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Bustamante MCC, Costa CLL, Esperança MN, Mazziero VT, Cerri MO, Badino AC. Effect of impeller type on cellular morphology and production of clavulanic acid by Streptomyces clavuligerus. Braz J Microbiol 2024:10.1007/s42770-024-01306-0. [PMID: 38557863 DOI: 10.1007/s42770-024-01306-0] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 03/10/2024] [Indexed: 04/04/2024] Open
Abstract
It is essential to evaluate the effects of operating conditions in submerged cultures of filamentous microorganisms. In particular, the impeller type influences the flow pattern, power consumption, and energy dissipation, leading to differences in the hydrodynamic environment that affect the morphology of the microorganism. This work investigated the effect of different impeller types, namely the Rushton turbine (RT-RT) and Elephant Ear impellers in up-pumping (EEUP) and down-pumping (EEDP) modes, on cellular morphology and clavulanic acid (CA) production by Streptomyces clavuligerus in a stirred-tank bioreactor. At 800 rpm and 0.5 vvm, the cultivations performed using RT-RT and EEUP impellers provided higher shear conditions and oxygen transfer rates than those observed with EEDP. These conditions resulted in higher clavulanic acid production using RT-RT (380.7 mg/L) and EEUP (453.3 mg/L) impellers, compared to EEDP (196.6 mg/L). Although the maximum CA concentration exhibited the same order of magnitude for RT-RT and EEUP impellers, the latter presented 40% of the specific power consumption (4.9 kW/m3) compared to the classical RT-RT (12.0 kW/m3). The specific energy for CA production ( E CA ), defined as the energy cost to produce 1 mg of CA, was 3.5 times lower using the EEUP impeller (1.91 kJ/mgCA) when compared to RT-RT (5.91 kJ/mgCA). Besides, the specific energy for O2 transfer ( E O 2 ), the energy required to transfer 1 mmol of O2, was 2.3 times lower comparing the EEUP impeller (3.28 kJ/mmolO2) to RT-RT (7.65 kJ/mmolO2). The results demonstrated the importance of choosing the most suitable impeller configuration in conventional bioreactors to manufacture bioproducts.
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Affiliation(s)
- M C C Bustamante
- Department of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil
| | - C L L Costa
- Department of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil
| | - M N Esperança
- Federal Institute of Education, Science and Technology of São Paulo, Campus Capivari, Capivari, SP, 13360-000, Brazil
| | - V T Mazziero
- Department of Bioprocesses Engineering and Biotechnology, Faculty of Pharmaceutical Sciences, São Paulo State University, Araraquara, SP, 14801-902, Brazil
| | - M O Cerri
- Department of Bioprocesses Engineering and Biotechnology, Faculty of Pharmaceutical Sciences, São Paulo State University, Araraquara, SP, 14801-902, Brazil
| | - Alberto C Badino
- Department of Chemical Engineering, Federal University of São Carlos, C.P. 676, São Carlos, SP, 13565-905, Brazil.
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Salehi F, Inanloodoghouz M. Rheological properties and color indexes of ultrasonic treated aqueous solutions of basil, Lallemantia, and wild sage gums. Int J Biol Macromol 2023; 253:127828. [PMID: 37924915 DOI: 10.1016/j.ijbiomac.2023.127828] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 09/09/2023] [Accepted: 10/26/2023] [Indexed: 11/06/2023]
Abstract
This research aimed to analyze the impacts of sonication on the rheological properties and color indexes of aqueous solutions of Basil seed gum (BSG), Lallemantia seed gum (LSG), and Wild sage seed gum (WSG). The apparent viscosity (AV) of aqueous solutions of gums decreased with increasing shear rate (SR) from 12.2 s-1 to 134.5 s-1. Also, the AV (at SR = 61 s-1) of BSG, LSG, and WSG solutions reduced from 0.015 to 0.006 Pa.s, 0.023 to 0.010 Pa.s, and 0.009 to 0.004 Pa.s with enhancing the sonication time from 0 to 20 min, respectively. Various rheological equations were employed to fit the empirical values, and the findings confirmed that the Power law (PL) model was the best fit to explain the flow behaviour of these gums solutions. The consistency coefficient (k-index) of BSG, LSG, and WSG solutions significantly (p < 0.05) reduced from 0.108 to 0.017 Pa.sn, 0.143 to 0.033 Pa.sn, and 0.034 to 0.014 Pa.sn with increasing sonication time from 0 to 20 min, respectively. The flow behaviour index (n-index) of the gums solutions increased with increasing sonication time. By applying ultrasound, the lightness (L⁎) and blueness/yellowness (b⁎) indexes of the solutions were increased, and the greenness/redness (a⁎) index was reduced.
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Affiliation(s)
- Fakhreddin Salehi
- Department of Food Science and Technology, Bu-Ali Sina University, Hamedan, Iran.
| | - Moein Inanloodoghouz
- Department of Food Science and Technology, Bu-Ali Sina University, Hamedan, Iran
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3
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Mohseni S, Khoshfetrat AB, Rahbarghazi R, Khodabakhshaghdam S, Kaleybar LS. Influence of shear force on ex vivo expansion of hematopoietic model cells in a stirred tank bioreactor. J Biol Eng 2023; 17:38. [PMID: 37277832 DOI: 10.1186/s13036-023-00358-4] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 05/27/2023] [Indexed: 06/07/2023] Open
Abstract
To evaluate shear stress influence on ex vivo expansion of hematopoietic cell lineages for clinical application, in this study, human pro-monocytic cell (namely U937 cell line) was selected as a hematopoietic stem cell (HSC) model and cultured in suspension mode at two different agitation rates (50, 100 rpm) in the stirred bioreactor. At the agitation rate of 50 rpm, the cells achieved higher expansion folds (27.4 fold) with minimal morphological changes as well as apoptotic cell death, while at 100 rpm the expansion fold decreased after 5-day of culture in suspension culture in comparison with static culture and reached 24.5 fold at the end of the culture. The results of glucose consumption and lactate production were also in agreement with the data of fold expansion and indicated the preference of culture in the stirred bioreactor when agitated at 50 rpm. This study indicated the stirred bioreactor system with an agitation rate of 50 rpm and surface aeration may be used as a potential dynamic culture system for clinical applications of hematopoietic cell lineage. The current experiments shed data related to the effect of shear stress on human U937 cells, as a hematopoietic cell model, to set a protocol for expansion of HSCs for biomedical applications.
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Affiliation(s)
- Sofia Mohseni
- Chemical Engineering Faculty, Sahand University of Technology, Tabriz, 51335-1996, Iran
- Stem Cell and Tissue Engineering Research Laboratory, Sahand University of Technology, Tabriz, 51335-1996, Iran
| | - Ali Baradar Khoshfetrat
- Chemical Engineering Faculty, Sahand University of Technology, Tabriz, 51335-1996, Iran.
- Stem Cell and Tissue Engineering Research Laboratory, Sahand University of Technology, Tabriz, 51335-1996, Iran.
| | - Reza Rahbarghazi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - Leila Shafiei Kaleybar
- Chemical Engineering Faculty, Sahand University of Technology, Tabriz, 51335-1996, Iran
- Stem Cell and Tissue Engineering Research Laboratory, Sahand University of Technology, Tabriz, 51335-1996, Iran
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Serra T, Colomer J. Scavenging of polystyrene microplastics by sediment particles in both turbulent and calm aquatic environments. Sci Total Environ 2023; 884:163720. [PMID: 37137361 DOI: 10.1016/j.scitotenv.2023.163720] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/03/2023] [Accepted: 04/21/2023] [Indexed: 05/05/2023]
Abstract
Microplastic particles (MP) are emerging pollutants ubiquitously distributed in all aquatic environments, remaining in suspension in the water column or deposited in sediment beds. MP are suspended in the water column along with other particles with whom they might interact. The current study presents the results of slow-settling MP (Polystyrene) scavenged by fast-settling sediment particles. The study covers a wide range of salinities (from freshwater to saltwater) and shear rates (from calm to mixing ecosystems). In calm regions, the scavenging by fast-settling sediment particles produces the greatest removal of MP from the water column (42 % of MP in suspension), thus increasing the MP pollution of sediment beds. In contrast, turbulence reduces the settling of MP and sediment particles (72 % of MP remain in suspension), causing more pollution than in calm regions. Although salinity increased the buoyancy of MP, the scavenging by sediment has been found to overcome the increase in buoyancy. Consequently, MP are transported to the sediment bed independently on the salinity. Therefore hotspots of MP contamination in aquatic environments need to consider both the MP and sediment interaction and the local mixing of the water column.
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Affiliation(s)
- T Serra
- Department of Physics, Escola Politècnica Superior, University of Girona, Campus Montilivi, 17003 Girona, Spain.
| | - J Colomer
- Department of Physics, Escola Politècnica Superior, University of Girona, Campus Montilivi, 17003 Girona, Spain
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Uzunget SB, Sahin KE. Another possible determinant for ischemic stroke with nonvalvular atrial fibrillation other than conventional oral anticoagulant treatment: The relationship between whole blood viscosity and stroke☆. J Stroke Cerebrovasc Dis 2022; 31:106687. [PMID: 35932540 DOI: 10.1016/j.jstrokecerebrovasdis.2022.106687] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 10/16/2022] Open
Abstract
OBJECTIVES Patients with nonvalvular atrial fibrillation (NVAF) still experience ischemic stroke despite recommended medications and this could be the consequence of increased whole blood viscosity (WBV). We evaluated the predictive value of WBV for stroke in patients with NVFA despite receiving oral anticoagulant (OAC) therapy. METHODS One thousand and forty-three NVAF patients on OAC medication were followed up for median 36.13 ± 18.31 months. WBV was calculated according to the validated de Simone's formula. RESULTS WBV was significantly higher in stroke group when compared to non-stroke group at both low shear rate (LSR) and high shear rate (HSR). Multiple regression analysis demonstrated an independent association between WBV and stroke when adjusted for other risk factors. CONCLUSIONS WBV appears to be a profitable predictor of ischemic stroke in patients with NVAF receiving OAC.
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Affiliation(s)
- Sezen Baglan Uzunget
- Department of Cardiology, Sincan State Hospital Ankara, Sincan, Ankara 06933, Turkey.
| | - Kader Eliz Sahin
- Department of Cardiology, Adiyaman University Education and Research Hospital, Adiyaman, Turkey
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Gupta S, Igne B, Omar T, Román-Ospino AD, Hausner D, Muzzio F. Multi-layer Raman chemical mapping to investigate the effect of API particle size and blending shear rate on API domain sizes in pharmaceutical tablets. Int J Pharm 2022; 624:122052. [PMID: 35902051 DOI: 10.1016/j.ijpharm.2022.122052] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 06/23/2022] [Accepted: 07/21/2022] [Indexed: 11/28/2022]
Abstract
While macromixing (gross uniformity) has received a lot of attention in pharmaceutical powder blending, micromixing (particularly, particle-level aggregation) has been significantly less studied. This study investigated the impact of active pharmaceutical ingredient (API) particle size (D50: 11, 28, and 70 µm) and blending shear rate (low and high) that was caused by tumbling blending (specifically, a V-blender) on micro-mixing. The effect on micro-mixing (API domain sizes) was assessed in direct compression tablets using high-resolution Raman chemical mapping. Analyses of multiple layers within tablets enabled a more reliable understanding of the variability in API domain sizes with respect to the independent variables. The relationship between API domain sizes and the manufactured tablets' content uniformity (CU) was also investigated using near-infrared transmission spectroscopy. Generally, at low shear, as the API particle size decreased, the frequency and size of API agglomerates increased, resulting in poor CU. However, in all cases, API domain sizes drastically reduced at high shear, resulting in an acceptable CU. The results of this work clearly demonstrated the utility of a multi-layer, multi-tablet, and high-resolution Raman chemical mapping as an off-line process analytical technology (PAT) system, to enable quality-by-design driven formulation and process development.
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Affiliation(s)
- Shashwat Gupta
- Chemical and Biochemical Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08854, USA
| | - Benoît Igne
- GlaxoSmithKline, Analytical Sciences and Development, 1250 South Collegeville Road, Collegeville, PA, USA
| | - Thamer Omar
- Chemical and Biochemical Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08854, USA
| | - Andrés D Román-Ospino
- Chemical and Biochemical Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08854, USA
| | - Douglas Hausner
- Chemical and Biochemical Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08854, USA; GlaxoSmithKline, Analytical Sciences and Development, 1250 South Collegeville Road, Collegeville, PA, USA
| | - Fernando Muzzio
- Chemical and Biochemical Engineering, Rutgers University, 98 Brett Road, Piscataway, NJ 08854, USA.
