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Bernstein, Lawrence S., i Mitchell R. Zakin. "Confined Electron Model for Single-Bubble Sonoluminescence". Journal of Physical Chemistry 99, nr 40 (październik 1995): 14619–27. http://dx.doi.org/10.1021/j100040a008.
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Kurata, Nobuhiko, i Takahide Oya. "Design of “bubble-inspired single-electron circuit” mimicking behavior of bubble film". Nonlinear Theory and Its Applications, IEICE 10, nr 4 (2019): 399–413. http://dx.doi.org/10.1587/nolta.10.399.
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Gareev B. M. i Sharipov G. L. "Atomic luminescence of Ag during single-bubble sonolysis of silver nanoparticles aqueous suspension". Technical Physics Letters 48, nr 14 (2022): 59. http://dx.doi.org/10.21883/tpl.2022.14.55120.18917.
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For the first time, luminescence of Ag atoms was recorded during moving single-bubble sonolysis of silver nanoparticles aqueous colloidal suspension. This glow is caused by the entry of nanoparticles into a bubble deformable during motion and their decomposition to atoms with collisional excitation in the nonequilibrium plasma of the bubble. Nanoparticles were obtained by multibubble sonolysis of an AgNO3 solution with the addition of honey. This method was used to synthesize a stable suspension of Ag nanoparticles with an average size of ~ 10 nm. By comparing the experimental spectrum of this suspension and simulated spectra of Ag, the electron temperature in the bubble plasma was found to be ~ 10 000 K. Keywords: single-bubble sonoluminescence, silver nanoparticles, electron plasma temperature.
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Heller, R., R. Jacob, D. Schönberner i M. Steffen. "Hot bubbles of planetary nebulae with hydrogen-deficient winds". Astronomy & Astrophysics 620 (grudzień 2018): A98. http://dx.doi.org/10.1051/0004-6361/201832683.
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Context. The first high-resolution X-ray spectroscopy of a planetary nebula, BD +30° 3639, opened the possibility to study plasma conditions and chemical compositions of X-ray emitting “hot” bubbles of planetary nebulae in much greater detail than before. Aims. We investigate (i) how diagnostic line ratios are influenced by the bubble’s thermal structure and chemical profile, (ii) whether the chemical composition inside the bubble of BD +30° 3639 is consistent with the hydrogen-poor composition of the stellar photosphere and wind, and (iii) whether hydrogen-rich nebular matter has already been added to the bubble of BD +30° 3639 by evaporation. Methods. We applied an analytical, one-dimensional (1D) model for wind-blown bubbles with temperature and density profiles based on self-similar solutions including thermal conduction. We also constructed heat-conduction bubbles with a chemical stratification. The X-ray emission was computed using the well-documented CHIANTI code. These bubble models are used to re-analyse the high-resolution X-ray spectrum from the hot bubble of BD +30° 3639. Results. We found that our 1D heat-conducting bubble models reproduce the observed line ratios much better than plasmas with single electron temperatures. In particular, all the temperature- and abundance-sensitive line ratios are consistent with BD +30° 3639 X-ray observations for (i) an intervening column density of neutral hydrogen, NH = 0.20-0.10+0.05 × 1022cm−2, (ii) a characteristic bubble X-ray temperature of TX = 1.8 ± 0.1 MK together with (iii) a very high neon mass fraction of about 0.05, virtually as high as that of oxygen. For lower values of NH, we cannot exclude the possibility that the hot bubble of BD +30° 3639 contains a small amount of “evaporated” (or mixed) hydrogen-rich nebular matter. Given the possible range of NH, the fraction of evaporated hydrogen-rich matter cannot exceed 3% of the bubble mass. Conclusions. The diffuse X-ray emission from BD +30° 3639 can be well explained by models of wind-blown bubbles with thermal conduction and a chemical composition equal to that of the hydrogen-poor and carbon-, oxygen-, and neon-rich stellar surface.
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GAREEV, B. M., A. M. ABDRAKHMANOV i G. L. SHARIPOV. "SONOLUMINESCENCE SPECTROSCOPY OF COLLOIDAL SUSPENSIONS: MOLECULAR, IONIC AND ATOMIC LUMINESCENCE DURING SONOCHEMICAL DECOMPOSITION OF SILICON DIOXIDE NANOPARTICLES CONTAINING RUTHENIUM AND COPPER COMPOUNDS". Izvestia Ufimskogo Nauchnogo Tsentra RAN, nr 4 (13.12.2021): 16–21. http://dx.doi.org/10.31040/2222-8349-2021-0-4-16-21.
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The article is devoted to an example of the sonoluminescence spectroscopy use, which was previously known as a method for analyzing substances from the characteristic spectra of their sonoluminescence only in true solutions, for carrying out a similar analysis of substances contained in insoluble nanoparticles in colloidal suspensions. The solutions sonolysis, that is, their irradiation with ultrasound, is accompanied by the formation of cavitation bubbles that vibrate radially at the frequency of the ultrasonic field. Volatile components of the solution enter the bubbles, evaporating from the liquid-gas interface; nonvolatile components can penetrate into the bubble as a result of the injection of solution nanodroplets into the gas phase, which occurs during intense bubble movements accompanied by their deformation. In a nonequilibrium plasma periodically forming in cavitation bubbles, destruction occurs, as well as collisional excitation of these components, followed by luminescence. It has been shown that this mechanism of sonoluminescence also operates in colloidal suspensions, where substances are present in the form of nanoparticles with sizes less than 50 nm. Such nanoparticles penetrate into moving cavitation bubbles, without destroying them, as part of nanodroplets, and then undergo decomposition in bubble plasma with the excited particles generation as emitters of characteristic sonoluminescence. In this work, we synthesized colloidal suspensions in dodecane of porous SiO2 nanoparticles containing adsorbed Ru(bpy)3Cl2 and CuSO4 salts. During moving single-bubble sonolysis for these suspensions, characteristic emission spectra of Ru and Cu atoms, SiO molecules, and Ru(bpy)3 ions suitable for sonoluminescence spectroscopic analysis were recorded. By comparing the experimental and calculated (at different temperatures) luminescence spectra of Ru atoms, we estimated the electron temperature attained upon acoustic compression of single bubble in colloidal suspension in dodecane: Te = 7000 K.
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Zhang, Feifei, Lynn Boatner, Yanwen Zhang, Di Chen, Yongqiang Wang i Lumin Wang. "Swelling and Helium Bubble Morphology in a Cryogenically Treated FeCrNi Alloy with Martensitic Transformation and Reversion after Helium Implantation". Materials 12, nr 17 (2.09.2019): 2821. http://dx.doi.org/10.3390/ma12172821.
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A cryo-quenched 70 wt % Fe-15 wt% Cr-15 wt% Ni single-crystal alloy with fcc (face centered cubic), bcc (body centered cubic), and hcp (hexagonal close packed) phases was implanted with 200 keV He+ ions up to 2 × 1017 ions·cm−2 at 773 K. Surface-relief features were observed subsequent to the He+ ion implantation, and transmission electron microscopy was used to characterize both the surface relief properties and the details of associated “swelling effects” arising cumulatively from the austenitic-to-martensitic phase transformation and helium ion-induced bubble evolution in the single-crystal ternary alloy. The bubble size in the bcc phase was found to be larger than that in the fcc phase, while the bubble density in the bcc phase was correspondingly lower. The phase boundaries with misfit dislocations formed during the martensitic transformation and reversion processes served as helium traps that dispersed the helium bubble distribution. Swelling caused by the phase transformation in the alloy was dominant compared to that caused by helium bubble formation due to the limited depth of the helium ion implantation. The detailed morphology of helium bubbles formed in the bcc, hcp, and fcc phases were compared and correlated with the characters of each phase. The helium diffusion coefficient under irradiation at 773 K in the bcc phase was much higher (i.e., by several orders of magnitude) than that in the fcc phase and led to faster bubble growth. Moreover, the misfit phase boundaries were shown to be effective sites for the diffusion of helium atoms. This feature may be considered to be a desirable property for improving the radiation tolerance of the subject, ternary alloy.
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SHARIPOV, G. L., B. M. GAREEV, A. M. ABDRAKHMANOV i L. R. YAKSHEMBETOVA. "ACTIVATION OF SINGLE-BUBBLE SONOLUMINESCENCE AND RADIOLUMINESCENCE OF GD3+ AND DY3+ IONS BY ELECTRON ACCEPTORS IN AQUEOUS SOLUTIONS AS CONSEQUENCE OF THE HYDRATED ELECTRON GENERATION DURING WATER SONOLYSIS AND RADIOLYSIS". Izvestia Ufimskogo Nauchnogo Tsentra RAN, nr 4 (13.12.2021): 22–29. http://dx.doi.org/10.31040/2222-8349-2021-0-4-22-29.
