Master of Science / Department of Grain Science and Industry / Yong Cheng Shi / Resistant starch (RS) is notable for having several health benefits in humans, including glucose control and intestinal well-being. Pullulanase is able to debranch amylopectin and result in higher RS content. Different levels of pullulanase have been used to debranch waxy maize starch in the literature, but the changes of structure during debranching are well documented. In this study, waxy maize starch was cooked and debranched by pullulanase with 80, 160 and 240 New Pullulanase Unit Novo (NPUN)/g starch pullulanase. One NPUN was defined as the amount of enzyme, which, under standard conditions, hydrolyzes pullulan, liberating reducing carbohydrate with reducing power equivalent to 1 µmole glucose per minute. The structure of waxy maize starch during debranching was investigated and the digestibility of the debranched products was measured. When pullulanase was increased from 80 to 240 NPUN/g, more amylopectin was debranched in the same debranching time, and the degree of crystallinity and the RS content increased. After the debranched starches were crystallized at 25°C for 24 hours, the RS contents were greater than 63%. When heated and recrystallized under highly regulated conditions, the linear material formed crystallites of a range of geometries, including spherulites of a highly organized structure. Debranched waxy maize starches were used to produce crystalline structure under four conditions: spherulites formed by adding ethanol and crystallized at 4°C (ES4); spherulites formed in water (WS4) at 4°C; particles formed at 50°C (WS50); and spherulites formed at 50°C then further precipitated at 4°C (WS50-4). Spherulites formed at 50°C (WS50) had a higher proportion of smaller molecules than existed in the parent starch (Rh<15nm). ES4 and WS4 were B-type crystalline structure; whereasWS50 and WS50-4 were A-type crystalline structure. ES4 had a larger proportion of molecules with a low degree of polymerization and the RS content was also the lowest of the four samples. With cooling from 50°C to 4°C (WS50-4), the RS content was increased from 60% to 73%. ES4 and WS50-4 contained particles with spherical symmetry and WS4 had partial radial symmetry with some distortions, whereas WS50 displayed oblate particles with a parallel crystal structure.

All far-field optical imaging is limited by diffraction from optical elements, a phenomenon called Rayleigh's curse. It has been shown that through the use of the spatial mode demultiplexing technique (SPADE), an arbitrarily small separation between two point sources can be resolved, given a sufficiently large total number of photons N. This quantum metrology approach to super-resolution has since then been demonstrated and generalized to more complex situations. We propose a variant of SPADE, that we call biphoton SPADE, applied to imaging systems with spatially entangled photon pairs generated through spontaneous parametric downconversion. Our method can achieve a higher precision than SPADE, given any non-zero level of entanglement. We furthermore demonstrate our technique in a coincidence imaging setup and show super-resolution while only projecting on a select few of the total optimal modes in the 2D joint basis. Since the method uses quantum light and provides even further sensitivity to SPADE, it can potentially be used in the future for various light-sensitive imaging applications and in combination with neural networks. In nature, one often finds structures that have only been replicated by humans through years of precise, state-of-the-art engineering. Polymer spherulites, naturally occurring birefringent crystals that grow around defects in a radial pattern, are an example of this. We show through the example of ascorbic acid, commonly referred to as Vitamin C, that spherulites are capable of creating beams with orbital angular momentum (OAM) through a process called spin-to-orbit coupling. This action of the ascorbic acid crystals is analogous to the one of spatially structured waveplates called q-plates, which are built to have an azimuthally dependant optic axis. This opens the door for potentially cheaper fabrication of q-plates, and possibilities of tuning the growth of the molecules for arbitrary wavefront shaping with natural crystals. Finally, because of the wide range of crystals in the spherulite class, further investigation into different spherulites could shed light on the relationship between crystal symmetry and structure, and the shaping of light.

No description available.

No description available.

