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In recent years, the increasing demand for vibration control has driven the development of viscous damping isolators, and there have been many attempts to apply the shear thickening fluid (STF) system to vibration control to achieve customized damping property according to different application requirements. Previous studies on the performance of STF-based isolators have observed a peculiar "collapse" phenomenon, but researchers have no clear explanation for the mechanism causing this unfavorable phenomenon. The main focus of this work is to explore the nonlinear characteristics and mechanism of STF-based isolators, especially for introducing a novel carbon fiber powder STF system (CFP-STF). The damping mechanism of the CFP-STF isolator is theoretically derived based on Poiseuille's law, the governing equations of arbitrary rheology are solved and demonstrated in details, and the theoretical model is established for multi-scale analysis under multi-frequency loading. To explore the influence of each parameter on the damping coefficient/force–displacement-velocity relationship, attention is paid to the initial viscosity and peak viscosity of the CFP-STF system, and as a result the concept of damping coefficient decrease rate is proposed in this paper. The results show that the the new CFP-STF isolator avoids the "collapse" phenomenon of the force–displacement hysteresis curve at high frequencies, where the damping force does not decrease and the mechanical dissipation tends to increase linearly after the threshold is exceeded, since the viscosity decreases more slowly than the velocity increases with increasing frequency. [ABSTRACT FROM AUTHOR]

The use of wet spirometers, although once common, has greatly declined because these devices measure only static lung volumes and students often face technical issues in their use. In this study, the wet spirometer has been modified to investigate the fundamental laws of flow and different types of lung disease. This modification was achieved by changing the dimensions of the device, printing a scale on the bell, and attaching an airflow control system (ACS) between the corrugated tube and hollow tube of the inner cylinder. The ACS allowed for flow control during the exercises. Two exercises were performed: exercise I compared the parameters measured by the wet spirometer, modified spirometer, and computerized spirometer to determine the suitability of the modification, while exercise II tested the variables affecting flow. These exercises introduce students to data collection, analysis, and the use of statistical tests as they compare various spirometers. Additionally, students gain valuable experience in experimental design by conducting diverse experiments that investigate factors influencing flow dynamics. By plotting the results and participating in small group discussions, students can apply flow principles in respiratory and circulatory systems, offering a hands-on experience that integrates physics and physiology. The modified spirometer facilitated multifaceted topic exploration, surpassing the traditional wet spirometer's capabilities. [ABSTRACT FROM AUTHOR]

Abstract Background We report the occurrence of a severe pulmonary hypertension (PH) in a neonate affected by a left congenital diaphragmatic hernia (CDH). PH in this patient was associated with an abnormal origin of the right pulmonary artery from the right brachiocephalic artery. This malformation, sometimes named hemitruncus arteriosus, has to the best of our knowledge never been reported in association with a CDH. Case presentation A male newborn was hospitalized from birth in the neonatal intensive care unit after prenatal diagnosis of a left CDH. Ultrasound examination at 34 weeks of gestational age evaluated the observed-to-expected lung-to-head ratio at 49%. Birth occurred at 38+ 5 weeks of gestational age. Soon after admission, severe hypoxemia, i.e., preductal pulse oximetry oxygen saturation (SpO2)

This article explores the possibility of using samples with embedded glass capillaries of various diameters as rock-mimicking samples with a-priori known values of the absolute gas permeability coefficients. The measured values of the absolute gas permeability coefficient were compared with those obtained by theoretical calculation. The results of measuring the absolute gas permeability coefficient were obtained using the State primary standard of units of specific gas adsorption, specific surface area, specific pore volume, pore size, open porosity, and gas permeability coefficient of solid substances and materials (GET 210-2019). The theoretical values of the permeability coefficient were obtained by measuring the diameters of the capillaries using an optical microscope. Based on the values of these diameters, the permeability coefficients of the samples with capillaries were calculated according to the combined Poiseuille and Darcy equation. It was proved that the measurement results obtained with the use of GET 210-2019 are consistent with the theoretically calculated values of the permeability coefficient within the uncertainty limits. In accordance with the obtained data, the possibility of utilizing cylindrical samples with embedded glass capillaries for measuring gas permeability coefficients of solid substances and materials has been confirmed. The results of this research will be useful for oil and gas professionals, for example, when performing petrophysical studies and geological exploration. [ABSTRACT FROM AUTHOR]

Key Clinical Message Duplicated femoral veins predispose to venous thrombosis, but patients may present with minimal/no symptoms. The required length of treatment is unclear, but periodic ultrasound surveillance may play a role in the absence of definitive treatment options.

Background: We report the occurrence of a severe pulmonary hypertension (PH) in a neonate affected by a left congenital diaphragmatic hernia (CDH). PH in this patient was associated with an abnormal origin of the right pulmonary artery from the right brachiocephalic artery. This malformation, sometimes named hemitruncus arteriosus, has to the best of our knowledge never been reported in association with a CDH. Case presentation: A male newborn was hospitalized from birth in the neonatal intensive care unit after prenatal diagnosis of a left CDH. Ultrasound examination at 34 weeks of gestational age evaluated the observed-to-expected lung-to-head ratio at 49%. Birth occurred at 38+ 5 weeks of gestational age. Soon after admission, severe hypoxemia, i.e., preductal pulse oximetry oxygen saturation (SpO2) < 80%, prompted therapeutic escalation including the use of high frequency oscillatory ventilation with fraction of inspired oxygen (FiO2) 100% and inhaled nitric oxide (iNO). Echocardiography assessment revealed signs of severe PH and normal right ventricle function. Despite administration of epoprostenolol, milrinone, norepinephrine, and fluid loadings with albumin and 0.9% saline, hypoxemia remained severe, preductal SpO2 inconsistently greater than or equal to 80-85% and post ductal SpO2 lower on average by 15 points. This clinical status remained unchanged during the first 7 days of life. The infant's clinical instability was incompatible with surgical intervention, while chest X-ray showed a relatively preserved lung volume, especially on the right side. This prompted an additional echocardiography, aimed at searching an explanation of this unusual evolution and found an abnormal origin of the right pulmonary artery, which was confirmed on computed tomography angiography subsequently. A change in the medical strategy was decided, with the suspension of pulmonary vasodilator treatments, the administration of diuretics, and the decrease in norepinephrine dose to decrease the systemic-to-pulmonary shunt. Progressive improvement in the infant respiratory and hemodynamic status enabled to perform CDH surgical repair 2 weeks after birth. Conclusions: This case recalls the interest of systematic analysis of all potential causes of PH in a neonate with CDH, a condition frequently associated with various congenital malformations. [ABSTRACT FROM AUTHOR]

