Advances in Bioengineering最新文献

{"title":"How Simplifying Assumptions Affect the Computation of Three-Dimensional Knee Loads in Cycling","authors":"C. Gregersen, M. Hull","doi":"10.1115/imece2001/bed-23069","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23069","url":null,"abstract":"\u0000 Determining the force and moment components transmitted by the knee is useful both to understand the etiology of over-use knee injuries common in cycling [1] and also to assess how well different interventions protect against over-use injury. Because the loads thought to be primarily responsible for over-use knee injury are the non-driving moments (varus/valgus and internal/external axial moments) transmitted by the knee [2], a 3-D model is necessary for calculating these loads. To our knowledge, no study has developed a model that includes complete 3-D kinematics of the segments to calculate these loads. Consequently one objective of this study was to develop a complete, 3-D model to calculate the intersegmental knee loads during cycling. A second objective was to use this model to examine how simplifying assumptions affect the 3-D knee loads.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86906376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Repeatability of a Computer-Aided Optical Tracking System for Total Knee Replacement Surgery","authors":"V. Sarin, W. Pratt, S. Stulberg","doi":"10.1115/imece2001/bed-23080","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23080","url":null,"abstract":"\u0000 The success of total knee replacement surgery depends critically on the restoration of limb alignment and on proper implant positioning [1]. Even with contemporary mechanical alignment instrumentation, errors in alignment correction and implant positioning do occur [2–5]. To improve upon the accuracy of conventional mechanical instrumentation, computer-aided navigation systems have been developed for total knee replacement surgery. Clinical studies have demonstrated that use of these systems for knee replacement surgery can lead to improved limb alignment and implant positioning [6–9]. While such systems have been shown to be clinically effective, their overall accuracy and repeatability in clinical use appears to be highly technique dependent [10]. The inherent repeatability (precision) of such systems has not been closely investigated.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90083895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A “Point Cloud” Approach in Superelastic Stent Design","authors":"X. Gong, C. Bonsignore, A. Pelton","doi":"10.1115/imece2001/bed-23083","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23083","url":null,"abstract":"\u0000 Figure 1 shows schematically the stress-strain relation for Nitinol under uniaxial tensile test at constant temperature. Originally, material is in the Austenite phase. Upon loading, below a small strain, ε1, stress is linearly proportional to the strain. The slope defines the Young’s modulus of Nitinol in Austenite phase. When strain reaches beyond ε1, a small increase in stress induces a large amount of strain owing to the phase transition from Austenite to Martensite. After completion of the phase transition, for strain larger than ε2, the stress and strain relation is linear again with a different slope, which defines the modulus of Martensite phase. During unloading, Martensite remains until strain ε3, which is less than ε2. Below ε3, the Martensite reverts to Austenite and a large reverse strain is produced until ε4, which is smaller than ε1. After unloading below ε4, the material returns to linear elastic behavior. This unique material behavior of Nitinol, known as superelasticity, along with its excellent biocompatibility and corrosion resistance, makes Nitinol a perfect material candidate for self-expanding stent applications.\u0000 Self-expanding stents made of Nitinol offer unique features such as biased stiffness to better fit the anatomy and excellent corrosion resistance. When implanted in vivo, stents are subjected to the pulsatile loading from systolic and diastolic heartbeats and therefore it is necessary to design for a long (10 years) fatigue life.\u0000 Nitinol’s fatigue behavior is known to depend upon the mean and the alternating strains from cyclic loading. Therefore, one approach to ensure that the stent has a long fatigue life is to design in such a manner that both the mean and the alternating strains of the proposed stent are lower than the Nitinol’s fatigue endurance limits. For linear materials, this normally is not an issue as the location of the maximum mean strain is also the location of maximum alternating strain, therefore the history of the maximum strain point can be used to predict the device fatigue life or used as the design criterion.\u0000 However, Nitinol is a highly nonlinear and path dependent material that makes it possible that the location of the maximum mean strain is not necessarily the location of maximum alternating strain.