High Electromagnetic Field Research Articles

The process for making low density LAS surfactant detergent agglomerates using microwave heating

The internal structure of detergent surfactant agglomerates is modified using electromagnetic heating to produce a lower bulk density final product. The agglomerates are heated in a 1.8KW microwave waveguide heating applicator operating at license-free ISM frequency band of 2450MHz. The density of the agglomerates reduces significantly when exposed to high power electromagnetic fields. The effect of number of process variables such as input power initial moisture content over bulk density of detergent particles is studied. Three different input power levels (500W, 1KW & 1.6KW) are applied to the agglomerates and it has been observed that higher input powers raise the temperature of the agglomerates very quickly, hence reducing the required residence time of the sample. Agglomerates exposed to the highest input power (1.6KW) had the lowest bulk density. The temperature profile and residence time of the agglomerates during heating was continuously recorded. Experimental results obtained in the lab-based process will be used to design a full scale continuous mode applicator.

Hardening of Metal Product Surface Layers by the Combined Gas Discharge Plasma

The properties of a low-pressure combined gas discharge initiated in a resonator chamber near the surface of a metal workpiece subjected to the superposition of high electromagnetic and electrostatic fields have been studied. It has been shown that, when a constant potential is applied to the workpiece, a layer forms on its surface in which positive ions or electrons (depending on the sign of the potential) accelerate to an energy as high as several hundred electronvolts. The interaction between accelerated particles and the workpiece causes the liberation of heat in the surface layer, which is sufficient for its complete melting. If the applied potential is positive, a hardening nanostructure arises on the workpiece surface. The physical parameters of the combined gas discharge have been estimated.

The Application of Simulation Software in Teaching Electromagnetic Field Theory

Electromagnetic field theory is an important basic major course of the communication engineering. In the course of teaching electromagnetic field theory, a lot of complicated formula derivation and abstract concept are involved, which makes the course a recognized challenge to both teachers and students. In this paper, the high performance full wave electromagnetic field simulation software, namely High Frequency Structural Simulator (HFSS), is introduced. The application of HFSS in teaching electromagnetic field theory is discussed. Two examples are given to demonstrate the effectiveness of HFSS in improving teaching quality.

The Application of Simulation Software in Teaching Electromagnetic Field Theory

Electromagnetic field theory is an important basic major course of the communication engineering. In the course of teaching electromagnetic field theory, a lot of complicated formula derivation and abstract concept are involved, which makes the course a recognized challenge to both teachers and students. In this paper, the high performance full wave electromagnetic field simulation software, namely High Frequency Structural Simulator (HFSS), is introduced. The application of HFSS in teaching electromagnetic field theory is discussed. Two examples are given to demonstrate the effectiveness of HFSS in improving teaching quality.

A monolithically integrated butt-coupled 3D bulk CMOS Si photodetector array with a fiber couplers platform on a single-chip

A linear array of 55 butt-coupled three-dimensional (3D) photodetectors based on a silicon (Si) substrate is presented with a monolithically integrated tapered U-grooves platform for embedding strands of a fiber bundle into a Si chip. This structure enables a direct coupling of the fiber strands with a diameter of Ø30μm to the vertical photoactive areas of a Si detector array one by one. A vertically 3D large photoactive area ∼30μm×40μm+2(30μm×10μm) is formed separated from the n-i-p structure on the top side to achieve a high performance butt-coupled photodetector. The prototype is fabricated by employing 3D CMOS and MEMS technology on a p-type Si wafer. The implementation of 30μm-deep double-trench isolation with the formation of a shallow n+-p junction and SiO2-liner over the trench sidewalls as well as SU-8 filling of the trenches realizes a high efficiency detector isolation and a low dark current of 1.14nA at 2V reverse bias. The maximum photoresponsivities under illumination with 470nm, 525nm, and 631nm LEDs light are observed under the lowest incident light power. A low junction capacitance of ∼30+/−3fF at 2.4V reverse bias is measured at a frequency of 1MHz. Therefore, this approach brings outstanding features for non-telecom and high efficiency remote optical fiber sensor applications at the wavelengths of 470nm, 525nm, and 631nm in high electromagnetic field environments.

