Flow Mode Research Articles

Effect of pulsation intensity on flow and dispersion characteristics of single-pulsed dual parallel plane jets

The effect of pulsation intensity on flow and dispersion characteristics of single-pulsed dual parallel plane jets was experimentally investigated in this study. A single jet from a pair of dual jets was pulsed by a loudspeaker. The flow evolution processes were examined using the laser-light sheet-assisted smoke flow visualization method. The visual spread of the jet flow was measured using the binary boundary edge detection technique. A hotwire anemometer was used to detect the instantaneous velocities, mean velocities, turbulence intensities, Lagrangian integral time, and length scales. The dispersion capabilities of the jet fluid were evaluated employing the tracer-gas concentration detection technique. Two characteristic flow modes, namely the coherent vortices and vortex breakup, could be classified based on pulsation intensity. At Ip < 1.0, the flow was characterized by coherent vortices, which maintained coherence within one excitation cycle. At Ip > 1.0, vortex breakup occurred, where vortices deformed, lost coherence, and transformed into puff-shaped vortical structures within one excitation cycle. The vortices emerging from the pulsed jet undergo deformation, evolving into puff-shaped vortices, and subsequently fragment into smaller turbulent eddies more quickly than the synchronized vortices from the non-pulsed jet. This leads to significant penetration and velocity fluctuations in the trajectory of the pulsed jet. Consequently, the overall spread width and concentration reduction index of the single-pulsed dual parallel plane jets exceed those of the non-pulsed dual parallel plane jets.

A comprehensive assessment of gap spacing in tandem cylinders: Lattice Boltzmann technique based simulations

The current study uses the Lattice Boltzmann method (LBM) to analyze flow phenomena around the five square cylinders in a tandem setup. It examines flow characteristics for different gap spacing (g*), ranging from 0.5 to 8 at a Reynolds number Re = 100, and identifies three distinct flow modes: steady flow mode, partially unsteady flow mode, and partially packed vortex street in a single row. It is found that the flow modes reported in literature for the case of inline bodies exist for the present case as well but with a different range of gap ratios. The strength of vorticity in the wakes of the first three upstream cylinders is found to be increasing thus enhancing the Strouhal number as the gap ratio between cylinders increased. The drag mean coefficient (Cdmean) is found to increase with an increase in gap spacing values, while negative Cdmean values are observed for cylinders C2 and C3 in the steady flow mode, due to the emergence of thrust force. The average drag coefficient is found to be minimal for C2 until g* = 6 compared to other cylinders, while for C1 it is found to be higher across all gap spacings. The local minimum average drag coefficient value of 0.1824 is observed for C2 at g* = 1.5 while the local maximum Cdmean value of 1.2849 is observed for C1 at g* = 8 in this study. A similar shedding frequency emerges for the first three cylinders which mostly spanned over the partially packed single row vortex street flow mode. The research also reveals that g* = 4 is the critical spacing value for abrupt fluid flow changes.

Investigation of nitrogen conversion in ditch-treated greywater: Contributions of biochar and aeration

This study aimed to assess the contribution of different combinations of uninterrupted aeration and tidal flow modes, as well as shallow and deep biochar landfill methods, to nitrogen removal pathways in ditches. Compared to natural ditches, the addition of biochar and aeration resulted in higher water pollution removal rates, lower Greenhouse Gas (GHG) emissions, and reduced sediment leaching. The nitrogen mass balance revealed that Total Nitrogen removal efficiency of each ditch group was 25.33% for CA-C, 43.75% for DBT-C, 49.08% for UBT-C, 30.75% for DBA-C, and 45.16% for UBA-C. Compared to the control group (CA-C), the tidal flow group with deep biochar landfill (DBT-C)demonstrated the highest efficiency in total nitrogen removal. To elucidate the fate of nitrogen elements, potential transformation processes of unexplained nitrogen were explored. The primary outflow pathway of nitrogen pollution in ditches is through liquids. The nitrogen composition in the liquid of each ditch indicated that for shallow biochar configurations (UBT-C/UBA-C), denitrification might be the main factor limiting TN removal efficiency. In contrast, for deep biochar configurations (DBT-C/DBA-C), hydrolysis and nitrification of organic nitrogen were identified as limiting factors, with tidal flow alleviating these limitations. Overall, the combination of shallow biochar and tidal flow aeration in a ditch is the most effective method for removing rural greywater, providing valuable insights for the development of design parameters in greywater removal systems.