Ascent of magma results in drastic drops of pressure and temperature during eruption. Exsolution or dissolution of water changes the physical and chemical properties of the magma and can promote or inhibit the formation of bubbles, crystals and cracks. The microstructural relations between bubbles, crystals and cracks are important records of processes immediately before and during volcanic eruptions and during deposition of volcanic products. This is an integrated study of analyses, conceptual and numerical models of textural relations, and water distribution patterns of natural and experimentally altered samples. Synchrotron Fourier transform infrared spectroscopy and focal plane array detectors open new possibilities for the analysis of the spatial distribution of volatiles in volcanic rocks. New ways of sample preparation, measurements and data analyses helped to create water distribution maps with spatial resolutions that are close to the diffraction limit (~3 μm). In order to constrain eruptive processes and mechanisms of lava emplacement, I describe textural features in volcanic glasses including bubbles, flow bands of crystals or bubbles, spherulites and different generations of cracks. In experiments, bubbles were grown under isobaric conditions, at one or two cooling steps, their textures were described and volume changes tracked. Water distribution patterns in the glass around the textures were described and categorized, and where possible, diffusion modeling was used to infer temperature- and timescales of formation. Rocks that are quenched within short periods of time after bubble growth preserve negative gradients of water toward the bubble margins. These gradients are generally not observed if the sample is kept at high temperatures for extended periods. If, however, a second step of cooling is added, water may be re-dissolved into the surrounding melt, which may lead to the complete resorption of bubbles. A conceptual of water redistribution during bubble resorption or collapse is used to interpret water heterogeneities across linear flow banding. These heterogeneities can be caused by shearing of bubbly magma, leading to collapse, degassing and resorption of water into the melt, creating a bubble free melt. Anhydrous spherulitic crystals grow both above and below the glass transition temperature (Tg) redistributiong water into the surrounding melt. Below Tg, cracks form and are successively hydrated by magmatic water from crystal growth or by meteoric water at temperatures far below Tg. The hydrated perlitic cracks in the samples of this study formed at elevated temperatures and are distinct from cracks formed at ambient temperatures without hydrated margins. This study shows that the heterogeneous distribution of water in volcanic rocks preserves the complex and non-linear degassing and cooling history of eruptive products. The timescales and temperatures discovered here provide new ways to interpret textural observations, water distribution patterns and signals of shallow volcanic unrest.

<p>Crystal structure, morphology and crystallization kinetics of melt-crystallized polypropylene and poly(propylene-stat-ethylene) fractions with 2.7 to 11.0 mol% of ethylene were studied by differential scanning calorimeter, wide- and small-angle X-ray scattering, polarized light microscopy, transmission electron microscopy and infrared spectroscopy. With increasing ethylene content the poly(propylene-stat-ethylene) fractions showed unchanged crystallinity, increased unit cell volume and constant crystal thickness in combination with a shortened helix length. This indicated that a fraction of ethylene defects were incorporated into the crystal structure. During the isothermal crystallization both α- and γ-crystals could be formed. The γ-crystal fraction increased with increasing ethylene content and increasing crystallization temperature. For samples with α- and γ-crystal contents, multimodal melting was observed and a noticeable γ- to α-crystal conversion was observed on slow heating. The spherulitic structure of the copolymers was coarser than that for the homopolymer.</p><p>The crystalline lamellae in copolymers exhibited profound curvature in contrast to the straighter cross-hatched α-crystals typical to the homopolymer. Area dependence of electrical breakdown strength was studied for thin polypropylene homopolymer films. The measurements were performed with an automatic measurement system equipped with a scanning electrode arm. Five different electrodes having areas between 0.045 cm2 and 9.3 cm2 were used and typically 40-80 breakdowns per sample and electrode area were collected. All measurements were performed on dry samples in air at room temperature. The data was analyzed statistically and the Weibull function parameters α and β, the first one related to 63% probability for the sample to break down and the second one to the width of the distribution were fitted to the obtained data. Different features concerning the measurement system and conditions, e.g. criteria for the automatic detection of the breakdowns, effect of electrode edge design, partial discharges, DC ramp speed and humidity were critically analyzed. It was concluded that the obtained α-parameter values were stable and repeatable over several years of time. The β-parameter values, however, varied ± 10-30%, more for the large than the small electrodes, and were also sensitive to the changes both in the sample itself and in the measurement conditions.</p><p>Breakdown strengths of over 50 capacitor grade polypropylene films were analyzed. The obtained α-parameter values were between 450 and 850 V/μm, depending on the film grade and electrode area. In addition to the high breakdown strengths, reflected by the obtained α-values, another, sparse distribution consisting of low breakdown strengths was revealed when the amount of measurement points was high enough. This means that more than one Weibull distribution could be needed to describe the breakdown strength behavior of a polypropylene film. Breakdown values showed decreasing area dependence with decreasing electrode area. Breakdown strengths for larger sample areas were predicted from the small area data by area- and Weibull extrapolation. The area extrapolation led to predicted α-values 50% higher than measured at 4 m² whereas the Weibull extrapolation showed an accuracy of ±15 % when predicted and measured values were compared.</p><p>Breakdown strengths were also extrapolated for film areas similar to those in impregnated power capacitors. It turned out that the power capacitors, tested at the factory, performed much better than predicted by the extrapolation. However, a few weak spots with very low breakdown values were also found. For the poly(ethyelene terephtalate) dielectric, which is not swelled by the impregnation liquid, the large area breakdown strength was predictable. This indicates that for polypropylene film processing and impregnation led, in addition to the improved large area breakdown performance, also to sparse weak spots with low breakdown probabilities. Different Weibull distributions were responsible for the breakdown strengths for the processed and impregnated polypropylene than for the dry film samples.</p>

