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Schmeling D, Shishkin A, Schiepel D, Wagner C. Numerical and experimental study of aerosol dispersion in the Do728 aircraft cabin. CEAS AERONAUTICAL JOURNAL 2023; 14:509-526. [PMID: 36819984 PMCID: PMC9930724 DOI: 10.1007/s13272-023-00644-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 12/20/2022] [Accepted: 01/18/2023] [Indexed: 05/24/2023]
Abstract
The dispersion of aerosols originating from one source, the 'index' passenger, within the cabin of the aircraft Do728 is studied experimentally using an aerosol-exhaling thermal manikin and in Reynolds-averaged Navier-Stokes simulations (RANS). The overall aim of the present study is the experimental determination of the aerosol spreading for the state-of-the-art mixing ventilation (MV) and to evaluate the potential of alternative ventilation concepts for controlling the aerosol spreading in RANS. For MV, the experiments showed that the ratio of inhaled to exhaled aerosol particles drops below 0.06% (volume ratio) for distances larger than two seat rows from the source. However, within a single row, the observed ratio is higher. Further, the dispersion is much weaker for a standing than for a seated index passenger. High air exchange rates and a well-guided flow prevent a dispersion of the aerosols in high concentrations over larger distances. Additionally, the positive effect of a mask and an increased air flow rate, and especially their combination are shown. In the complementary conducted RANS, the advantages of floor-based cabin displacement ventilation (CDV) which is alternative ventilation concept to MV, regarding spreading lengths and the dwell time of the aerosols in the cabin were determined. The obtained results also underline the importance of the flow field for the aerosol dispersion. Further, additional unsteady RANS (URANS) simulations of the short-term process of the initial aerosol cloud formation highlighted that the momentum decay of the breathing and the evaporation processes take place within a few seconds only. Supplementary Information The online version contains supplementary material available at 10.1007/s13272-023-00644-3.
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Affiliation(s)
- D. Schmeling
- German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Bunsenstr. 10, 37073 Göttingen, Germany
| | - A. Shishkin
- German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Bunsenstr. 10, 37073 Göttingen, Germany
| | - D. Schiepel
- German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Bunsenstr. 10, 37073 Göttingen, Germany
| | - C. Wagner
- German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Bunsenstr. 10, 37073 Göttingen, Germany
- Institute of Thermodynamics and Fluid Mechanics, Technische Universität Ilmenau, Am Helmholtzring 1, 98683 Ilmenau, Germany
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Nishal M, Ram Prasad K, Salman Dasthageer M, Ragunath A. Significance of additive manufacturing amidst the pandemic. MATERIALS TODAY. PROCEEDINGS 2023; 72:2540-2546. [PMID: 36267469 PMCID: PMC9556958 DOI: 10.1016/j.matpr.2022.09.571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In the light of COVID-19 pandemic, a global shortage for Personnel Protective Equipment (PPE) led to the search for an alternative to fill the gap where additive manufacturing made necessary development of rapid design and adaptive filtering masks for local manufacturing using 3D printing to help the frontline workers. The review focuses on the utilization of antimicrobial materials in additive manufacturing with the use of bespoke design to facilitate and respond to the disruptions in the medical supply chain. Previous studies confirmed the age-old theory of copper as an antimicrobial material with contact killing properties. The antimicrobial properties of copper have been registered at the U.S. Environmental Protection Agency as the first solid antimicrobial material. Combining the properties of copper in a PLA (Polylactic Acid) filament as a nano composite, Copper-3D facilitates the antimicrobial properties to any 3D printed object. Provided this flexibility of 3D printing, the use of masks designed distinctively based on the 3D scan of an individual's facial structures as an efficient Personnel Protective Equipment is also addressed. Additive manufacturing as a support to the shortage of medical devices and a responsive method to the disruption in the supply chain is discussed.
