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Francesco Fornarelli, Ruggiero Dadduzio, Marco Torresi, Sergio Mario Camporeale, Bernardo Fortunato
A fully 3D unsteady Computational Fluid Dynamics (CFD) approach coupled with heterogeneous reaction chemistry is presented in order to study the behavior of a single square channel as part of a Lean [Formula: see text] Traps. The reliability of the numerical tool has been validated against literature data considering only active BaO site. Even though the input/output performance of such catalyst has been well known, here the spatial distribution within a single channel is investigated in details. The square channel geometry influences the flow field and the catalyst performance being the flow velocity distribution on the cross section non homogeneous...
February 2018: Heliyon
Sarah E Sartain, Nancy A Turner, Joel L Moake
Atypical hemolytic uremic syndrome (aHUS) and bone marrow transplantation-associated thrombotic microangiopathy (TA-TMA) are associated with excessive activation of the alternative complement pathway (AP) and with severe renal - and rarely, cerebral - microvascular damage. Here, we compared AP activation and regulation in human glomerular and brain microvascular endothelial cells (GMVECs and BMVECs, respectively) unstimulated or stimulated by the proinflammatory cytokine, tumor necrosis factor (TNF). Compared with GMVECs and under both experimental conditions, BMVECs had increased gene expression of the AP-related genes C3 , CFB , and C5 , and decreased expression of CFD This was associated with increased expression in BMVECs (relative to GMVECs) of the genes for surface and soluble regulatory molecules ( CD46 , THBD , CD55 , CFI , and CFH ) suppressing formation of the AP C3 and C5 convertases...
March 19, 2018: Journal of Biological Chemistry
Jennifer Chia Wee Fern, Shuji Ohsaki, Satoru Watano, Robert Pfeffer
The synthesis of nano-size drug particles by antisolvent crystallization using a porous hollow fiber membrane provides promising benefits such as the capability of continuous operation, low energy input, and ease of scale-up for a variety of industrial processes. Porous hollow fiber membranes have also been shown to produce more efficient mixing than conventional mixing equipment mostly because in mixing binary fluids, they provide sufficient mixing time, retention time, and a large contact interface for the drug solution and the antisolvent, allowing for the precise control of nucleation and crystal growth necessary to form nano-size particles...
March 15, 2018: International Journal of Pharmaceutics
Rebecca C Gosling, Paul D Morris, Daniel A Silva Soto, Patricia V Lawford, D Rodney Hose, Julian P Gunn
OBJECTIVES: This study sought to assess the ability of a novel virtual coronary intervention (VCI) tool based on invasive angiography to predict the patient's physiological response to stenting. BACKGROUND: Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) is associated with improved clinical and economic outcomes compared with angiographic guidance alone. Virtual (v)FFR can be calculated based upon a 3-dimensional (3D) reconstruction of the coronary anatomy from the angiogram, using computational fluid dynamics (CFD) modeling...
March 9, 2018: JACC. Cardiovascular Imaging
Tsutomu Nomura, Munetaka Ushio, Kenji Kondo, Shigeru Kikuchi
OBJECTIVE: The purpose of this research is to examine the changes in nasal airflow dynamics before and after the nasal perforation repair. METHODS: Three dimensional (3D) models of the nasal cavity before and after septal perforation repair was reconstructed using preoperative and postoperative computed tomography (CT) images of a patient. The numerical simulation was carried out using ANSYS CFX V15.0. Pre- and post-operative models were compared by their velocity, pressure (P), pressure gradient (PG), wall shear (WS), shear strain rate (SSR) and turbulence kinetic energy (TKE) in three plains...
March 13, 2018: Auris, Nasus, Larynx
Chang Heon Cheong, Seonhye Lee
The prevention of airborne infections in emergency departments is a very important issue. This study investigated the effects of architectural features on airborne pathogen dispersion in emergency departments by using a CFD (computational fluid dynamics) simulation tool. The study included three architectural features as the major variables: increased ventilation rate, inlet and outlet diffuser positions, and partitions between beds. The most effective method for preventing pathogen dispersion and reducing the pathogen concentration was found to be increasing the ventilation rate...
March 13, 2018: International Journal of Environmental Research and Public Health
Cui Zhang, Liang Li, Yuanda Jiang, Cuicui Wang, Baoming Geng, Yanqiu Wang, Jianling Chen, Fei Liu, Peng Qiu, Guangjie Zhai, Ping Chen, Renfu Quan, Jinfu Wang
Bone formation is linked with osteogenic differentiation of mesenchymal stem cells (MSCs) in the bone marrow. Microgravity in spaceflight is known to reduce bone formation. In this study, we used a real microgravity environment of the SJ-10 Recoverable Scientific Satellite to examine the effects of space microgravity on the osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hMSCs). hMSCs were induced toward osteogenic differentiation for 2 and 7 d in a cell culture device mounted on the SJ-10 Satellite...
