Air Microbubbles Research Articles

The Emboless® venous chamber efficiently reduces air bubbles: a randomized study of chronic hemodialysis patients

Abstract Background When blood passes the extracorporeal circuit, air microbubbles (MBs) contaminate the blood. Some MBs will end up as microemboli in the lung, heart, and brain. MB exposure has no medical purpose and is considered as bio-incompatibility. Selecting venous chambers with high removal rate of MBs is warranted to reduce the risks of air bio-incompatibility. The primary aim was to compare the Fresenius 5008 (F5008-VC) and the Emboless® (Emboless-VC) venous chambers regarding the elimination of MBs in the return bloodline during hemodialysis (HD). Methods Twenty patients underwent 80 sessions of cross-over HD using both the F5008-VC and the Emboless-VC randomized such that half started with the F5008-VC and half with the Emboless-VC. For 32 of the 80 sessions measurements were also performed during hemodiafiltrations (HDF) after the initial HD. MBs were measured with an ultrasound device (within the size range of 20-500µm) at the ‘Inlet’ and ‘Outlet’ bloodline of the venous chambers. The Wilcoxon pairwise test compared the percentage of MB elimination between venous chambers. Results During HD, the median reduction of MBs for the Outlet was 39% with the F5008-VC and 76% with the Emboless-VC (p<0.001). During HDF, the reduction was 28% with the F5008-VC and 70% with the Emboless-VC (p<0.001). Conclusion Fewer MBs and subsequently fewer microemboli entered the bloodline of the patient using the Emboless-VC compared to the F5008-VC venous chamber during HD and during HDF. Venous chambers with a high removal rate of MBs will reduce the extent of air emboli.

Bubble-Inspired Multifunctional Magnetic Microrobots for Integrated Multidimensional Targeted Biosensing.

Microrobots possessing multifunctional integration are desired for therapeutics and biomedicine applications. However, existing microrobots with desired functionalities need to be fabricated through complex procedures due to their constrained volume, limited manufacturing processes, and lack of effective in vivo observation methods. Inspired by bubbles exhibiting various abilities, we report magnetic air bubble microrobots with simpler structures to simultaneously integrate multiple functions, including microcargo delivery, multimode locomotion, imaging, and biosensing. Contributed by buoyancy and magnetic actuation to overcome obstacles, flexible three-dimensional locomotion is implemented, guaranteeing the integrity of micro-objects adsorbed on the surface of the air bubble microrobot. Introducing air microbubbles enhances the ultrasound imaging capability of microrobots in the vascular system of mice in vivo, facilitating ample medical applications. Moreover, air-liquid reactions endow microrobots with rapid pH biosensing. This work provides a unique strategy to utilize relatively simple air bubbles to achieve the complex functions of microrobots for biomedical applications.

Synergistic cryoprotective effect of deaeration and polysorbate 80 on IgG denaturation during thin-film freeze-drying

Polysorbate 80 (PS80) is employed as a cryoprotectant in biotherapeutic formulations to preserve biologics from denaturation during the freezing process. However, excessive quantities of PS80 can lead to stickiness in dry powder, thereby reducing production yields and altering the physical and aerodynamic characteristics of the powder. Additionally, degradation byproducts of PS80 pose a risk of destabilizing proteins in therapeutic formulations. Our study reveals the synergistic cryoprotective effect of combining deaeration with PS80. PS80 plays a protective role by competitively binding to ice/water and air/water interfaces, as well as binding directly to IgG molecules. Deaeration increases the cryoprotective effect of PS80 by reducing the surface area of air microbubbles, thereby reducing the required amount of PS80 for surface coverage and limiting available adsorption sites for IgG molecules, which allows the decrease in the necessary concentration of PS80 required to minimize IgG denaturation during the thin-film freeze-drying (TFFD) process. Even at a low concentration of 0.0025 % w/v, PS80 prevents the aggregation of IgG during the freezing step of TFFD but does not eliminate IgG denaturation during the drying step. PS80 concentrations ranging from 0.0025 % to 0.0400 % w/v exhibit no impact on the specific surface area (SSA) and aerodynamic properties (i.e., fine particle fraction (FPF), mass median aerodynamic diameter (MMAD)) of IgG dry powders. These IgG TFFD powders exhibit a fine particle fraction exceeding 70 % and a median mass aerodynamic diameter of approximately 2.3–2.5 μm, with an SSA of around 20 m2/g.

