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.

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.

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.

On the Physics of Fizziness: How liquid properties control bursting bubble aerosol production?

NASA Astrophysics Data System (ADS)

Ghabache, Elisabeth; Antkowiak, Arnaud; Josserand, Christophe; Seon, Thomas

2014-11-01

Either in a champagne glass or at the oceanic scales, the tiny capillary bubbles rising at the surface burst in ejecting myriads of droplets. Focusing on the ejected droplets produced by a single bubble, we investigate experimentally how liquid properties and bubble size affect their characteristics: number, ejection velocities, sizes and ejection heights. These results allow us to finely tune the bursting bubble aerosol production. In the context of champagne industry, aerosols play a major role by spreading wine aroma above the glass. We demonstrate that this champagne fizz can be enhanced by selecting the wine viscosity and the bubble size, thanks to specially designed glass.

An assembly of steadily translating bubbles in a Hele-Shaw channel

NASA Astrophysics Data System (ADS)

Crowdy, Darren

2009-01-01

This paper presents new solutions for any finite number of bubbles steadily translating along a Hele-Shaw channel. This constitutes a nonlinear free boundary problem. The solutions can be written down explicitly in terms of a special transcendental function called the Schottky-Klein prime function. This work generalizes the exact solutions for a single bubble in a channel found by Tanveer (1987 Phys. Fluids 30 651-8) as well as the solutions for streams of bubbles aligned along the channel centreline due to Vasconcelos (1994 Phys. Rev. E 50 R3306-9).

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

Rod-shaped cavitation bubble structure in ultrasonic field.

PubMed

Bai, Lixin; Wu, Pengfei; Liu, Huiyu; Yan, Jiuchun; Su, Chang; Li, Chao

2018-06-01

Rod-shaped cavitation bubble structure in thin liquid layers in ultrasonic field is investigated experimentally. It is found that cavitation structure successively experiences several stages with the change of the thickness of the thin liquid layer. Rod-shaped structure is a stable structure of the boundary between the cavitation cloud region and the non-cavitation liquid region, which can be formed in two different ways. Cavitation bubbles in a thin liquid layer have a distribution in the thickness direction. The rod-shaped structures tend to crosslink with each other to form stable Y-branch structures. The angle of the Y-branch structure is Gauss distribution with mathematical expectation μ = 119.93. A special rod-shaped cavitation structure with source is also investigated in detail. Due to the pressure gradient in the normal direction, the primary Bjerknes force causes the bubbles in the rod-shaped structure on both sides to converge to the axis. The secondary Bjerknes forces between the bubbles also make the cluster converge, so the large bubbles which are attached to the radiating surface tend to align themselves along the central line. According to the formula deduced in this paper, the variation of curvature of curved rod-shaped structure is qualitatively analyzed. The Y-branch structure of cavitation cloud and Plateau boundary of soap bubbles are compared. Copyright © 2018 Elsevier B.V. All rights reserved.

Bubbles

NASA Astrophysics Data System (ADS)

Prosperetti, Andrea

2004-06-01

Vanitas vanitatum et omnia vanitas: bubbles are emptiness, non-liquid, a tiny cloud shielding a mathematical singularity. Born from chance, a violent and brief life ending in the union with the (nearly) infinite. But a wealth of phenomena spring forth from this nothingness: underwater noise, sonoluminescence, boiling, and many others. Some recent results on a "blinking bubble" micropump and vapor bubbles in sound fields are outlined. The last section describes Leonardo da Vinci's observation of the non-rectlinear ascent of buoyant bubbles and justifies the name Leonardo's paradox recently attributed to this phenomenon.

Freezing Bubbles

NASA Astrophysics Data System (ADS)

Kingett, Christian; Ahmadi, Farzad; Nath, Saurabh; Boreyko, Jonathan

2017-11-01

The two-stage freezing process of a liquid droplet on a substrate is well known; however, how bubbles freeze has not yet been studied. We first deposited bubbles on a silicon substrate that was chilled at temperatures ranging from -10 °C to -40 °C, while the air was at room temperature. We observed that the freeze front moved very slowly up the bubble, and in some cases, even came to a complete halt at a critical height. This slow freezing front propagation can be explained by the low thermal conductivity of the thin soap film, and can be observed more clearly when the bubble size or the surface temperature is increased. This delayed freezing allows the frozen portion of the bubble to cool the air within the bubble while the top part is still liquid, which induces a vapor pressure mismatch that either collapses the top or causes the top to pop. In cases where the freeze front reaches the top of the bubble, a portion of the top may melt and slowly refreeze; this can happen more than just once for a single bubble. We also investigated freezing bubbles inside of a freezer where the air was held at -20 °C. In this case, the bubbles freeze quickly and the ice grows radially from nucleation sites instead of perpendicular to the surface, which provides a clear contrast with the conduction limited room temperature bubbles.

Condensation of vapor bubble in subcooled pool

NASA Astrophysics Data System (ADS)

Horiuchi, K.; Koiwa, Y.; Kaneko, T.; Ueno, I.

2017-02-01

We focus on condensation process of vapor bubble exposed to a pooled liquid of subcooled conditions. Two different geometries are employed in the present research; one is the evaporation on the heated surface, that is, subcooled pool boiling, and the other the injection of vapor into the subcooled pool. The test fluid is water, and all series of the experiments are conducted under the atmospheric pressure condition. The degree of subcooling is ranged from 10 to 40 K. Through the boiling experiment, unique phenomenon known as microbubble emission boiling (MEB) is introduced; this phenomenon realizes heat flux about 10 times higher than the critical heat flux. Condensation of the vapor bubble is the key phenomenon to supply ambient cold liquid to the heated surface. In order to understand the condensing process in the MEB, we prepare vapor in the vapor generator instead of the evaporation on the heated surface, and inject the vapor to expose the vapor bubble to the subcooled liquid. Special attention is paid to the dynamics of the vapor bubble detected by the high-speed video camera, and on the enhancement of the heat transfer due to the variation of interface area driven by the condensation.

Bubble, Bubble, Toil and Trouble.

ERIC Educational Resources Information Center

Journal of Chemical Education, 2001

2001-01-01

Bubbles are a fun way to introduce the concepts of surface tension, intermolecular forces, and the use of surfactants. Presents two activities in which students add chemicals to liquid dishwashing detergent with water in order to create longer lasting bubbles. (ASK)

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.

Bubble Size Distribution in a Vibrating Bubble Column

NASA Astrophysics Data System (ADS)

Mohagheghian, Shahrouz; Wilson, Trevor; Valenzuela, Bret; Hinds, Tyler; Moseni, Kevin; Elbing, Brian

2016-11-01

While vibrating bubble columns have increased the mass transfer between phases, a universal scaling law remains elusive. Attempts to predict mass transfer rates in large industrial scale applications by extrapolating laboratory scale models have failed. In a stationary bubble column, mass transfer is a function of phase interfacial area (PIA), while PIA is determined based on the bubble size distribution (BSD). On the other hand, BSD is influenced by the injection characteristics and liquid phase dynamics and properties. Vibration modifies the BSD by impacting the gas and gas-liquid dynamics. This work uses a vibrating cylindrical bubble column to investigate the effect of gas injection and vibration characteristics on the BSD. The bubble column has a 10 cm diameter and was filled with water to a depth of 90 cm above the tip of the orifice tube injector. BSD was measured using high-speed imaging to determine the projected area of individual bubbles, which the nominal bubble diameter was then calculated assuming spherical bubbles. The BSD dependence on the distance from the injector, injector design (1.6 and 0.8 mm ID), air flow rates (0.5 to 5 lit/min), and vibration conditions (stationary and vibration conditions varying amplitude and frequency) will be presented. In addition to mean data, higher order statistics will also be provided.

Simulation and analysis of collapsing vapor-bubble clusters with special emphasis on potentially erosive impact loads at walls

NASA Astrophysics Data System (ADS)

Ogloblina, Daria; Schmidt, Steffen J.; Adams, Nikolaus A.

2018-06-01

Cavitation is a process where a liquid evaporates due to a pressure drop and re-condenses violently. Noise, material erosion and altered system dynamics characterize for such a process for which shock waves, rarefaction waves and vapor generation are typical phenomena. The current paper presents novel results for collapsing vapour-bubble clusters in a liquid environment close to a wall obtained by computational fluid mechanics (CFD) simulations. The driving pressure initially is 10 MPa in the liquid. Computations are carried out by using a fully compressible single-fluid flow model in combination with a conservative finite volume method (FVM). The investigated bubble clusters (referred to as "clouds") differ by their initial vapor volume fractions, initial stand-off distances to the wall and by initial bubble radii. The effects of collapse focusing due to bubble-bubble interaction are analysed by investigating the intensities and positions of individual bubble collapses, as well as by the resulting shock-induced pressure field at the wall. Stronger interaction of the bubbles leads to an intensification of the collapse strength for individual bubbles, collapse focusing towards the center of the cloud and enhanced re-evaporation. The obtained results reveal collapse features which are common for all cases, as well as case-specific differences during collapse-rebound cycles. Simultaneous measurements of maximum pressures at the wall and within the flow field and of the vapor volume evolution show that not only the primary collapse but also subsequent collapses are potentially relevant for erosion.

Stationary bubble formation and cavity collapse in wedge-shaped hoppers

PubMed Central

Yagisawa, Yui; Then, Hui Zee; Okumura, Ko

2016-01-01

The hourglass is one of the apparatuses familiar to everyone, but reveals intriguing behaviors peculiar to granular materials, and many issues are remained to be explored. In this study, we examined the dynamics of falling sand in a special form of hourglass, i.e., a wedge-shaped hopper, when a suspended granular layer is stabilized to a certain degree. As a result, we found remarkably different dynamic regimes of bubbling and cavity. In the bubbling regime, bubbles of nearly equal size are created in the sand at a regular time interval. In the cavity regime, a cavity grows as sand beads fall before a sudden collapse of the cavity. Bubbling found here is quite visible to a level never discussed in the physics literature and the cavity regime is a novel phase, which is neither continuous, intermittent nor completely blocked phase. We elucidate the physical conditions necessary for the bubbling and cavity regimes and develop simple theories for the regimes to successfully explain the observed phenomena by considering the stability of a suspended granular layer and clogging of granular flow at the outlet of the hopper. The bubbling and cavity regimes could be useful for mixing a fluid with granular materials. PMID:27138747

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.

Ultrasonic bubbles in medicine: influence of the shell.

PubMed

Postema, Michiel; Schmitz, Georg

2007-04-01

Ultrasound contrast agents consist of microscopically small bubbles encapsulated by an elastic shell. These microbubbles oscillate upon ultrasound insonification, and demonstrate highly nonlinear behavior, ameliorating their detectability. (Potential) medical applications involving the ultrasonic disruption of contrast agent microbubble shells include release-burst imaging, localized drug delivery, and noninvasive blood pressure measurement. To develop and enhance these techniques, predicting the cracking behavior of ultrasound-insonified encapsulated microbubbles has been of importance. In this paper, we explore microbubble behavior in an ultrasound field, with special attention to the influence of the bubble shell. A bubble in a sound field can be considered a forced damped harmonic oscillator. For encapsulated microbubbles, the presence of a shell has to be taken into account. In models, an extra damping parameter and a shell stiffness parameter have been included, assuming that Hooke's Law holds for the bubble shell. At high acoustic amplitudes, disruptive phenomena have been observed, such as microbubble fragmentation and ultrasonic cracking. We analyzed the occurrence of ultrasound contrast agent fragmentation, by simulating the oscillating behavior of encapsulated microbubbles with various sizes in a harmonic acoustic field. Fragmentation occurs exclusively during the collapse phase and occurs if the kinetic energy of the collapsing microbubble is greater than the instantaneous bubble surface energy, provided that surface instabilities have grown big enough to allow for break-up. From our simulations it follows that the Blake critical radius is not a good approximation for a fragmentation threshold. We demonstrated how the phase angle differences between a damped radially oscillating bubble and an incident sound field depend on shell parameters.

Bubble diagnostics

DOEpatents

Visuri, Steven R.; Mammini, Beth M.; Da Silva, Luiz B.; Celliers, Peter M.

2003-01-01

The present invention is intended as a means of diagnosing the presence of a gas bubble and incorporating the information into a feedback system for opto-acoustic thrombolysis. In opto-acoustic thrombolysis, pulsed laser radiation at ultrasonic frequencies is delivered intraluminally down an optical fiber and directed toward a thrombus or otherwise occluded vessel. Dissolution of the occlusion is therefore mediated through ultrasonic action of propagating pressure or shock waves. A vapor bubble in the fluid surrounding the occlusion may form as a result of laser irradiation. This vapor bubble may be used to directly disrupt the occlusion or as a means of producing a pressure wave. It is desirable to detect the formation and follow the lifetime of the vapor bubble. Knowledge of the bubble formation and lifetime yields critical information as to the maximum size of the bubble, density of the absorbed radiation, and properties of the absorbing material. This information can then be used in a feedback system to alter the irradiation conditions.

Pearls of mandibular trauma management.

PubMed

Koshy, John C; Feldman, Evan M; Chike-Obi, Chuma J; Bullocks, Jamal M

2010-11-01

Mandibular trauma is a common problem seen by plastic surgeons. When fractures occur, they have the ability to affect the patient's occlusion significantly, cause infection, and lead to considerable pain. Interventions to prevent these sequelae require either closed or open forms of reduction and fixation. Physicians determining how to manage these injuries should take into consideration the nature of the injury, background information regarding the patient's health, and the patient's comorbidities. Whereas general principles guide the management of the majority of injuries, special consideration must be paid to the edentulous patient, complex and comminuted fractures, and pediatric patients. These topics are discussed in this article, with a special emphasis on pearls of mandibular trauma management.

Pearls of Mandibular Trauma Management

PubMed Central

Koshy, John C.; Feldman, Evan M.; Chike-Obi, Chuma J.; Bullocks, Jamal M.

2010-01-01

Mandibular trauma is a common problem seen by plastic surgeons. When fractures occur, they have the ability to affect the patient's occlusion significantly, cause infection, and lead to considerable pain. Interventions to prevent these sequelae require either closed or open forms of reduction and fixation. Physicians determining how to manage these injuries should take into consideration the nature of the injury, background information regarding the patient's health, and the patient's comorbidities. Whereas general principles guide the management of the majority of injuries, special consideration must be paid to the edentulous patient, complex and comminuted fractures, and pediatric patients. These topics are discussed in this article, with a special emphasis on pearls of mandibular trauma management. PMID:22550460

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.

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.

Formation and evolution of bubbly screens in confined oscillating bubbly liquids

NASA Astrophysics Data System (ADS)

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.

Oceanic Gas Bubble Measurements Using an Acoustic Bubble Spectrometer

NASA Astrophysics Data System (ADS)

Wilson, S. J.; Baschek, B.; Deane, G.

2008-12-01

Gas bubble injection by breaking waves contributes significantly to the exchange of gases between atmosphere and ocean at high wind speeds. In this respect, CO2 is primarily important for the global ocean and climate, while O2 is especially relevant for ecosystems in the coastal ocean. For measuring oceanic gas bubble size distributions, a commercially available Dynaflow Acoustic Bubble Spectrometer (ABS) has been modified. Two hydrophones transmit and receive selected frequencies, measuring attenuation and absorption. Algorithms are then used to derive bubble size distributions. Tank test were carried out in order to test the instrument performance.The software algorithms were compared with Commander and Prosperetti's method (1989) of calculating sound speed ratio and attenuation for a known bubble distribution. Additional comparisons with micro-photography were carried out in the lab and will be continued during the SPACE '08 experiment in October 2008 at Martha's Vineyard Coastal Observatory. The measurements of gas bubbles will be compared to additional parameters, such as wind speed, wave height, white cap coverage, or dissolved gases.

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.

Accuracy of Pediatric Trauma Field Triage: A Systematic Review.

PubMed

van der Sluijs, Rogier; van Rein, Eveline A J; Wijnand, Joep G J; Leenen, Luke P H; van Heijl, Mark

2018-05-16

Field triage of pediatric patients with trauma is critical for transporting the right patient to the right hospital. Mortality and lifelong disabilities are potentially attributable to erroneously transporting a patient in need of specialized care to a lower-level trauma center. To quantify the accuracy of field triage and associated diagnostic protocols used to identify children in need of specialized trauma care. MEDLINE, Embase, PsycINFO, and Cochrane Register of Controlled Trials were searched from database inception to November 6, 2017, for studies describing the accuracy of diagnostic tests to identify children in need of specialized trauma care in a prehospital setting. Identified articles with a study population including patients not transported by emergency medical services were excluded. Quality assessment was performed using a modified version of the Quality Assessment of Diagnostic Accuracy Studies-2. After deduplication, 1430 relevant articles were assessed, a full-text review of 38 articles was conducted, and 5 of those articles were included. All studies were observational, published between 1996 and 2017, and conducted in the United States, and data collection was prospective in 1 study. Three different protocols were studied that analyzed a combined total of 1222 children in need of specialized trauma care. One protocol was specifically developed for a pediatric out-of-hospital cohort. The percentage of pediatric patients requiring specialized trauma care in each study varied between 2.6% (110 of 4197) and 54.7% (58 of 106). The sensitivity of the prehospital triage tools ranged from 49.1% to 87.3%, and the specificity ranged from 41.7% to 84.8%. No prehospital triage protocol alone complied with the international standard of 95% or greater sensitivity. Undertriage and overtriage rates, representative of the quality of the full diagnostic strategy to transport a patient to the right hospital, were not reported for inclusive trauma systems or

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.

Trauma research in Qatar: a literature review and discussion of progress after establishment of a trauma research centre.

PubMed

El-Menyar, A; Asim, M; Zarour, A; Abdelrahman, H; Peralta, R; Parchani, A; Al-Thani, H

2016-02-01

A structured research programme is one of the main pillars of a trauma care system. Despite the high rate of injury-related mortalities, especially road traffic accidents, in Qatar, little consideration has been given to research in trauma. This review aimed to analyse research publications on the subject of trauma published from Qatar and to discuss the progress of clinical research in Qatar and the Gulf Cooperation Council countries with special emphasis on trauma research. A literature search using PubMed and Google Scholar search engines located 757 English-language articles within the fields of internal medicine, surgery and trauma originating from Qatar between the years 1993 and 2013. A steep increase in the number of trauma publications since 2010 could be linked to the setting up of a trauma research centre in Qatar in 2011. We believe that establishing a research unit has made a major impact on research productivity, which ultimately benefits health care.

The Experimental Study of Dynamics of Scaled Gas-Filled Bubble Collapse in Liquid

NASA Astrophysics Data System (ADS)

Pavlenko, Alexander

2011-06-01

The article provides results of analyzing special features of the single-bubble sonoluminescence, developing the special apparatus to investigate this phenomenon on a larger-scale basis. Certain very important effects of high energy density physics, i.e. liquid compressibility, shock-wave formation under the collapse of the gas cavity in liquid, shock-wave focusing in the gas-filled cavity, occurrence of hot dense plasma in the focusing area, and high-temperature radiation yield are observed in this phenomenon. Specificity of the process is conditioned by the ``ideal'' preparation and sphericity of the gas-and-liquid contact boundary what makes the collapse process efficient due to the reduced influence of hydrodynamic instabilities. Results of experimental investigations; results of developing the facilities, description of methods used to register parameters of facilities and the system under consideration; analytical estimates how gas-filled bubbles evolve in liquid with the regard for scale effects; results of preliminary 1-D gas dynamic calculations of the gas bubble evolution are presented. The work supported by ISTC Project #2116.

Impact of shock wave pattern and cavitation bubble size on tissue damage during ureteroscopic electrohydraulic lithotripsy.

PubMed

Vorreuther, R; Corleis, R; Klotz, T; Bernards, P; Engelmann, U

1995-03-01

It is known that electrohydraulic lithotripsy (EHL) during ureteroscopy may cause ureteral damage. To evaluate this trauma potential, find its mechanism and make it possible to avoid it, our research employed photographic evaluation, tissue studies, shock wave measurements and disintegration tests. The setup included a 3.3 F probe attached to an experimental generator with adjustable voltages and capacities providing energies from 25 mJ. to 1300 mJ. per pulse. In general, we distinguish between two traumatic mechanisms: (1) After placing the probe directly on the mucosa the rapid initial plasma penetrates the tissue resulting in a small, nonthermal, punched-like defect, whose depth depends on the energy applied. This trauma has minor clinical implications and is avoided by maintaining a minimum safety distance of 1 mm.; (2) According to physics, each plasma is followed by a cavitation bubble. The maximum size of this bubble depends on the energy applied and ranges from 3 mm. (25 mJ) to > 15 mm. (1300 mJ). In proportion to the bubble size, the ureteral wall may be distended or disrupted, even when the probe is not in direct contact with the mucosa. Therefore, the goal should be to obtain a low energy pressure pulse with high disintegration efficacy. Our evaluation of the pressure waves revealed that the selection of a high voltage and a low capacity leads to short and steep "laser-like" pulses. These pulses have a significant higher impact on stone disintegration than the broader pulses of the same energy provided by currently available generators.

Idioms of distress among trauma survivors: subtypes and clinical utility.

PubMed

Hinton, Devon E; Lewis-Fernández, Roberto

2010-06-01

In this introduction to the Special Issue on Trauma and Idioms of Distress, we provide an overview of the concept and typology of "idioms of distress," focusing particularly on their clinical utility. This includes the role of idioms as indicators of trauma exposure, of various types of psychopathology and of levels of distress, risk and functioning. It likewise includes the fact that idioms of distress may profoundly influence the personal meaning of having a trauma-related disorder, may shape the interpersonal course of the disorder and may pattern help-seeking and self-treatment. Finally, it illustrates the fact that idioms may also help clinicians understand sufferers' views of the causes of their distress, constitute key therapeutic targets and help increase therapeutic empathy and treatment adherence. This special issue focuses on the role played by idioms of distress in the local trauma ontology, the associations between the idioms and psychiatric disorders occurring in the context of trauma and the mechanisms by which the idioms profoundly influence the personal and interpersonal course of trauma-related disorders.

Bubble levitation and translation under single-bubble sonoluminescence conditions.

PubMed

Matula, Thomas J

2003-08-01

Bubble levitation in an acoustic standing wave is re-examined for conditions relevant to single-bubble sonoluminescence. Unlike a previous examination [Matula et al., J. Acoust. Soc. Am. 102, 1522-1527 (1997)], the stable parameter space [Pa,R0] is accounted for in this realization. Forces such as the added mass force and drag are included, and the results are compared with a simple force balance that equates the Bjerknes force to the buoyancy force. Under normal sonoluminescence conditions, the comparison is quite favorable. A more complete accounting of the forces shows that a stably levitated bubble does undergo periodic translational motion. The asymmetries associated with translational motion are hypothesized to generate instabilities in the spherical shape of the bubble. A reduction in gravity results in reduced translational motion. It is hypothesized that such conditions may lead to increased light output from sonoluminescing bubbles.

Cavitation bubble nucleation induced by shock-bubble interaction in a gelatin gel

NASA Astrophysics Data System (ADS)

Oguri, Ryota; Ando, Keita

2018-05-01

An optical visualization technique is developed to study cavitation bubble nucleation that results from interaction between a laser-induced shock and a preexisting gas bubble in a 10 wt. % gelatin gel; images of the nucleated cavitation bubbles are captured and the cavitation inception pressure is determined based on Euler flow simulation. A spherical gas cavity is generated by focusing an infrared laser pulse into a gas-supersaturated gel and the size of the laser-generated bubble in mechanical equilibrium is tuned via mass transfer of the dissolved gas into the bubble. A spherical shock is then generated, through rapid expansion of plasma induced by the laser focusing, in the vicinity of the gas bubble. The shock-bubble interaction is recorded by a CCD camera with flash illumination of a nanosecond green laser pulse. The observation captures cavitation inception in the gel under tension that results from acoustic impedance mismatching at the bubble interface interacting with the shock. We measure the probability of cavitation inception from a series of the repeated experiments, by varying the bubble radius and the standoff distance. The threshold pressure is defined at the cavitation inception probability equal to one half and is calculated, through comparisons to Euler flow simulation, at -24.4 MPa. This threshold value is similar to that from shock-bubble interaction experiments using water, meaning that viscoelasticity of the 10 wt. % gelatin gel has a limited impact on bubble nucleation dynamics.

Suppression of shocked-bubble expansion due to tissue confinement with application to shock-wave lithotripsy

PubMed Central

Freund, Jonathan B.

2008-01-01

Estimates are made of the effect of tissue confinement on the response of small bubbles subjected to lithotriptor shock pressures. To do this the Rayleigh–Plesset equation, which governs the dynamics of spherical bubbles, is generalized to treat a bubble in a liquid region (blood), which is in turn encased within an elastic membrane (like a vessel’s basement membrane), beyond which a Voigt viscoelastic material models the exterior tissue. Material properties are estimated from a range of measurements available for kidneys and similar soft tissues. Special attention is given to the constitutive modeling of the basement membranes because of their expected importance due to their proximity to the bubble and their toughness. It is found that the highest expected values for the elasticity of the membrane and surrounding tissue are insufficient to suppress bubble growth. The reduced confinement of a cylindrical vessel should not alter this conclusion. Tissue viscosities taken from ultrasound measurements suppress bubble growth somewhat, though not to a degree expected to resist injury. However, the higher reported viscosities measured by other means, which are arguably more relevant to the deformations caused by growing bubbles, do indeed significantly suppress bubble expansion. PMID:18529202

Suppression of shocked-bubble expansion due to tissue confinement with application to shock-wave lithotripsy.

PubMed

Freund, Jonathan B

2008-05-01

Estimates are made of the effect of tissue confinement on the response of small bubbles subjected to lithotriptor shock pressures. To do this the Rayleigh-Plesset equation, which governs the dynamics of spherical bubbles, is generalized to treat a bubble in a liquid region (blood), which is in turn encased within an elastic membrane (like a vessel's basement membrane), beyond which a Voigt viscoelastic material models the exterior tissue. Material properties are estimated from a range of measurements available for kidneys and similar soft tissues. Special attention is given to the constitutive modeling of the basement membranes because of their expected importance due to their proximity to the bubble and their toughness. It is found that the highest expected values for the elasticity of the membrane and surrounding tissue are insufficient to suppress bubble growth. The reduced confinement of a cylindrical vessel should not alter this conclusion. Tissue viscosities taken from ultrasound measurements suppress bubble growth somewhat, though not to a degree expected to resist injury. However, the higher reported viscosities measured by other means, which are arguably more relevant to the deformations caused by growing bubbles, do indeed significantly suppress bubble expansion.

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.

Bubbling at high flow rates in inviscid and viscous liquids (slags)

NASA Astrophysics Data System (ADS)

Engh, T. Abel; Nilmani, M.

1988-02-01

The behavior of gas discharging into melts at high velocities but still in the bubbling regime has been investigated in a laboratory modeling study for constant flow conditions. Air or helium was injected through a vertical tuyere into water, zinc-chloride, and aqueous glycerol solutions. High speed cinematography and pressure measurements in the tuyere have been carried out simultaneously. Pressure fluctuations at the injection point were monitored and correlated to the mode of bubble formation. The effects of high gas flow rates and high liquid viscosities have been examined in particular. Flow rates were employed up to 10-3 m3/s and viscosity to 0.5 Ns/m2. In order to attain a high gas momentum, the tuyere diameter was only 3 x 10-3 m. The experimental conditions and modeling liquids were chosen with special reference to the established practice of submerged gas injection to treat nonferrous slags. Such slags can be highly viscous. Bubble volume is smaller than that calculated from existing models such as those given by Davidson and Schüler10,11 due to the effect of gas momentum elongating the bubbles. On the other hand, viscosity tends to retard the bubble rise velocity, thus increasing volumes. To take elongation into account, a mathematical model is presented that assumes a prolate ellipsoidal shape of the bubbles. The unsteady potential flow equations for the liquid are solved for this case. Viscous effects are taken into account by noting that flow deviates from irrotational motion only in a thin boundary layer along the surface of the bubble. Thus, drag on the bubble can be obtained by calculating the viscous energy dissipation for potential flow past an ellipse. The time-dependent inertia coefficient for the ellipsoid is found by equating the vertical pressure increase inside and outside the bubble. This pressure change in the bubble is obtained by assuming that gas enters as a homogeneous jet and then calculating the stagnation pressure at the apex of

Interfacial Bubble Deformations

NASA Astrophysics Data System (ADS)

Seymour, Brian; Shabane, Parvis; Cypull, Olivia; Cheng, Shengfeng; Feitosa, Klebert

Soap bubbles floating at an air-water experience deformations as a result of surface tension and hydrostatic forces. In this experiment, we investigate the nature of such deformations by taking cross-sectional images of bubbles of different volumes. The results show that as their volume increases, bubbles transition from spherical to hemispherical shape. The deformation of the interface also changes with bubble volume with the capillary rise converging to the capillary length as volume increases. The profile of the top and bottom of the bubble and the capillary rise are completely determined by the volume and pressure differences. James Madison University Department of Physics and Astronomy, 4VA Consortium, Research Corporation for Advancement of Science.

Bubble Dynamics and Resulting Noise from Traveling Bubble Cavitation.

DTIC Science & Technology

1982-04-13

proportional to the gas content. The subjectivity of visual cavitation determination is evidenced by the maximum standard deviation. As mentioned before...bubble radii at the maximum radius position on the model. The point on the model where the bubble will be at its maximum volume was determined by...48 3.7 Recording Bubble Dynamics . • . * . . . . 52 3.8 Measurement of Gas Nuclei in Water 0 • 52 3 TABLE OF CONTENTS (continued) Paqe

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.

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.

FERMI BUBBLES AND BUBBLE-LIKE EMISSION FROM THE GALACTIC PLANE

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

De Boer, Wim; Weber, Markus, E-mail: wim.de.boer@kit.edu, E-mail: markus.weber2@kit.edu

2014-10-10

The diffuse gamma-ray sky revealed ''bubbles'' of emission above and below the Galactic plane, symmetric around the center of the Milky Way, with a height of 10 kpc in both directions. At present, there is no convincing explanation for the origin. To understand the role of the Galactic center, one has to study the bubble spectrum inside the disk, a region that has been excluded from previous analyses because of the large foreground. From a novel template fit, which allows a simultaneous determination of the signal and foreground in any direction, we find that bubble-like emission is not only found inmore » the halo, but in the Galactic plane as well, with a width in latitude coinciding with the molecular clouds. The longitude distribution has a width corresponding to the Galactic bar with an additional contribution from the Scutum-Centaurus arm. The energy spectrum of the bubbles coincides with the predicted contribution from CRs trapped in sources (SCRs). Also, the energetics fits well. Hence, we conclude that the bubble-like emission has a hadronic origin that arises from SCRs, and the bubbles in the halo arise from hadronic interactions in advected gas. Evidence for advection is provided by the ROSAT X-rays of hot gas in the bubble region.« less

Electrowetting of soap bubbles

NASA Astrophysics Data System (ADS)

Arscott, Steve

2013-07-01

A proof-of-concept demonstration of the electrowetting-on-dielectric of a sessile soap bubble is reported here. The bubbles are generated using a commercial soap bubble mixture—the surfaces are composed of highly doped, commercial silicon wafers covered with nanometer thick films of Teflon®. Voltages less than 40 V are sufficient to observe the modification of the bubble shape and the apparent bubble contact angle. Such observations open the way to inter alia the possibility of bubble-transport, as opposed to droplet-transport, in fluidic microsystems (e.g., laboratory-on-a-chip)—the potential gains in terms of volume, speed, and surface/volume ratio are non-negligible.

Modeling of single film bubble and numerical study of the plateau structure in foam system

NASA Astrophysics Data System (ADS)

Sun, Zhong-guo; Ni, Ni; Sun, Yi-jie; Xi, Guang

2018-02-01

The single-film bubble has a special geometry with a certain amount of gas shrouded by a thin layer of liquid film under the surface tension force both on the inside and outside surfaces of the bubble. Based on the mesh-less moving particle semi-implicit (MPS) method, a single-film double-gas-liquid-interface surface tension (SDST) model is established for the single-film bubble, which characteristically has totally two gas-liquid interfaces on both sides of the film. Within this framework, the conventional surface free energy surface tension model is improved by using a higher order potential energy equation between particles, and the modification results in higher accuracy and better symmetry properties. The complex interface movement in the oscillation process of the single-film bubble is numerically captured, as well as typical flow phenomena and deformation characteristics of the liquid film. In addition, the basic behaviors of the coalescence and connection process between two and even three single-film bubbles are studied, and the cases with bubbles of different sizes are also included. Furthermore, the classic plateau structure in the foam system is reproduced and numerically proved to be in the steady state for multi-bubble connections.

Update on prehospital emergency care of severe trauma patients.

PubMed

Tazarourte, K; Cesaréo, E; Sapir, D; Atchabahian, A; Tourtier, J-P; Briole, N; Vigué, B

2013-01-01

The prognosis of severe trauma patients is determined by the ability of a healthcare system to provide high intensity therapeutic treatment on the field and to transport patients as quickly as possible to the structure best suited to their condition. Direct admission to a specialized center ("trauma center") reduces the mortality of the most severe trauma at 30 days and one year. Triage in a non-specialized hospital is a major risk of loss of chance and should be avoided whenever possible. Medical dispatching plays a major role in determining patient care. The establishment of a hospital care network is an important issue that is not formalized enough in France. The initial triage of severe trauma patients must be improved to avoid taking patients to hospitals that are not equipped to take care of them. For this purpose, the MGAP score can predict severity and help decide where to transport the patient. However, it does not help predict the need for urgent resuscitation procedures. Hemodynamic management is central to the care of hemorrhagic shock and severe head trauma. Transport helicopter with a physician on board has an important role to allow direct admission to a specialized center in geographical areas that are difficult to access. Copyright © 2013 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

Bridging Body and Mind: Considerations for Trauma-Informed Yoga.

PubMed

Justice, Lauren; Brems, Christiane; Ehlers, Karrie

2018-02-08

Individuals who suffer from trauma-related symptoms are a unique population that could benefit from the mind-body practice of yoga-or have their symptoms reactivated by it, depending on the type of yoga. Trauma-informed yoga (TIY), that is, yoga adapted to the unique needs of individuals working to overcome trauma, may ameliorate symptoms by creating a safe, tailored practice for students to learn how to respond, rather than react, to symptoms and circumstances. Yoga not thus adapted, on the other hand, may increase reactivity and activate symptoms such as hyperarousal or dissociation. This article reports on expert input about adapting yoga for individuals with trauma, with special considerations for military populations. Eleven experts, recruited based on literature review and referrals, were interviewed in person or via telephone and asked seven questions about trauma-informed yoga. Verbatim transcripts were subjected to open-coding thematic analysis and a priori themes. Findings revealed that TIY needs to emphasize beneficial practices (e.g., diaphragmatic breath and restorative postures), consider contraindications (e.g., avoiding sequences that overly engage the sympathetic nervous system), adapt to limitations and challenges for teaching in unconventional settings (e.g., prisons, VA hospitals), and provide specialized training and preparation (e.g., specialized TIY certifications, self-care of instructors/therapists, adaptions for student needs). TIY for veterans must additionally consider gender- and culture-related barriers, differing relationships to pain and injury, and medication as a barrier to practice.

Droplet bubbling evaporatively cools a blowfly.

PubMed

Gomes, Guilherme; Köberle, Roland; Von Zuben, Claudio J; Andrade, Denis V

2018-04-19

Terrestrial animals often use evaporative cooling to lower body temperature. Evaporation can occur from humid body surfaces or from fluids interfaced to the environment through a number of different mechanisms, such as sweating or panting. In Diptera, some flies move tidally a droplet of fluid out and then back in the buccopharyngeal cavity for a repeated number of cycles before eventually ingesting it. This is referred to as the bubbling behaviour. The droplet fluid consists of a mix of liquids from the ingested food, enzymes from the salivary glands, and antimicrobials, associated to the crop organ system, with evidence pointing to a role in liquid meal dehydration. Herein, we demonstrate that the bubbling behaviour also serves as an effective thermoregulatory mechanism to lower body temperature by means of evaporative cooling. In the blowfly, Chrysomya megacephala, infrared imaging revealed that as the droplet is extruded, evaporation lowers the fluid´s temperature, which, upon its re-ingestion, lowers the blowfly's body temperature. This effect is most prominent at the cephalic region, less in the thorax, and then in the abdomen. Bubbling frequency increases with ambient temperature, while its cooling efficiency decreases at high air humidities. Heat transfer calculations show that droplet cooling depends on a special heat-exchange dynamic, which result in the exponential activation of the cooling effect.

Rising dynamics of a bubble confined in vertical cells with rectangular cross-sections

NASA Astrophysics Data System (ADS)

Murano, Mayuko; Okumura, Ko

2017-11-01

Recently, the drag friction acting on a fluid drop in confined space has been actively studied. Here, we investigate the rising velocity of a bubble in a vertical cell with a rectangular cross-section, both theoretically and experimentally, in which understanding of the drag force acting on the rising bubble is crucial. Although the drag force in such confined space could involve several regimes, we study a special case in which the bubble is long and the aspect-ratio of the rectangular cross-section of the cell is high. As a result, we found new scaling law for the rising velocity and the drag force, and confirmed the laws experimentally. Crossover to the rising dynamics in a Hele-Shaw cell will be also discussed.

Nonlinear Bubble Dynamics And The Effects On Propagation Through Near-Surface Bubble Layers

NASA Astrophysics Data System (ADS)

Leighton, Timothy G.

2004-11-01

Nonlinear bubble dynamics are often viewed as the unfortunate consequence of having to use high acoustic pressure amplitudes when the void fraction in the near-surface oceanic bubble layer is great enough to cause severe attenuation (e.g. >50 dB/m). This is seen as unfortunate since existing models for acoustic propagation in bubbly liquids are based on linear bubble dynamics. However, the development of nonlinear models does more than just allow quantification of the errors associated with the use of linear models. It also offers the possibility of propagation modeling and acoustic inversions which appropriately incorporate the bubble nonlinearity. Furthermore, it allows exploration and quantification of possible nonlinear effects which may be exploited. As a result, high acoustic pressure amplitudes may be desirable even in low void fractions, because they offer opportunities to gain information about the bubble cloud from the nonlinearities, and options to exploit the nonlinearities to enhance communication and sonar in bubbly waters. This paper presents a method for calculating the nonlinear acoustic cross-sections, scatter, attenuations and sound speeds from bubble clouds which may be inhomogeneous. The method allows prediction of the time dependency of these quantities, both because the cloud may vary and because the incident acoustic pulse may have finite and arbitrary time history. The method can be readily adapted for bubbles in other environments (e.g. clouds of interacting bubbles, sediments, structures, in vivo, reverberant conditions etc.). The possible exploitation of bubble acoustics by marine mammals, and for sonar enhancement, is explored.

Letter: Entrapment and interaction of an air bubble with an oscillating cavitation bubble

NASA Astrophysics Data System (ADS)

Kannan, Y. S.; Karri, Badarinath; Sahu, Kirti Chandra

2018-04-01

The mechanism of the formation of an air bubble due to an oscillating cavitation bubble in its vicinity is reported from an experimental study using high-speed imaging. The cavitation bubble is created close to the free surface of water using a low-voltage spark circuit comprising two copper electrodes in contact with each other. Before the bubble is created, a third copper wire is positioned in contact with the free surface of water close to the two crossing electrodes. Due to the surface tension at the triple point (wire-water-air) interface, a small dip is observed in the free surface at the point where the wire is immersed. When the cavitation bubble is created, the bubble pushes at the dip while expanding and pulls at it while collapsing. The collapse phase leads to the entrapment of an air bubble at the wire immersion point. During this phase, the air bubble undergoes a "catapult" effect, i.e., it expands to a maximum size and then collapses with a microjet at the free surface. To the best of our knowledge, this mechanism has not been reported so far. A parametric study is also conducted to understand the effects of wire orientation and bubble distance from the free surface.

The big hurt: Trauma system funding in today's health care environment.

PubMed

Geehan, Douglas

2010-01-01

Trauma systems provide effective care of the injured patient but require major financial costs in readiness and availability of the extensive trauma team and specialized equipment. Traditional billing and collection practices do not fully recoup these costs. Effective use of the standard billing system is vital to the stability of a trauma system; however, a system wide funding mechanism provides an optimal, stable foundation. Efforts to provide sustainable trauma system funding are ongoing. Numerous state initiatives have been successful in funding trauma systems but a universal solution has yet to be found.

Nursing role innovations: improved outcomes in a trauma center.

PubMed

Holmquist, P J; Yamamoto, L; DiDonna, D; Sise, M J

1996-01-01

Trauma systems operate on the principle that people with severe injuries require special medical capabilities if they are to have their best chance of recovery. However, optimal trauma care is threatened by the problems of inadequate financial reimbursement. This threatens the ability to deliver trauma patient care. A variety of strategies is necessary to continue to provide care. Two specific nursing role innovations provide the opportunity to improve the ability to provide coordinated, efficient, and cost-effective quality care.

Bubble bath soap poisoning

MedlinePlus

... medlineplus.gov/ency/article/002762.htm Bubble bath soap poisoning To use the sharing features on this page, please enable JavaScript. Bubble bath soap poisoning occurs when someone swallows bubble bath soap. ...

[Endovascular interventions for multiple trauma].

PubMed

Kinstner, C; Funovics, M

2014-09-01

In recent years interventional radiology has significantly changed the management of injured patients with multiple trauma. Currently nearly all vessels can be reached within a reasonably short time with the help of specially preshaped catheters and guide wires to achieve bleeding control of arterial und venous bleeding. Whereas bleeding control formerly required extensive open surgery, current interventional methods allow temporary vessel occlusion (occlusion balloons), permanent embolization and stenting. In injured patients with multiple trauma preinterventional procedural planning is performed with the help of multidetector computed tomography whenever possible. Interventional radiology not only allows minimization of therapeutic trauma but also a considerably shorter treatment time. Interventional bleeding control has developed into a standard method in the management of vascular trauma of the chest and abdomen as well as in vascular injuries of the upper and lower extremities when open surgical access is associated with increased risk. Additionally, pelvic trauma, vascular trauma of the superior thoracic aperture and parenchymal arterial lacerations of organs that can be at least partially preserved are primarily managed by interventional methods. In an interdisciplinary setting interventional radiology provides a safe and efficient means of rapid bleeding control in nearly all vascular territories in addition to open surgical access.

Simulation of gas bubbles in hypobaric decompressions: roles of O2, CO2, and H2O.

PubMed

Van Liew, H D; Burkard, M E

1995-01-01

To gain insight into the special features of bubbles that may form in aviators and astronauts, we simulated the growth and decay of bubbles in two hypobaric decompressions and a hyperbaric one, all with the same tissue ratio (TR), where TR is defined as tissue PN2 before decompression divided by barometric pressure after. We used an equation system which is solved by numerical methods and accounts for simultaneous diffusion of any number of gases as well as other major determinants of bubble growth and absorption. We also considered two extremes of the number of bubbles which form per unit of tissue. A) Because physiological mechanisms keep the partial pressures of the "metabolic" gases (O2, CO2, and H2O) nearly constant over a range of hypobaric pressures, their fractions in bubbles are inversely proportional to pressure and their large volumes at low pressure add to bubble size. B) In addition, the large fractions facilitate the entry of N2 into bubbles, and when bubble density is low, enhance an autocatalytic feedback on bubble growth due to increasing surface area. C) The TR is not closely related to bubble size; that is when two different decompressions have the same TR, metabolic gases cause bubbles to grow larger at lower hypobaric pressures. We conclude that the constancy of partial pressures of metabolic gases, unimportant in hyperbaric decompressions, affects bubble size in hypobaric decompressions in inverse relation to the exposure pressure.

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.

