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Journal articleKandail H, Hamady M, Xu XY, 2015,
Comparison of blood flow in branched and fenestrated stent-grafts for endovascular repair of abdominal aortic aneurysms.
, Journal of Endovascular Therapy, Vol: 22, Pages: 578-590, ISSN: 1545-1550PURPOSE: To report a computational study assessing the hemodynamic outcomes of branched stent-grafts (BSGs) for different anatomic variations. METHODS: Idealized models of BSGs and fenestrated stent-grafts (FSGs) were constructed with different visceral takeoff angles (ToA) and lateral aortic neck angles. ToA was defined as the angle between the centerlines of the main stent-graft and side branch, with 90° representing normal alignment, and 30° and 120° representing angulated side branches. Computational simulations were performed by solving the conservation equations governing the blood flow under physiologically realistic conditions. RESULTS: The largest renal flow recirculation zones (FRZs) were observed in FSGs at a ToA of 30°, and the smallest FRZ was also found in FSGs (at a ToA of 120°). For straight-neck stent-grafts with a ToA of 90°, mean flow in each renal artery was 0.54, 0.46, and 0.62 L/min in antegrade BSGs, retrograde BSGs, and FSGs, respectively. For angulated stent-grafts, the corresponding values were 0.53, 0.48, and 0.63 L/min. All straight-neck stent-grafts experienced equal cycle-averaged displacement forces of 1.25, 1.69, and 1.95 N at ToAs of 30°, 90°, and 120°, respectively. Angulated main stent-grafts experienced an equal cycle-averaged displacement force of 3.6 N. CONCLUSION: The blood flow rate in renal arteries depends on the configuration of the stent-graft, with an FSG giving maximum renal flow and a retrograde BSG resulting in minimum renal flow. Nevertheless, the difference was small, up to 0.09 L/min. Displacement forces exerted on stent-grafts are very sensitive to lateral neck angle but not on the configuration of the stent-graft.
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Journal articleWang Z, Wood NB, Xu XY, 2015,
A viscoelastic fluid-structure interaction model for carotid arteries under pulsatile flow
, INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Vol: 31, ISSN: 2040-7939- Author Web Link
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- Citations: 13
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Journal articleLiu C, Xu XY, 2015,
A systematic study of temperature sensitive liposomal delivery of doxorubicin using a mathematical model
, Computers in Biology and Medicine, Vol: 60, Pages: 107-116, ISSN: 0010-4825 -
Journal articleLiu C, Krishnan J, Xu XY, 2015,
Intrinsic and induced drug resistance mechanisms: in silico investigations at the cellular and tissue scales
, INTEGRATIVE BIOLOGY, Vol: 7, Pages: 1044-1060, ISSN: 1757-9694- Author Web Link
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- Citations: 3
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Journal articleCheng Z, Wood NB, Gibbs RGJ, et al., 2015,
Geometric and Flow Features of Type B Aortic Dissection: Initial Findings and Comparison of Medically Treated and Stented Cases
, ANNALS OF BIOMEDICAL ENGINEERING, Vol: 43, Pages: 177-189, ISSN: 0090-6964- Author Web Link
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- Citations: 50
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Journal articleKidher E, Cheng Z, Jarral OA, et al., 2014,
In-vivo assessment of the morphology and hemodynamic functions of the BioValsalva (TM) composite valve-conduit graft using cardiac magnetic resonance imaging and computational modelling technology
, Journal of Cardiothoracic Surgery, Vol: 9, ISSN: 1749-8090Background: The evaluation of any new cardiac valvular prosthesis should go beyond the classical morbidityand mortality rates and involve hemodynamic assessment. As a proof of concept, the objective of this study wasto characterise for the first time the hemodynamics and the blood flow profiles at the aortic root in patientsimplanted with BioValsalva™ composite valve-conduit using comprehensive MRI and computer technologies.Methods: Four male patients implanted with BioValsalva™ and 2 age-matched normal controls (NC) underwent cardiacmagnetic resonance imaging (MRI). Phase-contrast imaging with velocity-mapping in 3 orthogonal directions wasperformed at the level of the aortic root and descending thoracic aorta. Computational fluid dynamic (CFD) simulationswere performed for all the subjects with patient-specific flow information derived from phase-contrast MR data.Results: The maximum and mean flow rates throughout the cardiac cycle at the aortic root level were very comparablebetween NC and BioValsalva™ patients (541 ± 199 vs. 567 ± 75 ml/s) and (95 ± 46 vs. 96 ± 10 ml/s), respectively.The maximum velocity (cm/s) was higher in patients (314 ± 49 vs. 223 ± 20; P = 0.06) due to relatively smaller effectiveorifice area (EOA), 2.99 ± 0.47 vs. 4.40 ± 0.24 cm2 (P = 0.06), however, the BioValsalva™ EOA was comparable to otherreported prosthesis. The cross-sectional area and maximum diameter at the root were comparable between the twogroups. BioValsalva™ conduit was stiffer than the native aortic wall, compliance (mm2 • mmHg−1 • 10−3) values were(12.6 ± 4.2 vs 25.3 ± 0.4.; P = 0.06). The maximum time-averaged wall shear stress (Pa), at the ascending aorta wasequivalent between the two groups, 17.17 ± 2.7 (NC) vs. 17.33 ± 4.7 (BioValsalva™ ). Flow streamlines at the root andascending aorta were also similar between the two groups apa
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Journal articleZhan W, Gedroyc W, Xu XY, 2014,
Effect of heterogeneous microvasculature distribution on drug delivery to solid tumour
, JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol: 47, ISSN: 0022-3727- Author Web Link
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- Citations: 28
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Journal articleKandail H, Hamady M, Xu XY, 2014,