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Discovered the activation of moving single-bubble sonoluminescence and radioluminescence for Gd3+ and Dy3+ ions in aqueous solutions of GdCl3 and DyCl3 by the acceptor of a hydrated electron (eaq-): H+, Cd2+, etc. This activation is similar to the previously found activation by acceptors of eaq- radioluminescence and single-bubble sonoluminescence for the Tb3+ ion. Electron acceptors do not affect the quantum yield of the said lantha-nide ions photoluminescence. They also do not affect the yield of their multibubble sonoluminescence in aqueous solutions, since eaqdoes not appear in significant amounts during multibubble sonolysis. The found luminescence activation effects of lanthanide ions are interpreted as a consequence of the suppression of the quenching (reduction) reactions of these electronically excited ions eaq: *Ln3+ + eaq- → Ln2+ by acceptors. The feasibility of these reactions was predicted for all Ln3+ ions based on a theoretical estimate of their free energy. The discovery of the described effects of activation of the luminescence of Ln3+ ions is a consequence and serves as confirmation of not only the known generation of eaq- during radiolysis, but also its previously unknown generation during moving single-bubble sonolysis of water.
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Memoli, Gianluca, Kate Baxter, Helen Jones, Ken Mingard i Bajram Zeqiri. "Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces". Micromachines 9, nr 8 (15.08.2018): 404. http://dx.doi.org/10.3390/mi9080404.
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The acoustically-driven dynamics of isolated particle-like objects in microfluidic environments is a well-characterised phenomenon, which has been the subject of many studies. Conversely, very few acoustofluidic researchers looked at coated microbubbles, despite their widespread use in diagnostic imaging and the need for a precise characterisation of their acoustically-driven behaviour, underpinning therapeutic applications. The main reason is that microbubbles behave differently, due to their larger compressibility, exhibiting much stronger interactions with the unperturbed acoustic field (primary Bjerknes forces) or with other bubbles (secondary Bjerknes forces). In this paper, we study the translational dynamics of commercially-available polymer-coated microbubbles in a standing-wave acoustofluidic device. At increasing acoustic driving pressures, we measure acoustic forces on isolated bubbles, quantify bubble-bubble interaction forces during doublet formation and study the occurrence of sub-wavelength structures during aggregation. We present a dynamic characterisation of microbubble compressibility with acoustic pressure, highlighting a threshold pressure below which bubbles can be treated as uncoated. Thanks to benchmarking measurements under a scanning electron microscope, we interpret this threshold as the onset of buckling, providing a quantitative measurement of this parameter at the single-bubble level. For acoustofluidic applications, our results highlight the limitations of treating microbubbles as a special case of solid particles. Our findings will impact applications where knowing the buckling pressure of coated microbubbles has a key role, like diagnostics and drug delivery.
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GLINEC, Y., J. FAURE, A. PUKHOV, S. KISELEV, S. GORDIENKO, B. MERCIER i V. MALKA. "Generation of quasi-monoenergetic electron beams using ultrashort and ultraintense laser pulses". Laser and Particle Beams 23, nr 2 (czerwiec 2005): 161–66. http://dx.doi.org/10.1017/s0263034605050275.
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Plasma-based accelerators have been proposed for the next generation of compact accelerators because of the huge electric fields they can support. However, it has been difficult to use them efficiently for applications because they produce poor quality particle beams with large energy spreads. Here, we demonstrate a dramatic enhancement in the quality of electron beams produced in laser-plasma interaction: an ultrashort laser pulse drives a plasma bubble which traps and accelerates plasma electrons to a single energy. This produces an extremely collimated and quasi-monoenergetic electron beam with a high charge of 0.5 nanocoulomb at energy 170 ± 20 MeV.
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Гареев, Б. М., i Г. Л. Шарипов. "Атомарная люминесценция Ag при однопузырьковом сонолизе водной суспензии наночастиц серебра". Письма в журнал технической физики 47, nr 22 (2021): 17. http://dx.doi.org/10.21883/pjtf.2021.22.51720.18917.
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For the first time, luminescence of Ag atoms was recorded during moving single-bubble sonolysis of silver nanoparticles aqueous colloidal suspension. This glow is caused by the entry of nanoparticles into a bubble deformable during motion and their decomposition to atoms with collisional excitation in the nonequilibrium plasma of the bubble. Nanoparticles were obtained by multibubble sonolysis of an AgNO3 solution with the addition of honey. This method was used to synthesize a stable suspension of Ag nanoparticles with an average size of ~ 10 nm. By comparing the experimental spectrum of this suspension and simulated spectra of Ag, the electron temperature in the bubble plasma was found to be ~ 10000 K.
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Li, Jun, Rui Yan, Bin Zhao, Jian Zheng, Huasen Zhang i Xiyun Lu. "Mitigation of the ablative Rayleigh–Taylor instability by nonlocal electron heat transport". Matter and Radiation at Extremes 7, nr 5 (1.09.2022): 055902. http://dx.doi.org/10.1063/5.0088058.
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The effects of electron nonlocal heat transport (NLHT) on the two-dimensional single-mode ablative Rayleigh–Taylor instability (ARTI) up to the highly nonlinear phase are reported for the first time through numerical simulations with a multigroup diffusion model. It is found that as well as its role in the linear stabilization of ARTI growth, NLHT can also mitigate ARTI bubble nonlinear growth after the first saturation to the classical terminal velocity, compared with what is predicted by the local Spitzer–Härm model. The key factor affecting the reduction in the linear growth rate is the enhancement of the ablation velocity V a by preheating. It is found that NLHT mitigates nonlinear bubble growth through a mechanism involving reduction of vorticity generation. NLHT enhances ablation near the spike tip and slows down the spike, leading to weaker vortex generation as the pump of bubble reacceleration in the nonlinear stage. NLHT more effectively reduces the nonlinear growth of shorter-wavelength ARTI modes seeded by the laser imprinting phase in direct-drive laser fusion.
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Hayami, Satoru. "Temperature-driven transition from skyrmion to bubble crystals in centrosymmetric itinerant magnets". New Journal of Physics 23, nr 11 (1.11.2021): 113032. http://dx.doi.org/10.1088/1367-2630/ac3683.
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Abstract Interplay between itinerant electrons and localized spins in itinerant magnets gives rise to a variety of noncoplanar multiple-Q spin textures, such as the skyrmion, hedgehog, meron, and vortex. We elucidate that another type of multiple-Q state consisting of collinear sinusoidal waves, a magnetic bubble crystal, appears at finite temperatures in a centrosymmetric itinerant electron system. The results are obtained for the classical Kondo lattice model with easy-axis single-ion anisotropy on a triangular lattice by a large-scale numerical simulation. We find that a finite-temperature topological phase transition between the skyrmion crystal and the bubble crystal occurs by changing the temperature. We obtain the minimal key ingredients for inducing the finite-temperature transition by analyzing an effective spin model where it is shown that the synergy between the multiple-spin interaction and magnetic anisotropy plays a significant role.
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Гареев, Б. М., А. М. Абдрахманов i Г. Л. Шарипов. "Атомарная однопузырьковая сонолюминесценция иттербия в коллоидной суспензии". Письма в журнал технической физики 48, nr 16 (2022): 18. http://dx.doi.org/10.21883/pjtf.2022.16.53201.19269.
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For the first time, atomic single-bubble sonoluminescence of Yb in a colloidal suspension in dodecane of SiO2 nanoparticles containing YbCl3 was recorded. A spectrum was obtained containing Yb, Yb+ lines in the region of 300-550 nm, together with SiO lines, due to the entry of nanoparticles into the bubble during sonolysis of the suspension. The lower limit of determination of ytterbium in the initial aqueous solution of YbCl3 used for depositing onto nanoparticles, according to the intensity of the analytical line at 399 nm in this spectrum, is 3∙10–3 mol/l. By comparing the experimental and temperature-dependent calculated spectra of ytterbium, we found the electron temperature in the nonequilibrium plasma that arises during bubble collapse, where Yb atoms emit light: Te = 7000±500 K.
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Graber, M., B. Lane, R. Lamia i E. Pastoriza-Munoz. "Bubble cells: renal tubular cells in the urinary sediment with characteristics of viability." Journal of the American Society of Nephrology 1, nr 7 (styczeń 1991): 999–1004. http://dx.doi.org/10.1681/asn.v17999.
