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Interactions between Hyaluronan and Surface Active Substances
Krouská, Jitka ; Burgert,, Ladislav (referee) ; Lehocký,, Marián (referee) ; Vikegard,, Peter (referee) ; Pekař, Miloslav (advisor)
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.
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Insulation and dielectric properties of water
Grill, Jiří ; Frk, Martin (referee) ; Špinka, Jiří (advisor)
This master´s thesis deals about insulation and dielectric properties of water. It describes the structure of water, covalent and hydrogen bonds. It outlines primary chemical and physical properties of water and then it describes parameters of water - dynamic viscosity, conductivity, surface tension, pH and also describes dielectric properties - dielectric loss, loss factor, permittivity, polarization. Part of the work is practical section, which includes measurements of deionized water, destilled water, tap water and shows primary dependence such as dependence loss factor on frequency or relative permittivity on frequency.
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Deposition and characterization of SA layers from vinyltriethoxysilane
Veverka, Miroslav ; Veselý, Michal (referee) ; Čech, Vladimír (advisor)
Development of composite material is very much progressive sector and leads to evolution of material with new property. This type of material has one, but important deficiency. It is small adhesion armature to matrix. My study is sight on improvement adhesion the surface by deposition self assembled (SA) monolayer from organosilanes. Property of this layer, like thickness, surface tension, homogenity and wettability, was evaluated by the contact angle measurement and spektroscopical elipsometri.
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Study of surface tension of systems applied in ultrasonography.
Říkovská, Klára ; Pekař, Miloslav (referee) ; Mravec, Filip (advisor)
Surface tension of sonography systems was investigated using several experiments. These experiments were comprised of measurements of surface tension using BPA-800P tensiometer. The influence of surface tension of commercial substance SonoVue®, which contains in its structure two types of phospholipids, was studied more detailed. Other phospholipids were studied to comparison with SonoVue®. All substances were dissolved in saline (0,15 M NaCl). Effect of gas type on microbubbles formation and surface tension was investigated. Some samples were studied using du Nüy ring method. It was found that gas constructing the microbubbles (air or SF6) has no impact to the surface tension value. Production of foam on the surface of solutions has an impact on the value of the surface tension. This foam degreases the surface tension. Gas pressure is significant to comparison of measured data.
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Investment casting waxes and measurements of their properties with regard to simulation software
Bochníček, Štěpán ; Mikulka, Vít (referee) ; Kosour, Vojtěch (advisor)
Today, the use of simulations is increasing in order to reduce cost and complexity of production and also to prevent product defects. For this purpose, we use simulation programs, such as ProCAST. This program is designed for simulation of casting parts. In my bachelor thesis I focused on the methods of casting lost wax, where the model is made of wax mixture. In each simulation we have to obtain and specify the properties of the material to casting. I described these properties and methods of measurement in this bachelor thesis.
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Dynamic surface tension in study of hyaluronan-surfactant interactions
Herzog, Milan ; Žídek, Jan (referee) ; Pekař, Miloslav (advisor)
The main task was to characterize interactions between negatively charged biopolymer sodium hyaluronate and two cationic surfactants: cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB). Interactions between sodium hyaluronate and these surfactants are based on their different charge and can be detected by changes of surface tension. The influence of constant addition of sodium hyaluronate (MW = 90 and 1400 kDa) on interface tension values at increasing bubble lifetime was observed. For this purpose, the maximum bubble pressure method was choosen. The measurements were performed in water and in 0,15 mol•l-1 NaCl solution. The obtained results can be used as for description of dynamic properties of hyaluronate-surfactant systems as, e.g., in targeting drug delivery.
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Improvements of the experimental apparatus for measurement of the surface tension of supercooled liquids using horizontal capillary tube
Vinš, Václav ; Hošek, Jan ; Hykl, Jiří ; Hrubý, Jan
An experimental apparatus with a horizontal capillary tube for measurement of the surface tension of supercooled liquids was designed and tested in the previous study [V. Vinš et al., EPJ Web Conf. 92, 02108 (2015)]. In this work, recent modifications of both the experimental setup and the measurement analysis are described. The main aim is to improve the accuracy and the reproducibility of measured surface tension and to achieve higher degrees of supercooling. Among other modifications, the optical setup observing the liquid meniscus at the open end of the horizontal capillary tube together with the video analysis were thoroughly revised. The modified apparatus was used for the measurement of surface tension of supercooled water at temperatures down to – 11 °C. The new data have a lower scatter compared to the previous horizontal measurements and show a good agreement with the other data obtained with a different measurement technique based on the modified capillary rise method.
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Molecular Simulations of the Vapor–Liquid Phase Interfaces of Pure Water Modeled with the SPC/E and the TIP4P/2005 Molecular Models
Vinš, Václav ; Celný, David ; Planková, Barbora ; Němec, Tomáš ; Duška, Michal ; Hrubý, Jan
In our previous study [Planková et al., EPJWeb. Conf. 92, 02071 (2015)], several molecular simulations of vapor-liquid phase interfaces for pure water were performed using the DL POLY Classic software. The TIP4P/2005 molecular model was successfully used for the modeling of the density profile and the thickness of phase interfaces together with the temperature dependence of the surface tension. In the current study, the extended simple point charge (SPC/E) model for water together with TIP4P/2005 were employed for the investigation of vapor-liquid phase interfaces over a wide temperature range from 250 K to 600 K. Results of the new simulations are in a good agreement with most of the literature data. TIP4P/2005 provides better results for the saturated liquid density with its maximum close to 275 K, while SPC/E predicts slightly better saturated vapor density. Both models give qualitatively correct representation for the surface tension of water.
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Prediction of surface tension of binary mixtures with the parachor method
Němec, Tomáš
The parachor method for the estimation of the surface tension of binary mixtures is modified by considering temperature-dependent values of the parachor parameters. The temperature dependence is calcu- lated by a least-squares fit of pure-solvent surface tension data to the binary parachor equation utilizing the Peng-Robinson equation of state for the calculation of equilibrium densities. A very good agreement between experimental binary surface tension data and the predictions of the modified parachor method are found for the case of the mixtures of carbon dioxide and butane, benzene, and cyclohexane, respectively. The surface tension is also predicted for three refrigerant mixtures, i.e. propane, isobutane, and chlorodifluoromethane, with carbon dioxide.
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An apparatus with a horizontal capillary tube intended for measurement of the surface tension of supercooled liquids
Vinš, Václav ; Hošek, Jan ; Hykl, Jiří ; Hrubý, Jan
New experimental apparatus for measurement of the surface tension of liquids under the metastable supercooled state has been designed and assembled in the study. The measuring technique is similar to the method employed by P.T. Hacker [NACA TN 2510, 1951]. A short liquid thread of the liquid sample was located in a horizontal capillary tube partly placed in a temperature-controlled chamber. One end of the capillary tube was connected to a setup with inert gas which allowed for precise tuning of the gas overpressure. The open end of the capillary tube was precisely grinded and polished in order to assure its planarity and perpendicularity. The liquid meniscus at the open end was illuminated by a laser beam and observed by a digital camera. Application of an increasing overpressure of the inert gas at the inner meniscus of the liquid thread caused variation of the outer meniscus such that it gradually changed from concave to flat and subsequently convex shape. The surface tension at the temperature of the inner meniscus could be evaluated from the overpressure corresponding to exactly planar outer meniscus.
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