Fluid Flow Rate Research Articles

One-step flow synthesis of size-controlled polymer nanogels in a fluorocarbon microfluidic chip.

Synthetic polymer nanoparticles (NPs) with biomimetic properties are ideally suited for different biomedical applications such as drug delivery and direct therapy. However, bulk synthetic approaches can suffer from poor reproducibility and scalability when precise size control or multi-step procedures are required. Herein, we report an integrated microfluidic chip for the synthesis of polymer NPs. The chip could sequentially perform homopolymer synthesis and subsequent crosslinking into NPs without intermediate purification. This was made possible by fabrication of the chip with a fluorinated elastomer and incorporation of two microfluidic mixers. The first was a long channel with passive mixing features for the aqueous RAFT synthesis of stimuli-responsive polymers in ambient conditions. The polymers were then directly fed into a hydrodynamic flow focusing (HFF) junction that rapidly mixed them with a crosslinker solution to produce NPs. Compared to microfluidic systems made of PDMS or glass, our chip had better compatibility and facile fabrication. The polymers were synthesized with high monomer conversion and the NP size was found to be influenced by the flow rate ratio between the crosslinker solution and polymer solution. This allowed for the size to be predictably controlled by careful adjustment of the fluid flow rates. The size of the NPs and their stimuli-responses were studied using DLS and SEM imaging. This microfluidic chip design can potentially streamline and provide some automation for the bottom-up synthesis of polymer NPs while offering on-demand size control.

Key Biophysical and Physiological Properties Impacting the Oxygenation Status of Breast Cancers During Thermo-radiotherapy.

Mild hyperthermia at 39-43°C for 30-60 min is applied locoregionally to improve the oxygenation status of recurrent breast cancers, thus enhancing the efficacy of radio-, chemo-, and immunotherapy. In this context, estimated (or even conflicting) data are often used in computational modelling of tumour oxygenation and simulation of O2 transport. In this chapter, we present information that may help to improve adjuvant thermotherapy delivered immediately prior to radiotherapy of recurrent breast cancers. Data are preferentially derived from clinical investigations; in some cases, measurements in experimental breast cancers are included.The biophysical properties presented for healthy, mostly postmenopausal, human breast (composite glandular-adipose-fibrous tissue) measured under normothermic (NT) conditions and in therapeutically heated breast cancers include tissue water content and tissue density. In general, averaged values of parameters reported for NT conditions are higher in breast cancers than in normal breast tissue, i.e., all ratios breast cancer/normal breast are >1. Mean values observed in breast cancers during mild hyperthermia (mHT) are consistently higher than those in NT tumours. Parameters determining convective transports in healthy breast tissue and breast cancer include blood flow rates, blood volume, exchanging water space, arterio-venous shunt flow, interstitial fluid flow rate, interstitial fluid pressure, microvascular permeability, interstitial hydraulic conductivity, and interstitial flow velocity. In general, averaged values of parameters measured under NT conditions are higher in breast cancers than in healthy breast. Except for interstitial fluid pressure, these values increase upon mHT treatment of cancers. Prime factors determining and describing the oxygenation status of the healthy breast, and in NT- versus mHT-treated breast cancers, include: oxygen (O2) delivery rates, O2- extractions, O2- consumption rates, subepidermal microvascular HbO2, tissue oxygen solubility, oxygen diffusion coefficients, mean O2 partial pressures pO2, hypoxic fractions HF<5mmHg, oxygen enhancement ratio, and mitochondrial ROS production. With the exception of the mean pO2, O2 extraction rate and tissue O2 saturation all parameters listed are distinctly higher in breast cancers under NT conditions compared to normal breast. Mild hyperthermia results in therapeutically relevant improvements of the oxygenation status of cancers and enhances mitochondrial ROS production, thus improving radiosensitivity. Note: The oxygenation status of the healthy (postmenopausal) breast is very similar to that of the normal human subcutis.

