GHz Irradiation Research Articles

Novel 60 GHz Band Spatial Synthetic Exposure Setup to Investigate Biological Effects of 5G and Beyond Wireless Systems on Human Body.

The global spread of 5th generation (5G) wireless systems causes some concern about health effects of millimeter waves (MMW). To investigate biological effects of local exposure to 5G-MMW on human body, a novel 60 GHz band exposure setup was developed, and its performance was validated. A spatial synthetic beam-type exposure setup using two dielectric lens antennas was proposed to achieve high intensity 60 GHz irradiation to the target area of human skin. Variety distributions and intensities of electromagnetic fields at the exposed area, which is modified by incident angles of the combined beams, were simulated using finite-difference time-domain methods. The exposure performance we estimated was verified by temperature elevations of surface in a physical arm-shaped silicone phantom during the MMW exposure. The interference fringes generated in the exposed area due to the combined two-directional beam radiations were observed both in the simulation and in the phantom experiment but eliminated by applying an orthogonalizing polarized feeding structure. Under these exposure conditions, the local temperature changes, which could evoke warmth sensations, were obtained at the target area of the human forearm skin, which means the achievement of exposure performance we intended.

An ultra-fast non-conventional waste management protocol to recycle of industrial fly ash into zeolite X.

An ultra-fast non-conventional waste management protocol was being designed and applied to recycle and reuse industrial coal fly ash (CFA) waste to generate highly pure nanozeolite X. Both microwave heating-assisted hydrothermal treatment method and ultrasonic waves-assisted hydrothermal method have been successfully used for the fast valorization of power plant CFA waste, and the results were compared with conversional valorization method for CFA conversion to zeolite. While conventional methods like hydrothermal treatment using sodium hydroxide took up to 4days in valorization of the solid CFA waste into a useful zeolitic X material; the non-conventional methods using microwave irradiation of frequency 2.45GHz and ultrasound irradiation of frequency 20kHz took 90min and 20min respectively to fast-valorize the solid waste into highly pure zeolite material with high cation-exchanged capacity. The unconventional techniques, therefore, can be used in the large-scale valorization of solid waste recycling and reuse to yield highly pure zeolite.

Feasibility Study on S-Band Microwave Radiation and 3D-Thermal Infrared Imaging Sensor-Aided Recognition of Polymer Materials from End-of-Life Vehicles.

With the increase the worldwide consumption of vehicles, end-of-life vehicles (ELVs) have kept rapidly increasing in the last two decades. Metallic parts and materials of ELVs can be easily reused and recycled, but the automobile shredder residues (ASRs), of which elastomer and plastic materials make up the vast majority, are difficult to recycle. ASRs are classified as hazardous materials in the main industrial countries, and are required to be materially recycled up to 85–95% by mass until 2020. However, there is neither sufficient theoretical nor practical experience for sorting ASR polymers. In this research, we provide a novel method by using S-Band microwave irradiation together with 3D scanning as well as infrared thermal imaging sensors for the recognition and sorting of typical plastics and elastomers from the ASR mixture. In this study, an industrial magnetron array with 2.45 GHz irradiation was utilized as the microwave source. Seven kinds of ELV polymer (PVC, ABS, PP, EPDM, NBR, CR, and SBR) crushed scrap residues were tested. After specific power microwave irradiation for a certain time, the tested polymer materials were heated up to different extents corresponding to their respective sensitivities to microwave irradiation. Due to the variations in polymer chemical structure and additive agents, polymers have different sensitivities to microwave radiation, which leads to differences in temperature rises. The differences of temperature increase were obtained by a thermal infrared sensor, and the position and geometrical features of the tested scraps were acquired by a 3D imaging sensor. With this information, the scrap material could be recognized and then sorted. The results showed that this method was effective when the tested polymer materials were heated up to more than 30 °C. For full recognition of the tested polymer scraps, the minimum temperature variations of 5 °C and 10.5 °C for plastics and elastomers were needed, respectively. The sorting efficiency was independent of particle sizes but depended on the power and time of the microwave irradiation. Generally, more than 75% (mass) of the tested polymer materials could be successfully recognized and sorted under an irradiation power of 3 kW. Plastics were much more insensitive to microwave irradiation than elastomers. With this method, the tested mixture of the plastic group (PVC, ABS, PP) and the mixture of elastomer group (EPDM, NBR, CR, and SBR) could be fully separated with an efficiency of 100%.