A derivation of the stable cavitation threshold accounting for bubble-bubble interactions.

PubMed

Guédra, Matthieu; Cornu, Corentin; Inserra, Claude

2017-09-01

The subharmonic emission of sound coming from the nonlinear response of a bubble population is the most used indicator for stable cavitation. When driven at twice their resonance frequency, bubbles can exhibit subharmonic spherical oscillations if the acoustic pressure amplitude exceeds a threshold value. Although various theoretical derivations exist for the subharmonic emission by free or coated bubbles, they all rest on the single bubble model. In this paper, we propose an analytical expression of the subharmonic threshold for interacting bubbles in a homogeneous, monodisperse cloud. This theory predicts a shift of the subharmonic resonance frequency and a decrease of the corresponding pressure threshold due to the interactions. For a given sonication frequency, these results show that an optimal value of the interaction strength (i.e. the number density of bubbles) can be found for which the subharmonic threshold is minimum, which is consistent with recently published experiments conducted on ultrasound contrast agents. Copyright © 2017 Elsevier B.V. All rights reserved.

Imaging of Combat-Related Thoracic Trauma - Review of Penetrating Trauma.

PubMed

Lichtenberger, John P; Kim, Andrew M; Fisher, Dane; Tatum, Peter S; Neubauer, Brian; Peterson, P Gabriel; Carter, Brett W

2018-03-01

Combat-related thoracic trauma is a significant contributor to morbidity and mortality of the casualties from Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF). Penetrating, blunt, and blast injuries were the most common mechanisms of trauma. Imaging plays a key role in the management of combat-related thoracic trauma casualties. This review discusses the imaging manifestations of thoracic injuries from penetrating trauma, emphasizing epidemiology and diagnostic clues seen during OEF and OIF. The assessment of radiologic findings in patients who suffer from combat-related thoracic trauma is the basis of this review article. The imaging modalities for this study include multi-detector computed tomography and chest radiography. High-velocity penetrating projectile injuries appear as hemorrhage and re-expansion pulmonary edema from the temporary cavity and a linear, blood-filled track from the permanent cavity. In cases where the projectile passes totally through the body, entrance wounds at the skin surface and tracks through the subcutaneous tissues may be the only indications of penetrating trauma. When assessing vascular injury, special attention should be paid to the right hilum in contrast-enhanced multi-detector computed tomography, as contrast is concentrated in the superior vena cava and superior cavoatrial junction may obscure small fragments. Additionally, CT angiography may show vessel disruption or extravasation of contrast distal to normal vessel location in addition to intraluminal filling defects and pseudo-aneurysms. Tension pneumopericardium may rarely complicate penetrating or blunt chest trauma. On imaging, distension of the pericardial sack by pneumopericardium and compression of the heart support the diagnosis of tension. On multi-detector computed tomography in the acute trauma setting, fluid in the pleural space should be considered hemothorax, particularly when Hounsfield units are above 35. Acutely, extravasated blood will

Single Bubble Sonoluminescence in Low Gravity and Optical Radiation Pressure Positioning of the Bubble

NASA Technical Reports Server (NTRS)

Thiessen, D. B.; Young, J. E.; Marr-Lyon, M. J.; Richardson, S. L.; Breckon, C. D.; Douthit, S. G.; Jian, P. S.; Torruellas, W. E.; Marston, P. L.

1999-01-01

Several groups of researchers have demonstrated that high frequency sound in water may be used to cause the regular repeated compression and luminescence of a small bubble of gas in a flask. The phenomenon is known as single bubble sonoluminescence (SBSL). It is potentially important because light emitted by the bubble appears to be associated with a significant concentration of energy within the volume of the bubble. Unfortunately, the detailed physical mechanisms causing the radiation of light by oscillating bubbles are poorly understood and there is some evidence that carrying out experiments in a weightless environment may provide helpful clues. In addition, the radiation pressure of laser beams on the bubble may provide a way of simulating weightless experiments in the laboratory. The standard model of SBSL attributes the light emission to heating within the bubble by a spherically imploding shock wave to achieve temperatures of 50,000 K or greater. In an alternative model, the emission is attributed to the impact of a jet of water which is required to span the bubble and the formation of the jet is linked to the buoyancy of the bubble. The coupling between buoyancy and jet formation is a consequence of the displacement of the bubble from a velocity node (pressure antinode) of the standing acoustic wave that drives the radial bubble oscillations. One objective of this grant is to understand SBSL emission in reduced buoyancy on KC-135 parabolic flights. To optimize the design of those experiments and for other reasons which will help resolve the role of buoyancy, laboratory experiments are planned in simulated low gravity in which the radiation pressure of laser light will be used to position the bubble at the acoustic velocity node of the ultrasonic standing wave. Laser light will also be used to push the bubble away from the velocity node, increasing the effective buoyancy. The original experiments on the optical levitation and radiation pressure on bubbles

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

The speed of sound in a gas–vapour bubbly liquid

PubMed Central

Prosperetti, Andrea

2015-01-01

In addition to the vapour of the liquid, bubbles in cavitating flows usually contain also a certain amount of permanent gas that diffuses out of the liquid as they grow. This paper presents a simplified linear model for the propagation of monochromatic pressure waves in a bubbly liquid with these characteristics. Phase change effects are included in detail, while the gas is assumed to follow a polytropic law. It is shown that even a small amount of permanent gas can have a major effect on the behaviour of the system. Particular attention is paid to the low-frequency range, which is of special concern in flow cavitation. Numerical results for water and liquid oxygen illustrate the implications of the model. PMID:26442146

The speed of sound in a gas-vapour bubbly liquid.

PubMed

Prosperetti, Andrea

2015-10-06

In addition to the vapour of the liquid, bubbles in cavitating flows usually contain also a certain amount of permanent gas that diffuses out of the liquid as they grow. This paper presents a simplified linear model for the propagation of monochromatic pressure waves in a bubbly liquid with these characteristics. Phase change effects are included in detail, while the gas is assumed to follow a polytropic law. It is shown that even a small amount of permanent gas can have a major effect on the behaviour of the system. Particular attention is paid to the low-frequency range, which is of special concern in flow cavitation. Numerical results for water and liquid oxygen illustrate the implications of the model.

Bubbles

NASA Astrophysics Data System (ADS)

Prosperetti, Andrea

2002-11-01

``Vanitas vanitatum et omnia vanitas": bubbles are emptiness, non-liquid, a tiny cloud shielding a mathematical singularity. Born from chance, a violent and brief life ending in the union with the (nearly) infinite. But a wealth of phenomena spring forth from this nothingness: underwater noise, sonoluminescence, boiling, many others. Ultimately, diffusive processes govern much of the physics, and the difference between the diffusivity of heat and dissolved gases in ordinary liquids holds the key to the striking differences between gas and vapor bubbles.

Fermi Bubble: Giant Gamma-Ray Bubbles in the Milky Way

NASA Astrophysics Data System (ADS)

Su, Meng

Data from the Fermi-LAT reveal two gigantic gamma-ray emitting bubble structures (known as the Fermibubbles), extending˜50° above and below the Galactic center symmetric about the Galactic plane, with a width of˜40∘ in longitude. The gamma-ray emission associated with these bubbles has a significantly harder spectrum ({dN}/{dE} ˜ {E}^{-2}) than the inverse Compton emission from known cosmic ray electrons in the Galactic disk, or the gamma-rays produced by decay of pions from proton-ISM collisions. The bubbles are spatially correlated with the hard-spectrum microwave excess known as the WMAPhaze; the edges of the bubbles also line up with features in the ROSATsoft X-ray maps at 1.5-2keV. The Fermibubble is most likely created by some large episode of energy injection in the Galactic center, such as past accretion events onto the central massive black hole, or a nuclear starburst in the last˜10Myr. Study of the origin and evolution of the bubbles also has the potential to improve our understanding of recent energetic events in the inner Galaxy and the high-latitude cosmic ray population.

Bubble measuring instrument and method

NASA Technical Reports Server (NTRS)

Magari, Patrick J. (Inventor); Kline-Schoder, Robert (Inventor)

2003-01-01

Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer, respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.

Bubble Measuring Instrument and Method

NASA Technical Reports Server (NTRS)

Kline-Schoder, Robert (Inventor); Magari, Patrick J. (Inventor)

2002-01-01

Method and apparatus are provided for a non-invasive bubble measuring instrument operable for detecting, distinguishing, and counting gaseous embolisms such as bubbles over a selectable range of bubble sizes of interest. A selected measurement volume in which bubbles may be detected is insonified by two distinct frequencies from a pump transducer and an image transducer. respectively. The image transducer frequency is much higher than the pump transducer frequency. The relatively low-frequency pump signal is used to excite bubbles to resonate at a frequency related to their diameter. The image transducer is operated in a pulse-echo mode at a controllable repetition rate that transmits bursts of high-frequency ultrasonic signal to the measurement volume in which bubbles may be detected and then receives the echo. From the echo or received signal, a beat signal related to the repetition rate may be extracted and used to indicate the presence or absence of a resonant bubble. In a preferred embodiment, software control maintains the beat signal at a preselected frequency while varying the pump transducer frequency to excite bubbles of different diameters to resonate depending on the range of bubble diameters selected for investigation.

BLOWING COSMIC BUBBLES

NASA Technical Reports Server (NTRS)

2002-01-01

This NASA Hubble Space Telescope image reveals an expanding shell of glowing gas surrounding a hot, massive star in our Milky Way Galaxy. This shell is being shaped by strong stellar winds of material and radiation produced by the bright star at the left, which is 10 to 20 times more massive than our Sun. These fierce winds are sculpting the surrounding material - composed of gas and dust - into the curve-shaped bubble. Astronomers have dubbed it the Bubble Nebula (NGC 7635). The nebula is 10 light-years across, more than twice the distance from Earth to the nearest star. Only part of the bubble is visible in this image. The glowing gas in the lower right-hand corner is a dense region of material that is getting blasted by radiation from the Bubble Nebula's massive star. The radiation is eating into the gas, creating finger-like features. This interaction also heats up the gas, causing it to glow. Scientists study the Bubble Nebula to understand how hot stars interact with the surrounding material. Credit: Hubble Heritage Team (AURA/STScI/NASA)

A Bubble Bursts

NASA Technical Reports Server (NTRS)

2005-01-01

RCW 79 is seen in the southern Milky Way, 17,200 light-years from Earth in the constellation Centaurus. The bubble is 70-light years in diameter, and probably took about one million years to form from the radiation and winds of hot young stars.

The balloon of gas and dust is an example of stimulated star formation. Such stars are born when the hot bubble expands into the interstellar gas and dust around it. RCW 79 has spawned at least two groups of new stars along the edge of the large bubble. Some are visible inside the small bubble in the lower left corner. Another group of baby stars appears near the opening at the top.

NASA's Spitzer Space Telescope easily detects infrared light from the dust particles in RCW 79. The young stars within RCW 79 radiate ultraviolet light that excites molecules of dust within the bubble. This causes the dust grains to emit infrared light that is detected by Spitzer and seen here as the extended red features.

Bubble nucleation and inflationary perturbations

NASA Astrophysics Data System (ADS)

Firouzjahi, Hassan; Jazayeri, Sadra; Karami, Asieh; Rostami, Tahereh

2017-12-01

In this work we study the imprints of bubble nucleation on primordial inflationary perturbations. We assume that the bubble is formed via the tunneling of a spectator field from the false vacuum of its potential to its true vacuum. We consider the configuration in which the observable CMB sphere is initially outside of the bubble. As the bubble expands, more and more regions of the exterior false vacuum, including our CMB sphere, fall into the interior of the bubble. The modes which leave the horizon during inflation at the time when the bubble wall collides with the observable CMB sphere are affected the most. The bubble wall induces non-trivial anisotropic and scale dependent corrections in the two point function of the curvature perturbation. The corrections in the curvature perturbation and the diagonal and off-diagonal elements of CMB power spectrum are estimated.

INTERACTIONS OF THE INFRARED BUBBLE N4 WITH ITS SURROUNDINGS

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

Liu, Hong-Li; Li, Jin-Zeng; Yuan, Jing-Hua

The physical mechanisms that induce the transformation of a certain mass of gas in new stars are far from being well understood. Infrared bubbles associated with H ii regions have been considered to be good samples for investigating triggered star formation. In this paper we report on the investigation of the dust properties of the infrared bubble N4 around the H ii region G11.898+0.747, analyzing its interaction with its surroundings and star formation histories therein, with the aim of determining the possibility of star formation triggered by the expansion of the bubble. Using Herschel PACS and SPIRE images with a widemore » wavelength coverage, we reveal the dust properties over the entire bubble. Meanwhile, we are able to identify six dust clumps surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K, mean column density of 1.7 × 10{sup 22} cm{sup −2}, mean volume density of about 4.4 × 10{sup 4} cm{sup −3}, and a mean mass of 320 M{sub ⊙}. In addition, from PAH emission seen at 8 μm, free–free emission detected at 20 cm, and a probability density function in special regions, we could identify clear signatures of the influence of the H ii region on the surroundings. There are hints of star formation, though further investigation is required to demonstrate that N4 is the triggering source.« less

Bubble Transport through Micropillar Arrays

NASA Astrophysics Data System (ADS)

Lee, Kenneth; Savas, Omer

2012-11-01

In current energy research, artificial photosynthetic devices are being designed to split water and harvest hydrogen gas using energy from the sun. In one such design, hydrogen gas bubbles evolve on the catalytic surfaces of arrayed micropillars. If these bubbles are not promptly removed from the surface, they can adversely affect gas evolution rates, water flow rates, sunlight capture, and heat management of the system. Therefore, an efficient method of collecting the evolved gas bubbles is crucial. Preliminary flow visualization has been conducted of bubbles advecting through dense arrays of pillars. Bubbles moving through square and hexagonal arrays are tracked, and the results are qualitatively described. Initial attempts to correlate bubble motion with relevant lengthscales and forces are also presented. These observations suggest how bubble transport within such pillar arrays can be managed, as well as guide subsequent experiments that investigate bubble evolution and collection. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award Number DE-SC0004993.

Gas bubble detector

NASA Technical Reports Server (NTRS)

Mount, Bruce E. (Inventor); Burchfield, David E. (Inventor); Hagey, John M. (Inventor)

1995-01-01

A gas bubble detector having a modulated IR source focused through a bandpass filter onto a venturi, formed in a sample tube, to illuminate the venturi with modulated filtered IR to detect the presence of gas bubbles as small as 0.01 cm or about 0.004 in diameter in liquid flowing through the venturi. Means are provided to determine the size of any detected bubble and to provide an alarm in the absence of liquid in the sample tube.

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.

Doughnut-shaped soap bubbles.

PubMed

Préve, Deison; Saa, Alberto

2015-10-01

Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L. It is well known that the sphere is the solution for V=L(3)/6π(2), and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for V<αL(3)/6π(2), with α≈0.21, such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but is rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V<αL(3)/6π(2) cannot be stable and should not exist in foams, for instance.

Doughnut-shaped soap bubbles

NASA Astrophysics Data System (ADS)

Préve, Deison; Saa, Alberto

2015-10-01

Soap bubbles are thin liquid films enclosing a fixed volume of air. Since the surface tension is typically assumed to be the only factor responsible for conforming the soap bubble shape, the realized bubble surfaces are always minimal area ones. Here, we consider the problem of finding the axisymmetric minimal area surface enclosing a fixed volume V and with a fixed equatorial perimeter L . It is well known that the sphere is the solution for V =L3/6 π2 , and this is indeed the case of a free soap bubble, for instance. Surprisingly, we show that for V <α L3/6 π2 , with α ≈0.21 , such a surface cannot be the usual lens-shaped surface formed by the juxtaposition of two spherical caps, but is rather a toroidal surface. Practically, a doughnut-shaped bubble is known to be ultimately unstable and, hence, it will eventually lose its axisymmetry by breaking apart in smaller bubbles. Indisputably, however, the topological transition from spherical to toroidal surfaces is mandatory here for obtaining the global solution for this axisymmetric isoperimetric problem. Our result suggests that deformed bubbles with V <α L3/6 π2 cannot be stable and should not exist in foams, for instance.

Bubble generation during transformer overload

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

Oommen, T.V.

1990-03-01

Bubble generation in transformers has been demonstrated under certain overload conditions. The release of large quantities of bubbles would pose a dielectric breakdown hazard. A bubble prediction model developed under EPRI Project 1289-4 attempts to predict the bubble evolution temperature under different overload conditions. This report details a verification study undertaken to confirm the validity of the above model using coil structures subjected to overload conditions. The test variables included moisture in paper insulation, gas content in oil, and the type of oil preservation system. Two aged coils were also tested. The results indicated that the observed bubble temperatures weremore » close to the predicted temperatures for models with low initial gas content in the oil. The predicted temperatures were significantly lower than the observed temperatures for models with high gas content. Some explanations are provided for the anomalous behavior at high gas levels in oil. It is suggested that the dissolved gas content is not a significant factor in bubble evolution. The dominant factor in bubble evolution appears to be the water vapor pressure which must reach critical levels before bubbles can be released. Further study is needed to make a meaningful revision of the bubble prediction model. 8 refs., 13 figs., 11 tabs.« less

Bubble transport in bifurcations

NASA Astrophysics Data System (ADS)

Bull, Joseph; Qamar, Adnan

2017-11-01

Motivated by a developmental gas embolotherapy technique for cancer treatment, we examine the transport of bubbles entrained in liquid. In gas embolotherapy, infarction of tumors is induced by selectively formed vascular gas bubbles that originate from acoustic vaporization of vascular droplets. In the case of non-functionalized droplets with the objective of vessel occlusion, the bubbles are transported by flow through vessel bifurcations, where they may split prior to eventually reach vessels small enough that they become lodged. This splitting behavior affects the distribution of bubbles and the efficacy of flow occlusion and the treatment. In these studies, we investigated bubble transport in bifurcations using computational and theoretical modeling. The model reproduces the variety of experimentally observed splitting behaviors. Splitting homogeneity and maximum shear stress along the vessel walls is predicted over a variety of physical parameters. Maximum shear stresses were found to decrease with increasing Reynolds number. The initial bubble length was found to affect the splitting behavior in the presence of gravitational asymmetry. This work was supported by NIH Grant R01EB006476.

Evaluating cochlear implant trauma to the scala vestibuli.

PubMed

Adunka, O; Kiefer, J; Unkelbach, M H; Radeloff, A; Gstoettner, W

2005-04-01

Placement of cochlear implant electrodes into the scala vestibuli may be intentional, e.g. in case of blocked scala tympani or unintentional as a result of trauma to the basilar membrane or erroneous location of the cochieostomy. The aim of this study was to evaluate the morphological consequences and cochlear trauma after implantation of different cochlear implant electrode arrays in the scala vestibuli. Human temporal bone study with histological and radiological evaluation. Twelve human cadaver temporal bones were implanted with different cochlear implant electrodes. Implanted bones were processed using a special method to section undecalcified bone. Cochlear trauma and intracochlear positions. All implanted electrodes were implanted into the scala vestibuli using a special approach that allows direct scala vestibuli insertions. Fractures of the osseous spiral lamina were evaluated in some bones in the basal cochlear regions. In most electrodes, delicate structures of the organ of Corti were left intact, however, Reissner's membrane was destroyed in all specimens and the electrode lay upon the tectorial membrane. In some bones the organ of Corti was destroyed. Scala vestibuli insertions did not cause severe trauma to osseous or neural structures, thus preserving the basis for electrostimulation of the cochlea. However, destruction of Reissner's membrane and impact on the Organ of Corti can be assumed to destroy residual hearing.

Compressible bubbles in Stokes flow

NASA Astrophysics Data System (ADS)

Crowdy, Darren G.

2003-02-01

The problem of a two-dimensional inviscid compressible bubble evolving in Stokes flow is considered. By generalizing the work of Tanveer & Vasconcelos (1995) it is shown that for certain classes of initial condition the quasi-steady free boundary problem for the bubble shape evolution is reducible to a finite set of coupled nonlinear ordinary differential equations, the form of which depends on the equation of state governing the relationship between the bubble pressure and its area. Recent numerical calculations by Pozrikidis (2001) using boundary integral methods are retrieved and extended. If the ambient pressures are small enough, it is shown that bubbles can expand significantly. It is also shown that a bubble evolving adiabatically is less likely to expand than an isothermal bubble.

Bubble propagation on a rail: a concept for sorting bubbles by size

NASA Astrophysics Data System (ADS)

Franco-Gómez, Andrés; Thompson, Alice B.; Hazel, Andrew L.; Juel, Anne

We demonstrate experimentally that the introduction of a rail, a small height constriction, within the cross-section of a rectangular channel could be used as a robust passive sorting device in two-phase fluid flows. Single air bubbles carried within silicone oil are generally transported on one side of the rail. However, for flow rates marginally larger than a critical value, a narrow band of bubble sizes can propagate (stably) over the rail, while bubbles of other sizes segregate to the side of the rail. The width of this band of bubble sizes increases with flow rate and the size of the most stable bubble can be tuned by varying the rail width. We present a complementary theoretical analysis based on a depth-averaged theory, which is in qualitative agreement with the experiments. The theoretical study reveals that the mechanism relies on a non-trivial interaction between capillary and viscous forces that is fully dynamic, rather than being a simple modification of capillary static solutions.

Key performance indicators in British military trauma.

PubMed

Stannard, Adam; Tai, Nigel R; Bowley, Douglas M; Midwinter, Mark; Hodgetts, Tim J

2008-08-01

Key performance indicators (KPI) are tools for assessing process and outcome in systems of health care provision and are an essential component in performance improvement. Although KPI have been used in British military trauma for 10 years, they remain poorly defined and are derived from civilian metrics that do not adjust for the realities of field trauma care. Our aim was to modify current trauma KPI to ensure they more faithfully reflect both the military setting and contemporary evidence in order to both aid accurate calibration of the performance of the British Defence Medical Services and act as a driver for performance improvement. A workshop was convened that was attended by senior, experienced doctors and nurses from all disciplines of trauma care in the British military. "Speciality-specific" KPI were developed by interest groups using evidence-based data where available and collective experience where this was lacking. In a final discussion these were streamlined into 60 KPI covering each phase of trauma management. The introduction of these KPI sets a number of important benchmarks by which British military trauma can be measured. As part of a performance improvement programme, these will allow closer monitoring of our performance and assist efforts to develop, train, and resource British military trauma providers.

Confinement and diffusion time-scales of CR hadrons in AGN-inflated bubbles

NASA Astrophysics Data System (ADS)

Prokhorov, D. A.; Churazov, E. M.

2017-09-01

While rich clusters are powerful sources of X-rays, γ-ray emission from these large cosmic structures has not been detected yet. X-ray radiative energy losses in the central regions of relaxed galaxy clusters are so strong that one needs to consider special sources of energy, likely active galactic nucleus (AGN) feedback, to suppress catastrophic cooling of the gas. We consider a model of AGN feedback that postulates that the AGN supplies the energy to the gas by inflating bubbles of relativistic plasma, whose energy content is dominated by cosmic-ray (CR) hadrons. If most of these hadrons can quickly escape the bubbles, then collisions of CRs with thermal protons in the intracluster medium (ICM) should lead to strong γ-ray emission, unless fast diffusion of CRs removes them from the cluster. Therefore, the lack of detections with modern γ-ray telescopes sets limits on the confinement time of CR hadrons in bubbles and CR diffusive propagation in the ICM.

Transformer overload characteristics---Bubble evolution

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

Woods, E.E.; Wendel, R.C.; Dresser, R.D.

1988-08-01

Project RP1289-3 explores significant parameters affecting bubble evolution from transformer oil under high temperature operating conditions to address the question: Does ''real life'' operation of a transformer cause harmful bubbling conditions. Studies outlined in the project are designed to determine when bubbling occurs in transformers and if bubbling can be harmful during the normal operation of these transformers. Data obtained from these studies should provide a basis for utilities to perform risk assessments in relation to their loading practices. The program is designed to demonstrate those conditions under which bubbling occurs in transformers by using controlled models and actual signalmore » phase transformers that were designed to give access to both high and low voltage windings for the purpose of viewing bubble generation. Results and observations from tests on the full-size transformers, thermal models, and electrical models have led to the conclusion that bubbles can occur under operating conditions. The electrical models show that dielectric strength can be reduced by as much as 40 percent due to the presence of bubbles. Because of factory safety considerations, the transformers could not be tested at hot spot temperatures greater than 140/degree/C. Therefore, there is no information on the dielectric strength of the full-size transformers under bubbling conditions. 4 refs., 28 figs., 45 tabs.« less

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…

The effect of both a thoracic trauma and a soft-tissue trauma on fracture healing in a rat model

PubMed Central

2011-01-01

Background and purpose There is some clinical evidence that fracture healing is impaired in multiply injured patients. Nothing is known, however, about the effects of various types of injuries and their contribution to a possible disturbance of the fracture-healing process. We investigated the effect of a thoracic trauma and an additional soft-tissue trauma on fracture healing in a rat tibia model. Methods 3 groups of rats were operated: group A with a simple fracture of the tibia and fibula, group B with a fracture and an additional thoracic trauma, and group C with a fracture, thoracic trauma, and an additional soft-tissue trauma. The fracture and the soft-tissue injury were produced by a special guillotine-like device and the thoracic trauma by a blast wave generator. After one day, the serum level of IL-6 was quantified, and at the end of the study (28 days) the mechanical properties and the callus volume of the healed tibia were determined. Results Increasing the severity of the injury caused IL-6 levels to more than double 1 day after injury. It halved the load to failure in mechanical tests and led to reduced callus volume after 28 days of healing. Interpretation Fracture healing is impaired when additional thoracic trauma and soft tissue trauma occurs. PMID:21463222

Gas depletion through single gas bubble diffusive growth and its effect on subsequent bubbles

NASA Astrophysics Data System (ADS)

Moreno Soto, Alvaro; Prosperetti, Andrea; Lohse, Detlef; van der Meer, Devaraj; Physics of Fluid Group Collaboration; MCEC Netherlands CenterMultiscale Catalytic Energy Conversion Collaboration

2016-11-01

In weakly supersaturated mixtures, bubbles are known to grow quasi-statically as diffusion-driven mass transfer governs the process. In the final stage of the evolution, before detachment, there is an enhancement of mass transfer, which changes from diffusion to natural convection. Once the bubble detaches, it leaves behind a gas-depleted area. The diffusive mass transfer towards that region cannot compensate for the amount of gas which is taken away by the bubble. Consequently, the consecutive bubble will grow in an environment which contains less gas than for the previous one. This reduces the local supersaturation of the mixture around the nucleation site, leading to a reduced bubble growth rate. We present quantitative experimental data on this effect and the theoretical model for depletion during the bubble growth rate. This work was supported by the Netherlands Center for Multiscale Catalytic Energy Conversion (MCEC), an NWO Gravitation programme funded by the Ministry of Education, Culture and Science of the government of the Netherlands.

Droplets, Bubbles and Ultrasound Interactions.

PubMed

Shpak, Oleksandr; Verweij, Martin; de Jong, Nico; Versluis, Michel

2016-01-01

The interaction of droplets and bubbles with ultrasound has been studied extensively in the last 25 years. Microbubbles are broadly used in diagnostic and therapeutic medical applications, for instance, as ultrasound contrast agents. They have a similar size as red blood cells, and thus are able to circulate within blood vessels. Perfluorocarbon liquid droplets can be a potential new generation of microbubble agents as ultrasound can trigger their conversion into gas bubbles. Prior to activation, they are at least five times smaller in diameter than the resulting bubbles. Together with the violent nature of the phase-transition, the droplets can be used for local drug delivery, embolotherapy, HIFU enhancement and tumor imaging. Here we explain the basics of bubble dynamics, described by the Rayleigh-Plesset equation, bubble resonance frequency, damping and quality factor. We show the elegant calculation of the above characteristics for the case of small amplitude oscillations by linearizing the equations. The effect and importance of a bubble coating and effective surface tension are also discussed. We give the main characteristics of the power spectrum of bubble oscillations. Preceding bubble dynamics, ultrasound propagation is introduced. We explain the speed of sound, nonlinearity and attenuation terms. We examine bubble ultrasound scattering and how it depends on the wave-shape of the incident wave. Finally, we introduce droplet interaction with ultrasound. We elucidate the ultrasound-focusing concept within a droplets sphere, droplet shaking due to media compressibility and droplet phase-conversion dynamics.

Soft Tissue Management in Facial Trauma

PubMed Central

Braun, Tara L.; Maricevich, Renata S.

2017-01-01

The management of soft tissue injury after facial trauma poses unique challenges to the plastic surgeon, given the specialized nature of facial tissue and the aesthetic importance of the face. The general principles of trauma management and wound care are applied in all cases. The management of severe injuries to the face is discussed in relation to the location and the mechanism of injury. Facial transplants have arisen in the past decade for the management of catastrophic soft tissue defects, although high morbidity and mortality after these non-life-saving operations must be considered in patient selection. PMID:28496386

Single-bubble sonoluminescence in sulfuric acid and water: bubble dynamics, stability, and continuous spectra.

PubMed

Puente, Gabriela F; García-Martínez, Pablo; Bonetto, Fabián J

2007-01-01

We present theoretical calculations of an argon bubble in a liquid solution of 85%wt sulfuric acid and 15%wt water in single-bubble sonoluminescence. We used a model without free parameters to be adjusted. We predict from first principles the region in parameter space for stable bubble evolution, the temporal evolution of the bubble radius, the maximum temperature, pressures, and the light spectra due to thermal emissions. We also used a partial differential equation based model (hydrocode) to compute the temperature and pressure evolutions at the center of the bubble during maximum compression. We found the behavior of this liquid mixture to be very different from water in several aspects. Most of the models in sonoluminescence were compared with water experimental results.

Electric field observations of equatorial bubbles

NASA Technical Reports Server (NTRS)

Aggson, T. L.; Maynard, N. C.; Hanson, W. B.; Saba, Jack L.

1992-01-01

Results from the double floating probe experiment performed on the San Marco D satellite are presented, with emphasis on the observation of large incremental changes in the convective electric field vector at the boundary of equatorial plasma bubbles. Attention is given to isolated bubble structures in the upper ionospheric F regions; these observed bubble encounters are divided into two types - type I (live bubbles) and type II (dead bubbles). Type I bubbles show varying degrees of plasma depletion and large upward velocities range up to 1000 km/s. The geometry of these bubbles is such that the spacecraft orbit may cut them where they are tilting either eastward or (more often) westward. Type II bubbles exhibit plasma density depletion but no appreciable upward convection. Both types of events are usually surrounded by a halo of plasma turbulence, which can extend considerably beyond the region of plasma depletion.

Single bubble sonoluminescence

NASA Astrophysics Data System (ADS)

Dan, Manas

In recent years considerable attention has been directed to the phenomenon of single bubble sonoluminescence, SBSL in which a single, stable, acoustically levitated bubble is made to oscillate with sufficiently large amplitude so as to emit picosecond light pulses in each cycle of the acoustic drive pressure. Remarkably, the phenomenon represents about twelve orders of magnitude of energy focusing. SBSL has been carefully and thoroughly studied in part of parameter space by previous authors. In the present work, the experimental observation of the influence of another important parameter namely the ambient pressure will be presented. It is the first complete and controlled study of the modifications of the bubble dynamics and SL emission due to the variation of the ambient pressure. It has been observed that the equilibrium radius as well as the maximum radius increase as the ambient pressure is decreased at constant driving pressure. Furthermore the expansion ratio (Rmax/ Rmin) increases as the ambient pressure is decreased, resulting in a change in the SL radiation. The intensity of SL emission increases about seven times for only a fifteen percent decrease of ambient pressure at constant driving pressure. However, it is not possible to push SL radiation beyond a certain limit by continuously decreasing the ambient pressure. On the other hand increasing the ambient pressure decreases the equilibrium radius, as well as the expansion ratio leading to a decrease of SL intensity. Amongst the SBSL emissions the light emission has been investigated rather elaborately. The other single bubble emission is the acoustic emission, AE. Here a detailed study of AE will be presented. The AE has been measured by a calibrated needle hydrophone in different regimes of bubble motion. The hydrophone response shows a large amplitude AE pulse which corresponds to the principal collapse, along with smaller amplitude pulses which can be associated with the after bounces of the bubble

Potential uses of vacuum bubbles in noise and vibration control

NASA Technical Reports Server (NTRS)

Ver, Istvan L.

1989-01-01

Vacuum bubbles are new acoustic elements which are dynamically more compliant than the gas volume they replace, but which are statically robust. They are made of a thin metallic shell with vacuum in their cavity. Consequently, they pose no danger in terms of contamination or fire hazard. The potential of the vacuum bubble concept for noise and vibration control was assessed with special emphases on spacecraft and aircraft applications. The following potential uses were identified: (1) as a cladding, to reduce sound radiation of vibrating surfaces and the sound excitation of structures, (2) as a screen, to reflect or absorb an incident sound wave, and (3) as a liner, to increase low frequency sound transmission loss of double walls and to increase the low frequency sound attenuation of muffler baffles. It was found that geometric and material parameters must be controlled to a very high accuracy to obtain optimal performance and that performance is highly sensitive to variations in static pressure. Consequently, it was concluded that vacuum bubbles have more potential in spacecraft applications where static pressure is controlled more than in aircraft applications where large fluctuations in static pressure are common.

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

PubMed

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

2014-08-01

This work shows a successful example of coupling of theory and experiment to study the tribology of bubble rubbing on solid surface. Such kind of investigation is reported for the first time in the literature. A theory about wetting film intercalated between bubble and moving solid surface was developed, thus deriving the non-linear evolution differential equation which accounted for the friction slip coefficient at the solid surface. The stationary 3D film thickness profile, which appears to be a solution of the differential equation, for each particular speed of motion of the solid surface was derived by means of special procedure and unique interferometric experimental setup. This allowed us to determine the 3D map of the lift pressure within the wetting film, the friction force per unit area and the friction coefficient of rubbing at different speeds of motion of the solid surface. Thus, we observed interesting tribological details about the rubbing of the bubble on the solid surface like for example: 1. A regime of mixed friction between dry and lubricated friction exists in the range of 6-170 μm/s, beyond which the rubbing between the bubble and solid becomes completely lubricated and passes through the maximum; 2. The friction coefficient of rubbing has high values at very small speeds of solid's motion and reduces substantially with the increase of the speed of the solid motion until reaching small values, which change insignificantly with the further increase of the speed of the solid. Despite the numerous studies on the motion of bubble/droplet in close proximity to solid wall in the literature, the present investigation appears to be a step ahead in this area as far as we were able to derive 3D maps of the bubble close to the solid surface, which makes the investigation more profound. © 2013.

Molecular Dynamics Investigation of Each Bubble Behavior in Coarsening of Cavitation Bubbles in a Finite Space

NASA Astrophysics Data System (ADS)

Tsuda, Shin-Ichi; Nakano, Yuta; Watanabe, Satoshi

2017-11-01

Recently, several studies using Molecular Dynamics (MD) simulation have been conducted for investigation of Ostwald ripening of cavitation bubbles in a finite space. The previous studies focused a characteristic length of bubbles as one of the spatially-averaged quantities, but each bubble behavior was not been investigated in detail. The objective of this study is clarification of the characteristics of each bubble behavior in Ostwald ripening, and we conducted MD simulation of a Lennard-Jones fluid in a semi-confined space. As a result, the time dependency of the characteristic length of bubbles as a spatially-averaged quantity suggested that the driving force of the Ostwald ripening is Evaporation/Condensation (EC) across liquid-vapor surface, which is the same result as the previous works. The radius change of the relatively larger bubbles also showed the same tendency to a classical EC model. However, the sufficiently smaller bubbles than the critical size, e.g., the bubbles just before collapsing, showed a different characteristic from the classical EC model. Those smaller bubbles has a tendency to be limited by mechanical non-equilibrium in which viscosity of liquid is dominant rather than by EC across liquid-vapor surface. This work was supported by JSPS KAKENHI Grant Number JP16K06085.

Bubble memory module for spacecraft application

NASA Technical Reports Server (NTRS)

Hayes, P. J.; Looney, K. T.; Nichols, C. D.

1985-01-01

Bubble domain technology offers an all-solid-state alternative for data storage in onboard data systems. A versatile modular bubble memory concept was developed. The key module is the bubble memory module which contains all of the storage devices and circuitry for accessing these devices. This report documents the bubble memory module design and preliminary hardware designs aimed at memory module functional demonstration with available commercial bubble devices. The system architecture provides simultaneous operation of bubble devices to attain high data rates. Banks of bubble devices are accessed by a given bubble controller to minimize controller parts. A power strobing technique is discussed which could minimize the average system power dissipation. A fast initialization method using EEPROM (electrically erasable, programmable read-only memory) devices promotes fast access. Noise and crosstalk problems and implementations to minimize these are discussed. Flight memory systems which incorporate the concepts and techniques of this work could now be developed for applications.

[Haemothorax after blunt thoracic trauma].

PubMed

Siller, J; Havlícek, K

2009-05-01

Haemothorax is frequent consequence of blunt and penetrating thoracic trauma and is usually associated with pneumothorax. The occurence of haemothorax in blunt thoracic trauma patients is estimated between 25-75%. The reason of bleeding is impairment of intercostal arteries or lung parenchyma after trauma of the ribs. Uncontrolled bleeding is the main cause of the death. The article is focused on the treatment of this injury. There were enrolled 238 patients with thoracic trauma, who were admitted into our department, into the study. The average age of the patients was 42.5 years. The ISS > or = 16 were in 101 patients. Forty two patients were artefitially ventilated. Conservative treatment prevails, almost in 65%. Special care was indicated in patients with haemothorax (fluidotoraxem). Clinically and based on other screening methods the presence of the fluid in thoracic cavity was in 131 patients. Surgical treatment (punction, drainage, videothoracoscopy and thoracotomy) was necessary in 47 (35.0%). Thoracotomy for the bleeding was indicated in seven cases (5.3 %). In diagnostics and in treatment of the bleeding in thoracic trauma patients the most important factor is clinical status of the patient. Indication for thoracotomy must be unambigous. Massive haemotorax leads to restrictive ventilation disorder with decreased preload and can be activator of the haemocolaguation disorders. This fact decreases chance for the survival of the patient.

Consistent cosmic bubble embeddings

NASA Astrophysics Data System (ADS)

Haque, S. Shajidul; Underwood, Bret

2017-05-01

The Raychaudhuri equation for null rays is a powerful tool for finding consistent embeddings of cosmological bubbles in a background spacetime in a way that is largely independent of the matter content. We find that spatially flat or positively curved thin wall bubbles surrounded by a cosmological background must have a Hubble expansion that is either contracting or expanding slower than the background, which is a more stringent constraint than those obtained by the usual Israel thin-wall formalism. Similarly, a cosmological bubble surrounded by Schwarzschild space, occasionally used as a simple "swiss cheese" model of inhomogenities in an expanding universe, must be contracting (for spatially flat and positively curved bubbles) and bounded in size by the apparent horizon.

Sinking bubbles in stout beers

NASA Astrophysics Data System (ADS)

Lee, W. T.; Kaar, S.; O'Brien, S. B. G.

2018-04-01

A surprising phenomenon witnessed by many is the sinking bubbles seen in a settling pint of stout beer. Bubbles are less dense than the surrounding fluid so how does this happen? Previous work has shown that the explanation lies in a circulation of fluid promoted by the tilted sides of the glass. However, this work has relied heavily on computational fluid dynamics (CFD) simulations. Here, we show that the phenomenon of sinking bubbles can be predicted using a simple analytic model. To make the model analytically tractable, we work in the limit of small bubbles and consider a simplified geometry. The model confirms both the existence of sinking bubbles and the previously proposed mechanism.

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.

Bubbles in live-stranded dolphins.

PubMed

Dennison, S; Moore, M J; Fahlman, A; Moore, K; Sharp, S; Harry, C T; Hoppe, J; Niemeyer, M; Lentell, B; Wells, R S

2012-04-07

Bubbles in supersaturated tissues and blood occur in beaked whales stranded near sonar exercises, and post-mortem in dolphins bycaught at depth and then hauled to the surface. To evaluate live dolphins for bubbles, liver, kidneys, eyes and blubber-muscle interface of live-stranded and capture-release dolphins were scanned with B-mode ultrasound. Gas was identified in kidneys of 21 of 22 live-stranded dolphins and in the hepatic portal vasculature of 2 of 22. Nine then died or were euthanized and bubble presence corroborated by computer tomography and necropsy, 13 were released of which all but two did not re-strand. Bubbles were not detected in 20 live wild dolphins examined during health assessments in shallow water. Off-gassing of supersaturated blood and tissues was the most probable origin for the gas bubbles. In contrast to marine mammals repeatedly diving in the wild, stranded animals are unable to recompress by diving, and thus may retain bubbles. Since the majority of beached dolphins released did not re-strand it also suggests that minor bubble formation is tolerated and will not lead to clinically significant decompression sickness.

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.

Bubble bursting at an interface

NASA Astrophysics Data System (ADS)

Kulkarni, Varun; Sajjad, Kumayl; Anand, Sushant; Fezzaa, Kamel

2017-11-01

Bubble bursting is crucial to understanding the life span of bubbles at an interface and more importantly the nature of interaction between the bulk liquid and the outside environment from the point of view of chemical and biological material transport. The dynamics of the bubble as it rises from inside the liquid bulk to its disappearance on the interface after bursting is an intriguing process, many aspects of which are still being explored. In our study, we make detailed high speed imaging measurements to examine carefully the hole initiation and growth in bursting bubbles that unearth some interesting features of the process. Previous analyses available in literature are revisited based on our novel experimental visualizations. Using a combination of experiments and theory we investigate the role of various forces during the rupturing process. This work aims to further our current knowledge of bubble dynamics at an interface with an aim of predicting better the bubble evolution from its growth to its eventual integration with the liquid bulk.

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

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

Mechanisms of single bubble cleaning.

PubMed

Reuter, Fabian; Mettin, Robert

2016-03-01

The dynamics of collapsing bubbles close to a flat solid is investigated with respect to its potential for removal of surface attached particles. Individual bubbles are created by nanosecond Nd:YAG laser pulses focused into water close to glass plates contaminated with melamine resin micro-particles. The bubble dynamics is analysed by means of synchronous high-speed recordings. Due to the close solid boundary, the bubble collapses with the well-known liquid jet phenomenon. Subsequent microscopic inspection of the substrates reveals circular areas clean of particles after a single bubble generation and collapse event. The detailed bubble dynamics, as well as the cleaned area size, is characterised by the non-dimensional bubble stand-off γ=d/Rmax, with d: laser focus distance to the solid boundary, and Rmax: maximum bubble radius before collapse. We observe a maximum of clean area at γ≈0.7, a roughly linear decay of the cleaned circle radius for increasing γ, and no cleaning for γ>3.5. As the main mechanism for particle removal, rapid flows at the boundary are identified. Three different cleaning regimes are discussed in relation to γ: (I) For large stand-off, 1.8<γ<3.5, bubble collapse induced vortex flows touch down onto the substrate and remove particles without significant contact of the gas phase. (II) For small distances, γ<1.1, the bubble is in direct contact with the solid. Fast liquid flows at the substrate are driven by the jet impact with its subsequent radial spreading, and by the liquid following the motion of the collapsing and rebounding bubble wall. Both flows remove particles. Their relative timing, which depends sensitively on the exact γ, appears to determine the extension of the area with forces large enough to cause particle detachment. (III) At intermediate stand-off, 1.1<γ<1.8, only the second bubble collapse touches the substrate, but acts with cleaning mechanisms similar to an effective small γ collapse: particles are removed by

Dynamics of two-dimensional bubbles.

