Bubble Counts Research Articles

Impact of cold plasma-assisted Non-thermal deamidation and glycosylation on the construction of sugar derivative-zein conjugates for enhancing pickering foam stability: Technical principles and molecular interactions

There is an urgent need for stable, plant-based Pickering foams to address the growing consumer demand for sustainable, low-calorie, aerated sweet foods. This study employed a cold plasma-assisted deamidation and glycosylation (CPDG) approach to promote hydrophilic reassembly of zein, resulting in the formation of sugar derivative-zein conjugates. This was accomplished by coupling deamidated zein with polyhydroxy sugars including sucralose (Suc), maltitol (Mal), mannitol (Man), and stevioside (Ste). The research focused on elucidating the technical mechanisms of conjugate formation and the molecular interactions that enhance foam performance. The CPDG-treated conjugates demonstrated substantially increased foamability (140.00–223.33 %) and foam stability (28.57–105.07 %). Furthermore, microscopy (100 × magnification) revealed enhanced bubble counts (+13–15 bubbles) and interface layer thickness (+1.85–4.60 nm), along with a decrease in the drainage area (+8.47–20.52 %) for all conjugates, except Suc/ZN-CP. Particularly, the amphiphilic nature of Ste, characterized by multiple chiral centers, various hydroxyl groups, and a distinct carbonyl group, resulted in the highest covalent grafting degree (38.82 %), water solubility (0.28 mg/mL), foaming capacity (223.33 %), and foam stability (105.07 %) of ZN/Ste-CP after CPDG treatment. Regarding interaction forces, CPDG treatment enhanced both hydrogen bonding and covalent interactions in zein while diminishing electrostatic and hydrophobic forces. Confocal laser scanning microscopy validated that these changes resulted in a hydrophilic conformational shift of the conjugates, allowing Ste to coat micelle surfaces and form chain-like aggregates through viscous stretching, thereby facilitating favorable adsorption and unfolding at the air/water interface. The CPDG technology proved to be an effective and eco-friendly method for modifying the interface of zein, offering a valuable strategy for its application in highly flexible, stabilized Pickering foamed foods.

Roles of Wettability and Wickability on Enhanced Hydrogen Evolution Reactions.

Bubble dynamics significantly impact mass transfer and energy conversion in electrochemical gas evolution reactions. Micro-/nanostructured surfaces with extreme wettability have been employed as gas-evolving electrodes to promote bubble departure and decrease the bubble-induced overpotential. However, effects of the electrodes' wickability on the electrochemical reaction performances remain elusive. In this work, hydrogen evolution reaction (HER) performances are experimentally investigated using micropillar array electrodes with varying interpillar spacings, and effects of the electrodes' wettability, wickability as well as bubble adhesion are discussed. A deep learning-based object detection model was used to obtain bubble counts and bubble departure size distributions. We show that microstructures on the electrode have little effect on the total bubble counts and bubble size distribution characteristics at low current densities. At high current densities, however, micropillar array electrodes have much higher total bubble counts and smaller bubble departure sizes compared with the flat electrode. We also demonstrate that surface wettability is a critical factor influencing HER performances under low current densities, where bubbles exist in an isolated regime. Under high current densities, where bubbles are in an interacting regime, the wickability of the micropillar array electrodes emerges as a determining factor. This work elucidates the roles of surface wettability and wickability on enhancing electrochemical performances, providing guidelines for the optimal design of micro-/nanostructured electrodes in various gas evolution reactions.

Roller fluctuations of pre-aerated high-Froude-number hydraulic jumps

This work presents an experimental study of the fluctuating properties of hydraulic jump rollers for high-Froude-number and pre-aerated inflow conditions, to investigate the validity of empirical relationships in the literature that are derived typically from experiments for smaller Froude numbers and clear-water approach flows. The jump roller fluctuations are evaluated in terms of the dimensions of the roller surface profile, the fluctuation magnitudes and frequencies of the instantaneous jump toe positions and water elevations, including at the tailwater surface, and the formation frequency and advection velocity of internal vortices in the shear layer. The effects of pre-aeration are found primarily in the length-scale properties such as jump length and surface fluctuation magnitudes, while the time-scale properties such as characteristic frequencies of the unsteady motions are not affected. Extrapolation of existing quantitative prediction of jump roller dynamic properties to high-Froude-number flow conditions should be performed carefully. An assessment of the fluctuating bubble counts within fixed time intervals yields close frequencies between the bubble grouping motions in the shear layer and the jump toe and tailwater wave motions, thus implying possible correlations between the roller surface deformations and air entrainment.

