Bubble Trap Research Articles

Bose–Einstein condensation in spherically symmetric traps

We present a pedagogical introduction to Bose–Einstein condensation in traps with spherical symmetry, namely, the spherical box and the thick shell, sometimes called bubble trap. In order to obtain the critical temperature for Bose–Einstein condensation, we describe how to calculate the cumulative state number and density of states in these geometries, using numerical and analytical (semi-classical) approaches. The differences in the results of both methods are a manifestation of Weyl's theorem, i.e., they reveal how the geometry of the trap (boundary condition) affects the number of the eigenstates counted. Using the same calculation procedure, we analyzed the impact of going from three-dimensions to two-dimensions, as we move from a thick shell to a two-dimensional shell. The temperature range we obtained, for the most commonly used atomic species and reasonable confinement volumes, is compatible with current cold atom experiments, which demonstrates that these trapping potentials may be employed in experiments.

Temperature‐Driven Bubble Migration as Proxy for Internal Bubble Pressures and Bubble Trapping Function in Ice Cores

AbstractIce core data record significant and abrupt past climate changes that are associated with large and rapid changes in atmospheric greenhouse gases, such as methane. Due to the gradual close‐off of gas bubbles and the relatively fast diffusion of gases within the firn column, even a discrete or quick step increase in air composition may be smoothed or integrated in the data; current laboratory analyses of gases consider the mean gas content value across all bubbles in a sample, rather than the content of individual bubbles. The convolution of the distribution of trapping ages with the history of atmospheric composition thus smears the measured gas record in each sample. We developed a nondestructive method to determine pressure distribution in all bubbles in a sample and estimate the shape of the trapping function derived from that bubble pressure distribution and site characteristics. Our method works not only for present conditions but also through varying paleo‐atmospheric conditions, while providing accurate measurements of morphological bubble properties. The method is based on using temperature‐driven air bubble migration as a proxy for the pressure of individual bubbles, which we combine with a model for bubbly ice densification to obtain the gas trapping functions and constrain the age distribution of air bubbles for past conditions, which are preserved at different depths. The trapping functions will help us to obtain a more accurate gas signal in the future that is less attenuated through the age distribution of the gas during the close‐off process.

Microfluidic chip system integrated with light addressable potentiometric sensor (LAPS) for real-time extracellular acidification detection

Metabolism is a common biological mechanism in living cells. Acidification plays an important role in cell metabolism, in which the extracellular pH change is used to indicate the vitality of cells. For extracellular detection of cell metabolic substances, light addressable potentiometric sensor (LAPS) has many advantages, such as high sensitivity, easy encapsulation, and convenient integration with microfluidic system for cell experiments. LAPS is a spatially resolved biochemical sensor based on field-effect. In this work, we present a microfluidic system integrated with LAPS for real-time extracellular acidification rate (ECAR) detection. The functions of traditional microphysiometer are achieved with simpler structure devices. Polydimethylsiloxane (PDMS) chamber was manufactured for cell culture, and microfluidic flow paths were used for medium and drug delivery. A bubble trap device was applied to eliminate air bubbles generated in microfluidics. Characteristic tests and cell metabolism experiments were carried out to determine the performance of LAPS by monitoring the pH change of hepatoma HepG2 cells. Glucose and doxorubicin were delivered to the cell chamber to verify the effects of the drug. The pH sensitivity of LAPS is 335.5 nA/pH at the working point in constant voltage mode. The ECAR of HepG2 cells was -48.53 mpH/min in normal glucose medium (25 mM), and it changed to -114.42 mpH/min in high glucose medium (125 mM) and -17.88 mpH/min under the effect of doxorubicin (10 μM). The results show that the microfluidic LAPS presents good performance in real-time detection of cell acidification and provides a convenient means of assessing cellular specificity of drugs. The modular structure and high expandability make the microfluidic LAPS has good potential in the application of organ-on-chip.

Imaging the Deep Subsurface Plumbing of Old Faithful Geyser From Low‐Frequency Hydrothermal Tremor Migration

AbstractOld Faithful Geyser in Yellowstone is one of the most well‐known hydrothermal features in the world. Despite abundant geophysical studies, the structure of Old Faithful's plumbing system beneath ~20‐m depth remained largely elusive. By deploying a temporary dense three‐component geophone array, we observe 1–5 Hz low‐frequency hydrothermal tremor originating from Old Faithful's deeper conduit. By applying seismic interferometry and polarization analyses, we track seismic tremor source migration throughout the eruption/recharge cycle. The tremor source drops rapidly to ~80‐m depth right after the eruption and gradually ascends vertically back to ~20‐m depth, coinciding with the previously inferred bubble trap location. Likely excited by the liquid/steam phase transition, the observed tremor source migration can provide new constraints on the recharge process and deeper conduit geometry. Combined with the shallow conduit structure from previous studies, these results provide constraints on the major fluid pathway down to 80‐m depth.

