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Electromagnetic Fields

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https://www.readbyqxmd.com/read/29155572/boosting-hot-electrons-in-hetero-superstructures-for-plasmon-enhanced-catalysis
#1
Jun Guo, Yin Zhang, Lin Shi, Yanfei Zhu, Megersa Feyissa Mideksa, Ke Hou, Wenshi Zhao, Dawei Wang, Meiting Zhao, Xiaofei Zhang, Jiawei Lv, Jianqi Zhang, Xiaoli Wang, Zhiyong Tang
Hetero-nanostructures featured with both strong plasmon absorption and high catalytic activity are believed to be ideal platforms to realize efficient light-driven catalysis. However, in reality it remains great challenge to acquire high performance catalysis in such hetero-nanostructures due to poor generation and transfer of plamson-induced hot electrons. In this report, we demonstrate that Au nanorod@Pd superstructures (Au@Pd SSs), where the ordered Pd nanoarrays are precisely grown on Au nanorod surfaces via solution-based seed-mediated approach, would be an excellent solution for this challenge...
November 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29151080/changes-in-u937-cell-viability-induced-by-stress-factors-possible-role-of-calmodulin
#2
K K Wojcik-Piotrowicz, J Kaszuba-Zwoinska, E Rokita, B Nowak, P Thor
Current studies were aimed to elucidate influence of magnetic field (MF) stimulation on cell viability and its effect on expression of calmodulin (CaM) and Hsp70 protein which plays a role of cell stress indicator and is a Ca(2+)-dependent CaM-binding protein. For the experimental model we have chosen U937 cell line exposed to chemical- and/or physical stress factors. Puromycin (PMC) was used as a chemical apoptosis inducer. Alternating (AC) (6.5rms mT, 35 Hz) magnetic field combined with 6 mT static (DC) component, or pulsed electromagnetic field (45 ± 5)mT, 50 Hz (PEMF) acted as physical stressors...
August 2017: Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society
https://www.readbyqxmd.com/read/29150613/a-study-of-the-ground-attachment-process-in-natural-lightning-with-emphasis-on-its-breakthrough-phase
#3
M D Tran, V A Rakov
Synchronized high-speed (124 or 210 kiloframes per second) video images and wideband electromagnetic field records of the attachment process were obtained for 4 negative strokes in natural lightning at the Lightning Observatory in Gainesville, Florida. The majority of imaged upward connecting leaders (UCLs) and upward unconnected leaders, inferred to be mostly initiated from trees, exhibited a pulsating behavior (brightening/fading cycles). UCLs, whose maximum extent ranged from 11 to 25 m, propagated in virgin air at speeds ranging from 1...
November 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29149059/a-high-performance-portable-transient-electro-magnetic-sensor-for-unexploded-ordnance-detection
#4
Haofeng Wang, Shudong Chen, Shuang Zhang, Zhiwen Yuan, Haiyang Zhang, Dong Fang, Jun Zhu
Portable transient electromagnetic (TEM) systems can be well adapted to various terrains, including mountainous, woodland, and other complex terrains. They are widely used for the detection of unexploded ordnance (UXO). As the core component of the portable TEM system, the sensor is constructed with a transmitting coil and a receiving coil. Based on the primary field of the transmitting coil and internal noise of the receiving coil, the design and testing of such a sensor is described in detail. Results indicate that the primary field of the transmitting coil depends on the diameter, mass, and power of the coil...
November 17, 2017: Sensors
https://www.readbyqxmd.com/read/29148897/oxidative-stress-response-in-sh-sy5y-cells-exposed-to-short-term-1800%C3%A2-mhz-radiofrequency-radiation
#5
Ana Marija Marjanovic Cermak, Ivan Pavicic, Ivancica Trosic
The exact mechanism that could explain the effects of radiofrequency (RF) radiation exposure at non-thermal level is still unknown. Increasing evidence suggests a possible involvement of reactive oxygen species (ROS) and development of oxidative stress. To test the proposed hypothesis, human neuroblastoma cells (SH-SY5Y) were exposed to 1800 MHz short-term RF exposure for 10, 30 and 60 minutes. Electric field strength within Gigahertz Transverse Electromagnetic cell (GTEM) was 30 V m(-1) and specific absorption rate (SAR) was calculated to be 1...
