CHARLES UNIVERSITY IN PRAGUE Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical technology Name and surname: Marie Korpasová Title of diploma thesis: Adhesive and rheological properties of mixtures based on chitosan Supervisor: PharmDr. Eva Šnejdrová, Ph.D. Diploma thesis deals with evaluation of rheological and adhesive properties of compounds for matrix tablets formulation, based on Chitosan with addition of retardant compound. The retardant compound consists of Sodium Alginate and Hypromellose in concentrations of 30 %, 40 % and 50 %. Theoretical part describes Chitosan, Sodium Alginate and Hypromellose. As next is division of matrix tablets. Theoretically is also described evaluation of rotational, oscillational and adhesive testing which was used in practical part. From viscosity curves can be seen, that viscosity is decreasing with increasing stress. Viscosity increases with increasing concentration of Sodium Alginate and Hypromellose. Oscillational testing is better for gel characterization, because it provides lower stress on test samples. Samples of given compound were prepared by hydrating with phosphate buffer of pH 6,8. Coefficient of consistency K and index flow rate n characterize rheological behaviour of gels. Viscoelastic compounds behave like solids with plastic...

<div>Pressure-gain combustion in wave rotors offer the opportunity for substantial improvement in gas turbine efficiency and power, while controlling emissions with fuel flexibility, if provided rapid and reliable ignition of lean mixtures. In addition, tightening emission regulations and increasing availability of gas fuels for internal-combustion engines require more reliable ignition for ultra-lean operation to avoid high peak combustion temperature. Turbulent jet ignition (TJI) is able to address the ignition challenges of lean premixed combustion. Especially, the turbulent hot jet results in faster ignition penetration for wave rotor pressure-gain combustors that have high-frequency operation and fast-burn requirements. Controllability of TJI needs better understanding of the chemistry and fluid mechanics in the jet mixing region, particularly the estimation of ignition delay time and identifying the location of the ignition onset. </div><div>In the present work, numerical and analytical methods are employed to develop models capable of estimating the ignition characteristics that the turbulent hot jet exhibits as it is issued to a cold stoichiometric CH4-H2-Air mixture with varied fuel reactivity blends. Numerical models of the starting turbulent jet are developed by Reynolds-averaged and large-eddy simulation of Navier-Stokes and scalar transport equations in a high-resolution computational domain, with major focus on ignition of high-reactivity fuel blends in the jet near-field due to computational resource limitations. The chemical reactions are modeled using detailed chemistry by well-stirred and partially stirred reactor approaches. Numerical models describe the temporal evolution of jet mixture fraction, scalar dissipation rate, flow strain rate, and thermochemical quantities of the flow.</div><div>For faster estimation of ignition characteristics, analytical methods are developed to explicitly solve governing equations for the transient evolution of the near field and the leading vortex of the starting hot jet. First, the transient radial evolution of the turbulent shear-layer of a round transient jet is analytically investigated in the near-field of the nozzle, where the momentum potential core exists. The methods approximate the mixing and chemical processes in the jet shear and mixing layer. The momentum equation is integrated analytically, with a mixing-length turbulence model to represent the variation of effective viscosity due to the velocity gradients. The analytic predictions of the velocity field and mass entrainment rate of the jet are compared with numerical predictions and experimental findings. In addition, the transport equation of conserved scalars in the jet near-field is solved analytically for the history of the jet mixture fraction. This analytic solution for temperature and species is used, together with available models for instantaneous chemical induction time, to create an analytic ignition model that provides the time and radial location of the ignition onset.</div><div>Lastly, the ignition mechanism within the vortex ring, which leads the starting turbulent jet, is modeled using prior understanding about the mixing characteristics of the vortex. This mechanism is more relevant to low-reactivity fuel blends. Due to the presence of strong mixing at the large-scale, the vortex ring is treated as a homogeneous batch-reactor, which contains certain levels of the jet mixture fraction. This assumption provides the initial composition and temperature of the reactor in which ignition ensues. </div><div>This article-dissertation is developed as a collection of 4 articles published in peer-reviewed journals, one submitted article, and additional unpublished work. The study is laid out in 6 chapters with the following contributions:</div><div>Chapter 1: This chapter numerically investigates the three-dimensional behavior of a transient hot jet as modeled using the Reynolds-averaged turbulence flow. The study aims at providing an insight towards the role of mixing in the ignition progress and how the operating conditions such as fuel mixture and pre-chamber pressure ratio can influence the ignition success. An ignition prediction criterion is developed in this chapter, which helps to predict the ignition success under a broad range of operating conditions.</div><div>Chapter 2: In this chapter, the large-eddy simulation (LES) of hot jet ignition is reported in conjunction with detailed kinetics mechanism and adaptive-mesh refinement. The correlation between local values of mixture fraction gradient and ignition is discussed. Furthermore, the role of methane-hydrogen ratio on the heat release pattern is studied for two specific mixtures.</div><div>Chapter 3: The LES of CH4-H2-Air ignition is extended in this chapter to account for multivariable evaluation of ignition. Joint probability assessment of ignition explains the role of important scalars on the formation and growth of ignition. Also, the effect of CH4-H2 ratio on the spatial distribution of ignition is assessed and discussed.</div><div>Chapter 4: In this chapter, the rate of mass entrainment into the jet in the near-field region is studied. Characterization of the mass entrainment illuminates the understanding of mixing behavior of the starting turbulent jets. Through an exact solution of the momentum equation, this chapter includes a model of the diffusive transport in a round transient jet at high Reynolds numbers.</div><div>Chapter 5: This chapter proposes a method to evaluate the mass/heat exchange between a transient-turbulent jet and a quiescent environment. To analyze the transport phenomena in the jet near-field, the transient diffusion equation in cylindrical coordinates is explicitly solved and its solution is compared with the empirical findings. The transport solution then enables an ignition model to describe the spatiotemporal characteristics of ignition in the near-field.</div><div>Chapter 6: The development of ignition within the vortex ring of the transient jet is investigated in this chapter. The initiation, growth, and departure of the vortex ring are studied using the available empirical correlations and the LES. Using a perfectly-stirred, zero-dimensional representation of the vortex, chemical kinetic calculations provide estimates of ignition delay for various fuel mixtures.</div><div><br></div>