Ring electrode geometry for microfluidic electrochemistry

We developed a ring electrode sensor for down-stream electrochemical sensing of microfluidic ELISA assay. The sensor is designed to easily integrate into the flow environment. Noble metal inks on Low Temperature Co-fired Ceramic provide straight forward fabrication at the mesoscale yielding robust sensors with very low sensing volumes. Two different sensor geometries were modeled. The best design was fabricated and tested in both static and flowing solutions. The sensor exhibits both macroelectrode and microelectrode behavior depending on fluid flow rate. Sensors of this type may be ideal for applications where electrochemical detection is desired in a flowing solution since the ring electrode has low propensity for bubble trapping.

IAMES: An inexpensive, Automated Methane Ebullition Sensor.

Atmospheric concentrations of methane have increased ∼2.4 fold since the industrial revolution with wetlands and inland waters representing the largest source of methane to the atmosphere. Substantial uncertainties remain in global methane budgets, due in part to the lack of adequate techniques and detailed measurements to assess ebullition in aquatic environments. Here, we present details of a low cost (∼$120 US per unit) ebullition sensor that autonomously logs both volumetric ebullition rate and methane concentrations. The sensor combines a traditional funnel bubble trap with an Arduino logger, a pressure sensor, thermal conductivity methane sensor, and a solenoid valve. Powered by three AA batteries, the sensor can measure autonomously for three months when programmed for a sampling frequency of 30 min. For field testing, four sensors were deployed for six weeks in a small lake. While ebullition was spatially and temporally variable, a distinct diurnal trend was observed with the highest rates from mid-morning to early afternoon. Ebullition rates were similar for all four sensors when integrated over the sampling period. The widespread deployment of low cost automated ebullition sensors such as the iAMES described here will help constrain one of the largest uncertainties in the global methane budget.

Integrated Flow Chamber System for Live Cell Microscopy.

In vitro quantification of the effect of mechanical loads on cells by live microscopy requires precise control of load and culture environment. Corresponding systems are often bulky, their setup and maintenance are time consuming, or the cell yield is low. Here, we show the design and initial testing of a new cell culture system that fits on standard light microscope stages. Based on the parallel plate principle, the system allows for live microscopy of cells exposed to flow-induced shear stress, features short setup time and requires little user interaction. An integrated feedback-controlled heater and a bubble trap enable long observation times. The key design feature is the possibility for quick exchange of the cultured cells. We present first test results that focus on verifying the robustness, biocompatibility, and ease of use of the device.

DIY Isolated Lung Set‐up: Construction and Troubleshooting

Ex-vivo lung preparations have the advantage of being able to study the responses of the lung to drugs or other interventions in a controlled environment without any hemodynamic changes or confounding variables such as a humoral or neuronal input. Assessments that can be taken over time include pulmonary artery pressure (PAP), pulmonary vein pressure (PVP) and airway pressure (AWP). Figure shows a schematic of the lung set-up (numbers in brackets refer to parts of the set-up). A heated reservoir [1] contains a balanced salt perfusate solution (NaCl 119 mM, NaHCO3 24 mM, Glucose 5.5 mM, CaCl2 1.6 mM, KCl 4.7 mM, MgSO4 1.17 mM, NaPO4 1.18 mM) with 4% bovine serum albumin. A sufficiently high and stable glucose concentration is important for the viability of the lung. Thus, due to its glucose metabolism, glucose concentrations must be monitored continuously, or at least every hour, and adjusted by glucose infusions. Stable temperature of the perfusate (37.0–37.5°C) is achieved with a heating plate [2], heating coil and heated bubble trap, with the coil and bubble trap heated by a separate circulating water bath [3]. A roller pump [4], with speed set to 40 cc · min−1 · kg−1 body weight and controlled manually or remotely, pumps the perfusate through the heating coil [5] and the heated bubble trap [6] to the inflow cannula placed in the pulmonary artery. The temperature of the heating coil and bubble trap needs to be adjusted according to the pump speed. To keep the lung warm and moist, it is hung above a heated water bath (~ 48°C) [7]. An outflow cannula placed into the left ventricle connects the pulmonary circulation back to the reservoir to recycle the perfusate. The lung is positive pressure ventilated by a rodent ventilator with, e.g. 30% O2, 5% CO2 and 65% N2, and a tidal volume VT = 10 cc · kg−1 body weight. The positive end-expiratory pressure (PEEP) is set to 2–3 mmHg by a water lock. The pressure transducers, placed at the same height as the lung, are attached to the inflow, outflow and the ventilator to continuously record PAP, PVP and AWP, respectively. They are connected to a data acquisition system via bio amplifiers. A framework made from aluminium rods and rod clamps provides three-dimensional stability. Weekly cleaning of the setup with 5% bleach and 5% HCl is advised to avoid contamination. In summary, the described self-made isolated lung set-up provides maximal flexibility for future adjustments, while being an affordable alternative to more expensive premade set-ups. Support or Funding Information This work was supported, in part, by institutional funds, NIH grant (5R01 HL123227), and a Merit Review Award (I01 BX003482) from the U.S. Department of Veterans Affairs Biomedical Laboratory R&D Service. Isolated lung set-up This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Geometry of Geyser Plumbing Inferred From Ground Deformation