Optimization and performance evaluation of a novel nano-zeolite amended pure oxygen-driven membrane aerated biofilm reactor (Z-PO-MABR) for enhanced carbon and nitrogen removal from high-strength wastewater

High-strength wastewater presents significant environmental challenges. Membrane-aerated biofilm reactor (MABR) technology, enhanced by pure oxygen, improves treatment efficiency. Additionally, nano-zeolite-based techniques have shown promise. This study introduces a novel nano-zeolite amended pure oxygen-based MABR system (Z-PO-MABR), combining the benefits of pure oxygen and nano-zeolite. A bench-scale Z-PO-MABR was developed and tested under various conditions to optimize the operation. Optimization achieved high removal rates of organic carbon (98 %) and total nitrogen (96.9 %) with 72 g/Lr of nano-zeolite after 9 h. The Z-PO-MABR system outperforms conventional and pure oxygen-based MABRs, demonstrating greater efficiency in continuous and batch flow modes. The optimized parameters maximize carbon degradation and support microbial growth, offering an eco-sustainable solution for high-strength wastewater treatment. The Z-PO-MABR system is proposed as a promising method for efficient carbon removal and complete nitrogen release. Thus, the study strongly nominates the Z-PO-MABR as an effective treatment system.

BGFlow: Brightness-guided normalizing flow for low-light image enhancement

Low-light image enhancement poses significant challenges due to its ill-posed nature. Recently, deep learning-based methods have attempted to establish a unified mapping relationship between normal-light images and their low-light versions but frequently struggle to capture the intricate variations in brightness conditions. As a result, these methods often suffer from overexposure, underexposure, amplified noise, and distorted colors. To tackle these issues, we propose a brightness-guided normalizing flow framework, dubbed BGFlow, for low-light image enhancement. Specifically, we recognize that low-frequency sub-bands in the wavelet domain carry significant brightness information. To effectively capture the intricate variations in brightness within an image, we design a transformer-based multi-scale wavelet-domain encoder to extract brightness information from the multi-scale features of the low-frequency sub-bands. The extracted brightness feature maps, at different scales, are then injected into the brightness-guided affine coupling layer to guide the training of the conditional normalizing flow module. Extensive experimental evaluations demonstrate the superiority of BGFlow over existing deep learning-based approaches in both qualitative and quantitative assessments. Moreover, we also showcase the exceptional performance of BGFlow on the underwater image enhancement task.

Enhancing thermal performance of jet-regeneration composite cooling systems: An analysis of flow mode and distribution utilizing supercritical n-decane and ambient air

To enhance the heat transfer performance of the scramjet, this paper conducts research and analysis on the impact of flow mode and flow distribution of supercritical n-decane and ambient air on flow and heat transfer characteristics, based on regeneration cooling channels. Given the disparities in fluid flow characteristics within the channel, the three flow configurations exhibit varying degrees of heat transfer deterioration. In the jet single outlet flow mode, the fluid mobility within the channel is relatively poor, leading to the most pronounced deterioration of heat transfer. The combined heat transfer performance between the jet fluid and the crossflow fluid is predominantly influenced by the number of jets and the distribution ratio of flow rates. Notably, the jet-crossflow single outlet arrangement exhibits exceptional heat transfer capabilities when the jet flow rate constitutes a relatively low proportion (12.5 %) while the crossflow flow rate is substantial (87.5 %). Ambient air, with its lower density, arrives at the heated surface with significantly higher velocities and greater turbulence intensity compared to supercritical n-decane. As the number of jet holes increases, the inhomogeneity (R) in the Nusselt number gradually diminishes. For most configurations, R is more pronounced in ambient air than in supercritical n-decane.