#2703 Venous chambers vary in the reduction capacity of air microbubbles: a randomized study of chronic haemodialysis patients

Abstract Background and Aims The extracorporeal circuit (ECC) enables haemodialysis (HD) of patients. When the blood passes the ECC air contamination occurs, and consequently microbubbles (MBs) enter into the patient. MBs are verified at autopsy of HD patients and are covered by clots manifested as microemboli that are deposited within the lung, heart and brain tissue. A venous chamber is inserted in the ECC to reduce air contamination. However, venous chambers in clinical use have limited capacity in eliminating MBs from entering the return bloodline. In an in vitro study, the Emboless® chamber showed better results in comparison to models commonly used clinically (the best of the clinical models was the Fresenius 5008). Our aim was to determine if the Emboless® venous chamber differed in its capacity to limit MB exposure compared to the Fresenius 5008 (F5008) during HD and hemodiafiltration (HDF). Method Twenty chronic HD patients were included in a cross-over randomized study to compare the Emboless® to the F5008 venous chamber during HD. Each patient underwent a total of four dialyses divided into two paired series. This resulted in 80 studied dialyses, of which 32 included HDF. Dialyzers, blood-pump speed, HD or HDF, and ultrafiltration was the same between the pairs. MBs (20-500 µm, merged in intervals of 5 µm) were measured with an ultrasound device adjusted for HD (BCC200, GAMPT) at the ‘inlet’ and ‘outlet’ of the venous chamber. Measurements of MBs were done in the HD mode during the first 30 minutes, and if HDF was prescribed the measurement proceeded for another 30 minutes after the switch to the HDF mode (time was extended if fewer than 1000 MBs were detected at the inlet). The percentage of change in the ‘outlet’ versus ‘inlet’ counts was compared (paired Wilcoxon test). A total reduction was equal to −100%, while an increase (+) of MBs (worsening) was expressed as an unlimited percentage. If a diameter of an MB was without counts, it was not included in the analysis. Results For patients during HD, the median change of MBs in the outlet versus the inlet bloodline was −39% with the F5008 (n = 3807) and −76% with the Emboless® (n = 3805) venous chambers (p < 0.001, Fig. 1). For patients during HDF, the median change of MBs in the outlet versus the inlet bloodline was −28% with the F5008 (n = 1549) and −70% with the Emboless® (n = 1517) venous chambers (p < 0.001, Fig. 2). Conclusion Fewer MBs and subsequently fewer microemboli entered the patient using the Emboless® compared to the Fresenius 5008 venous chamber during HD, as well as during HDF. In considering previous autopsy studies, our results support less patient tissue damage when using the Emboless® venous chamber.

Optimizing fouling mitigation in membrane distillation by controlled microbubble size and concentration

Fouling control strategies play a crucial role in membrane distillation (MD) process, primarily due to the significant limitation of fouling during the scaling-up process. The utilization of microbubbles (MBs) aeration has exhibited promising potential in mitigating membrane fouling when treating high salinity wastewater. Aeration can introduce gas-liquid two-phase flow on the membrane surface, thereby increasing the membrane surface shear force. The mechanism of aeration technology for controlling fouling includes the following points: introduction of gas-liquid two-phase flow; physical substitution of concentration polarization layer; pressure pulses caused by bubbles flowing through the membrane surface and increasement of the cross flow velocity. This research aims to optimizing the effect of air MBs with different concentrations and sizes introduced in the feed side on membrane fouling control, we creatively used the method of releasing pressure gradiently to achieve size regulation of MBs within a certain range for the first time, firstly regulated the generation of MBs by manipulating gas flow rate and release pressure. Under the optimal condition of 40 mL/min and 0.6 MPa, it will yield concentration of 1.58 × 104/mL and D50 Sauter size of 64.69 μm MBs with pure water permeance flux of 12.32 kg/(m2·h). It was observed that higher gas flow rates primarily increased MBs concentration, while lower pressures predominantly reduced MBs size through the method of inline imaging. Experimental results indicated that introduction of MBs can slightly improve the temperature polarization coefficient and mass transfer coefficient under different operating modes. Consequently, further investigations focused on the influence of MBs characteristics on different fouling control. All conditions reach 99 % rejection for inorganic salt and HA. This study provided empirical evidence that higher concentration and larger size of MBs intensify the gas-liquid two-phase flow disruption and exhibit a better shear effect on scaling phenomena, which yield advantageous outcomes in terms of augmenting permeance flux and water vapor production, with permeance flux increased from 40.12 % to 55.42 % for inorganic fouling and increased from 68.35 % to 80.15 % for inorganic and HA fouling. These results were confirmed via membrane surface using scanning electron microscopy and energy dispersive spectroscopy. In summary, this research aided in identifying appropriate operating conditions for mitigating inorganic and composite scaling by implementing air-infused MBs in direct contact membrane distillation (DCMD), which provides scientific and technical guidance for controlling fouling in MD in practical applications.

