The levels of blood lipid peroxidation, glutathione peroxidase, reduced glutathione, and vitamin C were used to follow the level of oxidative damage caused by 2.45 GHz electromagnetic radiation in rats. The possible protective effects of selenium and L-carnitine were also tested and compared to untreated controls. Thirty male Wistar Albino rats were equally divided into five groups, namely Groups A1 and A2: controls and sham controls, respectively; Group B: EMR; Group C: EMR + selenium, Group D: EMR + L-carnitine. Groups B–D were exposed to 2.45 GHz electromagnetic radiation during 60 min/ day for 28 days. The lipid peroxidation levels in plasma and erythrocytes were significantly higher in group B than in groups A1 and A2 (p<0.05), although the reduced glutathione and glutathione peroxidase values were slightly lower in erythrocytes of group B compared to groups A1 and A2. The plasma lipid peroxidation level in group A2 was significantly lower than in group B (p<0.05). Erythrocyte reduced glutathione levels (p<0.01) in group B; erythrocyte glutathione peroxidase activity in group A2 (p<0.05), group B (p<0.001), and group C (p<0.05) were found to be lower than in group D. In conclusion, 2.45 GHz electromagnetic radiation caused oxidative stress in blood of rat. L-carnitine seems to have protective effects on the 2.45-GHz-induced blood toxicity by inhibiting free radical supporting antioxidant redox system although selenium has no effect on the investigated values.

In this study, an ultra-wide band (UWB) energy harvesting circuit was proposed using the Greinacher rectifier circuit. The circuit was designed with Wilkinson power combiner (WPC) for use at two different radio frequency signal inputs. To enable broadband operation, the multisection Chebyshev impedance matching technique was applied in the branches of the WPC circuit. The center frequency was selected 2.2 GHz in the design. In terms of the parameters of reflection, transmission and isolation, the WPC circuit operates in the 0.4 GHz-3.4 GHz range and the percentage bandwidth has been calculated as 136%. In the designed Greinacher rectifier circuit, power conversion efficiency (PCE) was analyzed for different input powers. When load resistor selected as R = 1500 Ω, the PCE for the input power of 9 dBm was about 70%. The proposed circuit, where WPC and Greinacher rectifier circuits was used together for energy harvesting; was operated in the frequency ranges BW 1 = 0.4-0.81 GHz, BW 2 = 1.54-1.84 GHz, and BW 3 = 2.2 GHz-2.89 GHz. As a power combining application, dual power inputs were applied to the WPC circuit with frequencies of Eventually, approximately 70.5% PCE and 1.65 V output voltage were obtained.

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BackgroundThis research focused on the effects of low electric current (μE)-assisted sonic agitation of sodium hypochlorite on Enterococcus faecalis infected human root dentin.MethodsExtracted human canine roots were instrumented, sterilized, and experimentally contaminated with E. faecalis. After incubation for 21 days, the presence of the biofilm was confirmed by scanning electron microscopy (n = 3). Roots were randomly divided into seven groups according to decontamination procedures: G1: no treatment; G2: sterile saline; G3: 5.25% sodium hypochlorite; G4: passive ultrasonic irrigation; G5: EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK) agitation (EA); G6: μE agitation; and G7: μE-assisted sonic agitation. Fixed μE amperage and intensities were applied in G6 and G7. Following microbial sampling, bacterial colonies were counted using the direct plating method.ResultsBiofilm was not eradicated in any sample. The μE-assisted sonic agitation of sodium hypochlorite revealed the lowest cfu values (p<0.05), whereas there were no significant differences among the passive ultrasonic irrigation, EndoActivator and μE agitation alone (p>0.05).ConclusionsBased on available evidence, the following conclusions were drawn: The μE-assisted sonic agitation increased the antibiofilm efficiency of sodium hypochlorite than passive ultrasonic irrigation and EndoActivator. The μE-assisted sonic agitation on 5.25% sodium hypochlorite is not capable to eradicate biofilms at 10mA energy level in 60s.

In this study, a single‐stage and three‐stage Dickson rectifier circuits that would be able to perform RF energy harvesting were proposed. Operating frequency was selected as 1 GHz. The highest efficiency value was obtained at 7 dBm input power. The load resistance values for the input power were parametrically analyzed and the power conversion efficiency and output voltage were calculated. In the cases where the best performance was obtained, while a maximum power conversion efficiency of 70.5% was obtained in the single‐stage Dickson circuit, maximum 77% efficiency was obtained in the three‐stage circuit. In addition, in the cases where the highest efficiency was observed, the load resistance values were calculated as 5590 and 14 610 Ω at the single stage and three stages, respectively. The load resistance value used to obtain higher efficiency values in the three‐stage circuit is increasing. Moreover, it was observed that as the number of stages increased, the output voltage also increased linearly. The maximum output voltage which was 1.8 V in the single‐stage was measured as ~5.16 V in three‐stages.

Radio frequency energy harvesting (RFEH) circuits can convert the power of communication signals from radio frequencies (RF) in the environment into direct current and voltage (DC power). In this study, the Greinacher full-wave rectifier circuit topology was combined with a 180 hybrid ring (rat-race) coupler which was a passive RF/microwave circuit. Thus, higher RF-DC conversion efficiency was obtained. First, using the Greinacher rectifier topology, RFEH circuit operating at the center frequency of 1850 MHz was designed. Then, at this frequency, designing of the rat-race coupler having 1000 MHz bandwidth was made. The S-parameter measurements and simulation data of the designed coupler circuit were compared. Finally, the high efficiency rectifier circuit where these two circuits were used together was designed. The proposed rectifier circuit was constructed on 70 × 70 × 1.6 mm 3 FR4 substrate material with a permittivity of 4.3 (ε r = 4.3). The power conversion efficiency (PCE) of the rectifier circuit, which had 125 MHz bandwidth at the center frequency of 1850 MHz and was developed with rat-race coupler, was calculated as 71% at 4.7 dBm input power. In addition, with this study, at −15 dBm input power, which was a relatively low power level, 40% PCE value was obtained. K E Y W O R D S180 hybrid ring (rat-race) coupler, Greinacher full-wave rectifier, high efficiency rectifier topology

In recent years humans are more exposed to human-made fields than natural fields with developing technologies. Especially, widespread of wireless communication technologies in all areas of daily life and getting closer to sensitive organs like brain caused an increase in possible risks and worries about human health. In the study, a temperature measurement card has been designed and produced with the aim of observing the temperature rise at the phantom model generated by EM energy source. To that end, we present a study on the temperature rise of small dipole antenna (2450 MHz) that operate close to a user’s head (1, 4 and 7 cm). We found good correspondence between the temperature rise values evaluated in the phantom heads. According to the results of measure, expected temperature rise in the tissue exposed to RF energy may varies to the distance between radiated source and tissue.

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