Search

This study investigates the potential of a perforated structure for the control of near-wall turbulence in turbulent boundary layers. The perforated structure consists of a perforated plate, underneath of which is a backing chamber. The near-wall turbulent structures were analyzed using hot-wire measurements. Different inner-scaled chamber volumes from V + = 2.4 × 10 6 to 11.5 × 10 6 were considered to manipulate turbulent boundary layers at two Reynolds numbers of R e θ = 1165 and 2294. The findings reveal significant effects of the perforated structure on near-wall turbulent structures. Statistical analysis utilizing a variable-interval time-averaging technique illustrated a reduction of up to about 9% in sweep and ejection intensity, a decrease in about 25% in ejection frequency, and a decrease in approximately 33.5% in sweep frequency within the near-wall region, y + ≤ 30 , indicating that the perforated structure weakened burst events in this region. In addition, the perforated structure lifted the turbulence energy further from the wall. Consequently, there was a reduction of up to approximately 9% in turbulence intensities near the wall, contributing to locally diminished shear stresses and skin friction drag. When the inner-scaled chamber volume increased, the reduction in near-wall turbulence became more pronounced. [ABSTRACT FROM AUTHOR]

Igor Z Barjaktarevic,1 Russell G Buhr,1,2 Xiaoyan Wang,3 Scott Hu,1 David Couper,4 Wayne Anderson,4 Richard E Kanner,5 Robert Paine III,5 Surya P Bhatt,6 Nirav R Bhakta,7 Mehrdad Arjomandi,7 Robert J Kaner,8 Cheryl S Pirozzi,5 Jeffrey L Curtis,9,10 Wanda K O’Neal,4 Prescott G Woodruff,7 MeiLan K Han,9 Fernando J Martinez,8 Nadia Hansel,11 James Michael Wells,6 Victor E Ortega,12 Eric A Hoffman,13 Claire M Doerschuk,4 Victor Kim,14 Mark T Dransfield,6 M Bradley Drummond,4 Russell Bowler,15 Gerard Criner,14 Stephanie A Christenson,7 Bonnie Ronish,5 Stephen P Peters,12 Jerry A Krishnan,16 Donald P Tashkin,1 Christopher B Cooper1 On behalf of the NHLBI SubPopulations and InteRmediate Outcome Measures In COPD Study (SPIROMICS)1Department of Medicine, University of California, Los Angeles, Los Angeles, CA, USA; 2Department of Health Policy and Management, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, CA, USA; 3Department of General Internal Medicine and Health Services Research, University of California, Los Angeles, Los Angeles, CA, USA; 4Department of Medicine, University of North Carolina, Chapel Hill, NC, USA; 5Department of Medicine, University of Utah, Salt Lake City, UT, USA; 6Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA; 7Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; 8Department of Medicine, Weill Cornell Weill Cornell Medical Center, New York, NY, USA; 9Department of Medicine, University of Michigan, Ann Arbor, MI, USA; 10Medicine Service, VA Ann Arbor Healthcare System, Ann Arbor, MI, USA; 11Department of Medicine, John Hopkins University, Baltimore, MD, USA; 12Department of Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA; 13Department of Medicine, University of Iowa, Iowa City, IA, USA; 14Department of Thoracic Medicine and Surgery, Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA; 15Department of Medicine, National Jewish Health Systems, Denver, CO, USA; 16Department of Medicine, University of Illinois at Chicago, Chicago, IL, USACorrespondence: Christopher B CooperDepartments of Medicine and Physiology, David Geffen School of Medicine, University of California Los Angeles, 10833 Le Conte Avenue, 37-131 CHS, Los Angeles, CA 90095, USAEmail ccooper@mednet.ucla.eduObjective: Bronchodilator responsiveness (BDR) is prevalent in COPD, but its clinical implications remain unclear. We explored the significance of BDR, defined by post-bronchodilator change in FEV1 (BDRFEV1) as a measure reflecting the change in flow and in FVC (BDRFVC) reflecting the change in volume.Methods: We analyzed 2974 participants from a multicenter observational study designed to identify varying COPD phenotypes (SPIROMICS). We evaluated the association of BDR with baseline clinical characteristics, rate of prospective exacerbations and mortality using negative binomial regression and Cox proportional hazards models.Results: A majority of COPD participants exhibited BDR (52.7%). BDRFEV1 occurred more often in earlier stages of COPD, while BDRFVC occurred more frequently in more advanced disease. When defined by increases in either FEV1 or FVC, BDR was associated with a self-reported history of asthma, but not with blood eosinophil counts. BDRFVC was more prevalent in subjects with greater emphysema and small airway disease on CT. In a univariate analysis, BDRFVC was associated with increased exacerbations and mortality, although no significance was found in a model adjusted for post-bronchodilator FEV1.Conclusion: With advanced airflow obstruction in COPD, BDRFVC is more prevalent in comparison to BDRFEV1 and correlates with the extent of emphysema and degree of small airway disease. Since these associations appear to be related to the impairment of FEV1, BDRFVC itself does not define a distinct phenotype nor can it be more predictive of outcomes, but it can offer additional insights into the pathophysiologic mechanism in advanced COPD.Clinical trials registration: ClinicalTrials.gov: NCT01969344T4.Keywords: bronchodilator responsiveness, inspiratory capacity, FVC, FEV1, SPIROMICS