AbstractBroadband seismic data were recorded on the ground surface around an exceptionally regular eruptive system, geyser El Jefe, in the El Tatio geyser field, Chile. We identify two stages in the eruption, recharge and discharge, characterized by a radial expansion and contraction, respectively, of the surface around the geyser. We model the deformation with spherical sources that vary in size, location, and pressure, constrained by pressure observations inside the conduit that are highly correlated with deformation signals. We find that in order to fit the data, the subsurface pressure sources must be laterally offset from the geyser vent during the recharge phase and that they must migrate upward toward the vent during the eruption phase. This pattern is consistent with models in which ascending fluids accumulate and then are released from a bubble trap that is horizontally offset from the shallow conduit of the geyser.

Bubble-free Gonioscopy

Accurate gonioscopy is necessary for the diagnosis and the treatment of glaucoma. The "gold standard" for indirect gonioscopy has been the Goldmann 3-mirror lens, requires an optical coupling agent (methylcellulose) between the cornea and under the surface of the goniolens. The design of an ideal lens would not only eliminate the need for gel, but could at the same time solve the problems associated with the trapping of an air bubble under the lens. This investigation involved a prototype 2-mirror goniolens with a radius of curvature of 8.4 mm and a 16 mm diameter area of corneal contact. A total of, 69 consecutive patients had bilateral keratometer measurements made. The prototype 2-mirror lens was applied to the anesthetized eye. The results of this examination were tabulated by one of the authors (F.M.K.); A=good fit without trapping of air, B=good fit but trapped bubble of air which could be expelled by the patient turning their eye towards the bubble, and C=total failure to expel the trapped bubble of air. Finally, if there were wrinkles in Descemet's membrane, this was recorded. A total of 64 patients were evaluated with a prototype 2-mirror lens. In total, 54/64 (84.38%) of eyes were successfully evaluated without trapping of an air bubble. Our stated goal of eliminating the need for gel as a coupling agent without trapping of an air bubble was successful in 54/64 eyes (84.38%). Our findings could spur development of newer bubble-free goniolenses for procedures such as laser trabeculoplasty.

Fluid oscillations in a laboratory geyser with a bubble trap

Geysers are rare geologic features that episodically erupt water and steam. While it is understood that the eruptions are triggered by the conversion of thermal to kinetic energy during decompression of hot fluids, geysers commonly exhibit a range of dynamic behaviors in-between and during eruptions that have yet to be adequately explained. In-situ measurements of temperature and pressure as well as remote geophysical techniques have revealed oscillatory behavior across a range of timescales from eruption cycles to impulsive bubble collapse events. Many geysers, including Old Faithful in Yellowstone National Park, USA, are believed to have laterally-offset subsurface reservoirs (referred to as a ‘bubble trap’) that can trap and accumulate noncondensable gas or steam entering the system. The impact of a bubble trap on the dynamic behaviors of the system, however, has not been fully established. We constructed a laboratory bubble trap and performed a series of experiments to study how fluids oscillate back and forth between the eruption conduit and laterally-offset reservoir in-between eruptions. We present a new theoretical model based on Hamiltonian mechanics that successfully predicts the oscillation frequencies observed in our experiments based on the conduit system geometry, the amount of gas that has accumulated in the bubble trap, and the amount of liquid water in the system. We demonstrate that when scaled to Old Faithful Geyser, this mechanism is capable of producing oscillations at the observed frequencies.

