A schlieren optical study of the human cough with and without wearing masks for aerosol infection control

Various infectious agents are known to be transmitted naturally via respiratory aerosols produced by infected patients. Such aerosols may be produced during normal activities by breathing, talking, coughing and sneezing. The schlieren optical method, previously applied mostly in engineering and physics, can be effectively used here to visualize airflows around human subjects in such indoor situations, non-intrusively and without the need for either tracer gas or airborne particles. It accomplishes this by rendering visible the optical phase gradients owing to real-time changes in air temperature. In this study, schlieren video records are obtained of human volunteers coughing with and without wearing standard surgical and N95 masks. The object is to characterize the exhaled airflows and evaluate the effect of these commonly used masks on the fluid-dynamic mechanisms that spread infection by coughing. Further, a high-speed schlieren video of a single cough is analysed by a computerized method of tracking individual turbulent eddies, demonstrating the non-intrusive velocimetry of the expelled airflow. Results show that human coughing projects a rapid turbulent jet into the surrounding air, but that wearing a surgical or N95 mask thwarts this natural mechanism of transmitting airborne infection, either by blocking the formation of the jet (N95 mask), or by redirecting it in a less harmful direction (surgical mask).

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BIMG-13. A NOVEL RADIOPHARMACEUTICAL ([18F]DASA-23) TO MONITOR PYRUVATE KINASE M2 INDUCED GLYCOLYTIC REPROGRAMMING IN GLIOBLASTOMA

Neuro-Oncology Advances ◽

10.1093/noajnl/vdab024.012 ◽

2020 ◽

Vol 3 (Supplement_1) ◽

pp. i3-i4

Author(s):

Corinne Beinat ◽

Chirag Patel ◽

Tom Haywood ◽

Surya Murty ◽

Lewis Naya ◽

...

Keyword(s):

Cell Culture ◽

Pyruvate Kinase ◽

Cancer Metabolism ◽

Human Subjects ◽

Normal Brain ◽

Healthy Human ◽

Pyruvate Kinase M2 ◽

Molar Activity ◽

Pet Tracer ◽

Human Volunteers

Abstract BACKGROUND Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain, making it an important biomarker of cancer glycolytic re-programming. We describe the bench-to-bedside development, validation, and translation of a novel positron emission tomography (PET) tracer to study PKM2 in GBM. Specifically, we evaluated 1-((2-fluoro-6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and GBM patients. METHODS [18F]DASA-23 was synthesized with a molar activity of 100.47 ± 29.58 GBq/µmol and radiochemical purity >95%. We performed initial testing of [18F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next we produced [18F]DASA-23 under current Good Manufacturing Practices United States Food and Drug Administration (FDA) oversight, and evaluated it in healthy volunteers and a pilot cohort of patients with gliomas. RESULTS In mouse imaging studies, [18F]DASA-23 clearly delineated the U87 GBM from the surrounding healthy brain tissue and had a tumor-to-brain ratio (TBR) of 3.6 ± 0.5. In human volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In GBM patients, [18F]DASA-23 successfully outlined tumors visible on contrast-enhanced magnetic resonance imaging (MRI). The uptake of [18F]DASA-23 was markedly elevated in GBMs compared to normal brain, and it was able to identify a metabolic non-responder within 1-week of treatment initiation. CONCLUSION We developed and translated [18F]DASA-23 as a promising new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These encouraging results warrant further clinical evaluation of [18F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.

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Thermo-Fluid-Dynamic Design of Reciprocating Compressor Cylinders by Fluid Structure Interaction (FSI)

ASME 2011 Pressure Vessels and Piping Conference: Volume 5 ◽

10.1115/pvp2011-57059 ◽

2011 ◽

Cited By ~ 2

Author(s):

Riccardo Traversari ◽

Alessandro Rossi ◽

Marco Faretra

Keyword(s):

High Speed ◽

Fluid Dynamic ◽

Fluid Structure Interaction ◽

Classical Equation ◽

Flow Coefficient ◽

Reciprocating Compressor ◽

Complex Situation ◽

Fluid Structure ◽

Associated Gas ◽

Structure Interaction

Pressure losses at the cylinder valves of reciprocating compressors are generally calculated by the classical equation of the flow through an orifice, with flow coefficient determined in steady conditions. Rotational speed has increased in the last decade to reduce compressor physical dimensions, weight and cost. Cylinder valves and associated gas passages became then more and more critical, as they determine specific consumption and throughput. An advanced approach, based on the new Fluid Structure Interaction (FSI) software, which allows to deal simultaneously with thermodynamic, motion and deformation phenomena, was utilized to simulate the complex situation that occurs in a reciprocating compressor cylinder during the motion of the piston. In particular, the pressure loss through valves, ducts and manifolds was investigated. A 3D CFD Model, simulating a cylinder with suction and discharge valves, was developed and experimentally validated. The analysis was performed in transient and turbulent condition, with compressible fluid, utilizing a deformable mesh. The 3D domain simulating the compression chamber was considered variable with the law of motion of the piston and the valve rings mobile according to the fluid dynamic forces acting on them. This procedure is particularly useful for an accurate valve loss evaluation in case of high speed compressors and heavy gases. Also very high pressure cylinders, including LDPE applications, where the ducts are very small and MW close to the water one, can benefit from the new method.

