|
Structure and Properties of Aluminium Cast Alloys
Samek, Petr ; Podrábský, Tomáš (referee) ; Juliš, Martin (advisor)
The bachelor work is focused on favour of relationship between structure and porperties of aluminium cast alloy AlSi7Mg0,6 in dependence of the effect of cooling rate. The AlSi7Mg0.6 alloy is commonly used in foundry industry to produce high stressed automotive components like motor blocks and cylinder heads. The properties of the material correspond directly to their microstructure which is given by the parameters of the solidification process. Within the frame of experiment were got structural characteristics (DAS, porosity) depending up on method of cooling. There were watched location of structure defects in volume of specimens.
|
|
Study of sterilization effect of dielectric barrier discharge on eucaryotic microorganisms
Vojkovská, Hana ; Ing.Hana Grossmannová, Ph.D. (referee) ; Kozáková, Zdenka (advisor)
Nowadays the wide spectrum of decontamination methods are used for the inactivation of microorganism on various materials and subjects. The serious disadvantage of the conventional decontaminations methods is stressing of the exposed material by heat or chemicals. The presented bachelor thesis discusses plasma sterilization, which is more friendly and more effective on the wide spectrum of procaryotic and eucaryotic microorganisms. Basically, the main inactivation factors for cells exposed to plasma are heat, UV radiation and various reactive species The work was focused on studying of the effect of the dielectric barrier discharge (DBD) operating at atmospheric pressure on bioindicator Aspergillus niger. Plasma was generated in nitrogen and argon. Paper and PET-foil wer used as the carrying medium. The influence of various working conditions on the efficiency of plasma sterilization was studied. Namely it was the influence of plasma exposition time, plasma power density, the type of operating gas and type of the medium supporting the microorganism. According to our results the efficiency of the plasma sterilization increases with increasing plasma power density, resp. the plasma exposition time. When comparing the results observed for the same conditions in argon and nitrogen the higher sterilization effect was reached in argon. The sterilization time was 40 – 120 second in dependence to plasma power density, gas and carrying medium. Furthermore the influence of the carrying medium on the sterilization efficiency was prooved. It was shown, that porous materials have a ”shadowing effect” for microorganisms. The microorganism may penetrate into the paper material and embed in pits and cavities. Such penetration could preclude the interaction of plasma with the microorganism, thereby decreasing the efficiency of spore inactivation. Additionaly paper porosity complicates the detachment of spores into solution, so it is reached less microorganisms as from the PET-foil. The discharge parameters were studied by means of the optical emission spectroscopy.
|
|
The creation of an educational program focused on dental hygiene for children at the 2nd grade of elementary school in České Budějovice.
VANIŠOVÁ, Hana
The bachelor thesis is focused on dental hygiene of children attending second grade of elementary school. Integral part of the thesis is an educational video program created for designated age bracket. The main goal of the thesis is an overall knowledge improvement of target audience in dental hygiene and highlighting of an oral hygiene importance in order to minimize the risk of dental carries and relation to a general health condition. The theoretical part is focused on children´s dentistry, dental anatomy and prevalent periodontal diseases like dental caries, gum inflammation or juvenile periodontitis. Considerable attention was paid to mechanical and chemical means and techniques of cleaning tooth. Next the theoretical part deals with primary prevention which is very important to avoid irreversible changes in oral health. Also influence and importance of proper nutrition for a good dental condition is mentioned. The practical part is formed on a questionnaire survey basis which was needful to map current dental hygiene level. Gathered information was essential for questionnaire processing, resulting in form of graphs and basis for content of the educational program. The main thesis aim is to stress necessity of a regular and a systematic dental care.
|
|
Predisposing factors of recurrent vulvovaginal candidiasis VI.