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Affiliation(s)
- M. Nishal
- Department of mechanical engineering, Sri Venkateswara College of Engineering, Sriperumbudur Tk-602117, Tamil Nadu, India
| | - K. Ram Prasad
- Department of mechanical engineering, Sri Venkateswara College of Engineering, Sriperumbudur Tk-602117, Tamil Nadu, India
| | - M. Salman Dasthageer
- Department of mechanical engineering, Sri Venkateswara College of Engineering, Sriperumbudur Tk-602117, Tamil Nadu, India,Corresponding author
| | - A.G. Ragunath
- KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden
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3
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Huang W, Wang K, Hung CT, Chow KM, Tsang D, Lai RWM, Xu RH, Yeoh EK, Ho KF, Chen C. Evaluation of SARS-CoV-2 transmission in COVID-19 isolation wards: On-site sampling and numerical analysis. JOURNAL OF HAZARDOUS MATERIALS 2022; 436:129152. [PMID: 35739698 PMCID: PMC9106403 DOI: 10.1016/j.jhazmat.2022.129152] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/06/2022] [Accepted: 05/11/2022] [Indexed: 05/29/2023]
Abstract
Although airborne transmission has been considered as a possible route for the spread of SARS-CoV-2, the role that aerosols play in SARS-CoV-2 transmission is still controversial. This study evaluated the airborne transmission of SARS-CoV-2 in COVID-19 isolation wards at Prince of Wales Hospital in Hong Kong by both on-site sampling and numerical analysis. A total of 838 air samples and 1176 surface samples were collected, and SARS-CoV-2 RNA was detected using the RT-PCR method. Testing revealed that 2.3% of the air samples and 9.3% of the surface samples were positive, indicating that the isolation wards were contaminated with the virus. The dispersion and deposition of exhaled particles in the wards were calculated by computational fluid dynamics (CFD) simulations. The calculated accumulated number of particles collected at the air sampling points was closely correlated with the SARS-CoV-2 positive rates from the field sampling, which confirmed the possibility of airborne transmission. Furthermore, three potential intervention strategies, i.e., the use of curtains, ceiling-mounted air cleaners, and periodic ventilation, were numerically investigated to explore effective control measures in isolation wards. According to the results, the use of ceiling-mounted air cleaners is effective in reducing the airborne transmission of SARS-CoV-2 in such wards.
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Affiliation(s)
- Wenjie Huang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Kailu Wang
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Centre for Health Systems and Policy Research, JCSPHPC, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Chi-Tim Hung
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Centre for Health Systems and Policy Research, JCSPHPC, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Kai-Ming Chow
- Department of Medicine and Therapeutics, Prince of Wales Hospital, Shatin, N.T. 999077, Hong Kong, China
| | - Dominic Tsang
- Public Health Laboratory Centre, Centre for Health Protection, Kowloon 999077, Hong Kong, China
| | - Raymond Wai-Man Lai
- Department of Microbiology, Prince of Wales Hospital, Shatin, N.T. 999077, Hong Kong, China
| | - Richard Huan Xu
- Department of Rehabilitation Science, Faculty of Health and Social Science, The Hong Kong Polytechnic University, Kowloon 999077, Hong Kong, China
| | - Eng-Kiong Yeoh
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Centre for Health Systems and Policy Research, JCSPHPC, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China
| | - Kin-Fai Ho
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China.
| | - Chun Chen
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T. 999077, Hong Kong, China; Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen 518057, China.
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Luo Q, Ou C, Hang J, Luo Z, Yang H, Yang X, Zhang X, Li Y, Fan X. Role of pathogen-laden expiratory droplet dispersion and natural ventilation explaining a COVID-19 outbreak in a coach bus. BUILDING AND ENVIRONMENT 2022; 220:109160. [PMID: 35615259 PMCID: PMC9122785 DOI: 10.1016/j.buildenv.2022.109160] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/28/2022] [Accepted: 04/30/2022] [Indexed: 05/30/2023]
Abstract
The influencing mechanism of droplet transmissions inside crowded and poorly ventilated buses on infection risks of respiratory diseases is still unclear. Based on experiments of one-infecting-seven COVID-19 outbreak with an index patient at bus rear, we conducted CFD simulations to investigate integrated effects of initial droplet diameters(tracer gas, 5 μm, 50 μm and 100 μm), natural air change rates per hour(ACH = 0.62, 2.27 and 5.66 h-1 related to bus speeds) and relative humidity(RH = 35% and 95%) on pathogen-laden droplet dispersion and infection risks. Outdoor pressure difference around bus surfaces introduces natural ventilation airflow entering from bus-rear skylight and leaving from the front one. When ACH = 0.62 h-1(idling state), the 30-min-exposure infection risk(TIR) of tracer gas is 15.3%(bus rear) - 11.1%(bus front), and decreases to 3.1%(bus rear)-1.3%(bus front) under ACH = 5.66 h-1(high bus speed).The TIR of large droplets(i.e., 100 μm/50 μm) is almost independent of ACH, with a peak value(∼3.1%) near the index patient, because over 99.5%/97.0% of droplets deposit locally due to gravity. Moreover, 5 μm droplets can disperse further with the increasing ventilation. However, TIR for 5 μm droplets at ACH = 5.66 h-1 stays relatively small for rear passengers(maximum 0.4%), and is even smaller in the bus middle and front(<0.1%). This study verifies that differing from general rooms, most 5 μm droplets deposit on the route through the long-and-narrow bus space with large-area surfaces(L∼11.4 m). Therefore, tracer gas can only simulate fine droplet with little deposition but cannot replace 5-100 μm droplet dispersion in coach buses.