Vibrational modes prediction for water-air bubbles trapped in circular microcavities

Oscillating bubbles have proven to be a versatile tool for various microfluidic applications. Despite the existence of the extensive literature on the behavior of acoustically actuated bubbles, a ready-to-use approach, capable of predicting the oscillatory motion for the bubbles trapped in the circular microcavities, is still missing. In this study, we propose a theoretical model to quantify the resonant frequencies and viscous dissipation factors for a single trapped bubble and verify it experimentally. We further investigate an interaction of two coupled bubbles of equal and different radii. For the identical bubble pair, coupling results in controllable frequency shift from the modes of a single bubble, whereas the non-identical one can operate as a flow switch.

Bubble breakup dynamics and flow behaviors of a surface-functionalized nanocellulose based nanofluid stabilized foam in constricted microfluidic devices

Nanocellulose was surface-functionalized toward the applications in enhanced oil recovery (EOR) as a green alternative. The focus of this paper is on the effect of this material based nanofluid (NF) on foam lamella stabilization through studying its bubble breakup dynamics and flow behaviors in constricted mircofluidic devices. The NF stabilized foam produced an improved flow resistance across the capillary largely due to the capillary trapped bubbles at the contraction. The “snap-off” caused the NF stabilized foam to produce finer textured bubbles, which can migrate readily forward to the deep porous media, as revealed by the pressure profiles.

Effect of Feather Elasticity of Kingfisher Wing on Droplet Impact Dynamics

We experimentally studied droplet impact dynamics onto wing feathers of kingfishers. Distilled water droplets with a fixed diameter of 2.06 mm were used as drop liquid and the initial impact velocities of droplets varied from 0.28 m·s−1 to 1.60 m·s−1. Two high-speed cameras were utilized to capture the impact process of water droplets onto the wing feather surface from both horizontal and vertical directions. Two states of the feathers (elastic and inelastic) were considered to study the influence of elasticity. At the entire impact velocity range we studied, regular rebound, bubble trapping and jetting, partial pinning and partial rebound of droplets on inelastic wing feather surface were observed as the initial impact velocity increased. However, only one dynamic behavior (regular rebound) was found on the elastic wing feather surface. The elasticity plays a more important role in the direction difference of droplet spreading than wing feather microstructure. The contact time of water droplets on the elastic wing feather surface was less than that on the inelastic surface within the range of Web numbers from 1.06 to 36 under test conditions.

Characterizing foam flow in fractures for enhanced oil recovery

Gas is used in displacing oil for enhanced oil recovery because of its high microscopic-displacement efficiency. However, the process at the reservoir scale suffers from poor sweep efficiency due to density and viscosity differences compared to in-situ fluids. Foam substantially increases the viscosity of injected gas and hence improves the sweep. Foam rheology in 3D geological porous media has been characterized both theoretically and experimentally. In contrast, the knowledge of foam flow in fractured porous media is far less complete. A companion paper (AlQuaimi and Rossen, 2017c), We focused on foam generation and propagation in a fully characterized model fracture. Here we focus on foam rheology in the same model fracture. This investigation is conducted by varying superficial velocities of gas and surfactant solution. We find in this model fracture the same two foam-flow regimes central to the understanding of foam in 3D porous media: a low-quality regime where pressure gradient is independent of liquid velocity and a high-quality regime where pressure gradient is independent of gas velocity. The transition between regimes is less abrupt than in 3D porous media. Our study directly relates flow regime to foam texture through observation of bubble size, bubble trapping and mobilization, and foam stability as functions of superficial velocities which allows comparison with our understanding of the mechanisms behind the two flow regimes in 3D porous media. Additionally, foam is shear-thinning in both regimes. However, the mechanisms thought to be behind the two flow regimes in 3D porous media do not appear in our model fracture. Foam is not at the limit of stability in the high-quality regime. Mobility in the high-quality regime, instead, reflects reduced and fluctuating foam generation at high foam quality. Moreover, bubble size is not fixed at approximately pore size, the mechanism thought to control the low-quality regime in 3D porous media. Instead, bubbles are much smaller than pores. Finally, for this model fracture, the investigation of vertical flow reaches the same findings as for horizontal flow, with somewhat lower pressure gradient.

