Reflux Phenomenon Research Articles

Effects of Intrarenal Reflux on Renal Growth in Children With Grades III-V Primary Vesicoureteral Reflux.

The phenomenon of intrarenal reflux (IRR) has been considered a crucial link between vesicoureteral reflux (VUR) and segmental scarring. We conducted a study on renal length in 104 children diagnosed with Grades III-V VUR, with or without IRR, using contrast-enhanced voiding urosonography (ceVUS). The patients were divided into two treatment groups: the conservative antibiotic prophylaxis (CAP) group and the operation group, which were further categorized into two subgroups: the IRR group and the non-IRR group. Our findings revealed an incidence rate of 35.96% (41/114) for IRR occurrence, with 43.42% (33/76) occurring in upper renal segments, 32.89% (25/76) in lower segments, and 23.68% (18/76) in middle segments. In the CAP group where the effects of IRR persisted, the renal growth observed was as follows: IRR group-0.19 ± 0.13 cm; non-IRR group-0.39 ± 0.23 cm; contralateral negative group-0.66 ± 0.35 cm; control group-0.46 ± 0 .25 cm respectively (P < .05). In the operation group, where the effects of IRR were eliminated, the renal growth for the IRR group, non-IRR group, contralateral negative group, and control group was 0.46 ± 0.22 cm, 0.54 ± 0.31 cm, 0.67 ± 0 .42 cm, and 0.36 ± 0.17 cm respectively (P < .005). In conclusion, the presence of IRR can impact renal growth in children diagnosed with Grades III-V primary VUR. Following surgical intervention, the IRR kidney does not exhibit catch-up growth; however, it demonstrates parallel growth alongside the unaffected kidney. Conversely, the non-IRR kidney experiences catch-up growth. Therefore, for children presenting with Grades III-V primary VUR combined with IRR, a more aggressive treatment approach such as surgery is recommended.

PIV investigation of stalled flow field near the blade rim region of mixed-flow pump under different tip clearances

In order to further explore the physical mechanism of rotating stall induced by different rim leakage flow intensification, the velocity distribution of the stall flow field of the mixed flow pump under different rim clearance scales was obtained by Particle Image Velocimetry technology. By comparing the flow structure under different shooting sections, different phases and different working conditions, the influence of rim clearance scale on the flow field near the wall of the mixed flow pump was revealed. The results show that under the design flow conditions, there is an obvious reflux phenomenon near the hub of the guide vane inlet of the mixed flow pump under the four kinds of rim clearance, but the intensity is weak, and it does not affect the main flow field in the impeller channel. With the increase of rim clearance scale, the leakage flow intensity also increases, and the main flow area affected by the TLV structure also increases. In the deep stall condition, the reflux vortex at the inlet of the guide vane of the mixed flow pump still exists at each clearance, but the unsteady flow structure begins to appear inside, especially the large secondary vortex structure formed at the guide vane inlet, which seriously blocks the main flow. With the increase of the rim clearance, the flow field at the inlet of the guide vane is also obviously affected, and the secondary vortex core gradually moves towards the end wall area, resulting in an increase in the blocked area in the flow field. At the same time, the unsteady flow intensity of the flow field shows a nonlinear increasing trend. The unsteady strength of flow field increases rapidly with small gap impellers, while the unsteady strength changes slowly with large gap impellers. This study provides a reference for optimizing the rim clearance of mixed-flow pump and improving the efficiency of mixed-flow pump.

