Volume Flow Research Articles

Comparisons between full molecular dynamics simulation and Zhang's multiscale scheme for nanochannel flows.

In a very small surface separation, the fluid flow is actually multiscale consisting of both the molecular scale non-continuum adsorbed layer flow and the intermediate macroscopic continuum fluid flow. Classical simulation of this flow often takes over large computational source and is not affordable owing to using molecular dynamics simulation (MDS) to model the adsorbed layer flow, if the flow field size is on the engineering size scale such as of 0.01-10mm or even bigger like occurring in micro or macro hydrodynamic bearings. The present paper uses full MDS to validate Zhang's multiscale flow model, which yields the closed-form explicit flow equations respectively for the adsorbed layer flow and the intermediate continuum fluid flow. Here, full MDS was carried out for the pressure-driven flow of methane in the nano slit pore made of silicon respectively with the channel heights 5.79nm, 11.57nm, and 17.36nm. According to the number density distribution, the flow areas were respectively discriminated as the adsorbed layer zone and the intermediate fluid zone. The values of the characteristic parameters for Zhang's multiscale scheme were extracted from full MDS and input to Zhang's multiscale flow equations respectively for calculating the flow velocity profile and the volume flow rates of the adsorbed layers and the intermediate fluid. It was found that for these three channel heights, the flow velocity profiles calculated from Zhang's model approximate those calculated from full MDS, while the total flow rates through the channel calculated from Zhang's model are close to those calculated from full MDS. The accuracy of Zhang's multiscale flow model is improved with the increase of the channel height. The recent modification of the optimized potential for liquid simulation (MOPLS) model was used to calculate the interaction force between two methane molecules. In order to calculate the interaction force between the wall atoms and the methane molecules accurately, our previous non-equilibrium multiscale MDS was used. The interaction forces between the methane molecule and the wall atom were obtained from the coupled potential function by the L-B mixing rule when the fluid molecules arrived at near wall. The methane molecule diameter was obtained from the radial distribution function by using equilibrium MDS under the same initial conditions. The local viscosities across the adsorbed layer were obtained from the local velocity profile by using the Poiseuille flow method. The motion equation of the methane molecule was solved by the leapfrog method. The temperature of the simulation system was checked by Bhadauria's method, i.e., the system temperature was rectified by the velocities in the y- and z-directions. The flow velocity distributions across the channel height and the volume flow rates through the channel were also calculated from Zhang's closed-form explicit flow equations respectively for the adsorbed layer flow and the intermediate fluid flow. The results respectively obtained from full MDS and Zhang's multiscale flow equations were then compared.

Fluid Mechanics of Gas-Liquid Systems

The study of gas-liquid systems in fluid mechanics is essential for understanding multiphase flows, particularly in industries such as oil and gas field development. This research explores the key parameters that govern the behavior of such systems, including volume flow, velocity, area, dynamic viscosity, and diameter. Volume flow represents the quantity of fluid moving through a system per unit time, while velocity determines the rate at which the fluid particles travel. The cross-sectional area of the conduit directly influences the flow regime, and the dynamic viscosity defines the fluid's internal resistance to flow, significantly impacting pressure drops and flow patterns. The pipe diameter plays a critical role in determining flow characteristics such as Reynolds number and transition between laminar and turbulent flow. By analyzing these factors, this study provides insights into optimizing gas-liquid systems for improved performance and efficiency in industrial applications.