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The urinary sediment was examined by light microscopy in 65 consecutive inpatients with renal insufficiency (not due to pre- or postrenal factors) referred to a nephrology consult service for evaluation. In the 60 patients in whom a single diagnosis was reached, the sediments of 34 (57%) contained an easily recognized cell, which we have called the "bubble cell". These cells were bizarre, large cells with a single nucleus, which appeared to contain one or more fluid-filled vesicles. Bubble cells were most prevalent in the sediment of patients with acute tubular necrosis but were also seen a variety of other renal diseases. In most patients with acute tubular necrosis, the sediment also contained "normal"-appearing renal tubular cells, muddy brown casts, and oval fat bodies which were indistinguishable from those seen in the nephrotic syndrome. By electron microscopy, the bubble cells appeared to be vacuolated renal tubular epithelial cells, which had characteristics of viable cells. Most bubble cells excluded the vital dye Trypan blue, whereas the normal-appearing renal tubular cells were typically strongly positive. It was concluded that bubble cells, often accompanied by oval fat bodies, are commonly present in the sediment of patients with acute tubular necrosis as well as many other types of renal disease. Most cells which would be classified as "normal" renal tubular cells in these sediments are dead. In contrast, the findings suggest that the bubble cell represents an injured but viable renal tubular cell. The frequent finding of oval fat bodies in the same sediments suggests that the oval fat body is also produced by tubular cell injury.
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Burinskii, Alexander. "Source of the Kerr-Newman solution as a gravitating bag model: 50 years of the problem of the source of the Kerr solution". International Journal of Modern Physics A 31, nr 02n03 (20.01.2016): 1641002. http://dx.doi.org/10.1142/s0217751x16410025.
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It is known that gravitational and electromagnetic fields of an electron are described by the ultra-extreme Kerr-Newman (KN) black hole solution with extremely high spin/mass ratio. This solution is singular and has a topological defect, the Kerr singular ring, which may be regularized by introducing the solitonic source based on the Higgs mechanism of symmetry breaking. The source represents a domain wall bubble interpolating between the flat region inside the bubble and external KN solution. It was shown recently that the source represents a supersymmetric bag model, and its structure is unambiguously determined by Bogomolnyi equations. The Dirac equation is embedded inside the bag consistently with twistor structure of the Kerr geometry, and acquires the mass from the Yukawa coupling with Higgs field. The KN bag turns out to be flexible, and for parameters of an electron, it takes the form of very thin disk with a circular string placed along sharp boundary of the disk. Excitation of this string by a traveling wave creates a circulating singular pole, indicating that the bag-like source of KN solution unifies the dressed and point-like electron in a single bag-string-quark system.
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Toyota, Hiromichi, Ken Nagaoka, Xia Zhu, Yoshinari Kato, Shinfuku Nomura, Yukiharu Iwamoto, Hiroaki Yamamoto i Yu Shibano. "Synthesis of Single-Wall Carbon Nanotubes by In-Liquid CVD". Key Engineering Materials 749 (sierpień 2017): 217–22. http://dx.doi.org/10.4028/www.scientific.net/kem.749.217.
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High-speed synthesis of the carbon nanotubes in liquid is introduced. The conventional method for synthesizing carbon nanotubes is generally known as gas-phase chemical-vapor deposition (CVD). With that method, carbon nanotubes of high purity can be synthesized, but the synthesis rate is low. Even though the synthesized carbon nanotubes are excellent materials, they cannot be used in large quantities. Accordingly, in this study, single-wall carbon nanotubes (SWCNTs) are synthesized by “in-liquid” CVD. Since the molecular density of a liquid is much higher than that of a gas and the liquid has a cooling effect, performing CVD in a liquid can provide a high-speed growth rate of CNTs on substrate materials. A silicon substrate on which cobalt micro particles are deposited as the catalyst was used. Electrical-resistance heating was used for growing carbon nanotubes in pure ethanol. The synthesized nanotubes were analyzed by scanning electron microscope, transmission electron microscope, and Raman spectroscopy. The results of these analyses indicate that SWCNTs were successfully synthesized over a wide area of the substrate surface. By investigating the synthesized carbon nanotubes under varied experimental conditions (such as pressure and substrate surface roughness), it is shown that surface roughness of the substrate and the bubble behavior are related to the synthesis mechanism of the CNTs.
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Wisniewski, M., A. Sionkowska, H. Kaczmarek, J. Skopinska, S. Lazare i V. Tokarev. "The influence of KrF excimer laser irradiation on the surface of collagen and collagen/PVP films". International Journal of Photoenergy 2006 (2006): 1–7. http://dx.doi.org/10.1155/ijp/2006/35126.
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The surface properties of collagen and collagen/poly(vinyl pyrrolidone) (PVP) films after KrF excimer laser irradiation (λ=248nm) were investigated by means of the technique of scanning electron microscopy (SEM) and optical microscopy (OM). The laser irradiation of the used specimens caused an expansion of materials above their surface with pronounced sings of its melting. The height of the ablated volume in a case of collagen film at a fluence of1.1J/cm2was approximately 5μm. A white damage appears on the treated surfaces at a threshold of0.5J/cm2with a single pulse and becomes more visible for a higher fluence. It is also noteworthy that along with increasing fluences (beginning from the fluence of1.7J/cm2), the characteristic filaments at the spot edges are observed. The local heat and pressure generated by the laser radiation were able to induce bubble formation on the surface. Further bubble colliding and bursting produce a three-dimensional polymer “microfoam” structure with interconnected pores. These results can be of interest for some new applications.
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Kabakci, Gamze Cakir, Ozgur Aslan i Emin Bayraktar. "Toughening Mechanism Analysis of Recycled Rubber-Based Composites Reinforced with Glass Bubbles, Glass Fibers and Alumina Fibers". Polymers 13, nr 23 (1.12.2021): 4215. http://dx.doi.org/10.3390/polym13234215.
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Recycling of materials attracts considerable attention around the world due to environmental and economic concerns. Recycled rubber is one of the most commonly used recyclable materials in a number of industries, including automotive and aeronautic because of their low weight and cost efficiency. In this research, devulcanized recycled rubber-based composites are designed with glass bubble microsphere, short glass fiber, aluminum chip and fine gamma alumina fiber (γ-Al2O3) reinforcements. After the determination of the reinforcements with matrix, bending strength and fracture characteristics of the composite are investigated by three-point bending (3PB) tests. Halpin–Tsai homogenization model is adapted to the rubber-based composites to estimate the moduli of the composites. Furthermore, the relevant toughening mechanisms for the most suitable reinforcements are analyzed and stress intensity factor, KIc and critical energy release rate, GIc in mode I are determined by 3PB test with single edge notch specimens. In addition, 3PB tests are simulated by finite element analysis and the results are compared with the experimental results. Microstructural and fracture surfaces analysis are carried out by means of scanning electron microscopy (SEM). Mechanical test results show that the reinforcement with glass bubbles, aluminum oxide ceramic fibers and aluminum chips generally increase the fracture toughness of the composites.
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Zhang, Xiaoxi, Can Cao, Nan Gui, Xiaoli Huang, Xingtuan Yang, Jiyuan Tu, Shengyao Jiang i Qian Zhao. "A Particle-Scale Model of Surface Tension for Two-Phase Flow: Model Description and Validation". Energies 15, nr 19 (28.09.2022): 7132. http://dx.doi.org/10.3390/en15197132.
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A particle-scale surface tension force model (STF) is proposed here to be incorporated in the smoothed hydrodynamics particle (SPH) method. This model is based on the identification of interface geometry and the gradient of densities across the interface. A square bubble of single-phase and a square bubble immersed in fluids are simulated by the STF model accompanied with a combined kernel in SPH to validate their suitability to simulate the immersed bubble motion. Two cases of rising bubbles, i.e., a single rising bubble and a pair of rising bubbles, are simulated for demonstration. The rising velocity, density, surface tension force, interfacial curvature, the power of the STF, and the smoothing length of the rising bubble and surrounding fluids are all computed by the current STF model to study the characteristics of immersed bubble’s motion and coalescence. The current model provides a way to capture the interfacial interactions in two-phase flows at particle scales.
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Buckley, C. E., H. K. Birnbaum, J. S. Lin, S. Spooner, D. Bellmann, P. Staron, T. J. Udovic i E. Hollar. "Characterization of H defects in the aluminium–hydrogen system using small-angle scattering techniques". Journal of Applied Crystallography 34, nr 2 (1.04.2001): 119–29. http://dx.doi.org/10.1107/s0021889800018239.
