We present a systematic computational study of helium bubble coalescence in plasma-facing component (PFC) tungsten under helium retention conditions relevant to fusion reactor operation. The thermodynamics and kinetics of bubble coalescence are examined over a multidimensional parameter space encompassing the sizes, separation distance, internal pressure, and growth rate of two interacting helium bubbles. Targeted molecular-statics and molecular-dynamics simulations are used to identify the governing interaction energetics and coalescence mechanisms. The interaction between two helium bubbles is found to be well described by an elastic perturbation from a finite-width square-well potential, whose width defines a capture radius that correlates directly with bubble pressure. At short separation distances, the defective tungsten regions surrounding the adjacent bubbles merge, forming a characteristic dumbbell-shaped configuration. When the tungsten ligament separating the two bubbles is reduced to approximately one atomic layer, stress-driven displacement of tungsten atoms creates an open channel that connects the bubbles, enabling helium gas flow between the two bubbles and initiating coalescence. Localized strain in the narrowing ligament promotes Frenkel-pair formation, facilitating channel opening through vacancy creation and tungsten self-interstitial accommodation. Continued helium implantation after coalescence increases bubble pressure, leading to the emission of 12⟨111⟩ and ⟨100⟩ dislocation line segments from the bubble surface. For sufficiently large helium bubbles separated by distances exceeding the capture radius, dislocation emission narrows the interbubble tungsten ligament, thereby accelerating the coalescence process.
The manipulation of underwater gas bubbles offers potential for addressing pressing challenges such as energy shortages and oxygen harvesting in space. While substantial progress has been made in 1D bubble transport on asymmetric geometric-gradient surfaces and 2D penetration based on "bubble diode" type Janus surfaces, the integration of these functions, particularly for complex bubble manipulation under microgravity or against buoyancy, remains a challenge. Inspired by the hierarchical wettability gradients of cactus spines and the upper/lower surfaces of lotus leaves, we herein design and fabricate a directional transport channel with unidirectional penetration channels for gas bubbles. The influence of structural parameters on bubble motion and the performance of these channels under antibuoyancy conditions is systematically investigated. Moreover, a multifunctional integrated surface was developed through a simple fabrication strategy, enabling the simultaneous capture, directional transport, and collection of bubbles, and realizing complex 3D manipulation of bubbles in aqueous environments. In addition, the surface effectively captures, transports, and collects bubbles generated during water electrolysis. This work presents an integrated surface design for underwater bubble capture, transport, and collection, and offers a potential approach to bubble management in microgravity environments.
During ureteroscopic laser lithotripsy (URSL), unsafe elevations in ureteral temperature are thought to contribute to ureteral stricture formation. Cellular damage begins at 43°C, and proteins denature instantly at 60°C. Air bubbles may inadvertently migrate into the collecting system during URSL. The purpose of this study was to evaluate ureteral temperatures during simulated URSL in an air bubble with a holmium (Ho:YAG) and thulium fiber laser (TFL). BegoStone phantoms were positioned distal to the ureteropelvic junction in a model kidney and ureter submerged in a 35°C saline bath. A 7.5 Fr flexible ureteroscope was advanced to the stone, and continuous saline irrigation at 22°C was maintained at 15 mL/min. A needle thermocouple positioned 2 mm from the laser fiber tip monitored ureteral wall temperature. A 200 µm laser fiber was then advanced until it contacted the stone. The Ho:YAG and TFL were used in 5 trials each to ablate stones at 3, 10, and 20 W in saline and in a 3 mL air bubble. In the control condition, neither laser exceeded 43°C at 3, 10, or 20 W. In an air bubble, ureteral temperatures exceeded 43°C after 1 second at 3 W for both TFL and Ho:YAG. At 10 W, the Ho:YAG exceeded 43°C after 1 second, while the TFL exceeded 60°C. The average temperature exceeded 60°C at 20 W for both lasers after 1 second. Both lasers generated much higher temperatures in an air bubble than in saline at all time points (p = 0.008), with maximum temperature exceeding 250°C for both lasers. In this benchtop model, laser activation in an air bubble for 1 second exceeded the thermal safety threshold at ≥ 3 W and risks protein denaturation at ≥ 20 W. This study highlights the importance of avoiding air bubbles during URSL to maintain safe ureteral temperatures. Further studies are needed to validate these findings in vivo.
