Transverse Electromagnetic Mode Cell Research Articles

Microtubular structure impairment after GSM-modulated RF radiation exposure.

The objective of the study was to investigate whether low-level 915 MHz GSM-modulated radiofrequency (RF) radiation impairs microtubular structure and affects normal cell growth. V79 cells were exposed to a GSM-modulated field in a Gigahertz Transversal Electromagnetic Mode cell (GTEM cell) for 1, 2, and 3 h. Signal generator combined with power and chip modulator generated the electromagnetic field (EMF). The electric field strength was adjusted to 10, 20, and 30 V/m, and the average specific absorption rate (SAR) was calculated to be 0.23, 0.8, and 1.6 W/kg. The structure of microtubule proteins was assessed by indirect immunocytochemistry, and cell growth was determined based on cell counts taken every day over six post-exposure days. Three-hour radiation exposure significantly altered microtubule structure regardless of the electric field strength. Moreover, on the third post-exposure day, three-hour radiation significantly reduced cell growth, regardless of field strength. The same was observed with two-hour exposure at 20 and 30 V/m. In conclusion, 915 MHz GSM-modulated RF radiation affects microtubular proteins in a time-dependent manner, which, in turn, affects cell proliferation. Our future research will focus on microtubule structure throughout the cell cycle and RF radiation effects on mitotic spindle.

Determination of Equivalent Coupling Surface of Passive Components Using the TEM Cell

The design of cheaper and more compact electromagnetic compatibility (EMC) filters can be achieved by exploiting the magnetic coupling between components. This requires the knowledge of coupling coefficients between components and, consequently, of their equivalent coupling surface. The aim of this paper is to present how this coupling surface can be determined using a transverse electromagnetic mode cell. This methodology is described and applied to two different cases: a capacitor and an inductor. In order to validate the determination and usage of equivalent coupling surfaces, a comparison between the calculation and measurement of mutual inductances is carried out on practical examples.

Assessment of Integrated Circuits Emissions With an Equivalent Dipole-Moment Method

An appropriate integrated circuit (IC) evaluation early in the design stage is essential to ensure timely development of mobile devices with a satisfactory total isotropic sensitivity (TIS), a figure of merit to measure radio-frequency receiver sensitivity. An IC evaluation method based on equivalent dipole-moment source using the transverse electromagnetic mode (TEM) cell is proposed and experimentally investigated in terms of correlation of measured TIS with two existing IC emission measurement methods: the TEM cell method (IEC 61967-2) and the near-field scan method (IEC 61967-3). In addition, a cost-effective and reliable test scheme is introduced so the three approaches can share a single common test board to avoid potential hardware-to-hardware deviation. Measurement results on three software-controlled operation states are compared with respective TIS measured in an anechoic chamber. The best correlation was obtained in the proposed equivalent dipole-moment-based evaluation method and the limitations of the two previous methods are discussed.

In vitro non-thermal oxidative stress response after 1800 MHz radiofrequency radiation.

In this study possible connection between radiofrequency exposure (RF) and development of oxidative stress was investigated by measuring impairment in cellular oxidation-reduction balance immediately after RF exposure. Fibroblast cells V79 were exposed for 10, 30 and 60 minutes to 1800 MHz RF radiation. Electric field strength was 30 V/m and specific absorption rate (SAR) was calculated to be 1.6 W/kg. Electromagnetic field was generated within Gigahertz Transversal Electromagnetic Mode cell (GTEM) equipped by signal generator, amplifier and modulator. Cell viability was determined by CCK-8 colorimetric assay and level of reactive oxygen species (ROS) was detected by dihydroethidium staining. Reduced glutathione (GSH) and glutathione peroxidase (GSH-Px) were used to assess cell antioxidant activity while lipid oxidative damage was evaluated measuring concentration of malondialdehyde. Viability of V79 cells remained within normal physiological values regardless of exposure time. Increased level of superoxide radicals was detected after 60-min exposure. Significantly higher GSH level was observed immediately after 10-min exposure with higher but insignificant activity of GSH-Px. Lipid oxidative damage in exposed cell samples was not observed. Short-term RF exposure revealed transient oxidation-reduction imbalance in fibroblast cells following adaptation to applied experimental conditions.

