| 1. |
- Bayford, Richard H., et al.
(författare)
-
Locating Functionalized Gold Nanoparticles Using Electrical Impedance Tomography
- 2022
-
Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE. - 0018-9294 .- 1558-2531. ; 69:1, s. 494-502
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: An imaging device to locate functionalised nanoparticles, whereby therapeutic agents are transported from the site of administration specifically to diseased tissues, remains a challenge for pharmaceutical research. Here, we show a new method based on electrical impedance tomography (EIT) to provide images of the location of gold nanoparticles (GNPs) and the excitation of GNPs with radio frequencies (RF) to change impedance permitting an estimation of their location in cell models Methods: We have created an imaging system using quantum cluster GNPs as contrast agent, activated with RF fields to heat the functionalized GNPs, which causes a change in impedance in the surrounding region. This change is then identified with EIT. Results: Images of impedance changes of around 80 ± 4% are obtained for a sample of citrate stabilized GNPs in a solution of phosphate-buffered saline. A second quantification was carried out using colorectal cancer cells incubated with culture media, and the internalization of GNPs into the colorectal cancer cells was undertaken to compare them with the EIT images. When the cells were incubated with functionalised GNPs, the change was more apparent, approximately 40 ± 2%. This change was reflected in the EIT image as the cell area was more clearly identifiable from the rest of the area. Significance: EIT can be used as a new method to locate functionalized GNPs in human cells and help in the development of GNP-based drugs in humans to improve their efficacy in the future.
|
|
| 2. |
- Bayford, Richard H., et al.
(författare)
-
Locating Functionalized Gold Nanoparticles Using Electrical Impedance Tomography
- 2022
-
Ingår i: IEEE Transactions on Biomedical Engineering. - : IEEE. - 0018-9294 .- 1558-2531. ; 69:1, s. 494-502
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: An imaging device to locate functionalised nanoparticles, whereby therapeutic agents are transported from the site of administration specifically to diseased tissues, remains a challenge for pharmaceutical research. Here, we show a new method based on electrical impedance tomography (EIT) to provide images of the location of gold nanoparticles (GNPs) and the excitation of GNPs with radio frequencies (RF) to change impedance permitting an estimation of their location in cell models Methods: We have created an imaging system using quantum cluster GNPs as contrast agent, activated with RF fields to heat the functionalized GNPs, which causes a change in impedance in the surrounding region. This change is then identified with EIT. Results: Images of impedance changes of around 80 +/- 4% are obtained for a sample of citrate stabilized GNPs in a solution of phosphate-buffered saline. A second quantification was carried out using colorectal cancer cells incubated with culture media, and the internalization of GNPs into the colorectal cancer cells was undertaken to compare them with the EIT images. When the cells were incubated with functionalised GNPs, the change was more apparent, approximately 40 +/- 2%. This change was reflected in the EIT image as the cell area was more clearly identifiable from the rest of the area. Significance: EIT can be used as a new method to locate functionalized GNPs in human cells and help in the development of GNP-based drugs in humans to improve their efficacy in the future.
|
|
| 3. |
- Dalarsson, Mariana, et al.
(författare)
-
Wave propagation in waveguides with graded plasmonic obstacles
- 2021
-
Ingår i: Journal of the Optical Society of America. B, Optical physics. - : OPTICAL SOC AMER. - 0740-3224 .- 1520-8540. ; 38:1, s. 104-113
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, wave propagation in a hollow waveguide with a graded dielectric layer is studied. Analytic formulas are derived for the electric field components as well as general analytical results for the reflection and transmission coefficients for propagating waves. These results are all valid for waveguides of arbitrary cross sections, and the derived reflection and transmission coefficients are in exact asymptotic agreement with those obtained for a wry thin homogeneous dielectric layer using cascading and mode-matching techniques. Furthermore, the power transmission, reflection, and absorption coefficients, as functions of frequency and layer width, are studied, showing the expected behavior of these parameters. The method proposed in this paper gives directly applicable results that do not require cascading and mode matching, while at the same time having the ability to model smooth transitions that are more realistic in several applications. (C) 2020 Optical Society of America
|
|
| 4. |
- Ivanenko, Yevhen, et al.
(författare)
-
Approximation of dielectric spectroscopy data with Herglotz functions on the real line and convex optimization
- 2016
-
Ingår i: Proceedings of the 2016 18th International Conference on Electromagnetics in Advanced Applications. - : IEEE. - 9781467398114 ; , s. 863-866
-
Konferensbidrag (refereegranskat)abstract
- This paper describes the ongoing research on approximation of frequency dielectric spectroscopy measurement data. The algorithm based on passive approximation, Hilbert transform and Tikhonov regularization for non-uniformly sampled data is derived. The interpolation and extrapolation problems with application to the dielectric spectroscopy measurement data are solved using convex optimization.
|
|
| 5. |
|
|
| 6. |
- Ivanenko, Yevhen, et al.
