Formation Of Air Bubbles Research Articles

Selective Delivery of Clindamycin Using a Combination of Bacterially Sensitive Microparticle and Separable Effervescent Microarray Patch on Bacteria Causing Diabetic Foot Infection.

Diabetic foot infection (DFI) is one of the complications of diabetes mellitus. Clindamycin (CLY) is one of the antibiotics recommended to treat DFI, but CLY given orally and intravenously still causes many side effects. In this study, we encapsulated CLY in a bacteria sensitive microparticle system (MP-CLY) using polycaprolactone (PCL) polymer. MP-CLY was then delivered in a separable effervescent microarray patch (MP-CLY-SEMAP), which has the ability to separate between the needle layer and separable layer due to the formation of air bubbles when interacting with interstitial fluid in the skin. The characterization results of MP-CLY proved that CLY was encapsulated in large amounts as the amount of PCL polymer used increased, and there was no change in the chemical structure of CLY. In vitro release test results showed increased CLY release in media cultured with Staphylococcus aureus bacteria and showed controlled release. The characterization results of MPCLY-SEMAP showed that the developed formula has optimal mechanical and penetration capabilities and can separate in 56 ± 5.099s. An ex vivo dermatokinetic test on a bacterially infected skin model showed an improvement of CLY dermatokinetic profile from MP-CLY SEMAP and a decrease in bacterial viability by 99.99%. This research offers proof of concept demonstrating the improved dermatokinetic profile of CLY encapsulated in a bacteria sensitive MP form and delivered via MP-CLY-SEMAP. The results of this research can be developed for future research by testing MP-CLY-SEMAP in vivo in appropriate animal models.

Autoclave Design for Microgravity Hydrothermal Synthesis

Microgravity offers an enticing synthetic knob for materials scientists to explore—however, this environment creates major challenges in hardware development that can turn a simple 3-day experiment into a 3-year long nightmare. This paper provides an overview of engineering an autoclave, compatible with NASA’s Solidification Using a Baffle in Sealed Ampoules (SUBSA) furnace, to enable microgravity hydrothermal synthesis—an acceleration-sensitive technique that processes aqueous samples above the boiling point of water. Hydrothermal synthesis is a universal chemical transformation technique that is used to produce a range of advanced materials with applications in alternative energy, healthcare, and the food industry. In this work, we use the synthesis of graphene hydrogel as a case study to verify our hardware design on Earth before launching to the International Space Station for microgravity testing. The design addresses pertinent challenges which include enabling thermal expansion while preventing air bubble formation in solution and implementing a pressure fail-safe above the maximum operating temperature. Our goal in presenting this autoclave design is to provide a step forward towards commercial-of-the-shelf microgravity hardware.

Whole transcriptome analysis highlights nutrient limitation of nitrogen cycle bacteria in simulated microgravity

Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO2-producing C. testosteroni and the tripartite culture, a PermaLifeTM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O2 limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.

DENOISING THE SHOCKWAVE PRESSURE SIGNAL OF UNDERWATER EXPLOSION BASED ON EMD-CEEMDAN IN CONSIDERATION OF THE SIGNAL CURVE CURVATURE

The measured signal of shockwave pressure of underwater explosion is usually disturbed by many objective factors such as the disturbance of the environment surrounding the sensors, the complexity of wave propagation and wave reflection in complex environments, the formation and fluctuation of air bubbles, especially analog signals always have noise due to the influence of electronic noise from the A/D converter and circuit board error embedded in measuring devices, etc. These are the main causes of initial waveform distortion, obscuring important characteristics of the signal, and making it difficult to use and further analyze underwater explosion shockwave pressure. Based on two algorithms Empirical Mode Decomposition (EMD) and Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), this article combines the two algorithms above into one denoising model called EMD-CEEMDAN model with Python codes. Three evaluation criteria such as the average curvature of the signal curve, signal-to-noise ratio (SNR) and mean squared error (MSE) are applied to establish the most suitable denoising model. Applying this model to experimentally measured signal of underwater explosion shockwave pressure, the results show that high-frequency noise is eliminated, the denoised signal is transformed into a typically smooth explosion signal while its peak pressure value differs only about 2% from that of the initial signal.

