High Flow Rates Research Articles

Comparative Analysis of In Vitro Pumps Used in Cardiovascular Investigations: Focus on Flow Generation Principles and Characteristics of Generated Flows.

A comprehensive analysis of in vitro pumps used in cardiovascular research is provided in this review, with a focus on the characteristics of generated flows and principles of flow generations. The cardiovascular system, vital for nutrient circulation and waste removal, generates complex hemodynamics critical for endothelial cell function. Cardiovascular diseases (CVDs) could be caused by the disturbances in these flows, including aneurysms, atherosclerosis, and heart defects. In vitro systems simulate hemodynamic conditions on cultured cells in the laboratory to study and evaluate these diseases to advance therapies. Pumps used in these systems can be classified into contact and non-contact types. Contact pumps, such as piston and gear pumps, can generate higher flow rates, but they have a higher risk of contamination due to the direct interaction of pump with the fluid. Non-contact pumps, such as peristaltic and lab-on-disk centrifugal pumps, minimize contamination risks, but they are limited to lower flow rates. Advanced pumps including piezoelectric and I-Cor diagonal pumps are focused on improving the accuracy of flow replication and long-term stability. The operational principles, advantages, and some disadvantages of these pump categories are evaluated in this review, while providing insights for optimizing in vitro cardiovascular models and advancing therapeutic strategies against CVDs. The outcomes of the review elaborate the importance of selecting an appropriate pump system, to accurately replicate cardiovascular flow patterns.

Branching and nonbranching intracranial aneurysms in the presence of a persistent stapedial artery and an aberrant internal carotid artery assessed with computational hemodynamics: illustrative case.

The mechanisms underlying the initiation and progression of bifurcation versus lateral wall aneurysms are not well understood. Computational fluid dynamics (CFD) can improve the understanding of these mechanisms and can consequently help identify patients at higher risk for developing aneurysms and monitor them more closely. A 36-year-old man presented with a ruptured anterior communicating artery aneurysm, which was successfully treated with microsurgical clipping. Imaging also revealed a persistent stapedial artery with an elongated and tortuous posterior communicating artery (PComA). Fourteen years later, he was readmitted for a ruptured aneurysm on a PComA loop. CFD helped identify considerable collateral circulation due to the aberrant internal carotid artery (ICA). High flow rates trigger both types of aneurysms, but nuances exist in the hemodynamic mechanisms that drive their growth. Berry aneurysms and lateral wall aneurysms initially start due to a high flow rate, a common underlying cause. However, the formation of true sidewall aneurysms is primarily characterized by locally increased wall shear stress, while the development of berry aneurysms is mainly linked to high local blood pressure at arterial bifurcations. An aberrant ICA can lead to supraphysiological compensatory flow in the anterior and posterior circulation, increasing the risk of intracranial aneurysm formation at both branching and nonbranching sites, underscoring the need for lifelong monitoring. https://thejns.org/doi/10.3171/CASE24421.

Experimental and numerical investigations of liquid cooling plates for pouch lithium-ion batteries considering non-uniform heat generation

Ensuring the thermal safety of lithium-ion batteries requires efficient and reliable thermal management systems. However, the non-uniform heat generation of lithium-ion batteries results in uneven temperature distribution, which complicates the comprehension of the flow pattern design and operating parameter optimization in liquid-based battery thermal management, especially under extreme conditions. This study evaluates the thermal management performance of four classic liquid cooling plate designs for pouch batteries by considering their non-uniform heat generation through the electrochemical-thermal coupled model. Through experiment and numerical simulation, the optimal flow pattern is identified. Subsequently, the capability of the thermal management system, utilizing the best flow design, is further assessed under varying operating conditions. The results indicate that while a higher flow rate marginally enhances cooling, the coolant inlet temperature exerts a more substantial impact on the cooling performance. In addition, the recommended parameter settings for cell-level liquid cooling systems are outlined under extreme conditions. With a 5 C discharge rate and an initial temperature of 35 °C, the recommended coolant temperature range and coolant flow rate range are 20–30 °C and 60–100 mL min−1, respectively. As a typical example of computer-aided engineering, this study reveals the impact of battery non-uniform heat generation on battery temperature performance and provides a critical reference for the optimization of liquid-based battery thermal management systems.

