Fluid Kinetics Research Articles

Evaluation of the Distribution and Elimination of Balanced Isotonic Crystalloid, 5% Hypertonic Saline, and 6% Tetrastarch 130/0.4 Using Volume Kinetic Modeling and Analysis in Healthy Conscious Cats.

This prospective, randomized, blinded, interventional cross-over study investigated the distribution, elimination, plasma volume expansion, half-life, comparative potency, and ideal fluid prescription of three commonly prescribed intravenous (IV) fluids in 10 healthy conscious cats using volume kinetic analysis that is novel to veterinary medicine. Each cat received 20 mL/kg of balanced isotonic crystalloid (PLA), 3.3 mL/kg of 5% hypertonic saline (HS), and 5 mL/kg of 6% tetrastarch 130/0.4 (HES) over 15 min on separate occasions. Hemoglobin concentration, red blood cell count, hematocrit, heart rate, and blood pressure were measured at baseline, 5, 10, 15, 20, 30, 40, 50, 60, and every 15 min until 180 min. Urine output was estimated every 30 min using point-of-care bladder ultrasonography. Plasma dilution derived from serial hemoglobin concentration and red blood cell count served as input variables for group and individual fluid volume kinetic analyses using a non-linear mixed effects model. In general, the distribution of all IV fluids was rapid, while elimination was slow. The half-lives of PLA, HS, and HES were 49, 319, and 104 min, respectively. The prescribed fluid doses for PLA, HS, and HES resulted in similar peak plasma volume expansion of 27–30%. The potency of HS was 6 times higher than PLA and 1.7 times greater than HES, while HES was 3.5 times more potent than PLA. Simulation of ideal fluid prescriptions to achieve and maintain 15 or 30% plasma volume expansion revealed the importance of a substantial reduction in infusion rates following initial IV fluid bolus. In conclusion, volume kinetic analysis is a feasible research tool that can provide data on IV fluid kinetics and body water physiology in cats. The rapid distribution but slow elimination of IV fluids in healthy conscious cats is consistent with anecdotal reports of fluid overload susceptibility in cats and warrants further investigation.

МОДЕЛЮВАННЯ ПРОЦЕСІВ ВОЛОГОПЕРЕНОСУ В БАГАТОШАРОВИХ АПЛІКАЦІЙНИХ МАТЕРІАЛАХ МЕДИЧНОГО ПРИЗНАЧЕННЯ

To carry out modeling of moisture transfer processes in multilayer medical application materials for forecasting of targeted transport of drugs of a certain effective concentration into the lesion center, based on the geometric parameters of the wounds. Using digital image processing techniques in a computer environment have developed methods for designing three-dimensional fluid propagation effects in multilayer medical wound dressings. Modern wound dressings have been found to be multilayer multidimensional compositions with complex fluid kinetics. Additionally, the wounds on the human body itself have a complex space geometric shape. This requires taking into account the volumetric effects when analyzing and forecasting the processes of wetting and fluid flow in such systems. An algorithm for ordering the boundary of a wound by digital photography with the subsequent processing of a wound image in a computer environment is proposed. To evaluate the moisture transport properties for the controlled release of medicinal substances at the desired concentration in different layers of wound dressings, an experiment was made with wetting from two and three sources, followed by three-dimensional modeling. It has been experimentally found that the parameters of the layered distribution of liquid moisture in multilayer dressings vary significantly.. The results of the simulation are suitable for making prompt decisions about the type, the required geometric parameters of medical materials and wound dressings. The proposed method of establishing the real geometry of the wound, together with three-dimensional modeling, allows to predict the exact boundaries of the application of the drug, to calculate its required amount and time of movement to the wound. Using 3D computer graphics of discrete objects, methods have been developed to predict the conditions for the reliable functioning of multilayer dressings. Investigated processes of transport and distribution of liquid moisture can be used in the selection of components of the raw material composition, structure and number of layers of multilayer wound dressings, taking into account the real geometric profile of the wound.

Integrating Microbial Community Assembly and Fluid Kinetics to Decouple Nitrogen Dynamics in an Urban Channel Confluence.

