Bubble Formation Research Articles

Study of a novel micro‐cyclonic air flotation device for enhanced oil removal from wastewater

AbstractAs global oilfields advance into mid‐to‐late development stages, the produced fluids contain increasingly high water content, leading to substantial wastewater volumes. Existing oily wastewater treatment systems face challenges in meeting stricter discharge standards. To address this issue, this work proposes a micro‐cyclonic air flotation separator that integrates cyclonic and flotation technologies to enhance oil removal efficiency. An experimental setup was designed to systematically investigate the effects of structural and operational parameters on bubble formation and oil removal in a DN100 single‐tube micro‐cyclonic flotation device. Key operational parameters were selected, and structural parameters were optimized to support the development of a compact, high‐efficiency separator for oily wastewater treatment. The experimental results revealed that increasing dissolved air pressure reduces mean bubble size, increases bubble number density, and raises gas holdup. Conversely, as air flow rate increases, the mean bubble size grows, the number density initially rises before decreasing, and gas holdup follows a similar trend. Optimal structural parameters were determined, under which the device demonstrated excellent oil removal performance across an oil concentration range of 200–1000 mg/L, achieving a maximum removal efficiency of 85.69%.

Review of the behavior of helium bubbles in aged plutonium and their influence on material properties

The latest understanding of helium (He) bubbles in aged plutonium (Pu) and their effects on the properties and behavior of Pu is reviewed and compared to results from our laboratory. The radioactive decay of Pu atoms leads to the generation of uranium (U) atoms and alpha particles, the latter resulting in the evolution of He atoms, which aggregate over time to form He bubbles in the Pu lattice. A variety of techniques have been used to understand the He diffusion in aged Pu and the mechanisms of bubble formation. Also discussed are the effects of He bubbles on the mechanical properties (e.g., strength and hardness) as a result of the continuing formation of He bubbles over time.

Stirring the false vacuum via interacting quantized bubbles on a 5,564-qubit quantum annealer

Abstract False vacuum decay—the transition from a metastable quantum state to a true vacuum state—plays an important role in quantum field theory and non-equilibrium phenomena such as phase transitions and dynamical metastability. The non-perturbative nature of false vacuum decay and the limited experimental access to this process make it challenging to study, leaving several open questions regarding how true vacuum bubbles form, move and interact. Here we observe quantized bubble formation in real time, a key feature of false vacuum decay dynamics, using a quantum annealer with 5,564 superconducting flux qubits. We develop an effective model that captures both initial bubble creation and subsequent interactions, and remains accurate under dissipation. The annealer reveals coherent scaling laws in the driven many-body dynamics for more than 1,000 intrinsic qubit time units. This work provides a method for investigating false vacuum dynamics of large quantum systems in quantum annealers.

Molecular dynamics simulation of retention and bubble formation in tungsten with carbon impurities under high flux deuterium irradiation

Molecular dynamics simulation of retention and bubble formation in tungsten with carbon impurities under high flux deuterium irradiation

Non-intrusive experiments on coupled bubble dynamics and heat transfer during nucleate boiling under varying pressure conditions

The experimental investigation is concerned with the dynamics of single vapor bubble and heat transfer during nucleate boiling under varying pressure conditions, encompassing both atmospheric and sub-atmospheric levels. Utilizing high-speed rainbow schlieren deflectometry, a non-intrusive imaging technique for visualizing and quantifying the flow field variables in the fluid medium, this research examines the influence of operating pressure on some of the important parameters pertaining to boiling phenomenon such as bubble size, shape, and detachment mechanisms. The observations show that a decrease in pressure leads to the formation of larger bubbles, which, in turn, alters their growth mechanism. These changes in bubble behavior have a significant influence on the various forces acting on the growing bubble as well as on the associated heat transfer rates. The analysis provides insights into the complex interplay between buoyancy, surface tension, growth and contact pressure forces. Change in pressure significantly impacts these forces, influencing bubble dynamics. Moreover, the study presents a quantitative analysis of the whole field temperature distribution and heat transfer rates throughout the boiling process. Results reveal a strong dependence of thermal field on the working pressure, with higher pressures leading to more uniform temperature distributions. Evaporative component of heat transfer from the bubble base and convective heat transfer from the superheated layer are identified as the dominant mechanisms. Natural convection initially dominates, decreases post-nucleation, and increases upon bubble departure due to the fluid quenching effects.