Exposure systems used in the assessment of EMF impact on living organisms

The subject of the study in the article is the processes of analysis and exposure assessment of electromagnetic field on humans. The main goal is to optimize size of the exposure antenna systems, its electrical parameters and generated electromagnetic field (EMF) for different frequency range. Objectives: Electromagnetic field (EMF – Electromagnetic Fields) studies on living organisms are one of the important branches of biomedical research. Most of this type of research is conducted using dedicated exposures system with fixed and controlled EMF exposure conditions. The purpose of biomedical research is to determine the influence of electromagnetic fields on living organisms. For this purpose the exposure systems are designed. The main task of the exposure antenna system, is to produce the EMF with known and controlled parameters in a specific EMF area. Depending on the frequency and the component (E or H) of the electromagnetic field used, different types of systems are used. For low frequencies (for instance 50 Hz common frequency) and magnetic fields, Helmholtz solenoids or coils are used, and for electric fields - flat capacitors (E Field). For higher frequencies field E is used for systems with linear antennas or TEM lines. There are also dedicated probes for invasive tissue heating. Each solution has its advantages and limitations and usually there are no universal solutions for all cases. Results: For the generation of a low frequency magnetic field up to several hundred Hz, the Helmholtz solenoid or coil is generally used because of its relatively simple construction, the ability to obtain high intensity and good homogeneity of the field in a relatively large area relative to the dimensions of the whole system. The homogeneous field area can be determined analytically based on system geometry or measurement. Otherwise it looks for exposure system above few MHZ. To create a homogeneous EMF in the field of radio frequencies, the exposure systems - usually the TEM lines (Crawford compartment) or sometimes the GTEM are very likely to be used. In both cases there are frequency and spatial limitations - the homogeneous field is assumed to be maximally present. At 1/3 the height between the plates of the chamber and at the same time the maximum frequency of operation of the TEM chamber can be described by the approximate dependence of fmax [MHz] = 50 / d [m], resulting in a chamber operating at 1 GHz. The work piece does not exceed a height of about1.5 cmwith a diameter of about4 cm. Larger working areas, but at the same time, a lower homogeneity of the field can be obtained in the GTEM chamber - but at the same time the GTEM chamber has much larger geometric dimensions. Another way is to produce PEM with the parameters in open space - in the vicinity of the antenna. In this case, it is very important to select an antenna so that the expected homogeneous area can be obtained at an acceptable distance from the antenna - in order to maintain high EMF intensity and to reduce the radiation of the antenna beyond the desired area. This can be achieved by limiting the emission area by, for example, shielding or using EMF absorbers. In addition authors simulate novel ablation antenna for ablation treatment. Conclusions: Assessing the impact of EMF on biological objects is an interdisciplinary studies that requires the involvement of biological or medical specialists, as well as the EMF standard field and metrology specialist. In this work we have taken the subject of correct selection and description used in the experience of exposure systems. The authors presented the most commonly used EMF emitters in the low frequencies and microwave bands, as well as new model of the ablation treatment antenna.

The expression of pluripotency and neuronal differentiation markers under the influence of electromagnetic field and nitric oxide.

Nitric oxide (NO) is a diatomic free radical compound that as a secondary messenger contributes to cell physiological functions and its variations influence proteins activity and triggering intracellular signaling cascades. Low frequency electromagnetic field (EMF) alters the cell biology such as cell differentiation by targeting the plasma membrane and entering force to the ions and small electrical ligands. The effect of these chemical (NO) and physical (EMF) factors on the expression of the stemness and neuronal differentiation markers in rat bone marrow mesenchymal stem cells (BMSC) was investigated. The cells were treated with low (50micromolar) and high (1mM) concentrations of Deta-NO as a NO donor molecule and 50Hz low frequency EMF. The expression of pluripotency and neuronal differentiation genes and proteins was investigated using real time qPCR and Immunocytochemistry techniques. The simultaneous treatment of EMF with NO (1mM) led to the down-regulation of stemness markers expression and up-regulation of neuronal differentiation markers expression. Cell proliferation decreased and cell morphology changed which caused the majority of cells obtains neuronal protein markers in their cytoplasm. The decrease in the expression of neuronal differentiation Nestin and DCX markers without any change in the expression of pluripotency Oct4 marker (treated with low concentration of NO) indicates protection of stemness state in these cells. Treatment with NO demonstrated a double behavior. NO low concentration helped the cells protect the stemness state but NO high concentration plus EMF pushed cells into differentiation pathway.