\u0000 A rigorous design criterion is developed at Nitinol Devices and Components (NDC) to trace the strain history of every material point. We accomplish this by means of a nonlinear finite element analysis (FEA) using ABAQUS. The FEA analysis uses a special user-defined material subroutine by HKS/WEST customized for Nitinol. The loading condition on the stents can come from two sources: 1. An analytical approach to determine the stent diameters by balancing the stent within a 6% compliant tube to simulate physiological loading, or 2. A direct measurement of stent diameter change inside the tube from the in-vitro testing.\u0000 This article demonstrates the criterion using the second approach, i.e.,","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72644839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Exploration of Cell Stress and Deformation Under Shear Flow","authors":"X. Guo, E. Takai, Kai Liu, Xiaodong Wang","doi":"10.1115/imece2001/bed-23160","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23160","url":null,"abstract":"\u0000 The biological response of bone cells (osteoblasts and/or osteocytes) to mechanical loading is an important basic science topic in the mechanism of mechano-signal transduction in bone adaptation to mechanical loading. The characterization of this mechanism of signal transduction is crucial in the understanding of the etiology of age-related bone loss, bone loss during space flight and the optimal design of implants for total joint replacements. It has been hypothesized that deformation-generated fluid shear stress is one of the major mechanical stimuli that bone cells respond to. Many in vitro experiments utilize a parallel-plate flow chamber by imposing fluid shear stress on cultured osteoblasts. For example, changes in intracellular Ca++ levels and mitogen-activated protein kinase (MAPK) phosphorylation has been quantified in response to applied shear flow [1,2]. In these studies, the flow shear stress at the wall of the flow chamber τ wall = 6 μ Q w h 2 , where Q is the volumetric flow rate, w and h are the width and height of the flow chamber, respectively, and μ is the media viscosity. However, this wall shear stress may not indicate the actual stress state which bone cells experience, which depends on the details of the flow-cell interaction, including the mechanical properties of the cell, the attachment condition of the cell to the wall as well as the cell density. In order to obtain a quantitative relationship between the biological response of bone cells to applied shear flow, it is necessary to quantify in detail the flow-cell interaction in a typical shear flow experiment. The objective of this study was to quantify the shear stress within the cell under applied shear flow, incorporating fully coupled flow and solid deformation analyses using the finite element technique. Specifically, we examined the influence of the elastic modulus of the cell and the spacing distance between cells on the shear stress within the cell.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79120624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Simulation of Flow in a Physiologically Realistic Model of the Human Aorta With Vessel Compliance and Movement","authors":"Suo Jin, J. Oshinski, D. Giddens","doi":"10.1115/imece2001/bed-23122","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23122","url":null,"abstract":"\u0000 Vessel compliance and movement are important factors influencing blood flow patterns in arteries in addition to vessel geometry. This importance has been previously demonstrated in the study of coronary artery flow by several investigators. For large vessels such as the aorta, the effects are less well understood because its movement magnitude is relatively small and the movement trace is complex. In this study, a computational fluid dynamics (CFD) aorta model was reconstructed from magnetic resonance (MR) images, and MRI was used to obtain aortic flow mapping and wall movement data. Under some simplifying assumptions, the data were used to control an aorta model that has moving wall and meshes during a computational simulation. The results of the CFD simulation show similar flow patterns as the MRI results in the ascending aorta, verifying that the model reconstruction and simulation are reasonable.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74762837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic Model and Analysis of a Centrifugal Blood Pump and Induction Motor","authors":"P. R. Mawasha, Omotoye Omotoso, P. Lam, T. Conway","doi":"10.1115/imece2001/bed-23133","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23133","url":null,"abstract":"\u0000 A dynamic model of a centrifugal blood pump, induction motor, and channel is investigated through nonlinear analysis. A centrifugal blood pump with forward curved blades and an induction motor is subject to constant inlet and outlet mass flow conditions leading to a channel. The steady state pressure drop versus volumetric flow rate relation is described by a constitutive model containing a cubic nonlinearity obtained from centrifugal pump characteristic curves. Within certain operating regimes along the characteristic curve, the model exhibits self-excited pulsatile periodic morion and the qualitative features of the response can be understood in terms of the underlying model. Further, the mathematical model is a more general model and can be used by the designer of centrifugal blood pumps and other ventricular assist devices (VADs) to determine the instability mechanisms.