Vac-and-fill: A micromoulding technique for fabricating microneedle arrays with vacuum-activated, hands-free mould-filling

We report a simple and reproducible micromoulding technique that dynamically fills microneedle moulds with a liquid formulation, using a plastic syringe, triggered by the application of vacuum (‘vac-and-fill’). As pressure around the syringe drops, air inside the syringe pushes the plunger to uncover an opening in the syringe and fill the microneedle mould without manual intervention, therefore removing inter-operator variability. The technique was validated by monitoring the plunger movement and pressure at which the mould would be filled over 10 vacuum cycles for various liquid formulation of varying viscosity (water, glycerol, 20% polyvinylpyrrolidone (PVP) solution or 40% PVP solution). Additionally, the impact of re-using the disposable syringes on plunger movement, and thus the fill pressure, was investigated using a 20% PVP solution. The fill pressure was consistent at 300–450mbar. It produced well-formed and mechanically robust PVP, poly(methylvinylether/maleic anhydride) and hydroxyethylcellulose microneedles from liquid formulations. This simple and inexpensive technique of micromoulding eliminated the air entrapment and bubble formation, which prevent reproducible microneedle formation, in the resultant microneedle arrays. It provides a cost-effective alternative to the conventional micromoulding techniques, where the application of vacuum (‘fill-and-vac’) or centrifugation following mould-filling may be unsuitable, ineffective or have poor reproducibility.

Effect of Injection Parameters on the MRI and Dielectric Properties of Condensation-Cured Silicone.

Phantoms with tissue-mimicking properties play a crucial role in the calibration of medical imaging modalities, including Magnetic Resonance Imaging (MRI). Among these phantoms, silicone-based ones are widely used due to their long-term stability in MR imaging. Most of these phantoms are manufactured using traditional pour-mold techniques which often result in the production of air bubbles that can damage the phantom. This research investigates the feasibility of utilizing extrusion techniques to fabricate silicone phantoms and explores the effects of extrusion parameters including plunger speed and nozzle diameter on void content, T1 and T2 relaxation times, and dielectric properties. A custom double-syringe silicone extrusion apparatus was developed to prepare the silicone samples. The void content, relaxometry, and dielectric properties of extruded samples were measured and compared with traditional poured samples. The results show that extrusion parameters can affect the void content of the silicone samples. The presence of voids in the samples resulted in lower T1 values, indicating an inverse relationship between void content and relaxometry. This study demonstrates the potential of extrusion techniques for manufacturing silicone phantoms with reduced air bubble formation and provides valuable insights into the relationship between extrusion parameters and phantom properties.

Transportation of mAb Dosing Solution in Intravenous Bag: Impact of Manual, Vehicle, and Pneumatic Tube System Transportation Methods on Product Quality.

Monoclonal antibody (mAb) products for intravenous (IV) administration generally require aseptic compounding with a commercial diluent within a pharmacy. The prepared dosing solution in the IV bag may be transported to the dosing location via manual, vehicular, pneumatic tube system (PTS), or a combination of these methods. In this study, the type and level of physical stresses associated with these three methods and their product quality impact for relatively sensitive and stable mAbs were assessed. Vibration was found to be the main stress associated with manual and vehicle transportation methods, although this was at a relatively low level (<1 GRMS/Root-Mean-Square Acceleration). Shock and drop events, at relatively low levels, were also observed with these methods. PTS transportation showed substantially more intense shock, vibration, and drop stresses and the measured levels were up to 91 G/force of acceleration or deceleration, 3.7 GRMS and 39 G, respectively. Using a foam padding insert for PTS transportation reduced the shock level considerably (91 G to 59 G). Transportation of mAb dosing solutions in IV bags via different methods including PTS transportation variables caused a small increase in the subvisible particle counts and there was no change in submicrometer particle distribution. No visible particles and no significant change to soluble aggregate levels were observed after transportation. Strategies such as removal of IV bag headspace prior to transport and in-line filtration poststress reduced the subvisible particles counts. All tested transportation conditions showed negligible impact on other product quality attributes tested. Removal of IV bag headspace prior to PTS transport prevented formation of micro air bubbles and foaming compared to the unaltered IV bag. This study shows examples where manual, vehicle, and PTS transport methods did not significantly impact product quality, and provides evidence that mAb products that are appropriately stabilized in the dosing solution (e.g., with a surfactant) can be transported via a PTS.