Optimized control of gas temperature and relative humidity during non-invasive respiratory support in preterm infants: A simple and low-cost intervention

Background: During non-invasive respiratory support, administration of gases at high flow rates requires proper air conditioning to avoid upper airways complications. However, closed-loop control of temperature & relative humidity (T&RH) of mixed gases systems with wired-heated circuits are not commonly available in low-middle income countries (LMIC). Thus, a policy for close control of gas T&RH to overcome our system limitations was implemented. The objective of this study was to evaluate the impact of this intervention. Method: Single center retrospective study including preterm infants admitted to a level II unit (June 2019–2020). Close control of gas T&RH was implemented in Dec 2019 and consisted of starting with the heater at a set number higher than previously and followed by adjustments every 6 h based on intermittent temperature checks (target: 36.5°C–37°C). Humidity was controlled by adjusting the water level every 6 h and checking for the presence of condensation. Two groups were identified: infants treated with or without the close T&RH control. Primary outcome was the occurrence of nasal bleeding. Secondary outcomes were adherence to the policy, need to change the original mode of respiratory support or endotracheal intubation. Appropriate statistical tests were applied. Results: A total of 128 neonates were included: 63 managed without and 65 with close gas T&RH control. Rates of nasal bleeding decreased significantly with the close T&RH control, from 30% to 14% ( p = 0.026) despite longer duration of non-invasive support (CPAP: 1.8 ± 1.9 vs 4.3 ± 5.8 days; p = 0.002 and NIPPV: 1.8 ± 1.4 vs 4.2 ± 5.2; p = 0.009). Adherence to the policy was 93%. Changes of the original mode of respiratory support also decreased significantly (14% vs 3%; 0.024) with no intubation. Conclusion: In the absence of advanced and expensive systems, a simple and low-cost intervention to optimize gas T&RH during non-invasive respiratory support in LMIC is feasible and associated with clinical improvements.

Thermochemical heat storage and material behavior of calcium hydroxide fine powder in a fluidized bed reactor

The Ca(OH)2/CaO reaction has attracted much attention in thermochemical heat storage. However, commercial Ca(OH)2 is usually offered as a fine powder that tends to agglomerate in the fluidized bed and affects heat storage performance. The experimental study on these issues is incomplete. In this paper, a fluidized bed thermochemical heat storage test system is built to study the heat storage and release process of Ca(OH)2 fine powder. The experimental results indicate that the water vapor is the primary factor in agglomeration. The increase in heat storage temperature, fluidization velocity, and inlet water flow rate can all reduce reaction time. However, the effect of heat storage temperature on agglomeration is negligible. While a high fluidization velocity can alleviate the agglomeration, a high inlet water flow rate intensifies the agglomeration. The heat storage density decreases by about 12 % after 5 cycles owing to the material loss, while the agglomeration is trending upward. The specific surface area and specific pore volume decrease by 46.59 %, and 13.89 % respectively, which slows down the heat storage process. This work can serve as a reference for alleviating the agglomeration, as well as the operation and adjustment of the fluidized bed.

Experimental and computational assessment of the heat transfer exchange in evacuated tube receiver using helical external fins

This study examines the performance of solar thermal systems with a longitudinal finned tube, utilizing both experimental and computational fluid dynamics (CFD) methods. The University of Technology in Baghdad manufactured two copper tubes, one with a smooth surface and the other with a longitudinal fin, for the experiments. The research examines thermal efficiency and useful energy extraction across varying flow rates of 2, 3, 5, and 6 LPM. The experimental results show significant differences in the performance of the smooth-surfaced tube compared to the helically finned tube at different flow rates. At 2 LPM, the smooth-surfaced tube shows a gradual increase in useful power from 248.7 W at 8:00 to 1506 W at 13:00, which corresponds to available solar energy to the collectors ranging from 2400 W to 3084 W, resulting in a thermal efficiency between 17 % and 20 %.In contrast, the finned tube has higher Qu values, starting at 442.15 W at 8:00 and 538.7 W at 13:00, while Qs range from 2415 W to 3087 W. Thus, the thermal efficiency of this tube ranges from 10 % to 52 %. Conversely, at higher flow rates, both systems show comparable thermal efficiencies. Comparative analysis between the experimental results and the ANSYS results indicates agreement within a reasonable margin of error, confirming the validity of the computational simulation procedure. The CFD results were consistent with the experimental data, showing a similar trend in thermal efficiency and useful energy extraction for both smooth tubes and finned tubes. A higher temperature difference typically indicates greater heat absorption and heat transfer efficiency, reflecting a more efficient use of solar radiation. The error rate between the experimental and ANSYS results was no >12 %. The study confirms the role of longitudinal fins in improving the efficiency of vacuum tube solar collectors.

