Diploma thesis main goal is to obtain new pieces of knowledge about relationship between hydrogel structures and its flow and transport properties. Thesis is mainly focusing on combining pertinent biopolymers into model hydrogels based on agarose. Then perform correlation of results obtained by diffusion methods, and by rheologic measurements on macroscopic and microscopic level. Properties of hydrogels were measured by selected rheologic measurements, dynamic light scattering method, and correlative fluorescence spectroscopy. From these methods various parameters (MSD modules, values of complex viscosity) were obtained. Afterwards transport properties of prepared hydrogels were studied by observing Rhodamine 6G diffusion. Here two different approaches were used. From macroscopic perspective, simple principles of mass diffusion from dye solution to cuvettes filled with hydrogels containing individual biopolymers were used. From microscopic perspective, dye was added during the sample preparation and then the mass diffusion was investigated using FCS. Based on evaluated results it was discovered that added biopolymers don’t influence properties of carrier medium, in this case agarose hydrogels. During the study of prepared hydrogels’ reactivity and barrier properties some differences were observed. Charge of biopolymer and its charge density were discovered as main factors influencing transport of charged solutes into prepared hydrogels.

The diploma thesis deals with the influence of technological parameters on the emulsion copolymerization of methyl methacrylate with n butyl acrylate. The theoretical part contains knowledge in the field of influences of proces tempereture, concentration of initiator, concentration of emulsifier, stirring rate and dose rate on emulsion polymerization. In the experimental part was observed effect of the concentration of the ionic emulsifier, nonionic emulsifier, furthemore was observed effect of stirring speed and the concentration of initiator K2S2O8 on conversion of copolymerization. During all copolymerizations, conversions was determinated via solids content evaluation. By dynamic light scattering was determinated and presented polymer particle size of the prepared emulsions. Stability of emuldions was observed via effect of different ionic strenght and yield of freeze thaw cycles coalescence. Based on experimental results were proposed conditions of polyacrylic lattex preparation.

In the present thesis we study light-light scattering, which is a nonlinear effect occurring in quantum electrodynamics. The goal of this thesis is to study the low-energy effective theory (Lagrangians of Euler-Heisenberg type). The first part of the work is devoted to the derivation of the effective Lagrangian in spinor, scalar and vector QED using the amplitude matching of one-loop diagrams. The calculation for the case of vector QED is performed using the unitary gauge, which probably has not been done yet so far by other authors. In the second part, the effective Lagrangian for spinor QED is derived using functional methods. The essential point of the derivation is to calculate the determinant of the Dirac operator in constant background electromagnetic field. Powered by TCPDF (www.tcpdf.org)

One hundred years after the discovery of antimicrobials and antibiotics, intracellular bacterial pathogens remain a major cause of global morbidity and mortality. This is due to the complex and intricate ability of these pathogens to undergo intracellular replication while evading host cell immune defense. Bacterial agents such as Legionella pneumophila, Francisella tularensis, and Mycobacterium tuberculosis, as the causative agents of Legionnaires' disease, pulmonary tularemia, and tuberculosis (TB), respectively, contribute to this burden. Moreover, these agents are weaponizable pathogens due to their aerosolizability. TB represents a global health problem, although a potentially curative therapy has been available for approximately 50 years; this intracellular disease affects approximately 1 in 3 people worldwide, with over 10 million new cases per year and one death every three minutes. TB can usually be treated with a 6- to 9-month course of combined therapy. The necessity of using a cocktail of anti-TB drugs and the long-term treatment schedules required for conventional therapy, however, result in poor patient compliance; therefore, the risk of treatment failure and relapses is higher. Hence, improved drug delivery strategies for the existing drugs can be exploited to shorten the duration of TB...