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Three-Dimensional CFD Analysis of Meshing Losses in a Spur Gear Pair

Volume 5B: Heat Transfer ◽

10.1115/gt2018-77141 ◽

2018 ◽

Author(s):

T. Fondelli ◽

D. Massini ◽

A. Andreini ◽

B. Facchini ◽

F. Leonardi

Keyword(s):

High Speed ◽

Numerical Study ◽

Fluid Dynamic ◽

Three Dimensional ◽

Spur Gear ◽

Computational Domain ◽

Gear Pair ◽

Transient Pressure ◽

Numerical Effort ◽

Free Environment

The reduction of fluid-dynamic losses in high speed gearing systems is nowadays increasing importance in the design of innovative aircraft propulsion systems, which are particularly focused on improving the propulsive efficiency. Main sources of fluid-dynamic losses in high speed gearing systems are windage losses, inertial losses resulting by impinging oil jets used for jet lubrication and the losses related to the compression and the subsequent expansion of the fluid trapped between gears teeth. The numerical study of the latter is particularly challenging since it faces high speed multiphase flows interacting with moving surfaces, but it paramount for improving knowledge of the fluid behavior in such regions. The current work aims to analyze trapping losses in a gear pair by means of three-dimensional CFD simulations. In order to reduce the numerical effort, an approach for restricting computational domain was defined, thus only a portion of the gear pair geometry was discretized. Transient calculations of a gear pair rotating in an oil-free environment were performed, in the context of conventional eddy viscosity models. Results were compared with experimental data from the open literature in terms of transient pressure within a tooth space, achieving a good agreement. Finally, a strategy for meshing losses calculation was developed and results as a function of rotational speed were discussed.

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Lymphocyte metallothionein mRNA responds to marginal zinc intake in human volunteers

British Journal Of Nutrition ◽

10.1017/s0007114500002117 ◽

2000 ◽

Vol 84 (5) ◽

pp. 747-756 ◽

Cited By ~ 37

Author(s):

Adrian K. Allan ◽

Gabrielle M. Hawksworth ◽

Leslie R. Woodhouse ◽

Barbara Sutherland ◽

Janet C. King ◽

...

Keyword(s):

Human Subjects ◽

Baseline Period ◽

Zn Deficiency ◽

Pcr Assay ◽

Laser Induced Fluorescence Detection ◽

Pcr Product ◽

Human Volunteers ◽

Actin Mrna ◽

Zn Status ◽

Diagnostic Indicator

Marginal Zn deficiency is thought to be prevalent in both developed and developing countries. However, the extent of Zn deficiency is not known, due to the lack of a reliable diagnostic indicator. Blood plasma and erythrocyte concentrations of metallothionein (MT) reflect Zn status, but measurement of MT is dependent on the availability of sensitive immunoassays. Our aim was to show whether measurement of T lymphocyte MT-2A mRNA, using a competitive reverse transcriptase (RT)–polymerase chain reaction (PCR) assay, could indicate Zn status in human subjects in a residential Zn-depletion study. In the study, the Zn intake of seven volunteers was maintained at 13·7 mg/d for 5 weeks (baseline) followed by 4·6 mg/d for 10 weeks (marginal intake) and then 13·7 mg/d (repletion) for 5 weeks. The quantitative assay was developed using standard techniques and concentrations of MT-2A mRNA were normalized by reference to β-actin mRNA which was also measured by competitive RT–PCR assay. An alternative method of measuring the PCR product using capillary electrophoresis with laser-induced fluorescence detection was also evaluated. There was considerable inter-individual variation in MT-2A mRNA concentration and the mean level at the end of the baseline period was 10·3 (SE 3·7) fg MT-2A mRNA/pg β-actin mRNA, which then decreased by 64 % during the low Zn intake period. After repletion, MT-2A mRNA returned to baseline concentrations. In contrast, plasma Zn was unchanged by marginal Zn intake or repletion. The effect of low Zn in all individuals was consistent. We conclude that this assay is a sensitive method of evaluating marginal changes in dietary Zn intake.