CFD analysis of microscopic particle separation in low-volumetric classifiers: DPM tracking and experimental validation for enhanced efficiency using geometric modification strategy

The increasing demand for advanced air quality management technologies highlights the need for efficient separators capable of classifying microparticles by size. This study introduces a novel approach of geometric modifications to optimize low-volumetric environmental separators through Computational Fluid Dynamics (CFD) simulations. This study investigated micron particle flow behaviour, vortex strength, and separation chamber design using Lagrangian particle tracking to capture the complex particle–fluid interactions. Key geometry modifications included optimizing internal configurations, such as tube arrangements and discharge tube lengths, which resulted in significantly improved separation efficiency. The CFD simulations were validated against experimental data with flow rates ranging from 10 to 20 LPM (Re = 1008, 1512, 2016), demonstrating flow patterns, vorticity, and particle retention. A major contribution of this study is the particle retention efficiency analysis across a wide range of particle sizes. Particles larger than 10 µm were captured with near-perfect efficiency, while capturing finer particles (1–8 µm) proved more challenging, highlighting areas for future improvement. Notably, increasing the number of separation tubes from 3 to 4 and adjusting their heights led to a 10 % increase in particle retention for particle diameters of 10 and 20 µm. Additionally, higher flow rates, especially at 17 LPM (Re = 1714), increased capture rates for medium-sized particles by prolonging residence times through increased turbulence. This research advances micron particle separation technologies through design optimizations, supported by experimental and numerical analysis. The findings have broad implications for improving the performance of environmental separators in industrial applications, and for future developments in air quality management systems.

Mechanisms of attachment and distribution of Nitzschia and Fragilaria at different flow rates

Algae in rivers will accumulate on the surface of bridges and other structures in water with the increase of time, which will pollute the water environment and cause serious corrosion on the surface of structures. Extensive literature studies have shown that flow rate as the basic hydrodynamic condition significantly affects the growth and aggregation of algae, yet how different flow rate influences the aggregation and distribution of attached algae is relatively unexplored. In this work, used microscopic observation and high-throughput sequencing combined with a field hanging test to compare the mechanism of attachment and distribution of Nitzschia and Fragilaria at the flow rates of 0.794 m/s and 0.538 m/s, respectively. Mechanistic study shows that the high flow rate reduced the species abundance ca.10 % under the same conditions by increasing the interaction between hydrodynamic and gravity. It found an improvement in species distribution uniformity in different places and periods showed by high flow rate when contrasted with low flow rate. This mechanism offers mechanistic insights into preventing corrosion and fouling of attached algae.

An experimental study to evaluate the performance of variable-width channel cold plates for cooling rectangular Li-ion batteries