Numerical investigation and optimization of liquid battery thermal management system considering nanofluids, structural, and flow modifications under high discharge cycles

The thermal management of electric vehicle (EV) batteries continues to be a pressing challenge preventing wider EV adoption due to performance and safety concerns. Liquid battery thermal management systems (BTMSs) are the most commercially viable thermal management option due to their high heat transfer efficiency and compact design, despite these promising features, the current liquid BTMS designs suffer from high energy consumption and temperature gradients which severely affect the BTMS performance. To address these issues, this study numerically investigated the influence of various liquid BTMS design parameters for a 12 cylindrical lithium-ion battery module. The study evaluated 21 different BTMS configurations based on the maximum battery temperature, temperature difference, pressure drop, and energy consumption. Based on the selected evaluation criteria, The optimized liquid BTMS design (one cooling block, bidirectional flow, 0.0015 kg/s mass flow rate, 4 mm cell spacing, continuous operation strategy with hybrid CuO-MgO-TiO2 water 0.5 % concentration nanofluid) maintained the maximum temperature and temperature difference at 31.34 and 5.3 °C respectively, a 4.3 % and 21.1 % improvement compared to the base design, with a total pressure drop of 12.84 Pa when operated under 35 °C ambient temperature and 3C discharge rate. Proving the effectiveness of the proposed liquid BTMS design.

Resolving turbulence and drag over textured surfaces using texture-less simulations: the case of slip/no-slip textures

We study the effect of surface texture on an overlying turbulent flow for the case of textures made of an alternating slip/no-slip pattern, a common model for superhydrophobic surfaces, but also a particularly simple form of texture. For texture sizes $L^+ \gtrsim 25$ , we have previously reported that, even though the texture effectively imposes homogeneous slip boundary conditions on the overlying, background turbulence, this is not its sole effect. The effective conditions only produce an origin offset on the background turbulence, which remains otherwise smooth-wall-like. For actual textures, however, as their size increases from $L^+ \gtrsim 25$ the flow progressively departs from this smooth-wall-like regime, resulting in additional shear Reynolds stress and increased drag, in a non-homogeneous fashion that could not be reproduced by the effective boundary conditions. This paper focuses on the underlying physical mechanism of this phenomenon. We argue that it is caused by the nonlinear interaction of the texture-coherent flow, directly induced by the surface topology, and the background turbulence, as it acts directly on the latter and alters it. This does not occur at the boundary where effective conditions are imposed, but within the overlying flow itself, where the interaction acts as a forcing on the governing equations of the background turbulence, and takes the form of cross-advective terms between the latter and the texture-coherent flow. We show this by conducting simulations where we remove the texture and introduce additional, forcing terms in the Navier–Stokes equations, in addition to the equivalent homogeneous slip boundary conditions. The forcing terms capture the effect of the nonlinear interaction on the background turbulence without the need to resolve the surface texture. We show that, when the forcing terms are derived accounting for the amplitude modulation of the texture-coherent flow by the background turbulence, they quantitatively capture the changes in the flow up to texture sizes $L^+ \approx 70{-}100$ . This includes not just the roughness function but also the changes in the flow statistics and structure.

A novel Zero Back Power Flow (ZBPF) controlled DAB for DC bus stability and energy storage integrations in hybrid DC/AC off-grid systems

The paper presents an innovative approach for integrating energy storage devices into hybrid AC/DC grids to ensure a consistent power supply for modern loads. It introduces a Zero Back Power Flow (ZBPF) enabled bi-directional Dual Active Bridge (or, Direct AC-AC Boost) (DAB) controller strategy aimed at enhancing the power handling capacity DABs, while offering adaptable control for the microgrid system. Utilizing the proposed ZBPF control technique, the system endeavors to improve the power quality of the high-frequency AC link and regulate power transfer across DAB converter. Furthermore, a power management control strategy is described to facilitate efficient power flow among the diverse sources and loads within the hybrid off-grid system via battery system. By incorporating multiple utility features, the system aims to maintain stable bus voltages and mitigate potential power supply reliability issues. The paper concludes with simulation results validating the efficacy of the proposed ZBPF DAB control algorithms in grid forming operational modes, demonstrating the feasibility and effectiveness of the proposed solution. Additionally, the proposed ZBPF controller is tested on a hardware platform using batteries. An experimental setup has been conducted to verify the operation of the proposed ZBPF modulation scheme for a DAB converter in a practical setting. It involves implementing the ZBPF modulation scheme using a Hardware-in-the-Loop (HIL) setup and testing the DAB converter under both forward and reverse power flow modes.