Similar Pathophysiological Mechanisms Between Osteoarthritis and Vascular Disease

Osteoarthritis (OA) is a prevalent, chronic joint disorder affecting millions of people worldwide, characterized by articular cartilage degradation, subchondral bone remodeling, synovial cytokine secretion, and osteophyte formation. OA primarily affects the hips, knees, hands, and spine. Patients with OA exhibit a higher prevalence of cardiovascular comorbidities and potentially important associations between OA and cardiovascular diseases have prompted investigations into potentially similar pathophysiological associations. This review explores the coexistence of atherosclerotic peripheral vascular disease (ASPVD) in OA patients, including evidence from a contemporary study suggesting associations between OA and arterial wall thickness and blood flow changes which are characteristic of early atherosclerosis, and which stimulate reactive pathology in endothelial cells. Observations from this study demonstrate elevated arterial flow volume and increased intima-media thickness in arteries ipsilateral to OA knees, suggesting a potential link between OA and arterial wall disease. We further explore the intricate relationship between the vascular system and skeletal health, highlighting bidirectional interactions among endothelial cells, inflammatory cells, and various bone cells. Mechanical endothelial cell dysfunction is discussed, emphasizing the impact of vessel wall material changes and endothelial cell responses to alterations in fluid shear stress. Inflammatory changes in OA and ASPVD are also explored, showcasing shared pathophysiological processes involving immune cell infiltration and pro-inflammatory cytokines. Additionally, the role of hypofibrinolysis in OA and ASPVD is discussed, highlighting similarities in elevations of the hypercoagulative and hypofibrinolytic factor, plasminogen activator inhibitor (PAI-1). The review suggests a provocative relationship among low-grade chronic inflammation, endothelial dysfunction, and hypofibrinolytic states in OA and ASPVD, warranting further investigation. In conclusion, this review provides an exploration of the possible associations between OA and ASPVD. While the ongoing study’s findings and other reports are observational, they suggest shared pathophysiological processes and emphasize the need for further research to elucidate additional potentially correlative linkages between these conditions. Understanding common molecular pathways may pave a way for targeted interventions that address both OA and ASPVD.

Formation of a uniform velocity profile in the section of a profiled channel of a reference installation

The velocity profiles in gravity and pressure channels of flow diverters in reference installations in the field of liquid flow and quantity measurements are studied. The design shortcomings of reference installations that do not allow obtaining a flow velocity profile close to uniform in the sections of pressure nozzles over a long period of reference installation operation are described. It is shown that the placement of various straightening devices in the profiled channels and pressure nozzles of flow diverters of reference installations does not lead to obtaining a flow velocity profile close to uniform. An approach to profiling the gravity channel of the flow diverter is proposed, which allows obtaining a velocity profile close to uniform. An experimental justification of the hydraulic efficiency of the geometry of the flow part of the profiled channel of the flow diverter of the EU-3 reference installation from the State Primary Special Standard of Units of Mass and Volume of Liquid in a Flow, Mass and Volume Flow Rates of Liquid GET 63-2019 is presented. The influence of the flow velocity profile shape in the section of the profiled channel of the flow switch and the stability of the main hydro- and thermodynamic parameters of the water flow (flow rate, absolute pressure and temperature) in the pressure pipeline on the metrological characteristics of the reference installation is substantiated. Experimental studies of the velocity profile of the free-flow water flow in the section of the profiled channel are performed using high-speed total pressure meters and Pitot tubes. Close to uniform water flow velocity profiles in the section of a profiled channel were obtained for free flow in the range of investigated Reynolds numbers Re=(35...300)·103. The results of maintaining the stability of the specified value of the mass flow rate of water over a long period of time are presented. The equations for calculating the mass of water during transient processes are written down, taking into account the change in the thickness of the water flow and flow rate from zero to specified values. The presented approach and the obtained results are useful for manufacturers of reference installations and are relevant in the design, creation and modernization of profiled channels of flow switches of reference installations.