The limited cooling capacity of cold plates employing conventional channel designs represents a key obstacle in thermal management systems. The persistent growth of the thermal boundary layer and the uneven distribution of flow across the channels are the principal challenges encountered in this context. To overcome these challenges, this study aims to analyse a modified cold plate of obstructed variable-width channels that can improve the hydrothermal performance and temperature uniformity. Different shapes of pin fins and grooves with variable sizes that match the width of the variable-width channels are proposed. Specifically, four types of pin fins–grooves were used: ellipse, drop, rhombus and trapezoid. The traditional cold plate served as a basis for evaluating the performance of new designs of cold plates. In addition to the traditional cold plate, the four proposed designs of cold plates were manufactured from copper. Experiments were conducted with water as a working fluid under a laminar flow for a flow rate range of 0.004–0.04 kg s-1 and a discharge C-rate range of 1C–2C. Results indicated that the use of variable-width channels with all shapes of fins–grooves effectively contributed to improving the heat dissipation of the cold plate, accompanied with an increase in hydraulic pumping power. At the highest flow rate, the best improvement percentage in the Nusselt number of 82.5 % was achieved when trapezoidal pin fins–grooves were used; by contrast, the lowest pumping power increasing percentage of 33.2 % was obtained when elliptical pin fins–grooves were adopted. The best hydraulic/thermal performance was achieved when trapezoidal pin fins were utilised, with the highest figure of merit of 1.685.

Liquid film breakup pattern and optimization of vane-type separator

The formation of liquid film and fragmentation downstream of swirler in vane-type separators, which is the key phenomena affecting the separation efficiency, is not well understood. To reveal the film breakup mechanism and the distribution characteristics of liquid film at the outlet of swirler, a visual vane-type separator test facility has been developed. By high-speed camera from the top, serious film breakup occurs in the rear of arc-vane swirler due to liquid accumulation on the hub and vanes is captured. While both bag breakup and ligament breakup are the dominant film breakup types, bag breakup resulting in divergent secondary droplets prolongs the gas–liquid separation path and is the main threaten to achieve high separation efficiency. New swirler using tilted-flat vanes with micro-pillars are proposed to guide the liquid film to migrate towards the wall of the riser and suppress liquid film fragmentation. Visual observation verified that the liquid film and fragmentation on the hub are significantly reduced. This is consistent with the quantitative measurement of void fraction distribution by wire mesh conductivity sensor (WMS). The average void fraction at the outlet of the new swirler (1.3D above) is increased, especially in low gas flow rate and high fluid flow rate cases, and the maximum increasement is as high as 26.0% compared to the original arc-vane swirler. The results deepen our knowledge about the film structure near the outlet of swirler in vane-type separators and provide guide to the optimization of vanes.

Controlling the Crystalline Quality and Yield of Single‐Walled Carbon Nanotubes via Floating Catalyst Chemical Vapor Deposition Synthesis

AbstractCarbon nanotubes (CNTs) were synthesized by floating catalyst chemical vapor deposition (FCCVD) reactions. The complicated processing parameters that included a precursor solution composition, reaction temperature, flow rate of the carrier gas, weak oxidants, and injection rate of the precursor solution were controlled to synthesize single‐walled carbon nanotubes (SWCNTs) during the reaction process. The effects of the processing parameters were analyzed with respect to the formation of SWCNTs, yield, and the crystallinity in the CNTs structure. The SWCNTs were characterized by the Raman spectroscopy, scanning electron microscope, high‐resolution transmission electron microscopy, and thermogravimetric analysis. A high reaction temperature, high H2 flow rate, low injection rate of solution precursor, and low concentrations of iron catalysts in the reaction were important factors to improve the crystalline quality of the SWCNTs. The purity of the initial product grown by the standard process was more than 90 wt %, with a yield of 0.5 g/h. The average G/D ratio of the initial product was 178, and it had a distinct RBM peak. HRTEM confirmed that the synthesized SWCNTs had high purity and crystallinity. The SWCNTs could be tunable to meet a particular application by varying the reaction conditions.

KATANA - water activation facility at JSI TRIGA, Part II: First experiments

Water as a primary coolant will play an important role in the performance of fusion reactors, as after being irradiated and activated, it causes an ionising radiation field throughout the facility. In direct support of ITER, the KATANA irradiation facility, which utilises a closed-water activation loop and serves as a well-defined and stable high-energy γ and neutron source, was commissioned in 2024 at the TRIGA Mark II research reactor at the Jožef Stefan Institute in Slovenia.A series of first experiments using the KATANA irradiation facility were performed to determine the operational characteristics of the KATANA, i.e. characterisation of the neutron flux within the irradiation component, dose rate measurements, spectrum characterisation of the activated water, and response to a change in reactor power & flow rate. The KATANA facility demonstrated the desired operational characteristics in terms of high and stable water flow rates and high activity values of the observed isotopes 16N, 17N and 19O, which is essential for minimising the experimental uncertainties.The first experiments performed at KATANA provided in-depth knowledge into the operation and capabilities of the facility and essential data to serve as a basis for further, more detailed/benchmark experiments.