PubMed

Piedra, Saúl; Ramos, Eduardo; Herrera, J Ramón

2015-06-01

The dynamics of two-dimensional bubbles ascending under the influence of buoyant forces is numerically studied with a one-fluid model coupled with the front-tracking technique. The bubble dynamics are described by recording the position, shape, and orientation of the bubbles as functions of time. The qualitative properties of the bubbles and their terminal velocities are described in terms of the Eötvos (ratio of buoyancy to surface tension) and Archimedes numbers (ratio of buoyancy to viscous forces). The terminal Reynolds number result from the balance of buoyancy and drag forces and, consequently, is not an externally fixed parameter. In the cases that yield small Reynolds numbers, the bubbles follow straight paths and the wake is steady. A more interesting behavior is found at high Reynolds numbers where the bubbles follow an approximately periodic zigzag trajectory and an unstable wake with properties similar to the Von Karman vortex street is formed. The dynamical features of the motion of single bubbles are compared to experimental observations of air bubbles ascending in a water-filled Hele-Shaw cell. Although the comparison is not strictly valid in the sense that the effect of the lateral walls is not incorporated in the model, most of the dynamical properties observed are in good qualitative agreement with the numerical calculations. Hele-Shaw cells with different gaps have been used to determine the degree of approximation of the numerical calculation. It is found that for the relation between the terminal Reynolds number and the Archimedes number, the numerical calculations are closer to the observations of bubble dynamics in Hele-Shaw cells of larger gaps.

Acoustical stability of a sonoluminescing bubble

NASA Astrophysics Data System (ADS)

Holzfuss, Joachim; Rüggeberg, Matthias; Holt, R. Glynn

2002-10-01

In the parameter region for sonoluminescence of a single levitated bubble in a water-filled resonator it is observed that the bubble may have an enormous spatial stability leaving it ``pinned'' in the fluid and allowing it to emit light pulses of picosecond accuracy. We report here observations of a complex harmonic structure in the acoustic field surrounding a sonoluminescing bubble. We show that this complex sound field determines the position of the bubble and may either increase or decrease its spatial stability. The acoustic environment of the bubble is the result of the excitation of high-order normal modes of the resonator by the outgoing shock wave generated by the bubble collapse.

Between soap bubbles and vesicles: The dynamics of freely floating smectic bubbles

NASA Astrophysics Data System (ADS)

Stannarius, Ralf; May, Kathrin; Harth, Kirsten; Trittel, Torsten

2013-03-01

The dynamics of droplets and bubbles, particularly on microscopic scales, are of considerable importance in biological, environmental, and technical contexts. We introduce freely floating bubbles of smectic liquid crystals and report their unique dynamic properties. Smectic bubbles can be used as simple models for dynamic studies of fluid membranes. In equilibrium, they form minimal surfaces like soap films. However, shape transformations of closed smectic membranes that change the surface area involve the formation and motion of molecular layer dislocations. These processes are slow compared to the capillary wave dynamics, therefore the effective surface tension is zero like in vesicles. Freely floating smectic bubbles are prepared from collapsing catenoid films and their dynamics is studied with optical high-speed imaging. Experiments are performed under normal gravity and in microgravity during parabolic flights. Supported by DLR within grant OASIS-Co.

Cohesion of Bubbles in Foam

ERIC Educational Resources Information Center

Ross, Sydney

1978-01-01

The free-energy change, or binding energy, of an idealized bubble cluster is calculated on the basis of one mole of gas, and on the basis of a single bubble going from sphere to polyhedron. Some new relations of bubble geometry are developed in the course of the calculation. (BB)

Capillarity-Driven Bubble Separations

NASA Astrophysics Data System (ADS)

Wollman, Andrew; Weislogel, Mark; Dreyer, Michael

2013-11-01

Techniques for phase separation in the absence of gravity continue to be sought after 5 decades of space flight. This work focuses on the fundamental problem of gas bubble separation in bubbly flows through open wedge-shaped channel in a microgravity environment. The bubbles appear to rise in the channel and coalesce with the free surface. Forces acting on the bubble are the combined effects of surface tension, wetting conditions, and geometry; not buoyancy. A single dimensionless group is identified that characterizes the bubble behavior and supportive experiments are conducted in a terrestrial laboratory, in a 2.1 second drop tower, and aboard the International Space Station as part of the Capillary Channel Flow (CCF) experiments. The data is organized into regime maps that provide insight on passive phase separations for applications ranging from liquid management aboard spacecraft to lab-on-chip technologies. NASA NNX09AP66A, NASA Oregon Space Grant NNX10AK68H, NASA NNX12AO47A, DLR 50WM0535/0845/1145

Trauma related to falls from trees treated in a specialized trauma centre in Burkina-Faso-one hundred and six cases treated in one year.

PubMed

Dakouré, Patrick W H; Diallo, Malick; Traoré, André-Charles V; Gandéma, Salifou; Barro, Sie Drissa; Traoré, Ibrahim Alain; Zaré, Cyprien

2015-12-01

Falls from trees related traumas are rarely reported in literature. They are public health problems in developing countries where their frequency is still important. The aim of the study is to describe falls from trees related trauma patterns and to present preventative measures. An annual ongoing prospective study was held in our trauma emergency department (ED) about all the patients who sustained an injury after a recent fall from tree. A questionnaire related to the patient and to the trauma was established. The data were encoded and analysed by a statistical software. One hundred six patients who sustained a fall from tree trauma, out of a total of 139, were studied. Most patients were under 15 years old (76.4 %); they were injured in fruits season (33 %) after a fall from a fruit tree (mango trees, Shea trees, Néré, etc.) and were received late (86 %). Injuries were polymorphic from traumatic brain injuries (51.8 %) and spine injuries (13.2 %) to thoraco-abdominal (21.6 %) and limbs injuries (46.2 %). Three housewives were pregnant at the time of the trauma with secondary abortions. Patients were managed medically (33.9 %), surgically (19.8 %) or by casting (34.9 %) with good outcome in 59 cases. Twelve patients refused medical care and two died. Education programs must focus on picking fruits and leaves in order to make them safe and prevent injuries related to these traditional or professional activities.

Leverage bubble

NASA Astrophysics Data System (ADS)

Yan, Wanfeng; Woodard, Ryan; Sornette, Didier

2012-01-01

Leverage is strongly related to liquidity in a market and lack of liquidity is considered a cause and/or consequence of the recent financial crisis. A repurchase agreement is a financial instrument where a security is sold simultaneously with an agreement to buy it back at a later date. Repurchase agreement (repo) market size is a very important element in calculating the overall leverage in a financial market. Therefore, studying the behavior of repo market size can help to understand a process that can contribute to the birth of a financial crisis. We hypothesize that herding behavior among large investors led to massive over-leveraging through the use of repos, resulting in a bubble (built up over the previous years) and subsequent crash in this market in early 2008. We use the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles and behavioral finance to study the dynamics of the repo market that led to the crash. The JLS model qualifies a bubble by the presence of characteristic patterns in the price dynamics, called log-periodic power law (LPPL) behavior. We show that there was significant LPPL behavior in the market before that crash and that the predicted range of times predicted by the model for the end of the bubble is consistent with the observations.

The Early Years: Blowing Bubbles

ERIC Educational Resources Information Center

Ashbrook, Peggy

2016-01-01

Blowing bubbles is not only a favorite summer activity for young children. Studying bubbles that are grouped together, or "foam," is fun for children and fascinating to many real-world scientists. Foam is widely used--from the bedroom (mattresses) to outer space (insulating panels on spacecraft). Bubble foam can provide children a…

Distribution of specialized care centers in the United States.

PubMed

Wang, Henry E; Yealy, Donald M

2012-11-01

As a recommended strategy for optimally managing critical illness, regionalization of care involves matching the needs of the target population with available hospital resources. The national supply and characteristics of hospitals providing specialized critical care services is currently unknown. We seek to characterize the current distribution of specialized care centers in the United States. Using public data linked with the American Hospital Association directory and US Census, we identified US general acute hospitals providing specialized care for ST-segment elevation myocardial infarction (STEMI) (≥40 annual primary percutaneous coronary interventions reported in Medicare Hospital Compare), stroke (The Joint Commission certified stroke centers), trauma (American College of Surgeons or state-designated, adult or pediatric, level I or II), and pediatric critical care (presence of a pediatric ICU) services. We determined the characteristics and state-level distribution and density of specialized care centers (centers per state and centers per state population). Among 4,931 acute care hospitals in the United States, 1,325 (26.9%) provided one of the 4 defined specialized care services, including 574 STEMI, 763 stroke, 508 trauma, and 457 pediatric critical care centers. Approximately half of the 1,325 hospitals provided 2 or more specialized services, and one fifth provided 3 or 4 specialized services. There was variation in the number of each type of specialized care center in each state: STEMI median 7 interquartile range (IQR 2 to 14), stroke 8 (IQR 3 to 17), trauma 6 (IQR 3 to 11), pediatric specialized care 6 (IQR 3 to 11). Similarly, there was variation in the number of each type of specialized care center per population: STEMI median 1 center per 585,135 persons (IQR 418,729 to 696,143), stroke 1 center per 412,188 persons (IQR 321,604 to 572,387), trauma 1 center per 610,589 persons (IQR 406,192 to 917,588), and pediatric critical care 1 center per 665

Infinite stream of Hele--Shaw bubbles

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

Burgess, D.; Tanveer, S.

1991-03-01

Exact solutions are presented for a steady stream of bubbles in a Hele--Shaw cell when the effect of surface tension is neglected. These solutions form a three-parameter family. For specified area and distance between bubbles, the speed of the bubble remains arbitrary when surface tension is neglected. However, numerical and analytical evidence indicates that this arbitrariness is removed by the effect of surface tension. The branch of solutions that corresponds to the McLean--Saffman finger solution were primarily studied. A dramatic increase was observed in bubble speeds when the distance between bubbles is on the order of a bubble diameter, whichmore » may have relevance to experiments done by Maxworthy (J. Fluid Mech. {bold 173}, 95 (1986)).« 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.

Bubble baths: just splashing around?

NASA Astrophysics Data System (ADS)

Robinson, Wesley; Speirs, Nathan; Sharker, Saberul Islam; Hurd, Randy; Williams, Bj; Truscott, Tadd

2016-11-01

Soap Bubbles on the water surface would seem to be an intuitive means for splash suppression, but their presence appears to be a double edged sword. We present on the water entry of hydrophilic spheres where the liquid surface is augmented by the presence of a bubble layer, similar to a bubble bath. While the presence of a bubble layer can diminish splashing upon impact at low Weber numbers, it also induces cavity formation at speeds below the critical velocity. The formation of a cavity generally results in larger Worthington jets and thus, larger amounts of ejected liquid. Bubble layers induce cavity formation by wetting the sphere prior to liquid impact, causing them to form cavities similar to those created by hydrophobic spheres. Droplets present on a pre-wetted sphere disrupt the flow of the advancing liquid during entry, pushing it away from the impacting body to form an entrained air cavity. This phenomena was noted by Worthington with pre-wetted stone marbles, and suggests that the application of a bubble layer is generally ineffective as a means of splash suppression.

Watson Jones Lecture. The organisation of trauma services in the UK.

PubMed Central

Templeton, J.

2000-01-01

To provide a high level of orthopaedic trauma care, education and research, across the country, trauma services in the UK require modification. Good information is necessary prior to formulating ideas and proposals. Trauma care provision must be considered comprehensively at both the national and local levels. As a first step, it is important to know just how many acute hospitals there are in the country. It is also important to know about the distribution of surgical specialities and the number of consultant orthopaedic surgeons staffing those hospitals. Images Figure 1 PMID:10700769

Neural basis of economic bubble behavior.

PubMed

Ogawa, A; Onozaki, T; Mizuno, T; Asamizuya, T; Ueno, K; Cheng, K; Iriki, A

2014-04-18

Throughout human history, economic bubbles have formed and burst. As a bubble grows, microeconomic behavior ceases to be constrained by realistic predictions. This contradicts the basic assumption of economics that agents have rational expectations. To examine the neural basis of behavior during bubbles, we performed functional magnetic resonance imaging while participants traded shares in a virtual stock exchange with two non-bubble stocks and one bubble stock. The price was largely deflected from the fair price in one of the non-bubble stocks, but not in the other. Their fair prices were specified. The price of the bubble stock showed a large increase and battering, as based on a real stock-market bust. The imaging results revealed modulation of the brain circuits that regulate trade behavior under different market conditions. The premotor cortex was activated only under a market condition in which the price was largely deflected from the fair price specified. During the bubble, brain regions associated with the cognitive processing that supports order decisions were identified. The asset preference that might bias the decision was associated with the ventrolateral prefrontal cortex and the dorsolateral prefrontal cortex (DLPFC). The activity of the inferior parietal lobule (IPL) was correlated with the score of future time perspective, which would bias the estimation of future price. These regions were deemed to form a distinctive network during the bubble. A functional connectivity analysis showed that the connectivity between the DLPFC and the IPL was predominant compared with other connectivities only during the bubble. These findings indicate that uncertain and unstable market conditions changed brain modes in traders. These brain mechanisms might lead to a loss of control caused by wishful thinking, and to microeconomic bubbles that expand, on the macroscopic scale, toward bust. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

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.

Bubble composition of natural gas seeps discovered along the Cascadia Continental Margin

NASA Astrophysics Data System (ADS)

Baumberger, T.; Merle, S. G.; Embley, R. W.; Seabrook, S.; Raineault, N.; Lilley, M. D.; Evans, L. J.; Walker, S. L.; Lupton, J. E.

2016-12-01

Gas hydrates and gas-filled pockets present in sedimentary deposits have been recognized as large reservoirs for reduced carbon in the Earth's crust. This is particularly relevant in geological settings with high carbon input, such as continental margins. During expedition NA072 on the E/V Nautilus (operated by the Ocean Exploration Trust Inc.) in June 2016, the U.S. Cascadia Continental Margin (Washington, Oregon and northern California) was explored for gas seepage from sediments. During this expedition, over 400 bubble plumes at water depths ranging from 125 and 1640 m were newly discovered, and five of them were sampled for gas bubble composition using specially designed gas tight fluid samplers mounted on the Hercules remotely operated vehicle (ROV). These gas bubble samples were collected at four different depths, 494 m (rim of Astoria Canyon), 615 and 620 m (SW Coquille Bank), 849 m (floor of Astoria Canyon) and 1227 m (Heceta SW). At the two deeper sites, exposed hydrate was present in the same area where bubbles were seeping out from the seafloor. Other than the escaping gas bubbles, no other fluid flow was visible. However, the presence of bacterial mats point to diffuse fluid flow present in the affected area. In this study we present the results of the currently ongoing geochemical analysis of the gas bubbles released at the different sites and depths. Noble gas analysis, namely helium and neon, will give information about the source of the helium as well as about potential fractionation between helium and neon associated with gas hydrates. The characterization of these gas samples will also include total gas (CO2, H2, N2, O2, Ar, CH4 and other hydrocarbons) and stable isotope analysis (C and H). This dataset will reveal the chemical composition of the seeping bubbles as well as give information about the possible sources of the carbon contained in the seeping gas.

Influence of the bubble-bubble interaction on destruction of encapsulated microbubbles under ultrasound.

PubMed

Yasui, Kyuichi; Lee, Judy; Tuziuti, Toru; Towata, Atsuya; Kozuka, Teruyuki; Iida, Yasuo

2009-09-01

Influence of the bubble-bubble interaction on the pulsation of encapsulated microbubbles has been studied by numerical simulations under the condition of the experiment reported by Chang et al. [IEEE Trans. Ultrason Ferroelectr. Freq. Control 48, 161 (2001)]. It has been shown that the natural (resonance) frequency of a microbubble decreases considerably as the microbubble concentration increases to relatively high concentrations. At some concentration, the natural frequency may coincide with the driving frequency. Microbubble pulsation becomes milder as the microbubble concentration increases except at around the resonance condition due to the stronger bubble-bubble interaction. This may be one of the reasons why the threshold of acoustic pressure for destruction of an encapsulated microbubble increases as the microbubble concentration increases. A theoretical model for destruction has been proposed.

Dissolving Bubbles in Glass

NASA Technical Reports Server (NTRS)

Weinberg, M. C.; Oronato, P. I.; Uhlmann, D. R.

1984-01-01

Analytical expression used to calculate time it takes for stationary bubbles of oxygen and carbon dioxide to dissolve from glass melt. Technique based on analytical expression for bubble radius as function time, with consequences of surface tension included.

Blowing magnetic skyrmion bubbles

DOE PAGES

Jiang, Wanjun; Upadhyaya, Pramey; Zhang, Wei; ...

2015-06-11

The formation of soap bubbles from thin films is accompanied by topological transitions. In this paper, we show how a magnetic topological structure, a skyrmion bubble, can be generated in a solid-state system in a similar manner. Using an inhomogeneous in-plane current in a system with broken inversion symmetry, we experimentally “blow” magnetic skyrmion bubbles from a geometrical constriction. The presence of a spatially divergent spin-orbit torque gives rise to instabilities of the magnetic domain structures that are reminiscent of Rayleigh-Plateau instabilities in fluid flows. We determine a phase diagram for skyrmion formation and reveal the efficient manipulation of thesemore » dynamically created skyrmions, including depinning and motion. Finally, the demonstrated current-driven transformation from stripe domains to magnetic skyrmion bubbles could lead to progress in skyrmion-based spintronics.« less

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.

Research progress on combat trauma treatment in cold regions.

PubMed

Wang, Hui-Shan; Han, Jin-Song

2014-01-01

Cold regions are a special combat environment in which low temperatures have a great impact on human metabolism and other vital functions, including the nervous, motion, cardiovascular, circulatory, respiratory, and urinary systems; consequently, low temperatures often aggravate existing trauma, leading to high mortality rates if rapid and appropriate treatment is not provided. Hypothermia is an independent risk factor of fatality following combat trauma; therefore, proactive preventative measures are needed to reduce the rate of mortality. After summarizing the basic research on battlefield environments and progress in the prevention and treatment of trauma, this article concludes that current treatment and prevention measures for combat trauma in cold regions are inadequate. Future molecular biology studies are needed to elucidate the mechanisms and relevant cell factors underlying bodily injury caused by cold environment, a research goal will also allow further exploration of corresponding treatments.

[First aid system for trauma: development and status].

PubMed

Chen, D K; Lin, W C; Zhang, P; Kuang, S J; Huang, W; Wang, T B

2017-04-18

With the great progress of the economy, the level of industrialization has been increasing year by year, which leads to an increase in accidental trauma accidents. Chinese annual death of trauma is already more than 400 000, which makes trauma the fifth most common cause of death, following malignant tumor, heart, brain and respiratory diseases. Trauma is the leading cause of the death of young adults. At the same time, trauma has become a serious social problem in peace time. Trauma throws great treats on human health and life. As an important part in the medical and social security system, the emergency of trauma system occupies a very important position in the emergency medical service system. In European countries as well as the United States and also many other developed countries, trauma service system had a long history, and progressed to an advanced stage. However, Chinese trauma service system started late and is still developing. It has not turned into a complete and standardized system yet. This review summarizes the histories and current situations of the development of traumatic first aid system separately in European countries, the United States and our country. Special attentions are paid to the effects of the pre- and in-hospital emergency care. We also further try to explore the Chinese trauma emergency model that adapts to the situations of China and characteristics of different regions of China. Our review also introduces the trauma service system that suits the situations of China proposed by Professor Jiang Baoguo's team in details, taking Chinese conditions into account, they conducted a thematic study and made an expert consensus on pre-hospital emergency treatment of severe trauma, providing a basic routine and guidance of severe trauma treatment for those pre-hospital emergency physicians. They also advised to establish independent trauma disciplines and trauma specialist training systems, and to build the regional trauma care system as

FEASTING BLACK HOLE BLOWS BUBBLES

NASA Technical Reports Server (NTRS)

2002-01-01

A monstrous black hole's rude table manners include blowing huge bubbles of hot gas into space. At least, that's the gustatory practice followed by the supermassive black hole residing in the hub of the nearby galaxy NGC 4438. Known as a peculiar galaxy because of its unusual shape, NGC 4438 is in the Virgo Cluster, 50 million light-years from Earth. These NASA Hubble Space Telescope images of the galaxy's central region clearly show one of the bubbles rising from a dark band of dust. The other bubble, emanating from below the dust band, is barely visible, appearing as dim red blobs in the close-up picture of the galaxy's hub (the colorful picture at right). The background image represents a wider view of the galaxy, with the central region defined by the white box. These extremely hot bubbles are caused by the black hole's voracious eating habits. The eating machine is engorging itself with a banquet of material swirling around it in an accretion disk (the white region below the bright bubble). Some of this material is spewed from the disk in opposite directions. Acting like high-powered garden hoses, these twin jets of matter sweep out material in their paths. The jets eventually slam into a wall of dense, slow-moving gas, which is traveling at less than 223,000 mph (360,000 kph). The collision produces the glowing material. The bubbles will continue to expand and will eventually dissipate. Compared with the life of the galaxy, this bubble-blowing phase is a short-lived event. The bubble is much brighter on one side of the galaxy's center because the jet smashed into a denser amount of gas. The brighter bubble is 800 light-years tall and 800 light-years across. The observations are being presented June 5 at the American Astronomical Society meeting in Rochester, N.Y. Both pictures were taken March 24, 1999 with the Wide Field and Planetary Camera 2. False colors were used to enhance the details of the bubbles. The red regions in the picture denote the hot gas

Slowing down bubbles with sound

NASA Astrophysics Data System (ADS)

Poulain, Cedric; Dangla, Remie; Guinard, Marion

2009-11-01

We present experimental evidence that a bubble moving in a fluid in which a well-chosen acoustic noise is superimposed can be significantly slowed down even for moderate acoustic pressure. Through mean velocity measurements, we show that a condition for this effect to occur is for the acoustic noise spectrum to match or overlap the bubble's fundamental resonant mode. We render the bubble's oscillations and translational movements using high speed video. We show that radial oscillations (Rayleigh-Plesset type) have no effect on the mean velocity, while above a critical pressure, a parametric type instability (Faraday waves) is triggered and gives rise to nonlinear surface oscillations. We evidence that these surface waves are subharmonic and responsible for the bubble's drag increase. When the acoustic intensity is increased, Faraday modes interact and the strongly nonlinear oscillations behave randomly, leading to a random behavior of the bubble's trajectory and consequently to a higher slow down. Our observations may suggest new strategies for bubbly flow control, or two-phase microfluidic devices. It might also be applicable to other elastic objects, such as globules, cells or vesicles, for medical applications such as elasticity-based sorting.

Unorthodox bubbles when boiling in cold water.

PubMed

Parker, Scott; Granick, Steve

2014-01-01

High-speed movies are taken when bubbles grow at gold surfaces heated spotwise with a near-infrared laser beam heating water below the boiling point (60-70 °C) with heating powers spanning the range from very low to so high that water fails to rewet the surface after bubbles detach. Roughly half the bubbles are conventional: They grow symmetrically through evaporation until buoyancy lifts them away. Others have unorthodox shapes and appear to contribute disproportionately to heat transfer efficiency: mushroom cloud shapes, violently explosive bubbles, and cavitation events, probably stimulated by a combination of superheating, convection, turbulence, and surface dewetting during the initial bubble growth. Moreover, bubbles often follow one another in complex sequences, often beginning with an unorthodox bubble that stirs the water, followed by several conventional bubbles. This large dataset is analyzed and discussed with emphasis on how explosive phenomena such as cavitation induce discrepancies from classical expectations about boiling.

Pinch-off Scaling Law of Soap Bubbles

NASA Astrophysics Data System (ADS)

Davidson, John; Ryu, Sangjin

2014-11-01

Three common interfacial phenomena that occur daily are liquid drops in gas, gas bubbles in liquid and thin-film bubbles. One aspect that has been studied for these phenomena is the formation or pinch-off of the drop/bubble from the liquid/gas threads. In contrast to the formation of liquid drops in gas and gas bubbles in liquid, thin-film bubble pinch-off has not been well documented. Having thin-film interfaces may alter the pinch-off process due to the limiting factor of the film thickness. We observed the pinch-off of one common thin-film bubble, soap bubbles, in order to characterize its pinch-off behavior. We achieved this by constructing an experimental model replicating the process of a human producing soap bubbles. Using high-speed videography and image processing, we determined that the minimal neck radius scaled with the time left till pinch-off, and that the scaling law exponent was 2/3, similar to that of liquid drops in gas.

Bubbles in Sediments

DTIC Science & Technology

1999-09-30

saturated poroelastic medium. The transition matrix scattering formalism was used to develop the scattered acoustic field(s) such that appropriate...sediment increases from a fluid model (simplest) to a fluid-saturated poroelastic model (most complex). Laboratory experiments in carefully quantified...of a linear acoustic field from a bubble, collection of bubbles, or other targets embedded in a fluid-saturated sediment are not well known. This

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

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.

Acoustic Methods Remove Bubbles From Liquids

NASA Technical Reports Server (NTRS)

Trinh, E.; Elleman, D. D.; Wang, T. G.

1983-01-01

Two acoustic methods applied to molten glass or other viscous liquids to remove bubbles. Bubbles are either absorbed or brought to surface by applying high-intensity Sonic field at resonant frequency. Sonic oscillation increases surface area of bubbles and causes them to dissipate.

Trauma care at rural level III trauma centers in a state trauma system.

PubMed

Helling, Thomas S

2007-02-01

Although much has been written about the benefits of trauma center care, most experiences are urban with large numbers of patients. Little is known about the smaller, rural trauma centers and how they function both independently and as part of a larger trauma system. The state of Missouri has designated three levels of trauma care. The cornerstone of rural trauma care is the state-designated Level III trauma center. These centers are required to have the presence of a trauma team and trauma surgeon but do not require orthopedic or neurosurgical coverage. The purpose of this retrospective study was to determine how Level III trauma centers compared with Level I and Level II centers in the Missouri trauma system and, secondly, how trauma surgeon experience at these centers might shape future educational efforts to optimize rural trauma care. During a 2-year period in 2002 and 2003, the state trauma registry was queried on all trauma admissions for centers in the trauma system. Demographics and patient care outcomes were assessed by level of designation. Trauma admissions to the Level III centers were examined for acuity, severity, and type of injury. The experiences with chest, abdominal, and neurologic trauma were examined in detail. A total of 24,392 patients from 26 trauma centers were examined, including all eight Level III centers. Acuity and severity of injuries were higher at Level I and II centers. A total of 2,910 patients were seen at the 8 Level III centers. Overall deaths were significantly lower at Level III centers (Level I, 4% versus Level II, 4% versus Level III, 2%, p < 0.001). Numbers of patients dying within 24 hours were no different among levels of trauma care (Level I, 37% versus Level II, 30% versus Level III, 32%). Among Level III centers 45 (1.5%) patients were admitted in shock, and 48 (2%) had a Glasgow Coma Scale score <9. Twenty-six patients had a surgical head injury (7 epidural, 19 subdural hematomas). Twenty-eight patients (1%) needed

Mesoporous hollow spheres from soap bubbling.

PubMed

Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

2012-02-01

The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites. Copyright © 2011 Elsevier Inc. All rights reserved.

Rotating bubble membrane radiator

DOEpatents

Webb, Brent J.; Coomes, Edmund P.

1988-12-06

A heat radiator useful for expelling waste heat from a power generating system aboard a space vehicle is disclosed. Liquid to be cooled is passed to the interior of a rotating bubble membrane radiator, where it is sprayed into the interior of the bubble. Liquid impacting upon the interior surface of the bubble is cooled and the heat radiated from the outer surface of the membrane. Cooled liquid is collected by the action of centrifical force about the equator of the rotating membrane and returned to the power system. Details regarding a complete space power system employing the radiator are given.

Orthopedic and trauma services in the healthcare system of Serbia.

PubMed

Vukasinović, Zoran; Zivković, Zorica; Spasovski, Dusko

2008-01-01

Our aim has been to present the functioning of orthopaedic and trauma services in the healthcare system of Serbia. In the introduction, we present geographic, demographic, political and economic elements, which define more closely the position of Serbia in the Southeastern Europe. Further, the healthcare system of Serbia, organized in four levels, is presented: self-care, primary healthcare, secondary healthcare and tertiary healthcare, as well as the schedule of 20,157 physicians engaged in healthcare. In addition, we point out numerous problems, which the system is faced with. Special attention is paid to orthopaedic and trauma services active within the system, its development, current condition and personnel education. We have concluded that, despite this being a middle-income country, the healthcare system is well developed. With 524 orthopaedic surgeons, working in 56 specialized departments, musculoskeletal diseases and trauma management are covered at all three healthcare levels. Nevertheless, the authors also underline weaknesses that are mostly of technical nature. Measures for their elimination and improvement of the entire service are also suggested.

Surfactants for Bubble Removal against Buoyancy

NASA Astrophysics Data System (ADS)

Raza, Md. Qaisar; Kumar, Nirbhay; Raj, Rishi

2016-01-01

The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications.

Surfactants for Bubble Removal against Buoyancy

PubMed Central

Raza, Md. Qaisar; Kumar, Nirbhay; Raj, Rishi

2016-01-01

The common phenomenon of buoyancy-induced vapor bubble lift-off from a heated surface is of importance to many areas of science and technology. In the absence of buoyancy in zero gravity of space, non-departing bubbles coalesce to form a big dry patch on the heated surface and heat transfer deteriorates despite the high latent heat of vaporization of water. The situation is worse on an inverted heater in earth gravity where both buoyancy and surface tension act upwards to oppose bubble removal. Here we report a robust passive technique which uses surfactants found in common soaps and detergents to avoid coalescence and remove bubbles downwards, away from an inverted heater. A force balance model is developed to demonstrate that the force of repulsion resulting from the interaction of surfactants adsorbed at the neighboring liquid-vapor interfaces of the thin liquid film contained between bubbles is strong enough to overcome buoyancy and surface tension. Bubble removal frequencies in excess of ten Hz resulted in more than twofold enhancement in heat transfer in comparison to pure water. We believe that this novel bubble removal mechanism opens up opportunities for designing boiling-based systems for space applications. PMID:26743179

Gas Diffusion in Fluids Containing Bubbles

NASA Technical Reports Server (NTRS)

Zak, M.; Weinberg, M. C.

1982-01-01

Mathematical model describes movement of gases in fluid containing many bubbles. Model makes it possible to predict growth and shrink age of bubbles as function of time. New model overcomes complexities involved in analysis of varying conditions by making two simplifying assumptions. It treats bubbles as point sources, and it employs approximate expression for gas concentration gradient at liquid/bubble interface. In particular, it is expected to help in developing processes for production of high-quality optical glasses in space.

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

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

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 multi-functional bubble-based microfluidic system

PubMed Central

Khoshmanesh, Khashayar; Almansouri, Abdullah; Albloushi, Hamad; Yi, Pyshar; Soffe, Rebecca; Kalantar-zadeh, Kourosh

2015-01-01

Recently, the bubble-based systems have offered a new paradigm in microfluidics. Gas bubbles are highly flexible, controllable and barely mix with liquids, and thus can be used for the creation of reconfigurable microfluidic systems. In this work, a hydrodynamically actuated bubble-based microfluidic system is introduced. This system enables the precise movement of air bubbles via axillary feeder channels to alter the geometry of the main channel and consequently the flow characteristics of the system. Mixing of neighbouring streams is demonstrated by oscillating the bubble at desired displacements and frequencies. Flow control is achieved by pushing the bubble to partially or fully close the main channel. Patterning of suspended particles is also demonstrated by creating a large bubble along the sidewalls. Rigorous analytical and numerical calculations are presented to describe the operation of the system. The examples presented in this paper highlight the versatility of the developed bubble-based actuator for a variety of applications; thus providing a vision that can be expanded for future highly reconfigurable microfluidics. PMID:25906043

The life and death of film bubbles

NASA Astrophysics Data System (ADS)

Poulain, S.; Villermaux, E.; Bourouiba, L.

2017-11-01

Following its burst, the fragmentation of a large bubble (film bubble) at the air-water interface can release hundreds of micrometer-sized film-drops in the air we breathe. This mechanism of droplet formation is one of the most prominent sources of sea spray. Indoor or outdoor, pathogens from contaminated water are transported by these droplets and have also been linked to respiratory infection. The lifetime and thickness of bubbles govern the number and size of the droplets they produce. Despite these important implications, little is known about the factors influencing the life and death of surface film bubbles. In particular, the fundamental physical mechanisms linking bubble aging, thinning, and lifetime remain poorly understood. To address this gap, we present the results of an extensive investigation of the aging of film-drop-producing bubbles in various ambient air, water composition, and temperature conditions. We present and validate a generalized physical picture and model of bubble cap thickness evolution. The model and physical picture are linked to the lifetime of bubbles via a series of cap rupture mechanisms of increasing efficiency.

Analysis of a deflating soap bubble

NASA Astrophysics Data System (ADS)

Jackson, David P.; Sleyman, Sarah

2010-10-01

A soap bubble on the end of a cylindrical tube is seen to deflate as the higher pressure air inside the bubble escapes through a tube. We perform an experiment to measure the radius of the slowly deflating bubble and observe that the radius decreases to a minimum before quickly increasing. This behavior reflects the fact that the bubble ends up as a flat surface over the end of the tube. A theoretical analysis reproduces this behavior and compares favorably with the experimental data.

Agitation, Mixing, and Transfers Induced by Bubbles

NASA Astrophysics Data System (ADS)

Risso, Frédéric

2018-01-01

Bubbly flows involve bubbles randomly distributed within a liquid. At large Reynolds number, they experience an agitation that can combine shear-induced turbulence (SIT), large-scale buoyancy-driven flows, and bubble-induced agitation (BIA). The properties of BIA strongly differ from those of SIT. They have been determined from studies of homogeneous swarms of rising bubbles. Regarding the bubbles, agitation is mainly caused by the wake-induced path instability. Regarding the liquid, two contributions must be distinguished. The first one corresponds to the anisotropic flow disturbances generated near the bubbles, principally in the vertical direction. The second one is the almost isotropic turbulence induced by the flow instability through a population of bubbles, which turns out to be the main cause of horizontal fluctuations. Both contributions generate a k-3 spectral subrange and exponential probability density functions. The subsequent issue will be to understand how BIA interacts with SIT.

Acute management and outcome of multiple trauma patients with pelvic disruptions

PubMed Central

2012-01-01

Introduction Data on prehospital and trauma-room fluid management of multiple trauma patients with pelvic disruptions are rarely reported. Present trauma algorithms recommend early hemorrhage control and massive fluid resuscitation. By matching the German Pelvic Injury Register (PIR) with the TraumaRegister DGU (TR) for the first time, we attempt to assess the initial fluid management for different Tile/OTA types of pelvic-ring fractures. Special attention was given to the patient's posttraumatic course, particularly intensive care unit (ICU) data and patient outcome. Methods A specific match code was applied to identify certain patients with pelvic disruptions from both PIR and TR anonymous trauma databases, admitted between 2004 and 2009. From the resulting intersection set, a retrospective analysis was done of prehospital and trauma-room data, length of ICU stay, days of ventilation, incidence of multiple organ dysfunction syndrome (MODS), sepsis, and mortality. Results In total, 402 patients were identified. Mean ISS was 25.9 points, and the mean of patients with ISS ≥16 was 85.6%. The fracture distribution was as follows: 19.7% type A, 29.4% type B, 36.6% type C, and 14.3% isolated acetabular and/or sacrum fractures. The type B/C, compared with type A fractures, were related to constantly worse vital signs that necessitated a higher volume of fluid and blood administration in the prehospital and/or the trauma-room setting. This group of B/C fractures were also related to a significantly higher presence of concomitant injuries and related to increased ISS. This was related to increased ventilation and ICU stay, increased rate of MODS, sepsis, and increased rate of mortality, at least for the type C fractures. Approximately 80% of the dead had sustained type B/C fractures. Conclusions The present study confirms the actuality of traditional trauma algorithms with initial massive fluid resuscitation in the recent therapy of multiple trauma patients with pelvic

Transient bubbles, bublets and breakup

NASA Astrophysics Data System (ADS)

Keen, Giles; Blake, John

1999-11-01

The non-spherical nature of the collapse of bubbles has important ramifications in many practical situations such as ultrasonic cleaning, tanning of leather, and underwater explosions. In particular the high speed liquid jet that can thread a collapsing bubble is central to the functional performance. An impressive photographic record of a liquid jet was obtained by Crum using a bubble situated in the vicinity of a platform oscillating vertically at a frequency of 60 Hz. A boundary integral method is used to model this situation and is found to closely mimic some of the observations. However, a slight variation of parameters or a change in the phase of the driving frequency can lead to dramatically different bubble behaviour, a feature also observed by Crum.

Electroweak bubble wall speed limit

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

Bödeker, Dietrich; Moore, Guy D., E-mail: bodeker@physik.uni-bielefeld.de, E-mail: guymoore@ikp.physik.tu-darmstadt.de

In extensions of the Standard Model with extra scalars, the electroweak phase transition can be very strong, and the bubble walls can be highly relativistic. We revisit our previous argument that electroweak bubble walls can 'run away,' that is, achieve extreme ultrarelativistic velocities γ ∼ 10{sup 14}. We show that, when particles cross the bubble wall, they can emit transition radiation. Wall-frame soft processes, though suppressed by a power of the coupling α, have a significance enhanced by the γ-factor of the wall, limiting wall velocities to γ ∼ 1/α. Though the bubble walls can move at almost the speedmore » of light, they carry an infinitesimal share of the plasma's energy.« less

Let Them Blow Bubbles.

ERIC Educational Resources Information Center

Korenic, Eileen

1988-01-01

Describes a series of activities and demonstrations involving the science of soap bubbles. Starts with a recipe for bubble solution and gives instructions for several activities on topics such as density, interference colors, optics, static electricity, and galaxy formation. Contains some background information to help explain some of the effects.…

MOBI: Microgravity Observations of Bubble Interactions

NASA Technical Reports Server (NTRS)

Koch, Donald L.; Sangani, Ashok

2004-01-01

One of the greatest uncertainties affecting the design of multiphase flow technologies for space exploration is the spatial distribution of phases that will arise in microgravity or reduced gravity. On Earth, buoyancy-driven motion predominates whereas the shearing of the bubble suspension controls its behavior in microgravity. We are conducting a series of ground-based experiments and a flight experiment spanning the full range of ratios of buoyancy to shear. These include: (1) bubbles rising in a quiescent liquid in a vertical channel; (2) weak shear flow induced by slightly inclining the channel; (3) moderate shear flow in a terrestrial vertical pipe flow; and (4) shearing of a bubble suspension in a cylindrical Couette cell in microgravity. We consider nearly monodisperse suspensions of 1 to 1.8 mm diameter bubbles in aqueous electrolyte solutions. The liquid velocity disturbance produced by bubbles in this size range can often be described using an inviscid analysis. Electrolytic solutions lead to hydrophilic repulsion forces that stabilize the bubble suspension without causing Marangoni stresses. We will discuss the mechanisms that control the flow behavior and phase distribution in the ground-based experiments and speculate on the factors that may influence the suspension flow and bubble volume fraction distribution in the flight experiment.

Average properties of bidisperse bubbly flows

NASA Astrophysics Data System (ADS)

Serrano-García, J. C.; Mendez-Díaz, S.; Zenit, R.

2018-03-01

Experiments were performed in a vertical channel to study the properties of a bubbly flow composed of two distinct bubble size species. Bubbles were produced using a capillary bank with tubes with two distinct inner diameters; the flow through each capillary size was controlled such that the amount of large or small bubbles could be controlled. Using water and water-glycerin mixtures, a wide range of Reynolds and Weber number ranges were investigated. The gas volume fraction ranged between 0.5% and 6%. The measurements of the mean bubble velocity of each species and the liquid velocity variance were obtained and contrasted with the monodisperse flows with equivalent gas volume fractions. We found that the bidispersity can induce a reduction of the mean bubble velocity of the large species; for the small size species, the bubble velocity can be increased, decreased, or remain unaffected depending of the flow conditions. The liquid velocity variance of the bidisperse flows is, in general, bound by the values of the small and large monodisperse values; interestingly, in some cases, the liquid velocity fluctuations can be larger than either monodisperse case. A simple model for the liquid agitation for bidisperse flows is proposed, with good agreement with the experimental measurements.

Influences of non-uniform pressure field outside bubbles on the propagation of acoustic waves in dilute bubbly liquids.

PubMed

Zhang, Yuning; Du, Xiaoze

2015-09-01

Predictions of the propagation of the acoustic waves in bubbly liquids is of great importance for bubble dynamics and related applications (e.g. sonochemistry, sonochemical reactor design, biomedical engineering). In the present paper, an approach for modeling the propagation of the acoustic waves in dilute bubbly liquids is proposed through considering the non-uniform pressure field outside the bubbles. This approach is validated through comparing with available experimental data in the literature. Comparing with the previous models, our approach mainly improves the predictions of the attenuation of acoustic waves in the regions with large kR0 (k is the wave number and R0 is the equilibrium bubble radius). Stability of the oscillating bubbles under acoustic excitation are also quantitatively discussed based on the analytical solution. Copyright © 2015 Elsevier B.V. All rights reserved.

Bifurcation scenarios for bubbling transition.

PubMed

Zimin, Aleksey V; Hunt, Brian R; Ott, Edward

2003-01-01

Dynamical systems with chaos on an invariant submanifold can exhibit a type of behavior called bubbling, whereby a small random or fixed perturbation to the system induces intermittent bursting. The bifurcation to bubbling occurs when a periodic orbit embedded in the chaotic attractor in the invariant manifold becomes unstable to perturbations transverse to the invariant manifold. Generically the periodic orbit can become transversely unstable through a pitchfork, transcritical, period-doubling, or Hopf bifurcation. In this paper a unified treatment of the four types of bubbling bifurcation is presented. Conditions are obtained determining whether the transition to bubbling is soft or hard; that is, whether the maximum burst amplitude varies continuously or discontinuously with variation of the parameter through its critical value. For soft bubbling transitions, the scaling of the maximum burst amplitude with the parameter is derived. For both hard and soft transitions the scaling of the average interburst time with the bifurcation parameter is deduced. Both random (noise) and fixed (mismatch) perturbations are considered. Results of numerical experiments testing our theoretical predictions are presented.

The Minnaert bubble: an acoustic approach

NASA Astrophysics Data System (ADS)

Devaud, Martin; Hocquet, Thierry; Bacri, Jean-Claude; Leroy, Valentin

2008-11-01

We propose an ab initio introduction to the well-known Minnaert pulsating bubble at graduate level. After a brief recall of the standard stuff, we begin with a detailed discussion of the radial movements of an air bubble in water. This discussion is managed from an acoustic point of view, and using the Lagrangian rather than the Eulerian variables. In unbounded water, the air-water system has a continuum of eigenmodes, some of them correspond to regular Fabry-Pérot resonances. A singular resonance, the lowest one, is shown to coincide with that of Minnaert. In bounded water, the eigenmodes spectrum is discrete, with a finite fundamental frequency. A spectacular quasi-locking of the latter occurs if it happens to exceed the Minnaert frequency, which provides an unforeseen one-bubble alternative version of the famous 'hot chocolate effect'. In the (low) frequency domain in which sound propagation inside the bubble reduces to a simple 'breathing' (i.e. inflation/deflation), the light air bubble can be 'dressed' by the outer water pressure forces, and is turned into the heavy Minnaert bubble. Thanks to this unexpected renormalization process, we demonstrate that the Minnaert bubble definitely behaves like a true harmonic oscillator of the spring-bob type, but with a damping term and a forcing term in apparent disagreement with those commonly admitted in the literature. Finally, we underline the double role played by the water. In order to tell the water motion associated with water compressibility (i.e. the sound) from the simple incompressible accompaniment of the bubble breathing, we introduce a new picture analogous to the electromagnetic radiative picture in Coulomb gauge, which naturally leads us to split the water displacement in an instantaneous and a retarded part. The Minnaert renormalized mass of the dressed bubble is then automatically recovered.