Understanding the characteristics of biogeochemical processes in urban channel confluences is essential for the evaluation and improvement of water environmental capacity. However, influences of biogeochemical processes in confluence were always overlooked or simply parametrized since the transformation processes controlled by microbial community assembly were hard to quantify. To address this knowledge gap, the present study proposed a novel mathematical modeling system, based on microbial community assembly theory and fluid kinetics, to decouple nitrogen dynamics into flow-induced transport and microorganism-induced transformation processes, and quantified their contributions to nitrogen concentrations. Results revealed that variable selection processes (including hydrodynamic conditions) contributed to significant difference in microbial communities among different hydraulic regions. Variation in microbial communities further shifted transformation processes. Rhodobacterales and Sphingomonadales, which were reported to be vital participants in denitrification process, were enriched in flow separation region, and promoted it as a hotspot for nitrogen removal. In the flow separation region, microorganism-induced transformation processes accounted for 56% of total nitrogen removal, which was significantly higher than that in other regions (12% on average; p < 0.01). Results and findings could provide useful information for the improvement of water environmental capacity.

Water content of the endothelial glycocalyx layer estimated by volume kinetic analysis

BackgroundThe water volume of the endothelial glycocalyx layer has been estimated at 0.7 to 1.7 L using tracer methods of unclear value. The present study attempts to measure this fluid volume by analyzing the kinetics of a crystalloid fluid load.MethodsAn intravenous infusion of approximately 1 L of Ringer’s acetate was administered to 35 healthy volunteers, and the central volume of distribution of the water volume was calculated from the urinary excretion and frequent measurements of the fluid-induced hemodilution using mixed-effects modeling software. Comparisons were made with the plasma volume derived from three published anthropometric regression equations based on isotope measurements. In a second analysis, up to 2.5 L of Ringer’s was administered to 60 volunteers selected from a cohort of 160 to have as similar hematocrits as possible to the volunteers whose data were used to create the anthropometric equations.ResultsVolume kinetics showed that the infused crystalloid fluid occupied a larger central fluid space than was estimated with the isotope measurements. The first analysis of the 35 subjects indicated a mean difference of 0.51 L in males and 0.49 L in females. The second, larger analysis showed a mean excess volume of 0.43 L, which was approximately 15% of the circulating plasma volume.ConclusionsA crystalloid fluid load expands a 0.4–0.5 L larger central fluid space than the circulating plasma volume. The excess volume is probably located in the glycocalyx layer.

Kinetics of crystalloid fluid in hyperglycemia; an open-label exploratory clinical trial.

Infusion with 0.9% saline is a mainstay in the treatment of severe hyperglycemia, but the kinetics of the saline volume in this setting has not been studied. An intravenous infusion of 1L of 0.9% saline over 30minutes was given on 31 occasions to 17 patients with hyperglycemia due to poorly controlled diabetes (mean age 51years). A two-volume kinetic model was fitted to serial data on the hemodilution and urinary excretion, using mixed-effects modeling software. Plasma glucose was 36±9mmol/L on arrival to the hospital. The central volume of distribution (the plasma) was only 2.38 L (mean; 95% confidence interval 1.73-3.04) on the day of admission. Uptake into a remote compartment, believed to be the cells, amounted to 300mL of the first liter of saline, although only small amounts of insulin were given. Plasma glucose, plasma bicarbonate, urine glucose, and plasma creatinine served as covariates in the kinetic model and mathematically affected the urinary excretion. For example, elimination of the infused fluid tripled from an increase in plasma glucose from 5 to 35mmol/L and doubled from a reduction in plasma bicarbonate from 24 to 5mmol/L. The excretion of 0.9% saline was increased depending on the degree of hyperglycemia. The kinetics was characterized by glucose-accelerated diuresis, and an intracellular uptake that occurred at two thirds the urine flow rate. These data could help to determine appropriate volumes and rates of infusion of crystalloids in hyperglycemia.

Urea Injection and Uniformity of Ammonia Distribution in SCR System of Diesel Engine

Abstract The kinetic mechanism of chemical reaction was used to calculate the coupling of the fluid kinetics with the urea decomposition reaction and the SCR reaction kinetics. Combined with the engine test and simulation, the distribution uniformity of the urea injection and ammonia gas was studied. Through numerical simulation on urea spray and exhaust flow in Urea-SCR system, the flow field characteristics in whole after-treatment system are gotten. By using numerical calculation in different urea injection angle and orifice sizes, the urea-crystallization and ammonia distribution have been studied and the optimal urea spray angle and nozzle size are given.