Hydrogen as a direct heat exchange fluid in room temperature hydride systems: Numerical study on the desorption process

Abstract Hydrogen, as an energy carrier, is a promising candidate to foster decarbonization. However, its storage poses significant challenges. Common methods, such as compressed gas and liquid hydrogen, have high energy consumption and safety concerns. Recently, solid hydrogen storage in materials like metal hydrides has gained attention for their ability to store hydrogen safely at low pressures and low temperatures. This study aims to develop a numerical model to simulate the performance of metal hydrides using hydrogen as a direct fluid heat exchanger during desorption. The model, formulated as a system of partial differential equations, is implemented in MATLAB with the ODE15s solver and applied to a disk-type lanthanum nickel reactor to minimize pressure drops. Performance is investigated by varying design parameters, including reactor length and diameter, bed porosity, hydride particle diameter, operating pressure and temperature, and hydrogen mass flow rate at the reactor inlet. Additionally, the energy consumption of auxiliary equipment, such as pumping and thermal power, is evaluated. Results show that the system energy requirement is about 8-9% of the hydrogen lower heating value, with most desorption occurring in less than 300 seconds. The reactor dimensions are crucial for fast desorption and low pressure drops, with pumping power under 1 W given the small thickness and flow rate. Particle diameter and porosity have minor impacts, while pressure, temperature, and flow rate are fundamental. High temperatures, low pressures, and high recirculating flow rates favor the reaction, though a trade-off between performance and energy consumption is necessary since all high temperatures high recirculated mass flow rate allows for high consumption.

Manipulating microfluidic freezing phenomena of electrolytes using electromagnetic stimuli

We investigate the transients of freezing of a flowing electrolyte between cold microfluidic domain walls. We explore the novel effect of morphing the solidification characteristics of the flow system using externally applied electric and magnetic fields. The spatiotemporal evolution of solid–liquid (S–L) interface is simulated using arbitrary Lagrangian–Eulerian approach. We show that the solidification rate is highly influenced by advection effects, and for increasingly high liquid flow rates, solidification stops way before the event of channel closure. Due to electro-magneto-hydrodynamic interactions, a substantial decrease in channel closing time is observed with imposed fields. However, a considerably large electric field may lead to a significant increase in Joule heating, which marginally increases the channel closing time. The magnetic field is observed to produce smoother, curved frozen layers. The electric field tends to enhance the solidification rates more uniformly along the channel length, resulting in much flatter S–L front, hence trapping lesser liquid at channel closure. The results reveal that freezing kinetics in microfluidic devices can be morphed by using electric and magnetic fields, governed by the electric field number (En) and Hartmann number (Ha). The findings may be crucial for phase-change based microfluidic-systems, micro-castings, flow freezing valves, and diodes.

Static Characteristics of Hybrid Water-Lubricated Herringbone Groove Journal Bearing

Abstract The hydrodynamic herringbone groove journal bearing (HGJB) performs exceptionally well at high speeds but is limited by a low load-carrying capacity, largely due to the lubrication characteristics of water. To address this issue, a hybrid water-lubricated HGJB is proposed in this study. A lubrication model for the high-speed hybrid water-lubricated HGJB is developed, taking into account turbulence, thermal effects, and tilt. A comparative analysis of the static characteristics is conducted between the hybrid HGJB and both the hydrodynamic HGJB and the hybrid plain journal bearing (PJB). The results show that the proposed hybrid water-lubricated HGJB offers significantly greater load-carrying capacity than the conventional hydrodynamic HGJB, particularly during start-up or at low speeds. For example, when the bearing operates at 1000 rpm with an eccentricity ratio of 0.5, the load-carrying capacity of the water-lubricated hybrid HGJB under a supply pressure of 1.6 MPa reaches 650 N, compared to just 261 N for the water-lubricated hydrodynamic HGJB. Additionally, the hybrid water-lubricated HGJB demonstrates a higher flowrate and lower temperature rise than the traditional hybrid PJB, thanks to the improved pumping effect of the herringbone grooves at high speeds.

