Gas Microbubbles Research Articles

Sustained Regeneration of Hydrogen Peroxide at the Water-Gas Interface of Electrogenerated Microbubbles on an Electrode Surface.

Microbubbles, inside-out microdroplets, act as extraordinary microreactors to facilitate thermodynamically unfavorable reactions in bulk solutions of water. We explored the formation of hydrogen peroxide (H2O2) and its sustained regeneration at the interface of water-gas microbubbles. For this purpose, the chemiluminescence of luminol was recorded by a digital camera to map the intensity of blue light emission over the time of about 20 min. The formation and regeneration of hydrogen peroxide were also monitored by fluorescence microscopic imaging of a hydrogen peroxide probe. The microscopic images consistently show a stable glow around the microbubbles over time during which the formed hydrogen peroxide diffuses into the bulk solution. This observation confirms that the concentration of H2O2 at the interface is 30 times higher than that in the water solution bulk after several minutes, which can be attributed to its regeneration at the water-gas interface. These findings increase our understanding of why the chemistries of gas microbubbles in water and water microdroplets surrounded by gas are so distinct from those of bulk-phase water.

Ultrasound-compatible 3D-printed Franz diffusion system for sonophoresis with microbubbles

Sonophoresis is a topical drug delivery approach that utilises ultrasound as a physical stimulus to enhance permeation of active pharmaceutical ingredients through the skin. Only limited research has however been conducted to evaluate the potential of ultrasound-responsive drug carriers, such as gas microbubbles, in sonophoresis. Franz diffusion cells have been extensively used for measuring drug permeation in vitro; however, traditional systems lack compatibility with ultrasound and only limited characterisation of their acoustical behaviour has been carried out in previous research. To overcome this limitation, we designed and manufactured a novel Franz cell donor compartment coupled with a conventional glass receptor, and performed a functional characterisation of the assembly for application in sonophoresis with ultrasound-responsive agents (specifically imiquimod-loaded gas microbubbles). The donor was fabricated using a photoreactive resin via 3D printing and was designed to enable integration with a therapeutically relevant ultrasound source. The assembly was capable of effectively retaining liquids during prolonged incubation and the absorption of imiquimod onto the 3D-printed material was comparable to the one of glass. Moreover, a predictable ultrasound field could be generated at a target surface without any significant spatial distortion. Finally, we demonstrated applicability of the developed assembly in sonophoresis experiments with StratM®, wherein ultrasound stimulation in the presence of microbubbles resulted in significantly enhanced drug permeation through and partitioning within the membrane (2.96 ± 0.25 μg and 3.84 ± 0.39 μg) compared to passive diffusion alone (1.74 ± 0.29 μg and 2.29 ± 0.32 μg), over 24 h.

Contrast-Enhanced Ultrasound (CEUS) Evaluation of Canine Prostatic Hyperplasia before and after Osaterone Acetate Therapy: Preliminary Results.

The prostate is the only sexual gland of the male dog, and dihydrotestosterone (DHT) regulates its growth. In intact dogs, constant DHT stimulation results in benign prostatic hyperplasia (BPH) that can be treated with osaterone acetate (OSA). This study describes the effects of OSA treatment, detected by contrast-enhanced ultrasonography (CEUS), highlighting prostatic vascularization with a contrast agent composed of gas microbubbles. Fifteen dogs (2-8 years) of different sizes and breeds (4-30 kg) diagnosed with BPH are involved in the study. Before treatment (D0), CPSE is measured (294.05 ± 115.97 ng/mL), and a B-mode ultrasound is performed (Vratio = 2.80 ± 1.85), confirming BPH. CEUS highlights the length of the wash-in (11.93 ± 2.08 s) and wash-out (42.20 ± 6.99 s) phases of the contrast agent in the prostate and the presence of cysts and parenchymal alteration. Dogs are treated with OSA (0.5 mg/kg for 7 days) and reassessed after 21 days (D1): CPSE and prostate volume are significantly (p < 0.001) reduced. The length of the wash-in (14.73 ± 2.54 s) and wash-out (51.13 ± 6.03 s) phases are significantly (p < 0.001) increased. The results confirm the effectiveness of the treatment, particularly the reduction in prostatic perfusion, confirmed by the increase in diffusion times of the contrast. Although preliminary, these findings are promising for the use of CEUS in monitoring dogs with BPH.