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Sardelli L, Vangosa FB, Merli M, Ziccarelli A, Visentin S, Visai L, Petrini P. Bioinspired in vitro intestinal mucus model for 3D-dynamic culture of bacteria. Biomater Adv 2022; 139:213022. [PMID: 35891596 DOI: 10.1016/j.bioadv.2022.213022] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 05/27/2022] [Accepted: 07/05/2022] [Indexed: 06/15/2023]
Abstract
The intestinal mucus is a biological barrier that supports the intestinal microbiota growth and filters molecules. To perform these functions, mucus possesses optimized microstructure and viscoelastic properties and it is steadily replenished thus flowing along the gut. The available in vitro intestinal mucus models are useful tools in investigating the microbiota-human cells interaction, and are used as matrices for bacterial culture or as static component of microfluidic devices like gut-on-chips. The aim of this work is to engineer an in vitro mucus models (I-Bac3Gel) addressing in a single system physiological viscoelastic properties (i.e., 2-200 Pa), 3D structure and suitability for dynamic bacterial culture. Homogeneously crosslinked alginate hydrogels are optimized in composition to obtain target viscoelastic and microstructural properties. Then, rheological tests are exploited to assess a priori the hydrogels capability to withstand the flow dynamic condition. We experimentally assess the suitability of I-Bac3Gels in the evolving field of microfluidics by applying a dynamic flow to a bacterial-loaded mucus model and by monitoring E. coli growth and survival. The engineered models represent a step forward in the modelling of the mucus, since they can answer to different urgent needs such as a 3D structure, bioinspired properties and compatibility with dynamic system.
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Affiliation(s)
- Lorenzo Sardelli
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.
| | - Francesco Briatico Vangosa
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Marta Merli
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Anna Ziccarelli
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
| | - Sonja Visentin
- Molecular Biotechnology and Health Sciences Department, University of Torino, Torino, Italy
| | - Livia Visai
- Molecular Medicine Department (DMM), Center for Health Technologies (CHT), UdR INSTM, University of Pavia, Pavia, Italy; Department of Occupational Medicine, Toxicology and Environmental Risks, Istituti Clinici Scientifici (ICS) Maugeri, IRCCS, Pavia, Italy
| | - Paola Petrini
- Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy
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8
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Li W, Zu B, Hu L, Lan L, Zhang Y, Li J. Migration behaviors of microplastics in sediment-bearing turbulence: Aggregation, settlement, and resuspension. Mar Pollut Bull 2022; 180:113775. [PMID: 35665654 DOI: 10.1016/j.marpolbul.2022.113775] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 04/25/2022] [Accepted: 05/18/2022] [Indexed: 06/15/2023]
Abstract
The interaction between microplastics (MPs) and suspended sediment (SS) is important for the environmental fate of MPs. This study explored the interaction of MPs with SS and the vertical migration behavior of MPs in sediment-bearing turbulence. The turbulent shear flow caused MPs to aggregate. This aggregation resulted in a rapid increase in particle size, which peaked when the shear rate was 19.94 s-1, and then declined with a further increase in the shear rate. Compared to large MPs, small MPs were more prone to aggregation, which formed heterogeneous aggregate MPs-SS in sediment-bearing turbulence. Owing to the formation of heterogeneous aggregates, small MPs had a much higher settlement rate in sediment-bearing turbulence than in sediment-free turbulence. MPs in bottom sediments may resuspend owing to turbulent shear flow acting on sediments, causing secondary pollution. These results provide new insights into the aggregation, settlement, and resuspension behaviors of MPs in natural waters.
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Affiliation(s)
- Wang Li
- Chongqing Engineering Laboratory of Environmental Hydraulic Engineering, Chongqing Jiaotong University, Chongqing 400074, China
| | - Bo Zu
- Chongqing Engineering Laboratory of Environmental Hydraulic Engineering, Chongqing Jiaotong University, Chongqing 400074, China.
| | - Longteng Hu
- Chongqing Engineering Laboratory of Environmental Hydraulic Engineering, Chongqing Jiaotong University, Chongqing 400074, China
| | - Lisha Lan
- Chongqing Engineering Laboratory of Environmental Hydraulic Engineering, Chongqing Jiaotong University, Chongqing 400074, China
| | - Yunxia Zhang
- Chongqing Engineering Laboratory of Environmental Hydraulic Engineering, Chongqing Jiaotong University, Chongqing 400074, China
| | - Jiawen Li
- Chongqing Research Academy of Ecology and Environmental Sciences, Chongqing 401147, China
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Amin SB, Hansen AB, Mugele H, Simpson LL, Marume K, Moore JP, Cornwell WK, Lawley JS. High intensity exercise and passive hot water immersion cause similar post intervention changes in peripheral and cerebral shear. J Appl Physiol (1985) 2022; 133:390-402. [PMID: 35708700 DOI: 10.1152/japplphysiol.00780.2021] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Passive hot water immersion (PHWI) provides a peripheral vasculature shear stimulus comparable to low intensity exercise within the active skeletal muscle, whereas moderate and high intensity exercise elicit substantially greater shear rates in the peripheral vasculature, likely conferring greater vascular benefits. Few studies have compared post intervention shear rates in the peripheral and cerebral vasculature following high intensity exercise and PHWI, especially considering that the post intervention recovery period represents a key window in which adaptation occurs. Therefore, we aimed to compare shear rates in the internal carotid artery (ICA), vertebral artery (VA) and common femoral artery (CFA) between high intensity exercise and PHWI for up to 80 minutes post intervention. Fifteen healthy (27 ± 4 years), moderately trained individuals underwent three-time matched interventions in a randomised order which included 30 minutes of whole-body immersion in a 42°C hot bath, 30 minutes of treadmill running and 5x4 minute high intensity intervals (HIIE). There were no differences in ICA (P= 0.4643) and VA (P=0.1940) shear rates between PHWI and exercise (both continuous and HIIE) post intervention. All three interventions elicited comparable increases in CFA shear rate post intervention (P=0.0671), however, CFA shear rate was slightly higher 40 minutes post threshold running (P=0.0464) and, slightly higher, although not statically for HIIE (P=0.0565) compared with PHWI. Our results suggest that time and core temperature matched high intensity exercise and PHWI elicit limited changes in cerebral shear and comparable increases in peripheral vasculature shear rates when measured for up to 80 minutes post intervention.
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Affiliation(s)
- Sachin B Amin
- University Innsbruck, Department Sport Science, Innsbruck, Austria
| | | | - Hendrik Mugele
- University Innsbruck, Department Sport Science, Innsbruck, Austria
| | - Lydia L Simpson
- University Innsbruck, Department Sport Science, Innsbruck, Austria
| | - Kyohei Marume
- University Innsbruck, Department Sport Science, Innsbruck, Austria
| | - Jonathan P Moore
- School of Sport, Health and Exercise Science, Bangor University, Bangor, United Kingdom
| | - William K Cornwell
- Department of Medicine - Cardiology, University of Colorado Anschutz Medical Campus, Aurora CO, United States.,Clinical and Translational Research Center, University of Colorado Anschutz Medical Campus, Aurora CO, United States
| | - Justin S Lawley
- University Innsbruck, Department Sport Science, Innsbruck, Austria
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Alali MH, Lucas RAI, Junejo RT, Fisher JP. Impact of acute dynamic exercise and arterial shear rate modification on radial artery low-flow mediated constriction in young men. Eur J Appl Physiol 2022; 122:1885-1895. [PMID: 35551453 PMCID: PMC9287252 DOI: 10.1007/s00421-022-04963-x] [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: 12/02/2021] [Accepted: 04/25/2022] [Indexed: 11/30/2022]
Abstract
Purpose Leg cycling exercise acutely augments radial artery low-flow mediated constriction (L-FMC). Herein, we sought to determine whether this is associated with exercise-induced changes in arterial shear rate (SR). Methods Ten healthy and recreationally active young men (23 ± 2 years) participated in 30 min of incremental leg cycling exercise (50, 100, 150 Watts). Trials were repeated with (Exercise + WC) and without (Exercise) the use of a wrist cuff (75 mmHg) placed distal to the radial artery to increase local retrograde SR while reducing mean and anterograde SR. Radial artery characteristics were measured throughout the trial, and L-FMC and flow mediated dilatation (FMD) were assessed before and acutely (~ 10 min) after leg cycling. Results Exercise increased radial artery mean and anterograde SR, along with radial artery diameter, velocity, blood flow and conductance (P < 0.05). Exercise + WC attenuated the exercise-induced increase in mean and anterograde SR (P > 0.05) but also increased retrograde SR (P < 0.05). In addition, increases in radial artery blood flow and diameter were reduced during Exercise + WC (Exercise + WC vs. Exercise, P < 0.05). After Exercise, L-FMC was augmented (− 4.4 ± 1.4 vs. − 13.1 ± 1.6%, P < 0.05), compared to no change in L-FMC after Exercise + WC (− 5.2 ± 2.0 vs. − 3.0 ± 1.6%, P > 0.05). In contrast, no change in FMD was observed in either Exercise or Exercise + WC trials (P > 0.05). Conclusions These findings indicate that increases in L-FMC following exercise are abolished by the prevention of increases radial artery diameter, mean and anterograde SR, and by elevation of retrograde SR, during exercise in young men.
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Affiliation(s)
- Mohammad H Alali
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Rebekah A I Lucas
- School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Rehan T Junejo
- Department of Life Sciences, Faculty of Science and Engineering, Manchester Metropolitan University, Manchester, United Kingdom
| | - James P Fisher
- Department of Physiology, Faculty of Medical and Health Sciences, Manaaki Manawa-The Centre for Heart Research, University of Auckland, 85 Park Road, Grafton, Auckland, 1142, New Zealand.
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11
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Gamage PT, Dong P, Lee J, Gharaibeh Y, Zimin VN, Dallan LAP, Bezerra HG, Wilson DL, Gu L. Hemodynamic alternations following stent deployment and post-dilation in a heavily calcified coronary artery: In silico and ex-vivo approaches. Comput Biol Med 2021; 139:104962. [PMID: 34715552 DOI: 10.1016/j.compbiomed.2021.104962] [Citation(s) in RCA: 8] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 10/16/2021] [Accepted: 10/17/2021] [Indexed: 01/16/2023]
Abstract
In this work, hemodynamic alterations in a patient-specific, heavily calcified coronary artery following stent deployment and post-dilations are quantified using in silico and ex-vivo approaches. Three-dimensional artery models were reconstructed from OCT images. Stent deployment and post-dilation with various inflation pressures were performed through both the finite element method (FEM) and ex vivo experiments. Results from FEM agreed very well with the ex-vivo measurements, interms of lumen areas, stent underexpansion, and strut malapposition. In addition, computational fluid dynamics (CFD) simulations were performed to delineate the hemodynamic alterations after stent deployment and post-dilations. A pressure time history at the inlet and a lumped parameter model (LPM) at the outlet were adopted to mimic the aortic pressure and the distal arterial tree, respectively. The pressure drop across the lesion, pertaining to the clinical measure of instantaneous wave-free flow ratio (iFR), was investigated. Results have shown that post-dilations are necessary for the lumen gain as well as the hemodynamic restoration towards hemostasis. Malapposed struts induced much higher shear rate, flow disturbances and lower time-averaged wall shear stress (TAWSS) around struts. Post-dilations mitigated the strut malapposition, and thus the shear rate. Moreover, stenting induced larger area of low TAWSS (<0.4 Pa) and lager volume of high shear rate (>2000 s-1), indicating higher risks of in-stent restenosis (ISR) and stent thrombosis (ST), respectively. Oscillatory shear index (OSI) and relative residence time (RRT) indicated the wall regions more prone to ISR are located near the malapposed stent struts.
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Affiliation(s)
- Peshala T Gamage
- Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL, 32901, USA
| | - Pengfei Dong
- Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL, 32901, USA.
| | - Juhwan Lee
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Yazan Gharaibeh
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Vladislav N Zimin
- Cardiovascular Imaging Core Laboratory, Harrington Heart & Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, 44106, USA
| | - Luis A P Dallan
- Cardiovascular Imaging Core Laboratory, Harrington Heart & Vascular Institute, University Hospitals Cleveland Medical Center, Cleveland, OH, 44106, USA
| | - Hiram G Bezerra
- Interventional Cardiology Center, Heart and Vascular Institute, The University of South Florida, Tampa, FL, 33606, USA
| | - David L Wilson
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Linxia Gu
- Department of Biomedical and Chemical Engineering and Sciences, Florida Institute of Technology, Melbourne, FL, 32901, USA.
