scholarly journals Echogenic Advantages of Ferrogels Filled with Magnetic Sub-Microparticles

2021 ◽  
Vol 8 (10) ◽  
pp. 140
Author(s):  
Olga A. Dinislamova ◽  
Antonina V. Bugayova ◽  
Tatyana F. Shklyar ◽  
Alexander P. Safronov ◽  
Felix A. Blyakhman
Keyword(s):  
Magnetic Particles ◽  
Weight Fraction ◽  
Acoustic Properties ◽  
Echo Signal ◽  
Ultrasound Monitoring ◽  
Polymeric Networks ◽  
Natural Polysaccharide ◽  
Size Of Particles ◽  
Applied External Magnetic Field ◽  
Cylindrical Samples

Ultrasonic imaging of ferrogels (FGs) filled with magnetic nanoparticles does not reflect the inner structure of FGs due to the small size of particles. To determine whether larger particle size would improve the acoustic properties of FGs, biocompatible hydrogels filled with 100–400 nm iron oxide magnetic sub-microparticles with weight fraction up to 23.3% were synthesized and studied. Polymeric networks of synthesized FGs were comprised of chemically cross-linked polyacrylamide with interpenetrating physical network of natural polysaccharide—Guar or Xanthan. Cylindrical samples approximately 10 mm in height and 13 mm in diameter were immersed in a water bath and examined using medical ultrasound (8.5 MHz). The acoustic properties of FGs were characterized by the intensity of reflected echo signal. It was found that the echogenicity of sub-microparticles provides visualization not only of the outer geometry of the gel sample but of its inner structure as well. In particular, the echogenicity of FGs interior depended on the concentration of magnetic particles in the FGs network. The ultrasound monitoring of the shape, dimensions, and inner structure of FGs in the applied external magnetic field is demonstrated. It is especially valuable for the application of FGs in tissue engineering and regenerative medicine.

A kinetic model for magnetostriction of a ferrogel with physical networking

2021 ◽  
Vol 379 (2205) ◽  
pp. 20200315 ◽  
Author(s):  
A. P. Safronov ◽  
A. Yu. Zubarev ◽  
E. A. Mikhnevich ◽  
E. V. Rusinova
Keyword(s):  
Magnetic Particles ◽  
Guar Gum ◽  
Loss Modulus ◽  
Liquid Droplet ◽  
Mechanical Analysis ◽  
Strontium Hexaferrite ◽  
Theme Issue ◽  
Natural Polysaccharide ◽  
Order Of Magnitude ◽  
Kinetics Of

Kinetics of magnetostriction of ferrogel with physical networking based on natural polysaccharide guar gum with embedded strontium hexaferrite magnetic particles were studied in the uniform magnetic field 420 mT. An ellipsoidal sample was elongated by 37% along the applied field and contracted by 15% in the transverse direction, while its volume was kept constant. The characteristic time of magnetostriction was 440 s. Dynamic mechanical analysis in an oscillatory mode showed that the deformation of ferrogel is mostly elastic rather than viscous. Its storage modulus was almost constant in a frequency range of 0.1–100 Hz and by at least an order of magnitude larger than the loss modulus. Meanwhile, a developed theoretical model based on the elasto-viscous behaviour of the ferrogel failed to estimate correctly the experimental value of its magnetostriction. Calculated values of the elongation of ferrogel in the field were several orders of magnitude lower than those observed in the experiment for the ferrogel with physical networking. Consistency between the experiment and the theory was achieved using the alternative consideration based on the deformation of a liquid droplet of ferrofluid. The applicability of such an approach was discussed concerning structural relaxation properties of the ferrogel with physical networking. This article is part of the theme issue ‘Transport phenomena in complex systems (part 1)’.

scholarly journals Magnetohydrodynamic Blood Flow in a Cylindrical Tube with Magnetic Particles: A Time Fractional Model

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Farhad Ali ◽  
Samina Majeed ◽  
Anees Imtiaz
Keyword(s):  
Blood Flow ◽  
Magnetic Particles ◽  
Mass Parameter ◽  
Classical Model ◽  
Cylindrical Tube ◽  
Definition Of ◽  
Circular Cylindrical Tube ◽  
Short Time ◽  
Applied External Magnetic Field ◽  
Fractional Parameter

The present work theoretically investigates the natural convection blood flow as a Brinkman-type fluid with uniformly distributed magnetic particles in a circular cylindrical tube with the applied external magnetic field. The classical model for the blood flow is generalized by using the definition of Caputo time-fractional derivative. The exact solutions are obtained by using the Laplace and Henkel transforms. Unlike the classical model, the obtained general results are expressed in the form of “Lorenzo and Hartley’s” and “Robotnov and Hartley’s” functions. Graphs are plotted to show the effects of different parameters on the blood flow. Furthermore, the velocity and temperature distributions are discussed in terms of memory. The effect of fractional parameter α for a long and short time has also been observed. It is noticed that blood velocity can be controlled using the fractional parameter. It is also found that, for τ > 0 , fluid and particles motion increased, and reverse behavior is observed for τ < 0 . It has been noticed that increasing values of particle mass parameter P m and magnetic parameter M slow down the motion of blood and magnetic particles. These results are helpful for effective drug delivery and regulating blood flow.