Gas Bubble Dynamics under Mechanical Vibrations

NASA Astrophysics Data System (ADS)

Mohagheghian, Shahrouz; Elbing, Brian

2017-11-01

The scientific community has a limited understanding of the bubble dynamics under mechanical oscillations due to over simplification of Navier-Stockes equation by neglecting the shear stress tensor and not accounting for body forces when calculating the acoustic radiation force. The current work experimental investigates bubble dynamics under mechanical vibration and resulting acoustic field by measuring the bubble size and velocity using high-speed imaging. The experimental setup consists of a custom-designed shaker table, cast acrylic bubble column, compressed air injection manifold and an optical imaging system. The mechanical vibrations resulted in accelerations between 0.25 to 10 times gravitational acceleration corresponding to frequency and amplitude range of 8 - 22Hz and 1 - 10mm respectively. Throughout testing the void fraction was limited to <5%. The bubble size is larger than resonance size and smaller than acoustic wavelength. The amplitude of acoustic pressure wave was estimated using the definition of Bjerknes force in combination with Rayleigh-Plesset equation. Physical behavior of the system was capture and classified. Bubble size, velocity as well as size and spatial distribution will be presented.

Fearless versus fearful speculative financial bubbles

NASA Astrophysics Data System (ADS)

Andersen, J. V.; Sornette, D.

2004-06-01

Using a recently introduced rational expectation model of bubbles, based on the interplay between stochasticity and positive feedbacks of prices on returns and volatility, we develop a new methodology to test how this model classifies nine time series that have been previously considered as bubbles ending in crashes. The model predicts the existence of two anomalous behaviors occurring simultaneously: (i) super-exponential price growth and (ii) volatility growth, that we refer to as the “fearful singular bubble” regime. Out of the nine time series, we find that five pass our tests and can be characterized as “fearful singular bubbles”. The four other cases are the information technology Nasdaq bubble and three bubbles of the Hang Seng index ending in crashes in 1987, 1994 and 1997. According to our analysis, these four bubbles have developed with essentially no significant increase of their volatility. This paper thus proposes that speculative bubbles ending in crashes form two groups hitherto unrecognized, namely those accompanied by increasing volatility (reflecting increasing risk perception) and those without change of volatility (reflecting an absence of risk perception).

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.

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.

A modern combat trauma.

PubMed

Popivanov, Georgi; Mutafchiyski, V M; Belokonski, E I; Parashkevov, A B; Koutin, G L

2014-03-01

The world remains plagued by wars and terrorist attacks, and improvised explosive devices (IED) are the main weapons of our current enemies, causing almost two-thirds of all combat injuries. We wished to analyse the pattern of blast trauma on the modern battlefield and to compare it with combat gunshot injuries. Analysis of a consecutive series of combat trauma patients presenting to two Bulgarian combat surgical teams in Afghanistan over 11 months. Demographics, injury patterns and Injury Severity Scores (ISS) were compared between blast and gunshot-injured casualties using Fisher's Exact Test. The blast victims had significantly higher median ISS (20.54 vs 9.23) and higher proportion of ISS>16 (60% vs 33.92%, p=0.008) than gunshot cases. They also had more frequent involvement of three or more body regions (47.22% vs 3.58%, p<0.0001). A significantly higher frequency of head (27.27% vs 3.57%), facial (20% vs 0%) and extremities injuries (85.45% vs 42.86%) and burns (12.72% vs 0%) was noted among the victims of explosion (p<0.0001). Based on clinical examination and diagnostic imaging, primary blast injury was identified in 24/55 (43.6%), secondary blast injury in 37 blast cases (67.3%), tertiary in 15 (27.3%) and quaternary blast injury (all burns) in seven (12.72%). Our results corroborate the 'multidimensional' injury pattern of blast trauma. The complexity of the blast trauma demands a good knowledge and a special training of the military surgeons and hospital personnel before deployment.

Robust acoustic wave manipulation of bubbly liquids

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

Gumerov, N. A., E-mail: gumerov@umiacs.umd.edu; Center for Micro- and Nanoscale Dynamics of Dispersed Systems, Bashkir State University, Ufa 450076; Akhatov, I. S.

Experiments with water–air bubbly liquids when exposed to acoustic fields of frequency ∼100 kHz and intensity below the cavitation threshold demonstrate that bubbles ∼30 μm in diameter can be “pushed” away from acoustic sources by acoustic radiation independently from the direction of gravity. This manifests formation and propagation of acoustically induced transparency waves (waves of the bubble volume fraction). In fact, this is a collective effect of bubbles, which can be described by a mathematical model of bubble self-organization in acoustic fields that matches well with our experiments.

Hubble's Cosmic Bubbles

NASA Image and Video Library

2017-12-08

This entrancing image shows a few of the tenuous threads that comprise Sh2-308, a faint and wispy shell of gas located 5,200 light-years away in the constellation of Canis Major (The Great Dog). Sh2-308 is a large bubble-like structure wrapped around an extremely large, bright type of star known as a Wolf-Rayet Star — this particular star is called EZ Canis Majoris. These type of stars are among the brightest and most massive stars in the Universe, tens of times more massive than our own sun, and they represent the extremes of stellar evolution. Thick winds continually poured off the progenitors of such stars, flooding their surroundings and draining the outer layers of the Wolf-Rayet stars. The fast wind of a Wolf-Rayet star therefore sweeps up the surrounding material to form bubbles of gas. EZ Canis Majoris is responsible for creating the bubble of Sh2-308 — the star threw off its outer layers to create the strands visible here. The intense and ongoing radiation from the star pushes the bubble out farther and farther, blowing it bigger and bigger. Currently the edges of Sh2-308 are some 60 light-years apart! Beautiful as these cosmic bubbles are, they are fleeting. The same stars that form them will also cause their death, eclipsing and subsuming them in violent supernova explosions. Credit: ESA/Hubble & NASA NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Bubbly Little Star

NASA Technical Reports Server (NTRS)

2007-01-01

In this processed Spitzer Space Telescope image, baby star HH 46/47 can be seen blowing two massive 'bubbles.' The star is 1,140 light-years away from Earth.

The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are formed by starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. The red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

Whenever astronomers observe a star, or snap a stellar portrait, through the lens of any telescope, they know that what they are seeing is slightly blurred. To clear up the blurring in Spitzer images, astronomers at the Jet Propulsion Laboratory developed an image processing technique for Spitzer called Hi-Res deconvolution.

This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When scientists applied this image processing technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

Bernoulli Suction Effect on Soap Bubble Blowing?

NASA Astrophysics Data System (ADS)

Davidson, John; Ryu, Sangjin

2015-11-01

As a model system for thin-film bubble with two gas-liquid interfaces, we experimentally investigated the pinch-off of soap bubble blowing. Using the lab-built bubble blower and high-speed videography, we have found that the scaling law exponent of soap bubble pinch-off is 2/3, which is similar to that of soap film bridge. Because air flowed through the decreasing neck of soap film tube, we studied possible Bernoulli suction effect on soap bubble pinch-off by evaluating the Reynolds number of airflow. Image processing was utilized to calculate approximate volume of growing soap film tube and the volume flow rate of the airflow, and the Reynolds number was estimated to be 800-3200. This result suggests that soap bubbling may involve the Bernoulli suction effect.

Further experimentation on bubble generation during transformer overload

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

Oommen, T.V.

1992-03-01

This report covers additional work done during 1990 and 1991 on gas bubble generation under overload conditions. To improve visual bubble detection, a single disc coil was used. To further improve detection, a corona device was also used which signaled the onset of corona activity in the early stages of bubble formation. A total of fourteen model tests were conducted, half of which used the Inertaire system, and the remaining, a conservator (COPS). Moisture content of paper in the coil varied from 1.0% to 8.0%; gas (nitrogen) content varied from 1.0% to 8.8%. The results confirmed earlier observations that themore » mathematical bubble prediction model was not valid for high gas content model with relatively low moisture levels in the coil. An empirical relationship was formulated to accurately predict bubble evolution temperatures from known moisture and gas content values. For low moisture content models (below 2%), the simple Piper relationship was sufficient to predict bubble evolution temperatures, regardless of gas content. Moisture in the coil appears to be the key factor in bubble generation. Gas blanketed (Inertaire) systems do not appear to be prone to premature bubble generation from overloads as previously thought. The new bubble prediction model reveals that for a coil with 2% moisture, the bubble evolution temperature would be about 140{degrees}C. Since old transformers in service may have as much as 2% moisture in paper, the 140{degrees}C bubble evolution temperature may be taken as the lower limit of bubble evolution temperature under overload conditions for operating transformers. Drier insulation would raise the bubble evolution temperature.« less

Radionuclide evaluation of lung trauma

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

Lull, R.J.; Tatum, J.L.; Sugerman, H.J.

1983-07-01

Nuclear medicine imaging procedures can play a significant role in evaluating the pulmonary complications that are seen in trauma patients. A quantitative method for measuring increased pulmonary capillary permeability that uses Tc-99m HSA allows early diagnosis of acute respiratory distress syndrome (ARDS) and accurately differentiates this condition from pneumonia or cardiogenic pulmonary edema. This technique may be of great value in following the response to therapy. The use of 133Xe to diagnose inhalation injury remains an important diagnostic tool, particularly at hospitals with specialized burn units. Regional decreases in ventilation-perfusion images reliably localize aspirated foreign bodies. Radionuclide techniques that aremore » used to demonstrate gastropulmonary aspiration remain controversial and require further clinical evaluation. Pulmonary perfusion imaging, although nonspecific, may provide the earliest clue for correct diagnosis of fat embolism, air embolism, contusion, or laceration. Furthermore, the possibility of perfusion abnormality due to these uncommon conditions must be remembered whenever trauma patients are evaluated for pulmonary thromboembolism with scintigraphy. Occasionally, liver or spleen scintigraphy may be the most appropriate procedure when penetrating chest trauma also involves these subdiaphragmatic organs.« less

Bubble Dynamics in Polymer Solutions Undergoing Shear.

DTIC Science & Technology

1985-04-01

cavitation bubble in water has been established as the fundamental theoretical approach to understanding this phenomenon. LA_ Laser -induced...cavitation inception. 1-2 Polymer effects on cavity appearance. 2-1 Spherical laser -induced bubble dynamics. 2-2 Vapor cavity jet formation. 2-3 Bubble...distilled water. 2-6B Nonspherical bubble dynamics in dilute polymer. 3-1 Closed-loop hydraulic cavitation tunnel. 3-2 Laser system optical components. 3-3

Evaporation, Boiling and Bubbles

ERIC Educational Resources Information Center

Goodwin, Alan

2012-01-01

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

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.

Bubbles, Gating, and Anesthetics in Ion Channels

PubMed Central

Roth, Roland; Gillespie, Dirk; Nonner, Wolfgang; Eisenberg, Robert E.

2008-01-01

We suggest that bubbles are the bistable hydrophobic gates responsible for the on-off transitions of single channel currents. In this view, many types of channels gate by the same physical mechanism—dewetting by capillary evaporation—but different types of channels use different sensors to modulate hydrophobic properties of the channel wall and thereby trigger and control bubbles and gating. Spontaneous emptying of channels has been seen in many simulations. Because of the physics involved, such phase transitions are inherently sensitive, unstable threshold phenomena that are difficult to simulate reproducibly and thus convincingly. We present a thermodynamic analysis of a bubble gate using morphometric density functional theory of classical (not quantum) mechanics. Thermodynamic analysis of phase transitions is generally more reproducible and less sensitive to details than simulations. Anesthetic actions of inert gases—and their interactions with hydrostatic pressure (e.g., nitrogen narcosis)—can be easily understood by actions on bubbles. A general theory of gas anesthesia may involve bubbles in channels. Only experiments can show whether, or when, or which channels actually use bubbles as hydrophobic gates: direct observation of bubbles in channels is needed. Existing experiments show thin gas layers on hydrophobic surfaces in water and suggest that bubbles nearly exist in bulk water. PMID:18234836

Gravity Wave Seeding of Equatorial Plasma Bubbles

NASA Technical Reports Server (NTRS)

Singh, Sardul; Johnson, F. S.; Power, R. A.

1997-01-01

Some examples from the Atmosphere Explorer E data showing plasma bubble development from wavy ion density structures in the bottomside F layer are described. The wavy structures mostly had east-west wavelengths of 150-800 km, in one example it was about 3000 km. The ionization troughs in the wavy structures later broke up into either a multiple-bubble patch or a single bubble, depending upon whether, in the precursor wavy structure, shorter wavelengths were superimposed on the larger scale wavelengths. In the multiple bubble patches, intrabubble spacings vaned from 55 km to 140 km. In a fully developed equatorial spread F case, east-west wavelengths from 690 km down to about 0.5 km were present simultaneously. The spacings between bubble patches or between bubbles in a patch appear to be determined by the wavelengths present in the precursor wave structure. In some cases, deeper bubbles developed on the western edge of a bubble patch, suggesting an east-west asymmetry. Simultaneous horizontal neutral wind measurements showed wavelike perturbations that were closely associated with perturbations in the plasma horizontal drift velocity. We argue that the wave structures observed here that served as the initial seed ion density perturbations were caused by gravity waves, strengthening the view that gravity waves seed equatorial spread F irregularities.

Steady State Vapor Bubble in Pool Boiling

PubMed Central

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

2016-01-01

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

Trauma care in German-speaking countries: have changes in the curricula led to changes in practice after 10 years?

PubMed

Kuhn-Régnier, Sarah; Stickel, Michael; Link, Björn-Christian; Fischer, Henning; Babst, Reto; Beeres, Frank J P

2018-01-06

Traditionally, in the German-speaking countries, trauma patients are treated by general surgeons specialized in trauma surgery known as the Unfallchirurg. Over the last decade, a trend towards a lower influence of surgeons and a higher influence of subspecialties in the emergency department has been noted. With additional transformations in the health care system towards highly specialized medicine and the arising of new (sub-) specialties, diversification in the management of the trauma patient appears to occur. The new curricula for surgical disciplines providing trauma care will widen this issue even further, moreover, triggered by the Anglo-American medical model. The primary aim of this study was to evaluate the current situation in German-speaking countries concerning the management of trauma patients. The interfaces between emergency physicians, orthopaedic and general surgeons have been investigated concerning the management of the trauma patients. Additionally, different future scenarios have been evaluated. An online questionnaire was submitted to members of the German Society of Trauma and Orthopaedic Surgery [Deutsche Gesellschaft für Orthopädie und Unfallchirurgie (DGOU)], including both general and orthopaedic surgeons, emergency physicians and also some members from Austria, the Netherlands and Switzerland. Questions dealt with demographic data, the current situation in the clinic of the responders in terms of management of mono- and polytrauma patients as well as fracture care. In addition, various future scenarios were evaluated. 293 members of the DGOU answered the questionnaire. The majority of the responders (45%) were orthopaedic surgeons and 34% were general trauma surgeons. Sixty-two per cent of hospitals run their emergency departments with emergency physicians. Treatment of both mono- and polytrauma patients in the emergency department is equally distributed between general and orthopaedic surgeons. Fracture care, however, is

Cartilage formation in the CELLS 'double bubble' hardware

NASA Technical Reports Server (NTRS)

Duke, P. J.; Arizpe, Jorge; Montufar-Solis, Dina

1991-01-01

The CELLS experiment scheduled to be flown on the first International Microgravity Laboratory is designed to study the effect of microgravity on the cartilage formation, by measuring parameters of growth in a differentiating cartilage cell culture. This paper investigates the conditions for this experiment by studying cartilage differentiation in the 'bubble exchange' hardware with the 'double bubble' design in which the bubbles are joined by a flange which also overlays the gasket. Four types of double bubbles (or double gas permeable membranes) were tested: injection-molded bubbles 0.01- and 0.005-in. thick, and compression molded bubbles 0.015- and 0.01-in. thick. It was found that double bubble membranes of 0.005- and 0.010-in. thickness supported cartilage differentiation, while the 0.015-in. bubbles did not. It was also found that nodule count, used in this study as a parameter, is not the best measure of the amount of cartilage differentiation.

Microstreaming from Sessile Semicylindrical Bubbles

NASA Astrophysics Data System (ADS)

Hilgenfeldt, Sascha; Rallabandi, Bhargav; Guo, Lin; Wang, Cheng

2014-03-01

Powerful steady streaming flows result from the ultrasonic driving of microbubbles, in particular when these bubbles have semicylindrical cross section and are positioned in contact with a microfluidic channel wall. We have used this streaming in experiment to develop novel methods for trapping and sorting of microparticles by size, as well as for micromixing. Theoretically, we arrive at an analytical description of the streaming flow field through an asymptotic computation that, for the first time, reconciles the boundary layers around the bubble and along the substrate wall, and also takes into account the oscillation modes of the bubble. This approach gives insight into changes in the streaming pattern with bubble size and driving frequency, including a reversal of the flow direction at high frequencies with potentially useful applications. Present address: Mechanical and Aerospace Engineering, Missouri S &T.

Numerical simulation of high Reynolds number bubble motion

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

McLaughlin, J.B.

This paper presents the results of numerical simulations of bubble motion. All the results are for single bubbles in unbounded fluids. The liquid phase is quiescent except for the motion created by the bubble, which is axisymmetric. The main focus of the paper is on bubbles that are of order 1 mm in diameter in water. Of particular interest is the effect of surfactant molecules on bubble motion. Results for the {open_quotes}insoluble surfactant{close_quotes} model will be presented. These results extend research by other investigators to finite Reynolds numbers. The results indicate that, by assuming complete coverage of the bubble surface,more » one obtains good agreement with experimental observations of bubble motion in tap water. The effect of surfactant concentration on the separation angle is discussed.« less

Ring Bubbles of Dolphins

NASA Technical Reports Server (NTRS)

Shariff, Karim; Marten, Ken; Psarakos, Suchi; White, Don J.; Merriam, Marshal (Technical Monitor)

1996-01-01

The article discusses how dolphins create and play with three types of air-filled vortices. The underlying physics is discussed. Photographs and sketches illustrating the dolphin's actions and physics are presented. The dolphins engage in this behavior on their own initiative without food reward. These behaviors are done repeatedly and with singleminded effort. The first type is the ejection of bubbles which, after some practice on the part of the dolphin, turn into toroidal vortex ring bubbles by the mechanism of baroclinic torque. These bubbles grow in radius and become thinner as they rise vertically to the surface. One dolphin would blow two in succession and guide them to fuse into one. Physicists call this a vortex reconnection. In the second type, the dolphins first create an invisible vortex ring in the water by swimming on their side and waving their tail fin (also called flukes) vigorously. This vortex ring travels horizontally in the water. The dolphin then turns around, finds the vortex and injects a stream of air into it from its blowhole. The air "fills-out" the core of the vortex ring. Often, the dolphin would knock-off a smaller ring bubble from the larger ring (this also involves vortex reconnection) and steer the smaller ring around the tank. One other dolphin employed a few other techniques for planting air into the fluke vortex. One technique included standing vertically in the water with tail-up, head-down and tail piercing the free surface. As the fluke is waved to create the vortex ring, air is entrained from above the surface. Another technique was gulping air in the mouth, diving down, releasing air bubbles from the mouth and curling them into a ring when they rose to the level of the fluke. In the third type, demonstrated by only one dolphin, the longitudinal vortex created by the dorsal fin on the back is used to produce 10-15 foot long helical bubbles. In one technique she swims in a curved path. This creates a dorsal fin vortex since

Brief Trauma and Mental Health Assessments for Female Offenders in Addiction Treatment

PubMed Central

Rowan-Szal, Grace A.; Joe, George W.; Bartholomew, Norma G; Pankow, Jennifer; Simpson, D. Dwayne

2012-01-01

Increasing numbers of women in prison raise concerns about gender-specific problems and needs severity. Female offenders report higher trauma as well as mental and medical health complications than males, but large inmate populations and limited resources create challenges in administering proper diagnostic screening and assessments. This study focuses on brief instruments that address specialized trauma and health problems, along with related psychosocial functioning. Women from two prison-based treatment programs for substance abuse were assessed (N = 1,397), including one facility for special needs and one for regular female offenders. Results affirmed that admissions to the special needs facility reported more posttraumatic stress symptoms, higher rates of psychological stress and previous hospitalizations, and more health issues than those in the regular treatment facility. Findings supporting use of these short forms and their applications as tools for monitoring needs, progress, and change over time are discussed. PMID:23087587

Bubble Divergences: Sorting out Topology from Cell Structure

NASA Astrophysics Data System (ADS)

Bonzom, Valentin; Smerlak, Matteo

2012-02-01

We conclude our analysis of bubble divergences in the flat spinfoam model. In [arXiv:1008.1476] we showed that the divergence degree of an arbitrary two-complex Gamma can be evaluated exactly by means of twisted cohomology. Here, we specialize this result to the case where Gamma is the two-skeleton of the cell decomposition of a pseudomanifold, and sharpen it with a careful analysis of the cellular and topological structures involved. Moreover, we explain in detail how this approach reproduces all the previous powercounting results for the Boulatov-Ooguri (colored) tensor models, and sheds light on algebraic-topological aspects of Gurau's 1/N expansion.

Remobilizing the Interface of Thermocapillary Driven Bubbles Retarded By the Adsorption of a Surfactant Impurity on the Bubble Surface

NASA Technical Reports Server (NTRS)

Palaparthi, Ravi; Maldarelli, Charles; Papageorgiou, Dimitri; Singh, Bhim (Technical Monitor)

2001-01-01

Thermocapillary migration is a method for moving bubbles in space in the absence of buoyancy. A temperature gradient is the continuous phase in which a bubble is situated, and the applied gradient impressed on the bubble surface causes one pole of the drop to be cooler than the opposite pole. As the surface tension is a decreasing function of temperature, the cooler pole pulls at the warmer pole, creating a flow that propels the bubble in the direction of the warmer fluid. A major impediment to the practical use of thermocapillary to direct the movement of bubbles in space is the fact that surfactant impurities, which are unavoidably present in the continuous phase, can significantly reduce the migration velocity. A surfactant impurity adsorbed onto the bubble interface is swept to the trailing end of the bubble. When bulk concentrations are low (which is the case with an impurity), diffusion of surfactant to the front end is slow relative to convection, and surfactant collects at the back end of the bubble. Collection at the back lowers the surface tension relative to the front end setting up a reverse tension gradient. (This can also be the case if kinetic desorption of surfactant at the back end of the bubble is much slower than convection.) For buoyancy driven bubble motions in the absence of a thermocapillarity, the tension gradient opposes the surface flow, and reduces the surface and terminal velocities (the interface becomes more solid-like and bubbles translate as solid particles). When thermocapillary forces are present, the reverse tension gradient set up by the surfactant accumulation reduces the temperature-induced tension gradient, and can decrease to near zero the bubble's thermocapillary velocity. The objective of our research is to develop a method for enhancing the thermocapillary migration of bubbles which have be retarded by the adsorption onto the bubble surface of a surfactant impurity. Our remobilization theory proposes to use surfactant

Formation of soap bubbles by gas jet

NASA Astrophysics Data System (ADS)

Zhou, Maolei; Li, Min; Chen, Zhiyuan; Han, Jifeng; Liu, Dong

2017-12-01

Soap bubbles can be easily generated by various methods, while their formation process is complicated and still worth studying. A model about the bubble formation process was proposed in the study by Salkin et al. [Phys. Rev. Lett. 116, 077801 (2016)] recently, and it was reported that the bubbles were formed when the gas blowing velocity was above one threshold. However, after a detailed study of these experiments, we found that the bubbles could be generated in two velocity ranges which corresponded to the laminar and turbulent gas jet, respectively, and the predicted threshold was only effective for turbulent gas flow. The study revealed that the bubble formation was greatly influenced by the aerodynamics of the gas jet blowing to the film, and these results will help to further understand the formation mechanism of the soap bubble as well as the interaction between the gas jet and the thin liquid film.

MAGNETIC TOPOLOGY OF BUBBLES IN QUIESCENT PROMINENCES

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

Dudik, J.; Aulanier, G.; Schmieder, B.

We study a polar-crown prominence with a bubble and its plume observed in several coronal filters by the SDO/AIA and in H{alpha} by the MSDP spectrograph in Bialkow (Poland) to address the following questions: what is the brightness of prominence bubbles in EUV with respect to the corona outside of the prominence and the prominence coronal cavity? What is the geometry and topology of the magnetic field in the bubble? What is the nature of the vertical threads seen within prominences? We find that the brightness of the bubble and plume is lower than the brightness of the corona outsidemore » of the prominence, and is similar to that of the coronal cavity. We constructed linear force-free models of prominences with bubbles, where the flux rope is perturbed by inclusion of parasitic bipoles. The arcade field lines of the bipole create the bubble, which is thus devoid of magnetic dips. Shearing the bipole or adding a second one can lead to cusp-shaped prominences with bubbles similar to the observed ones. The bubbles have complex magnetic topology, with a pair of coronal magnetic null points linked by a separator outlining the boundary between the bubble and the prominence body. We conjecture that plume formation involves magnetic reconnection at the separator. Depending on the viewing angle, the prominence can appear either anvil-shaped with predominantly horizontal structures, or cusp-shaped with predominantly vertical structuring. The latter is an artifact of the alignment of magnetic dips with respect to the prominence axis and the line of sight.« 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.

Analysis of cavitation bubble dynamics in a liquid

NASA Technical Reports Server (NTRS)

Fontenot, L. L.; Lee, Y. C.

1971-01-01

General differential equations governing the dynamics of the cavitation bubbles in a liquid were derived. With the assumption of spherical symmetry the governing equations were simplified. Closed form solutions were obtained for simple cases, and numerical solutions were calculated for complicated ones. The growth and the collapse of the bubble were analyzed, oscillations of the bubbles were studied, and the stability of the cavitation bubbles were investigated. The results show that the cavitation bubbles are unstable, and the oscillation is not sinusoidal.

Simple improvements to classical bubble nucleation models.

PubMed

Tanaka, Kyoko K; Tanaka, Hidekazu; Angélil, Raymond; Diemand, Jürg

2015-08-01

We revisit classical nucleation theory (CNT) for the homogeneous bubble nucleation rate and improve the classical formula using a correct prefactor in the nucleation rate. Most of the previous theoretical studies have used the constant prefactor determined by the bubble growth due to the evaporation process from the bubble surface. However, the growth of bubbles is also regulated by the thermal conduction, the viscosity, and the inertia of liquid motion. These effects can decrease the prefactor significantly, especially when the liquid pressure is much smaller than the equilibrium one. The deviation in the nucleation rate between the improved formula and the CNT can be as large as several orders of magnitude. Our improved, accurate prefactor and recent advances in molecular dynamics simulations and laboratory experiments for argon bubble nucleation enable us to precisely constrain the free energy barrier for bubble nucleation. Assuming the correction to the CNT free energy is of the functional form suggested by Tolman, the precise evaluations of the free energy barriers suggest the Tolman length is ≃0.3σ independently of the temperature for argon bubble nucleation, where σ is the unit length of the Lennard-Jones potential. With this Tolman correction and our prefactor one gets accurate bubble nucleation rate predictions in the parameter range probed by current experiments and molecular dynamics simulations.

Bubble breakup phenomena in a venturi tube

NASA Astrophysics Data System (ADS)

Fujiwara, Akiko

2005-11-01

Microbubble has distinguished characteristics of large surface area to unit volume and small buoyancy, and it has advantages in many engineering fields. Recently microbubble generators with low energy and high performance are required to wide applications. In the present study, we propose one new effective technique to generate tiny bubbles with less than 200 μm diameter utilizing venturi tube under high void fraction condition. The objective of the present study is to elucidate the mechanism of bubble breakup phenomena in the venturi tube and to clarify the effects of parameters which are necessary to realize an optimum system experimentally. Experiment was conducted with void fraction of 4% and variation of liquid velocity from 9 to 26 m/s at the throat. Under low velocity condition, bubbles which were observed with a high speed camera parted gradually in a wide region. On the contrary under high velocity condition, bubbles expanded after passing through the throat and shrank rapidly. Since the speed of sound in gas-liquid system is extremely lower than that of single-phase flow, the bubble breakup phenomenon in the venturi tube is explained as the supersonic flow in a Laval nozzle. By rapid pressure recovery in diverging area, expanding bubbles collapse violently. The tiny bubbles are generated due to the surface instability of shrinking bubbles.

Comparison of cavitation bubbles evolution in viscous media

NASA Astrophysics Data System (ADS)

Jasikova, Darina; Schovanec, Petr; Kotek, Michal; Kopecky, Vaclav

2018-06-01

There have been tried many types of liquids with different ranges of viscosity values that have been tested to form a single cavitation bubble. The purpose of these experiments was to observe the behaviour of cavitation bubbles in media with different ranges of absorbance. The most of the method was based on spark to induced superheat limit of liquid. Here we used arrangement of the laser-induced breakdown (LIB) method. There were described the set cavitation setting that affects the size bubble in media with different absorbance. We visualized the cavitation bubble with a 60 kHz high speed camera. We used here shadowgraphy setup for the bubble visualization. There were observed time development and bubble extinction in various media, where the size of the bubble in the silicone oil was extremely small, due to the absorbance size of silicon oil.

Breathing, bubbling, and bending: DNA flexibility from multimicrosecond simulations.

PubMed

Zeida, Ari; Machado, Matías Rodrigo; Dans, Pablo Daniel; Pantano, Sergio

2012-08-01

Bending of the seemingly stiff DNA double helix is a fundamental physical process for any living organism. Specialized proteins recognize DNA inducing and stabilizing sharp curvatures of the double helix. However, experimental evidence suggests a high protein-independent flexibility of DNA. On the basis of coarse-grained simulations, we propose that DNA experiences thermally induced kinks associated with the spontaneous formation of internal bubbles. Comparison of the protein-induced DNA curvature calculated from the Protein Data Bank with that sampled by our simulations suggests that thermally induced distortions can account for ~80% of the DNA curvature present in experimentally solved structures.

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.

Bubble nucleation in stout beers

NASA Astrophysics Data System (ADS)

Lee, W. T.; McKechnie, J. S.; Devereux, M. G.

2011-05-01

Bubble nucleation in weakly supersaturated solutions of carbon dioxide—such as champagne, sparkling wines, and carbonated beers—is well understood. Bubbles grow and detach from nucleation sites: gas pockets trapped within hollow cellulose fibers. This mechanism appears not to be active in stout beers that are supersaturated solutions of nitrogen and carbon dioxide. In their canned forms these beers require additional technology (widgets) to release the bubbles which will form the head of the beer. We extend the mathematical model of bubble nucleation in carbonated liquids to the case of two gases and show that this nucleation mechanism is active in stout beers, though substantially slower than in carbonated beers and confirm this by observation. A rough calculation suggests that despite the slowness of the process, applying a coating of hollow porous fibers to the inside of a can or bottle could be a potential replacement for widgets.

Using an Ultrasonic Instrument to Size Extravascular Bubbles

NASA Technical Reports Server (NTRS)

Magari, Patrick J.; Kline-Schroder, J.; Kenton, Marc A.

2004-01-01

In an ongoing development project, microscopic bubbles in extravascular tissue in a human body will be detected by use of an enhanced version of the apparatus described in Ultrasonic Bubble- Sizing Instrument (MSC-22980), NASA Tech Briefs, Vol. 24, No. 10 (October 2000), page 62. To recapitulate: The physical basis of the instrument is the use of ultrasound to excite and measure the resonant behavior (oscillatory expansion and contraction) of bubbles. The resonant behavior is a function of the bubble diameter; the instrument exploits the diameter dependence of the resonance frequency and the general nonlinearity of the ultrasonic response of bubbles to detect bubbles and potentially measure their diameters. In the cited prior article, the application given most prominent mention was the measurement of gaseous emboli (essentially, gas bubbles in blood vessels) that cause decompression sickness and complications associated with cardiopulmonary surgery. According to the present proposal, the instrument capabilities would be extended to measure extravascular bubbles with diameters in the approximate range of 1 to 30 m. The proposed use of the instrument could contribute further to the understanding and prevention of decompression sickness: There is evidence that suggests that prebreathing oxygen greatly reduces the risk of decompression sickness by reducing the number of microscopic extravascular bubbles. By using the ultrasonic bubble-sizing instrument to detect and/or measure the sizes of such bubbles, it might be possible to predict the risk of decompression sickness. The instrument also has potential as a tool to guide the oxygen-prebreathing schedules of astronauts; high-altitude aviators; individuals who undertake high-altitude, low-opening (HALO) parachute jumps; and others at risk of decompression sickness. For example, an individual at serious risk of decompression sickness because of high concentrations of extravascular microscopic bubbles could be given a

From Rising Bubble to RNA/DNA and Bacteria

NASA Astrophysics Data System (ADS)

Marks, Roman; Cieszyńska, Agata; Wereszka, Marzena; Borkowski, Wojciech

2017-04-01

In this study we have focused on the movement of rising bubbles in a salty water body. Experiments reviled that free buoyancy movement of bubbles forces displacement of ions, located on the outer side of the bubble wall curvatures. During the short moment of bubble passage, all ions in the vicinity of rising bubble, are separated into anions that are gathered on the bubble upper half sphere and cations that slip along the bottom concave half-sphere of a bubble and develop a sub-bubble vortex. The principle of ions separation bases on the differences in displacement resistance. In this way, relatively heavier and larger, thus more resistant to displacement anions are gathered on the rising bubble upper half sphere, while smaller and lighter cations are assembled on the bottom half sphere and within the sub-bubble vortex. The acceleration of motion generates antiparallel rotary of bi-ionic domains, what implies that anions rotate in clockwise (CW) and cationic in counter-clockwise (CCW) direction. Then, both rotational systems may undergo splicing and extreme condensing by bi-pirouette narrowing of rotary. It is suggested that such double helix motion of bi-ionic domains creates RNA/DNA molecules. Finally, when the bubble reaches the water surface it burst and the preprocessed RNA/DNA matter is ejected into the droplets. Since that stage, droplet is suspended in positively charged troposphere, thus the cationic domain is located in the droplet center, whilst negative ions are attracted to configure the outer areola. According to above, the present study implies that the rising bubbles in salty waters may incept synergistic processing of matter resulting in its rotational/spherical organization that led to assembly of RNA/DNA molecules and bacteria cells.

Bubble, Drop and Particle Unit (BDPU)

NASA Technical Reports Server (NTRS)

1998-01-01

This section of the Life and Microgravity Spacelab (LMS) publication includes the following articles entitled: (1) Oscillatory Thermocapillary Instability; (2) Thermocapillary Convection in Multilayer Systems; (3) Bubble and Drop Interaction with Solidification Front; (4) A Liquid Electrohydrodynamics Experiment; (5) Boiling on Small Plate Heaters under Microgravity and a Comparison with Earth Gravity; (6) Thermocapillary Migration and Interactions of Bubbles and Drops; and (7) Nonlinear Surface Tension Driven Bubble Migration

Real-time on-line ultrasonic monitoring for bubbles in ceramic 'slip' in pottery pipelines.

PubMed

Yim, Geun Tae; Leighton, Timothy G

2010-01-01

When casting ceramic items in potteries, liquid 'slip' is passed from a settling tank, through overhead pipelines, before being pumped manually into the moulds. It is not uncommon for bubbles to be introduced into the slip as it passes through the complex piping network, and indeed the presence of bubbles is a major source of financial loss to the ceramics industry worldwide. This is because the bubbles almost always remain undetected until after the ceramic items have been fired in a kiln, during which process bubbles expand and create unwanted holes in the pottery. Since there it is usually an interval of several hours between the injection of the slip into the moulds, and the inspection of the items after firing, such bubble generation goes undetected on the production line during the manufacture of hundreds or even thousands of ceramic units. Not only does this mean hours of wasted staff time, power consumption and production line time: the raw material which makes up these faulty items cannot even be recycled, as fired ceramic cannot be converted back into slip. Currently, the state-of-the-art method for detecting bubbles in the opaque ceramic slip is slow and invasive, can only be used off-line, and requires expertise which is rarely available. This paper describes the invention, engineering and in-factory testing across Europe of an ultrasonic system for real-time monitoring for the presence of bubbles in casting slip. It interprets changes in the scattering statistics accompanying the presence of the bubbles, the latter being detected through perturbations in the received signal when a narrow-band ultrasonic probing wave is transmitted through the slip. The device can be bolted onto the outside of the pipeline, or used in-line. It is automated, and requires no special expertise. The acoustic problems which had to be solved were severe, and included making the system capable of monitoring the slip regardless of the material of pipe (plastic, steel, etc.) and

Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

NASA Astrophysics Data System (ADS)

Leifer, Ira; Chernykh, Denis; Shakhova, Natalia; Semiletov, Igor

2017-06-01

Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s-1 to derive the in situ calibration curve (Q(σ)). These nonlinear curves related flux (Q) to sonar return (σ) for a multibeam echosounder (MBES) and a single-beam echosounder (SBES) for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering - precluding the use of a theoretical approach to derive Q(σ) from the product of the bubble σ(r) and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function (Ψ(σ)) with respect to Q found Ψ(σ) for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. Ψ(σ) for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core. Ψ(σ) was bimodal for all but the weakest plumes. Q(σ) was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes (Qm) were 5.56, 42.73, and 4.88 mmol s-1 for MBES data with good to reasonable agreement (4-37 %) between the SBES and MBES systems. The seepage flux occurrence probability distribution function (Ψ(Q)) was bimodal, with weak Ψ(Q) in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost.

Gas transfer in a bubbly wake flow

NASA Astrophysics Data System (ADS)

Karn, A.; Gulliver, J. S.; Monson, G. M.; Ellis, C.; Arndt, R. E. A.; Hong, J.

2016-05-01

The present work reports simultaneous bubble size and gas transfer measurements in a bubbly wake flow of a hydrofoil, designed to be similar to a hydroturbine blade. Bubble size was measured by a shadow imaging technique and found to have a Sauter mean diameter of 0.9 mm for a reference case. A lower gas flow rate, greater liquid velocities, and a larger angle of attack all resulted in an increased number of small size bubbles and a reduced weighted mean bubble size. Bubble-water gas transfer is measured by the disturbed equilibrium technique. The gas transfer model of Azbel (1981) is utilized to characterize the liquid film coefficient for gas transfer, with one scaling coefficient to reflect the fact that characteristic turbulent velocity is replaced by cross-sectional mean velocity. The coefficient was found to stay constant at a particular hydrofoil configuration while it varied within a narrow range of 0.52-0.60 for different gas/water flow conditions.

Magnetite Scavenging and the Buoyancy of Bubbles in Magmas

NASA Astrophysics Data System (ADS)

Gualda, G. A.; Ghiorso, M. S.

2005-12-01

It is generally assumed that when eruptions are triggered, magmas are bubble-free, and all the vesicularity observed in pumice is due to nucleation and growth during ascent. However, decompression experiments show that bubbles tend to nucleate on magnetite crystals at relatively low supersaturation, and there is convincing evidence that an exsolved gas phase was present during much of the evolution of the Bishop magma. The fate of pre-eruptive bubbles depends directly on their buoyancy, which can be strongly modified by the presence of crystals attached to the bubble-melt interface. That crystals tend to attach to bubbles is indicated by experiments and observations, and can be explained theoretically. Whether, however, crystals and bubbles can be held together by interface forces is yet uncertain, and we use the available knowledge on surface energies to explore this problem. We call adhesion energy the surface energy change due to attachment of a crystal to a bubble. We show that sticking a bubble to a mineral substrate is always energetically favored over keeping bubble and mineral separate. Because the adhesion energy is a strong function of the wetting angle, different minerals will be more strongly attached to bubbles than others. In particular, oxide minerals will attach to a given bubble much more strongly than any silicates. One interesting consequence of the attachment of grains to a bubble is that this can cause these bubble-crystal pairs to be neutrally buoyant, preventing bubble rise and crystal sinking. The criterion for buoyancy of a bubble-crystal pair can be calculated as the condition when the apparent weight of the crystal and the bubble are opposite and equal. If a bubble-mineral pair is to remain joined, the binding force has to be provided by the adhesion force, which is also a strong function of the wetting angle. Since the adhesion force is linear on R, and the buoyancy force is proportional to R cubed, there is a critical bubble radius

Jumping acoustic bubbles on lipid bilayers.

PubMed

Der Loughian, Christelle; Muleki Seya, Pauline; Pirat, Christophe; Inserra, Claude; Béra, Jean-Christophe; Rieu, Jean-Paul

2015-05-07

In the context of sonoporation, we use supported lipid bilayers as a model for biological membranes and investigate the interactions between the bilayer and microbubbles induced by ultrasound. Among the various types of damage caused by bubbles on the surface, our experiments exhibit a singular dynamic interaction process where bubbles are jumping on the bilayer, forming a necklace pattern of alteration on the membrane. This phenomenon was explored with different time and space resolutions and, based on our observations, we propose a model for a microbubble subjected to the combined action of van der Waals, acoustic and hydrodynamic forces. Describing the repeated jumps of the bubble, this model explains the lipid exchanges between the bubble and bilayer.

Rise of Air Bubbles in Aircraft Lubricating Oils

NASA Technical Reports Server (NTRS)

Robinson, J. V.

1950-01-01

Lubricating and antifoaming additives in aircraft lubricating oils may impede the escape of small bubbles from the oil by forming shells of liquid with a quasi-solid or gel structure around the bubbles. The rates of rise of small air bubbles, up to 2 millimeters in diameter, were measured at room temperature in an undoped oil, in the same oil containing foam inhibitors, and in an oil containing lubricating additives. The apparent diameter of the air bubbles was measured visually through an ocular micrometer on a traveling telescope. The bubbles in the undoped oil obeyed Stokes' Law, the rate of rise being proportional to the square of the apparent diameter and inversely proportional to the viscosity of the oil. The bubbles in the oils containing lubricating additives or foam inhibitors rose more slowly than the rate predicted by Stokes 1 Law from the apparent diameter, and the rate of rise decreased as the length of path the bubbles traveled increased. A method is derived to calculate the thickness of the liquid shell which would have to move with the bubbles in the doped oils to account for the abnoi'I!l8.lly slow velocity. The maximum thickness of this shell, calculated from the velocities observed, was equal to the bubble radius.

Detecting vapour bubbles in simulations of metastable water

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

González, Miguel A.; Abascal, Jose L. F.; Valeriani, Chantal, E-mail: christoph.dellago@univie.ac.at, E-mail: cvaleriani@quim.ucm.es

2014-11-14

The investigation of cavitation in metastable liquids with molecular simulations requires an appropriate definition of the volume of the vapour bubble forming within the metastable liquid phase. Commonly used approaches for bubble detection exhibit two significant flaws: first, when applied to water they often identify the voids within the hydrogen bond network as bubbles thus masking the signature of emerging bubbles and, second, they lack thermodynamic consistency. Here, we present two grid-based methods, the M-method and the V-method, to detect bubbles in metastable water specifically designed to address these shortcomings. The M-method incorporates information about neighbouring grid cells to distinguishmore » between liquid- and vapour-like cells, which allows for a very sensitive detection of small bubbles and high spatial resolution of the detected bubbles. The V-method is calibrated such that its estimates for the bubble volume correspond to the average change in system volume and are thus thermodynamically consistent. Both methods are computationally inexpensive such that they can be used in molecular dynamics and Monte Carlo simulations of cavitation. We illustrate them by computing the free energy barrier and the size of the critical bubble for cavitation in water at negative pressure.« less

Morphology of Two-Phase Layers with Large Bubbles

NASA Astrophysics Data System (ADS)

Vékony, Klára; Kiss, László I.