Ethanologenic fermentation by Parageobacillus thermoglucosidasius with continuous hot microbubble gas-stripping

The increased use of biofuels in place of fossil fuels is one strategy to support the transition to net-zero carbon emissions, particularly in transport applications. However, expansion of the use of 1st generation crops as feedstocks is unsustainable due to the conflict with food use. The use of the lignocellulosic fractions from plants and/or co-products from food production including food wastes could satisfy the demand for biofuels without affecting the use of land and the availability of food, but organisms which can readily ferment all the carbohydrates present in these feedstocks often suffer from more severe bioethanol inhibition effects than yeast. This paper demonstrates the potential of hot gas microbubbles to strip ethanol from a thermophilic fermentation process using Parageobacillus thermoglucosidasius TM333, thereby reducing product inhibition and allowing production to continue beyond the nominal toxic ethanol concentrations of ≤ 2% v/v. Using an experimental rig in which cells were grown in fed-batch cultures on sugars derived from waste bread, and the broth continuously cycled through a purpose-built microbubble stripping unit, it was shown that non/low-inhibitory dissolved ethanol concentrations could be maintained throughout, despite reaching productivities equivalent to 4.7% v/v dissolved ethanol. Ethanol recovered in the condensate was at a concentration appropriate for dewatering to be cost effective and not prohibitively energy intensive. This suggests that hot microbubble stripping could be a valuable technology for the continuous production of bioethanol from fermentation processes which suffer from product inhibition before reaching economically viable titres, which is typical of most thermophilic ethanologenic bacteria.

Modeling high‐intensity ultrasound to enhance shrimp (Penaeus vannamei) brining without compromising crucial purchase attributes

AbstractTraditional brining methods, such as immersion, are time‐consuming and affect the quality of the food product. Thus, high‐intensity ultrasound (HIUS) has been studied as a brining‐assisted non‐thermal technology. However, this approach to shrimp and the assessment of the individual and combined effects of HIUS parameters, for example, time (t), power (P), and salt concentration (SC), is a knowledge gap. This study aimed to model HIUS‐brining for improving salt diffusion and water properties while maintaining relevant purchase attributes closer to fresh shrimp (Penaeus vannamei) quality. Our findings suggest HIUS improves salt diffusion, decreasing Aw and enhancing water‐holding capacity (WHC). Instead, the increased P reduced hardness and enhanced whiteness. HIUS‐brining (22.02 min/267.89 W/6.68%) maximized Na+ (2.58%) and WHC (86.31%), minimized Aw (.92), and retained hardness (71.07 N) and whiteness (55.14) close to freshness. Therefore, it is possible to employ HIUS in the shrimp brine to improve salt diffusion without damaging physicochemical attributes.Practical applicationsDespite traditional methods for seafood brining being considered effective, they are time‐consuming, taking hours to reach the desirable moisture value. High‐intensity ultrasound (HIUS) is an emerging non‐thermal technology recently explored as a brining technology for animal‐origin food, such as meat. The cavitation induced by HIUS generates gas microbubbles. The implosion increases local temperature and pressure and generates microjets, facilitating the mass transfer (sponge effect) and salt diffusion in the muscle tissues. However, the cavitation mechanism also releases free radicals, resulting in physicochemical alterations during processing, such as damage to color and texture. The present research contributes to providing a better understanding of the application and optimization of HIUS to accelerate the shrimp brining process. The findings herein are promising for the industrial utilization of sonication to obtain brined products without damaging the quality attributes of shrimp.

Applications of Nanotechnology in the Field of Cardiology.