Cell oxidation–reduction imbalance after modulated radiofrequency radiation

Aim of this study was to evaluate an influence of modulated radiofrequency field (RF) of 1800 MHz, strength of 30 V/m on oxidation–reduction processes within the cell. The assigned RF field was generated within Gigahertz Transversal Electromagnetic Mode cell equipped by signal generator, modulator, and amplifier. Cell line V79, was irradiated for 10, 30, and 60 min, specific absorption rate was calculated to be 1.6 W/kg. Cell metabolic activity and viability was determined by MTT assay. In order to define total protein content, colorimetric method was used. Concentration of oxidised proteins was evaluated by enzyme-linked immunosorbent assay. Reactive oxygen species (ROS) marked with fluorescent probe 2′,7′-dichlorofluorescin diacetate were measured by means of plate reader device. In comparison with control cell samples, metabolic activity and total protein content in exposed cells did not differ significantly. Concentrations of carbonyl derivates, a product of protein oxidation, insignificantly but continuously increase with duration of exposure. In exposed samples, ROS level significantly (p < 0.05) increased after 10 min of exposure. Decrease in ROS level was observed after 30-min treatment indicating antioxidant defence mechanism activation. In conclusion, under the given laboratory conditions, modulated RF radiation might cause impairment in cell oxidation–reduction equilibrium within the growing cells.

DESIGN AND VALIDATION OF A TEM CELL USED FOR RADIOFREQUENCY DOSIMETRIC STUDIES

A Transverse Electromagnetic Mode (TEM) cell is an interesting option for studying the biological efiects of radiofrequency radiation at reduced scale (in vitro studies). Controlled and well-characterized exposure conditions are essential for a conclusive investigation: the biological sample is exposed to a uniform incident electromagnetic wave and the dose of absorbed radiation is precisely determined and correlated with the efiect. Unfortunately, experimental dosimetry is often unavailable or inapplicable, so that a pre- characterized and validated experimental setup is most valuable. As such, the primary objective of the present work is to experimentally validate a computational model of a self-built TEM cell designed for bioelectromagnetic experiments in the 100MHz{1GHz frequency range. Validation is achieved by comparing the computed vs. measured values for three signiflcant parameters: scattering parameters, incident electric fleld distribution, and absorbed power in a set of liquid samples. Successful validation and characterization is achieved by using CST Microwave Studio's flnite integration technique (FIT), and respectively a network analyzer for the experimental setup. The secondary objective is a dosimetric study of four difierent liquid samples loaded in the cell. The absorption coe-cient (AC) is used, assimilated to the speciflc absorption rate (SAR) of energy deposition in the entire sample volume. AC is shown to converge in experiment and simulation up to 800MHz for all samples. AC doesn't depend directly on the samples' volume (despite greater volumes frequently showing higher absorption) but rather upon the internal fleld distribution, which in turn mostly depends on the frequency and on the dimensions of the liquid samples.

Exposure to ELF-pulse modulated X band microwaves increases in vitro human astrocytoma cell proliferation.

Common concern about the biological effects of electromagnetic fields (EMF) is increasing with the expansion of X-band microwaves (MW). The purpose of our work was to determine whether exposure to MW pulses in this range can induce toxic effects on human astrocytoma cells. Cultured astrocytoma cells (Clonetics line 1321N1) were submitted to 9.6 GHz carrier, 90% amplitude modulated by extremely low frequency (ELF)-EMF pulses inside a Gigahertz Transversal Electromagnetic Mode cell (GTEM-cell). Astrocytoma cultures were maintained inside a GTEM-incubator in standard culture conditions at 37+/-0.1 degrees C, 5% CO2, in a humidified atmosphere. Two experimental conditions were applied with field parameters respectively of: PW 100-120 ns; PRF 100-800 Hz; PRI 10-1.25 ms; power 0.34-0.60 mW; electric field strength 1.25-1.64 V/m; magnetic field peak amplitude 41.4-54.6 microOe. SAR was calculated to be 4.0 x 10-4 W/Kg. Astrocytoma samples were grown in a standard incubator. Reaching 70-80% confluence, cells were transferred to a GTEM-incubator. Experimental procedure included exposed human astrocytoma cells to MW for 15, 30, 60 min and 24 h and unexposed sham-control samples. Double blind method was applied. Our results showed that cytoskeleton proteins, cell morphology and viability were not modified. Statistically significant results showed increased cell proliferation rate under 24h MW exposure. Hsp-70 and Bcl-2 antiapoptotic proteins were observed in control and treated samples, while an increased expression of connexin 43 proteins was found in exposed samples. The implication of these results on increased proliferation is the subject of our current research.

