abstract: As experiencing hot months and thermal stresses is becoming more common, chemically protective fabrics must adapt and provide protections while reducing the heat stress to the body. These concerns affect first responders, warfighters, and workers regularly surrounded by hazardous chemical agents. While adapting traditional garments with cooling devices provides one route to mitigate this issue, these cooling methods add bulk, are time limited, and may not be applicable in locations without logistical support. Here I take inspiration from nature to guide the development of smart fabrics that have high breathability, but self-seal on exposure to target chemical(s), providing a better balance between cooling and protection. Natural barrier materials were explored as a guide, focusing specifically on prickly pear cacti. These cacti have a natural waxy barrier that provides protection from dehydration and physically changes shape to modify surface wettability and water vapor transport. The results of this study provided a basis for a shape changing polymer to be used to respond directly to hazardous chemicals, swelling to contain the agent. To create a stimuli responsive material, a novel superabsorbent polymer was synthesized, based on acrylamide chemistry. The polymer was tested for swelling properties in a wide range of organic liquids and found to highly swell in moderately polar organic liquids. To help predict swelling in untested liquids, the swelling of multiple test liquids were compared with their thermodynamic properties to observe trends. As the smart fabric needs to remain breathable to allow evaporative cooling, while retaining functionality when soaked with sweat, absorption of water, as well as that of an absorbing liquid in the presence of water were tested. Micron sized particles of the developed polymer were deposited on a plastic mesh with pore size and open area similar to common clothing fabric to establish the proof of concept of using a breathable barrier to provide chemical protection. The polymer coated mesh showed minimal additional resistance to water vapor transport, relative to the mesh alone, but blocked more than 99% of a xylene aerosol from penetrating the barrier. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2020

京都大学 / 0048 / 新制・論文博士 / 博士(理学) / 乙第13300号 / 論理博第1563号 / 新制||理||1653(附属図書館) / (主査)准教授 王 功輝, 教授 釜井 俊孝, 教授 福田 洋一 / 学位規則第4条第2項該当 / Doctor of Science / Kyoto University / DGAM

<div>Starch pasting behavior greatly influences the texture of a variety of food products such as canned soup, sauces, baby foods, batter mixes etc. The annual consumption of starch in the U.S. is 3 million metric tons. It is important to characterize the relationship between the structure, composition and architecture of the starch granules with its pasting behavior in order to arrive at a rational methodology to design modified starch of desirable digestion rate and texture. </div><div> In this research, polymer solution theory was applied to predict the evolution of average granule size of starch at different heating temperatures in terms of its molecular weight, second virial coefficient extent of cross-link and electrostatic interaction within a granule. Evolution of granule size distribution of normal maize starch (NMS) and NMS crosslinked to different extents with sodium trimetaphosphate, waxy rice starch, normal rice starch and normal potato starch when subjected to heating at a rate of 15 C/min to 65, 70, 75, 80, 85 and 90 C was characterized using static laser light scattering. As expected, granule swelling was more pronounced at higher temperatures and resulted in a shift of granule size distribution to larger sizes. Most of the swelling occurred within the first 10 min of heating except for potato starch. Novation 1600 (Modified Potato Starch) is also found to shift to larger sizes at longer holding times and higher temperatures, but this shift is found to be gradual and for penpure 80, even at 60 C, the size distribution shifts to smaller sizes at longer holding times indicating breakup of the granule. </div><div> The structure of normal maize starch was characterized by cryo scanning electron microscopy. The number of crosslinks in the starch network was inferred from equilibrium swelling. This is related to peak viscosity and zeta potential of granule for NMS and its crosslinked starches. Chemical potential profile as well as the temperature profile within the granule at different times were predicted which were then employed to evaluate the granule size at different times. The proposed model is able to describe the swelling behavior of different varieties of starch and also the effect of crosslinking. </div><div> The viscoelasticity for different starch types, heating rates, and heating temperatures were characterized. A methodology to predict the storage modulus of starch paste due to granule swelling, given the physical properties of the starch granule is presented. In high-volume fraction regime, classical model for foam rheology enabled calculation of limiting storage modulus for different starches. By scaling the storage modulus with limiting storage modulus, the storage modulus of a wide range of starches forms a master curve. This master curve when employed along with the swelling model resulted in the successful prediction of development of texture for different types of starches. </div><div> In low-volume fraction regime (below 65%), Stokesian dynamics simulations are used to predict the viscoelasticity of polystyrene micro particles and fractionated starch suspension and compared with experiments. Predicted values of storage modulus from stokesian dynamics simulation at 4 HZ for different volume fractions of monodispersed polystyrene spheres of two different sizes namely 25 and 116 micrometer compared well with experimental values. Stokesian dynamics also describes the storage modulus of fractionated starch granules for volume fractions between 0.4 - 0.5</div><div> The average granule size of starch in presence of sucrose was initially increasing and then decreasing with maximum swelling at 5% and 10% sucrose concentration for NMS and WRS. The average granules size continuously increases for WMS and decreases for NRS with increase in sucrose concentration. The Gelatinization Temperature increases with increase in sucrose concentration for all starches. Enthalpy of Gelatinization increases with increase in sucrose concentration for Normal starches where as there is no effect of sucrose concentration for waxy starches. Flory Huggins starch-sucrose interaction parameter was characterized which is used to predict the equilibrium swelling power using a mathematical model proposed to quantitatively describe the equilibrium swelling in the presence of solute (sucrose) based on Flory Huggins polymer solution theory to develop rational guidelines for identification of sugar substitute with desirable functional properties. The model predictions of equilibrium swelling power agrees with experimental results.</div>