Knowledge Regarding Intravenous Therapy among Health Workers of a Teaching Hospital Birgunj, Parsa, Nepal

INTRODUCTION: Intravenous fluid is a continuous process of administration of large amount of fluid into the vein by a drip apparatus. The main purpose of intravenous therapy is to supply fluid and electrolyte to prevent or treat fluid and electrolyte imbalance in the body. The intravenous drug injected through vein into the body for quick action. At the time of infusion the nurse check or observe the flow rate of fluid for any adverse affect and also for others complication. Globally more than 330 million people receive invasive procedure of intravenous catheter placement annually. 60% to 90% patients require an intravenous catheter during hospitalization in US and studies said that 35%-50% patient is in fail intravenous catheters in hospitalization and arise complication. The objective of the study was to find out the knowledge regarding intravenous therapy among health workers of Teaching Hospital Birgunj, Parsa. MATERIALS AND METHODS: A descriptive cross sectional study design was adopted for the study. This carried out in national medical college teaching hospital is a tertiary level Hospital, Birgunj, Nepal, with the sample size of 139. The instruments used for the study was a structured knowledge questionnaire was used in the study, after reviewing related literatures, which consists of 28 items and data were collected within 2 weeks. RESULTS: Among 139 health workers, 43.2% had moderate level of knowledge, 33.1% had low level of knowledge and 23.7% had adequate level of knowledge. CONCLUSION: From the study finding it can be concluded that knowledge regarding intravenous therapy among respondents had moderate level of knowledge. Hence, various educational programmes for health workers should be focused on enhancing their knowledge regarding intravenous therapy which enables them to provide quality care for patients.

Determination of regions prone to sand production and the linkage to fluid flow rates by integrating rock strength parameters and microphotographs in the southern onshore basin, India

One of the main challenges for healthy hydrocarbon yields from the production wells is the sand production, and its control assumes significant importance for successful production operations. The prime objective remains to control the sand production without compromising on the fluid flow rates. Sand production is conventionally associated with diverse heterogeneous formations, especially poorly consolidated formations. Scrutinizing fluid flow rates at different orientations of perforations is a valuable analysis in controlling the sand production. This study was conducted to examine the case of sand production in a few development wells from Malleshwaram field of the Krishna Godavari (KG) basin in south India and provide alternatives to arrest this sand production. The influence of oriented perforations on fluid flow rates to minimize sanding tendencies was examined. Sand grain diameter was estimated using the distribution plots of the grain sizes obtained from the photomicrographs, and the average value of the grain size was estimated around 100 μm. The fluid flow model was simulated for actual scenario in the hydrocarbon bearing Nandigama formation using finite element modeling (FEM). Sanding tendencies in these formations were studied at varying depletion rates. Critical draw down pressure (CDDP), which is a function of both critical bottom hole pressure and reservoir pore pressure, for well 1 and well 2 is estimated as 4650 Psi and 3400 Psi, respectively, at 0% depletion. CDDP was used to estimate the onset of sanding, and the flow rate for horizontal perforation was calculated as 0.024548 m3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathrm{m}}^{3}$$\\end{document}/sec. Strength parameters, namely the unconfined compressive strength (UCS) and cohesion, were also investigated in all the wells to decipher the formation strength and a possible linkage to sanding. These results present a completely fresh analysis of the sanding potential and the related parameters responsible for it in these formations. Fluid flow rates for the producing reservoir are studied at different set of oriented and sized perforations. It was observed that a hiked flow rate in horizontal perforations maintains the production in a safe and no-sanding zone. This study provides vital information and a workflow for similar heterogeneous complex formations for designing the well completions, augmenting economic production and reinforcing future reservoir management.

Experimental investigation of heat transfer characteristics in a miniature flat heat pipe with multi-channels