Cardiovascular diseases (CVDs) are aleading cause of death globally, demanding innovative therapeutic strategies. Nanoformulations, including nanoparticles, address challenges in drug delivery, stem cell therapy, imaging, and gene delivery. Nanoparticles enhance drug solubility, bioavailability, and targeted delivery, with gas microbubbles, liposomal preparations, and paramagnetic nanoparticles showing potential in treating atherosclerosis and reducing systemic side effects. In stem cell therapy, nanoparticles improve cell culture, utilizing three-dimensional nanofiber scaffolds and enhancing cardiomyocyte growth. Gold nanoparticles and poly(lactic-co-glycolic acid) (PLGA)-derived microparticles promote stem cell survival. Stem cell imaging utilizes direct labeling with nanoparticles for magnetic resonance imaging (MRI), while optical tracking employs dye-conjugated nanoparticles. In gene delivery, polymeric nanoparticles like polyethylenimine (PEI) and dendrimers, graphene-based carriers, and chitosan nanoparticles offer alternatives to virus-mediated gene transfer. The potential of magnetic nanoparticles in gene therapy is explored, particularly in hepatocellular carcinoma. Overall, nanoparticles have transformative potential in cardiovascular disease management, with ongoing research poised to enhance clinical outcomes.

Pore-scale visualization of hydrate dissociation and mass transfer during depressurization using microfluidic experiments

Natural gas hydrate is a potential low-carbon energy resource. Extracting this resource efficiently remains a challenge, due to the intricacies involved in multiphase reactive transport during hydrate dissociation. This study employs microfluidic experimental techniques to observe pore-scale interactions during depressurization-induced hydrate dissociation, utilizing high-resolution spatial and temporal imagery. Supervised machine learning algorithms segmented these microscopic images, enabling the analysis of phase saturation changes and hydrate dissociation rates. The study identifies two distinct hydrate forms in microfluidic chips: hydrate films and crystals, each exhibiting unique dissociation characteristics. Hydrate films decomposed rapidly in response to pressure reductions below equilibrium with the dissociation rate of O(10−1 %/s) under stationary gas–water conditions. When considering gas–water migration, the gas encapsulated in the hydrate film will be displaced by water, leading to a reduced dissociation rate. The hydrate crystal dissociation is much slower with the dissociation rate of O(10−3 %/s) under stationary gas–water conditions compared to the hydrate film, hindered by mass transfer limitations. Gas-water migration can enhance crystal dissociation. The formation and expansion of gas microbubbles under depressurization accelerated hydrate dissociation within a confined temporal and spatial range, which was known as the self-promotion mechanisms. Significantly, depressurization-induced gas slug flow increases the dissociation rate by more than one order of magnitude, compared to that in stationary gas–water conditions. The depressurization process played a significant role, not only by facilitating thermodynamic feasibility for hydrate dissociation but also by inducing the critical gas slug flow. These results of the present study provide theoretical guidance for improving natural gas hydrate production efficiency.

Hydrophobin-Coated Perfluorocarbon Microbubbles with Strong Non-Linear Acoustic Response

Gas-filled microbubbles are well-established contrast agents for ultrasound imaging and widely studied as delivery systems for theranostics. Herein, we have demonstrated the promising potential of the hydrophobin HFBII—a fungal amphiphilic protein—in stabilizing microbubbles with various fluorinated core gases. A thorough screening of several experimental parameters was performed to find the optimized conditions regarding the preparation technique, type of core gas, HFBII initial concentration, and protein dissolution procedure. The best results were obtained by combining perfluorobutane (C4F10) gas with 1 mg/mL of aqueous HFBII, which afforded a total bubble concentration higher than 109 bubbles/mL, with long-term stability in solution (at least 3 h). Acoustic characterization of such microbubbles in the typical ultrasound frequency range used for diagnostic imaging showed the lower pressure resistance of HFBII microbubbles, if compared to conventional ones stabilized by phospholipid shells, but, at the same time, revealed strong non-linear behavior, with a significant harmonic response already at low acoustic pressures. These findings suggest the possibility of further improving the performance of HFBII-coated perfluorinated gas microbubbles, for instance by mixing the protein with other stabilizing agents, e.g., phospholipids, in order to tune the viscoelastic properties of the outer shell.

