined over a range of operating conditions from 100 to 1000 psia chamber pressure and 1000 to 10,000-1bF thrust, and specific design points were analyzed in detail for propane, methane, RP-1, ammonia, and ethanol; similar design point studies were performed for a filmcooled reaction control thruster. Heat transfer characteristics of propate were experimentally evaluated in heated tube tests. Forced convection heat transfer coefficients were determined over the range of fluid conditions encompassed by 450 to 1800 psia, -250 to +250 F, and 50 to 150 ft/sec, with wall temperatures from ambient to 1200 F. Seventy-seven hot firing tests were conducted with LOX/propane and LOC/ethanol, for a total duration of nearly 1400 seconds, using both heat sink and water-cooled calorimetric chambers.

Impact of Acoustic Standing Waves on Structural Responses: Reverberant Acoustic Testing (RAT) vs. Direct Field Acoustic Testing (DFAT)

NASA Technical Reports Server (NTRS)

Kolaini, Ali R.; Doty, Benjamin; Chang, Zensheu

2012-01-01

Loudspeakers have been used for acoustic qualification of spacecraft, reflectors, solar panels, and other acoustically responsive structures for more than a decade. Limited measurements from some of the recent speaker tests used to qualify flight hardware have indicated significant spatial variation of the acoustic field within the test volume. Also structural responses have been reported to differ when similar tests were performed using reverberant chambers. To address the impact of non-uniform acoustic field on structural responses, a series of acoustic tests were performed using a flat panel and a 3-ft cylinder exposed to the field controlled by speakers and repeated in a reverberant chamber. The speaker testing was performed using multi-input-single-output (MISO) and multi-input-multi-output (MIMO) control schemes with and without the test articles. In this paper the spatial variation of the acoustic field due to acoustic standing waves and their impacts on the structural responses in RAT and DFAT (both using MISO and MIMO controls for DFAT) are discussed in some detail.

Effect of aircraft-cabin altitude on passenger discomfort.

PubMed

Muhm, J Michael; Rock, Paul B; McMullin, Dianne L; Jones, Stephen P; Lu, I L; Eilers, Kyle D; Space, David R; McMullen, Aleksandra

2007-07-05

Acute mountain sickness occurs in some unacclimatized persons who travel to terrestrial altitudes at which barometric pressures are the same as those in commercial aircraft during flight. Whether the effects are similar in air travelers is unknown. We conducted a prospective, single-blind, controlled hypobaric-chamber study of adult volunteers to determine the effect of barometric pressures equivalent to terrestrial altitudes of 650, 4000, 6000, 7000, and 8000 ft (198, 1219, 1829, 2134, and 2438 m, respectively) above sea level on arterial oxygen saturation and the occurrence of acute mountain sickness and discomfort as measured by responses to the Environmental Symptoms Questionnaire IV during a 20-hour simulated flight. Among the 502 study participants, the mean oxygen saturation decreased with increasing altitude, with a maximum decrease of 4.4 percentage points (95% confidence interval, 3.9 to 4.9) at 8000 ft. Overall, acute mountain sickness occurred in 7.4% of the participants, but its frequency did not vary significantly among the altitudes studied. The frequency of reported discomfort increased with increasing altitude and decreasing oxygen saturation and was greater at 7000 to 8000 ft than at all the lower altitudes combined. Differences became apparent after 3 to 9 hours of exposure. Persons older than 60 years of age were less likely than younger persons and men were less likely than women to report discomfort. Four serious adverse events, 1 of which may have been related to the study exposures, and 15 adverse events, 9 of which were related to study exposures, were reported. Ascent from ground level to the conditions of 7000 to 8000 ft lowered oxygen saturation by approximately 4 percentage points. This level of hypoxemia was insufficient to affect the occurrence of acute mountain sickness but did contribute to the increased frequency of reports of discomfort in unacclimatized participants after 3 to 9 hours. (ClinicalTrials.gov number, NCT00326703 [ClinicalTrials.gov].). Copyright 2007 Massachusetts Medical Society.

Inner-ear decompression sickness: 'hubble-bubble' without brain trouble?

PubMed

Tremolizzo, Lucio; Malpieri, Massimo; Ferrarese, Carlo; Appollonio, Ildebrando

2015-06-01

Inner-ear decompression sickness (DCS) is an incompletely understood and increasingly recognized condition in compressed-air divers. Previous reports show a high association of inner-ear DCS with persistent foramen ovale (PFO), suggesting that a moderate-to-severe right-to-left shunt might represent a major predisposing factor, and more properly defining it as an event from arterial gas embolism (AGE). However, other conditions characterized by bubbles entering the arterial circulation, such as open-chamber cardiac surgery, do not produce inner-ear involvement, while sometimes damaging the brain extensively. Moreover, in other sites, such as the spinal cord, the prevailing mechanism for DCS is not AGE, but more likely local bubble formation with subsequent compression of venules and capillaries. Thus, AGE might be, more properly, a predisposing condition, neither sufficient, nor possibly even strictly necessary for inner-ear DCS. A 'two-hit hypothesis' has been proposed, implying a locally selective vulnerability of the inner ear to AGE. Modelled kinetics for gas removal are slower in the inner ear compared to the brain, leading to a supersaturated environment which allows bubbles to grow until they eventually obstruct the labyrinthine artery. Since this artery is relatively small, there is a low probability for a bubble to enter it; this might explain the disproportion between the high prevalence of PFO in the general population (25-30%) and the very low incidence of inner-ear DCS in compressed-air diving (approximately 0.005%). Furthermore, given that the labyrinthine artery usually originates either from the anterior inferior cerebellar artery, or directly from the basilar artery, shunting bubbles will more frequently swarm through the entire brain. In this case, however, the brain's much faster gas removal kinetics might allow for them to be reabsorbed without damaging brain tissue. In line with this scenario is the low probability (approx. 15%) of inner-ear DCS presenting with concomitant symptoms suggestive of brain involvement. Interestingly, PFO is a putative risk factor not only for DCS but also for ischaemic stroke, and it has been hypothesized that a predominantly silent ischaemic cerebral burden might represent a meaningful surrogate of end-organ damage in divers with PFO, with implications for stroke or cognitive decline. Here we report the case of a 44-year-old diving instructor (> 350 dives) who suffered from inner-ear DCS about 10 min after a routine dive (5 min/40 metres' fresh water (mfw), ascent 7.5 mfw·min⁻¹, stop 10 min/5 mfw), resulting in severe left cochlear/vestibular impairment (complete deafness and marked vertigo, only the latter slowly receding after a few hours). The patient was not recompressed. A few months later, transcranial Doppler ultrasonography demonstrated a moderate-to-severe shunt (> 30 bubbles), presumably due to a PFO (he refused confirmatory echocardiography), while a brain MRI (1.5 T) was reported as negative for both recent and remote lacunar infarcts (Figure 1). We believe this may be evidence that inner-ear DCS could occur while the brain is completely spared, not only clinically, but also at neuroimaging. This would support either of two hypotheses: (a) that the brain is indeed relatively protected from arterial bubbles that preferentially harm the inner ear where, however, they only rarely infiltrate, or (b) that direct bubble formation within the inner ear cannot be completely discarded, and that the elevated PFO-inner-ear DCS association might be, in this latter case, merely circumstantial. We favour the hypothesis that inner-ear DCS might be related to AGE in an anatomically vulnerable region. More precise data regarding the exact incidence of inner-ear involvement, isolating those subjects with moderate-to-severe shunt, should be obtained before exploring the risk-to-benefit ratio given by transcatheter occlusion of a PFO for prevention of inner-ear DCS; odds that could end up to be sensibly different with respect to other types of DCS presentation.

The test facility requirements for the thermal vacuum thermal balance test of the Cosmic Background Explorer Observatory

NASA Technical Reports Server (NTRS)

Milam, Laura J.

1990-01-01

The Cosmic Background Explorer Observatory (COBE) underwent a thermal vacuum thermal balance test in the Space Environment Simulator (SES). This was the largest and most complex test ever conducted at this facility. The 4 x 4 m (13 x 13 ft) spacecraft weighed approx. 2223 kg (4900 lbs) for the test. The test set up included simulator panels for the inboard solar array panels, simulator panels for the flight cowlings, Sun and Earth Sensor stimuli, Thermal Radio Frequency Shield heater stimuli and a cryopanel for thermal control in the Attitude Control System Shunt Dissipator area. The fixturing also included a unique 4.3 m (14 ft) diameter Gaseous Helium Cryopanel which provided a 20 K environment for the calibration of one of the spacecraft's instruments, the Differential Microwave Radiometer. This cryogenic panel caused extra contamination concerns and a special method was developed and written into the test procedure to prevent the high buildup of condensibles on the panel which could have led to backstreaming of the thermal vacuum chamber. The test was completed with a high quality simulated space environment provided to the spacecraft. The test requirements, test set up, and special fixturing are described.

Tracking performance with two breathing oxygen concentrations after high altitude rapid decompression

NASA Technical Reports Server (NTRS)

Nesthus, Thomas E.; Schiflett, Samuel G.; Oakley, Carolyn J.

1992-01-01

Current military aircraft Liquid Oxygen (LOX) systems supply 99.5 pct. gaseous Aviator's Breathing Oxygen (ABO) to aircrew. Newer Molecular Sieve Oxygen Generation Systems (MSOGS) supply breathing gas concentration of 93 to 95 pct. O2. The margin is compared of hypoxia protection afforded by ABO and MSOGS breathing gas after a 5 psi differential rapid decompression (RD) in a hypobaric research chamber. The barometric pressures equivalent to the altitudes of 46000, 52000, 56000, and 60000 ft were achieved from respective base altitudes in 1 to 1.5 s decompressions. During each exposure, subjects remained at the simulated peak altitude breathing either 100 or 94 pct. O2 with positive pressure for 60 s, followed by a rapid descent to 40000 ft. Subjects used the Tactical Life Support System (TLSS) for high altitude protection. Subcritical tracking task performance on the Performance Evaluation Device (PED) provided psychomotor test measures. Overall tracking task performance results showed no differences between the MSOGS breathing O2 concentration of 94 pct. and ABO. Significance RMS error differences were found between the ground level and base altitude trials compared to peak altitude trials. The high positive breathing pressures occurring at the peak altitudes explained the differences.

Research Technology

NASA Image and Video Library

1999-11-01

This photograph shows an overall view of the Solar Thermal Propulsion Test Facility at the Marshall Space Flight Center (MSFC). The 20-by 24-ft heliostat mirror, shown at the left, has dual-axis control that keeps a reflection of the sunlight on an 18-ft diameter concentrator mirror (right). The concentrator mirror then focuses the sunlight to a 4-in focal point inside the vacuum chamber, shown at the front of concentrator mirror. Researchers at MSFC have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than chemical a combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propell nt. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth-orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Characterization by optical and magnetic spectroscopy of a synthesized SiO2 thin film used for radiation detector

NASA Astrophysics Data System (ADS)

Abdelaziz, T. D.; Ezz-Eldin, F. M.

2017-09-01

This work reports the synthesis and characterization of silica glass prepared by sol-gel procedure and finds out the effects of doses of gamma irradiation on the steps route of the heat-treated sample at 600 and 1100 °C. Combined characterizations of the glassy samples have been carried out by optical absorption and electron paramagnetic resonance. Also, FT infrared absorption spectra have been measured for both the heat-treated samples before and after gamma irradiation. Optical absorption spectra have identified an absorption band at 212-215 nm beside a broad band at 230-265 nm and the correlation of E' center with heat-treatment and gamma irradiation have been followed. FT infrared absorption spectra indicate the bands within near IR region representing the vibrational modes due to water, OH and SiOH within the wavenumber range 2500-3700 cm-1 are affected by heat treatment due to the elimination of organic residue and amount of OH and water. ESR investigations confirm the results obtained from optical and FTIR measurements. It is concluded from the collective data that sol-gel silica glass can serve as acceptable candidate for gamma-rays irradiator and gamma chamber dosimetry.

Sinkhole progression at the Weeks Island, Louisiana, Strategic Petroleum Reserve (SPR) site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neal, J.T.; Bauer, S.J.; Ehgartner, B.L.

1995-11-01

A sinkhole measuring 11 m (36 ft) across and 9 m (30 ft) deep was first observed in alluvium overlying the Weeks Island, Louisiana, salt dome in May 1992, but it was about a year old, based on initial surface appearance and subsequent reverse extrapolation of growth rates. A second and much smaller sinkhole was identified in early 1995, nearly three years later. Their position directly over the edges of the SPR oil storage chamber, a former room-and-pillar salt mine, caused apprehension. The association of sinkholes over mines is well established and this occurrence suggested that groundwater influx undoubtedly wasmore » causing salt dissolution at shallow depth, and associated collapse of soil at the surface. Leaks of groundwater into other salt mines in Louisiana and elsewhere led to flooding and eventual abandonment (Coates et al., 1981). Consequently, much attention has been and continues to be given to characterizing these sinkholes, and to mitigation. This paper summarizes current engineering geologic concepts, and briefly describes diagnostic and risk mitigation efforts being conducted by the US Department of Energy, operator of the Strategic Petroleum Reserve (Bauer et al., 1994).« less

Test facility requirements for the thermal vacuum thermal balance test of the Cosmic Background Explorer Observatory

NASA Technical Reports Server (NTRS)

Milam, Laura J.

1991-01-01

The Cosmic Background Explorer Observatory (COBE) underwant a thermal vacuum thermal balance test in the Space Environment Simulator (SES). This was the largest and most complex test ever conducted at this facility. The 4 x 4 m (13 x 13 ft) spacecraft weighed approx. 2223 kg (4900 lbs) for the test. The test set up included simulator panels for the inboard solar array panels, simulator panels for the flight cowlings, Sun and Earth Sensor stimuli, Thermal Radio Frequency Shield heater stimuli and a cryopanel for thermal control in the Attitude Control System Shunt Dissipator area. The fixturing also included a unique 4.3 m (14 ft) diameter Gaseous Helium Cryopanel which provided a 20 K environment for the calibration of one of the spacecraft's instruments, the Differential Microwave Radiometer. This cryogenic panel caused extra contamination concerns and a special method was developed and written into the test procedure to prevent the high buildup of condensibles on the panel which could have led to backstreaming of the thermal vacuum chamber. The test was completed with a high quality simulated space environment provided to the spacecraft. The test requirements, test set up, and special fixturing are described.

Solar Thermal Propulsion Test Facility at MSFC

NASA Technical Reports Server (NTRS)

1999-01-01

This photograph shows an overall view of the Solar Thermal Propulsion Test Facility at the Marshall Space Flight Center (MSFC). The 20-by 24-ft heliostat mirror, shown at the left, has dual-axis control that keeps a reflection of the sunlight on an 18-ft diameter concentrator mirror (right). The concentrator mirror then focuses the sunlight to a 4-in focal point inside the vacuum chamber, shown at the front of concentrator mirror. Researchers at MSFC have designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket engine that produces lower thrust but has better thrust efficiency than chemical a combustion engine. MSFC turned to solar thermal propulsion in the early 1990s due to its simplicity, safety, low cost, and commonality with other propulsion systems. Solar thermal propulsion works by acquiring and redirecting solar energy to heat a propell nt. As part of MSFC's Space Transportation Directorate, the Propulsion Research Center serves as a national resource for research of advanced, revolutionary propulsion technologies. The mission is to move the Nation's capabilities beyond the confines of conventional chemical propulsion into an era of aircraft-like access to Earth-orbit, rapid travel throughout the solar system, and exploration of interstellar space.

Spectral variation of high power microwave pulse propagating in a self-generated plasma

NASA Technical Reports Server (NTRS)

Ren, A.; Kuo, S. P.; Kossey, Paul

1995-01-01

A systematic study to understand the spectral variation of a high power microwave pulse propagating in a self-generated plasma is carried out. It includes the theoretical formulation, experimental demonstration, and computer simulations and computer experiments. The experiment of pulse propagation is conducted in a vacuum chamber filled with dry air (approximately 0.2 torr); the chamber is made of a 2 ft. cube of Plexiglas. A rectangular microwave pulse (1 microsec pulse width and 3.27 GHz carrier frequency) is fed into the cube through an S band microwave horn placed at one side of the chamber. A second S-band horn placed at the opposite side of the chamber is used to receive the transmitted pulse. The spectra of the incident pulse and transmitted pulse are then compared. As the power of the incident pulse is only slightly (less than 15%) above the breakdown threshold power of the background air, the peak of the spectrum of the transmitted pulse is upshifted from the carrier frequency 3.27 GHz of the incident pulse. However, as the power of the incident pulse exceeds the breakdown threshold power of the background air by 30%, a different phenomenon appears. The spectrum of the transmitted pulse begins to have two peaks. One is upshifted and the other one downshifted from the single peak location of the incident pulse. The amount of frequency downshift is comparable to that of the upshifted frequency. A theoretical model describing the experiment of pulse propagation in a self-generated plasma is developed. There are excellent agreements between the experimental results and computer simulations based on this theoretical model, which is also used to further carry out computer experiments identifying the role of plasma introduced wave loss on the result of frequency downshift phenomenon.

Satellite Test Assistant Robot (STAR)

NASA Technical Reports Server (NTRS)

Mcaffee, D. A.; Kerrisk, D. J.; Johnson, K. R.

1993-01-01

A three-year, three-phase program to demonstrate the applicability of telerobotic technology to the testing of satellites and other spacecraft has been initiated. Specifically, the objectives are to design, fabricate, and install into the JPL 25-ft. Space Simulator (SS) a system that will provide the capability to view test articles from all directions in both the visible and infrared (IR) spectral regions, to automatically map the solar flux intensity over the entire work volume of the chamber, and to provide the capability for leak detection. The first year's work, which provides a vertically mobile viewing platform equipped with stereo cameras, will be discussed. Design constraints and system implementation approaches mandated by the requirements of thermal vacuum operation will be emphasized.

CAPRICE98: a balloon-borne magnetic spectrometer equipped with a gas RICH and a silicon calorimeter to study cosmic rays

NASA Astrophysics Data System (ADS)

Barbiellini, G.; Bartalucci, S.; Bellotti, R.; Bergström, D.; Bidoli, V.; Boezio, M.; Bonvicini, V.; Bravar, U.; Cafagna, F.; Carlson, P.; Casolino, M.; Ciacio, F.; Circella, M.; De Marzo, C.; De Pascale, M. P.; Finetti, N.; Francke, T.; Grinstein, S.; Hof, M.; Khalchukov, F.; Kremer, J.; Menn, W.; Mitchell, J. W.; Morselli, A.; Ormes, J. F.; Papini, P.; Piccardi, S.; Picozza, P.; Ricci, M.; Simon, M.; Schiavon, P.; Sparvoli, R.; Spillantini, P.; Stochaj, S. J.; Streitmatter, R. E.; Stephens, S. A.; Suffert, M.; Vacchi, A.; Weber, N.; Zampa, N.

2001-04-01

CAPRICE98 is a superconducting magnetic spectrometer, equipped with a gas RICH and a silicon calorimeter, launched from Ft. Sumner (USA), on the 28th of May 1998, by the WiZard collaboration. For the first time a gas RICH detector flew together with a silicon electromagnetic calorimeter, allowing mass resolved antiprotons, with E>18 GeV, to be detected. The detector configuration was completed by a time of flight for particle identification, and a set of three drift chambers for rigidity measurement. The science objectives are the study of antimatter in cosmic rays and the cosmic ray composition in the atmosphere with special focus on muons.

Chinese modify CZ-2/3 rocket boosters, focus on commercial launch market

NASA Astrophysics Data System (ADS)

Covault, C.

1985-07-01

A program underway in the People's Republic of China to modify the Titan-class CZ-2/3 satellite-launch and ICBM boosters is described on the basis of a recent visit to the manufacturing plant in Shanghai. The present two-stage CZ-2 and three-stage CZ-3 can place 5000 lbs in LEO or 3080 lbs in GEO, respectively, and are produced on a custom basis with a delivery time of about 2 yrs. Modifications introduced include 4 x 6-ft fins and a pogo-suppression system for the four-engine first stage and a steel support band for the combustion chamber of the 80-ton-thrust second-stage main engine.

Experimental test of the PCAC-hypothesis in charged current neutrino and antineutrino interactions on protons

NASA Astrophysics Data System (ADS)

Jones, G. T.; Jones, R. W. L.; Kennedy, B. W.; O'Neale, S. W.; Klein, H.; Morrison, D. R. O.; Schmid, P.; Wachsmuth, H.; Miller, D. B.; Mobayyen, M. M.; Wainstein, S.; Aderholz, M.; Hoffmann, E.; Katz, U. F.; Kern, J.; Schmitz, N.; Wittek, W.; Allport, P.; Myatt, G.; Radojicic, D.; Bullock, F. W.; Burke, S.

1987-03-01

Data obtained with the bubble chamber BEBC at CERN are used for the first significant test of Adler's prediction for the neutrino and antineutrino-proton scattering cross sections at vanishing four-momentum transfer squared Q 2. An Extended Vector Meson Dominance Model (EVDM) is applied to extrapolate Adler's prediction to experimentally accessible values of Q 2. The data show good agreement with Adler's prediction for Q 2→0 thus confirming the PCAC hypothesis in the kinematical region of high leptonic energy transfer ν>2 GeV. The good agreement of the data with the theoretical predictions also at higher Q 2, where the EVDM terms are dominant, also supports this model. However, an EVDM calculation without PCAC is clearly ruled out by the data.

Multiplicities of secondary hadrons produced in vp and overlinevp charged current interactions

NASA Astrophysics Data System (ADS)

Grässler, H.; Lanske, D.; Schulte, R.; Jones, G. T.; Middleton, R. P.; O'Neale, S. W.; Böckmann, K.; Gebel, W.; Geich-Gimbel, C.; Nellen, B.; Grant, A.; Klein, H.; Morrison, D. R. O.; Schmid, P.; Wachsmuth, H.; Chima, J. S.; Mobayyen, M. M.; Talebzadeh, M.; Villalobos-Baillie, O.; Aderholz, M.; Deck, L.; Schmitz, N.; Settles, R.; Wernhard, K. L.; Wittek, W.; Corrigan, G.; Myatt, G.; Radojicić, D.; Saitta, B.; Wells, J.; Aachen-Birmingham-Bonn-CERN-Imperial College-München (MPI)-Oxford Collaboration

1983-08-01

In an experiment with the hydrogen bubble chamber BEBC at CERN multiplicities of hadrons produced in νp and overlinevp interactions have been investigated. Results are presented on the multiplicities of charged hadrons and neutral pions, forward and backward multiplicities of charged hadrons and correlations between forward and backward multiplicities. Comparisons are made with hadronic reactions and e +e - annihilation. In the framework of the quark-parton model the data imply similar charged multiplicities for the fragments of a u- and a d-quark, and a larger multiplicities for the fragments of a uu- than for a ud-diquark. The correlation data suggest independent fragmentation of the quark and diquark for hadronic masses above ˜ 7 GeV and local charge compensation within an event.

Total cross sections ν μ and ḡn μcharged-current interactions between 20 and 200 GeV

NASA Astrophysics Data System (ADS)

Bosetti, P.; Deden, H.; Fritze, P.; Grässler, H.; Hasert, F. J.; Schulte, R.; Böckmann, K.; Kokott, Th.; Nellen, B.; Wünsch, B.; Cundy, D. C.; Grant, A.; Hulth, P. O.; Klein, H.; Morrison, D. R. O.; Pagiola, E.; Pape, L.; Peyrou, Ch.; Scott, W. G.; Wachsmuth, H.; Simopoulou, E.; Vayaki, A.; Barnham, K. W. J.; Butterworth, I.; Iaselli, G.; Miller, D. B.; Mobayyen, M.; Penfold, C.; Petrides, A.; Powell, K. J.; Albajar, C.; Perkins, D. H.; Radojicic, D.; Saitta, B.; Bolognese, T.; Tallini, B.; Velasco, J.; Vignaud, D.; Aachen-Bonn-Cern-Demokritos-London-Oxford-Saclay Collaboration

1982-03-01

Exposures of the Ne/H 2 filled Big European Bubble Chamber (BEBC) to a dichromatic neutrino (antineutrino) beam produced by 400 GeV protons of the CERN SPS yielded ∼ 3100 events with a negative, and ∼ 1100 with a positive, muon. The neutrino flux is determined from the muon flux in the shielding. Assuming a linear energy dependence of the cross section, the values {σ}/{E} between 20 and 200 GeV are found to be 0.657 ± 0.012 (stat.) ± 0.027 (syst.) and 0.309 ± 0.009 (stat.) ± 0.013 (syst.) cm 2 (GeV nucleon) -1, for neutrinos and antineutrinos, respectively. The scaling variable {q 2}/{E} decreases significantly with increasing energy both for neutrinos and antineutrinos.

Mars Greenhouses: Concepts and Challenges. Proceedings from a 1999 Workshop

NASA Technical Reports Server (NTRS)

Wheeler, Ray M. (Editor); Martin-Brennan, Cindy (Editor)

2000-01-01

Topic covered include :Plants on Mars: On the Next Mission and in the Long Term Future; Bubbles in the Rocks: Natural and Artificial Caves and Cavities as Like Support Structures; Challenges for Bioregenerative Life Support on Mars; Cost Effectiveness Issues; Low Pressure Systems for Plant Growth; Plant Responses to Rarified Atmospheres; Can CO2 be Used as a Pressurizing Gas for Mars Greenhouses?; Inflatable Habitats Technology Development; Development of an Inflatable Greenhouse for a Modular Crop Production System; Mars Inflatable Greenhouse Workshop; Design Needs for Mars Deployable Greenhouse; Preliminary Estimates of the Possibilities for Developing a Deployable Greenhouse for a Planetary Surface Mars; Low Pressure Greenhouse Concepts for Mars; Mars Greenhouse Study: Natural vs. Artificial Lighting; and Wire Culture for an Inflatable Mars Greenhouse and Other Future Inflatable Space Growth Chambers.