Sweat is a rich biofluid whose composition depends heavily on physiology and varies systematically across a range of systemic and dermatological conditions, making it an attractive medium for non-invasive diagnostics. However, existing diagnostic tools, which rely primarily on electrochemical ion-selective electrodes and optical microfluidic systems, require complex instrumentation and have significant limitations in ease of application and deployment. This poses a need for a low-cost, simple sensing approach using sweat as a sample for disease detection. Here we demonstrate a novel bubble sensing methodology that exploits the relationship between bubble film stability and electrolyte concentration in a reagent-free setup requiring no electrochemical transduction. A controlled-volume bubble was made using a sodium dodecyl sulphate-glycerol solution, which was then tested by adding potassium chloride (KCl) solutions at concentrations of 0.01-0.15 mol L-1, simulating sweat at variable ionic strengths. Two characteristic timescales were identified: the time to burst (tb), measured by the naked eye on a seconds timescale, and the film retraction time (τ), resolved at 100 000 frames per second using a high-speed camera. The time to burst exhibited a strong exponential decay with increasing KCl concentration (R2 = 0.934), with greatest sensitivity in the healthy resting sweat range (0.01-0.1 mol L-1) and a plateau at pathological concentrations above 0.1 mol L-1. High-speed imaging revealed distinct changes in rupture initiation location and film retraction behaviour upon analyte addition, with retraction time increasing from 250 µs in control bubbles to ∼1.5 ms. The observed trend was quantitatively reproduced using a coupled DLVO-Kramers nucleation model, identifying electrostatic double-layer screening as the primary mechanism driving faster rupture at higher ionic strength. This work establishes the proof of concept for bubble rupture dynamics as a functional sensing mechanism and provides the basis for further development of surfactant bubble-based biosensors.
The bubble tube of a glass curing furnace was subjected to extreme heat-flow coupling conditions for a long time due to the scouring of melt flow caused by the gas flow bubbling in a high-temperature molten glass environment at 1150 °C, resulting in severe corrosion and structural failure. This paper conducts post-service sampling analysis of an Inconel 690 bubble tube, and systematically studies its corrosion morphologies, product distribution and corrosion mechanisms. The results show that the outer wall of the bubble tube undergoes an oxidation reaction in the high-temperature molten glass to form a Cr-rich oxide layer. However, local spalling occurs under the scouring of the molten glass flow, resulting in continuous corrosion. The corrosion behavior shows obvious asymmetry. The average corrosion rate near the bubble flow side (the inner curve side, 0.118 mm/day) is significantly higher than that on the outer side (0.051 mm/day) due to the higher partial pressure of oxygen and greater flow rate of molten glass. It reveals the synergistic mechanism by which fluid scouring continuously removes the protective Cr-rich oxide scale, thereby accelerating the oxidation-erosion cycle under the heat-flow coupling effect. The results provided experimental evidence and theoretical reference for the material optimization and life prediction of bubble tubes.
The role of the localized surface plasmon resonance (LSPR) effect in promoting the efficiency of hydrogen production by enhancing the catalytic performance has been much studied, but it is a complex physical phenomenon involving electromagnetic and temperature fields, and little research has been conducted on the aspect of its effect on mass transfer. In this study, we investigate the kinetics of individual hydrogen bubble formation during the hydrogen evolution reaction (HER) under LSPR excitation on a microelectrode. Our results reveal a dramatic reduction in the bubble growth-to-detachment time, from 60 s to 0.9 s, accompanied by a two-orders-of-magnitude increase in the hydrogen generation rate. LSPR induced by Au nanoparticles (AuNPs) generates a thermal Marangoni flow at bubble interface, producing a detachment force of 59.10 μN, thereby improving mass transport and reaction efficiency. Increasing light intensity further optimizes mass transfer by shifting the reaction-control regime. These results highlight the multifunctional role of LSPR in enhancing both catalytic and mass-transfer processes in electrochemical hydrogen production, which has implications for LSPR-based photoelectrochemical (PEC) catalysis, electrochemical water splitting, and even CO2 reduction.