High-sensitivity strain sensor based on an asymmetric tapered air microbubble Fabry-Pérot interferometer with an ultrathin wall

A Fabry-Pérot interferometer (FPI) with an asymmetric tapered structure and air microbubble with an ultrathin wall is designed for high-sensitivity strain measurement. The sensor contains an air microbubble formed by two single-mode fibers (SMF) prepared by fusion splicer arc discharge, and a taper is applied to one side of the air microbubble with a wall thickness of 3.6 µm. In this unique asymmetric structure, the microbubble is more easily deformed under stress, and the strain sensitivity of the sensor is up to 15.89 pm/µɛ as evidenced by experiments.The temperature sensitivity and cross-sensitivity of the sensor are 1.09 pm/°C and 0.069 µɛ/°C in the temperature range of 25-200°C, respectively, thus reducing the measurement error arising from temperature variations. The sensor has notable virtues such as high strain sensitivity, low-temperature sensitivity, low-temperature cross-sensitivity, simple and safe process preparation, and low cost. Experiments confirm that the sensor has good stability and repeatability, and it has high commercial potential, especially strain measurements in complex environments.

Effect of supersaturated dissolved oxygen on growth-, survival-, and immune-related gene expression of Pacific white shrimp (Litopenaeus vannamei).

Oxygen concentration is an essential water quality parameter for aquaculture systems. Recently, supersaturated dissolved oxygen (DO) has been widely used in aquaculture systems to prevent oxygen depletion; however, the long-term effects of supersaturated DO exposure on aquatic animals have not been studied. In this study, we examined the effects of supersaturated DO on the growth, survival, and gene expression of Pacific white shrimp (Litopenaeus vannamei). Specific pathogen-free shrimp with a body weight of 8.22 ± 0.03 g were randomly assigned to two groups with four replicates at a density of 15 shrimps per tank. Shrimp were cultivated in recirculating tanks containing 50 L of 15 ppt seawater in each replicate. Oxygen was supplied at 5 mg/L to the control tanks using an air microbubble generator and at 15 mg/L to the treatment tanks using a pure oxygen microbubble generator. Shrimp were fed commercial feed pellets containing 39% protein at 4% of their body weight per day for 30 days. Average daily growth (ADG) and feed conversion ratio (FCR) were determined on days 15 and 30. Shrimp molting was measured every day. Individual hemolymph samples were obtained and analyzed for total hemocyte count, differential hemocyte count, and expression of growth- and immune-related genes at the end of the experiment. Long-term exposure to supersaturated DO significantly affected shrimp growth. After 30 days of supersaturated DO treatment, the final weight and ADG were 14.73 ± 0.16 g and 0.22 ± 0.04, respectively. Shrimp treated with normal aeration showed significantly lower weight (12.13 ± 0.13 g) and ADG (0.13 ± 0.00) compared with the control group. FCR was 1.55 ± 0.04 in the treatment group and 2.51 ± 0.09 in the control group. Notably, the shrimp molting count was 1.55-fold higher in the supersaturated DO treatment than in the supersaturated DO treatment. The expression of growth-related genes, such as alpha-amylase, cathepsin L, and chitotriosidase, was 1.40-, 1.48-, and 1.35-fold higher, respectively, after supersaturated DO treatment. Moreover, the treatment increased the expression of anti-lipopolysaccharide factor, crustin, penaeidin3, and heat shock protein 70 genes by 1.23-, 2.07-, 4.20-, and 679.04-fold, respectively, compared to the controls. Supersaturated DO increased growth and ADG production and decreased FCR. Furthermore, enhanced immune-related gene expression by supersaturated DO may improve shrimp health and reduce disease risk during cultivation.

