scholarly journals Nanoferrofluid Materials: Advanced Structure Monitoring Using Optical Transmission in a Magnetic Field

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Serhii Shulyma ◽  
Bogdan Tanygin ◽  
Valery Kovalenko ◽  
Michail Petrychuk
Keyword(s):  
Magnetic Field ◽  
Optical Transmission ◽  
Structural Parameters ◽  
Aggregate Size ◽  
Spatial Dimension ◽  
Laser Wavelength ◽  
Time Interval ◽  
Field Pulse ◽  
Optical Extinction ◽  
Nanoparticle Aggregates

The optical transmission of a thin ferrofluid layer was investigated at various optical radiation wavelengths. The turning on of the durable external magnetic field pulse leads to nonmonotonic changes of the optical transmission value with minimal value during the field pulse. This phenomenon is related to the formation of columnar nanoparticle aggregates and transformation in the ferrofluid bulk. It was shown that time interval corresponding to the optical transmission minimum is proportional to the laser wavelength, which can be explained with Mie-like optical extinction on the ferrofluid aggregates and its dependence on the diameters of columnar aggregates. Hence, a simple experimental approach was proposed to measure and control the ferrofluid aggregates diameters in submicron spatial dimension ranges. Particularly, this approach could be used for the formation of composite nanomaterials consisting of polymers and magnetic nanoparticles with controlled structural parameters. These materials could be reused after parameters changes (e.g., lattice constant, aggregate size, and magnetic permeability tensor) with a heating/cooling cycle without the need for preparation of a new material from scratch.

Time dependent magnetically induced variations in optical transmission of magnetite nanoparticle aqueous suspension

Open Physics ◽  
2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Serhiy Malynych ◽  
Iryna Moroz
Keyword(s):  
Magnetic Field ◽  
Optical Transmission ◽  
Aqueous Suspension ◽  
Fast Response ◽  
Time Dependent ◽  
Time Interval ◽  
Particle Rotation ◽  
Magnetite Nanoparticle ◽  
Dc Magnetic Field ◽  
The Magnetic Field

AbstractWe observe time dependent variations in the light intensity transmitted through an aqueous suspension of Fe3O4 nanoparticles caused by applied DC magnetic field. Two types of variations can be distinguished. Fast response takes less than 1ms while slow variations occur at the time interval fromseconds to hundreds of minutes. Possible mechanisms of these variations are discussed. Formation of chain-like structures consisted from iron oxide nanoparticles is responsible for the slow variations. It is also accompanied by a diffraction pattern when the magnetic field is orthogonal to the light beam. Fast variations are due to particle rotation and reorientation of the magnetic moment inside a nanoparticle.

scholarly journals Design, Analysis and Test of a Hyperbolic Magnetic Field Voice Coil Actuator for Magnetic Levitation Fine Positioning Stage

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1830
Author(s):  
Yiheng Zhou ◽  
Baoquan Kou ◽  
He Zhang ◽  
Lu Zhang ◽  
Likun Wang
Keyword(s):  
Magnetic Field ◽  
High Precision ◽  
Magnetic Levitation ◽  
Structural Parameters ◽  
Industrial Applications ◽  
Degree Of Freedom ◽  
Force Density ◽  
Precision Positioning ◽  
Element Analysis ◽  
Voice Coil Actuator

The multi-degree-of-freedom high-precision positioning system (MHPS) is one of the key technologies in many advanced industrial applications. In this paper, a novel hyperbolic magnetic field voice coil actuator using a rhombus magnet array (HMF-VCA) for MHPS is proposed. Benefiting from the especially designed rhombus magnet array, the proposed HMF-VCA has the advantage of excellent force uniformity, which makes it suitable for multi-degree-of-freedom high-precision positioning applications. First, the basic structure and operation principles of the HMF-VCA are presented. Second, the six-degree-of-freedom force and torque characteristic of the HMF-VCA is studied by three-dimensional finite element analysis (3-D FEA). Third, the influence of structural parameters on force density and force uniformity is investigated, which is conducive to the design and optimization of the HMF-VCA. Finally, a prototype is constructed, and the comparison between the HMF-VCA and conventional VCAs proves the advantage of the proposed topology.