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Aluminium foils (99.99% purity) and single crystals (99.999% purity) were charged with hydrogen using a gas plasma method and electrochemical methods, resulting in the introduction of a large amount of hydrogen. X-ray diffraction measurements indicated that within experimental error there was a zero change in lattice parameter after plasma charging. This result is contradictory to almost all other face-centred cubic (f.c.c.) materials, which exhibit a lattice expansion when the hydrogen enters the lattice interstitially. It is hypothesized that the hydrogen does not enter the lattice as an interstitial solute, but instead forms an H–vacancy complex at the surface that diffuses into the volume and then clusters to form H2bubbles. Small- and ultra-small-angle neutron scattering (SANS, USANS) and small-angle X-ray scattering (SAXS) were primarily employed to study the nature and agglomeration of the H–vacancy complexes in the Al–H system. The SAXS results were ambiguous owing to double Bragg scattering, but the SANS and USANS investigation, coupled with results from inelastic neutron scattering, and transmission and scanning electron microscopy, revealed the existence of a large size distribution of hydrogen bubbles on the surface and in the bulk of the Al–H system. The relative change in lattice parameter is calculated from the pressure in a bubble of average volume and is compared with the experimentally determined value.
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Lai, S. C. N., F. R. Tay, G. S. P. Cheung, Y. F. Mak, R. M. Carvalho, S. H. Y. Wei, M. Toledano, R. Osorio i D. H. Pashley. "Reversal of Compromised Bonding in Bleached Enamel". Journal of Dental Research 81, nr 7 (lipiec 2002): 477–81. http://dx.doi.org/10.1177/154405910208100709.
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Oxygen inhibits polymerization of resin-based materials. We hypothesized that compromised bonding to bleached enamel can be reversed with sodium ascorbate, an anti-oxidant. Sandblasted human enamel specimens were treated with distilled water (control) and 10% carbamide peroxide gel with or without further treatment with 10% sodium ascorbate. They were bonded with Single Bond (3M-ESPE) or Prime&Bond NT (Dentsply DeTrey) and restored with a composite. Specimens were prepared for microtensile bond testing and transmission electron microscopy after immersion in ammoniacal silver nitrate for nanoleakage evaluation. Bond strengths of both adhesives were reduced after bleaching but were reversed following sodium ascorbate treatment (P < 0.001). Resin-enamel interfaces in bleached enamel exhibited more extensive nanoleakage in the form of isolated silver grains and bubble-like silver deposits. Reduction of resin-enamel bond strength in bleached etched enamel is likely to be caused by a delayed release of oxygen that affects the polymerization of resin components.
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Yu, Qidong, Zhicheng Xu, Jing Zhao, Mindi Zhang i Xiaojian Ma. "PIV-Based Acoustic Pressure Measurements of a Single Bubble near the Elastic Boundary". Micromachines 11, nr 7 (29.06.2020): 637. http://dx.doi.org/10.3390/mi11070637.
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The objective of this paper was to investigate acoustic pressure waves and the transient flow structure emitted from the single bubble near an elastic boundary based on the particle image velocimetry (PIV). A combination of an electric-spark bubble generator and PIV were used to measure the temporal bubble shapes, transient flow structure, as well as the mid-span deflection of an elastic boundary. Results are presented for three different initial positions near an elastic boundary, which were compared with results obtained using a rigid boundary. A formula relating velocity and pressure was proposed to calculate the acoustic pressure contours surrounding a bubble based on the velocity field of the transient flow structure obtained using PIV. The results show the bubbles near the elastic boundary presented a “mushroom” bubble and an inverted cone bubble. Based on the PIV-measured acoustic pressure contours, a significant pressure difference is found between the elastic boundary and the underside of the bubble, which contributed to the formation of the “mushroom” bubble and inverted cone bubble. Furthermore, the bubbles had opposite migration direction near rigid and elastic boundaries, respectively. In detail, the bubble was repelled away from the elastic boundary and the bubble was attracted by the rigid boundary. The resultant force made up of a Bjerknes force and buoyancy force dominated the migration direction of the bubble.
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Peng, YuXiang, i Wayne A. Scales. "Satellite Formation Flight Simulation Using Multi-Constellation GNSS and Applications to Ionospheric Remote Sensing". Remote Sensing 11, nr 23 (30.11.2019): 2851. http://dx.doi.org/10.3390/rs11232851.
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The Virginia Tech Formation Flying Testbed (VTFFTB) is a global navigation satellite system (GNSS)-based hardware-in-the-loop (HIL) simulation testbed for spacecraft formation flying with ionospheric remote sensing applications. Past applications considered only the Global Positioning System (GPS) constellation. The rapid GNSS modernization offers more signals from other constellations, including the growing European system—Galileo. This study presents an upgrade of VTFFTB with the incorporation of Galileo and the associated enhanced capabilities. By simulating an ionospheric plasma bubble scenario with a pair of LEO satellites flying in formation, the GPS-based simulations are compared to multi-constellation GNSS simulations including the Galileo constellation. A comparison between multi-constellation (GPS and Galileo) and single-constellation (GPS) shows the absolute mean and standard deviation of vertical electron density measurement errors for a specific Equatorial Spread F (ESF) scenario are decreased by 32.83% and 46.12% with the additional Galileo constellation using the 13 July 2018 almanac. Another comparison based on a simulation using the 8 March 2019 almanac shows the mean and standard deviation of vertical electron density measurement errors were decreased further to 43.34% and 49.92% by combining both GPS and Galileo data. A sensitivity study shows that the Galileo electron density measurements are correlated with the vertical separation of the formation configuration. Lower C/N 0 level increases the measurement errors and scattering level of vertical electron density retrieval. Relative state estimation errors are decreased, as well by utilizing GPS L1 plus Galileo E1 carrier phase instead of GPS L1 only. Overall, superior performance on both remote sensing and relative navigation applications is observed by adding Galileo to the VTFFTB.
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Wei, Fang, Liu Ling i Xu Lan. "Preparation and Characterization of CuO/ZnO/PVDF/PAN Nanofiber Composites by Bubble-electrospinning". Recent Patents on Nanotechnology 13, nr 3 (28.01.2020): 196–201. http://dx.doi.org/10.2174/1872210513666191007113524.
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Background: Nanocomposites loaded with metal oxides, such as CuO and ZnO, have excellent optical, electrical, mechanical and chemical properties, which result in their great potential applications in optoelectronic devices, sensors, photocatalysts and other fields. Especially, electrospun metal- oxide-loaded nanofibers have attracted much attention in many fields. However, the single-needle Electrospinning (ES) inhibits the industrial application of these electrospun nanofiber composites. Bubble-Electrospinning (BE) is an effective free surface ES for mass production of nanofiber membranes loaded with metal oxide. Few relevant patents to the topic have been reviewed and introduced. Methods: The BE was used to prepare mass production of Cu(Ac)2 /Zn(Ac)2/ PVDF/ PAN Composite Nanofiber Membranes (CNFMs). Then PVDF/PAN CNFMs containing CuO and ZnO nanocrystals were obtained by heat-treatment. Finally, CuO nanosheets and ZnO nanorods were successfully grown on the surface of PVDF/PAN CNFMs using hydrothermal method. In addition, the morphology and crystal structure of CNFMs were investigated by scanning electron microscopy (SEM) and X-Ray Powder Diffractometer (XRD). Results: The morphology and crystal structure of the samples were characterized by SEM and XRD. The results showed the heat treatment temperature of 150oC and the hydrothermal temperature of 150oC were the optimal process parameters for the fabrication of PVDF/PAN CNFMs loaded with CuO and ZnO nanocrystals, and a higher heat treatment temperature results in higher crystallinity of ZnO and CuO. Conclusion: CuO/ZnO/PVDF/PAN CNFMs were successfully prepared by a combination of BE, heattreatment and hydrothermal method. The ZnO/CuO beads obtained by heat treatment is the key point of growing ZnO/CuO nanocrystals, and the growth temperature has great effect on the morphology of ZnO/CuO nanocrystals.
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Wu, Hao, Tianshu Zhang, Xiaochen Lai, Haixia Yu, Dachao Li, Hao Zheng, Hui Chen, Claus-Dieter Ohl i Yuanyuan Li. "Influence of Surface Tension on Dynamic Characteristics of Single Bubble in Free-Field Exposed to Ultrasound". Micromachines 13, nr 5 (17.05.2022): 782. http://dx.doi.org/10.3390/mi13050782.
