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Fifty Years of Study of the Piezoelectric Properties of Macromolecular Structured Biological Materials

100%
Kryszewski M.
Acta Physica Polonica A
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2004
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vol. 105
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issue 4
389-408
EN
The piezoelectricity of biopolymers was discovered by E. Fukada for wood and bone in the fifties. This paper induced a number of studies on piezoelectric behaviour of bone collagen and tendon in wet and dry conditions as well as in many biological substances: polysaccharides, proteins, and biodegradable, optically active oriented films of poly(L-lactic acid). The implantation of this polymer induced the growth of bone, possibly because the ionic current caused by piezoelectric polarization stimulated the activity of bone cells. The phenomenon of bone growth has been discussed in terms of application of various substances, particularly modified collagen. The healing process of bone growth is still open both from the view of mechanism and biocompatibilities of materials used for this purpose. Fukada's group has a leading position in these studies. The fifty years of study of piezoelectricity in biomaterials resulted in many important observations and indication for further promising experimental and theoretical studies which will help to discover new ways and new materials for the tissue reconstruction.
2
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Analysis of Complex Viscosity in a Group of Patients with Circulation Disorders

88%
Marcinkowska-Gapińska A., Kowal P.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1A
A-54-A-56
EN
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.
3
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Micromechanics Investigation of Wood Cell Walls under Compression Loading

75%
Günay E., Golmohammadi H.
Acta Physica Polonica A
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2016
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vol. 129
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issue 4
459-463
EN
The aim of this study was to detect the determinations of the 3D cell deformations of pine wood (Pinus sylvestris L.) in micro-scale(µm) under mechanical compression loading. The 20× 20× 50 mm^3 sized wood specimens were tested under compressive pressure load through 35-40 MPa parallel to the grain orientations. The pressure applied samples were divided into three parts, then processed to form smaller cubic pieces and this pieces stained with gold liquid in order to get scanning electron microscopy images (12× 12× 12 mm^3 parts). The deformed cells were photographed in 3D-plane with magnification of (100×), (1500×) and in the range of 3.0-5.0 kV light voltage under the scanning electron microscope. Unloaded and loaded pine wood specimens were visualized and photographed to observe and examine the contraction or expansion of the cell walls comparatively. Based on the experimentally obtained microstructural permanent deformations of the cell structures, a numerical model had been proposed to explain the complex behaviour of cell structures under compression loading. Using the finite element method and ANSYS code, the permanent deformation ratios of three different pinewood cell models were simulated for 35-40 MPa loading to explain the overall stiffness and strength of the pinewood cells. In this way, by considering the results obtained from scanning electron microscopy measurements and related finite element analysis solutions, permanent deformation of honeycomb type pinewood cells was examined in detail.
4
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Analysis of the Effect of Magnetostimulation on Viscoelastic Properties of Blood in Patients with Lasting Pain

75%
Marcinkowska-Gapińska A., Kowal P.
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vol. 125
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issue 4A
A-24-A-26
EN
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.
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