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Wang C, Ng TCA, Ng HY. Comparison between novel vibrating ceramic MBR and conventional air-sparging MBR for domestic wastewater treatment: Performance, fouling control and energy consumption. Water Res 2021; 203:117521. [PMID: 34391023 DOI: 10.1016/j.watres.2021.117521] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/25/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
Two crucial themes emerge from the growing application of MBRs treating domestic wastewater so far: fouling control and energy demand. The significance of in-situ shear-enhanced methods for fouling control in MBRs has been widely acknowledged with air sparging over decades. However, it is still a challenge to develop energy-efficient ways to replace energy-intensive air sparging for effective fouling control during long-term real domestic wastewater treatment. A novel vibrating flat-sheet ceramic MBR (VMBR) was established for investigating the effects of different shear rates on treatment performance, fouling control and specific energy demand compared with air-sparging MBR (ASMBR). Three levels of shear rates with vibration speed of 120, 80, and 40 RPM in the VMBR, versus specific aeration rate of 1.5, 1.0 and 0.5 LPM in the ASMBR were examined as high-, middle- and low-shear phases. Results showed that the VMBR removed over 78.35% TOC, 89.89% COD and 99.9% NH4-N over three phases, and retarded initial increases in transmembrane pressure to control membrane fouling effectively with average fouling rate around 2.31 kPa/d, 3.59 kPa/d and 10.15 kPa/d, almost 70% lower than the ASMBR in Phase 1, 2 and 3, respectively. Particle size distribution of mixed liquor revealed that colloids and biopolymer clusters were significantly reduced in the VMBR showing less propensity for foulant formation. DOM characteristics further indicated that lower production of polysaccharides and protein (by approximately half in Phases 1 and 2) of SMP and EPS in the VMBR generated lower biopolymer content, promoting better fouling mitigation and enhanced dewaterability compared to the ASMBR. Moreover, the VMBR showed superior energy efficiency for fouling control and could save 51.7% to 78.5% energy of the ASMBR under similar-shear condition. The combination of excellent treatment performance, fouling control and energy efficiency from the VMBR makes this an attractive strategy for future improvement of MBR designs in full-scale application with the potential to replace conventional ASMBR.
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Affiliation(s)
- Chuansheng Wang
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore
| | - Tze Chiang Albert Ng
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore
| | - How Yong Ng
- Centre for Water Research, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576, Singapore; National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411, Singapore.
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Zhussupbekov M, Méndez Rojano R, Wu WT, Massoudi M, Antaki JF. A Continuum Model for the Unfolding of von Willebrand Factor. Ann Biomed Eng 2021; 49:2646-58. [PMID: 34401970 DOI: 10.1007/s10439-021-02845-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/31/2021] [Indexed: 01/21/2023]
Abstract
von Willebrand Factor is a mechano-sensitive protein circulating in blood that mediates platelet adhesion to subendothelial collagen and platelet aggregation at high shear rates. Its hemostatic function and thrombogenic effect, as well as susceptibility to enzymatic cleavage, are regulated by a conformational change from a collapsed globular state to a stretched state. Therefore, it is essential to account for the conformation of the vWF multimers when modeling vWF-mediated thrombosis or vWF degradation. We introduce a continuum model of vWF unfolding that is developed within the framework of our multi-constituent model of platelet-mediated thrombosis. The model considers two interconvertible vWF species corresponding to the collapsed and stretched conformational states. vWF unfolding takes place via two regimes: tumbling in simple shear and strong unfolding in flows with dominant extensional component. These two regimes were demonstrated in a Couette flow between parallel plates and an extensional flow in a cross-slot geometry. The vWF unfolding model was then verified in several microfluidic systems designed for inducing high-shear vWF-mediated thrombosis and screening for von Willebrand Disease. The model predicted high concentration of stretched vWF in key regions where occlusive thrombosis was observed experimentally. Strong unfolding caused by the extensional flow was limited to the center axis or middle plane of the channels, whereas vWF unfolding near the channel walls relied upon the shear tumbling mechanism. The continuum model of vWF unfolding presented in this work can be employed in numerical simulations of vWF-mediated thrombosis or vWF degradation in complex geometries. However, extending the model to 3-D arbitrary flows and turbulent flows will pose considerable challenges.
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Elduayen-Echave B, Lizarralde I, Schneider PA, Ayesa E, Larraona GS, Grau P. Inclusion of shear rate effects in the kinetics of a discretized population balance model: Application to struvite precipitation. Water Res 2021; 200:117242. [PMID: 34052476 DOI: 10.1016/j.watres.2021.117242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 05/02/2021] [Accepted: 05/08/2021] [Indexed: 06/12/2023]
Abstract
The effect of mixing in the modelling of processes based on mass transfer phenomena is commonly ignored in wastewater treatment industry. In this contribution, the effect of the average shear rate in the nucleation and growth rates of struvite is analyzed by combining experimental data with simulation results obtained with a previously presented mass-based discretized population balance model. According to the obtained results, the effect of the average shear rate is identifiable for the selected data and mechanisms. Therefore, it should be considered when a detailed modelling of the process is needed. Consequently, in this contribution, the average shear rate has been decoupled from the kinetic constants. In addition, kinetic rates where it is explicitly included as a power law function have been proposed. The exponents in these power law functions for the primary homogeneous nucleation and growth are 1.3 and 0.3, respectively. Considering shear rate effects allowed to see in the simulation outputs experimentally observed effects: a faster pH decay and smaller particle distribution for increasing mixing intensities.
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Affiliation(s)
- B Elduayen-Echave
- CEIT-Basque Research and Technology Alliance (BRTA), Manuel Lardizabal 15, Donostia, San Sebastián 20018, Spain.
| | - I Lizarralde
- Universidad de Navarra, Tecnun Escuela de Ingenieros, Manuel Lardizabal 13, Donostia, San Sebastián 20018, Spain.
| | - P A Schneider
- Engineering & Energy, Murdoch University, 90 South St, Murdoch WA 6150, Australia.
| | - E Ayesa
- CEIT-Basque Research and Technology Alliance (BRTA), Manuel Lardizabal 15, Donostia, San Sebastián 20018, Spain.
| | - G S Larraona
- Universidad de Navarra, Tecnun Escuela de Ingenieros, Manuel Lardizabal 13, Donostia, San Sebastián 20018, Spain.
| | - P Grau
- Universidad de Navarra, Tecnun Escuela de Ingenieros, Manuel Lardizabal 13, Donostia, San Sebastián 20018, Spain.
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15
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Smith WC, Bae J, Zhang Y, Qin B, Wang Y, Kozak D, Ashraf M, Xu X. Impact of particle flocculation on the dissolution and bioavailability of injectable suspensions. Int J Pharm 2021; 604:120767. [PMID: 34087414 DOI: 10.1016/j.ijpharm.2021.120767] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 05/27/2021] [Accepted: 05/30/2021] [Indexed: 11/13/2022]
Abstract
Injectable suspensions occasionally exhibit variations in dissolution and bioavailability, which may impact the clinical outcome of the drug product. Here, variation in the injection method (i.e., applied shear) for triamcinolone acetonide (TA) injectable suspension (40 mg/mL) altered the flocculation state of the particles and subsequently their dissolution. Notably, TA suspensions contained primary particles of approximately 2 µm and secondary flocculates of tens of microns. The conversion between flocculated and deflocculated particles was rapid, reversible and highly shear dependent. As such, changing shear rates during laser diffraction (LD) measurement like stirring rate, sonication, and sample introduction method (micropipette vs 25-gauge needle) may result in variability in particle size distributions (PSD) that have the potential to alter drug dissolution. Furthermore, a non-sink, discriminatory in vitro release testing (IVRT) method was developed, which combined in-situ fiber optic UV with LD to simultaneously monitor the dissolution and changing PSD of the suspension. The simultaneously measured dissolution and PSD data showed that flocculated and deflocculated particles followed different dissolution pathways. Importantly, deflocculated particles dissolved up to six times faster than the flocculated particles. Similar shear-induced changes during injection could occur in a clinical setting and have implications for drug bioavailability.
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Affiliation(s)
- William C Smith
- Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA; Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Jungeun Bae
- Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA; Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Ying Zhang
- Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA; Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Bin Qin
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Yan Wang
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Darby Kozak
- Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Muhammad Ashraf
- Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Xiaoming Xu
- Office of Testing and Research, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA.
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Khodabakhshaghdam S, Khoshfetrat AB, Rahbarghazi R. Alginate-chitosan core-shell microcapsule cultures of hepatic cells in a small scale stirred bioreactor: impact of shear forces and microcapsule core composition. J Biol Eng 2021; 15:14. [PMID: 33865460 PMCID: PMC8052835 DOI: 10.1186/s13036-021-00265-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [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: 12/20/2020] [Accepted: 04/03/2021] [Indexed: 01/20/2023] Open
Abstract
A small scale stirred bioreactor was designed and the effect of different agitation rates (30, 60 and 100 rpm) was investigated on HepG2 cells cultured in alginate-chitosan (AC) core-shell microcapsule in terms of the cell proliferation and liver-specific function. The microencapsulated hepatic cells could proliferate well when they were cultured for 10 days at 30 rpm while the cell-laden microcapsules showed no cell proliferation at 100 rpm in the bioreactor system. Albumin production rate, as an important liver function, increased also 1.8- and 1.5- fold under stirring rate of 30 rpm compared to the static culture and 60 rpm of agitation, respectively. Moreover, In comparison with the static culture, about 1.5-fold increment in urea production was observed at 30 rpm. Similarly, the highest expressions of albumin and P450 genes were found at 30 rpm stirring rate, which were 4.9- and 19.2-fold of the static culture. Addition of collagen to the microcapsule core composition (ACol/C) could improve the cell proliferation and functionality at 60 rpm in comparison with the cell-laden microcapsules without collagen. The study demonstrated the hepatic cell-laden ACol/C microcapsule hydrogel cultured in the small scale stirred bioreactor at low mixing rate has a great potential for mass production of the hepatic cells while maintaining liver-specific functions.
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Affiliation(s)
- Shahla Khodabakhshaghdam
- Chemical Engineering Faculty, Sahand University of Technology, Tabriz, 51335-1996, Iran
- Stem Cell and Tissue Engineering Research Laboratory, Sahand University of Technology, Tabriz, 51335-1996, Iran
| | - Ali Baradar Khoshfetrat
- Chemical Engineering Faculty, Sahand University of Technology, Tabriz, 51335-1996, Iran.
- Stem Cell and Tissue Engineering Research Laboratory, Sahand University of Technology, Tabriz, 51335-1996, Iran.
| | - Reza Rahbarghazi
- Stem Cell Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Applied Cell Sciences, Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
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Ribeiro RMMGP, Esperança MN, Sousa APA, Neto ÁB, Cerri MO. Individual effect of shear rate and oxygen transfer on clavulanic acid production by Streptomyces clavuligerus. Bioprocess Biosyst Eng 2021; 44:1721-32. [PMID: 33821325 DOI: 10.1007/s00449-021-02555-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/17/2021] [Indexed: 10/21/2022]
Abstract
The production of biocompounds through the cultivation of filamentous microorganisms is mainly affected by Oxygen Transfer Rate (OTR) and shear rate ([Formula: see text]) conditions. Despite efforts have been made to evaluate the effect of operating variables (impeller speed, N; and airflow rate, ϕair) on clavulanic acid production, no analysis regarding the effect of OTR and [Formula: see text] was made. Then, the aim of this study was to evaluate the dissociated effect of physical phenomena such as oxygen transfer and shear rate in the production of clavulanic acid from Streptomyces clavuligerus using a stirred tank bioreactor. Streptomyces clavuligerus cultivations were performed at five different OTR and [Formula: see text] conditions by manipulating the operating conditions (N, ϕair, and gas inlet composition). Cultivations performed at equal impeller speed (600 rpm, similar [Formula: see text]) using oxygen enrichment, showed that CA productivity (ProdCA) was positively affected by OTR increase. Subsequently, the different shear conditions (achieved by varying the impeller speed) lead to an increase in CA production levels. Despite both OTR and shear rate positively enhanced CA productivity, [Formula: see text] exhibited the highest impact: an increase of 145% in OTRinitial enhanced the clavulanic acid productivity of about 29%, while an increment in the shear rate of 134% raised the ProdCA in 53%.