Key Clinical Message: Duplicated femoral veins predispose to venous thrombosis, but patients may present with minimal/no symptoms. The required length of treatment is unclear, but periodic ultrasound surveillance may play a role in the absence of definitive treatment options. [ABSTRACT FROM AUTHOR]

We describe a novel technique for the characterization of the mean pore radius of self-ordered porous anodic alumina membranes. We have studied the flow of liquids through cylindrical membrane pores under conditions of very low Reynolds number (Re ≪ 1). We find that the flow data are well-described by Poiseuille's law. Characterization is achieved through the application of the Hägen-Poiseuille equation on flow measurements conducted in a simple and compact experimental setup. This setup allows for the monitoring of flow as a result of the pressure difference between the two sides of the membrane without the use of sophisticated and costly laboratory equipment. The proposed method has been tested by flow experiments using liquids of various viscosities. Good agreement is found between the results obtained from the flow data and the pore radii measured by scanning electron microscopy. Consistent results for the mean pore radius for the same membrane have been obtained in all cases. [ABSTRACT FROM AUTHOR]

In this paper, a generalization of Poiseuille's law for a self-similar fluid flow through a tube having a rough surface is proposed. The originality of this work is to consider, simultaneously, the self-similarity structure of the fluid and the roughness of the tube surface. This study can have a wide range of applications, for example, for fractal fluid dynamics in hydrology. The roughness of the tube surface presents a fractal structure that can be described by the surface fractal noninteger dimensions. Complex fluids that are invariant to changes in scale (self-similar) are modeled as a continuous medium in noninteger dimensional spaces. In this work, the analytical solution of the Navier–Stokes equations for the case of a self-similar fluid flow through a rough "fractal" tube is presented. New expressions of the velocity profiles, the fluid discharge, and the friction factor are determined analytically and plotted numerically. These expressions contain fractal dimensions describing the effects of the fractal aspect of the fluid and of that of the tube surface. This approach reveals some very important results. For the velocity profile to represent a physical solution, the fractal dimension of the fluid ranges between 0.5 and 1. This study also qualitatively demonstrates that self-similar fluids have shear thickening-like behavior. The fractal (self-similarity) nature of the fluid and the roughness of the surface both have a huge impact on the dynamics of the flow. The fractal dimension of the fluid affects the amplitude and the shape of the velocity profile, which loses its parabolic shape for some values of the fluid fractal dimension. By contrast, the roughness of the surface affects only the amplitude of the velocity profile. Nevertheless, both the fluid's fractal dimension and the surface roughness have a major influence on the behavior of the fluid, and should not be neglected. [ABSTRACT FROM AUTHOR]

A firm pubourethral ligament (PUL) is required to prevent the reflex posterior pelvic muscle forces forcibly opening out the posterior urethral wall on effort. A weak or loose PUL elongates on effort and this allows the posterior pelvic muscles to stretch open the posterior urethral wall causing urine loss, "stress urinary incontinence." Such forcible opening out of the urethra exponentially reduces the urethral resistance to flow inversely by the fourth power of the radius (i.e., 16 times). For example, if the radius doubles in size, the bladder pressure required for urine to flow out decreases by a factor of 16, from say, 160 to 10 cm H2O. A midurethral sling reinforces PUL to prevent the urethra opening out, thereby restoring both the distal urethral and bladder neck closure mechanisms. [ABSTRACT FROM AUTHOR]

In this paper, a generalization of Poiseuille’s law for a self-similar fluid flow through a tube having a rough surface is proposed. The originality of this work is to consider, simultaneously, the self-similarity structure of the fluid and the roughness of the tube surface. This study can have a wide range of applications, for example, for fractal fluid dynamics in hydrology. The roughness of the tube surface presents a fractal structure that can be described by the surface fractal noninteger dimensions. Complex fluids that are invariant to changes in scale (self-similar) are modeled as a continuous medium in noninteger dimensional spaces. In this work, the analytical solution of the Navier–Stokes equations for the case of a self-similar fluid flow through a rough “fractal” tube is presented. New expressions of the velocity profiles, the fluid discharge, and the friction factor are determined analytically and plotted numerically. These expressions contain fractal dimensions describing the effects of the fractal aspect of the fluid and of that of the tube surface. This approach reveals some very important results. For the velocity profile to represent a physical solution, the fractal dimension of the fluid ranges between 0.5 and 1. This study also qualitatively demonstrates that self-similar fluids have shear thickening-like behavior. The fractal (self-similarity) nature of the fluid and the roughness of the surface both have a huge impact on the dynamics of the flow. The fractal dimension of the fluid affects the amplitude and the shape of the velocity profile, which loses its parabolic shape for some values of the fluid fractal dimension. By contrast, the roughness of the surface affects only the amplitude of the velocity profile. Nevertheless, both the fluid’s fractal dimension and the surface roughness have a major influence on the behavior of the fluid, and should not be neglected.