scholarly journals The Effect of Sonication on Acoustic Properties of Biogenic Ferroparticle Suspension

2016 ◽  
Vol 41 (1) ◽  
pp. 161-168
Author(s):  
Arkadiusz Józefczak ◽  
Tomasz Hornowski ◽  
Anita Król ◽  
Matúš Molčan ◽  
Błażej Leszczyński ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Biological Membrane ◽  
Particle Surface ◽  
Superparamagnetic Iron Oxide ◽  
Magnetotactic Bacteria ◽  
High Energy ◽  
Ultrasonic Waves ◽  
The Body ◽  
Acoustic Properties ◽  
Ultrasonic Spectroscopy

Abstract Superparamagnetic iron oxide nanoparticles (SPION) synthesised chemically usually need the modification of the particle surface. Other natural sources of magnetic particles are various magnetotactic bacteria. Magnetosomes isolated from magnetotactic bacteria are organelles consisting of magnetite (Fe3O4) or greigite (Fe3S4) crystals enclosed by a biological membrane. Magnetotactic bacteria produce their magnetic particles in chains. The process of isolation of magnetosome chains from the body of bacteria consists of a series of cycles of centrifugation and magnetic decantation. Using a high-energy ultrasound it is possible to break the magnetosome chains into individual nanoparticles – magnetosomes. This study presents the effect of sonication of magnetosome suspension on their acoustic properties, that is speed and attenuation of the sound. Acoustic propagation parameters are measured using ultrasonic spectroscopy based on FFT spectral analysis of the received pulses. The speed and attenuation of ultrasonic waves in magnetosome suspensions are analysed as a function of frequency, temperature, magnetic field intensity, and the angle between the direction of the wave and the direction of the field.

Magnetic Properties of Co Nanoparticles in an AlMCM41 Mesoporous Host

2001 ◽  
Vol 676 ◽  
Author(s):  
Jin-Seung Jung ◽  
Jun-Yong Kim ◽  
Weon-Sik Chae ◽  
Yong-Rok Kim ◽  
Jong-Ho Jun ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Volume Fraction ◽  
Magnetic Measurements ◽  
X Ray Diffraction ◽  
Host Matrix ◽  
Transmission Electron ◽  
Small Volume Fraction ◽  
Size Of Particles ◽  
Co Nanoparticles

ABSTRACTUltrafine cobalt particles in AlMCM41 silica tubes have been synthesized by ion exchange and the reduction with sodium borohydride. The role of this stable host matrix of AlMCM41 silica is to prevent agglomeration of the magnetic particles attached to the walls of AlMCM41 silica pores. The size of the host pores naturally limits the particle dimensions and thus improves their size distribution. Both magnetic susceptibility measurements and transmission electron microscopy (TEM) show a narrow distribution size of the nanoparticles. Well controlled insertion of the magnetic material to the host channel excludes formation of bulk particles outside the host material grains, which was confirmed by the TEM studies. X-ray diffraction data did not show peaks corresponding to a crystalline cobalt, but this maybe due to small size of particles and their relatively small volume fraction. The content of Co in the AlMCM41 host was measured using both magnetic measurements and elemental analysis.

scholarly journals Magnetoimpedance Thin Film Sensor for Detecting of Stray Fields of Magnetic Particles in Blood Vessel

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3621
Author(s):  
Grigory Yu. Melnikov ◽  
Vladimir N. Lepalovskij ◽  
Andrey V. Svalov ◽  
Alexander P. Safronov ◽  
Galina V. Kurlyandskaya
Keyword(s):  
Blood Vessel ◽  
Biomedical Applications ◽  
Magnetic Particles ◽  
Epoxy Composite ◽  
Weight Fraction ◽  
Magnetic Composite ◽  
Film Sensor ◽  
Thin Film Sensor ◽  
Maximum Value ◽  
State Evaluation

Multilayered [FeNi (100 nm)/Cu (3 nm)]5/Cu (500 nm)/[Cu (3 nm)/[FeNi (100 nm)]5 structures were used as sensitive elements of the magnetoimpedance (MI) sensor prototype for model experiments of the detection of magnetic particles in blood vessel. Non-ferromagnetic cylindrical polymer rod with a small magnetic inclusion was used as a sample mimicking thrombus in a blood vessel. The polymer rod was made of epoxy resin with an inclusion of an epoxy composite containing 30% weight fraction of commercial magnetite microparticles. The position of the magnetic inclusion mimicking thrombus in the blood vessel was detected by the measurements of the stray magnetic fields of microparticles using MI element. Changes of the MI ratio in the presence of composite can be characterized by the shift and the decrease of the maximum value of the MI. We were able to detect the position of the magnetic composite sample mimicking thrombus in blood vessels. Comsol modeling was successfully used for the analysis of the obtained experimental results and the understanding of the origin the MI sensitivity in proposed configuration. We describe possible applications of studied configuration of MI detection for biomedical applications in the field of thrombus state evaluation and therapy.