LECTURES ON PHYSICS, BIOPHYSICS, AND CHEMISTRY FOR HIGH SCHOOL SCIENCE TEACHERS GIVEN AT THE ERNEST O. LAWRENCE RADIATION LABORATORY, BERKELEY, CALIFORNIA, JUNE-AUGUST 1959

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calhoon, E.C.; Starring, P.W. eds.

1959-08-01

Lectures given at the Ernest 0. Lawrence Radiation Laboratory on physics, biophysics, and chemistry for high school science teachers are presented. Topics covered include a mathematics review, atomic physics, nuclear physics, solid-state physics, elementary particles, antiparticies, design of experiments, high-energy particle accelerators, survey of particle detectors, emulsion as a particle detector, counters used in high-energy physics, bubble chambers, computer programming, chromatography, the transuranium elements, health physics, photosynthesis, the chemistry and physics of virus, the biology of virus, lipoproteins and heart disease, origin and evolution of the solar system, the role of space satellites in gathering astronomical data, and radiation andmore » life in space. (M.C.G.)« less

Scattering and stopping of hadrons in nuclear matter

NASA Technical Reports Server (NTRS)

Strugalski, Z.

1985-01-01

It was observed, in the 180 litre xenon bubble chamber, that when hadrons with kinetic energy higher than the pion production threshold fall on a layer of nuclear matter - on an atomic nucleus in other words - in many cases they can pass through it without causing particles production but they are deflected through some deflection angles; if the energy is lower than a few GeV and the nuclear matter layer is thick enough, the hadrons can be stopped in it. The amount of the deflection at a given incident hadron energy varies with the way the hadron strikes the atomic nucleus; the probability of the occurrence of stopping depends on the incident hadron identity and energy, and on the way the hadron passed through the nucleus, as well.

A comparison of preservative-free diclofenac and preserved diclofenac eye drops after cataract surgery in patients with diabetic retinopathy.

PubMed

Yasuda, Kanako; Miyazawa, Akiko; Shimura, Masahiko

2012-06-01

The aim of this study was to compare the anti-inflammatory efficacy of preservative-free and preserved 0.1% diclofenac eye drops for the management of postoperative inflammation after cataract surgery in patients with nonproliferative diabetic retinopathy and in normal controls. Forty-two diabetic patients and 50 normal control patients who underwent small-incision phacoemulsification cataract surgery bilaterally received topical preservative-free diclofenac in 1 eye and preserved diclofenac in the other eye. The corrected distance visual acuity (CDVA) as determined by a logarithm of the minimum angle of resolution (logMAR) chart, intraocular pressure (IOP), foveal thickness (FT) using optical coherence tomography (OCT), and the anterior chamber flare (ACF) score measured with a laser flare cell meter were monitored for 12 weeks after surgery. In the eyes with diabetic retinopathy, there were no significant differences in CDVA, IOP, FT, and ACF score between the right and left eyes at the initial exam. After cataract surgery, changes in CDVA, IOP, and FT were not influenced by the preservative in the diclofenac eye drops. In contrast, the ACF score in the eyes treated with preserved diclofenac showed slower recovery from postoperative inflammation than the eyes treated with preservative-free diclofenac. In the normal control eyes, similar but milder changes were observed in each of the clinical parameters. Because preservative suppressed the anti-inflammatory efficacy of topical diclofenac after cataract surgery, preservative-free diclofenac may have an improved safety profile during postoperative treatment, especially in patients with diabetic retinopathy.

Observations and Models of Heat and Salt Generation at a Deepwater Gulf of Mexico Vent

NASA Astrophysics Data System (ADS)

Sweetman, A. K.; Bøe, C.; Reigstad, L. J.; Durand, D.

2011-12-01

CO2 capture and storage (CCS) is, at present, one of the most promising measures for immediate regulation of CO2 emissions, while non-petroleum energy sources are being sought. Norway has taken a leading role in developing and implementing CCS, whilst international conventions, such as London and OSPAR, and regulations (EU directives) are defining the regulatory framework for CCS, in particular, for CO2 storage in geological structures including those under the seabed. To implement sub-seabed CCS on a global scale it is first necessary to understand how leakage from a CCS reservoir will impact marine ecosystems. To quantify how deep-sea benthic ecosystems respond to elevated levels of CO2, we conducted 4 in-situ benthic chamber lander deployments in a Norwegian fjord at 350m depth in September 2011. During each lander deployment, sediments in one benthic respirometry chamber were exposed to elevated levels of CO2 acidified seawater (up to 20,000 μatm), while those in a control chamber were exposed to seawater bubbled with air. Each experiment lasted approximately 40 hours. In the CO2 exposed chambers, benthic oxygen demand (respiration) increased and was negatively linearly correlated to pH. While bacterial and archael abundance showed no significant difference between the CO2 exposed chambers and the controls, bacterial and archael abundance was exponentially correlated to benthic oxygen demand, implying that microbial communities played a large role in forcing the strong correlation between respiration and pH. In terms of the effects of CO2 on sediment infauna, more macrofauna burrowed to deeper sediment depths in the CO2 exposed chambers relative to the control to potentially flee the low pH conditions in the experimental treatment. No large differences were seen in Pielou's evenness (J') (a measure of stress in diversity metrics) or the expected number of species between the control and experimental treatments, suggesting that no short-term (< 40 hrs) impacts on infaunal diversity are likely to be seen during a CO2 leakage event. Overall, the results collectively show that sedimentary ecosystems may respond very rapidly to CO2 exposure from a leakage event, and these responses may be manifested by higher respiration, but not necessarily by changes in sediment microbial abundance and faunal diversity. Results on faunal carbon uptakes rates between the 2 treatments will also be presented.

Chaotic bubbling and nonstagnant foams.

PubMed

Tufaile, Alberto; Sartorelli, José Carlos; Jeandet, Philippe; Liger-Belair, Gerard

2007-06-01

We present an experimental investigation of the agglomeration of bubbles obtained from a nozzle working in different bubbling regimes. This experiment consists of a continuous production of bubbles from a nozzle at the bottom of a liquid column, and these bubbles create a two-dimensional (2D) foam (or a bubble raft) at the top of this column. The bubbles can assemble in various dynamically stable arrangement, forming different kinds of foams in a liquid mixture of water and glycerol, with the effect that the bubble formation regimes influence the foam obtained from this agglomeration of bubbles. The average number of bubbles in the foam is related to the bubble formation frequency and the bubble mean lifetime. The periodic bubbling can generate regular or irregular foam, while a chaotic bubbling only generates irregular foam.

Toward jet injection by continuous-wave laser cavitation.

PubMed

Berrospe-Rodriguez, Carla; Visser, Claas Willem; Schlautmann, Stefan; Rivas, David Fernandez; Ramos-Garcia, Ruben

2017-10-01

This is a study motivated by the need to develop a needle-free device for eliminating major global healthcare problems caused by needles. The generation of liquid jets by means of a continuous-wave laser, focused into a light absorbing solution, was studied with the aim of developing a portable and affordable jet injector. We designed and fabricated glass microfluidic devices, which consist of a chamber where thermocavitation is created and a tapered channel. The growth of a vapor bubble displaces and expels the liquid through the channel as a fast traveling jet. Different parameters were varied with the purpose of increasing the jet velocity. The velocity increases with smaller channel diameters and taper ratios, whereas larger chambers significantly reduce the jet speed. It was found that the initial position of the liquid-air meniscus interface and its dynamics contribute to increased jet velocities. A maximum velocity of 94±3  m/s for a channel diameter of D=120  μm, taper ratio n=0.25, and chamber length E=200  μm was achieved. Finally, agarose gel-based skin phantoms were used to demonstrate the potential of our devices to penetrate the skin. The maximum penetration depth achieved was ∼1  mm, which is sufficient to penetrate the stratum corneum and for most medical applications. A meta-analysis shows that larger injection volumes will be required as a next step to medical relevance for laser-induced jet injection techniques in general. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Approaching behavior of a pair of spherical bubbles in quiescent liquids

NASA Astrophysics Data System (ADS)

Sanada, Toshiyuki; Kusuno, Hiroaki

2015-11-01

Some unique motions related bubble-bubble interaction, such as equilibrium distance, wake induced lift force, have been proposed by theoretical analysis or numerical simulations. These motions are different from the solid spheres like DKT model (Drafting, Kissing and Tumbling). However, there is a lack of the experimental verification. In this study, we experimentally investigated the motion of a pair of bubbles initially positioned in-line configuration in ultrapure water or an aqueous surfactant solution. The bubble motion were observed by two high speed video cameras. The bubbles Reynolds number was ranged from 50 to 300 and bubbles hold the spherical shape in this range. In ultrapure water, initially the trailing bubble deviated from the vertical line on the leading bubble owing to the wake of the leading bubble. And then, the slight difference of the bubble radius changed the relative motion. When the trailing bubble slightly larger than the leading bubble, the trailing bubble approached to the leading bubble due to it's buoyancy difference. The bubbles attracted and collided only when the bubbles rising approximately side by side configuration. In addition, we will also discuss the motion of bubbles rising in an aqueous surfactant solution.

CFD Modeling of Chamber Filling in a Micro-Biosensor for Protein Detection

PubMed Central

Islamov, Meiirbek; Sypabekova, Marzhan; Kanayeva, Damira; Rojas-Solórzano, Luis

2017-01-01

Tuberculosis (TB) remains one of the main causes of human death around the globe. The mortality rate for patients infected with active TB goes beyond 50% when not diagnosed. Rapid and accurate diagnostics coupled with further prompt treatment of the disease is the cornerstone for controlling TB outbreaks. To reduce this burden, the existing gap between detection and treatment must be addressed, and dedicated diagnostic tools such as biosensors should be developed. A biosensor is a sensing micro-device that consists of a biological sensing element and a transducer part to produce signals in proportion to quantitative information about the binding event. The micro-biosensor cell considered in this investigation is designed to operate based on aptamers as recognition elements against Mycobacterium tuberculosis secreted protein MPT64, combined in a microfluidic-chamber with inlet and outlet connections. The microfluidic cell is a miniaturized platform with valuable advantages such as low cost of analysis with low reagent consumption, reduced sample volume, and shortened processing time with enhanced analytical capability. The main purpose of this study is to assess the flooding characteristics of the encapsulated microfluidic cell of an existing micro-biosensor using Computational Fluid Dynamics (CFD) techniques. The main challenge in the design of the microfluidic cell lies in the extraction of entrained air bubbles, which may remain after the filling process is completed, dramatically affecting the performance of the sensing element. In this work, a CFD model was developed on the platform ANSYS-CFX using the finite volume method to discretize the domain and solving the Navier–Stokes equations for both air and water in a Eulerian framework. Second-order space discretization scheme and second-order Euler Backward time discretization were used in the numerical treatment of the equations. For a given inlet–outlet diameter and dimensions of an in-house built cell chamber, different inlet liquid flow rates were explored to determine an appropriate flow condition to guarantee an effective venting of the air while filling the chamber. The numerical model depicted free surface waves as promoters of air entrainment that ultimately may explain the significant amount of air content in the chamber observed in preliminary tests after the filling process is completed. Results demonstrated that for the present design, against the intuition, the chamber must be filled with liquid at a modest flow rate to minimize free surface waviness during the flooding stage of the chamber. PMID:28972568

CFD Modeling of Chamber Filling in a Micro-Biosensor for Protein Detection.

PubMed

Islamov, Meiirbek; Sypabekova, Marzhan; Kanayeva, Damira; Rojas-Solórzano, Luis

2017-10-03

Tuberculosis (TB) remains one of the main causes of human death around the globe. The mortality rate for patients infected with active TB goes beyond 50% when not diagnosed. Rapid and accurate diagnostics coupled with further prompt treatment of the disease is the cornerstone for controlling TB outbreaks. To reduce this burden, the existing gap between detection and treatment must be addressed, and dedicated diagnostic tools such as biosensors should be developed. A biosensor is a sensing micro-device that consists of a biological sensing element and a transducer part to produce signals in proportion to quantitative information about the binding event. The micro-biosensor cell considered in this investigation is designed to operate based on aptamers as recognition elements against Mycobacterium tuberculosis secreted protein MPT64, combined in a microfluidic-chamber with inlet and outlet connections. The microfluidic cell is a miniaturized platform with valuable advantages such as low cost of analysis with low reagent consumption, reduced sample volume, and shortened processing time with enhanced analytical capability. The main purpose of this study is to assess the flooding characteristics of the encapsulated microfluidic cell of an existing micro-biosensor using Computational Fluid Dynamics (CFD) techniques. The main challenge in the design of the microfluidic cell lies in the extraction of entrained air bubbles, which may remain after the filling process is completed, dramatically affecting the performance of the sensing element. In this work, a CFD model was developed on the platform ANSYS-CFX using the finite volume method to discretize the domain and solving the Navier-Stokes equations for both air and water in a Eulerian framework. Second-order space discretization scheme and second-order Euler Backward time discretization were used in the numerical treatment of the equations. For a given inlet-outlet diameter and dimensions of an in-house built cell chamber, different inlet liquid flow rates were explored to determine an appropriate flow condition to guarantee an effective venting of the air while filling the chamber. The numerical model depicted free surface waves as promoters of air entrainment that ultimately may explain the significant amount of air content in the chamber observed in preliminary tests after the filling process is completed. Results demonstrated that for the present design, against the intuition, the chamber must be filled with liquid at a modest flow rate to minimize free surface waviness during the flooding stage of the chamber.

Probability of cavitation for single ultrasound pulses applied to tissues and tissue-mimicking materials

PubMed Central

Maxwell, Adam D.; Cain, Charles A.; Hall, Timothy L.; Fowlkes, J. Brian; Xu, Zhen

2012-01-01

In this article, the negative pressure values at which inertial cavitation consistently occurs in response to a single, 2-cycle, focused ultrasound pulse were measured in several media relevant to cavitation-based ultrasound therapy. The pulse was focused into a chamber containing one of the media, which included liquids, tissue-mimicking materials, and ex-vivo canine tissue. Focal waveforms were measured by two separate techniques using a fiber-optic hydrophone. Inertial cavitation was identified by high-speed photography in optically transparent media and an acoustic passive cavitation detector. The probability of cavitation (Pcav) for a single pulse as a function of peak negative pressure (p−) followed a sigmoid curve, with the probability approaching 1 when the pressure amplitude was sufficient. The statistical threshold (defined as Pcav = 0.5) was between p− = 26.0–30.0 MPa in all samples with a high water content, but varied between p− = 13.7 to > 36 MPa for other media. A model for radial cavitation bubble dynamics was employed to evaluate the behavior of cavitation nuclei at these pressure levels. A single bubble nucleus with an inertial cavitation threshold of p− = 28.2 MPa was estimated to have a 2.5 nm radius in distilled water. These data may be valuable for cavitation-based ultrasound therapy to predict the likelihood of cavitation at different pressure levels and dimensions of cavitation-induced lesions in tissue. PMID:23380152

Cell proliferation of Paramecium tetraurelia on a slow rotating clinostat

NASA Astrophysics Data System (ADS)

Sawai, Satoe; Mogami, Yoshihiro; Baba, Shoji A.

Paramecium is known to proliferate faster under microgravity conditions, and slower under hypergravity. Experiments using axenic culture medium have demonstrated that hypergravity affected directly on the proliferation of Paramecium itself. In order to assess the mechanisms underlying the physiological effects of gravity on cell proliferation, Paramecium tetraurelia was grown under clinorotation (2.5 rpm) and the time course of the proliferation was investigated in detail on the basis of the logistic analysis. On the basis of the mechanical properties of Paramecium, this slow rate of the rotation appears to be enough to simulate microgravity in terms of the randomization of the cell orientation with respect to gravity. P. tetraurelia was cultivated in a closed chamber in which cells were confined without air bubbles, reducing the shear forces and turbulences under clinorotation. The chamber is made of quartz and silicone rubber film; the former is for the optically-flat walls for the measurement of cell density by means of a non-invasive laser optical-slice method, and the latter for gas exchange. Because of the small dimension for culture space, Paramecium does not accumulate at the top of the chamber in spite of its known negative gravitactic behavior. We measured the cell density at regular time intervals without breaking the configuration of the chamber, and analyzed the proliferation parameters by fitting the data to a logistic equation. As a result, P. tetraurelia showed reduced proliferation under slow clinorotation. The saturation of the cell density as well as the maximum proliferation rate decreased, although we found no significant changes on the half maximal time for proliferation. We also found that the mean swimming velocity decreased under slow clinorotation. These results were not consistent with those under microgravity and fast rotating clinostat. This may suggest that randomization of the cell orientation performed by slow rotating clinostat has not the same effect on Paramecium as that under microgravity that may affect the proliferation as the result of the reduced cost of propulsion.

Methane Ebullition During Simulated Lake Expansion and Permafrost Degradation

NASA Astrophysics Data System (ADS)

Mazéas, O.; von Fischer, J. C.; Whelan, M.; Rhew, R.

2007-12-01

Methane, a potent greenhouse gas, is emitted by Arctic tundra and lakes. Ebullition, or bubbling, of methane from Arctic lakes has been shown to be a major transport mechanism from the sediment to the atmosphere, and ebullition rates are greatest near the edges of the lakes where active erosion is occurring. In regions of continuous permafrost, Arctic lakes have been expanding in recent decades, attributed to permafrost melting and development of thermokarst. Lake expansion occurs when the margins erode into water, supplying large amounts of organic rich material to the sediment-water interface. This allows carbon that was previously stored in the soil (active layer and permafrost) to become bioavailable and subject to decomposition. An increase in Arctic methane emissions as a result of permafrost thawing and lake expansion would constitute a positive feedback to Arctic warming. In order to better understand these processes, an experiment was initiated in July 2007 at the Barrow Environmental Observatory, Barrow, AK. Different layers of locally collected tundra soil were placed into incubation chambers at the bottom of a shallow (about 1 m deep) lake. Each experimental chamber consists of a bucket fixed underneath an inverted funnel, with a sampling port on top to capture and collect the emitted gases. Gas samples are analyzed for methane and carbon dioxide concentrations, as well as relevant isotopic compositions. Gas sampling has occurred at frequent intervals during the late summer and will continue through the early winter. Three replicates of each layer (active layer, seasonally frozen active layer and permafrost) were incubated, as well as an empty control chamber. An additional chamber containing thawed permafrost and cellulose-rich sawdust was placed for comparison, as cellulose is a major component of plant tissue and the fermentation of the cellulose should yield substrates for methanogenesis. Total production of methane versus organic carbon content of initial sample, kinetics of ebullition, and relative potential emissions from each tundra layer will be assessed.

Interaction mechanism of double bubbles in hydrodynamic cavitation

NASA Astrophysics Data System (ADS)

Li, Fengchao; Cai, Jun; Huai, Xiulan; Liu, Bin

2013-06-01

Bubble-bubble interaction is an important factor in cavitation bubble dynamics. In this paper, the dynamic behaviors of double cavitation bubbles driven by varying pressure field downstream of an orifice plate in hydrodynamic cavitation reactor are examined. The bubble-bubble interaction between two bubbles with different radii is considered. We have shown the different dynamic behaviors between double cavitation bubbles and a single bubble by solving two coupling nonlinear equations using the Runge-Kutta fourth order method with adaptive step size control. The simulation results indicate that, when considering the role of the neighbor smaller bubble, the oscillation of the bigger bubble gradually exhibits a lag in comparison with the single-bubble case, and the extent of the lag becomes much more obvious as time goes by. This phenomenon is more easily observed with the increase of the initial radius of the smaller bubble. In comparison with the single-bubble case, the oscillation of the bigger bubble is enhanced by the neighbor smaller bubble. Especially, the pressure pulse of the bigger bubble rises intensely when the sizes of two bubbles approach, and a series of peak values for different initial radii are acquired when the initial radius ratio of two bubbles is in the range of 0.9˜1.0. Although the increase of the center distance between two bubbles can weaken the mutual interaction, it has no significant influence on the enhancement trend. On the one hand, the interaction between two bubbles with different radii can suppress the growth of the smaller bubble; on the other hand, it also can enhance the growth of the bigger one at the same time. The significant enhancement effect due to the interaction of multi-bubbles should be paid more attention because it can be used to reinforce the cavitation intensity for various potential applications in future.

A Philippinite with an Unusually Large Bubble: Gas Pressure and Noble Gas Composition

NASA Astrophysics Data System (ADS)

Matsuda, J.; Maruoka, T.; Pinti, D. L.; Koeberl, C.

1995-09-01

Bubbles are common in tektites, but usually their sizes range up to only a few mm. They are most abundant in Muong Nong-type tektites. The gases contained in these bubbles are of terrestrial atmospheric composition, with pressures below 1 atm (e.g., [1]). The abundances of light noble gases (He, Ne) are controlled by diffusion from the atmosphere [2], and noble gases dissolved in tektite glass indicate that the glass solidified at atmospheric pressures equivalent to about 40 km altitude [3]. Large bubbles in splash-form tektites are rather rare. Thus, the finding that a philippinite (size: 6.0 x 4.5 cm; weight: 199.6 g) contains an unusually large bubble justified a detailed study. The volume of the bubble, which was confirmed by X-ray photography, was estimated at 5.4 cm^3, by comparing the density of this tektite (2.288 g/cm^3) to that of normal philippinites (2.438 g/cm^3). A device was specifically constructed for crushing the present sample under vacuum. The 10x10 cm cylindrical device has a piston that allows to gently crush the sample by turning a handle. Various disk spacers can be used to adjust the inner height to that of the sample. The device is made of stainless steel, yielding a low noble gas blank. The crushing device is connected to a purification line and a noble gas sector-type mass spectrometer (VG 5400) [4]. Before crushing, the complete tektite was wrapped in aluminum foil. A first crushing attempt, using stainless steel disk spacers, failed and resulted in damage to the steel spacers, indicating a high strength of the tektite. Using iron disk spacers resulted in an ambient pressure increase (probably due to hydrogen from the Fe) in the sample chamber. However, the noble gas blanks were negligible. The background pressure, at 2 x 10-4 Torr, increased to 3 x 10-4 Torr when the sample was crushed. From the volume of the crushing device and that of the bubble in the tektite, the total gas pressure in the bubble was estimated at about 1 x 10-4 atm. Part of the extracted gas was kept for total gas analysis, while the remainder has been purified for the noble gas measurements. Total amounts and isotopic ratios of all noble gases were measured. The amounts of Ar, Kr, and Xe close to the blank level, while those of He and Ne were about 3 to 4 orders of magnitude larger than the blank. The ^20Ne/^36Ar ratio in the bubble gas is more than 4 orders of magnitude higher than the atmospheric value, which is similar to the pattern previously observed in tektites [2,3,5]. The isotopic ratios of Ar, Kr and Xe were, within uncertainties, similar to those of the terrestrial atmosphere. However, the Ne isotopic ratios were significantly different from atmospheric values, and differ from the results reported in previous studies [2,5]. The Ne isotope data seem to lie on the mass fractionation line from the atmosphere in a ^20Ne/^22Ne vs. ^21Ne/^22Ne three isotope plot, suggesting that the Ne in the bubble has diffused in from the atmosphere. However, it is generally believed that the isotopic fractionation during a steady state is very small, and the observed Ne values are higher than those calculated from simple mass fractionation [6]. The high isotopic fractionation is likely to be associated with the non-equilibrium conditions prevailing during tektite formation. Acknowledgments: We are grateful to D. Heinlein for bringing the precious sample to our attention and for allowing its analysis. References: [1] Jessberger E. K. and Gentner W. (1972) EPSL, 14, 221-225. [2] Matsubara K. and Matsuda J. (1991) Meteoritics, 26, 217-220. [3] Matsuda J. et al. (1993) Meteoritics, 28, 586-599. [4] Maruoka T. and Matsuda J. (1995) J. Mass Spectrom. Soc. Jpn., 43, 1-8. [5] Hennecke et al. (1975) JGR, 80, 2931-2934. [6] Kaneoka I., EPSL, 48, 284-292.

Simulation of Mini-Magnetospheric Plasma Propulsion (M2P2) Interacting with an External Plasma Wind

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Euripides, P.; Ziemba, T.; Slough, J.; Giersch, L.

2003-01-01

Substantial progress has been made over the last year in the development of the laboratory Mini-Magnetospheric Plasma Propulsion (M2P2) prototype. The laboratory testing has shown that that the plasma can be produced at high neutral gas efficiency, at high temperatures (a few tens of eV) with excellent confinement up to the point where chamber wall interactions dominate the physics. This paper investigates the performance of the prototype as it is opposed by an external plasma acting as a surrogate for the solar wind. The experiments were performed in 5ft diameter by 6ft long vacuum chamber at the University of Washington. The solar wind source comprised of a 33 kWe arc jet attached to a 200 kWe inductively generated plasma source. The dual plasma sources allow the interaction to be studied for different power levels, shot duration and production method. It is shown that plasma from the solar wind source (SWS) is able to penetrate the field of the M2P2 magnetic when no plasma is present. With operation of the M2P2 plasma source at only 1.5 kWe, the penetration of the SWS even at the highest power of operation at 200 kWe is stopped. This deflection is shown to be greatly enhanced over that produced by the magnet alone. In addition it is shown that with the presence of the SWS, M2P2 is able to produce enhanced magnetized plasma production out to at least 10 magnet radii where the field strength is only marginally greater than the terrestrial field. The results are consistent with the initial predictions that kWe M2P2 systems would be able to deflect several hundred kWe plasma winds to produce enhanced propulsion for a spacecraft.