November 17, 2017: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
https://www.readbyqxmd.com/read/29146825/toroidal-plasmoid-generation-via-extreme-hydrodynamic-shear
#6
Morteza Gharib, Sean Mendoza, Moshe Rosenfeld, Masoud Beizai, Francisco J Alves Pereira
Saint Elmo's fire and lightning are two known forms of naturally occurring atmospheric pressure plasmas. As a technology, nonthermal plasmas are induced from artificially created electromagnetic or electrostatic fields. Here we report the observation of arguably a unique case of a naturally formed such plasma, created in air at room temperature without external electromagnetic action, by impinging a high-speed microjet of deionized water on a dielectric solid surface. We demonstrate that tribo-electrification from extreme and focused hydrodynamic shear is the driving mechanism for the generation of energetic free electrons...
November 16, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29145005/assessment-of-long-term-spatio-temporal-radiofrequency-electromagnetic-field-exposure
#7
Sam Aerts, Joe Wiart, Luc Martens, Wout Joseph
As both the environment and telecommunications networks are inherently dynamic, our exposure to environmental radiofrequency (RF) electromagnetic fields (EMF) at an arbitrary location is not at all constant in time. In this study, more than a year's worth of measurement data collected in a fixed low-cost exposimeter network distributed over an urban environment was analysed and used to build, for the first time, a full spatio-temporal surrogate model of outdoor exposure to downlink Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS) signals...
November 13, 2017: Environmental Research
https://www.readbyqxmd.com/read/29144283/large-purcell-enhancement-with-efficient-one-dimensional-collection-via-coupled-nanowire-nanorod-system
#8
Xueke Duan, Juanjuan Ren, Fan Zhang, He Hao, Guowei Lu, Qihuang Gong, Ying Gu
Combining the advantages of both gap surface plasmons and evanescent waves, we demonstrate simultaneously large Purcell enhancement and efficient one- dimensional collection of photons at subwavelength scale in the coupled nanowire- nanorod system. The spontaneous emission can be enhanced by thousands of times based on the excitation of gap surface plasmons with strongly localized electromagnetic field. Emitted photons are directly collected by subwavelength-confined evanescent modes and guided along the nanowire...
November 16, 2017: Nanotechnology
https://www.readbyqxmd.com/read/29143352/assessment-of-exposure-to-radio-frequency-electromagnetic-fields-from-smart-utility-meters-in-gb-part-ii-numerical-assessment-of-induced-sar-within-the-human-body
#9
Muhammad R A Qureshi, Yasir Alfadhl, Xiaodong Chen, Azadeh Peyman, Myron Maslanyj, Simon Mann
Human body exposure to radiofrequency electromagnetic waves emitted from smart meters was assessed using various exposure configurations. Specific energy absorption rate distributions were determined using three anatomically realistic human models. Each model was assigned with age- and frequency-dependent dielectric properties representing a collection of age groups. Generalized exposure conditions involving standing and sleeping postures were assessed for a home area network operating at 868 and 2,450 MHz...
November 16, 2017: Bioelectromagnetics
https://www.readbyqxmd.com/read/29140354/enhancement-of-raman-scattering-of-a-gaseous-medium-near-the-surface-of-a-silver-holographic-grating
#10
Dmitry V Petrov, Alexey R Zaripov, Nikita A Toropov
The Letter demonstrates a possibility to enhance the Raman scattering of a gaseous medium due to an enhanced electromagnetic field caused by the excitation of propagating surface plasmon polaritons (PSPPs) on a silver holographic grating. Efficiency of collinear and noncollinear schemes of PSPP excitation on a metal-gaseous medium interface was studied. When using a collinear scheme, we registered an eightfold enhancement of the Raman scattering of atmospheric nitrogen and oxygen, where the average gain near the PSPP-active surface was ∼4×10(3)...