Implant devices for micro invasive glaucoma surgery (MIGS) are gaining increasing acceptance in clinical ophthalmic use. The implant requirements are defined in international standards, such as ANSI Z80.27-2014 and the 2015 Guidance for Industry and Food and Drug Administration Staff "Premarket Studies of Implantable Minimally Invasive Glaucoma Surgical (MIGS) Devices". The exact fluid-mechanical characterization represents a crucial part of the development and approval of innovative implant devices for MIGS. The current work describes the development and preliminary validation of a versatile test facility for pivotal characterization of glaucoma drainage devices. The test setup enables a pressurization of test specimens by means of two water columns. For measurement of pressure and volume flow, a pressure transducer and a total of three liquid flow meters were implemented into the test setup. Validation was conducted by experimental pressureflow characterization of standardized tubes and a comparison to theoretical results according to Hagen Poiseuille's law for stationary laminar flow of a Newtonian fluid in a tube with a circular cross section. Ultrapure water at (35 ± 2) °C was used for the analyses. The developed test setup potentially enables pressure-flow characterization of test specimens in a wide flow range of 0 μl min-1 ≤ Q ≤ 5.000 μl min-1. The preliminary test facility validation showed a good agreement of measured and theoretical volume flow characteristics as a function of the pressure difference, in the currently investigated flow range of Q < 80 μl min-1. The developed test facility is suitable for pivotal in vitro characterization of glaucoma drainage devices. Future investigations will focus on the final validation of the whole flow range and on the use of the test facility for fluid-mechanical characterization of self-developed prototypes of glaucoma microstents as well as commercially available glaucoma drainage devices. [ABSTRACT FROM AUTHOR]

Underactive bladder (UAB) is essentially an inability of the bladder to properly empty. UAB symptoms, when they co-occur with posterior fornix syndrome (PFS) symptoms (urge, frequency, nocturia, chronic pelvic pain), can be cured/improved, surgically by uterosacral ligament (USL) repair, non-surgically, by devices which give mechanical support of the USLs or strengthening pelvic muscle and ligaments with squatting-based exercises. The pathogenic pathway from weak USLs to UAB (and PFS) is that, when the muscles which externally open the posterior wall of the urethra contract against lax USLs, their contractile force weakens, and they cannot open the urethra adequately. The detrusor then contracts against a relatively unopened urethra to cause obstructive symptoms (i.e., UAB) such as slow stream, intermittent stream (stopping and starting), hesitancy (difficulty starting), feeling of incomplete emptying, and post-micturition dribble. Co-occurrence of PFS symptoms indicates that UAB may be part of the PFS, with USL causation, which can be tested by a tampon or probe in the posterior fornix. If the emptying (and other) PFS symptoms improve, it is a sign that UAB, and Fowler's syndrome (FS) can potentially be cured or improved by USL repair. Following USL repair, many studies have recorded very significant improvement in emptying symptoms, and objective tests, for example, postvoid residual (PVR), decreased natural bladder volume, and decreased emptying time. FS and UAB are most likely a part of the PFS and, therefore, potentially curable by USL repair., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://atm.amegroups.com/article/view/10.21037/atm-23-1775/coif). The series “Integral Theory Paradigm” was commissioned by the International Society for Pelviperineology without any funding or sponsorship. The authors have no other conflicts of interest to declare., (2024 Annals of Translational Medicine. All rights reserved.)

• Permeability of spun high strength concrete material during mechanical loading was tested. • Novel test equipment is designed for simultaneous mechanical loading and permeability test. • Roughness of crack in spun high strength concrete material is estimated. The pretensioned spun high strength concrete pipe pile (PHC pipe pile) is widely applied in important infrastructures of off-shore zones due to its low permeability and high capacity. During the construction process and the whole service period of PHC pipe piles, the damage is inevitably caused by many reasons, which may eventually cause the early durability failure of piles. Many researches have been conducted to study the change in permeability of normal concrete due to mechanical damage. However, the relation between permeability and damage of spun high strength concrete (SHSC) is still not been studied. To quantitively investigate the change of permeability of SHSC, a series of specimens of PHC pipe piles were tested for the change of permeability during mechanical loading process in this study. As a result, the relation of stress and permeability of spun high strength concrete as well as the crack roughness of the SHSC is obtained for efficient application in engineering. Before the 40% stress ratio, the permeability of the SHSC is slightly decreased as the compressive stress increases. The mean value and standard deviation of the intrinsic permeability of the SHSC are increased as the compressive stress loading reaches the peak stress. The order of magnitude of the crack roughness ξ can be taken as 10 - 4 for engineering application. Compared with the vibrate-casted concrete, the crack roughness ξ is smaller, indicating that the crack surface of SHSC is rougher than the vibrate-casted concrete. [ABSTRACT FROM AUTHOR]