Comparison of vapor bubble kinetics and cleaning efficacy of different root canal irrigation techniques in the apical area beyond the fractured instrument

Background/purposeIntracanal fractured instruments hamper adequate root canal disinfection. The aim of this study was to evaluate vapor bubble kinetics and cleaning efficacy of different irrigation techniques in the apical area beyond the fractured instrument. Materials and methodsSixty curved root canal models, in which a 3-mm fragment of a #20 K-file or a WaveOne Gold Primary (WOG) instrument was intentionally separated at 3 mm from the apical foramen, were irrigated with laser-activated irrigation with photon-induced photoacoustic streaming (LAI-PIPS; 20 mJ/15 Hz), laser-activated irrigation using an Er:YAG laser unit (LAI; 30 mJ/20 Hz), or ultrasonic-activated irrigation (UAI) for 5 s. Vapor bubble velocity and counts were analyzed using high-speed video imaging. To evaluate canal wall cleanliness, 40 canals of extracted human teeth with an intentionally separated 3-mm WOG fragment in the canal at 3 mm from the apical foramen were irrigated with LAI-PIPS, LAI, UAI or conventional syringe irrigation, using 17% EDTA (30 s, two cycles), saline (30 s), and 3% NaOCl (30 s, three cycles) as irrigants. Debris and smear layer on the apical canal wall beyond the fractured instrument were scored using scanning electron microscopy. ResultsLAI-PIPS and LAI demonstrated higher vapor bubble counts than UAI. The WOG fragment permitted higher bubble velocity and count than the K-file fragment. LAI-PIPS and LAI showed better debris and smear removal than the other techniques. ConclusionLAI and LAI-PIPS demonstrated higher vaporized bubble kinetics and better cleaning efficacy in the apical area, even in the presence of a fractured instrument.

Experimental study of molten bubble layer growth and bubble size distribution in post‐flame‐spread PMMA samples

AbstractAlthough thermoplastics possess many desirable traits as solidified materials, they are combustible and burn readily. Post burning samples of polymethylmethacrylate (PMMA) are the focus of this study. During flame spread, PMMA forms a bubble containing molten surface layer that influences the spread rate and the surface mass efflux. This study examines the formation and distribution of bubbles inside a PMMA sample that has previously been subjected to flame spread and then re‐hardened into its solid state. Experiments discussed herein were conducted in a Narrow Channel Apparatus (NCA), which reduces the influences of gravitation (buoyancy) on flame spread. Bubble sizes and counts were determined using digital image analysis (DIA). The burnt samples were analyzed by dividing sample images into eight equal area sections. Frequency distributions of bubble size (area) were compared. Distribution functions were fitted against the empirical probability density function (PDF) for the bubble size distribution. The log‐normal distribution predicts the bubble size distribution for all segments. The bubble distribution function can be used to describe physical processes inside the polymeric material as it undergoes thermal transformation by the spreading flame.

Improvements in chitosan-based slurry ice production and its application in precooling and storage of Pampus argenteus

The effects of microbubbles in chitosan-based slurry ice production were investigated, and the efficiency of chitosan-based slurry ice was evaluated for silver pomfret (Pampus argenteus) precooling and storage at 0 °C. Microbubbles generated though agitation accelerated slurry ice production by promoting ice nucleation and eliminating supercooling. Higher bubble counts improved freezing, but overly large bubbles reduced the performance. The rheological properties of chitosan solutions were also investigaed, and solutions with higher viscosity formed more bubbles. Experiments investigating precooling rates, microbial concentrations, pH, thiobarbituric-acid-reactive substances, and total volatile basic nitrogen all confirmed that chitosan-based slurry ice had higher performance than flake ice or conventional slurry ice. Chitosan-based slurry ice can be used for precooling in the fish industry to reduce energy consumption, accelerate precooling, reduce microbial growth, and improve shelf life.