EGFR-TKIs induce acneiform rash and xerosis via Caspase-3/GSDME-mediated pyroptosis of keratinocytes and sebocytes

Skin toxicities are the most common adverse effects of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). While EGFR-TKIs induce pyroptosis in lung cancer cells through Gasdermin E (GSDME) activation, it is unknown whether they can similarly affect skin cells. In this study, we used immunohistochemistry to demonstrate that in acneiform rash, the N-terminus of GSDME (GSDME-N) is predominantly expressed in the basal layer of the follicular epithelium and sebocytes, while it is absent in the interfollicular epidermis. In contrast, in cases of xerosis or secondary eczematous rash, GSDME-N was significantly expressed in the basal layer of the interfollicular epidermis and weakly or partially positive in the follicular epithelium. Bright-field microscopy of HaCaT and SZ95 cells treated with afatinib revealed cell swelling and large bubble formation, while scanning electron microscopy showed a reduction in microvilli and membrane pores formation. Transmission electron microscopy further revealed multiple membrane pores and decreased cytoplasmic density. Importantly, we found that GSDME is cleaved during afatinib-induced pyroptosis via caspase-3 activation. ELISA analysis further confirmed that afatinib-treated cells released elevated levels of HMGB1 and IL-1α. Meanwhile, inhibition of caspase-3 activity or knockdown of GSDME both suppressed afatinib-induced pyroptosis, while GSDME elimination did not affect caspase-3 activation. These results indicate that afatinib-induced pyroptosis in keratinocytes and sebocytes is mediated by the caspase-3/GSDME pathway. Our findings suggest that GSDME-dependent pyroptosis in HaCaT and SZ95 cells contributes to the development of acneiform rash and xerosis, highlighting the need for further investigation into the underlying mechanisms.

Dynamics of Taylor bubble formation in a small-scale flow focusing microchannel with an acute symmetrical inlet geometry

Dynamics of Taylor bubble formation in a small-scale flow focusing microchannel with an acute symmetrical inlet geometry

Accelerated kinetic Monte Carlo method for simulations of helium bubble formation in metals

Accelerated kinetic Monte Carlo method for simulations of helium bubble formation in metals

Experimental study on the flow field inside soap bubble at different incident velocities

Bubbles are widely present in nature. However, previous scientific studies have primarily focused on the development of the outer contour of the bubble while neglecting the changing behavior of the internal flow field due to the difficulty in implementing experiments. This study designs a simple experimental device that can conveniently observe changes in the flow field inside the bubble while avoiding the tedious operation and high costs associated with the particle image velocimetry (PIV) system. Accordingly, this experiment investigates the development process of the flow field inside the bubble and the velocity conditions required for bubble formation for different incident velocities and Reynolds numbers. The study first examines the minimum flow velocity necessary for bubble formation. Then, under low-speed conditions, the flow inside the straw is laminar, and the flow field inside the bubble exhibits a single vortex structure. Under high-speed conditions, the flow inside the straw transitions to turbulent flow, and the flow field inside the bubble exhibits a four-vortex structure. The formation process of this four-vortex structure shows variations as the flow velocity increases. In addition, this study proposes corresponding physical models for bubble formation under low and high flow velocities and verifies the models.