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Affiliation(s)
- Qiqi Luo
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Cuiyun Ou
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Jian Hang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Zhiwen Luo
- School of the Built Environment, University of Reading, Reading, UK
| | - Hongyu Yang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Xia Yang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Xuelin Zhang
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
| | - Yuguo Li
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Xiaodan Fan
- School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China
- Key Laboratory of Tropical Atmosphere-Ocean System (Sun Yat-sen University), Ministry of Education, Zhuhai, 519000, China
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Mohamadi F, Fazeli A. A Review on Applications of CFD Modeling in COVID-19 Pandemic. ARCHIVES OF COMPUTATIONAL METHODS IN ENGINEERING : STATE OF THE ART REVIEWS 2022; 29:3567-3586. [PMID: 35079217 PMCID: PMC8773396 DOI: 10.1007/s11831-021-09706-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 12/28/2021] [Indexed: 05/25/2023]
Abstract
COVID-19 pandemic has started a big challenge to the world health and economy during recent years. Many efforts were made to use the computation fluid dynamic (CFD) approach in this pandemic. CFD was used to understanding the airborne dispersion and transmission of this virus in different situations and buildings. The effect of the different conditions of the ventilation was studied by the CFD modeling to discuss preventing the COVID-19 transmission. Social distancing and using the facial masks were also modeled by the CFD approach to study the effect on reducing dispersion of the microdroplets containing the virus. Most of these recent applications of the CFD were reviewed for COVID-19 in this article. Special applications of the CFD modeling such as COVID-19 microfluidic biosensors, and COVID-19 inactivation using UV radiation were also reviewed in this research. The main findings of each research were also summarized in a table to answer critical questions about the effectiveness levels of applying the COVID-19 health protocols. CFD applications for modeling of COVID-19 dispersion in an airplane cabin, an elevator, a small classroom, a supermarket, an operating room of a hospital, a restaurant, a hospital waiting room, and a children's recovery room in a hospital were discussed briefly in different scenarios. CFD modeling for studying the effect of social distancing with different spaces, using and not using facial masks, difference of sneezing and coughing, different inlet/outlet ventilation layouts, combining air-conditioning and sanitizing machine, and using general or local air-conditioning systems were reviewed.
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Affiliation(s)
- Fateme Mohamadi
- Department of Chemical Engineering, Caspian Faculty of Engineering, College of Engineering, University of Tehran, Tehran, Iran
| | - Ali Fazeli
- Department of Chemical Engineering, Caspian Faculty of Engineering, College of Engineering, University of Tehran, Tehran, Iran
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Wang W, Wang F, Lai D, Chen Q. Evaluation of SARS-COV-2 transmission and infection in airliner cabins. INDOOR AIR 2022; 32:e12979. [PMID: 35048429 DOI: 10.1111/ina.12979] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/30/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
Commercial airliners have played an important role in spreading the SARS-CoV-2 virus worldwide. This study used computational fluid dynamics (CFD) to simulate the transmission of SARS-CoV-2 on a flight from London to Hanoi and another from Singapore to Hangzhou. The dispersion of droplets of different sizes generated by coughing, talking, and breathing activities in a cabin by an infected person was simulated by means of the Lagrangian method. The SARS-CoV-2 virus contained in expiratory droplets traveled with the cabin air distribution and was inhaled by other passengers. Infection was determined by counting the number of viral copies inhaled by each passenger. According to the results, our method correctly predicted 84% of the infected/uninfected cases on the first flight. The results also show that wearing masks and reducing conversation frequency between passengers could help to reduce the risk of exposure on the second flight.
