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Magnetic resonance imaging (MRI) is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within your body. MRI is safe, but if something goes wrong, it can go very wrong. Most reported cases of MRI-related injuries and the few fatalities that have occurred have apparently been the result of failure to follow safety guidelines or of use of inappropriate or outdated information related to the safety aspects of biomedical implants and devices. To prevent accidents in the MRI environment, therefore, it is necessary to revise information on biologic effects and safety according to changes that have occurred in MRI technology and with regard to current guidelines for biomedical implants and devices. This review provides an overview of and update on MRI biologic effects, discusses new or controversial MRI safety topics and issues, and presents evidence-based guidelines to ensure safety for patients and staff.

The present study has investigated the potential effects of extremely low frequency (ELF) electric field exposure on plasma cholesterol and triglyceride levels of adult male rats. Sixty rats have been divided into three independent groups randomly, 20 of which arranged as controls (without exposure to 50 Hz electric field), 20 of which have been exposed to a 50 Hz electric field for 10 days and 20 of which have been exposed to a 50-Hz electric field for 30 days. Levels of total cholesterol and triglyceride in plasma samples have been measured. Total cholesterol concentration of the plasma in group 2 with short-term exposure and group 3 with long-term exposure to 50 Hz EF (65.33 ± 15.31 mg/dL and 59.55 ± 15.01 mg/dL, respectively) has showed significant decrease when compared with control groups (70.44 ± 19.60 mg/dL). Also, plasma triglyceride showed similar changes (control: 84.44 ± 16.79 mg/dL, 67.33 ± 15.63 and 51.53 ± 14.17 mg/dL in group 1 and 2, respectively). Fifty Hz electric field may decrease plasma total cholesterol and triglyceride levels in rodents significantly, especially with long-term exposure.

The aim of this study was to investigate possible effects of 50 Hz-1 mT magnetic field (MF) on action potential in isolated rat sciatic nerve. We used 16 Wistar rats in the study. They were divided into control (n ¼ 10) and MF (n ¼ 6) groups. The sciatic nerve of left legs in the MF group was exposed to 50 Hz-1 mT MF for 30 min by using a Helmholtz applicator and then action potentials in control and experimental groups were recorded extracellularly. Maximum amplitude and hyperpolarization time and action potential were significantly (p 0.025) lower in the MF group than in control. However, conduction time, minimum amplitude, depolarization and repolarization times of the action potential was not different between control and MF groups evaluated. In conclusion, 50-1 mT MF caused to decrease amplitude value and hyperpolarization time of action potential in the rat nerve.

The aim of the present study is to investigate whether or not pulsed electric field (PEF) affects some hematological parameters in rats. Sixteen healthy male Wistar rats weighting 150-200 g were used and were randomly divided into two groups. Exposure group (n = 8) was exposed to a PEF (10 kV m⁻¹ for 1 h d⁻¹) for 10 consecutive days. The control group rats (n = 8) were not exposed to PEF. The following hematological parameters were measured in both the groups: white blood cells (WBCs), red blood cells (RBCs), hemoglobin (Hb), hematocrit (Ht) and platelets (PLTs). Some of the hematological parameters under investigation were similar in both the groups. Exposure group, exposed for 1 h d⁻¹ during 10 consecutive days, induced a significant increase in the rates of WBC (p < 0.05), RBC (p < 0.05), Hb (p < 0.05), Ht (p < 0.05) and PLTs (p < 0.05) in blood when compared with control. These results suggest that PEFs affect the hematological parameters in rat. Results of the parameters are statistically significant.

Lately, it has been seen that wireless communication systems have been more developed and there has been a huge demand for multi-spectral transactions. Using circuits for more than one function is a serious requirement in communication technology. Especially, it expected from RF output stages to show the same performance on more than one frequency. To that end, it is required to produce a solution with wideband designs. In this study, a novel power divider/combiner design with a layered conic line has been investigated for the RF energy harvesting applications. The center frequency was set at 2 GHz and concluded with three different designs. In each design, bandwidth and S parameter characteristics were compared according to the number of layers of the transmission, and it was observed that as the number of layers increases, the bandwidth also increases. According to the design result, triple layer Wilkinson power divider was selected to connect to Villard voltage doubler circuit. The Wilkinson power combiner circuit inputs were given between −10 dBm and 5 dBm input power. As a result, when low input power was given, efficiency was observed about 70%. K E Y W O R D S impedance matching, RF energy harvesting, Villard voltage Doubler, Wilkinson power divider/combiner

ÖZETİyonize olmayan elektromanyetik radyasyonun insan sağlığı üzerindeki etkileri, son elli yılda manyetik alanların kullanım alanının genişlemesi ile birlikte, büyük bir araştırma konusu olmuştur. Manyetik alanların tabiatı çok iyi bilinmekle beraber, insan vücudunun karmaşık yapısı, bu etkilerin incelenmesini zorlaştırmaktadır. Bununla beraber yapılan deneysel ve teorik çalışmaların sonucunda, manyetik alanların insan sağlığı üzerindeki etkileri konusunda kayda değer bulgular elde edilmiştir. Ancak, henüz bilinmeyen etkilerinin olabileceği konusunda da şüpheler mevcuttur. Bu çalışmanın amacı, insan medyan motor sinir ileti çalışmalarında elde edilen parametrelere, 50 Hz-1 mT manyetik alanın etkisini incelemektir. Bu frekansta 1 mT manyetik alan yoğunluğunun değeri, biyolojik etkileşimin başladığı sınır değer olarak bilinmekte ve kabul edilmektedir. Medyan sinirini değerlendirmek amacı ile, sabit ölçülü mesafelerin kullanıldığı standart iletim teknikleri uygulanmıştır. Sonuç olarak 4 kanal NCS/EMG/EPS cihazı kullanılarak yapılan ölçümlerde, manyetik alan uygulama sonrasındaki motor distal genlik, uygulama sırasındaki motor distal genliğe göre (p=0,000573) ve uygulama sonrasın-daki motor distal genlik/proksimal genlik oranı, manyetik alan uygulama öncesindeki motor distal genlik/proksimal genlik oranına göre anlamlı bir azalma göstermiştir (p=0,037418). Anahtar kelimeler : Manyetik alan, Medyan sinir, Motor distal genlik, Motor proksimal genlik. ABSTRACTWith the increasing use of magnetic fields in recent five decades, the health effects of nonionized electromagnetic radiation is an important investigation subject. While the magnetic field is well known, it is difficult to investigate the health effects of radiation, because of the complex metabolism of human body. However, by the experimental and theorical studies, a lot of significant health effects of magnetic fields have been discovered. But, there are probabilities that can have much more adverse health effects. The purpose of this study is to evaluate the effect of 50 Hz-1 mT magnetic field on human median motor nerve conduction parameters. At this frequency, 1 mT value of magnetic field intensity is known and accepted as the marginal value where biological interaction starts. Standard nerve conduction techniques using constant measured distances were applied to evaluate the median nerve. Consequently in the measures conducted using the device of 4 channel NCS/EMG/ EPS there was a significant decrease in motor distal amplitude after the magnetic field application in comparison to the one during the application (p=0,000573) and also in the motor distal amplitude/ proximal amplitude in comparison to the ones before the application (p=0,037418).

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.