Effect of Thermal Damage and Biaxial Loading on the Optical Properties of a Collagenous Tissue

2003 ◽  
Vol 125 (4) ◽  
pp. 540-548 ◽  
Author(s):  
J.-H. Jun ◽  
J. L. Harris ◽  
J. D. Humphrey ◽  
S. Rastegar
Keyword(s):  
Optical Properties ◽  
Thermal Damage ◽  
Biaxial Loading ◽  
Mechanical Load ◽  
Integrating Sphere ◽  
Biaxial Testing ◽  
Scattering Coefficients ◽  
Collagenous Tissue ◽  
Before And After ◽  
Diagnostic Applications

Thermal denaturation can induce marked changes in the optical and mechanical properties of collagenous tissues. The optical properties are important in both therapeutic and diagnostic applications of lasers in medicine. Although mechanical stress can be caused by collagen shrinkage in laser-based therapies, how the mechanical loading state affects the optical properties is not well understood. We used a new computer-controlled biaxial testing system to subject bovine epicardium to various loading conditions both before and after multiple levels of thermal damage. An integrating sphere technique was used to measure transmittance and diffuse reflectance, from which absorption and scattering coefficients were calculated using a Monte Carlo method. Results showed that the scattering coefficient increased with increasing mechanical load but decreased as the degree of thermal damage increased. There was no significant change in the absorption coefficient due to thermal damage over the ranges studied.

scholarly journals Determination of the optical properties of bovine liver tissue using integrating sphere technique

2018 ◽  
Vol 1 (1) ◽  
pp. 248-252
Author(s):  
Halil Arslan ◽  
Yasar Baris Dolukan
Keyword(s):  
Optical Properties ◽  
Liver Tissue ◽  
Tissue Sample ◽  
Bovine Liver ◽  
Integrating Sphere ◽  
Scattering Coefficients ◽  
Single Sphere ◽  
Microscope Slides ◽  
Good Agreement

The optical properties (absorption and reduced scattering coefficients, µa and µs’) of bovine liver tissue for 635 nm has been determined by using integrating sphere and inverse adding-doubling (IAD) techniques. For this purpose, total reflectance and total transmittance values of bovine liver tissue sample, which is placed between two microscope slides, have been measured by using single-sphere system. The measured values have been used as input parameters for IAD program to extract the µa and µs’ of the sample. In this study, µa and µs’ of bovine liver tissue for 635 nm have been determined to be 0.22 mm-1 and 0.51mm-1, respectively. These values, which yield 1.44 mm penetration depth, are in good agreement with the ones in the literature.

Heat-Induced Changes in the Finite Strain Viscoelastic Behavior of a Collaagenous Tissue

2005 ◽  
Vol 127 (4) ◽  
pp. 580-586 ◽  
Author(s):  
S. Baek ◽  
P. B. Wells ◽  
K. R. Rajagopal ◽  
J. D. Humphrey
Keyword(s):  
Stress Relaxation ◽  
Thermal Damage ◽  
Finite Strain ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Elastic Response ◽  
Collagenous Tissue ◽  
Before And After ◽  
Damage Process ◽  
Soft Tissue Diseases

Supra-physiological temperatures are increasingly being used to treat many different soft tissue diseases and injuries. To identify improved clinical treatments, however, there is a need for better information on the effect of the mechanics on the thermal damage process as well as the effect of the incurred damage on the subsequent mechanical properties. In this paper, we report the first biaxial data on the stress relaxation behavior of a collagenous tissue before and after thermal damage. Based on a two-dimensional finite strain viscoelastic model, which incorporates an exponential elastic response, it is shown that the thermal damage can significantly decrease the characteristic time for stress relaxation and the stress residual.