A clinical case: gastric cancer after gastric bypass

Introduction: Gastric cancer is one of the most common oncological diseases in the world, occupying the 5th place of morbidity and the 3rd place in the structure of mortality from oncological diseases. For a long time, issues affecting the risk of developing cancer after bariatric surgery remain relevant. Our observation is devoted to the diagnosis and treatment of a patient with gastric cancer after gastric bypass. Description of the clinical case: A 62‑year‑old patient was operated on 13. 07. 2016 – laparoscopic Roux gastric bypass for morbid obesity, 11. 09. 2019 – laparoscopic installation of the Cardioplant plate on a small stomach due to recurrent weight gain. Since 2020 the patient had the phenomena of anastomositis, dysphagia and gastroesophageal reflux. Courses of conservative therapy, sessions of balloon dilation of gastroenteroanastomosis and anastomosis resection failed to show a significant effect. The patient underwent comprehensive examinations at each treatment, including abdominal MSCT, cancer markers and studies of biopsy material of the gastric mucosa and gastroenteroanastomosis. As a result of histological studies, no signs of cancer were found. After applying to the Avicenna Medical Center in 2022 a molecular genetic analysis was carried out, in which the mRNA panel most corresponded to a malignant neoplasm. 20. 12. 2022 extirpation of the stomach stump with resection of the esophagus was performed. The cancer diagnosis was confirmed by histological and immunohistochemical studies: low‑grade adenocarcinoma of the stomach with a cricoid component with germination into the esophagus and small intestine, with spread beyond the muscle layer. Conclusion: This clinical case highlights the complexity of oncological verification in patients after bariatric surgery. Prolonged dysphagia, anastomositis and recurrent GERD in such patients determine the need for a more detailed examination, including the latest achievements of molecular genetic analysis.

Characteristic study of valveless pump with dual outlet composite drainage structures

Abstract Valveless pumps are gaining importance in various fields. However, the reflux phenomenon can reduce pump performance and limit its application. This article proposes a dual outlet composite drainage structure valve-less piezoelectric pump with multiple semicircular arc structures within the flow channel to address this issue. The operating methods are explained, and the pump output flow rate formulation has been derived. The ANSYS CFX was used to simulate flow conditions in various directions. A prototype pump was then produced and tested using 3D printing technology. The results show that the flow rate gets a maximum state of 189.6 mL/min under a voltage of 200 V and a frequency of 50 Hz.

Thermal-flow characteristics analysis of a novel resilient capacity ceramic insulated winding dry type transformer

With the increasing demand for the resilient capacity of transformers in high-proportion renewable energy grids, the overload capacity of transformers and the thermal conductivity of winding insulation materials have been put forward as important requirements. In response to these requirements, a novel ceramic high temperature tolerance insulation winding is proposed in this paper and is applied in a ceramic insulated winding transformer. A combination of simulation and experimentation is used to analyze the thermal-flow characteristics of this transformer. The temperature and flow field distribution characteristics of transformers with both winding insulation methods (ceramic and Nomex paper) are compared. The internal mechanism of reflux near the iron core and high voltage winding under forced air cooling is clarified. A superior outside cooling condition is obtained. A prototype ceramic insulated winding transformer is developed and tested to verify the accuracy of the simulation model. The results show that the hotspot temperature of the ceramic insulated winding transformer under natural cooling is 10.7% lower than that of the Nomex paper insulated winding transformer. With forced air cooling of 2, 3, 4, 5, and 6 m/s applied at the bottom, the hotspot temperature of the ceramic insulated winding transformer is 11.4%, 10.5%, 9.7%, 14.0%, and 17.8% lower than that of the Nomex paper insulation winding transformer, respectively. Under forced air cooling, a reflux phenomenon is observed in both transformers in the vicinity of the iron core and high voltage winding due to the formation of adverse pressure gradient region and wall viscous force blocking. The strength of the reflux is affected by the magnitude of the forced air cooling flow velocity and the construction of the transformer. The optimal range of the external cooling flow velocity for the ceramic insulated winding transformer is 3–4 m/s. The errors between the simulated temperature and the measured temperature at the nine monitoring points of the prototype are all less than 5%, which verifies the effectiveness of the simulation model. The experimental and theoretical basis for the design and application of resilient capacity dry type transformers is provided by this research.

Numerical Simulation and Environmental Impact Assessment of VOCs Diffusion Based on Multi-Emission Sources in the Natural Gas Purification Plant

The rising number of natural gas purification plants has raised concerns about safety and environmental issues related to VOC (Volatile Organic Compounds) leakage. Therefore, it is crucial to conduct in-depth research on oil vapor emission patterns in these plants. Taking a typical natural gas purification plant as an example, a 1:1 scale model was established. Using methanol as the simulated medium, a study was conducted to investigate the impact of multiple leaks on the dispersion process of VOCs at the plant, combining field sampling with numerical simulation. The results indicate that wind speed influences the concentration of oil vapor, particularly on the leeward side, where vortex and reflux phenomena occur. The area of high concentration of oil vapor at v = 4 m·s−1 is eight times that at v = 8 m·s−1. Gravity and eddy currents contribute to the accumulation of oil vapor, especially closer to the central area of the plant where surrounding buildings obstruct dispersion. Smaller distances between leakage sources result in higher concentrations of oil vapor in the central region, leading to a larger affected area in the event of an accident. The study holds significant practical significance for the research, prevention, and management of leakage and dispersion incidents.