Investigation of the non-thermal effects of exposing cells to 70-300 GHz irradiation using a widely tunable source.

This study investigated the effects of millimeter wave (MMW) irradiation with a wide range of frequencies on the proliferation and activity of normal human skin fibroblast (NB1RBG) and human glioblastoma (A172) cells. Very few studies have focused on low-power, long-term irradiation of cells with a widely tunable source. Our research examined non-thermal effects on cells exposed to radiation at low power with tunable frequencies from 70 GHz to 300 GHz. A widely tunable MMW source was set within a cell culture incubator. To avoid the effect of heat generation due to irradiation, the intensity was maintained below 10 μW and the device was arranged such that the irradiation came from underneath the cells. Irradiation was performed by sweeping from 70 GHz to 300 GHz in 1.0 GHz steps. The MMW source was positioned 100 mm away from the container in which the cells were cultured. Cells were exposed to MMWs for either 3, 70 or 94 h. Measurements of cell proliferation were made using the alternating current measurement method. We found no difference in proliferation between cells exposed to MMWs and unexposed cells. A colorimetric method using novel tetrazolium compound: MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] was used for cell activity and cytotoxicity assays. We found no difference in cellular activity or toxicity between MMW-exposed cells and sham cells. Our study thus found no non-thermal effect as a result of exposure of cells to 70 GHz to 300 GHz of radiation.

Quasi-millimeter-wave absorption behavior in Y/Yb-stabilized zirconia ceramics

Broadband dielectric spectra from 10 to 1014 Hz were acquired for 8 mol. % Y2O3/Yb2O3-stabilized zirconia (8YSZ and 8YbSZ) ceramics that related the dipole and ionic polarization losses to the absorption efficiency of electromagnetic irradiation. For 24 GHz irradiation, 8YSZ exhibited a higher absorption efficiency than 8YbSZ, resulting in a higher dielectric loss. The difference in the dielectric loss was interpreted as the difference in the loss of the dipoles originating from the fluctuations in the defect associations (Y′ZrVo¨ and Yb′ZrVo¨).

Millimeter Wave-induced Modulation of Calcium Dynamics in an Engineered Skin Co-culture Model: Role of Secreted ATP on Calcium Spiking

We have previously designed and characterized a 94 GHz exposure system that allows real-time monitoring of subcellular interactions induced by millimeter wave (MMW) stimulation. For example, studies of the calcium dynamics in neuronal cells in response to 94 GHz irradiation suggested that MMW stimulation increased calcium spiking. In this study, we engineered a 3D co-culture model that represents the major constituents of skin. We used this experimental model along with the custom-designed MMW exposure system to investigate the effects of 94 GHz irradiation in the skin-like tissue construct. Unlike typical non-excitable cells, keratinocytes exhibited calcium spikes in their resting state. Exposure to a 94 GHz irradiation induced a statistically significant increase in the calcium spiking. When co-cultured with neuronal cells in the 3D co-culture skin model, changes in the calcium spiking in neuronal cells depended on the MMW input power. Further, the 94 GHz irradiation caused ATP secretion by keratincytes. ATP is a major factor that modulates the calcium spiking in neuronal cells. Surprisingly, while a 5-fold increase in the ATP secretion enhanced the calcium spiking in neuronal cells, a 10-fold increase significantly hindered the calcium dynamics. Computational simulation of ATP-induced calcium dynamics was in general agreement with the experimental findings, suggesting the involvement of the ATP-sensitive purinergic receptors. The engineered co-culture skin model offers a physiologically relevant environment in which the calcium dynamics is regulated both by the cell-MMW and cell-cell interactions.