Flow aeration by an offset aerator: Air entrainment, bubbly flow turbulence, and adaptive-window cross-correlation processing

Chute aerators are used to induce flow aeration to prevent cavitation damages to flood discharge structures. The aerated chute flows are traditionally studied in terms of the air concentration distributions and air entrainment rate, whereas further detailed characterization of the bubbly flow associated with the turbulence modification has been missing. Herein the air–water flow turbulence was studied experimentally for a simple offset aerator model in a sloping chute. Advanced interfacial turbulence analyses were applied to the air–water flow measurement results using a dual-tip phase-detection probe. The new adaptive-window cross-correlation approach was first applied to the turbulence intensity estimate in both regions upstream and downstream the impact point. The overall spatial distributions of basic air–water flow properties agreed favorably with literature, and highlighted different patterns of air–water flow development in different sections of the flow. The turbulence level of the bubbly flow, and the bubble-turbulence interactions, were quantitatively described with the interfacial turbulence intensity, correlation turbulent length scale, and some measures of the bubble clustering behaviors. The interfacial turbulence intensity was obtained in the same order of magnitude as the common water-phase turbulence intensity observations, except for the impact zone. The results revealed the shear flow development and turbulence dissipation in the bottom layer of the aerated chute flow, which affected the local average bubble counts, the relative motions of neighboring bubbles, the diffusive transport of bubbly eddy structures, and consequently the near-wall bubble distributions critical for the protection of chute surface from cavitation erosion.

Effect of cannulation site on emboli travel during cardiac surgery

BackgroundDuring cardiac surgery, micro-air emboli regularly enter the blood stream and can cause cognitive impairment or stroke. It is not clearly understood whether the most threatening air emboli are generated by the heart-lung machine (HLM) or by the blood-air contact when opening the heart. We performed an in vitro study to assess, for the two sources, air emboli distribution in the arterial tree, especially in the brain region, during cardiac surgery with different cannulation sites.MethodsA model of the arterial tree was 3D printed and included in a hydraulic circuit, divided such that flow going to the brain was separated from the rest of the circuit. Air micro-emboli were injected either in the HLM (“ECC Bubbles”) or in the mock left ventricle (“Heart Bubbles”) to simulate the two sources. Emboli distribution was measured with an ultrasonic bubble counter. Five repetitions were performed for each combination of injection site and cannulation site, where air bubble counts and volumes were recorded. Air bubbles were separated in three categories based on size.ResultsFor both injection sites, it was possible to identify statistically significant differences between cannulation sites. For ECC Bubbles, axillary cannulation led to a higher amount of air bubbles in the brain with medium-sized bubbles. For Heart Bubbles, aortic cannulation showed a significantly bigger embolic load in the brain with large bubbles.ConclusionsThese preliminary in vitro findings showed that air embolic load in the brain may be dependent on the cannulation site, which deserves further in vivo exploration.

Controlling mechanisms of burning rate enhancement while using Flame Refluxer technology during in situ burning of crude oil spills

ABSTRACTThe focus of this study is to quantify the controlling mechanisms, which increases the burning rate of a pool fire using a Flame RefluxerTM. Part of the Flame RefluxerTM, is exposed to the fire and is heated up transferring heat to the fuel pool layer to which it extends. This enhances the conventional heat transfer that occurs only through the pool surface by transferring the heat from a fire to an in-depth layer of the liquid. Both sensible heat and heat of vaporization are supplied at increased rates by the submerged material. As an additional important effect, nucleate boiling onsets at the surface of the inserted material that generates bubbles of fuel vapor. These bubbles are transported to the surface of the pool, where they burst and release the v0061por to the gas-phase. While doing so, additional processes such as formation of micron-sized droplets or small jets of liquid fuel from the break point occur. This phenomenon causes additional fuel in liquid phase transported to the gas-phase, where they vaporize, ignite and burn in heterogeneous mode. Therefore, the processes involved in FR occur in three steps; enhancement of heat transfer to the liquid causing nucleate boiling, formation of bubbles and their transport, and dynamics of bubble breakage at the pool surface causing transfer of liquid fuel in the form of tiny droplets or jets towards the gas-phase. This study analyzes the influence of bubbles on the burning behavior of a pool fire using a simple experiment involving burning ethanol as a fuel. Ethanol is used due to its transparency and hence bubble behavior is easily observable on the heater surface. A 5cm x 5cm glass enclosure constantly replenished with ethanol serves as the burning pool. A solid aluminum block (8.8 cm tall x 3.6 cm wide x 1.2 cm thick) is placed in the flame to act as the Flame RefluxerTM. Bubble counts and burning rate measurements indicate the influence of the bubbles on the overall burning rate of the liquid pool.

