Inside Bubble Research Articles

Subretinal Foveal PFCL Micro-Droplets Removal “Bubble Inside Bubble” (BIB) Technique Without Intraoperative OCT

Subretinal Foveal PFCL Micro-Droplets Removal “Bubble Inside Bubble” (BIB) Technique Without Intraoperative OCT

Spectral softening in core-collapse supernova remnant expanding inside wind-blown bubble

Context. Galactic cosmic rays (CRs) are widely assumed to arise from diffusive shock acceleration, specifically at shocks in supernova remnants (SNRs). These shocks expand in a complex environment, particularly in the core-collapse scenario as these SNRs evolve inside the wind-blown bubbles created by their progenitor stars. The CRs at core-collapse SNRs may carry spectral signatures of that complexity. Aims. We study particle acceleration in the core-collapse SNR of a progenitor with an initial mass of 60 M⊙ and realistic stellar evolution. The SNR shock interacts with discontinuities inside the wind-blown bubble and generates several transmitted and reflected shocks. We analyse their impact on particle spectra and the resulting emission from the remnant. Methods. To model the particle acceleration at the forward shock of a SNR expanding inside a wind bubble, we initially simulated the evolution of the pre-supernova circumstellar medium (CSM) by solving the hydrodynamic equations for the entire lifetime of the progenitor star. As the large-scale magnetic field, we considered parameterised circumstellar magnetic field with passive field transport. We then solved the hydrodynamic equations for the evolution of a SNR inside the pre-supernova CSM simultaneously with the transport equation for CRs in test-particle approximation and with the induction equation for the magnetohydrodynamics in 1D spherical symmetry. Results. The evolution of a core-collapse SNR inside a complex wind-blown bubble modifies the spectra of both the particles and their emission on account of several factors including density fluctuations, temperature variations, and the magnetic field configuration. We find softer particle spectra with spectral indices close to 2.5 during shock propagation inside the shocked wind, and this softness persists at later evolutionary stages. Further, our calculated total production spectrum released into the interstellar medium demonstrates spectral consistency at high energy (HE) with the injection spectrum of Galactic CRs, which is required in propagation models. The magnetic field structure effectively influences the emission morphology of SNRs as it governs the transportation of particles and the synchrotron emissivity. There is rarely a full correspondence of the intensity morphology in the radio, X-ray, and gamma-ray bands.

Age-dependency of the Propagation Rate of Coronavirus Disease 2019 Inside School Bubble Groups in Catalonia, Spain.

Background:We analyzed contagions of coronavirus disease 2019 inside school bubble groups in Catalonia, Spain, in the presence of strong nonpharmaceutical interventions from September to December 2020. More than 1 million students were organized in bubble groups and monitored and analyzed by the Health and the Educational departments.Methods:We had access to 2 data sources, and both were employed for the analysis, one is the Catalan school surveillance system and the other of the educational department. As soon as a positive index case is detected by the health system, isolation is required for all members of the bubble group, in addition to a mandatory proactive systematic screening of each individual. All infected cases are reported. It permits the calculation of the average reproductive number (R*), corresponding to the average number of infected individuals per index case.Results:We found that propagation inside of the bubble group was small. Among 75% index cases, there was no transmission to other members in the classroom, with an average R* across all ages inside the bubble of R* = 0.4. We found a significant age trend in the secondary attack rates, with the R* going from 0.2 in preschool to 0.6 in high school youth.Conclusions:The secondary attack rate depends on the school level and therefore on the age. Super-spreading events (outbreaks of 5 cases or more) in childhood were rare, only occurring in 2.5% of all infections triggered from a pediatric index case.

Assessment of VoF based numerical scheme for bubble rise in isothermal liquid layer, and some new insight in thermally stratified liquid layers