Deteksi Bakteri Proteolitik Dari Ileum Gallus Gallus Sebagai Kandidat Agen Probiotik Pakan Fermentasi Unggas

The ileum is part of the small intestine that functions as the absorption of food and for the growth and development of bacteria to degrade feed, such as lactic acid bacteria. The purpose of this study was to explore and detect proteolytic bacteria from the ileum of Gallus gallus as a candidate probiotic agent. The research method is a selection of proteolytic bacteria, catalase, and motility. The results showed that the average proteolytic index in isolates GP sp. 4, GP sp.3, and GP sp. 1 were 1.533, 1.531, and 1.500. Nine isolates were gram-positive and one gram-negative (GP sp. 3). The ten isolates could hydrolyze hydrogen peroxide, as indicated by the formation of air bubbles. The motility test showed that eight isolates were motile and the other two isolates were non-motile (GP sp.8 and GP sp.10). The ten proteolytic bacterial isolates obtained did not have the potential to be used as probiotic agents for fermented poultry feed because low proteolytic index value.

Unusual formation of air bubbles in the arms of the California two-spot octopus, Octopus bimaculatus Verrill, 1883 during handling in captivity

Unusual formation of air bubbles in the arms of the California two-spot octopus, Octopus bimaculatus Verrill, 1883 during handling in captivity

Influences of admixture combinations on the formation and stability of air bubbles in fresh cementitious materials

Various mineral and chemical admixtures have been widely added to modern concrete mixtures but few studies have investigated the characteristics of air bubbles in fresh cementitious materials under different admixture combinations. This study aimed to explore the influences of mineral and chemical admixture combinations including one Class F fly ash, three different air entraining admixtures (AEAs), and two various polycarboxylate superplasticizers (SPs) on the formation and stability of air bubbles in fresh cementitious systems. The foam index tests on fresh cementitious paste were utilized to explore the impacts of fly ash, AEA types, and SP on foam ability. Also, twelve fresh concrete mixtures were produced in laboratory, then the air volume content and air bubble spacing were measured within 60 min to assess the air bubble stability. Test results suggested that adding fly ash decreased the foam ability of AEA, while the SP addition improved the foam ability. The neutralized vinsol-resin based AEA1 had a higher foam ability than synthetic AEA2 and AEA3. The foam index of paste with SP addition showed a higher correlation with the AEA dosage for fresh concrete than those without SP addition. The air bubble stability in fresh concrete was highly affected by the admixture combinations. Overall, neutralized vinsol-resin based AEA1 produced more stable air bubbles than synthetic AEA2 and AEA3.

Pore doublet micromodel experiments of evaporation influence on pre-event water entrapment and pre-event and event water interaction