Pokorná, Michaela ; Kestřánek, Jan (referee) ; Jílek, Petr (advisor)
1. Summary This thesis examines the impact of life contentment, general attitude towards life, and stress on recurrent vulvovaginal candidiasis (RVVK) which is considered to be one of the most common vaginal infections. It is widely stated that approximately 75% of women suffer from vulvovaginal candidiasis at least once in a lifetime. The recurrent vulvovaginal candidiasis is defined as three, respectively four or more attacks of the vulvovaginal candidiasis within one year. Background: The aim of this thesis is to verify whether stress is one of RVVC initiating agents and whether method used of collecting data in homogenous cohort is usable for more heterogeneous and bigger group of women. Methods: Data from woman patients have been obtained through specifically designed questionnaires with one part comprising a set of questions aimed at life contentment and a degree of stress vulnerability. These questionnaires have been completed by 329 women, a return ratio of 82.7%). Data were statistically analysed by means of Student's t-test. Results: The findings reveal that the patients' contentment belonging to the RVVK category compared with a control group proves lower, in some areas showing even significant statistical disproportion. The most apparent discrepancy has been discovered in terms of contentment...
|
|
Physical properties of ultrafine-grained polycrystals of magnesium based alloys
Vrátná, Jitka
The objective of the thesis is the study of microstructure evolution, mechanical properties, defect structure and corrosion resistance of ultra-fine grained magnesium alloy AZ31 prepared by a combined two-step process: the extrusion and the equal-channel angular pressing (ECAP). The microstructure development was studied using light and transmission electron microscopy and electron backscatter diffraction (EBSD). Mechanical properties were studied by microhardness measurement and tensile tests and the defect structure by positron annihilation spectroscopy (PAS). The results of tensile tests indicates that the characteristic stress σ0.2 increases slightly with increasing number of ECAP passes only to the second pass and then decreases significantly with additional ECAP straining. This behaviour is in accordance with the results of PAS. EBSD measurements show that the microstructure of extruded and ECAPed material has a bimodal distribution of grain sizes. The bimodal distribution becomes homogeneous with increasing number of ECAP passes and no remaining large grains are observed after 8 passes. The average grain size in the specimen after 8 passes is in the submicrometer range and the fraction of high-angle grain boundary (HAGB) is approximately 80%. The extruded specimens after 8 ECAP passes show...
|
|
Screening of alkaloidal plants for antioxidant and anticholinesterase activity in vitro II.
Pšeničková, Jana ; Macáková, Kateřina (advisor) ; Karlíčková, Jana (referee)
Pšeničková, Jana. Screening of alkaloidal plants for antioxidant and anticholinesterase activity in vitro II. Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany and Ecology. 57 pp. Supervisor: Ing. Kateřina Macáková, Ph.D. Keywords: cholinesterase inhibition activity, antioxidant activity, alkaloids, Alzheimer's disease, oxidative stress Selected plant species of the families Papaveraceae, Fumariaceae and Ranunculaceae were tested in terms of this thesis. Alkaloid content was evaluated by a thin-layer chromatography (TLC); ethanol and alkaloid extracts were tested for their cholinesterase inhibitory activity and antioxidant activity. All of the studied species were tested for the cholinesterase inhibition activity by the Ellman's spectrophotometric method using the 5,5'-dithiobis-2-nitrobenzoic acid. The activity of extracts was compared with IC50 values of common inhibitors of cholinesterases: galanthamine (IC50 HuAChE = 2.59 ± 0.065 μg/ml, HuBuChE = 58.02 ± 1,30 μg/ml), and huperzine A (IC50 HuAChE = 0.061 ± 0.001 μg/ml, HuBuChE 1000 μg/ml). The highest cholinesterase inhibitory activity from the tested specimen showed ethanol extract from the aerial part of Glaucium corniculatum (IC50 AChE = 0,39 µg/ml, IC50 BuChE = 4,27 µg/ml). The species...
|
|
Nanocompression of oriented pillars from Al thin film
Kuběna, Ivo ; Kruml, Tomáš
In this paper, a new method of measurement of mechanical properties of thin films is presented. This method combines specimen preparation by focused ion beam (FIB) and compression test using nanoindentation device. Compression specimens were prepared from thin film, Al-1.5%Cu, which is commonly used in integrated circuit. Cylindrical specimens were prepared by FIB milling. The height of specimens (pillars) was about 2 mircrometers (equal to the film thickness) and their diameter was about 1.3 micrometers. The pillars are single crystalline, therefore the results depend on crystallographic orientation of pillar, which was specified by EBSD (electron backscatter diffraction). Stress-strain curves of the thin film were obtained in two representations.