Comparison between linear and quadratic power take off for a single chamber land-fixed oscillating water column (OWC)

This study examines the influence of turbine response type on the performance of a land-fixed Oscillating Water Column (OWC) under second-order Stokes waves of varying heights. Numerical modelling techniques, including the Finite Element Method, incompressible Reynolds-Averaged Navier–Stokes (RANS) equations with the Shear-Stress Transport (SST) k-ω turbulence model, and an Arbitrary Lagrangian–Eulerian (ALE) scheme, were employed to gain insights into OWC behaviour. The linear turbine consistently displayed reduced efficiency with increasing wave height, maintaining a stable peak non-dimensional wave number (kh). Conversely, the quadratic turbine exhibited peak efficiency within a narrower wave height range, strongly influenced by wave height. Non-dimensional volume flow rate, non-dimensional chamber pressure, chamber volume, and maximum force on the front wall remained unaffected by changes in wave height for the linear turbine. In contrast, the quadratic turbine was notably impacted by variations in wave height. Moreover, the quadratic turbine revealed stronger odd-numbered higher-order harmonic components in both force and pressure due to its non-linear response. Notably, both linear and quadratic response types exhibited sloshing at similar wave numbers, suggesting minimal influence of turbine response on sloshing behaviour. Finally, the derived non-dimensional turbine coefficients proved both turbines could scale OWC models with negligible scaling effects from the turbine.

Elucidating the hemodynamic impact of residual stenosis post-carotid artery stenting: A numerical study.

Residual stenosis (RS) and hemodynamics demonstrate a significant correlation with postoperative in-stent restenosis/thrombosis following carotid artery stenting (CAS). This study endeavors to elucidate the potential associations between RS and adverse postoperative hemodynamic factors. This study utilized 46 patient-specific carotid artery models post-stenting, which were categorized into two groups based on the presence of RS: the normal group (N, n=23) and the RS group (RS, n=23). A comparative analysis was conducted to evaluate the discrepancies in geometry and adverse hemodynamic parameters, alongside investigating the potential correlation between hemodynamic and geometric parameters. The results reveal that a higher reflux flow volume is discernible in the RS group during low-velocity phases of the cardiac cycle, concomitant with an augmented extent of areas exposed to oscillatory shear stress and extended particle residence time. Moreover, the adverse hemodynamic parameters exhibit a positive correlation with the degree of stent expansion, stent length in the common carotid artery (CCA), and the distal slope of the RS. The distal slope and tortuosity of RS significantly influence the development of adverse hemodynamic conditions post-stenting, exacerbating the hemodynamic environment near the stenosis. Interestingly, while an extended stent length in the internal carotid artery (ICA) region improves hemodynamics by reducing flow disturbance, a longer stent in the CCA significantly worsens these conditions. Hence, it is prudent to analyze the characteristics of the local lesion regions to optimize the strategy for stent implantation.

ThP8.3 - From red coded report to Fistula salvage in 2 weeks

Abstract Aim Fistulas and grafts are life line for patients with End stage renal disease (ESRD). However, they frequently fail, and early intervention is recommended to prevent loss of access. The present study aimed to establish waiting times between identification of significant stenosis/thrombus on duplex scan to intervention. Methods In this study we looked at all red coded reports in 2022 to establish their waiting time from red report to a radiological or surgical intervention. We have a traffic light system where patients with fistulas with no stenosis and good volume flow (VF) over >600ml/min are labelled green, labelled amber when there is a <50% stenosis or minor thrombus with VF still around/above 600 ml/min. Red where there is significant stenosis/thrombus. Results 291 patients were identified, 178 patients with significant >50% stenosis/thrombus in fistula, 82 patients with occluded fistulas, 15 patients with significant inflow +/-outflow stenosis/occlusion, 16 patients with e.g. very high VF fistulas/pseudoaneurysms/small vein size +/- <600ml/min VF (maturing fistulas). As a result of red report, 9% of patients received a new fistula and 57% of patients received an intervention to salvage their existing fistula. Interventions included 112 fistuloplasty/venoplasty, 43 surgical thromb ectomy procedures. 58% of patients received an intervention within the first 2 weeks with 3.6% of patients receiving intervention on the same day as red coded report. 34% of patents however did not receive any intervention. Conclusion There is room for further improvement to salvage more fistulas, though 60% of patients did have an intervention within 2 weeks.