The heat transfer characteristics of a miniatured flat heat pipe (MFHP) with multi-channels, featuring a port diameter of 1.18 mm, is investigated experimentally. Various operating parameters are considered, including the working fluid volume (Vf = 1.5, 2.5, and 3.5 ml), length of the liquid reservoir (Lres = No reservoir, 5, and 10 mm), orientation such as axial face (αa) or lateral side (αl), inclination angles (α = −15 to 90o), and cooling water flow rates (ṁi = 10, 15, and 20 LPH). Based on the experiments, the optimal values for the working fluid volume, reservoir length, and flow rate are determined as Vf = 2.5 ml, Lres = 5 mm, and ṁi = 20 LPH, respectively. Further analysis reveals that, the heat dissipation rate for the axial face is significantly higher than that of the lateral side, with an average percentage increase of 35.4 %. However, the lateral side outperforms the axial face in terms of stabilizing the evaporator wall temperature, reducing fluctuations by an average of 24.5 %. Moreover, the presence of multi-channels allows the MFHP in axial face orientation to dissipate a maximum heat load of 15 W against gravity at an inclination angle of αa = −15o. Finally, the variations in MFHP operation based on the orientation and its underlying physical mechanisms that contribute to enhancing heat transfer are discussed.

Numerical Study and Hydrodynamic Calculation of the Feasibility of Retrofitting Tangentially Fired Boilers into Slag-Tap Boilers

Retrofitting a tangentially fired boiler into a slag-tap boiler offers a solution for fully burning high-alkali coal in power plant boilers. Numerical simulation and hydrodynamic calculation of such a retrofit scheme were performed in this study. The maximum temperature in the furnace after retrofitting is 2306.8 K, surpassing the pre-retrofit temperature of 2095.8 K. The average temperature in the combustion chamber of the slag-tap boiler is 2080.3 K, which ensures that the slag can be discharged in a molten state. When the coal consumption is halved relative to the working condition of the boiler maximum continuous rating (BMCR) in the slag-tap boiler, the maximum temperature in the combustion chamber decreases from 2306.8 to 2220.3 K. However, the temperature distribution remains relatively uniform, ensuring that the slag discharge is not disrupted. In both of the working conditions calculated in this study, the fluid flow rates in the water-cold wall are positively correlated with the wall heat fluxes. The maximum wall temperatures under the two working conditions are 653.9 and 590.6 K, respectively, both of which are well within the safe limits for the wall material. The results illustrate the feasibility of the retrofit scheme.

THE PROBLEM OF PRESERVING THE RESERVOIR PROPERTIES OF PRODUCTIVE HORIZONS – THE CURRENT STATE

The reasons for the deterioration of reservoir properties of productive layers during their opening are considered. Special attention is paid to the study of geological properties of emulsions of the drilling mud filtrate – oil type. Productive deposits on the example of the fields of Southwestern Turkmenistan are characterized by a complex and ambiguous composition of rocks, waters and drilling mud and oil. Each of the components, interacting with the filtrate of the drilling mud, determines the deterioration of reservoir properties and a decrease in the flow rates of hydrocarbon fluids. Oilbased solutions were used to open productive horizons while maintaining natural permeability, as well as for drilling in particularly unstable clay saline deposits. In such solutions, the dispersion medium is represented by diesel fuel, and the dispersed phase is finely ground oxidized bitumen. The results obtained make it possible to clarify the mechanism of reducing the reservoir properties of productive formations due to the penetration of filtrate of drilling fluids, as well as to formulate new requirements for technologies, composition and properties of drilling fluids for opening productive formations.

Thermal Performance Analysis of U-pipe Evacuated Tube Solar Heater System with and without PCM

The study presents a comprehensive thermal performance analysis of a U-pipe Evacuated Tube Solar Collector (U-ETSC) system, integrated with Phase Change Material (PCM), for satisfying water demand in domestic applications. The innovative approach of incorporating PCM aims to enhance the system's efficiency during night or off-sunny hours, addressing a common limitation in solar heater systems. The research primarily focuses on the impact of varying mass flow rates of the heat transfer fluid (HTF) on the thermal dynamics of the system. Experimental results reveal that as the mass flow rates of HTF increase from 0.5 to 1 and then to 1.5 liters per minute, there is a notable change in the phase transition times of the PCM. Specifically, the melting time of the PCM is increased by 13% and 16% for the respective flow rates, suggesting a delayed response in energy absorption. Conversely, the solidification time of the PCM is reduced by 16% and 18% respectively, indicating a faster release of stored thermal energy. This behavior underscores the PCM's significant role in stabilizing the system's thermal output during varying solar intensities. The findings of this study highlight the potential of integrating PCM in U-ETSC systems to achieve a more consistent and reliable supply of hot water for domestic purposes, especially during periods when solar irradiance is low or absent.