(författare)
-
Estimation of complex valued permeability of cable armour steel
- 2016
-
Ingår i: 2016 URSI International Symposium on Electromagnetic Theory (EMTS). - : IEEE Press. - 9781509025039 - 9781509025022
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a model based technique to estimate the complex valued permeability of cable armour steel. An efficient analytical model is derived for the linearized mutual impedance of a transformer coil built on a core of magnetic armour steel. A numerical residue calculation is used to solve the related inverse problem based on impedance data. The analytical model is validated using commercial finite element (FEM) software to establish that edge effects can be neglected. The numerical residue calculation is investigated by studying its convergence based on a simple rectangular quadrature rule in comparison to the composite Simpson's rule. When there are no measurement errors, both methods converge with an unexpected high order (superconvergence). However, in practice the estimation performance will be governed by measurement and model errors. Assuming that there are Gaussian measurement errors, the present performance of the estimation technique is quantified and investigated by means of the Cramér-Rao lower bound. In future, the proposed method will be useful as an input to general calculations of power losses in three-phase power cables.
|
|
| 7. |
- Ivanenko, Yevhen
(författare)
-
Estimation of electromagnetic material properties with application to high-voltage power cables
- 2017
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Efficient design of high-voltage power cables is important to achieve an economical delivery of electric power from wind farms and power plants over the very long distances as well as the overseas electric power. The main focus of this thesis is the investigation of electromagnetic losses in components of high-voltage power cables. The objective of the ongoing research is to develop the theory and optimization techniques as tools to make material choices and geometry designs to minimize the high-frequency attenuation and dispersion for HVDC power cables and the power losses associated with HVAC cables. Physical limitations, dispersion relationships and the application of sum rules as well as convex optimization will be investigated to obtain adequate physical insight and a priori modeling information for these problems.For HVAC power cables, the objectives are addressed by performing measurements and estimation of complex valued permeability of cable armour steel in Papers I and II. Efficient analytical solutions for the electromagnetic field generated by helical structures with applications for HVAC power cables have been obtained in Paper III.For HVDC power cables, estimation of insulation characteristics from dielectric spectroscopy data using Herglotz functions, convex optimization and B-splines, has been investigated in Papers V and VI. The unique solution requirements in waveguide problems have been reviewed in Paper IV.
|
|
| 8. |
- Ivanenko, Yevhen, et al.
(författare)
-
Estimation of electromagnetic parameters of cable steel
- 2015
-
Ingår i: Progress in Electromagnetics Research Symposium (PIERS), Prague, Czech Republic, 6-9 July 2015. - : Electromagnetics Academy. - 9781934142295 ; , s. 1068-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
|
|
| 9. |
- Ivanenko, Yevhen, et al.
(författare)
-
Measurements and estimation of the complex valued permeability of magnetic steel
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report is intended as a tutorial on electromagnetic modeling to measure and estimate the complex valued relative permeability of magnetic steel. The main application is with the estimation of the electromagnetic material parameters of the armour wires used with high-voltage AC power cables.When the magnetic field intensity is sufficiently far from saturating the magnetic steel, the magnetic hysteresis phenomena can be approximated by using a linearization approach based on a complex valued (and frequency and amplitude dependent) relative permeability. In the report it is demonstrated how the complex valued permeability of magnetic steel can be efficiently estimated in the presence of a strong skin-effect. This is achieved by using a simple transformer coil built on the magnetic steel to be tested and by efficient numerical modeling based on waveguide theory and complex analysis. Numerical computations based on the Finite Element Method (FEM) and the commercial software COMSOL are employed to establish when edge effects can be ignored in the simplified analytical model.
|
|
| 10. |
- Ivanenko, Yevhen, et al.
(författare)
-
Non-passive approximation as a tool to study the realizability of amplifying media
- 2019
-
Ingår i: 2019 URSI International symposium on electromagnetic theory (EMT2019). - : IEEE Press. - 9781946815064 - 9781538655931 ; , s. 1-4
-
Konferensbidrag (refereegranskat)abstract
- Non-passive approximation is presented as a tool to study the realizability of amplifying media. As an interesting physical example, we derive first a suitable approximation of the plasmonic singularity of a dielectric sphere with respect to a hypothetical amplifying background medium. A non-passive approximation based on convex optimization is then employed to investigate the necessary bandwidth requirements to achieve the approximate pole singularity.
|
|