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18
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Malkin AY. Shear-induced transitions in colloidal and polymeric liquids. Adv Colloid Interface Sci 2021; 290:102381. [PMID: 33640686 DOI: 10.1016/j.cis.2021.102381] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/05/2021] [Accepted: 02/06/2021] [Indexed: 11/22/2022]
Abstract
This review reflects different aspects of wide current studies of the phenomena related to the shear-induced structure transformation in various complex liquids. Experimental data, being the basis of this discussion, were obtained for polymeric liquids (melts, blends, solutions) and different dispersions (colloidal solutions, suspensions, emulsions). The general initial input of shearing is the creation of inhomogeneities which can continue to remain as separate domains, become the nuclei of new phases, or become diffuse, leading to phase separation. The following effects are discussed: diffusion-induced phase separation, phase transitions occurring mainly due to the deformation-driven orientation of polymer chains and worm-like micelles that results in the formation of a liquid-crystal state, as well as self-assembly effects. It can be stressed that the appearance of regular structures takes place in systems that can coexist in different concentrations or phase states at the same stress or shear rate. This is linked with the existence of two-value points on flow curves (part of a flow curve with negative slope) or transient regimes of deformation that lead to instability of the flow. The described experimental facts are briefly discussed on the basis of the application of different constitutive molecular or phenomenological rheological models.
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19
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Yamato Y, Higaki Y, Fujie S, Hasegawa N, Horii N, Aoyama H, Yamashina Y, Ogoh S, Iemitsu M. Acute effect of passive one-legged intermittent static stretching on regional blood flow in young men. Eur J Appl Physiol 2020; 121:331-337. [PMID: 33079234 DOI: 10.1007/s00421-020-04524-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 10/03/2020] [Indexed: 01/27/2023]
Abstract
PURPOSE Passive stretching reduces stiffness in the lower limb arteries of the stretched limb. To address this physiological mechanism, we measured the change in shear rate in the posterior tibial artery during a single bout of one-legged passive calf stretching compared with that in the non-stretched leg. METHODS The diameter, mean blood velocity, blood flow, and shear rate in the posterior tibial artery were measured using Doppler ultrasound before (baseline), during, and after a one-legged passive intermittent calf stretching procedure (six repetitions of 30-s static stretch with 10-s relaxation) in nine healthy young men. RESULTS In the posterior tibial artery of the stretched leg, the arterial diameter significantly decreased from baseline during the stretching period (baseline vs. stretching period of the 6th set, 0.19 ± 0.01 vs. 0.18 ± 0.01 cm, P < 0.05) without any change in shear rate and mean blood velocity. In contrast, during the relaxation period, the mean blood velocity (baseline vs. relaxation period of the 5th set, 2.98 ± 0.54 vs. 6.25 ± 1.48 cm/s) increased, and consequently, the shear rate (baseline vs. relaxation period of the 5th set, 66.75 ± 15.39 vs. 122.85 ± 29.40 s-1) increased (each P < 0.01); however, there was no change in arterial diameter. In contrast, these values in the non-stretched leg were unchanged at all-time points. CONCLUSIONS The stretching procedure increased the shear rate in the peripheral artery of the stretched leg during the relaxation period. This finding indicates that the local hemodynamic response (possibly through endothelial function), resulting from an increase in shear stress, may contribute to stretching-induced attenuation of local arterial stiffness.
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Affiliation(s)
- Yosuke Yamato
- Department of Physical Therapy, Aino University, Osaka, Japan
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Yuya Higaki
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Shumpei Fujie
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Natsuki Hasegawa
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
| | - Naoki Horii
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Hiroki Aoyama
- Department of Physical Therapy, Aino University, Osaka, Japan
| | | | - Shigehiko Ogoh
- Department of Biomedical Engineering, Toyo University, Saitama, Japan
| | - Motoyuki Iemitsu
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
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20
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Nowicki A, Gambin B, Secomski W, Trawinski Z, Szubielski M, Olszewski R. DOES FLOW-MEDIATED DILATION NORMALIZATION FOR BASE-SCALED SHEAR RATE IMPROVE ITS VALUE IN CORONARY ARTERY DISEASE DIAGNOSTICS? Ultrasound Med Biol 2020; 46:2551-2555. [PMID: 32600670 DOI: 10.1016/j.ultrasmedbio.2020.05.018] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 05/28/2020] [Accepted: 05/29/2020] [Indexed: 06/11/2023]
Abstract
The article presents a new normalization of flow-mediated dilation (FMD) in the radial artery, taking into account the parameter BSSR being equal to the ratio of the basal shear rate (BS) measured before the cuff inflation and post occlusive shear rate (SR). The in vivo usefulness of the new normalization algorithm was evaluated in two groups of patients. In group I, comprising 15 healthy volunteers, the normalized FMD/SR was (3.19 ± 1.4)•10-4, while in group II, comprising 13 patients with stable coronary artery disease (CAD), it was (1.02 ± 0.76)•10-4. We calculated almost 50% larger difference between the average values after normalizing FMD/BSSR. Specifically, the FMD/BSSR was equal to 28 ± 9.40 in group I and 6.01 ± 3.74 in group II. The prediction of CAD patients based on FMD/SR values had a sensitivity of 83.3% and a specificity of 84.6%, whereas the prediction of CAD patients based on the FMD/BSSR values revealed 100% sensitivity and specificity. These results confirm the usefulness of the novel normalization algorithm of the FMD in differentiation of normal patients from those with stable CAD.
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Affiliation(s)
- Andrzej Nowicki
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland.
| | - Barbara Gambin
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland
| | - Wojciech Secomski
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland
| | - Zbigniew Trawinski
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland
| | | | - Robert Olszewski
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland; Department of Geriatrics, National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland
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Bortot M, Sharifi A, Ashworth K, Walker F, Cox A, Ruegg K, Clendenen N, Neeves KB, Bark D, Di Paola J. Pathologic Shear and Elongation Rates Do Not Cause Cleavage of Von Willebrand Factor by ADAMTS13 in a Purified System. Cell Mol Bioeng 2020; 13:379-390. [PMID: 32952737 PMCID: PMC7479076 DOI: 10.1007/s12195-020-00631-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 06/18/2020] [Indexed: 01/13/2023] Open
Abstract
INTRODUCTION Pathological flows in patients with severe aortic stenosis are associated with acquired von Willebrand syndrome. This syndrome is characterized by excessive cleavage of von Willebrand factor by its main protease, A Disintegrin and Metalloproteinase with a Thrombospondin Type 1 Motif, Member 13 (ADAMTS13) leading to decreased VWF function and mucocutaneous bleeding. Aortic valve replacement and correction of the flow behavior to physiological levels reverses the syndrome, supporting the association between pathological flow and acquired von Willebrand syndrome. We investigated the effects of shear and elongational rates on von Willebrand factor cleavage in the presence of ADAMTS13. METHODS We identified acquired von Willebrand syndrome in five patients with severe aortic stenosis. Doppler echography values from these patients were used to develop three computational fluid dynamic (CFD) aortic valve models (normal, mild and severe stenosis). Shear, elongational rates and exposure times identified in the CFD simulations were used as parameters for the design of microfluidic devices to test the effects of pathologic shear and elongational rates on the structure and function of von Willebrand factor. RESULTS The shear rates (0-10,000s-1), elongational rates (0-1000 s-1) and exposure times (1-180 ms) tested in our microfluidic designs mimicked the flow features identified in patients with aortic stenosis. The shear and elongational rates tested in vitro did not lead to excessive cleavage or decreased function of von Willebrand factor in the presence of the protease. CONCLUSIONS High shear and elongational rates in the presence of ADAMTS13 are not sufficient for excessive cleavage of von Willebrand Factor.
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Affiliation(s)
- Maria Bortot
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Alireza Sharifi
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 USA
| | - Katrina Ashworth
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Faye Walker
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Allaura Cox
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Katherine Ruegg
- Hemophilia Center, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Nathan Clendenen
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - Keith B. Neeves
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
| | - David Bark
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045 USA
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 USA
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523 USA
| | - Jorge Di Paola
- Department of Pediatrics, Washington University in St. Louis, 660 S. Euclid Avenue, Campus Box 8208, 5th floor MPRB, St. Louis, MO 63110 USA
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Qazi WM, Ekberg O, Wiklund J, Kotze R, Stading M. Assessment of the Food-Swallowing Process Using Bolus Visualisation and Manometry Simultaneously in a Device that Models Human Swallowing. Dysphagia 2019; 34:821-833. [PMID: 30840137 PMCID: PMC6825639 DOI: 10.1007/s00455-019-09995-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 02/26/2019] [Indexed: 11/25/2022]
Abstract
The characteristics of the flows of boluses with different consistencies, i.e. different rheological properties, through the pharynx have not been fully elucidated. The results obtained using a novel in vitro device, the Gothenburg Throat, which allows simultaneous bolus flow visualisation and manometry assessments in the pharynx geometry, are presented, to explain the dependence of bolus flow on bolus consistency. Four different bolus consistencies of a commercial food thickener, 0.5, 1, 1.5 and 2 Pa s (at a shear rate of 50 s-1)-corresponding to a range from low honey-thick to pudding-thick consistencies on the National Dysphagia Diet (NDD) scale-were examined in the in vitro pharynx. The bolus velocities recorded in the simulator pharynx were in the range of 0.046-0.48 m/s, which is within the range reported in clinical studies. The corresponding wall shear rates associated with these velocities ranged from 13 s-1 (pudding consistency) to 209 s-1 (honey-thick consistency). The results of the in vitro manometry tests using different consistencies and bolus volumes were rather similar to those obtained in clinical studies. The in vitro device used in this study appears to be a valuable tool for pre-clinical analyses of thickened fluids. Furthermore, the results show that it is desirable to consider a broad range of shear rates when assessing the suitability of a certain consistency for swallowing.
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Affiliation(s)
- Waqas M Qazi
- Agrifood and Bioscience, Product Design and Perception, RISE, Research Institutes of Sweden AB, Göteborg, Sweden.
- Department of Industrial and Material Sciences, Chalmers University of Technology, Göteborg, Sweden.
| | - Olle Ekberg
- Diagnostic Centre of Imaging and Functional Medicine, Skåne University Hospital, Lund, Sweden
| | - Johan Wiklund
- Incipientus Ultrasound Flow Technologies AB, Frans Perssons Väg 6, 412 76, Göteborg, Sweden
| | - Reinhardt Kotze
- Incipientus Ultrasound Flow Technologies AB, Frans Perssons Väg 6, 412 76, Göteborg, Sweden
| | - Mats Stading
- Agrifood and Bioscience, Product Design and Perception, RISE, Research Institutes of Sweden AB, Göteborg, Sweden
- Department of Industrial and Material Sciences, Chalmers University of Technology, Göteborg, Sweden
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23
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Zhang H, Yang L, Zang X, Cheng S, Zhang X. Effect of shear rate on floc characteristics and concentration factors for the harvesting of Chlorella vulgaris using coagulation-flocculation-sedimentation. Sci Total Environ 2019; 688:811-817. [PMID: 31255819 DOI: 10.1016/j.scitotenv.2019.06.321] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 06/15/2019] [Accepted: 06/20/2019] [Indexed: 06/09/2023]
Abstract
Coagulation-based separation has been increasingly applied to microalgal harvesting because of its competitive cost and high scalability. The characteristics of flocs formed during coagulation/flocculation are critical for efficient harvesting. However, few studies have been devoted to systematically investigating the structural characteristics of microalgal flocs and their influences on subsequent settling performance. In this paper, the dynamic mean size and fractal dimension, strength, regrowth and settling performance of Al3+ coagulated Chlorella vulgaris flocs were characterized at various flocculation shear rates. The influence of shear rate on floc characteristics was revealed. An appropriate shear rate (9 s-1) produced more desirable microalgal flocs (in terms of size and compactness), with better settling performance and a higher concentration factor, than higher or lower shear rates, favoring their separation and subsequent harvesting. At this condition, the concentration factor reached 13.50, which was a 177.21% improvement over the 4.87 reached at a low shear rate.