Static and dynamic modeling and identification of a magnetic refrigerator

In this paper, an experimental study of a magnetic refrigerator was carried out to identify static and dynamic models, which can be used for proposing and tuning control strategies. For the experimental evaluation, a 40liter thermally insulated compartment was coupled to a magnetic refrigeration system equipped with an active magnetic regenerator. The influence of fluid flow rate, blow fraction, and magnetic cycle frequency on the temperature behavior inside the refrigerated compartment and on the power consumption of the system was evaluated. The results of the characterizations show that it is possible to reach equivalent cabinet temperatures by changing the flow rate of the thermal fluid or the cycle frequency. However, the former has a greater influence on the temperature of the cabinet, and the latter has a greater impact on the energy consumption and is associated with slower transients. Additionally, the temperature of the cabinet at steady state showed a parabolic behavior with respect to the fluid flow rate, demonstrating that there is an optimal flow rate for a given operating condition.

Improving the thermal performance of the heat exchanger through simultaneous utilization of novel magnetic turbulators and helical coil wire turbulators

In this study, the effect of simultaneously using two active and passive methods, namely the magnetic turbulator and the helical coil wire (HCW) turbulator, on the hydrothermal parameters of a double tube heat exchanger is being evaluated for the first time. The results are also being compared with those of a simple heat exchanger, a heat exchanger equipped with a magnetic turbulator, and a heat exchanger with a HCW turbulator insert. Finally, the most optimal option is selected using TEF. Tests have been conducted using different pitch ratios of the HCW turbulator (ranging from 2.5 to 10) and fluid flow rates (ranging from 0.5 to 4 l/min). According to the results, the usage of the HCW turbulator, magnetic turbulator, and the simultaneous use of both turbulators increases heat transfer by 237 %, 262 %, and 491 %, respectively. Additionally, the pressure drop in the presence of these two methods is 3.8 times that of a simple heat exchanger. Furthermore, with the help of TEF, the heat exchanger armed with both turbulators is chosen as the optimal option, achieving a TEF of 3.78.

An embedded microfluidic valve for dynamic control of cellular communication.

The communication between different cell populations is an important aspect of many natural phenomena that can be studied with microfluidics. Using microfluidic valves, these complex interactions can be studied with a higher level of control by placing a valve between physically separated populations. However, most current valve designs do not display the properties necessary for this type of system, such as providing variable flow rate when embedded inside a microfluidic device. While some valves have been shown to have such tunable behavior, they have not been used for dynamic, real-time outputs. We present an electric solenoid valve that can be fabricated completely outside of a cleanroom and placed into any microfluidic device to offer control of dynamic fluid flow rates and profiles. After characterizing the behavior of this valve under controlled test conditions, we developed a regression model to determine the required input electrical signal to provide the solenoid the ability to create a desired flow profile. With this model, we demonstrated that the valve could be controlled to replicate a desired, time-varying pattern for the interface position of a co-laminar fluid stream. Our approach can be performed by other investigators with their microfluidic devices to produce predictable, dynamic fluidic behavior. In addition to modulating fluid flows, this work will be impactful for controlling cellular communication between distinct populations or even chemical reactions occurring in microfluidic channels.

Multi-factor analysis and optimization design of a cascaded packed-bed thermal storage system coupled with adiabatic compressed air energy storage

In an adiabatic compressed air energy storage (A-CAES), one of the key components is the heat storage system, in which the packed bed filled with encapsulated phase-change capsules has been widely investigated because of its excellent thermal performance. In this paper, a packed-bed thermal energy storage model with three layers of phase change materials (PCM) is proposed in the context of an A-CAES. Four factors primarily affecting the thermal performance of the packed bed thermal storage system, namely the mass flow rate of heat transfer fluid (HTF), the inlet temperature of HTF, the cascade situation of PCM, and the arrangement of particle sizes, are critically analyzed by conducing the orthogonal experiments. On this basis, the machine learning method is applied to predict and optimize the thermal performance of the packed bed aiming to find the optimal results. The comparison of results between the optimized and original models expressively shows a reduction of 8.46% in PCM mass, an increase of 92.18%/116.82% in the overall heat storage/release quantity, and an increase of 19.23% in the overall efficiency. This work outlooks a guideline for the potential application of packed bed in A-CAES.