Altered Mechanical Behavior of Epicardium Under Isothermal Biaxial Loading

2004 ◽  
Vol 126 (4) ◽  
pp. 492-497 ◽  
Author(s):  
P. B. Wells ◽  
J. L. Harris ◽  
J. D. Humphrey
Keyword(s):  
Mechanical Behavior ◽  
Soft Tissues ◽  
Biaxial Loading ◽  
Biaxial Stress ◽  
Activation Entropy ◽  
Collagenous Tissue ◽  
Before And After ◽  
Isometric Heating ◽  
Complex Constraints

Most soft tissues that are treated clinically via heating experience multiaxial states of stress and strain in vivo and are subject to complex constraints during treatment. Remarkably, however, there are no prior data on changes in the multiaxial mechanical behavior of a collagenous tissue subjected to isometric constraints during heating. This paper presents the first biaxial stress-stretch data on a collagenous membrane (epicardium) before and after heating while subjected to various biaxial isometric constraints. It was found that isometric heating does not allow the increase in stiffness at low strains that occurs following isotonic heating. Moreover, increasing the degree of stretch prior to heating increased the thermal stability of the tissue consistent with the concept that mechanical loading primarily affects the activation entropy, not the activation energy.

Optical Properties of Nano-Structure Tungsten-Doped Vanadium Oxide

2012 ◽  
Author(s):  
W. B. Cai ◽  
F. Wang ◽  
Y. P. Miao ◽  
J. Wei ◽  
K. L. Zhang
Keyword(s):  
Optical Properties ◽  
Transition Temperature ◽  
Oxide Film ◽  
Vanadium Oxide ◽  
High Vacuum ◽  
Infrared Transmission ◽  
Dc Magnetron Sputtering ◽  
Nano Structure ◽  
Before And After ◽  
Deposited Film

Tungsten-doped vanadium oxide has been proved to decrease the transition temperature, which enables vanadium oxide film to be more promising. Besides, the nano-structure can improve the properties of the film when compared with the as-deposited film. In this letter, a nano-structure tungsten-doped vanadium oxide film is proposed. Tungsten-doped vanadium oxide film was deposited on the Si (400) substrate by DC magnetron sputtering. The doping level was controlled by adjusting the sputtering time. Then the as-deposited film was annealed to form a nano-structure film at the temperature of 500 °C for 1 h in high vacuum. The morphology and crystalline structure of such films were characterized by AFM and XRD, respectively. Optical properties of the films were tested by FTIR, mainly comparing the infrared transmission before and after annealing.

scholarly journals Time-Resolved Reflectance Spectroscopy Applied to the Nondestructive Monitoring of the Internal Optical Properties in Apples

2001 ◽  
Vol 55 (10) ◽  
pp. 1368-1374 ◽  
Author(s):  
Rinaldo Cubeddu ◽  
Cosimo D'Andrea ◽  
Antonio Pifferi ◽  
Paola Taroni ◽  
Alessandro Torricelli ◽  
...  
Keyword(s):  
Optical Properties ◽  
Industrial Applications ◽  
Nondestructive Monitoring ◽  
Nondestructive Measurement ◽  
Time Resolved ◽  
Mean Values ◽  
Scattering Coefficients ◽  
Scattering Spectra ◽  
The Mean ◽  
Temporal Dispersion

Time-resolved reflectance has been used for the nondestructive measurement of optical properties in apples. The technique is based on the detection of the temporal dispersion of a short laser pulse injected into the probed medium. The time distribution of re-emitted photons interpreted with a solution of the diffusion equation yields the mean values of the absorption and reduced scattering coefficients of the medium. The proposed technique proved useful for the measurement of the absorption and scattering spectra of different varieties of apples, revealing the spectral shape of chlorophyll. No major variations were observed in the experimental data when the fruit was peeled, showing that the optical properties measured were those of the pulp. With this technique the change in chlorophyll absorption during storage and ripening could be followed. Finally, a compact prototype working at few selected wavelengths was designed and constructed, demonstrating potentialities of the technique for industrial applications.

scholarly journals Annealing Effect on Some Optical Properties of Cr2O3 Thin Films Prepared by Spray Pyrolysis Technique

2011 ◽  
Vol 8 (2) ◽  
pp. 561-565
Author(s):  
Baghdad Science Journal
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Spray Pyrolysis ◽  
Annealing Temperature ◽  
Spray Pyrolysis Technique ◽  
Annealing Effect ◽  
Before And After

Cr2O3 thin films have been prepared by spray pyrolysis on a glass substrate. Absorbance and transmittance spectra were recorded in the wavelength range (300-900) nm before and after annealing. The effects of annealing temperature on absorption coefficient, refractive index, extinction coefficient, real and imaginary parts of dielectric constant and optical conductivity were expected. It was found that all these parameters increase as the annealing temperature increased to 550°C.

Sign in / Sign up

Export Citation Format

Share Document