Multi-objective optimization of a novel gas-liquid cylindrical cyclone based on response surface methodology

Currently, most major oilfields in China have reached a stage of high water content, where the extracted fluid is often accompanied by significant volumes of associated gas. This situation increases extraction costs and elevates safety risks. To address these challenges, this paper presents an innovative redesign of the traditional gas-liquid cylindrical cyclone (GLCC) by applying composite mechanics to improve the inner cone structure. The new design is tailored for conditions with high gas content and flow rates. Using response surface optimization, the optimal structural parameters for the separator were identified: an inlet area of 881 mm2, a column diameter of 110 mm, and an inner cone height of 189 mm. Furthermore, the study integrates numerical simulation with experimental research to compare and analyze the flow characteristics and separation performance of the GLCC before and after optimization. The results demonstrate that the optimized GLCC achieves a separation efficiency of 93.2 %, an improvement of 21.2 percentage points over the initial design, with a maximum pressure loss of 0.0621 MPa. The experimental findings and numerical simulations show strong agreement, confirming the efficacy of the new design.

Experimental study on the charging and discharging performance of a thermal energy storage unit using low temperature phase change material

The latent heat thermal energy storage (LHTES) unit offers a versatile solution for storing waste heat and solar thermal energy across various temperature ranges. Despite its potential, limited experimental research has been conducted on LHTES units operating at low temperature ranges. This study addresses this gap by experimentally investigating the performance of an LHTES unit using water as the heat transfer fluid (HTF) and myristic acid (PCM) with a phase change temperature of 53–55 °C. The rectangular configuration of the TES unit was chosen for its practical advantages in industrial and residential applications, facilitating efficient space utilization and uniform thermal distribution. Experiments were conducted with various HTF volumetric flow rates (200, 300, and 400 LPH) using a constant temperature heat source. PCM and HTF temperature profiles at three segments of the TES unit were used to evaluate key parameters essential for designing a storage system, including thermodynamic analysis, Nusselt number, stratification analysis, storage/recovery efficiency, and charging/discharging efficiency. These parameters provide valuable insights into the performance of the LHTES unit. The outcomes indicate that increasing the HTF flow rate from 200 to 400 LPH decreases the charging/discharging duration by 40.73 % and 38.24 %, respectively. At the higher flow rate (400 LPH), convective mixing increases, reducing stratified layer stability. Furthermore, increasing the HTF flow rate leads to a reduction in peak Richardson numbers by 31.6 % and 27.8 % during charging/discharging, indicating a transition towards diminished stratification and increased turbulence in the HTF flow. In conclusion, while the TES unit exhibited better performance at a lower HTF flow rate (200 LPH), practical applications demand efficient fast charging and discharging. Despite this, minimal differences in efficiencies, energy, and exergy rates across flow rates suggest practical viability in various test conditions.

Numerical simulation on exhaled aerosol transmission based on realistic oral-nasal structures and temperature distribution

