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Tuba Yilmaz - One of the best experts on this subject based on the ideXlab platform.

  • microwave Dielectric Property based stage detection of skin cancer
    URSI General Assembly and Scientific Symposium, 2021
    Co-Authors: Cemanur Aydinalp, Sulayman Joof, Tuba Yilmaz
    Abstract:

    Inherent discrepancy of Dielectric properties between biological tissues has drawn considerable interest for the last 30 years. Open-ended coaxial probe is one of the promising methods to measure Dielectric properties due to the non-destructive and broadband measurement characteristics. The advances in this method will improve the diagnosis and treatment processes in the medical industry. The aim of this study is not only to determine skin tumors but also to identify the cancer stages with open-ended coaxial probes. This will aid rapid an inexpensive diagnosis of skin cancer. To this end, we simulated a 2.2mm diameter open-ended coaxial probe, which is commercially available, with three-layered breast skin tissue and tumors with fifteen different volumes using Altair FEKO simulation software. The S-parameters of each configuration is simulated in the range of 500 MHz to 2GHz. Based on the simulated S-parameters, the results indicate that the first stage and healthy tissue shows a difference of 11.46 % at 1.5GHz. Similarly, there is a difference of about 39.48 % between the second and third stage. Skin cancer is considered critical at the third stage, therefore having a distinctive difference between Dielectric properties and thus between the S-parameter response when the probe is terminated with second and the third stage tumor tissue will help in the detection of early stage skin cancer.

  • Broadband Microwave Dielectric Property Comparison of Human Fetal Osteoblastic (hFOB) and Osteosarcoma (SaOS-2) Cell Lines
    2020 14th European Conference on Antennas and Propagation (EuCAP), 2020
    Co-Authors: Zeynep Macit, Tuba Yilmaz, Cemanur Aydinalp, Ayse Buse Ozdabak Sert, Fatma Nese Kok
    Abstract:

    Dielectric properties of biological tissues are mostly studied in order to develop microwave-based diagnosis and treatment methods for variety of applications including but not limited to cancer detection/treatment, detection of alzheimer diseases, and blood glucose monitoring. Reported studies generally focuses on tabulating the Dielectric Property discrepancy between the diseased and normal tissues on a macro level. For example, the measured Dielectric properties of malignant tumor tissues are higher than those of normal tissues. Possibly, one factor contributing to such discrepancy is the amount of water contained in the malignant tumor tissues. However, the sources of Dielectric Property discrepancy between the malignant and normal tissues remains unexplored. This study investigates whether the Dielectric Property discrepancy is consistent on cell level between the malignant and normal cell samples to identify sources for Dielectric Property discrepancy in tissues and to enable microwave pathological applications. To this end, the Dielectric properties of human fetal osteoblastic (hFOB) and osteosarcoma (SaOS-2) cell lines were measured in the frequency range of 500 MHz to 10 GHz using an open-ended coaxial probe. The measurements were conducted on pellet form and suspension form of cells, since there is no consensus on the protocol of cell line broadband Dielectric Property measurement. The discrepancy between hFOB and SaOS-2 cell suspensions at the whole measurement frequency are 0.1480% and 2.8267% for relative permittivity and conductivity, respectively. In pellet measurements, calculated percent discrepancy are to 2.1895% for relative permittivity and 3.6766% for conductivity.

  • microwave Dielectric Property based classification of renal calculi application of a knn algorithm
    Computers in Biology and Medicine, 2019
    Co-Authors: Banu Sacli, Tuba Yilmaz, Cemanur Aydinalp, Sulayman Joof, Gokhan Cansiz, Mehmet Cayoren, Bulent Onal, Ibrahim Akduman
    Abstract:

    Abstract The proper management of renal lithiasis presents a challenge, with the recurrence rate of the disease being as high as 46%. To prevent recurrence, the first step is the accurate categorization of the discarded renal calculi. Currently, the discarded renal calculi type is determined with the X-ray powder diffraction method which requires a cumbersome sample preparation. This work presents a new approach that can enable fast and accurate classification of discarded renal calculi with minimal sample preparation requirements. To do so, first, the measurements of the Dielectric properties of naturally formed renal calculi are collected with the open-ended contact probe technique between 500 MHz and 6 GHz with 100 MHz intervals. Cole–Cole parameters are fitted to the measured Dielectric properties with the generalized Newton–Raphson method. The renal calculi types are classified based on their Cole–Cole parameters as calcium oxalate, cystine, or struvite. The classification is performed using k-nearest neighbors (kNN) machine learning algorithm with the 10 nearest neighbors, where accuracy as high as 98.17% is achieved.

