Search results

1

Intermolecular Magnetic Spin-Spin Interaction in Asphaltene Suspensions at 1.53 mT

100%

Ovalioglu H., Kirimli H., Akay C.

Acta Physica Polonica A

|

2016

|

vol. 129

|

issue 4

806-809

EN

In this study, Overhauser effect (OE) type of dynamic nuclear polarization (DNP) experiments were performed to study suspensions of MC800 asphaltene in bromopentafluorobenzene, chloropentafluorobenzene and hexafluorobenzene aromatic solvents. The experiments were performed at a low field of 1.53 mT in a double-resonance nuclear magnetic resonance (NMR) spectrometer. In this technique the nuclei of diffusing solvent molecules and the unpaired electron existing on the asphaltene micelles interact magnetically. The DNP parameters were determined. Additionally, the interactions between ¹⁹F nuclei of the solvent and the electrons delocalized on the asphaltene are interpreted. The highest enhancement factor value (5.90) was obtained for the hexafluorobenzene solvent medium, because between these, hexafluorobenzene has the highest fluorine atom number. The solvent molecules attach to the colloidal asphaltene particles for a very short time forming complexes and making scalar interaction. Morphologies of asphaltene surfaces depending on the solvent effects were observed by using scanning electron microscopy (SEM).

2

Intermolecular Effects of Fluorocarbons on MC800 Asphaltene and their Characterization

100%

Kirimli H., Ovalioglu H., Akay C.

Acta Physica Polonica A

|

2017

|

vol. 131

|

issue 3

336-338

EN

Nuclear magnetic resonance and dynamic nuclear polarization experiments were performed to study suspensions of asphaltene in the fluorocarbons at a low magnetic field of 1.53 mT, at room temperature. The asphaltene was extracted from MC800 liquid asphalt, which was of Heavy Iran origin. The elemental composition and the surface morphology of the asphaltene were determined by scanning electron microscopy and energy dispersive X-ray analysis. Intermolecular spin-spin interactions occur between nuclear spins of hydrogen in the solvent medium and the free electron spins in the asphaltene micelles. The electron paramagnetic resonance spectrum of the asphaltene was obtained and the saturation experiments were applied to the samples prepared in vacuum. The main ¹H DNP parameters were listed. Chemical composition and molecular structure of the asphaltene were analyzed. Scanning electron microscope images have shown that asphaltenes are constituted of agglomerated particles and smooth surfaces. Energy dispersive X-ray analysis has shown that the most abundant element is carbon.

3

The Influence of Sonication and Silver Nanoparticles Doped on Viscoelastic Structure of Agarose Gel

88%

Żyła G., Stompor M., Kopańska M., Stagraczyński R., Fal J., Traciak J., Trybus M., Wolski S., Zawlik I., Cebulski J., Konefał-Janocha M., Cholewa M.

Acta Physica Polonica A

|

2017

|

vol. 132

|

issue 1

152-154

EN

The paper presents result of experimental measurements of viscoelastic properties of agarose gel after sonication and with silver nanoparticles doped. Researches were conducted using a HAAKE MARS 2 rheometer (Thermo Electron Corporation, Karlsruhe, Germany), with serrated plate-plate measuring geometry. Viscoelastic properties of samples were measured with oscillation tests at constant deformation rate 0.1%, and frequency 1 Hz in the temperature range from 278 to 348 K. It was presented that using the sonication before solidification of gel results in increases of the storage modulus and complex viscosity of the solidified gel. It was also presented that when silver nanoparticles are doped into agarose gel, storage modulus and complex viscosity start to decrease at lower temperature.

4

Ultrasound Frequency Analysis of a Magnetic Fluid in Low-Intensity External Magnetic Field

88%

Kurimský J., Rajňák M., Cimbala R., Dolník B., Tóthová J., Paulovičová K., Timko M., Kopčanský P., Kolcunová I., Petráš J., Džmura J., Balogh J.