Barjaktarevic IZ, Buhr RG, Wang X, et al. Int J Chron Obstruct Pulmon Dis. 2019;14:2927– 2938. The authors have advised that there is an error in the Funding section on page 2935. The correct funding statement is as follows: FundingThis study was supported by R01HL125432-01A1 (MBD), T32HL007106-41 (RMB), and TL1TR001883-01 (RGB). SPIROMICS was supported by contracts from the NIH/NHLBI (HHSN268200900013C, HHSN2682009 00014C, HHSN268200900015C, HHSN268200900016C, HHSN268200900017C, HHSN268200900018C, HHSN268200 900019C, and HHSN268200900020C) and supplemented by contributions made through the Foundation for the NIH and the COPD Foundation from AstraZeneca/MedImmune, Bayer, Bellerophon Therapeutics, Boehringer-Ingelheim Pharmaceuticals, Inc., Chiesi Farmaceutici S.p.A., Forest Research Institute, Inc., GlaxoSmithKline, Grifols Therapeutics, Inc., Ikaria, Inc., Nycomed GmbH, Takeda Pharmaceutical Company, Novartis Pharmaceuticals Corporation, ProterixBio; Regeneron Pharmaceuticals, Inc., Sanofi, and Sunovion. The PRM analyses were supported by NHLBI HL122438 and HL138188. Mehrdad Arjomandi was supported by a grant from the Flight Attendant Medical Research Institute. The authors apologize for this error. Read the original article

Introduction: Oral intake of vitamins which present antioxidant characteristics can protect living organisms against oxidative damage caused by exposure to ionizing radiation. It was previously reported that administration of high levels of vitamin C can lead to increased DNA damage through production of hydroxyl radicals from hydrogen peroxide by the Fenton reaction. However, our early experiments did not confirm this hypothesis. The main goal of this study was to determine if high doses of Vit C can show life-saving radioprotective effects. Materials and Methods: Phase I: Seventy two male Balb/c mice weighing 20-25g were randomly divided into six groups of 12 animals each. Group I; Vit E for five days, Groups II and III; Vit C and Vit A. Group 4; all three vitamins. Group V; an over-the-counter multivitamin. Group VI; none of the above. Phase II: 120 male BALB/c mice weighing 20-25g were randomly divided into 12 groups of 10 each. Group I; Vit A for five days. Groups II-IV; Vit C 200 mg/kg, 400 mg/kg, 800 mg/kg, respectively. Group V-VII; Vit E at daily doses of 200 iu/kg, 400 iu/kg, 800 iu/kg, respectively. Group VIII and IX; all three vitamins at low and high doses, respectively. Group X; an over-the-counter multivitamin. Group XI; controls group and Group XII; received pure olive oil. All animals (Phases I and II) were exposed to a lethal dose of gamma rays and the survival rates of the animals were monitored and recorded continuously for 16 days after exposure. Results: Phase I: 14 days after irradiation the survival rate for control group was 33.33%, while the survival rates for the 1st to 5th groups were 45.45%, 81.81%, 50%, 57.14%, and 9.09% , respectively. Phase II: The survival rates in the control group and the group that only received pure olive oil, were 50% and 60%, respectively. Survival rate in the animals received Vit C at daily doses of 200 mg/kg, 400 mg/kg, 800 mg/kg, were 90%, 90% and 90%, respectively. Log rank (Mantel-Cox) test showed statistically significant differences between the survival rates in control irradiated mice (no vitamins) and mice received Vit C at daily doses of 200 mg/kg (P=0.042), 400 mg/kg (P=0.042) and 800 mg/kg (P=0.042). Conclusion: Altogether, findings of this study showed that even high doses of Vit C can show life-saving radioprotective effects. The significant radioprotective effect of Vit C at doses used in this study, opens new horizons in developing non-toxic, cost effective, easily available radioprotectors in life-threatening situations such as exposure to lethal doses of ionizing radiation. The radioprotective effect of Vit A and Vit E seem to be less efficient compared to that of Vit C.