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Affiliation(s)
- Wensi Wang
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Feng Wang
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Dayi Lai
- Department of Architecture, Shanghai Jiao Tong University, Shanghai, China
| | - Qingyan Chen
- Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong
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7
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Löhner R, Antil H, Srinivasan A, Idelsohn S, Oñate E. High-Fidelity Simulation of Pathogen Propagation, Transmission and Mitigation in the Built Environment. ARCHIVES OF COMPUTATIONAL METHODS IN ENGINEERING : STATE OF THE ART REVIEWS 2021; 28:4237-4262. [PMID: 34248352 PMCID: PMC8256653 DOI: 10.1007/s11831-021-09606-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 05/08/2021] [Indexed: 05/31/2023]
Abstract
An overview of high-fidelity modeling of pathogen propagation, transmission and mitigation in the built environment is given. In order to derive the required physical and numerical models, the current understanding of pathogen, and in particular virus transmission and mitigation is summarized. The ordinary and partial differential equations that describe the flow, the particles and possibly the UV radiation loads in rooms or HVAC ducts are presented, as well as proper numerical methods to solve them in an expedient way. Thereafter, the motion of pedestrians, as well as proper ways to couple computational fluid dynamics and computational crowd dynamics to enable high-fidelity pathogen transmission and infection simulations is treated. The present review shows that high-fidelity simulations of pathogen propagation, transmission and mitigation in the built environment have reached a high degree of sophistication, offering a quantum leap in accuracy from simpler probabilistic models. This is particularly the case when considering the propagation of pathogens via aerosols in the presence of moving pedestrians.
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Affiliation(s)
- Rainald Löhner
- Center for Computational Fluid Dynamics, College of Science, George Mason University, Fairfax, VA 22030-4444 USA
| | - Harbir Antil
- Center for Mathematics and Artificial Intelligence, College of Science, George Mason University, Fairfax, VA 22030-4444 USA
| | - Ashok Srinivasan
- Department of Computer Science, University of West Florida, Pensacola, FL 32514 USA
| | - Sergio Idelsohn
- Catalan Institution for Research and Advanced Studies, ICREA, Barcelona, Spain
- International Center for Numerical Methods in Engineering, CIMNE, Barcelona, Spain
| | - Eugenio Oñate
- International Center for Numerical Methods in Engineering, CIMNE, Barcelona, Spain
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Planning and Design of a Full-Outer-Air-Intake Natural Air-Conditioning System for Medical Negative Pressure Isolation Wards. JOURNAL OF HEALTHCARE ENGINEERING 2021; 2021:8872167. [PMID: 33833861 PMCID: PMC8018840 DOI: 10.1155/2021/8872167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 02/13/2021] [Accepted: 03/17/2021] [Indexed: 11/20/2022]
Abstract
In the beginning of 2020, the coronavirus (COVID-19) pandemic started to spread globally, causing panic to the lives of people around the world; many countries executed lockdown of cities or even total lockdown of the entire countries. The coronavirus disease (COVID-19) is transmitted via air droplets. In medical environments that use traditional hermetic ventilation systems, medical personnel who come in contact with patients are more susceptible to infection compared to regular staff; therefore, the air flow and air quality of hermetic negative pressure isolation wards are highly critical. For this purpose, the study proposes a full-outer-air-intake natural air-conditioning system for negative pressure isolation wards. This innovative system draws in large amounts of fresh external air to greatly improve the air exchange rate in wards; negative pressure environments can be implemented depending on requirements to solve the issue of nosocomial infections in traditional negative pressure isolation wards that draw air from within the hospital. This greatly reduces the probability of nosocomial infection and infection via air droplets; furthermore, the system's intake and exhaust paths are completely isolated, solving the issue of air cross-contamination. Based on the results from the experiment site, this innovative system was designed and implemented based on the guidelines of hospital facilities and achieved air exchange per hour in excess of 12 times/hour, reaching a maximum of 54.5 times/hour. Indoor CO2 concentration was 576 ppm, negative pressure was −14 Pa, indoor temperature was 23.3°C, indoor humidity was 54.1%, and sensible heat exchange efficiency (ηs) was 105.88% which effectively reduced ventilation load. Therefore, this innovative full-outer-air-intake natural air-conditioning system can provide medical staff and patients with a safe and healthy environment that prevents cross-infection.
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Löhner R, Antil H, Idelsohn S, Oñate E. Detailed simulation of viral propagation in the built environment. COMPUTATIONAL MECHANICS 2020; 66:1093-1107. [PMID: 32836601 PMCID: PMC7403197 DOI: 10.1007/s00466-020-01881-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 05/20/2023]
Abstract
A summary is given of the mechanical characteristics of virus contaminants and the transmission via droplets and aerosols. The ordinary and partial differential equations describing the physics of these processes with high fidelity are presented, as well as appropriate numerical schemes to solve them. Several examples taken from recent evaluations of the built environment are shown, as well as the optimal placement of sensors.