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Affiliation(s)
- Haiyang Zhang
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Lin Yang
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaomiao Zang
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shaozhe Cheng
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuezhi Zhang
- Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China; Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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24
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Tanioka S, Ishida F, Kishimoto T, Tanaka K, Shimosaka S, Suzuki H. Prediction of the extent of thrombus formation in the parent artery after endovascular occlusion of a distal anterior cerebral artery aneurysm using computational fluid dynamics. J Clin Neurosci 2019; 74:210-212. [PMID: 31420275 DOI: 10.1016/j.jocn.2019.08.042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 08/05/2019] [Indexed: 11/25/2022]
Abstract
Endovascular coiling of a cerebral aneurysm and coil occlusion of the parent artery have been occasionally performed to treat cerebral aneurysms; however, it is difficult to predict the accurate extent of thrombus formation in the parent artery proximal to the coiled aneurysm and the coil-occluded parent artery preoperatively, and unexpected occlusion of the arterial branches can occur by thrombus extension into or in the parent artery. The authors describe a case of a distal anterior cerebral artery (ACA) aneurysm treated by endovascular parent artery occlusion (PAO) with preoperative computational fluid dynamics (CFD) prediction of the extent of thrombus formation. A 73-year-old woman presented with subarachnoid hemorrhage and an aneurysm that was located on the right pericallosal artery distal to the paracentral artery bifurcation. Endovascular coiling of the aneurysm and the pericallosal artery was planned. In advance of the treatment, CFD was performed to predict the extent of thrombus formation with specific wall shear stress and shear rate thresholds. The hemodynamic results indicated that coiling of the aneurysm resulted in thrombus formation in the pericallosal artery up to just distal to the paracentral artery ostium; therefore, the treatment was implemented according to the CFD prediction. Postoperative digital subtraction angiography revealed that the extent of thrombus formation was consistent with the preoperative CFD prediction. This technique may prevent unexpected occlusion of arterial branches.
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Affiliation(s)
- Satoru Tanioka
- Department of Neurosurgery, Mie Chuo Medical Center, 2158-5 Myojin-cho, Hisai, Tsu, Mie 514-1101, Japan.
| | - Fujimaro Ishida
- Department of Neurosurgery, Mie Chuo Medical Center, 2158-5 Myojin-cho, Hisai, Tsu, Mie 514-1101, Japan
| | - Tomoyuki Kishimoto
- Department of Neurosurgery, Mie Chuo Medical Center, 2158-5 Myojin-cho, Hisai, Tsu, Mie 514-1101, Japan
| | - Katsuhiro Tanaka
- Department of Neurosurgery, Mie Chuo Medical Center, 2158-5 Myojin-cho, Hisai, Tsu, Mie 514-1101, Japan
| | - Shinichi Shimosaka
- Department of Neurosurgery, Mie Chuo Medical Center, 2158-5 Myojin-cho, Hisai, Tsu, Mie 514-1101, Japan.
| | - Hidenori Suzuki
- Department of Neurosurgery, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie 514-8507, Japan.
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25
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Stroobach M, Haya L, Fenech M. Effects of red blood cell aggregation on microparticle wall adhesion in circular microchannels. Med Eng Phys 2019; 69:100-108. [PMID: 31088761 DOI: 10.1016/j.medengphy.2019.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 03/26/2019] [Accepted: 04/28/2019] [Indexed: 12/14/2022]
Abstract
The wall adhesion of 1 µm microparticles in human blood was studied in circular microchannels. The level of particle wall adhesion was measured for varying levels of shear rate and varying degrees of red blood cell aggregation, which was modulated by the addition of macromolecule dextran 500. The blood preparations were injected into PDMS microfluidic devices that were modified to have circular channels, better matching the geometry of physiological microcirculation compared to square channels or Couette flow systems. The circular walls of the microchannels were embedded with biotinylated phospholipids to which marginating microspheres coated with streptavidin bound. The particle wall adhesion was evaluated by counting the particles adhering to the channel wall after flushing the channel. Blood preparations of five dextran concentrations (including baseline case of 0%) were tested for four flow velocities, to quantify the effects of aggregation for varying shear rate. It was found that the level of particle wall adhesion was positively correlated with the level of RBC aggregation, particularly at low shear rates, when aggregation was enhanced. The particle adhesion was especially enhanceat aggregation levels in the range of physiological aggregation levels of whole blood, suggesting that RBC aggregation plays an important role in the dynamic of platelets and leukocytes in vivo.
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Affiliation(s)
- Mark Stroobach
- Department of Mechanical Engineering, University of Ottawa, Ottawa, Canada.
| | - Laura Haya
- Department of Mechanical Engineering, University of Ottawa, Ottawa, Canada.
| | - Marianne Fenech
- Department of Mechanical Engineering, University of Ottawa, Ottawa, Canada.
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26
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Lakshmanan HHS, Shatzel JJ, Olson SR, McCarty OJT, Maddala J. Modeling the effect of blood vessel bifurcation ratio on occlusive thrombus formation. Comput Methods Biomech Biomed Engin 2019; 22:972-980. [PMID: 31066295 DOI: 10.1080/10255842.2019.1610744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Vascular geometry is a major determinant of the hemodynamics that promote or prevent unnecessary vessel occlusion from thrombus formation. Bifurcations in the vascular geometry are repeating structures that introduce flow separation between parent and daughter vessels. We modelled the blood flow and shear rate in a bifurcation during thrombus formation and show that blood vessel bifurcation ratios determine the maximum shear rate on the surface of a growing thrombus. We built an analytical model that may aid in predicting microvascular bifurcation ratios that are prone to occlusive thrombus formation. We also observed that bifurcation ratios that adhere to Murray's law of bifurcations may be protected from occlusive thrombus formation. These results may be useful in the rational design of diagnostic microfluidic devices and microfluidic blood oxygenators.
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Affiliation(s)
- Hari Hara Sudhan Lakshmanan
- a Biomedical Engineering, School of Medicine , Oregon Health & Science University , Portland , OR , USA.,b Chemical and Biomedical Engineering , West Virginia University , Morgantown , WV , USA
| | - Joseph J Shatzel
- a Biomedical Engineering, School of Medicine , Oregon Health & Science University , Portland , OR , USA.,c Division of Hematology-Oncology, School of Medicine , Oregon Health & Science University , Portland , OR , USA
| | - Sven R Olson
- c Division of Hematology-Oncology, School of Medicine , Oregon Health & Science University , Portland , OR , USA
| | - Owen J T McCarty
- a Biomedical Engineering, School of Medicine , Oregon Health & Science University , Portland , OR , USA.,c Division of Hematology-Oncology, School of Medicine , Oregon Health & Science University , Portland , OR , USA
| | - Jeevan Maddala
- a Biomedical Engineering, School of Medicine , Oregon Health & Science University , Portland , OR , USA.,b Chemical and Biomedical Engineering , West Virginia University , Morgantown , WV , USA
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27
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Abstract
The pharynx is critical for correct swallowing, facilitating the transport of both air and food transport in a highly coordinated manner, and aberrant co-ordination causes swallowing disorders (dysphagia). In this work, an in vitro model of swallowing was designed to investigate the role of rheology in swallowing and for use as a pre-clinical tool for simulation of different routes to dysphagia. The model is based on the geometry of the human pharynx. Manometry is used for pressure measurements and ultrasonic analysis is performed to analyze the flow profiles and determine shear rate in the bolus, the latter being vital information largely missing in literature. In the fully automated model, bolus injection, epiglottis/nasopharynx movement, and ultrasound transducer positioning can be controlled. Simulation of closing of the airways and nasal cavity is modulated by the software, as is a clamping valve that simulates the upper esophageal sphincter. The actions can be timed and valves opened to different degrees, resembling pathologic swallowing conditions. To validate measurements of the velocity profile and manometry, continuous and bolus flow was performed. The respective velocity profiles demonstrated the accuracy and validity of the flow characterization necessary for determining bolus flow. A maximum bolus shear rate of 80 s-1 was noted for syrup-consistency fluids. Similarly, the manometry data acquired compared very well with clinical studies.
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Affiliation(s)
- M Stading
- Agrifood and Bioscience Product Design and Perception, RISE Research Institutes of Sweden AB, Göteborg, Sweden. .,Department of Industrial and Material Sciences, Chalmers University of Technology, Göteborg, Sweden.
| | - M Q Waqas
- Agrifood and Bioscience Product Design and Perception, RISE Research Institutes of Sweden AB, Göteborg, Sweden.,Department of Industrial and Material Sciences, Chalmers University of Technology, Göteborg, Sweden
| | - F Holmberg
- Animato Konstruktions AB, Domsjö, Sweden
| | - J Wiklund
- Agrifood and Bioscience Product Design and Perception, RISE Research Institutes of Sweden AB, Göteborg, Sweden
| | - R Kotze
- Agrifood and Bioscience Product Design and Perception, RISE Research Institutes of Sweden AB, Göteborg, Sweden
| | - O Ekberg
- Diagnostic Centre of Imaging and Functional Medicine, Skåne University Hospital, Lund University, Malmö, Sweden
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28
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Weaver JE, Hong H, Ducoste JJ, de Los Reyes FL. Controlling aerobic biological floc size using Couette-Taylor Bioreactors. Water Res 2018; 147:177-183. [PMID: 30308376 DOI: 10.1016/j.watres.2018.09.060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 09/28/2018] [Accepted: 09/29/2018] [Indexed: 06/08/2023]
Abstract
Biological floc size is an important reactor microenvironment parameter that is often not experimentally controlled due to a lack of suitable methods. Here, we introduce the Couette-Taylor bioreactor (CTB) as an improved tool for controlling biological floc size, specifically as compared with bubble-column sequencing batch reactors (SBRs). A CTB consists of two concentric walls, either of which may be rotated to induce fluid motion. The induced flow produces hydrodynamic shear which is more uniform than that produced through aeration in SBRs. Because hydrodynamic shear is a major parameter controlling floc size, we hypothesized the ability to better control shear rates within a CTB would enable better-controlled floc sizes. To test this hypothesis, we measured the particle size distributions of activated sludge flocs from CTBs with either inner (iCTB) or outer (oCTB) rotating walls as well as SBRs with varying height to diameter ratios (0.5, 1.1, and 9.4). The rotation speed of the CTBs and aeration rate of the SBRs were varied to produce predicted mean shear rates from 25 to 250 s-1. Further, the shear rate distributions for each experiment were estimated using computational fluid dynamics (CFD). In all SBR experiments, the floc distributions did not significantly vary with shear rate or geometry, likely because shear rates (estimated by CFD) differed much less than originally predicted by theory. In the CTB experiments, the mean particle size decreased proportionally with increased hydrodynamic shear, and iCTBs produced particle size distributions with smaller coefficients of variation than oCTBs (0.3 vs. 0.5-0.7, respectively).
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29
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Lasch M, Nekolla K, Klemm AH, Buchheim JI, Pohl U, Dietzel S, Deindl E. Estimating hemodynamic shear stress in murine peripheral collateral arteries by two-photon line scanning. Mol Cell Biochem 2018; 453:41-51. [PMID: 30128948 DOI: 10.1007/s11010-018-3430-9] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/16/2018] [Indexed: 12/20/2022]
Abstract
Changes in wall shear stress of blood vessels are assumed to be an important component of many physiological and pathophysiological processes. However, due to technical limitations experimental in vivo data are rarely available. Here, we investigated two-photon excitation fluorescence microscopy as an option to measure vessel diameter as well as blood flow velocities in a murine hindlimb model of arteriogenesis (collateral artery growth). Using line scanning at high frequencies, we measured the movement of blood cells along the vessel axis. We found that peak systolic blood flow velocity averaged 9 mm/s and vessel diameter 42 µm in resting collaterals. Induction of arteriogenesis by femoral artery ligation resulted in a significant increase in centerline peak systolic velocity after 1 day with an average of 51 mm/s, whereas the averaged luminal diameter of collaterals (52 µm) changed much less. Thereof calculations revealed a significant fourfold increase in hemodynamic wall shear rate. Our results indicate that two-photon line scanning is a suitable tool to estimate wall shear stress e.g., in experimental animal models, such as of arteriogenesis, which may not only help to understand the relevance of mechanical forces in vivo, but also to adjust wall shear stress in ex vivo investigations on isolated vessels as well as cell culture experiments.