A controlled lumbar puncture procedure improves the safety of lumbar puncture.

In order to improve the safety of lumbar puncture (LP), we designed a new type of LP needle, that is, an integrated and controlled LP needle, which can actively and accurately control the flow rate and retention of cerebrospinal fluid (CSF) during puncture, so as to achieve a controlled LP procedure. To evaluate whether a controlled LP procedure can improve the comfort of LP and reduce the risk of complications associated with LP. Patients requiring LP (n = 63) were pierced with an integrated and controlled LP needle or a conventional LP needle. The differences in vital signs, symptom score, comfort, operation time, CSF loss, CSF pressure fluctuation and back pain before and after puncture were analyzed. An integrated and controlled LP needle (n = 35) significantly improved patients' headache symptoms before and after puncture. In addition, a controlled LP procedure significantly reduced the amount of unnecessary CSF loss (p < 0.001), shortened the time of puncture (p < 0.001), improved patient comfort (p = 0.001) and reduced the incidence of back pain (p < 0.001). For patients with high intracranial pressure (HICP), the fluctuations in pressure of the CSF were also reduced while obtaining similar amounts of CSF (p = 0.009). A controlled LP procedure avoids unnecessary CSF loss, prevents rapid fluctuations in CSF pressure in patients with HICP, and reduces the risks associated with LP.

Cascading latent heat thermal energy storage in parabolic trough solar collector as a promising solution: An experimental investigation

Solar energy system can be considered as a reliable energy source if it connects to a latent heat thermal energy storage (LHTES) system using phase change materials (PCMs). To tackle the low thermal conductivity coefficient of PCMs, the cascaded latent heat storage (CLHS) configuration is a promising solution. This study aims to illustrate the improvement of CLHS setup comparing with non-cascaded arrangement, performing a whole-scale experimental investigation. A compact parabolic trough collector (PTC) unit equipped with a LHTES module is designed and constructed for a residential purpose. Experimental results reveal that the average thermal efficiency of PTC is 73.5 %. Three paraffin waxes with melting ranges of (64–68 ℃), (57–60 ℃) and (46–48 ℃) are injected in three same series of shell-tube heat exchangers. For comparing cascaded and non-cascaded PCM performance, three experimental series, namely (Exp.1, Exp.2 and Exp.3) are performed. The experimental findings show that the deployment of the CLHS configuration improves the latent heat storage of non-CLHS-Exps.1, 2, and 3 by more than 10, 47, and 5 %, respectively. In addition, CLHS system has a potential to increase the exergy storage of non-CLHS setup by up to 27.4 %. Furthermore, impact of increasing heat transfer fluid (HTF) flow rate is examined and it is observed that the melting process is shortened by almost 39 %. Accordingly, increasing flow rate improves energy stored in PCMs1, 2, and 3 by 60 %, 59.62 %, and 72.04 %, respectively. Consequently, the latent thermal exergy storage of the PCM experiences a twofold increase. Conducting an experimental evaluation of thermal performance of the storage module integrated with PTC setup can be valuable, particularly in the realm of residential applications.

Hydrodynamic characteristics of core/shell microdroplets formation: Map of the flow patterns in double-T microchannel

