Evaluation of Microparticle Leakage during DALI LDL Adsorption in a Simulated Clinical Setting

2000 ◽  
Vol 23 (5) ◽  
pp. 338-344 ◽  
Author(s):  
O. Heinemann ◽  
T. Bosch
Keyword(s):  
Clear Cell ◽  
Treatment Phase ◽  
Clinical Situation ◽  
Particle Sizes ◽  
Flow Rates ◽  
Particle Release ◽  
Simulation Procedure ◽  
Extracorporeal Circuits ◽  
Particle Counts ◽  
Free Media

The aim of the present study was to investigate microparticle (Mp) leakage during simulated LDL-hemoperfusion using 12 DALI 750 adsorbers and the original DALI hardware under conditions strictly comparable to the clinical situation. Thus, the sessions were divided into 4 sections, i.e. priming and preparation of the adsorber followed by treatment (6–7 L at a flow rate of 60 ml/min) and reinfusion. As Mp counts can be performed only in clear, cell-free media, blood was replaced by normal saline in sections 2–4 of the simulated sessions. Mp counts were analysed for ≥ 2, ≥ 5, ≥ 10 and ≥ 25 μm particle sizes in the efferent line post adsorber using a standard light blockage method. As there are no official thresholds for particle release in extracorporeal circuits, the limits for infusion of large fluid volumes of 500, 100 (80), 25 and 5 (3) Mp/ml according to the Europäische Arzneimittelbuch, the British and American Pharmacopoeias were used. Mean particle counts for the sections 3 and 4 in which the patient is connected to the efferent line were 19, 7, 2 and 0 Mp/ml and amounted to < 10% of the above mentioned limits. Modifications of the standard simulation procedure by inserting additional pump stops or using different flow rates during the treatment phase slightly increased Mp leakage, but never exceeded the prescribed limits. In summary, no undue particle release could be detected during simulations of the clinical DALI LDL-adsorption procedure.

scholarly journals COVID-19 in the Clinic: Human Testing of an Aerosol Containment Mask for Endoscopic Clinic Procedures

2021 ◽  
pp. 019459982110291
Author(s):  
Elisabeth H. Ference ◽  
Wihan Kim ◽  
John S. Oghalai ◽  
Clayton B. Walker ◽  
Jee-Hong Kim ◽  
...  
Keyword(s):  
Particle Size ◽  
Health Care Workers ◽  
Aerosol Particles ◽  
Random Fluctuation ◽  
Particle Sizes ◽  
Level Of Evidence ◽  
Normal Breathing ◽  
Care Workers ◽  
3D Printed ◽  
Particle Counts

Objective To create an aerosol containment mask (ACM) for common otolaryngologic endoscopic procedures that also provides nanoparticle-level protection to patients. Study Design Prospective feasibility study . Setting In-person testing with a novel ACM. Methods The mask was designed in Solidworks and 3D printed. Measurements were made on 10 healthy volunteers who wore the ACM while reading the Rainbow Passage repeatedly and performing a forced cough or sneeze at 5-second intervals over 1 minute with an endoscope in place. Results There was a large variation in the number of aerosol particles generated among the volunteers. Only the sneeze task showed a significant increase compared with normal breathing in the 0.3-µm particle size when compared with a 1-tailed t test ( P = .013). Both the 0.5-µm and 2.5-µm particle sizes showed significant increases for all tasks, while the 2 largest particle sizes, 5 and 10 µm, showed no significant increase (both P < .01). With the suction off, 3 of 30 events (2 sneeze events and 1 cough event) had increases in particle counts, both inside and outside the mask. With the suction on, 2 of 30 events had an increase in particle counts outside the mask without a corresponding increase in particle counts inside the mask. Therefore, these fluctuations in particle counts were determined to be due to random fluctuation in room particle levels. Conclusion ACM will accommodate rigid and flexible endoscopes plus instruments and may prevent the leakage of patient-generated aerosols, thus avoiding contamination of the room and protecting health care workers from airborne contagions. Level of evidence 2