Motion and Switching of Dual-Vortex Cores in Elliptical Permalloy Nanodisk Stimulated by a Gaussian Magnetic Field Pulse

2017 ◽  
Vol 53 (5) ◽  
pp. 1-6
Author(s):  
X. Li ◽  
Y. Zhou ◽  
T. Zeng ◽  
K. -W. Lin ◽  
P. T. Lai ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Field Pulse ◽  
Field Pulse

Theory of ground-state switching in an array of magnetic nanodots by application of a short external magnetic field pulse

2013 ◽  
Vol 87 (13) ◽  
Author(s):  
Roman Verba ◽  
Vasil Tiberkevich ◽  
Konstantin Guslienko ◽  
Gennadiy Melkov ◽  
Andrei Slavin
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Ground State ◽  
Magnetic Field Pulse ◽  
Field Pulse ◽  
Magnetic Nanodots ◽  
State Switching

Evaluation of Effect of Nd:YAG and Er:YAG Lasers on the Periodontal Pathogens: A Systematic Review

2020 ◽  
Author(s):  
Hosein Eslami
Keyword(s):  
Systematic Review ◽  
Chronic Periodontitis ◽  
Complementary Therapy ◽  
Root Surface ◽  
Laser Wavelength ◽  
Time Interval ◽  
Periodontal Pathogens ◽  
Probing Depth ◽  
Treatment Procedures ◽  
The Given

Introduction: By removing the periodontal pathogens and even the invasive bacteria attacking the tissues as well as the lack of normal periodontal treatment procedures, using a laser, as a complementary therapy, can have positive and useful impacts. The present study aims at investigating the impacts of Nd:YAG and Er:YAG laser on periodontal pathogens. Materials and Methods: In this systematic review, articles in the databases of Google Scholar, PubMed and Scopus were searched within 2000-2020. All information is classified into a table. Results: In searching the aforementioned databases and considering the given time interval, 78 articles were found in connection to the searched keywords and abstracts. Once the repeated titles and articles were deleted, 25 studies were selected which were decreased to 16 by the meticulous review by the assessment team. The full text of these 16 articles was reviewed. To make the final choice, 8 articles had the inclusion criteria which included the objectives of this study. Conclusion: To use the laser in treating the chronic periodontitis, an evidence-based study seems to be conducted. A few scientific pieces of evidence are indicating the advantage of a special laser wavelength in the common treatments.Based on most researches reviewed in this study, the results of the complementary application of Nd:YAG and Er:YAG lasers in treating the chronic periodontitis are the better than the ones obtained from the normal teeth scaling and planning the teeth root surface in terms of the reduced probing depth and subgingival bacteria population. The decision was made to use the laser in periodontal surgery based on the advantages such as hemostasis and less pain after the treatment. However, more studies are needed to apply the laser in periodontal treatments.

The variability of naturally occurring magnetic field levels: 10 Hz to 8 kHz

Geophysics ◽  
2010 ◽  
Vol 75 (6) ◽  
pp. F187-F197 ◽  
Author(s):  
Ben K. Sternberg
Keyword(s):  
Magnetic Field ◽  
Noise Level ◽  
Monsoon Season ◽  
Signal Frequency ◽  
Time Interval ◽  
Frequency Range ◽  
Noise Levels ◽  
Controlled Source ◽  
Naturally Occurring ◽  
Minimum Noise

The variability of naturally occurring magnetic fields in the frequency range from [Formula: see text] over a period of one year was studied. Contour plots for the [Formula: see text], [Formula: see text], and [Formula: see text] components and for frequencies of 10, 100, 1000, 2000, and 8000 Hz were produced. Average, minimum, maximum, and the standard deviations of these fields were also calculated for 12 distinctive time intervals. In the 1– to 8–kHz frequency range, the noise levels are typically higher at night. In the 10- to 100-Hz frequency range, the noise levels are typically higher during the day. During mid- to late-summer, there is frequent thunderstorm activity, known in the southwest United States as the monsoon season. The magnetic field levels are often very high during this time period. These variability ranges can be used to estimate the lowest levels of noise that may be encountered during field surveys, which iswhat the authors are looking for when running controlled-source electrical method surveys. These variability ranges can also be used to estimate the highest levels that may be encountered, which is what the authors are looking for when running natural-source electrical methods surveys, such as audio frequency magnetotelluric (AMT) surveys. These measurements of magnetic field strength variability show that better data for controlled-source electrical measurements can be obtained using the minimum noise level measurements, as opposed to using signal integration or signal averaging with all of the data. The minimum noise level is found by using frequency bins adjacent to the signal-frequency bin. Likewise, if one is interested in measuring the naturally occurring magnetic field data, using the maximum values during each time interval makes AMT measurements possible when the natural signal level is very low, particularly in the AMT dead zone around [Formula: see text].