Analyzing Single Peristaltic Wave Behavior in Ureter with Variable Diameters: A Ureterdynamic Study

Ureters are muscular tubes that transport urine from the kidney to the bladder. The peristalsis wave is responsible for carrying urine to the bladder. With the regular appearance of peristalsis, areas with anatomic narrowing junctions are crucial for ureteral diseases. A three-dimensional flow analysis is performed for different time steps to understand the effect of the urine bolus formation and the reflux phenomenon on variable diameter ureters. For the constant and variable diameter ureter, the pressure is obtained behind and in front of the propagating bolus respectively. The peristalsis wave creates the high-velocity of a jet in the neck region of the ureter. The contraction produces the trapping of the bolus leading to adverse flow in the contraction region. By virtue tapering, the high-pressure gradient builds up, leading to high wall shear in the ureter. The main goal is to determine the pressure, velocity, gradient pressure, and shear force on the ureter wall during peristaltic motion. These parameters are very important for clinicians to understand its effect in the unobstructed variable diameter ureter. This article may help to build a medical device for engineers. The physical significance of this information lies in its profound insights into the biomechanics and functionality of the ureters, which are essential components of the human urinary system.

Three-dimensional CFD simulation of geyser boiling in high-temperature sodium heat pipe

A deep understanding of the characteristics and mechanism of geyser boiling and capillary pumping is necessary to optimize a high-temperature sodium heat pipe. In this work, the Volume of Fluid (VOF) two-phase model and the capillary force model in the mesh wick were used to model the complex phase change and fluid flow in the heat pipe. Computational Fluid Dynamics (CFD) simulations successfully predicted the process of bubble nucleation, growth, aggregation, and detachment from the wall in the liquid pool of the evaporation section of the heat pipe in horizontal and tilted states, as well as the reflux phenomenon of capillary suction within the wick. The accuracy and stability of the capillary force model within the wick were verified. In addition, the causes of geyser boiling in heat pipes were analyzed by extracting the oscillation distribution of heat pipe wall temperature. The results show that adding the capillary force model within the wick structure can reasonably simulate the liquid backflow phenomenon at the condensation; Under the horizontal and inclined operating conditions of the heat pipe, the phenomenon of local dry-out will occur, resulting in a sharp increase in local temperature. The speed of bubble detachment and the timely reflux of liquid sodium (condensate) replenishment in the wick play a vital role in the geyser temperature oscillation of the tube wall. The numerical simulation method and the results of this study are anticipated to provide a good reference for the investigation of geyser boiling in high-temperature heat pipes.

Numerical investigation of flow and heat transfer behavior on vortex cooling with an optimal convergent coolant chamber for different nozzle aspect ratio arrangement mode

A computational model including convergent coolant chamber, nozzles and vortex chamber is established. The vortex cooling flow and thermal exchange features are investigated under different nozzle aspect ratio arrangement mode based on an optimal convergent coolant chamber. The nozzle aspect ratio arrangement mode consists of two parts, namely eight nozzle aspect ratio sizes and three kinds of nozzle aspect ratio axial variations. Results indicate that the erosion velocity increases due to the smaller windward area with the increasing nozzle size. The convergent coolant chamber makes the mass flow and pressure increases, the reflux phenomenon appears. And the increasing nozzle size leads to the first increase and then decrease with high pressure and Nusselt number area. For the nozzle aspect ratio arranged from high to low, the airflow stiffness and turbulent kinetic energy at the sixth nozzle are the largest, the thermal transfer feature enhances. For the nozzle aspect ratio arranged from low to high, the airflow impact strength and heat exchange characteristic decreases. But the drag coefficient is minimal that has a positive effect on flow features. The thermal exchange capacity is the highest with the nozzle aspect ratio 2.0. Consequently, this study can provide reference for gas turbine design.