Escherichia coli Membrane-Associated Energy-Dependent Processes and Sensitivity Toward Antibiotics Changes as Responses to Low-Intensity Electromagnetic Irradiation of 70.6 and 73 GHz Frequencies

Escherichia coli K-12(λ) was sensitive toward low-intensity (non-thermal, flux capacity 0.06 mW cm(-2)) electromagnetic irradiation (EMI) of extremely high frequency-70.6 and 73 GHz. 1 h exposure to EMI markedly depressed growth and cell viability of bacteria. Membrane-associated processes-total H(+) efflux and H(2) evaluation by whole cells during glucose fermentation were shown to be lowered as well. At the same time, the F(0)F(1)-ATPase activity of membrane vesicles was little depressed with 70.6 GHz irradiation only. This finding was in conformity with non-changed N,N'-dicyclohexylcarbodiimide-sensitive H(+) efflux. Furthermore, for understanding the different frequencies action mechanisms, the effects of antibiotics (chloramphenicol, ceftriaxone, kanamycin, and tetracycline) on irradiated cells growth and survival were determined. EMI with the frequencies of 70.6 and 73 GHz as with 51.8 and 53.0 GHz enhanced the sensitivity of bacteria toward antibiotics, but comparison revealed that each frequency had a different portion. Probably, EMI of specific frequency triggered changes in biological processes and afterward in growth and viability of bacteria, creating conditions when the action of antibiotics became facilitated.

Low-intensity electromagnetic irradiation of 70.6 and 73 GHz frequencies enhances the effects of disulfide bonds reducer on Escherichia coli growth and affects the bacterial surface oxidation–reduction state

Low-intensity electromagnetic irradiation (EMI) of 70.6 and 73GHz frequencies (flux capacity – 0.06mWcm−2) had bactericidal effects on Escherichia coli. This EMI (1h) exposure suppressed the growth of E. coli K-12(λ). The pH value (6.0–8.0) did not significantly affect the growth. The lag-phase duration was prolonged, and the growth specific rate was inhibited, and these effects were more noticeable after 73GHz irradiation. These effects were enhanced by the addition of DL-dithiothreitol (DTT), a strong reducer of disulfide bonds in surface membrane proteins, which in its turn also has bactericidal effect. Further, the number of accessible SH-groups in membrane vesicles was markedly decreased by EMI that was augmented by N,N′-dicyclohexycarbodiimide and DTT. These results indicate a change in the oxidation–reduction state of bacterial cell membrane proteins that could be the primary membranous mechanism in the bactericidal effects of low-intensity EMI of the 70.6 and 73GHz frequencies.

Nocturnal urinary melatonin levels and urine biochemistry in microwave-irradiated rats

The aim of this study was to explore whether, during the course of a 15 days-lasting experiment, a two hours per day and five days per week, 2.45 GHz microwave whole-body irradiation may substantially and therefore provably affect rats’ nocturnal urinary 6-hydroxy-melatonin sulphate (aMT6s) excretion and urinalysis parameters. The average whole-body specific absorption rate (SAR) equalled to 1.25 (± 0.36 SE) W/kg. To collect nocturnal urine samples, animals were held in individual metabolic cages every experimental night from 7:00 PM till 7:00 AM next day. The concentration of aMT6s in rat urine samples was determined by a direct radioimmunoassay. Bilirubin, ketones, and urine protein content have been determined via multiple-use reagent strips. In comparison to the sham-exposed group, no significant changes in body temperature and food or water intake were observed in the exposed group. A decline in aMT6s, determined in the exposed rats, was observed from day 8 to day 11 of the experiment (P < 0.05). The aMT6s level remained consistently low until the end of the experiment, but not significantly lower than the control values. The results of the urine samples biochemical workup failed to reveal any significant differences between the exposed and the control animal groups. The results of this study suggest that, under the above described experimental conditions, repeated 2.45 GHz irradiation could act as a stressor and therefore influence the melatonine balance in rat.