Foam bubble size is significantly influenced by sclerosant concentration for polidocanol but not sodium tetradecyl sulphate

To determine the effect of liquid gas fraction (LGF), sclerosant type and concentration, and filter use on foam bubble size and count. Sclerosant foam microstructure was investigated using light microscopy for a range of LGFs (1 + 2, 1 + 4 and 1 + 8), for both sodium tetradecyl sulphate (STS) and polidocanol (POL), at a range of concentrations (0.5-3%), with and without the addition of micro-filters. Foam was generated using a modified Tessari method and placed into wells for analysis by light microscopy. Foam microscopic morphology was photographically documented, and bubble diameters and counts were quantified. Spherical bubbles were observed at lower LGF and a trend towards polyhedral morphology was observed at the higher LGF of (1 + 8). The higher gas content in LGF led to larger but fewer bubbles. POL bubble diameters appeared to be more influenced by concentration than STS with smaller bubbles observed at higher concentrations of POL. The mean bubble diameters were slightly larger for STS than POL at the highest concentration of 3% but smaller at lower concentrations of 1% and 1.5%. LGF is the primary determinant of bubble diameter and count. In contrast to STS, POL concentration influences the foam bubble size with smaller bubbles generated at higher concentrations of POL and larger bubbles appearing at low concentrations of this agent.

Development of soy milk in the form of wet foam in the presences of whey protein concentrate and polysaccharides at different whipping temperatures: Study of physical, rheological and microstructural properties

The aim of current work was generation soy milk in the form of the wet foam and clarify the controlling factors of foamability and foam stability. Soy milk foam (SMF) was prepared with the help of whey protein concentrate (3 and 6% w/w) and hydrocolloids (xanthan, guar and locust bean gums (0.05 and 0.15% w/w) at different temperature (5, 40 and 75°C). The overrun of SMFs was not greatly impacted by increasing guar gum concentration from 0.05% to 0.15%, whereas foam stability was greatly enhanced. When 0.15% xanthan gum was added to the samples, a great decrease on drainage was observed but they showed the lowest overrun. Also, in general, SMFs produced at temperatures of 5 and 75°C showed the highest overrun and stability, respectively. To summarize the basic physical properties of foam data (overrun, and drainage), hierarchical clustering analysis was performed. Samples from different classes evaluated for surface tension, zeta potential, rheological behavior and bubble properties to find factors controlling the formation and stability of foams. It was observed that the SMFs exhibited viscoelastic properties. Results showed that foam stability was directly related to rheological parameters (consistency coefficient, static and dynamic yield stress, zero shear viscosity, storage modulus, loss modulus, complex modulus and complex viscosity) and, except one sample, showed a negative correlation with surface tension. Overrun showed a positive correlation with the bubble counts and a negative correlation with the average bubble diameter. But microstructure changes cannot necessarily represent foam stability. Also, zeta potential could not explain any differences in the foam properties.

Production-Logging Technologies Enhance Inflow Profiling in Deepwater Gulf of Mexico

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 196188, “Third-Generation Production-Logging Technologies Enhance Inflow Profiling in Deepwater Gulf of Mexico Reservoirs,” by Glenn Donovan, SPE, Sagar Kamath, and Elizabeth Tanis, SPE, Shell, et al., prepared for the 2019 SPE Annual Technology Conference and Exhibition, Calgary, 30 September–2 October. The paper has not been peer reviewed. This paper discusses the effectiveness of third-generation (Gen3) production-logging-tool (PLT) technology, which uses co-located digital sensors for simultaneous acquisition of flow data to provide the most accurate characterization of the flow condition at each depth surveyed. The resulting data allow for much-improved processing. The probabilistic interpretive model used in the processing has been updated to incorporate this and future developments in PLT architecture. Introduction The first generation of PLT provided a single, discrete measurement for each sensor along the tool assembly’s length, resulting in long tool assemblies and measurements taken at different points along the flow path. This approach had several drawbacks: long toolstrings, point sensors that only provided a measurement at a single point in the cross section of the flow, and measurements that were not acquired simultaneously at each depth logged. Second- generation PLTs represented an improvement because sensors were arranged as an array, enabling multiple measurements to be made at a single depth. However, the toolstrings were still long and not all were arranged optimally to capture data in the flow path. The Gen3 PLT is one-tenth the length of the first-generation versions and roughly one-third that of the shortest second-generation tools. Digitalization allows for direct measurement of flow conditions and rapid interpretation of results. In multiphase flow and deviated wells, co-locating sensors in a spatial geometry provides the optimal information with which to create a fully accurate picture of the downhole flow. Description of Gen3 PLT The PLT described in the paper exemplifies how miniaturization and digitalization are enabling transformational improvements over traditional systems in terms of efficiency and capability. The tool encompasses, within a 3-ft length, up to 24 sensors that collect multiple measurements of fluid properties and fluid movements in a wellbore. These include oil, gas, and water holdup and bubble count, fluid conductivity, phase velocities, pressure, temperature, inclination, rotation, and depth correlation, plus power and communication. The fluid characteristics are locally screened by an array of 8 to 16 tube-shaped probe sensors that are interchangeable, depending on the targeted measurements (Fig. 1). The tool relies on a refractive index needle-shaped probe with a triphasic sensor to identify and quantify the oil, gas, and water holdups and bubble counts at each point of the array. The geometric design of the sensitive tip, along with the optoelectronics of the sensor, are optimized to discriminate oil, water, and gas with high confidence, overcoming the fact that the refractive indexes of oil and water are close to each other.