High-order multiphoton Thomson scattering

Electron–photon scattering, or Thomson scattering, is one of the most fundamental mechanisms in electrodynamics, underlying laboratory and astrophysical sources of high-energy X-rays. After a century of studies, it is only recently that sufficiently high electromagnetic field strengths have been available to experimentally study the nonlinear regime of Thomson scattering in the laboratory. Making use of a high-power laser and a laser-driven electron accelerator, we made the first measurements of high-order multiphoton scattering, in which more than 500 near-infrared laser photons were scattered by a single electron into a single X-ray photon. Both the electron motion and the scattered photons were found to depend nonlinearly on field strength. The observed angular distribution of scattered X-rays permits independent measurement of absolute intensity, in situ, during interactions of ultra-intense laser light with free electrons. Furthermore, the experiment's potential to generate attosecond-duration hard X-ray pulses can enable the study of ultrafast nuclear dynamics. More than 500 near-infrared laser photons are scattered by a single electron into a single X-ray photon. This is the first experimental evidence of high-order multiphoton Thomson scattering and validates the decades-old theoretical predictions.

Tamm plasmon modes on semi-infinite metallodielectric superlattices

We analyze the fundamental properties of optical waves referred to as Tamm plasmon modes (TPMs) which are tied to the interface of a semi-infinite two-phase metallodielectric superlattice with an arbitrary homogeneous capping medium. Such modes offer new ways of achieving high electromagnetic field localization and spontaneous emission enhancement in the vicinity of the interface in conjunction with absorption loss management, which is crucial for future applications. The homointerface, formed when the capping medium has the same permittivity as one of the superlattice constituents, is found to support a TPM whose dispersion overlaps the single-interface surface plasmon polariton (SPP) dispersion but which has a cut off at the topological transition point. In contrast, a heterointerface formed for an arbitrary capping medium, is found to support multiple TPMs whose origin can be traced by considering the interaction between a single-interface SPP and the homointerface TPM burried under the top layer of the superlattice. By carrying out a systematic comparison between TPMs and single-interface SPPs, we find that the deviations are most pronounced in the vicinity of the transition frequency for superlattices in which dielectric layers are thicker than metallic ones.

Optical bistability in graphene-wrapped dielectric nanowires.

We study the optical bistability of graphene-wrapped dielectric cylinders with Kerr-type nonlinear response within the framework of both nonlinear full-wave scattering theory and nonlinear quasistatic theory. Typical optical bistable properties are observed in both near-field and far-field spectra with the excitation of electric dipolar modes. Moreover, when high electromagnetic field is applied, nonlinear full wave theory yields new bistable region, indicating the existence of an artificial tunable magnetic dipole. The switching threshold fields are found to be tunable by changing either the size, permittivity of the nanocylinder or the chemical potential of graphene. Our results offer insight into the interaction between Kerr-type nonlinearity and graphene plasmonics, and may promise the graphene-wrapped nanowire a candidate for all-optical switching and nano-memories in terahertz region.

Mobile phone use, school electromagnetic field levels and related symptoms: a cross-sectional survey among 2150 high school students in Izmir

BackgroundHealth outcomes of electromagnetic fields (EMF) from mobile phones and their base stations are of concern. Conducting multidisciplinary research, targeting children and exploring dose-response are recommended. Our objectives were to describe the mobile phone usage characteristics of high school students and to explore the association between mobile phone usage characteristics, high school EMF levels and self-reported symptoms.MethodsThis cross-sectional study’s data were collected by a survey questionnaire and by measuring school EMF levels between November 2009 and April 2011. A sample size of 2530 was calculated from a total of 20,493 students in 26 high schools and 2150 (85.0%) were included in the analysis. The frequencies of 23 symptoms were questioned and analysed according to 16 different aspects of mobile phone use and school EMF levels, exploring also dose-response. School EMF levels were measured with Aaronia Spectran HF-4060 device. Chi square and trend tests were used for univariate and logistic regression was used for multivariate analyses.ResultsAmong participants, 2021 (94.0%) were using mobile phones and 129 (6.0%) were not. Among users, 49.4% were speaking <10 min and 52.2% were sending/receiving 75 or more messages per day. Headache, fatigue and sleep disturbances were observed respectively 1.90 (95% CI 1.30–2.77), 1.78 (1.21–2.63) and 1.53 (1.05–2.21) times more among mobile phone users. Dose-response relationships were observed especially for the number of calls per day, total duration of calls per day, total number of text messages per day, position and status of mobile phone at night and making calls while charging as exposures and headache, concentration difficulties, fatigue and sleep disturbances as general symptoms and warming of the ear and flushing as local symptoms.ConclusionsWe found an association between mobile phone use and especially headache, concentration difficulties, fatigue, sleep disturbances and warming of the ear showing also dose-response. We have found limited associations between vicinity to base stations and some general symptoms; however, we did not find any association with school EMF levels. Decreasing the numbers of calls and messages, decreasing the duration of calls, using earphones, keeping the phone away from the head and body and similar precautions might decrease the frequencies or prevalence of the symptoms.