Influence of diffuser structure on draining and dry process of Tokamak cooling water system

The diffuser used at the pipe size changing is a common part in the Tokamak cooling water system. It is one of the factors affecting the cooling water retention in the drainage and drying process, which will reduce the dryness of the drying system. This paper focuses on the effect of diffuser structure on gas-liquid flow characteristics in drainage drying process. Further, a numerical simulation model is established to analyze the pressure field, velocity field and phase distribution in the diffuser with different expansive angle in detail. According to the research results, the reflux phenomenon in the diffuser increases with the increase of the angle of the diffuser. This work provides a reference for the design and analysis of drying system of fusion reactor in the future.

Design and analysis of Double-cavity micropump of flexible valve

Piezoelectric micropump and surface tension micropump are generally favored in industrial applications, but these two micropumps have obvious defects through industrial practice. Due to the presence of a piezoelectric oscillator, it is difficult to reduce the volume by optimization further, and the oscillator will be damaged to a certain extent after use for a long time. Based on electric wetting on dielectric (EWOD), a new, efficient EWOD-driven flexible valve micropump is designed using EWOD and flexible valves to replace the conical tube, and a dual microchannel structure is proposed to reduce flow fluctuations at the outlet. The working principle of the EWOD flexible valve micro-pump is deeply discussed. The micropump design is optimized by the finite element method, and its performance is analyzed. The numerical analysis results show that: (1) When the flexible valve structure is adopted, the micropump outlet flow increases significantly. (2) When using the double microchannel, the outlet flow fluctuation of the micropump is significantly reduced. (3) Using the structure of the double microchannel, the micropump has two internal rings, and the direction of the inner ring is related to the direction of the vibration droplet. The EWOD micropump structure is designed to solve the reflux phenomenon in the current micropump pumping process

Investigation of the hydrodynamic characteristics of an axial flow pump system under special utilization conditions

In actual operation, axial flow pump stations are often used for various special purposes to meet changing needs. However, because the hydrodynamic characteristics of axial flow pump systems are still unclear when used for special purposes, there are many risks when pump systems are used for special purposes. To explore the hydrodynamic characteristics of an axial flow pump system under special utilization conditions, a high-precision full-feature test bench for an axial flow pump system is established in this paper. For the first time, an energy characteristics experiment and a pressure fluctuation measurement for a pump are carried out for a large axial flow pump system model under zero head, reverse pump and reverse power generation conditions. Then, ANSYS CFX software is used to solve the continuous equation and Reynolds average Navier–Stokes equation, combined with the SST k–ω turbulence model, and the characteristic curve and internal flow field of the pump system under special conditions are obtained. Finally, the numerical simulation results are compared with the experimental results. The results show that the velocity gradient distribution in the pump is uniform under the near zero head condition (NZHC), and there is no obvious flow collision and reflux phenomenon in the pump. Compared with the designed condition (DC), the peak-to-peak value (PPV) of pressure pulsation at the inlet of the impeller decreased by 67.16%, and the PPV at the outlet of the impeller decreased by 8.14% at H = 0 m. The maximum value of the main frequency amplitude (MFA) in the impeller area appears at the impeller inlet. Under reverse pump conditions (RPC), the phenomenon of unstable flow in the pump system is obvious, and a large range of recirculation zones appears in the nonworking face of the blade. Compared with the DC, the PPV of the impeller inlet at the optimal point of RPC increased by 122.61%, and the impeller outlet PPV increased by 11.37%. The maximum value of MFA in the impeller area appears at the impeller inlet. Under the reverse power generation condition (RPGC), no obvious flow separation was found in the nonworking face of the impeller. Compared to the DC, the PPV of the impeller inlet at the optimal point of the RPGC increased by 65.34%, and the PPV of the impeller outlet increased by 206.40%.