Reduction of Cerebral Emboli: In vitro Study with a Novel Cerebral Embolic Protection Device.

AimTo assess the efficacy of the TriGUARD 3™, a novel cerebral embolic protection (CEP) device in reducing cerebral embolization by deflecting embolic debris away from the cerebral circulation using a quantitative in vitro model.Methods and ResultsThis in vitro study assessed the ability of a cerebral embolic protection device to deflect embolic debris, by measuring the percent of particles and air bubbles, 200 µm and 300 µm in size, from entering the cerebral circulation compared to unprotected controls. A 3D printed silicone model of the ascending aorta, the aortic arch with its three major cerebral arteries and the descending aorta was connected to a custom-made simulator that mimics physiological pulsatile flow patterns of the left ventricle. Comparative analyses were used to assess the efficacy of the cerebral embolic protection device to deflect particles and air bubbles away from the major cerebral arteries. The percent of particles and air bubbles entering the major cerebral arteries was significantly lower with cerebral embolic protection compared to unprotected controls (p<0.0001). Cerebral protection resulted in 97.4–100% reduction in air bubble counts, and 97.4–97.8% reduction in particle counts compared to unprotected controls.ConclusionThis in vitro study used simulated physiologic flow conditions in an aortic arch model to demonstrate >97% efficacy of the TriGUARD 3 CEP device, in reducing cerebral embolization of particulate and air bubbles of 200 µm to 300 µm in size.

A Novel Interpretation Approach for Production Logging

Production logging (PL) is the industry standard method to evaluate wells and reservoir performance. This paper introduces guidelines for PL interpretation. The recommended interpretation strategy depends on an intensive study of hundreds of production logging cases covering the commonly encountered interpretation challenges in the Gulf of Suez. This study has three main objectives: the first is selecting the best water-oil slippage model; the second is finding an alternative for spinner to quantify flow rate; and the third is selecting the best liquid-gas slippage model. There are also other challenges that the study finds solutions to understand and solve all of them. The study finds that temperature and bubble counts are good alternatives for spinner data. In addition, ABB-deviated and Artep models are the best water-oil and liquid-gas slippage models. [Received: September 29, 2019; Accepted: February 12, 2020]

Intra-pulmonary arteriovenous anastomoses and pulmonary gas exchange: evaluation by microspheres, contrast echocardiography and inert gas elimination.