Influence of surfactant type on the microstructure, mechanical and thermal properties of phenolic foams

Surfactant chemistry can affect the phenolic foam (PF) properties by controlling the collision and combination of the created bubbles during foam production. The study was accomplished using two surfactant families, nonionic: polysorbate (Tween80) and anionic: sodium and ammonium lauryl sulfates (SLS30 and ALS70) and sodium laureth sulfate (SLES270) to manufacture PF foams. Tween80 and SLS30 resulted in foams with the lowest and highest densities, 20.2 ± 0.2 and 42.72 ± 0.4 kg/m3, respectively. All the surfactants created an open-cell morphology, except Tween80 with a semi-open-cell structure consisting of large cells and thicker cell wall thickness. The anionic surfactant had better performance, the foams made by SLS30 had cells with diameters of 338.5 ± 18.5 and cell density of 2.5 cell/mm3 × 105. While the SLES270 made foam with the highest cell density and the smallest cell size that caused higher compressive strength. The SLES270 led to keeping the foam flexibility even under the fire exposition, and it increased the thermal insulation by 50% while the other samples were turned into fragile foam. A higher level of polarity in SLES270 caused better micelle production and then better bubble formation, followed by the bubble coalition.

Platinum hydride formation during cathodic corrosion in aqueous solutions.

Cathodic corrosion is an electrochemical phenomenon that etches metals at moderately negative potentials. Although cathodic corrosion probably occurs by forming a metal-containing anion, such intermediate species have not yet been observed. Here, aiming to resolve this long-standing debate, our work provides such evidence through X-ray absorption spectroscopy. High-energy-resolution X-ray absorption near-edge structure experiments are used to characterize platinum nanoparticles during cathodic corrosion in 10 mol l-1 NaOH. These experiments detect minute chemical changes in the Pt during corrosion that match first-principles simulations of X-ray absorption spectra of surface platinum multilayer hydrides. Thus, this work supports the existence of hydride-like platinum during cathodic corrosion. Notably, these results provide a direct observation of these species under conditions where they are highly unstable and where prominent hydrogen bubble formation interferes with most spectroscopy methods. Therefore, this work identifies the elusive intermediate that underlies cathodic corrosion.

Process, dynamics and bioeffects of acoustic droplet vaporization induced by dual-frequency focused ultrasound.

Acoustic droplet vaporization (ADV) plays a crucial role in ultrasound-related biomedical applications. While previous models have examined the stages of nucleation, growth, and oscillation in isolation, which may limit their ability to fully describe the entire ADV process. To address this, our study developed an integrated model that unifies these three stages of ADV, stimulated by a continuous nonlinear dual-frequency ultrasound wave. Using this integrated model, we investigated the influence of nonlinear dual-frequency ultrasound parameters on ADV dynamics and bioeffects by incorporating tissue viscoelasticity through parametric studies. Our results demonstrated that the proposed model accurately captured the entire ADV process, ensuring continuous vapor bubble formation and evolution throughout the phase transition process. Moreover, the applied unified theory for bubble dynamics can simulate intense bubble collapse with high Mach Number as a result of the nonlinear effects of dual-frequency ultrasound. In addition, cavitation-associated mechanical and thermal damage appeared to be more strongly correlated with rapid bubble collapse than with maximum bubble size. Our research also revealed that the mechanical and thermal effects could be regulated independently to some extent by adjusting dual-frequency ultrasound parameters, as they presented differing sensitivities to frequency and acoustic power. Importantly, dual-frequency combinations such as 1.5MHz+3 MHz (fundamental and second harmonic), which exhibit a higher Degree of Nonlinearity (DoN) can extend bubble lifespan, offering a potential pathway to the efficacy of ultrasound treatments.