Flotation of Chromium Ions from Simulated Wastewater Using Air Microbubbles

A microbubble air flotation technique was used to remove chromium ions from simulated wastewater (e.g. water used for electroplating, textiles, paints and pigments, and tanning leather). Experimental parameters were investigated to analyze the flotation process and determine the removal efficiency. These parameters included the location of the sampling port from the bottom of the column, where the diffuser is located to the top of flotation column (30, 60, and 90 cm), the type of surfactant (anionic, SDS, or cationic, CTAB) and its concentration (5, 10, 15, and 20 mg/L), the pH of the initial solution (3, 5, 7, 9, and 11), the initial contaminant concentration (10, 20, 30, and 40 mg/L), the gas flow rate (0.1, 0.2, 0.3, and 0.5 L/min), and the contact time (5, 10, 15, 20, 25, 30, and 35 min). The experimental results revealed that the highest removal efficiency (95%) was achieved in 20 min with a pH of 7, a flow rate of air 0.5 L/min, an SDS surfactant concentration of 15 mg/L, and a pollutant concentration of 30 mg/L at a sampling port height of 30 cm. The use of microbubbles in comparison to normal bubbles, resulted in a 56% improvement of the removal efficiency. The flotation process follows a first-order kinetics.

Reagentless reduction of hydrogen carbonate-calcium hardness of water: equilibrium states and kinetics

The equilibrium states and kinetics of changes in the concentrations of carbonate system components in water with different calcium hardness are analyzed and the possibility of reducing this indicator by an environmentally friendly method, aeration, is evaluated. Changes in the concentrations of dissolved carbon dioxide, calcium ions, hydrogen ions (pH), bicarbonate and carbonate ions in water depending on the partial pressure of carbon dioxide in soil and atmospheric air and the kinetics of reducing the bicarbonate-calcium hardness of water during its natural and forced aeration were traced. It is shown that water purification by a stream of atmospheric air microbubbles with an average radius of 50 m and a flow rate of 10 l/min can reduce the hydrogen carbonate-calcium hardness from 8 mg-eq/l to 1 mg-eq/l in 100 liters of water in 20 minutes. In the paradigm of "green chemistry", this method is more rational, environmentally friendly, and economical than ion exchange or reverse osmosis, which are currently practiced to reduce hardness in decentralized water supply systems.

Микропузырьковая безреагентная гидрофобизация поверхности угля

The paper describes methodological features of coal surface hydrophobization the using a microbubble gas-liquid medium to intensify the process of flotation concentration of coal. Air microbubbles were generated using decompression of liquid saturated under air pressure. The influence of water saturation pressure with gas on the size of the bubbles and their stability over time has been established. It is shown that addition of microbubbles leads to formation of an intermediate hydrophobic air layer on the surface of coal, which is the basis for catching bubbles of the flotation size. The results of coking coals flotation using a microbubble gas-liquid mixture are presented. By means of the method of differential particle size analysis, the preferred flotation of fine coal particles < 50 microns in size by micro-bubbles of air was established. It was found that for low-ash coals, the efficiency of reagentless microbubble flotation can be comparable with the results of concentration using traditional petrochemical reagents. In the reagent mode, the micro-bubbles are attached to the oil-hydrophobized surface of small particles with the formation of carbon-air complexes.

Iatrogenic Air Embolisms During Endovascular Interventions: Impact of Origin and Number of Air Bubbles on Cerebral Infarctions.