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Affiliation(s)
- Rainald Löhner
- Center for Computational Fluid Dynamics, College of Science, George Mason University, Fairfax, VA 22030-4444 USA
| | - Harbir Antil
- Center for Mathematics and Artificial Intelligence, College of Science, George Mason University, Fairfax, VA 22030-4444 USA
| | - Sergio Idelsohn
- ICREA, Catalan Institution for Research and Advanced Studies, Barcelona, Spain
- CIMNE, International Center for Numerical Methods in Engineering, Barcelona, Spain
| | - Eugenio Oñate
- CIMNE, International Center for Numerical Methods in Engineering, Barcelona, Spain
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Liu W, You R, Chen C. Modeling transient particle transport by fast fluid dynamics with the Markov chain method. BUILDING SIMULATION 2019; 12:881-889. [PMID: 32218906 PMCID: PMC7090511 DOI: 10.1007/s12273-019-0513-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 12/18/2018] [Accepted: 12/25/2018] [Indexed: 05/05/2023]
Abstract
Fast simulation tools for the prediction of transient particle transport are critical in designing the air distribution indoors to reduce the exposure to indoor particles and associated health risks. This investigation proposed a combined fast fluid dynamics (FFD) and Markov chain model for fast predicting transient particle transport indoors. The solver for FFD-Markov-chain model was programmed in OpenFOAM, an open-source CFD toolbox. This study used two cases from the literature to validate the developed model and found well agreement between the transient particle concentrations predicted by the FFD-Markov-chain model and the experimental data. This investigation further compared the FFD-Markov-chain model with the CFD-Eulerian model and CFD-Lagrangian model in terms of accuracy and efficiency. The accuracy of the FFD-Markov-chain model was similar to that of the other two models. For the two studied cases, the FFD-Markovchain model was 4.7 and 6.8 times faster, respectively, than the CFD-Eulerian model, and it was 137.4 and 53.3 times faster than the CFD-Lagrangian model in predicting the steady-state airflow and transient particle transport. Therefore, the FFD-Markov-chain model is able to greatly reduce the computing cost for predicting transient particle transport in indoor environments.
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Affiliation(s)
- Wei Liu
- School of Civil Engineering, ZJU-UIUC, Zhejiang University, Haining, 314400 China
- Division of Fluid and Climate Technology, Department of Civil and Architectural Engineering, KTH Royal Institute of Technology, Brinellvägen 23, Stockholm, 100 44 Sweden
| | - Ruoyu You
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, 999077, Hong Kong China
| | - Chun Chen
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, N.T., 999077, Hong Kong China
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, 518057 China
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11
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Yang L, Li X, Yan Y, Tu J. Effects of cough-jet on airflow and contaminant transport in an airliner cabin section. ACTA ACUST UNITED AC 2017. [DOI: 10.1177/1757482x17746920] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The goals of this study were to investigate the effect of cough-jet on local airflow and contaminant transport in a typical cabin environment by using computational fluid dynamics. A fully occupied airliner cabin section was employed as the computational domain. Contaminants were released through coughing passengers from different locations inside the cabin. Numerical results in terms of contaminant transport characteristics were examined and compared. It can be concluded that cough-jet has significant effects on air flow in front of cough passenger in a short period of time. Also, it was found that, without considering the cough-jet model, the simulation results could not be a precise representation of the transport and distribution of cough-generated airborne contaminants.
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Affiliation(s)
- Lin Yang
- School of Engineering, RMIT University, Bundoora, Australia
| | - Xiangdong Li
- School of Engineering, RMIT University, Bundoora, Australia
| | - Yihuan Yan
- School of Engineering, RMIT University, Bundoora, Australia
| | - Jiyuan Tu
- School of Engineering, RMIT University, Bundoora, Australia
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12
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Chen C, Liu W, Lin CH, Chen Q. A Markov chain model for predicting transient particle transport in enclosed environments. BUILDING AND ENVIRONMENT 2015; 90:30-36. [PMID: 32288030 PMCID: PMC7117050 DOI: 10.1016/j.buildenv.2015.03.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/09/2015] [Accepted: 03/14/2015] [Indexed: 05/05/2023]
Abstract
Obtaining information about particle dispersion in a room is crucial in reducing the risk of infectious disease transmission among occupants. This study developed a Markov chain model for quickly obtaining the information on the basis of a steady-state flow field calculated by computational fluid dynamics. When solving the particle transport equations, the Markov chain model does not require iterations in each time step, and thus it can significantly reduce the computing cost. This study used two sets of experimental data for transient particle transport to validate the model. In general, the trends in the particle concentration distributions predicted by the Markov chain model agreed reasonably well with the experimental data. This investigation also applied the model to the calculation of person-to-person particle transport in a ventilated room. The Markov chain model produced similar results to those of the Lagrangian and Eulerian models, while the speed of calculation increased by 8.0 and 6.3 times, respectively, in comparison to the latter two models.