The effect of decafluorobutane lipid nanoemulsion concentration on oxygen scavenging via acoustic droplet vaporization

Acoustic droplet vaporization (ADV) is the phase transition of liquid droplets into gas microbubbles via ultrasound. Oxygen diffuses from the surrounding fluid into the microbubbles. This study determined the efficiency of oxygen scavenging using a lipid decafluorobutane (DFB) nanoemulsion. DFB nanoemulsions were prepared using high-shear pressure homogenization. Nanoemulsion size distributions and concentrations were measured (n = 10) using a Beckman Coulter Multisizer 4. Oxygen scavenging in 95% oxygenated water was measured in a flow phantom prior to introducing DFB nanoemulsion at concentrations of 0.05 × 10−4, 0.25 × 10−4, 0.5 × 10−4, 2.5 × 10−4, and 5 × 10−4 mL/mL and with ADV nucleated by an EkoSonic catheter driven with 47 W electrical power. The DFB nanoemulsion had a modal diameter of 920 ± 60 nm, polydispersity index (PDI) of 0.11 ± 0.03, and concentration of 3.11 × 10–2 ± 0.01 × 10–2 mL/mL. No statistical significant differences was detected in droplet size distribution metrics for at least 5 h at room temperature and 23 days at 4C. The baseline oxygen partial pressure (pO2) of the water was 553 ± 8 mmHg for all experiments. Peri-ADV pO2 dropped to 505 ± 16, 398 ± 44, 348 ± 11, 231 ± 27, 241 ± 7 mmHg for increasing concentration. A significant difference in pO2 was seen between thelowest and highest concentration (p = 0.0097). The computed ADV transition efficiency was highest at 0.25 × 10−4 mL/mL.

Hydrodynamics and mass transfer performance of microbubble flow in the bubble column with a contraction section

Bubble columns have many applications in the biochemical, petrochemical, and metallurgical industries. The gas-liquid system composed of microbubbles is characterized by significant phase interfacial area, high mass transfer efficiency, fast dissolution rate, strong adsorption capacity, and long self-sustaining time. This paper investigated the performance of pressurized dissolved gas microbubble generation (PDG) using a Venturi tube as the releaser using a plug-in online imaging instrument. The hydrodynamic and mass transfer characteristics of the microbubble flow generated by PDG in a bubbling column with a contraction section (BCS) were then investigated. One of the primary studies was the effect of the contraction section on the flow performance of the bubbles, the mass transfer performance, and the aeration efficiency of the PDG versus the throat inlet Venturi bubble generator (VBG). The results show that the initial bubble Sauter mean diameter is essentially constant with dissolved gas pressure, and the bubble size distribution(BSD) is similar. The bubble stream passing through the contraction section exhibits two different BSD at the center and side walls of the BCS outlet section. Microbubbles in the inlet section in the absence of external forces almost do not occur in bubble coalescence. The flow of bubbles in the contraction section is subject to a slight coalescence effect. The diameter of bubbles in the contraction section is mainly larger than 20 μm. In the contraction section, coalescence occurs mainly at the side wall. The way of occurrence is adsorption coalescence and collision coalescence. The bubbles move in a gradually confined space with a high degree of interference with each other's bubbles, and the liquid linear velocity acts as an ‘external force’ that benefits the flow of the bubbles out of the confined space. The standard aeration efficiency of PDG is 3–11 times higher than that of the VBG. At 0.3 MPa, the highest standard aeration efficiency for the PDG method was between 0.18 and 0.64 kgO2/kW∙h.

Nanobubble Contrast Enhanced Ultrasound Imaging: AReview.

Contrast-enhanced ultrasound is currently used worldwide with clinical indications in cardiology and radiology, and it continues to evolve and develop through innovative technological advancements. Clinically utilized contrast agents for ultrasound consist of hydrophobic gas microbubbles stabilized with a biocompatible shell. These agents are used commonly in echocardiography, with emerging applications in cancer diagnosis and therapy. Microbubbles are a blood pool agent with diameters between 1 and 10 μm, which precludes their use in other extravascular applications. To expand the potential use of contrast-enhanced ultrasound beyond intravascular applications, sub-micron agents, often called nanobubbles or ultra-fine bubbles, have recently emerged as a promising tool. Combining the principles of ultrasound imaging with the unique properties of nanobubbles (high concentration and small size), recent work has established their imaging potential. Contrast-enhanced ultrasound imaging using these agents continues to gain traction, with new studies establishing novel imaging applications. We highlight the recent achievements in nonlinear nanobubble contrast imaging, including a discussion on nanobubble formulations and their acoustic characteristics. Ultrasound imaging with nanobubbles is still in its early stages, but it has shown great potential in preclinical research and animal studies. We highlight unexplored areas of research where the capabilities of nanobubbles may offer new advantages. As technology advances, this technique may find applications in various areas of medicine, including cancer detection and treatment, cardiovascular imaging, and drug delivery.