Raman spectroscopy has widely been recognized as an analytical tool of high potential in biopharmaceutical downstream processing, and the use of flow cells has been suggested for use in in situ or in-line Raman spectroscopy measurements at least for development-scale processes. However, there remains a need for Raman analysis of samples that cannot be accessed through an in-line monitoring system, particularly for low-volume samples in micro-to-milliliter range. This article presents a new setup that enables automated Raman measurements of liquid samples with low injection volume of 300 µL. A designed adapter links a Tornado Micro Flow Cell to a Tecan liquid handling system, allowing direct sample delivery. This work focuses on a set of methods implemented on this setup to address the issue of air bubbles, which can significantly interfere with Raman signal quality during measurement. These methods include adapted residence time, a three-step purging/cleaning method, combined with a vertical and upflow flow-cell orientation. A series of experiments demonstrates the effectiveness of these methods in reducing air bubbles and improving spectral robustness. The presented setup and methods enable automated high-throughput Raman detection of fluidic samples with small injection volumes and high-quality spectral data.
Hypoxemia after left ventricular assist device (LVAD) implantation is a life-threatening complication with a wide differential diagnosis. One potentially catastrophic cause is right-to-left shunting through an unmasked or underestimated patent foramen ovale (PFO). We describe a 63-year-old man in whom an intraoperatively identified PFO with left-to-right flow was initially judged mild and unlikely to be clinically significant. However, on postoperative day 1 in the intensive care unit, profound refractory hypoxemia developed due to massive right-to-left shunting, requiring rescue venovenous (VV) extracorporeal membrane oxygenation (ECMO). Furthermore, a bedside agitated saline solution study (bubble study) performed by transesophageal echocardiography under full VV-ECMO support was confounded by the extracorporeal sump effect, wherein the high-velocity venous drainage cannula siphoned agitated saline solution and led to a significant underestimation of the intracardiac shunt. This case reinforces the argument for a low threshold for PFO closure at the time of LVAD implantation, given the inherent limitations of preoperative echocardiographic assessment in advanced heart failure: Even defects that appear mild may carry clinically significant risk after LVAD-mediated left atrial decompression. Additionally, clinicians should be aware that active ECMO venous drainage can mask or underestimate intracardiac shunting on bubble study and that transient reduction of extracorporeal flow is essential for accurate interpretation during concurrent ECMO support.
This study examined how preferred bubble-tube motion speeds in sensory rooms relate to individual physiological and psychological characteristics, including interoceptive sensitivity, subjective time perception, visual discomfort, and anxiety levels. Fifty adult participants took part in a controlled laboratory experiment using a method-of-adjustment procedure to select their most comfortable motion speed for a simulated bubble tube, presented as an upward-moving Random Dot Motion (RDM) stimulus. Subjective time perception was evaluated using a 60-second time-estimation task, and interoceptive sensitivity was measured via a heartbeat-tracking task. Visual discomfort and anxiety were assessed using the Japanese versions of the Visual Discomfort Scale (VDS-J), Trypophobia Questionnaire (TQ-J), and State-Trait Anxiety Inventory (STAI). The results from the method of adjustment indicated that the preferred speed varied widely, from 1.09 to 13.86 degrees per second. Spearman's correlation analysis revealed that higher interoceptive awareness was associated with a preference for slower speeds, whereas higher anxiety levels were associated with a preference for faster speeds. In addition, multiple regression analysis showed that subjective time-perception accuracy and visual discomfort levels were significant predictors of participants' preferred RDM speeds. The results indicate that interoceptive sensitivity, subjective time perception, visual discomfort, and anxiety levels play significant roles in determining preferred RDM stimulation speeds. These findings highlight the importance of considering individual differences in physiological and psychological states when designing therapeutic sensory environments, such as sensory rooms and bubble tubes, to support comfort, well-being, and therapeutic outcomes.
This study explores women's experiences of pelvic floor (PF) care after childbirth, revealing significant insights into their physical and emotional journeys during the transformative period following birth in a Swedish tertiary hospital context. The focus is on women who sustained third- or fourth-degree PF injuries after vaginal birth, viewed through the perspective of universal design (UD). The study uses qualitative methods, observations, and interviews to illuminate challenges in PF care. Qualitative content analysis is used to identify themes emerging from participants' narratives. Comics serve as a visual and multimodal method to depict the variety and sequencing of women's narratives in multimodal ways. The analysis identified two main themes. The first, the Bubbleverse, is a metaphor for women's experiences across interconnected phases of birth and recovery, where PF injuries were often overshadowed by vaginal birth, newborn care, and future uncertainty. The second theme reflected women's recommendations for healthcare, calling for timely, individualised communication, and structured support. The study concludes with a call to reconfigure the fragmented and underprioritised aftercare. Alternative care pathways tailored to individual needs are essential for more equitable PF care.