Exclusive Muon-Neutrino Charged Current Muon Plus Any Number of Protons Topologies In ArgoNeuT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Partyka, Kinga Anna

2013-01-01

Neutrinos remain among the least understood fundamental particles even after decades of study. As we enter the precision era o f neutrino measurements bigger and more sophisticated detectors have emerged. The leading candidate among them is a Liquid Argon Time Projection Chamber (LArTPC ) detector technology due to its bubble-like chamber imaging, superb background rejection and scalability. I t is a perfect candidate that w ill aim to answer the remaining questions of the nature o f neutrino and perhaps our existence. Studying neutrinos with a detector that employs detection via beautiful images o f neutrino interactions can be bothmore » illuminating and surprising. The analysis presented here takes the full advantage of the LArTPC power by exploiting the first topological analysis of charged current muon neutrino p + N p , muon and any number of protons, interactions with the ArgoNeuT LArTPC experiment on an argon target. The results presented here are the first that address the proton multiplicity at the vertex and the proton kinematics. This study also addresses the importance o f nuclear effects in neutrino interactions. Furthermore, the developed here reconstruction techniques present a significant step forward for this technology and can be employed in the future LArTPC detectors.« less

Design and Testing of a Shell-Flow Hollow-Fiber Venting Gas Trap

NASA Technical Reports Server (NTRS)

Bue, Grant C.; Cross, Cindy; Hansen, Scott; Vogel, Matthew; Dillon, Paul

2013-01-01

A Venting Gas Trap (VGT) was designed, built, and tested at NASA Johnson Space Center to eliminate dissolved and free gas from the circulating coolant loop of the Orion Environmental Control Life Support System. The VGT was downselected from two different designs. The VGT has robust operation, and easily met all the Orion requirements, especially size and weight. The VGT has a novel design with the gas trap made of a five-layer spiral wrap of porous hydrophobic hollow fibers that form a cylindrically shaped curtain terminated by a dome-shaped distal plug. Circulating coolant flows into the center of the cylindrical curtain and flows between the hollow fibers, around the distal plug, and exits the VGT outlet. Free gas is forced by the coolant flow to the distal plug and brought into contact with hollow fibers. The proximal ends of the hollow fibers terminate in a venting chamber that allows for rapid venting of the free gas inclusion, but passively limits the external venting from the venting chamber through two small holes in the event of a long-duration decompression of the cabin. The VGT performance specifications were verified in a wide range of flow rates, bubble sizes, and inclusion volumes. Long-duration and integrated Orion human tests of the VGT are also planned for the coming year.

A temperature-controlled photoelectrochemical cell for quantitative product analysis.

PubMed

Corson, Elizabeth R; Creel, Erin B; Kim, Youngsang; Urban, Jeffrey J; Kostecki, Robert; McCloskey, Bryan D

2018-05-01

In this study, we describe the design and operation of a temperature-controlled photoelectrochemical cell for analysis of gaseous and liquid products formed at an illuminated working electrode. This cell is specifically designed to quantitatively analyze photoelectrochemical processes that yield multiple gas and liquid products at low current densities and exhibit limiting reactant concentrations that prevent these processes from being studied in traditional single chamber electrolytic cells. The geometry of the cell presented in this paper enables front-illumination of the photoelectrode and maximizes the electrode surface area to electrolyte volume ratio to increase liquid product concentration and hence enhances ex situ spectroscopic sensitivity toward them. Gas is bubbled through the electrolyte in the working electrode chamber during operation to maintain a saturated reactant concentration and to continuously mix the electrolyte. Gaseous products are detected by an in-line gas chromatograph, and liquid products are analyzed ex situ by nuclear magnetic resonance. Cell performance was validated by examining carbon dioxide reduction on a silver foil electrode, showing comparable results both to those reported in the literature and identical experiments performed in a standard parallel-electrode electrochemical cell. To demonstrate a photoelectrochemical application of the cell, CO 2 reduction experiments were carried out on a plasmonic nanostructured silver photocathode and showed different product distributions under dark and illuminated conditions.

A temperature-controlled photoelectrochemical cell for quantitative product analysis

NASA Astrophysics Data System (ADS)

Corson, Elizabeth R.; Creel, Erin B.; Kim, Youngsang; Urban, Jeffrey J.; Kostecki, Robert; McCloskey, Bryan D.

2018-05-01

In this study, we describe the design and operation of a temperature-controlled photoelectrochemical cell for analysis of gaseous and liquid products formed at an illuminated working electrode. This cell is specifically designed to quantitatively analyze photoelectrochemical processes that yield multiple gas and liquid products at low current densities and exhibit limiting reactant concentrations that prevent these processes from being studied in traditional single chamber electrolytic cells. The geometry of the cell presented in this paper enables front-illumination of the photoelectrode and maximizes the electrode surface area to electrolyte volume ratio to increase liquid product concentration and hence enhances ex situ spectroscopic sensitivity toward them. Gas is bubbled through the electrolyte in the working electrode chamber during operation to maintain a saturated reactant concentration and to continuously mix the electrolyte. Gaseous products are detected by an in-line gas chromatograph, and liquid products are analyzed ex situ by nuclear magnetic resonance. Cell performance was validated by examining carbon dioxide reduction on a silver foil electrode, showing comparable results both to those reported in the literature and identical experiments performed in a standard parallel-electrode electrochemical cell. To demonstrate a photoelectrochemical application of the cell, CO2 reduction experiments were carried out on a plasmonic nanostructured silver photocathode and showed different product distributions under dark and illuminated conditions.

Visualization of airflow growing soap bubbles

NASA Astrophysics Data System (ADS)

Al Rahbi, Hamood; Bock, Matthew; Ryu, Sangjin

2016-11-01

Visualizing airflow inside growing soap bubbles can answer questions regarding the fluid dynamics of soap bubble blowing, which is a model system for flows with a gas-liquid-gas interface. Also, understanding the soap bubble blowing process is practical because it can contribute to controlling industrial processes similar to soap bubble blowing. In this study, we visualized airflow which grows soap bubbles using the smoke wire technique to understand how airflow blows soap bubbles. The soap bubble blower setup was built to mimic the human blowing process of soap bubbles, which consists of a blower, a nozzle and a bubble ring. The smoke wire was placed between the nozzle and the bubble ring, and smoke-visualized airflow was captured using a high speed camera. Our visualization shows how air jet flows into the growing soap bubble on the ring and how the airflow interacts with the soap film of growing bubble.

Double bubble with the big-bubble technique during deep anterior lamellar keratoplasty.

PubMed

Wise, Stephanie; Dubord, Paul; Yeung, Sonia N

2017-04-28

To report a case of intraoperative double bubble that formed during big-bubble DALK surgery in a patient with corneal scarring secondary to herpetic stromal keratitis. Case report. A 22 year old woman presented with a large corneal scar, likely secondary to previous herpetic stromal keratitis. She underwent big-bubble DALK surgery for visual rehabilitation. Intraoperatively, a mixed bubble with persistent type 2 bubble postoperatively was noted. The second bubble resorbed with clearance of the graft and good visual outcome after 6 weeks. This case report describes the unusual development of a mixed bubble during big-bubble DALK surgery. This graft cleared with resolution of the second bubble postoperatively without further surgical intervention.

X-1 aircraft in flight

NASA Technical Reports Server (NTRS)

1949-01-01

The first of the rocket-powered research aircraft, the X-1 (originally designated the XS-1), was a bullet-shaped airplane that was built by the Bell Aircraft Company for the US Air Force and the National Advisory Committee for Aeronautics (NACA). The mission of the X-1 was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier'. The first of the three X-1s was glide-tested at Pinecastle Field, FL, in early 1946. The first powered flight of the X-1 was made on Dec. 9, 1946, at Muroc Army Air Field (later redesignated Edwards Air Force Base) with Chalmers Goodlin, a Bell test pilot,at the controls. On Oct. 14, 1947, with USAF Captain Charles 'Chuck' Yeager as pilot, the aircraft flew faster than the speed of sound for the first time. Captain Yeager ignited the four-chambered XLR-11 rocket engines after being air-launched from under the bomb bay of a B-29 at 21,000 ft. The 6,000-lb thrust ethyl alcohol/liquid oxygen burning rockets, built by Reaction Motors, Inc., pushed him up to a speed of 700 mph in level flight. Captain Yeager was also the pilot when the X-1 reached its maximum speed of 957 mph. Another USAF pilot. Lt. Col. Frank Everest, Jr., was credited with taking the X-1 to its maximum altitude of 71,902 ft. Eighteen pilots in all flew the X-1s. The number three plane was destroyed in a fire before evermaking any powered flights. A single-place monoplane, the X-1 was 31 ft long, 10 ft high, and had a wingspan of 29 ft. It weighed 4,900 lb and carried 8,200 lb of fuel. It had a flush cockpit with a side entrance and no ejection seat. The following movie runs about 20 seconds, and shows several air-to-air views of X-1 Number 2 and its modified B-50 mothership. It begins with different angles of the X-1 in-flight while mated to the B-50's bomb bay, and ends showing the air-launch. The X-1 drops below the B-50, then accelerates away as the rockets ignite.

Hindrance Velocity Model for Phase Segregation in Suspensions of Poly-dispersed Randomly Oriented Spheroids

NASA Astrophysics Data System (ADS)

Faroughi, S. A.; Huber, C.

2015-12-01

Crystal settling and bubbles migration in magmas have significant effects on the physical and chemical evolution of magmas. The rate of phase segregation is controlled by the force balance that governs the migration of particles suspended in the melt. The relative velocity of a single particle or bubble in a quiescent infinite fluid (melt) is well characterized; however, the interplay between particles or bubbles in suspensions and emulsions and its effect on their settling/rising velocity remains poorly quantified. We propose a theoretical model for the hindered velocity of non-Brownian emulsions of nondeformable droplets, and suspensions of spherical solid particles in the creeping flow regime. The model is based on three sets of hydrodynamic corrections: two on the drag coefficient experienced by each particle to account for both return flow and Smoluchowski effects and a correction on the mixture rheology to account for nonlocal interactions between particles. The model is then extended for mono-disperse non-spherical solid particles that are randomly oriented. The non-spherical particles are idealized as spheroids and characterized by their aspect ratio. The poly-disperse nature of natural suspensions is then taken into consideration by introducing an effective volume fraction of particles for each class of mono-disperse particles sizes. Our model is tested against new and published experimental data over a wide range of particle volume fraction and viscosity ratios between the constituents of dispersions. We find an excellent agreement between our model and experiments. We also show two significant applications for our model: (1) We demonstrate that hindered settling can increase mineral residence time by up to an order of magnitude in convecting magma chambers. (2) We provide a model to correct for particle interactions in the conventional hydrometer test to estimate the particle size distribution in soils. Our model offers a greatly improved agreement with the results obtained with direct measurement methods such as laser diffraction.

Gender Consideration in Experiment Design for Airbrake in Prebreathe

NASA Technical Reports Server (NTRS)

Conkin, Johnny; Gernhardt, Michael I.; Dervay, Joseph P.

2007-01-01

If gender is a confounder of the decompression sickness (DCS) or venous gas emboli (VGE) outcomes of a proposed air break in oxygen prebreathe (PB) project, then decisions about the final experiment design must be made. We evaluated if the incidence of DCS and VGE from tests in altitude chambers over 20 years were different between men and women after resting and exercise prebreathe protocols. Nitrogen washout during PB is our primary risk mitigation strategy to prevent subsequent DCS and VGE in subjects. Bubbles in the pulmonary artery (venous blood) were detected from the precordial position using Doppler ultrasound bubble detectors. The subjects were monitored for VGE for four min at about 15 min intervals for the duration of the altitude exposure, with maximum bubble grade assigned a Spencer Grade of IV. There was no difference in DCS incidence between men and women in either PB protocol. The incidence of VGE and Grade IV VGE is statistically lower in women compared to men after resting PB. Even when 10 tests were compared with Mantel-Haenszel 2 where both men (n = 168) and women (n = 92) appeared, the p-value for VGE incidence was still significant at 0.03. The incidence of VGE and Grade IV VGE is not statistically lower in women compared to men after exercise PB. Even when six tests were compared with Mantel-Haenszel x2 where both men (n = 165) and women (n = 49) appeared, the p-value for VGE incidence was still not significant at 0.90. Our goal is to understand the risk of brief air breaks during PB without other confounding variables invalidating our conclusions. The cost to additionally account for the confounding role of gender on VGE outcome after resting PB is judged excessive. Our decision is to only evaluate air breaks in the exercise PB protocol. So there is no restriction to recruiting women as test subjects.

Experimental study on bubble dynamics and wall heat transfer arising from a single nucleation site at subcooled flow boiling conditions – Part 2: Data analysis on sliding bubble characteristics and associated wall heat transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yooa, Junsoo; Estrada-Perez, Carlos E.; Hassan, Yassin A.

In this second of two companion papers presents an analysis of sliding bubble and wall heat transfer parameters measured during subcooled boiling in a square, vertical, upward flow channel. Bubbles were generated only from a single nucleation site for better observation of both the sliding bubbles’ characteristics and their impact on wall heat transfer through optical measurement techniques. Specific interests include: (i) bubbles departure and subsequent growth while sliding, (ii) bubbles release frequency, (iii) coalescence of sliding bubbles, (iv) sliding bubbles velocity, (v) bubbles size distribution and (vi) wall heat transfer influenced by sliding bubbles. Our results showed that slidingmore » bubbles involve two distinct growth behaviors: (i) at low mass fluxes, sliding bubbles grew fast near the nucleation site, subsequently shrank, and then grew again, (ii) as mass flux increased, however, sliding bubbles grew more steadily. The bubbles originating from the single nucleation site coalesced frequently while sliding, which showed close relation with bubbles release frequency. The sliding bubble velocity near the nucleation site consistently decreased by increasing mass flux, while the observation often became reversed as the bubbles slid downstream due to the effect of interfacial drag. The sliding bubbles moved faster than the local liquid (i.e., ur<0) at low mass flux conditions, but it became reversed as the mass flux increased. The size distribution of sliding bubbles followed Gaussian distribution well both near and far from the nucleation site. The standard deviation of bubble size varied insignificantly through sliding compared to the changes in mean bubble size. Lastly, the sliding bubbles enhanced the wall heat transfer and the effect became more noticeable as inlet subcooling/mass flux decreased or wall heat flux increased. Particularly, the sliding bubble characteristics such as bubble growth behavior observed near the nucleation site played a dominant role in determining the ultimate level of wall heat transfer enhancement within the test channel.« less

Experimental study on bubble dynamics and wall heat transfer arising from a single nucleation site at subcooled flow boiling conditions – Part 2: Data analysis on sliding bubble characteristics and associated wall heat transfer

DOE PAGES

Yooa, Junsoo; Estrada-Perez, Carlos E.; Hassan, Yassin A.

2016-04-28

In this second of two companion papers presents an analysis of sliding bubble and wall heat transfer parameters measured during subcooled boiling in a square, vertical, upward flow channel. Bubbles were generated only from a single nucleation site for better observation of both the sliding bubbles’ characteristics and their impact on wall heat transfer through optical measurement techniques. Specific interests include: (i) bubbles departure and subsequent growth while sliding, (ii) bubbles release frequency, (iii) coalescence of sliding bubbles, (iv) sliding bubbles velocity, (v) bubbles size distribution and (vi) wall heat transfer influenced by sliding bubbles. Our results showed that slidingmore » bubbles involve two distinct growth behaviors: (i) at low mass fluxes, sliding bubbles grew fast near the nucleation site, subsequently shrank, and then grew again, (ii) as mass flux increased, however, sliding bubbles grew more steadily. The bubbles originating from the single nucleation site coalesced frequently while sliding, which showed close relation with bubbles release frequency. The sliding bubble velocity near the nucleation site consistently decreased by increasing mass flux, while the observation often became reversed as the bubbles slid downstream due to the effect of interfacial drag. The sliding bubbles moved faster than the local liquid (i.e., ur<0) at low mass flux conditions, but it became reversed as the mass flux increased. The size distribution of sliding bubbles followed Gaussian distribution well both near and far from the nucleation site. The standard deviation of bubble size varied insignificantly through sliding compared to the changes in mean bubble size. Lastly, the sliding bubbles enhanced the wall heat transfer and the effect became more noticeable as inlet subcooling/mass flux decreased or wall heat flux increased. Particularly, the sliding bubble characteristics such as bubble growth behavior observed near the nucleation site played a dominant role in determining the ultimate level of wall heat transfer enhancement within the test channel.« less

Bubble dynamics and bubble-induced turbulence of a single-bubble chain

NASA Astrophysics Data System (ADS)

Lee, Joohyoung; Park, Hyungmin

2016-11-01

In the present study, the bubble dynamics and liquid-phase turbulence induced by a chain of bubbles injected from a single nozzle have been experimentally investigated. Using a high-speed two-phase particle image velociemtry, measurements on the bubbles and liquid-phase velocity field are conducted in a transparent tank filled with water, while varying the bubble release frequency from 0.1 to 35 Hz. The tested bubble size ranges between 2.0-3.2 mm, and the corresponding bubble Reynolds number is 590-1100, indicating that it belongs to the regime of path instability. As the release frequency increases, it is found that the global shape of bubble dispersion can be classified into two regimes: from asymmetric (regular) to axisymmetric (irregular). In particular, at higher frequency, the wake vortices of leading bubbles cause an irregular behaviour of the following bubble. For the liquid phase, it is found that a specific trend on the bubble-induced turbulence appears in a strong relation to the above bubble dynamics. Considering this, we try to provide a theoretical model to estimate the liquid-phase turbulence induced by a chain of bubbles. Supported by a Grant funded by Samsung Electronics, Korea.

Space Science

NASA Image and Video Library

2003-04-09

The Eastman-Kodak mirror assembly is being tested for the James Webb Space Telescope (JWST) project at the X-Ray Calibration Facility at Marshall Space Flight Center (MSFC). In this photo, one of many segments of the mirror assembly is being set up inside the 24-ft vacuum chamber where it will undergo x-ray calibration tests. MSFC is supporting Goddard Space Flight Center (GSFC) in developing the JWST by taking numerous measurements to predict its future performance. The tests are conducted in a vacuum chamber cooled to approximate the super cold temperatures found in space. During its 27 years of operation, the facility has performed testing in support of a wide array of projects, including the Hubble Space Telescope (HST), Solar A, Chandra technology development, Chandra High Resolution Mirror Assembly and science instruments, Constellation X-Ray Mission, and Solar X-Ray Imager, currently operating on a Geostationary Operational Environment Satellite. The JWST is NASA's next generation space telescope, a successor to the Hubble Space Telescope, named in honor of NASA's second administrator, James E. Webb. It is scheduled for launch in 2010 aboard an expendable launch vehicle. It will take about 3 months for the spacecraft to reach its destination, an orbit of 940,000 miles in space.

Gas Bubble Migration and Trapping in Porous Media: Pore-Scale Simulation

NASA Astrophysics Data System (ADS)

Mahabadi, Nariman; Zheng, Xianglei; Yun, Tae Sup; van Paassen, Leon; Jang, Jaewon

2018-02-01

Gas bubbles can be naturally generated or intentionally introduced in sediments. Gas bubble migration and trapping affect the rate of gas emission into the atmosphere or modify the sediment properties such as hydraulic and mechanical properties. In this study, the migration and trapping of gas bubbles are simulated using the pore-network model extracted from the 3D X-ray image of in situ sediment. Two types of bubble size distribution (mono-sized and distributed-sized cases) are used in the simulation. The spatial and statistical bubble size distribution, residual gas saturation, and hydraulic conductivity reduction due to the bubble trapping are investigated. The results show that the bubble size distribution becomes wider during the gas bubble migration due to bubble coalescence for both mono-sized and distributed-sized cases. And the trapped bubble fraction and the residual gas saturation increase as the bubble size increases. The hydraulic conductivity is reduced as a result of the gas bubble trapping. The reduction in hydraulic conductivity is apparently observed as bubble size and the number of nucleation points increase.

Nonspherical laser-induced cavitation bubbles

NASA Astrophysics Data System (ADS)

Lim, Kang Yuan; Quinto-Su, Pedro A.; Klaseboer, Evert; Khoo, Boo Cheong; Venugopalan, Vasan; Ohl, Claus-Dieter

2010-01-01

The generation of arbitrarily shaped nonspherical laser-induced cavitation bubbles is demonstrated with a optical technique. The nonspherical bubbles are formed using laser intensity patterns shaped by a spatial light modulator using linear absorption inside a liquid gap with a thickness of 40μm . In particular we demonstrate the dynamics of elliptic, toroidal, square, and V-shaped bubbles. The bubble dynamics is recorded with a high-speed camera at framing rates of up to 300000 frames per second. The observed bubble evolution is compared to predictions from an axisymmetric boundary element simulation which provides good qualitative agreement. Interesting dynamic features that are observed in both the experiment and simulation include the inversion of the major and minor axis for elliptical bubbles, the rotation of the shape for square bubbles, and the formation of a unidirectional jet for V-shaped bubbles. Further we demonstrate that specific bubble shapes can either be formed directly through the intensity distribution of a single laser focus, or indirectly using secondary bubbles that either confine the central bubble or coalesce with the main bubble. The former approach provides the ability to generate in principle any complex bubble geometry.

Aspherical bubble dynamics and oscillation times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godwin, R.P.; Chapyak, E.J.; Noack, J.

1999-03-01

The cavitation bubbles common in laser medicine are rarely perfectly spherical and are often located near tissue boundaries, in vessels, etc., which introduce aspherical dynamics. Here, novel features of aspherical bubble dynamics are explored. Time-resolved experimental photographs and simulations of large aspect ratio (length:diameter {approximately}20) cylindrical bubble dynamics are presented. The experiments and calculations exhibit similar dynamics. A small high-pressure cylindrical bubble initially expands radially with hardly any axial motion. Then, after reaching its maximum volume, a cylindrical bubble collapses along its long axis with relatively little radial motion. The growth-collapse period of these very aspherical bubbles differs only sightlymore » from twice the Rayleigh collapse time for a spherical bubble with an equivalent maximum volume. This fact justifies using the temporal interval between the acoustic signals emitted upon bubble creation and collapse to estimate the maximum bubble volume. As a result, hydrophone measurements can provide an estimate of the bubble energy even for aspherical bubbles. The prolongation of the oscillation period of bubbles near solid boundaries relative to that of isolated spherical bubbles is also discussed.« less

Extreme conditions in a dissolving air nanobubble

NASA Astrophysics Data System (ADS)

Yasui, Kyuichi; Tuziuti, Toru; Kanematsu, Wataru

2016-07-01

Numerical simulations of the dissolution of an air nanobubble in water have been performed taking into account the effect of bubble dynamics (inertia of the surrounding liquid). The presence of stable bulk nanobubbles is not assumed in the present study because the bubble radius inevitably passes the nanoscale in the complete dissolution of a bubble. The bubble surface is assumed to be clean because attachment of hydrophobic materials on the bubble surface could considerably change the gas diffusion rate. The speed of the bubble collapse (the bubble wall speed) increases to about 90 m/s or less. The shape of a bubble is kept nearly spherical because the amplitude of the nonspherical component of the bubble shape is negligible compared to the instantaneous bubble radius. In other words, a bubble never disintegrates into daughter bubbles during the dissolution. At the final moment of the dissolution, the temperature inside a bubble increases to about 3000 K due to the quasiadiabatic compression. The bubble temperature is higher than 1000 K only for the final 19 ps. However, the Knudsen number is more than 0.2 for this moment, and the error associated with the continuum model should be considerable. In the final 2.3 ns, only nitrogen molecules are present inside a bubble as the solubility of nitrogen is the lowest among the gas species. The radical formation inside a bubble is negligible because the probability of nitrogen dissociation is only on the order of 10-15. The pressure inside a bubble, as well as the liquid pressure at the bubble wall, increases to about 5 GPa at the final moment of dissolution. The pressure is higher than 1 GPa for the final 0.7 ns inside a bubble and for the final 0.6 ns in the liquid at the bubble wall. The liquid temperature at the bubble wall increases to about 360 K from 293 K at the final stage of the complete dissolution.

Multiplicity distributions of charged hadrons in vp and charged current interactions

NASA Astrophysics Data System (ADS)

Jones, G. T.; Jones, R. W. L.; Kennedy, B. W.; Morrison, D. R. O.; Mobayyen, M. M.; Wainstein, S.; Aderholz, M.; Hantke, D.; Katz, U. F.; Kern, J.; Schmitz, N.; Wittek, W.; Borner, H. P.; Myatt, G.; Radojicic, D.; Burke, S.

1992-03-01

Using data on vp andbar vp charged current interactions from a bubble chamber experiment with BEBC at CERN, the multiplicity distributions of charged hadrons are investigated. The analysis is based on ˜20000 events with incident v and ˜10000 events with incidentbar v. The invariant mass W of the total hadronic system ranges from 3 GeV to ˜14 GeV. The experimental multiplicity distributions are fitted by the binomial function (for different intervals of W and in different intervals of the rapidity y), by the Levy function and the lognormal function. All three parametrizations give acceptable values for X 2. For fixed W, forward and backward multiplicities are found to be uncorrelated. The normalized moments of the charged multiplicity distributions are measured as a function of W. They show a violation of KNO scaling.

Total cross section for the γd-->π-pp reaction between 380 and 840 MeV

NASA Astrophysics Data System (ADS)

Asai, M.; Endo, I.; Harada, M.; Kasai, S.; Niki, K.; Sumi, Y.; Kato, S.; Maruyama, K.; Murata, Y.; Muto, M.; Yoshida, K.; Iwatani, K.; Hasai, H.; Ito, H.; Maki, T.; Rangacharyulu, C.; Shimizu, H.; Wada, Y.

1990-09-01

The total cross section for the γd-->π-pp reaction has been measured for incident photon energies from 380 to 840 MeV in steps of 10 MeV, with the best energy resolution attained so far. A large-acceptance detector was used to observe the reaction products. Overall uncertainties in the deduced cross sections are less than 9% (~4% statistical and ~8% systematic). The results are in excellent agreement with previous bubble chamber measurements and do not show any statistically significant structure which can be interpreted as evidence for the formation of dibaryon resonances. An upper limit at 95% confidence level of σpeakΓ<230 μb MeV is obtained for a resonance in the vicinity of photon energy 700 MeV (mass~2490 MeV).

Numerical investigation of cavitation flow inside spool valve with large pressure drop

NASA Astrophysics Data System (ADS)

Deng, Jian; Pan, Dingyi; Xie, Fangfang; Shao, Xueming

2015-12-01

Spool valves play an important role in fluid power system. Cavitation phenomena happen frequently inside the spool valves, which cause structure damages, noise and lower down hydrodynamic performance. A numerical tools incorporating the cavitation model, are developed to predict the flow structure and cavitation pattern in the spool valve. Two major flow states in the spool valve chamber, i.e. flow-in and flow-out, are studies. The pressure distributions along the spool wall are first investigated, and the results agree well with the experimental data. For the flow-in cases, the local pressure at the throttling area drops much deeper than the pressure in flow-out cases. Meanwhile, the bubbles are more stable in flow-in cases than those in flow-out cases, which are ruptured and shed into the downstream.