Volume kinetic analysis of fluid retention after induction of general anesthesia

BackgroundInduction of general anesthesia increases the hemodilution resulting from infusion of crystalloid fluid, which is believed to be due to slower distribution caused by arterial hypotension. When normal distribution returns is not known.MethodsAn intravenous infusion of 25 mL kg− 1 of Ringer’s lactate was infused over 30 min to 25 volunteers just after induction of general anesthesia for open abdominal hysterectomy. A two-volume model was fitted to the repeated measurements of the blood hemoglobin concentration and the urinary excretion using mixed-effects modelling software. Individual-specific covariates were added in sequence.ResultsDistribution of infused fluid was interrupted during the first 20 min of the infusions. During this time 16.6 mL kg− 1 of lactated Ringer’s had been infused, of which virtually all remained in the circulating blood. Thereafter, the fluid kinetics was similar to that previously been found in awake volunteers except for the elimination rate constant (k10), which remained to be very low (0.86 × 10− 3 min− 1). Redistribution of infused fluid from the interstitium to the plasma occurred faster (higher k21) when the arterial pressure was low. No covariance was found between the fixed parameters and preoperatively concentrated urine, the use of sevoflurane or propofol to maintain the anesthesia, or the plasma concentrations of two degradation products of the endothelial glycocalyx, syndecan-1 and heparan sulfate.ConclusionsInduction of general anesthesia interrupted the distribution of lactated Ringer’s solution up to when 16.6 mL kg− 1 of crystalloid fluid had been infused. Plasma volume expansion during this period of time was pronounced.Trial registrationControlled-trials.com (ISRCTN81005631) on May 17, 2016 (retrospectively registered).

A New Method To Evaluate Reaction Kinetics of Acids with Carbonate Rocks Using NMR Diffusion Measurements

In this work, a new method to evaluate the reaction kinetics of different stimulation fluids with carbonate rocks was introduced. NMR diffusion measurements were used to determine the acid diffusion coefficient and the acid tortuous path inside carbonate rocks. Reaction kinetics can also be evaluated using rotating disk apparatus (RDA) in which a disc is rotated in the bulk fluid at different rotational speeds. RDA does not represent the actual, restricted acid diffusion that takes place in the porous media because only the surface of the rock is exposed to the reaction and the acid is not confined in the porous media. NMR diffusion measurements can accurately describe and determine the acid restricted diffusion in porous media. The diffusion coefficient of the acid is a crucial term in describing the reaction kinetics of acids with carbonate rocks. It is also used to predict the optimum injection rate required during the acidizing treatment and the soaking time for different fluids required to remove scales and deposits in the wellbore. The restricted diffusion was determined for different fluids such as GLDA chelating agent, HEDTA chelating agent, and EDTA chelating agent. Core flooding experiments for each fluid were conducted to determine the optimum injection rate. NMR restricted diffusion measurements then were conducted to determine the restricted diffusion and in turn to determine the optimum injection rate. The optimum injection rate estimated from the NMR was compared to that from the core flooding experiments. The results were a good match showing that NMR is a suitable, reliable, and robust method to evaluate reaction kinetics of different fluids with carbonate rocks.

Software Platform for Computation Fluid Dynamics Simulation of Mixing and Crystallization in a Stirred Vessel

Mixing and crystallization are strongly influenced by fluid flow and kinetics in a stirred vessel. Computation fluid dynamics (CFD) simulation is a powerful tool to predict transient behaviors of such processes. In this study, we developed a software that simplifies procedures such as geometry, meshing, simulation, and preprocessing that occur when using CFD. For the development of this software, C# language was employed for a user-friendly interface with a built-in library, generation of user-defined functions for crystallization kinetics, and a translator to generate script language to invoke FLUENT software. To elucidate applications of the developed software, CDF simulation for mixing in a stirred vessel with four different impellers and scale-up of DTB crystallizer from 500 to 3000 L was executed within the framework of this software. Results of both cases were compared with corresponding references and showed good agreements. Examples showed the benefit of this software in saving time and effort, eventually giving a user more time to focus on problem solving strategies.