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Affiliation(s)
- Chun Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Wei Liu
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Chao-Hsin Lin
- Environmental Control Systems, Boeing Commercial Airplanes, Everett, WA, 98203, USA
| | - Qingyan Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Tianjin Key Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
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13
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Tang JW, Wilson P, Shetty N, Noakes CJ. Aerosol-Transmitted Infections-a New Consideration for Public Health and Infection Control Teams. CURRENT TREATMENT OPTIONS IN INFECTIOUS DISEASES 2015; 7:176-201. [PMID: 32226323 PMCID: PMC7100085 DOI: 10.1007/s40506-015-0057-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Since the emergence of the 2003 severe acute respiratory syndrome (SARS), the 2003 reemergence of avian A/H5N1, the emergence of the 2009 pandemic influenza A/H1N1, the 2012 emergence of Middle East respiratory syndrome (MERS), the 2013 emergence of avian A/H7N9 and the 2014 Ebola virus outbreaks, the potential for the aerosol transmission of infectious agents is now routinely considered in the investigation of any outbreak. Although many organisms have traditionally been considered to be transmitted by only one route (e.g. direct/indirect contact and/or faecal-orally), it is now apparent that the aerosol transmission route is also possible and opportunistic, depending on any potentially aerosol-generating procedures, the severity of illness and the degree and duration of pathogen-shedding in the infected patient, as well as the environment in which these activities are conducted.This article reviews the evidence and characteristics of some of the accepted (tuberculosis, measles, chickenpox, whooping cough) and some of the more opportunistic (influenza, Clostridium difficile, norovirus) aerosol-transmitted infectious agents and outlines methods of detecting and quantifying transmission.
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Affiliation(s)
- Julian W. Tang
- Clinical Microbiology, Leicester Royal Infirmary, University Hospitals Leicester, Leicester NHS Trust, Leicester, LE1 5WW UK
| | - Peter Wilson
- Clinical Microbiology, University College London Hospitals NHS Trust, London, UK
| | - Nandini Shetty
- Clinical Microbiology, University College London Hospitals NHS Trust, London, UK
| | - Catherine J. Noakes
- Institute for Public Health and Environmental Engineering, School of Civil Engineering, University of Leeds, Leeds, UK
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14
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Revisiting a two-patch SIS model with infection during transport. MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA 2015; 33:29-55. [DOI: 10.1093/imammb/dqv001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 01/01/2015] [Indexed: 11/14/2022]
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15
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Guan Y(D, Ramesh A, Memarzadeh F. The Effects of Patient Movement on Particles Dispersed by Coughing in an Indoor Environment. APPLIED BIOSAFETY 2014. [DOI: 10.1177/153567601401900401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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16
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Hoad VC, O'Connor BA, Langley AJ, Dowse GK. Risk of measles transmission on aeroplanes: Australian experience 2007-2011. Med J Aust 2013; 198:320-3. [PMID: 23545030 DOI: 10.5694/mja12.11752] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 02/14/2013] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To quantify the risk of transmission of measles associated with infectious people who travelled on aeroplane flights to or within Australia. DESIGN, SETTING AND SUBJECTS Data were obtained from state and territory health authorities on all measles notifications from January 2007 to June 2011 for people who were likely to have been infectious or infected while travelling on aeroplanes in Australia. RESULTS Forty-five infectious people travelled on aeroplanes. Twenty secondary infections occurred in people on seven of 49 flights (14%; 95% CI, 6%-29%), comprising 19% (95% CI, 8%-40%) of the 36 international flights and none of 13 (95% CI, 0-28%) domestic flights that carried infectious people. Secondary infections occurred in nine people who were seated within two rows of the index case and in 11 people who were seated outside of two rows. Secondary transmission was more likely to occur with younger index cases (P = 0.025) and when there were multiple infectious people travelling (P = 0.018). About a third(15/49) of flight manifests were available to health authorities within 5 days oftravel. CONCLUSION Despite secondary measles transmission occurring on 19% of international flights carrying infectious people, risk was not clearly related to seating proximity, and contact tracing was ineffective, especially given delays in diagnosis, notification and accessing flight manifests. We recommend that direct contact tracing to identify susceptible people exposed to people infected with measles on aeroplane flights should not be undertaken routinely, and other strategies should be considered.