Cerebral infarctions caused by air embolisms (AE) are afeared risk in endovascular procedures; however, the relevance and pathophysiology of these AEs is still largely unclear. The objective of this study was to investigate the impact of the origin (aorta, carotid artery or right atrium) and number of air bubbles on cerebral infarctions in an experimental in vivo model. In 20rats 1200 or 2000 highly calibrated micro air bubbles (MAB) with asize of 85 µm were injected at the aortic valve (group Ao), into the common carotid artery (group CA) or into the right atrium (group RA) using amicrocatheter via atransfemoral access, resembling endovascular interventions in humans. Magnetic resonance imaging (MRI) using a9.4T system was performed 1 h after MAB injection followed by finalization. The number (5.5 vs. 5.5 median) and embolic patterns of infarctions did not significantly differ between groups Ao and CA. The number of infarctions were significantly higher comparing 2000 and 1200 injected MABs (6 vs. 4.5; p < 0.001). The infarctions were significantly larger for group CA (median infarction volume: 0.41 mm3 vs. 0.19 mm3; p < 0.001). In group RA and in the control group no infarctions were detected. Histopathological analyses showed early signs of ischemic stroke. Iatrogenic AEs originating at the ascending aorta cause asimilar number and pattern of cerebral infarctions compared to those with origin at the carotid artery. These findings underline the relevance and potential risk of AE occurring during endovascular interventions at the aortic valve and ascending aorta.

Reproducible reformation of a bilayer lipid membrane using microair bubbles

AbstractPlanar bilayer lipid membranes (BLMs) are widely used as models for cell membranes in various applications, including drug discovery and biosensors. However, the nanometer‐thick bilayer structure, assembled through hydrophobic interactions of amphiphilic lipid molecules, makes such BLM systems mechanically and electrically unstable. In this study, we developed a device to reform BLMs using a microair bubble. The device consists of a double well divided by a separator with a microaperture, where a BLM was formed by infusing a lipid‐dispersed solvent and an aqueous droplet into each well in series. When the BLM ruptured, a microair bubble was injected from the bottom of the well to split the merged aqueous droplet at the microaperture, which resulted in the reformation of two lipid monolayers on the split droplets. By bringing the two droplets into contact, a new BLM was formed. An angled step design was introduced in the BLM device to guide the bubble and ensure the splitting of the merged droplet. We also elucidated the optimal bubble inflow rate for the reproducible BLM reformation. Using a 4‐channel parallel device, we demonstrated the individual and repeatable reformation of BLMs. Our approach will aid the development of automated and arrayed BLM systems.

Ammonia Air Stripping from Different Livestock Effluents Prior to and after Anaerobic Digestion

Livestock digestate provides nutrients and organic matter to the soil while increasing agricultural sustainability. Nevertheless, nitrogen (N) losses due to the nutrient surplus in regions characterized by intensive animal farming activities still represent an unsolved issue. For this purpose, digestate needs proper treatment and management to avoid N losses in the environment. In the livestock farming context, anaerobic digestion (AD) can be accompanied by an ammonia stripping (AS) process for N recovery. This paper aims to investigate the feasibility AS prior to and after AD of the manure, focusing on two different livestock farms, representative of dairy cattle and pig breeding in southern Italy. AS was performed at a lab scale by injecting microbubbles of air, which allowed the pH to increase, and thus the removal of ammonia. The results show that treating a dairy raw slurry with high intermediate alkalinity (IA) (6707 mg CaCO3 L−1) with AS may not be convenient in terms of total ammonia nitrogen (TAN) reduction. As a matter of fact, the loss of buffering capacity during the stripping process resulted in a pH never exceeding the value of 9, which could not promote free ammonia volatilization, whereas integrating AD with AS allowed us to obtain a 34% higher TAN reduction under the same stripping conditions at a temperature (T) of 38 °C and a gas-to-liquid ratio (G/L) of 1:1. Therefore, the AS removal efficiency strongly depends on the characteristics (mainly IA) of the treated matrix. High IA values suggest a possible high concentration of volatile fatty acids, which hinders pH increases and, thus, enables ammonia stripping. Despite the initial matrix origin, a low IA compared to the total alkalinity (TA) (&lt;20% of TA) ensures a greater ammonia removal efficiency, which could be similar between digestate and raw manure in the same operative process conditions. Nonetheless, the amount of ammonia stripped is related to the initial TAN concentration of the specific matrix.