The dynamics of histotripsy bubbles

NASA Astrophysics Data System (ADS)

Kreider, Wayne; Bailey, Michael R.; Sapozhnikov, Oleg A.; Khokhlova, Vera A.; Crum, Lawrence A.

2011-09-01

Histotripsy describes treatments in which high-amplitude acoustic pulses are used to excite bubbles and erode tissue. Though tissue erosion can be directly attributed to bubble activity, the genesis and dynamics of bubbles remain unclear. Histotripsy lesions that show no signs of thermal coagulative damage have been generated with two different acoustic protocols: relatively long acoustic pulses that produce local boiling within milliseconds and relatively short pulses that are higher in amplitude but likely do not produce boiling. While these two approaches are often distinguished as `boiling' versus `cavitation', such labels can obscure similarities. In both cases, a bubble undergoes large changes in radius and vapor is transported into and out of the bubble as it oscillates. Moreover, observations from both approaches suggest that bubbles grow to a size at which they cease to collapse violently. In order to better understand the dynamics of histotripsy bubbles, a single-bubble model has been developed that couples acoustically excited bubble motions to the thermodynamic state of the surrounding liquid. Using this model for bubbles exposed to histotripsy sound fields, simulations suggest that two mechanisms can act separately or in concert to lead to the typically observed bubble growth. First, nonlinear acoustic propagation leads to the evolution of shocks and an asymmetry in the positive and negative pressures that drive bubble motion. This asymmetry can have a rectifying effect on bubble oscillations whereby the bubble grows on average during each acoustic cycle. Second, vapor transport to/from the bubble tends to produce larger bubbles, especially at elevated temperatures. Vapor transport by itself can lead to rectified bubble growth when the ambient temperature exceeds 100 °C (`boiling') or local heating in the vicinity of the bubble leads to a superheated boundary layer.

Vapor Bubbles

NASA Astrophysics Data System (ADS)

Prosperetti, Andrea

2017-01-01

This article reviews the fundamental physics of vapor bubbles in liquids. Work on bubble growth and condensation for stationary and translating bubbles is summarized and the differences with bubbles containing a permanent gas stressed. In particular, it is shown that the natural frequency of a vapor bubble is proportional not to the inverse radius, as for a gas bubble, but to the inverse radius raised to the power 2/3. Permanent gas dissolved in the liquid diffuses into the bubble with strong effects on its dynamics. The effects of the diffusion of heat and mass on the propagation of pressure waves in a vaporous bubbly liquid are discussed. Other topics briefly touched on include thermocapillary flow, plasmonic nanobubbles, and vapor bubbles in an immiscible liquid.

Anti-Bubbles

NASA Astrophysics Data System (ADS)

Tufaile, Alberto; Sartorelli, José Carlos

2003-08-01

An anti-bubble is a striking kind of bubble in liquid that seemingly does not comply the buoyancy, and after few minutes it disappears suddenly inside the liquid. Different from a simple air bubble that rises directly to the liquid surface, an anti-bubble wanders around in the fluid due to its slightly lesser density than the surrounding liquid. In spite of this odd behavior, an anti-bubble can be understood as the opposite of a conventional soap bubble in air, which is a shell of liquid surrounding air, and an anti-bubble is a shell of air surrounding a drop of the liquid inside the liquid. Two-phase flow has been a subject of interest due to its relevance to process equipment for contacting gases and liquids applied in industry. A chain of bubbles rising in a liquid formed from a nozzle is a two-phase flow, and there are certain conditions in which spherical air shells, called anti-bubbles, are produced. The purpose of this work is mainly to note the existence of anti-bubbling regime as a sequel of a bubbling system. We initially have presented the experimental apparatus. After this we have described the evolution of the bubbling regimes, and emulated the effect of bubbling coalescence with simple maps. Then is shown the inverted dripping as a consequence of the bubble coalescence, and finally the conditions for anti-bubble formation.

Cognitive Performance Effects of Bilastine 20 mg During 6 Hours at 8000 ft Cabin Altitude.

PubMed

Valk, Pierre J L; Simons, Ries; Jetten, Andrea M; Valiente, Román; Labeaga, Luis

2016-07-01

Bilastine is a new oral, second generation antihistamine used in the symptomatic treatment of allergic rhinoconjunctivitis and urticaria. It is considered a nonsedating antihistamine and might be recommended for use in pilots, pending research on the effects on flying-related performance under hypobaric conditions that prevail in an airliner. We assessed the effects of a single dose of bilastine 20 mg on alertness and complex task performance of healthy volunteers in a hypobaric chamber at 75.2 kPa (8000 ft/2438 m cabin altitude). In a randomized, double-blind, crossover study, 24 volunteers received a single dose of bilastine 20 mg, hydroxyzine 50 mg (active control), and placebo. Using the Vigilance and Tracking Task, Multi-Attribute Task Battery, and Stanford Sleepiness Scale, assessments were made before and up to 6 h after intake of the study medication. Bilastine 20 mg had no impairing effects on sleepiness levels, vigilance, or complex task performance for up to 6 h post-dose. Hydroxyzine 50 mg (active control) was associated with significant sleepiness and impaired performance across this time period, confirming the sensitivity of the tests. Bilastine 20 mg did not cause sleepiness or impaired performance on tasks related to flying. It is anticipated that a single dose of bilastine 20 mg will not affect flying performance. Bilastine may provide a safe therapeutic alternative for pilots suffering from allergic rhinitis or urticaria. Our findings might also have implications for the treatment of allergic disorders of personnel involved in other safety-sensitive jobs. Valk PJL, Simons R, Jetten AM, Valiente R, Labeaga L. Cognitive performance effects of bilastine 20 mg during 6 hours at 8000 ft cabin altitude. Aerosp Med Hum Perform. 2016; 87(7):622-627.

Monte Carlo simulation of spectral reflectance and BRDF of the bubble layer in the upper ocean.

PubMed

Ma, Lanxin; Wang, Fuqiang; Wang, Chengan; Wang, Chengchao; Tan, Jianyu

2015-09-21

The presence of bubbles can significantly change the radiative properties of seawater and these changes will affect remote sensing and underwater target detection. In this work, the spectral reflectance and bidirectional reflectance characteristics of the bubble layer in the upper ocean are investigated using the Monte Carlo method. The Hall-Novarini (HN) bubble population model, which considers the effect of wind speed and depth on the bubble size distribution, is used. The scattering coefficients and the scattering phase functions of bubbles in seawater are calculated using Mie theory, and the inherent optical properties of seawater for wavelengths between 300 nm and 800 nm are related to chlorophyll concentration (Chl). The effects of bubble coating, Chl, and bubble number density on the spectral reflectance of the bubble layer are studied. The bidirectional reflectance distribution function (BRDF) of the bubble layer for both normal and oblique incidence is also investigated. The results show that bubble populations in clear waters under high wind speed conditions significantly influence the reflection characteristics of the bubble layer. Furthermore, the contribution of bubble populations to the reflection characteristics is mainly due to the strong backscattering of bubbles that are coated with an organic film.

Possible high sonic velocity due to the inclusion of gas bubbles in water

NASA Astrophysics Data System (ADS)

Banno, T.; Mikada, H.; Goto, T.; Takekawa, J.

2010-12-01

If formation water becomes multi-phase by inclusion of gas bubbles, sonic velocities would be strongly influenced. In general, sonic velocities are knocked down due to low bulk moduli of the gas bubbles. However, sonic velocities may increase depending on the size of gas bubbles, when the bubbles in water or other media oscillate due to incoming sonic waves. Sonic waves are scattered by the bubbles and the superposition of the incoming and the scattered waves result in resonant-frequency-dependent behavior. The phase velocity of sonic waves propagating in fluids containing bubbles, therefore, probably depends on their frequencies. This is a typical phenomenon called “wave dispersion.” So far we have studied about the bubble impact on sonic velocity in bubbly media, such as the formation that contains gas bubbles. As a result, it is shown that the bubble resonance effect is a key to analyze the sonic phase velocity increase. Therefore to evaluate the resonance frequency of bubbles is important to solve the frequency response of sonic velocity in formations having bubbly fluids. There are several analytical solutions of the resonance frequency of bubbles in water. Takahira et al. (1994) derived a equation that gives us the resonance frequency considering bubble - bubble interactions. We have used this theory to calculate resonance frequency of bubbles at the previous work. However, the analytical solution of the Takahira’s equation is based on several assumptions. Therefore we used a numerical approach to calculate the bubble resonance effect more precisely in the present study. We used the boundary element method (BEM) to reproduce a bubble oscillation in incompressible liquid. There are several reasons to apply the BEM. Firstly, it arrows us to model arbitrarily sets and shapes of bubbles. Secondly, it is easy to use the BEM to reproduce a boundary-surface between liquid and gas. The velocity potential of liquid surrounding a bubble satisfies the Laplace equation when the liquid is supposed to be incompressible. We got the boundary integral equation from the Laplace equation and solved the boundary integral equation by the BEM. Then, we got the gradient of the velocity potential from the BEM. We used this gradient to get time derivative of the velocity potential from the Bernouii’s equation. And we used the second order Adams-Bashforth method to execute time integration of the velocity potential. We conducted this scheme iteratively to calculate a bubble oscillation. At each time step, we input a pressure change as a sinusoidal wave. As a result, we observed a bubble oscillation following the pressure frequency. We also evaluated the resonance frequency of a bubble by changing the pressure frequency. It showed a good agreement with the analytical solution described above. Our future work is to extend the calculation into plural bubbles condition. We expect that interaction between bubbles becomes strong and resonance frequency of bubbles becomes small when distance between bubbles becomes small.

Test Capabilities and Recent Experiences in the NASA Langley 8-Foot High Temperature Tunnel

NASA Technical Reports Server (NTRS)

Hodge, Jeffrey S.; Harvin, Stephen F.

2000-01-01

The NASA Langley 8-Foot High Temperature Tunnel is a combustion-heated hypersonic blowdown-to-atmosphere wind tunnel that provides flight enthalpy simulation for Mach numbers of 4, 5, and 7 through an altitude range from 50,000 to 120,000 feet. The open-.jet test section is 8-ft. in diameter and 12-ft. long. The test section will accommodate large air-breathing hypersonic propulsion systems as well as structural and thermal protection system components. Stable wind tunnel test conditions can be provided for 60 seconds. Additional test capabilities are provided by a radiant heater system used to simulate ascent or entry heating profiles. The test medium is the combustion products of air and methane that are burned in a pressurized combustion chamber. Oxygen is added to the test medium for air-breathing propulsion tests so that the test gas contains 21 percent molar oxygen. The facility was modified extensively in the late 1980's to provide airbreathing propulsion testing capability. In this paper, a brief history and general description of the facility are presented along with a discussion of the types of supported testing. Recently completed tests are discussed to explain the capabilities this facility provides and to demonstrate the experience of the staff.

Bubbles in an acoustic field: an overview.

PubMed

Ashokkumar, Muthupandian; Lee, Judy; Kentish, Sandra; Grieser, Franz

2007-04-01

Acoustic cavitation is the fundamental process responsible for the initiation of most of the sonochemical reactions in liquids. Acoustic cavitation originates from the interaction between sound waves and bubbles. In an acoustic field, bubbles can undergo growth by rectified diffusion, bubble-bubble coalescence, bubble dissolution or bubble collapse leading to the generation of primary radicals and other secondary chemical reactions. Surface active solutes have been used in association with a number of experimental techniques in order to isolate and understand these activities. A strobe technique has been used for monitoring the growth of a single bubble by rectified diffusion. Multibubble sonoluminescence has been used for monitoring the growth of the bubbles as well as coalescence between bubbles. The extent of bubble coalescence has also been monitored using a newly developed capillary technique. An overview of the various experimental results has been presented in order to highlight the complexities involved in acoustic cavitation processes, which on the other hand arise from a simple, mechanical interaction between sound waves and bubbles.

Improvement of ore recovery efficiency in a flotation column cell using ultra-sonic enhanced bubbles

NASA Astrophysics Data System (ADS)

Filippov, L. O.; Royer, J. J.; Filippova, I. V.

2017-07-01

The ore process flotation technique is enhanced by using external ultra-sonic waves. Compared to the classical flotation method, the application of ultrasounds to flotation fluids generates micro-bubbles by hydrodynamic cavitation. Flotation performances increase was modelled as a result of increased probabilities of the particle-bubble attachment and reduced detachment probability under sonication. A simplified analytical Navier-Stokes model is used to predict the effect of ultrasonic waves on bubble behavior. If the theory is verified by experimentation, it predicts that the ultrasonic waves would create cavitation micro-bubbles, smaller than the flotation bubble added by the gas sparger. This effect leads to increasing the number of small bubbles in the liquid which promote particle-bubble attachment through coalescence between bubbles and micro-bubbles. The decrease in the radius of the flotation bubbles under external vibration forces has an additional effect by enhancing the bubble-particle collision. Preliminary results performed on a potash ore seem to confirm the theory.

Bubbles with shock waves and ultrasound: a review.

PubMed

Ohl, Siew-Wan; Klaseboer, Evert; Khoo, Boo Cheong

2015-10-06

The study of the interaction of bubbles with shock waves and ultrasound is sometimes termed 'acoustic cavitation'. It is of importance in many biomedical applications where sound waves are applied. The use of shock waves and ultrasound in medical treatments is appealing because of their non-invasiveness. In this review, we present a variety of acoustics-bubble interactions, with a focus on shock wave-bubble interaction and bubble cloud phenomena. The dynamics of a single spherically oscillating bubble is rather well understood. However, when there is a nearby surface, the bubble often collapses non-spherically with a high-speed jet. The direction of the jet depends on the 'resistance' of the boundary: the bubble jets towards a rigid boundary, splits up near an elastic boundary, and jets away from a free surface. The presence of a shock wave complicates the bubble dynamics further. We shall discuss both experimental studies using high-speed photography and numerical simulations involving shock wave-bubble interaction. In biomedical applications, instead of a single bubble, often clouds of bubbles appear (consisting of many individual bubbles). The dynamics of such a bubble cloud is even more complex. We shall show some of the phenomena observed in a high-intensity focused ultrasound (HIFU) field. The nonlinear nature of the sound field and the complex inter-bubble interaction in a cloud present challenges to a comprehensive understanding of the physics of the bubble cloud in HIFU. We conclude the article with some comments on the challenges ahead.

Bubbles with shock waves and ultrasound: a review

PubMed Central

Ohl, Siew-Wan; Klaseboer, Evert; Khoo, Boo Cheong

2015-01-01

The study of the interaction of bubbles with shock waves and ultrasound is sometimes termed ‘acoustic cavitation'. It is of importance in many biomedical applications where sound waves are applied. The use of shock waves and ultrasound in medical treatments is appealing because of their non-invasiveness. In this review, we present a variety of acoustics–bubble interactions, with a focus on shock wave–bubble interaction and bubble cloud phenomena. The dynamics of a single spherically oscillating bubble is rather well understood. However, when there is a nearby surface, the bubble often collapses non-spherically with a high-speed jet. The direction of the jet depends on the ‘resistance' of the boundary: the bubble jets towards a rigid boundary, splits up near an elastic boundary, and jets away from a free surface. The presence of a shock wave complicates the bubble dynamics further. We shall discuss both experimental studies using high-speed photography and numerical simulations involving shock wave–bubble interaction. In biomedical applications, instead of a single bubble, often clouds of bubbles appear (consisting of many individual bubbles). The dynamics of such a bubble cloud is even more complex. We shall show some of the phenomena observed in a high-intensity focused ultrasound (HIFU) field. The nonlinear nature of the sound field and the complex inter-bubble interaction in a cloud present challenges to a comprehensive understanding of the physics of the bubble cloud in HIFU. We conclude the article with some comments on the challenges ahead. PMID:26442143

Bubble dynamics in a standing sound field: the bubble habitat.

PubMed

Koch, P; Kurz, T; Parlitz, U; Lauterborn, W

2011-11-01

Bubble dynamics is investigated numerically with special emphasis on the static pressure and the positional stability of the bubble in a standing sound field. The bubble habitat, made up of not dissolving, positionally and spherically stable bubbles, is calculated in the parameter space of the bubble radius at rest and sound pressure amplitude for different sound field frequencies, static pressures, and gas concentrations of the liquid. The bubble habitat grows with static pressure and shrinks with sound field frequency. The range of diffusionally stable bubble oscillations, found at positive slopes of the habitat-diffusion border, can be increased substantially with static pressure.

How many bubbles in your glass of bubbly?

PubMed

Liger-Belair, Gérard

2014-03-20

The issue about how many carbon dioxide bubbles are likely to nucleate in a glass of champagne (or bubbly) is of concern for sommeliers, wine journalists, experienced tasters, and any open minded physical chemist wondering about complex phenomena at play in a glass of bubbly. The whole number of bubbles likely to form in a single glass is the result of the fine interplay between dissolved CO2, tiny gas pockets trapped within particles acting as bubble nucleation sites, and ascending bubble dynamics. Based on theoretical models combining ascending bubble dynamics and mass transfer equations, the falsely naı̈ve question of how many bubbles are likely to form per glass is discussed in the present work. A theoretical relationship is derived, which provides the whole number of bubbles likely to form per glass, depending on various parameters of both the wine and the glass itself.

Soap bubbles in analytical chemistry. Conductometric determination of sub-parts per million levels of sulfur dioxide with a soap bubble.

PubMed

Kanyanee, Tinakorn; Borst, Walter L; Jakmunee, Jaroon; Grudpan, Kate; Li, Jianzhong; Dasgupta, Purnendu K

2006-04-15

Soap bubbles provide a fascinating tool that is little used analytically. With a very low liquid volume to surface area ratio, a soap bubble can potentially provide a very useful interface for preconcentration where mass transfer to an interfacial surface is important. Here we use an automated system to create bubbles of uniform size and film thickness. We utilize purified Triton-X 100, a nonionic surfactant, to make soap bubbles. We use such bubbles as a gas-sampling interface. Incorporating hydrogen peroxide into the bubble provides a system where electrical conductance increases as the bubble is exposed to low concentrations of sulfur dioxide gas. We theoretically derive the conductance of a hollow conducting spherical thin film with spherical cap electrodes. We measure the film thickness by incorporating a dye in the bubble making solution and laser transmission photometry and find that it agrees well with the geometrically computed thickness. With the conductance of the bubble-making soap solution being measured by conventional methods, we show that the measured values of the bubble conductance with known bubble and electrode dimensions closely correspond to the theoretically computed value. Finally, we demonstrate that sub-ppm levels of SO(2) can readily be detected by the conductivity change of a hydrogen peroxide-doped soap bubble, measured in situ, when the gas flows around the bubble.

Acoustic bubble removal method

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Elleman, D. D.; Wang, T. G. (Inventor)

1983-01-01

A method is described for removing bubbles from a liquid bath such as a bath of molten glass to be used for optical elements. Larger bubbles are first removed by applying acoustic energy resonant to a bath dimension to drive the larger bubbles toward a pressure well where the bubbles can coalesce and then be more easily removed. Thereafter, submillimeter bubbles are removed by applying acoustic energy of frequencies resonant to the small bubbles to oscillate them and thereby stir liquid immediately about the bubbles to facilitate their breakup and absorption into the liquid.

Rise characteristics of gas bubbles in a 2D rectangular column: VOF simulations vs experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishna, R.; Baten, J.M. van

About five centuries ago, Leonardo da Vinci described the sinuous motion of gas bubbles rising in water. The authors have attempted to simulate the rise trajectories of bubbles of 4, 5, 7, 8, 9, 12, and 20 mm in diameter rising in a 2D rectangular column filled with water. The simulations were carried out using the volume-of-fluid (VOF) technique developed by Hirt and Nichols (J. Computational Physics, 39, 201--225 (1981)). To solve the Navier-Stokes equations of motion the authors used a commercial solver, CFX 4.1c of AEA Technology, UK. They developed their own bubble-tracking algorithm to capture sinuous bubble motions.more » The 4 and 5 mm bubbles show large lateral motions observed by Da Vinci. The 7, 8 and 9 mm bubble behave like jellyfish. The 12 mm bubble flaps its wings like a bird. The extent of lateral motion of the bubbles decreases with increasing bubble size. Bubbles larger than 20 mm in size assume a spherical cap form and simulations of the rise characteristics match experiments exactly. VOF simulations are powerful tools for a priori determination of the morphology and rise characteristics of bubbles rising in a liquid. Bubble-bubble interactions are also properly modeled by the VOF technique.« less

Experimental study on wake structure of single rising clean bubble

NASA Astrophysics Data System (ADS)

Sato, Ayaka; Takedomi, Yuta; Shirota, Minori; Sanada, Toshiyuki; Watanabe, Masao

2007-11-01

Wake structure of clean bubble rising in quiescent silicone oil solution of photochromic dye is experimentally studied. A single bubble is generated, immediately after UV sheet light illuminates the part of the liquid just above the bubble generation nozzle in order to activate photochromic dye. Once the bubble passes across the colored part of the liquid, the bubble is accompanied by some portion of activated dye tracers; hence the flow structure in the rear of the single rising bubble is visualized. We capture stereo images of both wake structure and bubble motion. We study how wake structure changes with the increase in bubble size. We observe the stable axisymmetric wake structure, which is called `standing eddy' when bubble size is relatively small, and then wake structure becomes unstable and starts to oscillate with the increase in bubble size. With further increase in bubble size, a pair of streamwise vortices, which is called `double thread', is observed. We discuss in detail this transition from the steady wake to unsteady wake structure, especially double thread wake development and hairpin vortices shedding, in relation to the transition from rectilinear to spiral or zigzag bubble motions.

Bubble Departure from Metal-Graphite Composite Surfaces and Its Effects on Pool Boiling Heat Transfer

NASA Technical Reports Server (NTRS)

Chao, David F.; Sankovic, John M.; Motil, Brian J.; Yang, W-J.; Zhang, Nengli

2010-01-01

The formation and growth processes of a bubble in the vicinity of graphite micro-fiber tips on metal-graphite composite boiling surfaces and their effects on boiling behavior are investigated. It is discovered that a large number of micro bubbles are formed first at the micro scratches and cavities on the metal matrix in pool boiling. By virtue of the non-wetting property of graphite, once the growing micro bubbles touch the graphite tips, the micro bubbles are sucked by the tips and merged into larger micro bubbles sitting on the end of the tips. The micro bubbles grow rapidly and coalesce to form macro bubbles, each spanning several tips. The necking process of a detaching macro bubble is analyzed. It is revealed that a liquid jet is produced by sudden break-off of the bubble throat. The composite surfaces not only have higher temperatures in micro- and macrolayers but also make higher frequency of the bubble departure, which increase the average heat fluxes in both the bubble growth stage and in the bubble departure period. Based on these analyses, the enhancement mechanism of pool boiling heat transfer on composite surfaces is clearly revealed.

Review-Physicochemical hydrodynamics of gas bubbles in two phase electrochemical systems.

PubMed

Taqieddin, Amir; Nazari, Roya; Rajic, Ljiljana; Alshawabkeh, Akram

2017-01-01

Electrochemical systems suffer from poor management of evolving gas bubbles. Improved understanding of bubbles behavior helps to reduce overpotential, save energy and enhance the mass transfer during chemical reactions. This work investigates and reviews the gas bubbles hydrodynamics, behavior, and management in electrochemical cells. Although the rate of bubble growth over the electrode surface is well understood, there is no reliable prediction of bubbles break-off diameter from the electrode surface because of the complexity of bubbles motion near the electrode surface. Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) are the most common experimental techniques to measure bubble dynamics. Although the PIV is faster than LDA, both techniques are considered expensive and time-consuming. This encourages adapting Computational Fluid Dynamics (CFD) methods as an alternative to study bubbles behavior. However, further development of CFD methods is required to include coalescence and break-up of bubbles for better understanding and accuracy. The disadvantages of CFD methods can be overcome by using hybrid methods. The behavior of bubbles in electrochemical systems is still a complex challenging topic which requires a better understanding of the gas bubbles hydrodynamics and their interactions with the electrode surface and bulk liquid, as well as between the bubbles itself.

Dynamics of Single Hydrogen Bubbles at a Platinum Microelectrode.

PubMed

Yang, Xuegeng; Karnbach, Franziska; Uhlemann, Margitta; Odenbach, Stefan; Eckert, Kerstin

2015-07-28

Bubble dynamics, including the formation, growth, and detachment, of single H2 bubbles was studied at a platinum microelectrode during the electrolysis of 1 M H2SO4 electrolyte. The bubbles were visualized through a microscope by a high-speed camera. Electrochemical measurements were conducted in parallel to measure the transient current. The periodic current oscillations, resulting from the periodic formation and detachment of single bubbles, allow the bubble lifetime and size to be predicted from the transient current. A comparison of the bubble volume calculated from the current and from the recorded bubble image shows a gas evolution efficiency increasing continuously with the growth of the bubble until it reaches 100%. Two different substrates, glass and epoxy, were used to embed the Pt wire. While nearly no difference was found with respect to the growth law for the bubble radius, the contact angle differs strongly for the two types of cell. Data provided for the contact point evolution further complete the image of single hydrogen bubble growth. Finally, the velocity field driven by the detached bubble was measured by means of PIV, and the effects of the convection on the subsequent bubble were evaluated.

Bubble Proliferation in Shock Wave Lithotripsy Occurs during Inertial Collapse

NASA Astrophysics Data System (ADS)

Pishchalnikov, Yuri A.; McAteer, James A.; Pishchalnikova, Irina V.; Williams, James C.; Bailey, Michael R.; Sapozhnikov, Oleg A.