Imaging techniques such as contrast echocardiography suggest that anatomical intra-pulmonary arteriovenous anastomoses (IPAVAs) are present at rest and are recruited to a greater extent in conditions such as exercise. IPAVAs have the potential to act as a shunt, although gas exchange methods have not demonstrated significant shunt in the normal lung. To evaluate this discrepancy, we compared anatomical shunt with 25-µm microspheres to contrast echocardiography, and gas exchange shunt measured by the multiple inert gas elimination technique (MIGET). Intra-pulmonary shunt measured by 25-µm microspheres was not significantly different from gas exchange shunt determined by MIGET, suggesting that MIGET does not underestimate the gas exchange consequences of anatomical shunt. A positive agitated saline contrast echocardiography score was associated with anatomical shunt measured by microspheres. Agitated saline contrast echocardiography had high sensitivity but low specificity to detect a ≥1% anatomical shunt, frequently detecting small shunts inconsequential for gas exchange. The echocardiographic visualization of transpulmonary agitated saline microbubbles suggests that anatomical intra-pulmonary arteriovenous anastomoses are recruited during exercise, in hypoxia, and when cardiac output is increased pharmacologically. However, the multiple inert gas elimination technique (MIGET) shows insignificant right-to-left gas exchange shunt in normal humans and canines. To evaluate this discrepancy, we measured anatomical shunt with 25-µm microspheres and compared the results to contrast echocardiography and MIGET-determined gas exchange shunt in nine anaesthetized, ventilated canines. Data were acquired under the following conditions: (1) at baseline, (2) 2µgkg-1 min-1 i.v. dopamine, (3) 10µgkg-1 min-1 i.v. dobutamine, and (4) following creation of an intra-atrial shunt (in four animals). Right to left anatomical shunt was quantified by the number of 25-µm microspheres recovered in systemic arterial blood. Ventilation-perfusion mismatch and gas exchange shunt were quantified by MIGET and cardiac output by direct Fick. Left ventricular contrast scores were assessed by agitated saline bubble counts, and separately by appearance of 25-µm microspheres. Across all conditions, anatomical shunt measured by 25-µm microspheres was not different from gas exchange shunt measured by MIGET (microspheres: 2.3±7.4%; MIGET: 2.6±6.1%, P=0.64). Saline contrast bubble score was associated with microsphere shunt (ρ=0.60, P<0.001). Agitated saline contrast score had high sensitivity (100%) to detect a ≥1% shunt, but low specificity (22-48%). Gas exchange shunt by MIGET does not underestimate anatomical shunt measured using 25-µm microspheres. Contrast echocardiography is extremely sensitive, but not specific, often detecting small anatomical shunts which are inconsequential for gas exchange.

Comparison of data processing algorithm performance for optical and conductivity void probes

In commercial nuclear reactors, heat exchangers, and bubble column reactors, two-phase flows are present. When predicting the safety and process efficiency of these systems, it is necessary to model the behavior found in them. The most common model used in two-phase flows is the two-fluid model due to its practicality. In the two-fluid model, two key parameters are the void fraction (VF, also known as the gas fraction or gas holdup) and interfacial area concentration (IAC, also known as interfacial area density). In order to produce accurate results, the bubbles are separated into groups based on the transport properties. When benchmarking models, experimental data are required. In many cases the experimental data are produced with the use of intrusive conductivity or optical probes. Recently a new data processing algorithm was developed to improve bubble interface identification and implement a method to group bubbles based on diameter rather than chord length. In this paper, the new data processing algorithm is evaluated by comparing the results when using both conductivity and optical probes. At a data acquisition frequency of 22 kHz, the optical probe collected more bubbles than the conductivity probe using the old algorithm. The new algorithm results in similar bubble counts for both instruments. There is a shift in bubbles from Group 1 to Group 2 in both the optical and conductivity probes. The new bubble size calculation means that several bubbles, which were previously classified as “spherical/distorted”, are now classified as “cap/slug/churn” bubbles for both the optical and conductivity probes. However due to low sample rates used in this research, the IAC is larger for the conductivity probe when compared to the optical probe by 10% to 60%. While some of these changes were expected, the increase in the IAC was larger than the reported uncertainty of the instruments.

Time Course of Endothelial Dysfunction Induced by Decompression Bubbles in Rats.

Decompression stress can cause endothelial injury, leading to systematic inflammation and prothrombotic phenomena. Our previous work found that endothelial injury following decompression correlated positively with bubble formation. This study aimed to investigate the time course of endothelial injury and the relationship with bubble amounts. Rats were subjected to a simulated air dive to 7 ATA for 90 min with rapid decompression. Bubbles were detected ultrasonically at the root of pulmonary arteries following decompression. Surviving rats were randomly divided into six groups according to sampling time following decompression (2, 6, 12, 24, 48, and 72 h). Three parameters, serum levels of malondialdehyde (MDA), endothelin-1 (ET-1), and intercellular cell adhesion molecule-1 (ICAM-1) were identified from our previous study and measured. The level of MDA reached a peak level at 12 h post decompression, and then decreased gradually to control level before 72 h. For both ET-1 and ICAM-1, the greatest expression appeared at 24 h following surfacing, and the increases lasted for more than 72 h. These changes correlated positively with bubble counts at most detection time points. This study reveals the progress of endothelial dysfunction following decompression which provides guidance for timing the determination at least for the current model. The results further verify that bubbles are the causative agents of decompression induced endothelial damage and bubble amounts are an objective and suitable parameter to predict endothelial dysfunction. Most importantly, levels of endothelial biomarkers post dive may serve as sensitive parameters for assessing bubble load and decompression stress.