This Master‘s thesis is focused on the preparation of hydrogels based on a hydrophobic derivative of hyaluronic acid palmitoyl hyaluronan in presence of biosurfactant decyl glucoside’s micelles and micelles of surfactant triton X-100. For followed characterization were chosen rheological tests and infrared spectrometry. There was observed influence of preparation method, type and concentration of surfactant and presence of micelles on final features of the hydrogel. Moreover, an experimental test of swelling was performed with interesting results for future research.

The effects of elevated pressure and high heating rates on coal pyrolysis and gasification were investigated. A high-pressure flat-flame burner (HPFFB) was designed and built to conduct these studies. The HPFFB was designed to provide an environment with laminar, dispersed entrained flow, with particle heating rates of ~10^5 K/s, pressures of up to 15 atm, and gas temperatures of up to 2000 K. Residence times were varied from 30 to 700 ms in this study. Pyrolysis experiments were conducted at particle heating rates of ~10^5 K/s and maximum gas temperatures of ~1700 K at pressures of 1 to 15 atm. A new coal swelling correlation was developed that predicts the effects of heating rate, pressure, and coal rank on the swelling ratio at heating rates above ~10^4 K/s. A coal swelling rank index system based on 13C-NMR chemical structural parameters was devised. The empirical swelling model requires user inputs of the coal ultimate and proximate analyses and the use of a transient particle energy balance to predict the maximum particle heating rate. The swelling model was used to explain differences in previously reported bituminous coal swelling ratios that were measured in facilities with different heating rates. Char gasification studies by CO2 were conducted on a subbituminous coal and 4 bituminous coals in the HPFFB. Pressures of 5, 10, and 15 atmospheres were used with gas compositions of 20, 40, and 90 mole % CO2. Gas conditions with peak temperatures of 1700 K to 2000 K were used, which resulted in char particle temperatures of 1000 K to 1800 K. Three gasification models were developed to fit and analyze the gasification data. A simple 1st-order model was used to show that the measured gasification rates were far below the film-diffusion limit. The other two models, designated CCK and CCKN, were based on three versions of the CBK models. CCKN used an nth-order kinetic mechanism and CCK used a semi-global Langmuir-Hinshelwood kinetic mechanism. The two CCK models fit the HPFFB gasification data better than the 1st-order model. The fits of the gasification data with CCK and CCKN were comparable to each other. The fit of the data in CCK suggests that Knudsen diffusion may have influenced the gasification rates in the HPFFB experiments. The gasification rate parameters in each of the three models were correlated with coal rank. 13C-NMR parameters were used to estimate a structural parameter of the coal char. Char-CO2 gasification rate coefficients correlated better with this NMR-based char structure index than it did with the carbon and oxygen content of the parent coal.