This thesis deals with the post-polymerization functionalization of a pH-responsive poly(styrene)-b-poly(4-vinyl pyridine)-b-poly(ethylene oxide) triblock terpolymer with stimuli responsive and diol-binding 2-bromomethyl-4-fluorophenylboronic acid and 2- bromomethyl-phenylboronic acid suitable for biomedical applications. A reproducible method of quaternization of poly(4-vinyl pyridine) block with prescriptible quaternization ratio was developed and the reaction yield was analyzed by 11 B, 1 H NMR and infrared spectroscopy. A reproducible self-assembly protocol for stable nanoparticles from functionalized stimuli-responsive triblock terpolymer was found, and the nanoparticles were studied by static, dynamic and electrophoretic light scattering, and cryogenic transmission electron microscopy. Fluorescence and UV-VIS spectroscopy measurements were performed for description of boron-ester linkages formation and hydrolysis with model drug Alizarin as a study of encapsulation and release reactions together with sugar sensing reactions for potential drug delivery.

Catanoinic systems spontaneously form micelles and vesicles, which are self-assembled spherical structures made up by surfactants. In the core of the micelle a drug, or other organic substance, can be kept to stabilize it when placed in an aqueous environment. The micelle-to-vesicle transition corresponds to the moment when the drug is releases, and understanding which factors that trigger this transition is thus of great interest for the pharmaceutical industry. In this study the micelle-to-vesicle transition in water and the effect of salt were studied for the systems 95 mol% SDS/DDAB and 95 mol% SDeS/DDAB with different total concentrations. The static light scattering measurements showed that the micelle-to-vesicle transition for the system 95 mol% SDS/DDAB was shifted to lower total concentrations both when 50 mM NaBr and 100 mM NaBr were added, and that the transition was unaffected by changing the anionic surfactant from SDS to SDeS when no salt had been added. A phase separation was observed when 50 mM NaBr was added to 95 mol% SDeS/DDAB (the Krafft point was probably reached), and when 100 mM NaBr was added to the same system the sample remained opaque one week after mixing the sample and also after heating it to 40°C in a water bath. The curve for sample 95 mol% SDS/DDAB 1/8192 mM + 100 mM NaBr was oscillating implying possible defects in the vesicle membrane. The cryo-TEM images confirmed the light scattering results and additionally showed that at higher total concentrations agglomeration occurred, while whenever salt was added less vesicles seemed to appear, while both discs and broken vesicles were present suggesting that the disc structure is preferred over the spherical structure when salt is present. Also a vesicle inside another vesicle was discovered for the sample 0.95 SDS/DDAB 3.75 mM + 50 mM NaBr. The mole fraction of anionic surfactant in the aggregates (x) was calculated using a MATLAB code based on the Poisson-Boltzmann theory. The results from the calculations showed that a higher amount of SOS was needed for the system 0.95 SOS/CTAB than the amount of SDS and SDeS needed for the systems 0.95 SDS/DDAB and 0.95 SDeS/DDAB when forming aggregates, indicating that a shorter chain of the anion and the higher spontaneous curvature of the cation leads to a higher curvature. Also a larger amount of cation was needed when the tail was single than when it was double in order to form stable spherical structures. Finally, as the total concentration decreased the x value also decreased in all cases, thus the spontaneous curvature was decreased.

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When scattering intensity is plotted against the dimensionless quantity qR, where q is the magnitude of the scattering wave vector and R is the radius of the particle, in log-log scale the scattering curve shows a power-law structure which defines characteristic crossovers. This work reveals some new relationships between the power-law structure and the particle properties. In this work, computer simulation results from T-matrix, Mie theory, and discrete dipole approximation methods are used to study the far field intensity and the internal field of the particles. Scattering by both weakly and strongly refractive particles are studied. For weakly refractive randomly oriented spheroidal particles, how the phasor cancellation-based tip volume method can be applied to predict the scattering envelope is demonstrated. The relationship between backscattering enhancement and the curvature of the weakly refractive particles is explained. In strongly-refractive particles when the phase shift parameter is high, regions with higher field amplitudes start to appear. These regions are recognized as the hot spot regions. In this work, a proper definition is given to the hot spot region. The relationships between the hot spot region and the power-law structure, between the hot spot region and the particle morphology, and between the power-law structure and the particle morphology are extensively studied for scattering by spherical particles. A new semi-quantitative phasor analysis method is introduced, and the new method is used with color-coded phasor plots to identify how different regions of the particle contribute to the scattering pattern to get an insight into the physics behind the scattering. How different regions of the particle contribute to the second crossover (SC) and the backscattering enhancement is presented. Relationships between the SC, particle size, and relative refractive index of the particle are derived. It was identified that the scattering angle at the SC depends only on the relative refractive index of the particle. How the findings of this work can be applied to solve the inverse electromagnetic scattering problem for a single non-absorbing spherical particle is also discussed.