Scalable approach for growing hexagonal boron nitride on silicon and its role in III-nitride van der Waals epitaxy

Hexagonal boron nitride (h-BN) stands out among 2D materials for its insulating properties, making it promising for the integration of 2D and 3D materials. However, achieving wafer-scale growth on silicon substrates remains a significant challenge. In this study, growth strategies for depositing h-BN on Si substrates are explored utilizing the wafer scalable metalorganic chemical vapor deposition. Our investigations reveal that employing a pulsed flow mode scheme is preferable over the conventional continuous flow mode scheme in growing h-BN thin films on 150 mm Si substrates. The as-grown h-BN film on Si exhibits uniform coverage with h-BN[0001]//Si[111]. With the successful wafer-scale growth of h-BN on Si, its role in aiding the van der Waals epitaxy of III-nitrides on Si substrates and subsequent epitaxial lift-off (ELO) of III-nitrides is further exemplified. An optimized h-BN thickness for the ELO process is also determined.

Performance Characteristics of a Compact Core Annular-Radial Magnetorheological Damper for Vehicle Suspension Systems

The magnetorheological (MR) damper is a by-wire system capable of providing variable damping stiffness by responding to an apparent magnetic field. In response to the magnetic field application, the magnetorheological fluid (MR fluid) exhibited altered behavior within the damper. Typically, a damper’s internal and external valves operate in flow mode, where the flow is regulated by controlling the magnetic field. This study aims to investigate the performance characteristics of a small core annular and radial magnetorheological valve (SCARMV) designed for applications in vehicle suspension systems. The proposed design of the simplified MR valve is based on a meandering-type valve composed of multiple valve cores that have been simplified to a single core. Dynamic testing was performed on the proposed valve, which features a single rod tube damper, to investigate the damping force characteristics by varying currents and frequencies. The characteristics of the measured damping force were compared to the calculated damping force based on the pressure drop calculation and the FEMM simulation of magnetic flux. By increasing the stroke length of the valve travel is set to 10 mm at a current input of 0 A to 1.0 A, the maximum output of the MR valve damping force was approximately 1.57 kN. In addition, a mathematical model of SCARMV is presented and compared to the experimental data. Therefore, based on the experimental results, it was concluded that the usability of a compact core MR valve is reliable. However, more in-depth studies are required before these dampers can be applied to vehicle suspension systems.

Convenient-style electrodeionization system with novel configuration and inflow mode for small-scale high purity water preparation

Electrodeionization (EDI) is a promising sustainable and eco-friendly technology for deep desalination, essential for preparing high purity water (HPW). Its miniaturization and simplification are crucial for the application of small-scale HPW machines in decentralized HPW supply scenarios. In this study, a two-stage Convenient-style EDI (Conv-EDI) system with the countercurrent flow mode and special resin-filling strategy was proposed, which eliminates the need for many components found in conventional EDI systems. The influences of total inflow (Qtot), inflow ratio of dilute and concentrate stream (QD/QC), total applied current (Itot), and the distribution of current between two stacks (I1/I2) were studied, respectively. Initially, the inflow pattern had great influence on the back diffusion phenomenon and the competitive electromigration among H+, OH−, and other ions in the dilute stream. Optimal conditions were determined to be a Qtot of 25 L·h−1 and a QD/QC of 3/2. Meanwhile, the operation mode of the Conv-EDI stack was determined by the applied current, and the optimal Itot and I1/I2 were 0.30 A and 1/1, respectively. Furthermore, the system demonstrated excellent long-term stability and anti-scaling performance over 20 days of continuous operation. It could operate stably with raw water containing hardness of ~3.4 mg·L−1, and the highest resistivity HPW of 15.52 MΩ·cm could be produced with the energy consumption of ~0.19 kWh·m−3 and the total process of 2.43 USD·m−3. In summary, the Conv-EDI system offers a practical and efficient solution for small-scale HPW production, advancing the miniaturization of EDI technology and potentially transforming decentralized HPW supply systems.

