Vliv hyaluronanu na micelizaci tenzidů byl studován různými fyzikálně-chemickými metodami. Byly zvoleny dva kationaktivní tenzidy, a to tetradecyltrimethylammonium bromid (TTAB) a cetyltrimethylammonium bromid (CTAB). Metoda izotermické titrační kalorimetrie byla využita pro stanovení entalpie micelizace, tenziometrie popisuje povrchové vlastnosti daných vzorků. Byl sledován také vliv různé molekulové hmotnosti použitého hyaluronanu a délka alkylového řetězce tenzidu na agregační chování daného systému. Výsledkem jsou hodnoty kritické micelární nebo agregační koncentrace tenzidu. V neposlední řadě se diskutuje využití agregátů hyaluronan-tenzid jako možné nosiče pro cílenou distribuci léčiv.

Diploma thesis studies the effect of temperature (75 and 105 °C) and the effect of 3 kinds of liquids (silicone and hydraulic oil and coolant) at room temperature and at 105 °C on change of the structure of 3 species butadiene-acrylonitrile (NBR) seals (o-ring and two types of bolts). The seals are inspected by the thermogravimetric analysis, differential scanning calorimetry and infrared spectroscopy, the influence of 105 °C on the o-rings is also evaluated in terms of changes in tensile properties. The greatest changes in the composition and structure are observed on o-rings particularly due to temperature of 105 °C, there was a significant reduction in dilatability and an increase in stiffness and glass transition temperature. The root cause is the surface and centre additive decomposition and oxidation. The bolts have suffered from decomposition of the protective surface layer and the additives in the centre, structural change was minor. Exposure to 75 °C has resulted in a gradual loss of low molecular weight substances. Liquids at room temperature didn‘t affect the structure of the seals, at 105 °C it caused a loss of weight due to decomposition of the protective surface layer and release of additives and the products of their decomposition. Results showed that the common use of the NBR seals at 105 °C is unsuitable, at 75 °C it leads to gradual changes, loss in mechanical and sealing properties.

Introduction: Indirect calorimetry (IC) is a very accurate and non-invasive method which is used in clinical practice to measure the resting metabolic rate. This method is based on the assumption that oxygen consumption, carbon dioxide production and nitrogen metabolite waste are in definite relation to energy consumption. Based on the measurement of resting metabolic rate, a nutritional therapist can individually determine daily energy intake of a respective individual, the optimal amount of specific nutrients and thus prevents excessive or inadequate intake of energy and nutrients. Objective: The main aim of this thesis is to compare for group of overweight patients the results of the measurement of the resting metabolic rate (RMR), values of the resting metabolic rate calculated according to the Harris-Benedict (HB) equation and the actual energy intake calculated from the diet report obtained from the patients. In addition, the body composition of the examined group with a focus on the amount of muscle tissue is also marginally evaluated. Methods: The research sample includes in total 50 persons-36 women and 14 men. These persons are patients of the General Faculty Hospital in Prague. The average age is 46 years for women and 51 years for men. The average BMI for women is 38,2 kg/m2 and for men...

Huntington's disease is a dominantly-inherited autosomal neurodegenerative disease manifested by disorders of motility, cognitive function, behaviour, and weight loss, which is conditioned multifactorially. The aim of the study was to determine whether there are eating disorders in Huntington's disease, as well as its etiology and severity. Neurological scaling, anthropometric examinations, evaluation of three-day diet records, measurements with a manual dynamometer, bioimpedance analyses, indirect colorimetry and predictions of energy expenditure were performed on 10 patients. Algorithms were applied for the diagnosis of sarcopenia and malnutrition. Unwanted weight loss was observed in all patients and 4 out of 10 showed malnutrition. No difference was found between the values of measured resting metabolism and calculated according to the predictive equation. However, it has been shown that strict nutritional recommendations based on this data can be misleading for some patients with HN, as real energy consumption can be significantly higher. All our patients had a positive energy balance. A new diagnostic algorithm for the early diagnosis of sarcopenia has proven its worth. Using bioimpedance analysis and examination of the force of the handshake, we identified possible sarcopenia and already-present...

