Controlling penetration depth of the THz radiation in biological tissues by hyperosmotic agents

The penetration depth of an evanescent wave in Attenuated Total Reflection (ATR) is dependent on the wavelength of the radiation utilised. At THz frequencies, the penetration depth into biological tissues is in the order of 0.1 to 0.5 mm; rendered pig lard was used as a model sample in this study. A method for the direct measurement of the evanescent wave penetration depth is presented which allows for the estimation of the dispersion of the complex refractive index by using the reflection of the evanescent wave from varying sample depths. The method employs frustrated total internal reflection, and has been demonstrated by using the THz/Far-IR beamline at the Australian synchrotron, and modelled using finite difference time domain (FDTD) simulations.

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Numerical modelling and experimental verification of thermal effects in living cells exposed to high-power pulses of THz radiation

Scientific Reports ◽

10.1038/s41598-021-96898-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

D. S. Sitnikov ◽

A. A. Pronkin ◽

I. V. Ilina ◽

V. A. Revkova ◽

M. A. Konoplyannikov ◽

...

Keyword(s):

Numerical Modelling ◽

Thermal Effect ◽

High Power ◽

Repetition Rate ◽

Numerical Solutions ◽

Biological Tissues ◽

Dermal Fibroblasts ◽

Thz Radiation ◽

Fe Model ◽

Significant Difference

AbstractExposure of cells or biological tissues to high-power pulses of terahertz (THz) radiation leads to changes in a variety of intracellular processes. However, the role of heating effects due to strong absorption of THz radiation by water molecules still stays unclear. In this study, we performed numerical modelling in order to estimate the thermal impact on water of a single THz pulse as well as a series of THz pulses. A finite-element (FE) model that provides numerical solutions for the heat conduction equation is employed to compute the temperature increase. A simple expression for temperature estimation in the center of the spot of THz radiation is presented for given frequency and fluence of the THz pulse. It has been demonstrated that thermal effect is determined by either the average power of radiation or by the fluence of a single THz pulse depending on pulse repetition rate. Human dermal fibroblasts have been exposed to THz pulses (with an energy of $$15\,\upmu \hbox {J}$$ 15 μ J and repetition rate of 100 Hz) to estimate the thermal effect. Analysis of heat shock proteins expression has demonstrated no statistically significant difference ($$p < 0.05$$ p < 0.05 ) between control and experimental groups after 3 h of irradiation.

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Penetration depth of photons in biological tissues from hyperspectral imaging in shortwave infrared in transmission and reflection geometries

Journal of Biomedical Optics ◽

10.1117/1.jbo.21.12.126006 ◽

2016 ◽

Vol 21 (12) ◽

pp. 126006 ◽

Cited By ~ 49

Author(s):

Hairong Zhang ◽

Daniel Salo ◽

David M. Kim ◽

Sergey Komarov ◽

Yuan-Chuan Tai ◽

...

Keyword(s):

Penetration Depth ◽

Hyperspectral Imaging ◽

Biological Tissues ◽

Shortwave Infrared ◽

Transmission And Reflection

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Three-Dimensional Visualization of the T-System of Frog Muscle Using High Voltage Electron Microscopy and a Lanthanum Stain

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080286 ◽

1977 ◽

Vol 35 ◽

pp. 570-571 ◽

Cited By ~ 2

Author(s):

Lee D. Peachey ◽

Clara Franzini-Armstrong

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Three Dimensional ◽

Biological Tissues ◽

High Voltage Electron Microscopy ◽

Transverse Tubular System ◽

Peroxidase Reaction ◽

Voltage Electron ◽

High Voltage Electron ◽

T System

The effective study of biological tissues in thick slices of embedded material by high voltage electron microscopy (HVEM) requires highly selective staining of those structures to be visualized so that they are not hidden or obscured by other structures in the image. A tilt pair of micrographs with subsequent stereoscopic viewing can be an important aid in three-dimensional visualization of these images, once an appropriate stain has been found. The peroxidase reaction has been used for this purpose in visualizing the T-system (transverse tubular system) of frog skeletal muscle by HVEM (1). We have found infiltration with lanthanum hydroxide to be particularly useful for three-dimensional visualization of certain aspects of the structure of the T- system in skeletal muscles of the frog. Specifically, lanthanum more completely fills the lumen of the tubules and is denser than the peroxidase reaction product.

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On the High Voltage Electron Microscopy (1 MeV) of Biological Thick Sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095571 ◽

1972 ◽

Vol 30 ◽

pp. 464-465

Author(s):

William H. Massover

Keyword(s):

Electron Microscopy ◽

High Voltage ◽

Present Report ◽

Biological Tissues ◽

Specimen Preparation ◽

Technical Problems ◽

High Voltage Electron Microscopy ◽

Thin Sections ◽

Voltage Electron ◽

High Voltage Electron

Stereoscopic examination of thick sections of fixed and embedded biological tissues by high voltage electron microscopy has been shown to allow direct visualization of three-dimensional fine structure. The present report will consider the occurrence of some new technical problems in specimen preparation and Image interpretation that are not common during lower voltage studies of thin sections.Thick Sectioning and Tissue Coloration - Epon sections of 0.5 μm or more that are cut with glass knives do not have a uniform thickness as Judged by their interference colors; these colors change with time during their flotation on the knife bath, and again when drying onto the specimen support. Quoted thicknesses thus must be considered only as rough estimates unless measured in specific regions by other methods. Chloroform vapors do not always result in good spreading of thick sections; however, they will spread spontaneously to large degrees after resting on the flotation bath for several minutes. Ribbons of thick sections have been almost impossible to obtain.

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Rapid Critical Point Drying of Tissues in a Parr Bomb

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095261 ◽

1972 ◽

Vol 30 ◽

pp. 400-401

Author(s):

C.A. Baechler ◽

W. C. Pitchford ◽

J. M. Riddle ◽

C.B. Boyd ◽

H. Kanagawa ◽

...

Keyword(s):

Critical Point ◽

Critical Pressure ◽

Soft Tissues ◽

Biological Tissues ◽

Critical Temperatures ◽

Air Drying ◽

The Past ◽

Critical Point Drying ◽

Great Stress ◽

Infiltration Techniques

Preservation of the topographic ultrastructure of soft biological tissues for examination by scanning electron microscopy has been accomplished in the past by using lengthy epoxy infiltration techniques, or dehydration in ethanol or acetone followed by air drying. Since the former technique requires several days of preparation and the latter technique subjects the tissues to great stress during the phase change encountered during air-drying, an alternate rapid, economical, and reliable method of surface structure preservation was developed. Turnbill and Philpott had used a fluorocarbon for the critical point drying of soft tissues and indicated the advantages of working with fluids having both moderately low critical pressures as well as low critical temperatures. Freon-116 (duPont) which has a critical temperature of 19. 7 C and a critical pressure of 432 psi was used in this study.

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Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135149 ◽

1990 ◽

Vol 48 (2) ◽

pp. 308-309

Author(s):

Bruno Schueler ◽

Robert W. Odom

Keyword(s):

Mass Spectrometry ◽

Secondary Ion Mass Spectrometry ◽

Structural Information ◽

Time Of Flight ◽

Biological Tissues ◽

Polymer Surfaces ◽

Tof Sims ◽

Secondary Ions ◽

Ion Mass Spectrometry ◽

Secondary Ion

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

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