A fully resolved multiphysics model of gastric peristalsis and bolus emptying in the upper gastrointestinal tract

Over the past few decades, in silico modeling of organ systems has significantly furthered our understanding of their physiology and biomechanical function. In spite of the relative importance of the digestive system in normal functioning of the human body, there is a scarcity of high-fidelity models for the upper gastrointestinal tract including the esophagus and the stomach. In this work, we present a detailed numerical model of the upper gastrointestinal tract that not only accounts for the fiber architecture of the muscle walls, but also the multiphasic components they help transport during normal digestive function. Construction details for 3D models of representative stomach geometry are presented along with a simple strategy for assigning circular and longitudinal muscle fiber orientations for each layer. We developed a fully resolved model of the stomach to simulate gastric peristalsis by systematically activating muscle fibers embedded in the stomach. Following this, for the first time, we simulate gravity-driven bolus emptying into the stomach due to density differences between ingested contents and fluid contents of the stomach. Finally, we present a case of retrograde flow of fluid from the stomach into the esophagus, resembling the phenomenon of acid reflux. This detailed computational model of the upper gastrointestinal tract provides a foundation for future models to investigate the biomechanics of acid reflux and probe various strategies for gastric bypass surgeries to address the growing problem of obesity.

The variation of environmental parameters after gas explosion in semi-closed pipeline

ABSTRACT The understanding of the laws of environmental parameters in the later stage of gas explosion in coal mine roadways is of great significance for the prevention and control of derivative disasters and post-disaster rescue. To further comprehend this, the article performed explosion experiments under different gas concentrations in a semi-closed pipeline, focusing on the continuously varied rules of environmental parameters (pressure, temperature, humidity) after a gas explosion. The results showed that the pressure at the open end of the pipeline exhibited a relatively remarkable upward tendency when it arrived in the valley. By comparing with the pressure monitored in the middle of the pipeline, it was concluded that there was a more apparent air reflux phenomenon at the open end. The changes in temperature and humidity were roughly similar, both had a relatively distinct increase after an explosion, with the temperature rising by 7.2% on average and the humidity increasing by 2.7% on average. When the methane concentration was 9.5%, its pressure peaks, temperature peak, and humidity peak were all the maximum. Moreover, the phenomenon of air reflux was also the earliest, with 3.1 seconds, which demonstrated that the closer to the gas equivalent concentration, the more sufficient and violent the explosion reaction, the greater the possibility of secondary accidents. The research can provide a theoretical basis for preventing derived hazards (coal dust explosions, secondary explosions) and reducing the effect of derived hazards.

Immobilized thrombin on X-ray radiopaque polyvinyl alcohol/chitosan embolic microspheres for precise localization and topical blood coagulation

Trans-catheter arterial embolization (TAE) plays an important role in treating various diseases. The available embolic agents lack X-ray visibility and do not prevent the reflux phenomenon, thus hindering their application for TAE therapy. Herein, we aim to develop a multifunctional embolic agent that combines the X-ray radiopacity with local procoagulant activity. The barium sulfate nanoparticles (BaSO4 NPs) were synthesized and loaded into the polyvinyl alcohol/chitosan (PVA/CS) to prepare the radiopaque BaSO4/PVA/CS microspheres (MS). Thereafter, thrombin was immobilized onto the BaSO4/PVA/CS MS to obtain the thrombin@BaSO4/PVA/CS MS. The prepared BaSO4/PVA/CS MS were highly spherical with diameters ranging from 100 to 300 μm. In vitro CT imaging showed increased X-ray visibility of BaSO4/PVA/CS MS with the increased content of BaSO4 NPs in the PVA/CS MS. The biocompatibility assessments demonstrated that the MS were non-cytotoxic and possessed permissible hemolysis rate. The biofunctionalized thrombin@BaSO4/PVA/CS MS showed improved hemostatic capacity and facilitated hemostasis in vitro. Additionally, in vivo study performed on a rabbit ear embolization model confirmed the excellent X-ray radiopaque stability of the BaSO4/PVA/CS MS. Moreover, both the BaSO4/PVA/CS and thrombin@BaSO4/PVA/CS MS achieved superior embolization effects with progressive ischemic necrosis on the ear tissue and induced prominent ultrastructural changes in the endothelial cells. The findings of this study suggest that the developed MS could act as a radiopaque and hemostatic embolic agent to improve the embolization efficiency.