  • Microwave Dielectric Property Based Classification of Malignancies
    2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2019
    Co-Authors: Tuba Yilmaz
    Abstract:

    Broadband Dielectric Property measurements of biological tissues is mostly performed with open ended coaxial probe technique due to a number of advantages such as flexible sample shape and size. However, the technique is known to suffer from high error rates; thus, envisioned applications of the technique remains hampered by this problem. One way to mitigate such error for medical applications is to perform tissue classification with machine learning algorithms. In this work, Cole-Cole parameters of rat liver Dielectric properties are used for training and testing of an in house Support Vector Machine (SVM) algorithm to enable malignant tissue classification. Cole-Cole parameters are fitted with Particle Swarm Optimization (PSO) to a total of 700 Dielectric Property measurements collected from 22 rats. The Cole-Cole parameters are fed to the SVM algorithm and k-fold cross validation is used to prevent the algorithm from memorizing the data. Hepatic malignancies are classified with 96% accuracy where a better accuracy is obtained in comparison to plain Dielectric Property measurement and also an automated decision making mechanism is enabled.

  • towards accurate Dielectric Property retrieval of biological tissues for blood glucose monitoring
    IEEE Transactions on Microwave Theory and Techniques, 2014
    Co-Authors: Tuba Yilmaz, Robert Foster
    Abstract:

    An analytical formulation for relative Dielectric con- stant retrieval is reconstructed to establish a relationship between the response of a spiral microstrip resonator and effective relative Dielectric constant of a lossy superstrate, such as biological tissue. To do so, an analytical equation is modified by constructing functions for the two unknowns, filling factor A and the effective length leff of the resonator. This is done by simulating the resonator with digital phantoms of varying permittivity .T he values of A and leff are determined for each phantom from the resulting S-parameter response, using Particle Swarm Op- timization. Multiple non-linear regression is applied to produce equations for A and leff, expressed as a function of frequency and the phantom's relative Dielectric constant. These equations are combined to form a new non-linear analytical equation, which is then solved using the Newton-Raphson iterative method, for both simulations and measurements of physical phantoms. To verify the reconstructed Dielectric constant, the Dielectric properties of the physical phantoms are determined with a commercial high temperature open-ended coaxial probe. The Dielectric properties are reconstructed by the described method, with less than 3.67% error with respect to the measurements.

Xianzhong Tang - One of the best experts on this subject based on the ideXlab platform.

  • low temperature synthesis of polyimide poly vinylidene fluoride composites with excellent Dielectric Property
    Materials Letters, 2017
    Co-Authors: Xin Mao, Wenfeng Guo, Jie Yang, Xianzhong Tang
    Abstract:

    Abstract All-organic polyimide (PI)/poly(vinylidene fluoride) (PVDF) composite materials with high Dielectric constant and low Dielectric loss were fabricated via solution blending followed by the chemical imidization of polyamic acid (PAA, precursor of PI) at a low temperature. The Dielectric and thermal properties of the PI/PVDF composites were investigated. Results indicated that the Dielectric properties of the composites were significantly increased due to the incorporation of PVDF, and the composites exhibited excellent thermal stability. The Dielectric constant of the composites was sharply increased to 7.745 at 1 kHz, which was approximately 2.1 times higher than that of pure PI. The Dielectric loss was only 0.0898 when PVDF content was as high as 50 wt.%. Moreover, the dependence of the Dielectric constant and Dielectric loss on frequency was studied. Within the testing frequency range of 100 Hz–1 MHz, the Dielectric constant of the composites slightly decreased and the Dielectric loss was less than 0.12. The results demonstrated that the PI/PVDF composites were promising Dielectric materials for modern electronic applications.

  • preparation and characterization of pi pvdf composite films with excellent Dielectric Property
    Journal of Materials Science: Materials in Electronics, 2017
    Co-Authors: Xin Mao, Wenfeng Guo, Jie Yang, Xianzhong Tang
    Abstract:

    All-organic polyimide (PI)/poly(vinylidene fluoride) (PVDF) composite materials with high Dielectric constant and low Dielectric loss were fabricated via solution blending. The Dielectric, mechanical, and thermal properties of the PI/PVDF composite films were studied. Results indicated that the Dielectric properties of the composites were highly reinforced through the introduction of PVDF, and the composites exhibited excellent thermal stability. When the mass fraction of PVDF was adjusted to 30 wt%, the specimen demonstrated excellent thermal properties, superior mechanical properties, high Dielectric constant (5.7, 1 kHz), and low Dielectric loss (0.009, 1 kHz). Moreover, the dependence of the Dielectric constant and Dielectric loss on frequency was investigated. The composite presented stable Dielectric constant and Dielectric loss that were less than 0.04 within the testing frequency range of 100 Hz–10 MHz. This study demonstrated that the PI/PVDF composites were potential Dielectric materials in the field of electronics.