The 1/20 venous line has long been the drainage tubing diameter of choice for adult patients undergoing cardiac surgery. However, several programs use a smaller diameter venous line when used in conjunction with kinetic-assisted venous drainage or vacuum-assisted venous drainage. In 2014, our perfusion team made an institution-wide effort to miniaturize the cardiopulmonary bypass (CPB) circuit for children. One of our changes was the transition to a 3/8" diameter venous line for drainage, even in our larger patients (up to 80 kg). We reviewed the current literature on this topic and delineated the various parameters required to be able to use the 3/8" venous line with gravity drainage with the aim of using it on patients up to 115 kg with the appropriate venous reservoir. We have successfully used the 3/8" venous line in more than 40 of our larger patients (35-90 kg) without the need for assisted venous drainage. We were able to reduce CPB prime from 625 ± 118 to 425 ± 52 mL before retrograde autologous priming (RAP)/venous autologous priming (VAP). The prime was further reduced to 325 6 66 mL after RAP/VAP. Homologous blood utilization was reduced from 217 ± 311 mL to 27 ± 77 mL. Both results were statistically significant. We hypothesize that taking into account two of the parameters of Poiseuille's law, namely length and diameter, it is possible to safely drain large children and mid-size adults via gravity venous drainage and the 3/8" venous line. This technique allows reducing prime volume, simplifies CPB circuits with increased safety and potentially reduces the need for homologous blood transfusion. [ABSTRACT FROM AUTHOR]

Highlights • A damage model based on standard and non-standard plasticity is described. • The permeability tensor of cracked brittle materials is computed anisotropically. • A reversed Rankine criterion is used to manage the crack reclosure processing. • The permeability can decrease as the crack reclose. • The flow rate is computed through a concrete sample loaded and then unloaded. • Permeability can be modelled accurately thanks to the crack reclosure processing. Abstract A macroscopic model intended to predict the change of permeability with respect to cracking is described. This development allows both diffuse and localized damage to be considered when computing the permeability. In compression, diffuse microcracking is initiated with respect to the material dilatancy. In this stage, the model adopts Poiseuille's law and uses the transverse expansions obtained with a non-associated Drucker-Prager yield function to compute the anisotropic permeability components. In tension, Poiseuille's law is also used to compute the flow rate through the localized crack. The permeability model uses the orthotropic crack opening information obtained by the mechanical model to compute the anisotropic permeability tensor. In addition, a reversed Rankine criterion is used to manage the localized crack reclosure processing and allows the principal crack opening and its associated permeability components to decrease. Finally, the model is used to simulate the flow rate through a real concrete specimen that has been subjected to tensile loading and then unloaded. With this application, the contribution of the crack reclosure processing to the permeability variations can be highlighted and utility of modelling crack reclosure accurately is demonstrated. [ABSTRACT FROM AUTHOR]

Pressure Injectors are used routinely in diagnostic and interventional radiology. Advances in medical science and technology have made it is imperative for both diagnostic as well as interventional radiologists to have a thorough understanding of the various aspects of pressure injectors. Further, as many radiologists may not be fully conversant with injections into ports, central lines and PICCs, it is important to familiarize oneself with the same. It is also important to follow stringent operating protocols during the use of pressure injectors to prevent complications such as contrast extravastion, sepsis and air embolism. This article aims to update existing knowledge base in this respect.

We consider the nonstationary motion of a viscous incompressible micropolar uid having a prescribed ux in an infinite cylinder. The global existence and uniqueness result for the generalized time-dependent Poiseuille solution is provided by means of semidiscretization in time and by passing to the limit from discrete approximations. [ABSTRACT FROM AUTHOR]

In this work, the water permeability of the cracked concrete has been investigated. Three types of cylindrical specimens with different fiber content were pre-cracked by the feedback controlled splitting test, and the specimens without any fiber reinforcement were also studied as reference. The water permeability of the specimens with different crack width was measured by hydraulic permeability test. The coordinate data of the crack surface was collected by the self designed data acquisition system, the total crack length and surface area of the samples were analyzed, the crack geometry (tortuosity and roughness) was evaluated quantitatively. A modified factor ξ was introduced to the Poiseuille law to verify the permeability of the cracked specimen. The results showed that with the addition of macro steel fibers, the deformability of the specimens was improved significantly and the crack width could be controlled. The coefficient of the water permeability of the specimens was declined by fiber addition, the modified Poiseuille law could be used to evaluate the water permeability of the cracked concrete, the modified factor ξ decreased with the increasing of fiber dosage. The crack tortuosity and surface roughness increased obviously with the addition of steel fiber. [ABSTRACT FROM AUTHOR]

A number of experiments on fluid flow at the micro/nano-scale have demonstrated that flow velocity obviously deviates from the classical Poiseuille's law due to the micro forces between the wall and the fluid. Based on an oil--water two-phase network simulation model, a three-dimensional pore-scale micro network model with solid--liquid interfacial effects was established. The influences of solid--liquid interface effects including van der Waals force and wettability on the residual oil distribution and relative permeability were investigated through microscopic simulation. The effects of pore radius, pore--throat size ratio, shaping factor, and coordination number on the residual oil distribution were analyzed at the same time. The results showed that the oil recovery would be overestimated by about 4% without van der Waals force in a water-wet reservoir. The impact of van der Waals force on water-wet reservoirs was significantly obvious in contrast with oil-wet reservoirs. In addition, the residual oil distribution was significantly influenced by pore radius in water-wet reservoir, comparatively influenced by pore--throat size ratio in oil-wet reservoir. The present study illustrates the successful application of three-dimensional micro network models considering solid--liquid interfacial effects, and provides new insights for oil recovery enhancement. [ABSTRACT FROM AUTHOR]