Liquid-liquid–liquid (L/L/L) flows in microchannels involving three-phase interactions are important in various chemical applications that entail liquid–liquid–liquid reactions. This work comprehensively investigates core (silicone oil)/shell (Polycaprolactone) microdroplet formation using a continuous third phase (distilled water) in a double T-junction microchannel with a diameter of 600 µm, employing Volume-of-Fluid (VOF) simulations and high-speed imaging experimental observation. Due to the satisfactory agreement between computational and experimental techniques, the theoretical flow patterns were identified and categorized into three distinct categories at various flow rates of three phases: core/shell dripping, core/shell slug, and core/shell jetting. The shell thickness increases as the ratio of shell to core phase velocity (ushell:ucore) increases. Based on the continuous phase Capillary number (Cac) and core and shell phases Weber number (Wecore,shell), a flow pattern map was generated that segregates the distinct flow patterns into different regions. When the flow of the core and shell phases fails to form a droplet due to the inertia of the continuous phase, a core/shell dripping/slug pattern is observed. The channel walls encompass the droplets that form in the slug pattern (2×10-5≤Cac≤5×10-4, 0<Weshell≤1.5×10-3, and 0<Wecore≤5×10-5) because the continuous phase has less inertia, whereas, in the dripping pattern (5.5×10-5≤Cac≤9×10-4, 7×10-5≤Weshell≤2.5×10-4, and 1×10-5≤Wecore≤7×10-5), the shell phase fluid is enclosed by the continuous phase. The transition from dripping to jetting (Cac≥0.5, 0<Weshell≤0.15, and 1×10-2≤Wecore≤8×10-2) occurs as the flow rate of a continuous fluid or shell fluid increases. A dimensionless correlation for shell thickness estimation with a 12 % tolerance was proposed with a core/shell/continuous phase's physical properties, surface tensions, and microdroplet size, using Buckingham's theory based on 200 CFD simulations. Additionally, the flow rate and viscosity substantially impact the internal fluid velocity and vorticity of core/shell microdroplets, whereas the influence of interfacial tension can be disregarded. This research lays the groundwork for future studies on mass transfer and reaction behaviors in liquid–liquid–liquid three-phase flow in double T-junction microchannels by exploring various hydrodynamic characteristics under different operating conditions for core/shell microdroplet formation.

Morphological evolution and flow conduction characteristics of fracture channels in fractured sandstone under cyclic loading and unloading

In coal mining, rock strata are fractured under cyclic loading and unloading to form fracture channels. Fracture channels are the main flow narrows for gas. Therefore, expounding the flow conductivity of fracture channels in rocks on fluids is significant for gas flow in rock strata. In this regard, graded incremental cyclic loading and unloading experiments were conducted on sandstones with different initial stress levels. Then, the three-dimensional models for fracture channels in sandstones were established. Finally, the fracture channel percentages were used to reflect the flow conductivity of fracture channels. The study revealed how the particle size distribution of fractured sandstone affects the formation and expansion of fracture channels. It was found that a smaller proportion of large blocks and a higher proportion of small blocks after sandstone fails contribute more to the formation of fracture channels. The proportion of fracture channels in fractured rock can indicate the flow conductivity of those channels. When the proportion of fracture channels varies gently, fluids flow evenly through those channels. However, if the proportion of fracture channels varies significantly, it can greatly affect the flow rate of fluids. The research results contribute to revealing the morphological evolution and flow conductivity of fracture channels in sandstone and then provide a theoretical basis for clarifying the gas flow pattern in the rock strata of coal mines.

Effect of Water-Based Nanofluids on the Generation of Entropy in a Shell and Helical Coil Heat Exchanger

A forced convection finding proves that entropy was generated as a result of the heat transfer between the fluids on the coil and the fluids on the shell side. It was found that entropy generation was affected by nanofluid concentration, coil-side fluid flow rate, shell-side fluid temperature, and agitator speed (500 rpm, 1000 rpm, and 1500 rpm) in this paper. The nanoparticle (Al2O3, CuO, and TiO2) weight fractions ranged from 0.3 to 2%. This paper investigates the friction entropy generation rate, the entropy generation ratio, and the thermal entropy generation rate of various nanofluids in laminar and turbulent flow conditions, using existing correlations to guide the investigation. The results revealed that the generation of entropy increased as the Dean number, SS, and fluid temperature on the shell side of the reactor were increased in the laboratory. And, found that the maximum entropy generation rate of Al2O3/water, CuO/water, and TiO2/water nanofluids occurred at 56.4 percent by weight of the nanofluid, 62.1 percent by weight of the nanofluid, and 48.1 percent by weight of the nanofluid.

