Synthesis of Silver Incorporated Hydroxyapatite under Magnetic Field

2011 ◽  
Vol 493-494 ◽  
pp. 181-185 ◽  
Author(s):  
Tapash R. Rautray ◽  
Kyo Han Kim
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Titanium Surface ◽  
Field Conditions ◽  
Silver Concentration ◽  
Cathodic Deposition ◽  
Magnetic Stirrer ◽  
Hydroxyapatite Coatings ◽  
Nanocrystalline Hydroxyapatite

Cathodic deposition of nanocrystalline hydroxyapatite coatings on titanium surface was carried out under different magnetic field conditions. The electrolyte was prepared to maintain physiological pH and was agitated using a magnetic stirrer throughout the time of electrolysis. Silver was incorporated in the current coating because of its antibactericidal and cytotoxic nature. It was found that the silver concentration in HA coated titanium without magnetic field was higher than the coating formed under magnetic fields. This may be attributed to the diamagnetic nature of silver in different magnetic field conditions.

Control of the Alloying Element Distribution in Al-Alloys by High Magnetic Fields

2007 ◽  
Vol 539-543 ◽  
pp. 457-462 ◽  
Author(s):  
Qiang Wang ◽  
Xue Jun Pang ◽  
Chun Jiang Wang ◽  
Tie Liu ◽  
Dong Gang Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Physical Properties ◽  
High Magnetic Field ◽  
Element Distribution ◽  
Field Conditions ◽  
High Magnetic Fields ◽  
Gradient Magnetic Field ◽  
The Matrix ◽  
Al Mg Alloys

The distribution and solidified structure of alloying elements are important for the quality and the properties of alloys. In the present study, the solidification behavior of aluminum-rich alloys is studied under various high magnetic field conditions, and the influences of uniform and gradient magnetic fields with different intensity and direction on the distribution and the morphology of solute elements of Al-Cu and Al-Mg alloys are investigated. It is found that because of the differences of the electromagnetic force (Lorentz and magnetization forces) acting on Cu element and Mg element with different physical properties in the matrix, the regularities of distribution for Cu element and Mg element are opposite just in the intracrystalline and intergranular under high uniform magnetic field condition, and not only the content but the distributions of Cu and Mg elements are obviously different under high gradient magnetic field conditions as well. It can be concluded that high magnetic field has different effect on the solute distribution in alloys with different physical properties such as density, susceptibility, conductivity, etc. And the experimental results indicate that it is possible to control the terminal solubility and morphology of the solute elements in alloys by high magnetic fields.

MAGNETIC NANOPARTICLE MEDIATED GENE DELIVERY IN OLIGODENDROGLIAL CELLS: A COMPARISON OF DIFFERENTIATED CELLS VERSUS PRECURSOR FORMS

Nano LIFE ◽  
2013 ◽  
Vol 03 (02) ◽  
pp. 1243001 ◽  
Author(s):  
STUART I. JENKINS ◽  
MARK R. PICKARD ◽  
DIVYA M CHARI
Keyword(s):  
Magnetic Field ◽  
Gene Delivery ◽  
Magnetic Fields ◽  
Nerve Fibers ◽  
Field Conditions ◽  
Nonviral Gene Delivery ◽  
Parent Cell ◽  
Neural Lineage ◽  
Differentiated Cells ◽  
Magnetic Vectors

Magnetic nanoparticles (MNPs) have emerged as a major platform for the formulation of magnetic vectors for nonviral gene delivery. Notably the application of "magnetofection" strategies (use of magnetic fields to increase MNP–cell interactions) can significantly enhance MNP mediated gene transfer. Despite the potential of this approach, the use of MNPs and magnetofection for gene delivery to oligodendrocytes (the cells that make and maintain myelin, the insulating sheath around nerve fibers in the central nervous system) has never been tested. Here, we prove the feasibility of using MNPs in conjunction with applied static or oscillating gradient magnetic fields (the "magnetofection" method) to deliver genes to oligodendrocytes; all applied magnetic field conditions resulted in greater transfection than the no field condition but overall transfection levels obtained were typically low (ca. < 6%). Oligodendrocyte transfection levels under all magnetic field conditions were less than a third compared with their parent cell population, the oligodendrocyte precursor cells. Our results demonstrate for the first time that, within cells of a specific neural lineage, the amenability to transfection is dependent on the differentiation status of the cell.