2008-06-01

In shock wave lithotripsy (SWL), firing shock pulses at slow pulse repetition frequency (0.5 Hz) is more effective at breaking kidney stones than firing shock waves (SWs) at fast rate (2 Hz). Since at fast rate the number of cavitation bubbles increases, it appears that bubble proliferation reduces the efficiency of SWL. The goal of this work was to determine the basis for bubble proliferation when SWs are delivered at fast rate. Bubbles were studied using a high-speed camera (Imacon 200). Experiments were conducted in a test tank filled with nondegassed tap water at room temperature. Acoustic pulses were generated with an electromagnetic lithotripter (DoLi-50). In the focus of the lithotripter the pulses consisted of a ˜60 MPa positive-pressure spike followed by up to -8 MPa negative-pressure tail, all with a total duration of about 7 μs. Nonlinear propagation steepened the shock front of the pulses to become sufficiently thin (˜0.03 μm) to impose differential pressure across even microscopic bubbles. High-speed camera movies showed that the SWs forced preexisting microbubbles to collapse, jet, and break up into daughter bubbles, which then grew rapidly under the negative-pressure phase of the pulse, but later coalesced to re-form a single bubble. Subsequent bubble growth was followed by inertial collapse and, usually, rebound. Most, if not all, cavitation bubbles emitted micro-jets during their first inertial collapse and re-growth. After jetting, these rebounding bubbles could regain a spherical shape before undergoing a second inertial collapse. However, either upon this second inertial collapse, or sometimes upon the first inertial collapse, the rebounding bubble emerged from the collapse as a cloud of smaller bubbles rather than a single bubble. These daughter bubbles could continue to rebound and collapse for a few cycles, but did not coalesce. These observations show that the positive-pressure phase of SWs fragments preexisting bubbles but this initial fragmentation does not yield bubble proliferation, as the daughter bubbles coalesce to reform a single bubble. Instead, bubble proliferation is the product of the subsequent inertial collapses.

Behavior of Rapidly Sheared Bubble Suspensions

NASA Technical Reports Server (NTRS)

Sangani, A. S.; Kushch, V. I.; Hoffmann, M.; Nahra, H.; Koch, D. L.; Tsang, Y.

2002-01-01

An experiment to be carried out aboard the International Space Station is described. A suspension consisting of millimeter-sized bubbles in water containing some dissolved salt, which prevents bubbles from coalescing, will be sheared in a Couette cylindrical cell. Rotation of the outer cylinder will produce centrifugal force which will tend to accumulate the bubbles near the inner wall. The shearing will enhance collisions among bubbles creating thereby bubble phase pressure that will resist the tendency of the bubbles to accumulate near the inner wall. The bubble volume fraction and velocity profiles will be measured and compared with the theoretical predictions. Ground-based research on measurement of bubble phase properties and flow in vertical channel are described.

Cavitation inception by the backscattering of pressure waves from a bubble interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahira, Hiroyuki, E-mail: takahira@me.osakafu-u.ac.jp; Ogasawara, Toshiyuki, E-mail: oga@me.osakafu-u.ac.jp; Mori, Naoto, E-mail: su101064@edu.osakafu-u.ac.jp

2015-10-28

The secondary cavitation that occurs by the backscattering of focused ultrasound from a primary cavitation bubble caused by the negative pressure part of the ultrasound (Maxwell, et al., 2011) might be useful for the energy exchange due to bubble oscillations in High Intensity Focused Ultrasound (HIFU). The present study is concerned with the cavitation inception by the backscattering of ultrasound from a bubble. In the present experiment, a laser-induced bubble which is generated by a pulsed focused laser beam with high intensity is utilized as a primary cavitation bubble. After generating the bubble, focused ultrasound is emitted to the bubble.more » The acoustic field and the bubble motion are observed with a high-speed video camera. It is confirmed that the secondary cavitation bubble clouds are generated by the backscattering from the laser-induced bubble. The growth of cavitation bubble clouds is analyzed with the image processing method. The experimental results show that the height and width of the bubble clouds grow in stepwise during their evolution. The direct numerical simulations are also conducted for the backscattering of incident pressure waves from a bubble in order to evaluate a pressure field near the bubble. It is shown that the ratio of a bubble collapse time t{sub 0} to a characteristic time of wave propagation t{sub S}, η = t{sub 0}/t{sub s}, is an important determinant for generating negative pressure region by backscattering. The minimum pressure location by the backscattering in simulations is in good agreement with the experiment.« less

Spontaneous and Directional Bubble Transport on Porous Copper Wires with Complex Shapes in Aqueous Media.

PubMed

Li, Wenjing; Zhang, Jingjing; Xue, Zhongxin; Wang, Jingming; Jiang, Lei

2018-01-24

Manipulation of gas bubble behaviors is crucial for gas bubble-related applications. Generally, the manipulation of gas bubble behaviors generally takes advantage of their buoyancy force. It is very difficult to control the transportation of gas bubbles in a specific direction. Several approaches have been developed to collect and transport bubbles in aqueous media; however, most reliable and effective manipulation of gas bubbles in aqueous media occurs on the interfaces with simple shapes (i.e., cylinder and cone shapes). Reliable strategies for spontaneous and directional transport of gas bubbles on interfaces with complex shapes remain enormously challenging. Herein, a type of 3D gradient porous network was constructed on copper wire interfaces, with rectangle, wave, and helix shapes. The superhydrophobic copper wires were immersed in water, and continuous and stable gas films then formed on the interfaces. With the assistance of the Laplace pressure gradient between two bubbles, gas bubbles (including microscopic gas bubbles) in the aqueous media were subsequently transported, continuously and directionally, on the copper wires with complex shapes. The small gas bubbles always moved to the larger ones.

Predawn plasma bubble cluster observed in Southeast Asia

NASA Astrophysics Data System (ADS)

Watthanasangmechai, Kornyanat; Yamamoto, Mamoru; Saito, Akinori; Tsunoda, Roland; Yokoyama, Tatsuhiro; Supnithi, Pornchai; Ishii, Mamoru; Yatini, Clara

2016-06-01

Predawn plasma bubble was detected as deep plasma depletion by GNU Radio Beacon Receiver (GRBR) network and in situ measurement onboard Defense Meteorological Satellite Program F15 (DMSPF15) satellite and was confirmed by sparse GPS network in Southeast Asia. In addition to the deep depletion, the GPS network revealed the coexisting submesoscale irregularities. A deep depletion is regarded as a primary bubble. Submesoscale irregularities are regarded as secondary bubbles. Primary bubble and secondary bubbles appeared together as a cluster with zonal wavelength of 50 km. An altitude of secondary bubbles happened to be lower than that of the primary bubble in the same cluster. The observed pattern of plasma bubble cluster is consistent with the simulation result of the recent high-resolution bubble (HIRB) model. This event is only a single event out of 76 satellite passes at nighttime during 3-25 March 2012 that significantly shows plasma depletion at plasma bubble wall. The inside structure of the primary bubble was clearly revealed from the in situ density data of DMSPF15 satellite and the ground-based GRBR total electron content.

Isolation of Resistance-Bearing Microorganisms

NASA Technical Reports Server (NTRS)

Venkateswaran, Kasthuri, J.; Probst, Alexander; Vaishampayan, Parang A.; Ghosh, Sudeshna; Osman, Shariff

2010-01-01

To better exploit the principles of gas transport and mass transport during the processes of cell seeding of 3D scaffolds and in vitro culture of 3D tissue engineered constructs, the oscillatory cell culture bioreactor provides a flow of cell suspensions and culture media directly through a porous 3D scaffold (during cell seeding) and a 3D construct (during subsequent cultivation) within a highly gas-permeable closed-loop tube. This design is simple, modular, and flexible, and its component parts are easy to assemble and operate, and are inexpensive. Chamber volume can be very low, but can be easily scaled up. This innovation is well suited to work with different biological specimens, particularly with cells having high oxygen requirements and/or shear sensitivity, and different scaffold structures and dimensions. The closed-loop changer is highly gas permeable to allow efficient gas exchange during the cell seeding/culturing process. A porous scaffold, which may be seeded with cells, is fixed by means of a scaffold holder to the chamber wall with scaffold/construct orientation with respect to the chamber determined by the geometry of the scaffold holder. A fluid, with/without biological specimens, is added to the chamber such that all, or most, of the air is displaced (i.e., with or without an enclosed air bubble). Motion is applied to the chamber within a controlled environment (e.g., oscillatory motion within a humidified 37 C incubator). Movement of the chamber induces relative motion of the scaffold/construct with respect to the fluid. In case the fluid is a cell suspension, cells will come into contact with the scaffold and eventually adhere to it. Alternatively, cells can be seeded on scaffolds by gel entrapment prior to bioreactor cultivation. Subsequently, the oscillatory cell culture bioreactor will provide efficient gas exchange (i.e., of oxygen and carbon dioxide, as required for viability of metabolically active cells) and controlled levels of fluid dynamic shear (i.e., as required for viability of shear-sensitive cells) to the developing engineered tissue construct. This bioreactor was recently utilized to show independent and interactive effects of a growth factor (IGF-I) and slow bidirectional perfusion on the survival, differentiation, and contractile performance of 3D tissue engineering cardiac constructs. The main application of this system is within the tissue engineering industry. The ideal final application is within the automated mass production of tissue- engineered constructs. Target industries could be both life sciences companies as well as bioreactor device producing companies.

Oscillating Cell Culture Bioreactor

NASA Technical Reports Server (NTRS)

Freed, Lisa E.; Cheng, Mingyu; Moretti, Matteo G.

2010-01-01

To better exploit the principles of gas transport and mass transport during the processes of cell seeding of 3D scaffolds and in vitro culture of 3D tissue engineered constructs, the oscillatory cell culture bioreactor provides a flow of cell suspensions and culture media directly through a porous 3D scaffold (during cell seeding) and a 3D construct (during subsequent cultivation) within a highly gas-permeable closed-loop tube. This design is simple, modular, and flexible, and its component parts are easy to assemble and operate, and are inexpensive. Chamber volume can be very low, but can be easily scaled up. This innovation is well suited to work with different biological specimens, particularly with cells having high oxygen requirements and/or shear sensitivity, and different scaffold structures and dimensions. The closed-loop changer is highly gas permeable to allow efficient gas exchange during the cell seeding/culturing process. A porous scaffold, which may be seeded with cells, is fixed by means of a scaffold holder to the chamber wall with scaffold/construct orientation with respect to the chamber determined by the geometry of the scaffold holder. A fluid, with/without biological specimens, is added to the chamber such that all, or most, of the air is displaced (i.e., with or without an enclosed air bubble). Motion is applied to the chamber within a controlled environment (e.g., oscillatory motion within a humidified 37 C incubator). Movement of the chamber induces relative motion of the scaffold/construct with respect to the fluid. In case the fluid is a cell suspension, cells will come into contact with the scaffold and eventually adhere to it. Alternatively, cells can be seeded on scaffolds by gel entrapment prior to bioreactor cultivation. Subsequently, the oscillatory cell culture bioreactor will provide efficient gas exchange (i.e., of oxygen and carbon dioxide, as required for viability of metabolically active cells) and controlled levels of fluid dynamic shear (i.e., as required for viability of shear-sensitive cells) to the developing engineered tissue construct. This bioreactor was recently utilized to show independent and interactive effects of a growth factor (IGF-I) and slow bidirectional perfusion on the survival, differentiation, and contractile performance of 3D tissue engineering cardiac constructs. The main application of this system is within the tissue engineering industry. The ideal final application is within the automated mass production of tissue- engineered constructs. Target industries could be both life sciences companies as well as bioreactor device producing companies.

Different mixing techniques in experimental mesocosms—does mixing affect plankton biomass and community composition?

PubMed Central

Striebel, Maren; Kirchmaier, Leo; Hingsamer, Peter

2014-01-01

Over the past four decades, mesocosm studies have been successfully used for a wide range of applications and have provided a lot of information on trophic interactions and biogeochemical cycling of aquatic ecosystem. However, the setup of such mesocosms (e.g., dimensions and duration of experiments) needs to be adapted to the relevant biological processes being investigated. Mixing of the water column is an important factor to be considered in mesocosm experiments because enclosing water in an artificial chamber always alters the mixing regime. Various approaches have been applied to generate mixing in experimental ecosystems, including pure mechanical mixing (e.g., using a disc), airlifts, bubbling with compressed air, and pumping. In this study, we tested different mixing techniques for outdoor mesocosms and their impact on plankton biomass and community composition. We compared mesocosms mixed with a disc, an airlift-system, and bubbling, and used a nonactively mixed mesocosm as a control. We investigated phytoplankton, ciliate, and zooplankton communities during a 19-d mesocosm experiment. Based on our results, we concluded that mechanical mixing with a disc was the most effective technique due to the undertow produced by lowering and lifting the disc. While no mixing technique affected seston biomass, zooplankton biomass was highest in the treatments mixed with the disc. The airlift treatments had the lowest relative share of small flagellates. However, no further differences in phytoplankton community composition occurred and no differences in zooplankton community composition existed between all actively mixed treatments. PMID:25729335

THE FAULT DIVERTER-A PROTECTIVE DEVICE FOR HIGH-POWER ELECTRON TUBES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, B.H.

1957-08-01

Fault diverters, or crowbars, have proven to be very effective protection against transient-induced power arcs within accelerator oscillator tubes. This device short circuits the oscillator-plate power supply in the event of an over-current, thus removing the power flow from the fault within a few microseconds. Ignitrons, thyratrons, and triggered spark gaps are used for this purpose. The power supply is protected from the short circuit either by a current-limiting device or a high-speed contactor which removes the system from the power lines within a few milliseconds. The fault diverters, and associated circuitry, used on several of the accelerators in Berkeleymore » and Livermore are described. (auth) l73O Studies of pi -meson and K-meson interactions were continued with counters, emulsions, and the 10-inch liquid hydrogen bubble chanmber. Six emulsion exposures were made for external groups to a pi -meson beam, three to Kmeson beams, two to a neutral-particle beanm, and three to the internal proton beam. An H-D reaction, catalyzed by mu mesons, was observed in the 10-inch liquid hydrogen bubble chamber. Absorption cross-section measurements for antiprotons were continued, using counters. Nineteen target bombardments were made for the chemistry group. A technique of producing two or more secondary-particle beam pulses per acceleration cycle, using different targets, has been successfully tried and used. (For preceding period see UCRL- 36l4.1 (auth)« less

Thermodynamic and experimental study on heat transfer mechanism of miniature loop heat pipe with water-copper nanofluid

NASA Astrophysics Data System (ADS)

Wang, Xiao-wu; Wan, Zhen-ping; Tang, Yong

2018-02-01

A miniature loop heat pipe (mLHP) is a promising device for heat dissipation of electronic products. Experimental study of heat transfer performance of an mLHP employing Cu-water nanofluid as working fluid was conducted. It is found that, when input power is above 25 W, the temperature differences between the evaporator wall and vapor of nanofluid, Te - Tv, and the total heat resistance of mLHP using nanofluid are always lower than those of mLHP using de-ionized water. The values of Te - Tv and total heat resistance of mLHP using nanofluid with concentration 1.5 wt. % are the lowest, while when the input power is 25 W, the values of Te - Tv and total heat resistance of mLHP using de-ionized water are even lower than those of mLHP using nanofluid with concentration 2.0 wt. %. At larger input power, the dominant interaction is collision between small bubbles and nanoparticles which can facilitate heat transfer. While at lower input power, nanoparticles adhere to the surface of large bubble. This does not benefit boiling heat transfer. For mLHP using nanofluid with larger concentration, for example 2.0%, the heat transfer may even be worse compared with using de-ionized water at lower input power. The special structure of the mLHP in this study, two separated chambers in the evaporator, produces an extra pressure difference and contributes to the heat transfer performance of the mLHP.

Automatic sequential fluid handling with multilayer microfluidic sample isolated pumping

PubMed Central

Liu, Jixiao; Fu, Hai; Yang, Tianhang; Li, Songjing

2015-01-01

To sequentially handle fluids is of great significance in quantitative biology, analytical chemistry, and bioassays. However, the technological options are limited when building such microfluidic sequential processing systems, and one of the encountered challenges is the need for reliable, efficient, and mass-production available microfluidic pumping methods. Herein, we present a bubble-free and pumping-control unified liquid handling method that is compatible with large-scale manufacture, termed multilayer microfluidic sample isolated pumping (mμSIP). The core part of the mμSIP is the selective permeable membrane that isolates the fluidic layer from the pneumatic layer. The air diffusion from the fluidic channel network into the degassing pneumatic channel network leads to fluidic channel pressure variation, which further results in consistent bubble-free liquid pumping into the channels and the dead-end chambers. We characterize the mμSIP by comparing the fluidic actuation processes with different parameters and a flow rate range of 0.013 μl/s to 0.097 μl/s is observed in the experiments. As the proof of concept, we demonstrate an automatic sequential fluid handling system aiming at digital assays and immunoassays, which further proves the unified pumping-control and suggests that the mμSIP is suitable for functional microfluidic assays with minimal operations. We believe that the mμSIP technology and demonstrated automatic sequential fluid handling system would enrich the microfluidic toolbox and benefit further inventions. PMID:26487904

Bubble migration in a compacting crystal-liquid mush

NASA Astrophysics Data System (ADS)

Boudreau, Alan

2016-04-01

Recent theoretical models have suggested that bubbles are unlikely to undergo significant migration in a compaction crystal mush by capillary invasion while the system remains partly molten. To test this, experiments of bubble migration during compaction in a crystal-liquid mush were modeled using deformable foam crystals in corn syrup in a volumetric burette, compacted with rods of varying weights. A bubble source was provided by sodium bicarbonate (Alka-Seltzer®). Large bubbles (>several crystal sizes) are pinched by the compacting matrix and become overpressured and deformed as the bubbles experience a load change from hydrostatic to lithostatic. Once they begin to move, they move much faster than the compaction-driven liquid. Bubbles that are about the same size as the crystals but larger than the narrower pore throats move by deformation or breaking into smaller bubbles as they are forced through pore restrictions. Bubbles that are less than the typical pore diameter generally move with the liquid: The liquid + bubble mixture behaves as a single phase with a lower density than the bubble-free liquid, and as a consequence it rises faster than bubble-free liquid and allows for faster compaction. The overpressure required to force a bubble through the matrix (max grain size = 5 mm) is modest, about 5 %, and it is estimated that for a grain size of 1 mm, the required overpressure would be about 25 %. Using apatite distribution in a Stillwater olivine gabbro as an analog for bubble nucleation and growth, it is suggested that relatively large bubbles initially nucleate and grow in liquid-rich channels that develop late in the compaction history. Overpressure from compaction allows bubbles to rise higher into hotter parts of the crystal pile, where they redissolve and increase the volatile content of the liquid over what it would have without the bubble migration, leading to progressively earlier vapor saturation during crystallization of the interstitial liquid. Bubbles can also move rapidly by `surfing' on porosity waves that can develop in a compacting mush.

Study on the bubble transport mechanism in an acoustic standing wave field.

PubMed

Xi, Xiaoyu; Cegla, Frederic B; Lowe, Michael; Thiemann, Andrea; Nowak, Till; Mettin, Robert; Holsteyns, Frank; Lippert, Alexander

2011-12-01

The use of bubbles in applications such as surface chemistry, drug delivery, and ultrasonic cleaning etc. has been enormously popular in the past two decades. It has been recognized that acoustically-driven bubbles can be used to disturb the flow field near a boundary in order to accelerate physical or chemical reactions on the surface. The interactions between bubbles and a surface have been studied experimentally and analytically. However, most of the investigations focused on violently oscillating bubbles (also known as cavitation bubble), less attention has been given to understand the interactions between moderately oscillating bubbles and a boundary. Moreover, cavitation bubbles were normally generated in situ by a high intensity laser beam, little experimental work has been carried out to study the translational trajectory of a moderately oscillating bubble in an acoustic field and subsequent interactions with the surface. This paper describes the design of an ultrasonic test cell and explores the mechanism of bubble manipulation within the test cell. The test cell consists of a transducer, a liquid medium and a glass backing plate. The acoustic field within the multi-layered stack was designed in such a way that it was effectively one dimensional. This was then successfully simulated by a one dimensional network model. The model can accurately predict the impedance of the test cell as well as the mode shape (distribution of particle velocity and stress/pressure field) within the whole assembly. The mode shape of the stack was designed so that bubbles can be pushed from their injection point onto a backing glass plate. Bubble radial oscillation was simulated by a modified Keller-Miksis equation and bubble translational motion was derived from an equation obtained by applying Newton's second law to a bubble in a liquid medium. Results indicated that the bubble trajectory depends on the acoustic pressure amplitude and initial bubble size: an increase of pressure amplitude or a decrease of bubble size forces bubbles larger than their resonant size to arrive at the target plate at lower heights, while the trajectories of smaller bubbles are less influenced by these factors. The test cell is also suitable for testing the effects of drag force on the bubble motion and for studying the bubble behavior near a surface. Copyright © 2011 Elsevier B.V. All rights reserved.

Wetting of soap bubbles on hydrophilic, hydrophobic, and superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Arscott, Steve

2013-06-01

Wetting of sessile bubbles on various wetting surfaces (solid and liquid) has been studied. A model is presented for the apparent contact angle of a sessile bubble based on a modified Young's equation--the experimental results agree with the model. Wetting a hydrophilic surface results in a bubble contact angle of 90° whereas using a superhydrophobic surface one observes 134°. For hydrophilic surfaces, the bubble angle diminishes with bubble radius whereas on a superhydrophobic surface, the bubble angle increases. The size of the plateau borders governs the bubble contact angle, depending on the wetting of the surface.

Acoustical Testing Laboratory Developed to Support the Low-Noise Design of Microgravity Space Flight Hardware

NASA Technical Reports Server (NTRS)

Cooper, Beth A.

2001-01-01

The NASA John H. Glenn Research Center at Lewis Field has designed and constructed an Acoustical Testing Laboratory to support the low-noise design of microgravity space flight hardware. This new laboratory will provide acoustic emissions testing and noise control services for a variety of customers, particularly for microgravity space flight hardware that must meet International Space Station limits on noise emissions. These limits have been imposed by the space station to support hearing conservation, speech communication, and safety goals as well as to prevent noise-induced vibrations that could impact microgravity research data. The Acoustical Testing Laboratory consists of a 23 by 27 by 20 ft (height) convertible hemi/anechoic chamber and separate sound-attenuating test support enclosure. Absorptive 34-in. fiberglass wedges in the test chamber provide an anechoic environment down to 100 Hz. A spring-isolated floor system affords vibration isolation above 3 Hz. These criteria, along with very low design background levels, will enable the acquisition of accurate and repeatable acoustical measurements on test articles, up to a full space station rack in size, that produce very little noise. Removable floor wedges will allow the test chamber to operate in either a hemi/anechoic or anechoic configuration, depending on the size of the test article and the specific test being conducted. The test support enclosure functions as a control room during normal operations but, alternatively, may be used as a noise-control enclosure for test articles that require the operation of noise-generating test support equipment.

How are soap bubbles blown? Fluid dynamics of soap bubble blowing

NASA Astrophysics Data System (ADS)

Davidson, John; Lambert, Lori; Sherman, Erica; Wei, Timothy; Ryu, Sangjin

2013-11-01

Soap bubbles are a common interfacial fluid dynamics phenomenon having a long history of delighting not only children and artists but also scientists. In contrast to the dynamics of liquid droplets in gas and gas bubbles in liquid, the dynamics of soap bubbles has not been well documented. This is possibly because studying soap bubbles is more challenging due to there existing two gas-liquid interfaces. Having the thin-film interface seems to alter the characteristics of the bubble/drop creation process since the interface has limiting factors such as thickness. Thus, the main objective of this study is to determine how the thin-film interface differentiates soap bubbles from gas bubbles and liquid drops. To investigate the creation process of soap bubbles, we constructed an experimental model consisting of air jet flow and a soap film, which consistently replicates the conditions that a human produces when blowing soap bubbles, and examined the interaction between the jet and the soap film using the high-speed videography and the particle image velocimetry.

Acoustic measurement of bubble size and position in a piezo driven inkjet printhead

NASA Astrophysics Data System (ADS)

van der Bos, Arjan; Jeurissen, Roger; de Jong, Jos; Stevens, Richard; Versluis, Michel; Reinten, Hans; van den Berg, Marc; Wijshoff, Herman; Lohse, Detlef

2008-11-01

A bubble can be entrained in the ink channel of a piezo-driven inkjet printhead, where it grows by rectified diffusion. If large enough, the bubble counteracts the pressure buildup at the nozzle, resulting in nozzle failure. Here an acoustic sizing method for the volume and position of the bubble is presented. The bubble response is detected by the piezo actuator itself, operating in a sensor mode. The method used to determine the volume and position of the bubble is based on a linear model in which the interaction between the bubble and the channel are included. This model predicts the acoustic signal for a given position and volume of the bubble. The inverse problem is to infer the position and volume of the bubble from the measured acoustic signal. By solving it, we can thus acoustically measure size and position of the bubble. The validity of the presented method is supported by time-resolved optical observations of the dynamics of the bubble within an optically accessible ink-jet channel.

