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You searched for +publisher:"Temple University" +contributor:("Vorp, David"). Showing records 1 – 2 of 2 total matches.

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Temple University

1. Hemmasizadeh, Ali. Characterization of Heterogeneous Material Properties of Aorta Using Nanoindentation.

Degree: PhD, 2013, Temple University

Mechanical Engineering

Arterial mechanical properties have received increasing attention in the past few decades due to their vast effect on predicting cardiovascular diseases and injuries. The heterogeneity of thoracic aortic tissue was characterized in terms of viscoelastic material properties and correlations were obtained between these properties and tissue morphology. Additionally, the effect of material preservation on the material properties was determined. Changes in the mechanical properties of porcine thoracic aorta wall in the radial direction were characterized using a quasi-linear viscoelastic modeling of nanoindentaiton tests. Two layers of equal thickness were mechanically distinguishable in descending aorta based on the radial variations in the instantaneous Young's modulus E and reduced relaxation function G(t). Overall, comparison of E and Ginf of the outer half (70.27±2.47 kPa and 0.35±0.01) versus the inner half (60.32±1.65 kPa and 0.33±0.01) revealed that the outer half was stiffer and showed less relaxation. The results were used to explain local mechanisms of deformation, force transmission, tear propagation and failure in arteries. A multimodal and multidisciplinary approach was adopted to characterize the transmural morphological properties of aorta. The utilized methods included histology and multi-photon microscopy for describing the wall micro-architecture in the circumferential-radial plane, and Fourier-Transform infrared imaging spectroscopy for determining structural protein, and total protein content. The distributions of these quantified properties across the wall thickness of the porcine descending thoracic aorta were characterized and their relationship with the mechanical properties was determined. It was revealed that there is an increasing trend in mechanical stiffness, Elastic lamella Density (ELD), Structural Protein (SPR), Total Protein (TPR), and Elastin and Collagen Circumferential Percentage (ECP and CCP) from inner layers toward the outer ones. Finally two larger regions with equal thickness (inner and outer halves) were determined based on cluster analysis results of ELD which were in agreement with the cluster analysis of instantaneous Young's modulus. Changes to the local viscoelastic properties of fresh porcine thoracic aorta wall due to three common storage temperatures (+4 °C, -20 °C and -80 °C) within 24 hours, 48 hours, 1 week and 3 weeks were characterized. The changes to both elastic and relaxation behaviors were investigated considering the multilayer, heterogeneous nature of the aortic wall. For +4 °C storage samples, the average instantaneous Young's modulus (E) decreased while their permanent average relaxation amplitude (Ginf) increased and after 48 hours these changes became significant (10%, 13% for E, Ginf respectively). Generally, in freezer storage, E increased and Ginf showed no significant change. In prolonged preservation (> 1 week), the results of +20 °C storage showed significant increase in E (20% after 3 weeks) while this increase for -80 °C…

Advisors/Committee Members: Darvish, Kurosh;, Kiani, Mohammad F., Vorp, David, Autieri, Michael V., Hutapea, Parsaoran, Kent, Richard W.;.

Subjects/Keywords: Engineering; Mechanical engineering; Biomechanics;

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Hemmasizadeh, A. (2013). Characterization of Heterogeneous Material Properties of Aorta Using Nanoindentation. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,240046

Chicago Manual of Style (16th Edition):

Hemmasizadeh, Ali. “Characterization of Heterogeneous Material Properties of Aorta Using Nanoindentation.” 2013. Doctoral Dissertation, Temple University. Accessed August 10, 2020. http://digital.library.temple.edu/u?/p245801coll10,240046.

MLA Handbook (7th Edition):

Hemmasizadeh, Ali. “Characterization of Heterogeneous Material Properties of Aorta Using Nanoindentation.” 2013. Web. 10 Aug 2020.

Vancouver:

Hemmasizadeh A. Characterization of Heterogeneous Material Properties of Aorta Using Nanoindentation. [Internet] [Doctoral dissertation]. Temple University; 2013. [cited 2020 Aug 10]. Available from: http://digital.library.temple.edu/u?/p245801coll10,240046.

Council of Science Editors:

Hemmasizadeh A. Characterization of Heterogeneous Material Properties of Aorta Using Nanoindentation. [Doctoral Dissertation]. Temple University; 2013. Available from: http://digital.library.temple.edu/u?/p245801coll10,240046


Temple University

2. Cheheltani, Rabee. DEVELOPMENT OF INFRARED SPECTROSCOPIC METHODS FOR ASSESSMENT OF EXTRACELLULAR MATRIX CHANGES IN CARDIOVASCULAR DISEASES.