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A CFD Study on the Dynamic Coefficients of Labyrinth Seals

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-68292 ◽

2012 ◽

Cited By ~ 4

Author(s):

Donghui Zhang ◽

Chester Lee ◽

Michael Cave

Keyword(s):

High Speed ◽

Fluid Dynamic ◽

Labyrinth Seal ◽

Leakage Flow ◽

Labyrinth Seals ◽

Dynamic Coefficients ◽

Rotating Impeller ◽

Coupling Stiffness ◽

Direct Stiffness ◽

Compressor Efficiency

Labyrinth seals are widely used in gas compressors to reduce internal leakage and increase the compressor efficiency. Due to the eccentricity between the rotating impeller and the stationary part as *well as the shaft whirling motion, forces are generated when the leakage flow passing through the cavities and the seals. For a lot of applications with high speed and pressure, these forces can drive the system unstable. Thus, predicting the forces accurately become a very important for compressor rotordynamic designs. A lot of research and studies has been done to the seals itself, including bulk flow method, computational fluid dynamic (CFD) and test measurement. The seal and leakage flow interaction forces can be predicted relatively accurate. But very few research treat the seal and cavities as one component interacting with the leakage flow and produce the forces. This paper presents results of CFD investigations on the dynamic coefficients of one typical impeller eye seal and front cavity. The CFD results show that large forces are generated in the front cavity due to circumferential uniform pressure distribution, which caused by the downstream labyrinth seal. The forces generated in the front cavity are more than in the front seal. It was found that the inertia, damping, and stiffness are proportional to average pressure. The cross-coupling stiffness increases with speed with power of 2 while the direct stiffness increases with speed with power of about 1.7.

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CFD Modelling of Loss of Vacuum Accident (LOVA) for CFETR

Volume 8: Computational Fluid Dynamics (CFD); Nuclear Education and Public Acceptance ◽

10.1115/icone26-81970 ◽

2018 ◽

Author(s):

Youyou Xu ◽

Songlin Liu ◽

Xiaoman Cheng ◽

Xuebin Ma

Keyword(s):

High Speed ◽

Reverse Flow ◽

Fluid Dynamic ◽

Fusion Energy ◽

Normal Operation ◽

Vacuum Vessel ◽

Cfd Modelling ◽

Ansys Cfx ◽

Section Area ◽

Break Area

Chinese Fusion Engineering Testing Reactor (CFETR) is a tokamak-type machine and next device in the roadmap for the realization of fusion energy in China, which aims to bridge the gaps between the International Thermonuclear Experimental Reactor (ITER) and the demonstration reactor (DEMO) [1]. The accident sequence starting from loss of vacuum accident (LOVA) is an important issue concerning the performance of CFETR. During LOVA, air will leak into the vacuum vessel (VV) causing fast pressurization of VV. At the same time, the high speed airflow jet will result in migration and re-suspension of the large quantity of tungsten dust produced and deposited in the lower part of plasma chamber, causing possibilities of radioactive dust leakage into the workshop and environment. In order to conduct a comprehensive analysis of the accident sequence, firstly, the airflow characteristics of LOVA should be studied. In this article, a postulated rupture of different section area is assumed due to a failed component at the equatorial port level. The computational fluid dynamic (CFD) modelling of LOVA was conducted by ANSYS CFX. The results show that the break area has significant influences on the characteristics of the airflow. Two swirling airflows are formed in the upper and lower part of the torus. The airflow characteristics are quite different when the LOVA happens during maintenance or during normal operation. A reverse flow occurs when the LOVA happens during normal operation. Yet can not be observed when LOVA occurs during maintenance. The results are the basis to the further safety study of CFETR such as the re-suspension, migration and explosion of dust.

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Numerical Optimization of a Stall Margin Enhancing Recirculation Channel for an Axial Compressor

Fluids ◽

10.3390/fluids4020088 ◽

2019 ◽

Vol 4 (2) ◽

pp. 88

Author(s):

Motoyuki Kawase ◽

Aldo Rona

Keyword(s):