Oxygen isotope study of the Long Valley magma system, California: isotope thermometry and convection in large silicic magma bodies

NASA Astrophysics Data System (ADS)

Bindeman, Ilya; Valley, John

2002-07-01

Products of voluminous pyroclastic eruptions with eruptive draw-down of several kilometers provide a snap-shot view of batholith-scale magma chambers, and quench pre-eruptive isotopic fractionations (i.e., temperatures) between minerals. We report analyses of oxygen isotope ratio in individual quartz phenocrysts and concentrates of magnetite, pyroxene, and zircon from individual pumice clasts of ignimbrite and fall units of caldera-forming 0.76 Ma Bishop Tuff (BT), pre-caldera Glass Mountain (2.1-0.78 Ma), and post-caldera rhyolites (0.65-0.04 Ma) to characterize the long-lived, batholith-scale magma chamber beneath Long Valley Caldera in California. Values of δ18O show a subtle 1‰ decrease from the oldest Glass Mountain lavas to the youngest post-caldera rhyolites. Older Glass Mountain lavas exhibit larger ( 1‰) variability of δ18O(quartz). The youngest domes of Glass Mountain are similar to BT in δ18O(quartz) values and reflect convective homogenization during formation of BT magma chamber surrounded by extremely heterogeneous country rocks (ranging from 2 to +29‰). Oxygen isotope thermometry of BT confirms a temperature gradient between "Late" (815 °C) and "Early" (715 °C) BT. The δ18O(quartz) values of "Early" and "Late" BT are +8.33 and 8.21‰, consistent with a constant δ18O(melt)=7.8+/-0.1‰ and 100 °C temperature difference. Zircon-melt saturation equilibria gives a similar temperature range. Values of δ18O(quartz) for different stratigraphic units of BT, and in pumice clasts ranging in pre-eruptive depths from 6 to 11 km (based on melt inclusions), and document vertical and lateral homogeneity of δ18O(melt). Worldwide, five other large-volume rhyolites, Lava Creek, Lower Bandelier, Fish Canyon, Cerro Galan, and Toba, exhibit equal δ18O(melt) values of earlier and later erupted portions in each of the these climactic caldera-forming eruptions. We interpret the large-scale δ18O homogeneity of BT and other large magma chambers as evidence of their longevity (>105 years) and convection. However, remaining isotopic zoning in some quartz phenocrysts, trace element gradients in feldspars, and quartz and zircon crystal size distributions are more consistent with far shorter timescales (102-104 years). We propose a sidewall-crystallization model that promotes convective homogenization, roofward accumulation of more evolved and stagnant, volatile-rich liquid, and develops compositional and temperature gradients in pre-climactic magma chamber. Crystal + melt + gas bubbles mush near chamber walls of variable δ18O gets periodically remobilized in response to chamber refill by new hotter magmas. One such episode of chamber refill by high-Ti, Sr, Ba, Zr, and volatile-richer magma happened 103-104 years prior to the 0.76-Ma caldera collapse that caused magma mixing at the base, mush thawing near the roof and walls, and downward settling of phenocrysts into this hybrid melt.

Investigation of the interaction dynamics of a pair of laser-induced bubbles generated at the same time through double-exposure strobe method and numerical simulations

NASA Astrophysics Data System (ADS)

Han, Bing; Liu, Liu; Ni, Xiao-Wu

2017-08-01

In order to understand the interaction dynamics of a pair of laser-induced bubbles, a double-exposure strobe photography experimental setup is build up to study the temporal evolution of the bubble pairs and to measure the transient bubble-interface moving speed. The interaction mechanisms of the bubble pairs are discussed together with the numerical results obtained through OpenFOAM. It is shown that the direction and the velocity of the jetting could be controlled by the relative size and the relative initiation distance of the bubble pair, when the bubbles are generated at the same time, i.e., in-phase. The liquid jet is considered to be a penetrating jet. The jet is originated from the smaller bubble and clearly protruding outside of the bigger bubble. The parameter space of the relative size and the initiation distance of the bubble pair allowing the formation of the penetrating jet are very narrow. It is concluded that the liquid jet induced by the bubble interactions resulted from the collapse and the rebound of the smaller bubble nearby the bigger bubble. This is defined as the "catapult effect." Such a directional liquid transportation is a promising tool as a micro-injector or a micro-pump. The investigation results could be also supplementary to the understandings of the bubble dynamics.

Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols

NASA Astrophysics Data System (ADS)

Schmitt-Kopplin, P.; Liger-Belair, G.; Koch, B. P.; Flerus, R.; Kattner, G.; Harir, M.; Kanawati, B.; Lucio, M.; Tziotis, D.; Hertkorn, N.; Gebefügi, I.

2012-04-01

Atmospheric aerosols impose direct and indirect effects on the climate system, for example, by absorption of radiation in relation to cloud droplets size, on chemical and organic composition and cloud dynamics. The first step in the formation of Organic primary aerosols, i.e. the transfer of dissolved organic matter from the marine surface into the atmosphere, was studied. We present a molecular level description of this phenomenon using the high resolution analytical tools of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance spectroscopy (NMR). Our experiments confirm the chemoselective transfer of natural organic molecules, especially of aliphatic compounds from the surface water into the atmosphere via bubble bursting processes. Transfer from marine surface water to the atmosphere involves a chemical gradient governed by the physicochemical properties of the involved molecules when comparing elemental compositions and differentiating CHO, CHNO, CHOS and CHNOS bearing compounds. Typical chemical fingerprints of compounds enriched in the aerosol phase were CHO and CHOS molecular series, smaller molecules of higher aliphaticity and lower oxygen content, and typical surfactants. A non-targeted metabolomics analysis demonstrated that many of these molecules corresponded to homologous series of oxo-, hydroxy-, methoxy-, branched fatty acids and mono-, di- and tricarboxylic acids as well as monoterpenes and sugars. These surface active biomolecules were preferentially transferred from surface water into the atmosphere via bubble bursting processes to form a significant fraction of primary organic aerosols. This way of sea spray production leaves a selective biological signature of the surface water in the corresponding aerosol that may be transported into higher altitudes up to the lower atmosphere, thus contributing to the formation of secondary organic aerosol on a global scale or transported laterally with possible deposition in the context of global biogeocycling.

In Search of the Big Bubble

ERIC Educational Resources Information Center

Simoson, Andrew; Wentzky, Bethany

2011-01-01

Freely rising air bubbles in water sometimes assume the shape of a spherical cap, a shape also known as the "big bubble". Is it possible to find some objective function involving a combination of a bubble's attributes for which the big bubble is the optimal shape? Following the basic idea of the definite integral, we define a bubble's surface as…

A note on effects of rational bubble on portfolios

NASA Astrophysics Data System (ADS)

Wang, Chan; Nie, Pu-yan

2018-02-01

In general, demand increases in wealth and decreases in price in microeconomics. We thereby propose a completely different perspective. By establishing expected utility function of investors, this article introduces one rational bubble asset and one bubble free asset in portfolios and focuses on the effects of bubble on investment portfolios from wealth and price perspectives. All conclusions are obtained by theoretical analysis with microeconomics theory. We argue that inferior goods and Giffen behavior can occur for the bubble free asset in microeconomic fields. The results can help investors to recognize bubble assets and bubble free assets more scientifically. Both bubble and bubble free assets can be inferior goods under some conditions, so we cannot to say which asset better than the other one absolutely.

Characterization of nano-bubbles as an oxygen carrier for in-situ bioremediation of organic pollutants in the subsurface

NASA Astrophysics Data System (ADS)

KIM, E.; Jung, J.; Kang, S.; Choi, Y.

2016-12-01

In-situ bioremediation using bubbles as an oxygen carrier has shown its applicability for aerobic biodegradation of organic pollutants in the subsurface. By recent progresses, generation of nano-sized bubbles is possible, which have enhanced oxygen transfer efficiencies due to their high interfacial area and stability. We are developing an in-situ bioremediation technique using nano-bubbles as an oxygen carrier. In this study, nano-bubbles were characterized for their size and oxygen supply capacity. Nano-bubbles were generated with pure oxygen and pure helium gas. The stable nano-bubbles suspended in water were sonicated to induce the bubbles to coalesce, making them to rise and be released out of the water. By removing the bubbles, the water volume was decreased by 0.006%. The gas released from the bubble suspension was collected to measure the amount of gas in the nano-bubbles. For sparingly soluble helium gas 17.9 mL/L was released from the bubble suspension, while for oxygen 46.2 mL/L was collected. For the oxygen nano-bubble suspension, it is likely that the release of dissolved oxygen (DO) contributed to the collected gas volume. After removing the oxygen nano-bubbles, 36.0 mg/L of DO was still present in water. Altogether, the oxygen nano-bubble suspension was estimated to have 66.2 mg/L of oxygen in a dissolved form and 25.6 mg/L as nano-bubbles. A high DO level in the water was possible because of their large Laplace pressure difference across the fluid interface. Applying Young-Laplace equation and ideal gas law, the bubble diameter was estimated to be approximately 10 nm, having an internal pressure of 323 atm. Considering the saturation DO of 8.26 mg/L for water in equilibrium with the atmosphere, the total oxygen content of 91.8 mg/L in the nano-bubble suspension suggests its great potential as an oxygen carrier. Studies are underway to verify the enhanced aerobic biodegradation of organic pollutants in soils by injecting nano-bubble suspensions.

Dynamics of Vapour Bubbles in Nucleate Boiling. 2; Evolution of Thermally Controlled Bubbles

NASA Technical Reports Server (NTRS)

Buyevich, Yu A.; Webbon, Bruce W.; Callaway, Robert (Technical Monitor)

1995-01-01

The previously developed dynamic theory of growth and detachment of vapour bubbles under conditions of nucleate pool boiling is applied to study motion and deformation of a bubble evolving at a single nucleation site. The bubble growth is presumed to be thermally controlled, and two components of heat transfer to the bubble are accounted of: the one from the bulk of surrounding liquid and the one due to heat conduction across a liquid microlayer formed underneath the bubble. Bubble evolution is governed by the buoyancy and an effective surface tension force, both the forces making the bubble centre of mass move away from the wall and, thus, assisting its detachment. Buoyancy-controlled and surface-tension-controlled regimes are considered separately in a meticulous way. The duration of the whole process of bubble evolution till detachment, the rate of growth, and the bubble departure size are found as functions of time and physical and operating parameters. Some repeatedly observed phenomena, such as an influence of gravity on the growth rate, are explained. Inferences of the model agree qualitatively with available experimental evidence, and conclusions pertaining to the dependence on gravity of the bubble radius at detachment and the whole time of the bubble development when being attached to the wall are confirmed quantitatively.

Review—Physicochemical hydrodynamics of gas bubbles in two phase electrochemical systems

PubMed Central

Taqieddin, Amir; Nazari, Roya; Rajic, Ljiljana; Alshawabkeh, Akram

2018-01-01

Electrochemical systems suffer from poor management of evolving gas bubbles. Improved understanding of bubbles behavior helps to reduce overpotential, save energy and enhance the mass transfer during chemical reactions. This work investigates and reviews the gas bubbles hydrodynamics, behavior, and management in electrochemical cells. Although the rate of bubble growth over the electrode surface is well understood, there is no reliable prediction of bubbles break-off diameter from the electrode surface because of the complexity of bubbles motion near the electrode surface. Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) are the most common experimental techniques to measure bubble dynamics. Although the PIV is faster than LDA, both techniques are considered expensive and time-consuming. This encourages adapting Computational Fluid Dynamics (CFD) methods as an alternative to study bubbles behavior. However, further development of CFD methods is required to include coalescence and break-up of bubbles for better understanding and accuracy. The disadvantages of CFD methods can be overcome by using hybrid methods. The behavior of bubbles in electrochemical systems is still a complex challenging topic which requires a better understanding of the gas bubbles hydrodynamics and their interactions with the electrode surface and bulk liquid, as well as between the bubbles itself. PMID:29731515

Electricity generation using an air-cathode single chamber microbial fuel cell in the presence and absence of a proton exchange membrane.

PubMed

Liu, Hong; Logan, Bruce E

2004-07-15

Microbial fuel cells (MFCs) are typically designed as a two-chamber system with the bacteria in the anode chamber separated from the cathode chamber by a polymeric proton exchange membrane (PEM). Most MFCs use aqueous cathodes where water is bubbled with air to provide dissolved oxygen to electrode. To increase energy output and reduce the cost of MFCs, we examined power generation in an air-cathode MFC containing carbon electrodes in the presence and absence of a polymeric proton exchange membrane (PEM). Bacteria present in domestic wastewater were used as the biocatalyst, and glucose and wastewater were tested as substrates. Power density was found to be much greater than typically reported for aqueous-cathode MFCs, reaching a maximum of 262 +/- 10 mW/m2 (6.6 +/- 0.3 mW/L; liquid volume) using glucose. Removing the PEM increased the maximum power density to 494 +/- 21 mW/m2 (12.5 +/- 0.5 mW/L). Coulombic efficiency was 40-55% with the PEM and 9-12% with the PEM removed, indicating substantial oxygen diffusion into the anode chamber in the absence of the PEM. Power output increased with glucose concentration according to saturation-type kinetics, with a half saturation constant of 79 mg/L with the PEM-MFC and 103 mg/L in the MFC without a PEM (1000 omega resistor). Similar results on the effect of the PEM on power density were found using wastewater, where 28 +/- 3 mW/m2 (0.7 +/- 0.1 mW/L) (28% Coulombic efficiency) was produced with the PEM, and 146 +/- 8 mW/m2 (3.7 +/- 0.2 mW/L) (20% Coulombic efficiency) was produced when the PEM was removed. The increase in power output when a PEM was removed was attributed to a higher cathode potential as shown by an increase in the open circuit potential. An analysis based on available anode surface area and maximum bacterial growth rates suggests that mediatorless MFCs may have an upper order-of-magnitude limit in power density of 10(3) mW/m2. A cost-effective approach to achieving power densities in this range will likely require systems that do not contain a polymeric PEM in the MFC and systems based on direct oxygen transfer to a carbon cathode.

Bubble pinch-off and scaling during liquid drop impact on liquid pool

NASA Astrophysics Data System (ADS)

Ray, Bahni; Biswas, Gautam; Sharma, Ashutosh

2012-08-01

Simulations are performed to show entrapment of air bubble accompanied by high speed upward and downward water jets when a water drop impacts a pool of water surface. A new bubble entrapment zone characterised by small bubble pinch-off and long thick jet is found. Depending on the bubble and jet behaviour, the bubble entrapment zone is subdivided into three sub-regimes. The entrapped bubble size and jet height depends on the crater shape and its maximum depth. During the bubble formation, bubble neck develops an almost singular shape as it pinches off. The final pinch-off shape and the power law governing the pinching, rneck ∝ A(t0 - t)αvaries with the Weber number. Weber dependence of the function describing the radius of the bubble during the pinch-off only affects the coefficient A and not the power exponent α.

Deep Basalt Aquifers in Orcus Patera, Elysium Basin Mars: Perspectives for Exobiology Exploration

NASA Technical Reports Server (NTRS)

Grin, E. A.; Cabrol, N. A.

1998-01-01

Direct indicators of shorelines, spillways, and terraces allowed to determine the extent of the Elysium Paleolake between the contour-lines 1000 and 500 m below the Martian datum. The Elysium Paleolake is bordered north by Orcus Patera (14N/181W), which lies west of the Tartarus Montes and Tartarus Colles. The Orcus Patera displays an ellipse-shaped collapsed caldera of 360-km long and 100-km wide. Viking topographic data show that the bottom of the caldera is located at 2500 below the Martian datum, and surrounded by a steep-walled ram art which crest is located at about 0 m elevation. Considering the localization of Orcus Patera in the Elysium paleolake, its altimetry, and the magmatic origin of this caldera, we propose the existence of a paleolake in Orcus Patera generated (a) by juvenile water from magma during the Noachian period, and (b) by intermittent influx of the Elysium Basin from Hesperian to Amazonian. Results are encouraging to consider this site as a potential high-energy source environment for microbial communities. are circumscribed by a 50-km wide lava field mapped as Noachian material. The structure of Orcus Patera represents the record of material erupted from a magmatic reservoir. The caldera is enclosed by steep inner walls (25% measured from topographic data), values which could be in agreement with the presence of a deep magmatic reservoir, as suggested by the typology of Crumpler et.al. The depth of the caldera might be due to the collapse of the magma reservoir, and the release of gases accompanying the magma thermal evolution. Origins of water for the paleolake(s): The water that generated a paleolake in Orcus Patera may have come from two origins: (1) Juvenile water: Plescia and Crips estimated a magma H20 content by weight between 0.5% and 1.5% using for the first value a comparison with terrestrial basalt, and for the second values from a Martian meteorite. The amount of H20 can be estimated by the volume of erupted lava, and the lava content of the caldera. In this study, we adopt a water content of 1%. The total volume of magma that has been contained in the caldera, and the volume of lava contained in the observed lava field is about 110 x 10(exp 6) cubic km, that gives a total volume of 1.10 x 10(exp 6) cubic km of water. The juvenile water expelled by the overpressure within the magma chamber charged with desolved water-vapor may have moved into the crust. The decrease in overburden pressure led to bubble formation. The ascent of these bubbles generated a pressurization of the magma, which was sufficient to fracture the overlaying magma layer, (2) Water from Elysium paleolake. During the Amazonian, the rise of the Elysium paleolake level generated an overspilling that supplied the caldera with water. The southern portion of the crest shows a deep gap 12-km wide at -1500 m elevation, locating the gap between 500 to 1000 in below the assumed water of Elysium paleolake, thus facilitating the influx of Elysium paleolake water into Orcus Patera. Bathymetric calculations give a floor area of 25,500 sq km at -2000 m elevation, and a water volume of 42,000 cubic km, with a lake-level at -1500 m. A substantial amount of water may have percolated through the fractured lava, and part of the volume may have overspilled the northern crest of Orcus Patera to debouch in the Tartarus Montes region. We envision the formation of a subsurface aqueous environment in basaltic rocks at the contact of the two water-source origins, possibly the percolating surface lake water, and more likely the juvenile water. Similarly to terrestrial calderas, Orcus Patera might be surrounded by ring-fractures caused by the collapse of the magma chamber that followed the release of gases. These ring-fractures may have been covered later by sedimentation in the caldera (lacustrine, aeolian, and volcanic), and by mass wasting. The detumescence of the magma in the caldera, and the vesiculation of the juvenile water may have operated simultaneously. Comparatively to terrestrial melts, Martian iron-rich melts are denser. This greater density implies greater effusion rates (eight-times terrestrial values), and larger fissuration widths (two-times terrestrial ones). With increasing vesiculation of magma, the bubbles interact with one-another because there are of similar pressure. They make a magma froth at the contact with the caldera surface, and on the walls of the fractures. In the saturated magma, froth, where the volume ratio of gases-to-liquid is about 4:1, the bubbles form a huge surface area of interconnected spaces. Bubbles near the caldera surface disrupt the magma, and fragmentation takes place, which moves downward through the magma column. On Earth, the bubbles are likely to grow between 1 and 50 mm in diameter due to the difference between the magma surface tension, and the bubble supersaturation pressure. The Martian low-pressure at surface level is likely to accelerate the expansion of the bubbles, and increase their final diameter and number, creating more voids in the magma. The strong magma froth with enclosed juvenile water bubbles interconnected with exsolved gas bubbles constitute a potential geothermal environment for geochemical energy production from basalt and water that does not require excessive temperatures. This process can start at +20C. Similar types of environments have been shown on Earth as potential energy sources for microbial metabolism, and could have provided deep aqueous basaltic niches for possible Martian microorganisms, even geologically recently. During the Amazonian, combination of volcanism and water activity still existed on Mars. Moreover, this type of potential niches open ways for investigation of possible oases of extinct or extant life, not only on paleolakes, and surface hydrothermalism spring areas, but also all large systems of fossae, which combine hydrologic and volcanic activities, and which provide an energy source, and an underground shelter to prevent surface UV bombardment. Additional information contained in the original.

Bubble velocity, diameter, and void fraction measurements in a multiphase flow using fiber optic reflectometer

NASA Astrophysics Data System (ADS)

Lim, Ho-Joon; Chang, Kuang-An; Su, Chin B.; Chen, Chi-Yueh

2008-12-01

A fiber optic reflectometer (FOR) technique featuring a single fiber probe is investigated for its feasibility of measuring the bubble velocity, diameter, and void fraction in a multiphase flow. The method is based on the interference of the scattered signal from the bubble surface with the Fresnel reflection signal from the tip of the optical fiber. Void fraction is obtained with a high accuracy if an appropriate correction is applied to compensate the underestimated measurement value. Velocity information is accurately obtained from the reflected signals before the fiber tip touches the bubble surface so that several factors affecting the traditional dual-tip probes such as blinding, crawling, and drifting effects due to the interaction between the probe and bubbles can be prevented. The coherent signals reflected from both the front and rear ends of a bubble can provide velocity information. Deceleration of rising bubbles and particles due to the presence of the fiber probe is observed when they are very close to the fiber tip. With the residence time obtained, the bubble chord length can be determined by analyzing the coherent signal for velocity determination before the deceleration starts. The bubble diameters are directly obtained from analyzing the signals of the bubbles that contain velocity information. The chord lengths of these bubbles measured by FOR represent the bubble diameters when the bubble shape is spherical or represent the minor axes when the bubble shape is ellipsoidal. The velocity and size of bubbles obtained from the FOR measurements are compared with those obtained simultaneously using a high speed camera.

Wall Area of Influence and Growing Wall Heat Transfer due to Sliding Bubbles in Subcooled Boiling Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoo, Junsoo; Estrada-Perez, Carlos E.; Hassan, Yassin A.

A variety of dynamical features of sliding bubbles and their impact on wall heat transfer were observed at subcooled flow boiling conditions in a vertical square test channel. Among the wide range of parameters observed, we particularly focus in this paper on (i) the sliding bubbles’ effect on wall heat transfer (supplemantry discussion to the authors’ previous work in Yoo et al. (2016a,b)) and (ii) the wall area influenced by sliding bubbles in subcooled boiling flow. At first, this study reveals that the degree of wall heat transfer improvement due to sliding bubbles depended less on the wall superheat conditionmore » as the mass flux increased. Also, the sliding bubble trajectory was found to be one of the critical factors in order to properly describe the wall heat transfer associated with sliding bubbles. In particular, the wall area influenced by sliding bubbles depended strongly on both sliding bubble trajectory and sliding bubble size; the sliding bubble trajectory was also observed to be closely related to the sliding bubble size. Importantly, these results indicate the limitation of current approach in CFD analyses especially for the wall area of bubble influence. In addition, the analyses on the temporal fraction of bubbles’ residence (FR) along the heated wall show that the sliding bubbles typically travel through narrow path with high frequency while the opposite was observed downstream. That is, both FR and sliding bubble trajectory depended substantially on the distance from nucleation site, which is expected to be similar for the quenching heat transfer mode induced by sliding bubbles.« less

Void fraction, bubble size and interfacial area measurements in co-current downflow bubble column reactor with microbubble dispersion

DOE PAGES

Hernandez-Alvarado, Freddy; Kalaga, Dinesh V.; Turney, Damon; ...

2017-05-06

Micro-bubbles dispersed in bubble column reactors have received great interest in recent years, due to their small size, stability, high gas-liquid interfacial area concentrations and longer residence times. The high gas-liquid interfacial area concentrations lead to high mass transfer rates compared to conventional bubble column reactors. In the present work, experiments have been performed in a down-flow bubble column reactor with micro-bubbles generated and dispersed by a novel mechanism to determine the gas-liquid interfacial area concentrations by measuring the void fraction and bubble size distributions. Gamma-ray densitometry has been employed to determine the axial and radial distributions of void fractionmore » and a high speed camera equipped with a borescope is used to measure the axial and radial variations of bubble sizes. Also, the effects of superficial gas and liquid velocities on the two-phase flow characteristics have been investigated. Further, reconstruction techniques of the radial void fraction profiles from the gamma densitometry's chordal measurements are discussed and compared for a bubble column reactor with dispersed micro-bubbles. The results demonstrate that the new bubble generation technique offers high interfacial area concentrations (1,000 to 4,500 m 2/m 3) with sub-millimeter bubbles (500 to 900 µm) and high overall void fractions (10% – 60%) in comparison with previous bubble column reactor designs. The void fraction data was analyzed using slip velocity model and empirical correlation has been proposed to predict the Sauter mean bubble diameter.« less

Interaction of lithotripter shockwaves with single inertial cavitation bubbles

PubMed Central

Klaseboer, Evert; Fong, Siew Wan; Turangan, Cary K.; Khoo, Boo Cheong; Szeri, Andrew J.; Calvisi, Michael L.; Sankin, Georgy N.; Zhong, Pei

2008-01-01

The dynamic interaction of a shockwave (modelled as a pressure pulse) with an initially spherically oscillating bubble is investigated. Upon the shockwave impact, the bubble deforms non-spherically and the flow field surrounding the bubble is determined with potential flow theory using the boundary-element method (BEM). The primary advantage of this method is its computational efficiency. The simulation process is repeated until the two opposite sides of the bubble surface collide with each other (i.e. the formation of a jet along the shockwave propagation direction). The collapse time of the bubble, its shape and the velocity of the jet are calculated. Moreover, the impact pressure is estimated based on water-hammer pressure theory. The Kelvin impulse, kinetic energy and bubble displacement (all at the moment of jet impact) are also determined. Overall, the simulated results compare favourably with experimental observations of lithotripter shockwave interaction with single bubbles (using laser-induced bubbles at various oscillation stages). The simulations confirm the experimental observation that the most intense collapse, with the highest jet velocity and impact pressure, occurs for bubbles with intermediate size during the contraction phase when the collapse time of the bubble is approximately equal to the compressive pulse duration of the shock wave. Under this condition, the maximum amount of energy of the incident shockwave is transferred to the collapsing bubble. Further, the effect of the bubble contents (ideal gas with different initial pressures) and the initial conditions of the bubble (initially oscillating vs. non-oscillating) on the dynamics of the shockwave–bubble interaction are discussed. PMID:19018296

Interaction of lithotripter shockwaves with single inertial cavitation bubbles.

PubMed

Klaseboer, Evert; Fong, Siew Wan; Turangan, Cary K; Khoo, Boo Cheong; Szeri, Andrew J; Calvisi, Michael L; Sankin, Georgy N; Zhong, Pei

2007-01-01

The dynamic interaction of a shockwave (modelled as a pressure pulse) with an initially spherically oscillating bubble is investigated. Upon the shockwave impact, the bubble deforms non-spherically and the flow field surrounding the bubble is determined with potential flow theory using the boundary-element method (BEM). The primary advantage of this method is its computational efficiency. The simulation process is repeated until the two opposite sides of the bubble surface collide with each other (i.e. the formation of a jet along the shockwave propagation direction). The collapse time of the bubble, its shape and the velocity of the jet are calculated. Moreover, the impact pressure is estimated based on water-hammer pressure theory. The Kelvin impulse, kinetic energy and bubble displacement (all at the moment of jet impact) are also determined. Overall, the simulated results compare favourably with experimental observations of lithotripter shockwave interaction with single bubbles (using laser-induced bubbles at various oscillation stages). The simulations confirm the experimental observation that the most intense collapse, with the highest jet velocity and impact pressure, occurs for bubbles with intermediate size during the contraction phase when the collapse time of the bubble is approximately equal to the compressive pulse duration of the shock wave. Under this condition, the maximum amount of energy of the incident shockwave is transferred to the collapsing bubble. Further, the effect of the bubble contents (ideal gas with different initial pressures) and the initial conditions of the bubble (initially oscillating vs. non-oscillating) on the dynamics of the shockwave-bubble interaction are discussed.