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75405533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the Visco-Elastic Response of Bovine Liver Tissue","authors":"A. J. Moskowitz, M. Richards, L. S. Taylor, A. Lerner","doi":"10.1115/imece2001/bed-23005","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23005","url":null,"abstract":"\u0000 Liver tissue plays a role in many physiological systems and is characterized as a soft tissue. Changes in the perceived stiffness of the liver by palpation may indicate Cirrhosis or other liver ailments. New ultrasound techniques that use an applied force such as sonoelastography may aid physicians in diagnosis by providing a quantitative comparison of the mechanical properties for the tissue [1]. At this time, these mechanical characteristics remain to be fully defined. In this study, a four-parameter model composed of springs and dashpots has been used to describe the response of liver under unconfined creep compression tests.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76238650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Real-Time Approach to Modeling Soft Tissue Deformation","authors":"J. Mayrose, K. Chugh, T. Kesavadas","doi":"10.1115/imece2001/bed-23067","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23067","url":null,"abstract":"\u0000 We are working toward developing a physically accurate real-time abdominal palpation simulator. To achieve this, two major goals must be met. The first is to develop a model that accurately simulates the physical characteristics of the tissues in the human abdomen. The model must not only be physically accurate, it must run in real-time for the simulation to be usable. The second major goal is to design a framework within which to parameterize physical properties of different tissues as well as a methodology to extract those parameters non-invasively.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74170714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Novel Device for Direct Permeation Measurements of Hydrogels and Soft Hydrated Tissues","authors":"N. A. Andarawis, Sara L. Seyhan, R. Mauck, M. Soltz, G. Ateshian, C. Hung","doi":"10.1115/imece2001/bed-23149","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23149","url":null,"abstract":"\u0000 The goal of this study was to develop a system to reliably measure the intrinsic hydraulic permeability of hydrogels and soft hydrated tissues. Such a device can be used to assess the development of functional properties in tissue engineered constructs [1]. The design parameters for such a device include ease of assembly and the ability to measure hydraulic permeability over a range of specimen deformations. To meet these criteria, a device was designed that could quantify the hydraulic permeability of a sample under different levels of deformation, allowing characterization of strain-dependent effects. The device was tested on both agarose and articular cartilage specimens, yielding permeability values consistent with published data [2]. The intrinsic hydraulic permeability of a tissue is an important parameter that governs fluid exudation during deformational loading. The ability of articular cartilage, which exhibits non-linear strain dependent hydraulic permeability [3], to generate and sustain interstitial fluid pressurization is essential to its functional properties (e.g., load bearing and lubrication). This novel device allows for direct and reliable measurement of these physical properties.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86589023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nuclear Membrane Dynamics of a Nuclear Pore Complex Structure","authors":"R. Pidaparti, P. A. Sarma, A. Sinha, G. Vemuri, A. Gacy","doi":"10.1115/imece2001/bed-23162","DOIUrl":"https://doi.org/10.1115/imece2001/bed-23162","url":null,"abstract":"\u0000 The nuclear pore complex (NPC) is an excellent example of a bio-molecular motor, since it operates primarily via energy dependent processes, and performs some of the most vital functions required for the survival of a cell. In the presence of appropriate chemical stimuli, the NPC apparently opens or closes, like a gating mechanism, and permits the flow of material in to and out of the nucleus. An NPC, with typical dimensions of 100–200 nm, is a megadalton (MDa) heteromultimeric protein complex, which spans the nuclear envelope and is postulated to possess a transporter-containing central cylindrical body embedded between cytoplasmic and nucleoplasmic rings as shown in Fig.1. A cell has many, presumably identical, NPCs, each of which participates in the import and export of nuclear material from within the nucleus [1–2]. Exactly how this transport occurs through the NPC is an open question, and a very important one, with profound implications for nanoscale devices for fluidic transport, genetic engineering and targeted drug delivery.","PeriodicalId":7238,"journal":{"name":"Advances in Bioengineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2001-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86585086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}