• A modified K–C equation considering the Poiseuille's law is presented. • Poiseuille's law is modified by adding coefficients to consider changed section. • Predicting formulas of the parameters in the modified K–C equation are discussed. • The modified K–C equation predicts hydraulic conductivity of sand and clay well. The Kozeny–Carman (K–C) equation based on Poiseuille's law is an efficient theoretical equation predicting hydraulic conductivity. Some modified K–C equations were proposed focusing on obtaining the uncertainty parameters in the original K–C equation. However, assumptions of some modified K–C equations are inconsistent with Poiseuille's law. This study proposes a new modified K–C equation considering the derivation principle of the original K–C equation. By applying Poiseuille's law in porous media, the concept of 2D porosity (ε) and a correction coefficient for permeation (f) are presented. During the derivation process, each section's void distribution is assumed to be similar, and void pipes in various directions share similar characteristics, because the effective porosity (n e) is approximately equal to ε only when the change in the cross-section in porous media is small. The parameters in the new modified K–C equation include specific surface area (S 0), tortuosity (1/cosθ), and n e. The prediction formulas of n e are presented according to the soil mineral and bound water features. The prediction formulas for S 0 and 1/cosθ are deduced and verified by comparing them with established formulas proposed by other researchers and experimental data. The new modified K–C equation is adequate for predicting hydraulic conductivity for clay and sand by comparing it with the experimental value and theoretical equations, including the original and other established modified K–C equations. [ABSTRACT FROM AUTHOR]

A fractal permeability model coupling non-flowing boundary-layer effect for tight oil reservoirs was proposed. Firstly, pore structures of tight formations were characterized with fractal theory. Then, with the empirical equation of boundary-layer thickness, Hagen-Poiseuille equation and fractal theory, a fractal torturous capillary tube model coupled with boundary-layer effect was developed, and verified with experimental data. Finally, the parameters influencing effective liquid permeability were quantitatively investigated. The research results show that effective liquid permeability of tight formations is not only decided by pore structures, but also affected by boundary-layer distributions, and effective liquid permeability is the function of fluid type, fluid viscosity, pressure gradient, fractal dimension, tortuosity fractal dimension, minimum pore radius and maximum pore radius. For the tight formations dominated with nanoscale pores, boundary-layer effect can significantly reduce effective liquid permeability, especially under low pressure gradient. [ABSTRACT FROM AUTHOR]

The vascular system is arguably the most important biological system in many organisms. Although the general principles of its architecture are simple, the growth of blood vessels occurs under extreme physical conditions. Optimization is an important aspect of the development of computational models of the vascular branching structures. This review surveys the approaches used to optimize the topology and estimate different geometrical parameters of the vascular system. The review is focused on optimizations using complex cost functions based on the minimum total energy principle and the relationship between the laws of growth and precise vascular network topology. Experimental studies of vascular networks in different species are also discussed. [ABSTRACT FROM AUTHOR]

Objective: Recipient vessel caliber may be the singlemost important variable for flow to free tissue transfer. We performed cadaveric dissection of the external carotid artery and its branches to analyze average diameter in order to determine an algorithm for recipient vessel selection in head and neck reconstruction. Methods: The external carotid artery and branches were exposed on 3 lightly embalmed male human cadavers, aged 82 to 85 years. Each vessel was dissected, and luminal diameters were recorded with calipers. Results: The proximal ECA had the greatest average diameter (4 ± 0.6 mm) and potential flow; followed by distal ECA (2.85 ± 0.4 mm) facial (2.0 ± 0.6 mm), lingual (1.65 ± 0.6 mm), superior thyroid (1 ± 0.3 mm), and superficial temporal (0.85 ± 0.4 mm). There was a trend towards size variation between sides of the same cadaver. Conclusion: The external carotid artery has the greatest internal diameter and potential blood flow. It should be considered, when feasible, especially for defects of the upper third of the head. For defects of the lower third, the facial artery and the lingual artery should be utilized before the smaller diameter superior thyroid artery. Vessel selection is more challenging in the setting of radiation therapy, complex trauma, and prior neck surgery. In these settings, it is useful to have knowledge of the vascular anatomy and an objective algorithm for recipient vessel selection. [ABSTRACT FROM AUTHOR]

On the basis of Kedem-Katchalsky equations a mathematical analysis of volume flow (Jv) of a binary solution through a membrane (M) is presented. Two cases of transport generators have been considered: hydrostatic (Δp) as well as osmotic (Δπ) pressure difference. Based on the Poiseuille's law we derive the formula for the membrane filtration coefficient (Lp) which takes into account the membrane properties, kinetic viscosity and density of a solution flowing across the membrane. With use of this formula we have made model calculations of the filtration coefficient Lp and volume flow Jv for a polymer membrane in the case when the solutions on both sides of the membrane are mixed.

In this Letter, we report experimental and theoretical studies of Newtonian fluid flow through permeable media with fractal porosity. Darcy flow experiments were performed on samples with a deterministic pre-fractal pore network. We found that the seepage velocity is linearly proportional to the pressure drop, but the apparent absolute permeability increases with the increase of sample length in the flow direction L . We claim that a violation of the Hagen–Poiseuille law is due to an anomalous diffusion of the fluid momentum. In this regard we argue that the momentum diffusion is governed by the flow metric induced by the fractal topology of the pore network. The Darcy-like equation for laminar flow in a fractal pore network is derived. This equation reveals that the apparent absolute permeability is independent of L , only if the number of effective spatial degrees of freedom in the pore-network ν is equal to the network fractal (self-similarity) dimension D , e.g. it is in the case of fractal tree-like networks. Otherwise, the apparent absolute permeability either decreases with L , if ν < D , e.g. in media with self-avoiding fractal channels, or increases with L , if ν > D , as this is in the case of the inverse Menger sponge. [ABSTRACT FROM AUTHOR]