This degree work is a project that started out from weaving, which became the founding technique for how a modular textile took its shape, woven together as interlaced parts. Modularity was taken into this work in order to avoid a flat result and give the woven textile playful attributes and multiple functions. By using bold colours and layers in weaving, an investigation of the interactive and playful side of this textile technique was done. The method was based on workshops where geometrical forms were systematically woven into a repetitive pattern according to the plain weave binding. The result were three voluminous textiles with a given hierarchy of colours and material as they were placed at different levels. Practically, it is a textile that can be fitted to different spaces by being either diminished or built out, in order to be interactive. The quantity of elements within the textiles became the essence and the quality in the project and the advantage is that it is a textile that can be made from waste.

CHARLES UNIVERSITY Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Name of author: Dominik Vavřich Title of diploma thesis: Rheological behaviour of mixtures for freeze-drying Supervisor: PharmDr. Eva Šnejdrová, Ph.D. The diploma thesis deals with the evaluation of rheological properties of aqueous dispersions of fish gelatin and carrageenans intended for lyophilization. Theoretical part of this work is dedicated to the characterization of fish gelatin and carrageenans which were used for preparation of the mixtures in experimental part of this work. Characterization of an oral cavity from an application of medicaments point of view and an orally disintegrating tablets of the medicine with a focus on the lyophilized tablets are also presented. Mixtures of the fish gelatin and the carrageenans were prepared in the experimental part of the work. Their rheological behaviour employing an absolute rotational rheometer Kinexus Pro+ was measured and evaluated. Also, the testing of the rheological characteristics of these materials transformed into the freeze-dried tablets was performed. Nonlinear viscous curves were obtained, and they were mathematically evaluated by the Power law model. Pseudoplastic behaviour of the mixtures can be derived from the results of acquired...

Increased understanding of the mechanisms that operate in conjunction with the welding of metal surfaces may help to improve existing manufacturing processes, and to enable new products and combinations of materials. The purpose of the project has therefore been to acquire a deeper understanding of what is happening in the bond for steel and for the factors that form the basis for a bond to develop between metals in the production of laminates by pressing. The merge has been done by pressing and the surfaces after the experiments have been studied in detail in the scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and with interferenceprofilometry in Wyko, to provide a greater understanding of the mechanisms that influence the bonding in the interface between metals.   The project was limited to contain the materials Docol 1000, HyTens 1200, Aluminum AA3003 and a commercial steel. The parameters varied in the experiments to study their influence closer are temperature, pressure, heat treatment and pretreatment. This has been implemented by pressing with varying temperature and pressure. The materials have been pressed at room temperature or heated in an oven at 300 or 600 degrees and pressed immediately after the levying. Pretreatment was done by cleaning in acetone followed by either brushing or sandblasting alternatively no pretreatment have been done at all. The result was that the increased pressure and increased temperature increases the chance of joining by pressing. Pressing at slightly elevated temperature (about 100-250 degrees, depending on the material) makes bonding possible for metals which are not joined together at room temperature. Pretreatment by sandblasting gives a rougher and more riddled surface than brushing. At the cracking in the oxide layer at the pressing, wells new clean metal into between the oxides to the surface. When the new material reaches the surface, a joint can be made with the opposite clean material. The clean metal that wells up, then flows in a pattern which presses down the oxide in the material, away from the surface. This is done so more clean material can come to the surface and a finer binding can be obtained.