A novel gas embolotherapy using microbubbles electrocoalescence for cancer treatment

Background and ObjectiveEmbolotherapy has been increasingly used to disrupt tumor growth. Despite its success in the occlusion of microvessels, it has drawbacks such as limited access to the target location, limited control of the blocker size, and inattention to the tumor characteristics, especially high interstitial fluid pressure. The present work introduces a novel numerical method of gas embolotherapy for cancer treatment through tumor vessel occlusion. MethodsThe gas microbubbles are generated from Levovist bolus injection into the tumor microvessel. The microbubble movement in the blood flow is innovatively controlled by an electric field applied to the tumor-feeding vessel. The interaction between the Levovist microbubbles and the electric field is resolved by developing a fully coupled model using the phase-field model, Carreau model for non-Newtonian blood, Navier-Stokes equations and Maxwell stress tensor. Additionally, the critical effect of high interstitial fluid pressure as a characteristic of solid tumors is included. ResultsThe findings of this study indicate that the rates of microbubble deformation and displacement increase with the applied potential intensity to the microvessel wall. Accordingly, the required time for a microbubble to join the upper microvessel wall reduces from 1.97ms to 22 μs with an increase of the electric potential from 3.5V to 12.5V. Additionally, an electric potential of 12.5V causes the microbubbles coalescence and formation of a gas column against the bloodstream. ConclusionsClinically, our novel embolization procedure can be considered a non-invasive targeted therapy, and under a controlled electric field, the blocker size can be precisely controlled. Also, the proposed method has the potential to be used as a gradual treatment in advanced cancers as tumors develop resistance and relapse.

New Alternative Techniques for Sentinel Lymph Node Biopsy.

Background and Objectives: This review paper highlights the key alternatives to the blue dye/radioisotope method of sentinel lymph node biopsy (SLNB). It analyses the research available on these alternative methods and their outcomes compared to the traditional techniques. Materials and Methods: This review focused on fifteen articles, of which five used indocyanine green (ICG) as a tracer, four used magnetic tracers, one used one-step nucleic acid amplification (OSNA) and Metasin (quantitative reverse transcriptase-polymerase chain reaction), one used the photosensitiser talaporfin sodium, one used sulphur hexafluoride gas microbubbles, one used CT-guided lymphography and two focused on general SLNB technique reviews. Results: Of the 15 papers analysed, the sentinel node detection rates were 69-100% for indocyanine green, 91.67-100% for magnetic tracers, 81% for talaporfin sodium, 9.3-55.2% for sulphur hexafluoride gas microbubbles, 90.5% for CTLG and 82.7-100% for one-step nucleic acid amplification. Conclusions: Indocyanine green fluorescence (ICG) and magnetic tracers have been proven non-inferior to traditional blue dye and isotope regarding SLNB localisation. Further studies are needed to investigate the use of these techniques in conjunction with each other and the possible use of language learning models. Dedicated studies are required to assess cost efficacy and longer-term outcomes.

High-speed optical observations of asymmetric pulsations of microbubbles released from tablet matrix

Abstract Microbubbles with a negligible shell are of utmost importance in the study of harmonic ultrasound contrast agents. The purpose of this study was to collect and quantify experimental pulsation footage of gas microbubbles released from tablet matrix under sonication. Radii were measured as a function of time of 50 microbubbles that had been released from tablet matrix and were subjected to 3-cycle pulses of 1-MHz ultrasound with a 0.3-MPa peak-negative pressure. The size distribution was measured, as well as pre- and postsonication radii. The experimental footage showed proof of asymmetric buckling, but also of excursion-only behaviour. The former phenomenon has been attributed to a surplus of material accumulated on the microbubble-liquid interfaces, whilst the latter phenomenon has been associated with the presence of incompressible material inside the microbubbles. The postsonication resting radii of 41 microbubbles had become less compared to the corresponding pre-sonication radii. The opposite effect was observed with eight microbubbles in the same size range. This feasibility study confirmed that the gas microbubbles released from tablet matrix may pulsate asymmetrically. Thus, they might be suitable tracers for harmonic imaging.