Independent regulation of Piezo1 activity by principal and intercalated cells of the collecting duct

The renal collecting duct is continuously exposed to a wide spectrum of fluid flow rates and osmotic gradients. Expression of a mechanoactivated Piezo1 channel is the most prominent in the collecting duct. However, the status and regulation of Piezo1 in functionally distinct principal and intercalated cells (PCs and ICs) of the collecting duct remain to be determined. We used pharmacological Piezo1 activation to quantify Piezo1-mediated [Ca2+]i influx and single-channel activity separately in PCs and ICs of freshly isolated collecting ducts with fluorescence imaging and electrophysiological tools. We also employed a variety of systemic treatments to examine their consequences on Piezo1 function in PCs and ICs. Piezo1 selective agonists, Yoda-1 or Jedi-2, induced a significantly greater Ca2+ influx in PCs than in ICs. Using patch clamp analysis, we recorded a Yoda-1-activated nonselective channel with 18.6± 0.7 pS conductance on both apical and basolateral membranes. Piezo1 activity in PCs but not ICs was stimulated by short-term diuresis (injections of furosemide) and reduced by antidiuresis (water restriction for 24 h). However, prolonged stimulation of flow by high K+ diet decreased Yoda-1-dependent Ca2+ influx without changes in Piezo1 levels. Water supplementation with NH4Cl to induce metabolic acidosis stimulated Piezo1 activity in ICs but not in PCs. Overall, our results demonstrate functional Piezo1 expression in collecting duct PCs (more) and ICs (less) on both apical and basolateral sides. We also show that acute changes in fluid flow regulate Piezo1-mediated [Ca2+]i influx in PCs, whereas channel activity in ICs responds to systemic acid-base stimuli.

Mixing phenomena in circular and rectangular cross-sectional T-mixers: Experimental and numerical assessment

In the present work, the mixing performance of square and circular cross-sectional millimetre-sized T-mixers was experimentally and numerically investigated. The pure dilution of non-reacting species (blue and yellow food dyes) and the chemical reaction of two-coloured reactants (i.e., strong acid and strong base with a pH indicator) were captured experimentally by adopting a low-cost colorimetric digital image analysis technique. Turbulence was modelled by k − ε model coupled with the β-PDF approach to account for turbulence-chemistry interactions. The circular cross-sectional T-mixer showed better mixing efficiency than the square one. Moreover, an even larger mixing performances were obtained by setting unbalanced fluid flow rates. To exploit the low computational demanding k − ε model, the Cε2 parameter was tuned, showing good reliability in describing the phenomena in the mixers. Mixing time estimations were based on both time averages and instantaneous quantities, and some possible limits of the approaches commonly adopted in the literature were identified.

Efficiency Improvement of Double Pipe Heat Exchanger by using TiO2/water Nanofluid

Heat exchangers are commonly utilized to transfer heat between two fluids in a number of industries. However, parameters such as fluid flow velocity, temperature difference, and thermal conductivity limit their efficiency. Researchers have investigated the use of nanofluids - fluids containing nanoparticles that boost thermal characteristics - to improve the performance of heat exchangers. The use of nanofluids can improve the efficiency of double-pipe heat exchangers. However, research on the influence of TiO2/water nanofluid on the performance of double-pipe heat exchangers is insufficient. The purpose of this research is to investigate the impact of TiO2/water nanofluid on the efficiency of a double-pipe copper counter-flow heat exchanger. A double-pipe copper counter-flow heat exchanger using cold (room temperature) and hot (70°C) water as working fluids was used in an experimental investigation. They created nanofluids by adding varying concentrations (0.1%, 0.3%, and 0.5%) of TiO2 nanoparticles to water and measuring their heat conductivity and viscosity. They then calculated the overall heat transfer coefficient and efficacy by measuring the input and outlet temperatures as well as the flow rates of both fluids. It was discovered that adding TiO2 nanoparticles to water enhanced its heat conductivity and viscosity substantially. The overall heat transfer coefficient increased up to 0.3% but declined at 0.5% nanoparticle concentration. At a nanoparticle concentration of 0.3%, the maximum effectiveness was attained, with a corresponding increase in efficiency of up to 23%. The scientists found that using TiO2/water nanofluid to improve the efficiency of double-pipe heat exchangers is a viable option.