Switching and Hysteresis on the I-V Curves of Submicron BSCCO (2212) Bridges

In thin BSCCO (2212) whisker-based superconducting bridges with width and length ≤ 1 μm we observe random telegraph noise at discrete values of current. We show that the noise is associated with spontaneous processes of addition and removal of discrete vortex trains and reflects the regular structure of steps on the I–V curves. The average lifetime of the trains τ falls down with increasing temperature T in a complex way: intervals of steep drop (∼ an order of magnitude per Kelvin) are separated with a plateau of τ(T) with τ ∼ 10−2 s. The 70 GHz irradiation with 100 μW power results in the growth of the average switching frequency by 5 orders of magnitude; thus the HTSC bridges could be efficient detectors of microwave radiation. We discuss the peculiar features of τ(T).

THz Josephson properties of grain boundary YBaCuO junctions on symmetric, tilted bicrystal sapphire substrates

Superconducting Josephson junctions with high characteristic voltages (IcRn larger than 4 mV at 4.2 K) are fabricated by depositing YBa2Cu3O7−x on tilted sapphire bicrystal substrates, where the tilting axis is along the grain boundary. The good junction quality and low microwave losses in sapphire gave high frequency response well into the THz region. High quality YBa2Cu3O7−x epitaxial films were deposited on tilted sapphire substrates with CeO2 buffer layers by pulsed laser deposition. YBaCuO films have smaller tilt angles, from 1.0° up to 10.3°, compared to inclination angles of the substrates from 1.5° to 13.6°. X-ray diffraction shows only a single orientation of the films in the a-b plane, as well as an absence of a-axis particles and outgrowths. Critical temperatures as high as Tc=88.5−89.0K and ΔTc⩽1.5K were obtained in all films. The grain boundary in a common high-Tc superconducting junction is usually much less straight than in the in-plane rotated bicrystal substrate, depressing Josephson currents. The waviness of the artificial grain boundary in a tilted bicrystal film is three times less than in an in-plane (untilted) bicrystal. Tilted Josephson junctions of widths from 1.5 to 6 μm were tested at temperatures from 0.26 to 77 K. IcRn products as high as 4.5 mV were observed at T=4.2K. Shapiro steps were observed at voltages over 3 mV under 300 GHz irradiation. Josephson radiation from the tilted junction was measured at frequencies up to 1.7 THz by a cryogenic bolometer. Suppressing the critical current with a magnetic field can separate Josephson radiation and thermal radiation. A parabolic dependence of the response on bias voltage for thermal radiation corresponds to an increase of junction temperature from 260 mK at zero bias to 3 K at 1 mV bias.

Microwave radiation and sensing of Josephson junction with the log-periodic toothed trapezoid antenna of high T/sub c/ superconducting films

Using high temperature superconducting thin films, we designed and fabricated Josephson junctions associated with a log-periodic toothed trapezoid antenna. Microwave self-radiation from the Josephson junction was measured by using both a superheterodyne receiver at the center frequency of 22 GHz and an external waveguide system. In the case of junction incorporated with an antenna structure, there was a significant increase of power by an order of magnitude with respect to a junction without antenna. Under the 22 GHz irradiation, we observed distinctive Shapiro steps in the I-V measurement, which allowed as estimating the received power of the junction. The received power of the junction with an antenna exhibited as a large increase as that of a self-radiation. Our results indicate that a Josephson junction with an antenna is very effective for the microwave coupling between Josephson junction and free space. The combined device can be used either for a high power microwave source or for a high sensitive sensor.