Residue-free and nondestructive separation of transparent adhesive thin films using the interfacial coating of thermo-responsive nanocapsules

The effective separation of flexible optoelectronic panels bonded with transparent adhesive films is an innovative technology that enables the reuse of expensive devices, reducing manufacturing costs in multilayered flexible displays. Herein, we present an effective, facile strategy for heat-triggered detachment of adhesive thin films with high optical transparency by interfacial coating with thermo-responsive nanocapsules. These temperature-sensitive nanocapsules, comprising reactive benzenesulfonyl hydrazide cores and polyacrylonitrile-poly(methyl methacrylate) copolymer shells, were simply prepared through a one-pot synthesis using surfactant-free emulsion polymerization. The synthesized nanocapsules were mixed with UV-curable resins and applied as a thin interfacial layer on the substrate through blade coating and UV curing, producing a transparent, uniform nanocapsule layer of 10 μm with extensive coverage. A transparent double-layered adhesive film was achieved by stacking optically clear adhesive film on the interfacial nanocapsule layer. Compared with pure transparent adhesive film, this double-layered adhesive film containing interfacial nanocapsule layer yields a remarkable optical transparency of 99.1 % and high initial adhesion strength of 98.2 %. Furthermore, a short-time heat treatment at 100 °C produces numerous gas microbubbles in the interfacial region between the substrate and optical thin film, facilitating their clean and spontaneous detachment with an outstanding desorption efficiency of 78.7 %. Our separation approach will be helpful for providing a promising way to dismantle polymer thin films without surface damage in wide industries from semiconductor packaging to flexible devices.

Physical Characterization to Improve Scalability and Potential of Anesthetic-Loaded Nanodroplets.

Drug-loaded perfluorocarbon nanodroplets (NDs) can be activated non-invasively by focused ultrasound (FUS) and allow for precise drug-delivery. Anesthetic-loaded NDs and transcranial FUS have previously achieved targeted neuromodulation. To assess the clinical potential of anesthetic-loaded NDs, in depth physical characterization and investigation of storage strategies and triggered-activation is necessary. Pentobarbital-loaded decafluorobutane nanodroplets (PBNDs) with a Definity-derived lipid shell (237 nm; 4.08 × 109 particles/mL) were fabricated and assessed. Change in droplet stability, concentration, and drug-release efficacy were tested for PBNDs frozen at -80 °C over 4 weeks. PBND diameter and the polydispersity index of thawed droplets remained consistent up to 14 days frozen. Cryo-TEM images revealed NDs begin to lose circularity at 7 days, and by 14 days, perfluorocarbon dissolution and lipid fragmentation occurred. The level of acoustic response and drug release decreases through prolonged storage. PBNDs showed no hemolytic activity at clinically relevant concentrations and conditions. At increasing sonication pressures, liquid PBNDs vaporized into gas microbubbles, and acoustic activity at the second harmonic frequency (2 f0) peaked at lower pressures than the subharmonic frequency (1/2 f0). Definity-based PBNDs have been thoroughly characterized, cryo-TEM has been shown to be suitable to image the internal structure of volatile NDs, and PBNDs can be reliably stored at -80 °C for future use up to 7 days without significant degradation, loss of acoustic response, or reduction in ultrasound-triggered drug release.

Recent Advances in Perfluorocarbon-Based Delivery Systems for Cancer Theranostics.