In the production of biodiesel via the transesterification of vegetable oils, purification to international standards is challenging. A key measure of biodiesel quality is the level of free glycerol in the biodiesel. In order to remove glycerol from fatty acid methyl ester (FAME or biodiesel), a membrane separation setup was tested. The main objective of this thesis was to develop a membrane process for the separation of free glycerol dispersed in FAME after completion of the transesterification reaction and to investigate the effect of different factors on glycerol removal. These factors included membrane pore size, pressure, temperature, and methanol, soap and water content. First, a study of the effect of different materials present in the transesterification reaction, such as water, soap, and methanol, on the final free glycerol separation was performed using a modified polyacrylonitrile (PAN) membrane, with 100 kD (ultrafiltration) molecular weight cut off for all runs at 25°C. Results showed low concentrations of water had a considerable effect in removing glycerol from the FAME. The mechanism of separation of free glycerol from FAME was due to the removal of an ultrafine dispersed glycerol-rich phase present in the untreated (or raw) FAME. The size of the droplets and the free glycerol separation both increased with increasing water content of the FAME. Next, three types of polymeric membranes in the ultrafiltration range with different molecular weight cut off, were tested at three fixed operating pressures and three operating temperatures (0, 5 and 25oC) to remove the free glycerol from a biodiesel reactor effluent. The ASTM standard for free glycerol concentration was met for the experiments performed at 25°C. The results of this study indicate that glycerol could be separated from raw FAME to meet ASTM and EN standards at methanol feed concentrations of up to 3 mass%. The process was demonstrated to rely on the formation of a dynamic polar layer on the membrane surface. Ceramic membranes of different pore sizes (0.05 µm (ultrafiltration (UF) range) and 0.2 µm (microfiltration (MF) range)) were used to treat raw FAME directly using the membrane separation set up at temperatures of 0, 5 and 25°C. The results were encouraging for the 0.05 µm pore size membrane at the highest temperature (25°C). The effect of temperature on glycerol removal was evident from its relation with the concentration factor (CF). Higher temperatures promoted the achievement of the appropriate CF value sooner for faster separation. Membrane pore size was also found to affect separation performance. A subsequent study revealed the effect of different variables on the size of the glycerol droplets using dynamic light scattering (DLS). A key parameter in the use of membrane separation technology is the size of the glycerol droplets and the influence of other components such as water, methanol and soaps on that droplet size. The effect of water, methanol, soap and glycerol on the size of suspended glycerol droplets in FAME was studied using a 3-level Box-Behnken experimental design technique. Standard statistical analysis techniques revealed the significant effect of water and glycerol on increasing droplet size while methanol and soap served to reduce the droplet size. Finally, a study on the effect of trans-membrane pressure (TMP) at different water concentrations in the FAME phase on glycerol removal using UF (0.03 µm pore size, polyethersulfone (PES)) and MF (0.1 and 0.22 µm pore sizes, PES) membranes at 25, 40 and 60°C was performed. Results showed that running at 25°C for the two membrane types produced the best results for glycerol removal and exceeded the ASTM and EN standards. An enhancement of glycerol removal was found by adding small amounts of water up to the maximum solubility limit in biodiesel. An increase in temperature resulted in an increase in the solubility of water in the FAME and less effective glycerol removal. Application of cake filtration theory and a gel layer model showed that the gel layer on the membrane surface is not compressible and the specific cake resistance and gel layer concentration decrease with increasing temperature. An approximate value for the limiting (steady-state) flux was reported and it was found that the highest fluxes were obtained at the lowest initial water concentrations at fixed temperatures. In conclusion, dispersed glycerol can be successfully removed from raw FAME (untreated FAME) using a membrane separation system to meet the ASTM biodiesel fuel standards. The addition of water close to the solubility limit to the FAME mixture enables the formation of larger glycerol droplets and makes the separation of these droplets straightforward.

No description available.