Impact of high strength electromagnetic fields generated by Tesla transformer on plant cell ultrastructure

Non-thermal effects of direct electric fields and alternating electromagnetic fields (EMF) have been successfully used in a number of studies and applications in agriculture and biotechnology. Among different kinds of high strength EMF generators, the Tesla transformer (TT) is known as a widely applied, low cost, and troubleproof device, which generates EMF in the range of 2–8MHz. Despite of a number of developed and perspective applications of high strength EMFs in agriculture and biotechnology, the EMFs generated by TT, as well as the 1–50MHz range of high strength EMF still remain unexplored in the fields of plant physiology, ultrastructure studies and biochemistry. In this work, we have shown that TT-EMFs (4MHz) induced fast stem and petiole bending, disappearance of cell organelles, vacuolar membranes, and increase of a non-photochemical chlorophyll fluorescence quenching in petioles. It is intriguing that such fatal effects can be evoked in plants by EMFs which are well known as harmless for man at the applied strength and frequency.

Branched Nanostructure for Dual-Model Imaging

Single-model imaging can hardly provide sufficient information to clearly describe cellular behaviors, thus dual-model probes have been intensively studied for multiplex bio-detection and bio-imaging. Here, we developed a series of branched Au nanostructures with different surface modifications, which enabled dark-field microscopy (DFM) and surface-enhanced Raman scattering (SERS) imaging, owning to their high electromagnetic fields around the nanostructures. Moreover, we found that nanostructures modified with DNA and Arg–Gly–Asp (RGD) peptide could be internalized by cells efficiently and well distributed in cells without aggregation. These results demonstrate the potential of the nanostructures in applications like cell imaging and drug delivery.

Monitoring the transformation of aliphatic and fullerene molecules by high-energy electrons using surface-enhanced Raman spectroscopy

We report on using 100 keV electrons to obtain amorphous carbon from aliphatic and fullerene molecules, and study this process by monitoring their Raman signal. In this regard, we use self-assembled monolayers of gold nanoparticles to provide high electromagnetic field enhancement, which allows the detection of the Raman signal from even nanometer-thick layers of analyte. Our results show different dynamics in the amorphization process of the two molecules, although both show suppression of their original vibrational resonances even at low exposure doses. We have also used atomic-force microscopy to evaluate the sensitivity of the C60 molecules to electron beams in forming networks of amorphized molecules that are less soluble in the development process. This method allows precise patterning possibilities as well as in situ functionalization of carbonaceous thin films in the perspective of using in electronic device applications.

Detection of surface-linked polychlorinated biphenyls using surface-enhanced Raman scattering spectroscopy

We present an improved procedure for analytical detection of toxic polychlorinated biphenyls (PCB) using surface-enhanced Raman scattering (SERS) spectroscopy. A gold-capped silicon nanopillar substrate was utilized to concentrate PCB molecules within an area of high electromagnetic fields through formation of microsized nanopillar clusters, and consequently, so-called “hot spots” can be formed. In order to improve PCB detection limit, 3,3′,4,4′-tetrachlorobiphenyl (PCB77) compounds were chemically modified with a SCH3 (PCB77-SCH3) group. Experimental and numerical analysis of vibrational modes showed only minor differences between standard PCB77 and PCB77-SCH3. Consequently, we observe significantly increased SERS signals for SCH3 modified PCB77 while retaining most vibrational modes that characterize standard PCB77. Results point towards more efficient path for detecting different PCB congeners from real-life samples. We interpret the result as PCB77SCH3 link to gold surface via sulfur atoms that facilitates accumulation of the modified PCB molecules on the metal surface. For similar SERS experimental conditions most spectral characteristics of PCB77 are identifiable down to concentrations of ∼10−5M while PCB77SCH3 spectral fingerprint is retained in ∼10−8M range.