Decompression venous gas formation intensity scale

Relevance. Severe decompression sickness is the most common diving disorder; therefore, its diagnosis and prevention is considered important aspects of hyperbaric physiology and diving medicine. Diver’s susceptibility to gas bubble formation under decompression is most critical for decompression sickness prevention. Doppler bubble detection is the most common procedure to identify divers who are most susceptible to gas bubble formation under decompression; nevertheless, a more comprehensive examination including pulse pressure and 2D visualization of gas bubbles provide valuable advantages.The objective is to provide justify the implementation of the decompression risk and venous gas bubble formation scale.Methods. The study enrolled 42 divers who were examined for tolerance to gas bubble formation under decompression; gas bubbles were visualized using Doppler ultrasound. Next, the developed decompression risk and venous gas bubble formation scale was used to verify its efficiency and practical value.Results and discussion. After hyperbaric exposure, 2D gas bubble visualization data were analyzed showing that 6 subjects (14.3 %) had no decompression-caused gas bubble formation (0 points); 9 subjects (21.4 %) scored up to 5 points, showing a small amount of gas bubbles during exercise; 22 subjects (52.4 %) scored between 6 and 15; whereas the remaining 5 subjects presented with gas bubbles at rest and a sharp increase in bubble formation during mild exercise. The obtained data suggest that the examined diver cohort included 13 subjects (31 %) with very high tolerance to gas bubble formation, 21 divers (50 %) showing average tolerance and 8 highly susceptible subjects (19 %).Conclusion. During decompression, venous gas bubble formation scale has significant diagnostic value providing a tool to measure individual diver’s susceptibility to gas bubble formation. The scale allows to reduce the hyperbaric load by decreasing exposure on the ground at threshold pressure (0.4 MPa) and thus reduce the decompression time, based on sufficient evidence regarding individual susceptibility to gas bubble formation under decompression

Formulation Factors Affecting the Formation of Visible-Bubbles During the Reconstitution Process of Freeze-Dried Etanercept Formulations: Protein Concentration, Stabilizers, and Surfactants.

Freeze drying is one of the common methods to extend the long-term stability of biologicals. Biological products in solid form have the advantages of convenient transportation and stable long-term storage. However, long reconstitution time and extensive visible bubbles are frequently generated during the reconstitution process for many freeze-dried protein formulations, which can potentially affect the management efficiency of staff, patient compliance, and product quality. The reconstitution time has been extensively studied, but the influence of the formulations on the formation of visible bubbles is often overlooked. This paper investigated the effect of freeze-drying formulation factors (i.e., protein concentrations, surfactant concentrations, and sucrose/mannitol compositions) on product stability and visible bubbles generated during reconstitution of freeze-dried etanercept formulations. The generating and breakup mechanisms of visible bubbles were detected via internal microstructure of cake, surface tension, and viscosity measurement. Under the same protein concentration, the formulation of mannitol mixed with sucrose in a weight ratio of 4:1 produces fewer visible bubbles during the reconstitution process compared to the formulation of sucrose with the same total mass. This has been proven to be due to the large number of smaller radius pores distributed in the pores of the freeze-dried cake of the former, while the average internal structure pores of the latter are much larger than those of the former. As an amorphous stabilizer, sucrose can ensure the long-term stability of protein and greatly reduce the generation and maintenance of foams in the reconstitution process, making it a more robust excipient for freeze-dried protein formulations.

Quantitative investigation of a 3D bubble trapper in a high shear stress microfluidic chip using computational fluid dynamics and L*A*B* color space

Microfluidic chips often face challenges related to the formation and accumulation of air bubbles, which can hinder their performance. This study investigated a bubble trapping mechanism integrated into microfluidic chip to address this issue. Microfluidic chip design includes a high shear stress section of fluid flow that can generate up to 2.7 Pa and two strategically placed bubble traps. Commercially available magnets are used for fabrication, effectively reducing production costs. The trapping efficiency is assessed through video recordings with a phone camera and analysis of captured air volumes by injecting dye at flow rates of 50, 100, and 150 µL/min. This assessment uses L*A*B* color space with analysis of the perceptual color difference ∆E and computational fluid dynamics (CFD) simulations. The results demonstrate successful application of the bubble trap mechanism for lab-on-chip bubble detection, effectively preventing bubbles from entering microchannels and mitigating potential damage. Furthermore, the correlation between the L*A*B* color space and volume fraction from CFD simulations allows accurate assessment of trap performance. Therefore, this observation leads to the hypothesis that ∆E could be used to estimate the air volume inside the bubble trap. Future research will validate the bubble trap performance in cell cultures and develop efficient methods for long-term air bubble removal.Graphical abstract

Electrodeposited Nitrate-Intercalated NiFeCe-Based (Oxy)hydroxide Heterostructure as a Competent Electrocatalyst for Overall Water Splitting.