Features of interaction of factors of social and communication activity

The purpose of the study is to determine the features of the interaction of factors of social and communication activities in the context of modern media. It is noted that the audience does not trust the propaganda, but trusts the media, which are carriers of particular propaganda. The content information of the media is analyzed through the prism of the phenomenon of communication reflux. It is noted that communication in its real functional capacity, pursuing the interests of the future, is reduced for the present, for the current needs of the audience. The audience does not have the opportunity to react to the effects, to structural manipulation, to the processes that may lead to the cessation of the supply of mass media distorted reality that is spreading in society.

Temperature logging guidelines and factors that affect measurement accuracy in steamfloods

A robust reservoir surveillance program is key to successful management of a steamflood operation and accurate measurement and proper interpretation of temperature surveys is essential for such a surveillance program. The objective of this study was to look at factors that can impact a temperature log by performing an extensive analysis of field data, primarily gathered from a single company's steamflood operations in California, from over 1000 temperature observation wells. Additionally, a simple analytical assessment was performed to understand the role of key dominating mechanisms and to gain directional insight. Field data and analytical assessment suggest that higher logging speeds introduce greater error in measured temperature data and these errors are greater at elevated steamchest temperatures. Temperature tools with longer sensor response times need to be run at lower logging speeds to get accurate measurements. Ensuring an adequate level of thermally equilibrated liquid (typically water) in the observation well is essential both, for gathering accurate data and to mitigate possible safety concerns for the logging operator. Several field examples are presented to illustrate the effects of logging speed, steamchest temperature, sensor type, and wellbore fluid on recorded temperature data. Guidance on evaluating and interpreting different temperature signatures such as interpretation of liquid level in an observation well, understanding temperature signatures in air, wellbore reflux phenomenon, and examples of logs from malfunctioning logging tools, are also provided. The main purpose of this work is to aid both the operators and the service companies to gather accurate temperature data for improved steamflood management and for all investigators using thermal operation temperature data to understand how and where that data might be compromised.

Transient flow analysis for multi-state automotive scroll compressors

Due to the merit of high efficiency, low noise and vibration, scroll compressor has been rapidly developed in recent years. The working process of a scroll compressor is a three-dimensional non-constant compressible viscous flow process. In order to optimize the compressor design for better performance, it is necessary to understand and reveal the detailed mechanism of the unsteady flow inside a scroll compressor. In this paper, a three-dimensional flow-field model of scroll compressor is established. Non-stationary transient simulation of the flow field is carried out by using a combination of dynamic grid and User-Defined-Files. The distribution of temperature, pressure and velocity within the flow field of the work gas under different operating conditions were obtained. In this paper, the flow phenomenon of gas reflux at the suction and discharge ports and its effect on the performance of the scroll compressor was analysed.

Research on reflux phenomenon of liquid film on the wall of corrugated plate dryer

The corrugated plate is a vital steam-water separation device in nuclear power plants. Research on steam-water separation mechanism and separation efficiency of corrugated plates has been a hot research direction. In this paper, the film lateral movement distance of the film reflux on the corrugated plate wall is measured by PLIF method. Based on experimental results, calculation equation of film lateral movement distance when the film reflux with good applicability is fitted. The degree of liquid film reflux is characterized by the lateral distance between the apex of the liquid film reflux profile and film mainstream. This parameter is defined as distance of liquid film reflux. Based on the law of conservation of mass, theoretical equation of distance of liquid film reflux is derived. Results show that theoretical results of distance of liquid film reflux agree well with experimental results in small and medium Reynolds number regions (Re < 2625).

The value of DMSA scintigraphy in the diagnostic evaluation of vesicoureteric reflux

In terms of treatment planning, the radiologic phenomenon of vesicoureteric reflux has become less important than its inherent risk of further urinary tract infections and loss of renal function. Whilst radiologic and sonographic voiding cystourethrography continues to be the gold standard in the mere detection of vesicoureteric reflux, dimercaptosuccinic acid scanning is important for risk stratification. Also it serves to confirm renal involvement in uncertain situations with urinary tract infection and fever. In older children, it is the standard in primary diagnostics. Furthermore, it enables the diagnosis of occult reflux in many cases. Therefore, dimercaptosuccinic acid scanning is an indispensable tool in the diagnostic evaluation of vesicoureteric reflux.