Quantitative diagnosis of breast tumors by characterization of viscoelastic behavior of healthy breast tissue

Pressurized vessels that transfer media from one location to another often contain a bolted connection. Gaskets are essential for these systems since they confer high levels of leak mitigation across of range of operating environments (i.e., internal pressure and temperature). The balance of both sealability and compressibility must be displayed in candidate gasket materials to be subjected to aggressive operating conditions. Historically, thin gauge gasket (i.e., 1/16” thick) confer high sealability while thick gaskets offer superior compressibility (i.e., 1/8”). Fabricated with skive cut, ceramic particle-reinforced PTFE, these materials display linear viscoelastic behavior that allow consolidation to occur. For example, GYLON® 3504 is filled with Aluminosilicate Microspheres, GYLON®3510 is filled with barium sulfate, respectively, to efficiently fill crevices along the surfaces of the flange. Novel textured PTFE gasket (3504 EPX and 3510 EPX) have been developed to simultaneously confer sealability and compressibility compared to flat products. A design of experiments (DoE) approach is applied to characterize the factors that influence load relaxation responses of the both candidate textured PTFE (dual-face honeycomb) and existing (flat) gasket styles. Using an instrumented test platform analyzed. A new parameter is presented to quantify gasket efficiency. The collection of efficiency measurement methods and approach to re-torque optimization convey a novel framework that designers can invoke to facilitate improved flange performance.

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Characterization of the three-dimensional linear viscoelastic behavior of asphalt concrete mixtures

Construction and Building Materials ◽

10.1016/j.conbuildmat.2015.12.094 ◽

2016 ◽

Vol 105 ◽

pp. 356-364 ◽

Cited By ~ 6

Author(s):

Andrea Graziani ◽

Fabrizio Cardone ◽

Amedeo Virgili

Keyword(s):

Asphalt Concrete ◽

Three Dimensional ◽

Viscoelastic Behavior ◽

Concrete Mixtures ◽

Linear Viscoelastic Behavior ◽

Linear Viscoelastic

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Role of smooth muscle activation in the static and dynamic mechanical characterization of human aortas

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2117232119 ◽

2022 ◽

Vol 119 (3) ◽

pp. e2117232119

Author(s):

Giulio Franchini ◽

Ivan D. Breslavsky ◽

Francesco Giovanniello ◽

Ali Kassab ◽

Gerhard A. Holzapfel ◽

...

Keyword(s):

Experimental Data ◽

Smooth Muscle ◽

Muscle Activation ◽

Mechanical Response ◽

Mechanical Characterization ◽

Viscoelastic Behavior ◽

Material Model ◽

Suitable Material ◽

Dynamic Mechanical

Experimental data and a suitable material model for human aortas with smooth muscle activation are not available in the literature despite the need for developing advanced grafts; the present study closes this gap. Mechanical characterization of human descending thoracic aortas was performed with and without vascular smooth muscle (VSM) activation. Specimens were taken from 13 heart-beating donors. The aortic segments were cooled in Belzer UW solution during transport and tested within a few hours after explantation. VSM activation was achieved through the use of potassium depolarization and noradrenaline as vasoactive agents. In addition to isometric activation experiments, the quasistatic passive and active stress–strain curves were obtained for circumferential and longitudinal strips of the aortic material. This characterization made it possible to create an original mechanical model of the active aortic material that accurately fits the experimental data. The dynamic mechanical characterization was executed using cyclic strain at different frequencies of physiological interest. An initial prestretch, which corresponded to the physiological conditions, was applied before cyclic loading. Dynamic tests made it possible to identify the differences in the viscoelastic behavior of the passive and active tissue. This work illustrates the importance of VSM activation for the static and dynamic mechanical response of human aortas. Most importantly, this study provides material data and a material model for the development of a future generation of active aortic grafts that mimic natural behavior and help regulate blood pressure.

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Copper Containing Glass-Based Bone Adhesives for Orthopaedic Applications: Glass Characterization and Advanced Mechanical Evaluation

10.1101/2020.11.19.390138 ◽

2020 ◽

Author(s):

Sahar. Mokhtari ◽

Anthony.W. Wren

Keyword(s):

Mechanical Properties ◽

Photoelectron Spectroscopy ◽

Structural Changes ◽

Viscoelastic Behavior ◽

Polymer Chains ◽

Nano Particles ◽

X Ray Diffraction ◽

X Ray ◽

Compression Data

AbstractThis study addresses issues with currently used bone adhesives, by producing novel glass based skeletal adhesives through modification of the base glass composition to include copper (Cu) and by characterizing each glass with respect to structural changes. Bioactive glasses have found applications in fields such as orthopedics and dentistry, where they have been utilized for the restoration of bone and teeth. The present work outlines the formation of flexible organic-inorganic polyacrylic acid (PAA) – glass hybrids, commercial forms are known as glass ionomer cements (GICs). Initial stages of this research will involve characterization of the Cu-glasses, significant to evaluate the properties of the resulting adhesives. Scanning electron microscopy (SEM) of annealed Cu glasses indicates the presence of partial crystallization in the glass. The structural analysis of the glass using Raman suggests the formation of CuO nanocrystals on the surface. X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy (XPS) further confirmed the formation of crystalline CuO phases on the surface of the annealed Cu-glass. The setting reaction was studied using Fourier transform infrared spectroscopy (ATR-FTIR). The mechanical properties of the Cu containing adhesives exhibited gel viscoelastic behavior and enhanced mechanical properties when compared to the control composition. Compression data indicated the Cu glass adhesives were efficient at energy dissipation due to the reversible interactions between CuO nano particles and PAA polymer chains.

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