|
|
The Methodology of Measurement of Biomechanical Properties of Biological Materials
Kuchařová, Monika ; Ďoubal, Stanislav (advisor) ; Hanuš, Josef (referee) ; Petrtýl, Miroslav (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of biophysics and physical chemistry Candidate: Mgr. Monika Kuchařová Supervisor: Prof. Ing. RNDr. Stanislav Ďoubal, CSc. Title of Doctoral Thesis: The methodology of measurement of biomechanical properties of biological materials As a part of this dissertation thesis a methodology of measurement of mechanical properties of viscoelastic materials was developed. The methodology was then verified and applied in measurement of shoulder-blades of pheasants and in measurement of the trabecular section of human caput femoris in bending and twisting stress, viscoelastic parameters of these materials were also calculated. Results, in the case of human bones, were compared with measurement of body mass density and content of vitamin D. Mechanical behaviour of many biological materials corresponds to the behaviour of so- called viscoelastic body. These materials cannot be categorized simply as solids or liquids. The mechanical behaviour of this type of materials has partially elastic and partially viscose character. Skin, cell walls, bones, numerous structures of internal organs and many other materials belong to this category. In spite of the fact that in physiological conditions biological materials are loaded dynamically, in...
|
|
Dissociation in adolescence. Validation of the Czech version of the A-DES in the clinical and non-clinical group of adolescents
Soukup, Jan ; Papežová, Hana (advisor) ; Hrdlička, Michal (referee) ; Praško, Ján (referee)
The purpose of this study was to find psychometric properties of the Czech language version of the Adolescent Dissociative Experiences Scale (Armstrong et al., 1997). 653 non-clinical participants and 162 adolescent psychiatric inpatients completed Czech versions of the A-DES and SDQ-20 questionnaires (Somatoform dissociative questionnaire; Nijenhuis et al., 1996), and provided further information (data regarding demographic variables, diagnoses, further psychopathology). The Czech A-DES has very good internal consistency, test-retest reliability and a good validity, though its predictive power is limited. The ADES scores significantly correlate with the measure of somatoform dissociation, self injurious behavior, reported traumatic experiences, a presence of clinician-observed dissociative symptoms, and polysymptomatic diagnostic picture (three comorbid diagnoses, differential diagnosis). A-DES scores were significantly higher in ADHD group, but not in a group with a diagnosis of a dissociative disorder. The study supports the intercultural validity of the concept of the dissociation and its clinical correlates; however, further research of the intercultural differences is needed. The authors stress the need to screen all adolescent psychiatric patients for dissociation, especially those who show more...
|
|
Risk factors for atherosclerosis and its potential pharmacological effects in patients with coronary artery disease and lower limb
Hromádka, Milan ; Filipovský, Jan (advisor) ; Piťha, Jan (referee) ; Šimon, Jaroslav (referee)
1 Statin therapy in patients with peripheral artery obstructive disease (PAOD) 1.1 Patients with lipid metabolism disorders Simvastatin therapy with the dose titration adjusted to the effect led to the prolongation of claudication interval and to the elevation of ankle-brachial pressure index, which was statistically significant at the interval of 18 months after starting the therapy. At the same time we observed normalization of lipid levels and the lowest levels of oxidative stress markers. Statin use was also associated with lowering homocysteine level. 1.2 Patients without lipid metabolism disorders - the influence on laboratory parameters and functional capacity In patients without lipid metabolism disorder, treated with simvastatin 20 mg daily, we noted an improvement, i.e. prolongation of claudication interval and elevation of ankle-brachial pressure index, while in the control group treated only with a diet we observed further deterioration of capacity. In the control group, the parameters of lipid metabolism were statistically significantly worse after six months and this trend remained even in further control visits with HDL cholesterol slightly lowering. In the simvastatin group, a statistically significant decrease of LDL occurred during several months as well as elevation of HDL...
|
guest ::