Effects of Purge-Flow Rate on Microbubble Capture in Radial Arterial-Line Filters

The process of microbubble filtration from blood is complex and highly dependent on the forces of flow and buoyancy. To protect the patient from air emboli, arterial-line filters commonly use a micropore screen, a large volume housing with purpose-built shape, and a purge port to trap, separate, and remove circulating microbubbles. Although it has been proposed that an insufficient buoyancy force renders the purge port ineffective at removing microbubbles smaller than 500 μm, this research attempts to investigate the purge flow of an arterial-line filter to better understand the microbubble removal function in a typical radial filter design. As its primary objective, the study aims to determine the effect of purge-flow rate on bubble capture using air bolus injections from a syringe pump with 22-gauge needle and Doppler ultrasound bubble detection. The measureable bubble size generated in the test circuit ranged between 30 and 500 μm, while purge flow was varied between .1 and .5 L/min for testing. Statistical analysis of the test data was handled using a repeated measures design with significance set atp&lt; .05 level. Outcomes demonstrated that higher purge flows yielded higher bubble counts, but the effect of purge-flow rate on bubble capture decreased as bubble size increased. Results also showed that purge flow from the test filter was capable of capturing all bubble sizes being generated over the entire flow range tested, and confirms utility of the purge port in removing microbubbles smaller than 500 μm. By analyzing bubble counts in the purge flow of a typical radial-filter design, this study demonstrates that currently available micropore filter technology is capable of removing the size range of bubbles that commonly pass through modern pump-oxygenator systems and should continue to be considered during extracorporeal circulation as a measure to improve patient safety.

Correlation between bulk characteristics of aggregated β-lactoglobulin and its surface and foaming properties

Bovine β-lactoglobulin features a pronounced surface activity, and therefore, is widely applied in order to provide stability to food-related aerated systems. Due to its distinct tertiary and quaternary structure, it can be used both in native state as well as in the form of thermally aggregated particles. In this context, heat treatment (80 °C/90 min) of highly purified solutions of β-lactoglobulin (c = 10.0 g L−1) under variation of solution pH (6.8 or 8.0) and NaCl concentration (0–130 mM) resulted in the formation of soluble aggregates, whose median particle diameters ranged from about 2.5 nm to 1.1 μm. These differences in particle size in combination with differences in particle characteristics (e.g. surface hydrophobicity, zeta potential) had a significant impact on surface properties, i.e. surface tension, dynamics of protein adsorption and interfacial dilatational properties. Thereby, diffusion rates decreased with increasing median particle diameter. Initial protein adsorption was majorly influenced by surface hydrophobicity. However, reverse observations emerged in terms of foam characteristics. Foam stability clearly increased with increasing aggregate size, showing maxima for the largest particles examined. The increasing foam stabilization ability was also reflected in time-resolved bubble properties, e.g. lower mean bubble areas as well as higher bubble counts for larger aggregates. This observation was traced back to the increasing surface hydrophobicity as well as more negative zeta potential of the aggregates with increasing particle diameter. As a result, sterically stabilized and more impermeable surface films in combination with electrostatic repulsive forces led to a reduction in coalescence rate as indicated by a lower coarsening exponent, and thus, a decrease of foam decay.

The effect of forced air warming devices compared to other active warming devices on surgical site contamination: a systematic review protocol.

REVIEW QUESTION / OBJECTIVE The objective of this systematic review is to synthesize the best available evidence comparing forced air warming devices to other active warming devices to determine whether or not there is an increased risk of surgical site contamination by microbial emissions during the perioperative period. Specifically the review question is: Do forced air warming devices compared to other active warming devices have an increased risk of surgical site contamination during the perioperative period? INCLUSION CRITERIA Types of participants This review will consider studies that include subjects (patients, volunteers, mannequins) of all ages that were warmed perioperatively in any type of surgery or simulated surgical environment. Types of intervention(s) This review will consider studies that compare only forced air warming devices to other active warming technologies such as a radiant warming blanket. Types of outcomes This review will consider studies that include the following outcome measures: particle counts or neutrally buoyant bubble counts, measured by: a laser particle count device or time-lapse photography.