The project examines how a new structure could be added on top a 60’s school building without interfering with its structurally order and aesthetical manifestation. A new space for the citizens of Tensta, a hovering glass box that puts Tensta Centrum on the map. Together with new office spaces for the City District Administration it would work as a catalytic effect for the area. New spatial qualities emerges and the composition, the old vs the new, together creates Tensta’s new Town Hall. / Projektet undersöker hur en ny struktur kan läggas ovanpå en befintlig skolbyggnad utan att störa dess strukturella ordning och estetiska uttryck. En ny plats för medborgarna i Tensta, en svävande glasbox som sätter Tensta Centrum på kartan. Tillsammans med nya kontorsutrymmen för Stadsdelsförvaltningen skulle det fungera som en katalysator för området. Nya rumsliga kvaliteter framträder och sammansättningen det gamla och det nya, skapar tillsammans Tenstas nya Rådhus.

Restoration has been a tool for enhancing selected parts of history, which tells about the ideals of its time. Today most older buildings have already been through several restorations or renovations. How should one approach and valuate historical layers? The purpose of this thesis has been to study earlier restoration work and its approaches and ideals. From this, interventions and design has been done through an alteration of Börshuset in Gamla Stan in Stockholm. The restoration proposal consists of three interventions done with three different approaches: reconstruction, alteration of the existing and an added function and element. Through this method, the project attempts to answer questions about how we can relate to existing buildings, not just as artefacts of their time, but as living things with a complex and layered history. My proposal is a suggestion to reintroduce lost qualities and value the historical layers that are or have been present in Börshuset. By being aware of the difficulty in appreciating newer layers there is a possibility for a better assessment and decision-making that could save historical layers which might become our future cultural heritage.

We have investigated the impact of strain on the incorporation and the properties of extended and point defects in (Mg,Zn)O thin films by means of photoluminescence, X-ray diffraction, deep-level transient spectroscopy (DLTS), and deep-level optical spectroscopy. The recombination line Y2, previously detected in ZnO thin films grown on an Al-doped ZnO buffer layer and attributed to tensile strain, was exclusively found in (Mg,Zn)O samples being under tensile strain and is absent in relaxed or compressively strained thin films. Furthermore a structural defect E3′ can be detected via DLTS measurements and is only incorporated in tensile strained samples. Finally it is shown that the omnipresent deep-level E3 in ZnO can only be optically recharged in relaxed ZnO samples.

Room temperature magnetoelectric BiFeO3-BaTiO3 superlattices with strong out-of-plane magnetic anisotropy have been prepared by pulsed laser deposition. We show that the out-ofplane magnetization component increases with the increasing number of double layers. Moreover, the magnetoelectric voltage coefficient can be tuned by varying the number of interfaces, reaching a maximum value of 29 V/cmOe for the20×BiFeO3-BaTiO3 superlattice. This enhancement is accompanied by a high degree of perpendicular magnetic anisotropy, making the latter an ideal candidate for the next generation of data storage devices.

I have made an investigation in how I can encourage curiosity in textiles with a specific interest in its structures. I have found that repetition is one efficient way to make a separate building element disappear into its own mass and instead be viewed as a surface. I researched how different surfaces are created by experiment with materials and techniques and looked into the big role tactility plays when curiosity in textiles are created but as well realized that a haptic experience can be reached not only with skin but through the eyes. The experiments and elaborations I made took my ideas beyond my starting point and further than I first could imagine. I explored and questioned hierarchies and values of materials by the way I used and combined them. By doing so I realized and discussed the dilemma of being positive to the idea of letting people experience my work through touching and the issue with sustainability, duration and demolishing the patterns while doing so.  Through this paper I aimed to find a definition for what fiber art can be today. I didn´t find one or totally uniform answer but it seems to me that it´s a movement that stretches over diverse material fields and has an underlying power to push boundaries and traditions and break free from classifications.