Flow Dynamics Investigation of CO2/CH4 Gas Mixture through Porous Media Using Computational Approach

2014 ◽  
Vol 625 ◽  
pp. 369-372
Author(s):  
Ali Qasim ◽  
M. Zamri Abdullah ◽  
K.K. Lau ◽  
Nor Adilla
Keyword(s):  
Porous Media ◽  
Packed Column ◽  
Pilot Scale ◽  
Computational Approach ◽  
Flow Dynamics ◽  
Velocity Variation ◽  
Particle Sizes ◽  
Flow Rates ◽  
High Pressure Adsorption ◽  
Adsorbent Particle

The following study involves the investigation of hydrodynamics inside the packed column both at laboratory scale which is HPVA high pressure adsorption analyzer chamber and pilot scale. The simulations are performed in ANSYS FLUENT14. Velocity variation due to porous media along with the pressure gradient for different adsorbent particle sizes and varying flow rates are obtained and compared for both the scales. Simulation is based on the criterion which identifies the emergence of non-Darcy flow.

Computational Fluid Dynamics Simulation of Flow of Exhaled Particles From Powered-Air Purifying Respirators

2019 ◽  
Author(s):  
Susan S. Xu ◽  
Zhipeng Lei ◽  
Ziqing Zhuang ◽  
Michael Bergman
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particle Size ◽  
Simulation Study ◽  
Particle Concentration ◽  
Air Flow ◽  
Dynamics Simulation ◽  
Cfd Modeling ◽  
Particle Sizes ◽  
Flow Rates

Abstract In surgical settings, infectious particulate wound contamination is a recognized cause of post-operative infections. Powered air-purifying respirators (PAPRs) are widely used by healthcare workers personal protection against infectious aerosols. Healthcare infection preventionists have expressed concern about the possibility that infectious particles expelled from PAPR exhalation channels could lead to healthcare associated infections, especially in operative settings where sterile procedural technique is emphasized. This study used computational fluid dynamics (CFD) modeling to simulate and visualize the distribution of particles exhaled by the PAPR wearer. In CFD simulations, the outward release of the exhaled particles, i.e., ratio of exhaled particle concentration outside the PAPR to that of inside the PAPR, was determined. This study also evaluated the effect of particle sizes, supplied air flow rates, and breathing work rates on outward leakage. This simulation study for the headform and loose-fitting PAPR system included the following four main steps: (1) preprocessing (establishing a geometrical model of a headform wearing a loose-fitting PAPR by capturing a 3D image), (2) defining a mathematical model for the headform and PAPR system, and (3) running a total 24 simulations with four particle sizes, three breathing workloads and two supplied-air flow rates (4 × 3 × 2 = 24) applied on the digital model of the headform and PAPR system, and (4) post-processing the simulation results to visually display the distribution of exhaled particles inside the PAPR and determine the particle concentration of outside the PAPR compared with the concentration inside. We assume that there was no ambient particle, and only exhaled particles existed. The results showed that the ratio of the exhaled particle concentration outside to inside the PAPR were influenced by exhaled particle sizes, breathing workloads, and supplied-air flow rates. We found that outward concentration leakage from PAPR wearers was approximately 9% with a particle size of 0.1 and 1 μm at the light breathing and 205 L/min supplied-air flow rates, which is similar to the respiratory physiology of a health care worker in operative settings, The range of the ratio of exhaled particle concentration leaking outside the PAPR to the exhaled particle concentration inside the PAPR is from 7.6% to 49. We found that supplied air flow rates and work rates have significant impact on outward leakage, the outward concentration leakage increased as particle size decreased, breathing workload increased, and supplied-air flow rate decreased. The results of our simulation study should help provide a foundation for future clinical studies.

