National Repository of Grey Literature 24 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Biomechanical Properties of Bones in the Experiment and the Effect of Homocysteine in Bone Health
Řeháčková, Petra ; Ďoubal, Stanislav (advisor) ; Klemera, Petr (referee) ; Payer, Juraj (referee)
1 ABSTRACT Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: PharmDr. Petra Řeháčková Supervisor: Prof. RNDr. Ing. Stanislav Ďoubal, CSc. Consultants: Doc. MUDr. Štěpán Kutílek, CSc.; Doc. MUDr. Sylva Skálová, Ph.D. Title of Doctoral Thesis: Biomechanical properties of bones in the experiment and the effect of homocysteine on bone health The Doctoral Thesis comprises two basic parts - the Experimental and Clinical. The former one addresses viscoelastic properties of biological materials, in particular bones under dynamic strain. The latter one focuses on the effect of elevated homocysteine levels on bone health. The Introduction includes detailed anatomical description and physiology of human bone, its development, metabolism, and finally some metabolic disorders, the impact of nourishment on its quality and the impact of homocysteine on bone health. Furthermore, the Introduction contains description of Rheological models (described by Hooke's and Newton's elements). As porcine bones resemble human bones in their structure and biomechanical properties, they were used in the Experimental part with the main objective to verify, investigate and measure their characteristics. Two series of measurement with moderate changes in...
: Viscoelasticity of bones - the methodology of measurement
Cihlář, Zdeněk ; Ďoubal, Stanislav (advisor) ; Kuchařová, Monika (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of biophysics and physical chemistry Candidate: Mgr. Zdeněk Cihlář Supervisor: Prof. RNDr. Ing. Stanislav Ďoubal, CSc. Title of Thesis: Viscoelasticity of bones - the methodology of measurement The aim of the thesis was to verify the methodology of measuring the viscoelastic parameters of human bones using an apparatus enabling the measurement of dynamic characteristics. The method is based on measurement of deformation response of samples to short or rectangular impulse of force. The samples were obtained from femoral head. The methodology is therefore based on measuring of creep curves and impulse characteristics. Resulting damped oscillations were analysed. The transient and impulse characteristics in bending stress and twisting stress were obtained. Based on these characteristics, viscoelastic parameters of samples were determined (Young modulus, shear modulus and viscosity). The Poisson's number, indicating the ratio of transverse contraction to longitudinal extension of the material during deformation, was calculated using the values of Young's modulus and shear modulus. The measured values of the Young's modulus in bending stress vary in the range from 62MPa to 670MPa. The values of the shear stress modulus range...
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...
Measurement of the skin mechanical properties after application of the anti-aging product
Lejsalová, Alžběta ; Kuchařová, Monika (advisor) ; Ďoubal, Stanislav (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of biophysics and physical chemistry Candidate: Mgr. Alžběta Lejsalová Supervisor: Mgr. Monika Kuchařová, PhD. Title of Thesis: Measurement of the skin mechanical properties after application of the anti-aging product The maintaince of youthful skin appearance is strongly desired by the sociaty nowadays. A lot of anti-aging strategies, agents and procedures have been already described but it is difficult to measure the effectiveness of these products and methods. Viscoelastometer developed at the Faculty of Pharmacy in Hradec Králové offers a quick and painless measurement of basic mechanical parameters of the skin, stiffness and viscosity. Previous researches indicate that these parameters vary with age. The aim of this study was to determinate the effect of anti-aging product on these mechanical parameters. Twenty volunteers (women aged 25 - 67 years) used the tested product Vichy Liftactiv Serum 10 twice a day for two months. During the experiment skin mechanical properties were measured at the application site and the obtained values were compared by the t-test. The theoretical part is focused on characterizing the basic anatomical, physiological and biomechanical properties of the skin, describes the aging process...
Measurement of changes in mechanical properties of human skin after application of therapeutic laser.