Aims: The aim of this work was to determine whether a increased resting energy expenditure contributes to the nutritional risk for patients with pancreatic cancer. What the variability of resting energy expenditure is and whether it predicts weight loss. Another aim was to verify that lower protein-energy intake also has an impact on weight loss. Methods: Data for the diploma thesis were obtained from the project "Pancreatic Cancer: Metabolic Derangements Associated With Insulin Resistance", which takes place at the Department of Clinical Physiology of Metabolism at 2nd Department of internal medicine in the University Hospital Královské Vinohrady. The project includes 40 - 50 patients with pancreatic tumor resection per year. Data were collected from the beginning of December 2019 until the end of April 2020. The project is funded by the grant AZV NV19-01-00101. 10 consecutive patients (4 women and 6 men) with pancreatic cancer who had a complete dataset for analysis were selected for the research set for the diploma thesis. The patients underwent anthropometric examination, blood tests were taken, and indirect calorimetry was performed. Results: The first part of the research was focused on anthropometric parameters, parameters of nutritional status and the presence of cancer cachexia. The second...

<p>Superabsorbent polymer (SAP) hydrogel particles have been used as internal curing agents in concrete mixes as they are capable of absorbing and subsequently releasing large amounts of water. This reduces autogenous shrinkage during early stages of hydration. The size, shape, and composition of the hydrogel particles can be controlled during the synthesis, hence providing the opportunity to custom synthesize these internal curing agents to elicit desired structure-property relationships. Utilization of optimized dosage and formulation of SAP has the potential to improve the microstructure, durability, and strength of internally cured concrete. </p> <p>The first study focuses on the synthesis and application of novel composite hydrogel particles as internal curing agents in cementitious mixes. Composite polyacrylamide hydrogel particles containing two different amorphous silica–either nanosilica or silica fume–were used to investigate whether the internal curing performance of hydrogel particles could be enhanced. The dosage and type of silica, crosslinker amount were varied to identify the composite polyacrylamide hydrogel particle composition that provides optimum benefits to internally cured cementitious systems. The synthesized hydrogels were characterized by means of absorption capacity tests, compositional and size analysis. The beneficial impacts of the addition of composite hydrogels on cement paste microstructure are highlighted, including the preferential formation of cement hydration products (such as portlandite) within the hydrogel-induced voids that appeared to be influenced by the composition of the hydrogel particles. The interrelationship between extent of hydration, size of hydrogel voids, and void-filling with hydration products was found to strongly influence mechanical strength and is thus an important structure-property relationship to consider when selecting hydrogels for internal curing purposes. This study informs the design of composite hydrogel particles to optimize performance in cementitious mixes. Additionally, it provides a novel means of incorporating other commonly used admixtures in concrete without facing common challenges related to dispersion and health hazards.</p> <p>The second study focuses on the utilization of two retarding admixture-citric acid and sucrose-to custom synthesize composite polyacrylamides to investigate whether the composite hydrogels could delay hydration of cement paste. Isothermal calorimetry analysis results showed that composite sucrose-containing polyacrylamide hydrogel particles were successfully able to retard main hydration peak of cement paste, beyond the retardation capabilities of the pure polyacrylamide hydrogels. Thus, this study provides avenues of exploring the utilization of common admixtures to formulate novel composite hydrogels that imparts specific properties to cementitious systems.</p> <p>In another study, SAP formulated by admixture industries were used to investigate the feasibility of internal curing of bridge decks and pavement patches with SAP particles. The microstructure and early age hydration properties of SAP-cured cementitious systems were studied. Mitigation of microcracks in the matrix, along with portlandite growth in SAP voids, were observed in SAP-cured mortars. Presence of SAP also mitigated autogenous shrinkage and improved early age hydration as observed by isothermal calorimetry analysis. This thesis highlights some of the beneficial impacts of SAP-cured cementitious systems, and the potential to harness those benefits in large-scale applications of SAP-cured concrete.</p> <br>