Experimental study on the influence of operating parameters of plug flow on thermal efficiency of direct absorption solar collector with Fe3O4 nanofluid

In this paper, the influence of operating parameters of plug flow on thermal efficiency of direct absorption solar collector (DASC) using Fe3O4 nanofluid (0.05–0.2 wt%) was experimentally studied, the DASC is a device that directly converts sunlight into heat by using a working fluid with high thermal conductivity. As a result, the outlet temperature and efficiency of DASC was affected by the ratio of length of liquid plug to the inner diameter of the tube, the working time of air compressor, the mass flow rate, the inlet temperature, solar radiation and concentration of the Fe3O4 nanofluid. When the plug flow mode was implemented, the energy gained and stored exhibited a notable enhancement compared to the regular flow mode. Furthermore, the DASC exhibited the highest efficiency when the L/D were 1.7 which was 27.7 % higher than that of regular flow mode. In addition, the inlet temperature was inversely proportional to the efficiency cause the heat loss to the environment.The maximum performance of the direct absorption solar collector was obtained when 0.1 wt% Fe3O4 nanofluid was used as the working fluid with plug flow mode.

Abstract Sa1107: Resuscitation of Lungs after Cardiac Arrest with Ex-Vivo Lung Perfusion: A Bench Study to Minimize Ventilator-Induced Lung Injury through Flow Modulation

Introduction: Lung donation after uncontrolled circulatory death (uDCD) following a witnessed cardiac arrest is feasible after resuscitation and assessment with ex vivo lung perfusion (EVLP). This bench study explores the efficacy of expiratory flow modulation in minimizing damage caused by mechanical power during volume-controlled ventilation within the EVLP procedure. Methods: Donor lungs were simulated using the ASL 5000 lung simulator (IngMar Medical) and ventilated in volume-controlled mode using the ViX-ventilator (KU Leuven), set at 7 breaths per minute with a positive end-expiratory pressure of 5 cmH 2 O. (Figure 1) Baseline measurements were obtained to deliver tidal volumes (VT) of 300, 400, and 500 mL. These measurements were then compared to an intervention where expiratory flow was modulated using an in-house designed device, the flow modulator. Mechanical power (J/min) was calculated using the pressure-volume curve. Differences in power between the baseline and various levels of flow modulation were assessed using a one-sided t-test. Results: No clinically relevant differences were observed in VT delivery between baseline settings and during expiratory flow modulation. (Table 1) However, significant differences in mechanical power were noted between baseline and flow modulation across the three VT settings (p&lt;0.001). The reduction in power varied from 10.9% to 58.5%, depending on the selected VT and the degree of flow modulation applied. Notably, the extent of power reduction increased with the level of flow modulation. Conclusion: Flow modulation in the expiratory circuit during volume-controlled ventilation in a bench set-up does not affect VT delivery and can significantly reduce mechanical power by up to 58.5%. This reduction in mechanical power could potentially reduce iatrogenic damage during EVLP. Consequently, this might extend preservation times and improve the resuscitation outcomes of uncontrolled DCD lungs. Emergency medicine has the opportunity to leverage this vital pool of donor lungs, moving towards a future with minimal transplant waitlists.