Fabrication of Multiphase Liquid Metal Composites Containing Gas and Solid Fillers: From Pastes to Foams

Gallium-based liquid metals (LMs) are suitable for many potential applications due to their unique combination of metallic and liquid properties. However, due to their high surface tension and low viscosity, LMs are challenging to apply to substrates in useful shapes, such as dots, wires, and films. These issues are mitigated by mixing the LMs in air with other materials, such as mixing with solid particles to form LM solid pastes or mixing with gases to form LM foams. Underlying these deceivingly simple mixing processes are complex and highly intertwined microscale mechanisms. Air microbubbles are inevitably incorporated while making LM pastes, making them partly foams. On the other hand, for foaming of the LM to occur, a critical volume content of solid particles must be internalized first. Consequently, both LM pastes and foams are multiphase composites containing solid and fluid microcomponents. Here, we systematically study the impact of the mixing procedure, solid particle size, and volume fraction (SiO2) on the air content of the multiphase LM composites. We demonstrate that decreasing the particle size and increasing their volume fraction substantially decrease the composite density (i.e., increases air entrapment). The foaming process can also be enhanced with the use of high-speed mechanical mixing, although leading to the formation of a more disordered internal structure. In contrast, manual mixing with larger microparticles can promote the formation of more paste-like composites with minimal air content. We explain the microscopic mechanisms underlying these trends by correlating macroscopic measurements with cross-sectional electron microscopy of the internal structure.

Multi-modality imaging assessment of microbubbles and cerebral emboli in left ventricular pulsed field ablation.

Pulsed field ablation (PFA) may have a superior safety profile compared to other technologies, but it has the potential to cause gaseous microbubbles (MB), which may be associated with cerebral emboli. Limited relative safety data has been published regarding PFA in the left ventricle (LV). Healthy and chronic myocardial infarction (MI) swine underwent PFA (monopolar, biphasic, 25 Amps) in the LV using an irrigated focal catheter under intra-cardiac echocardiography (ICE) guidance for MB monitoring. Two control swine received air MBs through the lumen of the ablation catheter. Swine underwent brain MRI before and after PFA (or control air MB injection). Gross pathology and histology of brains with abnormal MRI findings were performed. Four healthy and 5 chronic MI swine underwent 124 left ventricular PFA applications. No PFA-related MB formation was noted on ICE. Both control swine developed multiple acute emboli in the thalamus and caudate on DWI, ADC, and FLAIR brain MRI images in response to air MB injection. Of the 9 PFA swine, there were no abnormalities on ADC or FLAIR images. There was one hyperintense focus in the left putamen on the DWI trace image, but the absence of ADC or FLAIR affirmation suggested it was artifact. Gross pathology and histopathology of this region did not detect any abnormalities. Focal monopolar biphasic PFA of both healthy and chronically infarcted left ventricular myocardium does not generate any MB or cerebral emboli observable on ICE and brain MRI.

Transient formation theory of air-microbubble oil and testing its oil-spraying mechanism

In oil–air lubrication systems, large numbers of air microbubbles are often included in the oil phase. However, the principles of microbubble formation in oil–air annular flow and their influencing factors remain uncertain, and previous conclusions regarding the effects of microbubbles on the viscosity properties of the lubricant oil are inconsistent. Thus, there is an urgent need for experimental verification. In this paper, a transient force balance model is established and used to ascertain the formation of air microbubbles in oil (AB-oil) for an oil–air annular flow. The stability of these microbubbles is analyzed using the Rayleigh–Plesset equation. Theoretical analysis shows that the microbubble radius is the key factor affecting the force balance and stability of microbubbles in oil. Experiments are conducted based on this theoretical analysis, and the void fraction of AB-oil is determined through image analysis to verify the principles and influencing factors of AB-oil formation in oil–air lubrication systems. The viscosity properties of AB-oil are then tested using a rheometer. The experimental results indicate that the formation of AB-oil is affected by oil viscosity, pipe range, oil feeding rate, and air pressure. AB-oil exhibit different viscosity properties at different shear rates and void fractions. Finally, the relationship between the void fraction and viscosity at different shear rates is determined from the experimental data. The outcomes of this research provide insights into the characteristics of oil–air lubrication systems for high-speed machine tool spindles.

Experimental Inactivation of Microalgae in Marine Ballast Water by Microbubbles Generated through Hydrodynamic Cavitation

This paper presents a novel approach to microbubble technology for the treatment of aquatic invasive organisms in ship ballast water. The microbubbles are produced by hydrodynamic cavitation with a sudden and dramatic water pressure drop. The air and ozone microbubbles, respectively, verified the bioavailability of ship ballast water treatment using marine microalgae as an indicator. Besides the effects of an ozone injection dose, the morphological changes of cells and the effluent toxicity were investigated. Compared with the ozone microbubble treatment, the inactivation of marine microalgae by air microbubbles required a long treatment time. In the storage experiment, it was found that air microbubbles did not inhibit the growth of microalgae cells, and that the injection of active matter such as ozone was still necessary to ensure the validity of biological invasion. However, even with very low doses of ozone, the inactivation effect of ozone microbubbles was still very evident. Overall, it helps to minimize the use of active matter to reduce the toxicity of treated water, and this has the capability to develop into an environmentally acceptable and practical ballast water treatment technology.