2010-10-01

The understanding of formation and movement of bubbles nucleated during aluminum reduction is essential for a good control of the electrolysis process. In our experiments, we filmed and studied the formation of a bubble layer under the anode in a real-size air-water electrolysis cell model. The maximum height of the bubbles was found to be up to 2 cm because of the presence of the so-called Fortin bubbles. Also, the mean height of the bubble layer was found to be much higher than published previously. The Fortin bubbles were investigated more closely, and their shape was found to be induced by a gravity wave formed at the gas-liquid interface. In addition, large bubbles were always observed to break up into smaller parts right before escaping from under the anode. This breakup and escape led to a large momentum transfer in the bath.

The detachment of particles from coalescing bubble pairs.

PubMed

Ata, Seher

2009-10-15

This paper is concerned with the detachment of particles from coalescing bubble pairs. Two bubbles were generated at adjacent capillaries and coated with hydrophobic glass particles of mean diameter 66 microm. The bubbles were then positioned next to each other until the thin liquid film between them ruptured. The particles that dropped from the bubble surface during the coalescence process were collected and measured. The coalescence process was very vigorous and observations showed that particles detached from the bubble surfaces as a result of the oscillations caused by coalescence. The attached particles themselves and, to some extent the presence of the surfactant had a damping affect on the bubble oscillation, which played a decisive role on the particle detachment phenomena. The behaviour of particles on the surfaces of the bubbles during coalescence was described, and implications of results for the flotation process were discussed.

Contact bubble bilayers with flush drainage.

PubMed

Iwamoto, Masayuki; Oiki, Shigetoshi

2015-03-16

Planar lipid bilayers have been used to form stable bilayers into which membrane proteins are reconstituted for measurements of their function under an applied membrane potential. Recently, a lipid bilayer membrane is formed by the apposition of two monolayers that line an oil-electrolyte interface. Here, a bilayer membrane system is developed with picoliter bubbles under mechanically and chemically manipulable conditions. A water bubble lined with a phospholipid monolayer is blown from a glass pipette into an oil phase. Two blowing pipettes are manipulated, and bubbles (each with a diameter of ~ 50 μm) are held side by side to form a bilayer, which is termed a contact bubble bilayer. With the electrode implemented in the blowing pipette, currents through the bilayer are readily measured. The intra-bubble pressure is varied with the pressure-controller, leading to various sizes of the bubble and the membrane area. A rapid solution exchange system is developed by introducing additional pressure-driven injection pipettes, and the blowing pipette works as a drain. The solution is exchanged within 20 ms. Also, an asymmetric membrane with different lipid composition of each leaflet is readily formed. Example applications of this versatile method are presented to characterize the function of ion channels.

Contact Bubble Bilayers with Flush Drainage

PubMed Central

Iwamoto, Masayuki; Oiki, Shigetoshi

2015-01-01

Planar lipid bilayers have been used to form stable bilayers into which membrane proteins are reconstituted for measurements of their function under an applied membrane potential. Recently, a lipid bilayer membrane is formed by the apposition of two monolayers that line an oil-electrolyte interface. Here, a bilayer membrane system is developed with picoliter bubbles under mechanically and chemically manipulable conditions. A water bubble lined with a phospholipid monolayer is blown from a glass pipette into an oil phase. Two blowing pipettes are manipulated, and bubbles (each with a diameter of ~ 50 μm) are held side by side to form a bilayer, which is termed a contact bubble bilayer. With the electrode implemented in the blowing pipette, currents through the bilayer are readily measured. The intra-bubble pressure is varied with the pressure-controller, leading to various sizes of the bubble and the membrane area. A rapid solution exchange system is developed by introducing additional pressure-driven injection pipettes, and the blowing pipette works as a drain. The solution is exchanged within 20 ms. Also, an asymmetric membrane with different lipid composition of each leaflet is readily formed. Example applications of this versatile method are presented to characterize the function of ion channels. PMID:25772819

Flying after diving: should recommendations be reviewed? In-flight echocardiographic study in bubble-prone and bubble-resistant divers.

PubMed

Cialoni, Danilo; Pieri, Massimo; Balestra, Costantino; Marroni, Alessandro

2015-03-01

Inert gas accumulated after multiple recreational dives can generate tissue supersaturation and bubble formation when ambient pressure decreases. We hypothesized that this could happen even if divers respected the currently recommended 24-hour pre-flight surface interval (PFSI). We performed transthoracic echocardiography (TTE) on a group of 56 healthy scuba divers (39 male, 17 female) as follows: first echo--during the outgoing flight, no recent dives; second echo--before boarding the return flight, after a multiday diving week in the tropics and a 24-hour PFSI; third echo--during the return flight at 30, 60 and 90 minutes after take-off. TTE was also done after every dive during the week's diving. Divers were divided into three groups according to their 'bubble-proneness': non-bubblers, occasional bubblers and consistent bubblers. During the diving, 23 subjects never developed bubbles, 17 only occasionally and 16 subjects produced bubbles every day and after every dive. Bubbles on the return flight were observed in eight of the 56 divers (all from the 'bubblers' group). Two subjects who had the highest bubble scores during the diving were advised not to make the last dive (increasing their PFSI to approximately 36 hours), and did not demonstrate bubbles on the return flight. Even though a 24-hour PFSI is recommended on the basis of clinical trials showing a low risk of decompression sickness (DCS), the presence of venous gas bubbles in-flight in eight of 56 divers leads us to suspect that in real-life situations DCS risk after such a PFSI is not zero.

Bubble gate for in-plane flow control.

PubMed

Oskooei, Ali; Abolhasani, Milad; Günther, Axel

2013-07-07

We introduce a miniature gate valve as a readily implementable strategy for actively controlling the flow of liquids on-chip, within a footprint of less than one square millimetre. Bubble gates provide for simple, consistent and scalable control of liquid flow in microchannel networks, are compatible with different bulk microfabrication processes and substrate materials, and require neither electrodes nor moving parts. A bubble gate consists of two microchannel sections: a liquid-filled channel and a gas channel that intercepts the liquid channel to form a T-junction. The open or closed state of a bubble gate is determined by selecting between two distinct gas pressure levels: the lower level corresponds to the "open" state while the higher level corresponds to the "closed" state. During closure, a gas bubble penetrates from the gas channel into the liquid, flanked by a column of equidistantly spaced micropillars on each side, until the flow of liquid is completely obstructed. We fabricated bubble gates using single-layer soft lithographic and bulk silicon micromachining procedures and evaluated their performance with a combination of theory and experimentation. We assessed the dynamic behaviour during more than 300 open-and-close cycles and report the operating pressure envelope for different bubble gate configurations and for the working fluids: de-ionized water, ethanol and a biological buffer. We obtained excellent agreement between the experimentally determined bubble gate operational envelope and a theoretical prediction based on static wetting behaviour. We report case studies that serve to illustrate the utility of bubble gates for liquid sampling in single and multi-layer microfluidic devices. Scalability of our strategy was demonstrated by simultaneously addressing 128 bubble gates.

Numerical simulations of non-spherical bubble collapse.

PubMed

Johnsen, Eric; Colonius, Tim

2009-06-01

A high-order accurate shock- and interface-capturing scheme is used to simulate the collapse of a gas bubble in water. In order to better understand the damage caused by collapsing bubbles, the dynamics of the shock-induced and Rayleigh collapse of a bubble near a planar rigid surface and in a free field are analysed. Collapse times, bubble displacements, interfacial velocities and surface pressures are quantified as a function of the pressure ratio driving the collapse and of the initial bubble stand-off distance from the wall; these quantities are compared to the available theory and experiments and show good agreement with the data for both the bubble dynamics and the propagation of the shock emitted upon the collapse. Non-spherical collapse involves the formation of a re-entrant jet directed towards the wall or in the direction of propagation of the incoming shock. In shock-induced collapse, very high jet velocities can be achieved, and the finite time for shock propagation through the bubble may be non-negligible compared to the collapse time for the pressure ratios of interest. Several types of shock waves are generated during the collapse, including precursor and water-hammer shocks that arise from the re-entrant jet formation and its impact upon the distal side of the bubble, respectively. The water-hammer shock can generate very high pressures on the wall, far exceeding those from the incident shock. The potential damage to the neighbouring surface is quantified by measuring the wall pressure. The range of stand-off distances and the surface area for which amplification of the incident shock due to bubble collapse occurs is determined.

Numerical simulations of non-spherical bubble collapse

PubMed Central

JOHNSEN, ERIC; COLONIUS, TIM

2009-01-01

A high-order accurate shock- and interface-capturing scheme is used to simulate the collapse of a gas bubble in water. In order to better understand the damage caused by collapsing bubbles, the dynamics of the shock-induced and Rayleigh collapse of a bubble near a planar rigid surface and in a free field are analysed. Collapse times, bubble displacements, interfacial velocities and surface pressures are quantified as a function of the pressure ratio driving the collapse and of the initial bubble stand-off distance from the wall; these quantities are compared to the available theory and experiments and show good agreement with the data for both the bubble dynamics and the propagation of the shock emitted upon the collapse. Non-spherical collapse involves the formation of a re-entrant jet directed towards the wall or in the direction of propagation of the incoming shock. In shock-induced collapse, very high jet velocities can be achieved, and the finite time for shock propagation through the bubble may be non-negligible compared to the collapse time for the pressure ratios of interest. Several types of shock waves are generated during the collapse, including precursor and water-hammer shocks that arise from the re-entrant jet formation and its impact upon the distal side of the bubble, respectively. The water-hammer shock can generate very high pressures on the wall, far exceeding those from the incident shock. The potential damage to the neighbouring surface is quantified by measuring the wall pressure. The range of stand-off distances and the surface area for which amplification of the incident shock due to bubble collapse occurs is determined. PMID:19756233

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.

Trauma-Focused CBT for Youth who Experience Ongoing Traumas

PubMed Central

Cohen, Judith A.; Mannarino, Anthony P.; Murray, Laura A.

2011-01-01

Many youth experience ongoing trauma exposure, such as domestic or community violence. Clinicians often ask whether evidence-based treatments containing exposure components to reduce learned fear responses to historical trauma are appropriate for these youth. Essentially the question is, if youth are desensitized to their trauma experiences, will this in some way impair their responding to current or ongoing trauma? The paper addresses practical strategies for implementing one evidence-based treatment, Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) for youth with ongoing traumas. Collaboration with local therapists and families participating in TF-CBT community and international programs elucidated effective strategies for applying TF-CBT with these youth. These strategies included: 1) enhancing safety early in treatment; 2) effectively engaging parents who experience personal ongoing trauma; and 3) during the trauma narrative and processing component focusing on a) increasing parental awareness and acceptance of the extent of the youths’ ongoing trauma experiences; b) addressing youths’ maladaptive cognitions about ongoing traumas; and c) helping youth differentiate between real danger and generalized trauma reminders. Case examples illustrate how to use these strategies in diverse clinical situations. Through these strategies TF-CBT clinicians can effectively improve outcomes for youth experiencing ongoing traumas. PMID:21855140

Bursting the bubble of melt inclusions

USGS Publications Warehouse

Lowenstern, Jacob B.

2015-01-01

Most silicate melt inclusions (MI) contain bubbles, whose significance has been alternately calculated, pondered, and ignored, but rarely if ever directly explored. Moore et al. (2015) analyze the bubbles, as well as their host glasses, and conclude that they often hold the preponderance of CO2 in the MI. Their findings entreat future researchers to account for the presence of bubbles in MI when calculating volatile budgets, saturation pressures, and eruptive flux.

Fast Initialization of Bubble-Memory Systems

NASA Technical Reports Server (NTRS)

Looney, K. T.; Nichols, C. D.; Hayes, P. J.

1986-01-01

Improved scheme several orders of magnitude faster than normal initialization scheme. State-of-the-art commercial bubble-memory device used. Hardware interface designed connects controlling microprocessor to bubblememory circuitry. System software written to exercise various functions of bubble-memory system in comparison made between normal and fast techniques. Future implementations of approach utilize E2PROM (electrically-erasable programable read-only memory) to provide greater system flexibility. Fastinitialization technique applicable to all bubble-memory devices.

Buoyancy Driven Shear Flows of Bubble Suspensions

NASA Technical Reports Server (NTRS)

Koch, D. L.; Hill, R. J.; Chellppannair, T.; Zenit, R.; Zenit, R.; Spelt, P. D. M.

1999-01-01

In this work the gas volume fraction and the root-mean-squared fluid velocity are measured in buoyancy driven shear flows of bubble suspensions in a tall, inclined, rectangular channel. The experiments are performed under conditions where We << 1a nd Re >> 1, for which comparisons are made with kinetic theory and numerical simulations. Here Re = gamma(a(exp 2)/nu is the Reynolds number and We = rho(gamma(exp 2))a(exp 3)/sigma is the Weber number; gamma is the shear rate, a is the bubble radius, nu is the kinematic viscosity of the liquid, rho is the density of the liquid, and sigma is the surface tension of the gas/liquid interface. Kang et al. calculated the bubble phase pressure and velocity variance of sheared bubble suspensions under conditions where the bubbles are spherical and the liquid phase velocity field can be approximated using potential flow theory, i.e. We= 0 and Re >> 1. Such conditions can be achieved in an experiment using gas bubbles, with a radius of O(0.5mm), in water. The theory requires that there be no average relative motion of the gas and liquid phases, hence the motivation for an experimental program in microgravity. The necessity of performing preliminary, Earth based experiments, however, requires performing experiments where the gas phase rises in the liquid, which significantly complicates the comparison of experiments with theory. Rather than comparing experimental results with theory for a uniform, homogeneous shear flow, experiments can be compared directly with solutions of the averaged equations of motion for bubble suspensions. This requires accounting for the significant lift force acting on the gas phase when the bubbles rise parallel to the average velocity of the sheared suspension. Shear flows can be produced in which the bubble phase pressure gradient, arising from shear induced collisions amongst the bubbles, balances a body force (centrifugal or gravitational) on the gas phase. A steady, non-uniform gas volume fraction

Characterisation of bubbles in liquids using acoustic techniques

NASA Astrophysics Data System (ADS)

Ramble, David Gary

1997-12-01

This thesis is concerned with the characterisation of air bubbles in a liquid through the use of a range of acoustic techniques, with the ultimate aim of minimising the ambiguity of the result and the complexity of the task. A bubble is particularly amenable to detection by using acoustical methods because there usually exists a large acoustic impedance mismatch between the gas/vapour inside the bubble and that of the surrounding liquid. The bubble also behaves like a single degree-of-freedom oscillator when excited, and as such exhibits a well-defined resonance frequency which is related to its radius. Though techniques which exploit this resonance property of the bubble are straightforward to apply, the results are prone to ambiguities as larger bubbles can geometrically scatter more sound than a smaller resonant bubble. However, these drawbacks can be overcome by using acoustical methods which make use of the nonlinear behaviour of bubbles. A particular nonlinear technique monitors the second harmonic emission of the bubble which is a global maximum at resonance. In addition, a two- frequency excitation technique is used which involves exciting the bubble with a fixed high frequency signal (the imaging signal, ωi) of the order of megahertz, and a lower variable frequency (the pumping signal, ωp) which is tuned to the bubble's resonance. The bubble couples these two sound fields together to produce sum-and-difference terms which peak at resonance. The two most promising combination frequency signals involve the coupling of the bubble's fundamental with the imaging frequency to give rise to a ωi+ωp signal, and the coupling of a subharmonic signal at half the resonance frequency of the bubble to give rise to a ωi/pmωp/2 signal. Initially, theory is studied which outlines the advantages and disadvantages of each of the acoustic techniques available. Experiments are then conducted in a large tank of water on simple bubble populations, ranging from stationary

Bursting the Taylor cone bubble

NASA Astrophysics Data System (ADS)

Pan, Zhao; Truscott, Tadd

2014-11-01

A soap bubble fixed on a surface and placed in an electric field will take on the shape of a cone rather than constant curvature (dome) when the electrical field is not present. The phenomenon was introduced by J. Zeleny (1917) and studied extensively by C.T. Wilson & G.I. Taylor (1925). We revisit the Taylor cone problem by studying the deformation and bursting of soap bubbles in a point charge electric field. A single bubble takes on the shape of a cone in the electric field and a high-speed camera equipped with a micro-lens is used to observe the unsteady dynamics at the tip. Rupture occurs as a very small piece of the tip is torn away from the bubble toward the point charge. Based on experiments, a theoretical model is developed that predicts when rupture should occur. This study may help in the design of foam-removal techniques in engineering and provide a better understanding of an electrified air-liquid interface.

Raman Spectral Band Oscillations in Large Graphene Bubbles

NASA Astrophysics Data System (ADS)

Huang, Yuan; Wang, Xiao; Zhang, Xu; Chen, Xianjue; Li, Baowen; Wang, Bin; Huang, Ming; Zhu, Chongyang; Zhang, Xuewei; Bacsa, Wolfgang S.; Ding, Feng; Ruoff, Rodney S.

2018-05-01

Raman spectra of large graphene bubbles showed size-dependent oscillations in spectral intensity and frequency, which originate from optical standing waves formed in the vicinity of the graphene surface. At a high laser power, local heating can lead to oscillations in the Raman frequency and also create a temperature gradient in the bubble. Based on Raman data, the temperature distribution within the graphene bubble was calculated, and it is shown that the heating effect of the laser is reduced when moving from the center of a bubble to its edge. By studying graphene bubbles, both the thermal conductivity and chemical reactivity of graphene were assessed. When exposed to hydrogen plasma, areas with bubbles are found to be more reactive than flat graphene.

A computationally efficient modelling of laminar separation bubbles

NASA Technical Reports Server (NTRS)

Dini, Paolo; Maughmer, Mark D.

1989-01-01

The goal is to accurately predict the characteristics of the laminar separation bubble and its effects on airfoil performance. Toward this end, a computational model of the separation bubble was developed and incorporated into the Eppler and Somers airfoil design and analysis program. Thus far, the focus of the research was limited to the development of a model which can accurately predict situations in which the interaction between the bubble and the inviscid velocity distribution is weak, the so-called short bubble. A summary of the research performed in the past nine months is presented. The bubble model in its present form is then described. Lastly, the performance of this model in predicting bubble characteristics is shown for a few cases.

Two types of nonlinear wave equations for diffractive beams in bubbly liquids with nonuniform bubble number density.

PubMed

Kanagawa, Tetsuya

2015-05-01

This paper theoretically treats the weakly nonlinear propagation of diffracted sound beams in nonuniform bubbly liquids. The spatial distribution of the number density of the bubbles, initially in a quiescent state, is assumed to be a slowly varying function of the spatial coordinates; the amplitude of variation is assumed to be small compared to the mean number density. A previous derivation method of nonlinear wave equations for plane progressive waves in uniform bubbly liquids [Kanagawa, Yano, Watanabe, and Fujikawa (2010). J. Fluid Sci. Technol. 5(3), 351-369] is extended to handle quasi-plane beams in weakly nonuniform bubbly liquids. The diffraction effect is incorporated by adding a relation that scales the circular sound source diameter to the wavelength into the original set of scaling relations composed of nondimensional physical parameters. A set of basic equations for bubbly flows is composed of the averaged equations of mass and momentum, the Keller equation for bubble wall, and supplementary equations. As a result, two types of evolution equations, a nonlinear Schrödinger equation including dissipation, diffraction, and nonuniform effects for high-frequency short-wavelength case, and a Khokhlov-Zabolotskaya-Kuznetsov equation including dispersion and nonuniform effects for low-frequency long-wavelength case, are derived from the basic set.

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.

Blunt Force Trauma in Veterinary Forensic Pathology.

PubMed

Ressel, L; Hetzel, U; Ricci, E

2016-09-01

Veterinary pathologists commonly encounter lesions of blunt trauma. The development of lesions is affected by the object's mass, velocity, size, shape, and angle of impact and by the plasticity and mobility of the impacted organ. Scrape, impact, and pattern abrasions cause localized epidermal loss and sometimes broken hairs and implanted foreign material. Contusions are best identified after reflecting the skin, and must be differentiated from coagulopathies and livor mortis. Lacerations-traumatic tissue tears-may have irregular margins, bridging by more resilient tissue, deviation of the wound tail, crushed hairs, and unilateral abrasion. Hanging or choking can cause circumferential cervical abrasions, contusions and rupture of hairs, hyoid bone fractures, and congestion of the head. Other special forms of blunt trauma include fractured nails, pressure sores, and dog bites. Ocular blunt trauma causes extraocular and intraocular hemorrhages, proptosis, or retinal detachment. The thoracic viscera are relatively protected from blunt trauma but may develop hemorrhages in intercostal muscles, rib fractures, pulmonary or cardiac contusions or lacerations with subsequent hemothorax, pneumothorax, or cardiac arrhythmia. The abdominal wall is resilient and moveable, yet the liver and spleen are susceptible to traumatic laceration or rupture. Whereas extravasation of blood can occur after death, evidence of vital injury includes leukocyte infiltration, erythrophagocytosis, hemosiderin, reparative lesions of fibroblast proliferation, myocyte regeneration in muscle, and callus formation in bone. Understanding these processes aids in the diagnosis of blunt force trauma including estimation of the age of resulting injuries. © The Author(s) 2016.

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).

Orbital motions of bubbles in an acoustic field

NASA Astrophysics Data System (ADS)

Shirota, Minori; Yamashita, Ko; Inamura, Takao

2012-09-01

This experimental study aims to clarify the mechanism of orbital motion of two oscillating bubbles in an acoustic field. Trajectory of the orbital motion on the wall of a spherical levitator was observed using a high-speed video camera. Because of a good repeatability in volume oscillation of bubbles, we were also able to observe the radial motion driven at 24 kHz by stroboscopic like imaging technique. The orbital motions of bubbles raging from 0.13 to 0.18 mm were examined with different forcing amplitude and in different viscous oils. As a result, we found that pairs of bubbles revolve along an elliptic orbit around the center of mass of the bubbles. We also found that the two bubbles perform anti-phase radial oscillation. Although this radial oscillation should result in a repulsive secondary Bjerknes force, the bubbles kept a constant separate distance of about 1 mm, which indicates the existence of centripetal primary Bjerknes force.

Dual-frequency ultrasound for detecting and sizing bubbles.

PubMed

Buckey, Jay C; Knaus, Darin A; Alvarenga, Donna L; Kenton, Marc A; Magari, Patrick J

2005-01-01

ISS construction and Mars exploration require extensive extravehicular activity (EVA), exposing crewmembers to increased decompression sickness risk. Improved bubble detection technologies could help increase EVA efficiency and safety. Creare Inc. has developed a bubble detection and sizing instrument using dual-frequency ultrasound. The device emits "pump" and "image" signals at two frequencies. The low-frequency pump signal causes an appropriately-sized bubble to resonate. When the image frequency hits a resonating bubble, mixing signals are returned at the sum and difference of the two frequencies. To test the feasibility of transcutaneous intravascular detection, intravascular bubbles in anesthetized swine were produced using agitated saline and decompression stress. Ultrasonic transducers on the chest provided the two frequencies. Mixing signals were detected transthoracically in the right atrium using both methods. A histogram of estimated bubble sizes could be constructed. Bubbles can be detected and sized transthoracically in the right atrium using dual-frequency ultrasound. c2005 Elsevier Ltd. All rights reserved.

The elasticity of soap bubbles containing wormlike micelles.

PubMed

Sabadini, Edvaldo; Ungarato, Rafael F S; Miranda, Paulo B

2014-01-28

Slow-motion imaging of the rupture of soap bubbles generally shows the edges of liquid films retracting at a constant speed (known as the Taylor-Culick velocity). Here we investigate soap bubbles formed from simple solutions of a cationic surfactant (cetyltrimethylammonium bromide - CTAB) and sodium salicylate. The interaction of salicylate ions with CTAB leads to the formation of wormlike micelles (WLM), which yield a viscoelastic behavior to the liquid film of the bubble. We demonstrate that these elastic bubbles collapse at a velocity up to 30 times higher than the Taylor-Culick limit, which has never been surpassed. This is because during the bubble inflation, the entangled WLM chains stretch, storing elastic energy. This extra energy is then released during the rupture of the bubble, yielding an additional driving force for film retraction (besides surface tension). This new mechanism for the bursting of elastic bubbles may have important implications to the breakup of viscoelastic sprays in industrial applications.

Degradation mechanisms of 4-chlorophenol in a novel gas-liquid hybrid discharge reactor by pulsed high voltage system with oxygen or nitrogen bubbling.

PubMed

Zhang, Yi; Zhou, Minghua; Hao, Xiaolong; Lei, Lecheng

2007-03-01

The effect of gas bubbling on the removal efficiency of 4-chlorophenol (4-CP) in aqueous solution has been investigated using a novel pulsed high voltage gas-liquid hybrid discharge reactor, which generates gas-phase discharge above the water surface simultaneously with the spark discharge directly in the liquid. The time for 100% of 4-CP degradation in the case of oxygen bubbling (7 min) was much shorter than that in the case of nitrogen bubbling (25 min) as plenty of hydrogen peroxide and ozone formed in oxygen atmosphere enhanced the removal efficiency of 4-CP. Except for the main similar intermediates (4-chlorocatechol, hydroquinone and 1,4-benzoquinone) produced in the both cases of oxygen and nitrogen bubbling, special intermediates (5-chloro-3-nitropyrocatechol, 4-chloro-2-nitrophenol, nitrate and nitrite ions) were produced in nitrogen atmosphere. The reaction pathway of 4-CP in the case of oxygen bubbling was oxygen/ozone attack on the radical hydroxylated derivatives of 4-CP. However, in the case of nitrogen bubbling, hydroxylation was the main reaction pathway with effect of N atom on degradation of 4-CP.

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.

OH Production Enhancement in Bubbling Pulsed Discharges

NASA Astrophysics Data System (ADS)

Lungu, Cristian P.; Porosnicu, Corneliu; Jepu, Ionut; Chiru, Petrica; Zaroschi, Valentin; Lungu, Ana M.; Saito, Nagahiro; Bratescu, Maria; Takai, Osamu; Velea, Theodor; Predica, Vasile

2010-10-01

The generation of active species, such as H2O2, O*, OH*, HO2*, O3, N2*, etc, produced in aqueous solutions by HV pulsed discharges was studied in order to find the most efficient way in waste water treatment taking into account that these species are almost stronger oxidizers than ozone. Plasma was generated inside gas bubbles formed by the argon, air and oxygen gas flow between the special designed electrodes. The pulse width and pulse frequency influence was studied in order to increase the efficiency of the OH active species formation. The produced active species were investigated by optical emission spectroscopy and correlated with electrical parameters of the discharges (frequency, pulse width, amplitude, and rise and decay time).

Expansion of a compressible gas bubble in Stokes flow

NASA Astrophysics Data System (ADS)

Pozrikidis, C.

2001-09-01

The flow-induced deformation of an inviscid bubble occupied by a compressible gas and suspended in an ambient viscous liquid is considered at low Reynolds numbers with particular reference to the pressure developing inside the bubble. Ambient fluid motion alters the bubble pressure with respect to that established in the quiescent state, and requires the bubble to expand or contract according to an assumed equation of state. When changes in the bubble volume are prohibited by a global constraint on the total volume of the flow, the ambient pressure is modified while the bubble pressure remains constant during the deformation. A numerical method is developed for evaluating the pressure inside a two-dimensional bubble in an ambient Stokes flow on the basis of the normal component of the interfacial force balance involving the capillary pressure, the normal viscous stress, and the pressure at the free surface on the side of the liquid; the last is computed by evaluating a strongly singular integral. Dynamical simulations of bubble deformation are performed using the boundary integral method properly implemented to remove the multiplicity of solutions due to the a priori unknown rate of expansion, and three particular problems are discussed in detail: the shrinkage of a bubble at a specified rate, the deformation of a bubble subject to simple shear flow, and the deformation of a bubble subject to a purely elongational flow. In the case of shrinkage, it is found that the surface tension plays a critical role in determining the behaviour of the bubble pressure near the critical time when the bubble disappears. In the case of shear or elongational flow, it is found that the bubble contracts during an initial period of deformation from the circular shape, and then it expands to obtain a stationary shape whose area is higher than that assumed in the quiescent state. Expansion may destabilize the bubble by raising the capillary number above the critical threshold under which

Psychological Trauma in the Schools: A Retrospective Study.

ERIC Educational Resources Information Center

Zelikoff, Wendy L.; Hyman, Irwin A.

An increase in clinical cases indicates that trauma in school children can be connected to teacher abuse. A survey was administered to 35 college undergraduates, 40 school teachers, 41 special educators, and 65 mixed individuals from Pennsylvania, New Jersey, New York, Delaware, Georgia, and Puerto Rico to determine the nature of the abuse, its…

How Stressful Is "Deep Bubbling"?

PubMed

Tyrmi, Jaana; Laukkanen, Anne-Maria

2017-03-01

Water resistance therapy by phonating through a tube into the water is used to treat dysphonia. Deep submersion (≥10 cm in water, "deep bubbling") is used for hypofunctional voice disorders. Using it with caution is recommended to avoid vocal overloading. This experimental study aimed to investigate how strenuous "deep bubbling" is. Fourteen subjects, half of them with voice training, repeated the syllable [pa:] in comfortable speaking pitch and loudness, loudly, and in strained voice. Thereafter, they phonated a vowel-like sound both in comfortable loudness and loudly into a glass resonance tube immersed 10 cm into the water. Oral pressure, contact quotient (CQ, calculated from electroglottographic signal), and sound pressure level were studied. The peak oral pressure P(oral) during [p] and shuttering of the outer end of the tube was measured to estimate the subglottic pressure P(sub) and the mean P(oral) during vowel portions to enable calculation of transglottic pressure P(trans). Sensations during phonation were reported with an open-ended interview. P(sub) and P(oral) were higher in "deep bubbling" and P(trans) lower than in loud syllable phonation, but the CQ did not differ significantly. Similar results were obtained for the comparison between loud "deep bubbling" and strained phonation, although P(sub) did not differ significantly. Most of the subjects reported "deep bubbling" to be stressful only for respiratory and lip muscles. No big differences were found between trained and untrained subjects. The CQ values suggest that "deep bubbling" may increase vocal fold loading. Further studies should address impact stress during water resistance exercises. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Pressure waves in a supersaturated bubbly magma

USGS Publications Warehouse

Kurzon, I.; Lyakhovsky, V.; Navon, O.; Chouet, B.

2011-01-01

We study the interaction of acoustic pressure waves with an expanding bubbly magma. The expansion of magma is the result of bubble growth during or following magma decompression and leads to two competing processes that affect pressure waves. On the one hand, growth in vesicularity leads to increased damping and decreased wave amplitudes, and on the other hand, a decrease in the effective bulk modulus of the bubbly mixture reduces wave velocity, which in turn, reduces damping and may lead to wave amplification. The additional acoustic energy originates from the chemical energy released during bubble growth. We examine this phenomenon analytically to identify conditions under which amplification of pressure waves is possible. These conditions are further examined numerically to shed light on the frequency and phase dependencies in relation to the interaction of waves and growing bubbles. Amplification is possible at low frequencies and when the growth rate of bubbles reaches an optimum value for which the wave velocity decreases sufficiently to overcome the increased damping of the vesicular material. We examine two amplification phase-dependent effects: (1) a tensile-phase effect in which the inserted wave adds to the process of bubble growth, utilizing the energy associated with the gas overpressure in the bubble and therefore converting a large proportion of this energy into additional acoustic energy, and (2) a compressive-phase effect in which the pressure wave works against the growing bubbles and a large amount of its acoustic energy is dissipated during the first cycle, but later enough energy is gained to amplify the second cycle. These two effects provide additional new possible mechanisms for the amplification phase seen in Long-Period (LP) and Very-Long-Period (VLP) seismic signals originating in magma-filled cracks.

Role of entrapped vapor bubbles during microdroplet evaporation

NASA Astrophysics Data System (ADS)

Putnam, Shawn A.; Byrd, Larry W.; Briones, Alejandro M.; Hanchak, Michael S.; Ervin, Jamie S.; Jones, John G.

2012-08-01

On superheated surfaces, the air bubble trapped during impingement grows into a larger vapor bubble and oscillates at the frequency predicted for thermally induced capillary waves. In some cases, the entrapped vapor bubble penetrates the droplet interface, leaving a micron-sized coffee-ring pattern of pure fluid. Vapor bubble entrapment, however, does not influence the evaporation rate. This is also true on laser heated surfaces, where a laser can thermally excite capillary waves and induce bubble oscillations over a broad range of frequencies, suggesting that exciting perturbations in a pinned droplets interface is not an effective avenue for enhancing evaporative heat transfer.

Bubble coalescence in a Newtonian fluid

NASA Astrophysics Data System (ADS)

Garg, Vishrut; Basaran, Osman

2017-11-01

Bubble coalescence plays a central role in the hydrodynamics of gas-liquid systems such as bubble column reactors, spargers, and foams. Two bubbles approaching each other at velocity V coalesce when the thin film between them ruptures, which is often the rate-limiting step. Experimental studies of this system are difficult, and recent works provide conflicting results on the effect of V on coalescence times. We simulate the head-on approach of two bubbles of equal radii R in an incompressible Newtonian fluid (density ρ, viscosity μ, and surface tension σ) by solving numerically the free boundary problem comprised of the Navier Stokes and continuity equations. Simulations are made challenging by the existence of highly disparate lengthscales, i.e. film thickness and drop radii, which are resolved by using the method of elliptic mesh generation. For a given liquid, the bubbles are shown to coalesce for all velocities below a critical value. The effects of Ohnesorge number Oh = μ /√{ ρσR } on coalescence time and critical velocity are also investigated.

Inflation and bubbles in general relativity

NASA Astrophysics Data System (ADS)

Laguna-Castillo, Pablo; Matzner, Richard A.

1986-11-01

Following Israel's study of singular hypersurfaces and thin shells in general relativity, the complete set of Einstein's field equations in the presence of a bubble boundary SIGMA is reviewed for all spherically symmetric embedding four-geometries M+/-. The mapping that identifies points between the boundaries Σ+ and Σ- is obtained explicitly when the regions M+ and M- are described by a de Sitter and a Minkowski metric, respectively. In addition, the evolution of a bubble with vanishing surface energy density is studied in a spatially flat Robertson-Walker space-time, for region M- radiation dominated with a vanishing cosmological constant, and an energy equation in M+ determined by the matching. It is found that this type of bubble leads to a ``worm-hole'' matching; that is, an infinite extent exterior of a sphere is joined across the wall to another infinite extent exterior of a sphere. Interior-interior matches are also possible. Under this model, solutions for a bubble following a Hubble law are analyzed. Numerical solutions for bubbles with constant tension are also obtained.

Assuring optimal trauma care: the role of trauma centre accreditation

PubMed Central

Simons, Richard; Kirkpatrick, Andrew

2002-01-01

Optimal care of the injured patient requires the delivery of appropriate, definitive care shortly after injury. Over the last 30 to 40 years, civilian trauma systems and trauma centres have been developed in the United States based on experience gained in military conflicts, particularly in Korea and Vietnam. A similar process is evolving in Canada. National trauma committees in the US and Canada have defined optimal resources to meet the goal of rapid, appropriate care in trauma centres. They have introduced programs (verification or accreditation) to externally audit trauma centre performance based on these guidelines. It is generally accepted that implementing trauma systems results in decreased preventable death and improved survival after trauma. What is less clear is the degree to which each facet of trauma system development contributes to this improvement. The relative importance of national performance guidelines and trauma centre audit as integral steps toward improved outcomes following injury are reviewed. Current Trauma Association of Canada guidelines for trauma centres are presented and the process of trauma centre accreditation is discussed. PMID:12174987

A radio characterization of Galactic compact bubbles

NASA Astrophysics Data System (ADS)

Ingallinera, A.; Trigilio, C.; Umana, G.; Leto, P.; Noriega-Crespo, A.; Flagey, N.; Paladini, R.; Agliozzo, C.; Buemi, C. S.

2014-02-01

We report the radio observations of a subsample of the 428 Galactic compact bubbles discovered at 24 μm with the MIPSGAL survey. Pervasive through the entire Galactic plane, these objects are thought to be different kinds of evolved stars. The very large majority of the bubbles (˜70 per cent) are however not yet classified. We conducted radio observations with the Expanded Very Large Array at 6 and 20 cm in order to obtain the spectral index of 55 bubbles. We found that at least 70 per cent of the 31 bubbles for which we were effectively able to compute the spectral index (or its lower limit) are likely to be thermal emitters. We were also able to resolve some bubbles, obtaining that the size of the radio nebula is usually similar to the IR size, although our low resolution (with respect to IR images) did not allow further morphological studies. Comparisons between radio flux densities and IR archive data from Spitzer and IRAS suggest that at least three unclassified bubbles can be treated as planetary nebula candidates.

Far-Field Noise Induced by Bubble near Free Surface

NASA Astrophysics Data System (ADS)

Ye, Xi; Li, Jiang-tao; Liu, Jian-hua; Chen, Hai-long

2018-03-01

The motion of a bubble near the free surface is solved by the boundary element method based on the linear wave equation, and the influence of fluid compressibility on bubble dynamics is analyzed. Based on the solution of the bubble motion, the far-field radiation noise induced by the bubble is calculated using Kirchhoff moving boundary integral equation, and the influence of free surface on far-field noise is researched. As the results, the oscillation amplitude of the bubble is weakened in compressible fluid compared with that in incompressible fluid, and the free surface amplifies the effect of fluid compressibility. When the distance between the bubble and an observer is much larger than that between the bubble and free surface, the sharp wave trough of the sound pressure at the observer occurs. With the increment of the distance between the bubble and free surface, the time of the wave trough appearing is delayed and the value of the wave trough increase. When the distance between the observer and the bubble is reduced, the sharp wave trough at the observer disappears.

Photothermally controlled Marangoni flow around a micro bubble

NASA Astrophysics Data System (ADS)

Namura, Kyoko; Nakajima, Kaoru; Kimura, Kenji; Suzuki, Motofumi

2015-01-01

We have experimentally investigated the control of Marangoni flow around a micro bubble using photothermal conversion. Using a focused laser spot acting as a highly localized heat source on Au nanoparticles/dielectric/Ag mirror thin film enables us to create a micro bubble and to control the temperature gradient around the bubble at a micrometer scale. When we irradiate the laser next to the bubble, a strong main flow towards the bubble and two symmetric rotation flows on either side of it develop. The shape of this rotation flow shows a significant transformation depending on the relative position of the bubble and the laser spot. Using this controllable rotation flow, we have demonstrated sorting of the polystyrene spheres with diameters of 2 μm and 0.75 μm according to their size.

Bubble fusion: Preliminary estimates

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

Krakowski, R.A.

1995-02-01

The collapse of a gas-filled bubble in disequilibrium (i.e., internal pressure {much_lt} external pressure) can occur with a significant focusing of energy onto the entrapped gas in the form of pressure-volume work and/or acoustical shocks; the resulting heating can be sufficient to cause ionization and the emission of atomic radiations. The suggestion that extreme conditions necessary for thermonuclear fusion to occur may be possible has been examined parametrically in terms of the ratio of initial bubble pressure relative to that required for equilibrium. In this sense, the disequilibrium bubble is viewed as a three-dimensional ``sling shot`` that is ``loaded`` tomore » an extent allowed by the maximum level of disequilibrium that can stably be achieved. Values of this disequilibrium ratio in the range 10{sup {minus}5}--10{sup {minus}6} are predicted by an idealized bubble-dynamics model as necessary to achieve conditions where nuclear fusion of deuterium-tritium might be observed. Harmonic and aharmonic pressurizations/decompressions are examined as means to achieve the required levels of disequilibrium required to create fusion conditions. A number of phenomena not included in the analysis reported herein could enhance or reduce the small levels of nuclear fusions predicted.« less

The collapse of a cavitation bubble in a corner

NASA Astrophysics Data System (ADS)

Peters, Ivo; Tagawa, Yoshiyuki

2017-11-01

The collapse of cavitation bubbles is influenced by the surrounding geometry. A classic example is the collapse of a bubble near a solid wall, where a fast jet is created towards the wall. The addition of a second wall creates a non-axisymmetric flow field, which influences the displacement and jet formation during the collapse of a bubble. In this experimental study we generate mm-sized vapor bubbles using a focused pulsed laser, giving us full control over the position of the bubble. The corner geometry is formed by two glass slides. High-speed imaging reveals the directional motion of the bubble during the collapse. We find that the bubble displacement cannot be fully described by a simple superposition of the bubble dynamics of the two walls individually. Comparison of our experimental results to a model based on potential flow shows a good agreement for the direction of displacement.

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.

Eternal inflation, bubble collisions, and the persistence of memory

NASA Astrophysics Data System (ADS)

Garriga, Jaume; Guth, Alan H.; Vilenkin, Alexander

2007-12-01

A “bubble universe” nucleating in an eternally inflating false vacuum will experience, in the course of its expansion, collisions with an infinite number of other bubbles. In an idealized model, we calculate the rate of collisions around an observer inside a given reference bubble. We show that the collision rate violates both the homogeneity and the isotropy of the bubble universe. Each bubble has a center which can be related to “the beginning of inflation” in the parent false vacuum, and any observer not at the center will see an anisotropic bubble collision rate that peaks in the outward direction. Surprisingly, this memory of the onset of inflation persists no matter how much time elapses before the nucleation of the reference bubble.

Behavior of bubbles in glassmelts. II - Dissolution of a stationary bubble containing a diffusing and a nondiffusing gas

NASA Technical Reports Server (NTRS)

Weinberg, M. C.; Onorato, P. I. K.; Uhlmann, D. R.

1980-01-01

The effect of a foreign nondiffusing gas on the rate of shrinkage of an oxygen bubble in a soda-lime-silica melt was studied. The rate of change of bubble radius with time was computed using the quasi-stationary approximation. The effects of melt undersaturation and initial fraction of foreign gas in the bubble are considered and compared with those calculated using previously derived expressions.

Bubble-Free Containers For Liquids In Microgravity

NASA Technical Reports Server (NTRS)

Kornfeld, Dale M.; Antar, Basil L.

1995-01-01

Reports discuss entrainment of gas bubbles during handling of liquids in microgravity, and one report proposes containers filled with liquids in microgravity without entraining bubbles. Bubbles are troublesome in low-gravity experiments - particularly in biological experiments. Wire-mesh cage retains liquid contents without solid wall, because in microgravity, surface tension of liquid exerts sufficient confining force.

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.

Transformer overload and bubble evolution: Proceedings

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

Addis, G.; Lindgren, S.

1988-06-01

The EPRI workshop on Transformer Overload Characteristics and Bubble Evolution was held to review the findings of investigations over the past 7-8 years to determine whether enough information is now available for utilities to establish safe loading practices. Sixteen papers were presented, including a utility review, physical and dielectric effects of gas and bubble formation from cellulose insulated transformers, transformer life characteristics, gas bubble studies and impulse test on distribution transformers, mathematical modeling of bubble evolution, transformer overload characteristics, variation of PD-strength for oil-paper insulation, survey on maximum safe operating hot spot temperature, and overload management. The meeting concluded withmore » a general discussion covering the existing state of knowledge and the need for additional research. Sixteen papers have been cataloged separately.« less

An Analysis of Bubble Deformation by a Sphere Relevant to the Measurements of Bubble-Particle Contact Interaction and Detachment Forces.

PubMed

Sherman, H; Nguyen, A V; Bruckard, W

2016-11-22

Atomic force microscopy makes it possible to measure the interacting forces between individual colloidal particles and air bubbles, which can provide a measure of the particle hydrophobicity. To indicate the level of hydrophobicity of the particle, the contact angle can be calculated, assuming that no interfacial deformation occurs with the bubble retaining a spherical profile. Our experimental results obtained using a modified sphere tensiometry apparatus to detach submillimeter spherical particles show that deformation of the bubble interface does occur during particle detachment. We also develop a theoretical model to describe the equilibrium shape of the bubble meniscus at any given particle position, based on the minimization of the free energy of the system. The developed model allows us to analyze high-speed video captured during detachment. In the system model deformation of the bubble profile is accounted for by the incorporation of a Lagrange multiplier into both the Young-Laplace equation and the force balance. The solution of the bubble profile matched to the high-speed video allows us to accurately calculate the contact angle and determine the total force balance as a function of the contact point of the bubble on the particle surface.