Asymmetric transfer of CO2 across a broken sea surface

Most estimates of the climatically-important transfer of atmospheric gases into, and out of, the ocean assume that the ocean surface is unbroken by breaking waves. However the trapping of bubbles of atmospheric gases in the ocean by breaking waves introduces an asymmetry in this flux. This asymmetry occurs as a bias towards injecting gas into the ocean where it dissolves, and against the evasion/exsolution of previously-dissolved gas coming out of solution from the oceans and eventually reaching the atmosphere. Here we use at-sea measurements and modelling of the bubble clouds beneath the ocean surface to show that the numbers of large bubbles found metres below the sea surface in high winds are sufficient to drive a large and asymmetric flux of carbon dioxide. Our results imply a much larger asymmetry for carbon dioxide than previously proposed. This asymmetry contradicts an assumption inherent in most existing estimates of ocean-atmosphere gas transfer. The geochemical and climate implications include an enhanced invasion of carbon dioxide into the stormy temperate and polar seas.

Self-organized nanostructures forming under high-repetition rate femtosecond laser bulk-heating of fused silica.

Femtosecond laser exposure of fused silica can lead to non-linear absorption, eventually causing structural modifications in the material. Above a given pulse repetition frequency, the effects from one pulse to the next one become cumulative leading to a localized bulk heating of the substrate, and in turn, to the dissociation of the glass matrix leading to gas bubbles formation. Here, we investigate the dynamics of bubbles formation as a function of the incoming net fluence. In particular, we observe evidences of laser trapping of gas bubbles and the unexpected formation of self-organized nanostructures, resembling nanogratings normally found at much lower repetition rate, i.e. when cumulative effects are absent.

Thermographic analysis of interfacial heat transfer mechanisms on droplet/wall interactions with high temporal and spatial resolution

This paper explores the use of time resolved infrared (IR) thermography combined with high-speed imaging to describe the liquid-surface interfacial heat transfer phenomena occurring at droplet/wall interactions. A first set of experiments is used to infer on the validation of custom made calibration and post-processing methods to evaluate the potential to obtain accurate data, useful to describe the observed phenomena. In this context, the technique showed good potential to capture very well particular details on droplet dynamics and heat transfer, allowing to identify air bubble trapping at the impact region, as well as the temperature variations at the formation of the rim. The combined analysis of droplet dynamics (e.g. the spreading factor) with the radial temperature profiles, heat flux and cooling effectiveness allowed establishing qualitative and quantitative trends on the effect of various parameters on the heat transfer occurring at droplet/wall interactions. Particularly, details on the temperature distribution within the lamella, reflected on the surface temperature fields, which are related to the spreading dynamics, are explored and discussed. Furthermore, extreme wetting scenarios, such as superhydrophobicity are studied in detail. The analysis performed show that they limit the heat transfer between the droplet and the surface. However, the thermal analysis coupled with the spreading dynamics reveals that a major reason for this is not just related to the reduced contact time of the droplet (due to rebound) or air entrapment, but is also associated to the reduced wetted area caused by low wettability, which is not obvious from the analysis of the spreading diameter alone, but becomes evident when this is coupled with the evaluation of the temperature fields on the heated surface.

Nano-Oxide-Dispersed Ferritic Steel for Fusion Energy Systems

ABSTRACTThe role of oxide nanoparticles in cavity formation of a nano-oxide-dispersed ferritic steel subjected to (Fe + He) dual-ion and (Fe + He + H) triple-ion irradiations has been studied using transmission electron microscopy to elucidate the synergistic effects of helium and hydrogen on radiation tolerance of nano-oxide-dispersed ferritic steel for fusion energy systems. The effect of oxide nanoparticles on suppressing radiation-induced void swelling is clearly revealed from the observation of preferred trapping of helium bubbles at oxide nanoparticles, which results in a unimodal distribution of cavities in the (Fe + He) dual-ion irradiated specimen. An adverse effect of hydrogen implantation, however, is revealed from the observation of a bimodal distribution of cavities with large and facetted voids in association with the formation of HFe5O8-based hydroxide in local regions of the (Fe + He + H) triple-ion irradiated specimen.

Filling angle and its effect on filling process in roll-to-roll ultraviolet imprint lithography

Bubble defects are a serious problem in the roll-to-roll ultraviolet imprint lithography process. To investigate the air bubble trapping in microcavities, a numerical simulation method is proposed based on a sliding mesh and open-channel model. Such considerations in the model make it possible to include both the rotation of the roller and the flow of resin, which is different from the conventional methods. Through analysis with our model, a parameter, termed filling angle here, is found to be a significant factor in the imprinting process. With this parameter, the relationships between resin accumulation and bubble defects are studied. The differences in resin filling at different rotation velocities are also discussed. The experimental observations are in good agreement with the theoretical calculations. The results provide a deep understanding of the filling process, which can provide good theoretical guidance to eliminating bubble defects in industrial applications.