Microwave processing and properties of Ce–Y–ZrO 2 ceramics with 2.45 GHz irradiation

Green samples of Ce–Y–ZrO 2 ceramics were sintered to 99.5% TD in a multimode cavity with 2.45 GHz radiation. A smaller and uniform grain structure was developed in microwave sintered samples compared to that by conventionally sintering due to enhanced densification and short sintering time. Microwave sintering produced higher flexural strength (1195 MPa) and fracture toughness (13.7 MPa m 1/2). And more of the zirconia tetragonal phase was obtained on examining the polished surfaces of the microwave-sintered samples.

Frequency-Locked Submillimeter Wave Generation from Josephson Junction Arrays

We fabricated a Josephson junction array with an additional inductive coupling line to detect the high frequency and power of Josephson self-radiation. The YBa2Cu3Oy Josephson junctions are fabricated by a pulsed laser deposition method on bicrystal MgO substrates. We measured the submillimeter wave and the Josephson self-radiation power in an external waveguide system. The Josephson junction arrays showed the resistively shunted junction (RSJ)-like current–voltage characteristics and good frequency-locking of Josephson self-radiation. As the number of Josephson junctions increased, the maximum detected power was increased. We observed the maximum frequency of above 6 THz for Josephson self-radiation in the array with 11 Josephson junctions from the Shapiro steps under 22 GHz irradiation.

Cardiovascular and thermal responses in rats during 94 GHz irradiation

We investigated the thermal distribution and cardiovascular effects produced by sustained exposure of rats to 94 GHz radio-frequency electromagnetic radiation (RFR). Sixteen ketamine-anesthetized Sprague-Dawley rats were exposed individually at a power density of 75 mW/cm2 under far-field conditions in E orientation. Irradiation began when colonic temperature was 37 °C and continued until death. Large, immediate increases in subcutaneous temperature on the irradiated side were accompanied by more moderate, delayed increases in colonic temperature. These body-temperature responses were similar to previous results obtained during 35 GHz RFR exposure. During irradiation, arterial blood pressure initially increased and then precipitously decreased until death. The heart rate increased throughout the exposure period. When comparing the results of these 94 GHz exposures with those in previous studies of lower RFR frequencies, it appears that the patterns of heart-rate and blood-pressure changes that occur before death are similar. We conclude that exposure to 94 GHz RFR produces extreme peripheral heating without similar levels of core heating and that this pattern of heat deposition is sufficient to produce circulatory failure and subsequent death. Bioelectromagnetics 20:264–267, 1999. Published 1999 Wiley-Liss, Inc.

Cardiovascular and thermal responses in rats during 94 GHz irradiation

We investigated the thermal distribution and cardiovascular effects produced by sustained exposure of rats to 94 GHz radio-frequency electromagnetic radiation (RFR). Sixteen ketamine-anesthetized Sprague-Dawley rats were exposed individually at a power density of 75 mW/cm2 under far-field conditions in E orientation. Irradiation began when colonic temperature was 37 degrees C and continued until death. Large, immediate increases in subcutaneous temperature on the irradiated side were accompanied by more moderate, delayed increases in colonic temperature. These body-temperature responses were similar to previous results obtained during 35 GHz RFR exposure. During irradiation, arterial blood pressure initially increased and then precipitously decreased until death. The heart rate increased throughout the exposure period. When comparing the results of these 94 GHz exposures with those in previous studies of lower RFR frequencies, it appears that the patterns of heart-rate and blood-pressure changes that occur before death are similar. We conclude that exposure to 94 GHz RFR produces extreme peripheral heating without similar levels of core heating and that this pattern of heat deposition is sufficient to produce circulatory failure and subsequent death.

