Wyniki wyszukiwania - Biblioteka Nauki

1

Effects of Magnetic Field Decay Time on the Hysteresis of Ultrasonic Wave Attenaution on Ferrofluid

100%

Józefczak A. , Skumiel A.

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2003

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tom Vol. 24

89-96

EN

Acoustic properities of a ferrofluid subject to an external magnetic filed depend on the sweep rate. The magnetic filed determines the mode and degree of aggregations of the magnetic particles and their association into chain-like clusters. After the removal of the filed the ferrofluid does not return to the original state as indicated by the ultrasound wave propagation study, in particular by changes in the ultrasonic wave absorption coefficient. A hysteresis of the ultrasonic wave absorption coefficient has been observed. The hysteresis depends on the rate of the magnetic field intensity decay. The effect of the hysteresis on the acoustic properities of the ferrofluid has been studied.

2

Ultradźwięki jako narzędzie badań nanomateriałów

80%

Hornowski T. , Józefczak A. , Skumiel A.

|

2013

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tom T. 64, z. 3-6

116--119

PL

Rozchodzeniem się fal ultradźwiękowych i słyszalnych rządzą te same prawa fizyczne, a tym, co je różni, jest przede wszystkim częstotliwość. Ta pozornie drobna różnica ma ogromne konsekwencje praktyczne. Fale sprężyste o dużych częstotliwościach dają sie łatwo kształtować w wąskie wiązki, co umożliwia ich wykorzystanie do kierunkowego sondowania właściwości ośrodka lub aktywnego wpływu na jego stan za pomocą temperatury lub nieliniowych zjawisk w rodzaju kawitacji.

3

Wykorzystanie rezonansowego pochłaniania fali ultradźwiękowej do określania rozmiarów klasterów cieczy magnetycznej APG-832

80%

Józefczak A. , Skumiel A. , Hornowski T.

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tom Vol. 19

119-124

EN

A magnetic fluid is a colloidal suspension of magnetic particles in a liquid carrier. It uses in engineering applications. Industries most commonly use ferrofluids are computers loundspeakers, petrochemicals, semiconductors, medicals. The present paper includes results of measurement dimension of spherical which arise in a magnetic fluid under the influence an external magnetic field. We used an acoustic method of a ultrasonic wave resonanse absorbtion. The measurement have been carried out in a magnetic fluid APG-832 for frequency f=l,l MHz at the temperatures 20°C, 30°C, 40°C, 50°C and 60°C. The obtain dimensions of spherical clusters are 624 nm (100 mT) - 1324 nm (450 mT).

4

Temperature Dependence of the Ultrasonic Wave Absorption Coefficient in Ferrofluid Subjected to External Magnetic Field

80%

Józefczak A. , Skumiel A. , Regulska P.

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tom Vol. 25

153-158

5

The Effect of Duration of Magnetic Field Application and Temperature of Velocity and Absorption Coefficient of Ultrasound Wave in a Magnetic Fluid

80%

Hornowski T. , Józefczak A. , Łabowski M. , Skumiel A.

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2003

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tom Vol. 24

31-40

6

The Effect of the Concentration of Ferroparticles in a Magnetic Fluid on its Acoustic and Magnetic Properties

80%

Skumiel A. , Józefczak A. , Hornowski T. , Kaczmarek M.

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tom Vol. 23

389-396

7

Magnetic and Ulrtrasonic Studies of Gel-Like Magnetic Systems

80%

Hornowski T. , Skumiel A. , Józefczak A. , Kaczmarek M.

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2001

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tom Vol. 22

107-112

EN

The paper presents results of experimental studies of magnetic susceptibility and ultrasonic properties of ferrogel in the presence of magnetic field. The results are discussed in terms of theoretical predictions, and some magnetic as well as elastic parameters of studied system are obtained.

8

Determination on the Magnetic Susceptibility Anisotropy, Propagation Velocity and Absorption Coefficient of an Ultrasonic Wave in a Magnetic Fluid

80%

Skumiel A. , Hornowski T. , Józefczak A. , Łabowski M.

|

2001

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tom Vol. 22

221-230

9

An Investigation of the Magnetic Properties of Ferrofluids

80%

Skumiel A. , Hornowski T. , Józefczak A. , Łabowski M.

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2001

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tom Vol. 22

231-238

10

Investigation of Ultrasonic Emulsifying Processes of a Linseed Oil and Water Mixture

71%

Skumiel A. , Józefczak A. , Heller K. , Hornowski T. , Wielgusz K.

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tom Vol. 38, No. 3

297--301

EN

Ultrasonic emulsifying processes of immiscible liquids can be used to obtain stable emulsions. The authors used an ultrasonic sandwich head with an energy concentrator to obtain a suitable value of the energy density necessary for the emerge of ultrasonic cavitation. Two piezoelectric ring (Dext = 50 mm) transducers of Pz-26 type produced by FERROPERM were used to design the ultrasonic sandwich head. The frequency of the ultrasonic wave was 18.4 kHz and the excitation time of the ultrasonic transducer exiting 5 minutes. Visible bubbles during the generation of ultrasonic waves appeared in the mixture after exceeding the cavitation threshold. The authors determined also the cavitation threshold by measuring the electrical voltage conducted to the transducers. To receive long-lasting emulsion, the electrical voltage attained 300 Vpeak. The dispersion dependence on the emulsifying time was determined. The emulsion of linseed oil and water was stable through some months without surfactants.

11

Ultrasonic and Magnetic Study of Physiology Based Magnetic Fluid

71%

Józefczak A. , Skumiel A. , Łabowski M. , Timko M. , Gierczyk N.

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tom Vol. 23

193-199

12

The Effect of Sonication on Acoustic Properties of Biogenic Ferroparticle Suspension

61%

Józefczak A. , Hornowski T. , Król A. , Molčan M. , Leszczyński B. , Timko M.

Archives of Acoustics

|

2016

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tom Vol. 41, No. 1

161--168

EN

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.