Electrochemical water splitting is a promising method for the generation of "green hydrogen", a renewable and sustainable energy source. However, the complex, multistep synthesis processes, often involving hazardous or expensive chemicals, limit its broader adoption. Herein, a nitrate (NO3-) anion-intercalated nickel-iron-cerium mixed-metal (oxy)hydroxide heterostructure electrocatalyst is fabricated on nickel foam (NiFeCeOxHy@NF) via a simple electrodeposition method followed by cyclic voltammetry activation to enhance its surface properties. The NiFeCeOxHy@NF electrocatalyst exhibited a low overpotential of 72 and 186 mV at 10 mA cm-2 for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, in 1.0 M KOH. In a two-electrode system, the NiFeCeOxHy@NF obtained a low voltage of 1.47 V at 10 mA cm-2 in 1.0 M KOH with robust stability. Results revealed that the notable activity of the NiFeCeOxHy@NF catalyst is primarily due to (i) hierarchical nanosheet morphology, which provides a large surface area and abundant active sites; (ii) NO3- anion intercalation enhances electrode stability and eliminates the need for binders while simultaneously promoting a strong catalyst-substrate adhesion, resulting in decreased electrode resistance and accelerated reaction kinetics; and (iii) the unique superhydrophilic surface properties facilitate electrolyte penetration through capillary action and minimize gas bubble formation by reducing interfacial tension.

Role of Competing Magnetic Exchange on Non-Collinear to Collinear Magnetic Ordering and Skyrmion Stabilization in Centrosymmetric Hexagonal Magnets.

Topological magnetic skyrmions with helicity state degrees of freedom in centrosymmetric magnets possess great potential for advanced spintronics applications and quantum computing. Till date, the skyrmion study in this class of materials mostly remains focused to collinear ferromagnets with uniaxial magnetic anisotropy. Here, we present a combined theoretical and experimental study on the competing magnetic exchange-induced evolution of noncollinear magnetic ground states and its impact on the skyrmion formation in a series of centrosymmetric hexagonal noncollinear magnets, MnFe1-xCoxGe. We show that by engineering the Fe/Co ratio, the system progressively transforms from a noncollinear magnetic state with in-plane antiferromagnetic ordering in MnFeGe to a collinear ferromagnetic (FM) spin arrangement in MnFe0.2Co0.8Ge. We utilize Lorentz transmission electron microscopy, neutron diffraction experiments, and micromagnetic simulations to demonstrate the role of competing magnetic exchange-induced in-plane magnetic moment in the formation of nontopological type-II magnetic bubbles in the system. However, skyrmions with degenerate helicity states are found to be stable magnetic entities in the case of the perfect uniaxial magnetic anisotropy system. The present study offers a great opportunity to tune the skyrmion phase in centrosymmetric magnets by intrinsically designing the magnetic ground state, thereby providing a unique platform for realizing skyrmion-based spintronics devices.