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The motion of bubbles in an ultrasonic field is a fundamental physical mechanism in most applications of acoustic cavitation. In these applications, surface-active solutes, which could lower the surface tension of the liquid, are always utilized to improve efficiency by reducing the cavitation threshold. This paper examines the influence of liquids’ surface tension on single micro-bubbles motion in an ultrasonic field. A novel experimental system based on high-speed photography has been designed to investigate the temporary evolution of a single bubble in the free-field exposed to a 20.43 kHz ultrasound in liquids with different surface tensions. In addition, the R-P equations in the liquid with different surface tension are solved. It is found that the influences of the surface tension on the bubble dynamics are obvious, which reflect on the changes in the maximum size and speed of the bubble margin during bubble oscillating, as well as the weaker stability of the bubble in the liquid with low surface tension, especially for the oscillating bubble with higher speed. These effects of the surface tension on the bubble dynamics can explain the mechanism of surfactants for promoting acoustic cavitation in numerous application fields.
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Wang, Ronghang, Bingxin Liu, Jiahao Gong, Jinlu Zhang, Meng Gao, Lunjia Zhang, Xuelin Wang, Sen Chen, Jie Hong i Lin Gui. "Development of a bubble-based single cell picking system". Journal of Micromechanics and Microengineering 32, nr 3 (14.02.2022): 035006. http://dx.doi.org/10.1088/1361-6439/ac4c96.
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Abstract In this work, we proposed a novel method to ‘pick’ single cell from a cluster of cells using bubbles as ‘fingers’. Particularly, the bubble was generated in the cell suspension solution via the pores in a porous membrane sandwiched between the solution channel and the gas channel. Controlling the pressure of the gas and the cell suspension could produce a bubble with certain size in the solution channel, and the bubble could capture a cell in its surface due to the interfacial tension between the cell suspension solution and the bubble, and then transfer the cell away. A simplified mechanical model was built to interpret the mechanism of the cell control. This method can be easily applied on multiple fields, including the single cell analysis, drug screening, cells sorting, and tumor biology, since it could separate a single cell from the cell cluster efficiently.
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Afridi, Jing i Younas. "Biogas Production and Fundamental Mass Transfer Mechanism in Anaerobic Granular Sludge". Sustainability 11, nr 16 (16.08.2019): 4443. http://dx.doi.org/10.3390/su11164443.
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Anaerobic granules are responsible for organic degradation and biogas production in a reactor. The biogas production is entirely dependent on a mass transfer mechanism, but so far, the fundamental understanding remains poor due to the covered surface of the reactor. The study aimed at investigating the fundamental mass transfer characteristics of single anaerobic granules of different sizes using microscopic imaging and analytical monitoring under single and different organic loadings. The experiment was conducted in a micro reactor and mass transfer was calculated using modified Fick’s law. Scanning electron microscopy was applied to observe biogas production zones in the granule, and a lab-scale microscope equipped with a camera revealed the biogas bubble detachment process in the micro reactor for the first time. In this experiment, the granule size was 1.32, 1.47, and 1.75 mm, but 1.75 mm granules were chosen for further investigation due to their large size. The results revealed that biogas production rates for 1.75 mm granules at initial Chemical Oxygen Demand (COD) 586, 1700, and 6700 mg/L were 0.0108, 0.0236, and 0.1007 m3/kg COD, respectively; whereas the mass transfer rates were calculated as 1.83 × 10−12, 5.30 × 10−12, and 2.08 × 10−11 mg/s. It was concluded that higher organic loading and large granules enhance the mass transfer inside the reactor. Thus, large granules should be preferred in the granule-based reactor to enhance biogas production.
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Lemaire, Cédric, Yann Quilichini, Nicole Brunel-Michac, Jérémie Santini, Liliane Berti, Julien Cartailler, Pierre Conchon, Éric Badel i Stéphane Herbette. "Plasticity of the xylem vulnerability to embolism in Populus tremula x alba relies on pit quantity properties rather than on pit structure". Tree Physiology 41, nr 8 (8.02.2021): 1384–99. http://dx.doi.org/10.1093/treephys/tpab018.
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Abstract Knowledge on variations of drought resistance traits are needed to predict the potential of trees to acclimate to coming severe drought events. Xylem vulnerability to embolism is a key parameter related to such droughts, and its phenotypic variability relies mainly on environmental plasticity. We investigated the structural determinants controlling the plasticity of vulnerability to embolism, focusing on the key elements involved in the air bubble entry in vessels, especially the intervessel pits. Poplar saplings (Populus tremula x alba (Aiton) Sm., 1804) grown in contrasted water availability or light exposure exhibited differences in the vulnerability to embolism (P50) in a range of 0.76 MPa. We then characterized the structural changes in features related to pit quantity and pit structure, from the pit ultrastructure to the organization of xylem vessels, using different microscopy techniques (transmission electron microscopy, scanning electron microscopy, light microscopy). A multispectral combination of X-ray microtomography and light microscopy analysis allowed measuring the vulnerability of each single vessel and testing some of the relationships between structural traits and vulnerability to embolism inside the xylem. The pit ultrastructure did not change, whereas the vessel dimensions increased with the vulnerability to embolism and the grouping index and fraction of intervessel cell wall both decreased with the vulnerability to embolism. These findings hold when comparing between trees or between the vessels inside the xylem of an individual tree. These results evidenced that plasticity of vulnerability to embolism in hybrid poplar occurs through changes in the pit quantity properties such as pit area and vessel grouping rather than changes on the pit structure.
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Panton, Ronald L., Jong W. Lee, Lakhi Goenka i Achyuta Achari. "Simulation of Void Growth in Molten Solder Bumps". Journal of Electronic Packaging 125, nr 3 (1.09.2003): 329–34. http://dx.doi.org/10.1115/1.1569954.
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This research studies the motion of void bubbles within molten solder bumps. Surface tension variation on the outer surface of the bump drives a flow that is transmitted to the interior by viscosity. Bubbles inside the bump grow by collisions with other bubbles. A computer model of this process has been formulated. In cases with the melting process from top to bottom, a ring of bubbles collected at the top outer rim of the solder bump. When the melting direction was reversed, the typical result was a single large bubble near the center with a few smaller recirculating bubbles.
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Liu, Yaxin, Eric R. Upchurch i Evren M. Ozbayoglu. "Experimental Study of Single Taylor Bubble Rising in Stagnant and Downward Flowing Non-Newtonian Fluids in Inclined Pipes". Energies 14, nr 3 (23.01.2021): 578. http://dx.doi.org/10.3390/en14030578.
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An experimental investigation of single Taylor bubbles rising in stagnant and downward flowing non-Newtonian fluids was carried out in an 80 ft long inclined pipe (4°, 15°, 30°, 45° from vertical) of 6 in. inner diameter. Water and four concentrations of bentonite–water mixtures were applied as the liquid phase, with Reynolds numbers in the range 118 < Re < 105,227 in countercurrent flow conditions. The velocity and length of Taylor bubbles were determined by differential pressure measurements. The experimental results indicate that for all fluids tested, the bubble velocity increases as the inclination angle increases, and decreases as liquid viscosity increases. The length of Taylor bubbles decreases as the downward flow liquid velocity and viscosity increase. The bubble velocity was found to be independent of the bubble length. A new drift velocity correlation that incorporates inclination angle and apparent viscosity was developed, which is applicable for non-Newtonian fluids with the Eötvös numbers (E0) ranging from 3212 to 3405 and apparent viscosity (μapp) ranging from 0.001 Pa∙s to 129 Pa∙s. The proposed correlation exhibits good performance for predicting drift velocity from both the present study (mean absolute relative difference is 0.0702) and a database of previous investigator’s results (mean absolute relative difference is 0.09614).
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Frolov, Sergey M., Konstantin A. Avdeev, Viktor S. Aksenov, Illias A. Sadykov, Igor O. Shamshin i Fedor S. Frolov. "Interaction of Shock Waves with Water Saturated by Nonreacting or Reacting Gas Bubbles". Micromachines 13, nr 9 (19.09.2022): 1553. http://dx.doi.org/10.3390/mi13091553.