The Crystal Orientation of Hydroxyapatite Coatings Affected by the Magnetic Fields on Magnesium Alloy

2013 ◽  
Vol 395-396 ◽  
pp. 751-754 ◽  
Author(s):  
Chen Yang Xu ◽  
Xiao Ling Xu ◽  
Fang Gao ◽  
Fu Xiang Chu ◽  
Qi Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Crystal Structure ◽  
Biological Activity ◽  
Magnesium Alloy ◽  
Magnetic Fields ◽  
Crystal Orientation ◽  
Degradation Rate ◽  
The Arctic ◽  
Hydroxyapatite Coatings ◽  
The Antarctic

Hydroxyapatite coatings with biological activity on magnesium alloy can effectively reduce its degradation rate in the physiological environment. Pre-calcification was applied as the pretreatment in this paper. And then, hydroxyapatite coatings were deposited on the surface of the magnesium alloy in non-magnetic field, near the antarctic and the arctic of a constant magnetic field respectively. The morphology, phase composition and crystal structure of the coatings were analyzed using SEM and XRD. The results show that the crystals of the coatings affected by the magnetic fields are preferential orientation significantly.

Geophysical Variables and Behavior: Xci. Ambulatory Behavior in Rats following Prenatal Exposures to Complex Magnetic Fields Designed to Interact with Genetic Expression

2001 ◽  
Vol 92 (1) ◽  
pp. 183-192 ◽  
Author(s):  
M. A. Persinger ◽  
L. S. St-Pierre ◽  
S. A. Koren
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Open Field ◽  
Applied Magnetic Field ◽  
Prenatal Development ◽  
Field Conditions ◽  
Complex Pattern ◽  
Neuronal Organization ◽  
Genetic Expression ◽  
And Behavior

A total of 45 litters were exposed during their entire prenatal development to one of two complex patterns of magnetic fields whose strengths varied within one of four intensity ranges between 10 nT and 1000 nT or to sham-field conditions. The litters exposed to the most complex pattern, composed of 50 200-msec. presentations of different pulses for 10 sec. every 50 sec., displayed more ambulation in an open field at 21 days of age than the litters that had been exposed continuously to a repetitive frequency-modulated field or to sham-field conditions. This treatment explained 25% of the variance in the numbers of squares traversed. The results suggest that complexity of the applied magnetic field during prenatal development may be more important than intensity for permanently affecting neuronal organization and behavior.

scholarly journals Quasi-Static Transduction Characterization of Galfenol

Aerospace ◽  
2003 ◽  
Author(s):  
Rick A. Kellogg ◽  
Alison Flatau ◽  
Arthur E. Clark ◽  
Marilyn Wun-Fogle ◽  
Thomas Lograsso
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Thermal Conditions ◽  
Cyclic Stress ◽  
Field Conditions ◽  
Directionally Solidified ◽  
Saturation Magnetostriction ◽  
Magnetic Characterization

The objective of the work presented is characterization of the magnetoelastic transduction properties of single crystal and textured polycrystalline Fe-Ga alloys (Galfenol) under controlled mechanical, magnetic and thermal conditions. Polycrystalline samples of interest include a directionally solidified specimen, which possesses a favorable saturation magnetostriction output, and an extruded specimen, whose magnetostriction properties were significantly reduced by annealing. A brief discussion of the thermally controlled transducer used for the magnetic testing is presented first. Thereafter, the single crystal response to major-loop cyclic magnetic fields under different temperature and stress conditions, as well as its response to minor-loop cyclic magnetic fields and major-loop cyclic stress is examined. Next, the magnetic and magnetostrictive responses to major-loop cyclic magnetic field conditions are compared for the directionally solidified, extruded and single crystal specimens. The paper concludes with a magnetic characterization summary of the different Fe-Ga alloys examined.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust &amp; Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust &amp; Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

Peculiarity Parameters

1976 ◽  
Vol 32 ◽  
pp. 233-254
Author(s):  
H. M. Maitzen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Theoretical Work ◽  
Observational Evidence ◽  
Rotator Model ◽  
Peculiar Behaviour ◽  
Field Spectrum ◽  
Oblique Rotator ◽  
Ap Stars ◽  
The Way

Ap stars are peculiar in many aspects. During this century astronomers have been trying to collect data about these and have found a confusing variety of peculiar behaviour even from star to star that Struve stated in 1942 that at least we know that these phenomena are not supernatural. A real push to start deeper theoretical work on Ap stars was given by an additional observational evidence, namely the discovery of magnetic fields on these stars by Babcock (1947). This originated the concept that magnetic fields are the cause for spectroscopic and photometric peculiarities. Great leaps for the astronomical mankind were the Oblique Rotator model by Stibbs (1950) and Deutsch (1954), which by the way provided mathematical tools for the later handling pulsar geometries, anti the discovery of phase coincidence of the extrema of magnetic field, spectrum and photometric variations (e.g. Jarzebowski, 1960).

Nuclear magnetic resonance microscopy

1989 ◽  
Vol 47 ◽  
pp. 828-829
Author(s):  
Paul C. Lauterbur
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Signal To Noise ◽  
Field Gradients ◽  
Useful Signal ◽  
Magnetic Field Gradients ◽  
Observation Times ◽  
Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

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