Bubble continuous positive airway pressure (bCPAP) is a low-cost respiratory support device that has demonstrated different outcomes for children with severe pneumonia in different settings. Some differences in outcomes may be attributable to implementation factors (e.g., patient monitoring and feeding practices). We aimed to characterize bCPAP reach, implementation fidelity, and safety outcomes for children with severe pneumonia in Pakistan. We conducted a prospective cohort study at Aga Khan University Hospital and Abbasi Shaheed Hospital from February through May 2025. We enrolled children 1-59 months who met WHO criteria for severe pneumonia within 24 hours of presentation to the emergency department. Participants were followed daily via chart review, caregiver survey, and physical exam through discharge, transfer, or death. We reported the proportion of children receiving bCPAP ("reach") and constructed a mixed-effects, multinomial logistic regression model with robust standard errors to report: fidelity (child location in a highly monitored area, continuous monitoring, avoidance of unplanned disruptions to bCPAP, and avoidance of oral feeding); safety (aspiration events and pneumothorax); bCPAP failure (death, respiratory support escalation, or leaving against medical advice); and in-hospital mortality. Of 165 children with severe pneumonia, 88 (53%) received bCPAP over 141 bCPAP days. The average predicted probabilities (95% CI) of our fidelity measures were: 85% (78-92%) for location in a highly monitored area; 56% (51-60%) for continuous monitoring; 66% (57-75%) for continuous bCPAP without disruptions; 46% (36-55%) for avoidance of oral feeding while on bCPAP. Among children receiving bCPAP, 9 (10%) experienced an aspiration event, 1 (2.2%) experienced a pneumothorax; 19 (22%) experienced bCPAP treatment failure. One child (1.1%) died; 6 (6.8%) required respiratory support escalation; 14 (16%) left against medical advice. We identified several gaps in bCPAP reach and fidelity. These may be modifiable by individual- and team-targeted strategies to reduce bCPAP-related complications and pneumonia-related child deaths.
Biofilm-associated contamination represents a persistent and costly challenge across environmental systems, causing reduced efficacy of disinfectants. Recently, nanobubbles (NBs) have shown promise for biofilm decontamination; yet, their underpinning mode of action remains a topic of debate. In this study, the interaction of air-generated NBs with Escherichia coli and Staphylococcus aureus biofilms was investigated. NBs were generated using a venturi nozzle and characterized using Nanoparticle Tracking Analysis, revealing a NB density of 5.66 × 108 particles/mL and a mean diameter of 84 nm. Application of NB solution to microbial biofilms resulted in a 2.16 log reduction for E. coli and 1.52 log reduction for S. aureus, along with visible morphological changes such as cell collapse, wrinkling, and matrix disruption. ESR spin trapping confirmed hydroxyl radical formation, but intracellular ROS and lipid peroxidation levels were minimal and, in some cases, not significantly different from Milli-Q water controls. After 28 days, NBs remained present and continued to demonstrate antimicrobial activity, biofilm disruption, and some ROS activity. These findings indicate that although hydroxyl radicals are generated, oxidative stress is not the dominant antimicrobial mechanism under the examined conditions, suggesting physical biofilm disruption is the primary mode of action.