In vitro testing of cellular response to ultra high frequency electromagnetic field radiation

The aim of this study was to evaluate whether low-level, ultra high frequency (UHF) irradiation of 935 MHz influences the cell structure and growth of V79 cells. UHF field was generated inside a Gigahertz Transversal Electromagnetic Mode cell (GTEM-cell) with a Hewlett-Packard signal generator. The electric field strength was 8.2+/-0.3 V/cm and the average specific absorption rate (SAR) was calculated to be 0.12 W/kg. Cell samples were cultivated in a humidified atmosphere at 37 degrees C with 5% CO2. Prepared cell samples were exposed to a 935 MHz continuous wave frequency field for 1, 2, and 3 h. The structure of microtubule proteins has been determined using the immunocytochemical method. Cell growth was determined by cell counts for each hour of exposure during five post-exposure days. Negative- and positive-cell controls were included into the experimental procedure. In comparison with control cells, the microtubule structure clearly altered after 3h of irradiation (p<0.05). Significantly decreased growth was noted in cells exposed for 3h three days after irradiation (p<0.05). It seems that the 935 MHz, low-level UHF radiation affects microtubule proteins, which consequently may obstruct cell growth.

Backscattering-Based Measurement of Reactive Antenna Input Impedance

A scattering technique for measuring reactive antenna input impedance is described. The antenna scattering is measured with three different loads: an open circuit, a conjugate match, and a reactive match. The load reactances tune the antenna into resonance at the measurement band. Theory and error considerations are presented, as well as measurement results of two ultra high frequency radio frequency identification antennas. The measurements were performed in a gigahertz transverse electromagnetic mode cell. The measured impedances are within about 10% of the simulated values for a dipole-like antenna. The results of a planar inverted-F antenna are somewhat more complex, but also supported by the presented simulations and the coaxial impedance measurement results.

Influence of 864 MHz electromagnetic field on growth kinetics of established cell line

Considering often contradictory data on biological effects of mobile phones frequencies on established cell culture lines, our study aimed at evaluating the influence of 864 MHz electromagnetic field on proliferation, colony forming ability and viability of Chinese hamster lung cells of line V79 cell. Prior to exposure for 1, 2 and 3 hours in transversal electromagnetic mode cell (TEM-cell) cell culture were subcultivated for one day. Cells were exposed to 864 MHz continuous wave (CW) at an average specific absorption rate (SAR) of 0.66 W/kg. Philips PM 5508 connected with signal amplifier was used as signal generator. To determine cell growth, V79 cells were plated in concentration of 1x10/sup 4/cells/ml, and raised in a humified atmosphere at 37/spl deg/C in 5% CO/sub 2/. Cell proliferation was determined by cell counts for each hour of exposure on postexposure days 1, 2, 3, 4 and 5. To identify colony-forming ability, cells were cultivated in concentration of 40 cells/ml, and incubated as above. Colony forming ability for each hour of exposure was defined by colony counts on experimental day 7. Trypan blue exclusion method was used to determine cell viability. In comparison to sham-exposed cells, growth curve of irradiated culture samples showed significant decrease (p<0.05) after 2 and 3 hours of exposure on experimental day 3, respectively. Both, the colony forming ability and viability of irradiated cells did not significantly differ from sham-exposed controls. In conclusion, no vigorous influence of 864 MHz electromagnetic field on growth kinetics of V79 cell culture was detected. Where effect was seen, it was not dose-dependent.

Measurement of integrated circuit conducted emissions by using a transverse electromagnetic mode (TEM) cell

This paper presents a new technique for the measurement of integrated circuit (IC) conducted emissions. In particular, the spectrum of interfering current flowing through an IC port is detected by using a transverse electromagnetic mode (TEM) cell. A structure composed of a microstrip line inserted in a matched TEM cell is considered. The structure is excited by an interfering source connected to one end of the transmission line. The relationship between the current spectrum of the source and the spectrum of the RF power delivered to the TEM mode of the cell is derived. This relationship is evaluated for one specific structure and the experimental validation is shown. Results of conducted emission measurement performed by using such a technique are shown as well and compared with those derived by using the magnetic probe method.