Void fraction, bubble size and interfacial area measurements in co-current downflow bubble column reactor with microbubble dispersion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez-Alvarado, Freddy; Kalaga, Dinesh V.; Turney, Damon

Micro-bubbles dispersed in bubble column reactors have received great interest in recent years, due to their small size, stability, high gas-liquid interfacial area concentrations and longer residence times. The high gas-liquid interfacial area concentrations lead to high mass transfer rates compared to conventional bubble column reactors. In the present work, experiments have been performed in a down-flow bubble column reactor with micro-bubbles generated and dispersed by a novel mechanism to determine the gas-liquid interfacial area concentrations by measuring the void fraction and bubble size distributions. Gamma-ray densitometry has been employed to determine the axial and radial distributions of void fractionmore » and a high speed camera equipped with a borescope is used to measure the axial and radial variations of bubble sizes. Also, the effects of superficial gas and liquid velocities on the two-phase flow characteristics have been investigated. Further, reconstruction techniques of the radial void fraction profiles from the gamma densitometry's chordal measurements are discussed and compared for a bubble column reactor with dispersed micro-bubbles. The results demonstrate that the new bubble generation technique offers high interfacial area concentrations (1,000 to 4,500 m 2/m 3) with sub-millimeter bubbles (500 to 900 µm) and high overall void fractions (10% – 60%) in comparison with previous bubble column reactor designs. The void fraction data was analyzed using slip velocity model and empirical correlation has been proposed to predict the Sauter mean bubble diameter.« less

Time-Dependent Changes in a Shampoo Bubble

NASA Astrophysics Data System (ADS)

Chattopadhyay, Arun

2000-10-01

This article demonstrates the fascinating phenomenon of time evolution of a shampoo bubble through experiments that can be performed by undergraduate students. The changes in thickness of the bubble films with time are followed by UV-vis spectroscopy. The change in chemical composition as a bubble film evolves is monitored by FTIR spectroscopy. It is observed that the change in thickness of a typical shampoo bubble film enclosed in a container is gradual and slow, and the hydrocarbon components of the bubble drain from the bubble much more slowly than water. An additional agent, such as acetonitrile, strikingly alters the dynamics of evolution of such a bubble.

Effect of electrolytes on bubble coalescence in columns observed with visualization techniques.

PubMed

Aguilera, María Eugenia; Ojeda, Antonieta; Rondón, Carolina; López De Ramos, Aura

2002-10-01

Bubble coalescence and the effect of electrolytes on this phenomenon have been previously studied. This interfacial phenomenon has attracted attention for reactor design/operation and enhanced oil recovery. Predicting bubble coalescence may help prevent low yields in reactors and predict crude oil recovery. Because of the importance of bubble coalescence, the objectives of this work were to improve the accuracy of measuring the percentage of coalescing bubbles and to observe the interfacial gas-liquid behavior. An experimental setup was designed and constructed. Bubble interactions were monitored with a visualization setup. The percentage of air bubble coalescence was 100% in distilled water, about 50% in 0.1 M sodium chloride (NaCl) aqueous solution, and 0% in 0.145 M NaCl aqueous solution. A reduction of the contact gas-liquid area was observed in distillate water. The volume of the resulting bubble was the sum of the original bubble volumes. Repulsion of bubbles was observed in NaCl solutions exceeding 0.07 M. The percentage of bubble coalescence diminishes as the concentration of NaCl chloride increases. High-speed video recording is an accurate technique to measure the percentage of bubble coalescence, and represents an important advance in gas-liquid interfacial studies.

Two-Dimensional Numerical Simulations of Ultrasound in Liquids with Gas Bubble Agglomerates: Examples of Bubbly-Liquid-Type Acoustic Metamaterials (BLAMMs)

PubMed Central

Vanhille, Christian

2017-01-01

This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding gas bubbles of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and several monodisperse bubble populations confined in restricted areas of a liquid have on ultrasound by calculating their nonlinear interaction. The filtering of an input ultrasonic pulse performed by a net of bubbly-liquid cells is analyzed. The generation of a low-frequency component from a single cell impinged by a two-frequency harmonic wave is also studied. These effects rely on the particular dispersive character of attenuation and nonlinearity of such bubbly fluids, which can be extremely high near bubble resonance. They allow us to observe how gas bubbles can change acoustic signals. Variations of the bubbly medium parameters induce alterations of the effects undergone by ultrasound. Results suggest that acoustic signals can be manipulated by bubbles. This capacity to achieve the modification and control of sound with oscillating gas bubbles introduces the concept of bubbly-liquid-based acoustic metamaterials (BLAMMs). PMID:28106748

Repeated bubble breakup and coalescence in perturbed Hele-Shaw channels

NASA Astrophysics Data System (ADS)

Thompson, Alice; Franco-Gomez, Andres; Hazel, Andrew; Juel, Anne

2017-11-01

The introduction of an axially-uniform, centred constriction in a Hele-Shaw channel leads to multiple propagation modes for both air fingers and bubbles, including symmetric and asymmetric steadily propagating modes along with oscillations. These multiple modes correspond to a non-trivial bifurcation structure, and relate to the plethora of steadily propagating bubbles and fingers which exist in the Saffman-Taylor system. In both experiments and depth-averaged computations, a very small centred occlusion can be enough to trigger bubble breakup, with a single large centred bubble splitting into two smaller bubbles which propagate along each side of the channel. We present numerical simulations for the depth-averaged model, implementing geometric criteria for pinchoff and coalescence in order to track the bubble before and beyond breakup. We find that the two-bubble state is itself unstable, with finger competition causing one bubble to move ahead; the trailing bubble then moves across the channel to merge with the leading bubble. However, the story is not always so simple, enabling complicated cascades of splitting and merging bubbles. We compare the general dynamical behaviour, basins of attraction, and the details of merging and splitting, to experimental observations.

Odds of observing the multiverse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahlen, A.

2010-03-15

Eternal inflation predicts that our observable universe lies within a bubble (or pocket universe) embedded in a volume of inflating space. The interior of the bubble undergoes inflation and standard cosmology, while the bubble walls expand outward and collide with other neighboring bubbles. The collisions provide either an opportunity to make a direct observation of the multiverse or, if they produce unacceptable anisotropy, a threat to inflationary theory. The probability of an observer in our bubble detecting the effects of collisions has an absolute upper bound set by the odds of being in the part of our bubble that liesmore » in the forward light cone of a collision; in the case of collisions with bubbles of identical vacua, this bound is given by the bubble nucleation rate times (H{sub O}/H{sub I}){sup 2}, where H{sub O} is the Hubble scale outside the bubbles and H{sub I} is the scale of the second round of inflation that occurs inside our bubble. Similar results were obtained by Freigovel et al. using a different method for the case of collisions with bubbles of much larger cosmological constant; here, it is shown to hold in the case of collisions with identical bubbles as well.« less

Observations of the collapses and rebounds of millimeter-sized lithotripsy bubbles

PubMed Central

Kreider, Wayne; Crum, Lawrence A.; Bailey, Michael R.; Sapozhnikov, Oleg A.

2011-01-01

Bubbles excited by lithotripter shock waves undergo a prolonged growth followed by an inertial collapse and rebounds. In addition to the relevance for clinical lithotripsy treatments, such bubbles can be used to study the mechanics of inertial collapses. In particular, both phase change and diffusion among vapor and noncondensable gas molecules inside the bubble are known to alter the collapse dynamics of individual bubbles. Accordingly, the role of heat and mass transport during inertial collapses is explored by experimentally observing the collapses and rebounds of lithotripsy bubbles for water temperatures ranging from 20 to 60 °C and dissolved gas concentrations from 10 to 85% of saturation. Bubble responses were characterized through high-speed photography and acoustic measurements that identified the timing of individual bubble collapses. Maximum bubble diameters before and after collapse were estimated and the corresponding ratio of volumes was used to estimate the fraction of energy retained by the bubble through collapse. The rebounds demonstrated statistically significant dependencies on both dissolved gas concentration and temperature. In many observations, liquid jets indicating asymmetric bubble collapses were visible. Bubble rebounds were sensitive to these asymmetries primarily for water conditions corresponding to the most dissipative collapses. PMID:22088027

Inertial collapse of bubble pairs near a solid surface

NASA Astrophysics Data System (ADS)

Alahyari Beig, Shahaboddin; Johnsen, Eric

2017-11-01

Cavitation occurs in a variety of applications ranging from naval structures to biomedical ultrasound. One important consequence is structural damage to neighboring surfaces following repeated inertial collapse of vapor bubbles. Although the mechanical loading produced by the collapse of a single bubble has been widely investigated, less is known about the detailed dynamics of the collapse of multiple bubbles. In such a problem, the bubble-bubble interactions typically affect the dynamics, e.g., by increasing the non-sphericity of the bubbles and amplifying/hindering the collapse intensity depending on the flow parameters. Here, we quantify the effects of bubble-bubble interactions on the bubble dynamics, as well as the pressures/temperatures produced by the collapse of a pair of gas bubbles near a rigid surface. We perform high-resolution simulations of this problem by solving the three-dimensional compressible Navier-Stokes equations for gas/liquid flows. The results are used to investigate the non-spherical bubble dynamics and characterize the pressure and temperature fields based on the relevant parameters entering the problem: stand-off distance, geometrical configuration (angle, relative size, distance), collapse strength. This research was supported in part by ONR Grant N00014-12-1-0751 and NSF Grant CBET 1253157.

Two-Dimensional Numerical Simulations of Ultrasound in Liquids with Gas Bubble Agglomerates: Examples of Bubbly-Liquid-Type Acoustic Metamaterials (BLAMMs).

PubMed

Vanhille, Christian

2017-01-17

This work deals with a theoretical analysis about the possibility of using linear and nonlinear acoustic properties to modify ultrasound by adding gas bubbles of determined sizes in a liquid. We use a two-dimensional numerical model to evaluate the effect that one and several monodisperse bubble populations confined in restricted areas of a liquid have on ultrasound by calculating their nonlinear interaction. The filtering of an input ultrasonic pulse performed by a net of bubbly-liquid cells is analyzed. The generation of a low-frequency component from a single cell impinged by a two-frequency harmonic wave is also studied. These effects rely on the particular dispersive character of attenuation and nonlinearity of such bubbly fluids, which can be extremely high near bubble resonance. They allow us to observe how gas bubbles can change acoustic signals. Variations of the bubbly medium parameters induce alterations of the effects undergone by ultrasound. Results suggest that acoustic signals can be manipulated by bubbles. This capacity to achieve the modification and control of sound with oscillating gas bubbles introduces the concept of bubbly-liquid-based acoustic metamaterials (BLAMMs).

A Study of Bubble and Slug Gas-Liquid Flow in a Microgravity Environment

NASA Technical Reports Server (NTRS)

McQuillen, J.

2000-01-01

The influence of gravity on the two-phase flow dynamics is obvious.As the gravity level is reduced,there is a new balance between inertial and interfacial forces, altering the behavior of the flow. In bubbly flow,the absence of drift velocity leads to spherical-shaped bubbles with a rectilinear trajectory.Slug flow is a succession of long bubbles and liquid slug carrying a few bubbles. There is no flow reversal in the thin liquid film as the long bubble and liquid slug pass over the film. Although the flow structure seems to be simpler than in normal gravity conditions,the models developed for the prediction of flow behavior in normal gravity and extended to reduced gravity flow are unable to predict the flow behavior correctly.An additional benefit of conducting studies in microgravity flows is that these studies aide the development of understanding for normal gravity flow behavior by removing the effects of buoyancy on the shape of the interface and density driven shear flows between the gas and the liquid phases. The proposal calls to study specifically the following: 1) The dynamics of isolated bubbles in microgravity liquid flows will be analyzed: Both the dynamics of spherical isolated bubbles and their dispersion by turbulence, their interaction with the pipe wall,the behavior of the bubbles in accelerated or decelerated flows,and the dynamics of isolated cylindrical bubbles, their deformation in accelerated/decelerated flows (in converging or diverging channels), and bubble/bubble interaction. Experiments will consist of the use of Particle Image Velocimetry (PIV) and Laser Doppler Velocimeters (LDV) to study single spherical bubble and single and two cylindrical bubble behavior with respect to their influence on the turbulence of the surrounding liquid and on the wall 2) The dynamics of bubbly and slug flow in microgravity will be analyzed especially for the role of the coalescence in the transition from bubbly to slug flow (effect of fluid properties and surfactant), to identify clusters that promote coalescence and transition the void fraction distribution in bubbly and slug flow,to measure the wall friction in bubbly flow. These experiments will consist of multiple bubbles type flows and will utilize hot wire and film anemometers to measure liquid velocity and wall shear stress respectively and double fiber optic probes to measure bubble size and velocity as a function of tube radius and axial location.

The Speed of Axial Propagation of a Cylindrical Bubble Through a Cylindrical Vortex

NASA Technical Reports Server (NTRS)

Shariff, Karim; Mansour, Nagi N. (Technical Monitor)

2002-01-01

Inspired by the rapid elongation of air columns injected into vortices by dolphins, we present an exact inviscid solution for the axial speed (assumed steady) of propagation of the tip of a semi-infinite cylindrical bubble along the axis of a cylindrical vortex. The bubble is assumed to be held at constant pressure by being connected to a reservoir, the lungs of the dolphin, say. For a given bubble pressure, there is a modest critical rotation rate above which steadily propagating bubbles exist. For a bubble at ambient pressure, the propagation speed of the bubble (relative to axial velocity within the vortex) varies between 0.5 and 0.6 of the maximum rotational speed of the vortex. Surprisingly, the bubble tip can propagate (almost as rapidly) even when the pressure minimum in the vortex core is greater than the bubble pressure; in this case, solutions exhibit a dimple on the nose of the bubble. A situation important for incipient vortex cavitation, and one which dolphins also demonstrate, is elongation of a free bubble, i.e., one whose internal pressure may vary. Under the assumption that the acceleration term is small (checked a posteriori), the steady solution is applied at each instant during the elongation. Three types of behavior are then possible depending on physical parameters and initial conditions: (A) Unabated elongation with slowly increasing bubble pressure, and nearly constant volume. Volume begins to decrease in the late stages. (B1) Elongation with decreasing bubble pressure. A limit point of the steady solution is encountered at a finite bubble length. (B2) Unabated elongation with decreasing bubble pressure and indefinite creation of volume. This is made possible by the existence of propagating solutions at bubble pressures below the minimum vortex pressure. As the bubble stretches, its radius initially decreases but then becomes constant; this is also observed in experiments on incipient vortex cavitation.

Size distributions of micro-bubbles generated by a pressurized dissolution method

NASA Astrophysics Data System (ADS)

Taya, C.; Maeda, Y.; Hosokawa, S.; Tomiyama, A.; Ito, Y.

2012-03-01

Size of micro-bubbles is widely distributed in the range of one to several hundreds micrometers and depends on generation methods, flow conditions and elapsed times after the bubble generation. Although a size distribution of micro-bubbles should be taken into account to improve accuracy in numerical simulations of flows with micro-bubbles, a variety of the size distribution makes it difficult to introduce the size distribution in the simulations. On the other hand, several models such as the Rosin-Rammler equation and the Nukiyama-Tanazawa equation have been proposed to represent the size distribution of particles or droplets. Applicability of these models to the size distribution of micro-bubbles has not been examined yet. In this study, we therefore measure size distribution of micro-bubbles generated by a pressurized dissolution method by using a phase Doppler anemometry (PDA), and investigate the applicability of the available models to the size distributions of micro-bubbles. Experimental apparatus consists of a pressurized tank in which air is dissolved in liquid under high pressure condition, a decompression nozzle in which micro-bubbles are generated due to pressure reduction, a rectangular duct and an upper tank. Experiments are conducted for several liquid volumetric fluxes in the decompression nozzle. Measurements are carried out at the downstream region of the decompression nozzle and in the upper tank. The experimental results indicate that (1) the Nukiyama-Tanasawa equation well represents the size distribution of micro-bubbles generated by the pressurized dissolution method, whereas the Rosin-Rammler equation fails in the representation, (2) the bubble size distribution of micro-bubbles can be evaluated by using the Nukiyama-Tanasawa equation without individual bubble diameters, when mean bubble diameter and skewness of the bubble distribution are given, and (3) an evaluation method of visibility based on the bubble size distribution and bubble number density is proposed, and the evaluated visibility agrees well with the visibility measured in the upper tank.

Transfer Ionization Studies for Proton on He - new Inside into the World of Correlation

NASA Astrophysics Data System (ADS)

Schmidt-Böcking, Horst

2005-04-01

Correlated many-particle dynamics in Coulombic systems, which is one of the unsolved fundamental problems in AMO-physics, can now be experimentally approached with so far unprecedented completeness and precision. The recent development of the COLTRIMS technique (COLd Target Recoil Ion Momentum Spectroscopy) provides a coincident multi-fragment imaging technique for eV and sub-eV fragment detection. In its completeness it is as powerful as the bubble chamber in high energy physics. In recent benchmark experiments quasi snapshots (duration as short an atto-sec) of the correlated dynamics between electrons and nuclei has been made for atomic and molecular objects. This new imaging technique has opened a powerful observation window into the hidden world of many-particle dynamics. Recent transfer ionization studies will be presented and the direct observation of correlated electron pairs will be discussed.

Air embolism during CT-guided transthoracic needle biopsy

PubMed Central

Lederer, Wolfgang; Schlimp, Christoph J; Glodny, Bernhard; Wiedermann, Franz J

2011-01-01

Air embolism (AE) is a potential complication during transthoracic needle biopsy (TNB). The authors report on venous and systemic AE during CT-guided TNB under general anaesthesia. During the intervention, the radiologist observed accumulation of air bubbles in the left heart chambers, in the right subclavian vein, the superior vena cava and the right atrium. This was presumably due to pressure infusion of contrast medium (CM) air entrained via a stop-cock improperly fixed to the venous cannula or via the injection valve of the cannula by Venturi forces. Prevention of AE related to CM infusion is a subject for institutional risk management. Stop-cocks and injection valves should not be used in intravenous lines supplied by pressure infusions. Adverse outcome may be avoided by placing the patient head down, increasing FiO2 to 1.0, administering antithrombotic therapy and immobilizing the patient on the intervention table until CT has proved complete remission of AE. PMID:22693299

Davisson-Germer Prize in Atomic or Surface Physics: The COLTRIMS multi-particle imaging technique-new Insight into the World of Correlation

NASA Astrophysics Data System (ADS)

Schmidt-Bocking, Horst

2008-05-01

The correlated many-particle dynamics in Coulombic systems, which is one of the unsolved fundamental problems in AMO-physics, can now be experimentally approached with so far unprecedented completeness and precision. The recent development of the COLTRIMS technique (COLd Target Recoil Ion Momentum Spectroscopy) provides a coincident multi-fragment imaging technique for eV and sub-eV fragment detection. In its completeness it is as powerful as the bubble chamber in high energy physics. In recent benchmark experiments quasi snapshots (duration as short as an atto-sec) of the correlated dynamics between electrons and nuclei has been made for atomic and molecular objects. This new imaging technique has opened a powerful observation window into the hidden world of many-particle dynamics. Recent multiple-ionization studies will be presented and the observation of correlated electron pairs will be discussed.

Predictions and measurements of isothermal flowfields in axisymmetric combustor geometries. Ph.D. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Rhodes, D. L.; Lilley, D. G.

1985-01-01

Numerical predictions, flow visualization experiments and time-mean velocity measurements were obtained for six basic nonreacting flowfields (with inlet swirl vane angles of 0 (swirler removed), 45 and 70 degrees and sidewall expansion angles of 90 and 45 degrees) in an idealized axisymmetric combustor geometry. A flowfield prediction computer program was developed which solves appropriate finite difference equations including a conventional two equation k-epsilon eddy viscosity turbulence model. The wall functions employed were derived from previous swirling flow measurements, and the stairstep approximation was employed to represent the sloping wall at the inlet to the test chamber. Recirculation region boundaries have been sketched from the entire flow visualization photograph collection. Tufts, smoke, and neutrally buoyant helium filled soap bubbles were employed as flow tracers. A five hole pitot probe was utilized to measure the axial, radial, and swirl time mean velocity components.

Inclusive strange-resonance production in pp,. pi. /sup +/p, and K/sup +/p interactions at 147 GeV/c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brick, D.; Rudnicka, H.; Shapiro, A.M.

1982-05-01

We have studied the inclusive production of K/sup asteriskplus-or-minus/(890) and Y/sup asteriskplus-or-minus/(1385) in pp, ..pi../sup +/p, and K/sup +/p interactions at 147 GeV/c. The experiment used the Fermilab 30-inch hydrogen bubble chamber with the hybrid spectrometer system. Results are based on a sample of 1916 observed K/sub S/ and 932 observed ..lambda... Inclusive cross sections are given for K/sup asteriskplus-or-minus/ and Y/sup asteriskplus-or-minus/ production from the three beams, and comparisons are made with experiments at other energies. Feynman-x and transverse-momentum-squared distributions are also calculated. The results suggest that the K/sup asterisk-/ is entirely produced in the central region, while themore » K/sup asterisk+/ includes a component from beam fragmentation. Comparisons are made with the additive quark model.« less

Cor triatriatum dexter: A rare cause of cyanosis during neonatal period.

PubMed

Alghamdi, Mohammed Hussien

2016-01-01

Cor-triatriatum dexter is an extremely rare congenital heart defect in which there is complete persistence of the right valve of embryonic sinus venosus that results in partitioning of the right atrium into a smooth and trabeculated portion. The smooth portion receives venous blood from inferior vena cava, superior vena cava, and coronary sinus while the trabeculated portion contains the right atrial appendage and the opening of tricuspid valve. We report a 1-week-old child who presented with intermittent episodes of central cyanosis. Echocardiography, established, and bubble contrast study confirmed the diagnosis of an isolated cor-triatriatum dexter. The baby initially underwent an intervention by cardiac catheterization, which was unsuccessful in disrupting the membrane and re-direct the systemic venous flow to the right heart chambers. She subsequently had the cor-triatriatum dexter membrane resected via an uncomplicated open-heart surgery.

Physical analysis of the process of cavitation in xylem sap.

PubMed

Shen, Fanyi; Gao, Rongfu; Liu, Wenji; Zhang, Wenjie

2002-06-01

Recent studies have confirmed that cavitation in xylem is caused by air bubbles. We analyzed expansion of a preexistent bubble adhering to a crack in a conduit wall and a bubble formed by the passage of air through a pore of a pit membrane, a process known as air seeding. We consider that there are two equilibrium states for a very small air bubble in the xylem: one is temporarily stable with a bubble radius r1 at point s1 on the curve P(r) relating pressure within the bubble (P) with bubble radius (r); the other is unstable with a bubble radius r2 at point s2 on Pr (where r1 < r2). In each equilibrium state, the bubble collapse pressure (2sigma/r, where sigma is surface tension of water) is balanced by the pressure difference across its surface. In the case of a bubble from a crack in a conduit wall, which is initially at point s1, expansion will occur steadily as water potential decreases. The bubble will burst only if the xylem pressure drops below a threshold value. A formula giving the threshold pressure for bubble bursting is proposed. In the case of an air seed entering a xylem conduit through a pore in a pit membrane, its initial radius may be r2 (i.e., the radius of the pore by which the air seed entered the vessel) at point s2 on Pr. Because the bubble is in an unstable equilibrium when entering the conduit, it can either expand or contract to point s1. As water vaporizes into the air bubble at s2, P rises until it exceeds the gas pressure that keeps the bubble in equilibrium, at which point the bubble will burst and induce a cavitation event in accordance with the air-seeding hypothesis. However, other possible perturbations could make the air-seeded bubble contract to s1, in which case the bubble will burst at a threshold pressure proposed for a bubble expanding from a crack in a conduit wall. For this reason some cavitation events may take place at a xylem threshold pressure (Pl'*) other than that determined by the formula, Plp'* = -2sigma/rp, proposed by Sperry and Tyree (1988), which is applicable only to air-seeded bubbles at s2. The more general formula we propose for calculating the threshold pressure for bubble breaking is consistent with the results of published experiments.

Modeling quiescent phase transport of air bubbles induced by breaking waves

NASA Astrophysics Data System (ADS)

Shi, Fengyan; Kirby, James T.; Ma, Gangfeng

Simultaneous modeling of both the acoustic phase and quiescent phase of breaking wave-induced air bubbles involves a large range of length scales from microns to meters and time scales from milliseconds to seconds, and thus is computational unaffordable in a surfzone-scale computational domain. In this study, we use an air bubble entrainment formula in a two-fluid model to predict air bubble evolution in the quiescent phase in a breaking wave event. The breaking wave-induced air bubble entrainment is formulated by connecting the shear production at the air-water interface and the bubble number intensity with a certain bubble size spectra observed in laboratory experiments. A two-fluid model is developed based on the partial differential equations of the gas-liquid mixture phase and the continuum bubble phase, which has multiple size bubble groups representing a polydisperse bubble population. An enhanced 2-DV VOF (Volume of Fluid) model with a k - ɛ turbulence closure is used to model the mixture phase. The bubble phase is governed by the advection-diffusion equations of the gas molar concentration and bubble intensity for groups of bubbles with different sizes. The model is used to simulate air bubble plumes measured in laboratory experiments. Numerical results indicate that, with an appropriate parameter in the air entrainment formula, the model is able to predict the main features of bubbly flows as evidenced by reasonable agreement with measured void fraction. Bubbles larger than an intermediate radius of O(1 mm) make a major contribution to void fraction in the near-crest region. Smaller bubbles tend to penetrate deeper and stay longer in the water column, resulting in significant contribution to the cross-sectional area of the bubble cloud. An underprediction of void fraction is found at the beginning of wave breaking when large air pockets take place. The core region of high void fraction predicted by the model is dislocated due to use of the shear production in the algorithm for initial bubble entrainment. The study demonstrates a potential use of an entrainment formula in simulations of air bubble population in a surfzone-scale domain. It also reveals some difficulties in use of the two-fluid model for predicting large air pockets induced by wave breaking, and suggests that it may be necessary to use a gas-liquid two-phase model as the basic model framework for the mixture phase and to develop an algorithm to allow for transfer of discrete air pockets to the continuum bubble phase. A more theoretically justifiable air entrainment formulation should be developed.