Coherent structures in a turbulent boundary layer have been shown to have an influence on the skin-friction drag acting on surfaces beneath the boundary layer. The use of micro-cavities on a flat surface has recently shown the potential to passively control a turbulent boundary layer by attenuating the sweep events. Previous experiments have determined the design parameters of the cavity array for the optimal boundary-layer control by reducing the sweep events. However, investigating the flow physics behind the interaction of the boundary-layer flow with the cavities is challenging. High near-wall velocity gradients and very small scales and sizes of the cavity holes limit the experiments from investigating the flow characteristics very close to the wall and inside the holes. Therefore, in the present work, direct numerical simulations have been utilized to model the boundary layer flow over a flat surface with a micro-cavity array in order to understand the flow interactions. Detection of coherent structures in the boundary layer shows a reduction in the number of events over the cavity array. Reynolds stresses have been analyzed to determine the effect of micro-cavities. The reduction in the Reynolds shear stress results in a lower skin-friction drag. The flow fluctuations through the holes in the streamwise sequence have been found to be highly correlated using cross correlation. These flow fluctuations interact with the boundary layer to suppress the coherent structures. Overall, the use of the micro-cavity array has resulted in a reduced wall shear stress and approximately 5.6% lower local skin-friction drag. [ABSTRACT FROM AUTHOR]

This article describes a direct comparison between two symmetrical airfoils undergoing dynamic stall at high, unsteady reduced frequencies under otherwise identical conditions. Particle image velocimetry (PIV) was performed to distinguish the differences in flow structure between a NACA 0021 and a NACA 0012 airfoil undergoing dynamic stall. In addition, surface pressure measurements were performed to evaluate aerodynamic load and investigate the effect of laminar separation bubbles and vortex structures on the pressure fields surrounding the airfoils. Airfoil geometry is shown to have a significant effect on flow structure development and boundary layer separation, with separation occurring earlier for thinner airfoil sections undergoing constant pitch-rate motion. Inertial forces were identified to have a considerable impact on the overall force generation with increasing rotation rate. Force oscillation was observed to correlate with multiple vortex structures shedding at the trailing-edge during high rotation rates. The presence of laminar separation bubbles on the upper and lower surfaces was shown to dramatically influence the steady-state lift of both airfoils. Poststall characteristics are shown to be independent of airfoil geometry such that periodic vortex shedding was observed for all cases. However, the onset of deep stall is delayed with increased nondimensional pitch rate due to the delay in initial dynamic-stall vortex. [ABSTRACT FROM AUTHOR]

The present study experimentally investigates the potential application of a liquid metal enriched with aluminum oxide nanoparticles in a microchannel, which can have further applications in designing the next generation of solar thermal receivers equipped with microchannel fluid passages. The gallium nano-suspensions were prepared at mass fractions of 5%, 10% and 15% of aluminum oxide in gallium and were utilized in a copper-made rectangular microchannel liquid block at 200 °C. Effects of different operating parameters such as heater heat flux, mass fraction of nanoparticles and peristaltic flow rate on the overall heat transfer coefficient, value of the pressure drop and thermo-hydraulic performance index of the microchannel were experimentally investigated. Results showed that gallium nano-suspension offers a great potential for cooling the surface of the microchannel at high heat flux condition. The highest thermal performance index of 3.5 and 2.9 were achieved for the flow in laminar and turbulent regimes at mass fraction of 10%. Likewise, heat flux and peristaltic flow rate plausibly enhanced the heat transfer coefficient, however, for the mass concentration, the thermo-hydraulic performance was decreased at wt% = 15, due to the augmentation in the viscosity and agglomeration of aluminum oxide nanoparticles within the gallium, which was attributed to the increase in friction forces between layers of gallium. [ABSTRACT FROM AUTHOR]