Hypoxia is a key impediment encountered in the treatment of most solid tumors, leading to immune escape and therapeutic resistance. Perfluorocarbons (PFCs) have a unique electrical structure and are characterized by a high solubility for gases. PFC-based oxygen carriers have been evaluated for their ability to deliver oxygen effectively to hypoxic tissues, and significant clinical translation has been demonstrated. And due to the unique acoustic activity, PFCs have been employed to stabilize the injection of gas microbubbles (MBs) as clinical ultrasonography contrast agents. In contrast, the ultrasound and photothermally activatable PFC phase-shift nanodroplets (P-SNDs) represent a novel alternative to ultrasound imaging and hypoxia improvement. The PFC-based oxygen carriers may be utilized to improve the efficacy of cancer treatments based on synergistic radiotherapy (RT), chemotherapy (CMT), and photodynamic therapy (PDT) to reshape the tumor microenvironment through synergistic immunotherapy (IMT) and to achieve precise tumor diagnosis using acoustic imaging. This review described the characteristics of PFCs to provide an update on the design of PFC delivery systems used for oxygen delivery and ultrasound imaging to facilitate the treatment and diagnosis of tumors. The objective was to contribute to overcoming the obstacles encountered during PFC research and provide the developing prospects.

Cascade capture, oxidization and inactivation for removing multi-species pollutants, antimicrobial resistance and pathogenicity from hospital wastewater

As reservoirs of pathogens, antimicrobial resistant microorganisms and a wide variety of pollutants, hospital wastewaters (HWWs) need to be effectively treated before discharge. This study employed the functionalized colloidal microbubble technology as one-step fast HWW treatment. Inorganic coagulant (monomeric Fe(III)-coagulant or polymeric Al(III)-coagulant) and ozone were used as surface-decorator and gaseous core modifier, respectively. The Fe(III)- or Al(III)-modified colloidal gas (or, ozone) microbubbles (Fe(III)-CCGMBs, Fe(III)-CCOMBs, Al(III)-CCGMBs and Al(III)-CCOMBs) were constructed. Within 3 min, CCOMBs decreased CODCr and fecal coliform concentration to the levels meeting the national discharge standard for medical organization. Regrowth of bacteria was inhibited and biodegradability of organics was increased after the simultaneous oxidation and cell-inactivation process. The metagenomics analysis further reveals that Al(III)-CCOMBs performed best in capturing the virulence genes, antibiotic resistance genes and their potential hosts. The horizontal transfer of those harmful genes could be effectively hampered thanks to the removal of mobile genetic elements. Interestingly, the virulence factors of adherence, micronutrient uptake/acquisition and phase invasion could facilitate the interface-dominated capture. Featured as cascade processes of capture, oxidation and inactivation in the one-step operation, the robust Al(III)-CCOMB treatment is recommended for the HWW treatment and the protection of downstream aquatic environment.

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.

Implementing bubbly mercury material model (R-P model) in the pulse simulation to predict strain on the Spallation Neutron Source target vessel with gas injection

The Spallation Neutron Source (SNS) creates neutrons by striking a liquid mercury target with short pulses of high-energy protons. SNS targets have been operated with helium microbubble gas injection into portions of the flowing mercury since 2017. The measurements during in situ testing showed that the strain response of the stainless steel target vessel significantly decreased with gas injection. Strain reductions ranged from 40% to 75% for targets operating with gas-injection rates between 2 and 3 standard liters per minute. These strain reductions have allowed SNS to operate reliably at 1.4 MW over the last few years and are expected to significantly improve the fatigue life of the target vessel. The achieved mitigation of the pulse response and the associated cavitation damage with gas injection is a cornerstone of the upgrade basis to the redesigned mercury vessel for planned higher power operation.Existing methods can simulate the structural response of the target operated without gas injection. Developing simulation techniques that account for the benefits of gas injection adds a considerable challenge. A combined mercury/bubble material model based on the Rayleigh–Plesset equation was developed to improve simulation of the response of a structure containing liquid and gas by incorporating bubble growth volume feedback. This paper details the implementation of the mercury/bubble material model in the pulse simulation of an existing target design. The newly developed simulation technique combines the current no-gas mercury material model for no-gas regions and the bubbly mercury material model for the regions with gas bubbles. The results of the strain response simulation using the new techniques are promising. The challenges of the technique development are also discussed. For example, the bubble size distributions are crucial for the simulations but remain an area of active research.