The stable isotopic signature of xylem water differs from those of rainfall and river water. Without considering the water exchange through the vapor phase, this phenomenon implies that when the event water (new water) infiltrates the soil, a part of the pre-event water (old water) is isolated. The isolation and immobilization of old water are suspected because of the low matrix potential. Because evaporation is the main process that can reduce the matrix potential after quick gravitational drainage, we conjectured that after evaporation, the old water hides in small pores and increases the likelihood of air entrapment, which separates the new and old water. To examine and visualize the potential effect of evaporation on the interactions between old and new water, we performed a series of wetting–drainage–evaporation–wetting experiments within pore doublet micromodels (PDMs). The experimental results showed that air bubbles are trapped when the menisci of the residual liquid are sufficiently far from the inlet and outlet of the PDM. Evaporation can increase these distances, resulting in the formation of larger air bubbles. The air bubble trapped upstream prevents the invading liquid from quickly flushing the original residual liquid out of the PDM. Nevertheless, the invading wetting liquid is still able to bypass the trapped air bubbles and mix with the residual wetting phase via corner flow. In addition, the remobilization of the upstream bubble enhances the process of removing the old trapped liquid.

Effect of proteins on the mineralization, microstructure and mechanical properties of carbonation cured calcium silicate

The effect of five proteins with different physicochemical properties on the mineralization, microstructure, and mechanical properties of carbonated wollastonite pastes was examined. The negative surface charge of wollastonite particles increased as the result of protein adsorption. The flow of fresh paste was shown to increase in the pastes with proteins due to the enhanced electrostatic repulsion of the wollastonite particles as a result of the adsorption of negatively charged proteins, the ball bearing effect of the proteins in the pore solution, and formation of air bubbles. While calcite and amorphous calcium carbonate were the primary phases of calcium carbonate in all pastes, other polymorphs including aragonite and vaterite were present, to a small extent, in the microstructure of most of the pastes modified with proteins. The calcium carbonate content was shown to be higher in some of the pastes modified with proteins and this was attributed to the delayed water loss to evaporation and presence of free water due to hydrophobization of pastes modified with proteins. The X-ray micro-computed tomography (micro-CT) analysis revealed the formation of cracks in the control and some of the protein modified pastes resulting from drying shrinkage. It was demonstrated that the increased microstructure hydrophobicity was the reason for the absence of cracks in the pastes with the proteins that did not show cracks. Overall, the carbonated pastes with proteins exhibited higher compressive strength compared to the control paste. Absence of cracks, enhanced interfacial strength between carbonated products in the microstructure and organic-inorganic composite formation are suggested to be responsible for the increased compressive strength of the carbonated pastes with proteins.

Cerebrovascular events after cardiovascular surgery: diagnosis, management and prevention strategies.

Cerebrovascular events after cardiac surgery are among the most serious complications, related to a greater risk of patient mortality. This problem can occur following the formation of gas emboli during open heart surgery. To address all the mechanisms that can lead to embolic events after cardiovascular surgery, how to manage them and how to possibly prevent them. A search of the PubMed database was conducted. We reviewed the clinical literature and examined all aspects to identify the root causes that can lead to the formation of emboli. Among the studies reviewed, it was found that the main causes include manipulation of the aorta, inadequate deaeration after cardiac surgery, and blood-component contact of extracorporeal circulation. It has been reported that gas emboli can lead to deleterious damage such as damage to the cerebral vascular endothelium, disruption of the blood-brain barrier, complement activation, leukocyte aggregation, increased platelet adhesion, and fibrin deposition in the microvascular system. Stroke after cardiovascular surgery is one of the most important complications, with a great impact on operative mortality and patient survival. Efforts have been made over time to understand all the pathophysiological mechanisms related to this complication, with the aim of reducing its incidence. One of the goals should be to improve both the surgical technique and the perfusion modality and minimize the formation of air bubbles or to facilitate their elimination during the cardiopulmonary bypass procedure.