In this work, a mathematical model has been developed for vacuum membrane distillation incorporating molecular diffusion–Knudsen diffusion–Poiseuille flow and validated with the experimental data. The feed-side membrane surface temperature used in mathematical model was estimated by computational fluid dynamics modeling. The effects of different operating parameters such as feed flow rate, feed bulk temperature, inlet concentration, and permeate-side pressure on water flux and salt rejection have been studied using PTFE membrane. It has been shown that with variation in feed flow rate from 0.5 to 2 lpm, the permeate flux increased from 20.1 to 25.6 kg/m2 h. Similarly, with increase in feed bulk temperature from 40 to 60°C, the permeate flux increased from 2.10 to 26.6 kg/m2 h. The permeate flux showed the variation from 17.8 to 19.5 kg/m2 h on decreasing permeate pressure from 7 to 5.5 kPa. No significant effect of feed salt concentration was observed on permeate flux. More than 99% rejection was obtained at the feed salt concentration of 40,000 ppm of NaCl. Few runs were also carried out by taking multi-ion feed (Ca++, Mg++, Na+, K+, Cl−,, Fe++,, F−) equivalent to that in ground water; in which case also more than 99% rejection was obtained. [ABSTRACT FROM AUTHOR]

In this work we analyze the capillary filling dynamics of non-Newtonian fluids that can be modeled with a power law constitutive equation. We solve the Poiseuille equations for an hydrophilic closed channel where capillary pressures drives the fluid in until a rest position given by the barometric pressure is reached. We show that this dynamics can be used to measure both the coefficient k and exponent n , that describes the power law fluid viscosity and we ran tests on Soda Lime Glass microchannels. Using a simple experimental setup with a USB Microscope and a custom image processing software we were able to measure the power law parameters of whole blood, wall varnish and DI water. The exponents were also obtained from the velocity profiles inside the microchannel using a custom μPIV setup matching both results with those measured with a standard Brookfield Rotational Microviscometer. [ABSTRACT FROM AUTHOR]

A quantitative comparison of the internal diameters of cerebral feeder arteries (internal carotid and vertebral) and the aorta in developing non-human eutherians, metatherians and monotremes has been made, with the aim of determining if there are differences in cerebral arterial flow between the three infraclasses of mammals such as might reflect differences in metabolism of the developing brain. There were no significant differences between eutherians and metatherians in the internal radius of the aorta or the thickness of the aortic wall, but aortic internal radius was significantly smaller in developing monotremes than therians at the < 10 mm body length range. Aortic thickness in the developing monotremes also rose at a slower rate relative to body length than in metatherians or eutherians. The sums of the internal calibres of the internal carotid and vertebral arteries were significantly lower in metatherians as a group and monotremes compared with non-human eutherians at body lengths up to 20 mm and in metatherians at > 20 mm body length. The internal calibre of the internal carotids relative to the sum of all cerebral feeder arteries was also significantly lower in monotremes at < 10 mm body length compared with eutherians. It was noted that dasyurids differed from other metatherians in several measures of cerebral arterial calibre and aortic internal calibre. The findings suggest that: (i) both aortic outflow and cerebral arterial inflow may be lower in developing monotremes than in therians, particularly at small body size (< 20 mm); (ii) cerebral inflow may be lower in some developing metatherians than non-human eutherians; and (iii) dasyurids have unusual features of cerebral arteries possibly related to the extreme immaturity and small size at which they are born. The findings have implications for nutritional sourcing of the developing brain in the three infraclasses of mammals. [ABSTRACT FROM AUTHOR]

Quantifying fluid flow through porous media hinges on the description of permeability, a property of considerable importance in many fields ranging from oil and gas exploration to hydrology. A common building block for modeling porous media permeability is consideration of fluid flow through tubes with circular cross section described by Poiseuille's law in which flow discharge is proportional to the fourth power of the tube's radius. In most natural porous media, pores are neither cylindrical nor smooth; they often have an irregular cross section and rough surfaces. This study presents a theoretical scaling of Poiseuille's approximation for flow in pores with irregular rough cross section quantified by a surface fractal dimension Ds2. The flow rate is a function of the average pore radius to the power 2(3- Ds2) instead of 4 in the original Poiseuille's law. Values of Ds2 range from 1 to 2, hence, the power in the modified Poiseuille's approximation varies between 4 and 2, indicating that flow rate decreases as pore surface roughness (and surface fractal dimension Ds2) increases. We also proposed pore length-radius relations for isotropic and anisotropic fractal porous media. The new theoretical derivations are compared with standard approximations and with experimental values of relative permeability. The new approach results in substantially improved prediction of relative permeability of natural porous media relative to the original Poiseuille equation. [ABSTRACT FROM AUTHOR]

The embryonic and early fetal human brain is known to undergo extraordinary expansion of its cellular population during embryonic and early fetal life, and is critically dependant on a steady supply of nutrients and oxygen for proper brain development. Quantitative analysis of the internal radius of the aorta and cerebral arteries in a range of eutherian mammals has been used to compare arterial flow to the developing human brain with that to the brains of non-human eutherians. Human embryos showed a much steeper rise of internal radius of the aorta with increasing body size than the embryos of non-human eutherians, but the thickness of the aorta rose at the same pace relative to body size in both humans and non-humans, suggesting that aortic pressure is similar in all eutherian embryos of a similar size. The sums of internal radii of both the internal carotids and vertebral arteries of human embryos raised to the fourth power were much lower at embryonic stages (less than 22 mm body length) than in non-human eutherians, were similar between humans and non-humans at 22-30 mm body length, and exceeded the non-humans at body lengths of more than 30 mm. The relative size of the internal calibre of the cerebral feeder arteries (internal carotid and vertebral) to the aorta did not change between embryonic and fetal sizes in either humans or non-humans. The findings suggest that the developing human brain may actually receive less blood flow at embryonic sizes (less than 22 mm body length) than do other mammalian embryos of a similar body size, but that internal carotid and vertebral flow is higher in human fetuses (body length greater than 30 mm) than in developing non-humans of the same body size. Increased flow to the developing human brain relative to non-humans is achieved by simultaneous increases in both aortic and cerebral feeder artery internal calibre. [ABSTRACT FROM AUTHOR]