Acta Physica Polonica A

|

2017

|

vol. 131

|

issue 4

910-912

EN

This work deals with an interaction of a magnetic fluid of a dielectric nature with a magnetic field by means of ultrasound waves measurements and analysis. Ultrasound analysis is known as a non-destructive inspection tool often used in technical diagnostics, moreover, it has numerous applications in medicine and biology, too. We report the low-frequency ultrasound analysis of a dielectric magnetic fluid in a low-intensity external static magnetic field. The studied magnetic fluid was composed of a transformer oil and dispersed magnetite nanoparticles coated with oleic acid. Experiments were carried out by using an ultrasonic testing cell. The cell was exposed to a magnetic field of 50 mT in both parallel and perpendicular direction to the waves propagation. A through-transmission mode measurement was applied, where two fixed narrow-band transducers with completely shielded crystal for maximum RFI/EMI immunity (Physical Acoustic R15I-AST, the resonant frequency 150 kHz) served as a transmitter and a receiver. In this way we carried out the measurement of the frequency-dependent ultrasonic response to a rectangle calibrating signal of 5 μs pulse width. Digitized signals were recorded for further analysis. We present the frequency domain analysis of the low-frequency ultrasound in magnetic fluid. The frequency spectrum in magnetic fluid colloidal system was calculated by the Fourier transformation method. Results show that there is a frequency shift in the amplitude-frequency spectrum caused by the step-up magnetic field. The higher the magnetic field, the higher the frequency of the peaks. The effect of particle aggregation in magnetic field on the ultrasound wave propagation is discussed in the paper.

5

Dynamic Viscosity of Aluminum Oxide-Ethylene Glycol (Al₂O₃-EG) Nanofluids

88%

Żyła G., Fal J., Gizowska M., Witek A., Cholewa M.

|

EN

The paper presents the results of measurements of rheological properties of ethylene glycol (EG) based aluminum oxide (Al₂O₃) nanofluids. The nanofluids have been produced by two-step method with the use of commercially available nanoparticles. Dynamic viscosity curves and dependence of viscosity on temperature for these materials have been measured. It has shown that with higher concentration of nanoparticles in the suspension, these nanofluids exhibit the non-Newtonian flow and it can be considered as shear-thinning liquids. The effect of temperature on the dynamic viscosity in Al₂O₃-EG nanofluids can be modelled with the use of Vogel-Fulcher-Tammann expression.

6

Ultrasonic Methods of the Cells Separation in Human Blood

88%

Włoch A., Czyż H., Jasiński T.

Acta Physica Polonica A

|

2015

|

vol. 128

|

issue 2

234-236

EN

This work deals with the problem of ultrasound in the context of biomedical and clinical applications. Ultrasonic waves can be used for the separation of cells in human blood. Under the influence of ultrasonic waves cells included in the liquid experience a certain characteristic displacement was referred to as drift. Presented work suggests that only radiation pressure should be taken into account as a mechanism of drifting in this situation. It has been demonstrated that the growth of cells concentration around the points of stable equilibrium is exponential. The time constant of this growth was estimated and the formulae which determine the time needed to obtain the assumed concentration increase have been derived. The theoretical studies of acoustic agglomeration of particles in the liquid have become a new focus in the ultrasonic research.

Refine search results

Intermolecular Magnetic Spin-Spin Interaction in Asphaltene Suspensions at 1.53 mT

Intermolecular Effects of Fluorocarbons on MC800 Asphaltene and their Characterization

The Influence of Sonication and Silver Nanoparticles Doped on Viscoelastic Structure of Agarose Gel

Ultrasound Frequency Analysis of a Magnetic Fluid in Low-Intensity External Magnetic Field

Dynamic Viscosity of Aluminum Oxide-Ethylene Glycol (Al₂O₃-EG) Nanofluids

Ultrasonic Methods of the Cells Separation in Human Blood