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Affiliation(s)
- Manuel Lasch
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistr.15, 81377, Munich, Germany.,Department of Otorhinolaryngology, Head & Neck Surgery, Klinikum der Universität München, Ludwig- Maximilians-Universität München, Munich, Germany
| | - Katharina Nekolla
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistr.15, 81377, Munich, Germany
| | - Anna H Klemm
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistr.15, 81377, Munich, Germany.,Core Facility Bioimaging at the Biomedical Center, LMU Munich, Planegg-Martinsried, Germany
| | - Judith-Irina Buchheim
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistr.15, 81377, Munich, Germany.,Department of Anesthesiology, Laboratory for Stress and Immunity, Hospital of the University of the LMU Munich, Munich, Germany
| | - Ulrich Pohl
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistr.15, 81377, Munich, Germany.,Core Facility Bioimaging at the Biomedical Center, LMU Munich, Planegg-Martinsried, Germany.,German Center for Cardiovascular Research, Partner Site Munich Heart Alliance, Munich, Germany
| | - Steffen Dietzel
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistr.15, 81377, Munich, Germany.,Core Facility Bioimaging at the Biomedical Center, LMU Munich, Planegg-Martinsried, Germany
| | - Elisabeth Deindl
- Walter-Brendel-Centre of Experimental Medicine, University Hospital, LMU Munich, Marchioninistr.15, 81377, Munich, Germany.
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30
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Wang Z, Nan J, Ji X, Yang Y. Effect of the micro-flocculation stage on the flocculation/sedimentation process: The role of shear rate. Sci Total Environ 2018; 633:1183-1191. [PMID: 29758870 DOI: 10.1016/j.scitotenv.2018.03.286] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/03/2018] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
Dynamic analysis on the variation of particle size distribution (PSD) and the fractal characteristics of PSD (Df) were investigated to better understand the continuous procedure of the floc growth and optimize the control of flocculation process. It was found that the flocculation process could be divided into three stages, i.e., the micro-flocculation stage, the growth stage and the steady (or breakage) stage. As the stage which is crucial to the morphology of micro-flocs (the building blocks of large flocs), the micro-flocculation stage plays an important role on flocculation/sedimentation process. The results showed that an increase in shear rate (11s-1<G<30s-1) during the micro-flocculation stage contributed to micro-flocs with larger size and more compact structure. As shear rate further increased (30s-1<G<55s-1), the micro-floc average size gently decreased from 13.61μm to 10.91μm, whereas two-dimension fractal dimension of micro-flocs gradually increased from 1.85 to 1.89. This indicated that further increase of shear rate during the micro-flocculation was incline to the formation of smaller micro-flocs with more compact structure. According to the results of final floc properties, the moderate shear rate (G=30s-1) benefited to the micro-floc formation to form final flocs with desired properties, further improved the treatment efficiency in the whole process. Based on the kinetics in the micro-flocculation stage, a conceptual model was proposed to describe the micro-floc growth under different shear rates, further revealed the reason for the different properties of final flocs under various shear rate during the micro-flocculation stage. Combining the results with model, it was concluded that shear rate during the micro-flocculation stage mainly affected final flocs by the domination of micro-floc structure. This research gives indications both for theoretical and actual works to improve the efficiency in the solid/liquid process.
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Affiliation(s)
- Zhenbei Wang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China
| | - Jun Nan
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China.
| | - Xiaoyu Ji
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China
| | - Yueming Yang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, People's Republic of China
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31
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Nowicki A, Trawinski Z, Gambin B, Secomski W, Szubielski M, Parol M, Olszewski R. 20-MHz Ultrasound for Measurements of Flow-Mediated Dilation and Shear Rate in the Radial Artery. Ultrasound Med Biol 2018; 44:1187-1197. [PMID: 29598961 DOI: 10.1016/j.ultrasmedbio.2018.02.011] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 02/14/2018] [Accepted: 02/22/2018] [Indexed: 06/08/2023]
Abstract
A high-frequency scanning system consisting of a 20-MHz linear array transducer combined with a 20-MHz pulsed Doppler probe was introduced to evaluate the degree of radial artery flow-mediated dilation (FMD [%]) in two groups of patients after 5 min of controlled forearm ischemia followed by reactive hyperemia. In group I, comprising 27 healthy volunteers, FMD (mean ± standard deviation) was 15.26 ± 4.90% (95% confidence interval [CI]: 13.32%-17.20%); in group II, comprising 17 patients with chronic coronary artery disease, FMD was significantly less at 4.53 ± 4.11% (95% CI: 2.42%-6.64%). Specifically, the ratio FMD/SR (mean ± standard deviation), was equal to 5.36 × 10-4 ± 4.64 × 10-4 (95% CI: 3.54 × 10-4 to 7.18 × 10-4) in group I and 1.38 × 10-4 ± 0.89 × 10-4 (95% CI: 0.70 × 10-4 to 2.06 × 10-4) in group II. Statistically significant differences between the two groups were confirmed by a Wilcoxon-Mann-Whitney test for both FMD and FMD/SR (p <0.01). Areas under receiver operating characteristic curves for FMD and FMD/SR were greater than 0.9. The results confirm the usefulness of the proposed measurements of radial artery FMD and SR in differentiation of normal patients from those with chronic coronary artery disease.
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Affiliation(s)
- Andrzej Nowicki
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland.
| | - Zbigniew Trawinski
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland
| | - Barbara Gambin
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland
| | - Wojciech Secomski
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland
| | | | - Marzena Parol
- The John Paul II Western Hospital in Grodzisk Mazowiecki, Grodzisk Mazowiecki, Poland
| | - Robert Olszewski
- Department of Ultrasound, Institute of the Fundamental Technological Research of the Polish Academy of Sciences, Warsaw, Poland; Department of Geriatrics National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland
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32
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Moruzzi RB, de Oliveira AL, da Conceição FT, Gregory J, Campos LC. Fractal dimension of large aggregates under different flocculation conditions. Sci Total Environ 2017; 609:807-814. [PMID: 28768213 DOI: 10.1016/j.scitotenv.2017.07.194] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/21/2017] [Accepted: 07/21/2017] [Indexed: 06/07/2023]
Abstract
The two-dimensional fractal dimension (Df) of large aggregates of kaolin (>540μm) during the shear flocculation process for kaolin solution was investigated using non-intrusive in situ image-based acquisition system. Separate experiments were also carried out for three different sized sub-ranges of large aggregates (0.540-1.125mm; 1.125-1.750mm; 1.750-2.375mm). Digital images were taken at a frequency of 10Hz for 10s for each different pairs of gradients of velocity (Gf) of 20 and 60s-1 and flocculation times of 2; 3; 4; 5; 10; 20; 30; 60; 120 and 180min. For the same conditions, particle size distribution (PSD) was also determined. Under the investigated conditions, the lowest Gf produced the greatest Df (1.69) at a flocculation time of 30min for the whole range of aggregates. Also, the evolution of the longest length of aggregate (l) and Df with time, showed that the dynamic steady-state was reached at different times for each shear rate and l ranges. However, Df varied for each size sub-range (ca. 1.1 to 1.8). Finally, the behavior of the aggregate structure may be understood by the predominance of different aggregation mechanisms such as cluster-cluster for Gf of 60s-1 and particle-cluster for Gf of 20s-1.
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Affiliation(s)
- Rodrigo B Moruzzi
- Universidade Estadual Paulista (UNESP), Instituto de Geociências e Ciências Exatas, Brazil.
| | - André L de Oliveira
- Universidade Estadual Paulista (UNESP), Instituto de Geociências e Ciências Exatas, Brazil
| | - Fabiano T da Conceição
- Universidade Estadual Paulista (UNESP), Instituto de Geociências e Ciências Exatas, Brazil
| | - John Gregory
- Department of Civil, Environmental and Geomatic Engineering, University College London, United Kingdom
| | - Luiza C Campos
- Department of Civil, Environmental and Geomatic Engineering, University College London, United Kingdom
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33
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Sokhal KS, Gangacharyulu D, Bulasara VK. Effect of guar gum and salt concentrations on drag reduction and shear degradation properties of turbulent flow of water in a pipe. Carbohydr Polym 2017; 181:1017-1025. [PMID: 29253926 DOI: 10.1016/j.carbpol.2017.11.048] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 10/28/2017] [Accepted: 11/14/2017] [Indexed: 10/18/2022]
Abstract
Concentrated solutions of guar gum in water (1000-3000ppm) with and without KCl salt (1000-4000ppm) were injected near the wall for a short period (2.5min) to investigate their effect on drag reduction in turbulent flow of water through a pipe (Re≈17000-45000). Relative to bulk solution, the concentrations of polymer and salt were 50-150ppm and 50-200ppm, respectively. A drag reduction of 71.45% was observed for 3000ppm of biopolymer without salt. Guar gum experienced mechanical degradation under high shear conditions and addition of KCl improved shear stability up to 47% (for Re≈45000). A polymer concentration of 3000ppm and salt concentration of 2000ppm in the injection fluid were found to be optimum for achieving the highest drag reduction with better shear stability. Results indicated that boundary layer injection shows better drag reduction ability than pre-mixed solutions.
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Affiliation(s)
- Kamaljit Singh Sokhal
- Department of Chemical Engineering, Thapar University, Patiala, Punjab, 147004, India.
| | | | - Vijaya Kumar Bulasara
- Department of Chemical Engineering, Thapar University, Patiala, Punjab, 147004, India.
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34
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Hodges GJ, Stewart DG, Davison PJ, Cheung SS. The role of shear stress on cutaneous microvascular endothelial function in humans. Eur J Appl Physiol 2017; 117:2457-68. [PMID: 28986690 DOI: 10.1007/s00421-017-3732-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/30/2017] [Indexed: 12/31/2022]
Abstract
PURPOSE Previous studies suggest that exercise and heat stress improve cutaneous endothelial function, caused by increases in shear stress. However, as vasodilatation in the skin is primarily a thermogenic phenomenon, we investigated if shear stress alone without increases in skin temperature that occur with exercise and heat stress increases endothelial function. We examined the hypothesis that repeated bouts of brief occlusion would improve cutaneous endothelial function via shear stress-dependent mechanisms. METHODS Eleven males underwent a shear stress intervention (forearm occlusion 5 s rest 10 s) for 30 min, five times·week-1 for 6 weeks on one arm, the other was an untreated control. Skin blood flow was measured using laser-Doppler flowmetry, and endothelial function was assessed with and without NOS-inhibition with L-NAME in response to three levels of local heating (39, 42, and 44 °C), ACh administration, and reactive hyperaemia. Data are cutaneous vascular conductance (CVC, laser-Doppler/blood pressure). RESULTS There were no changes in the control arm (all d ≤ 0.2, p > 0.05). In the experimental arm, CVC to 39 °C was increased after 3 and 6 weeks (d = 0.6; p ≤ 0.01). Nitric oxide contribution was increased after 6 weeks compared to baseline (d = 0.85, p < 0.001). Following skin heating to 42 °C and 44 °C, CVC was not different at weeks 3 or 6 (d ≤ 0.8, p > 0.05). For both 42 and 44 °C, nitric oxide contribution was increased after weeks 3 and 6 (d ≥ 0.4, p < 0.03). Peak and area-under-the-curve responses to ACh increased following 6 weeks (p < 0.001). CONCLUSIONS Episodic increases in shear stress, without changes in skin or core temperature, elicit an increase in cutaneous microvascular reactivity and endothelial function.
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Moradkhani H, Izadkhah MS, Anarjan N, Abdi A. Oxygen mass transfer and shear stress effects on Pseudomonas putida BCRC 14365 growth to improve bioreactor design and performance. Environ Sci Pollut Res Int 2017; 24:22427-22441. [PMID: 28803423 DOI: 10.1007/s11356-017-9827-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 07/24/2017] [Indexed: 06/07/2023]
Abstract
In this work, the experimental evidence is presented for two basic issues including oxygen mass transfer and shear analysis on the microorganism containing medium on the most prominent sections of the bioreactor. Computational fluid dynamics (CFD) methodology reproduces shear rate values for specific impeller designs using the commercial code (Fluent 6.2). CFD calculates volumetric mass transfer coefficient based on the Higbie's penetration theory. Four types of impeller are used. The spherical probe is used to measure flow hydrodynamic parameters to obtain shear rate by electro-diffusion (ED) method. The obtained results are validated experimentally and it is shown that a fully axial pattern impeller represents more enhanced results than partially axial and radial. In this regard, experimental results for volumetric oxygen mass transfer coefficient (k l a) confirm CFD predictions by acceptable deviations of 2.65, 8.90, and 9.20 for 0.15, 0.2, and 0.3 VVM, respectively. These results collaboratively indicate that LIGHTNIN-C 200 type operates more efficiently by reflecting the flow to the bottom corner stagnation areas with the minimum tolerable shear and the most velocity distribution uniformity. Furthermore, the values of k l a improve by aeration rate. Conversely, increasing the rotational speed of impeller creates difficulties for cell growth due to the generated harsh shear condition. CFD provide a better understanding of how operational and geometrical variables may be manipulated to achieve a moderate shear rate and acceptable level of mass transfer.