March 13, 2018: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Dong Zhang, Pengcheng Xu, Hongyu Qiao, Xin Liu, Liangping Luo, Wenhua Huang, Heye Zhang, Changzheng Shi
BACKGROUND: Cerebrovascular events are frequently associated with hemodynamic disturbance caused by internal carotid artery (ICA) stenosis. It is challenging to determine the ischemia-related carotid stenosis during the intervention only using digital subtracted angiography (DSA). Inspired by the performance of well-established FFRct technique in hemodynamic assessment of significant coronary stenosis, we introduced a pressure-based carotid arterial functional assessment (CAFA) index generated from computational fluid dynamic (CFD) simulation in DSA data, and investigated its feasibility in the assessment of hemodynamic disturbance preliminarily using pressure-wired measurement and arterial spin labeling (ASL) MRI as references...
March 12, 2018: Biomedical Engineering Online
Yong Lei Wang, Ning Wang, Ruibao Jia, Kefeng Zhang, Baozhen Liu, Wuchang Song, Junqi Jia
Countercurrent-cocurrent dissolved air flotation (CCDAF), the popular water purification device, which consists of collision and adhesion contact zones, showed favorable flotation conditions for micro-bubble adhesion and stability. In this study, computational fluid dynamics (CFD) numerical simulation was employed to confirm that the unique CCDAF configuration create reasonable and that the flow field characteristics were good no matter for single phase or gas-liquid two-phase conditions. In addition, the turbulence of the flow field was enhanced with the increasing influent load; the swirling was remarkably reduced with the increase of gas holdup...
March 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Panneerselvam Ranganathan, Sivaraman Savithri
Computational Fluid Dynamics (CFD) technique is used in this work to simulate the hydrothermal liquefaction of Nannochloropsis sp. microalgae in a lab-scale continuous plug-flow reactor to understand the fluid dynamics, heat transfer, and reaction kinetics in a HTL reactor under hydrothermal condition. The temperature profile in the reactor and the yield of HTL products from the present simulation are obtained and they are validated with the experimental data available in the literature. Furthermore, the parametric study is carried out to study the effect of slurry flow rate, reactor temperature, and external heat transfer coefficient on the yield of products...
February 21, 2018: Bioresource Technology
R A J Wain, D J Smith, D R Hammond, J P M Whitty
Arterial thrombus formation is directly related to the mechanical shear experienced by platelets within flow. High shear strain rates (SSRs) and large shear gradients cause platelet activation, aggregation and production of thrombus. This study, for the first time, investigates the influence of pulsatile flow on local haemodynamics within sutured microarterial anastomoses. We measured physiological arterial waveform velocities experimentally using Doppler ultrasound velocimetry, and a representative example was applied to a realistic sutured microarterial geometry...
March 6, 2018: Microvascular Research
Yang Wang, Ying Zhou, Jian Zuo, Raufdeen Rameezdeen
Particle emissions derived from construction activities have a significant impact on the local air quality, while the canyon effect with reduced natural ventilation contributes to the highest particulate pollution in urban environments. This study attempted to examine the effect of PM10 emissions derived from the construction of a rail transit system in an urban street canyon. Using a 3D computational fluid dynamic (CFD) model based on a real street canyon with different height ratios, this study formulates the impact of height ratio and wind directions on the dispersion and concentration of PM10 ...
March 9, 2018: International Journal of Environmental Research and Public Health
Tomoya Watanabe, Haruo Isoda, Yasuo Takehara, Masaki Terada, Takehiro Naito, Takafumi Kosugi, Yuki Onishi, Chiharu Tanoi, Takashi Izumi
PURPOSE: We performed computational fluid dynamics (CFD) for patients with and without paraclinoid internal carotid artery (ICA) aneurysms to evaluate the distribution of vascular biomarkers at the aneurysm initiation sites of the paraclinoid ICA. METHODS: This study included 35 patients who were followed up for aneurysms using 3D time of flight (TOF) magnetic resonance angiography (MRA) and 3D cine phase-contrast MR imaging. Fifteen affected ICAs were included in group A with the 15 unaffected contralateral ICAs in group B...
March 8, 2018: Neuroradiology
Federico Canè, Benedict Verhegghe, Matthieu De Beule, Philippe B Bertrand, Rob J Van der Geest, Patrick Segers, Gianluca De Santis
With cardiovascular disease (CVD) remaining the primary cause of death worldwide, early detection of CVDs becomes essential. The intracardiac flow is an important component of ventricular function, motion kinetics, wash-out of ventricular chambers, and ventricular energetics. Coupling between Computational Fluid Dynamics (CFD) simulations and medical images can play a fundamental role in terms of patient-specific diagnostic tools. From a technical perspective, CFD simulations with moving boundaries could easily lead to negative volumes errors and the sudden failure of the simulation...
