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Wang Z, Zhang Z, Yu J, Zhai Z. The effect of flexible obstacles with different thicknesses on explosion propagation of premixed methane-air in a confined duct. Heliyon 2023; 9:e18803. [PMID: 37609431 PMCID: PMC10440448 DOI: 10.1016/j.heliyon.2023.e18803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 07/25/2023] [Accepted: 07/28/2023] [Indexed: 08/24/2023] Open
Abstract
The effect of flexible obstacles with varying thicknesses on the explosion characteristics of combustible gas in a simulated confined duct (cross section 80 mm × 80 mm, length 3 m) was experimentally investigated, aiming to reduce the huge losses caused by gas explosion accidents in the process industries and mining industries. In this paper, plant fiber membranes with an opening area of 0 and thicknesses of 0.105 mm, 0.210 mm, 0.315 mm, 0.420 mm, 0.525 mm, and 0.630 mm were selected as flexible obstacles. The thickness of the flexible obstacle determines the strength of its compressive resistance. The characteristics of overpressure and flame during methane explosions are analyzed and conclusions are drawn. Results indicate that several shock wave reflection processes occur before the diaphragm ruptures, resulting in turbulent flames. In addition, the explosion wave generated numerous shock reflections during the rupture process of the diaphragm, which was gradually discharged downstream of the pipe by ejection as the pressure wave accumulated in front of the diaphragm. It should be noted that the thickness of the flexible obstacle determines the pressure accumulation in front of the membrane. Generally, the thinner the flexible obstacle, the less intense the turbulent flame is induced by the flexible obstacle, decreasing the contact area between the unignited gas downstream of the pipeline and the turbulent flame area. In conclusion, with an increase in the thickness of the flexible barrier, it exhibits a mechanism of initially suppressing and subsequently enhancing the impact on methane explosions. The increase of the thickness of the flexible obstacle motivates the flame propagation speed, which leads to an increase of turbulence intensity and explosion intensity.
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Affiliation(s)
- Zheshi Wang
- College of Environmental and Safety Engineering, Qingdao University of Science and Technology, Qingdao, 266000, China
| | - Zengliang Zhang
- College of Environmental and Safety Engineering, Qingdao University of Science and Technology, Qingdao, 266000, China
| | - Jia Yu
- College of Environmental and Safety Engineering, Qingdao University of Science and Technology, Qingdao, 266000, China
| | - Zhi Zhai
- College of Environmental and Safety Engineering, Qingdao University of Science and Technology, Qingdao, 266000, China
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Wicaksono AN, Abu-Mahfouz IS, Idiz E, Cartwright J, Santamarina JC, Vahrenkamp VC. Stress distribution around kerogen particles as a measure of the initiation of bitumen-filled microfractures in organic-rich source rocks. MethodsX 2022; 9:101817. [PMID: 36046736 PMCID: PMC9420931 DOI: 10.1016/j.mex.2022.101817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 08/05/2022] [Indexed: 11/25/2022] Open
Abstract
In this article, we present a method used to model the initiation of bitumen-filled microfractures in immature, organic-rich source rocks. The first part presents the method used to calculate the stress distribution around the kerogen particles. The second part explains the method used to calculate the pressure change as a function of the transformation ratio and the resulting overpressure.The effective principal stresses acting on the kerogen boundary were calculated. Kerogen geometries were determined using the measured aspect ratio of the kerogen traces obtained from the petrography observation. To estimate overpressure, the increase in pressure due to the transformation of kerogen to bitumen was calculated.