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Affiliation(s)
- Hamed Moradkhani
- Environmental Engineering Research Center (EERC), Faculty of Chemical Engineering, Sahand University of Technology, P.O. Box 513551996, Sahand New Town, Tabriz, Iran.
| | - Mir-Shahabeddin Izadkhah
- Department of Chemical and Petroleum Engineering, University of Tabriz, P.O. Box 5166616471, Tabriz, Iran
| | - Navideh Anarjan
- Department of Chemical Engineering, Tabriz Branch, Islamic Azad University, P.O. Box 5157944533, Tabriz, Iran
| | - Abolfazl Abdi
- Department of Chemical and Petroleum Engineering, University of Tabriz, P.O. Box 5166616471, Tabriz, Iran
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Mouser JG, Dankel SJ, Jessee MB, Mattocks KT, Buckner SL, Counts BR, Loenneke JP. A tale of three cuffs: the hemodynamics of blood flow restriction. Eur J Appl Physiol 2017; 117:1493-9. [PMID: 28501908 DOI: 10.1007/s00421-017-3644-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/09/2017] [Indexed: 10/19/2022]
Abstract
INTRODUCTION The blood flow response to relative levels of blood flow restriction (BFR) across varying cuff widths is not well documented. With the variety of cuff widths and pressures reported in the literature, the effects of different cuffs and pressures on blood flow require investigation. PURPOSE To measure blood pressure using three commonly used BFR cuffs, examine possible venous/arterial restriction pressures, and measure hemodynamic responses to relative levels of BFR using these same cuffs. METHODS 43 participants (Experiment 1, brachial artery blood pressure assessed) and 38 participants (Experiment 2, brachial artery blood flow assessed using ultrasound, cuff placed at proximal portion of arm) volunteered for this study. RESULTS Blood pressure measurement was higher in the 5 cm cuff than in the 10 and 12 cm cuffs. Sub-diastolic relative pressures appear to occur predominantly at <60% of arterial occlusion pressure (AOP). Blood flow under relative levels of restriction decreases in a non-linear fashion, with minimal differences between cuffs [resting: 50.3 (44.2) ml min-1; 10% AOP: 42.0 (36.8); 20%: 33.6 (28.6); 30%: 23.6 (20.4); 40%: 17.1 (15.9); 50%: 12.5 (9.4); 60%: 11.5 (8.1); 70%: 11.4 (7.0); 80%: 10.3 (6.3); 90%: 7.9 (4.8); 100%: 1.5 (2.9)]. Peak blood velocity remains relatively constant until higher levels (>70% of AOP) are surpassed. Calculated mean shear rate decreases in a similar fashion as blood flow. CONCLUSIONS Under relative levels of restriction, pressures from 40 to 90% of AOP appear to decrease blood flow to a similar degree in these three cuffs. Relative pressures appear to elicit a similar blood flow stimulus when accounting for cuff width and participant characteristics.
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Casey DP, Schneider AC, Ueda K. Influence of chronic endurance exercise training on conduit artery retrograde and oscillatory shear in older adults. Eur J Appl Physiol 2016; 116:1931-40. [PMID: 27497720 DOI: 10.1007/s00421-016-3445-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/26/2016] [Indexed: 01/12/2023]
Abstract
PURPOSE With aging, there tends to be an increase in retrograde and oscillatory shear in peripheral conduit arteries of humans. Whether the increase in shear rate is due to the aging process or an effect of a less active lifestyle that often accompanies aging is unknown. Therefore, we examined whether chronic endurance exercise training attenuates conduit artery retrograde and oscillatory shear in older adults. METHODS Brachial and common femoral artery mean blood velocities and diameter were determined via Doppler ultrasound under resting conditions, and shear rate was calculated in 13 young (24 ± 2 years), 17 older untrained (66 ± 3 years), and 16 older endurance exercise-trained adults (66 ± 7 years). RESULTS Brachial artery retrograde (-9.1 ± 6.4 vs. -12.6 ± 9.4 s(-1); P = 0.35) and oscillatory (0.14 ± 0.08 vs. 0.14 ± 0.08 arbitrary units; P = 0.99) shear were similar between the older trained and untrained groups, whereas brachial artery retrograde and oscillatory shear were greater in older untrained compared to young adults (-5.0 ± 3.4, 0.08 ± 0.05 s(-1) arbitrary units, P = 0.017 and 0.048, respectively). There was no difference between the young and older trained brachial retrograde (P = 0.29) and oscillatory (P = 0.07) shear. Common femoral artery retrograde (-6.3 ± 2.9 s(-1)) and oscillatory (0.21 ± 0.08 arbitrary units) shear were reduced in older trained compared to the older untrained group (-10.4 ± 4.1 and 0.30 ± 0.09 s(-1) arbitrary units, both P = 0.005 and 0.006, respectively), yet similar to young adults (-7.1 ± 3.5 and 0.19 ± 0.06 s(-1) arbitrary units, P = 0.81 and 0.87, respectively). CONCLUSION Our results suggest that chronic endurance exercise training in older adults ameliorates retrograde and oscillatory shear rate patterns, particularly in the common femoral artery.
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Affiliation(s)
- Darren P Casey
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USA. .,Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USA. .,Fraternal Order of Eagles Diabetes Research, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USA.
| | - Aaron C Schneider
- Department of Health and Human Physiology, University of Iowa, Iowa, IA, 52242, USA
| | - Kenichi Ueda
- Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USA
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Ghobadi N, Ogino C, Yamabe K, Ohmura N. Characterizations of the submerged fermentation of Aspergillus oryzae using a Fullzone impeller in a stirred tank bioreactor. J Biosci Bioeng 2016; 123:101-108. [PMID: 27475924 DOI: 10.1016/j.jbiosc.2016.07.001] [Citation(s) in RCA: 4] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 06/07/2016] [Accepted: 07/01/2016] [Indexed: 11/29/2022]
Abstract
A Fullzone (FZ) impeller was used in the first study of the characteristics involved in the fermentation of Aspergillus oryzae. Both the experimental and simulation results of this study revealed novel findings into the positive relationship between the global-axial mixing patterns of a FZ impeller and fermentation efficiency. The mixing results when using the FZ impeller compared with a double Rushton turbine (DRT) impeller indicated that the culture mixed by the FZ resulted in a more homogeneous medium with higher values for oxygen mass transfer, cell growth rate, and alpha amylase activity. The simulation of fluid flow was done in a laminar regime using a two-fluid model. According to the simulation results, the maximum shear stress when using the DRT was higher than that with the FZ at the same power input (Pin). A high degree of local shear stress and the shear rate near the turbine blade of the DRT resulted in cell damage and a reduction in the enzyme activity, biomass, pellet diameter, and dissolved oxygen concentration. Calculations using the Brown equation showed that the maximum and average shear rates during mixing with the FZ impeller were lower than that when using the DRT. Therefore, the use of an FZ impeller, particularly at low Pin, enhanced the cultivation of A. oryzae.
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Affiliation(s)
- Narges Ghobadi
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
| | - Chiaki Ogino
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan
| | - Kaoru Yamabe
- Division of Process Equipment, Kobelco Eco-Solutions, Co., Ltd., 19 Nijima, Harimacho, Kakogun, Hyogo 675-0155, Japan
| | - Naoto Ohmura
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan.
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Rabani A, Pinfield VJ, Challis RE. Rate of shear of an ultrasonic oscillating rod viscosity probe. Ultrasonics 2016; 65:18-22. [PMID: 26409767 DOI: 10.1016/j.ultras.2015.08.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 08/27/2015] [Accepted: 08/31/2015] [Indexed: 06/05/2023]
Abstract
Ultrasonic oscillating rod probes have recently been used by researchers to measure viscosity and/or density in fluids. However, in order to use such probes to characterise the rheological properties of fluids, it is necessary to define the shear rate produced by the probe. This paper proposes an analytical solution to estimate the shear rate of ultrasonic oscillating rod viscosity probes and a method to measure their maximum operational shear rate. A relationship is developed which relates the torsional surface velocity of an oscillating cylindrical rigid body to the rate of shear in its vicinity. The surface displacement and torsional surface velocity of a torsional probe of length 1000 mm and diameter 1mm were measured over the frequency range from 525 to 700 kHz using a laser interferometer and the maximum shear rate estimated. The reported work provides the basis for characterising shear rate for such probes, enabling their application for rheological investigations.
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Affiliation(s)
- A Rabani
- Department of Mechanical, Materials and Manufacturing Engineering, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
| | - V J Pinfield
- Department of Chemical Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK
| | - R E Challis
- Department of Electrical and Electronic Engineering, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK
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Zhang P, Liu X, Sun A, Fan Y, Deng X. Hemodynamic insight into overlapping bare-metal stents strategy in the treatment of aortic aneurysm. J Biomech 2015; 48:2041-6. [PMID: 25911250 DOI: 10.1016/j.jbiomech.2015.03.028] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 03/18/2015] [Accepted: 03/22/2015] [Indexed: 10/23/2022]
Abstract
Clinical trials have shown overlapping bare-metal stents provoke effective thrombus clot within the aneurysm sac and shrinkage of the aneurysm by directly regulating the hemodynamics. To gain insight into the hemodynamic mechanism of the technique, three cases of simplified thoracic aortic aneurysm models (with no stent, a single stent and two overlapped stents deployed within the aneurysm sac) were studied and compared in terms of time-varying velocity and shear rate, time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and relative residence time (RRT). The results demonstrated that the overlapping stents' strategy was more effective in reducing the velocity of blood flow within the aneurysm, especially for the area near the aneurysm wall. Stenting induced a dramatic change trend of shear rate during the cardiac cycle, in which a very high shear rate (>10,000 s(-1)) during the systole and a quite low shear rate (<1000 s(-1)) during the diastole were observed, respectively. Moreover, reduced TAWSS and OSI and elevated RRT values were observed on the aneurysm wall after stent placement. The effects of stenting on the shear rate, TAWSS, OSI and RRT in the aneurysm would be significantly enhanced by two overlapped stents. The present findings therefore indicated that, the overlapping bare-metal stents can isolate the aneurysm effectively and may create a favorable hemodynamic environment provoking platelets activation and aggregation within the aneurysm, which may promote thrombus formation/growth there, hence contribute to degradation of the aneurysm.
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Affiliation(s)
- Peng Zhang
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiao Liu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China.
| | - Anqiang Sun
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Yubo Fan
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiaoyan Deng
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China.
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Binoy D, Sajjan GS, Peddireddi S, Kumar MSR, Bhavana V, Raju SR. A Comparitive Evaluation of Sealing Ability, pH and Rheological Properties of Zinc Oxide Eugenol Sealer Combined with Different Antibiotics: An In Vitro Study. J Clin Diagn Res 2015; 8:ZC05-8. [PMID: 25584296 DOI: 10.7860/jcdr/2014/8398.5095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 09/03/2014] [Indexed: 11/24/2022]
Abstract
AIM The objective of this study was to evaluate and compare the sealing ability, pH & viscosity of Zinc oxide eugenol sealer mixed with different antibiotics (Amoxicillin, Ciprofloxacin, Clindamycin and Doxycycline). MATERIALS AND METHODS Ninety single rooted anterior teeth were randomly divided into four experimental groups of 15 teeth each and 3 control groups of 10 each. Sealer-antibiotic combination was used as a sealer in experimental group. Teeth were sectioned longitudinally to assess linear dye penetration. pH and viscosity of the experimental groups were evaluated with Elico pH Meter and Brook Field Viscometer respectively. RESULTS (Amoxicillin+ ZOE) Group II and (Clindamycin + ZOE) Group IV have shown minimum linear dye leakage of 1.07mm & 1.22 mm respectively & (Ciprofloxacin + ZOE) Group III and (Doxycycline + ZOE) Group V 2.69 mm & 2.59 mm respectively. There was decrease in the viscosity of the experimental group. pH was found to be 8.55 for Group II sealer which was greater than control group. CONCLUSION Amoxicillin and sealer combination can improve the success rate of endodontic therapy by enhancing the antimicrobial activity, alkaline environment and reducing apical microleakage.