The thesis is focused on physical hyaluronan gels. The object of study is the interaction of hyaluronan (HyA) with oppositely charged surfactants in physiologic solution (0.15 M NaCl), leading to the formation of gel. In the first part of work have been determined the solids´ contents (X) in gels and their supernatants in percentage and their correlation with molecular weight concentration of original HyA solution and the ratio of binding sites on hyaluronan chain and surfactant CTAB. To conclude, decrease in HyA concentration results in higher values of X and vice versa. On the other hand, increase in the value of X with increasing molecular weight of HyA is not so significant. Analogous conclusions have been made for supernatants and the amount of solids in gel. Drying process has been recorded by drying curves. Swelling process has been used for the characterization of gels. The percentage of water that can be absorbed by dried gel, was determined. The results are in agreement with the measurements of solids´ content in gels. In the next part, the correlation between rheological properties of gels and HyA concentration, HyA molecular weight and concentration of CTAB have been studied by the oscillation and flow tests. The samples with the highest molecular weight and concentration have the most viscoelastic character. The flow test confirmed the assumed pseudoplastic behavior of gels. A very interesting trend arose while comparing HyA concentrations and viscosity in stock solutions and gels. Whereas in stock solution viscosity (at low shear rate) is lower with increasing of HyA concentration, the situation was exactly the opposite in gels. The results are in agreement with frequency tests and observed character of gels.

This master thesis deals with characterization of two black and white products based on ethylene-propylene-diene rubber (EPDM) used for skating rink. Products marked with A and are different in their diameter of circular tubes trough which cooling medium passes and also in the distance of these tubes. Both of materials were characterized in order to determine whether it is the EPDM and how are they different. The characterization methods were used: differential scanning calorimetry, thermogravimetric analysis, attenuated total reflectance Fourier transform infrared spectroscopy, tensile test, swelling test, thermooxidative test. The composition of both materials, including fillers and others additives is almost the same but difference is in structure of EPDM and probably also in interaction with fillers, what exhibits different mechanical properties, thermooxidative stability and thermal capacity. These differences which have been found are essential for long-term use properties of both materials.

This diploma thesis deals with preparation and subsequent characterization of albumin (BSA) and mixed hyaluronan-albumin (HA+BSA) hydrogels. The experimental characterization was based on the rheological measurements of the influence of ionic strength, pH and molar mass of HA on the gelation process and the properties of formed gels, as well as the time stability of these properties. Following object of the study was swelling of hydrogels in water and buffers with different pH value. Characterization was extended by thermal analysis, morphology description using scanning electron microscopy (SEM) and study of transport properties of hydrogels for selected model substance. Due to increasing ionic strength, the gel point was shifted towards higher temperature values and the resulting gels exhibited higher values of complex moduli. In case when pH was lower than isoelectric point of BSA, attractive electrostatic interactions between albumin and hyaluronan took place and the faster gelation occurred, compared to the case when pH was higher than isoelectric point of BSA. On the contrary, values of complex moduli increased with increasing pH. The gel samples prepared in the presence of low molecular weight HA reached higher values of complex moduli, compared to samples with the high molecular weight HA. Rheological properties of BSA gels were stable over time, whereas the mixed HA+BSA were characterized by significant decrease of complex moduli during the first three days of storage. Due to heating up to 100 °C, more than 80 % of the weight of studied samples was lost, as a result of water evaporation. Further heating of hydrogels, up to 250 °C, did not cause other changes associated with weight loss, in contrast with crystalline powder BSA, in which another weight loss at 220 °C was observed, as a result of the beginning degradation. Swelling studies, as well as SEM images, indicated higher crosslink density of BSA gels, compared to HA+BSA samples, which exhibited higher values of swelling ratio. The lowest values of equilibrium swelling ratio were observed at pH 4, which is close to the isoelectric point of albumin. Calculated diffusion coefficients relative to diffusivity of methylene blue in water ranged between the order of 10E-2 for diffusion into physiological solution and the order of 10E-3 for the diffusion into water. Ongoing transport of model dye from gel to solution was significantly slower, compared to its diffusion in water, as a result of gel porosity and electrostatic immobilization of positively charged molecules of methylene blue on the negatively charged BSA and HA chains.