Relative permeability as an important petrophysical parameter is often measured directly in the laboratory or obtained indirectly from the capillary pressure data. However, the literature on relationship between relative permeability and resistivity is lacking. To this end, a new model of inferring two-phase relative permeability from resistivity index data wav derived on the basis of Poiseuille's law and Darcy's law. The wetting phase tortuosity ratio was included in the proposed model. The relative permeabilities computed from the capillary pressure data, as well as the experimental data measured in gas-water and oil-water flow condition, were compared with the proposed model. Both results demonstrated that the two-phase permeability obtained by proposed model were generally in good agreement with the data computed from capillary pressure and measured in the laboratory. The comparison also showed that our model was much better than Li model at matching the relative permeability data. [ABSTRACT FROM AUTHOR]

Pressure Injectors are used routinely in diagnostic and interventional radiology. Advances in medical science and technology have made it is imperative for both diagnostic as well as interventional radiologists to have a thorough understanding of the various aspects of pressure injectors. Further, as many radiologists may not be fully conversant with injections into ports, central lines and PICCs, it is important to familiarize oneself with the same. It is also important to follow stringent operating protocols during the use of pressure injectors to prevent complications such as contrast extravastion, sepsis and air embolism. This article aims to update existing knowledge base in this respect. [ABSTRACT FROM AUTHOR]

Fluids dynamic is one of the main applications of PDE in physics. In the paper, the non-stationary Stokes problem with a given flux condition is considered. The problem is analyzed in the three dimensional infinite domain (pipe) which is periodic with respect to one of the axis. The aim of the article is to prove the existence and uniqueness of the Poiseuille type solution. For solving the problem, the Galerkin approximation method is chosen, and the convergence of the constructed series and the uniqueness of the solution is proved. Under the flux condition, the unique existence of the axial pressure drop function is proved. [ABSTRACT FROM AUTHOR]

Ionic liquids are increasingly attracting the attention of researchers in both academia and industry. However, research into ionic liquids is mainly limited in chemistry, and the electromagnetic characteristics and microfluidic/optofluidic applications of ionic liquids have been rarely studied. Here, ionic liquids are used as a new type of fluid material for microfluidics/optofluidics, and the research on magnetohydrodynamic (MHD) microfluidic drive of ionic liquids is conducted using hydrophilic [bmim]BF4 and hydrophobic [bmim]NTf2. The experimental study shows that ionic liquids can be driven by Lorentz force to induce laminar flow. The flow rates of [bmim]NTf2 are 2.7 and 7.8 μl/s at applied direct-current potentials of 6 and 8 V, respectively, in a 0.4-T magnetic field. The experimental results of the two ionic liquids and electrolytes are compared. Moreover, the experimental results are compared with the theoretical data calculated using a numerical simulation and Poiseuille's law, and the limitation of Poiseuille's law is pointed for the MHD drive. The conducted research can promote the application of ionic liquids in microfluidics or optofluidics. [ABSTRACT FROM AUTHOR]

A firm pubourethral ligament (PUL) is required to prevent the reflex posterior pelvic muscle forces forcibly opening out the posterior urethral wall on effort. A weak or loose PUL elongates on effort and this allows the posterior pelvic muscles to stretch open the posterior urethral wall causing urine loss, "stress urinary incontinence." Such forcible opening out of the urethra exponentially reduces the urethral resistance to flow inversely by the fourth power of the radius (i.e., 16 times). For example, if the radius doubles in size, the bladder pressure required for urine to flow out decreases by a factor of 16, from say, 160 to 10 cm H 2 O. A midurethral sling reinforces PUL to prevent the urethra opening out, thereby restoring both the distal urethral and bladder neck closure mechanisms., (© 2022 Wiley Periodicals LLC.)

Objective Our primary goal is to investigate the effects of non-Newtonian blood properties on wall shear stress in microvessels. The secondary goal is to derive a correction factor for the Poiseuille-law-based indirect measurements of wall shear stress. Methods The flow is assumed to exhibit two distinct, immiscible and homogeneous fluid layers: an inner region densely packed with RBCs, and an outer cell-free layer whose thickness depends on discharge hematocrit. The cell-free layer is assumed to be Newtonian, while rheology of the RBC-rich core is modeled using the Quemada constitutive law. Results Our model provides a realistic description of experimentally observed blood velocity profiles, tube hematocrit, core hematocrit, and apparent viscosity over a wide range of vessel radii and discharge hematocrits. Conclusions Our analysis reveals the importance of incorporating this complex blood rheology into estimates of WSS in microvessels. The latter is accomplished by specifying a correction factor, which accounts for the deviation of blood flow from the Poiseuille law. [ABSTRACT FROM AUTHOR]

Nanoporous alumina membranes were silanized with aminopropylsilane and iminodiacetic acid (IDA) groups were generated in situ by reaction with iodoacetate. The membranes were mounted in standard filter holders, connected to a HPLC system and saturated with selected metal ions. Cu(II) allowed the capture of chicken muscle lactate dehydrogenase with such stability, repeatability and reproducibility that Michaelis-Menten kinetics could be studied. The IDA surface was stable for months and could be depleted and regenerated with metal ions multiple times without appreciable loss of capacity. The binding of lactate dehydrogenase influenced the backpressure to the extent that could be expected for a monolayer according to Poiseuilles law. [ABSTRACT FROM AUTHOR]