Fluid management in perioperative and critically ill patients.

Fluid therapy to restore and/or maintain tissue perfusion may affect patient outcomes in perioperative, emergency, and intensive care. Kinetic analyses and outcome-oriented studies have provided more insight into fluid management. Crystalloids are slowly distributed to the interstitial space, and the efficiency (proportion of infused fluid retained in the bloodstream) is 50%−75% as long as infusion continues and may increase up to 100% when the arterial pressure has decreased. Elimination of the infused fluid during general anesthesia and surgery is very slow, amounting to only 10%–20% compared with that in conscious patients. When the endothelial glycocalyx layer is degraded in sepsis or trauma-induced systemic inflammation, turnover of colloids and crystalloids is accelerated and the efficiency is reduced, which may lead to tissue edema, inflammation, poor wound healing, and organ dysfunction. Balanced crystalloids are pragmatic initial resuscitation fluids and improve patient outcomes compared to saline (0.9% sodium chloride). Albumin may be beneficial, but other synthetic colloids appear to increase the risk of acute kidney injury and death among patients in the intensive care unit. Fluid kinetics is likely to change based on patient physiological conditions (e.g., general anesthesia, surgery, stress, dehydration, blood pressure, or inflammation) and fluid types. To maximize efficacy and minimize iatrogenic side effects, fluids should be prescribed based on individual patient factors, disease states, and other treatment remedies.

Object kinetics perception in auto-stereoscopic vision.

In this paper, we study the conditions for the perception of object kinetics, produced by a multiview auto-stereoscopic system and a set of still images. We assess the capabilities and performances of such an optical system to encode complex trajectories and kinetics of objects moving in depth. In particular, we set up rules to create motions with nonuniform velocities, when obtained by motion parallax induced by the observer. We establish a link with plenoptic systems from where we derive applicable scaling rules to ensure stereoscopic vision and to provide fluid motion perception with satisfying visual comfort. Finally, we scale the optical system, thanks to obtained parameters, to emulate the perception of object motions in depth with fluid kinetics and to create impressive motion effects.

Comment on "Theoretical prediction of crystallization kinetics of a supercooled Lennard-Jones fluid" [J. Chem. Phys. 148, 204506 (2018)

First Page

Response to "Comment on 'Theoretical prediction of crystallization kinetics of a supercooled Lennard-Jones fluid'" [J. Chem. Phys. 151, 017101 (2019)

First Page

Water Chemistry in Oil and Gas Operations: Scales Properties and Composition

Oil and gas operations depend heavily on water in many different aspects. Water is present wherever there is hydrocarbon production. It is produced along with the hydrocarbons and helps in mobilizing them. It is also injected into the reservoirs to aid in mobilizing the hydrocarbons, maintain the pressure and increase the recovery of the development project. With water presence, some serious problems occur such as scaling. Scaling is a well-known problematic precipitation caused mainly due to mixing of two incompatible fluids, changes in temperature and pressure conditions and disturbance to thermodynamics and kinetics of reservoir fluids. They can be found at any point of the operations starting down at the formation up to the surface tanks. Scales are directly responsible for compromising the economics and safety of development projects. This review paper is going to include a recap of the importance of water in the oil and gas industry, then review the different types of scales as well as their properties including carbonate and sulfate scales. After that, famous scales from each type is going to be reviewed as well as their properties and precipitation conditions such as Calcium Carbonate CaCO3, Calcium Sulfate CaSO4, Barium Sulfate BaSO4 and Strontium Sulfate SrSO4. Moreover, common practices and precautions steps in the industry are going to be reviewed as well. Finally, the paper presents the common practices used by the operators for scale removal.