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The power-induced quenching for sonochemical reactions in which the rate of sonochemical reactions decreases sharply as ultrasonic power increases is interpreted by a multiscale numerical simulation based on the Caflisch model. The utilization of a representative acoustic bubble for each numerical grid cell facilitated the numerical modeling of the interaction between the fundamental ultrasonic wave and the sound emission and absorption from the bubbles. The numerical results indicated that the waveform of ultrasound is largely distorted by the sound emission and absorption from the bubbles, generating harmonics and broadband noise. In the highly distorted conditions, the maximum temperature at the moment of bubble collapse experiences a substantial decrease, which contributes to the phenomenon of power-induced quenching. While the larger bubble number density and larger equilibrium bubble radius result in heightened sound emission and absorption from the bubbles, leading to a modest decline in the maximum temperature within the bubble, the predominant factor contributing to the temperature decrease and the sound emission and absorption is the sound pressure amplitude. This finding further substantiates the phenomenon of power-induced quenching. The sound wave maintains a standing wave configuration at a low-pressure amplitude, but transitions into a traveling wave configuration at a high-pressure amplitude due to the process of sound emission and absorption from the bubbles. In the traveling wave field, the temperature within the bubble is observed to decrease, while the distribution of the high-temperature zone becomes more extensive. This phenomenon aligns closely with the outcomes of previous experimental studies.
Ultrasound has gained widespread application in the field of transdermal drug delivery (TDD), including dermatological therapy and aesthetic medicine, owing to its non-invasive nature and cost-effectiveness. Despite its widespread use, clinical researchers have largely relied on empirical selection of low-frequency ultrasound (tens to hundreds of kHz) for single-frequency sonophoresis, and a mechanistic understanding of how ultrasound frequency regulates cavitation-from nucleation to bubble collapse-remains lacking, which limits the rational design of ultrasound-based TDD systems. In this study, we proposed a simulation framework that couples Zwart-Gerber-Belamri (ZGB) cavitation model (for nucleation) with Keller-Miksis (K-M) equation (for bubble dynamics), thereby addressing the limitation of existing models that treat nucleation and bubble growth/collapse separately. Using this model, we analyzed the relationship between ultrasound frequency and cavitation effects was analyzed. The results indicate that high-frequency ultrasound can facilitate faster generation of more cavitation nuclei, whereas low-frequency ultrasound is more conducive to the growth and collapse of pre-existing bubbles. Based on these findings, an integrated dual-frequency (400 kHz, 2 MHz) ultrasound transducer (iDFUT) was designed and fabricated to enhance the efficacy of dermatological treatments. Both in vitro and in vivo studies confirmed that this device significantly improves drug delivery efficiency. The proposed theoretical model, dual-frequency transducer design, and experimental validation form an integrated framework that directly links cavitation mechanisms to device optimization and therapeutic efficacy, offering a reliable technical reference for the rational development of ultrasound-mediated TDD systems.
This study aimed to evaluate the prognostic value of late-stage vacuolization in Day 4 embryos relative to compaction status. We retrospectively analyzed 9,779 embryos from 2,409 patients undergoing fresh D4 transfers between 2018 and 2024. Embryos were stratified by compaction status (full, part, non-compaction) and assessed for vacuolization. Predictive performance for blastocyst formation was evaluated using ROC curves and logistic regression. The results showed that late-stage vacuolization correlated with higher maternal and paternal age, increased gonadotropin (Gn) dosage, and lower Anti-Müllerian Hormone (AMH)/estradiol (P<0.001), but comparable oocyte yield and intracytoplasmic sperm injection (ICSI) rates (P>0.05). False-compaction subgroup​ (77.6% of vacuolized embryos) showed reduced transferable blastocyst (38.7% vs. 53.3%, P=0.021), high-quality blastocyst (9.8% vs. 23.4%, P=0.001), and day 5 blastocyst rates (20.6% vs. 35.1%, P=0.007). A significant interaction was observed between late-stage vacuolization and compaction status affecting both transferable and high-quality blastocyst formation (P for interaction<0.001). Specifically, late-stage vacuolization significantly increased the rates of transferable (OR = 3.34, 95% CI = 2.54-4.39, P<0.001) and high-quality blastocyst formation (OR=2.51, 95% CI=1.60-3.96, P<0.001) in the non-compacted subgroup. Conversely, it decreased the high-quality blastocyst formation rate in the fully compacted subgroup (OR=0.37, 95% CI=0.15-0.89, P=0.026), while showing no significant effect on transferable blastocyst formation in this group (OR=0.83, 95% CI=0.28-2.48, P=0.740). In conclusion, late-stage vacuolization is a compaction-dependent prognostic marker, detrimental in compacted embryos yet potentially beneficial in non-compacted ones. We hypothesize that its effects may be mediated through mechanical stress-induced pseudo-compaction, suggesting that it should be integrated into D4 embryo grading systems in a context-specific manner. This study looked at over 9,700 embryos used in IVF. We found that tiny, bubble-like structures (called "vacuolization") inside a 4-day-old embryo can be either good or bad news, depending on whether the embryo's cells are tightly or loosely packed together. In tightly packed embryos, these bubbles are harmful and reduce the chance of forming a high-quality embryo. In loosely packed embryos, the same bubbles can be helpful and increase the chance of successful development. This is different from other embryo problems, which are always bad. By checking for these bubbles and how packed the cells are, we can predict which embryo is most likely to lead to a baby 10% more accurately than before. To use this new method, embryos need to be grown for 4 days instead of 3.