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A compressible medium represented by pure water saturated by small nonreactive or reactive gas bubbles can be used for generating a propulsive force in large-, medium-, and small-scale thrusters referred to as a pulsed detonation hydroramjet (PDH), which is a novel device for underwater propulsion. The PDH thrust is produced due to the acceleration of bubbly water (BW) in a water guide by periodic shock waves (SWs) and product gas jets generated by pulsed detonations of a fuel–oxidizer mixture. Theoretically, the PDH thrust is proportional to the operation frequency, which depends on both the SW velocity in BW and pulsed detonation frequency. The studies reported in this manuscript were aimed at exploring two possible directions of the improvement of thruster performances, namely, (1) the replacement of chemically nonreacting gas bubbles by chemically reactive ones, and (2) the increase in the pulsed detonation frequency from tens of hertz to some kilohertz. To better understand the SW-to-BW momentum transfer, the interaction of a single SW and a high-frequency (≈7 kHz) sequence of three SWs with chemically inert or active BW containing bubbles of air or stoichiometric acetylene–oxygen mixture was studied experimentally. Single SWs and SW packages were generated by burning or detonating a gaseous stoichiometric acetylene–oxygen or propane–oxygen mixture and transmitting the arising SWs to BW. The initial volume fraction of gas in BW was varied from 2% to 16% with gas bubbles 1.5–4 mm in diameter. The propagation velocity of SWs in BW ranged from 40 to 580 m/s. In experiments with single SWs in chemically active BW, a detonation-like mode of reaction front propagation (“bubbly quasidetonation”) was realized. This mode consisted of a SW followed by the front of bubble explosions and was characterized by a considerably higher propagation velocity as compared to the chemically inert BW. The latter could allow increasing the PDH operation frequency and thrust. Experiments with high-frequency SW packages showed that on the one hand, the individual SWs quickly merged, feeding each other and increasing the BW velocity, but on the other hand, the initial gas content for each successive SW decreased and, accordingly, the SW-to-BW momentum transfer worsened. Estimates showed that for a small-scale water guide 0.5 m long, the optimal pulsed detonation frequency was about 50–60 Hz.
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Bello, Valentina, Elisabetta Bodo i Sabina Merlo. "Optical Multi-Parameter Measuring System for Fluid and Air Bubble Recognition". Sensors 23, nr 15 (26.07.2023): 6684. http://dx.doi.org/10.3390/s23156684.
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Detection of air bubbles in fluidic channels plays a fundamental role in all that medical equipment where liquids flow inside patients’ blood vessels or bodies. In this work, we propose a multi-parameter sensing system for simultaneous recognition of the fluid, on the basis of its refractive index and of the air bubble transit. The selected optofluidic platform has been designed and studied to be integrated into automatic pumps for the administration of commercial liquid. The sensor includes a laser beam that crosses twice a plastic cuvette, provided with a back mirror, and a position-sensitive detector. The identification of fluids is carried out by measuring the displacement of the output beam on the detector active surface and the detection of single air bubbles can be performed with the same instrumental scheme, exploiting a specific signal analysis. When a bubble, traveling along the cuvette, crosses the readout light beam, radiation is strongly scattered and a characteristic fingerprint shape of the photo-detected signals versus time is clearly observed. Experimental testing proves that air bubbles can be successfully detected and counted. Their traveling speed can be estimated while simultaneously monitoring the refractive index of the fluid.
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Xu, Zhicheng, Xiaojian Ma, Qidong Yu, Jing Zhao, Dapeng Wang, Xiaosheng Bi i Fen Qin. "Experimental Investigation of Bubble Migration near Anisotropic Beams". Micromachines 12, nr 12 (6.12.2021): 1518. http://dx.doi.org/10.3390/mi12121518.
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In order to resist bubble loading, anisotropic composite materials are the development direction of the future. The objective of this paper was to experimentally investigate the hydrodynamic performance of anisotropic laminate composite plates, with a focus on the effect of its anisotropic characteristics on single bubble migration. In these experiments, the bubble was generated in a transparent water tank filled with sufficiently degassed water by Joule heating at the connecting point of the electrodes through the discharge of a 6600 μF charge to 800 V, and a high-speed camera system with a recording speed of 40,000 frames per second was used to record the temporal evolution of bubble patterns and the dynamic responses of the laminated composite plates. The results are presented for two anisotropic cantilever composite beams with different ply angles, namely, 0° and 30°. Several variables, such as the shapes of the bubble, the curved trail of motion of the bubble center, bubble collapse time, and bubble initial standoff distances were extracted from the photographic images. The results showed that bubble migration near the 30° plate presents a curved bubble trail with an evident tilted angle during the collapse and rebound stages, which is very different from bubbles that all move vertically above the 0° plate. Furthermore, a characterization method for bubble migration was proposed to quantitatively describe the curved bubble trails and the deformation of the composite beams in temporal and spatial scales. This method shows that the curved bubble trails near the 30° plate are closely related to the dynamic response of composite beams, with a focus on the bending-twisting coupling effect.
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Han, Zhaofeng, Cyril Mauger, Thibaut Chaise, Thomas Elguedj, Michel Arrigoni, Mahmoud El Hajem i Nicolas Boisson. "Experimental and Analytical Study of under Water Pressure Wave Induced by the Implosion of a Bubble Generated by Focused Laser". Sensors 21, nr 14 (14.07.2021): 4800. http://dx.doi.org/10.3390/s21144800.
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In various domains of material processing, such as surface cleaning and surface treatment, cavitation phenomenon may become an alternative to traditional methods if this phenomenon is well understood. Due to experimental and mathematical difficulties in theoretical models, it is still a challenge to accurately measure the physical mechanism of the fluid/structure interactions. In this study, we verified the feasibility of using polyvinylidene fluoride (PVDF) sensors to quantitatively measure the under-water pressure wave generated by the collapse of a single cavitation bubble. The electrical signal obtained by PVDF can be converted into pressure information only by using the sensor material parameters provided by the supplier. During the conversion process, only the capacitance of the acquisition chain needs to be additionally measured. At the same time, a high-speed video recording system was used to visualize the evolution of the cavitation bubble. The Gilmore analytical model and an associated wave propagation model were used to simulate the pressure peak of the first collapse of the cavitation bubble. This theoretical pressure was compared with the experimental results. The result showed that, for bubbles with a normalized standoff distance γ larger than 5, the PVDF sensor had the ability to quantitatively measure the pressure wave generated by a single cavitation bubble.
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Al-Saud, LMS, i HNA Al-Nahedh. "Occluding Effect of Nd:YAG Laser and Different Dentin Desensitizing Agents on Human Dentinal Tubules In Vitro: A Scanning Electron Microscopy Investigation". Operative Dentistry 37, nr 4 (1.07.2012): 340–55. http://dx.doi.org/10.2341/10-188-l.
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SUMMARY Objectives This in vitro study aimed to microscopically evaluate and compare the occluding effect of the Nd:YAG laser and different dentin desensitizing agents on human dentinal tubules. Materials and Methods The Nd:YAG laser (SunLase™ 800) and four commercially available and professionally applied dentin desensitizers (Gluma® desensitizer, Tenure Quick®, Quell™ desensitizer, and VivaSens®) were investigated in this study. Sixty-four extracted intact human molars were used. Each dentin surface was divided by shallow indentation into two halves, one of which was used for treatment and the other of which served as a control. The dentin surfaces were etched to remove any smear plugs and to mimic the open dentinal tubules of sensitive dentin using 0.5 M ethylenediaminetetraacetic acid (pH 7.4) for two minutes (applied with a microbrush) and then rinsed with an air-water syringe for 30 seconds. The laser samples (n=16) were randomly divided into four groups of four samples each. These groups were the step-up technique group, the 14-day group, the one-minute group, and the two-minute group. Forty-eight samples were treated with the four tested desensitizing agents and were randomly divided into four groups (n=12/group). Each group was further subdivided into three subgroups (n=4). Samples of the first subgroup were treated for 14 days, while those of the second subgroup were treated once. Samples of the last subgroup were fractured longitudinally after a single treatment. All of the samples were then examined under a scanning electron microscope. Results The Nd:YAG laser–irradiated dentin showed reduction or complete obliteration of the dentinal tubule lumen; thus, the treatment modified the original dentinal structure. The lased dentin surface in the two-minute group showed bubble-like changes in the area of the dentinal tubules' orifices. Statistically, the two-minute group was found to have a significantly higher percentage of partially or fully occluded tubules than did the one-minute group. All of the studied desensitizing agents produced occlusion of the dentinal tubules; however, the appearance of the precipitates, the level of coverage, and the degree of dentinal occlusion varied among the tested products. Conclusion Throughout the specified period of this study, occlusion and/or narrowing of the open dentinal tubules have been successfully achieved with both treatment approaches.