Experimental and numerical analysis of the magnetophoresis of magnetic nanoparticles under the influence of cylindrical permanent magnet

Abstract Dye-tracing and concentration-measuring experiments are carried out to investigate the magnetophoresis of magnetic nanoparticles (MNP) in the presence of an external cylindrical permanent magnet. The magnetophoresis of MNP, inducing an obvious forced-convective flowing of the carrier fluid, which can be observed by visualizing flowing of carrier fluid, results in a temporal and spatial variation of particle concentration. Moreover, in order to get insight into the physical mechanisms of magnetophoresis of MNP, a coupled particle-fluid analysis, in which the non-linear drift-diffusion differential equation is incorporated into the Navier-Stokes equation, is adopted to discuss the influence of particle-fluid interaction on the variation of particle concentration and the kinetics of carrier fluid. It is worth noting that the equivalent current source (ECS) method is adopted to obtain a closed-form field analysis, which provides exactly prediction of the Kelvin force and enables magnetophoretic analysis more efficient. In dye-tracing experiments, an obvious vortex can be observed as the methylene blue moves with the convection of carrier fluid. Furthermore, this phenomenon is also predicted by using the coupled particle-fluid model. A comparison between the experimental and numerical results shows that the hydrodynamic interactions between MNP and carrier fluid plays an important role in inducing forced-convective flowing of carrier fluid and enhancing the magnetophoresis of MNP. Furthermore, these results also denote that the coupled particle-fluid model provides a more efficient and accurate method in investigating the magnetophoresis of MNP.

Rumen parameters and passage rate in cattle fed diets based on sugarcane hydrolyzed with calcium oxide

Nine non-lactating Holstein x Gyr cattle were fed with rations based on chopped sugarcane supplied in natura (control) or hydrolyzed (fresh matter basis) for 24 h with 1% or 2% calcium oxide (CaO), which corresponds to 3.1% or 6.2% CaO on a dry matter (DM) basis, respectively. Ruminal parameters (pH and ammonia N, acetate, propionate and butyrate concentrations) as well as the kinetics of fluid and particulate passage in the gastrointestinal tract from cattle were evaluated. A design using three 3 x 3 contemporaneous Latin Squares (LS) was adopted. The studies of kinetics of fluid and particulate passage were performed using the external markers cobalt-EDTA and chromium-mordanted-NDF, respectively. The ruminal parameters were analyzed according to a 3 x 3 LS replicated three times with repeated measures in time using mixed models that included the fixed effects of treatment (level of CaO), time of sampling and their interaction and the following random effects: LS, animal(LS), period of LS and period*animal (LS). The kinetic parameters of fluid and particulate passage were analyzed using mixed models with treatment as a fixed effect and period of LS, animal(LS) and LS as random effects. The linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. Significant differences were declared at P ? 0.05. No treatment*time interaction was observed (P &gt; 0.05) for any ruminal parameter. A linear effect (P = 0.0279) of CaO inclusion on ruminal pH was observed, but there were no effects (P &gt; 0.05) of the treatments on the ammonia N, acetate, butyrate and total volatile fatty acid ruminal concentrations. There was a quadratic effect (P = 0.05) of the addition of CaO on the ruminal propionate concentration. There was no effect (P &gt; 0.05) of the treatments on the particulate rate of passage in the rumen as well as on the mean retention time in this compartment and in the total gastrointestinal tract. On the other hand, the addition of CaO to sugarcane promoted a linear increase (P = 0.0258) in the particulate post-ruminal passage rate and, consequently, a linear reduction (P = 0.0363) of the mean retention time in the cecum-proximal colon. There was no effect (P &gt; 0.05) of the sugarcane hydrolysis with CaO on the ruminal parameters of the kinetics of fluid passage (dilution rate, retention time and turnover rate). The addition of 3.1% or 6.2% CaO on a DM basis (1% or 2% CaO on a fresh matter basis, respectively) of sugarcane does not improve ruminal fermentation, nor does it increase the fluid or particulate passage in the rumen of non-lactating Holstein x Gyr cattle.