Regional brain heating during microwave exposure (2.06 GHz), warm-water immersion, environmental heating and exercise

Nonuniform heating may result from microwave (MW) irradiation of tissues and is therefore important to investigate in terms of health and safety issues. Hypothalamic (Thyp), cortical (Tctx), tympanic (Tty), and rectal (Tre) temperatures were measured in rats exposed in the far field, k-polarization (i.e., head pointed toward the transmitter horn and E-field in vertical direction) to two power densities of 2.06 GHz irradiation. The high-power density (HPM) was 1700 mW/cm2 [specific absorption rate (SAR): hypothalamus 1224 W/kg; cortex 493 W/kg]; the low-power density (LPM) was 170 mW/cm2 (SAR: hypothalamus 122.4 W/kg; cortex 49.3 W/kg). The increase (rate-of-rise, in degrees C/s) in Thyp was significantly greater than those in Tctx or Tre when rats were exposed to HPM. LPM produced more homogeneous heating. Quantitatively similar results were observed whether rats were implanted with probes in two brain sites or a single probe in one or the other of the two sites. The qualitative difference between regional brain heating was maintained during unrestrained exposure to HPM in the h-polarization (i.e., body parallel to magnetic field). To compare the temperature changes during MW irradiation with those produced by other modalities of heating, rats were immersed in warm water (44 degrees C, WWI); exposed to a warm ambient environment (50 degrees C, WSED); or exercised on a treadmill (17 m/min 8% grade) in a warm ambient environment (35 degrees C, WEX). WWI produced uniform heating in the regions measured. Similar rates-of-rise occurred among regions following WSED or WEX, thus maintaining the pre-existing gradient between Thyp and Tctx These data indicate that HPM produced a 2-2.5-fold difference in the rate-of-heating within brain regions that were separated by only a few millimeters. In contrast, more homogeneous heating was recorded during LPM or nonmicrowave modalities of heating.

Millimeter Wave Mixing Properties of EuBa 2Cu 3O 7-δ Bicrystal Grain Boundary Junction Arrays

We report the millimeter wave mixing properties of high-T c superconductor Josephson junction arrays using a waveguide-to-microstrip converter in the 100 GHz frequency range. The junction arrays consist of 3 weak links fabricated from EuBa2Cu3O7-δ thin films grown on an MgO bicrystal substrate. In these junction arrays, Shapiro steps are observed in the presence of 100 GHz irradiation at intervals of 3 times the fundamental step voltage. Millimeter wave mixing with an input local oscillator frequency of 99.142 GHz and an input signal frequency of 99.880 GHz is detected as the IF output at 738 MHz. The IF output power peaks at voltages corresponding to those of the dynamic resistance dV/ dI. A mixing conversion efficiency of -24.1 dB is obtained for a 3-junction array.

Imitation of influence of plasma and neutron fluxes on graphite made plasma-facing components of plasma diagnostics in mm and sub-mm wavelength range

Carbon-graphite materials are proposed for manufacturing inner elements of mm and submm diagnostics in a fusion reactor (i.e., reflectors and antennae of different kinds). The investigations of influence of pulsed power plasma streams with a power density ⩾ 1 kJ/cm 2 on radiotechnical characteristics of these elements at frequencies 37.5, 75, 105, 694, 890 and 2520 GHz and neutron irradiation with a fluence ∼ 10 22 n/cm 2 on plane reflectors at a frequency 890 GHz were carried out. Results of our tests point out the prospect to use these materials for making the mentioned elements, especially in the case if similar materials will be used as the first wall protection.

Double-barrier tunnel junctions for quasiparticle mixers

Double-barrier niobium tunnel junctions with the middle electrode thinner than the London penetration depth were fabricated. Their I-V curves, annealing behavior, response to external magnetic field, and response to 230 and 350 GHz irradiation in mixer experiments is discussed. Junctions with an integrated tuning circuit designed for the 230 GHz frequency range gave double-sideband receiver noise temperatures of 100 K. Vertically stack arrays can be attractive for various applications. Compared to single-barrier devices possible drawbacks were noted. The I-V curve indicates heating and/or nonequilibrium effects. Double-barrier devices became nonuniform after thermal annealing at 200 °C. The response to the external magnetic field is more complex and considerably larger flux densities are needed to suppress Josephson effects.