2018: BioMed Research International
Jian Li, Ze-Yuan Fei, Yi-Feng Xu, Jie Wang, Bing-Feng Fan, Xue-Jin Ma, Gang Wang
Metal-organic chemical vapour deposition (MOCVD) is a key technique for fabricating GaN thin film structures for light-emitting and semiconductor laser diodes. Film uniformity is an important index to measure equipment performance and chip processes. This paper introduces a method to improve the quality of thin films by optimizing the rotation speed of different substrates of a model consisting of a planetary with seven 6-inch wafers for the planetary GaN-MOCVD. A numerical solution to the transient state at low pressure is obtained using computational fluid dynamics...
February 2018: Royal Society Open Science
Xiao Li, Chao-Qun Xu, Yu-Di Luo, Song Zhang, Cong Huang, Kun Zou, Ya-Li Tan, Ye-Xu Wu, Zhang-Shuang Deng
The computational fluid dynamics (CFD) software package Fluent was utilized to simulate the flow field of Escherichia coli (E. coli) BL21 fermentation in a 50 L automatic bioreactor for producing α-cyclodextrin glycosyltransferase (α-CGTase) in this study. 4-down-pumping propeller (4DPP), 6-curved-blade disc turbine (6CBDT), and Rushton turbine (RT) were assembled to form eight impeller combinations (C1-C8). Through flow field simulating, four referential impeller combinations, in which C6, C7, and C8 were three layers stirring blades and C1 as a control, were selected to carry out batch fermentation experiments (TC1, TC6, TC7, and TC8) for validation...
March 6, 2018: Bioprocess and Biosystems Engineering
Shuai Ren, Yan Shi, Maolin Cai, Hongmei Zhao, Zhaozhi Zhang, Xiaohua Douglas Zhang
Coughing is an irritable reaction that protects the respiratory system from infection and improves mucus clearance. However, for the patients who cannot cough autonomously, an assisted cough device is essential for mucus clearance. Considering the low efficiency of current assisted cough devices, a new simulated cough device based on the pneumatic system is proposed in this paper. Given the uncertainty of airflow rates necessary to clear mucus from airways, the computational fluid dynamics (CFD) Eulerian Wall Film (EWF) model and cough efficiency (CE) were used in this study to simulate the cough process and evaluate cough effectiveness...
March 5, 2018: International Journal for Numerical Methods in Biomedical Engineering
Shouliang Qi, Baihua Zhang, Yong Yue, Jing Shen, Yueyang Teng, Wei Qian, Jianlin Wu
Tracheal Bronchus (TB) is a rare congenital anomaly characterized by the presence of an abnormal bronchus originating from the trachea or main bronchi and directed toward the upper lobe. The airflow pattern in tracheobronchial trees of TB subjects is critical, but has not been systemically studied. This study proposes to simulate the airflow using CT image based models and the computational fluid dynamics (CFD) method. Six TB subjects and three health controls (HC) are included. After the geometric model of tracheobronchial tree is extracted from CT images, the spatial distribution of velocity, wall pressure, wall shear stress (WSS) is obtained through CFD simulation, and the lobar distribution of air, flow pattern and global pressure drop are investigated...
March 1, 2018: Journal of Medical Systems
Rainier Hreiz, Olivier Potier, Jim Wicks, Jean-Marc Commenge
In this paper, CFD simulations are employed to characterize the effects of bubble aerator layouts (i.e. spatial arrangement) on the hydrodynamics in activated sludge reactors. The first configuration considered is a channel reactor with aerators placed alongside one lateral wall, for which velocity measurements are available in literature. CFD results were in good agreement with experimental data, which proves that the model is sufficiently accurate and predictive. Accordingly, simulations and numerical residence time distribution tests were conducted for different aerator layouts to determine their effects on the reactor hydrodynamics...
March 1, 2018: Environmental Technology
Iñigo Aramendia, Unai Fernandez-Gamiz, Alberto Lopez-Arraiza, Carmen Rey-Santano, Victoria Mielgo, Francisco Jose Basterretxea, Javier Sancho, Miguel Angel Gomez-Solaetxe
Respiratory distress syndrome (RDS) represents one of the major causes of mortality among preterm infants, and the best approach to treat it is an open research issue. The use of perfluorocarbons (PFC) along with non-invasive respiratory support techniques has proven the usefulness of PFC as a complementary substance to achieve a more homogeneous surfactant distribution. The aim of this work was to study the inhaled particles generated by means of an intracorporeal inhalation catheter, evaluating the size and mass distribution of different PFC aerosols...
February 28, 2018: International Journal of Environmental Research and Public Health
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