Study of bubble behavior in weightlessness (effects of thermal gradient and acoustic stationary wave) (M-16)

NASA Technical Reports Server (NTRS)

Azuma, H.

1993-01-01

The aim of this experiment is to understand how bubbles behave in a thermal gradient and acoustic stationary wave under microgravity. In microgravity, bubble or bubbles in a liquid will not rise upward as they do on Earth but will rest where they are formed because there exists no gravity-induced buoyancy. We are interested in how bubbles move and in the mechanisms which support the movement. We will try two ways to make bubbles migrate. The first experiment concerns behavior of bubbles in a thermal gradient. It is well known than an effect of surface tension which is masked by gravity on the ground becomes dominant in microgravity. The surface tension on the side of the bubble at a lower temperature is stronger than at a higher temperature. The bubble migrates toward the higher temperature side due to the surface tension difference. The migration speed depends on the so-called Marangoni number, which is a function of the temperature difference, the bubble diameter, liquid viscosity, and thermal diffusivity. At present, some experimental data about migration speeds in liquids with very small Marangoni numbers were obtained in space experiments, but cases of large Marangoni number are rarely obtained. In our experiment a couple of bubbles are to be injected into a cell filled with silicon oil, and the temperature gradient is to be made gradually in the cell by a heater and a cooler. We will be able to determine migration speeds in a very wide range of Marangoni numbers, as well as study interactions between the bubbles. We will observe bubble movements affected by hydrodynamical and thermal interactions, the two kinds of interactions which occur simultaneously. These observation data will be useful for analyzing the interactions as well as understanding the behavior of particles or drops in materials processing. The second experiment concerns bubble movement in an acoustic stationary wave. It is known that a bubble in a stationary wave moves toward the node or the loop according to whether its diameter is larger or smaller than that of the main resonant radius. In our experiment fine bubbles will be observed to move according to an acoustic field formed in a cylindrical cell. The existence of bubbles varies the acoustic speed, and the interactive force between bubbles will make the bubble behavior collective and complicated. This experiment will be very useful to development of bubble removable technology as well as to the understanding of bubble behavior.

Sleep-wake cycle of an unrestrained isolated chimpanzee under entrained and free running conditions.

NASA Technical Reports Server (NTRS)

Mcnew, J. J.; Burson, R. C.; Hoshizaki, T.; Adey, W. R.

1972-01-01

Biorhythmic patterns of EEG activity - the sleep-wake cycle and the sleep cycle - were investigated in an unrestrained chimpanzee subjected to 30 days of isolation in a 4-ft cubical cage placed in a high performance sound isolation chamber. The animal received 10 days of 12 hours of light and 12 hours of dark, then 10 days of continuous light, followed by 10 more days of 12 hours of light and 12 hours of dark. The circadian sleep-wake rhythm and the wake and sleep phases of this rhythm during entrained and free running conditions were analyzed in terms of duration. The awake and nonREM sleep and REM sleep stages were also analyzed. In addition, the mean duration of the sleep cycle of the sleep phase was computed.

Soap bubbles in paintings: Art and science

NASA Astrophysics Data System (ADS)

Behroozi, F.

2008-12-01

Soap bubbles became popular in 17th century paintings and prints primarily as a metaphor for the impermanence and fragility of life. The Dancing Couple (1663) by the Dutch painter Jan Steen is a good example which, among many other symbols, shows a young boy blowing soap bubbles. In the 18th century the French painter Jean-Simeon Chardin used soap bubbles not only as metaphor but also to express a sense of play and wonder. In his most famous painting, Soap Bubbles (1733/1734) a translucent and quavering soap bubble takes center stage. Chardin's contemporary Charles Van Loo painted his Soap Bubbles (1764) after seeing Chardin's work. In both paintings the soap bubbles have a hint of color and show two bright reflection spots. We discuss the physics involved and explain how keenly the painters have observed the interaction of light and soap bubbles. We show that the two reflection spots on the soap bubbles are images of the light source, one real and one virtual, formed by the curved surface of the bubble. The faint colors are due to thin film interference effects.

Dynamics and noise emission of laser induced cavitation bubbles in a vortical flow field

NASA Astrophysics Data System (ADS)

Oweis, Ghanem F.; Choi, Jaehyug; Ceccio, Steven L.

2004-03-01

The sound produced by the collapse of discrete cavitation bubbles was examined. Laser-generated cavitation bubbles were produced in both a quiescent and a vortical flow. The sound produced by the collapse of the cavitation bubbles was recorded, and its spectral content was determined. It was found that the risetime of the sound pulse produced by the collapse of single, spherical cavitation bubbles in quiescent fluid exceeded that of the slew rate of the hydrophone, which is consistent with previously published results. It was found that, as collapsing bubbles were deformed by the vortical flow, the acoustic impulse of the bubbles was reduced. Collapsing nonspherical bubbles often created a sound pulse with a risetime that exceeded that of the hydrophone slew rate, although the acoustic impulse created by the bubbles was influenced largely by the degree to which the bubbles became nonspherical before collapse. The noise produced by the slow growth of cavitation bubbles in the vortex core was not detectable. These results have implications for the interpretation of hydrodynamic cavitation noise produced by vortex cavitation.

On the effect of irradiation-induced resolution in modelling fission gas release in UO2 LWR fuel

NASA Astrophysics Data System (ADS)

Lösönen, Pekka

2017-12-01

Irradiation resolution of gas atoms and vacancies from intra- and intergranular bubbles in sintered UO2 fuel was studied by comparing macroscopic models with a more mechanistic approach. The applied macroscopic models imply the resolution rate of gas atoms to be proportional to gas concentration in intragranular bubbles and at grain boundary (including intergranular bubbles). A relation was established between the macroscopic models and a single encounter of an energetic fission fragment with a bubble. The effect of bubble size on resolution was quantified. The number of resoluted gas atoms per encounter of a fission fragment per bubble was of the same order of magnitude for intra- and intergranular bubbles. However, the resulting macroscopic resolution rate of gas atoms was about two orders of magnitude larger from intragranular bubbles. The number of vacancies resoluted from a grain face bubble by a passing fission fragment was calculated. The obtained correlations for resolution of gas atoms from intragranular bubbles and grain boundaries and for resolution of vacancies from grain face bubbles were used to demonstrate the effect of irradiation resolution on fission gas release.

Mathematical and experimental modelling of the dynamic bubble processes occurring in a two-phase cyclonic separation device

NASA Astrophysics Data System (ADS)

Schrage, Dean Stewart

1998-11-01

This dissertation presents a combined mathematical and experimental analysis of the fluid dynamics of a gas- liquid, dispersed-phase cyclonic separation device. The global objective of this research is to develop a simulation model of separation process in order to predict the void fraction field within a cyclonic separation device. The separation process is approximated by analyzing the dynamic motion of many single-bubbles, moving under the influence of the far-field, interacting with physical boundaries and other bubbles. The dynamic motion of the bubble is described by treating the bubble as a point-mass and writing an inertial force balance, equating the force applied to the bubble-point-location to the inertial acceleration of the bubble mass (also applied to the point-location). The forces which are applied to the bubble are determined by an integration of the surface pressure over the bubble. The surface pressure is coupled to the intrinsic motion of the bubble, and is very difficult to obtain exactly. However, under moderate Reynolds number, the wake trailing a bubble is small and the near-field flow field can be approximated as an inviscid flow field. Unconventional potential flow techniques are employed to solve for the surface pressure; the hydrodyamic forces are described as a hydrodynamic mass tensor operating on the bubble acceleration vector. The inviscid flow model is augmented with adjunct forces which describe: drag forces, dynamic lift, far-field pressure forces. The dynamic equations of motion are solved both analytically and numerically for the bubble trajectory in specific flow field examples. A validation of these equations is performed by comparing to an experimentally-derived trajectory of a single- bubble, which is released into a cylindrical Couette flow field (inner cylinder rotating) at varying positions. Finally, a simulation of a cyclonic separation device is performed by extending the single-bubble dynamic model to a multi-bubble ensemble. A simplified model is developed to predict the effects of bubble-interaction. The simulation qualitatively depicts the separation physics encountered in an actual cyclonic separation device, supporting the original tenet that the separation process can be approximated by the collective motions of single- bubbles.

Evaluation of stability and size distribution of sunflower oil-coated micro bubbles for localized drug delivery.

PubMed

Filho, Walter Duarte de Araujo; Schneider, Fábio Kurt; Morales, Rigoberto E M

2012-09-20

Micro bubbles were initially introduced as contrast agents for ultrasound examinations as they are able to modify the signal-to-noise ratio in imaging, thus improving the assessment of clinical information on human tissue. Recent developments have demonstrated the feasibility of using these bubbles as drug carriers in localized delivery. In micro fluidics devices for generation of micro bubbles, the bubbles are formed at interface of liquid gas through a strangulation process. A device that uses these features can produce micro bubbles with small size dispersion in a single step. A T-junction micro fluidic device constructed using 3D prototyping was made for the production of mono dispersed micro bubbles. These micro bubbles use sunflower oil as a lipid layer. Stability studies for micro bubbles with diameters different generated from a liquid phase of the same viscosity were conducted to evaluate whether micro bubbles can be used as drug carriers. The biocompatibility of coating layer, the ability to withstand environmental pressure variations combined with echogenicity, are key factors that they can safely play the role of drug transporters. The normal distribution curve with small dispersion of the diameter of bubbles validates the process of generating micro bubbles with low value of variation coefficient, i.e., 0.381 at 1.90%. The results also showed the feasibility of using sunflower oil as the lipid matrix with stable population of bubbles over 217 minutes for micro bubbles with an average diameter of 313.04 μm and 121 minutes for micro bubbles with an average diameter of 73.74 μm, considering bubbles with air as gaseous phase. The results indicate that the micro fluidic device designed can be used for producing micro bubbles with low variation coefficient using sunflower oil as a coating of micro bubbles. These carriers were stable for periods of time that are long enough for clinical applications even when regular air is used as the gas phase. Improved stability can be achieved when biocompatible gas with lower permeability is used.

A simple chip free-flow electrophoresis for monosaccharide sensing via supermolecule interaction of boronic acid functionalized quencher and fluorescent dye.

PubMed

Yin, Xiao-Yang; Dong, Jing-Yu; Wang, Hou-Yu; Li, Si; Fan, Liu-Yin; Cao, Cheng-Xi

2013-08-01

Here, a simple micro free-flow electrophoresis (μFFE) was developed for fluorescence sensing of monosaccharide via supermolecule interaction of synthesized boronic acid functionalized benzyl viologen (ο-BBV) and fluorescent dye. The μFFE contained two open electrode cavities and an ion-exchange membrane was sandwiched between two polymethylmethacrylate plates. The experiments demonstrated the following merits of developed μFFE: (i) up to 90.5% of voltage efficiency due to high conductivity of ion-exchange membrane; (ii) a strong ability against influence of bubble produced in two electrodes due to open design of electrode cavities; and (iii) reusable and washable separation chamber (45 mm × 17 mm × 100 μm, 77 μL) avoiding the discard of μFFE due to blockage of solute precipitation in chamber. Remarkably, the μFFE was first designed for the sensing of monosaccharide via the supermolecule interaction of synthesized ο-BBV, fluorescent dye, and monosaccharide. Under the optimized conditions, the minimum concentration of monosaccharide that could be detected was 1 × 10(-11) M. Finally, the developed device was used for the detection of 0.3 mM glucose spiked in human urine. All of the results demonstrated the feasibility of monosaccharide detection via the μFFE. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Air bubble migration is a random event post embryo transfer.

PubMed

Confino, E; Zhang, J; Risquez, F

2007-06-01

Air bubble location following embryo transfer (ET) is the presumable placement spot of embryos. The purpose of this study was to document endometrial air bubble position and migration following embryo transfer. Multicenter prospective case study. Eighty-eight embryo transfers were performed under abdominal ultrasound guidance in two countries by two authors. A single or double air bubble was loaded with the embryos using a soft, coaxial, end opened catheters. The embryos were slowly injected 10-20 mm from the fundus. Air bubble position was recorded immediately, 30 minutes later and when the patient stood up. Bubble marker location analysis revealed a random distribution without visible gravity effect when the patients stood up. The bubble markers demonstrated splitting, moving in all directions and dispersion. Air bubbles move and split frequently post ET with the patient in the horizontal position, suggestive of active uterine contractions. Bubble migration analysis supports a rather random movement of the bubbles and possibly the embryos. Standing up changed somewhat bubble configuration and distribution in the uterine cavity. Gravity related bubble motion was uncommon, suggesting that horizontal rest post ET may not be necessary. This report challenges the common belief that a very accurate ultrasound guided embryo placement is mandatory. The very random bubble movement observed in this two-center study suggests that a large "window" of embryo placement maybe present.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Shenyang; Setyawan, Wahyu; Joshi, Vineet V.

Xe gas bubble superlattice formation is observed in irradiated uranium–10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble growth and superlattice formation are not well known. In this work, molecular dynamics is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the molecular dynamics simulations, the embedded-atom method (EAM) potential of U10Mo-Xe (Smirnova et al. 2013) is employed. Initial gas bubbles with low Xe concentration aremore » generated in a U10Mo single crystal. Then Xe atom atoms are continuously added into the bubbles, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that the gas bubble growth is accompanied by partial dislocation emission, which results in a star-shaped dislocation structure and an anisotropic stress field. The emitted partial dislocations have a Burgers vector along the <111> direction and a slip plane of (11-2). Dislocation loop punch-out was not observed. A tensile stress was found along <110> directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in body-centered cubic U10Mo fuels.« less

Modelling cavitation erosion using fluid–material interaction simulations

PubMed Central

Chahine, Georges L.; Hsiao, Chao-Tsung

2015-01-01

Material deformation and pitting from cavitation bubble collapse is investigated using fluid and material dynamics and their interaction. In the fluid, a novel hybrid approach, which links a boundary element method and a compressible finite difference method, is used to capture non-spherical bubble dynamics and resulting liquid pressures efficiently and accurately. The bubble dynamics is intimately coupled with a finite-element structure model to enable fluid/structure interaction simulations. Bubble collapse loads the material with high impulsive pressures, which result from shock waves and bubble re-entrant jet direct impact on the material surface. The shock wave loading can be from the re-entrant jet impact on the opposite side of the bubble, the fast primary collapse of the bubble, and/or the collapse of the remaining bubble ring. This produces high stress waves, which propagate inside the material, cause deformation, and eventually failure. A permanent deformation or pit is formed when the local equivalent stresses exceed the material yield stress. The pressure loading depends on bubble dynamics parameters such as the size of the bubble at its maximum volume, the bubble standoff distance from the material wall and the pressure driving the bubble collapse. The effects of standoff and material type on the pressure loading and resulting pit formation are highlighted and the effects of bubble interaction on pressure loading and material deformation are preliminarily discussed. PMID:26442140

A study of the accuracy of neutrally buoyant bubbles used as flow tracers in air

NASA Technical Reports Server (NTRS)

Kerho, Michael F.

1993-01-01

Research has been performed to determine the accuracy of neutrally buoyant and near neutrally buoyant bubbles used as flow tracers in air. Theoretical, computational, and experimental results are presented to evaluate the dynamics of bubble trajectories and factors affecting their ability to trace flow-field streamlines. The equation of motion for a single bubble was obtained and evaluated using a computational scheme to determine the factors which affect a bubble's trajectory. A two-dimensional experiment was also conducted to experimentally determine bubble trajectories in the stagnation region of NACA 0012 airfoil at 0 deg angle of attack using a commercially available helium bubble generation system. Physical properties of the experimental bubble trajectories were estimated using the computational scheme. These properties included the density ratio and diameter of the individual bubbles. the helium bubble system was then used to visualize and document the flow field about a 30 deg swept semispan wing with simulated glaze ice. Results were compared to Navier-Stokes calculations and surface oil flow visualization. The theoretical and computational analysis have shown that neutrally buoyant bubbles will trace even the most complex flow patterns. Experimental analysis revealed that the use of bubbles to trace flow patterns should be limited to qualitative measurements unless care is taken to ensure neutral buoyancy. This is due to the difficulty in the production of neutrally buoyant bubbles.

Magnetic skyrmion bubble motion driven by surface acoustic waves

DOE PAGES

Nepal, Rabindra; Güngördü, Utkan; Kovalev, Alexey A.

2018-03-12

Here, we study the dynamical control of a magnetic skyrmion bubble by using counter-propagating surface acoustic waves (SAWs) in a ferromagnet. First, we determine the bubble mass and derive the force due to SAWs acting on a magnetic bubble using Thiele’s method. The force that pushes the bubble is proportional to the strain gradient for the major strain component. We then study the dynamical pinning and motion of magnetic bubbles by SAWs in a nanowire. In a disk geometry, we propose a SAWs-driven skyrmion bubble oscillator with two resonant frequencies.

Magnetic skyrmion bubble motion driven by surface acoustic waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nepal, Rabindra; Güngördü, Utkan; Kovalev, Alexey A.

Here, we study the dynamical control of a magnetic skyrmion bubble by using counter-propagating surface acoustic waves (SAWs) in a ferromagnet. First, we determine the bubble mass and derive the force due to SAWs acting on a magnetic bubble using Thiele’s method. The force that pushes the bubble is proportional to the strain gradient for the major strain component. We then study the dynamical pinning and motion of magnetic bubbles by SAWs in a nanowire. In a disk geometry, we propose a SAWs-driven skyrmion bubble oscillator with two resonant frequencies.

Lithotripter shock wave interaction with a bubble near various biomaterials.

PubMed

Ohl, S W; Klaseboer, E; Szeri, A J; Khoo, B C

2016-10-07

Following previous work on the dynamics of an oscillating bubble near a bio-material (Ohl et al 2009 Phys. Med. Biol. 54 6313-36) and the interaction of a bubble with a shockwave (Klaseboer et al 2007 J. Fluid Mech. 593 33-56), the present work concerns the interaction of a gas bubble with a traveling shock wave (such as from a lithotripter) in the vicinity of bio-materials such as fat, skin, muscle, cornea, cartilage, and bone. The bubble is situated in water (to represent a water-like biofluid). The bubble collapses are not spherically symmetric, but tend to feature a high speed jet. A few simulations are performed and compared with available experimental observations from Sankin and Zhong (2006 Phys. Rev. E 74 046304). The collapses of cavitation bubbles (created by laser in the experiment) near an elastic membrane when hit by a lithotripter shock wave are correctly captured by the simulation. This is followed by a more systematic study of the effects involved concerning shockwave bubble biomaterial interactions. If a subsequent rarefaction wave hits the collapsed bubble, it will re-expand to a very large size straining the bio-materials nearby before collapsing once again. It is noted that, for hard bio-material like bone, reflection of the shock wave at the bone-water interface can affect the bubble dynamics. Also the initial size of the bubble has a significant effect. Large bubbles (∼1 mm) will split into smaller bubbles, while small bubbles collapse with a high speed jet in the travel direction of the shock wave. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a shock wave, and a nearby bio-material.

Lithotripter shock wave interaction with a bubble near various biomaterials

NASA Astrophysics Data System (ADS)

Ohl, S. W.; Klaseboer, E.; Szeri, A. J.; Khoo, B. C.

2016-10-01

Following previous work on the dynamics of an oscillating bubble near a bio-material (Ohl et al 2009 Phys. Med. Biol. 54 6313-36) and the interaction of a bubble with a shockwave (Klaseboer et al 2007 J. Fluid Mech. 593 33-56), the present work concerns the interaction of a gas bubble with a traveling shock wave (such as from a lithotripter) in the vicinity of bio-materials such as fat, skin, muscle, cornea, cartilage, and bone. The bubble is situated in water (to represent a water-like biofluid). The bubble collapses are not spherically symmetric, but tend to feature a high speed jet. A few simulations are performed and compared with available experimental observations from Sankin and Zhong (2006 Phys. Rev. E 74 046304). The collapses of cavitation bubbles (created by laser in the experiment) near an elastic membrane when hit by a lithotripter shock wave are correctly captured by the simulation. This is followed by a more systematic study of the effects involved concerning shockwave bubble biomaterial interactions. If a subsequent rarefaction wave hits the collapsed bubble, it will re-expand to a very large size straining the bio-materials nearby before collapsing once again. It is noted that, for hard bio-material like bone, reflection of the shock wave at the bone—water interface can affect the bubble dynamics. Also the initial size of the bubble has a significant effect. Large bubbles (˜1 mm) will split into smaller bubbles, while small bubbles collapse with a high speed jet in the travel direction of the shock wave. The numerical model offers a computationally efficient way of understanding the complex phenomena involving the interplay of a bubble, a shock wave, and a nearby bio-material.

An evaluation of bubble-CPAP in a neonatal unit in a developing country: effective respiratory support that can be applied by nurses.

PubMed

Koyamaibole, Lanieta; Kado, Joseph; Qovu, Josaia D; Colquhoun, Samantha; Duke, Trevor

2006-08-01

To describe the implementation of bubble-CPAP in a referral hospital in a developing country and to investigate: the feasibility of nurses implementing bubble-CPAP and the impact of bubble-CPAP on need for mechanical ventilation and mortality. Retrospective evaluation of prospectively collected data from two time periods: 18 months before and 18 months after the introduction of bubble-CPAP. The introduction of bubble-CPAP was associated with a 50 per cent reduction in the need for mechanical ventilation; from 113 of 1,106 (10.2 per cent) prior to bubble-CPAP to 70 of 1,382 (5.1%) after introduction of CPAP (chi2, p<0.001). In the 18 months prior to bubble-CPAP there were 79 deaths (case fatality of 7.1 per cent). In the 18 months after bubble-CPAP there were 74 deaths (CF 5.4 per cent), relative risk: 0.75 (0.55-1.02, chi2, p=0.065). Nurses could safely apply bubble-CPAP after 1-2 months of on-the-job training. Equipment for Bubble-CPAP cost 15 per cent of the cost of the cheapest mechanical ventilator. The introduction of bubble-CPAP substantially reduced the need for mechanical ventilation, with no difference in mortality. In models of neonatal care for resource-limited countries, bubble-CPAP may be the first type of ventilatory support that is recommended. Its low cost and safety when administered by nurses makes it ideal for this purpose. Bubble-CPAP has the potential for being available at even lower cost than the current commercially available bubble systems used in this study.

Time-evolving bubbles in two-dimensional stokes flow

NASA Technical Reports Server (NTRS)

Tanveer, Saleh; Vasconcelos, Giovani L.

1994-01-01

A general class of exact solutions is presented for a time evolving bubble in a two-dimensional slow viscous flow in the presence of surface tension. These solutions can describe a bubble in a linear shear flow as well as an expanding or contracting bubble in an otherwise quiescent flow. In the case of expanding bubbles, the solutions have a simple behavior in the sense that for essentially arbitrary initial shapes the bubble will asymptote an expanding circle. Contracting bubbles, on the other hand, can develop narrow structures ('near-cusps') on the interface and may undergo 'break up' before all the bubble-fluid is completely removed. The mathematical structure underlying the existence of these exact solutions is also investigated.

Bubble colloidal AFM probes formed from ultrasonically generated bubbles.

PubMed

Vakarelski, Ivan U; Lee, Judy; Dagastine, Raymond R; Chan, Derek Y C; Stevens, Geoffrey W; Grieser, Franz

2008-02-05

Here we introduce a simple and effective experimental approach to measuring the interaction forces between two small bubbles (approximately 80-140 microm) in aqueous solution during controlled collisions on the scale of micrometers to nanometers. The colloidal probe technique using atomic force microscopy (AFM) was extended to measure interaction forces between a cantilever-attached bubble and surface-attached bubbles of various sizes. By using an ultrasonic source, we generated numerous small bubbles on a mildly hydrophobic surface of a glass slide. A single bubble picked up with a strongly hydrophobized V-shaped cantilever was used as the colloidal probe. Sample force measurements were used to evaluate the pure water bubble cleanliness and the general consistency of the measurements.

Simulations of Bubble Motion in an Oscillating Liquid

NASA Astrophysics Data System (ADS)

Kraynik, A. M.; Romero, L. A.; Torczynski, J. R.

2010-11-01

Finite-element simulations are used to investigate the motion of a gas bubble in a liquid undergoing vertical vibration. The effect of bubble compressibility is studied by comparing "compressible" bubbles that obey the ideal gas law with "incompressible" bubbles that are taken to have constant volume. Compressible bubbles exhibit a net downward motion away from the free surface that does not exist for incompressible bubbles. Net (rectified) velocities are extracted from the simulations and compared with theoretical predictions. The dependence of the rectified velocity on ambient gas pressure, bubble diameter, and bubble depth are in agreement with the theory. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Formation and evolution of bubbly screens in confined oscillating bubbly liquids.

PubMed

Shklyaev, Sergey; Straube, Arthur V

2010-01-01

We consider the dynamics of dilute monodisperse bubbly liquid confined by two plane solid walls and subject to small-amplitude high-frequency oscillations normal to the walls. The initial state corresponds to the uniform distribution of bubbles and motionless liquid. The period of external driving is assumed much smaller than typical relaxation times for a single bubble but larger than the period of volume eigenoscillations. The time-averaged description accounting for the two-way coupling between the liquid and the bubbles is applied. We show that the model predicts accumulation of bubbles in thin sheets parallel to the walls. These singular structures, which are formally characterized by infinitely thin width and infinitely high concentration, are referred to as bubbly screens. The formation of a bubbly screen is described analytically in terms of a self-similar solution, which is in agreement with numerical simulations. We study the evolution of bubbly screens and detect a one-dimensional stationary state, which is shown to be unconditionally unstable.