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Optimization of condition of procedure of gelation hydroxyethylcellulose using citric acid
Burešová, Natálie ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
The bachelor thesis dealt with hydrogels, which have the advantage detention large quantities of water, it allows large potential applications, such as in medicine. Hyaluronan and hydroxyethylcellulose were the reactants of crosslinking reaction. Citric acid was crosslinking agent which is nontoxic and inexpensive. Hydroxyethylcellulose and hyaluronan for crosslinking reaction were selected on the finding from available publications. The resulting gels can be used mainly in medicine because they are nontoxic. The main aim of the thesis was optimalizacion process of gelation and hydroxyethylcellulose and finding a suitable gelation process. Selected gelation procedure is applied to a mixture of hydroxyethyl cellulose and hyaluronan in two different weight ratios and hyaluronan. Chemicaly cross-linked were considered samples, which contained hydroxyethylcellulose and then a mixture of hyaluronate and hydroxyethyl cellulose in a weight ratio of 3:7.
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The gelation of hydroxyethylcellulose and hyaluronan using citric acid
Martinková, Martina ; Krouská, Jitka (referee) ; Hurčíková, Andrea (advisor)
This master's thesis deals with gelation of hydroxyethylcellulose and hyaluronan crosslinked with nontoxic crosslinking agent – citric acid. First of all, the optimalization of gelation process of hydroxyethylcellulose took place. After obtaining the product insolube in the ultrapure deionized water, a reaction mixture of hyaluronan and hydroxyethylcellulose in two different weight ratios were prepared. There was prepared solution containing only hyaluronan as the polymeric part too. Citric acid was used in concentrations of 5 %, 10 % and 20 % (w/w of polymer). These solutions of polymers and citric acid were gelated under the same conditions and the products were compared to each other using Differential Scanning Calorimetry, Thermogravimetry and Fourier Transform Infrared Spectroscopy. The products containing hydroxyethylcellulose and hyaluronan with hydroxyethylcellulose in weight ratio equal to 3 : 7 were considered crosslinked.
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Evaluation of Milk Quality in Conventional and Ecological Breeding of Cattle
TSCHERNAYOVÁ, Kateřina
In my work are confronted two farms with cattle breeding in Southbohemical district. One of them is farming ecological and the other conventional. Both farms are situated in the foothills of the Bohemian Forest. On the farms are bred two breeds- Holstein and Czech Spotted Cattle, on each one hundert cattles. I focused on composition of feeding ration, feed quality and its prospective influence on milk composition. In work are graphic compared the reservoir samples of milk from ecological and conventional farm with average values of districts České Budějovice and Český Krumlov. There are also compared for example milk fat, protein and somatic cells. In individual samples were analysed- citric acid, pH and conductivity of milk.
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