A Novel Direct-Expansion Radiant Floor System Utilizing Water (R-718) for Cooling and Heating

While forced-air convective systems remain the predominant method for heating and cooling worldwide, radiant cooling and heating systems are emerging as a more efficient alternative. Current radiant cooling systems primarily rely on hydronic chilled water systems. This study introduces direct-expansion radiant cooling as a novel technique that could enhance the efficiency of radiant cooling and reduce its environmental impact. Water (R-718) has been tested as a refrigerant due to its favorable thermodynamic properties and environmental advantages; however, to the author’s knowledge, it has yet to be tested in direct-expansion radiant cooling. This research investigated several refrigerants, including water (R-718), ammonia (R-717), R-410a, R-32, R-134a, and R-1234yf, for this application. The findings indicate that water demonstrates efficiency comparable to other non-natural refrigerants, making it a promising candidate, given its favorable thermodynamic properties and substantial environmental benefits. Despite challenges such as a high compression ratio necessitating multi-stage compression, a high compressor discharge temperature exceeding 300 °C and requiring specialized blade materials, and a high suction volume flow rate, direct-expansion radiant cooling operates within a different temperature range. Consequently, the compressor discharge temperature can be reduced to 176 °C, and the compression ratio can be lowered to approximately 3.5, making water a more viable refrigerant option for this application.

Human impacts mediate freshwater invertebrate community responses to and recovery from drought

Abstract Drought is an increasing risk to the biodiversity within rivers—ecosystems which are already impacted by human activities. However, the long‐term spatially replicated studies needed to generate understanding of how anthropogenic stressors alter ecological responses to drought are lacking. We studied aquatic invertebrate communities in 2500 samples collected from 179 sites on rivers emerging from England's chalk aquifer over three decades. We tested two sets of alternative hypotheses describing responses to and recovery from drought in interaction with human impacts affecting water quality, fine sediment, water temperature, channel morphology, flow and temporal change in land use. We summarized communities using taxa richness, an index indicating tolerance of anthropogenic degradation (average score per taxon, ASPT) and deviation from the average composition. Responses to drought were altered by interactions with human impacts. Poor water quality exacerbated drought‐driven reductions in taxa richness. Drought‐driven deviations from the average community composition were reduced and enhanced at sites impacted by flow augmentation (e.g. effluent releases) and flow reduction (e.g. abstraction), respectively. Human impacts altered post‐drought recovery. Increases in richness were lower at sites impacted by water abstraction and higher at sites with augmented flows, in particular as recovery trajectories extended beyond 3 years. ASPT recovered faster at sites that gained woodland compared to urban land, due to their greater recovery potential, that is, their lower drought‐driven minimum values and higher post‐drought maximum values. Synthesis and applications. We show that communities in river ecosystems exposed to human impacts—in particular poor water quality, altered flow volumes and land use change—are particularly vulnerable to drought. These results provide evidence that management actions taken to enhance water quality, regulate abstraction and restore riparian land use could promote ecological resilience to drought in groundwater‐dominated rivers such as globally rare chalk streams and other rivers of the Anthropocene, as they adapt to a future characterized by increasing climatic extremity.

A novel wide flow matching approach of hydrogen-powered F-class gas turbine based on multistage installation angle