Für die visuelle Wahrnehmung im Gehirn spielt die ungestörte Funktion von Neuronen und Gliazellen in der Netzhaut eine entscheidende Rolle. Viele schädigende Prozesse wie Entzündungen, Ischämien oder Traumata können zur Ödementstehung in der Netzhaut führen. Da die Netzhaut entwicklungsgeschichtlich einen vorverlagerten Teil des Zwischenhirns darstellt, lassen sich die pathophysiologischen Zusammenhänge, die zur Entstehung eines Netzhautödems führen, auch auf die Ödementstehung im Gehirn übertragen. Diese Arbeit beschäftigt sich mit dem Phänomen der Zellvolumenregulation von Müllerzellen – den hauptsächlich in der Netzhaut anzutreffenden Gliazellen – und leistet damit einen Beitrag zur Grundlagenerforschung der Ödementstehung in neuronalen Geweben. Die im Rahmen von Ödementstehungen regelmäßig zu beobachtenden Gefäßpermeabilitätserhöhungen führen in neuronalen Geweben auch zur Extravasation von Albumin. Unter diesem Gesichtspunkt untersucht die vorliegende Arbeit den Einfluss von bovinem Serumalbumin auf die Müllerzellen und die damit verbundenen Mechanismen am Modell der Netzhaut von Ratten.

Diese Arbeit befasst sich mit der Lichttransmission im retinalen Gewebe. Aufgrund der inversen Konfiguration der Wirbeltiernetzhaut muss das ins Auge eintretende Licht zahlreiche Zellschichten durchdringen, bevor es von den Photorezeptoren detektiert wird. Die Autorin geht davon aus, dass die morphologische Heterogenität dieser Zellschichten mit einer optischen Heterogenität einhergeht, welche den Lichttransport zu den Photorezeptoren beeinflusst. In den Versuchsbeschreibungen wird erläutert, wie das native Netzhautgewebe von Meerschweinen verschiedenen osmotischen Stimuli ausgesetzt wurde, um morphologische Veränderungen zu provozieren. Durch die parallele Beobachtung der Durchmesser ausgewählter Zellen der äußeren und inneren Netzhaut, sowie der quantitativen Lichtdurchlässigkeit des Gewebes, konnte die Autorin die morphologischen Veränderungen zur retinalen Lichtdurchlässigkeit in Beziehung setzen. Die Ergebnisse zeigen, dass Zellschwellungen zu einer Erhöhung der quantitativen Lichtdurchlässigkeit und Zellschrumpfungen zu einer Verringerung dieser führen. Es werden folgende Schlüsse gezogen: Die osmotischen Stimuli bewirken Volumenregulationsprozesse, infolge derer sich lokale Brechungsindizes und Extinktionskoeffizienten ändern und die retinale Lichtdurchlässigkeit beeinflussen. Zudem konnte die Autorin durch Versuche mit nativen Primatennetzhäuten nachweisen, dass die Abbildungsqualität im Zentrum der Fovea centralis am besten ist, weil die inneren Netzhautschichten dort nicht vorhanden sind und das Licht direkt auf die Photorezeptoren trifft. Diese Arbeit zeigt, dass die Wirbeltiernetzhaut ein optisch aktives Medium ist, dessen Morphologie die Lichttransmission durch das Gewebe beeinflusst.