Experimental study on pressure characteristics and flow coefficient of butterfly valve

Air entrainment and self-aeration flow are phenomena that can generate fluctuation in pressure and induce disadvantages in piping systems. In this study, the mechanism of air bubble formation in Partially Filled Pipe Flow (PFPF) is investigated through a series of experiments on a butterfly valve with flow visualization and pressure measurement. This paper provides a description of the formation of bubbles induced by a butterfly valve and analyzes the characteristics of the pressure and flow coefficient of the valve. The pressures at various locations on the pipeline adjacent to the valve were measured to compare with the positions recommended by the International Society of Automation standard. The results indicated that in PFPF, the differences in the pressure between measured points downstream are noticeable, notably at valve openings less than 50°. The bubbles created at the valve, which lead to the highly-disordered aerated flow downstream, might induce the differences. The pressure drop and the flow rate across the butterfly valve in 100% water fraction flow are respectively 3–7.5 and 2–9 times higher than those in 90% WF. The flow coefficient of the 3-inch butterfly valve was found to increase linearly with the Reynolds number before leveling off when the Reynolds number exceeds 6×104. Besides, the flow coefficients in 100% water fraction flow are double those in 90% water fraction flow.

A new brain‐cutting device and ultraviolet resin‐mounted human brain slices as a teaching adjunct for neuroanatomy education

Although the level of neuroscience research is rapidly developing with the introduction of new technologies, the method of neuroanatomy education remains at the traditional level and requires improvement to meet the needs of educators and trainees. We developed a new three-dimensional (3D) printed device (human brain-cutting mold, HBCM) for creating human brain slices; moreover, we demonstrated a simple method for creating semi-permanent ultraviolet (UV) resin-mounted brain slice specimens for neuroanatomy education. We obtained brain slices of uniform thickness (3 mm) through the HBCM; the resultant brain slices were optimal for assessing morphological details of the human brain. Furthermore, we used an agar-embedding method for brain-slicing with the HBCM, which minimized geometrical distortions of the brain slices. Also, we prepared semi-permanent brain serial specimens using an acrylic brain slice frame and UV-curable resin, which was highly compatible with moist bio-specimens. During UV resin curing, neither air bubble formation nor color change occurred. The resultant UV resin-mounted brain slices produced definite coronal sections with high transparency and morphological accuracy. We also performed 3D modeling by stacking brain slice images that differentiated the cortical area and nine subcortical regions via manual segmentation. This method could be a reliable alternative for displaying high-quality human brain slices and would be helpful for students and trainee to understand anatomical orientation from 2D images to 3D structures. Also, this may present an innovative approach for preparing and preserving coronal sections of the normal or pathological human brain.

Suppression of Thermal Conductivity Enhancement in Carbon Nanofluids Caused by Surfactant High Concentration

In this study, structural and thermal properties of dispersed carbon nanomaterials such as single-wall carbon nanotubes and graphene in water are investigated. Carbon nanostructures are dispersed in the fluid through surfactant and ultrasonication treatment. Structural studies of the samples are carried out by Raman spectroscopy which show that the dispersion process leads to the formation of two kind of nanofluids: nanostructured graphene based and single-wall carbon nanotubes ones. The first in the form of graphene dots. The thermal diffusivities of the samples are measured by thermal lens technique. Contrary to what is normally expected our nanofluids show a considerable reduction in thermal conductivity. The reduction is stronger for graphene dots than for the carbon nanotubes. This peculiar behavior of the thermal conductivity is attributed to the high concentration ratio of surfactant to dispersed particles, as well as, the formation of air layer or bubbles attached to the nanoparticles due to sonication process. To evaluate this hypothesis, simulation of the effective thermal conductivity based on Murshed model is conducted for spherical and cylindrical particles surrounded by air layer. The simulation shows an effective decrease in thermal conductivity, which corroborates with the experimental trend.