Bubble behavior characteristics based on virtual binocular stereo vision

NASA Astrophysics Data System (ADS)

Xue, Ting; Xu, Ling-shuang; Zhang, Shang-zhen

2018-01-01

The three-dimensional (3D) behavior characteristics of bubble rising in gas-liquid two-phase flow are of great importance to study bubbly flow mechanism and guide engineering practice. Based on the dual-perspective imaging of virtual binocular stereo vision, the 3D behavior characteristics of bubbles in gas-liquid two-phase flow are studied in detail, which effectively increases the projection information of bubbles to acquire more accurate behavior features. In this paper, the variations of bubble equivalent diameter, volume, velocity and trajectory in the rising process are estimated, and the factors affecting bubble behavior characteristics are analyzed. It is shown that the method is real-time and valid, the equivalent diameter of the rising bubble in the stagnant water is periodically changed, and the crests and troughs in the equivalent diameter curve appear alternately. The bubble behavior characteristics as well as the spiral amplitude are affected by the orifice diameter and the gas volume flow.

Visualization of the wake behind a sliding bubble

NASA Astrophysics Data System (ADS)

O'Reilly Meehan, R.; Grennan, K.; Davis, I.; Nolan, K.; Murray, D. B.

2017-10-01

In this work, Schlieren measurements are presented for the wake of an air bubble sliding under a heated, inclined surface in quiescent water to provide new insights into the intricate sliding bubble wake structure and the associated convective cooling process. This is a two-phase flow configuration that is pertinent to thermal management solutions, where the fundamental flow physics have yet to be fully described. In this work, we present an experimental apparatus that enables high-quality Schlieren images for different bubble sizes and measurement planes. By combining these visualizations with an advanced bubble tracking technique, we can simultaneously quantify the symbiotic relationship that exists between the sliding bubble dynamics and its associated wake. An unstable, dynamic wake structure is revealed, consisting of multiple hairpin-shaped vortex structures interacting within the macroscopic area affected by the bubble. As vorticity is generated in the near wake, the bubble shape is observed to recoil and rebound. This also occurs normal to the surface and is particularly noticeable for larger bubble sizes, with a periodic ejection of material from the near wake corresponding to significant shape changes. These findings, along with their implications from a thermal management perspective, provide information on the rich dynamics of this natural flow that cannot be obtained using alternate experimental techniques.

Can airborne ultrasound monitor bubble size in chocolate?

NASA Astrophysics Data System (ADS)

Watson, N.; Hazlehurst, T.; Povey, M.; Vieira, J.; Sundara, R.; Sandoz, J.-P.

2014-04-01

Aerated chocolate products consist of solid chocolate with the inclusion of bubbles and are a popular consumer product in many countries. The volume fraction and size distribution of the bubbles has an effect on their sensory properties and manufacturing cost. For these reasons it is important to have an online real time process monitoring system capable of measuring their bubble size distribution. As these products are eaten by consumers it is desirable that the monitoring system is non contact to avoid food contaminations. In this work we assess the feasibility of using an airborne ultrasound system to monitor the bubble size distribution in aerated chocolate bars. The experimental results from the airborne acoustic experiments were compared with theoretical results for known bubble size distributions using COMSOL Multiphysics. This combined experimental and theoretical approach is used to develop a greater understanding of how ultrasound propagates through aerated chocolate and to assess the feasibility of using airborne ultrasound to monitor bubble size distribution in these systems. The results indicated that a smaller bubble size distribution would result in an increase in attenuation through the product.

Shock waves from non-spherically collapsing cavitation bubbles

NASA Astrophysics Data System (ADS)

Supponen, Outi; Obreschkow, Danail; Farhat, Mohamed

2017-11-01

Combining simultaneous high-speed imaging and hydrophone measurements, we uncover details of the multiple shock wave emission from laser-induced cavitation bubbles collapsing in a non-spherical way. For strongly deformed bubbles collapsing near a free surface, we identify the distinct shock waves caused by the jet impact onto the opposite bubble wall and by the individual collapses of the remaining bubble segments. The energy carried by each of these shocks depends on the level of bubble deformation, quantified by the anisotropy parameter ζ, the dimensionless equivalent of the Kelvin impulse. For jetting bubbles, at ζ < 0.01 , the jet impact hammer pressure is found to be the most energetic shock. Through statistical analysis of the experimental data and theoretical derivations, and by comparing bubbles deformed by different sources (variable gravity achieved on parabolic flights, and neighboring free and rigid surfaces), we find that the shock peak pressure may be approximated as the jet impact-induced water hammer as ph = 0.45 (ρc2 Δp) 1 / 2ζ-1 .

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

Colorful Demos with a Long-Lasting Soap Bubble.

ERIC Educational Resources Information Center

Behroozi, F.; Olson, D. W.

1994-01-01

Describes several demonstrations that feature interaction of light with soap bubbles. Includes directions about how to produce a long-lasting stationary soap bubble with an easily changeable size and describes the interaction of white light with the bubble. (DDR)

Dynamics of diffusive bubble growth and pressure recovery in a bubbly rhyolitic melt embedded in an elastic solid

USGS Publications Warehouse

Chouet, Bernard A.; Dawson, Phillip B.; Nakano, Masaru

2006-01-01

We present a model of gas exsolution and bubble expansion in a melt supersaturated in response to a sudden pressure drop. In our model, the melt contains a suspension of gas bubbles of identical sizes and is encased in a penny-shaped crack embedded in an elastic solid. The suspension is modeled as a three-dimensional lattice of spherical cells with slight overlap, where each elementary cell consists of a gas bubble surrounded by a shell of volatile-rich melt. The melt is then subjected to a step drop in pressure, which induces gas exsolution and bubble expansion, resulting in the compression of the melt and volumetric expansion of the crack. The dynamics of diffusion-driven bubble growth and volumetric crack expansion span 9 decades in time. The model demonstrates that the speed of the crack response depends strongly on volatile diffusivity in the melt and bubble number density and is markedly sensitive to the ratio of crack thickness to crack radius and initial bubble radius but is relatively insensitive to melt viscosity. The net drop in gas concentration in the melt after pressure recovery represents only a small fraction of the initial concentration prior to the drop, suggesting the melt may undergo numerous pressure transients before becoming significantly depleted of gases. The magnitude of pressure and volume recovery in the crack depends sensitively on the size of the input-pressure transient, becoming relatively larger for smaller-size transients in a melt containing bubbles with initial radii less than 10-5 m. Amplification of the input transient may be large enough to disrupt the crack wall and induce brittle failure in the rock matrix surrounding the crack. Our results provide additional basis for the interpretation of volume changes in the magma conduit under Popocatépetl Volcano during Vulcanian degassing bursts in its eruptive activity in April–May 2000.

Systemic trauma.

PubMed

Goldsmith, Rachel E; Martin, Christina Gamache; Smith, Carly Parnitzke

2014-01-01

Substantial theoretical, empirical, and clinical work examines trauma as it relates to individual victims and perpetrators. As trauma professionals, it is necessary to acknowledge facets of institutions, cultures, and communities that contribute to trauma and subsequent outcomes. Systemic trauma-contextual features of environments and institutions that give rise to trauma, maintain it, and impact posttraumatic responses-provides a framework for considering the full range of traumatic phenomena. The current issue of the Journal of Trauma & Dissociation is composed of articles that incorporate systemic approaches to trauma. This perspective extends conceptualizations of trauma to consider the influence of environments such as schools and universities, churches and other religious institutions, the military, workplace settings, hospitals, jails, and prisons; agencies and systems such as police, foster care, immigration, federal assistance, disaster management, and the media; conflicts involving war, torture, terrorism, and refugees; dynamics of racism, sexism, discrimination, bullying, and homophobia; and issues pertaining to conceptualizations, measurement, methodology, teaching, and intervention. Although it may be challenging to expand psychological and psychiatric paradigms of trauma, a systemic trauma perspective is necessary on both scientific and ethical grounds. Furthermore, a systemic trauma perspective reflects current approaches in the fields of global health, nursing, social work, and human rights. Empirical investigations and intervention science informed by this paradigm have the potential to advance scientific inquiry, lower the incidence of a broader range of traumatic experiences, and help to alleviate personal and societal suffering.

Remobilizing the Interfaces of Thermocapillary Driven Bubbles Retarded by the Adsorption of a Surfactant Impurity on the Bubble Surface

NASA Technical Reports Server (NTRS)

Palaparthi, Ravi; Maldarelli, Charles; Papageorgiou, Dimitri; Singh, Bhim S. (Technical Monitor)

2000-01-01

Thermocapillary migration is a method for moving bubbles in space in the absence of buoyancy. A temperature gradient is applied to the continuous phase in which a bubble is situated, and the applied gradient impressed on the bubble surface causes one pole of the drop to be cooler than the opposite pole. As the surface tension is a decreasing function of temperature, the cooler pole pulls at the warmer pole, creating a flow which propels the bubble in the direction of the warmer fluid. A major impediment to the practical use of thermocapillarity to direct the movement of bubbles in space is the fact that surfactant impurities which are unavoidably present in the continuous phase can significantly reduce the migration velocity. A surfactant impurity adsorbed onto the bubble interface is swept to the trailing end of the bubble. When bulk concentrations are low (which is the case with an impurity), diffusion of surfactant to the front end is slow relative to convection, and surfactant collects at the back end of the bubble. Collection at the back lowers the surface tension relative to the front end setting up a reverse tension gradient. For buoyancy driven bubble motions in the absence of a thermocapillarity, the tension gradient opposes the surface flow, and reduces the surface and terminal velocities (the interface becomes more solid-like). When thermocapillary forces are present, the reverse tension gradient set up by the surfactant accumulation reduces the temperature tension gradient, and decreases to near zero the thermocapillary velocity. The objective of our research is to develop a method for enhancing the thermocapillary migration of bubbles which have been retarded by the adsorption onto the bubble surface of a surfactant impurity, Our remobilization theory proposes to use surfactant molecules which kinetically rapidly exchange between the bulk and the surface and are at high bulk concentrations. Because the remobilizing surfactant is present at much higher

Helium bubbles aggravated defects production in self-irradiated copper

NASA Astrophysics Data System (ADS)

Wu, FengChao; Zhu, YinBo; Wu, Qiang; Li, XinZhu; Wang, Pei; Wu, HengAn

2017-12-01

Under the environment of high radiation, materials used in fission and fusion reactors will internally accumulate numerous lattice defects and bubbles. With extensive studies focused on bubble resolution under irradiation, the mutually effects between helium bubbles and displacement cascades in irradiated materials remain unaddressed. Therefore, the defects production and microstructure evolution under self-irradiation events in vicinity of helium bubbles are investigated by preforming large scale molecular dynamics simulations in single-crystal copper. When subjected to displacement cascades, distinguished bubble resolution categories dependent on bubble size are observed. With the existence of bubbles, radiation damage is aggravated with the increasing bubble size, represented as the promotion of point defects and dislocations. The atomic mechanisms of heterogeneous dislocation structures are attributed to different helium-vacancy cluster modes, transforming from the resolved gas trapped with vacancies to the biased absorption of vacancies by the over-pressured bubble. In both cases, helium impedes the recombination of point defects, leading to the accelerated formation of interstitial loops. The results and insight obtained here might contribute to understand the underlying mechanism of transmutant solute on the long-term evolution of irradiated materials.

What selects the velocity of fingers and bubbles in a Hele-Shaw cell?

NASA Astrophysics Data System (ADS)

Vasconcelos, Giovani; Mineev-Weinstein, Mark; Brum, Arthur

2017-11-01

It has been widely accepted that surface tension is responsible for the selection of a single pattern out of a continuum of steady solutions for the interface dynamics. Recently, however, it was demonstrated by using time-dependent solutions that surface tension is not required for velocity selection in a Hele-Shaw cell: the velocity is selected entirely within the zero surface tension dynamics, as the selected pattern is the only attractor of the dynamics. These works changed the paradigm regarding the necessity of surface tension for selection, but were limited to a single interface. Here we show that the same selection mechanism holds for any number of interfaces. We present a new class of exact solutions for multiple time-evolving bubbles in a Hele-Shaw cell. The solution is given by a conformal mapping from a multiply connected domain and is written in closed form in terms of certain special functions (the secondary Schottky-Klein prime functions). We demonstrate that the bubbles reach an asymptotic steady velocity, U, which is twice greater than the velocity, V, of the uniform background flow, i.e., U = 2 V . The result does not depend on the number of bubbles. This confirms the prediction that contrary to common belief velocity selection does not require surface tension

Treating Women Drug Abusers: Action Therapy and Trauma Assessment

PubMed Central

Uhler, Ann S.; Parker, Olga V.

2002-01-01

The authors suggest that action therapy, a group of techniques including psychodrama, drama therapy, and role training, warrants research attention to determine whether it is well suited to the special characteristics and needs of women clients. In addition, the authors call on researchers to develop a new standardized tool for counselors to use during initial interviews to determine whether women presenting for drug abuse treatment also have significant issues related to trauma. The authors believe the use of unassisted clinical judgment for trauma assessment in first interviews may drive patients away by probing for painful information that clients are not yet ready to confront or divulge. PMID:18567963

Treating women drug abusers: action therapy and trauma assessment.

PubMed

Uhler, Ann S; Parker, Olga V

2002-07-01

The authors suggest that action therapy, a group of techniques including psychodrama, drama therapy, and role training, warrants research attention to determine whether it is well suited to the special characteristics and needs of women clients. In addition, the authors call on researchers to develop a new standardized tool for counselors to use during initial interviews to determine whether women presenting for drug abuse treatment also have significant issues related to trauma. The authors believe the use of unassisted clinical judgment for trauma assessment in first interviews may drive patients away by probing for painful information that clients are not yet ready to confront or divulge.

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.

Beer tapping: dynamics of bubbles after impact

NASA Astrophysics Data System (ADS)

Mantič-Lugo, V.; Cayron, A.; Brun, P.-T.; Gallaire, F.

2015-12-01

Beer tapping is a well known prank where a bottle of beer is impacted from the top by a solid object, usually another bottle, leading to a sudden foam overflow. A description of the shock-driven bubble dynamics leading to foaming is presented based on an experimental and numerical study evoking the following physical picture. First, the solid impact produces a sudden downwards acceleration of the bottle creating a strong depression in the liquid bulk. The existing bubbles undergo a strong expansion and a sudden contraction ending in their collapse and fragmentation into a large amount of small bubbles. Second, the bubble clouds present a large surface area to volume ratio, enhancing the CO2 diffusion from the supersaturated liquid, hence growing rapidly and depleting the CO2. The clouds of bubbles migrate upwards in the form of plumes pulling the surrounding liquid with them and eventually resulting in the foam overflow. The sudden pressure drop that triggers the bubble dynamics with a collapse and oscillations is modelled by the Rayleigh-Plesset equation. The bubble dynamics from impact to collapse occurs over a time (tb ≃ 800 μs) much larger than the acoustic time scale of the liquid bulk (tac = 2H/c ≃ 80 μs), for the experimental container of height H = 6 cm and a speed of sound around c ≃ 1500 m/s. This scale separation, together with the comparison of numerical and experimental results, suggests that the pressure drop is controlled by two parameters: the acceleration of the container and the distance from the bubble to the free surface.

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.

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.

Primordial black hole formation by vacuum bubbles

NASA Astrophysics Data System (ADS)

Deng, Heling; Vilenkin, Alexander

2017-12-01

Vacuum bubbles may nucleate during the inflationary epoch and expand, reaching relativistic speeds. After inflation ends, the bubbles are quickly slowed down, transferring their momentum to a shock wave that propagates outwards in the radiation background. The ultimate fate of the bubble depends on its size. Bubbles smaller than certain critical size collapse to ordinary black holes, while in the supercritical case the bubble interior inflates, forming a baby universe, which is connected to the exterior region by a wormhole. The wormhole then closes up, turning into two black holes at its two mouths. We use numerical simulations to find the masses of black holes formed in this scenario, both in subcritical and supercritical regime. The resulting mass spectrum is extremely broad, ranging over many orders of magnitude. For some parameter values, these black holes can serve as seeds for supermassive black holes and may account for LIGO observations.

Acoustic Behavior of Vapor Bubbles

NASA Technical Reports Server (NTRS)

Prosperetti, Andrea; Oguz, Hasan N.

1996-01-01

In a microgravity environment vapor bubbles generated at a boiling surface tend to remain near it for a long time. This affects the boiling heat transfer and in particular promotes an early transition to the highly inefficient film boiling regime. This paper describes the physical basis underlying attempts to remove the bubbles by means of pressure radiation forces.

Advanced detectors and signal processing for bubble memories

NASA Technical Reports Server (NTRS)

Kryder, M. H.; Rasky, P. H. L.; Greve, D. W.

1985-01-01

The feasibility of combining silicon and magnetic bubble technologies is demonstrated. Results of bubble film annealing indicate that a low temperature silicon on garnet technology is the most likely one to succeed commercially. Annealing ambients are also shown to have a major effect on the magnetic properties of bubble films. Functional MOSFETs were fabricated on bubble films coated with thick (approximately 1 micron) SiO2 layers. The two main problems with these silicon on garnet MOSFETs are low electron mobilities and large gate leakage currents. Results indicate that the laser recrystallized silicon and gate oxide (SiO2) layers are contaminated. The data suggest that part of the contaminating ions originate in the sputtered oxide spacer layer and part originates in the bubble film itself. A diffusion barrier, such as silicon nitride, placed between the bubble film and the silicon layer should eliminate the contamination induced problem.

The acoustic environment of a sonoluminescing bubble

NASA Astrophysics Data System (ADS)

Holzfuss, Joachim; Rüggeberg, Matthias; Holt, R. Glynn

2000-07-01

A bubble is levitated in water in a cylindrical resonator which is driven by ultrasound. It has been shown that in a certain region of parameter space the bubble is emitting light pulses (sonoluminescence). One of the properties observed is the enormous spatial stability leaving the bubble "pinned" in space allowing it to emit light with a timing of picosecond accuracy. We argue that the observed stability is due to interactions of the bubble with the resonator. A shock wave emitted at collapse time together with a self generated complex sound field, which is experimentally mapped with high resolution, is responsible for the observed effects.

A simple bubble-flowmeter with quasicontinuous registration.

PubMed

Ludt, H; Herrmann, H D

1976-07-22

The construction of a simple bubble-flow-meter is described. The instrument has the following features: 1. automatic bubble injection, 2. precise measurement of the bubble passage time by a digital counter, 3. quasicontinuous registration of the flow rate, 4. alternative run with clear fluid (water) and coloured fluid (blood), 5. low volume, 6. closed measuring system for measurements in low and high pressure systems.

Bubble Formation Modeling in IE-911

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

Fondeur, F.F.

2000-09-27

The author used diffusion modeling to determine the hydrogen and oxygen concentration inside IE-911. The study revealed gas bubble nucleation will not occur in the bulk solution inside the pore or on the pore wall. This finding results from the fast oxygen and hydrogen gas molecular diffusion and a very confined pore space. The net steady state concentration of these species inside the pore proves too low to drive bubble nucleation. This study did not investigate other gas bubble nucleating mechanism such as suspended particles in solution.

Nonlinear Bubble Interactions in Acoustic Pressure Fields

NASA Technical Reports Server (NTRS)

Barbat, Tiberiu; Ashgriz, Nasser; Liu, Ching-Shi

1996-01-01

The systems consisting of a two-phase mixture, as clouds of bubbles or drops, have shown many common features in their responses to different external force fields. One of particular interest is the effect of an unsteady pressure field applied to these systems, case in which the coupling of the vibrations induced in two neighboring components (two drops or two bubbles) may result in an interaction force between them. This behavior was explained by Bjerknes by postulating that every body that is moving in an accelerating fluid is subjected to a 'kinetic buoyancy' equal with the product of the acceleration of the fluid multiplied by the mass of the fluid displaced by the body. The external sound wave applied to a system of drops/bubbles triggers secondary sound waves from each component of the system. These secondary pressure fields integrated over the surface of the neighboring drop/bubble may result in a force additional to the effect of the primary sound wave on each component of the system. In certain conditions, the magnitude of these secondary forces may result in significant changes in the dynamics of each component, thus in the behavior of the entire system. In a system containing bubbles, the sound wave radiated by one bubble at the location of a neighboring one is dominated by the volume oscillation mode and its effects can be important for a large range of frequencies. The interaction forces in a system consisting of drops are much smaller than those consisting of bubbles. Therefore, as a first step towards the understanding of the drop-drop interaction subject to external pressure fluctuations, it is more convenient to study the bubble interactions. This paper presents experimental results and theoretical predictions concerning the interaction and the motion of two levitated air bubbles in water in the presence of an acoustic field at high frequencies (22-23 KHz).

Convection in a volcanic conduit recorded by bubbles

USGS Publications Warehouse

Carey, Rebecca J.; Manga, Michael; Degruyter, Wim; Gonnermann, Helge M.; Swanson, Donald; Houghton, Bruce F.; Orr, Tim R.; Patrick, Matthew R.

2013-01-01

Microtextures of juvenile pyroclasts from Kīlauea’s (Hawai‘i) early A.D. 2008 explosive activity record the velocity and depth of convection within the basaltic magma-filled conduit. We use X-ray microtomography (μXRT) to document the spatial distribution of bubbles. We find small bubbles (radii from 5 μm to 70 μm) in a halo surrounding larger millimeter-size bubbles. This suggests that dissolved water was enriched around the larger bubbles—the opposite of what is expected if bubbles grow as water diffuses into the bubble. Such volatile enrichment implies that the volatiles within the large bubbles were redissolving into the melt as they descended into the conduit by the downward motion of convecting magma within the lava lake. The thickness of the small bubble halo is ∼100–150 μm, consistent with water diffusing into the melt on time scales on the order of 103 s. Eruptions, triggered by rockfall, rapidly exposed this magma to lower pressures, and the haloes of melt with re-dissolved water became sufficiently supersaturated to cause nucleation of the population of smaller bubbles. The required supersaturation pressures are consistent with a depth of a few hundred meters and convection velocities of the order of 0.1 m s−1, similar to the circulation velocity observed on the surface of the Halema‘uma‘u lava lake.

Perfectly monodisperse micro-bubble production by novel mechanical means. Scaling laws.

NASA Astrophysics Data System (ADS)

Ganan-Calvo, Alfonso M.; Gordillo, Jose M.; Ouarti, Nawel; Prevost, Thomas; Sampedro, Jose L.

2000-11-01

A continuous stream of controllable, perfectly homogeneous size micro-bubbles (of the order of some microns and larger) can be produced by a novel, extremely simple mechanical means that we call "Flow Focusing" (e.g. see Ganan-Calvo 1998, Phys. Rev. Lett. vol. 80, 285). Using this technique, a capillary gas micro-jet is formed ("focused") by a co-flowing stream of liquid forced through a sub-millimetric orifice. This gas micro-jet undergoes a rapid capillary breakup (e.g. Chandrasekhar 1961 "Hydrodynamic and Hydromagnetic Stability", p. 541) with a strong frequency "self-locking" effect. In this work we present a theoretical model which predicts the micro-bubble size as a function of the physical and geometrical parameters of the system. A complete experimental study is also provided, and the raw data are collapsed into a universal scaling law given by our theoretical model. This novel micro-fluidics phenomenon may have a wide variety of applications ranging from bio-medicine, pharmaceutical specialities, food industry, and even for the mesoscale micro-templating of micro-engineered materials (i.e. photonic crystals, smart materials, etc.).

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.

Bubbles in extended inflation and multi-production of universes

NASA Astrophysics Data System (ADS)

Sakai, Nobuyuki; Maeda, Kei-ichi

Developing the thin-wall method of Israel, we present a formalism to investigate bubble dynamics in generalized Einstein theories. We derive the equations of motion for a bubble, finding that the space-time inside a bubble is always inhomogeneous. Applying this formalism to extended inflation, we find the following two results: (1) Any true vacuum bubble expands, contrary to the results of Goldwirth-Zaglauer, who claim that bubbles created initially later collapse. We show that their initial conditions for collapsing bubbles are physically inconsistent. (2) Concerning the global space-time structure of the Universe in extended inflation, we show that worm-holes are produced as in old inflation, resulting in the multi-production of universes.

GAS AND BUBBLE PRODUCTION BY SIPHONOPHORES.

DTIC Science & Technology

Gas-filled siphonophore floats collected from a deep scattering layer (DSL) were photographed in the act of voluntarily expelling bubbles of nearly...Such free bubbles, together with the siphonophore floats themselves, constitute a biological family of potentially resonant sonar targets

Gas separation and bubble behavior at a woven screen

NASA Astrophysics Data System (ADS)

Conrath, Michael; Dreyer, Michael E.

Gas-liquid two phase flows are widespread and in many applications the separation of both phases is necessary. Chemical reactors, water treatment devices or gas-free delivery of liquids like propellant are only some of them. We study the performance of a woven metal screen in respect to its phase separation behavior under static and dynamic conditions. Beside hydraulic screen resistance and static bubble point, our study also comprises the bubble detachment from the screen upon gas breakthrough. Since a woven screen is essentially an array of identical pores, analogies to bubble detachment from a needle can be established. While the bubble point poses an upper limit for pressurized gas at a wetted screen to preclude gas breakthrough, the necessary pressure for growing bubbles to detach from the screen pores a lower limit when breakthrough is already in progress. Based on that inside, the dynamic bubble point effects were constituted that relate to a trapped bubble at such a screen in liquid flow. A trapped is caused to break through the screen by the flow-induced pressure drop across it. Our model includes axially symmetric bubble shapes, degree of coverage of the screen and bubble pressurization due to hydraulic losses in the rest of the circuit. We have built an experiment that consists of a Dutch Twilled woven screen made of stainless steel in a vertical acrylic glass tube. The liquid is silicon oil SF0.65. The screen is suspended perpendicular to the liquid flow which is forced through it at variable flow rate. Controlled injection of air from a needle allows us to examine the ability of the screen to separate gas and liquid along the former mentioned effects. We present experimental data on static bubble point and detachment pressure for breakthrough at different gas supply rates that suggest a useful criterion for reliable static bubble point measurements. Results for the dynamic bubble point are presented that include i) screen pressure drop for different

A computationally efficient modelling of laminar separation bubbles

NASA Technical Reports Server (NTRS)

Maughmer, Mark D.

1988-01-01

The goal of this research is to accurately predict the characteristics of the laminar separation bubble and its effects on airfoil performance. To this end, a model of the bubble is under development and will be incorporated in the analysis section of the Eppler and Somers program. As a first step in this direction, an existing bubble model was inserted into the program. It was decided to address the problem of the short bubble before attempting the prediction of the long bubble. In the second place, an integral boundary-layer method is believed more desirable than a finite difference approach. While these two methods achieve similar prediction accuracy, finite-difference methods tend to involve significantly longer computer run times than the integral methods. Finally, as the boundary-layer analysis in the Eppler and Somers program employs the momentum and kinetic energy integral equations, a short-bubble model compatible with these equations is most preferable.

Bubble-induced microstreaming: guiding and destroying lipid vesicles

NASA Astrophysics Data System (ADS)

Marmottant, Philippe; Hilgenfeldt, Sascha

2002-11-01

Micron-sized bubbles respond with strong oscillations when submitted to ultrasound. This has led to their use as echographic contrast enhancers. The large energy and force densities generated by the collapsing bubbles also make them non-invasive mechanical tools: Recently, it has been reported that the interaction of cavitating bubbles with nearby cells can render the latter permeable to large molecules (sonoporation), suggesting prospects for drug delivery and gene transfection. We have developed a laboratory setup that allows for a controlled study of the interaction of single microbubbles with single lipid bilayer vesicles. Substituting vesicles for cell membranes is advantageous because the mechanical properties of vesicles are well-known. Microscopic observations reveal that vesicles near a bubble follow the vivid streaming motion set up by the bubble. The vesicles "bounce" off the bubble, being periodically accelerated towards and away from it, and undergo well-defined shape deformations along their trajectory in accordance with fluid-dynamical theory. Break-up of vesicles could also be observed.

OH Production Enhancement in Bubbling Pulsed Discharges

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

Lungu, Cristian P.; Porosnicu, Corneliu; Jepu, Ionut

2010-10-13

The generation of active species, such as H{sub 2}O{sub 2}, O{sup *}, OH*, HO{sub 2}*, O{sub 3}, N{sub 2}{sup *}, etc, produced in aqueous solutions by HV pulsed discharges was studied in order to find the most efficient way in waste water treatment taking into account that these species are almost stronger oxidizers than ozone. Plasma was generated inside gas bubbles formed by the argon, air and oxygen gas flow between the special designed electrodes. The pulse width and pulse frequency influence was studied in order to increase the efficiency of the OH active species formation. The produced active speciesmore » were investigated by optical emission spectroscopy and correlated with electrical parameters of the discharges (frequency, pulse width, amplitude, and rise and decay time).« less

Luminescence from cavitation bubbles deformed in uniform pressure gradients

NASA Astrophysics Data System (ADS)

Supponen, Outi; Obreschkow, Danail; Kobel, Philippe; Farhat, Mohamed

2017-09-01

Presented here are observations that demonstrate how the deformation of millimetric cavitation bubbles by a uniform pressure gradient quenches single-collapse luminescence. Our innovative measurement system captures a broad luminescence spectrum (wavelength range, 300-900 nm) from the individual collapses of laser-induced bubbles in water. By varying the bubble size, driving pressure, and perceived gravity level aboard parabolic flights, we probed the limit from aspherical to highly spherical bubble collapses. Luminescence was detected for bubbles of maximum radii within the previously uncovered range, R0=1.5 -6 mm, for laser-induced bubbles. The relative luminescence energy was found to rapidly decrease as a function of the bubble asymmetry quantified by the anisotropy parameter ζ , which is the dimensionless equivalent of the Kelvin impulse. As established previously, ζ also dictates the characteristic parameters of bubble-driven microjets. The threshold of ζ beyond which no luminescence is observed in our experiment closely coincides with the threshold where the microjets visibly pierce the bubble and drive a vapor jet during the rebound. The individual fitted blackbody temperatures range between Tlum=7000 and Tlum=11 500 K but do not show any clear trend as a function of ζ . Time-resolved measurements using a high-speed photodetector disclose multiple luminescence events at each bubble collapse. The averaged full width at half-maximum of the pulse is found to scale with R0 and to range between 10 and 20 ns.

Short term evaluation of respiratory effort by premature infants supported with bubble nasal continuous airway pressure using Seattle-PAP and a standard bubble device

PubMed Central

Welty, Stephen E.; Rusin, Craig G.; Stanberry, Larissa I.; Mandy, George T.; Gest, Alfred L.; Ford, Jeremy M.; Backes, Carl H.; Richardson, C. Peter; Howard, Christopher R.; Hansen, Thomas N.

2018-01-01

Background Almost one million prematurely born infants die annually from respiratory insufficiency, predominantly in countries with limited access to respiratory support for neonates. The primary hypothesis tested in the present study was that a modified device for bubble nasal continuous positive airway pressure (Bn-CPAP) would provide lower work of spontaneous breathing, estimated by esophageal pressure-rate products. Methods Infants born <32 weeks gestation and stable on Bn-CPAP with FiO2 <0.30 were studied within 72 h following delivery. Esophageal pressures during spontaneous breathing were measured during 2 h on standard Bn-CPAP, then 2 h with Bn-CPAP using a modified bubble device presently termed Seattle-PAP, which produces a different pattern of pressure fluctuations and which provided greater respiratory support in preclinical studies, then 2 h on standard Bn-CPAP. Results All 40 infants enrolled completed the study and follow-up through 36 wks post menstrual age or hospital discharge, whichever came first. No infants were on supplemental oxygen at completion of follow-up. No infants developed pneumothoraces or nasal trauma, and no adverse events attributed to the study were observed. Pressure-rate products on the two devices were not different, but effort of breathing, assessed by areas under esophageal pressure-time curves, was lower with Seattle-PAP than with standard Bn-CPAP. Conclusion Use of Seattle-PAP to implement Bn-CPAP lowers the effort of breathing exerted even by relatively healthy spontaneously breathing premature neonates. Whether the lower effort of breathing observed with Seattle-PAP translates to improvements in neonatal mortality or morbidity will need to be determined by studies in appropriate patient populations. PMID:29590143

21 CFR 870.4205 - Cardiopulmonary bypass bubble detector.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Cardiopulmonary bypass bubble detector. 870.4205 Section 870.4205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... bypass bubble detector. (a) Identification. A cardiopulmonary bypass bubble detector is a device used to...

21 CFR 870.4205 - Cardiopulmonary bypass bubble detector.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cardiopulmonary bypass bubble detector. 870.4205 Section 870.4205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... bypass bubble detector. (a) Identification. A cardiopulmonary bypass bubble detector is a device used to...

21 CFR 870.4205 - Cardiopulmonary bypass bubble detector.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Cardiopulmonary bypass bubble detector. 870.4205 Section 870.4205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... bypass bubble detector. (a) Identification. A cardiopulmonary bypass bubble detector is a device used to...

21 CFR 870.4205 - Cardiopulmonary bypass bubble detector.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Cardiopulmonary bypass bubble detector. 870.4205 Section 870.4205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... bypass bubble detector. (a) Identification. A cardiopulmonary bypass bubble detector is a device used to...

21 CFR 870.4205 - Cardiopulmonary bypass bubble detector.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Cardiopulmonary bypass bubble detector. 870.4205 Section 870.4205 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... bypass bubble detector. (a) Identification. A cardiopulmonary bypass bubble detector is a device used to...

Shock wave interaction with laser-generated single bubbles.

PubMed

Sankin, G N; Simmons, W N; Zhu, S L; Zhong, P

2005-07-15

The interaction of a lithotripter shock wave (LSW) with laser-generated single vapor bubbles in water is investigated using high-speed photography and pressure measurement via a fiber-optic probe hydrophone. The interaction leads to nonspherical collapse of the bubble with secondary shock wave emission and microjet formation along the LSW propagation direction. The maximum pressure amplification is produced during the collapse phase of the bubble oscillation when the compressive pulse duration of the LSW matches with the forced collapse time of the bubble.

Scaling and Instabilities in Bubble Pinch-Off

NASA Astrophysics Data System (ADS)

Burton, J. C.; Waldrep, R.; Taborek, P.

2005-05-01

We have used a 100 000 frame-per-second video to analyze the pinch-off of nitrogen gas bubbles in fluids with a wide range of viscosity. If the external fluid is highly viscous (ηext>100 cP), the bubble neck radius is proportional to the time before break, τ, and decreases smoothly to zero. If the external fluid has low viscosity (ηext<10 cP), the radius scales as τ1/2 until an instability develops in the gas bubble, which causes the neck to rupture and tear apart. Finally, if the viscosity of the external fluid is in an intermediate range, an elongated thread is formed, which breaks apart into micron-sized bubbles.

Filtering microfluidic bubble trains at a symmetric junction.

PubMed

Parthiban, Pravien; Khan, Saif A

2012-02-07

We report how a nominally symmetric microfluidic junction can be used to sort all bubbles of an incoming train exclusively into one of its arms. The existence of this "filter" regime is unexpected, given that the junction is symmetric. We analyze this behavior by quantifying how bubbles modulate the hydrodynamic resistance in microchannels and show how speeding up a bubble train whilst preserving its spatial periodicity can lead to filtering at a nominally symmetric junction. We further show how such an asymmetric traffic of bubble trains can be triggered in symmetric geometries by identifying conditions wherein the resistance to flow decreases with an increase in the number of bubbles in the microchannel and derive an exact criterion to predict the same.

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.

Numerical simulation of single bubble dynamics under acoustic travelling waves.

PubMed

Ma, Xiaojian; Huang, Biao; Li, Yikai; Chang, Qing; Qiu, Sicong; Su, Zheng; Fu, Xiaoying; Wang, Guoyu

2018-04-01

The objective of this paper is to apply CLSVOF method to investigate the single bubble dynamics in acoustic travelling waves. The Naiver-Stokes equation considering the acoustic radiation force is proposed and validated to capture the bubble behaviors. And the CLSVOF method, which can capture the continuous geometric properties and satisfies mass conservation, is applied in present work. Firstly, the regime map, depending on the dimensionless acoustic pressure amplitude and acoustic wave number, is constructed to present different bubble behaviors. Then, the time evolution of the bubble oscillation is investigated and analyzed. Finally, the effect of the direction and the damping coefficient of acoustic wave propagation on the bubble behavior are also considered. The numerical results show that the bubble presents distinct oscillation types in acoustic travelling waves, namely, volume oscillation, shape oscillation, and splitting oscillation. For the splitting oscillation, the formation of jet, splitting of bubble, and the rebound of sub-bubbles may lead to substantial increase in pressure fluctuations on the boundary. For the shape oscillation, the nodes and antinodes of the acoustic pressure wave contribute to the formation of the "cross shape" of the bubble. It should be noted that the direction of the bubble translation and bubble jet are always towards the direction of wave propagation. In addition, the damping coefficient causes bubble in shape oscillation to be of asymmetry in shape and inequality in size, and delays the splitting process. Copyright © 2017 Elsevier B.V. All rights reserved.

Relative acoustic frequency response of induced methane, carbon dioxide and air gas bubble plumes, observed laterally.

PubMed

Kubilius, Rokas; Pedersen, Geir

2016-10-01

There is an increased need to detect, identify, and monitor natural and manmade seabed gas leaks. Fisheries echosounders are well suited to monitor large volumes of water and acoustic frequency response [normalized acoustic backscatter, when a measure at one selected frequency is used as a denominator, r(f)] is commonly used to identify echoes from fish and zooplankton species. Information on gas plume r(f) would be valuable for automatic detection of subsea leaks and for separating bubble plumes from natural targets such as swimbladder-bearing fish. Controlled leaks were produced with a specially designed instrument frame suspended in mid-water in a sheltered fjord. The frame was equipped with echosounders, stereo-camera, and gas-release nozzles. The r(f) of laterally observed methane, carbon dioxide, and air plumes (0.040-29 l/min) were measured at 70, 120, 200, and 333 kHz, with bubble sizes determined optically. The observed bubble size range (1-25 mm) was comparable to that reported in the literature for natural cold seeps of methane. A negative r(f) with increasing frequency was observed, namely, r(f) of about 0.7, 0.6, and 0.5 at 120, 200, and 333 kHz when normalized to 70 kHz. Measured plume r(f) is also compared to resolved, single bubble target strength-based, and modeled r(f).

The impact of specialist trauma service on major trauma mortality.

PubMed

Wong, Ting Hway; Lumsdaine, William; Hardy, Benjamin M; Lee, Keegan; Balogh, Zsolt J

2013-03-01

Trauma services throughout the world have had positive effects on trauma-related mortality. Australian trauma services are generally more consultative in nature rather than the North American model of full trauma admission service. We hypothesized that the introduction of a consultative specialist trauma service in a Level I Australian trauma center would reduce mortality of the severely injured. A 10-year retrospective study (January 1, 2002-December 31, 2011) was performed on all trauma patients admitted with an Injury Severity Score (ISS) > 15. Patients were identified from the trauma registry, and data for age, sex, mechanism of injury, ISS, survival to discharge, and length of stay were collected. Mortality was examined for patients with severe injury (ISS > 15) and patients with critical injury (ISS > 24) and compared for the three periods: 2002-2004 (without trauma specialist), 2005-2007 (with trauma specialist), and 2008-2011 (with specialist trauma service). A total of 3,869 severely injured (ISS > 15) trauma patients were identified during the 10-year period. Of these, 2,826 (73%) were male, 1,513 (39%) were critically injured (ISS > 24), and more than 97% (3,754) were the victim of blunt trauma. Overall mortality decreased from 12.4% to 9.3% (relative risk, 0.75) from period one to period three and from 25.4% to 20.3% (relative risk, 0.80) for patients with critical injury. A 0.46% per year decrease (p = 0.018) in mortality was detected (odds ratio, 0.63; p < 0.001). For critically injured (ISS > 24), the trend was (0.61% per year; odds ratio, 0.68; p = 0.039). The introduction of a specialist trauma service decreased the mortality of patients with severe injury, the model of care should be considered to implement state- and nationwide in Australia. Epidemiologic study, level III.

One-dimensional bubble model of pulsed discharge in water

NASA Astrophysics Data System (ADS)

Lu, XinPei

2007-09-01

In this paper, a one-dimensional bubble model of pulsed discharge in water is presented. With a total input energy of 0.63J, the simulation results show that when the bubble collapses at the center of the bubble, the plasma pressure oscillates strongly. It oscillates between 800 and 1150atm with an oscillation frequency of about 6.9MHz, while at r =R/2 (R: bubble radius), the gas velocity oscillates intensely at the same frequency. It oscillates between -235 and 229m/s when the bubble radius reaches its minimum. But it does not oscillate at r =R because of the inertia of the surrounding water. The bubble collapses and reexpands with almost the same speed as that of the zero-dimensional (0D) model. This further confirms why the shock wave pressure from the 0D mode has a good agreement with the experimental results since the shock wave pressure is only determined by the bubble wall velocity v(R ).

Rhetoric, Risk, and Markets: The Dot-Com Bubble

ERIC Educational Resources Information Center

Goodnight, G. Thomas; Green, Sandy Edward, Jr.

2010-01-01

Post-conventional economic theories are assembled to inquire into the contingent, mimetic, symbolic, and material spirals unfolding the dot-com bubble, 1992-2002. The new technologies bubble is reconstructed as a rhetorical movement across the practices of the hybrid market-industry risk culture of communications. The legacies of the bubble task…

Production of Gas Bubbles in Reduced Gravity Environments

NASA Technical Reports Server (NTRS)

Oguz, Hasan N.; Takagi, Shu; Misawa, Masaki

1996-01-01

In a wide variety of applications such as waste water treatment, biological reactors, gas-liquid reactors, blood oxygenation, purification of liquids, etc., it is necessary to produce small bubbles in liquids. Since gravity plays an essential role in currently available techniques, the adaptation of these applications to space requires the development of new tools. Under normal gravity, bubbles are typically generated by forcing gas through an orifice in a liquid. When a growing bubble becomes large enough, the buoyancy dominates the surface tension force causing it to detach from the orifice. In space, the process is quite different and the bubble may remain attached to the orifice indefinitely. The most practical approach to simulating gravity seems to be imposing an ambient flow to force bubbles out of the orifice. In this paper, we are interested in the effect of an imposed flow in 0 and 1 g. Specifically, we investigate the process of bubble formation subject to a parallel and a cross flow. In the case of parallel flow, we have a hypodermic needle in a tube from which bubbles can be produced. On the other hand, the cross flow condition is established by forcing bubbles through an orifice on a wall in a shear flow. The first series of experiments have been performed under normal gravity conditions and the working fluid was water. A high quality microgravity facility has been used for the second type and silicone oil is used as the host liquid.

Further experimentation on bubble generation during transformer overload. Final report

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

Oommen, T.V.

