scholarly journals Light propagation from fluorescent probes in biological tissues by coupled time-dependent parabolic simplified spherical harmonics equations: erratum

2011 ◽  
Vol 2 (4) ◽  
pp. 980
Author(s):  
Jorge Bouza Domínguez ◽  
Yves Bérubé-Lauzière
Keyword(s):  
Spherical Harmonics ◽  
Fluorescent Probes ◽  
Light Propagation ◽  
Biological Tissues ◽  
Time Dependent

Poroelastic Indentation Analysis for Hydrated Biological Tissues

2006 ◽  
Vol 975 ◽  
Author(s):  
Michelle L. Oyen ◽  
Amanpreet K. Bembey ◽  
Andrew J. Bushby
Keyword(s):  
Indentation Test ◽  
Biological Tissues ◽  
Time Dependent ◽  
Spherical Indentation ◽  
Indentation Creep ◽  
Polar Solvents ◽  
Viscoelastic Analysis ◽  
Wide Range ◽  
Indentation Problem

ABSTRACTIndentation techniques are employed for the measurement of mechanical properties of a wide range of materials. In particular, techniques focused at small length-scales, such as nanoindentation and AFM indentation, allow for local characterization of material properties in heterogeneous materials including natural tissues and biomimetic materials. Typical elastic analysis for spherical indentation is applicable in the absence of time-dependent deformation, but is inappropriate for materials with time-dependent responses. Recent analyses for the viscoelastic indentation problem, based on elastic-viscoelastic correspondence, have begun to address the issue of time-dependent deformation during an indentation test. The viscoelastic analysis has been shown to fit experimental indentation data well, and has been demonstrated as useful for characterization of viscoelasticity in polymeric materials and in hydrated mineralized tissues. However, a viscoelastic analysis is not necessarily sufficient for multi-phase materials with fluid flow. In the current work, a poroelastic analysis—based on fluid motion through a porous elastic network—is used to examine spherical indentation creep responses of hydrated biological materials. Both analytical and finite element approaches are considered for the poroelastic Hertzian indentation problem. Modeling results are compared with experimental data from nanoindentation of hydrated bone immersed in water and polar solvents (ethanol, methanol, acetone). Baseline (water-immersed) bone responses are characterized using the poroelastic model and numerical results are compared with altered hydration states due to polar solvents.

scholarly journals Generalized Beer–Lambert model for near-infrared light propagation in thick biological tissues

2016 ◽  
Vol 21 (7) ◽  
pp. 076012 ◽  
Author(s):  
Manish Bhatt ◽  
Kalyan R. Ayyalasomayajula ◽  
Phaneendra K. Yalavarthy
Keyword(s):  
Light Propagation ◽  
Near Infrared ◽  
Biological Tissues ◽  
Infrared Light ◽  
Near Infrared Light ◽  
Lambert Model

Measurement of time-dependent changes in optical transmission characteristics of biological tissues

1995 ◽  
Author(s):  
Uwe Vogel ◽  
Juergen Uhlemann ◽  
Andreas Melchner ◽  
Richard Freyer ◽  
Juergen Beuthan
Keyword(s):  
Optical Transmission ◽  
Biological Tissues ◽  
Time Dependent ◽  
Transmission Characteristics

A DIFFUSION–TRANSPORT HYBRID METHOD FOR ACCELERATING OPTICAL TOMOGRAPHY

2010 ◽  
Vol 03 (04) ◽  
pp. 293-305 ◽  
Author(s):  
HYUN KEOL KIM ◽  
ANDREAS H. HIELSCHER
Keyword(s):  
Hybrid Method ◽  
Light Propagation ◽  
Optical Tomography ◽  
Biological Tissues ◽  
Initial Guess ◽  
Computationally Efficient ◽  
Diffusion Transport ◽  
Tissue Phantoms ◽  
Hybrid Solver ◽  
Reconstruction Time

It is well acknowledged that the equation of radiative transfer (ERT) provides an accurate prediction of light propagation in biological tissues, while the diffusion approximation (DA) is of limited accuracy for the transport regime. However, ERT-based reconstruction codes require much longer computation times as compared to DA-based reconstruction codes. We introduce here a computationally efficient algorithm, called a diffusion–transport hybrid solver, that makes use of the DA- or low-order ERT-based inverse solution as an initial guess for the full ERT-based reconstruction solution. To evaluate the performance of this hybrid method, we present extensive studies involving numerical tissue phantoms and experimental data. As a result, we show that the hybrid method reduces the reconstruction time by a factor of up to 23, depending on the physical character of the problem.

scholarly journals Characterizing the viscoelastic properties of thin hydrogel-based constructs for tissue engineering applications

2005 ◽  
Vol 2 (5) ◽  
pp. 455-463 ◽  
Author(s):  
Mark Ahearne ◽  
Ying Yang ◽  
Alicia J El Haj ◽  
Kong Y Then ◽  
Kuo-Kang Liu
Keyword(s):  
Tissue Engineering ◽  
Viscoelastic Properties ◽  
Biological Tissues ◽  
Constant Load ◽  
Time Dependent ◽  
Hydrogel Membranes ◽  
Agarose Hydrogel ◽  
Viscoelastic Theory ◽  
Working Distance ◽  
Convenient Technique

We present a novel indentation method for characterizing the viscoelastic properties of alginate and agarose hydrogel based constructs, which are often used as a model system of soft biological tissues. A sensitive long working distance microscope was used for measuring the time-dependent deformation of the thin circular hydrogel membranes under a constant load. The deformation of the constructs was measured laterally. The elastic modulus as a function of time can be determined by a large deformation theory based on Mooney–Rivlin elasticity. A viscoelastic theory, Zener model, was applied to correlate the time-dependent deformation of the constructs with various gel concentrations, and the creep parameters can therefore be quantitatively estimated. The value of Young's modulus was shown to increase in proportion with gel concentration. This finding is consistent with other publications. Our results also showed the great capability of using the technique to measure gels with incorporated corneal stromal cells. This study demonstrates a novel and convenient technique to measure mechanical properties of hydrogel in a non-destructive, online and real-time fashion. Thus this novel technique can become a valuable tool for soft tissue engineering.

scholarly journals A first-principles simulation method for ultra-fast nano-optics

2019 ◽  
Vol 205 ◽  
pp. 04023 ◽  
Author(s):  
Mitsuharu Uemoto ◽  
Kazuhiro Yabana ◽  
Shunsuke A. Sato ◽  
Yuta Hirokawa ◽  
Taisuke Boku
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Light Propagation ◽  
Nonlinear Effects ◽  
Simulation Method ◽  
Time Dependent ◽  
Full Account ◽  
Nano Structure ◽  
Sham Equation ◽  
Ultrashort Laser

We develop a computational approach for ultrafast nano-optics based on first-principles time-dependent density functional theory. Solving Maxwell equations for light propagation and time-dependent Kohn-Sham equation for electron dynamics simultaneously, intense and ultrashort laser pulse interaction with a dielectric nano-structure is described taking full account of nonlinear effects. As an illustrative example, irradiation of a pulsed light on silicon nano-sphere system is presented.

Sign in / Sign up

Export Citation Format

Share Document