Jurčíová, Veronika ; Kuchařová, Monika (advisor) ; Ďoubal, Stanislav (referee)
Charles Univerzity in Prague Faculty of Pharmacy in Hradec Králové Department of Biophysics and Physical Chemistry Candidate: Veronika Jurčíová Sepervizor: Mgr. Monika Kuchařová, Ph.D. Title of diploma thesis: Measurement of changes in mechanical properties of human skin after application of therapeutic laser This diploma thesis describes in the theoretical part the properties of human skin, the properties of laser radiation and the nature of interaction of laser radiation with human skin. The practical part deals with an in vivo measurement of changes in mechanical parameters of human skin after application of therapeutic laser radiation. The mechanical parameters of human skin were measured in ten volunteers before the application of laser radiation and then after the application. Used energy density of the laser radiation increased from 30 to 90 J·cm-2 . The observed parameters were Hooke's coefficient, Newton's coefficient and the time constant. Hooke's coefficient describes the stiffness of the skin as a whole, Newton's coefficient characterises the viscosity of the skin, the time constant is the time in which skin returns to the original state after deformation. For measurement of those parameters was used dynamic elastometer. It was found out that the changes of Hooke's and Newton's...
The Optimalization of Nutrition for Elderly People-Evaluating the Impact of Diet
Salfická, Monika ; Ďoubal, Stanislav (advisor) ; Kuchařová, Monika (referee)
Title: The Optimization of Nutrition for Elderly People-Evaluation of the Effectiveness of Diet Summary: This bachelor thesis deals with a question of nutrition and using diets in aging persons. The theoretical part focuses on explaining term of aging and old age in the field of gerontology. This part contains, inter alia, a description of the manifestations of aging on the appearance, movement and mentality. The next section informs about the "right" nutrition throughout life, as we age the moment we are born. In conclusion the theoretical part we find basic information on diet, malnutrition, obesity and diabetes mellitus. The empirical section presents the results of the survey. The survey involved 18 respondents from dietary counseling UROCONT Ltd. in Pardubice and 46 respondents of Flora. The aim of the study was to compare the data of men and women within the age categories. Learn how different Body Mass Index (BMI), Waist to Hip Ratio (WHR), Percent Body Fat (PBF) in patients affected by diabetes and patients healthy. Key words: aging, age, nutrition, diet, obesity, malnutrition, diabetes mellitus, WHR, PBF, BMI, waist circumference
Compressibility of powder mixture with antifrictional agents.
Motlová, Tereza ; Řehula, Milan (advisor) ; Ďoubal, Stanislav (referee)
The tablet is formed by the effect of compression force during compression process. The supplied energy is consumed in the formation bonds between particles and molecules of compressed material. For that reason it is important to determine the size of energy to be applied for forming tablets. The most common method for detecting the size of the energy is rating of force- displacement profile. In this work were monitored two factors affecting energy compressing. It was a compression pressures of size 5, 10 and 15 kN and research of the influence of frictional materials on the energy compressing. These effects were observed for tablets compressed from microcrystalline cellulose Avicel PH 102. As the frictional material was used magnesium stearate, Aerosil 200, Syloid AL - 1 and Syloid 244. As the parameters of energy were evaluated the following parameters: pre-compression energy E1, plastic energy E2, elastic energy E3, energy used for the compression Elis, total energy Emax and plasticity. The results of this work indicates that compression pressure increases the studied energy except plasticity, where is reduced of this parameter. The presence of friction substances reduces parameter E1, E2, Elis, Emax and plasticity and on the contrary increases the parameter E3.
The influence of parameters of samples on mechanical properties of biological materials
Roušarová, Pavla ; Kuchařová, Monika (advisor) ; Ďoubal, Stanislav (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 parameters of samples on mechanical properties of biological materials. In this diploma thesis I dealt with the influence of dimensions of samples of biological material, namely bovine bones, to change their mechanical characteristics measured in static and dynamic mode. Samples were measured on a dynamic elastomers developed at the Department of Biophysics and Physical Chemistry. For our experiment we obtained three samples that had different dimensions, in terms of width, height and length. It was the shin bone (tibia) of a young bull (Bos taurus primigenius f). Animal slaughter age was 20 weeks and the bones were obtained 1 day after slaughter. Impulse response for each sample was measured three times. After every fifth repeated measurements, the distance between the sample and movable measuring system has shrunk by 2 mm. The computer evaluated dynamic modul Ed and viscosity η - which we then transformed into a graph, such as dependence on length. Step characteristic for each sample was measured three times. After every fifth repeated measurements, the distance between the...

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1 Doubal, Štěpán
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