Transcranial magnetic stimulation (TMS) coil designing for high electromagnetic field gradient generation

Transcranial magnetic stimulation (TMS) coil designing for high electromagnetic field gradient generation

High-intensity laser therapy versus pulsed electromagnetic field in the treatment of primary dysmenorrhea

[Purpose] To determine the efficacy of high intensity laser therapy (HILT) versus pulsed electromagnetic field (PEMF) in the treatment of primary dysmenorrhea. [Subjects and Methods] This was a randomized clinical trial that included 52 girls diagnosed with primary dysmenorrhea and who were assigned randomly into two groups of equal numbers. The treatment was three sessions every cycle for three consecutive cycles where group (A) included those participants treated with HILT 15 min/session and group (B) those who were treated with PEMF 30 min/session. All patients were evaluated before starting the treatment as well as after the end of treatment by present pain intensity scale and the prostaglandin level in blood and pain relief scale at the end of treatment for both groups. [Results] The results showed a significant decrease in the severity of pain, statistically significant decrease in prostaglandin level in blood, and a statistically significant pain alleviation in both groups. With comparison between both groups there was a statistically significant decrease in the severity of pain, significant decrease in the blood levels of PGF2α, in group (A) than group (B). [Conclusion] Both HILT and PEMF are effective in the treatment of primary dysmenorrhea with HILT being superior to PEMF.

Pumping electrons in graphene to theMpoint in the Brillouin zone: Emergence of anisotropic plasmons

We consider the existence of plasmons in a non-equilibrium situation where electrons from the valence band of graphene are pumped to states in the Brillouin zone around the $\mathbf{M}$-point by a high intensity UV electromagnetic field. The resulting out-of-equilibrium electron gas is later probed by a weak electromagnetic field of different frequency. We show that the optical properties of the system and the dispersion of the plasmons are strongly anisotropic, depending on the pumping radiation properties: its intensity, polarization, and frequency. This anisotropy has its roots in the saddle-like nature of the electronic dispersion relation around that particular point in the Brillouin zone. It is found that despite the strong anisotropy, the dispersion of the plasmons scales with the square root of the wave number but is characterized an effective Fermi energy, which depends on the properties of the pumping radiation. Our calculations go beyond the usual Dirac cone approximation taking the full band structure of graphene into account. This is a necessary condition for discussing plasmons at the $\mathbf{M}$-point in the Brillouin zone.

Analyzing Exposures to Electromagnetic Fields in an Intensive Care Unit.

In this study, we conducted a numerical analysis of exposure to electromagnetic fields (EMFs) in a hospital's intensive care unit that is one of the most crucial one in terms of hazardous areas among all service units. This is a new study for measuring exposure to EMFs in an intensive care unit as well as other healthcare services in Turkey. We measured the EMFs in the intensive care unit with a SRM-3006 (selective radiation metre), which was used for measurement of the absolute and the limit values of high frequency EMFs. The measurement points were chosen to represent the highest levels of exposure to which a person might be subjected. We obtained a dataset that included 5929 observations, with 96 extreme values, through measuring the magnetic field in terms of V/m. The measurements show the frequency varies from 47 MHz to 2.5 GHz as 17 frequency ranges at the measurement point as well. According to these findings, the referenced maximum safety limit was not exceeded. However, it was also found that mobile telecommunication was the most critical cause of magnetic fields. Further studies need to be performed with different frequency antennas to assess the EMFs in intensive care units.

Dynamical equations and transport coefficients for the metals at high pulse electromagnetic fields

We offer a metal model suitable for the description of fast electrophysical processes in conductors under influence of powerful electronic and laser radiation of femto- and picosecond duration, and also high-voltage electromagnetic pulses with picosecond front and duration less than 1 ns. The obtained dynamic equations for metal in approximation of one quasineutral liquid are in agreement with the equations received by other authors formerly. New wide-range expressions for the electronic conduction in strong electromagnetic fields are obtained and analyzed.