Degree: PhD, 2014, Temple University

Mechanical Engineering

Extracellular matrix (ECM) is a key component and regulator of many biological tissues. Several cardiovascular pathologies are associated with significant changes in the composition of the matrix. Better understanding of these pathologies and the physiological phenomenon behind their development depends on reliable methods that can measure and characterize ECM content and structure. In this dissertation, infrared spectroscopic methodologies are developed to study the changes in extracellular matrix of cardiovascular tissue in two cardiovascular pathologies; myocardial infarction and abdominal aortic aneurysm. The specific aims of this dissertation were: 1. To develop a Fourier transform infrared imaging spectroscopy (FT-IRIS) methodology for creating distribution maps of collagen in remodeled cardiac tissue sections after myocardial infarction, and to quantitatively compare maps created by FT-IRIS with conventional staining techniques. 2. To develop an FT-IRIS method to assess elastin and collagen composition in the aortic wall. This will be accomplished using ex vivo animal aorta samples, where the primary ECM components of the wall will be systematically enzymatically degraded. 3. To apply the newly developed FTIR imaging methodology to evaluate changes in the primary ECM components (collagen and elastin) in the wall of human AAA tissues. The infrared absorbance band centered at 1338 cm-1, was used to map collagen deposition across heart tissue sections of a rat model of myocardial infarction, and was correlated strongly in the size of the scar (R=0.93) and local intensity of collagen deposition (R=0.86). In enzymatically degraded pig aorta samples, as a model of ECM degradation in abdominal aortic aneurysm (AAA), partial least squares (PLS) models were created to predict collagen and elastin content in aorta based on collected FTIR spectra and biochemically measured values. PLS models based on FT-IRIS spectra were able to predict elastin and collagen content of the samples with strong correlations (R2=0.90 and 0.70 respectively). Elastin content prediction from IFOP spectra was successful through a PLS regression model with high correlation (R2=0.81). The PLS regression coefficient from the FT-IRIS models were used to map collagen and elastin human AAA biopsy tissue sections, creating a similar map of each component compared to histologically stained images. The mean value of collagen deposition in each tissue was calculated for 13 pairs of AAA samples where stress had been calculated using finite element modeling. In most pairs with stress values higher than 5 N/m2, collagen content was lower in the sample with higher stress value. Collagen maturity had a weak negative correlation (R=-0.35) with collagen content in these samples. These results confirm that infrared spectroscopy is a powerful tool that can be applied to replace or complement conventional methods such as histology and biochemical analysis to characterize ECM components in cardiovascular tissues. Furthermore, infrared…

Advisors/Committee Members: Kiani, Mohammad F., Pleshko, Nancy;, Sabri, Abdelkarim, Vorp, David, Wang, Bin, Barbe, Mary F.;.

Subjects/Keywords: Biomedical engineering; Mechanical engineering; Analytical chemistry;

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Cheheltani, R. (2014). DEVELOPMENT OF INFRARED SPECTROSCOPIC METHODS FOR ASSESSMENT OF EXTRACELLULAR MATRIX CHANGES IN CARDIOVASCULAR DISEASES. (Doctoral Dissertation). Temple University. Retrieved from http://digital.library.temple.edu/u?/p245801coll10,255000

Chicago Manual of Style (16th Edition):

Cheheltani, Rabee. “DEVELOPMENT OF INFRARED SPECTROSCOPIC METHODS FOR ASSESSMENT OF EXTRACELLULAR MATRIX CHANGES IN CARDIOVASCULAR DISEASES.” 2014. Doctoral Dissertation, Temple University. Accessed August 10, 2020. http://digital.library.temple.edu/u?/p245801coll10,255000.

MLA Handbook (7th Edition):

Cheheltani, Rabee. “DEVELOPMENT OF INFRARED SPECTROSCOPIC METHODS FOR ASSESSMENT OF EXTRACELLULAR MATRIX CHANGES IN CARDIOVASCULAR DISEASES.” 2014. Web. 10 Aug 2020.

Vancouver:

Cheheltani R. DEVELOPMENT OF INFRARED SPECTROSCOPIC METHODS FOR ASSESSMENT OF EXTRACELLULAR MATRIX CHANGES IN CARDIOVASCULAR DISEASES. [Internet] [Doctoral dissertation]. Temple University; 2014. [cited 2020 Aug 10]. Available from: http://digital.library.temple.edu/u?/p245801coll10,255000.

Council of Science Editors:

Cheheltani R. DEVELOPMENT OF INFRARED SPECTROSCOPIC METHODS FOR ASSESSMENT OF EXTRACELLULAR MATRIX CHANGES IN CARDIOVASCULAR DISEASES. [Doctoral Dissertation]. Temple University; 2014. Available from: http://digital.library.temple.edu/u?/p245801coll10,255000

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