A New Magnetooptical Effect Discovered on Magnetic Multilayers: The Magnetorefractive Effect

1995 ◽  
Vol 384 ◽  
Author(s):  
J. C. Jacquet ◽  
T. Valet
Keyword(s):  
Magnetic Field ◽  
Optical Transmission ◽  
Theoretical Calculations ◽  
Wavelength Region ◽  
Magnetic Multilayers ◽  
Light Wavelength ◽  
Metallic Multilayers ◽  
Magnetooptical Effect ◽  
Transmission Measurements ◽  
Magnetorefractive Effect

ABSTRACTWe show theoretically that the change in the magnetization structure of magnetic metallic multilayers under the application of a magnetic field shall be generally associated with a significant change of the refractive index. This constitutes a new magnetooptical effect: the magnetorefractive effect.Optical transmission measurements under an applied magnetic field through [Ni80Fe20/Cu/Co/Cu] multilayers, in the light wavelength region between 2 μm and 20 μm, clearly demonstrate the existence of the predicted effect and are found in reasonnable agreement with the theoretical calculations.

scholarly journals Spiral wave unpinning facilitated by wave emitting sites in cardiac monolayers

2019 ◽  
Vol 475 (2230) ◽  
pp. 20190420
Author(s):  
Shreyas Punacha ◽  
Sebastian Berg ◽  
Anupama Sebastian ◽  
Valentin I. Krinski ◽  
Stefan Luther ◽  
...  
Keyword(s):  
Electric Field ◽  
Electrical Activity ◽  
Spiral Wave ◽  
Electrical Stimulus ◽  
Spiral Waves ◽  
Time Interval ◽  
Field Pulse ◽  
The Core ◽  
Rotating Wave ◽  
Multiple Obstacles

Rotating spiral waves of electrical activity in the heart can anchor to unexcitable tissue (an obstacle) and become stable pinned waves. A pinned rotating wave can be unpinned either by a local electrical stimulus applied close to the spiral core, or by an electric field pulse that excites the core of a pinned wave independently of its localization. The wave will be unpinned only when the pulse is delivered inside a narrow time interval called the unpinning window (UW) of the spiral. In experiments with cardiac monolayers, we found that other obstacles situated near the pinning centre of the spiral can facilitate unpinning. In numerical simulations, we found increasing or decreasing of the UW depending on the location, orientation and distance between the pinning centre and an obstacle. Our study indicates that multiple obstacles could contribute to unpinning in experiments with intact hearts.

scholarly journals Ion motion in the current sheet with sheared magnetic field – Part 2: Non-adiabatic effects

2013 ◽  
Vol 20 (5) ◽  
pp. 899-919 ◽  
Author(s):  
A. V. Artemyev ◽  
A. I. Neishtadt ◽  
L. M. Zelenyi
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Particle Motion ◽  
Phase Plane ◽  
Time Interval ◽  
Ion Motion ◽  
Average Value ◽  
Structure And Dynamics ◽  
Adiabatic Theory ◽  
The Magnetic Field

Abstract. We investigate dynamics of charged particles in current sheets with the sheared magnetic field. In our previouspaper (Artemyev et al., 2013) we studied the particle motion in such magnetic field configurations on the basis of the quasi-adiabatic theory and conservation of the quasi-adiabatic invariant. In this paper we concentrate on violation of the adiabaticity due to jumps of this invariant and the corresponding effects of stochastization of a particle motion. We compare effects of geometrical and dynamical jumps, which occur due to the presence of the separatrix in the phase plane of charged particle motion. We show that due to the presence of the magnetic field shear, the average value of dynamical jumps is not equal to zero. This effect results in the decrease of the time interval necessary for stochastization of trapped particle motion. We investigate also the effect of the magnetic field shear on transient trajectories, which cross the current sheet boundaries. Presence of the magnetic field shear leads to the asymmetry of reflection and transition of particles in the current sheet. We discuss the possible influence of single-particle effects revealed in this paper on the current sheet structure and dynamics.

Optimization of Semimagnetic Semiconductor-Based Nanostructures for Spintronic Applications

2006 ◽  
Vol 518 ◽  
pp. 35-40
Author(s):  
J. Radovanović ◽  
V. Milanović ◽  
Z. Ikonić ◽  
D. Indjin
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Simulated Annealing Algorithm ◽  
Structural Parameters ◽  
Zeeman Effect ◽  
Parameters Optimization ◽  
Potential Barriers ◽  
Annealing Algorithm ◽  
Electrical Bias ◽  
Spin Filtering

We have analyzed the spin-filtering effects of the electron current in asymmetric ZnSe/Zn1-xMnxSe multilayer structures, under the influence of both an external magnetic field and a bias voltage. In this type of semiconductor systems, conduction band electrons interact with 3d electrons of the magnetic Mn2+ ions. Because of this sp-d exchange interaction, an external magnetic field modulates the effective potential profile seen by spin-up and spin-down electrons, giving rise to a large Zeeman effect. It is found that the degree of spin polarization changes significantly when the electrical bias is switched from forward to reverse, thus the proposed structure displays obvious behavior of spin-filter diode. This originates from the effective “lifting” of the potential for spin-up electrons, which tunnel through actual potential barriers. Structural parameters optimization, with the goal of maximizing the spin-filtering coefficient, was performed by using simulated annealing algorithm. The described effect may be important for designing new tunable spin-based multifunctional semiconductor devices.

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