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Affiliation(s)
- Akbar N Wicaksono
- Ali I. Al-Naimi Petroleum Engineering Research Centre, King Abdullah University of Science & Technology (KAUST), Thuwal, 23955 Saudi Arabia
| | - Israa S Abu-Mahfouz
- Ali I. Al-Naimi Petroleum Engineering Research Centre, King Abdullah University of Science & Technology (KAUST), Thuwal, 23955 Saudi Arabia.,Department of Geosciences, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran 31261, Saudi Arabia
| | - Erdem Idiz
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - Joe Cartwright
- Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, UK
| | - J Carlos Santamarina
- Ali I. Al-Naimi Petroleum Engineering Research Centre, King Abdullah University of Science & Technology (KAUST), Thuwal, 23955 Saudi Arabia
| | - Volker C Vahrenkamp
- Ali I. Al-Naimi Petroleum Engineering Research Centre, King Abdullah University of Science & Technology (KAUST), Thuwal, 23955 Saudi Arabia
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Karunakaran CP, Burgess MT, Rao MB, Holland CK, Mast TD. Effect of Overpressure on Acoustic Emissions and Treated Tissue Histology in ex Vivo Bulk Ultrasound Ablation. Ultrasound Med Biol 2021; 47:2360-2376. [PMID: 34023187 PMCID: PMC8243850 DOI: 10.1016/j.ultrasmedbio.2021.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 04/08/2021] [Accepted: 04/11/2021] [Indexed: 06/12/2023]
Abstract
Bulk ultrasound ablation is a thermal therapy approach in which tissue is heated by unfocused or weakly focused sonication (average intensities on the order of 100 W/cm2) to achieve coagulative necrosis within a few minutes exposure time. Assessing the role of bubble activity, including acoustic cavitation and tissue vaporization, in bulk ultrasound ablation may help in making bulk ultrasound ablation safer and more effective for clinical applications. Here, two series of ex vivo ablation trials were conducted to investigate the role of bubble activity and tissue vaporization in bulk ultrasound ablation. Fresh bovine liver tissue was ablated with unfocused, continuous-wave ultrasound using ultrasound image-ablate arrays sonicating at 31 W/cm2 (0.9 MPa amplitude) for either 20 min at a frequency of 3.1 MHz or 10 min at 4.8 MHz. Tissue specimens were maintained at a static overpressure of either 0.52 or 1.2 MPa to suppress bubble activity and tissue vaporization or at atmospheric pressure for control groups. A passive cavitation detector was used to record subharmonic (1.55 or 2.4 MHz), broadband (1.2-1.5 MHz) and low-frequency (5-20 kHz) acoustic emissions. Treated tissue was stained with 2% triphenyl tetrazolium chloride to evaluate thermal lesion dimensions. Subharmonic emissions were significantly reduced in overpressure groups compared with control groups. Correlations observed between acoustic emissions and lesion dimensions were significant and positive for the 3.1-MHz series, but significant and negative for the 4.8-MHz series. The results indicate that for bulk ultrasound ablation, where both acoustic cavitation and tissue vaporization are possible, bubble activity can enhance ablation in the absence of tissue vaporization, but can reduce thermal lesion dimensions in the presence of vaporization.
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Affiliation(s)
| | - Mark T Burgess
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA
| | - Marepalli B Rao
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA; Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio, USA
| | - Christy K Holland
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA; Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, Ohio, USA
| | - T Douglas Mast
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, Ohio, USA; Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati, Cincinnati, Ohio, USA.
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Nazarious MI, Mathanlal T, Zorzano MP, Martin-Torres J. Pressure Optimized PowEred Respirator (PROPER): A miniaturized wearable cleanroom and biosafety system for aerially transmitted viral infections such as COVID-19. HardwareX 2020; 8:e00144. [PMID: 33043172 PMCID: PMC7536593 DOI: 10.1016/j.ohx.2020.e00144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 05/18/2023]
Abstract
The supply of Personal Protective Equipment (PPE) in hospitals to keep the Health Care Professionals (HCP) safe taking care of patients may be limited, especially during the outbreak of a new disease. In particular, the face and body protective equipment is critical to prevent the wearer from exposure to pathogenic biological airborne particulates. This situation has been now observed worldwide during the onset of the COVID-19 pandemic. As concern over shortages of PPE at hospitals grows, we share with the public and makers' community the Pressure Optimized PowEred Respirator (PROPER) equipment, made out of COTS components. It is functionally equivalent to a Powered Air Purifying Respirator (PAPR). PROPER, a hood-based system which uses open source and easily accessible components is low-cost, relatively passive in terms of energy consumption and mechanisms, and easy and fast to 3D print, build and assemble. We have adapted our experience on building clean room environments and qualifying the bioburden of space instruments to this solution, which is in essence a miniaturized, personal, wearable cleanroom. PROPER would be able to offer better protection than an N95 respirator mask, mainly because it is insensitive to seal fit and it shields the eyes as well. The PROPER SMS fabric is designed for single-use and not intended for reuse, as they may start to tear and fail but the rest of the parts can be disinfected and reused. We provide a set of guidelines to build a low-cost 3D printed solution for an effective PAPR system and describe the procedures to validate it to comply with the biosafety level 3 requirements. We have validated the prototype of PROPER unit for air flow, ISO class cleanliness level, oxygen and carbon-dioxide gas concentrations during exhalation, and present here these results for illustration. We demonstrate that the area inside the hood is more than 200 times cleaner than the external ambient without the operator and more than 175 times with the operator and in an aerosol exposed environment. We also include the procedure to clean and disinfect the equipment for reuse. PROPER may be a useful addition to provide protection to HCPs against the SARS-CoV-2 virus or other potential future viral diseases that are transmitted aerially.