To achieve excellent power performance of F-class gas turbine when using pure H2 or H2-rich fuel, this work develops a novel and flexible flow matching approach by modifying the turbine multistage installation angle, with obvious features of easy implementation and low cost. An accurate thermodynamic model of heavy-duty gas turbine considering turbine-stage cooling is established and verified by the actual operation data from Ban-Shan power plant, and to investigate variable condition property and emission characteristic of gas turbine with natural gas and H2-rich fuel. Faced with the inefficiency and narrow working area caused by the flow mismatch between 18-stage compressor and 3-stage turbine when natural gas is switched to H2-rich fuel, the scheme of modifying the installation angles of multistage rotary blade and static blade is proposed. By calculating the pressure and temperature at each turbine stage, the gas turbine power, efficiency, Mach number and NOx emission with different H2 concentration are predicted. Results show that, as the H2 concentration increases, the fuel volume flow required to reach the same turbine inlet temperature increases.When H2-rich fuel increases the turbine inlet volume flow by 3.23 %, the cooling effect significantly decreases, and the turbine outlet temperature rises by about 13.60 K, which deviates from the appropriate operating point. The most serious is the phenomenon of over Mach number and airflow blocking at the outlet of the 2-stage and 3-stage turbine static blades. The installation angle variation increases with the increase of H2, and the higher the stage, the bigger the angle change. The gas turbine can be realized the wide flow matching feature corresponding to the installation angle variation of 0.19°/-0.41°, 0.38°/-0.48°, and 0.53°/-0.94°, respectively for all stages static/rotary blades. After re-matching, the maximum fluctuation of rated power and efficiency are 1.5 % and 1.7 %, and the NOx emission will reach the maximum value of 14.3 ppm with 70 % H2. Research work will provide a novel and feasible retrofit scheme for the heavy-duty gas turbine using clean and low-carbon fuel to widen flow matching scenario.

Experimental study of the optimal design and performance of a mixed-flow dew-point indirect evaporative cooler

Evaporative cooling technologies represent a promising alternative to face the emerging cooling energy poverty, owing to their low production and operative costs. High performance can be achieved through more complex designs, such as dew point indirect evaporative cooling (DIEC) systems. Recent literature explores improvements on these systems, like flow configuration, materials, and water distribution. This study proposes a compact mixed-flow DIEC system made of polycarbonate plates covered with two possible wicking materials. Three water distribution systems are also studied. The prototypes are experimentally characterised by varying the inlet air temperature, humidity, volume flow, and working-to-intake air ratio. The best performing design is evaluated in terms of temperature drop, dew-point effectiveness, wet-bulb effectiveness, and cooling capacity. Results are consistent with those in the literature for equivalent heat transfer areas. The use of a wicking material improves the cooling capacity by up to 1.45. The type of material is less relevant, which enables to select the most economic and accessible option. External nozzles for water distribution offers temperature drops of more than 1 °C and better cooling capacities of approximately 100 W than inlet water distributors.

Identifying Cross-Regional Ecological Compensation Based on Ecosystem Service Supply, Demand, and Flow for Landscape Management

Clarifying the issues related to the supply, demand, and flow of ecosystem services is crucial for regional landscape management. This study employs the equivalence factor method and demand index quantification to analyze the supply and demand of ecosystem services in the Zheng-Bian-Luo region in 2000 and 2020. We used hotspot analysis tools and the minimum cumulative resistance model to establish the ecological corridors, identifying the spatial flow paths of ecosystem services in our site. By calculating the flow volume of the key corridor value through the breakpoint formula and field strength theory and combining this with the ratio of the regulating service value, we computed the ecological compensation amount, thereby realizing the value of the ecosystem service. The results indicate that the area of balance between ecosystem service supply and demand gradually decreased and the deficit area in the Zheng-Bian-Luo region increased 43.62% from 2000 to 2020 along with rapid urbanization. The total value flow of ecosystem services by the important ecological corridors in 2000 and 2020 was USD 242.40 million and USD 365.92 million, respectively. In 2020, it was predicted that Luanchuan County would receive ecological compensation totals of USD 237.76 million from each ecological demand area, and mainly from Jinshui District. Our findings support enhancing the quality of the ecological environment and optimizing the landscape management of the Yellow River’s Henan section.