This paper aims at (a) comparative assessment of the different volume of fluid (VoF) based numerical schemes for a rising, single air bubble in isothermal liquid (water) layers and (b) investigation of bubble rise in thermally stratified liquid (therminol) layers. For numerical investigation of bubble rise in isothermal liquid layers, three available numerical schemes, Upwind, Quadratic Upstream Interpolation for Convective Kinematics (QUICK) and Monotonic Upwind Scheme for Conservation Laws (MUSCL) schemes, combined with the pressure-velocity coupling(p-v) approaches, such as, Pressure Implicit with Splitting of Operators (PISO) and Semi Implicit Method for Pressure-Linked Equations (SIMPLE), are considered. The wake analysis revealed that the region of influence grows beyond 10 times the diameter of the bubble. Moreover, based on the comparative assessment, MUSCL scheme with PISO is selected, for investigating the bubble rise in thermally stratified therminol layers. Based on these investigations, a 3D diagram, describing bubble shape as f (Ra, Eo, Ga), is proposed, and a new insight to the micro-convection, inside the rising bubbles is provided. Furthermore, a time-scale analysis is performed to describe the heat transfer mechanisms, (a) inside air bubble, and (b) between air bubble and the external surrounding liquid. Thus, the findings will be useful for the design of heat exchangers or cooling devices, which rely on the heat transfer augmentation with rising air bubble.

The “molecule diode” effect caused by adsorbed surfactant layers improves evaporation efficiency in the bubble column evaporator (BCE) for seawater desalination

The bubble column evaporator (BCE) can be used as an improved thermal desalination technology simply based on pumping a heated gas, such as helium, through a porous sinter to produce hot gas bubbles to transfer heat and mass across the water-gas interface. In this paper, a “molecule diode” effect caused by surfactant monolayers has been proposed, because adding surfactants into the column solution produced an improved evaporation efficiency. The mechanism involved appears to be based on enhancing water molecule transport across the bubble surfaces from the column solution via the hydrophilic headgroups, whilst restricting water vapour molecules returning to the solution because of the layer of hydrophobic tails coating the inside bubble surface. In this paper, the enthalpy of vaporization (△Hv) was estimated, and the bubble saturation period and the bubbling and foaming behaviour was observed, to study the performance of surfactants on improving the evaporation efficiency achieved by the BCE process. Myristyltrimethylammonium bromide (MAB), a typical cationic surfactant, combined with the moderately heated helium bubbles generated in the BCE column, performed best by reducing the apparent △Hv value for water by 15 % and increasing the evaporation efficiency by 2.3 times, compared with the value for non-surfactant column solutions pumped with air, which demonstrates the potential for a low cost thermal desalination technology based on this sub-boiling process.

Fluid Velocity Prediction Inside Bubble Column Reactor Using ANFIS Algorithm Based on CFD Input Data

Fluid Velocity Prediction Inside Bubble Column Reactor Using ANFIS Algorithm Based on CFD Input Data

Estimation of Hydroxyl Radicals Produced by Pulsed Discharge Inside Bubble in Water Using Indigo Carmine as Chemical Probe

Amount of hydroxyl radicals produced by pulsed discharge inside bubble in water is estimated with the decomposition of indigo carmine as a chemical probe. Argon gas (99.99 vol.% purity) is injected into the water through a vertically positioned glass tube, in which high-voltage wire electrode is placed to generate plasmas at low applied voltage. Amount of the indigo carmine decomposition increases with increasing indigo carmine concentration and held a constant value at $1.5 {\times} 10^{-6}$ mol when indigo carmine concentration is higher than 2.5 mM. The amount of hydroxyl radicals is estimated as $1.3 \times 10^{-6}$ mol by measuring the hydrogen peroxide production in the potassium solution, which corresponds to the amount of hydroxyl radicals obtained from indigo carmine decomposition. The energy yield of dissolved hydroxyl radical, which contributes to react with the solutes in the solutions, is estimated to be 4 ~ $5 \times 10^{-9}$ mol/J.

A model to evaluate unstable ductile crack arrestability of offshore pipeline

We developed the first model to evaluate unstable ductile crack arrestability in offshore pipelines. The proposed model is an integrated one-dimensional model with four sub-models to calculate (a) pipe deformation, (b) gas flow inside pipe, (c) bubble growth, and (d) crack propagation. We validated the proposed model by applying it to two types of tests: laboratory scale underwater rupture tests and existing data of a full-scale burst test of an offshore pipeline. In addition, the calculation results of the proposed model showed that a deep water depth results in increased unstable crack arrestability of the pipeline.