November 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/29139285/subradiant-dipolar-interactions-in-plasmonic-nanoring-resonator-array-for-integrated-label-free-biosensing
#11
Yuzhang Liang, Hui Zhang, Wenqi Zhu, Amit Agrawal, Henri J Lezec, Lixia Li, Wei Peng, Yi Zou, Yan-Qing Lu, Ting Xu
With the development of advanced nanofabrication technologies over the last decade, plasmonic nanostructures have attracted wide attention for their potential in label-free biosensing applications. However, the sensing performance of nanostructured plasmonic sensors is primarily limited by the broad-linewidth features with low peak-to-dip signal ratio in the extinction spectra that result from strong radiative damping. Here, we propose and systematically investigate the in-plane and out-of-plane dipolar interactions in an array of plasmonic nanoring resonators that are from the spatial combination of classic nanohole and nanodisk structures...
November 15, 2017: ACS Sensors
https://www.readbyqxmd.com/read/29138675/benign-effect-of-extremely-low-frequency-electromagnetic-field-on-brain-plasticity-assessed-by-nitric-oxide-metabolism-during-poststroke-rehabilitation
#12
Natalia Cichoń, Piotr Czarny, Michał Bijak, Elżbieta Miller, Tomasz Śliwiński, Janusz Szemraj, Joanna Saluk-Bijak
Nitric oxide (NO) is one of the most important signal molecules, involved in both physiological and pathological processes. As a neurotransmitter in the central nervous system, NO regulates cerebral blood flow, neurogenesis, and synaptic plasticity. The aim of our study was to investigate the effect of the extremely low-frequency electromagnetic field (ELF-EMF) on generation and metabolism of NO, as a neurotransmitter, in the rehabilitation of poststroke patients. Forty-eight patients were divided into two groups: ELF-EMF and non-ELF-EMF...
2017: Oxidative Medicine and Cellular Longevity
https://www.readbyqxmd.com/read/29138434/generating-localized-plasmonic-fields-on-an-integrated-photonic-platform-using-tapered-couplers-for-biosensing-applications
#13
Gurpreet Singh, Renzhe Bi, U S Dinish, Malini Olivo
A theoretical design and analysis of a tapered-coupler structure on a silicon nitride integrated-photonic platform for coupling optical energy from a dielectric waveguide to a plasmonic tip is presented. The proposed design can be considered as a hybrid photonic-plasmonic structure that generally supports hybrid symmetric and asymmetric modes. Along the taper, one of the hybrid modes approaches the cut-off, while the other approaches the short-range surface plasmon mode that generates localized fields. Potential use of the proposed novel tapered-coupler plasmonic structure for highly sensitive biosensing applications using surface enhanced Raman scattering (SERS) and metal enhanced fluorescence (MEF) techniques is discussed...
November 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29138310/sparsity-enables-estimation-of-both-subcortical-and-cortical-activity-from-meg-and-eeg
#14
Pavitra Krishnaswamy, Gabriel Obregon-Henao, Jyrki Ahveninen, Sheraz Khan, Behtash Babadi, Juan Eugenio Iglesias, Matti S Hämäläinen, Patrick L Purdon
Subcortical structures play a critical role in brain function. However, options for assessing electrophysiological activity in these structures are limited. Electromagnetic fields generated by neuronal activity in subcortical structures can be recorded noninvasively, using magnetoencephalography (MEG) and electroencephalography (EEG). However, these subcortical signals are much weaker than those generated by cortical activity. In addition, we show here that it is difficult to resolve subcortical sources because distributed cortical activity can explain the MEG and EEG patterns generated by deep sources...
November 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29134998/2d-molybdenum-and-vanadium-nitrides-synthesized-by-ammoniation-of-2d-transition-metal-carbides-mxenes
#15
Patrick Urbankowski, Babak Anasori, Kanit Hantanasirisakul, Long Yang, Lihua Zhang, Bernard Haines, Steven J May, Simon J L Billinge, Yury Gogotsi
MXenes are a rapidly growing class of 2D transition metal carbides and nitrides, finding applications in fields ranging from energy storage to electromagnetic interference shielding and transparent conductive coatings. However, while more than 20 carbide MXenes have already been synthesized, Ti4N3 and Ti2N are the only nitride MXenes reported so far. Here by ammoniation of Mo2CTx and V2CTx MXenes at 600 °C, we report on their transformation to 2D metal nitrides. Carbon atoms in the precursor MXenes are replaced with N atoms, resulting from the decomposition of ammonia molecules...