Modeling and experiment study on inter-electrode gap in electrochemical machining with a floating cathode for rotary parts

A small inter-electrode gap is necessary to improve the machining accuracy in electrochemical machining (ECM). In order to achieve a stable small gap processing, this paper proposes a new concept of ECM method with a floating cathode. Aiming at the problem of gap regulation in this method, the modeling and experimental research are carried out, taking the electrochemical machining with a large span floating cathode of dual round outlets for rotary parts as an example. A mathematical model of machining gap is established based on fluid mechanics and kinetics of electrode processes, from which the relationships between the gap and process parameters are analyzed. Through the experimental method, the influence law of the variation of process parameters on the gap is further studied, and the mathematical model is modified. Comparisons between the modified theoretical model calculation results and experimental results show that considering only the flow field conditions, the average error of the inter-electrode gap obtained by experiment and model during work-piece rest and work-piece rotation is 6.1% and 4.3%; considering the flow field and electric field conditions, the average error of the inter-electrode gap during work-piece rest and work-piece rotation is 4.1% and 5.1%. The study demonstrates that a stable inter-electrode gap can be formed in ECM through the liquid electrolyte to support the cathode, and the inter-electrode gap was correlated with the electrolyte flowrate, current, and electrolyte pressure, so it is a feasible method to regulate the gap by adjusting the electrolyte flow or the inter-electrode current during processing, which provides a new way for gap formation and control in high-precision electrochemical machining.

Fasting-dependent Vascular Permeability Enhancement in Brown Adipose Tissues Evidenced by Using Carbon Nanotubes as Fluorescent Probes

Brown adipose tissue (BAT), which is composed of thermogenic brown adipocytes (BA) and non-parenchymal components including vasculatures and extracellular matrix, contribute to the maintenance of body temperature. BAT distribution is detected by positron emission tomography-computed tomography (PET/CT) using 18F-fluorodeoxy glucose (18F-FDG) or single-photon-emission computed tomography-computed tomography (SPECT/CT) using [123/125I]-beta-methyl-p-iodophenyl-pentadecanoic acid. Although sympathetic nerve activity and thermogenic capacity of BA is downregulated under fasting conditions in mice, fasting-dependent structural changes and fluid kinetics of BAT remain unknown. Here we show that the fasting induces fine and reversible structural changes in the non-parenchymal region in murine BAT with widened intercellular spaces and deformed collagen bands as revealed by electron microscopy. Interestingly, a newly introduced near infrared fluorescent probe of single-walled carbon nanotubes (CNTs) coated with phospholipid polyethylene glycol (PLPEG) easily demonstrated enhanced vascular permeability in BAT by the fasting. PLPEG-CNTs extravasated and remained in intercellular spaces or further redistributed in parenchymal cells in fasted mice, which is a previously unknown phenomenon. Thus, PLPEG-CNTs provide a powerful tool to trace fluid kinetics in sub-tissue levels.

Analysis of continuous wave diode pumped cesium laser with gas circulation: experimental and theoretical studies.

Analysis of the operation of flowing-gas low power DPALs is crucial for designing high power devices. In particular, the comparison between the measured and calculated temperature rise in the laser cell makes it possible to estimate the contribution of the quenching of the alkali atoms electronic states to the gas heating. Here we report on an experimental and theoretical study of continuous wave flowing-gas Cs DPAL with He and CH4 buffer gases, flow velocities of 1-4 m/s and pump powers of 30-65 W. In the calculations we used a 3D computational fluid dynamics model, solving the fluid mechanics and kinetics equations relevant to the laser operation. Maximum CW output power of 24 W with a slope efficiency of 48% was obtained. The experimental and theoretical values of the power and gas temperature are in good agreement. The lasing power was not affected by the flow velocity at this range of pump power and the gas temperature rise was only several degrees. It was found that the best agreement between the measured and calculated temperature rise is achieved for quenching cross-section ~0.05 Å2.

Theoretical prediction of crystallization kinetics of a supercooled Lennard-Jones fluid.

The first order curvature correction to the crystal-liquid interfacial free energy is calculated using a theoretical model based on the interfacial excess thermodynamic properties. The correction parameter (δ), which is analogous to the Tolman length at a liquid-vapor interface, is found to be 0.48 ± 0.05 for a Lennard-Jones (LJ) fluid. We show that this curvature correction is crucial in predicting the nucleation barrier when the size of the crystal nucleus is small. The thermodynamic driving force (Δμ) corresponding to available simulated nucleation conditions is also calculated by combining the simulated data with a classical density functional theory. In this paper, we show that the classical nucleation theory is capable of predicting the nucleation barrier with excellent agreement to the simulated results when the curvature correction to the interfacial free energy is accounted for.