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Advanced Magnesium Alloys Surface Modification by Ni-P Based Coatings
Kosár, Petr ; Pacal, Bohumil (referee) ; Nový,, František (referee) ; Havlica, Jaromír (advisor)
The dissertation thesis deals with the modification of the surface of advanced magnesium alloys with Ni-P based coatings. At the beginning of the theoretical part, the structures of the used magnesium alloys and the influence of individual alloying elements on their properties are characterized. In the following part of the thesis the current knowledge in the field of electroless deposition on metal substrates is summarized. The theoretical part of the thesis is closed with contemporary research study in the field of clarification and determination of possible mechanism of electroless deposition. For the subsequent investigation of the mechanism of electroless deposition on magnesium alloys, it was necessary to characterize the microstructure and composition of individual magnesium alloys in the first phase of the experimental part. The exact composition of elements was determined using glow discharge optical emission spectroscopy and scanning electron microscopy with EDS was used for composition of phases of magnesium alloys. Using scanning electron microscopy and detailed elemental analysis of the coated magnesium substrate, it was found that for optimal Ni-P coating deposition on magnesium alloys, acid pickling prior coating is required in a mixture of acetic acid and sodium nitrate. Using the XPS method, it was found that the phosphorus atom in the sodium dihydride-diphosphate reducing agent has a + V charge. 4 At the end of the experimental part scanning electron microscopy and detailed elemental analyses were used for monitoring of the Ni-P particles nucleation and growth in the first 120 seconds of the coating process.
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Obsah přiboudliny v ovocných destilátech
Borko, Jozef
Fusel typical compounds for fruit juices, but also for distillate fractions (Luther head, heart, tail). Of the varieties TOPAZ was ready to leaven, which was converted by distillation to the mentioned distillate fractions. Samples of fresh apple juice and distillate stocks were stored in a cooling box at - 18 ° C. Analysis of fusel oils and other ingredients of fabric were determined SPME / GC / MS. Analytical treated sample (captured in the hollow fiber), followed by desorption of the liquid was divided column. The mass spectrometer analytical peaks quantified according to the standard for which is a recognized m / z. Of the amount of the analyte for each analytical unit (juice - boiling fraction) were separated substance of analytical chemical group of the alcohols, branched alcohols, aldehydes, ketones, esters and terpenes.
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Studium vlivu teploty na obsah antioxidantů při přípravě zelených čajů
Blažková, Lucie
Tea is one of the most popular beverages worldwide. It was demonstrated that the beverage prepared by leaching of leaves of Camellia sinensis in hot water, has a positive effect on human organism in many cases. The substances found in green tea have antioxidant properties and positive effects on the prevention of many diseases. The beneficial effects are attributed mainly due to plant phenols whose antioxidative activity protects the body against free radicals. In this work the content of selected biologically active compounds in extracts of loose green teas was determined using modern bioanalytical methods. The amount of natural antioxidants determined in tea from Japan and China at different preparation temperatures of the tea extract solution were compared.
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Charakteristika a metody stanovení vitaminů v masozeleninových přesnídávkách určených pro dětskou výživu
Piechowiczová, Markéta
Bachelor thesis Characteristics and methods for determination of vitamins in meat-vegetables purées intended for baby food was focused on acquiring general knowledge about child nutrition, with regard to adequate intake of vitamins in the diet, which are then characterized, together with methods of their determination. In the first part there are described particular periods of nourishment until 12th month of life. Nourishment recommendations are summarized here, more specifically required nutrients in this age, but also issues concerning allergies, alternative nourishment and some diseases, which can lead to hypovitaminosis. The second part is devoted to the characteristics of vitamins. Chemical properties, effect on the body, occurrence in foods and the recommended daily intake are included. The chapter about occurrence in food is always accompanied by the recommendation of ingredients with a high content of vitamins, which are appropriate to add to complementary food. In the last part of thesis the methodology for determination of vitamins are summarized in the light of the newest trends. These methods include chromatographic methods, spectrophotometric,fluorimetric, polarographic, microbiological and capillary electrophoresis.