Development and Validation of an Augmentation to the Commercial CFD Software FLUENT™ Enabling the Tracking of Ellipsoidal Particles in Low Reynolds Number Flows

2009 ◽  
Author(s):  
Kevin T. Shanley ◽  
Goodarz Ahmadi
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Spherical Particles ◽  
Particle Sizes ◽  
Flow Rates ◽  
Low Reynolds Number Flows ◽  
Low Reynolds ◽  
Lagrangian Tracking ◽  
Reynolds Number Flows ◽  
Strong Agreement

A majority of the commercially available computational fluid dynamics packages are equipped with a module for Lagrangian tracking of spherical particles. No such module exists in an off-the-shelf product enabling the Lagrangian tracking of ellipsoidal shaped particles. This work took advantage of the user defined function facilities provided in FLUENT™ to gain this capability. Three user defined functions were implemented to transpose the spherical geometry to an ellipsoidal geometry. The orientation of the ellipsoid was determined by numerically solving the equations of rotational motion. Hydrodynamic drag was taken to be a function of Reynolds number and orientation. Two tests were performed to validate the rotational and translational motions of the ellipsoid in low Reynolds number flows. First, a simple shear configuration was examined with a single particle suspended at the center of the domain. The particle was allowed to rotate without translation. This was repeated for several particle sizes and flow rates and the simulated time for the particle to perform a single rotation was compared with the theoretical findings of Jeffery (1922). The results showed strong agreement for the range of particle sizes and flow rates examined. Second, a horizontal pipe with circular cross-section setup was simulated. Particles were injected from the pipe inlet and their motions were analyzed. Deposition efficiency was shown to be a function of aspect ratio and dimensionless relaxation time. Strong agreement was shared with a previously published empirical expression.

Particle Size and Concentration Effects on Solid Particle Erosion With PIV Measurements of Particle Velocities

2020 ◽  
Author(s):  
Yeshwanth R. Rajkumar ◽  
Siamack A. Shirazi ◽  
Soroor Karimi
Keyword(s):  
Particle Size ◽  
Solid Particle ◽  
Particle Flow ◽  
Solid Particle Erosion ◽  
Average Particle ◽  
Particle Sizes ◽  
Particle Erosion ◽  
Concentration Effects ◽  
Flow Rates ◽  
Particle Velocities

Abstract Solid particle erosion is one of the most commonly encountered problems faced by the oil and gas industries during production and transportation processes. The severity of solid particle erosion is affected by multitude of factors such as particle properties, fluid flow properties and flow geometry, flow regime, and target material properties. The present work investigates the effect of particle size on solid particle erosion in gas flows. Sharp quartz particles with nominal sizes of 75, 150, 300 and 600 μm are used in this work. Particle Image Velocimeter (PIV) is used to measure the particles velocities distributions for various particle flow rates. An average particle velocity of 24 m/s is used to conduct erosion experiments for various particle sizes and two particle rates on Stainless Steel 316 at two different impact angles of 15 and 90 degrees. Comparison of measurements for two particle flow rates of approximately 0.02% and 0.002% by volumes demonstrates that increased particle flow rate can affect the carrier fluid’s flow field and change particle velocities within the carrying fluid. In the erosion experiments, the magnitude of erosion ratio increases as there is an increase in particle size. A preliminary erosion model is developed that can be used in CFD simulations of solid particle erosion for various particle sizes.

Plasma Chemical Synthesis of Aluminum Nitride Nanopowder

2019 ◽  
Vol 822 ◽  
pp. 628-633 ◽  
Author(s):  
Pavel Alexandrovich Novikov ◽  
Artem Eduardovich Kim ◽  
Nikolay Evgenievich Ozerskoi ◽  
Qing Sheng Wang ◽  
Anatoly Anatolyevich Popovich
Keyword(s):  
Aluminum Nitride ◽  
Gas Flow ◽  
Granulometric Composition ◽  
Pure Aluminum ◽  
Nitrogen Plasma ◽  
Particle Sizes ◽  
Plasma Chemical ◽  
Flow Rates ◽  
Inductively Coupled ◽  
Micron Powder

We studied in detail the process of producing nanosized aluminum nitride using inductively coupled nitrogen plasma from micron powder of pure aluminum. The phase and granulometric composition of the obtained nanopowders, as well as their morphology, was studied. The influence of various parameters (initial components, gas flow rates, feed rate of the initial powder, etc.) on the synthesis result is determined. Received nanodispersed Al-AlN powder with particle sizes up to 300 nm and aluminum nitride content from 11.6 to 48.8%.