1992-03-01

This report covers additional work done during 1990 and 1991 on gas bubble generation under overload conditions. To improve visual bubble detection, a single disc coil was used. To further improve detection, a corona device was also used which signaled the onset of corona activity in the early stages of bubble formation. A total of fourteen model tests were conducted, half of which used the Inertaire system, and the remaining, a conservator (COPS). Moisture content of paper in the coil varied from 1.0% to 8.0%; gas (nitrogen) content varied from 1.0% to 8.8%. The results confirmed earlier observations that themore » mathematical bubble prediction model was not valid for high gas content model with relatively low moisture levels in the coil. An empirical relationship was formulated to accurately predict bubble evolution temperatures from known moisture and gas content values. For low moisture content models (below 2%), the simple Piper relationship was sufficient to predict bubble evolution temperatures, regardless of gas content. Moisture in the coil appears to be the key factor in bubble generation. Gas blanketed (Inertaire) systems do not appear to be prone to premature bubble generation from overloads as previously thought. The new bubble prediction model reveals that for a coil with 2% moisture, the bubble evolution temperature would be about 140{degrees}C. Since old transformers in service may have as much as 2% moisture in paper, the 140{degrees}C bubble evolution temperature may be taken as the lower limit of bubble evolution temperature under overload conditions for operating transformers. Drier insulation would raise the bubble evolution temperature.« less

How do bubbles grow in a weakly supersaturated solution?

NASA Astrophysics Data System (ADS)

Enriquez, Oscar; Sun, Chao; Lohse, Detlef; Prosperetti, Andrea; van der Meer, Devaraj

2013-11-01

Beer, champagne and soft-drinks are water-based solutions which owe their ``bubbliness'' to a moderate degree of carbon dioxide supersaturation. Bubbles grow sequentially from nucleation sites due to solute concentration gradients and detach due to buoyancy. The leading mass transfer mechanism is diffusion, but the advection caused by the moving surface also plays an important role. Now, what happens at the limit of very weak supersaturation? We take an experimental look at CO2 bubbles growing in water under such a condition. Nucleation sites are provided by hydrophobic micro-cavities on a silicon chip, therefore controlling the number and position of bubbles. Although advection is negligible, measured growth rates for an isolated bubble differ noticeably from a purely diffusive theoretical solution. We can explain the differences as effects of the concentration boundary layer around the bubble. Initially, its interaction with the surface on which the bubble grows slows the process down. Later on, the growth rate is enhanced by buoyancy effects caused by the depletion of the solute in the surroundings of the bubble. When neighboring bubbles are brought into play they interact through their boundary layers, further slowing down their growth rates.

Three-dimensional magnetic bubble memory system

NASA Technical Reports Server (NTRS)

Stadler, Henry L. (Inventor); Katti, Romney R. (Inventor); Wu, Jiin-Chuan (Inventor)

1994-01-01

A compact memory uses magnetic bubble technology for providing data storage. A three-dimensional arrangement, in the form of stacks of magnetic bubble layers, is used to achieve high volumetric storage density. Output tracks are used within each layer to allow data to be accessed uniquely and unambiguously. Storage can be achieved using either current access or field access magnetic bubble technology. Optical sensing via the Faraday effect is used to detect data. Optical sensing facilitates the accessing of data from within the three-dimensional package and lends itself to parallel operation for supporting high data rates and vector and parallel processing.

Star formation in shells of colliding multi-SNe bubbles

NASA Astrophysics Data System (ADS)

Vasiliev, Evgenii O.; Shchekinov, Yuri A.

2017-12-01

It is believed that when bubbles formed by multiple supernovae explosions interact with one another, they stimulate star formation in overlapping shells. We consider the evolution of a shocked layer formed by the collision of two identical bubbles each of which originated from OB clusters of ˜ 50 members and ˜ 50 pc. The clusters are separated by 200-400 pc.We found that depending on evolutionary status of colliding bubbles the shocked layer can either be destroyed into diffuse lumps, or be fragmented into dense clumps: the former occurs in collisions of young bubbles with continuing supernovae explosions, and the latter occurs in older bubble interactions.We argue that fragmentation efficiency in shells depends on external heating: for a heating rate <˜ 1.7×10-24 erg s-1 the number of fragments formed in a collision of two old bubbles reaches several tens at t ˜ 4 Myr, while a heating rate >˜ 7 × 10-24 erg s-1 prevents fragmentation. The clumps formed in freely expanding parts of bubbles are gradually destroyed and disappear on t <˜ 1 Myr,whereas those formed in the overlapping shells survive much longer. Because of this the number of fragments in an isolated bubble begins to decrease after reaching a maximum, while in collision of two old bubbles it fluctuates around 60-70 until longer than t ˜ 5 Myr.

Ethnic diversity deflates price bubbles

PubMed Central

Levine, Sheen S.; Apfelbaum, Evan P.; Bernard, Mark; Bartelt, Valerie L.; Zajac, Edward J.; Stark, David

2014-01-01

Markets are central to modern society, so their failures can be devastating. Here, we examine a prominent failure: price bubbles. Bubbles emerge when traders err collectively in pricing, causing misfit between market prices and the true values of assets. The causes of such collective errors remain elusive. We propose that bubbles are affected by ethnic homogeneity in the market and can be thwarted by diversity. In homogenous markets, traders place undue confidence in the decisions of others. Less likely to scrutinize others’ decisions, traders are more likely to accept prices that deviate from true values. To test this, we constructed experimental markets in Southeast Asia and North America, where participants traded stocks to earn money. We randomly assigned participants to ethnically homogeneous or diverse markets. We find a marked difference: Across markets and locations, market prices fit true values 58% better in diverse markets. The effect is similar across sites, despite sizeable differences in culture and ethnic composition. Specifically, in homogenous markets, overpricing is higher as traders are more likely to accept speculative prices. Their pricing errors are more correlated than in diverse markets. In addition, when bubbles burst, homogenous markets crash more severely. The findings suggest that price bubbles arise not only from individual errors or financial conditions, but also from the social context of decision making. The evidence may inform public discussion on ethnic diversity: it may be beneficial not only for providing variety in perspectives and skills, but also because diversity facilitates friction that enhances deliberation and upends conformity. PMID:25404313

Ethnic diversity deflates price bubbles.

PubMed

Levine, Sheen S; Apfelbaum, Evan P; Bernard, Mark; Bartelt, Valerie L; Zajac, Edward J; Stark, David

2014-12-30

Markets are central to modern society, so their failures can be devastating. Here, we examine a prominent failure: price bubbles. Bubbles emerge when traders err collectively in pricing, causing misfit between market prices and the true values of assets. The causes of such collective errors remain elusive. We propose that bubbles are affected by ethnic homogeneity in the market and can be thwarted by diversity. In homogenous markets, traders place undue confidence in the decisions of others. Less likely to scrutinize others' decisions, traders are more likely to accept prices that deviate from true values. To test this, we constructed experimental markets in Southeast Asia and North America, where participants traded stocks to earn money. We randomly assigned participants to ethnically homogeneous or diverse markets. We find a marked difference: Across markets and locations, market prices fit true values 58% better in diverse markets. The effect is similar across sites, despite sizeable differences in culture and ethnic composition. Specifically, in homogenous markets, overpricing is higher as traders are more likely to accept speculative prices. Their pricing errors are more correlated than in diverse markets. In addition, when bubbles burst, homogenous markets crash more severely. The findings suggest that price bubbles arise not only from individual errors or financial conditions, but also from the social context of decision making. The evidence may inform public discussion on ethnic diversity: it may be beneficial not only for providing variety in perspectives and skills, but also because diversity facilitates friction that enhances deliberation and upends conformity.

Improving electrokinetic microdevice stability by controlling electrolysis bubbles.

PubMed

Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

2014-07-01

The voltage-operating window for many electrokinetic microdevices is limited by electrolysis gas bubbles that destabilize microfluidic system causing noise and irreproducible responses above ∼3 V DC and less than ∼1 kHz AC at 3 Vpp. Surfactant additives, SDS and Triton X-100, and an integrated semipermeable SnakeSkin® membrane were employed to control and assess electrolysis bubbles from platinum electrodes in a 180 by 70 μm, 10 mm long microchannel. Stabilized current responses at 100 V DC were observed with surfactant additives or SnakeSkin® barriers. Electrolysis bubble behaviors, visualized via video microscopy at the electrode surface and in the microchannels, were found to be influenced by surfactant function and SnakeSkin® barriers. Both SDS and Triton X-100 surfactants promoted smaller bubble diameters and faster bubble detachment from electrode surfaces via increasing gas solubility. In contrast, SnakeSkin® membranes enhanced natural convection and blocked bubbles from entering the microchannels and thus reduced current disturbances in the electric field. This data illustrated that electrode surface behaviors had substantially greater impacts on current stability than microbubbles within microchannels. Thus, physically blocking bubbles from microchannels is less effective than electrode functionalization approaches to stabilize electrokinetic microfluidic systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of mass transfer on bubble plume hydrodynamics.

PubMed

Lima Neto, Iran E; Parente, Priscila A B

2016-03-01

This paper presents an integral model to evaluate the impact of gas transfer on the hydrodynamics of bubble plumes. The model is based on the Gaussian type self-similarity and functional relationships for the entrainment coefficient and factor of momentum amplification due to turbulence. The impact of mass transfer on bubble plume hydrodynamics is investigated considering different bubble sizes, gas flow rates and water depths. The results revealed a relevant impact when fine bubbles are considered, even for moderate water depths. Additionally, model simulations indicate that for weak bubble plumes (i.e., with relatively low flow rates and large depths and slip velocities), both dissolution and turbulence can affect plume hydrodynamics, which demonstrates the importance of taking the momentum amplification factor relationship into account. For deeper water conditions, simulations of bubble dissolution/decompression using the present model and classical models available in the literature resulted in a very good agreement for both aeration and oxygenation processes. Sensitivity analysis showed that the water depth, followed by the bubble size and the flow rate are the most important parameters that affect plume hydrodynamics. Lastly, dimensionless correlations are proposed to assess the impact of mass transfer on plume hydrodynamics, including both the aeration and oxygenation modes.

Evolution of Vapor Bubbles Nucleation Sites in Low Gravity

NASA Technical Reports Server (NTRS)

Buyevich, Yu A.; Webbon, Bruce W.

1995-01-01

When liquid is expelled by a vapor bubble growing at a nucleation site on a superheated surface, a thin microlayer underneath the bubble is left behind. It is evaporated from the free microlayer surface that provides for bubble growth. The average thickness of the microlayer determining the evaporation rate increases with time if the latter does not exceed a threshold value associated with the burn-out crisis. The bubble is described as a spherical segment with its flattened part adjoining the microlayer. This introduces two independent variables - the radius of the spherical part of the bubble surface and the polar angle that defines the relative area of the flattened part. They are to be found out from a set of two strongly nonlinear equations resulting from mass and momentum conservation laws. The first one depends on both microlayer thickness and nonmonotonously changing bubble base area. The second involves two major factors favoring bubble detachment - the buoyancy and a force due to the initial momentum of vapor input into the bubble. The former force depends on gravity whereas the latter one does not. It is why the limiting regimes of bubble evolution that correspond to normal or moderately reduced gravity and to microgravity feature drastically different properties. In the first case, the buoyancy dominates and the bubble evolves in such a manner as to become a full sphere at a moment that can be viewed as that of detachment. The detachment volume grows as gravity decreases. In the second case, the buoyancy is negligible and the bubble stays near the surface, while its volume continues to increase for a sufficiently long time. The findings are discussed in connection with experimental data obtained under different gravity conditions, some unpublished experiments being included. They help to understand why the pool boiling heat transfer coefficient frequently increases as gravity falls down and eventually vanishes.

Bubble video experiments in the marine waters off Panarea Island (Italy): real-world data for modelling CO2 bubble dissolution and evolution

NASA Astrophysics Data System (ADS)

Beaubien, Stan; De Vittor, Cinzia; McGinnis, Dan; Bigi, Sabina; Comici, Cinzia; Ingrosso, Gianmarco; Lombardi, Salvatore; Ruggiero, Livio

2014-05-01

Carbon capture and storage is expected to provide an important, short-term contribution to mitigate global climate change due to anthropogenic emissions of CO2. Offshore reservoirs are particularly favourable, however concerns exist regarding the potential for CO2 leakage into the water column (with possible ecosystem impacts) and the atmosphere. Although laboratory experiments and modelling can examine these issues, the study of natural systems can provide a more complete and realistic understanding. For this reason the natural CO2 emission site off the coast of Panarea Island (Italy) was chosen for study within the EC-funded ECO2 project. The present paper discusses the results of field experiments conducted at this site to better understand the fate of CO2 gas bubbles as they rise through the water column, and to use this real-world data as input to test the predictive capabilities of a bubble model. Experiments were conducted using a 1m wide x 1m deep x 3m tall, hollow-tube structure equipped with a vertical guide on the front face and a dark, graduated cloth for contrast and depth reference on the back. A Plexiglas box was filled with the naturally emitted gas and fixed on the seafloor inside the structure. Tubes exit the top of the box to make bubbles of different diameters, while valves on each tube control bubble release rate. Bubble rise velocity was measured by tracking each bubble with a HD video camera mounted in the guide and calculating values over 20 cm intervals. Bubble diameter was measured by filming the bubbles as they collide with a graduated Plexiglas sheet deployed horizontally at the measurement height. Bubble gas was collected at different heights using a funnel and analysed in the laboratory for CO2, O2+Ar, N2, and CH4. Water parameters were measured by performing a CTD cast beside the structure and collecting water samples at four depths using a Niskin bottle; samples were analysed in the laboratory for all carbonate system species, DO

Tiny Bubbles.

ERIC Educational Resources Information Center

Kim, Hy

1985-01-01

A simple oxygen-collecting device (easily constructed from glass jars and a lid) can show bubbles released by water plants during photosynthesis. Suggestions are given for: (1) testing the collected gas; (2) using various carbon dioxide sources; and (3) measuring respiration. (DH)

Time-resolved imaging of electrical discharge development in underwater bubbles

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

Tu, Yalong; Xia, Hualei; Yang, Yong, E-mail: yangyong@hust.edu.cn, E-mail: luxinpei@hust.edu.cn

2016-01-15

The formation and development of plasma in single air bubbles submerged in water were investigated. The difference in the discharge dynamics and the after-effects on the bubble were investigated using a 900 000 frame per second high-speed charge-coupled device camera. It was observed that depending on the position of the electrodes, the breakdown could be categorized into two modes: (1) direct discharge mode, where the high voltage and ground electrodes were in contact with the bubble, and the streamer would follow the shortest path and propagate along the axis of the bubble and (2) dielectric barrier mode, where the groundmore » electrode was not in touch with the bubble surface, and the streamer would form along the inner surface of the bubble. The oscillation of the bubble and the development of instabilities on the bubble surface were also discussed.« less

Exploding and Imaging of Electron Bubbles in Liquid Helium

NASA Astrophysics Data System (ADS)

Yadav, Neha; Vadakkumbatt, Vaisakh; Maris, Humphrey J.; Ghosh, Ambarish

2017-06-01

An electron bubble in liquid helium-4 under the saturated vapor pressure becomes unstable and explodes if the pressure becomes more negative than -1.9 bars. In this paper, we use focused ultrasound to explode electron bubbles. We then image at 30,000 frames per second the growth and subsequent collapse of the bubbles. We find that bubbles can grow to as large as 1 mm in diameter within 2 ms after the cavitation event. We examine the relation between the maximum size of the bubble and the lifetime and find good agreement with the experimental results.

Trauma center staffing, infrastructure, and patient characteristics that influence trauma center need.

PubMed

Faul, Mark; Sasser, Scott M; Lairet, Julio; Mould-Millman, Nee-Kofi; Sugerman, David

2015-01-01

The most effective use of trauma center resources helps reduce morbidity and mortality, while saving costs. Identifying critical infrastructure characteristics, patient characteristics and staffing components of a trauma center associated with the proportion of patients needing major trauma care will help planners create better systems for patient care. We used the 2009 National Trauma Data Bank-Research Dataset to determine the proportion of critically injured patients requiring the resources of a trauma center within each Level I-IV trauma center (n=443). The outcome variable was defined as the portion of treated patients who were critically injured. We defined the need for critical trauma resources and interventions ("trauma center need") as death prior to hospital discharge, admission to the intensive care unit, or admission to the operating room from the emergency department as a result of acute traumatic injury. Generalized Linear Modeling (GLM) was used to determine how hospital infrastructure, staffing Levels, and patient characteristics contributed to trauma center need. Nonprofit Level I and II trauma centers were significantly associated with higher levels of trauma center need. Trauma centers that had a higher percentage of transferred patients or a lower percentage of insured patients were associated with a higher proportion of trauma center need. Hospital infrastructure characteristics, such as bed capacity and intensive care unit capacity, were not associated with trauma center need. A GLM for Level III and IV trauma centers showed that the number of trauma surgeons on staff was associated with trauma center need. Because the proportion of trauma center need is predominantly influenced by hospital type, transfer frequency, and insurance status, it is important for administrators to consider patient population characteristics of the catchment area when planning the construction of new trauma centers or when coordinating care within state or regional

Dissolution of multicomponent bubbles. [gases in glass melts

NASA Technical Reports Server (NTRS)

Weinberg, M. C.; Subramanian, R. S.

1980-01-01

The behavior of an isolated, stationary, multicomponent gas bubble in a glassmelt containing several dissolved gases is considered. The relevant mass-transport equations are formulated and calculations are performed for the case of two diffusing gases using a quasi-stationary model and a numerical solution of the exact mass-transfer equations. The results obtained from these two approaches are compared. The factors which govern the dissolution or growth of a bubble are thermodynamic and kinetic in origin. The tendency of a bubble to grow or shrink at long times is controlled by departure from overall equilibrium, whereas the short-time bubble dynamics may be dominated by kinetic effects. As a result of the existence of these dual influences, maxima and/or minima occur in the functional dependence of the bubble radius on time.

Generation of Submicron Bubbles using Venturi Tube Method

NASA Astrophysics Data System (ADS)

Wiraputra, I. G. P. A. E.; Edikresnha, D.; Munir, M. M.; Khairurrijal

2016-08-01

In this experiment, submicron bubbles that have diameters less than 1 millimeter were generated by mixing water and gas by hydrodynamic cavitation method. The water was forced to pass through a venturi tube in which the speed of the water will increase in the narrow section, the throat, of the venturi. When the speed of water increased, the pressure would drop at the throat of the venturi causing the outside air to be absorbed via the gas inlet. The gas was then trapped inside the water producing bubbles. The effects of several physical parameters on the characteristics of the bubbles will be discussed thoroughly in this paper. It was found that larger amount of gas pressure during compression will increase the production rate of bubbles and increase the density of bubble within water.

Rates of trauma-informed counseling at substance abuse treatment facilities: reports from over 10,000 programs.

PubMed

Capezza, Nicole M; Najavits, Lisa M

2012-04-01

Trauma-informed treatment increasingly is recognized as an important component of service delivery. This study examined differences in treatment-related characteristics of facilities that offer moderate or high levels of trauma-informed counseling versus those that offer no or low levels of such counseling. Responses from 13,223 substance abuse treatment facilities surveyed in 2009 by the National Survey of Substance Abuse Treatment Services (NSSATS) were used. A majority (66.6%) of facilities reported using trauma counseling sometimes or always or often. Facilities that provided moderate or high levels of trauma counseling were more likely to provide additional treatment services, such as disease testing and specialized group therapy, as well as child care, employment counseling, and other ancillary services. A majority of facilities reported provision of trauma counseling. Additional training and resources may be needed for programs that reported low rates of trauma counseling.

Incremental cost-effectiveness of trauma service improvements for road trauma casualties: experience of an Australian major trauma centre.

PubMed

Dinh, Michael M; Bein, Kendall J; Hendrie, Delia; Gabbe, Belinda; Byrne, Christopher M; Ivers, Rebecca

2016-09-01

Objective The aim of the present study was to estimate the cost-effectiveness of trauma service funding enhancements at an inner city major trauma centre. Methods The present study was a cost-effectiveness analysis using retrospective trauma registry data of all major trauma patients (injury severity score >15) presenting after road trauma between 2001 and 2012. The primary outcome was cost per life year gained associated with the intervention period (2007-12) compared with the pre-intervention period (2001-06). Incremental costs were represented by all trauma-related funding enhancements undertaken between 2007 and 2010. Risk adjustment for years of life lost was conducted using zero-inflated negative binomial regression modelling. All costs were expressed in 2012 Australian dollar values. Results In all, 876 patients were identified during the study period. The incremental cost of trauma enhancements between 2007 and 2012 totalled $7.91million, of which $2.86million (36%) was attributable to road trauma patients. After adjustment for important covariates, the odds of in-hospital mortality reduced by around half (adjusted odds ratio (OR) 0.48; 95% confidence interval (CI) 0.27, 0.82; P=0.01). The incremental cost-effectiveness ratio was A$7600 per life year gained (95% CI A$5524, $19333). Conclusion Trauma service funding enhancements that enabled a quality improvement program at a single major trauma centre were found to be cost-effective based on current international and Australian standards. What is known about this topic? Trauma quality improvement programs have been implemented across most designated trauma hospitals in an effort to improve hospital care processes and outcomes for injured patients. These involve a combination of education and training, the use of audit and key performance indicators. What does this paper add? A trauma quality improvement program initiated at an Australian Major Trauma Centre was found to be cost-effective over 12 years with

Multiple bubbles in a Hele-Shaw cell

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

Vasconcelos, G.L.

A new class of exact solutions is reported for an infinite stream of identical groups of bubbles moving with a constant velocity [ital U] in a Hele-Shaw cell when surface tension is neglected. It is suggested that the existence of these solutions might explain some of the complex behavior observed in recent experiments on rising bubbles in a Hele-Shaw cell. Solutions for a finite number of bubbles in a channel are also obtained. In this case, it is shown that solutions with an arbitrary bubble velocity [ital U][gt][ital V], where [ital V] is the fluid velocity at infinity, can inmore » general be obtained from a simple transformation of the solutions for [ital U]=2[ital V].« less

Interaction of a vortex ring and a bubble

NASA Astrophysics Data System (ADS)

Jha, Narsing K.; Govardhan, Raghuraman N.

2014-11-01

Micro-bubble injection in to boundary layers is one possible method for reducing frictional drag of ships. Although this has been studied for some time, the physical mechanisms responsible for drag reduction using microbubbles in turbulent boundary layers is not yet fully understood. Previous studies suggest that bubble-vortical structure interaction seems to be one of the important physical mechanisms for frictional drag reduction using microbubbles. In the present work, we study a simplification of this problem, namely, the interaction of a single vortical structure, in particular a vortex ring, with a single bubble for better understanding of the physics. The vortex ring is generated using a piston-cylinder arrangement and the bubble is generated by connecting a capillary to an air pump. The bubble dynamics is directly visualized using a high speed camera, while the vorticity modification is measured using time resolved PIV. The results show that significant deformations can occur of both the bubble and the vortex ring. Effect of different non-dimensional parameters on the interaction will be presented in the meeting.

Distinguishing between microscale gaseous bubbles and liquid drops

NASA Astrophysics Data System (ADS)

Tan, Beng Hau; An, Hongjie; Chan, Chon U.; Ohl, Claus-Dieter

2015-11-01

In recent years, there has been strong research interest in decorating surfaces with tiny bubbles and drops due to their potential applications in reducing slippage in micro and nanofluidic devices. Both nanobubbles and nanodrops are typically nucleated by exchanging fluids over a suitable substrate. However, the nucleation experiments present many challenges, such as reproducibility and the possibility of contamination. The use of one-use plastic syringes and needle cannulas in nucleation experiments can introduce polymeric contamination. A contaminated experiment may nucleate bubbles, drops or both. Moreover, it is surprisingly difficult to distinguish between bubbles and drops under the usual atomic force microscopy or optical techniques. Here we present an experimental study comparing bubbles and oil (PDMS) drops on an atomically smooth surface (HOPG). Instead of nucleating the objects via solvent exchange, we directly introduced bubbles via electrolysis, and oil drops by injecting a dilute solution. Contrary to previous reports, we find that under careful AFM characterisation, liquid drops and gaseous bubbles respond differently to a change in imaging force, and moreover present different characteristic force curves.

An Inquiry of the Lived Experiences and Contextual Understandings of Early Childhood Special Educators Related to Children's Trauma

ERIC Educational Resources Information Center

DuBois, Alison L.

2010-01-01

Secondary trauma stress, compassion fatigue, and vicarious trauma are terms rarely found in educational literature. Studies have shown the significant and lasting ramifications of these constructs within the realm of counseling and psychology. Professionals working in educational settings with high risk populations encounter multiple exposures to…

The Role of Cumulative Trauma, Betrayal, and Appraisals in Understanding Trauma Symptomatology.

PubMed

Martin, Christina Gamache; Cromer, Lisa Demarni; Deprince, Anne P; Freyd, Jennifer J

2013-03-01

Poor psychological outcomes are common among trauma survivors, yet not all survivors experience adverse sequelae. The current study examined links between cumulative trauma exposure as a function of the level of betrayal (measured by the relational closeness of the survivor and the perpetrator), trauma appraisals, gender, and trauma symptoms. Participants were 273 college students who reported experiencing at least one traumatic event on a trauma checklist. Three cumulative indices were constructed to assess the number of different types of traumas experienced that were low (LBTs), moderate (MBTs), or high in betrayal (HBTs). Greater trauma exposure was related to more symptoms of depression, dissociation, and PTSD, with exposure to HBTs contributing the most. Women were more likely to experience HBTs than men, but there were no gender differences in trauma-related symptoms. Appraisals of trauma were predictive of trauma-related symptoms over and above the effects explained by cumulative trauma at each level of betrayal. The survivor's relationship with the perpetrator, the effect of cumulative trauma, and their combined impact on trauma symptomatology are discussed.

The Role of Cumulative Trauma, Betrayal, and Appraisals in Understanding Trauma Symptomatology

PubMed Central

Martin, Christina Gamache; Cromer, Lisa DeMarni; DePrince, Anne P.; Freyd, Jennifer J.

2012-01-01

Poor psychological outcomes are common among trauma survivors, yet not all survivors experience adverse sequelae. The current study examined links between cumulative trauma exposure as a function of the level of betrayal (measured by the relational closeness of the survivor and the perpetrator), trauma appraisals, gender, and trauma symptoms. Participants were 273 college students who reported experiencing at least one traumatic event on a trauma checklist. Three cumulative indices were constructed to assess the number of different types of traumas experienced that were low (LBTs), moderate (MBTs), or high in betrayal (HBTs). Greater trauma exposure was related to more symptoms of depression, dissociation, and PTSD, with exposure to HBTs contributing the most. Women were more likely to experience HBTs than men, but there were no gender differences in trauma-related symptoms. Appraisals of trauma were predictive of trauma-related symptoms over and above the effects explained by cumulative trauma at each level of betrayal. The survivor’s relationship with the perpetrator, the effect of cumulative trauma, and their combined impact on trauma symptomatology are discussed. PMID:23542882

Preparing Global Trauma Nurses for Leadership Roles in Global Trauma Systems.

PubMed

Muñiz, Sol Angelica; Lang, Richard W; Falcon, Lisa; Garces-King, Jasmine; Willard, Suzanne; Peck, Gregory L

Trauma leads to 5.7 million annual deaths globally, accounting for 25%-33% of global unintentional deaths and 90% of the global trauma burden in low- and middle-income countries. The Lancet Commission on Global Surgery and the World Health Organization assert that emergent and essential surgical capacity building and trauma system improvement are essential to address the global burden of trauma. In response, the Rutgers Global Surgery program, the School of Nursing and Medicine, and the Robert Wood Johnson University Hospital faculty collaborated in the first Interprofessional Models in Global Injury Care and Education Symposium in June 2016. This 2-week symposium combined lectures, high-fidelity simulation, small group workshops, site visits to Level I trauma centers, and a 1-day training course from the Panamerican Trauma Society. The aim was to introduce global trauma nurses to trauma leadership and trauma system development. After completing the symposium, 10 nurses from China, Colombia, Kenya, Puerto Rico, and Uruguay were surveyed. Overall, 88.8% of participants reported high levels of satisfaction with the program and 100% stated being very satisfied with trauma lectures. Symposia, such as that developed and offered by Rutgers University, prepare nurses to address trauma within system-based care and facilitate trauma nursing leadership in their respective countries.

Simulation Studies on Cooling of Cryogenic Propellant by Gas Bubbling

NASA Astrophysics Data System (ADS)

Sandilya, Pavitra; Saha, Pritam; Sengupta, Sonali

Injection cooling was proposed to store cryogenic liquids (Larsen et al. [1], Schmidt [2]). When a non-condensable gas is injected through a liquid, the liquid component would evaporate into the bubble if its partial pressure in the bubble is lower than its vapour pressure. This would tend to cool the liquid. Earlier works on injection cooling was analysed by Larsen et al. [1], Schmidt [2], Cho et al. [3] and Jung et al. [4], considering instantaneous mass transfer and finite heat transfer between gas bubble and liquid. It is felt that bubble dynamics (break up, coalescence, deformation, trajectory etc.) should also play a significant role in liquid cooling. The reported work are based on simple assumptions like single bubble, zero bubble deformation, and no inter-bubble interactions. Hence in this work, we propose a lumped parameter model considering both heat and mass interactions between bubble and the liquid to gain a preliminary insight into the cooling phenomenon during gas injection through a liquid.

Size limits the formation of liquid jets during bubble bursting

PubMed Central

Lee, Ji San; Weon, Byung Mook; Park, Su Ji; Je, Jung Ho; Fezzaa, Kamel; Lee, Wah-Keat

2011-01-01

A bubble reaching an air–liquid interface usually bursts and forms a liquid jet. Jetting is relevant to climate and health as it is a source of aerosol droplets from breaking waves. Jetting has been observed for large bubbles with radii of R≫100 μm. However, few studies have been devoted to small bubbles (R<100 μm) despite the entrainment of a large number of such bubbles in sea water. Here we show that jet formation is inhibited by bubble size; a jet is not formed during bursting for bubbles smaller than a critical size. Using ultrafast X-ray and optical imaging methods, we build a phase diagram for jetting and the absence of jetting. Our results demonstrate that jetting in bubble bursting is analogous to pinching-off in liquid coalescence. The coalescence mechanism for bubble bursting may be useful in preventing jet formation in industry and improving climate models concerning aerosol production. PMID:21694715

Implementing screening, brief intervention, and referral for alcohol and drug use: the trauma service perspective.

PubMed

Sise, Michael J; Sise, C Beth; Kelley, Dorothy M; Simmons, Charles W; Kelso, Dennis J

2005-09-01

Most trauma surgeons are unfamiliar with screening, brief intervention, and referral (SBIR) programs for substance use disorders, and few trauma centers provide them. This report describes how an urban private-teaching hospital adapted a protocol from an existing emergency department-based program to include patients treated by the trauma service. We recorded the rates of SBIR completion and reasons for failure during each phase of the implementation, interviewed trauma service staff and health educators to assess attitudes toward the program, and evaluated patient satisfaction surveys. By adding SBIR staff to the trauma outpatient clinic and to trauma morning rounds, the capture rate increased from 12 to 71%. Most screened patients (59%) were found at risk for problems or probably dependent on alcohol or drugs. Trauma service staff and health educators reported high satisfaction with the program. Patients reported higher satisfaction with SBIR. SBIR services can be effectively integrated into all components of a busy, urban trauma service by adding specially trained health educators to the trauma service staff. This collaboration provides effective SBIR services to both trauma and emergency service patients without interfering with patient flow or medical procedures. The relatively high percentage of patients at risk for alcohol or drug problems supports the inclusion of routine alcohol and drug screening for all eligible trauma patients.

Trauma-focused CBT for youth with complex trauma

PubMed Central

Mannarino, Anthony P.; Kliethermes, Matthew; Murray, Laura A.

2013-01-01

Objectives Many youth develop complex trauma, which includes regulation problems in the domains of affect, attachment, behavior, biology, cognition, and perception. Therapists often request strategies for using evidence-based treatments (EBTs) for this population. This article describes practical strategies for applying Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) for youth with complex trauma. Methods TF-CBT treatment phases are described and modifications of timing, proportionality and application are described for youth with complex trauma. Practical applications include a) dedicating proportionally more of the model to the TF-CBT coping skills phase; b) implementing the TF-CBT Safety component early and often as needed throughout treatment; c) titrating gradual exposure more slowly as needed by individual youth; d) incorporating unifying trauma themes throughout treatment; and e) when indicated, extending the TF-CBT treatment consolidation and closure phase to include traumatic grief components and to generalize ongoing safety and trust. Results Recent data from youth with complex trauma support the use of the above TF-CBT strategies to successfully treat these youth. Conclusions The above practical strategies can be incorporated into TF-CBT to effectively treat youth with complex trauma. Practice implications Practical strategies include providing a longer coping skills phase which incorporates safety and appropriate gradual exposure; including relevant unifying themes; and allowing for an adequate treatment closure phase to enhance ongoing trust and safety. Through these strategies therapists can successfully apply TF-CBT for youth with complex trauma. PMID:22749612

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

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.

Pediatric trauma at an adult trauma center.

PubMed

Siram, Suryanarayana; Oyetunji, Tolulope A; Khoury, Amal L; Walker, Sonya R; Bolorunduro, Oluwaseyi B; Chang, David C; Greene, Wendy R; Cornwell, Edward E; Frederick, Wayne A I

2010-08-01

Accidental traumatic injury is the number 1 cause of morbidity and mortality in the pediatric population. In this study, we aim to prove that certain pediatric patients can be treated with good outcomes at an adult level 1 trauma center. Retrospective analysis using the Howard University Hospital trauma registry identified 71 patients treated at Howard University Hospital between the ages of 1 and 17 years old. Specific variables were identified and collected for each patient. The majority of pediatric traumas treated at Howard University Hospital between June 2004 and May 2005 had high survival rates (93%). The patients who did not survive (7%) included 3 patients who were dead on arrival and 2 who died shortly after arrival to the hospital. Certain pediatric populations who present with minor and/or isolated injuries can be treated in an adult level 1 trauma center with similar outcomes to treatment in a pediatric level 1 trauma center.

Trauma Fact Sheet

MedlinePlus

... News & Meetings Science Education About NIGMS NIGMS Home > Science Education > Physical Trauma Physical Trauma Tagline (Optional) Middle/Main Content Area PDF Version (420 KB) Other Fact Sheets What is physical trauma? Physical trauma is ...

Dynamics of sonoluminescing bubbles within a liquid hammer device.

PubMed

Urteaga, Raúl; García-Martínez, Pablo Luis; Bonetto, Fabián J

2009-01-01

We studied the dynamics of a single sonoluminescing bubble (SBSL) in a liquid hammer device. In particular, we investigated the phosphoric acid-xenon system, in which pulses up to four orders of magnitude brighter than SBSL in water systems (about 10;{12} photons per pulse) have been previously reported [Chakravarty, Phys. Rev. E 69, 066317 (2004)]. We used stroboscopic photography and a Mie scattering technique in order to measure the radius evolution of the bubbles. Under adequate conditions we may position a bubble at the bottom of the tube (cavity) and a second bubble trapped at the middle of the tube (upper bubble). During its collapse, the cavity produces the compression of the liquid column. This compression drives impulsively the dynamics of the upper bubble. Our measurements reveal that the observed light emissions produced by the upper bubble are generated at its second collapse. We employed a simple numerical model to investigate the conditions that occur during the upper bubble collapse. We found good agreement between numerical and experimental values for the light intensity (fluence) and light pulse widths. Results from the model show that the light emission is increased mainly due to an increase in noble gas ambient radius and not because the maximum temperature increases. Even for the brightest pulses obtained ( 2x10;{13} photons, about 20W of peak power) the maximum temperatures computed for the upper bubble are always lower than 20000K .

Driving bubbles out of glass

NASA Technical Reports Server (NTRS)

Mattox, D. M.

1981-01-01

Surface tension gradient in melt forces gas bubbles to surface, increasing glass strength and transparency. Conventional chemical and buoyant fining are extremely slow in viscous glasses, but tension gradient method moves 250 um bubbles as rapidly as 30 um/s. Heat required for high temperature part of melt is furnished by stationary electrical or natural-gas heater; induction and laser heating are also possible. Method has many applications in industry processes.

Dynamic Bubble Surface Tension Measurements in Northwest Atlantic Seawater

NASA Astrophysics Data System (ADS)

Kieber, D. J.; Long, M. S.; Keene, W. C.; Kinsey, J. D.; Frossard, A. A.; Beaupre, S. R.; Duplessis, P.; Maben, J. R.; Lu, X.; Chang, R.; Zhu, Y.; Bisgrove, J.

2017-12-01

Numerous reports suggest that most organic matter (OM) associated with newly formed primary marine aerosol (PMA) originates from the sea-surface microlayer. However, surface-active OM rapidly adsorbs onto bubble surfaces in the water column and is ejected into the atmosphere when bubbles burst at the air-water interface. Here we present dynamic surface tension measurements of bubbles produced in near surface seawater from biologically productive and oligotrophic sites and in deep seawater collected from 2500 m in the northwest Atlantic. In all cases, the surface tension of bubble surfaces decreased within seconds after the bubbles were exposed to seawater. These observations demonstrate that bubble surfaces are rapidly saturated by surfactant material scavenged from seawater. Spatial and diel variability in bubble surface evolution indicate corresponding variability in surfactant concentrations and/or composition. Our results reveal that surface-active OM is found throughout the water column, and that at least some surfactants are not of recent biological origin. Our results also support the hypothesis that the surface microlayer is a minor to negligible source of OM associated with freshly produced PMA.

Observation of high-temperature bubbles in an ECR plasma

NASA Astrophysics Data System (ADS)

Terasaka, K.; Yoshimura, S.; Tanaka, M. Y.

2018-05-01

Creation and annihilation of high-temperature bubbles have been observed in an electron cyclotron resonance plasma. The electron temperature in the bubble core is three times higher than that in the ambient region, and the size perpendicular to the magnetic field is much smaller than the plasma diameter. Formation of a bubble accompanies large negative spikes in the floating potential of a Langmuir probe, and the spatiotemporal behavior of the bubble has been visualized with a high-impedance wire grid detector. It is found that the bubble is in a prolate spheroidal shape with the axis along the magnetic field and occurs randomly in time and independently in space.

Champagne experiences various rhythmical bubbling regimes in a flute.

PubMed

Liger-Belair, Gérard; Tufaile, Alberto; Jeandet, Philippe; Sartorelli, José-Carlos

2006-09-20

Bubble trains are seen rising gracefully from a few points on the glass wall (called nucleation sites) whenever champagne is poured into a glass. As time passes during the gas-discharging process, the careful observation of some given bubble columns reveals that the interbubble distance may change suddenly, thus revealing different rhythmical bubbling regimes. Here, it is reported that the transitions between the different bubbling regimes of some nucleation sites during gas discharging is a process which may be ruled by a strong interaction between tiny gas pockets trapped inside the nucleation site and/or also by an interaction between the tiny bubbles just blown from the nucleation site.

Bubble clustering in a glass of stout beer

NASA Astrophysics Data System (ADS)

Iwatsubo, Fumiya; Watamura, Tomoaki; Sugiyama, Kazuyasu

2017-11-01

To clarify why the texture in stout beer poured into a pint glass descends, we investigated local time development of the void fraction and velocity of bubbles. The propagation of the number density distribution, i.e. the texture, appearing near the inclined wall is observed. We visualized individual advective bubbles near the inclined wall by microscope and measured the local void fraction using brightness of images while the velocity of bubbles by means of Particle Tracking Velocimetry. As the result of measurements, we found the local void fraction and the bubbles advection velocity increase and decrease repeatedly with a time delay. We conclude the texture pattern is composed of fluid blobs which contain less bubbles; extruding and suction flows respectively toward and from the interior of the container form respectively in front and back of the blobs.

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

Moduli vacuum bubbles produced by evaporating black holes

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

Morris, J. R.

2007-10-15

We consider a model with a toroidally compactified extra dimension giving rise to a temperature-dependent 4D effective potential with one-loop contributions due to the Casimir effect, along with a 5D cosmological constant. The forms of the effective potential at low and high temperatures indicate a possibility for the formation of a domain wall bubble, formed by the modulus scalar field, surrounding an evaporating black hole. This is viewed as an example of a recently proposed black hole vacuum bubble arising from matter-sourced moduli fields in the vicinity of an evaporating black hole [D. Green, E. Silverstein, and D. Starr, Phys.more » Rev. D 74, 024004 (2006)]. The black hole bubble can be highly opaque to lower-energy particles and photons, and thereby entrap them within. For high-temperature black holes, there may also be a symmetry-breaking black hole bubble of false vacuum of the type previously conjectured by Moss [I. G. Moss, Phys. Rev. D 32, 1333 (1985)], tending to reflect low-energy particles from its wall. A double bubble composed of these two different types of bubble may form around the black hole, altering the hole's emission spectrum that reaches outside observers. Smaller mass black holes that have already evaporated away could have left vacuum bubbles behind that contribute to the dark matter.« less

New solutions for steady bubbles in a Hele-Shaw cell

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

Tanveer, S.

1987-03-01

Exact solutions are presented for steadily moving bubbles in a Hele--Shaw cell when the effect of surface tension is neglected. These solutions form a three-parameter family. For specified area, both the speed of the bubble and the distance of its centroid from the channel centerline remain arbitrary when surface tension is ignored. However, numerical evidence suggests that this twofold arbitrariness is removed by the effect of surface tension, i.e., for given bubble area and surface tension, solutions exist only when the bubble velocity and the centroid distance from the channel centerline attain one or more isolated values. From a limitedmore » numerical search, no nonsymmetric solutions could be found; however, a branch of symmetric bubble solutions that was not found in earlier work was found. This branch corresponds to one of the Romero-Vanden-Broeck branch of finger solutions when the bubble size is large. A new procedure for numerical calculations of bubble solutions in the presence of surface tension is presented and is found to work very well for reasonably large bubbles, unlike the previous method of Tanveer (Phys. Fluids 29, 3537 (1986)). The precise power law dependence of bubble velocity on surface tension for small surface tension is explored for bubbles of different area. Agreement is noted with recent analytical results for a finger.« less

Single-bubble dynamics in pool boiling of one-component fluids.

PubMed

Xu, Xinpeng; Qian, Tiezheng

2014-06-01

We numerically investigate the pool boiling of one-component fluids with a focus on the effects of surface wettability on the single-bubble dynamics. We employed the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)], a diffuse-interface model for liquid-vapor flows involving liquid-vapor transition in nonuniform temperature fields. We first perform simulations for bubbles on homogeneous surfaces. We find that an increase in either the contact angle or the surface superheating can enhance the bubble spreading over the heating surface and increase the bubble departure diameter as well and therefore facilitate the transition into film boiling. We then examine the dynamics of bubbles on patterned surfaces, which incorporate the advantages of both hydrophobic and hydrophilic surfaces. The central hydrophobic region increases the thermodynamic probability of bubble nucleation while the surrounding hydrophilic region hinders the continuous bubble spreading by pinning the contact line at the hydrophobic-hydrophilic intersection. This leads to a small bubble departure diameter and therefore prevents the transition from nucleate boiling into film boiling. With the bubble nucleation probability increased and the bubble departure facilitated, the efficiency of heat transfer on such patterned surfaces is highly enhanced, as observed experimentally [Int. J. Heat Mass Transfer 57, 733 (2013)]. In addition, the stick-slip motion of contact line on patterned surfaces is demonstrated in one-component fluids, with the effect weakened by surface superheating.

Impurity bubbles in a BEC

NASA Astrophysics Data System (ADS)

Timmermans, Eddy; Blinova, Alina; Boshier, Malcolm

2013-05-01

Polarons (particles that interact with the self-consistent deformation of the host medium that contains them) self-localize when strongly coupled. Dilute Bose-Einstein condensates (BECs) doped with neutral distinguishable atoms (impurities) and armed with a Feshbach-tuned impurity-boson interaction provide a unique laboratory to study self-localized polarons. In nature, self-localized polarons come in two flavors that exhibit qualitatively different behavior: In lattice systems, the deformation is slight and the particle is accompanied by a cloud of collective excitations as in the case of the Landau-Pekar polarons of electrons in a dielectric lattice. In natural fluids and gases, the strongly coupled particle radically alters the medium, e.g. by expelling the host medium as in the case of the electron bubbles in superfluid helium. We show that BEC-impurities can self-localize in a bubble, as well as in a Landau-Pekar polaron state. The BEC-impurity system is fully characterized by only two dimensionless coupling constants. In the corresponding phase diagram the bubble and Landau-Pekar polaron limits correspond to large islands separated by a cross-over region. The same BEC-impurity species can be adiabatically Feshbach steered from the Landau-Pekar to the bubble regime. This work was funded by the Los Alamos LDRD program.