A study on the combined effects of variable viscosity and thermal conductivity on forced convection in bidisperse porous medium

This research focuses on exploring the flow and temperature distribution of forced convection in a channel of horizontally placed parallel plate under the existence of a bidisperse porous medium (BDPM) emphasizing the consequences of viscous dissipation. The temperature-dependent thermal conductivity and viscosity are considered while maintaining the momentum slip and constant wall temperature at the channel walls. Analysis of the dynamics of fluid flow and the temperature distributions in both the fluid and solid phases is conducted by following the two-velocity and two-temperature models in this work. The model governing equations are non-dimensionalized following the relevant dimensionless parameters and the study calculates the temperature and velocity profiles for each phase using the Homotopy Analysis Method (HAM). The obtained temperature and velocity are discussed and explained with the help of graphs. Certain fluids exhibit varying behaviors at different temperatures. Therefore, it is crucial to consider the temperature-dependent physical properties of the fluid for specific applications. This highlights the importance of implementing temperature-dependent physical properties in the analysis. Throughout the investigation, it is discovered that the viscosity parameter has a greater influence on velocity as compared to temperature, the same for thermal conductivity on temperature. The impact of physical parameters including skin friction, volume flow rate, and Nusselt number on both plates are also examined in this study. The findings are discussed, and tables displaying numerical values for various physical characteristics are provided for both the liquid and solid phases. The results obtained were also compared with existing literature, revealing a strong alignment between them.

Superb microvascular ultrasound is a promising non-invasive diagnostic tool to assess a ventriculoperitoneal shunt system function: a feasibility study

The objective of this pilot study was to assess the reliability of superb microvascular ultrasound (SMI) for the measurement of the cerebrospinal fluid (CSF) flow within VPS systems as an indirect sign for shunt dysfunction. Asymptomatic hydrocephalus patients, with a VPS system implanted between 2017 and 2021, were prospectively enrolled in the study. Using SMI, the CSF flow within the proximal and distal catheters were analysed. Before and after pumping the shunt reservoir, intraabdominal free fluid, optical nerve sheath diameter (ONSD), and papilla diameter (PD) were evaluated and correlated with the amount of valve activation. Nineteen patients were included. A flow was detectable in 100% (N = 19) patients in the proximal and in 89.5% (N = 17) in the distal catheter. The distal catheter tip was detectable in 27.7% (N = 5) patients. Free intraabdominal fluid was initially detected in 21.4% (N = 4) patients and in 57.9% (N = 11) at the end of the examination (P = 0.049). ONSD was significantly lower after pump activation (4.4 ± 0.9 mm versus 4.1 ± 0.8 mm, P = 0.049). Both peak velocity and flow volume per second were higher in proximal compared to distal catheters (32.2 ± 45.2 versus 5.6 ± 3.7 cm/sec, P = 0.015; 16.6 ± 9.5 ml/sec versus 5.1 ± 4.0 ml/sec, P = 0.001, respectively). No correlation was found between the number of pump activations and the changes in ONSD (P = 0.975) or PD (P = 0.820). SMI appears to be a very promising non-invasive diagnostic tool to assess CSF flow within the VPS systems and therefore affirm their function. Furthermore, appearance of free intraperitoneal fluid followed by repeated compression of a shunt reservoir indicates an intact functioning shunt system.

Adoption of Multi-Modal Transportation for Configuring Sustainable Agri-Food Supply Chains in Constrained Environments

Agri-food supply chains have the potential to make a significant contribution to achieving sustainable development goals through ongoing improvements in their configurations. A range of strategic, tactical, and operational level decisions pertaining to the design and operation of sustainable supply chains have been studied in the extant literature. However, investigations into the adoption of multi-modal transportation as a strategic decision in the context of agri-food supply chains operating in constrained environments are limited. As such, in this study, the adoption of bi-modal transportation for the domestic vegetable supply chain in a developing country context under certain constraints was examined. A mixed-integer linear programming model was developed to determine the volume and direction of the product flow to achieve the minimum total food-miles and smallest emissions footprint. As a case study, a Sri Lankan mainstream vegetable supply chain was used to investigate the applicability of a combination of truck and railway modes to transport vegetables from farms to retailer locations via economic (consolidation) centers. The adoption of a bi-modal transportation structure demonstrated the potential to reduce food miles by 32%, transportation costs by 36%, contributions to global warming potential by 35%, and empty truck hauls by 38%, compared to a structure with truck-based, uni-modal transportation.