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Affiliation(s)
- Veronica C Hoad
- Public Health and Ambulatory Care, North Metropolitan Health Service, Perth, WA, Australia.
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Chen C, Liu W, Li F, Lin CH, Liu J, Pei J, Chen Q. A hybrid model for investigating transient particle transport in enclosed environments. BUILDING AND ENVIRONMENT 2013; 62:45-54. [PMID: 32288023 PMCID: PMC7126580 DOI: 10.1016/j.buildenv.2012.12.020] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 12/12/2012] [Accepted: 12/31/2012] [Indexed: 05/04/2023]
Abstract
It is important to accurately model person-to-person particle transport in mechanical ventilation spaces to create and maintain a healthy indoor environment. The present study introduces a hybrid DES-Lagrangian and RANS-Eulerian model for simulating transient particle transport in enclosed environments; this hybrid model can ensure the accuracy and reduce the computing cost. Our study estimated two key time constants for the model that are important parameters for reducing the computing costs. The two time constants estimated were verified by airflow data from both an office and an aircraft cabin case. This study also conducted experiments in the first-class cabin of an MD-82 commercial airliner with heated manikins to validate the hybrid model. A pulse particle source was applied at the mouth of an index manikin to simulate a cough. The particle concentrations versus time were measured at the breathing zone of the other manikins. The trend of particle concentrations versus time predicted by the hybrid model agrees with the experimental data. Therefore, the proposed hybrid model can be used for investigating transient particle transport in enclosed environments.
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Affiliation(s)
- Chun Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Wei Liu
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Naikai District, Tianjin 300072, China
| | - Fei Li
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Naikai District, Tianjin 300072, China
| | - Chao-Hsin Lin
- Environmental Control Systems, Boeing Commercial Airplanes, Everett, WA 98203, USA
| | - Junjie Liu
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Naikai District, Tianjin 300072, China
| | - Jingjing Pei
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Naikai District, Tianjin 300072, China
- Corresponding author. Tel.: +86 22 27403416; fax: +86 22 27401561.
| | - Qingyan Chen
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
- School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Naikai District, Tianjin 300072, China
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Tang JW, Nicolle AD, Klettner CA, Pantelic J, Wang L, Suhaimi AB, Tan AYL, Ong GWX, Su R, Sekhar C, Cheong DDW, Tham KW. Airflow dynamics of human jets: sneezing and breathing - potential sources of infectious aerosols. PLoS One 2013; 8:e59970. [PMID: 23560060 PMCID: PMC3613375 DOI: 10.1371/journal.pone.0059970] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Accepted: 02/19/2013] [Indexed: 11/18/2022] Open
Abstract
Natural human exhalation flows such as coughing, sneezing and breathing can be considered as 'jet-like' airflows in the sense that they are produced from a single source in a single exhalation effort, with a relatively symmetrical, conical geometry. Although coughing and sneezing have garnered much attention as potential, explosive sources of infectious aerosols, these are relatively rare events during daily life, whereas breathing is necessary for life and is performed continuously. Real-time shadowgraph imaging was used to visualise and capture high-speed images of healthy volunteers sneezing and breathing (through the nose - nasally, and through the mouth - orally). Six volunteers, who were able to respond to the pepper sneeze stimulus, were recruited for the sneezing experiments (2 women: 27.5±6.36 years; 4 men: 29.25±10.53 years). The maximum visible distance over which the sneeze plumes (or puffs) travelled was 0.6 m, the maximum sneeze velocity derived from these measured distances was 4.5 m/s. The maximum 2-dimensional (2-D) area of dissemination of these sneezes was 0.2 m(2). The corresponding derived parameter, the maximum 2-D area expansion rate of these sneezes was 2 m(2)/s. For nasal breathing, the maximum propagation distance and derived velocity were 0.6 m and 1.4 m/s, respectively. The maximum 2-D area of dissemination and derived expansion rate were 0.11 m(2) and 0.16 m(2)/s, respectively. Similarly, for mouth breathing, the maximum propagation distance and derived velocity were 0.8 m and 1.3 m/s, respectively. The maximum 2-D area of dissemination and derived expansion rate were 0.18 m(2) and 0.17 m(2)/s, respectively. Surprisingly, a comparison of the maximum exit velocities of sneezing reported here with those obtained from coughing (published previously) demonstrated that they are relatively similar, and not extremely high. This is in contrast with some earlier estimates of sneeze velocities, and some reasons for this difference are discussed.
