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Effect of UV radiation on the change of mechanical parameters of human skin
Mazouchová, Denisa ; Kuchařová, Monika (advisor) ; Klemera, Petr (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: Denisa Mazouchová Supervizor: Mgr. Monika Kuchařová, Ph.D. Title of diploma thesis: Effect of ultraviolet radiation on the change the mechanical parameters of human skin This diploma thesis deals in theoretical part with the properties of human skin, the characteristics of the UV radiation and its effects on human skin. The practical part of the thesis focuses on the in vivo measurement of mechanical parameters of human skin after UV radiation. Mechanical characteristics of human skin were measured in 12 subjects before the application of UV radiation, immediately after application of UV and after 24 hours of rest skin. The experiment used a UV lamp with a wavelength of 370 nm emitted light. The monitored parameters were Hooke's and Newton's coefficients. Hooke's coefficient gives us the stiffness of the skin as a whole , Newton coefficient characterises its viscosity. For measurement of those parameters was used dynamic viscoelastomer. The experiment has been found out that no signifiant ganges of Hooke's and Newton's coefficients were not found immediately after the application of UV radiation of wavelength 370 nm, in 12 volunteers. Significant change occurred only in the...
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Biomechanics of veins and vein's substitutes
Stošek, Zdeněk ; Ďoubal, Stanislav (advisor) ; Klemera, Petr (referee)
Mechanical properties of vessel walls influence many physiological functions of organisms and its health status. Biomechanical changes in mechanical properties of vessels accompany process of aging. Consequently, biomechanical characteristics may be marker of aging. Aim of this work was identification of biomechanical characteristics of pig aorta walls on the basis of measurement of impulse and transient mechanical responses of deformation on stress. Work also analyzed linearity of parameters. Measurements were performed by instruments developed on department of biophysics and physical chemistry.
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The influence of frequency on values of mechanical parameters of biological samples
Roušarová, Pavla ; Kuchařová, Monika (advisor) ; Klemera, Petr (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of biophysics and physical chemistry Candidate: Pavla Roušarová Supervisor: Mgr. Monika Kuchařová Ph.D. Title of diploma thesis: The influence of frequency on values of mechanical parameters of biological samples My diploma thesis builds on my diploma work, in which I investigated the effect of sizes of samples of biological materials on changes of their mechanical properties when measured in static and dynamic mode. In this work, I examined the influence of frequency f [Hz] on the values of the mechanical parameters of biological samples. The frequency gradually decreased during the measurement. I did the measurements in dynamic mode resonance analyzer, which was developed at the Department of Biophysics and Physical Chemistry. I obtained samples of the shin bone (tibia) of a young bull (Bos primigenius f. taurus) for the purpose of the measurements. The animal was slaughtered at the age of 20 weeks. The bones were obtained one day after slaughter. For our experiment, I received three samples that had different dimensions (height, width and length). During the measurement, a frequency f [Hz] was always diminished by using a weight that was affixed to the movable part of the measuring instrument. At each frequency, the...
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In-vivo measurement of mechanical properties of biological materials
Čermáková, Viola ; Kuchařová, Monika (advisor) ; Klemera, Petr (referee)
Measurement of mechanical properties of many biological materials in vivo is based on the assumption that they can be considered as a visco-elastic body. This means that their mechanical properties under dynamic loading response partly to viscous and partly to elastic character. The visco-elastic biological materials include skin, blood walls, vessels, bones, tendons etc. Mechanical properties of biological materials depend on the structure of the material from the molecular to the macroscopic level. They also depend on age and health status of the organism. Obtaining of the standard values of mechanical parameters would be potentially useful as an indicators of functional age of organism also to study the influence of external factors (cosmetics, UV radiation) to changing the properties of biological materials and as well in terms of compatibility with artificial materials. To understand the ongoing processes in the skin, which was chosen as a biological material for measurement of mechanical properties in this thesis, the anatomical and physiological characteristic, including biochemical processes taking place in the synthesis of the main building components of the skin are needed to know. Aging of the skin is a complex biological phenomen consisting of two main parts of the so-called intrinsic...
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Methods of measurement and evaluation of biological age
Řeháková, Štěpánka ; Klemera, Petr (advisor) ; Ďoubal, Stanislav (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: Štěpánka Řeháková Supervisor: doc. RNDr. Petr Klemera, CSc. Title of diploma thesis: Methods of measurement and evaluation of biological age The theoretical part of this thesis deals with theories of aging, the concept of biological age, biomarkers of aging and the evaluation of various methods of determining of the biological age of people. Real data are evaluated in the practical part by using the program BIOLVEK. Simulated data with different selected parameters, generated and evaluated by program BIOLVEK, verify some characteristics of the methodology resulting from the theory. It is mainly about to assess the real possibility of estimating of the true variability of differences between biological and chronological age and about to what extent the inaccuracies of the estimate affect the error of estimate of biological age. Key words: biological age, biomarkers, estimation of biological age, aging
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Significance of frequency of measurement on describing linear mechanical systems - in- vivo measurements
Kohoutová, Tereza ; Kuchařová, Monika (advisor) ; Klemera, Petr (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: Tereza Kohoutová Supervisor: Mgr. Monika Kuchařová, Ph.D. Title of diploma thesis: Significance of frequency of measurement on describing linear mechanical systems - in vivo measurements This diploma thesis in its theoretical part deals with description of skin and its functions and properties. The main subject of interest are the mechanical properties of the skin. Second component of the theoretical part is a chapter about rheology and its importance for characterisation of mechanical properties especially biological materials. The practical part is focused on in vivo measurement of mechanical parameters of human skin and on finding dependence of Hooke's and Newton's coefficients on frequency of the measurements. Hooke's coefficient represents the elastic part of the skin. Newton's coefficient characterises its viscosity. The method used was based on measuring impulse response with the dynamic viscoelastometer. Measurements took place on ten female volunteers. During the experiment we were changing the mass of the measuring probe with weights, thereby altering the frequency of measurement. By this proceeding we were able to discover the dependence of both coefficients on...
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Quantification of viscoelastic properties of porcine aortic walls in dependence on direction of strain, distance from heart and age of donors
Tobias, Miriam Christine ; Ďoubal, Stanislav (advisor) ; Klemera, Petr (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Department of Biophysics and Physical Chemistry on direction of strain, distance from heart and age of donors Mechanical behaviour of biological structures depends on elastic, as well as viscous properties of biological materials. The main problem is the identification of models and the estimation of their parameters. Practically, the static deformation responses are combined with various dynamic characteristics. In most cases, transient and frequency characteristics or creep curves are being used in available appliances. Apparatuses based on these principles are technically complicated and expensive. One aim of our research was to alleviate this situation. Furthermore our aim was to investigate in a phenomenological study quantitative differences in viscoelastic parameters of porcine aortic walls in dependence on distance to heart, direction of strain, and age of donors. For that reason we developed appliance based on measurements of self-oscillation of sample of material simulating the dynamic loading to get information about the relationship between harmonic stress and loading, and simulating dissipation of energy in real systems. In order to obtain relevant information from the experiment, the load and deformation...
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