Spatio-Temporal Distribution of Water Availability in Marshyangdi Basin: Hydrological Model Development

This Study has developed a hydrological model for the Marshyangdi river basin in Western Nepal, showing considerable potential for developing water resources and overall national prosperity. The model is also used to characterise hydrology and assess the availability of water resources across different spatial and temporal dimensions, hence improving our comprehension of water availability and its possible applications. The newly developed hydrological model in the Soil and Water Assessment Tool (SWAT) replicates the mean flows, hydrological pattern, and flow duration curve at the basin and 54 sub-basin outputs. Additionally, the model undergoes calibration and validation, employing Sufi-2 to fine-tune hydrological parameters. Based on the data generated by the model, the annual average precipitation (P) in the Marshyangdi basin is projected to be 1843 mm. Approximately 17.88% of the average yearly rainfall is lost via evapotranspiration; however, this varies significantly across different locations and time periods. Contrasting the two, the mountains have a higher moisture level than the Himalayan regions. The predicted average annual flow volume at the basin outflow is 9467.423 million cubic metres (MCM). Examining water shortages, finding regions with excess water, and developing solutions to address the competing needs of agriculture, industry, urban areas, and ecosystems are advantageous. Therefore, this method may improve the effectiveness of strategic planning and the long-term management of water resources.

Flow characteristics of the rip current system adjacent to a coastal vertical structure for irregular waves

Rip currents are common hazards found on many beaches around the world. The present research examines the rip current flow features adjacent to a coastal vertical structure with total reflection function to the incident waves. The laboratory experiments were conducted over the planar beach for both regular and irregular waves to explore the specific phenomenon for the irregular waves, and a higher-order Boussinesq equation model was adopted in the simulations to analyze the formation mechanism of the flow features. The study results show that, the standing wave pattern for the irregular wave is much weaker than that for the regular wave with inducing only one apparent node rip at the first node line in the reflection wave area. Moreover, the specific “single-vortex” flow pattern was formed in the crossing wave field for the irregular wave tests. This specific flow pattern is found essentially induced by the larger wave reflection rate of the vertical structure, which leads to the strong lateral flow against the downstream longshore current. This specific flow pattern prefers to present for the smaller wave incident angles and larger wave heights and periods, and leads to the feeding flow volume rates discharged more in the form of lateral flow. The C-shaped lateral flow is found mainly induced by the longshore gradient of the wave set-up instead of the non-uniform wave radiation stress nearshore.

Perfusion Abnormalities on 24-Hour Perfusion Imaging in Patients With Complete Endovascular Reperfusion.

Perfusion abnormalities in the infarct and salvaged penumbra have been proposed as a potential reason for poor clinical outcome (modified Rankin Scale score >2) despite complete angiographic reperfusion (Thrombolysis in Cerebral Infarction [TICI3]). In this study, we aimed to identify different microvascular perfusion patterns and their association with clinical outcomes among TICI3 patients. University Hospital Bern's stroke registry of all patients between February 2015 and December 2021. Macrovascular reperfusion was graded using the TICI scale. Microvascular reperfusion status was evaluated within the infarct area on cerebral blood volume and cerebral blood flow perfusion maps obtained 24-hour postintervention. Primary outcome was functional independence (90-day modified Rankin Scale score 0-2) evaluated with the logistic regression analysis adjusted for age, sex, and 24-hour infarct volume from follow-up imaging. Based on microvascular perfusion findings, the entire cohort (N=248) was stratified into one of the 4 clusters: (1) normoperfusion (no perfusion abnormalities; n=143/248); (2) hyperperfusion (hyperperfusion on both cerebral blood volume and cerebral blood flow; n=54/248); (3) hypoperfusion (hypoperfusion on both cerebral blood volume and cerebral blood flow; n=14/248); and (4) mixed (discrepant findings, eg, cerebral blood volume hypoperfusion and cerebral blood flow hyperperfusion; n=37/248). Compared with the normoperfusion cluster, patients in the hypoperfusion cluster were less likely to achieve functional independence (adjusted odds ratio, 0.3 [95% CI, 0.1-0.9]), while patients in the hyperperfusion cluster tended to have better outcomes (adjusted odds ratio, 3.3 [95% CI, 1.3-8.8]). In around half of TICI3 patients, perfusion abnormalities on the microvascular level can be observed. Microvascular hypoperfusion, despite complete macrovascular reperfusion, is rare but may explain the poor clinical course among some TICI3 patients, while a detrimental effect of hyperperfusion after reperfusion could not be confirmed.