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Affiliation(s)
- Julian W Tang
- Alberta Provincial Laboratory for Public Health, University of Alberta Hospital, Edmonton, Canada.
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Measles transmission during air travel, United States, December 1, 2008–December 31, 2011. Travel Med Infect Dis 2013; 11:81-9. [DOI: 10.1016/j.tmaid.2013.03.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/06/2013] [Indexed: 11/22/2022]
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20
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Zhang L, Peng Z, Ou J, Zeng G, Fontaine RE, Liu M, Cui F, Hong R, Zhou H, Huai Y, Chuang SK, Leung YH, Feng Y, Luo Y, Shen T, Zhu BP, Widdowson MA, Yu H. Protection by face masks against influenza A(H1N1)pdm09 virus on trans-Pacific passenger aircraft, 2009. Emerg Infect Dis 2013; 19. [PMID: 23968983 PMCID: PMC3810906 DOI: 10.3201/eid1909.121765] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
In response to several influenza A(H1N1)pdm09 infections that developed in passengers after they traveled on the same 2 flights from New York, New York, USA, to Hong Kong, China, to Fuzhou, China, we assessed transmission of influenza A(H1N1)pdm09 virus on these flights. We defined a case of infection as onset of fever and respiratory symptoms and detection of virus by PCR in a passenger or crew member of either flight. Illness developed only in passengers who traveled on the New York to Hong Kong flight. We compared exposures of 9 case-passengers with those of 32 asymptomatic control-passengers. None of the 9 case-passengers, compared with 47% (15/32) of control-passengers, wore a face mask for the entire flight (odds ratio 0, 95% CI 0-0.71). The source case-passenger was not identified. Wearing a face mask was a protective factor against influenza infection. We recommend a more comprehensive intervention study to accurately estimate this effect.
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Affiliation(s)
- Lijie Zhang
- Chinese Center for Disease Control and Prevention, Beijing, China
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Gupta JK, Lin CH, Chen Q. Risk assessment of airborne infectious diseases in aircraft cabins. INDOOR AIR 2012; 22:388-95. [PMID: 22313168 DOI: 10.1111/j.1600-0668.2012.00773.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
UNLABELLED Passengers in an aircraft cabin can have different risks of infection from airborne infectious diseases such as influenza, severe acute respiratory syndrome (SARS), and tuberculosis (TB) because of the non-uniform airflow in an aircraft cabin. The current investigation presents a comprehensive approach to assessing the spatial and temporal distributions of airborne infection risk in an aircraft cabin. A case of influenza outbreak was evaluated in a 4-h flight in a twin-aisle, fully occupied aircraft cabin with the index passenger seated at the center of the cabin. The approach considered the characteristics of the exhalation of the droplets carrying infectious agents from the index passenger, the dispersion of these droplets, and the inhalation of the droplets by susceptible passengers. Deterministic and probabilistic approaches were used to quantify the risks based on the amount of inhaled influenza virus RNA particles and quanta, respectively. The probabilistic approach indicated that the number of secondary infection cases can be reduced from 3 to 0 and 20 to 11, for influenza cases if N95 respirator masks are used by the passengers. The approach and methods developed can easily be implemented in other enclosed spaces such as buildings, trains, and buses to assess the infection risk. PRACTICAL IMPLICATIONS Airborne infectious disease transmission could take place in enclosed environments such as buildings and transport vehicles. The infection risk is difficult to estimate, and very few mitigation methods are available. This study used a 4-h flight as an example in analyzing the infection risk from influenza and in mitigating the risk with an N95 mask. The results will be useful to the airline industry in providing necessary protection to passengers and crew, and the results can also be used for other enclosed spaces.
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Affiliation(s)
- Jitendra K Gupta
- National Air Transportation Center of Excellence for Research in the Intermodal Transport Environment-RITE, School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA
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Edelson PJ. Patterns of measles transmission among airplane travelers. Travel Med Infect Dis 2012; 10:230-5. [DOI: 10.1016/j.tmaid.2012.10.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 10/10/2012] [Accepted: 10/11/2012] [Indexed: 11/25/2022]
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