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Membrane Transport
Published in Lelio G. Colombetti, Biological Transport of Radiotracers, 2020
There are two ways to measure reflection coefficients. One is to observe at what concentration of permeant the volume flow becomes zero. For instance, in red blood cells when isotonic saline is replaced by isoosmotic urea (300 mosmol) the cells will swell (Figure 3). Only when the isotonic saline is replaced by 500 mosmol urea they will not swell. The reflection coefficient for urea in these cells10 is therefore 300/500 = 0.6. The other way to measure reflection coefficients is to consider the volume flow for an impermeable species and replace it by a partially permeable one using the same osmotic gradient in the two cases. The reflection coefficient is then given by
Scanning Angle Interference Microscopy (SAIM)
Published in Qiu-Xing Jiang, New Techniques for Studying Biomembranes, 2020
Cristina Bertocchi, Timothy J. Rudge, Andrea Ravasio
where is the wavenumber in the oxide layer and . The reflection coefficient is then given by:
Physics
Published in Peter R Hoskins, Kevin Martin, Abigail Thrush, Diagnostic Ultrasound, 2019
Kevin Martin, Kumar V Ramnarine
So far, reflection has been described in terms of the amplitude reflection coefficient, which relates the amplitude of the reflected wave to that of the incident wave and was defined in terms of pressure. Reflection coefficient can also be described in terms of the intensity reflection coefficient, which is the ratio of the intensities of the reflected (Ir) and incident waves (Ii). As intensity is proportional to pressure squared, the intensity reflection coefficient RI is given by:
A highly miniaturized antenna with wider band for biomedical applications
Published in Electromagnetic Biology and Medicine, 2022
Doondi Kumar Janapala, M. Nesasudha
The proposed miniaturized antenna for implantable and endoscopic biomedical applications is fabricated and presented in the following Figure 14(a). In order to fabricate, the copper foil of 0.03 mm is used and a stack of such foils are placed in between high thickness copper plates and placed in an electrical discharge machining (EDM) tool to achieve the fine cutting of the intended radiator and ground part design. The PDMS substrate layers with the desired thickness are prepared using traditional methods by mixing the base and curing agent in 10:1 ratio and backed at 60° for 8 hours. The measurement setup for reflection coefficient is presented in Figure 14(b). Minced pork is used as it has equivalent dielectric properties of the human stomach. The antenna is placed approximately 5mm inside the meat. A low loss pigtail connector is connected and field fox microwave analyzer N9915A is used to measure the reflection coefficient vs frequency curve and the cooperation between simulated and measured analysis is presented in the following Figure 15.
Mathematical and computational modeling for the determination of optical parameters of breast cancer cell
Published in Electromagnetic Biology and Medicine, 2021
Shadeeb Hossain, Shamera Hossain
sc is reflection coefficient, −1. The speed of EM propagation ct through tissue specimen is calculated from refractive index of cancer and non-malignant tissues which is 1.41 and 1.35, respectively. The reflection coefficient rsc is calculated from Equation (2). As an experimental setup for 60 mW, 532 nm monochromatic laser source; the number of photons at penetration depth for malignant and non-lesion tissue is shown is reduced to Equations (5) and (6), respectively.
Simulation guided design of the MRcollar: a MR compatible applicator for deep heating in the head and neck region
Published in International Journal of Hyperthermia, 2021
Tomas Drizdal, Kemal Sumser, Gennaro G. Bellizzi, Ondrej Fiser, Jan Vrba, Gerard C. van Rhoon, Desmond T. B. Yeo, Margarethus M. Paulides
To validate this embedded antenna concept, we created a dedicated measurement setup in Sim4Life, as shown in Figure 2(a). Figure 2(b) shows the manufactured setup using polyethylene terephthalate glycol (PET-G) filament printed with 0.4 mm nozzle diameter, 0.25 mm layer height and 100% filling factor at Prusa i3 MK3 (Prusa Research, Prague, Czech Republic) 3D printer. A two-component epoxide glue (Chemex POX Z 21, Prague, Czech Republic) was applied for antenna fixation and coating of the 3D printed part ensuring water resistance of the entire measurement setup. We also 3D printed a 30 mm height frame for the water bolus filled with demineralized water. For the reflection coefficient measurements, we created a phantom with muscle equivalent properties at 434 MHz consisting of demineralized water, salt and isopropyl alcohol. The concentrations of the individual components were adjusted in a few iterative steps using dielectric assessment kit DAK-12 (SPEAG, Zürich, Switzerland) connected to N9923A FieldFox vector network analyzer (Keysight, Santa Rosa, USA). This procedure resulted in a liquid phantom with a relative permittivity of εr=56.4 and an electric conductivity of σ = 0.79 S/m. These values were very close to the literature values for muscle of εr=56.9 and σ = 0.81 S/m used for the hyperthermia treatment planning purposes within this study. The reflection coefficient characteristics were measured for different encasing top thicknesses, ranging from 0.5 mm to 1.5 mm, using a liquid phantom and a FSH8 (Rohde&Schwarz, Munich, Germany) vector network analyzer.