Post-stall flow structure and surface pressures are evaluated to determine the effects of large angles of attack, perching like manoeuvres on the flow about a NACA 0021 airfoil exposed to dynamic stall. Phase-averaged particle image velocimetry was performed to assess the load development during the constant angular velocity pitch-up motion and in post-stall conditions. Evaluation of the resultant aerodynamic loads indicates that initial airfoil rotation generates significant delays in force response. Furthermore, the reduced frequency is shown to influence the angle of attack at which deep stall is initiated, to the extent that fully separated flows are delayed to an angle of attack of 60°. Vortex structures are linked to lower surface pressures with increased angle of attack and also for post-stall flow conditions. Likewise, the presence of the vortex structures shifts the centre of pressure significantly along the airfoil chordline immediately after cessation of the airfoil rotation. At the maximum angle of attack, the centre of pressure is shown to move aft for fully separated flow conditions. The variation in location of the centre of pressure, not only changes the moment generation and aero-elastic characteristics of the airfoil, but also increases structural torsional loading and fluctuations that result in increased fatigue of helicopter rotor shafts and horizontal-axis wind turbines. [ABSTRACT FROM AUTHOR]

The present study was designed to study the chemical composition, apparent and true metabolizable energy values of the walnut meal and to evaluate the effects of different levels of walnut meal (0, 10, 20 and 30%) on Japanese quail's growth performance, blood metabolites, relative weight of different organs, malondialdehyde (MDA) concentration in breast meat and egg yolks' cholesterol. This study was conducted as a completely randomize design with 288 unsexed Japanese quails randomly dividing into 4 treatments with 4 replicates of 18 birds each. As a result of this study, no significant differences were found for feed intake and feed conversion ratio (P>0.05), except the birds fed 30% walnut meal showed lower weight gain compared to the control at 7-21 days of age (P<0.05). There were no significant differences in serum glucose, uric acid, serum aspartate aminotranspherase (AST) and alanine aminotranspherase (ALT) activities between different dietary treatments. The serum low density lipoprotein (LDL), cholesterol and triglyceride tended to decrease linearly (P<0.01) as the walnut meal levels were increased. The serum high density lipoprotein (HDL) level in quails fed 10% walnut meal were significantly higher than control group (P<0.05). Consumption of different levels of walnut meal significantly decreased malondialdehyde (MDA) concentration in breast meat of chicks aged 42 d (P<0.01). Different dietary treatments had no effect on the relative weight of different organs and carcass traits. In general, walnut meal is a good source of energy (apparent metabolizable energy corrected for nitrogen (AMEn) 3689 kcal/kg), oil (23%) and crude protein (40%) and could be used up to 20% for young chicks and 30% for older chicks, without any adverse effect on growth performance. [ABSTRACT FROM AUTHOR]

Self-sustained oscillations of the grazing flow along the orifice of a Helmholtz resonator were considered numerically. These fluctuations are driven by hydrodynamic instabilities inside the shear layer and the resonant acoustical field. Quantitative prediction of this process requires accurate calculations of grazing flow characteristics over the three dimensional resonator. In this paper flow excitation phenomenon assumed to be associated with external pressure fluctuations within the turbulent boundary layer of grazing flow and acoustic response of the cavity. To this end a Large Eddy Simulation (LES) of the three dimensional shear flow over the orifice carried out at a low Mach number to allow predictions of the amplitude and frequency of the pressure and velocity fluctuations. For validation propose, for pressure fluctuations inside the cavity, a good quantitative agreement with published data was obtained. Therefore the simulations provide an ability to predict the resonating frequency, pressure and velocity field for different inlet conditions. [ABSTRACT FROM AUTHOR]

The jetting characteristics of dielectric barrier discharge (DBD) actuators make these devices suitable for augmenting boundary layer flows. The associated change to the hydrodynamic stability of the fluid arising from the actuator provides a mechanism through which a DBD-based laminar flow control (LFC) system can be developed. Historically, DBD actuators with electrodes arranged parallel to each other have been used for LFC with mixed results. An alternative is to use an actuator with electrodes placed orthogonally to each other. Orthogonally arranged actuators exhibit different jetting characteristics to conventional ones, and as such understanding the effect that these actuators have on the mean velocity profile within a flat plate boundary layer is of significant interest to the development of DBD-based LFC technology. In this investigation, the velocity distribution within a flat plate boundary layer in a zero pressure gradient is measured in response to the operation of an orthogonally arranged actuator. The results suggest that significant thinning of the boundary layer can be realized with an orthogonally arranged actuator, over a short distance downstream of the device, and used in conjunction with a subtle suction effect, this thinning can be exacerbated. However, further downstream, rapid thickening of the layer, supported by a decrease in the shape factor of the flow suggests that the layer becomes unstable, in an accelerated fashion, to the presence of the actuator. Hence the stability of the layer is found to be significantly altered by the presence of the orthogonally arranged actuator, a requisite for a LFC system. However, since the actuator produces a destabilizing effect, the development of a successful LFC system based on orthogonal actuators will require further work. [ABSTRACT FROM AUTHOR]