Neurons depend upon neurotransmitter release through regulated exocytosis to accomplish the immense processing performed within the central nervous system. The SNARE hypothesis points to a family of proteins that are thought to enable the membrane fusion that leads to exocytosis. The secondary structure of SNAP-25 is unique among SNARE proteins in that it has two alpha helical SNARE motifs and a cysteine rich (C85, C88, C90, C92) membrane interacting region but notransmembrane domain. The cysteines may be modified by palmitoylation or oxidation but the role of these modifications in vivo is not well understood. Our goal is to elucidate possible regulatory roles of SNAP-25 that relate to its unique structure and these reversible modifications. However, the study of SNAP-25 in reconstituted systems is hampered by a lack of readily available palmitoylated SNAP-25. A method for in vitro palmitoylation of SNAP-25 by HIP14, a neuronal acyltransferase, is described along with the application of a biotinylation streptavidin assay to verify palmitoylation. Palmitoylation increases the extent to which SNAP-25 interacts with lipids as observed with an environment sensitive trpytophan fluorescence assay. Palmitoylation also alters the phase transition of DPPC lipids differently than unpalmitoylated SNAP-25.This effect on the membrane may influence fusion events. Oxidation of the cysteine residues may be responsible for the sensitivity of SNAP-25 to reactive oxygen species. Our data suggests that, when oxidized, SNAP-25 does not interact with membranes to the same extent as palmitoylated SNAP-25. This may provide a mechanism for reducing exocytosis during oxidative stress. Also, oxidized SNAP-25 is not susceptible to Botulinum Neurotoxin E. The effects of oxidation and palmitoylation on the protein interactions of SNAP-25 may shed light on its role in the SNARE complex and membrane fusion.

Shape memory alloys when deformed can produce strains as high as 8%. Heating results in a phase transformation and associated recovery of all the accumulated strain, a phenomenon known as shape memory. This strain recovery can occur against large forces, resulting in their use as actuators. The goal of this project is to lower the operating temperature range of shape memory alloys in order for them to be used in cryogenic switches, seals, valves, fluid-line repair and self-healing gaskets for space related technologies. The Ni-Ti-Fe alloy system, previously used in Grumman F-14 aircrafts and activated at 120 K, is further developed through arc-melting a range of compositions and subsequent thermo-mechanical processing. A controlled atmosphere arc-melting facility and vertical vacuum quench furnace facility was commissioned to fabricate these alloys. The facility can create a vacuum of 10-7 Torr and heat treat samples up to 977 °C. High purity powders of Ni, Ti and Fe in varying ratios were mixed and arc-melted into small buttons weighing 0.010 kg to 0.025 kg. The alloys were subjected to solutionizing and aging treatments. A combination of rolling, electro-discharge machining and low-speed cutting techniques were used to produce strips. Successful rolling experiments highlighted the workability of these alloys. The shape memory effect was successfully demonstrated at liquid nitrogen temperatures through a constrained recovery experiment that generated stresses of over 40 MPa. Differential scanning calorimetry (DSC) and a dilatometry setup was used to characterize the fabricated materials and determine relationships between composition, thermo-mechanical processing parameters and transformation temperatures.

Изучено влияние природы растворителя и магнитного порошка на процесс кристаллизации поливинилиденфторида (ПВДФ). Методам изотермической микрокалориметрии определены энтальпии разбавления ПВДФ в растворителях различной химической природы. Полученные данные использованы для расчета параметров Флори-Хаггинса. Получены полимерные композиционные материалы на основе ПВДФ и порошков никеля и железа. Получены зависимости степени кристалличности композиций и максимумов температур плавления от состава. Изучен их фазовый состав методами инфракрасной спектроскопии и дифференциальной сканирующей калориметрии. / The influence of the nature of the solvent and magnetic powder on the crystallization process of polyvinylidenefluoride (PVDF) has been studied. The enthalpies of dilution of PVDF in solvents of various chemical nature are determined by the methods of isothermal microcalorimetry. Data used to calculate Flory-Huggins parameters. Polymer composite materials based on PVDF and powders of nickel and iron are obtained. The dependences of the degree of crystallinity of the compositions and maxima of the melting points on the composition were obtained. The phase composition was studied using infrared spectroscopy and differential scanning calorimetry.

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