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Wyświetlanie 1-4 z 4
Tytuł:
Analysis of Complex Viscosity in a Group of Patients with Circulation Disorders
Autorzy:
Marcinkowska-Gapińska, A.
Kowal, P.
Powiązania:
https://bibliotekanauki.pl/articles/1490444.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
83.50.Ax
83.60.Fg
83.60.Bc
83.80.Lz
83.85.Vb
Opis:
Rheology of viscoelastic fluids is a complex phenomenon. Full blood is an example of a body fluid of non-Newtonian character with pronounced viscoelastic properties. Blood flow in the circulatory system depends not only on the physical and physico-chemical properties of blood but also on the structure and properties of the vascular system. Blood viscosity is one of the most important factor determining the blood flow. Its value depends on the shear rate, hematocrit, erythrocyte aggregability and deformability, and on the plasma viscosity and composition. In the course of the investigation we utilized oscillatory methods, called also dynamic mechanical analysis. The technique principle is based on the measurement of the amplitude and phase of oscillations of the sample subject to a harmonic force with certain amplitude and frequency. The results of dynamic mechanical analysis were used to determine the viscoelastic properties of blood samples. We performed also the standard flow curve measurements of the blood plasma samples, that is shear stress as a function of shear rate in the rotary mode. All measurements were performed by means of a Contraves LS-40 rheometer on blood samples taken from two groups of patients. One group contained patients after heart attack, while the second one - after cerebral infarction. In none of the groups the patients were in an acute state. Information obtained from oscillatory measurements indicate increased erythrocyte aggregability in both groups of patients.
Źródło:
Acta Physica Polonica A; 2012, 121, 1A; A-054-A-056
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the Effect of Magnetostimulation on Viscoelastic Properties of Blood in Patients with Lasting Pain
Autorzy:
Marcinkowska-Gapińska, A.
Kowal, P.
Powiązania:
https://bibliotekanauki.pl/articles/1197513.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
83.50.Ax
83.60.Fg
83.60.Bc
83.80.Lz
83.85.Vb
87.50.C-
Opis:
The aim of the current work was to analyze the influence of alternating magnetic field on the viscoelastic properties of blood in vivo in patients with lasting pain problems. Oscillatory techniques, also called the dynamic mechanical analysis, have been used in the current work to study the viscoelastic properties of blood. The blood samples were collected from patients of a neurological ward complaining about spinal cord and lower limbs pain. Altogether 25 patients took part in the study. A blood sample was collected from each patient twice: before the magnetostimulation and after five treatments. For each blood sample, the hematocrit value was measured using the standard method. Plasma viscosity and the complex whole blood viscosity were measured by means of a rotary-oscillating rheometer Contraves LS40. Magnetic field was generated by the instrument Viofor JPS and the magnetostimulation treatments were performed using different programs. The analysis of the results included estimation of the hematocrit value, plasma viscosity, complex whole blood viscosity and its components: viscous and elastic viscosity at four chosen amplitudes of the shear rate as a function of the applied treatment program. The results obtained in the study suggest that rheological properties of blood change depending on the applied magnetostimulation program.
Źródło:
Acta Physica Polonica A; 2014, 125, 4A; A-24-A-26
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Viscosity Measurement Using Optical Tracking of Free Fall in Newtonian Fluid
Autorzy:
Kheloufi, N.
Lounis, M.
Powiązania:
https://bibliotekanauki.pl/articles/1402341.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
83.85.Jn
83.60.Fg
Opis:
This paper presents a novel method in viscosity assessment using a tracking of the ball moving in Newtonian fluid. The movement of the ball is assimilated to a free fall within a tube containing liquid of whose we want to measure a viscosity. In classical measurement, height of fall is estimated directly by footage where accuracy is not really considered. Falling ball viscometers have shown, on the one hand, a limit in the ball falling height measuring, on the other hand, a limit in the accuracy estimation of velocity and therefore a weak precision on the viscosity calculation of the fluids. Our technique consist to measure the fall height by taking video sequences of the ball during its fall and thus estimate its terminal velocity which is an important parameter for cinematic velocity computing, using the Stokes formalism. The time of fall is estimated by cumulating time laps between successive video sequences which mean that we can finally estimate the cinematic viscosity of the studied fluid.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 123-127
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Differentiation of Native and Reconstructed Ferritin using the MRI Gradient Echo Pulse Sequence
Autorzy:
Balejcikova, L.
Strbak, O.
Baciak, L.
Kovac, J.
Masarova, M.
Krafcik, A.
Kopcansky, P.
Dobrota, D.
Frollo, I.
Powiązania:
https://bibliotekanauki.pl/articles/1032829.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.Ej
83.85.Fg
87.61.-c
87.64.Cc
87.85.jf
Opis:
Ferritin is a biological iron storage biomacromolecule, consisting of a spherical protein shell (apoferritin) and mineral iron core. It plays a crucial role in the pathological processes of disrupted iron homeostasis followed by iron accumulation, linked with various disorders (e.g. neuroinflammation, neurodegeneration, cirrhosis, cancer, etc.) In vitro reconstructed ferritin, with the assistance of a non-invasive magnetic resonance imaging technique, has the potential to become a suitable biomarker of these pathological processes. Through gradient echo pulse sequencing, we were able to clearly distinguish between native (physiological) and reconstructed/iron-overloaded (pathological) ferritin, which can serve as a starting point for the development of a method for their differentiation. Such method is necessary for the early diagnosis of iron-based diseases.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1093-1095
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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