P-110 A novel Artificial Intelligence Microscopy: Mojo AISA, the new way to perform semen analysis

Abstract Study question Can Mojo AISA, an Artificial Intelligence microscopy, release accurate and reliable semen analysis results for the daily routine? Summary answer Mojo AISA guarantee precise semen analysis results improving the objectiveness and minimizing human error. Moreover, embryologists can safe 50% of time per procedure. What is known already The current method to perform a semen analysis is through the manual microscope and/or computer-assisted semen analysis. The most automated sperm analyzers rely on a classic image processing algorithms which can distinguish spermatozoa by size and brightness. However, it has been demonstrated that these algorithms are not able to discriminate well spermatozoa heads from other cells that have similar size, leading to improper results. To overcome these limits, a new Artificial Intelligence Semen Analysis system, Mojo AISA, has been developed to carry out concentration and motility. Mojo AISA is based on a neural network classification, a series of embedded algorithms. Study design, size, duration In the last nine months, semen parameters of 64 men were assessed simultaneously by manual microscopy method and by Mojo AISA. The manual semen analysis was performed by two certified andrologists following WHO 5th Edition guidelines. Concentration and motility parameters were assessed and compared between the two methods. Regarding the motility, we compare the following 3 categories: Progressive (PR), Non-Progressive (NP) and combined motility (PR+NP). Samples with normal and abnormal semen parameters were included. Participants/materials, setting, methods Semen samples were allowed to liquefy for at least 15 min at 37°C. For the manual method, 10 μL of raw sample was loaded onto a Makler chamber and for Mojo AISA, two 10 μl drops of raw samples were smeared side on the side on a glass slide. Mojo AISA delivered semen analysis results in 4 minutes per sample. The statistical analysis was carried out with SPSS 14.0 statistical software. Main results and the role of chance A semen analysis of 64 semen samples from 62 men (40±10 years old) was performed simultaneously with manual method and Mojo AISA, following WHO 5th Edition (2010) guidelines. The average and the standard deviation of semen concentration with manual method and with Mojo AISA was 52.7±46 and 50.6± 43.2 x 106/ml, respectively (P=NS). No significant difference was found when the combined motility (PR+NP) was evaluated. Indeed, the average and standard deviation was 53.5±20% with manual method and 49.1± 22.1% with Mojo AISA (P=NS). Similar results were seen with progressive motility showing an average and standard deviation of 38.5±19% and 34.1±20%, respectively (P=NS). Ultimately, the assessment of non-progressive motility showed an average and standard deviation of 12.3±12% with manual method and 13.9± 9% with Mojo AISA, showing no statistic difference. Limitations, reasons for caution The protocol of the slide’s preparation should be properly followed since the formation of air bubbles can impact on the correct semen evaluation of Mojo, misleading sperm results. Mojo AISA presents difficulty to assess sample with extremely low concentration and further evaluation are needed for this type of samples. Wider implications of the findings These findings show that the semen analysis results of mojo AISA and those of manual method are comparable. Mojo AISA can guarantee semen analysis results more precise, with lower inter-laboratory variability and in a 50% shorter time. Trial registration number N/A

Testing 3D printed biological platform for advancing simulated microgravity and space mechanobiology research

The advancement of microgravity simulators is helping many researchers better understanding the impact of the mechanically unloaded space environment on cellular function and disfunction. However, performing microgravity experiments on Earth, using simulators such as the Random Positioning Machine, introduces some unique practical challenges, including air bubble formation and leakage of growth medium from tissue culture flask and plates, all of which limit research progress. Here, we developed an easy-to-use hybrid biological platform designed with the precision of 3D printing technologies combined with PDMS microfluidic fabrication processes to facilitate reliable and reproducible microgravity cellular experiments. The system has been characterized for applications in the contest of brain cancer research by exposing glioblastoma and endothelial cells to 24 h of simulated microgravity condition to investigate the triggered mechanosensing pathways involved in cellular adaptation to the new environment. The platform demonstrated compatibility with different biological assays, i.e., proliferation, viability, morphology, protein expression and imaging of molecular structures, showing advantages over the conventional usage of culture flask. Our results indicated that both cell types are susceptible when the gravitational vector is disrupted, confirming the impact that microgravity has on both cancer and healthy cells functionality. In particular, we observed deactivation of Yap-1 molecule in glioblastoma cells and the remodeling of VE-Cadherin junctional protein in endothelial cells. The study provides support for the application of the proposed biological platform for advancing space mechanobiology research, also highlighting perspectives and strategies for developing next generation of brain cancer molecular therapies, including targeted drug delivery strategies.