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

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

Numerical modeling of gravity-driven bubble flows with account of polydispersion

The present study is focused on the investigation of motion of bubble-liquid medium inside the bubble columns or vertical pipes with account of polydisperse phenomena by the means of numerical simulation. The underlying mathematical model is based on the Euler- Euler approach with interphase interaction described by the momentum and mass transfer between phases, along with the k-w-SST turbulence model which includes turbulence generation by the bubble motion and bubble path dispersion. Polydispersion is taken into account by the multi-class model with piecewise-constant distribution of bubble sizes per cell. Simulation of downward flow inside the straight vertical pipe resulted in maximum of the bubble void fraction close to the pipe center which is in good correlation with the experimental data. Simulation of multiphase flow inside rectangular bubble column with off-center sparger resulted in vertical bubble-liquid jet which is biased towards nearby wall with the correct prediction of attachment point location.

Switching bubbles: From Outside to Inside Bubbles

The United States has recently experienced two asset price bubbles: the Dot-Com and the Housing Bubbles. These bubbles had very different effects on investment and debt of manufacturing firms. In this paper I develop a framework to understand the differential effect of two types of rational bubbles. I distinguish between (i) Outside Bubbles, which I define as savers purchasing and selling costless assets not-attached to inputs of production and (ii) Inside Bubbles, which I define as savers buying an input of production (e.g., land or houses) only as a store of value. The model is an OLG economy with savers and entrepreneurs. Savers save to consume when they are old. Entrepreneurs can borrow to invest but they face a collateral constraint. In this environment, rational bubbles can emerge. I show that the size of an Inside Bubble is larger. I also find that when the economy switches from an Outside to an Inside Bubble, manufacturing (or non-housing) investment and debt is lower, consistent with the U.S. experience. Finally, I show that even though steady-state consumption is higher with an Outside Bubble, a social planner would prefer an Inside Bubble when the productivity of entrepreneurs is low.

Simultaneous Decomposition of Phenol and Sodium Formate by Discharge Inside Bubble in Water

Simultaneous Decomposition of Phenol and Sodium Formate by Discharge Inside Bubble in Water

アルゴンガスを用いた水中気泡内放電による有機染料の脱色におけるパルス幅のエネルギー効率への影響

アルゴンガスを用いた水中気泡内放電による有機染料の脱色におけるパルス幅のエネルギー効率への影響

Giga-electronvolt electrons due to a transition from laser wakefield acceleration to plasma wakefield acceleration

We show through experiments that a transition from laser wakefield acceleration (LWFA) regime to a plasma wakefield acceleration (PWFA) regime can drive electrons up to energies close to the GeV level. Initially, the acceleration mechanism is dominated by the bubble created by the laser in the nonlinear regime of LWFA, leading to an injection of a large number of electrons. After propagation beyond the depletion length, leading to a depletion of the laser pulse, whose transverse ponderomotive force is not able to sustain the bubble anymore, the high energy dense bunch of electrons propagating inside bubble will drive its own wakefield by a PWFA regime. This wakefield will be able to trap and accelerate a population of electrons up to the GeV level during this second stage. Three dimensional particle-in-cell simulations support this analysis and confirm the scenario.

Investigating the possibility of Sonofusion in Deuterated acetone

In this article, energetic implosion of a single vapor bubble induced by a standing acoustic wave is theoretically studied and the Sonoluminescing bubble parameters involved in Sonofusion in Deuterated acetone (C 3 D 6 O) are investigated. Parameters such as radius, wall velocity, interior temperature and pressure of the bubble influenced by various driving pressure amplitudes in Deuterated acetone at ∼0 °C are investigated. Based on the obtained results, the possibility of thermonuclear fusion inside imploding cavitation bubbles is discussed. The interior pressure of C 3 D 6 O vapor bubbles at the collapse time is extremely high and the increase of the pressure amplitude increases the pressure inside the bubble. Our findings reveal that the maximum temperature inside acoustic-induced cavitation bubble in Deuterated acetone increases with the acoustic pressure amplitude and it is much higher than the maximum temperature inside acoustic induced cavitation bubbles in liquids such as water and acids. Consequently, the calculated temperature at the pressure amplitude of 7.23 bar was about 3.7 × 10 5 K and it is predicted that at the reported experimental condition, the case of a bubble cluster subjected to the pressure amplitude of about 15 bar, the temperature inside the bubble reaches to 1.2 × 10 6 K. • The Sonoluminescing bubble parameters involved in Sonofusion are obtained. • Increasing acoustic pressure amplitude increases maximum temperature inside bubble. • Temperature inside C 3 D 6 O bubble is much higher than the bubbles in other liquids. • Bubble interior temperature at reported experimental condition can be 10 6 K < T < 10 7 K.

