The exposure system consisted of an environmentally enclosed room containing nine radial transmission lines (RTL). A detailed description of the RTL irradiator and its environmental controls has been given in several publications (see reference articles). Each RTL was formed by two horizontal parallel conductive plates 4.3 cm apart, with a lightweight composite top plate hinged to the bottom aluminium plate (6 mm thick) providing mechanical support and minimizing temperature gradients among flasks. A central conical aluminium antennaemitted TEM waves radially outward that were terminated by an annulus of RF-absorbing foam braced by a thin lamina of perforated aluminium located 53.3 cm from the antenna's center.
Setup
A total of 16 T-75 culture flasks each containing 40 ml of medium (5 mm deep) were distributed angularly around the antenna with their centers located at a radius of 29.2 cm. The nominal distances of the cell layer from the antenna's center were between 24.7 and 33.8 cm. To boost and homogenize the SAR distribution, each flask was dielectrically loaded with a 3-mm-thick shim of alumina (Al2O3) ceramic that fit snugly under the skirt of the flask.
The flasks were separated into four groups: RTL shams, RTL exposed, start-of-run incubator controls (day 0), and end-of-run incubator controls (day 4). The flasks for simultaneous sham exposure were handled in the same way as the flasks exposed to RFradiation but RTLs were not connected to an RF field source. The mean temperature of the culture medium was maintained at 37 ± 0.3°C with the temperature of each RTL being monitored continuously. However, thermometric measurements revealed bell-shaped temperature profiles along orthogonal axes on the bottom of a flask exposed at 10.0 W/kg with thermal gradients as large as 0.5°C/cm, implying that the cell layer sustained a temperature distribution over a range of ± 1°C which must be taken into consideration in the experimental design and/or interpretation of results.
Pickard WF et al.
(2000):
Experimental and numerical determination of SAR distributions within culture flasks in a dielectric loaded radial transmission line
Moros EG et al.
(1999):
The radial transmission line as a broad-band shielded exposure system for microwave irradiation of large numbers of culture flasks
Moros EG et al.
(1998):
A compact shielded exposure system for the simultaneous long-term UHF irradiation of forty small mammals: I. Electromagnetic and environmental design
Air Force Office of Scientific Research (AFOSR), USA
Air Force Office of Scientific Research/Department of Defense Multidisciplinary University Research Initiative (AFOSR/DOD MURI), USA
Department of Defense (DoD), USA
Motorola
Replicated studies
Goswami PC et al.
(1999):
Proto-oncogene mRNA levels and activities of multiple transcription factors in C3H 10T 1/2 murine embryonic fibroblasts exposed to 835.62 and 847.74 MHz cellular phone communication frequency radiation
Related articles
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Proto-oncogene mRNA levels and activities of multiple transcription factors in C3H 10T 1/2 murine embryonic fibroblasts exposed to 835.62 and 847.74 MHz cellular phone communication frequency radiation
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