This study proposes a novel dynamic composite heat source combining discrete tracking and vapor heating, which can precisely capture the transient energy deposition at the keyhole wall, and further discusses the formation mechanism of weld defects by investigating keyhole evolution and melt pool flow behavior. The weld morphology and dimensions predicted by the simulation are in good agreement with the experimental data, revealing the coupled mechanism between keyhole instability and porosity formation, as well as the generation mechanism of process-type porosity mainly influenced by the keyhole dynamic characteristics and the melt pool flow field together; specifically, keyhole instability forms a vapor cavity that will generate bubbles to participate in melt pool flow if it cannot be re-fused with the keyhole, and the bubble trajectory is related to buoyancy, gravity and liquid flow in the melt pool, with larger bubbles less likely to escape due to greater liquid viscous force. In addition, this study finds that increasing weld power and weld speed helps improve keyhole stability, weaken melt pool circulation intensity and shorten bubble escape path, thereby fundamentally revealing the formation mechanism of porosity defects during electron beam welding (EBW) of aluminum alloy, providing an effective numerical tool for optimizing EBW process parameters, and proposing corresponding inhibition measures to improve weld quality.
Accurate oil-water interface measurement in small transparent test tubes is important for subsequent volume readout in laboratory analysis. However, manual observation and conventional vision-based methods are easily affected by illumination variation, wall stains, and bubbles, while deep learning detectors alone usually provide only coarse semantic perception. To address this issue, a coarse-to-fine framework is proposed for robust oil-water interface measurement. In the coarse stage, YOLOv8n is used to provide semantic constraints for subsequent processing. In the fine stage, a Fisher-discriminative chromatic-weighted brightness feature is constructed from RGB information, where the RGB weights are derived from the Fisher criterion to enhance oil-water chromatic separability rather than using fixed grayscale or empirical channel weights. This feature is then fused with a SobelY-based vertical-gradient feature to improve interface localization. A stain-aware row-aggregation strategy with effective-pixel compensation is further introduced to suppress artefact interference. The validated interface position is finally converted into a volume readout, with additional correction for bubble-induced bias. The framework was validated on sampled frames from a complete shale-oil core pressing process conducted under mixed-lighting conditions. Stage-wise evaluation and ablation results indicate that the proposed design improves readout stability under stains, bubbles, and illumination variation, achieving a mean absolute error of 0.0159 mL and keeping the maximum error below 0.03 mL in the current experimental setup.
Electrocatalytic hydrogen evolution reaction (HER) necessitates managing both macroscopic wettability for bubble release and microscopic water structure for proton transfer. However, highly hydrophilic surfaces, while beneficial for bubble transport, tend to induce strongly hydrogen-bonded water networks that hinder proton dynamics, presenting a fundamental conflict in advancing electrocatalyst design. Herein, we leverage polymeric modifiers to tune the surface electronic structure of platinum electrodes and investigate the synergistic influence of macroscopic wettability and microscopic interfacial water structure on HER performance. We demonstrate that peak HER performance is achieved on polyethylenimine (PEI)-modified Pt electrode, which uniquely affords moderate hydrophilicity (contact angle: ∼15°) alongside a disordered, weakly hydrogen-bonded interfacial water network. This dual optimization enhances bubble release and proton-transfer kinetics, reducing the overpotential by 229 mV at 10 mA cm-2 compared to pristine Pt. In situ Raman spectroscopy confirms an increase in weakly hydrogen-bonded water species under PEI modification compared to the superhydrophilic electrode. This study bridges interfacial water dynamics with electrode wettability, guiding the design of advanced electrocatalytic interfaces.