New In Vitro Model to Study Multicellular and Flow Control of Blood‐Brain Barrier

Brain endothelial cells of the blood‐brain barrier (BBB) have been shown to be regulated by supportive cells, such as pericytes and astrocytes, and shear stress exposure. However, studies investigating the impact of pericytes and astrocytes on brain endothelial cell function have identified both beneficial and detrimental results. Additionally, most studies investigating the relationship between shear stress and brain endothelial cell function lack physiological relevance via the use of sub‐physiological shear stress magnitudes and/or via the absence of pericytes and astrocytes. In this study, we developed a millifluidic device compatible with standard transwell inserts to investigate BBB function. In contrast to standard polydimethylsiloxane (PDMS) microfluidic devices, this model allows for easy, reproducible shear stress exposure without common limitations of PDMS devices such as inadequate nutrient diffusion and air bubble formation. In no‐flow conditions, we first used the device to examine the impact of primary human pericytes and astrocytes on human brain microvascular endothelial cell (HBMEC) barrier integrity. We found that astrocytes, pericytes, and a 1:1 ratio of both cell types increased HBMEC barrier integrity via reduced permeability to 40 kDa fluorescent dextran, which was associated with increased expression of tight junction protein, claudin‐5. Interestingly, we also observed a significantly lower permeability to 3 kDa dextran in HBMEC‐pericyte co‐cultures compared to HBMEC‐astrocyte and HBMEC‐astrocyte‐pericyte co‐cultures. Based on these findings, we hypothesize pericytes may be providing increased barrier support to the BBB model compared to astrocytes although they both function as permeability reducers. After using the device to generate 24‐hour flow at 12 dynes/cm2, we observed that shear stress exposure significantly reduced dextran permeability in HBMEC monolayers, but not in tri‐culture models consisting of HBMECs, pericytes, and astrocytes. These results indicate that co‐cultures may demonstrate a more pronounced impact on overall BBB permeability than flow exposure. In both cases, flow exposure was interestingly associated with reduced expression of both claudin‐5 and occludin. However, ZO‐1 expression, and localization at cell‐cell junctions increased in the tri‐culture but exhibited no apparent change in the HBMEC monolayer. Under flow conditions, we also observed alignment of HBMECs in the tri‐culture while no such phenomenon was observed in HBMEC monolayers, indicating supportive cells and flow are both essential to observe brain endothelial cell alignment in vitro. Collectively, these results support the necessity of physiologically relevant, multicellular BBB models when investigating brain endothelial cell function in relation to the BBB. Additionally, our findings provide clues on the role of shear stress and supportive cells within the BBB, a critical step to elucidating the physiology of the neurovascular unit.

Numerical investigation of water draining and oil-water draining from a square tank-A comparison

The present study investigates the interfacial dynamics in case water and oil-water drain through a storage tank pipe. The tank has a square cross-section and is connected with a drain port at the bottom of the tank of diameter 0.009 m. Different eccentric positions are also considered. OpenFOAM software is used to analyze the liquid draining situation. A 3D numerical model is used to simulate the liquid draining situation. The VOF model is used to track the interface. Free surface in water draining is narrower than that in oil-water draining. At the extreme eccentric port of e0.96, the oil-water case leads to the formation of air bubbles from the vortex tip inside the tank. In the case of water draining, a zone of velocity de-acceleration was noticed at the central part of the drain pipe for e0. Velocity and pressure fluctuations are noted at the inlet of the drain port; however, reverse flow is not observed. Reverse flow in water draining was observed at e 0.96. The opposite is the trend for oil-water draining. A flow reversal is noted after the initiation of three-phase flow inside the drainpipe at e 0. However, since three-phase flow was initiated early in the tank for e 0.96, reverse flow is not noticed inside the drain pipe.