IMPROVING METHODS FOR PREDICTING THE STRUCTURE OF GAS-LIQUID FLOW IN HORIZONTAL PIPES

Analysis of existing research on the hydrodynamics of two-phase mixtures allows us to trace the main trends in the development of engineering calculation methods, as well as identify the most promising approaches for developing algorithms for predicting the patterns of gas-liquid flows in horizontal pipes. Predicting the patterns of two-phase flows is necessary to solve a number of applied problems related to the design of field pipeline systems, monitoring of operational parameters during the transportation of well products, calculation of hydraulic pressure drop in pipes, etc. Conventionally, in creating methods for predicting flow regimes in horizontal pipes, there are stages based on empirical approaches, mechanistic modeling and unification of hydrodynamic criteria for assessing the processes of patterns transformations of two-phase flows. Approaches based on the unification of hydrodynamic models of gas-liquid flows are noted as promising directions in the development of hydrodynamic forecasting criteria. The principles of unification consist in bringing to uniformity a mathematical apparatus capable of predicting all possible patterns of gas-liquid flow in vertical, inclined and horizontal pipes based on known volumetric flow rates of liquid and gas. The article proposes the improvement of known unification approaches in the development of criteria for predicting the annular and dispersed-bubble patterns of gas-liquid flow in field pipes. The verification of the obtained algorithms for pattern prediction of annular and dispersed-bubble modes of horizontal gas-liquid flow was carried out.

Biphenyl derived hyper-crosslinked polymer as a metal-free adsorbent for the removal of pharmaceuticals from water

The global concern of emergent aquatic pollutants, especially pharmaceutical contaminants, emphasizes the necessity for metal-free adsorbents to tackle water contamination issues. In this direction, a biphenyl-derived hyper-crosslinked polymer (poly-biph) was utilized as an adsorbent for the removal of ciprofloxacin (CPX) and doxycycline (DOX) from water. Micro-mesoporous hyper-crosslinked polymeric adsorbent (poly-biph) was synthesized by using biphenyl as precursor and formaldehyde dimethyl acetal (FDA) as crosslinker via microwave assisted method. It exhibits specific surface area (SABET) and pore volume of 1088 m2/g and 1.3 cm3/g, respectively. The spectral analysis confirmed the successful crosslinking of biphenyl with the linker FDA. The sorption efficiency of metal-free poly-biph for CPX and DOX was evaluated via batch and continuous flow modes under various operational parameters. poly-biph exhibited swift removal efficiency (>80 %) for CPX and DOX within a min. The batch mode sorption modeling revealed a chemisorption process and remarkable maximum sorption capacity of 470.8 and 425.1 mg/g for CPX and DOX, respectively. The continuous-flow studies of poly-biph revealed the better applicability of the Clark kinetic model with a maximum bed capacity of 313.5 and 372.4 mg/g for CPX and DOX, respectively. Synergistic mechanisms, including π-π interaction, electrostatic interaction, and pore-filling effect, were found to be the main driving forces for the sorptive removal of CPX and DOX onto poly-biph. The findings indicated that poly-biph possesses the ability to effectively eliminate DOX and CPX from the aquatic environment.

Patch-scale habitat dynamics: three metrics to assess ecological impacts of frequent hydropeaking

Human activities significantly alter natural river flows, impacting ecosystem functioning and biodiversity worldwide. Hydropeaking, resulting from intermittent on-demand hydropower generation, introduces sub-daily flow fluctuations exceeding natural variability. While the effects of single hydropeaking events are well-studied, the cumulative impacts of frequent hydropeaking requires further exploration. This study aims to develop metrics that captures changes in habitat dynamics at the patch scale (i.e. individual micro-habitats within the habitat mosaic) due to reoccurring hydropeaking. Using hydrodynamic simulations, we introduce three patch-scale metrics to quantify habitat dynamics with high spatial (0.5 m) and temporal (10 min) resolution: (M1) Habitat probability within patches, assessing spatio-temporal diversity of habitats; (M2) Habitat shifts within patches, evaluating habitat persistence for sessile organisms (e.g. vegetation, invertebrates); and (M3) Spatial shifts of habitats, indicating habitat relocation affecting mobile species (e.g. adult fish). Using eight hydro-morphological scenarios representing different levels of anthropogenic modification of flow and morphology, we demonstrate that these metrics effectively quantify changes in habitat dynamics at patch-scale. The results highlight the ecological relevance of these metrics and their potentially utility for river management. By identifying areas susceptible to ecological impacts, these metrics may serve as tools for hydropeaking mitigation, enabling more targeted and spatially explicit habitat management and restoration.