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Affiliation(s)
- Miracle Israel Nazarious
- Group of Atmospheric Science, Department of Computer Science, Electrical and Space Engineering, Luleå, University of Technology, Luleå 97 187, Sweden
- Corresponding author.
| | - Thasshwin Mathanlal
- Group of Atmospheric Science, Department of Computer Science, Electrical and Space Engineering, Luleå, University of Technology, Luleå 97 187, Sweden
| | - Maria-Paz Zorzano
- Group of Atmospheric Science, Department of Computer Science, Electrical and Space Engineering, Luleå, University of Technology, Luleå 97 187, Sweden
- Centro de Astrobiología (CSIC-INTA), Torrejon de Ardoz, 28850 Madrid, Spain
- School of Geosciences, University of Aberdeen, Meston Building, King's College, Aberdeen AB24 3UE, UK
| | - Javier Martin-Torres
- Group of Atmospheric Science, Department of Computer Science, Electrical and Space Engineering, Luleå, University of Technology, Luleå 97 187, Sweden
- School of Geosciences, University of Aberdeen, Meston Building, King's College, Aberdeen AB24 3UE, UK
- Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), 18100 Granada, Spain
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Hlavac N, Guilhaume-Corrêa F, VandeVord PJ. Mechano-stimulation initiated by extracellular adhesion and cationic conductance pathways influence astrocyte activation. Neurosci Lett 2020; 739:135405. [PMID: 32979460 DOI: 10.1016/j.neulet.2020.135405] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 09/10/2020] [Accepted: 09/21/2020] [Indexed: 11/13/2022]
Abstract
Traumatic brain injury (TBI) represents a major cause of long-term disability worldwide. Primary damage to brain tissue leads to complex secondary injury mechanisms involving inflammation, oxidative stress and cellular activation/reactivity. The molecular pathways that exacerbate brain cell dysfunction after injury are not well understood and provide challenges to developing TBI therapeutics. This study aimed to delineate mechanisms of astrocyte activation induced by mechano-stimulation, specifically involving extracellular adhesion and cationic transduction. An in vitro model was employed to investigate 2D and 3D cultures of primary astrocytes, in which cells were exposed to a single high-rate overpressure known to cause upregulation of structural and proliferative markers within 72 h of exposure. An inhibitor of focal adhesion kinase (FAK) phosphorylation, TAE226, was used to demonstrate a relationship between extracellular adhesion perturbations and structural reactivity in the novel 3D model. TAE226 mitigated upregulation of glial fibrillary acidic protein in 3D cultures by 72 h post-exposure. Alternatively, incubation with gadolinium (a cationic channel blocker) during overpressure, demonstrated a role for cationic transduction in reducing the increased levels of proliferating cell nuclear antigen that occur at 24 h post-stimulation. Furthermore, early changes in mitochondrial polarization at 15 min and in endogenous ATP levels at 4-6 h occur post-overpressure and may be linked to later changes in cell phenotype. By 24 h, there was evidence of increased amine metabolism and increased nicotinamide adenine dinucleotide phosphate oxidase (NOX4) production. The overproduction of NOX4 was counteracted by gadolinium during overpressure exposure. Altogether, the results of this study indicated that both extracellular adhesion (via FAK activation) and cationic conductance (via ion channels) contribute to early patterns of astrocyte activation following overpressure stimulation. Mechano-stimulation pathways are linked to bioenergetic and metabolic disruptions in astrocytes that influence downstream oxidative stress, aberrant proliferative capacity and structural reactivity.
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Affiliation(s)
- Nora Hlavac
- Virginia Tech, Department of Biomedical Engineering and Mechanics, Blacksburg, VA, USA
| | | | - Pamela J VandeVord
- Virginia Tech, Department of Biomedical Engineering and Mechanics, Blacksburg, VA, USA; Salem Veterans Affairs Medical Center, Department of Research, Salem, VA, USA.