Zhimin Dang - One of the best experts on this subject based on the ideXlab platform.

  • effect of tensile strain on morphology and Dielectric Property in nanotube polymer nanocomposites
    Applied Physics Letters, 2007
    Co-Authors: Zhimin Dang, Shenghong Yao
    Abstract:

    As an electrically conducting filler, multiwall carbon nanotube (MWNT) with a great slenderness ratio was introduced into poly(vinylidene fluoride) (PVDF) to form the MWNT/PVDF nanocomposites. Dielectric properties of these composites before and after stretching were studied at wide frequency ranges from 102to107Hz. The results showed that the Dielectric constant and conductivity after stretching were always lower than those before stretching. In the composites with high concentration of MWNT, the decreases in Dielectric constant and conductivity were very significant. Rearrangement of MWNT in the composites along with the tensile-strain direction could be charge with the results of Dielectric properties.

  • influence of silane coupling agent on morphology and Dielectric Property in batio3 polyvinylidene fluoride composites
    Applied Physics Letters, 2006
    Co-Authors: Zhimin Dang, Haiyan Wang, Haiping Xu
    Abstract:

    Surface of BaTiO3 particle was chemically modified using silane coupling agent (KH550) in order to improve its compatibility with polyvinylidene fluoride (PVDF) matrix polymer, and therefore, expectable microstructure and Dielectric Property of the BaTiO3/PVDF composites were acquired. Infrared spectra reveal an obvious interaction between BaTiO3 and PVDF induced by the addition of KH550 coupling agent, and the interaction was also confirmed by the observation of morphology of fractured surface of the BaTiO3/PVDF composite when the concentration of KH550 is around 1.0wt%. Crystal lattice parameter of BaTiO3 in the composite was also changed because of the interaction. Finally, increased Dielectric constant in the PVDF matrix composite with BaTiO3 treated by 1.0wt% KH550 was found.

  • dependence of Dielectric behavior on the physical Property of fillers in the polymer matrix composites
    Synthetic Metals, 2004
    Co-Authors: Zhimin Dang, Yihe Zhang, S C Tjong
    Abstract:

    Abstract Low-density polyethylene (LDPE)/electrical conducting fillers composites were prepared via simple blending and hot-molding technique. Dielectric Property of the composites with different conductivity fillers, such as carbon fiber (CF), cupper (Cu) and nickel (Ni) powders was investigated. Dependence of the Dielectric Property of the LDPE/fillers composites on frequency and volume fraction of fillers was studied. The experimental results could be explained by means of the conductivity of fillers and the interface polarization between LDPE and fillers. Percolation was also seen in this study when the volume fraction of conducting fillers was close to critical value, in which the composites undergo an insulator–conductor transition. The relationship among the Dielectric Property, the microstructure and the fillers with different conductivity was proposed.

Hitoshi Ohsato - One of the best experts on this subject based on the ideXlab platform.

  • low temperature sintering microwave Dielectric Property relations in ba3 vo4 2 ceramic
    Journal of Alloys and Compounds, 2006
    Co-Authors: Ryosuke Umemura, Hirotaka Ogawa, Atsushi Yokoi, Hitoshi Ohsato
    Abstract:

    Abstract The Ba 3 (VO 4 ) 2 – x  wt.%B 2 O 3 ( x  = 0–5) ceramics were prepared by the solid state reaction method in order to reduce the sintering temperature. The saturated bulk densities of Ba 3 (VO 4 ) 2 – x  wt.%B 2 O 3 ceramics were shifted toward lower sintering temperatures with increased the amounts of B 2 O 3 doping, and then an improvement in the quality factor ( Q · f ) of the samples was recognized at the lower sintering temperatures. As a result, the Q · f value of 41,065 GH, the ɛ r of 12.5 and the τ f value of 38.8 ppm/°C were obtained in the sample of the Ba 3 (VO 4 ) 2 –0.5 wt.%B 2 O 3 ceramic sintered at the temperature of 950 °C. However, the Q · f values of the sample with B 2 O 3 higher than that of 3 wt.% additions decreased because of the formation of secondary phase and abnormal grain growth of the sample. As for the chemical compatibility with silver, no secondary phase was detected in the XRPD pattern when the mixtures of Ba 3 (VO 4 ) 2 –1 wt.%B 2 O 3 ceramics and Ag powders were heat-treated at 900 °C for 1 h in air.