A Numerical Study on Bubble Detachment from Solid Wall and Formation of Jet inside Detached Bubble

A numerical study dedicated to observe bubble detachment phenomena from solid wall has been carried out. The Comsol Multiphysics's level set method has been chosen to perform numerical simulations. Numerical results are clearly evidencing bubble detachment and formation of jet inside detached bubble, which after deforming bubble maneuver inside with relatively higher velocity. Detachment time is found to be a direct function of bubble size and shows linear behavior for various fluids. Detailed study reveals that there exists a bubble size effect on jet formation.

Development of Pulsed Discharge Inside Bubble in Water

The development of pulsed discharges inside a stationary air bubble in water was observed using an intensified charge-coupled device camera with high-speed gate. The discharges were ignited from a tungsten wire inserted into a glass tube, which was immersed in the purified water. The pulsed high voltage was applied to the wire by an inductive energy storage system pulsed-power generator. The streamer discharge was propagated into the bubble from the wire tip with a propagation velocity of 0.5 mm/ns. A back discharge was observed due to a charge accumulation on the water surface and the glass tube.

Sonolysis of chlorobenzene in the presence of transition metal salts

AbstractSonolysis of aqueous solution of chlorobenzene at 200 kHz frequency in the presence of transition metals chlorides was investigated. Through analyzing the nature and distribution of the products detected in the reaction mixture, a new mechanism of sonodegradation is advanced. Depending on the metals used and their behavior during sonolysis, we were able to discriminate between inside and outside cavitation bubble mechanisms. Iron and cobalt chlorides, which could undergo redox reactions in the presence of HO radicals generated ultrasonically, give higher amounts of phenolic compounds compared with palladium chloride that undergoes a reduction to metal. Palladium reduction takes place in bulk solution and therefore all organic reactions that compete for hydrogen must occur also in bulk solution. Accordingly, palladium can be a useful tool in determining the reaction site and the decomposition mechanism of organic compounds under ultrasonic irradiation.

Effect of Water Vapour to Temperature Inside Sonoluminescing Bubble

Using the model based on the homo-pressure approximation, weexplain why the maximum temperature is sensitive to the ambient temperaturein the single bubble sonoluminescence. The numerical simulation shows that themaximum temperature inside a sonoluminescing bubble depends on howmuch water vapour evaporates or coagulates at the bubble wall duringthe bubble shrinking to its minimum size. While the amount of watervapour inside the bubble at the initial and the final state of the compressiondepends on the saturated water vapour pressure which is sensitiveto the ambient temperature. The lower the saturated vapour pressure is,the higher the maximum temperature is. This may lead to more generalconclusion that those liquids with lower saturated vapour pressureare more favourable for the single bubble sonoluminescence. We alsocompare those bubbles with different noble gases, the result showsthat the maximum temperatures in the different gas bubbles arealmost the same for those with the same ambient temperature.

Biaxial orientation of polyamide films: processability and properties

The production of biaxially oriented films can be performed with two techniques: the tenter frame and the double bubble process. The most important difference between the two processes is that in tubular orientation the MD and TD stretching are simultaneous. This event is very important specially in the case of biaxially oriented polyamide films to avoid hydrogen bonding which occur during the first stretching stage of tenter frame process and cause resistance to subsequent transverse direction orientation (1-4). Double bubble process consists in the stretching of a tubular film where the stretching ratios in the machine and transverse directions are determined by inside bubble pressure and the difference in roll speeds between the two sets of nips rolls that contain the bubble. The work presented here reports some results about double bubble polyamide films realised with a laboratory scale system. The study concerns the processability (5-6) of two different polyamides: a nylon 6 (PA6) and a copolymer of the nylon 6 with isophthalic acid and isophorondiamine (PA6 - IPA.IPD) at 5% w/w of comonomer. Two main process arrangements where adopted differing for first bubble cooling technique: a water cooling and a air cooling. The films produced in both conditions were then characterised with a particular regard to mechanical and barrier performances. Morphological analyses were also carried out in order to correlate the process conditions to structure and properties of films.