The critical micelle concentration (CMC) can be obtained by measuring the distinct physical properties of surfactant molecules in the monomeric and micellar states. In this study, two linear increments of relative viscosity with distinct slopes were obtained when increasing surfactant concentrations from dilute solution to above the CMC, which was then determined by the intersection of the two linear extrapolations. Using a capillary electrophoresis (CE) instrument and Poiseuille's law, the viscosities of surfactants at a series of concentrations covering the monomeric and micellar regions could be obtained by measuring the hydrodynamic flow rates of the corresponding surfactant solutions. We applied this method to determine the CMC values of various types of surfactants including anionic, cationic, zwitterionic, and nonionic surfactants. The resulting CMC values were all in good agreement with those reported in literature. Using this method, the multiple-stage micellization process of a short-chain surfactant was revealed. We have also demonstrated that the CE-based viscometer was applicable to the study of CMC variation caused by organic or electrolyte additives. [ABSTRACT FROM AUTHOR]

Fractures and pores are major flow channels of fluid in low permeability and unconventional reservoirs. So, it is very important to accurately predict multiphase flow in fractures and porous media. In this paper, the empirical, semi-empirical, and theoretical relative permeability models in fractures and porous media are investigated. Among these models, four models have been usually suggested to represent two-phase flow behavior: X-model, Corey or Brooks-Corey model, viscous-coupling model and Chima's model. However, these models have not considered some factors that affect relative permeability significantly. For example, X-model doesn't reflect nonlinear characteristic, Corey or Brooks-Corey model neglects gas-liquid interaction, and viscous-coupling model and Chima's model don't consider irreducible phase. According to Chima's method, when the surface geometry of fracture is assumed to be two ideal parallel planes and that of fracture or pore is assumed to be a pipe, new analytical relative permeability models of fractures and porous media considering irreducible water have been proposed respectively, based on cubic law for flow in rectangular fractures, Poiseuille law for flow in pores; and the momentum balance and Newton's law of viscosity both in fractures and pores. Furthermore, we also improved these relative permeability models by considering the influence of tortuosity based on Brooks-Corey model. The results show that the relative permeability models are nonlinear functions of mobile water, viscosity, irreducible water and the fracture or pore-size distribution index. The gas and water relative permeabilities are different in fractures and pores, and the gas phase relative permeability is more sensitive to the surface geometry of flow channels. And compared with model of fractures, the gas phase relative permeability deviates by more than 50% while the water phase relative permeability deviates by less than 20% in pores. What's more, the deviation will become smaller with the increase of irreducible water saturation. The proposed model with irreducible water saturation of fractures is validated with experimental data from literature and good agreements between experimental data and those evaluated by the proposed model. And the model of porous media is validated by Brooks-Corey model and there is consistency in the forecasting result of two models when there is no irreducible water. The relative permeability models proposed in this work will be useful to professionals involved in modeling well performance, and gas production forecasting in low permeability and unconventional reservoirs. [ABSTRACT FROM AUTHOR]

Abstract: Unlike micropores where water moves upward or downward based on hydraulic gradient, in macropores, water flows predominantly downward due to the gravity. Therefore, models based on capillary flow are not capable of simulating macropore flow. There are attempts to model the macropore flow using two domains, one for capillary flow and another one for macropores. These models use Richard’s equation for capillary flow and Poiseuille’s law for macropores in which the macropore is approximated to be cylindrical or planar. This study quantifies the magnitudes of the errors induced by this assumption. Influence of macropore shapes and tortuosity was quantified by using a 3D Lattice Boltzmann model, which is capable of simulating fluid flow in micropores as well as macropores of cracked clays. Artificial macropores of constant sectional area and volume, but different shapes were generated in 3D and the influence of macropore shapes, shape related parameters, and tortuosity were systematically investigated. Macropore flow rate decreases with different shapes compared to cylindrical macropores and increase in aspect ratio of sectional shape leads to decrease in macropore flow rate. The maximum effect of bends/turnings along the tortuous macropore was about 25% on overall decrease of flow rate due to tortuosity. However, more detailed study is required on the influence of bends on macropore flow rate. The macropore flow rate reduces by about 70% for tortuosity of 1.41. A prediction equation is verified to predict the flow rate of different shapes and tortuous macropores based on straight cylindrical macropore using aspect ratio and tortuosity factor. [Copyright &y& Elsevier]

SUMMARY A two-scales numerical analysis is set up in order to upscale the permeability of fractured materials such as concrete. To that aim, we couple finite element (FE) kinematics enhancements (strong discontinuities) representing fine scale cracks to the fine scale permeability tensor. The latter may be split into two parts: the first one is isotropic and corresponds to flows within the porosity of the material; the second one, based upon a set of cracks with different orientations and openings, is anisotropic. For the latter, each crack is a path for mass flow according to the Poiseuille law considering two infinite planes. We show how the upscaling procedure leads both to the definition of macroscopic permeability tensors as well as the flow rate evaluation for components of concrete structures. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Viscous laminar fluid flow in a pipe is described by the well known Hagen-Poiseuille relation. According to this relation, the velocity of the fluid is directly proportional to the pressure difference between the ends of the pipe and the square of the radius of the pipe and inversely proportional to its length. But as this length becomes vanishingly small, this relation predicts that the velocity of the flow approaches infinity, which obviously is unphysical. The origin of this paradox is discussed, and an extension of the Hagen-Poiseuille relation is presented that is valid for all values of the length of the pipe. [ABSTRACT FROM AUTHOR]