Long-Term Retention Microbubbles with Three-Layer Structure for Floating Intravesical Instillation Delivery.

Intravesical instillation is an effective treatment for bladder cancer. However, clinical anticancer agents always suffer rapid excretion by periodic urination, leading to low therapeutic efficacy. Prolonging the retention time of drugs in the bladder is the key challenge for intravesical instillation treatment. Herein, a facile and powerful surface cross-linking-freeze drying strategy is proposed to generate ultra-stable albumin bovine air microbubbles (BSA-MBs) that can float and adhere to the bladder wall to overcome the excretion of urination and exhibit a remarkable property of long-term retention in the bladder. More noteworthy, BSA-MBs are endowed with a specific three-layer structure, namely, the outer membrane, middle drug loading layer and inner air core, which makes them have a low density to easily float and possess a high drug loading capacity. Based on their unique superiorities, the therapeutic potential of doxorubicin (DOX)-loaded BSA-MBs (DOX-MBs) is exemplified by intravesical instillation for bladder cancer. After injection into the bladder, DOX-MBs can remain in the bladder for a long time and sustain the release of DOX in urine, exhibiting potent anticancer efficacy. Consequently, the prolonged retention of BSA-MBs in the bladder renders them as an effective floating drug delivery system for intravesical instillation therapy.

Scaling mitigation in direct contact membrane distillation using air microbubbles

Membrane distillation (MD) is a promising process for high-salinity waters. However, water recovery in MD treatments of these feed waters is often limited by their high scaling potential, which results in the need for extensive pre-treatment or the use of antiscalants for scaling control. In this study, we show the potential of using air microbubbles (MB) for scaling mitigation in MD. Addition of MB in the feed was found to reduce membrane scaling, which was confirmed by electron microscopy and quantification of salt deposits on the membrane. In the presence of MB, scaling-induced flux decline was observed at a critical concentration factor of 2.70, compared to 1.97 in the absence of MBs. Scaling mitigation by MB was found to be dependent on the MD operating conditions, with better performance at lower feed temperatures (50 °C) and flow rate (0.4 L/min). Continuous MB injection was more effective in preventing scaling than a periodic on/off MB regime, which emphasized that MB mitigate scaling by preventing salt crystal formation on the membrane instead of dislodging the scaling layer formed on the surface. These results highlight the potential of air MB as a chemical-free scaling control strategy for MD treatment of high scaling potential waters.

Different effects of air microembolism through patent foramen ovale in patients with migraine: A quantitative electroencephalogram case series.

Literature suggests an association between patent foramen ovale (PFO) and migraine, mostly migraine with aura (MA). Previous data suggest that air microembolism through PFO can lead to bioelectrical abnormalities detectable at electroencephalogram (EEG) in patients with MA, thus suggesting a pathophysiological mechanism for the MA-PFO association. However, those data lack replication. Patients with MA or migraine without aura (MO) and large PFO underwent a 19-channel EEG recording before and after injection of air microbubbles. We compared EEG power before and after microbubble injection for each electrode location, for each frequency band (theta: 5-7 Hz; alpha: 8-12 Hz; beta: 13-30 Hz; lower gamma: 31-45 Hz), and for total global power (the average of EEG power at each location and frequency band). We included 10 patients, four with MA and six with MO; six patients had medium-to-high migraine frequency (four or more monthly migraine days), while four had low frequency (one monthly migraine day). EEG power changes after air microembolism varied across patients. Considering the overall group, total global EEG power did not change; however, EEG power in the higher frequency ranges (beta and lower gamma) increased in patients with MA. We did not replicate the effects of air microembolism previously reported in patients with migraine. Aura status, migraine frequency, and medications might influence patients' response to microembolism. More refined EEG measurements are needed to clarify the dynamic role of PFO on migraine occurrence.