scholarly journals Ferrogels Ultrasonography for Biomedical Applications

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3959 ◽  
Author(s):  
Felix A. Blyakhman ◽  
Sergey Yu Sokolov ◽  
Alexander P. Safronov ◽  
Olga A. Dinislamova ◽  
Tatyana F. Shklyar ◽  
...  
Keyword(s):  
Targeted Drug Delivery ◽  
Biomedical Engineering ◽  
Entire Range ◽  
Biomedical Applications ◽  
Medical Ultrasound ◽  
Acoustic Oscillations ◽  
Echo Signal ◽  
Magnetic Composites ◽  
Targeted Drug ◽  
Cylindrical Samples

Ferrogels (FG) are magnetic composites that are widely used in the area of biomedical engineering and biosensing. In this work, ferrogels with different concentrations of magnetic nanoparticles (MNPs) were synthesized by the radical polymerization of acrylamide in stabilized aqueous ferrofluid. FG samples were prepared in various shapes that are suitable for different characterization techniques. Thin cylindrical samples were used to simulate the case of targeted drug delivery test through blood vessels. Samples of larger size that were in the shape of cylindrical plates were used for the evaluation of the FG applicability as substitutes for damaged structures, such as bone or cartilage tissues. Regardless of the shape of the samples and the conditions of their location, the boundaries of FG were confidently visualized over the entire range of concentrations of MNPs while using medical ultrasound. The amplitude of the reflected echo signal was higher for the higher concentration of MNPs in the gel. This result was not related to the influence of the MNPs on the intensity of the reflected echo signal directly, since the wavelength of the ultrasonic effect used is much larger than the particle size. Qualitative theoretical model for the understanding of the experimental results was proposed while taking into account the concept that at the acoustic oscillations of the hydrogel, the macromolecular net, and water in the gel porous structure experience the viscous Stocks-like interaction.

scholarly journals Fiber Weight Fraction Effect to Acoustic Properties of RHDPE Cantula Composite

2017 ◽  
Vol 16 (2) ◽  
Author(s):  
Muhammad Taufik Burhany Hendrowarsito ◽  
Wijang Wisnu Raharjo ◽  
Dwi Aries Himawanto
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Density Measurement ◽  
Weight Ratio ◽  
Weight Fraction ◽  
Acoustic Properties ◽  
Sound Absorption Coefficient ◽  
Hot Press ◽  
Coefficient Increase ◽  
Impedance Tube Method

In this study, composites made from recycled HDPE and Cantula fiber have been done and the absorption coefficient have been measured. Composites rHDPE-Cantula were made using hot press for approximately 60 minutes with 170oC temperature while pressure exerted by 50 bar. In this study the weight ratio of Cantula fiber was varied 40%, 50%, 60%, and 70%. Impedance Tube Method was used to measure the sound absorption coefficient in accordance with ASTM E 1050. An increase weight ratio wasn’t influence the sound absorption coefficient significantly, but the optimum sound absorption coefficient shifted to the higher frequencies from 80-200 Hz. An increase weight ratio showed better sound absorption coefficient from 500-1600 Hz, but the result from 60% weight ratio showed low sound absorption coefficient that may caused by it high density leading to the reduction of porosity. This result was supported by density measurement in accordance with ASTM D 792, which the result showed that the sound absorption coefficient increase with decreasing of the density.

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

A magnetic super lattice

1987 ◽  
Vol 45 ◽  
pp. 360-361 ◽  
Author(s):  
M.D. Bentzon ◽  
J. v. Wonterghem ◽  
A. Thölén
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Carbon Film ◽  
Thick Layer ◽  
Amorphous Iron ◽  
Super Lattice ◽  
Carrier Liquid ◽  
Median Diameter

We report on the oxidation of a magnetic fluid. The oxidation results in magnetic super lattice crystals. The “atoms” are hematite (α-Fe2O3) particles with a diameter ø = 6.9 nm and they are covered with a 1-2 nm thick layer of surfactant molecules.Magnetic fluids are homogeneous suspensions of small magnetic particles in a carrier liquid. To prevent agglomeration, the particles are coated with surfactant molecules. The magnetic fluid studied in this work was produced by thermal decomposition of Fe(CO)5 in Declin (carrier liquid) in the presence of oleic acid (surfactant). The magnetic particles consist of an amorphous iron-carbon alloy. For TEM investigation a droplet of the fluid was added to benzine and a carbon film on a copper net was immersed. When exposed to air the sample starts burning. The oxidation and electron irradiation transform the magnetic particles into hematite (α-Fe2O3) particles with a median diameter ø = 6.9 nm.

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