ABSTRACT Respiratory infections are currently understood to be caused by pathogens released through the nose or mouth of an infected individual, and subsequently transmitted to susceptible hosts. These pathogens are enclosed in liquid particles that are aerosolized from the respiratory tract during activities such as breathing, speaking, sneezing, and coughing. These particles vary widely in size, ranging from submicron to several microns. While past research has largely overlooked the human respiratory system, recent analysis has revealed that the actual structure of the nasal cavity significantly influences the prediction of aerosol transmission during exhalation. In this study, computational fluid dynamics (CFD) simulations were conducted to analyze the aerosol transmission generated during exhalation from the nasal and oral cavities. Realistic nasal and oral cavity structures were taken into account, and authentic temperature distributions were applied to the surfaces. Additionally, inhalation conditions for susceptible individuals were established to evaluate the risk of inhalation-generated exposure. Through various simulation scenarios, we separately discussed the impact of environmental wind speed, separation distance, and exhalation flow rate. The simulation results indicate that environmental wind amplifies the complexity of the flow field and the transmission and deposition of particles between two individuals. Under ambient wind velocities of 0.5 m/s and 1 m/s, it was observed that over 80% of the particles with a diameter of 1 µm inhaled through the nasal cavity accounted for the total deposition on the infected individual. Furthermore, high exhalation flow rates exhibited higher deposition ratios at close distances, in line with our expectations. Therefore, it is advisable to minimize close contact as much as possible during periods of frequent respiratory infections, and to wear masks in order to reduce the risk of inhalation exposure. Implications: During the activities such as breathing, speaking, sneezing, and coughing, liquid particles containing pathogens are aerosolized from the respiratory tract and are released from nose or mouth through the nebulization. In this study, we investigated the transmission of aerosols from human exhalation in the outdoor environment, innovatively taking the real oral-nasal structure and the active inhalation of vulnerable people into consideration, and explored the human-to-human transmission of respiratory viruses. The results are beneficial for public health assessment and policy development.

Task-Driven Tailored Covalent Organic Framework for Dynamic Capture of Trace Radioactive CH3 131I under High-Flow Rate Conditions.

The removal of radioactive gaseous iodine is crucial for sustainable nuclear energy development, safe spent fuel management, and secure disposal of radioactive waste and radioactive medical waste. However, the efficient capture of gaseous iodine, particularly methyl iodide, under conditions of low concentration and high-flow rate that are representative of real-world scenarios remains underexplored. Herein, we adopted a "theory-first" strategy to design adsorbents with a superior affinity for methyl iodide. The rigorous theoretical calculations for both physisorption and chemisorption have guided us to rationally design a piperazine-based covalent organic framework material (Pip-COF, Pip = piperazine). The pioneering hot-testing under dynamic conditions, featuring low concentrations of 5 ppm radioactive CH3 131I and a high-flow rate of 600 mL/min, demonstrated Pip-COF's exceptional capture performance. Pip-COF exhibits saturated capacities of 39 mg/g at 75 °C and 78 mg/g at 25 °C, significantly outperforming the previously reported best COF (COF-TAPT, 6 mg/g at 25 °C) in this scenario. The gradual process of methylation and the identification of specific high-affinity sites were elucidated by time-resolved FT-IR spectroscopy and density functional theory (DFT) analysis, consistent with the design philosophy. This study exemplifies rational material design in facilitating the separation of trace pollutants in challenging environments.

The management of high flow arteriovenous fistula and possible solutions.

The development of a high flow rate arteriovenous fistula (AVF) can expose the patient to development of heart failure due to increased cardiac preload and pulmonary hypertension. AVF flow measurement (Qa) is considered a screening tool for AVF surveillance, aiming to evaluate the access dysfunction and prevent complications, like a non-maturation, suspected stenosis, high-flow AVF, and distal ischemia. In the upper arm AVF, a high Qa may develops, which can expose the patient to the risk of high-output heart failure and ischemia. Although, the exact threshold to define high-flow access is not universally accepted, AVF with a Qa of 1-1.5 L/min or cardio-pulmonary recirculation (Qa/CO) >20% are considered at risk. In our work we describe the treatment performed in three patients with high flow AVF treated with DRIL technique with interposition of a Prosthetic Patch, revascularization procedures such as distal inflow revision or RUDI and with innovative technique a "tench snout," removal the previous anastomosis and reconstruction of the integrity of the radial artery at the terminal in pre and post anastomosis. A PTFE prosthetic segment measuring 5 cm in length and 5 mm in diameter was interposed, terminally anastomosed with the efferent cephalic vein and terminally lateral with the radial artery, reducing the anastomosis to approximately 4 mm. All treated patients showed a clear improvement in the clinical picture in particularly heart failure. The calculation of the post-intervention flow rate approximately 1500 mL/min. The patient on hemodialysis with arteriovenous fistula must be constantly monitored with clinical examination, monitoring during the hemodialysis session and color Doppler ultrasound of the AVF with calculation of the flow rate. The surgical technique used for flow reduction is chosen on the surgical experience of each operator with the main objective of preserving the autologous AVF.