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Acrylamide in potato products
Jiruška, Jan ; Sedláková, Vladimíra (advisor) ; Dvořák, Petr (referee)
This thesis provides a review describing acrylamide (AA), its detection and reduction. Botanical description and list of registered varieties of Solanum tuberosum in the Czech Republic is provided. Attention is payed to chemical composition of tubers. Next step is about AA. AA can cause carcinogenic and neurotoxic effects, particularly because it can be converted to a more reactive compound glycidamide in a human body. Thanks to animal experiments, we can reveal negative effects on the human body.
AA is formed by heat treatment over 120 °C in potatoes. Therefore, it is in potato chips and crisps. It is reaction of the free amino acids (especially asparagine) and reducing sugars (mostly glucose or fructose). It is all about several consecutive reactions that are included in the Maillard reaction. This reaction causes typical taste and aroma in products. Unfortunately, AA is one of the byproducts.
Today, formation of acrylamide has growing attention, because scientists want to reduce it as much as possible. Growing, industrial processing of potatoes and addition of additives during heat treatment is included. Antioxidants can significantly prevent formation of AA in food. There are also gathered informations on advanced analytical methods to detect AA in food. Rapid methods of detection are becoming more popular by scientits, that is why they are also included.
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Analytické a senzorické možnosti kontroly falšování pravosti révového vína
Rozek, Kamil
The diploma thesis deals with analytical and sensorial possibilities of control of grape wine adulteration. In the first, theoretical part of the thesis, the author introduces valid legislation regulating authorized substances in wine, as well as the wine production processes itself. The reader is acquainted with the means of wine adulteration in the Czech Republic that ensued from an analysis of unsatisfactory samples of wine, collected between 2012 -- 2015 by the SZPI (Czech Agriculture and Food Inspection Authority). The second, practical part of the thesis, describes not only grape wine and SZPI samples imitation production processes, but also methods used for their subsequent sensorial and analytical study. Besides, it interprets measured data, and compares and contrasts the possibilities and appropriateness of the sensorial evaluation and analytical study for the detection of wine adulteration.
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Analysis of the Selected Company by the Selective Methods
Volková, Ludmila ; Tihlařík, Michal (referee) ; Hanušová, Helena (advisor)
This master´s thesis is focused on analysis of the company which is situated in the pro-duction of plastic windows and profile systems. Analysis of the actual state is made through the analysis of the inner and outer environment, financial situaction is estimated with the Kralicek Quick Test. Thesis includes suggestions and recommendations which will cause improvement of the situation at general in following years.
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Possibilities of determination of metalocompounds present in living systems
Hauerlandová, Petra ; Zemanová, Jana (referee) ; Vitoulová, Eva (advisor)
This bachelor thesis deals with the topic of metallomics. There are explained basic concepts and definitions, differences between the metal-binding proteins and metalloproteins. This thesis also deals with metallothioneins and theirs basic types. The study describes possible interactions of metals and organic compounds. Attention is paid to interactions between metals and peptides or proteins. There are given examples of some essential metals, which are linked to important organic compounds, which are necessary for the proper function of the organism. Mainly there are described enzymes necessary for the human body. There are also referred organic compounds of toxic metals. Another part of the thesis is devoted to analytical methods used for determination of metallocompounds. There are described methods for separation and detection, which are combined for qualification and quantification of metallocompounds. There are referred examples of the determination of some metallocompounds.
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Analysis of elements in nutrition supplements
Motlová, Tereza ; Navrátilová, Jana (referee) ; Vitoulová, Eva (advisor)
This bachelor thesis deals with food supplements, mineral elements and their determination in dietary supplements. The aim of this thesis was to elaborate a literature review focused on the food supplements, mineral elements, which are used in food supplements, and methods for determination of mineral elements in nutrition supplements. Forepart of this bachelor treats of food supplements, their basic categories, mineral elements which are contained in nutrition supplements and their effects in case of their oversupply (at high doses) or lack (at low concentrations) in a human body. Other part of this thesis is concerned with options of mineral elements determination in food supplements. Thereinafter, the thesis deals with ways of preparing samples for determination and analytical methods which are used for determination of mineral elements in nutrition supplements. Food supplements are foodstuffs which serve to direct consumption. Supplements differ from casually foodstuffs by high contents of vitamins, mineral elements and others matters which have nutrition and physiological effect. Food supplements are manufactured in order to achieve a diet completion of common user with positive impact on human health.
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