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Marks, Roman. "Bubble mediated polymerization of RNA and DNA". AIMS Biophysics 9, nr 2 (2022): 96–107. http://dx.doi.org/10.3934/biophy.2022009.
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<abstract> <p>Research dedicated to trace rotational motion of bubbles in saline water revealed that these may generate either single cationic or cationic/anionic motions, including spliced double helix flow. In all cases, the aggregated ionic flows propagate in spiraling as well as rotational manner. However, if bi-ionic or double helix motion is generated, the flow is oppositely directed and has opposite electric charges. Next, the assembled flow is forced to pirouette within the bubble vortex. During that processing the narrowing of spiraling flow takes place and result in increase of revolutions to even millions per second. As a result, a significant friction is induced between revolving ionic hydrates allowing continuous detachment of electrons from covalent atomic shells of electropositive elements. Then, free electrons may be attracted by electronegative elements that are dissolved in seawater. Afterwards, that negatively charged elements may undergo electrical condensation around cationic centers of revolutions. That explain a unique mechanism which operates when negatively charged phosphate compounds and pentagonal blocks found in RNA and DNA as ribose as well as pentagonal rings in nitrogenous bases A and G are being winded. The compensative anionic flow and revolutions may conduct winding of hexagonal blocks found in nitrogenous bases A, G and C, T or U. These assume to gather more positive charge needed to bridge negatively charged sugar molecules in nucleic acids. Thus, the continuity in generation of electronegative compounds and spiral manner of arranging them within the sub-bubble vortices should be regarded as a mechanism responsible for precise, rotational-electric polymerization of elongated macromolecules of RNA/DNA architecture. Reported research refers mainly to physical processes activated by rising bubbles thus should be confronted with other experimental methods used in genetics, microbiology and chemistry.</p> </abstract>
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Wongsaroj, Wongsakorn, Hideharu Takahashi, Natee Thong-Un i Hiroshige Kikura. "Ultrasonic Measurement for the Experimental Investigation of Velocity Distribution in Vapor-Liquid Boiling Bubbly Flow". International Journal of Engineering and Technology Innovation 12, nr 1 (7.12.2021): 16–28. http://dx.doi.org/10.46604/ijeti.2021.8329.
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This study proposes an ultrasonic velocity profiler (UVP) with a single ultrasonic gas-liquid two-phase separation (SUTS) technique to measure the velocity distribution of vapor-liquid boiling bubbly flow. The proposed technique is capable of measuring the velocity of the vapor bubble and liquid separately in boiling conditions. To confirm the viability of the measurement technique, the experiment is conducted on vertical pipe flow apparatus. The ultrasonic transmission and effect of ultrasonic refraction through the pipe wall and water are investigated at ambient temperature until subcooled boiling temperature is reached. The velocity profile in the water at elevated temperature is measured to verify the ability of the technique in this application. The bubbly flow velocity distribution measurement in boiling conditions is then demonstrated. The results show that the proposed technique can effectively investigate the velocity of both phases under various fluid conditions in boiling bubbly flow.
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Balakrishnan, Kaushik, i Suresh Menon. "A multiphase buoyancy-drag model for the study of Rayleigh-Taylor and Richtmyer-Meshkov instabilities in dusty gases". Laser and Particle Beams 29, nr 2 (22.03.2011): 201–17. http://dx.doi.org/10.1017/s0263034611000176.
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AbstractA new multiphase buoyancy-drag model is developed for the study of Rayleigh-Taylor and Richtmyer-Meshkov instabilities in dusty gases, extending on a counterpart single-phase model developed in the past by Srebro et al. (2003). This model is applied to single- and multi-mode perturbations in dusty gases and both Rayleigh-Taylor and Richtmyer-Meshkov instabilities are investigated. The amplitude for Rayleigh-Taylor growth is observed to be contained within a band, which lies within limits identified by a multiphase Atwood number that is a function of the fluid densities, particle size, and a Stokes number. The amplitude growth is subdued with (1) an increase in particle size for a fixed particle number density and with (2) an increase in particle number density for a fixed particle size. The power law index for Richtmyer-Meshkov growth under multi-mode conditions also shows dependence to the multiphase Atwood number, with the index for the bubble front linearly decreasing and then remaining constant, and increasing non-linearly for the spike front. Four new classes of problems are identified and are investigated for Rayleigh-Taylor growth under multi-mode conditions for a hybrid version of the model: (1) bubbles in a pure gas rising into a region of particles; (2) spikes in a pure gas falling into a region of particles; (3) bubbles in a region of particles rising into a pure gas; and (4) spikes in a region of particles falling into a pure gas. Whereas the bubbles accelerate for class (1) and the spikes for class (4), for classes (2) and (3), the spikes and bubbles, respectively, oscillate in a gravity wave-like phenomenon due to the buoyancy term changing sign alternatively. The spike or bubble front, as the case may be, penetrates different amounts into the dusty or pure gas for every subsequent penetration, due to drag effects. Finally, some extensions to the presently developed multiphase buoyancy-drag model are proposed for future research.
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Zhu, Junwen, Qiqian Zhang, Fei Liang, Yongxiang Feng i Wenhui Wang. "High-throughput acoustofluidic microchannels for single cell rotation". Journal of Micromechanics and Microengineering 31, nr 12 (15.11.2021): 124004. http://dx.doi.org/10.1088/1361-6439/ac349e.
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Abstract There is a growing desire for cell rotation in the field of biophysics, bioengineering and biomedicine. We herein present novel microfluidic channels for simultaneous high-throughput cell self-rotation using local circular streaming generated by ultrasonic wave excited bubble arrays. The bubble traps achieve high homogeneity of liquid–gas interface by setting capillary valves at the entrances of dead-end bubble trappers orthogonal to the main microchannel. In such a highly uniform bubble array, rotation at different fields of bubble-relevant vortices is considered equal and interconvertible. The device is compatible with cells of various size and retains manageable rotation velocity when actuated by signals of varying frequency and voltage. Experimental observations were confirmed consistent with theoretical estimation and numerical simulation. Comparing with conventional approaches (e.g. mechanical contact based, dielectrophoresis, optical tweezers) of cell rotation, our device has multiple merits such as high throughput, low cost and simple fabrication procedure, and high compatibility for lab-on-chip integration. Therefore, the platform holds a promise in cell observation, medicine development and biological detection.
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Thoharudin, Thoharudin, Sunardi Sunardi, Fitroh Anugrah Kusuma Yudha, Muhammad Nadjib i Arif Setyo Nugroho. "Design and Analysis of Venturi Microbubble Generator Using Computational Fluid Dynamics". Eksergi 19, nr 2 (31.05.2023): 49. http://dx.doi.org/10.32497/eksergi.v19i2.4305.
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The necessity for dissolved oxygen in water is crucial for the survival and growth of aquatic organisms, particularly tilapia. Seventy-five percent of tilapia will die if there is insufficient dissolved oxygen in the water. This work seeks to develop a venturi bubble-generating technique to combat the scarcity of dissolved oxygen in the water. A floating pump with a capacity of 12 m<sup>3</sup>/hour was selected as the medium for distributing water and generating vacuum pressure to draw in air for mixing with the water flow in the venturi. Ansys Fluent was used to model piping and venturi systems. The piping system was modeled with a single-phase (water) flow at a steady state, whereas the flow in the venturi was modeled with a multiphase (air and water) flow under transient situations. The simulation findings revealed that the pressure drop at the 90-degree elbow was much greater (27.17 kPa) than that at the 45-degree elbow (16.53 kPa). A 1-inch input diameter venturi produced bubbles with an average diameter of 105 µm, whereas a ½ inch venturi bubble generator produced bubbles with an average diameter of 83 µm. Owing to the numerous advantages of adopting a six-outlet piping system with a ½ inch venturi, this design is recommended for floating pumps with a capacity of 12 m<sup>3</sup>/h.
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Silvera, I. F., J. Blanchfield i J. Tempere. "Stability of multielectron bubbles against single-electron split-off". physica status solidi (b) 237, nr 1 (maj 2003): 274–79. http://dx.doi.org/10.1002/pssb.200301792.
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KARTOON, D., D. ORON, L. ARAZI i D. SHVARTS. "Three-dimensional multimode Rayleigh–Taylor and Richtmyer–Meshkov instabilities at all density ratios". Laser and Particle Beams 21, nr 3 (lipiec 2003): 327–34. http://dx.doi.org/10.1017/s0263034603213069.