Air handling characteristics of five membrane oxygenators

Perfusion ◽  
1994 ◽  
Vol 9 (5) ◽  
pp. 357-362 ◽  
Author(s):  
AP Mehra ◽  
A. Akins ◽  
A. Maisuria ◽  
BE Glenville
Keyword(s):  
Flow Rate ◽  
Venous Drainage ◽  
Clinical Situation ◽  
Low Flow ◽  
Time Interval ◽  
Arterial Line ◽  
Flow Rates ◽  
Handling Characteristics ◽  
Wide Range ◽  
Membrane Oxygenators

This project looked at the potential of five different membrane oxygenators to allow passage of catastrophic quantities of air in a clinically simulated environment. All the oxygenators were set up in an identical circuit using heparinized human blood as the perfusate. The study was carried out at flow rates ranging from 1.0 to 6.0 I/min. The clinical situation of obstructed venous drainage was simulated by clamping the venous return line at each respective flow rate, while the initial level of blood in the open system hard shell venous reservoir was maintained at 600 ml. The time interval between the application of the clamp on the venous line and the first appearance of macroscopic air in the arterial line was recorded at each level of flow rate. A graph of time versus flow rate was plotted for each oxygenator type. At a flow rate of 6 I/min, the Safe II oxygenator took 20 seconds to allow passage of air after the venous line was clamped, while it took the Bentley Univox Oxygenator only 10 seconds. The Dideco oxygenator, which has a valve incorporated in its reservoir, did not, however, allow any air to be pumped forward at all. At low flow rates, some of the oxygenators offered protection against passage of air into the arterial line. Thus the Cobe oxygenator offered protection at flow rates of less than 2 I/min, the Safe II oxygenator at flow rates of up to 2.5 I/min and the Bard oxygenator at flow rates up to 3 I/min. This study has demonstrated the potential of membrane oxygenators to allow passage to clinical quantities of air into the arterial line. This study also has demonstrated that the top to bottom flow feature offers protection against passage of air at low flow rates only, while a simple valve is quite effective in preventing passage of air at a wide range of clinically relevant flow rates.

Tubing Spallation in Extracorporeal Circuits. An in Vitro Study Using an Electronic Particle Counter

1992 ◽  
Vol 15 (4) ◽  
pp. 222-228 ◽  
Author(s):  
J.C. Briceño T. ◽  
T. M. Runge
Keyword(s):  
Flow Rate ◽  
In Vitro Study ◽  
Blood Flow Rate ◽  
Vitro Study ◽  
Occlusion Pressure ◽  
Roller Pump ◽  
Extracorporeal Circuits ◽  
Electronic Particle Counter ◽  
Particle Counts

The roller pump is the most common pumping device used in extracorporeal circulation (ECC). The interaction between the roller and tubing causes tubing spallation. Spallation has been associated with complications in ECC. Previous spallation studies present mixed results, including a decrease in the number of circulating particles. The objective of this work is to perform an in vitro study of tubing spallation which elucidates the causes of the particle sequestration, and the effect of tubing material, blood flow rate and duration of the procedure upon spallation. A sampling method minimizing background counts was devised. Silicone and PVC tubing were tested under normal and tight occlusion pressure at typical cardiopulmonary bypass and hemodialysis flow rates, for circulating times up to 4 h. Occlusion pressure and flow rate highly influenced the amount of spallation produced. Particle sequestration was noted and aggregation of the plastic particles was demonstrated. We conclude that, at least in vitro, aggregation causes the decrease in the particle counts and the misleading results obtained in most spallation studies using a Coulter counter.

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