National Repository of Grey Literature 40 records found  previous11 - 20nextend  jump to record: Search took 0.00 seconds. 
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 bone density and its use for determination of biological age, prevention and indication of osteoporosis
Krátká, Jitka ; Ďoubal, Stanislav (advisor) ; Klemera, Petr (referee) ; Hála, Tomáš (referee)
The actual level of factual individual ageing of organism is characterized by biological age. By means of measuring function ability of physiological systems it is possible to evaluate the biological age and use it as an indicator of premature ageing and therefore as an indicator of the risk of getting ill. This study brings an overview of contemporary used, non-standard markers for the measurement of biological age and uncovers the possibility of measurement of biological age (BA) of skeleton and its use in osteoporosis precaution. Inclusion of BA measurement of skeleton into basic screening should bring another perspective how to measure objectively the changes in organism that correspond with ageing. Key words: biological age, osteoporosis, bone ageing, osteodenzitometry
Effect of piracetam on advanced dementia with predominated cardiovascular symptoms
Kovtun, Vladimír ; Ďoubal, Stanislav (advisor) ; Zadák, Zdeněk (referee) ; Mrňa, Boris (referee)
From 2001 to 2004 a retrospective non-invasive clinical trial on the effects off Piracetam was carried out in the nursing home in Česká Kamenice. The effect of Piracetam was observed on 150 patients aged 84,29 ( +- 3,5 years ) who suffered from an advanced form of vascular dementia. The patients were diagnosed in accordance with all currently valid criteria. At the time of the clinical trial the patients had been suffering from the disease for more than 6 months. A placebo was administered to the reference group composed of patients suffering from the same disease. The clinical trial lasted for a period of 12 months . The treatment with Piracetam did not demonstrate any positive effects which would be statistically substantial. This is probably due to an increased number of advanced forms of dementia syndrome with an irreversible loss of the brain's ability to compensate. For the above mentioned reasons an early diagnosis of demetia is of high importance because of a possibility to positively influence the disease. We assume that it is a task of an immense significance which goes beyond the boarders of the Czech Republic. Also, it raises the importance of geriatrics and gerontopharmacy on the societal ladder. Obviously, it is necessary to conduct further and much more extensive studies, which would...
Compressibility of the powder mixture with microcrystalline cellulose.
Hrdinová, Petra ; Řehula, Milan (advisor) ; Ďoubal, Stanislav (referee)
Compressing process can be evaluated by the parameters that are acquired from the record of force-run, stress relaxation or compaction equation. Compac- tion equation expresses the dependency on height, volume or density compression moulded material by pressure. In these thesis is pressing process characterized by parameters of compaction equation. Original Heckel equation declared range of pressing pressures, which caused plastic deformation of materials. Simultaneously pressed material is characterized by rate constant, expressing the rate of reduction of material in the plastic deformation. In these thesis is used triple - exponential equation, which was created at the Department of Pharmaceutical Technology and which is based on Cooper-Eaton equation. In a comparison between the Cooper- Eaton equation, the triple-exponential equation is not based on genuine values of density and detailed interpretation of the meaning of individual parameters. These thesis evaluates the granulate produced from a mixture of lactose monohydrate and microcrystalline cellulose and starch in mixtures where the microcrystalline cellulose is added at the concentration of 10, 20, 30, 40 %. The work results showed that with increasing reduction of volume, at the same time increases the volume of energy consumption and...
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...

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1 Doubal, Štěpán
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