Effect of 2450 MHz microwave exposure on behavioural thermoregulation in mice

1. 1.|The purpose of this study was to determine the threshold specific absorption rate (SAR) during exposure to 2450 MHz continuous wave (CW) microwaves that affected thermoregulatory behaviour in mice.

2. 2.|A Plexiglas shuttle box was placed inside a waveguide imposed with a temperature gradient. The temperature gradient allowed the mice to select a particular section of the shuttle box which was, presumably, related to their state of thermal comfort. Exposing the mice to 2450 MHz inside the waveguide at SARs of 0–5.3 W kg⁻¹ for 1 h caused no significant change in their preferred ambient temperature.

3. 3.|Increasing SAR from 5.3 to 18.1 W kg⁻¹ caused the animals to shift their position to the cooler end of the shuttle box.

4. 4.|Following termination of microwave exposure animals that had selected a cool ambient temperature returned to the warm side of the shuttle box.

5. 5.|It is concluded that for mice exposed to radiation at 2450 MHz the thermoregulatory behaviour is significantly affected at SARs of 5.3 to 9.9 W kg⁻¹.

Testicular function of rats following exposure to microwave radiation

Male Sprague-Dawley rats were exposed for 6 h per day for nine days to pulse-modulated microwave radiation (1.3 GHz, at 1-microseconds pulse width, 600 pulses per second). Exposures were carried out in cylindrical waveguide sections at a mean dose rate of 6.3 mW/g; sham controls were treated similarly and received no irradiation. At time periods corresponding to 0.5, 1.0, 2.0, and 4.0 cycles of the seminiferous epithelium, groups of four sham-irradiated and four irradiated rats were killed and the testes removed for analysis. Net mass of the testes, epididymides, and seminal vesicles; daily sperm production (DSP) per testis and per gram of testis; sperm morphology; and the number of epididymal sperm were determined. There were no statistically significant differences between the sham-irradiated and irradiated groups with respect to any measured variable. In a group of seven surrogate animals of similar body mass, the dose rate of 6.3 mW/g caused a net change in body temperature (via rectal probe) of 1.5 degrees C.     

Improvement of Nonradioactive DNA in Situ Hybridization

With the introduction of microwave pretreatment, the quality of nonradioactive in situ hybridization (NISH) using DNA probes on formalin fixed tissue has significantly improved. Even after microwave treatment, however, there are cases where NISH results remain unsatisfactory. Therefore, we tried to improve NISH by testing other buffer systems as alternatives to the citrate buffer that is routinely applied during microwave pretreatment. By using buffer systems originally designed for immunohistochemistry, we significantly improved our NISH results. Difficult tissue samples were more accessible to NISH using these alternative buffer systems and made the quantitative evaluation easier. These results may also be of interest for combined applications of NISH and immunohistochemistry.     

Microwave effect on diffusion: a possible mechanism for non-thermal effect

Abstract

In this study, we assume that microwave radiation affects hydrogen bonding between dipolar water molecules and through that diffusion in water at constant temperature. The experimental study was performed on the setup of two identical reservoirs filled with pure water and 0.9% NaCl solution and connected by a thin tube. Alterations of NaCl concentration in the reservoir initially filled with pure water were measured using the resistance of the solution as an indicator. The applied 450?MHz continuous-wave microwave field had the maximal specific absorption rate of 0.4?W/kg on the connecting tube. The standard deviation of water temperature in the setup was 0.02?°C during an experiment. Our experimental data demonstrated that microwave exposure makes faster the process of diffusion in water. The time required for reduction of initial resistance of the solution by 10% was 1.7 times shorter with microwave. This result is consistent with the proposed mechanism of low-level microwave effect: microwave radiation, rotating dipolar water molecules, causes high-frequency alterations of hydrogen bonds between water molecules, thereby affects its viscosity and makes faster diffusion.     