November 14, 2017: Nanoscale
https://www.readbyqxmd.com/read/29133925/absorption-and-extinction-cross-sections-and-photon-streamlines-in-the-optical-near-field
#16
Moritz Striebel, Jӧrg Wrachtrup, Ilja Gerhardt
The optical interaction of light and matter is modeled as an oscillating dipole in a plane wave electromagnetic field. We analyze absorption, scattering and extinction for this system by the energy flow, visualized as streamlines of the Poynting vector. Depending on the dissipative damping of the oscillator, a part of the streamlines ends up in the dipole. Based on a graphical investigation of the streamlines, this represents the absorption cross section, and forms a far-field absorption aperture. In the near-field of the oscillator, a modification of the aperture is observed...
November 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29131166/achieving-electric-field-focusing-using-annular-metal-dielectric-multilayers
#17
Feng Wu
We present studies on an electric field focuser comprised of annular epsilon-near-zero metamaterials (ENZMs) and inner free space. According to effective medium theory, annular ENZMs can be realized via annular metal-dielectric multilayers. In practice, we choose silver and air to design the focuser. Our numerical simulations demonstrate that the electric field can be focused on a fixed point, regardless of the number and location of electromagnetic sources in annular multilayers, which might be helpful for laser ignition...
November 10, 2017: Applied Optics
https://www.readbyqxmd.com/read/29129601/on-chip-signal-amplification-of-magnetic-bead-based-immunoassay-by-aviating-magnetic-bead-chains
#18
Uddin M Jalal, Gyeong Jun Jin, Kyu Shik Eom, Min Ho Kim, Joon S Shim
In this work, a Lab-on-a-Chip (LOC) platform is used to electromagnetically actuate magnetic bead chains for an enhanced immunoassay. Custom-made electromagnets generate a magnetic field to form, rotate, lift and lower the magnetic bead chains (MBCs). The cost-effective, disposable LOC platform was made with a polymer substrate and an on-chip electrochemical sensor patterned via the screen-printing process. The movement of the MBCs is controlled to improve the electrochemical signal up to 230% when detecting beta-type human chorionic gonadotropin (β-hCG)...
November 6, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/29129049/dna-origami-directed-au-nanostar-dimers-for-single-molecule-surface-enhanced-raman-scattering
#19
Swati Tanwar, Krishna Haldar, Tapasi Sen
We demonstrate the synthesis of Au nanostar dimer with tunable interparticle gap and controlled stoichiometry as-sembled on DNA origami. Au nanostars with uniform and sharp tips were immobilized on rectangular DNA origami dimerized structures to create nanoantennas containing monomeric and dimeric Au nanostars. Single Texas red dye was specifically attached in the junction of the dimerized origami which acts as a Raman reporter molecule. The SERS enhancement factors of single Texas red dye located in the conjunction region in the dimer structures having inter-particle gaps of 7 nm and 13 nm are 2 × 1010 and 8 × 109, respectively, which are strong enough for single analyte detec-tion...
November 13, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29125197/iei-emf-provocation-case-studies-a-novel-approach-to-testing-sensitive-individuals
#20
Adam Verrender, Sarah P Loughran, Vitas Anderson, Lena Hillert, G James Rubin, Gunnhild Oftedal, Rodney J Croft
The etiology of Idiopathic Environmental Intolerance attributed to Electromagnetic Fields (IEI-EMF) is controversial. While the majority of studies have indicated that there is no relationship between EMF exposure and symptoms reported by IEI-EMF sufferers, concerns about methodological issues have been raised. Addressing these concerns, the present experiment was designed as a series of individual case studies to determine whether there is a relationship between radiofrequency-electromagnetic field (RF-EMF) exposure and an IEI-EMF individual's self-reported symptoms...
November 10, 2017: Bioelectromagnetics
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