Revised method for constructing acoustic vulnerability curves in trees

Abstract During drought, the formation of air bubbles known as embolisms in the water-conducting xylem reduces hydraulic conductivity, which can ultimately result in tree death. Accurately quantifying vulnerability to embolism formation is therefore essential for understanding tree hydraulics. Acoustic emission (AE) analysis offers a non-destructive method to monitor this process, yet the interpretation of captured signals remains debated. In this study, we introduce an improved methodology for constructing acoustic vulnerability curves (VCAE) that minimizes subjectivity and enhances the accuracy of assessing a tree’s vulnerability to drought stress. Our approach combines AE signal clustering with an objective method for pinpointing the endpoint (point of 100% embolism) based on the observed correlation between water potential at maximum AE activity and 50% loss of hydraulic conductivity. By applying a refined clustering algorithm to four temperate tree species (Platanus × acerifolia (Aiton) Willd., Betula pendula Roth, Quercus robur L. and Fagus sylvatica L.), we consistently identified natural frequency-based clusters that effectively separate embolism-related AEs from other signals. This focus on embolism-related AE activity allowed us to minimize the influence of non-embolism-related signals and identify the true VCAE endpoint. Our method, by reducing the subjectivity inherent in previous approaches, enhances the accuracy of VCAE construction, offering broader insights into tree hydraulics and expanding its applicability across different species and environmental conditions.

Synergizing superwetting and architected electrodes for high-rate water splitting.

Water splitting is one of the most promising technologies for generating green hydrogen. To meet industrial demand, it is essential to boost the operation current density to industrial levels, typically in the hundreds of mA cm-2. However, operating at these high current densities presents significant challenges, with bubble formation being one of the most critical issues. Efficient bubble management is crucial as it directly impacts the performance and stability of the water splitting process. Superwetting electrodes, which can enhance aerophobicity, are particularly favorable for facilitating bubble detachment and transport. By reducing bubble contact time and minimizing the size of detached bubbles, these electrodes help prevent blockage and maintain high catalytic efficiency. In this review, we aim to provide an overview of recent advancements in tackling bubble-related issues through the design and implementation of superwetting electrodes, including surface modification techniques and structural optimizations. We will also share our insights into the principles and mechanisms behind the design of superwetting electrodes, highlighting the key factors that influence their performance. Our review aims to guide future research directions and provides a solid foundation for developing more efficient and durable superwetting electrodes for high-rate water splitting.

Performance of Fluid Infusion Systems in the Changing Atmospheric Pressures Encountered in Aviation.

With the increasing use of aeromedical transport for critically ill patients, it is essential to understand the impact of pressure changes on drug infusion delivery systems. As airplanes ascend and descend, gases/bubbles are released from solutions when ambient pressure decreases and dissolves when pressure increases. This may affect mechanical fluid delivery systems and cause clinically significant changes, especially within a critical care setting. We aimed to evaluate the impact of pressure changes on volumetric pumps and syringe drivers. An in vitro study of six volumetric pumps and eight syringe drivers was conducted in a hypobaric chamber to mimic pressure changes during flights. Infusion devices were set to deliver water at 0.2 ml ⋅ h-1 and infused volumes were measured. There were 15 open-ended syringes also studied. During ascent, syringe drivers and volumetric pumps over-delivered 173 µL and 38 µL of fluid. During descent, syringe drivers under-delivered by 166 µL, whereas volumetric pumps under-delivered by 9 µL. Syringe drivers experienced statistically significant changes in fluid delivery during both ascent and descent. In volumetric pumps, only the descent phase infusion differed significantly from other phases. The volume of fluid expansion is dependent on volume and the mechanical properties of the fluid. Decreasing ambient pressure causes bubble formation, which displaces fluid, and increasing ambient pressure causes bubble reabsorption in mechanical infusion devices. Hence, atmospheric pressure changes during air travel may alter fluid delivery from medical fluid delivery systems and affect critically ill patients who require both aeromedical evacuation and accurate infusion of drugs. Fan KS, Paterson M, Shojaee-Moradie F, Manoli A, Edwards V, Lee V, Hutchison E, Gifford RM, Parsons IT, Koehler G, Mathieu C, Mader JK, King BR, Russell-Jones D; EASA Consortium. Performance of fluid infusion systems in the changing atmospheric pressures encountered in aviation. Aerosp Med Hum Perform. 2025; 96(1):4-11.