Elucidating the Role of a Tetrafluoroborate‐Based Ionic Liquid at the n‐Type Oxide/Perovskite Interface

Halide perovskites are currently one of the most heavily researched emerging photovoltaic materials. Despite achieving remarkable power conversion efficiencies, perovskite solar cells have not yet achieved their full potential, with the interfaces between the perovskite and the charge‐selective layers being where most recombination losses occur. In this study, a fluorinated ionic liquid (IL) is employed to modify the perovskite/SnO₂ interface. Using Kelvin probe and photoelectron spectroscopy measurements, it is shown that depositing the perovskite onto an IL‐treated substrate results in the crystallization of a perovskite film which has a more n‐type character, evidenced by a decrease of the work function and a shift of the Fermi level toward the conduction band. Photoluminescence spectroscopy and time‐resolved microwave conductivity are used to investigate the optoelectronic properties of the perovskite grown on neat and IL‐modified surfaces and it is found that the modified substrate yields a perovskite film which exhibits an order of magnitude lower trap density than the control. When incorporated into solar cells, this interface modification results in a reduction in the current–voltage hysteresis and an improvement in device performance, with the best performing devices achieving steady‐state PCEs exceeding 20%.     

Multifrequency Microwave Imaging for Brain Stroke Detection

CT and MRI are often used in the diagnosis and monitoring of stroke. However, they are expensive, time-consuming, produce ionizing radiation (CT), and not suitable for continuous monitoring stroke. Microwave imaging (MI) has been extensively investigated for identifying several types of human organs, including breast, brain, lung, liver, and gastric. The authors recently developed a holographic microwave imaging (HMI) algorithm for biological object detection. However, this method has difficulty in providing accurate information on embedded small inclusions. This paper describes the feasibility of the use of a multifrequency HMI algorithm for brain stroke detection. A numerical system, including HMI data collection model and a realistic head model, was developed to demonstrate the proposed method for imaging of brain tissues. Various experiments were carried out to evaluate the performance of the proposed method. Results of experiments carried out using multifrequency HMI have been compared with the results obtained from single frequency HMI. Results showed that multifrequency HMI could detect strokes and provide more accurate results of size and location than the single frequency HMI algorithm.     

Microwave irradiation for fixation and immunostaining of endothelial cells in situ

Using microwave irradiation during tissue fixation and immunostaining reduces sample preparation time and facilitates penetration of fixatives and antibody solutions into the tissues. This results in improved fixation and reduction of non-specific binding of antibodies, respectively. Experimental analyses of endothelial cells in blood vessels in situ have been limited because of the difficulty of tissue preparation. We report here a technique using intermittent microwave irradiation for blood vessel fixation and immunostaining the fixed tissues. Intermittent microwave irradiation during fixation reduced blood vessel contraction and resulted in well preserved morphology of blood vessels, especially the endothelial cells. Microwave irradiation also reduced non-specific binding of fluorescein-labeled antibodies. These microwave irradiation-assisted techniques are useful for analysis of endothelial cell function and for pathological study of blood vessels in situ.     

Microwave Fixation of Whole Fetal Specimens

This study compares microwave fixation of whole fetal specimens with conventional techniques performed at room temperature. All fetuses were obtained from the same pregnant rat; half of them were placed in neutral formalin for 15 min at room temperature, then irradiated for 2.5 min in a domestic microwave oven. The remaining fetuses were placed in neutral formalin at room temperature for 48 hr as a control. Both experimental and control groups were exposed to routine tissue processing for light microscopy and embedded in paraffin wax. Sections 5 μm thick were stained with hematoxylin and eosin. Our results showed that the microwave technique reduced the fixation time while providing thin sections that were equal to or better in quality than those in the control group.     

A facile microwave assisted green chemical synthesis of novel piperidino 2-thioxoimidazolidin-4-ones and their in vitro microbiological evaluation

A series of novel hybrid heterocyclic compounds, 3-(3-alkyl-2,6-diarylpiperin-4-ylidene)-2-thioxoimidazolidin-4-ones were synthesised and a comparative study was also carried out under microwave irradiation. The synthesised compounds were characterised by their melting points, elemental analysis, MS, FT-IR, one-dimensional NMR (1H, D₂O exchanged 1H and ¹³C), two dimensional HOMOCOSY and NOESY spectroscopic data. All the synthesised title compounds were screened for their in vitro antibacterial and antifungal activity against clinically isolated strains namely B. subtilis, M. luteus, S. typhii, S. paratyphii B, S. felxneri, P. vulgaris, A. niger, Mucor, Rhizopus and M. gypsuem and the results were discussed.