Models of cylindrical bubble pulsation

PubMed Central

Ilinskii, Yurii A.; Zabolotskaya, Evgenia A.; Hay, Todd A.; Hamilton, Mark F.

2012-01-01

Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23–26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion. PMID:22978863

Guest investigator program study: Physics of equatorial plasma bubbles

NASA Technical Reports Server (NTRS)

Tsunoda, Roland T.

1994-01-01

Plasma bubbles are large-scale (10 to 100 km) depletions in plasma density found in the night-time equatorial ionosphere. Their formation has been found to entail the upward transport of plasma over hundreds of kilometers in altitude, suggesting that bubbles play significant roles in the physics of many of the diverse and unique features found in the low-latitude ionosphere. In the simplest scenario, plasma bubbles appear first as perturbations in the bottomside F layer, which is linearly unstable to the gravitationally driven Rayleigh-Taylor instability. Once initiated, bubbles develop upward through the peak of the F layer into its topside (sometimes to altitudes in excess of 1000 km), a behavior predicted by the nonlinear form of the same instability. While good general agreement has been found between theory and observations, little is known about the detailed physics associated with plasma bubbles. Our research activity centered around two topics: the shape of plasma bubbles and associated electric fields, and the day-to-day variability in the occurrence of plasma bubbles. The first topic was pursued because of a divergence in view regarding the nonlinear physics associated with plasma bubble development. While the development of perturbations in isodensity contours in the bottomside F layer into plasma bubbles is well accepted, some believed bubbles to be cylinder-like closed regions of depleted plasma density that floated upward leaving a turbulent wake behind them (e.g., Woodman and LaHoz, 1976; Ott, 1978; Kelley and Ott, 1978). Our results, summarized in a paper submitted to the Journal of Geophysical Research, consisted of incoherent scatter radar measurements that showed unambiguously that the depleted region is wedgelike and not cylinderlike, and a case study and modeling of SM-D electric field instrument (EFI) measurements that showed that the absence of electric-field perturbations outside the plasma-depleted region is a distinct signature of wedge

Relation between psychotic symptoms, parental care and childhood trauma in severe mental disorders.

PubMed

Catalan, Ana; Angosto, Virxina; Díaz, Aida; Valverde, Cristina; de Artaza, Maider Gonzalez; Sesma, Eva; Maruottolo, Claudio; Galletero, Iñaki; Bustamante, Sonia; Bilbao, Amaia; van Os, Jim; Gonzalez-Torres, Miguel Angel

2017-05-01

A relation between different types of parental care, trauma in childhood and psychotic symptoms in adulthood has been proposed. The nature of this association is not clear and if it is more related to psychotic disorders per se or to a cluster of symptoms such as positive psychotic symptoms remains undefined. We have analysed the presence of childhood trauma using the CTQ scale and types of parental care using the PBI scale in three groups of subjects: borderline personality disorder patients (n=36), first psychotic episode patients (n=61) and healthy controls (n=173). Positive psychotic symptomatology was assessed with the CAPE scale. General linear models were used to study the relation between positive psychotic symptomatology and variables of interest. BPD patients had the highest rate of any kind of trauma, followed by FEP patients. We found a positive relationship between psychotic symptomatology and the existence of trauma in childhood in all groups. Moreover, an affectionless control rearing style was directly associated with the existence of trauma. Furthermore, subjects with trauma presented less probability of having an optimal parenting style in childhood. The relation between psychotic symptoms and trauma remained statistically significant after adjusting for other variables including parental rearing style. There seems to be a link between trauma in childhood and psychotic symptomatology across different populations independently of psychiatric diagnosis. Taking into account that there is an association between trauma and psychosis and that trauma is a modifiable factor, clinicians should pay special attention to these facts. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Characterisation of gene delivery using liposomal bubbles and ultrasound

NASA Astrophysics Data System (ADS)

Koshima, Risa; Suzuki, Ryo; Oda, Yusuke; Hirata, Keiichi; Nomura, Tetsuya; Negishi, Yoichi; Utoguchi, Naoki; Kudo, Nobuki; Maruyama, Kazuo

2011-09-01

The combination of nano/microbubbles and ultrasound is a novel technique for a non-viral gene deliver. We have previously developed novel ultrasound sensitive liposomes (Bubble liposomes) which contain the ultrasound imaging gas perfluoropropane. In this study, Bubble liposomes were compared with cationic lipid (CL)-DNA complexes as potential gene delivery carriers into tumors in vivo. The delivery of genes by bubble liposomes depended on the intensity of the applied ultrasound. The transfection efficiency plateaued at 0.7 W/cm2 ultrasound intensity. Bubble liposomes efficiently transferred genes into cultured cells even when the cells were exposed to ultrasound for only 1 s. In addition, bubble liposomes were able to introduce the luciferase gene more effectively than CL-DNA complexes into mouse ascites tumor cells. We conclude that the combination of Bubble liposomes and ultrasound is a good method for gene transfer in vivo.

Membrane cleaning with ultrasonically driven bubbles.

PubMed

Reuter, Fabian; Lauterborn, Sonja; Mettin, Robert; Lauterborn, Werner

2017-07-01

A laboratory filtration plant for drinking water treatment is constructed to study the conditions for purely mechanical in situ cleaning of fouled polymeric membranes by the application of ultrasound. The filtration is done by suction of water with defined constant contamination through a membrane module, a stack of five pairs of flat-sheet ultrafiltration membranes. The short cleaning cycle to remove the cake layer from the membranes includes backwashing, the application of ultrasound and air flushing. A special geometry for sound irradiation of the membranes parallel to their surfaces is chosen. Two frequencies, 35kHz and 130kHz, and different driving powers are tested for their cleaning effectiveness. No cleaning is found for 35kHz, whereas good cleaning results are obtained for 130kHz, with an optimum cleaning effectiveness at moderate driving powers. Acoustic and optic measurements in space and time as well as analytical considerations and numerical calculations reveal the reasons and confirm the experimental results. The sound field is measured in high resolution and bubble structures are high-speed imaged on their nucleation sites as well as during their cleaning work at the membrane surface. The microscopic inspection of the membrane surface after cleaning shows distinct cleaning types in the cake layer that are related to specific bubble behaviour on the membrane. The membrane integrity and permeate quality are checked on-line by particle counting and turbidity measurement of the permeate. No signs of membrane damage or irreversible membrane degradation in permeability are detected and an excellent water permeate quality is retained. Copyright © 2017 Elsevier B.V. All rights reserved.

Laryngeal findings and acoustic changes in hubble-bubble smokers.

PubMed

Hamdan, Abdul-latif; Sibai, Abla; Oubari, Dima; Ashkar, Jihad; Fuleihan, Nabil

2010-10-01

The purpose of our investigation was to evaluate the laryngeal findings and acoustic changes in hubble-bubble smokers. A total of 42 subjects with history of hubble-bubble smoking were recruited for this study. A corresponding group with a history of cigarette smoking and controls were matched. All subjects underwent laryngeal video-endostroboscopic evaluation and acoustic analysis. In the hubble-bubble smoking group, 61.9% were males. The average age was 30.02 +/- 9.48 years and the average number of years of smoking was 8.09 +/- 6.45 years. Three subjects had dysphonia at the time of examination. The incidence of benign lesions of the vocal folds in the hubble-bubble group was 21.5%, with edema being the most common at 16.7% followed by cyst at 4.8%. The incidence of laryngeal findings was significantly higher in the hubble-bubble group compared to controls. In the cigarette-smoking group, the most common finding was vocal fold cyst in 14.8% followed by polyps in 7.4%, and edema, sulcus vocalis and granuloma. These findings were not significantly different from the hubble-bubble group except for the thick mucus, which was significantly higher in the latter. There were no significant changes in any of the acoustic parameters between hubble-bubble smokers and controls except for the VTI and MPT, which were significantly lower in the hubble-bubble group. In comparison with the cigarette-smoking group, hubble-bubble smokers had significantly higher Fundamental frequency and habitual pitch (p value 0.042 and 0.008, respectively). The laryngeal findings in hubble-bubble smokers are comparable to cigarette smokers. These laryngeal findings are not translated acoustically, as all the acoustic parameters are within normal range compared to controls.

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

Light Scattering by Ice Crystals Containing Air Bubbles

NASA Astrophysics Data System (ADS)

Zhang, J.; Panetta, R. L.; Yang, P.; Bi, L.

2014-12-01

The radiative effects of ice clouds are often difficult to estimate accurately, but are very important for interpretation of observations and for climate modeling. Our understanding of these effects is primarily based on scattering calculations, but due to the variability in ice habit it is computationally difficult to determine the required scattering and absorption properties, and the difficulties are only compounded by the need to include consideration of air and carbon inclusions of the sort frequently observed in collected samples. Much of the previous work on effects of inclusions in ice particles on scattering properties has been conducted with variants of geometric optics methods. We report on simulations of scattering by ice crystals with enclosed air bubbles using the pseudo-spectral time domain method (PSTD) and improved geometric optics method (IGOM). A Bouncing Ball Model (BBM) is proposed as a parametrization of air bubbles, and the results are compared with Monte Carlo radiative transfer calculations. Consistent with earlier studies, we find that air inclusions lead to a smoothing of variations in the phase function, weakening of halos, and a reduction of backscattering. We extend these studies by examining the effects of the particular arrangement of a fixed number of bubbles, as well as the effects of splitting a given number of bubbles into a greater number of smaller bubbles with the same total volume fraction. The result shows that the phase function will not change much for stochastic distributed air bubbles. It also shows that local maxima of phase functions are smoothed out for backward directions, when we break bubbles into small ones, single big bubble scatter favors more forward scattering than multi small internal scatters.

Numerical investigation of bubble nonlinear dynamics characteristics

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

Shi, Jie, E-mail: shijie@hrbeu.edu.cn; Yang, Desen; Shi, Shengguo

2015-10-28

The complicated dynamical behaviors of bubble oscillation driven by acoustic wave can provide favorable conditions for many engineering applications. On the basis of Keller-Miksis model, the influences of control parameters, including acoustic frequency, acoustic pressure and radius of gas bubble, are discussed by utilizing various numerical analysis methods, Furthermore, the law of power spectral variation is studied. It is shown that the complicated dynamic behaviors of bubble oscillation driven by acoustic wave, such as bifurcation and chaos, further the stimulated scattering processes are revealed.

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

Effects of fluid viscosity on a moving sonoluminescing bubble.

PubMed

Sadighi-Bonabi, Rasoul; Mirheydari, Mona; Rezaee, Nastaran; Ebrahimi, Homa

2011-08-01

Based on the quasi-adiabatic model, the parameters of the bubble interior for a moving single bubble sonoluminescence in water, adiponitrile, and N-methylformamide are calculated for various fluid viscosities. By using a complete form of the hydrodynamic force, the bubble trajectory is calculated for a moving single bubble sonoluminescence (m-SBSL). It is found that as the fluid viscosity increases, the unique circular path changes to an ellipsoidal and then linear form and along this incrementally increase of viscosity the light intensity increases. By using the Bremsstrahlung model to describe the bubble radiation, gradual increase of the viscosity results in brighter emissions. It is found that in fluids with higher viscosity the light intensity decreases as time passes.

Analytical and numerical investigations of bubble behavior in electric fields

NASA Astrophysics Data System (ADS)

Vorreiter, Janelle Orae

The behavior of gas bubbles in liquids is important in a wide range of applications. This study is motivated by a desire to understand the motion of bubbles in the absence of gravity, as in many aerospace applications. Phase-change devices, cryogenic tanks and life-support systems are some of the applications where bubbles exist in space environments. One of the main difficulties in employing devices with bubbles in zero gravity environments is the absence of a buoyancy force. The use of an electric field is found to be an effective means of replacing the buoyancy force, improving the control of bubbles in space environments. In this study, analytical and numerical investigations of bubble behavior under the influence of electric fields are performed. The problem is a difficult one in that the physics of the liquid and the electric field need to be considered simultaneously to model the dynamics of the bubble. Simplifications are required to reduce the problem to a tractable form. In this work, for the liquid and the electric field, assumptions are made which reduce the problem to one requiring only the solution of potentials in the domain of interest. Analytical models are developed using a perturbation analysis applicable for small deviations from a spherical shape. Numerical investigations are performed using a boundary integral code. A number of configurations are found to be successful in promoting bubble motion by varying properties of the electric fields. In one configuration, the natural frequencies of a bubble are excited using time-varying electric and pressure fields. The applied electric field is spatially uniform with frequencies corresponding to shape modes of the bubble. The resulting bubble velocity is related to the strength of the electric field as well as the characteristics of the applied fields. In another configuration, static non-uniform fields are used to encourage bubble motion. The resulting motion is related to the degree of non

Morphological bubble evolution induced by air diffusion on submerged hydrophobic structures

NASA Astrophysics Data System (ADS)

Lv, Pengyu; Xiang, Yaolei; Xue, Yahui; Lin, Hao; Duan, Huiling

2017-03-01

Bubbles trapped in the cavities always play important roles in the underwater applications of structured hydrophobic surfaces. Air exchange between bubbles and surrounding water has a significant influence on the morphological bubble evolution, which in turn frequently affects the functionalities of the surfaces, such as superhydrophobicity and drag reduction. In this paper, air diffusion induced bubble evolution on submerged hydrophobic micropores under reduced pressures is investigated experimentally and theoretically. The morphological behaviors of collective and single bubbles are observed using confocal microscopy. Four representative evolution phases of bubbles are captured in situ. After depressurization, bubbles will not only grow and coalesce but also shrink and split although the applied pressure remains negative. A diffusion-based model is used to analyze the evolution behavior and the results are consistent with the experimental data. A criterion for bubble growth and shrinkage is also derived along with a phase diagram, revealing that the competition of effective gas partial pressures across the two sides of the diffusion layer dominates the bubble evolution process. Strategies for controlling the bubble evolution behavior are also proposed based on the phase diagram. The current work provides a further understanding of the general behavior of bubble evolution induced by air diffusion and can be employed to better designs of functional microstructured hydrophobic surfaces.

Axisymmetric bubble pinch-off at high Reynolds numbers.

PubMed

Gordillo, J M; Sevilla, A; Rodríguez-Rodríguez, J; Martínez-Bazán, C

2005-11-04

Analytical considerations and potential-flow numerical simulations of the pinch-off of bubbles at high Reynolds numbers reveal that the bubble minimum radius, rn, decreases as tau proportional to r2n sqrt[1lnr2n], where tau is the time to break up, when the local shape of the bubble near the singularity is symmetric. However, if the gas convective terms in the momentum equation become of the order of those of the liquid, the bubble shape is no longer symmetric and the evolution of the neck changes to a rn proportional to tau1/3 power law. These findings are verified experimentally.

Removal of hydrogen bubbles from nuclear reactors

NASA Technical Reports Server (NTRS)

Jenkins, R. V.

1980-01-01

Method proposed for removing large hydrogen bubbles from nuclear environment uses, in its simplest form, hollow spheres of palladium or platinum. Methods would result in hydrogen bubble being reduced in size without letting more radioactivity outside reactor.

The effect of gravity-induced pressure gradient on bubble luminescence

NASA Astrophysics Data System (ADS)

Supponen, Outi; Obreschkow, Danail; Kobel, Philippe; Dorsaz, Nicolas; Tinguely, Marc; Farhat, Mohamed

2014-11-01

The violent collapse of a bubble can heat up its gaseous contents to temperatures exceeding those on the sun's surface, resulting in a short luminescence flash. Occurring at the very moment of the collapse, luminescence must be highly sensitive to the bubble geometry at the preceding final stage. This represents an important feature as any pressure anisotropy in the surrounding liquid will result in a deformation of an initially spherical bubble, inducing a micro-jet that pierces the bubble and makes it experience a toroidal collapse. We therefore present these as complementary phenomena by investigating the link between jets and luminescence of laser-generated single bubbles. Through ultra-high-speed imaging, the micro-jet formation and evolution of a single bubble are observed with unprecedented detail, whilst the bubble light emission is analyzed by means of a spectrometer. The bubble energy and the micro-jet size are controlled by adjusting the laser-pulse and by varying the gravity level aboard ESA parabolic flights, respectively. We here provide systematic evidence on how bubble-jets suppress luminescence in a considerable manner, even in normal gravity where the jet is barely observable. We conclude that gravity must be accounted for in accurate models of luminescence.

Modeling nonclassical heterogeneous bubble nucleation from cellulose fibers: application to bubbling in carbonated beverages.

PubMed

Liger-Belair, Gérard; Voisin, Cédric; Jeandet, Philippe

2005-08-04

In this paper, the kinetics of CO(2) bubble nucleation from tiny gas pockets trapped inside cellulose fibers immersed in a glass of champagne were investigated, in situ, from high-speed video recordings. Taking into account the diffusion of CO(2)-dissolved molecules from the liquid bulk to the gas pocket, a model was derived which enabled us to connect the kinetics of bubble nucleation with both fiber and liquid parameters. Convection was found to play a major role in this process. The boundary layer around the gas pocket where a gradient of CO(2)-dissolved molecules exists was also indirectly approached and found to be in the order of 10-20 mum. Because most of the particles adsorbed on the wall of a container or vessel free from any particular treatment are also believed to be cellulose fibers coming from the surrounding air, the results of this paper could be indeed extended to the more general field of nonclassical heterogeneous bubble nucleation from supersaturated liquids.

Black holes as bubble nucleation sites

NASA Astrophysics Data System (ADS)

Gregory, Ruth; Moss, Ian G.; Withers, Benjamin

2014-03-01

We consider the effect of inhomogeneities on the rate of false vacuum decay. Modelling the inhomogeneity by a black hole, we construct explicit Euclidean instantons which describe the nucleation of a bubble of true vacuum centred on the inhomogeneity. We find that inhomogeneity significantly enhances the nucleation rate over that of the Coleman-de Luccia instanton — the black hole acts as a nucleation site for the bubble. The effect is larger than previously believed due to the contributions to the action from conical singularities. For a sufficiently low initial mass, the original black hole is replaced by flat space during this process, as viewed by a single causal patch observer. Increasing the initial mass, we find a critical value above which a black hole remnant survives the process. This resulting black hole can have a higher mass than the original black hole, but always has a lower entropy. We compare the process to bubble-to-bubble transitions, where there is a semi-classical Lorentzian description in the WKB approximation.

Convective mass transfer around a dissolving bubble

NASA Astrophysics Data System (ADS)

Duplat, Jerome; Grandemange, Mathieu; Poulain, Cedric

2017-11-01

Heat or mass transfer around an evaporating drop or condensing vapor bubble is a complex issue due to the interplay between the substrate properties, diffusion- and convection-driven mass transfer, and Marangoni effects, to mention but a few. In order to disentangle these mechanisms, we focus here mainly on the convective mass transfer contribution in an isothermal mass transfer problem. For this, we study the case of a millimetric carbon dioxide bubble which is suspended under a substrate and dissolved into pure liquid water. The high solubility of CO2 in water makes the liquid denser and promotes a buoyant-driven flow at a high (solutal) Rayleigh number (Ra˜104 ). The alteration of p H allows the concentration field in the liquid to be imaged by laser fluorescence enabling us to measure both the global mass flux (bubble volume, contact angle) and local mass flux around the bubble along time. After a short period of mass diffusion, where the boundary layer thickens like the square root of time, convection starts and the CO2 is carried by a plume falling at constant velocity. The boundary layer thickness then reaches a plateau which depends on the bubble cross section. Meanwhile the plume velocity scales like (dV /d t )1 /2 with V being the volume of the bubble. As for the rate of volume loss, we recover a constant mass flux in the diffusion-driven regime followed by a decrease in the volume V like V2 /3 after convection has started. We present a model which agrees well with the bubble dynamics and discuss our results in the context of droplet evaporation, as well as high Rayleigh convection.

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.

Single-bubble dynamics in pool boiling of one-component fluids

NASA Astrophysics Data System (ADS)

Xu, Xinpeng; Qian, Tiezheng

2014-06-01

We numerically investigate the pool boiling of one-component fluids with a focus on the effects of surface wettability on the single-bubble dynamics. We employed the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007), 10.1103/PhysRevE.75.036304], a diffuse-interface model for liquid-vapor flows involving liquid-vapor transition in nonuniform temperature fields. We first perform simulations for bubbles on homogeneous surfaces. We find that an increase in either the contact angle or the surface superheating can enhance the bubble spreading over the heating surface and increase the bubble departure diameter as well and therefore facilitate the transition into film boiling. We then examine the dynamics of bubbles on patterned surfaces, which incorporate the advantages of both hydrophobic and hydrophilic surfaces. The central hydrophobic region increases the thermodynamic probability of bubble nucleation while the surrounding hydrophilic region hinders the continuous bubble spreading by pinning the contact line at the hydrophobic-hydrophilic intersection. This leads to a small bubble departure diameter and therefore prevents the transition from nucleate boiling into film boiling. With the bubble nucleation probability increased and the bubble departure facilitated, the efficiency of heat transfer on such patterned surfaces is highly enhanced, as observed experimentally [Int. J. Heat Mass Transfer 57, 733 (2013), 10.1016/j.ijheatmasstransfer.2012.10.080]. In addition, the stick-slip motion of contact line on patterned surfaces is demonstrated in one-component fluids, with the effect weakened by surface superheating.

Compression-induced stacking fault tetrahedra around He bubbles in Al

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

Shao, Jian-Li, E-mail: shao-jianli@iapcm.ac.cn; Wang, Pei; He, An-Min

Classic molecular dynamics methods are used to simulate the uniform compression process of the fcc Al containing He bubbles. The formation of stacking fault tetrahedra (SFTs) during the collapse of He bubbles is found, and their dependence on the initial He bubble size (0.6–6 nm in diameter) is presented. Our simulations indicate only elastic deformation in the samples for the He bubble size not more than 2 nm. Instead, increasing the He bubble size, we detect several small SFTs forming on the surface of the He bubble (3 nm), as well as the two intercrossed SFTs around the He bubbles (4–6 nm). All thesemore » SFTs are observed to be stable under further compression, though there may appear some SF networks outside the SFTs (5–6 nm). Furthermore, the dynamic analysis on the SFTs shows that the yield pressure keeps a near-linear increase with the initial He bubble pressure, and the potential energy of Al atoms inside the SFTs is lower than outside because of their gliding inwards. In addition, the pressure increments of 2–6 nm He bubbles with strain are less than that of Al, which just provides the opportunity for the He bubble collapse and the SFTs formation. Note that the current work only focuses on the case that the number ratio between He atoms and Al vacancies is 1:1.« less

Bubble transport and sticking in gas embolotherapy

NASA Astrophysics Data System (ADS)

Bull, Joseph

2002-11-01

Pressure-driven bubble transport in a two-dimensional, bifurcating channel is investigated as a model of gas emboli transport in the microcirculation. Gas emboli are relevant to a number of clinical situations, and our particular interest is a novel gas embolotherapy technique, which involves using gas bubbles to occlude blood flow to tumors. This minimally invasive treatment modality allows selective delivery of emboli. The bubbles originate as 6 micron-diameter liquid droplets of perfluorocarbon (PFC), mixed in saline, and are injected into the vascular system. The droplet forms are small enough to pass through capillary beds, so they can circulate until the next stage of the therapy. By strategically placing an ultrasound source over the artery feeding the tumor, the droplets may be vaporized at that location. Our model is developed using the Stokes equation subject to interfacial and wall boundary conditions, and is solved using the boundary element method. The conditions under which bubbles 'stick' to the channel walls and occlude flow are investigated. Clinically, these results are important because the location and homogeneity of bubble sticking determines the degree of tumor necrosis and the efficacy of the treatment.

Bubble collisions and measures of the multiverse

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

Salem, Michael P., E-mail: salem@cosmos.phy.tufts.edu

2012-01-01

To compute the spectrum of bubble collisions seen by an observer in an eternally-inflating multiverse, one must choose a measure over the diverging spacetime volume, including choosing an ''initial'' hypersurface below which there are no bubble nucleations. Previous calculations focused on the case where the initial hypersurface is pushed arbitrarily deep into the past. Interestingly, the observed spectrum depends on the orientation of the initial hypersurface, however one's ability observe the effect rapidly decreases with the ratio of inflationary Hubble rates inside and outside one's bubble. We investigate whether this conclusion might be avoided under more general circumstances, including placingmore » the observer's bubble near the initial hypersurface. We find that it is not. As a point of reference, a substantial appendix reviews relevant aspects of the measure problem of eternal inflation.« less

Applications of squeezed states: Bogoliubov transformations and wavelets to the statistical mechanics of water and its bubbles

NASA Technical Reports Server (NTRS)

Defacio, Brian; Kim, S.-H.; Vannevel, A.

1994-01-01

The squeezed states or Bogoliubov transformations and wavelets are applied to two problems in nonrelativistic statistical mechanics: the dielectric response of liquid water, epsilon(q-vector,w), and the bubble formation in water during insonnification. The wavelets are special phase-space windows which cover the domain and range of L(exp 1) intersection of L(exp 2) of classical causal, finite energy solutions. The multiresolution of discrete wavelets in phase space gives a decomposition into regions of time and scales of frequency thereby allowing the renormalization group to be applied to new systems in addition to the tired 'usual suspects' of the Ising models and lattice gasses. The Bogoliubov transformation: squeeze transformation is applied to the dipolaron collective mode in water and to the gas produced by the explosive cavitation process in bubble formation.

Effects of Particle Size and Bubble Characteristics on Transport of Micro- and Nano-Bubbles in Saturated Porous Media

NASA Astrophysics Data System (ADS)

Hamamoto, S.; Nihei, N.; Ueda, Y.; Moldrup, P.; Nishimura, T.

2016-12-01

The micro- and nano-bubbles (MNBs) have considerable potentials for the remediation of soil contaminated by organic compounds when used in conjunction with bioremediation technology. Understanding a transport mechanism of MNBs in soils is essential to optimize remediation techniques using MNBs. In this study, column transport experiments using glass beads with different size fractions (average particles size: 0.1 mm and 0.4 mm) were conducted, where MNBs created by oxygen gas were injected to the column with different flow rates. Effects of particle size and bubble characteristics on MNB transport in porous media were investigated based on the column experiments. The results showed that attachments of MNBs were enhanced under lower flow rate. Under higher flow rate condition, there were not significant differences of MNBs transport in porous media with different particle size. A convection-dispersion model including bubble attachment, detachment, and straining terms was applied to the obtained breakthrough curves for each experiment, showing good fitness against the measured data. Further investigations will be conducted to understand bubble characteristics including bubble size and zeta potential on MNB transport in porous media. Relations between in model parameters in the transport model and physical and chemical properties in porous media and MNBs will be discussed.

Intraluminal bubble dynamics induced by lithotripsy shock wave

NASA Astrophysics Data System (ADS)

Song, Jie; Bai, Jiaming; Zhou, Yufeng

2016-12-01

Extracorporeal shock wave lithotripsy (ESWL) has been the first option in the treatment of calculi in the upper urinary tract since its introduction. ESWL-induced renal injury is also found after treatment and is assumed to associate with intraluminal bubble dynamics. To further understand the interaction of bubble expansion and collapse with the vessel wall, the finite element method (FEM) was used to simulate intraluminal bubble dynamics and calculate the distribution of stress in the vessel wall and surrounding soft tissue during cavitation. The effects of peak pressure, vessel size, and stiffness of soft tissue were investigated. Significant dilation on the vessel wall occurs after contacting with rapid and large bubble expansion, and then vessel deformation propagates in the axial direction. During bubble collapse, large shear stress is found to be applied to the vessel wall at a clinical lithotripter setting (i.e. 40 MPa peak pressure), which may be the mechanism of ESWL-induced vessel rupture. The decrease of vessel size and viscosity of soft tissue would enhance vessel deformation and, consequently, increase the generated shear stress and normal stresses. Meanwhile, a significantly asymmetric bubble boundary is also found due to faster axial bubble expansion and shrinkage than in radial direction, and deformation of the vessel wall may result in the formation of microjets in the axial direction. Therefore, this numerical work would illustrate the mechanism of ESWL-induced tissue injury in order to develop appropriate counteractive strategies for reduced adverse effects.

Electron self-injection and trapping into an evolving plasma bubble.

PubMed

Kalmykov, S; Yi, S A; Khudik, V; Shvets, G

2009-09-25

The blowout (or bubble) regime of laser wakefield acceleration is promising for generating monochromatic high-energy electron beams out of low-density plasmas. It is shown analytically and by particle-in-cell simulations that self-injection of the background plasma electrons into the quasistatic plasma bubble can be caused by slow temporal expansion of the bubble. Sufficient criteria for the electron trapping and bubble's expansion rate are derived using a semianalytic nonstationary Hamiltonian theory. It is further shown that the combination of bubble's expansion and contraction results in monoenergetic electron beams.

Characterization of an acoustic cavitation bubble structure at 230 kHz.

PubMed

Thiemann, Andrea; Nowak, Till; Mettin, Robert; Holsteyns, Frank; Lippert, Alexander

2011-03-01

A generic bubble structure in a 230 kHz ultrasonic field is observed in a partly developed standing wave field in water. It is characterized by high-speed imaging, sonoluminescence recordings, and surface cleaning tests. The structure has two distinct bubble populations. Bigger bubbles (much larger than linear resonance size) group on rings in planes parallel to the transducer surface, apparently in locations of driving pressure minima. They slowly rise in a jittering, but synchronous way, and they can have smaller satellite bubbles, thus resembling the arrays of bubbles observed by Miller [D. Miller, Stable arrays of resonant bubbles in a 1-MHz standing-wave acoustic field, J. Acoust. Soc. Am. 62 (1977) 12]. Smaller bubbles (below and near linear resonance size) show a fast "streamer" motion perpendicular to and away from the transducer surface. While the bigger bubbles do not emit light, the smaller bubbles in the streamers show sonoluminescence when they pass the planes of high driving pressure. Both bubble populations exhibit cleaning potential with respect to micro-particles attached to a glass substrate. The respective mechanisms of particle removal, though, might be different. Copyright © 2010 Elsevier B.V. All rights reserved.

Plasmonic nanoparticle-generated photothermal bubbles and their biomedical applications

PubMed Central

Lapotko, Dmitri

2009-01-01

This article is focused on the optical generation and detection of photothermal vapor bubbles around plasmonic nanoparticles. We report physical properties of such plasmonic nanobubbles and their biomedical applications as cellular probes. Our experimental studies of gold nanoparticle-generated photothermal bubbles demonstrated the selectivity of photothermal bubble generation, amplification of optical scattering and thermal insulation effect, all realized at the nanoscale. The generation and imaging of photothermal bubbles in living cells (leukemia and carcinoma culture and primary cancerous cells), and tissues (atherosclerotic plaque and solid tumor in animal) demonstrated a noninvasive highly sensitive imaging of target cells by small photothermal bubbles and a selective mechanical, nonthermal damage to the individual target cells by bigger photothermal bubbles due to a rapid disruption of cellular membranes. The analysis of the plasmonic nanobubbles suggests them as theranostic probes, which can be tuned and optically guided at cell level from diagnosis to delivery and therapy during one fast process. PMID:19839816

Trapping, focusing, and sorting of microparticles through bubble streaming

NASA Astrophysics Data System (ADS)

Wang, Cheng; Jalikop, Shreyas; Hilgenfeldt, Sascha

2010-11-01

Ultrasound-driven oscillating microbubbles can set up vigorous steady streaming flows around the bubbles. In contrast to previous work, we make use of the interaction between the bubble streaming and the streaming induced around mobile particles close to the bubble. Our experiment superimposes a unidirectional Poiseuille flow containing a well-mixed suspension of neutrally buoyant particles with the bubble streaming. The particle-size dependence of the particle-bubble interaction selects which particles are transported and which particles are trapped near the bubbles. The sizes selected for can be far smaller than any scale imposed by the device geometry, and the selection mechanism is purely passive. Changing the amplitude and frequency of ultrasound driving, we can further control focusing and sorting of the trapped particles, leading to the emergence of sharply defined monodisperse particle streams within a much wider channel. Optimizing parameters for focusing and sorting are presented. The technique is applicable in important fields like cell sorting and drug delivery.

The growth of oscillating bubbles in an ultrasound field

NASA Astrophysics Data System (ADS)

Yamauchi, Risa; Yamashita, Tatsuya; Ando, Keita

2017-11-01

From our recent experiments to test particle removal by underwater ultrasound, dissolved gas supersaturation is found to play an important role in physical cleaning; cavitation bubble nucleation can be triggered easily by weak ultrasound under the supersaturation and mild motion of the bubbles contributes to efficient cleaning without erosion. The state of gas bubble nuclei in water is critical to the determination of a cavitation inception threshold. Under ultrasound forcing, the size of bubble nuclei is varied by the transfer of dissolved gas (i.e., rectified diffusion); the growth rate will be promoted by the supersaturation and is thus expected to contribute to cavitation activity enhancement. In the present work, we experimentally study rectified diffusion for bubbles attached at glass surfaces in an ultrasound field. We will present the evolution of bubble nuclei sizes with varying parameters such as dissolved oxygen supersaturation, and ultrasound intensity and frequency. the Research Grant of Keio Leading-edge Laboratory of Science & Technology.

Numerical Study of Underwater Explosions and Following Bubble Pulses

NASA Astrophysics Data System (ADS)

Abe, Atsushi; Katayama, Masahide; Murata, Kenji; Kato, Yukio; Tanaka, Katsumi

2007-06-01

Underwater explosions and following bubble pulses were simulated by using the hydrocode AUTODYN. The pressure gradient depended on the water depth was applied to the water, and the effects of the atmospheric pressure and the gravity on the bubble properties were investigated numerically. In the deep and shallow water depth cases the bubble properties or pressure histories obtained numerically were compared with the empirical formula or the experimental data. Not only the pressure gradient in the water and the atmospheric pressure but also the application of the JWL EOS to slow energy release of the non-ideal explosive (Miller model) were found to be of great importance to simulate the generation of the bubble pulse precisely. Although the gravitational term during the dynamic analysis can be neglected in numerical analyses for very short time phenomena, it is indispensable to simulate the buoyancy of the bubble because the time range of the bubble behavior is some hundred times longer than that of the explosion phenomena.

Bubble evolution in Kr-irradiated UO2 during annealing

NASA Astrophysics Data System (ADS)

He, L.; Bai, X. M.; Pakarinen, J.; Jaques, B. J.; Gan, J.; Nelson, A. T.; El-Azab, A.; Allen, T. R.

2017-12-01

Transmission electron microscopy observation of Kr bubble evolution in polycrystalline UO2 annealed at high temperature was conducted in order to understand the inert gas behavior in oxide nuclear fuel. The average diameter of intragranular bubbles increased gradually from 0.8 nm in as-irradiated sample at room temperature to 2.6 nm at 1600 °C and the bubble size distribution changed from a uniform distribution to a bimodal distribution above 1300 °C. The size of intergranular bubbles increased more rapidly than intragranular ones and bubble denuded zones near grain boundaries formed in all the annealed samples. It was found that high-angle grain boundaries held bigger bubbles than low-angle grain boundaries. Complementary atomistic modeling was conducted to interpret the effects of grain boundary character on the Kr segregation. The area density of strong segregation sites in the high-angle grain boundaries is much higher than that in the low angle grain boundaries.

The trauma ecosystem: The impact and economics of new trauma centers on a mature statewide trauma system.

PubMed

Ciesla, David J; Pracht, Etienne E; Leitz, Pablo T; Spain, David A; Staudenmayer, Kristan L; Tepas, Joseph J

2017-06-01

Florida serves as a model for the study of trauma system performance. Between 2010 and 2104, 5 new trauma centers were opened alongside 20 existing centers. The purpose of this study was to explore the impact of trauma system expansion on system triage performance and trauma center patients' profiles. A statewide data set was queried for all injury-related discharges from adult acute care hospitals using International Classification of Diseases, Ninth Revision (ICD-9) codes for 2010 and 2014. The data set, inclusion criteria, and definitions of high-risk injury were chosen to match those used by the Florida Department of Health in its trauma registry. Hospitals were classified as existing Level I (E1) or Level II (E2) trauma centers and new E2 (N2) centers. Five N2 centers were established 11.6 to 85.3 miles from existing centers. Field and overall trauma system triage of high-risk patients was less accurate with increased overtriage and no change in undertriage. Annual volume at N2 centers increased but did not change at E1 and E2 centers. In 2014, Patients at E1 and E2 centers were slightly older and less severely injured, while those at N2 centers were substantially younger and more severely injured than in 2010. The injured patient-payer mix changed with a decrease in self-pay and commercial patients and an increase in government-sponsored patients at E1 and E2 centers and an increase in self-pay and commercial patients with a decrease in government-sponsored patients at N2 centers. Designation of new trauma centers in a mature system was associated with a change in established trauma center demographics and economics without an improvement in trauma system triage performance. These findings suggest that the health of an entire trauma system network must be considered in the design and implementation of a regional trauma system. Therapeutic/care management study, level IV; epidemiological, level IV.

The Minnaert Bubble: An Acoustic Approach

ERIC Educational Resources Information Center

Devaud, Martin; Hocquet, Thierry; Bacri, Jean-Claude; Leroy, Valentin

2008-01-01

We propose an "ab initio" introduction to the well-known Minnaert pulsating bubble at graduate level. After a brief recall of the standard stuff, we begin with a detailed discussion of the radial movements of an air bubble in water. This discussion is managed from an acoustic point of view, and using the Lagrangian rather than the Eulerian…

Drops and Bubble in Materials Science

NASA Technical Reports Server (NTRS)

Doremus, R. H.

1982-01-01

The formation of extended p-n junctions in semiconductors by drop migration, mechanisms and morphologies of migrating drops and bubbles in solids and nucleation and corrections to the Volmer-Weber equations are discussed. Bubble shrinkage in the processing of glass, the formation of glass microshells as laser-fusion targets, and radiation-induced voids in nuclear reactors were examined.

STABILITY OF AQUEOUS FILMS BETWEEN BUBBLES

PubMed Central

Ohnishi, Satomi; Vogler, Erwin A.; Horn, Roger G.

2010-01-01

Film thinning experiments have been conducted with aqueous films between two air phases in a thin film pressure balance. The films are free of added surfactant but simple NaCl electrolyte is added in some experiments. Initially the experiments begin with a comparatively large volume of water in a cylindrical capillary tube a few mm in diameter, and by withdrawing water from the center of the tube the two bounding menisci are drawn together at a prescribed rate. This models two air bubbles approaching at a controlled speed. In pure water the results show three regimes of behavior depending on the approach speed: at slow speed (<1 µm/s) it is possible to form a flat film of pure water, ~100 nm thick, that is stabilised indefinitely by disjoining pressure due to repulsive double-layer interactions between naturally-charged air/water interfaces. The data are consistent with a surface potential of −57 mV on the bubble surfaces. At intermediate approach speed (~1 – 150 µm/s) the films are transiently stable due to hydrodynamic drainage effects, and bubble coalescence is delayed by ~10 – 100 s. At approach speeds greater than ~150 µm/s the hydrodynamic resistance appears to become negligible, and the bubbles coalesce without any measurable delay. Explanations for these observations are presented that take into account DLVO and Marangoni effects entering through disjoining pressure, surface mobility and hydrodynamic flow regimes in thin film drainage. In particular, it is argued that the dramatic reduction in hydrodynamic resistance is a transition from viscosity-controlled drainage to inertia-controlled drainage associated with a change from immobile to mobile air/water interfaces on increasing the speed of approach of two bubbles. A simple model is developed that accounts for the boundaries between different film stability or coalescence regimes. Predictions of the model are consistent with the data, and the effects of adding electrolyte can be explained. In

Delinquent-Victim Youth-Adapting a Trauma-Informed Approach for the Juvenile Justice System.

PubMed

Rapp, Lisa

2016-01-01

The connection between victimization and later delinquency is well established and most youth involved with the juvenile justice system have at least one if not multiple victimizations in their history. Poly-victimized youth or those presenting with complex trauma require specialized assessment and services to prevent deleterious emotional, physical, and social life consequences. Empirical studies have provided information which can guide practitioners work with these youth and families, yet many of the policies and practices of the juvenile justice system are counter to this model. Many youth-serving organizations are beginning to review their operations to better match a trauma-informed approach and in this article the author will highlight how a trauma-informed care model could be utilized to adapt the juvenile justice system.

Generating Soap Bubbles by Blowing on Soap Films

NASA Astrophysics Data System (ADS)

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

2016-02-01

Making soap bubbles by blowing air on a soap film is an enjoyable activity, yet a poorly understood phenomenon. Working either with circular bubble wands or long-lived vertical soap films having an adjustable steady state thickness, we investigate the formation of such bubbles when a gas is blown through a nozzle onto a film. We vary film size, nozzle radius, space between the film and nozzle, and gas density, and we measure the gas velocity threshold above which bubbles are formed. The response is sensitive to containment, i.e., the ratio between film and jet sizes, and dissipation in the turbulent gas jet, which is a function of the distance from the film to the nozzle. We rationalize the observed four different regimes by comparing the dynamic pressure exerted by the jet on the film and the Laplace pressure needed to create the curved surface of a bubble. This simple model allows us to account for the interplay between hydrodynamic, physicochemical, and geometrical factors.

Generating Soap Bubbles by Blowing on Soap Films.

PubMed

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

2016-02-19

Making soap bubbles by blowing air on a soap film is an enjoyable activity, yet a poorly understood phenomenon. Working either with circular bubble wands or long-lived vertical soap films having an adjustable steady state thickness, we investigate the formation of such bubbles when a gas is blown through a nozzle onto a film. We vary film size, nozzle radius, space between the film and nozzle, and gas density, and we measure the gas velocity threshold above which bubbles are formed. The response is sensitive to containment, i.e., the ratio between film and jet sizes, and dissipation in the turbulent gas jet, which is a function of the distance from the film to the nozzle. We rationalize the observed four different regimes by comparing the dynamic pressure exerted by the jet on the film and the Laplace pressure needed to create the curved surface of a bubble. This simple model allows us to account for the interplay between hydrodynamic, physicochemical, and geometrical factors.

Cavitation Bubble Streaming in Ultrasonic-Standing-Wave Field

NASA Astrophysics Data System (ADS)

Nomura, Shinfuku; Mukasa, Shinobu; Kuroiwa, Masaya; Okada, Yasuyuki; Murakami, Koichi

2005-05-01

The mechanism of cavitation bubble streaming by ultrasonic vibration in a water tank was experimentally investigated. A standard ultrasonic cleaner unit with a resonant frequency of 40 kHz was used as an ultrasonic generator. The behavior of the streaming was visualized by the schlieren method and sonochemical luminescence, and the velocity of the streaming was measured by laser Doppler velocity measurement equipment (LDV). The cavitation bubble streaming has two structures. A cavitation cloud, which consists of many cavitation bubbles, is shaped like a facing pair of bowls with a diameter of approximately 1/3 the wavelength of the standing wave, and moves inside the standing-wave field with a velocity of 30 to 60 mm/s. The cavitation bubbles move intensely in the cloud with a velocity of 5 m/s at an ultrasonic output power of 75 W. The streaming is completely different from conventional acoustic streaming. Also the cavitation bubble is generated neither at the pressure node nor at the antinode.

The Milky Way Project: A Census of Small Bubbles