Magnetohydrodynamic and Aerodynamic Assessment of a 70° Spherecone at Mars and Venus

An electrical conductivity database for continuum flow in a CO2 atmosphere over a 70° spherecone was created using the Data Parallel Line Relaxation Code computational fluid dynamics software to inform development of future magnetohydrodynamic subsystems at Venus and Mars. Sixteen freestream conditions were considered at Mars with atmospheric relative velocities from 5 to 8 km/s and altitudes between 20 and 80 km. Sixteen freestream conditions were considered at Venus with atmospheric relative velocities from 9 to 12 km/s and altitudes between 85 and 115 km. Results indicate that the total electrical conductivity in the flow volume always increases as velocity increases. At low velocities, the electrical conductivity is higher at high altitudes whereas, at high velocities, the electrical conductivity is higher at low altitudes. Three of the 80 km altitude computational fluid dynamics solutions show good agreement with direct simulation Monte Carlo results. In general, computational fluid dynamics predicts thinner shocks, higher electron number density, and similar vibrational temperatures to direct simulation Monte Carlo. The magnetohydrodynamic force was calculated at both Mars and Venus. Results indicate there may not be sufficient control authority to use magnetohydrodynamics as a trajectory control mechanism at Mars without artificially increasing the electrical conductivity of the flow, but there may be appreciable control authority for a drag-modulated aerocapture at Venus.

Trends in Venous Diameter and Brachial Artery Volume Flow of arteriovenous fistula in 12 Weeks Postoperatively

ObjectiveTo explore the trends of venous diameter and brachial artery volume flow (VF) in 12 weeks after arteriovenous fistula (AVF) and the influence of preoperative arterial diameter on this trend. Our goal was to clarify the maturation process within 12 weeks after AVF surgery. MethodsClinical data of 257 patients with end-stage renal disease who had their first radial-cephalic AVF established at our institution from February 1, 2023 to February 1, 2024 were included. The patients were divided into group A (radial artery diameter <1.5 mm), group B (radial artery diameter 1.5-2.0 mm), and group C (radial artery diameter >2.0 mm) according to the preoperative radial artery diameter. After AVF surgery, the artery and vein diameter, brachial artery VF were recorded at 1 day, 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks and 12 weeks. Results1. The venous diameter and brachial artery VF of AVF showed an upward trend, and increased significantly in 1 day-6 weeks postoperatively (P < 0.05),especially between 1 day and 2 weeks, while no significant difference in the increases at 6-12 weeks. 2. Groups B and C were in line with the above trend, whereas the patients in group A showed best growth in 2-4 weeks postoperatively. 3. The natural maturation rates of AVF in groups B and C were significantly better than that of group A at all postoperative time (P＜0.05). ConclusionThe AVF was in a developmentally dominant stage at 6 weeks postoperatively, with 1 day-2 weeks being particularly prominent. The postoperative natural maturation rate of AVF with arteries diameter of<1.5 mm was low, the direct use of such arteries to establish AVFneed careful consideration.