  • microwave Dielectric Property microstructure relationships in y2ba cu1 xmg x o5 solid solutions
    Journal of The European Ceramic Society, 2004
    Co-Authors: Katsuhiro Mori, Hirotaka Ogawa, Akinori Kan, Hitoshi Ohsato
    Abstract:

    Abstract Y 2 Ba(Cu 1− x Mg x )O 5 solid solutions were synthesized by the solid state reaction method and the microstructure was studied by using SEM in order to clarify the microwave Dielectric Property–structure relationship. From the variations in the lattice parameters obtained by Rietveld analysis and the least-squares method, it was clarified that the limit of Y 2 Ba(Cu 1− x Mg x )O 5 solid solutions is approximately at x =0.2. Grain growth and the reduction of porosity in the samples increased with the composition x . The Dielectric constants were constant and the quality factors were extremely increased from 3800 to 42 300 GHz, as the composition x increased from 0 to 0.2. Thus, it was found that the quality factors of the samples were closely related to the morphological changes and a formation of the porosity; the temperature coefficient of resonant frequency of the samples ranged from −35.0 to −56.5 ppm/°C. Moreover, compared to Y 2 Ba(Cu 1− x Mg x )O 5 compound without cold isotropic pressure (CIP), that with CIP especially exhibited approximately 16% higher Q · f value.

  • low temperature sintering and microwave Dielectric Property of ba6 3xsm8 2xti18o54 solid solution
    Journal of the Ceramic Society of Japan, 2002
    Co-Authors: Yutaka Ota, Hitoshi Ohsato, Kenichi Kakimoto, Susumu Nishigaki
    Abstract:

    Ba6-3xSm(8+2x)(1-y)Ti18O54-δ{δ=3y(x+4)} ceramics were developed in this study to lower the sintering temperature as well as to maintain the excellent microwave Dielectric properties of tungsten-bronze-type like Ba6-3xSm8+2xTi18O54 solid solutions. Ba6-3xSm(8+2x)(1-y)Ti18O54-δ ceramics were prepared by a slight change in the mixing composition from the solid solutions area to Ba2Ti9O20 direction on the BaO-Sm2O3-TiO2 ternary phase diagram. Effects of compositional parameters x and y on the density of the sintered body and the microwave Dielectric properties were investigated. Ba4Sm9.15Ti18O53.72(x=2/3, y=0.02) ceramics sintered at 1350°C demonstrated the excellent properties including a high relative permittivity (er=81), high quality factor (Q⋅f=10000GHz) and low temperature factor of resonant frequency (τf=-13ppm/°C). These properties are almost equivalent to those obtained in Ba4Sm9.33Ti18O54(x=2/3) solid solutions which need higher fabricating temperatures than 1460°C. It was also shown that a ball-milling technique strongly affected the density of sintered body and the resulting relative permittivity.

Kenneth Reifsnider - One of the best experts on this subject based on the ideXlab platform.

  • Relationship of Dielectric Property change to composite material state degradation
    Composites Science and Technology, 2014
    Co-Authors: Rassel Raihan, Jon Michael Adkins, Jeffrey Baker, Fazle Rabbi, Kenneth Reifsnider
    Abstract:

    Polymer matrix composites are widely used in many industries, i.e. aerospace, microelectronics, energy storage etc., because of their unique properties and performance. During their service life, changes of material state caused by deformation and damage accumulation under combined mechanical, thermal and electrical fields requires fundamental understanding to support design of those material systems. Heterogeneous material systems are inherently Dielectric as determined by their complex morphology. Dielectric properties of such materials are altered by many factors, e.g., electrical and structural interactions of the particles, and the shape, orientation and distribution of the constituents of the material system. When damage occurs, new phases are created as micro-defects, and grow progressively, interact, and accumulate. The Dielectric properties of the composite system also change in a manner that uniquely reflects those details. In the present work we report a non-invasive, in-operando technique to study changes in Dielectric properties during progressive damage accumulation in composite materials subjected to mechanical loading.