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A study of the compressibility of directly compressible tableting materials for matrix tablets with ascorbic acid.
Mačková, Hana ; Mužíková, Jitka (advisor) ; Ondrejček, Pavel (referee)
This thesis evaluates and compares compressibility of directly compressible tableting materials for the preparation of matrix tablets containing ascorbic acid. Avicel® PH 102 was used as the dry binder. The hydrophilic matrix tablets contained carbomers (Carbopol® 71G NF) or hypromellose (MethocelTM K15M) in concentration of 20 % or both in concentration of 10 % , the lipophilic matrix tablets contained glycerol dibehenate (Compritol® 888 ATO). The dual matrix tablets contained both types of retarding materials in concentration of 10 %. Sodium stearyl fumarate was used as the lubricant in concentration of 1 %. The compressibility was evaluated by means of the energy profile of the compression process and determination of tensile strength of the tablets. The total energy of compression increased with the increase of compression force, the tableting material with 20 % of MethocelTM K15M showed the highest values. Plasticity decreased with compression force, the tableting material with 20 % of Carbopol® G and the tableting material with MethocelTM K15M showed the highest values. The tensile strength of tablets increased with compression force, the strongest tablets were the ones containing 20 % of Compritol® 888 ATO, with the exception of compression force of 8 kN. In this case the strongest tables...
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A study of the compressibility of directly compressible tableting materials for matrix tablets with ascorbic acid.
Mačková, Hana ; Mužíková, Jitka (advisor) ; Ondrejček, Pavel (referee)
This thesis evaluates and compares compressibility of directly compressible tableting materials for the preparation of matrix tablets containing ascorbic acid. Avicel® PH 102 was used as the dry binder. The hydrophilic matrix tablets contained carbomers (Carbopol® 71G NF) or hypromellose (MethocelTM K15M) in concentration of 20 % or both in concentration of 10 % , the lipophilic matrix tablets contained glycerol dibehenate (Compritol® 888 ATO). The dual matrix tablets contained both types of retarding materials in concentration of 10 %. Sodium stearyl fumarate was used as the lubricant in concentration of 1 %. The compressibility was evaluated by means of the energy profile of the compression process and determination of tensile strength of the tablets. The total energy of compression increased with the increase of compression force, the tableting material with 20 % of MethocelTM K15M showed the highest values. Plasticity decreased with compression force, the tableting material with 20 % of Carbopol® G and the tableting material with MethocelTM K15M showed the highest values. The tensile strength of tablets increased with compression force, the strongest tablets were the ones containing 20 % of Compritol® 888 ATO, with the exception of compression force of 8 kN. In this case the strongest tables...
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Neinvazivní potické měření deformací elastických trubic
Macková, H. ; Chlup, Hynek ; Žitný, R.
Noninvasive optical measurement and evaluation of the pulse wave velocity of a self-oscillating elastic tube was done. A latex tube was loaded by self-excited internal pulsatile flow as a simple model of human big arteries. The method is based on evaluation of high speed camera recordings and edges detection algorithm. Displacements of the tube edge were evaluated by a given scale factor from a standard gauge inserted to the recorded scene. Our goal is to recognize the pulse wave and measure its velocity along the tube.
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Konstitutivní modelování tepenné stěny
Horný, L. ; Chlup, Hynek ; Adámek, T. ; Zitny, R. ; Macková, H.
Inflation tests and uni–axial extension tests of arterial tissue were performed. Experimental data were used in nonlinear regression analysis to identify material model. Arterial tissue was assumed to be incompressible hyperelastic material. 5–parameter strain energy density function based on combination of isotropic Neo–Hookean expression and Fung–type orthotropic expression was used. Computational model for material parameters identification was based on thick–wall tube with axial pre–strains. Residual strains were included. Internal structure of arterial wall was not considered. Fitted material models correspond to experimental data very well.
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Optimalizace měření rychlosti pulzní vlny v tepnách
Macková, H. ; Chlup, Hynek ; Hulan, M. ; Žitný, R.
Measurements of the pulse wave velocity (PWV) in human arteries are important for two different reasons: an early diagnostics of atherosclerosis and identification of material properties of the vessel wall for numerical simulations. The PWV in blood vessels is not constant and classical methods of pressure wave shift between two points are not sufficient. We consider three methods: optical measurements of vessel wall displacement in several points by high speed camera, continual optical measurements of vessel wall displacement by correlator Q-450 and measurements of flow rate and displacements by ultrasonic device. The first method can determine the PWV only between several points. The second method can show 3D reconstruction of displacements with very good resolution. The ultrasound measurements need combination of Doppler ultrasound velocimetry and B-scan imagining. However, the common devices used in medicine do not have any data output. It causes bad resolution.
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Experimentální měření pulzní vlny v elastické trubici
Chlup, Hynek ; Macková, H. ; Žitný, R. ; Konvičková, S.
The pulse wave velocity (PWV) in blood vessels is one of the important hemodynamical parameters for detection of artery health condition. In our laboratory, the PWV in elastic tubes and arteries is measured in vitro. The method is based on optical measurements of displacement of the pulsating tube wall. A high frame rate camera was used. The obtained data were evaluated by several methods and compared. The measured pulse wave velocities were in the same order of magnitude as values based on theoretical calculations and published physiological data.
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Samobuzené oscilace elastické trubice
Chlup, Hynek ; Macková, H. ; Maršík, František ; Konvičková, S.
Our paper studies experimentally the self-excited oscillations of thin-walled elastic tubes with respect to the Korotkoff sounds. The self-excited oscillation is a phenomenon, when an elastic tube looses stability of its shape and starts to oscillate, loaded only by continual flow, therefore without any external excitation. An experimental set-up was designed for the experiments. The mean flow rates, pressures at the ends of the tube and external pressures were recorded under various modes of oscillation. The effective cross-section and elastic modulus of the tube were calculated by simplified formulas. The data analysis showed an increase of the oscillation frequency with a decrease of the tube wall compliance. It means the frequency of the oscillation is dependent on ratio of the wall thickness and the tube diameter. The mode of the oscillation is also influenced by the transmural pressure.
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Detection of the pulse wave velocity in an elastic tube
Chlup, Hynek ; Macková, H. ; Vilímek, M. ; Žitný, R. ; Konvičková, S.
The velocity of the pulse wave in blood vessels is one of the important hemodynamical parameters to detect health condition or a degree of damage of a diseased artery. To understand the problem, the physiological values must be known. In our laboratory, the velocity of pulsewave in elastic tubes and arteries is measured in vitro by non-invasive method. The method is based on optical measurements of displacement of the pulsating pipe wall. A crash test camera with high frame rate of 1000 Hz (fps) was used.
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Physical model of the bloodstream systemic resistance enabeling partical transport
Chlup, Hynek ; Macková, H. ; Žitný, R. ; Konvičková, S.
One of the basic elements of an experimental line simulating a cardiovascular system is an element simulating blood stream peripheral resistance. This element is being developed in the Laboratory of Human Biomechanics, CTU Prague. The element is a part of the experimental line for in vitro monitoring of pulse wave speed in thin walled elastic pipes and blood vessels. From the pulse wave speed measured invasively or non-invasively, material properties of the vessel walls could be determined. The element consists from numerous flow splits and resistance segments. The total hydraulic resistance could be controlled by number of active resistance segments.
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