High Speed ◽

High Performance ◽

Fluid Dynamic ◽

Axial Compressor ◽

Leading Edge ◽

Navier Stokes ◽

Test Case ◽

Dynamic Simulations ◽

Stall Margin ◽

Casing Treatment

A proof of concept is provided by computational fluid dynamic simulations of a new recirculating type casing treatment. This treatment aims at extending the stable operating range of highly loaded axial compressors, so to improve the safety of sorties of high-speed, high-performance aircraft powered by high specific thrust engines. This casing treatment, featuring an axisymmetric recirculation channel, is evaluated on the NASA rotor 37 test case by steady and unsteady Reynolds Averaged Navier Stokes (RANS) simulations, using the realizable k-ε model. Flow blockage at the recirculation channel outlet was mitigated by chamfering the exit of the recirculation channel inner wall. The channel axial location from the rotor blade tip leading edge was optimized parametrically over the range −4.6% to 47.6% of the rotor tip axial chord c z . Locating the channel at 18.2% c z provided the best stall margin gain of approximately 5.5% compared to the untreated rotor. No rotor adiabatic efficiency was lost by the application of this casing treatment. The investigation into the flow structure with the recirculating channel gave a good insight into how the new casing treatment generates this benefit. The combination of stall margin gain at no rotor adiabatic efficiency loss makes this design attractive for applications to high-speed gas turbine engines.

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The E-wave propagation index (EPI): A novel echocardiographic parameter for prediction of left ventricular thrombus. Derivation from computational fluid dynamic modeling and validation on human subjects

International Journal of Cardiology ◽

10.1016/j.ijcard.2016.10.079 ◽

2017 ◽

Vol 227 ◽

pp. 662-667 ◽

Cited By ~ 8

Author(s):

Thura T. Harfi ◽

Jung-hee Seo ◽

Hayder S. Yasir ◽

Nathaniel Welsh ◽

Susan A. Mayer ◽

...

Keyword(s):

Wave Propagation ◽

Dynamic Modeling ◽

Computational Fluid Dynamic ◽

Fluid Dynamic ◽

Human Subjects ◽

Left Ventricular ◽

Left Ventricular Thrombus ◽

Echocardiographic Parameter ◽

Ventricular Thrombus ◽

Computational Fluid Dynamic Modeling

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PHASED MULTI-JOINT MOVEMENT OF THE INDEX FINGER DURING A FULL FLEXION CYCLE

Biomedical Engineering Applications Basis and Communications ◽

10.4015/s1016237208000921 ◽

2008 ◽

Vol 20 (05) ◽

pp. 303-312

Author(s):

Wensheng Hou ◽

Xiaoying Wu ◽

Yingtao Jiang ◽

Jun Zheng ◽

Xiaolin Zheng ◽

...

Keyword(s):

Angular Velocity ◽

High Speed ◽

Index Finger ◽

Human Subjects ◽

Joint Motion ◽

Joint Movement ◽

General Belief ◽

Angular Velocities ◽

Full Flexion ◽

Five Phases

Flexion of the index finger is a fairly complex process requiring the coordination of different joints. This study is the first attempt to investigate how the angular velocity profile of the three right index joints (DIP, PIP, and MCP) varies with respect to time during the course of flexion. Ten right-handed subjects (healthy college students between 21 and 23 years old) were recruited to participate in the experiment. Each of these human subjects was instructed to perform a flexion task with his/her right hand. Five miniaturized (5-mm diameter) reflective markers were applied to each human subject: three placed at the DIP, PIP, and MCP joints of the index finger on the side close to thumb, and the rest at the predetermined landmarks on dorsum of thumb. A high-speed camera was used to record the motion of the index finger during a paced flexion, and the instantaneous angular velocity of each joint was determined by relating the marker displacement to the frame frequency (~5 ms between two consecutive frames). Opposite to the general belief that the speed is constant throughout a flexion cycle, to our best knowledge, this study, for the first time, has revealed that the speed of multi-joint movement actually varies with time. It has been identified that during one full flexion cycle, the angular velocity of the three joints of interest undergoes five distinguishable phases, referred as phases P1 (slow), P2 (fast), P3 (slow), P4 (fast), and P5 (slow), respectively. It has also been observed that duration of each of phases P1, P2, P4, or P5 accounts for approximately 10–15% of the whole flexion cycle, while P3 lasts for nearly half a cycle. Furthermore, although the flexions of DIP, PIP, and MCP joints cycle through the same five phases, the starts of their respective phases tend to vary. In P2 and P5, flexion of MCP takes place considerably later than those of PIP and DIP, whereas DIP flexes earlier than PIP in P2. The angular velocity of each joint reaches its peaks in P2 and P4; the peak velocity of DIP occurs earlier than that of PIP or MCP in P2, whereas peak of MCP is reached later than that of PIP. Moreover, the three joints of index finger flex with different angular velocities in each of the five phases: PIP moves significantly faster than MCP in P2, whereas DIP moves faster than MCP in P4. The results from our study indicate that the multi-joint motion of index finger is an uneven course, i.e. different joints flex with different angular velocities during the flexion. The temporal features of the velocity due to a single joint or multi-joint motion provide useful information to further clarify the dexterity of finger movement.

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