OBJECTIVE:: To investigate the potential effects of lifetime cumulative ozone (O3) exposure on acute pulmonary responses to O3. METHODS:: Fifteen healthy subjects from a larger cohort of young adults were exposed to 200 ppb O3 for 4 hours followed by bronchoscopy and bronchoalveolar lavage 18 hours later. Lung function, symptom questionnaires, and blood samples were obtained before and after each exposure. Subjects' lifetime cumulative O3 exposures were estimated from residential histories and air-quality monitoring data. RESULTS:: Acute exposure to O3 caused decrements in forced expiratory volume in 1 second (FEV1), maximal mid-expiratory flow rate (FEF25-75), and forced expiratory flow rate at 75% of forced vital capacity (FEF75), and an increase in plasma clara cell protein (CC16) level. Changes in CC16 and lower respiratory symptoms, but not in lung function, were positively correlated with lifetime cumulative O3 exposure. CONCLUSION:: Higher lifetime cumulative O3 exposure was associated with airway injury and respiratory symptom responses, but not with airway inflammatory or lung function responses, to acute O3 exposure. [ABSTRACT FROM AUTHOR]

Rationale: Repeated, short-term exposures to ozone (O3) lead to attenuation of the acute lung function and airway inflammatory responses seen after a single exposure in healthy subjects, but it is unclear whether these acute responses also attenuate in subjects with asthma.Objective: To address this question by exposing 14 subjects with asthma to 0.2 ppm O3 for either 4 hours on a single day or 4 hours on 4 consecutive days (multiday [MD]). At least 3 weeks later, subjects underwent the alternate exposure.Methods: Spirometry was performed immediately pre- and postexposure and bronchoalveolar lavage (BAL) was obtained 18 hours after each exposure.Main Results: The decrease in FEV1 was greatest across Day 2 of the MD (MD2) exposure and then gradually declined on successive days of the MD exposure (mean +/- SD decrease in FEV1 of 25.4 +/- 18.0% across MD2 compared with 4.2 +/- 6.5% across MD4). Respiratory symptoms followed a similar pattern to that of FEV1. Although the concentration of neutrophils in BAL after the MD4 exposure was not significantly different from that after the single-day exposure (1.7 +/- 1.3 x 10(4) cells/ml vs. 1.2 +/- 0.8 x 10(4) cells/ml, p = 0.20), the concentration of alveolar macrophages did significantly increase in BAL after the MD exposure (19.9 +/- 9.7 x 10(4) cells/ml after MD4 vs. 12.1 +/- 6.4 x 10(4) cells/ml after the single day).Conclusions: Alveolar macrophages are recruited to the airways of subjects with asthma with repeated short-term exposures to O3, suggesting a possible role for these cells in the chronic response to oxidant-induced injury. [ABSTRACT FROM AUTHOR]

Formation of bubbles in water inside an annulus pipe in a flow boiling regime was experimentally investigated. The effect of various variables, such as total dissolved solid materials (TDS) in terms of mass fraction, flow rate of water, and applied heat flux (HF) on the heat transfer coefficient (HTC) and bubble behavior of water, was experimentally investigated. A regression formula was fitted to estimate the average bubble diameter at various TDS values, with accuracy of <4.1% up to heat flux of 90 kW/m2. Results show that the presence of TDS materials can increase the contact angle of bubble and bubble diameter, and also promotes the HTC value of the system. However, flow rate of water suppressed bubble generation, and increased the heat transfer coefficient due to the renewal of the thermal boundary layer around the boiling surface. Likewise, it was identified that forced convective and nucleate boiling heat transfer mechanisms contribute to the flow of boiling water, and heat flux is a key parameter in determining the mechanism of heat transfer. In the present study, heat flux of 15 kW/m2 at 50 °C was the heat flux in which onset of nucleate boiling was identified inside the annulus pipe. The contact angle of water at TDS values of 300 mg/L and 1200 mg/L was 74° and 124°, respectively, showing the improvement in heat transfer characteristics of water due to the presence of TDS materials. [ABSTRACT FROM AUTHOR]

