High rate failure properties of human aortic tissue under longitudinal extension

2018 ◽  
Vol 4 (2/3) ◽  
pp. 125 ◽  
Author(s):  
Piyush Gaur ◽  
Khyati Verma ◽  
Anoop Chawla ◽  
Sudipto Mukherjee ◽  
Sanjeev Lalwani ◽  
...  
Keyword(s):  
High Rate ◽  
Aortic Tissue ◽  
Failure Properties ◽  
Longitudinal Extension

High rate failure properties of human aortic tissue under longitudinal extension

2018 ◽  
Vol 4 (2/3) ◽  
pp. 125
Author(s):  
Ravi Kiran Chitteti ◽  
Pronoy Ghosh ◽  
Christian Mayer ◽  
Sudipto Mukherjee ◽  
Sanjeev Lalwani ◽  
...  
Keyword(s):  
High Rate ◽  
Aortic Tissue ◽  
Failure Properties ◽  
Longitudinal Extension

High rate failure properties of porcine aortic tissue under uniaxial tension

2019 ◽  
pp. 1-11
Author(s):  
Piyush Gaur ◽  
Sanyam Sharma ◽  
Devendra Kumar ◽  
Anoop Chawla ◽  
Sudipto Mukherjee ◽  
...  
Keyword(s):  
Uniaxial Tension ◽  
High Rate ◽  
Aortic Tissue ◽  
Failure Properties

Effect of Hypertension on Elasticity and Geometry of Aortic Tissue From Dogs

1990 ◽  
Vol 112 (1) ◽  
pp. 70-74 ◽  
Author(s):  
Ramesh N. Vaishnav ◽  
Jafar Vossoughi ◽  
Dali J. Patel ◽  
LaVal N. Cothran ◽  
Bernell R. Coleman ◽  
...  
Keyword(s):  
Longitudinal Direction ◽  
Circumferential Direction ◽  
Tissue Response ◽  
Aortic Tissue ◽  
External Diameter ◽  
Extension Ratio ◽  
Axial Forces ◽  
Bilateral Renal Artery ◽  
Longitudinal Extension ◽  
Geometric Changes

Inflation-extension experiments were carried out on segments of the descending thoracic aortas from 4 normotensive and 4 hypertensive dogs rendered hypertensive using either unilateral or bilateral renal artery constriction. Intravascular pressures up to 200 mm Hg and axial forces up to 200 g were used. The external diameter of the segment and the distance between two longitudinally spaced gage marks were recorded photographically at each pressure-force level combination. Dimensions in the undeformed configuration were measured at the end of the inflation-extension experiment. Data were analyzed for changes in geometry and force-deformation response. Results indicate that: 1. Under sustained hypertension the wall thickness in the undeformed configuration increases with a concurrent reduction in the in-situ longitudinal extension ratio. 2. This dual tissue response accomplishes substantial reductions in the circumferential and longitudinal stresses from the levels that would be reached at equivlaent pressures in the absence of these geometric changes. 3. At comparable intravascular pressures the extensibility in the circumferential direction is slightly greater for the hypertensive aortas as compared to normals. However, the stress-extension ratio relationship in the circumferential direction is similar in the two groups. 4. The stress-extension ratio relationship in the longitudinal direction indicates that the hypertensive aorta is stiffer than its normotensive counterpart.

Material Properties of the Post-Mortem Stomach in High-Rate Equibiaxial Elongation

2012 ◽  
Author(s):  
Meghan K. Howes ◽  
Warren N. Hardy
Keyword(s):  
Failure Modes ◽  
Motor Vehicle ◽  
High Rate ◽  
Motor Vehicle Collisions ◽  
Tissue Samples ◽  
Vehicle Collisions ◽  
Gastric Rupture ◽  
Biomechanical Response ◽  
Failure Properties ◽  
Equibiaxial Elongation

Risk of serious abdominal injury in motor vehicle collisions (MVCs) is substantially reduced with the proper use of seatbelts [1]. However, a significant increase in occurrence of gastrointestinal tract injury exists with belt loading [2]. Crash-induced injuries of the stomach that occur in MVCs include gastric rupture and laceration [3]. To characterize the biomechanical response of the stomach associated with these failure modes, the multidirectional failure properties of cruciate tissue samples were investigated with high-rate biaxial stretch.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Ultrastructural observations of the aorta of calves implanted with a mechanical left ventricular assist device

1990 ◽  
Vol 48 (3) ◽  
pp. 834-835
Author(s):  
J P Cassella ◽  
V Salih ◽  
T R Graham
Keyword(s):  
Left Ventricular Assist Device ◽  
Ventricular Assist Device ◽  
Left Ventricular ◽  
Aortic Tissue ◽  
Assist Device ◽  
Ventricular Assist ◽  
Transmission Electron ◽  
Left Ventricular Assist ◽  
Preliminary Study

Left ventricular assist systems are being developed for eventual long term or permanent implantation as an alternative to heart transplantation in patients unsuitable for or denied the transplant option. Evaluation of the effects of these devices upon normal physiology is required. A preliminary study was conducted to evaluate the morphology of aortic tissue from calves implanted with a pneumatic Left Ventricular Assist device-LVAD. Two 3 month old heifer calves (calf 1 and calf 2) were electively explanted after 128 days and 47 days respectively. Descending thoracic aortic tissue from both animals was removed immediately post mortem and placed into karnovsky’s fixative. The tissue was subsequently processed for transmission electron microscopy (TEM). Some aortic tissue was fixed in neutral buffered formalin and processed for routine light microscopy.

Rapid Freezing of Freeze-Etch Specimens

1980 ◽  
Vol 38 ◽  
pp. 752-755
Author(s):  
A. Elgsaeter ◽  
T. Espevik ◽  
G. Kopstad
Keyword(s):  
Low Temperature ◽  
Metal Surface ◽  
Relative Velocity ◽  
Thermal Contact ◽  
High Rate ◽  
Rapid Freezing ◽  
Temperature Decrease ◽  
Freeze Etching

The importance of a high rate of temperature decrease (“rapid freezing”) when freezing specimens for freeze-etching has long been recognized1. The two basic methods for achieving rapid freezing are: 1) dropping the specimen onto a metal surface at low temperature, 2) bringing the specimen instantaneously into thermal contact with a liquid at low temperature and subsequently maintaining a high relative velocity between the liquid and the specimen. Over the last couple of years the first method has received strong renewed interest, particularily as the result of a series of important studies by Heuser and coworkers 2,3. In this paper we will compare these two freezing methods theoretically and experimentally.

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