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Affiliation(s)
- D Binoy
- Senior Lecturer, Department of Conservative Dentistry and Endodontics, Sri Sai College Of Dental Surgery , Vikarabad, Telangana, India
| | - Girija S Sajjan
- Professor & Head, Department of Conservative Dentistry and Endodontics, Vishnu Dental College , Bhimavaram, Andhra Pradesh, India
| | - Suresh Peddireddi
- Senior Lecturer, Department of Conservative Dentistry and Endodontics, Lenora Dental College , Rajamundry, Andhra Pradesh, India
| | - M Sita Rama Kumar
- Senior Lecturer, Department of Conservative Dentistry and Endodontics, Vishnu Dental College , Bhimavaram, Andhra Pradesh, India
| | - V Bhavana
- Senior Lecturer, Department of Conservative Dentistry and Endodontics, Sri Sai College Of Dental Surgery , Vikarabad, Telangana, India
| | - Sita Rama Raju
- Senior Lecturer, Department of Conservative Dentistry and Endodontics, Vishnu Dental College , Bhimavaram, Andhra Pradesh, India
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Badve MP, Alpar T, Pandit AB, Gogate PR, Csoka L. Modeling the shear rate and pressure drop in a hydrodynamic cavitation reactor with experimental validation based on KI decomposition studies. Ultrason Sonochem 2015; 22:272-7. [PMID: 24924259 DOI: 10.1016/j.ultsonch.2014.05.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 05/22/2014] [Accepted: 05/22/2014] [Indexed: 05/14/2023]
Abstract
A mathematical model describing the shear rate and pressure variation in a complex flow field created in a hydrodynamic cavitation reactor (stator and rotor assembly) has been depicted in the present study. The design of the reactor is such that the rotor is provided with surface indentations and cavitational events are expected to occur on the surface of the rotor as well as within the indentations. The flow characteristics of the fluid have been investigated on the basis of high accuracy compact difference schemes and Navier-Stokes method. The evolution of streamlining structures during rotation, pressure field and shear rate of a Newtonian fluid flow have been numerically established. The simulation results suggest that the characteristics of shear rate and pressure area are quite different based on the magnitude of the rotation velocity of the rotor. It was observed that area of the high shear zone at the indentation leading edge shrinks with an increase in the rotational speed of the rotor, although the magnitude of the shear rate increases linearly. It is therefore concluded that higher rotational speeds of the rotor, tends to stabilize the flow, which in turn results into less cavitational activity compared to that observed around 2200-2500RPM. Experiments were carried out with initial concentration of KI as 2000ppm. Maximum of 50ppm of iodine liberation was observed at 2200RPM. Experimental as well as simulation results indicate that the maximum cavitational activity can be seen when rotation speed is around 2200-2500RPM.
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Affiliation(s)
- Mandar P Badve
- Department of Chemical Engineering, Institute of Chemical Technology, Mumbai 400 019, India
| | - Tibor Alpar
- University of West Hungary, Institute of Wood Based Products and Technologies, 9400 Sopron, Hungary
| | - Aniruddha B Pandit
- Department of Chemical Engineering, Institute of Chemical Technology, Mumbai 400 019, India
| | - Parag R Gogate
- Department of Chemical Engineering, Institute of Chemical Technology, Mumbai 400 019, India.
| | - Levente Csoka
- University of West Hungary, Institute of Wood Based Products and Technologies, 9400 Sopron, Hungary.
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Al Ashhab A, Gillor O, Herzberg M. Biofouling of reverse-osmosis membranes under different shear rates during tertiary wastewater desalination: microbial community composition. Water Res 2014; 67:86-95. [PMID: 25262553 DOI: 10.1016/j.watres.2014.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 09/04/2014] [Accepted: 09/06/2014] [Indexed: 06/03/2023]
Abstract
We investigated the influence of feed-water shear rate during reverse-osmosis (RO) desalination on biofouling with respect to microbial community composition developed on the membrane surface. The RO membrane biofilm's microbial community profile was elucidated during desalination of tertiary wastewater effluent in a flat-sheet lab-scale system operated under high (555.6 s(-1)), medium (370.4 s(-1)), or low (185.2 s(-1)) shear rates, corresponding to average velocities of 27.8, 18.5, and 9.3 cm s(-1), respectively. Bacterial diversity was highest when medium shear was applied (Shannon-Weaver diversity index H' = 4.30 ± 0.04) compared to RO-membrane biofilm developed under lower and higher shear rates (H' = 3.80 ± 0.26 and H' = 3.42 ± 0.38, respectively). At the medium shear rate, RO-membrane biofilms were dominated by Betaproteobacteria, whereas under lower and higher shear rates, the biofilms were dominated by Alpha- and Gamma- Proteobacteria, and the latter biofilms also contained Deltaproteobacteria. Bacterial abundance on the RO membrane was higher at low and medium shear rates compared to the high shear rate: 8.97 × 10(8) ± 1.03 × 10(3), 4.70 × 10(8) ± 1.70 × 10(3) and 5.72 × 10(6) ± 2.09 × 10(3) copy number per cm(2), respectively. Interestingly, at the high shear rate, the RO-membrane biofilm's bacterial community consisted mainly of populations known to excrete high amounts of extracellular polymeric substances. Our results suggest that the RO-membrane biofilm's community composition, structure and abundance differ in accordance with applied shear rate. These results shed new light on the biofouling phenomenon and are important for further development of antibiofouling strategies for RO membranes.
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Affiliation(s)
- Ashraf Al Ashhab
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 84990, Israel.
| | - Osnat Gillor
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 84990, Israel.
| | - Moshe Herzberg
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 84990, Israel.
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Chen H, Ma C, Yang GF, Wang HZ, Yu ZM, Jin RC. Floatation of flocculent and granular sludge in a high-loaded anammox reactor. Bioresour Technol 2014; 169:409-415. [PMID: 25069095 DOI: 10.1016/j.biortech.2014.06.063] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Revised: 06/16/2014] [Accepted: 06/18/2014] [Indexed: 06/03/2023]
Abstract
The floatation of flocculent and granular sludge was investigated in this study. An anaerobic ammonium oxidation (anammox) upflow anaerobic sludge blanket (UASB) reactor was operated for 665 days. During this time, the maximum nitrogen removal rate was 52.6 kg Nm(-3) d(-1). Floccule floatation occurred between days 100 and 140, which potentially resulted from the sudden increase in gas yield and the poor settling ability of the floccules. Increasing the shear rate from 0.084 to 0.135 s(-1) was effective at eliminating floccule floatation. In addition, granule floatation occurred between days 572 and 665, which likely resulted from the formation of hollows within the granules. Floatation may be effectively prevented by maintaining a shear rate of more than 0.778 s(-1). Furthermore, the mechanisms of granule floatation and the floatation processes were proposed. Overall, controlling the shear force may effectively overcome sludge floatation.
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Affiliation(s)
- Hui Chen
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China
| | - Chun Ma
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China
| | - Guang-Feng Yang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China
| | - Hui-Zhong Wang
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Zhi-Ming Yu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China
| | - Ren-Cun Jin
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China; Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036, China.
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Yeom E, Nam KH, Paeng DG, Lee SJ. Effects of red blood cell aggregates dissociation on the estimation of ultrasound speckle image velocimetry. Ultrasonics 2014; 54:1480-7. [PMID: 24794508 DOI: 10.1016/j.ultras.2014.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 02/24/2014] [Accepted: 04/13/2014] [Indexed: 05/11/2023]
Abstract
Ultrasound speckle image of blood is mainly attributed by red blood cells (RBCs) which tend to form RBC aggregates. RBC aggregates are separated into individual cells when the shear force is over a certain value. The dissociation of RBC aggregates has an influence on the performance of ultrasound speckle image velocimetry (SIV) technique in which a cross-correlation algorithm is applied to the speckle images to get the velocity field information. The present study aims to investigate the effect of the dissociation of RBC aggregates on the estimation quality of SIV technique. Ultrasound B-mode images were captured from the porcine blood circulating in a mock-up flow loop with varying flow rate. To verify the measurement performance of SIV technique, the centerline velocity measured by the SIV technique was compared with that measured by Doppler spectrograms. The dissociation of RBC aggregates was estimated by using decorrelation of speckle patterns in which the subsequent window was shifted as much as the speckle displacement to compensate decorrelation caused by in-plane loss of speckle patterns. The decorrelation of speckles is considerably increased according to shear rate. Its variations are different along the radial direction. Because the dissociation of RBC aggregates changes ultrasound speckles, the estimation quality of SIV technique is significantly correlated with the decorrelation of speckles. This degradation of measurement quality may be improved by increasing the data acquisition rate. This study would be useful for simultaneous measurement of hemodynamic and hemorheological information of blood flows using only speckle images.
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Affiliation(s)
- Eunseop Yeom
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, South Korea
| | - Kweon-Ho Nam
- Department of Ocean System Engineering, Interdisciplinary Postgraduate Program in Biomedical Engineering, Jeju National University, Jeju, South Korea
| | - Dong-Guk Paeng
- Department of Ocean System Engineering, Interdisciplinary Postgraduate Program in Biomedical Engineering, Jeju National University, Jeju, South Korea.
| | - Sang-Joon Lee
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, South Korea.
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Thomas A, Tan J, Liu Y. Characterization of nanoparticle delivery in microcirculation using a microfluidic device. Microvasc Res 2014; 94:17-27. [PMID: 24788074 DOI: 10.1016/j.mvr.2014.04.008] [Citation(s) in RCA: 27] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 04/03/2014] [Accepted: 04/18/2014] [Indexed: 10/25/2022]
Abstract
This work focuses on the characterization of particle delivery in microcirculation through a microfluidic device. In microvasculature the vessel size is comparable to that of red blood cells (RBCs) and the existence of blood cells largely influences the dispersion and binding distribution of drug loaded particles. The geometry of the microvasculature leads to non-uniform particle distribution and affects the particle binding characteristics. We perform an in vitro study in a microfluidic chip with micro vessel mimicking channels having a rectangular cross section. Various factors that influence particle distribution and delivery such as the vessel geometry, shear rate, blood cells, particle size, particle antibody density are considered in this study. Around 10% higher particle binding density is observed at bifurcation regions of the mimetic microvasculature geometry compared to straight regions. Particle binding density is found to decrease with increased shear rates. RBCs enhance particle binding for both 210 nm and 2 μm particles for shear rates between 200-1600 s(-1) studied. The particle binding density increases about 2-3 times and 6-10 times when flowing in whole blood at 25% RBC concentration compared to the pure particle case, for 210 nm and 2 μm particles respectively. With RBCs, the binding enhancement is more significant for 2 μm particles than that for 210 nm particles, which indicates an enhanced size dependent exclusion of 2 μm particles from the channel centre to the cell free layer (CFL). Increased particle antibody coating density leads to higher particle binding density for both 210 nm and 2 μm particles.
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Affiliation(s)
- Antony Thomas
- Bioengineering program, Lehigh University, Bethlehem, PA 18015, USA.
| | - Jifu Tan
- Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA.
| | - Yaling Liu
- Bioengineering program, Lehigh University, Bethlehem, PA 18015, USA; Department of Mechanical Engineering and Mechanics, Lehigh University, Bethlehem, PA 18015, USA.
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Abstract
Injury of an arterial vessel wall acutely triggers a multifaceted process of thrombus formation, which is dictated by the high-shear flow conditions in the artery. In this overview, we describe how the classical concept of arterial thrombus formation and vascular occlusion, driven by platelet activation and fibrin formation, can be extended and fine-tuned. This has become possible because of recent insight into the mechanisms of: (i) platelet-vessel wall and platelet-platelet communication, (ii) autocrine platelet activation, and (iii) platelet-coagulation interactions, in relation to blood flow dynamics. We list over 40 studies with genetically modified mice showing a role of platelet and plasma proteins in the control of thrombus stability after vascular injury. These include multiple platelet adhesive receptors and other junctional molecules, components of the ADP receptor signalling cascade to integrin activation, proteins controlling platelet shape, and autocrine activation processes, as well as multiple plasma proteins binding to platelets and proteins of the intrinsic coagulation cascade. Regulatory roles herein of the endothelium and other blood cells are recapitulated as well. Patient studies support the contribution of platelet- and coagulation activation in the regulation of thrombus stability. Analysis of the factors determining flow-dependent thrombus stabilization and embolus formation in mice will help to understand the regulation of this process in human arterial disease.
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Affiliation(s)
- Judith M E M Cosemans
- Department of Biochemistry, Cardiovascular Research Institute Maastricht , Maastricht University, PO Box 616, Maastricht 6200 MD, The Netherlands
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