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The three-dimensional (3D) turbulent mixing zone (TMZ) evolution under Rayleigh–Taylor and Richtmyer–Meshkov conditions was studied using two approaches. First, an extensive numerical study was made, investigating the growth of a random 3D perturbation in a wide range of density ratios. Following that, a new 3D statistical model was developed, similar to the previously developed two-dimensional (2D) statistical model, assuming binary interactions between bubbles that are growing at a 3D asymptotic velocity. Confirmation of the theoretical model was gained by detailed comparison of the bubble size distribution to the numerical simulations, enabled by a new analysis scheme that was applied to the 3D simulations. In addition, the results for the growth rate of the 3D bubble front obtained from the theoretical model show very good agreement with both the experimental and the 3D simulation results. A simple 3D drag–buoyancy model is also presented and compared with the results of the simulations and the experiments with good agreement. Its extension to the spike-front evolution, made by assuming the spikes' motion is governed by the single-mode evolution determined by the dominant bubbles, is in good agreement with the experiments and the 3D simulations. The good agreement between the 3D theoretical models, the 3D numerical simulations, and the experimental results, together with the clear differences between the 2D and the 3D results, suggest that the discrepancies between the experiments and the previously developed models are due to geometrical effects.
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Tien, Tsung-Mo, Ching-Jer Huang, Chien-Hsun Lee i Kuan-Wen Liu. "Fiber-Optic Probe Array for Measuring Spatial Distributions of Air Volume Fractions in Bubbly Flows". Sensors 23, nr 3 (20.01.2023): 1222. http://dx.doi.org/10.3390/s23031222.
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In this study, we developed a fiber-optic sensing system with an eight-probe array for measuring the spatial distributions of air volume (void) fractions in bubbly flows. Initially, we performed calibration experiments in a cylindrical tank by using a fiber-optic sensing system with a single probe to determine the relationship between the time fraction ratio of bubble signals and void fractions. A high correlation coefficient was obtained between the time fraction ratio and the void fraction, suggesting that the proposed fiber-optic sensing system can measure local void fractions of up to 18%. Subsequently, we used the proposed fiber-optic sensing system with the eight-probe array to measure the spatial distribution of air volume fractions in a bubbly flow caused by breaking waves near a submerged breakwater. The effects of different variables, including the incident wave height, period, and width of the breakwater, on the spatial distribution of the void fraction on the lee side of the breakwater were systematically studied. The results demonstrated that the proposed fiber-optic sensing system can be used to determine the spatial distribution of air volume fractions in bubbly flows.
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PELESZ, Adam. "Charging of a single soap bubble". PRZEGLĄD ELEKTROTECHNICZNY 1, nr 10 (5.10.2018): 178–81. http://dx.doi.org/10.15199/48.2018.10.40.
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Ying, Chongfu, Yu An i Chongguo Xie. "Bremsstrahlung in single bubble sonoluminescence". Journal of Physics D: Applied Physics 38, nr 14 (1.07.2005): 2489–96. http://dx.doi.org/10.1088/0022-3727/38/14/029.
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Osuna, Isaac Aaron Rodriguez, Pablo Cobelli i Nahuel Olaiz. "Bubble Formation in Pulsed Electric Field Technology May Pose Limitations". Micromachines 13, nr 8 (31.07.2022): 1234. http://dx.doi.org/10.3390/mi13081234.
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Currently, increasing amounts of pulsed electric fields (PEF) are employed to improve a person’s life quality. This technology is based on the application of the shortest high voltage electrical pulse, which generates an increment over the cell membrane permeability. When applying these pulses, an unwanted effect is electrolysis, which could alter the treatment. This work focused on the study of the local variations of the electric field and current density around the bubbles formed by the electrolysis of water by PEF technology and how these variations alter the electroporation protocol. The assays, in the present work, were carried out at 2 KV/cm, 1.2 KV/cm and 0.6 KV/cm in water, adjusting the conductivity with NaCl at 2365 μs/cm with a single pulse of 800 μs. The measurements of the bubble diameter variations due to electrolysis as a function of time allowed us to develop an experimental model of the behavior of the bubble diameter vs. time, which was used for simulation purposes. In the in silico model, we calculated that the electric field and observed an increment of current density around the bubble can be up to four times the base value due to the edge effect around it, while the thermal effects were undesirable due to the short duration of the pulses (variations of ±0.1 °C are undesirable ). This research revealed that the rise of electric current is not just because of the shift in electrical conductivity due to chemical and thermal effects, but also varies with the bubble coverage over the electrode surface and variations in the local electric field by edge effect. All these variations can conduce to unwanted limitations over PEF treatment. In the future, we recommend tests on the variation of local current conductivity and electric fields.
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M., Adama Maiga. "Particle model of single bubble sonoluminescence". International Journal of Physical Sciences 11, nr 19 (16.10.2016): 252–61. http://dx.doi.org/10.5897/ijps2016.4535.
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Dehane, Aissa, i Slimane Merouani. "Microscopic Analysis of Hydrogen Production from Methane Sono-Pyrolysis". Energies 16, nr 1 (30.12.2022): 443. http://dx.doi.org/10.3390/en16010443.
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The sonolysis of certain substrates in water has proved its effectiveness for the enhancement of the sonochemical production of hydrogen. In this study, the sonolysis of methane has been investigated for the first time in a single acoustic bubble (microreactor) over a frequency from 140 to 515 kHz. The obtained findings have been compared to those available in the literature. Independently of the methane dose (inside the bubble), the yield of H2 was improved especially with the decrease in wave frequency (from 515 to 140 kHz). For the driving frequencies 140, 213, 355, and 515 kHz, the production of hydrogen was maximized at 20, 15, 10, and 10% CH4, respectively. For 213 kHz, and the presence of 10% methane, the yield of hydrogen goes up by 111 fold compared to the case where the gas atmosphere is saturated only by argon. On the other hand, the highest methane conversions (~100% for 2, 5 and 7% CH4) were retrieved at 140 and 213 kHz. In terms of hydrogen formation and methane decay, the use of 140 kHz was found to be the best choice, whereas for a multi-bubble system, the number of acoustic bubbles should be taken into account for an optimal choice of frequency. Interestingly, it was observed that at 140 and 213 kHz and for methane mole fractions lower than or equal to 30 and 10%, respectively, a maximal formation of H2 and a relatively important production of •OH could result simultaneously.
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Wang, Hanxiong, Liping Liu i Dong Liu. "Equilibrium shapes of a heterogeneous bubble in an electric field: a variational formulation and numerical verifications". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 473, nr 2199 (marzec 2017): 20160494. http://dx.doi.org/10.1098/rspa.2016.0494.
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The equilibrium shape of a bubble/droplet in an electric field is important for electrowetting over dielectrics (EWOD), electrohydrodynamic (EHD) enhancement for heat transfer and electro-deformation of a single biological cell among others. In this work, we develop a general variational formulation in account of electro-mechanical couplings. In the context of EHD, we identify the free energy functional and the associated energy minimization problem that determines the equilibrium shape of a bubble in an electric field. Based on this variational formulation, we implement a fixed mesh level-set gradient method for computing the equilibrium shapes. This numerical scheme is efficient and validated by comparing with analytical solutions at the absence of electric field and experimental results at the presence of electric field. We also present simulation results for zero gravity which will be useful for space applications. The variational formulation and numerical scheme are anticipated to have broad applications in areas of EWOD, EHD and electro-deformation in biomechanics.
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Fu, J. Y., H. S. Zhang, H. B. Cai, P. L. Yao i S. P. Zhu. "Effect of ablation on the nonlinear spike growth for the single-mode ablative Rayleigh–Taylor instability". Matter and Radiation at Extremes 8, nr 1 (1.01.2023): 016901. http://dx.doi.org/10.1063/5.0106832.
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The effect of ablation on the nonlinear spike growth of single-mode ablative Rayleigh–Taylor instability (RTI) is studied by two-dimensional numerical simulations. It is shown that the ablation can reduce the quasi-constant velocity and significantly suppress the reacceleration of the spike in the nonlinear phase. It is also shown that the spike growth can affect the ablation-generated vorticity inside the bubble, which further affects the nonlinear bubble acceleration. The vorticity evolution is found to be correlated with the mixing width (i.e., the sum of the bubble and spike growths) for a given wave number and ablation velocity. By considering the effects of mass ablation and vorticity, an analytical model for the nonlinear bubble and spike growth of single-mode ablative RTI is developed in this study. It is found that the nonlinear growth of the mixing width, induced by the single mode, is dominated by the bubble growth for small-scale ablative RTI, whereas it is dominated by the spike growth for classical RTI.