A thermodynamic assessment is conducted for a new configuration of a supercritical water gasification plant with a water–gas shift reactor. The proposed configuration offers the potential for the production of syngas at different H2:CO ratios for various applications such as the Fischer–Tropsch process or fuel cells, and it is a path for addressing the common challenges associated with conventional gasification plants such as nitrogen dilution and ash separation. The proposed concept consists of two reactors, R1 and R2, where the carbon containing fuel is gasified (in reactor R1) and in reactor R2, the quality of the syngas (H2:CO ratio) is substantially improved. Reactor R1 is a supercritical water gasifier and reactor R2 is a water–gas shift reactor. The proposed concept was modelled using the Gibbs minimization method with HSC chemistry software. Our results show that the supercritical water to fuel ratio (SCW/C) is a key parameter for determining the quality of syngas (molar ratio of H2:CO) and the carbon conversion reaches 100%, when the SWC/C ratio ranges between two and 2.5 at 500–1000 °C. [ABSTRACT FROM AUTHOR]

In the present work, an experimental investigation is performed to assess the thermal and electrical performance of a photovoltaic solar panel cooling with multi-walled carbon nanotube–water/ethylene glycol (50:50) nano-suspension (MWCNT/WEG50). The prepared nanofluid was stabilized using an ultrasonic homogenizer together with the addition of 0.1vol% of nonylphenol ethoxylates at pH = 8.9. To reduce the heat loss and to improve the heat transfer rate between the coolant and the panel, a cooling jacket was designed and attached to the solar panel. It was also filled with multi-walled carbon nanotube–paraffin phase change material (PCM) and the cooling pipes were passed through the PCM. The MWCNT/WEG50 nanofluid was introduced into the pipes, while the nano-PCM was in the cooling jacket. The electrical and thermal power of the system and equivalent electrical–thermal power of the system was assessed at various local times and at different mass fractions of MWCNTs. Results showed that with an increase in the mass concentration of the coolant, the electricity and power production were promoted, while with an increase in the mass concentration of the nanofluid, the pumping power was augmented resulting in the decrease in the thermal–electrical equivalent power. It was identified that a MWCNT/WEG50 nano-suspension at 0.2wt% can represent the highest thermal and electrical performance of 292.1 W/m2. It was also identified that at 0.2wt%, ~45% of the electricity and 44% of the thermal power can be produced with a photovoltaic (PV) panel between 1:30 pm to 3:30 pm. [ABSTRACT FROM AUTHOR]

Abstract We report an experimental demonstration of the chemical reactions for the chemical looping gasification process using molten bismuth oxide as the oxygen carrier. Cycling of the material without noticeable degradation was shown using a thermo-gravimetric analyser (TGA) furnace through both the reduction of bismuth oxide with carbon and its oxidation with air. The potential for any contamination of liquid bismuth oxide with the alumina container and of any agglomeration was assessed experimentally using x-ray diffraction (XRD) test. A kinetic model was also developed using Kissinger method to estimate the activation energy and the pre-exponential factor for the reduction and the oxidation reactions. It was found that the reduction and oxidation of bismuth and its oxide is feasible at temperatures of approximately 900 °C with the activation energies of 229.4 kJ/mol and 173.6 kJ/mol for the reduction and oxidation reactions, respectively at chemical conversion of 0.7. The chemical conversion of carbon in the presence of bismuth oxide was measured to reach 85% for the partial oxidation of carbon and to reach completion for the complete oxidation of bismuth. Furthermore, no containment challenges for liquid bismuth were identified in the alumina crucible at 900 °C. Hence, the proposed system offers potential to avoid the challenges of sintering and agglomeration that are associated with chemical looping systems using a solid oxygen carrier. Highlights • Carbon was gasified with liquid bismuth oxide. • TGA was used to investigate the cyclical reduction-oxidation of bismuth oxide. • The containment of liquid bismuth oxide was assessed in an alumina crucible. • A kinetic model was developed with Kissinger model. • Reduction-oxidation of bismuth over 5 cycles was plausible. [ABSTRACT FROM AUTHOR]