Modeling Fibrin Accumulation on Flow-Diverting Devices for Intracranial Aneurysms.

The mechanisms leading to aneurysm occlusion after treatment with flow-diverting devices are not fully understood. Flow modification induces thrombus formation within the aneurysm cavity, but fibrin can simultaneously accumulate and cover the device scaffold, leading to further flow modification. However, the interplay and relative importance of these processes are not clearly understood. A computational model of fibrin accumulation and flow modification after flow diversion treatment of cerebral aneurysms has been developed under the guidance of invitro experiments and observations. The model is based on the loose coupling of flow and transport-reaction equations that are solved separately by independent codes. Interaction or reactive terms account for thrombin production from prothrombin stimulated by thrombogenic metallic wires and inhibition by antithrombin as well as fibrin production from fibrinogen stimulated by thrombin and flow shear stress, and fibrin adhesion to device wires and already attached fibrin. The computational model was demonstrated and tested on idealized vessel and aneurysm geometries. The model was able to reproduce the salient features of fibrin accumulation after the deployment of flow-diverting devices in idealized invitro models of cerebral aneurysms. Namely, fibrin production in regions of high shear stress, initial accumulation at the inflow zone, and progressive occlusion of the device and corresponding flow attenuation. The computational model linking flow dynamics to fibrin production, transport, and adhesion can be used to investigate and better understand the effects that lead to fibrin accumulation and the resulting aneurysm inflow reduction and intra-aneurysmal flow modulation.

Microglia modulate cerebral blood flow and neurovascular coupling through ectonucleotidase CD39.

Microglia and the border-associated macrophages (BAMs) contribute to the modulation of cerebral blood flow (CBF), but the mechanisms have remained ill-defined. Here, we show that microglia regulate the CBF baseline and upsurges after whisker stimulation or intracisternal magna injection of adenosine triphosphate (ATP). Genetic or pharmacological depletion of microglia reduces the activity-dependent hyperemia but not the cerebrovascular responses to adenosine stimulation. Notably, microglia repopulation corrects these CBF reactivity deficits. The microglial-dependent regulation of CBF requires the ATP-sensing P2ry12 receptor and the ectonucleotidase CD39 that initiates the breakdown of extracellular ATP. Pharmacological inhibition or microglia-specific deletion of CD39 simulates the CBF anomalies detected in microglia-deficient mice and reduces the rise of extracellular adenosine after whisker stimulation. Together, these results suggest that the microglial CD39-initiated conversion of extracellular ATP to adenosine is an important step in neurovascular coupling and the regulation of cerebrovascular reactivity.

Redox-mediated electrochemical separation of boron ions: Cell design, process optimization, adsorption isotherm, kinetics, and thermodynamics

Boron contamination of various water sources has been increasing in recent years and is receiving worldwide attention for its negative effects on the environment, wildlife, and humans; therefore, its removal is of utmost importance. Considering dwindling water sources and the possibility of the world population soon experiencing water scarcity, effective and innovative technologies must be developed to remove boron ions from water sources. The aim of the present study was to assess a sustainable separation process for the removal of boron ions using an electrochemical flow cell with symmetric redox-active polyvinyl ferrocene (PVF) functionalized carbon nanotube (CNT) electrodes using real-time measurements of the boron adsorption performance in continuous-flow mode while varying the flow rate, cell voltage, and boron concentration. A Box–Behnken experimental design (BBD) was used to improve boron adsorption. The adsorption isotherms, kinetics, and thermodynamics were investigated to further describe the adsorption process. The high R2 value, calculated using a linear and nonlinear procedure, demonstrated that the Langmuir isotherm and pseudo-first order models fit quite well. The maximum adsorption of 60.61 mg/g was observed. The thermodynamic results illustrated that the adsorption of boron ions onto the PVF/CNT electrodes was spontaneous and endothermic under continuous flow mode.