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Li P, Huang P, Liu Z, Du B, Li M. Experimental study on vented explosion overpressure of methane/air mixtures in manhole. J Hazard Mater 2019; 374:349-355. [PMID: 31026628 DOI: 10.1016/j.jhazmat.2019.04.046] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 03/26/2019] [Accepted: 04/13/2019] [Indexed: 06/09/2023]
Abstract
Gas explosion in manhole often occurs in cities. Many previous researches on gas explosion are not suitable for manhole explosion because of the particularity of manhole structure. To investigate the gas explosion in manhole, a full-scale manhole model was established, in which the explosion overpressure of methane/air mixtures were studied experimentally. The variation of blast wave overpressure with time at different distances was analyzed. In addition, the effects of methane concentration, ignition location and manhole cover weight on the external overpressure after manhole explosion were obtained. The results showed that at the experimental conditions in this paper, under the influence of vent mode and flame propagation, the maximum peak overpressure caused by manhole explosion was mostly at the third measuring point. And there were two peaks in the overpressure histories. It was also found that when the methane concentration was close to stoichiometric ratio, the ignition location was further away from the manhole head, and the weight of manhole cover increased, the peak overpressure of blast wave caused by explosion increased. Besides, some suggestions were put forward for the risk control of manhole explosion accident based on the experimental results.
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Affiliation(s)
- Pengliang Li
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, China
| | - Ping Huang
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, China.
| | - Zhenyi Liu
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, China
| | - Bingxuan Du
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, China
| | - Mingzhi Li
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, China
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Song Y, Zhang Q. The quantitative studies on gas explosion suppression by an inert rock dust deposit. J Hazard Mater 2018; 353:62-69. [PMID: 29635175 DOI: 10.1016/j.jhazmat.2018.03.052] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 03/25/2018] [Accepted: 03/27/2018] [Indexed: 06/08/2023]
Abstract
The traditional defence against propagating gas explosions is the application of dry rock dust, but not much quantitative study on explosion suppression of rock dust has been made. Based on the theories of fluid dynamics and combustion, a simulated study on the propagation of premixed gas explosion suppressed by deposited inert rock dust layer is carried out. The characteristics of the explosion field (overpressure, temperature, flame speed and combustion rate) at different deposited rock dust amounts are investigated. The flame in the pipeline cannot be extinguished when the deposited rock dust amount is less than 12 kg/m3. The effects of suppressing gas explosion become weak when the deposited rock dust amount is greater than 45 kg/m3. The overpressure decreases with the increase of the deposited rock dust amounts in the range of 18-36 kg/m3 and the flame speed and the flame length show the same trends. When the deposited rock dust amount is 36 kg/m3, the overpressure can be reduced by 40%, the peak flame speed by 50%, and the flame length by 42% respectively, compared with those of the gas explosion of stoichiometric mixture. In this model, the effective raised dust concentrations to suppress explosion are 2.5-3.5 kg/m3.
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Affiliation(s)
- Yifan Song
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Qi Zhang
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
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Stix J, de Moor JM. Understanding and forecasting phreatic eruptions driven by magmatic degassing. Earth Planets Space 2018; 70:83. [PMID: 31007532 PMCID: PMC6448360 DOI: 10.1186/s40623-018-0855-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/01/2018] [Indexed: 06/09/2023]
Abstract
This paper examines phreatic eruptions which are driven by inputs of magma and magmatic gas. We synthesize data from several significant phreatic systems, including two in Costa Rica (Turrialba and Poás) which are currently highly active and hazardous. We define two endmember types of phreatic eruptions, the first (type 1) in which a deeper hydrothermal system fed by magmatic gases is sealed and produces overpressure sufficient to drive explosive eruptions, and the second (type 2) where magmatic gases are supplied via open-vent degassing to a near-surface hydrothermal system, vaporizing liquid water which drives the phreatic eruptions. The surficial source of type 2 eruptions is characteristic, while the source depth of type 1 eruptions is commonly greater. Hence, type 1 eruptions tend to be more energetic than type 2 eruptions. The first type of eruption we term "phreato-vulcanian", and the second we term "phreato-surtseyan". Some systems (e.g., Ruapehu, Poás) can produce both type 1 and type 2 eruptions, and all systems can undergo sealing at various timescales. We examine a number of precursory signals which appear to be important in understanding and forecasting phreatic eruptions; these include very long period events, banded tremor, and gas ratios, in particular H2S/SO2 and CO2/SO2. We propose that if these datasets are carefully integrated during a monitoring program, it may be possible to accurately forecast phreatic eruptions.
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Affiliation(s)
- John Stix
- Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, QC H3A 0E8 Canada
| | - J. Maarten de Moor
- Observatorio Vulcanológico y Sismológico de Costa Rica (OVSICORI), Universidad Nacional, AP 2386-3000, Heredia, Costa Rica
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