Patient-specific analysis of displacement forces acting on fenestrated stent grafts for endovascular aneurysm repair
, JOURNAL OF BIOMECHANICS, Vol: 47, Pages: 3546-3554, ISSN: 0021-9290- Author Web Link
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- Citations: 25
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Journal articleBotto L, Preuss K, Robertson LX, et al., 2014,
Physical characterisation and yield stress of a concentrated Miscanthus suspension
, RHEOLOGICA ACTA, Vol: 53, Pages: 805-815, ISSN: 0035-4511- Author Web Link
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- Citations: 5
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Journal articleTakizawa K, Torii R, Takagi H, et al., 2014,
Coronary arterial dynamics computation with medical-image-based time-dependent anatomical models and element-based zero-stress state estimates
, COMPUTATIONAL MECHANICS, Vol: 54, Pages: 1047-1053, ISSN: 0178-7675- Author Web Link
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- Citations: 36
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Journal articleCheng Z, Juli C, Wood NB, et al., 2014,
Predicting flow in aortic dissection: Comparison of computational model with PC-MRI velocity measurements
, MEDICAL ENGINEERING & PHYSICS, Vol: 36, Pages: 1176-1184, ISSN: 1350-4533- Author Web Link
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- Citations: 49
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Journal articleZhan W, Gedroyc W, Xu XY, 2014,
Mathematical Modelling of Drug Transport and Uptake in a Realistic Model of Solid Tumour.
, Protein and Peptide Letters, Vol: 21, Pages: 1146-1156, ISSN: 1875-5305Effective delivery of therapeutic agents to tumour cells is essential to the success of most cancer treatment therapies except for surgery. The transport of drug in solid tumours involves multiple biophysical and biochemical processes which are strongly dependent on the physicochemical properties of the drug and biological properties of the tumour. Owing to the complexities involved, mathematical models are playing an increasingly important role in identifying the factors leading to inadequate drug delivery to tumours. In this study, a computational model is developed which incorporates real tumour geometry reconstructed from magnetic resonance images, drug transport through the tumour vasculature and interstitium, as well as drug uptake by tumour cells. The effectiveness of anticancer therapy is evaluated based on the percentage of survival tumour cells by directly solving the pharmacodynamics equation using predicted intracellular drug concentrations. Computational simulations are performed for the delivery of doxorubicin through different administration modes and doses. Our predictions show that continuous infusion is far more effective than bolus injection in maintaining high levels of intracellular drug concentration, thereby increasing drug uptake by tumour cells. On the other hand, bolus injection leads to higher extracellular concentration in both tumour and normal tissues compared to continuous infusion, which is undesirable as high drug concentration in normal tissues may increase the risk of associated side effects.
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Journal articleMassai D, Pisani G, Rodriguez A, et al., 2014,
A bioreactor-based model system for cardiac tissue investigation and culture
, JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Vol: 8, Pages: 481-481, ISSN: 1932-6254 -
Journal articleKousera CA, Nijjer S, Torii R, et al., 2014,
Patient-Specific Coronary Stenoses Can Be Modeled Using a Combination of OCT and Flow Velocities to Accurately Predict Hyperemic Pressure Gradients
, IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, Vol: 61, Pages: 1902-1913, ISSN: 0018-9294- Author Web Link
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- Citations: 13
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Journal articleSu J, Gu Z, Zhang M, et al., 2014,
An improved version of RIGID for discrete element simulation of particle flows with arbitrarily complex geometries
, POWDER TECHNOLOGY, Vol: 253, Pages: 393-405, ISSN: 0032-5910- Author Web Link
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- Citations: 14
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Conference paperZhan W, Xu XY, 2014,
Simulation of hifu heating in solid tumour: Comparison of different temperature control modes
, Pages: 176-179, ISSN: 2305-5995Three different temperature control modes used in high intensity focused ultrasound (HIFU) heating of solid tumour are compared in this study. Results show that the control mode with an independent temperature monitor for each focused region is effective in achieving a rapid temperature rise and maintaining a stable temperature level in tumour.
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Conference paperGu B, Adjiman C, Xu Y, 2014,
An integrated model of a spiral-wound membrane module for reverse osmosis considering the effects of winding and spacers
, Pages: 566-568 -
Journal articleLiu C, Krishnan J, Xu X-Y, 2013,
Towards an integrated systems-based modelling framework for drug transport and its effect on tumour cells
, Journal of Biological Engineering -
Journal articleLattimer CR, Azzam M, Kalodiki E, et al., 2013,
Hemodynamic changes in the femoral vein with increasing outflow resistance
, Journal of Vascular Surgery, Vol: 2, Pages: 26-33, ISSN: 1097-6809 -
Journal articleZhang X, Luckham PF, Hughes AD, et al., 2013,
Towards an understanding of the release behavior of temperature-sensitive liposomes: a possible explanation of the "pseudoequilibrium'' release behavior at the phase transition temperature
, JOURNAL OF LIPOSOME RESEARCH, Vol: 23, Pages: 167-173, ISSN: 0898-2104- Author Web Link
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- Citations: 8
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