Cette thèse concerne l’auto-assemblage d'alcanes semi-fluorés (FnHm) et de fluorocarbures (FCs) aux interfaces et leurs interactions avec des phospholipides (PLs) en 2D et 3D. Nous avons étudié les sphérulites formées dans des films de diblocs FnHm. La morphologie de ces sphérulites, concentrique ou radiale, est contrôlée par la longueur des blocs Fn et Hm et la vitesse de refroidissement. Les nanodomaines de diblocs FnHm dans les monocouches de Langmuir sont incompressibles et forment des gels physiques 2D, même à pression nulle. Les blocs Hm sont cristallisés et inclinés d’ ~30°C par rapport à la normale à la surface. La réflectivité de neutrons a montré que l’albumine adsorbée sur des monocouches de PL est désorbée par un FC gazeux. Ce résultat pourrait permettre de lutter contre l’inactivation du surfactant pulmonaire par les protéines sériques. L’ajout de diblocs à des films de PLs accroit l'élasticité des monocouches. Nous avons préparé des microbulles stables à parois de PLs/FnHm, les diblocs agissant en co-surfactants. / This thesis focuses on the self-assembly of semi-fluorinated alkanes (FnHm) and fluorocarbons (FCs) at interfaces and their interactions with phospholipids (PLs) in 2D and 3D. 2D Spherulites were identified in FnHm films for the first time. Their morphology, ring-banded or radial, was controlled by varying block lengths and cooling rate. Nanodomains of FnHm in monolayers formed incompressible 2D physical gels, even at zero surface pressure. The Hm segments are crystalline and titled by 30°C to the normal to the surface. Neutron reflectivity showed that albumin adsorbed on PLs monolayers is desorbed by exposure to FC gas, which opens the potential use of FCs to treat the inactivation of the lung surfactant by serum proteins. Incorporating FnHm into PL monolayers increases their elasticity. Small, stable microbubbles of PLs/FnHm were obtained. FnHm diblocks function as co-surfactants for stabilizing microbubbles.

The diffusion of small-molecule penetrants in polyethylene is hindered by impenetrable crystals and by the segmental constraints imposed by the crystals on the penetrable phase. Liquid and vapour n-hexane sorption/desorption measurements were performed on metallocene catalyzed homogenous poly(ethylene-co-octene)s. It was shown that the fractional free volume of the polymer penetrable component increased with increasing amount of penetrable polymer. It also increased with the relative proportion of liquid-like component in the penetrable polymer fraction. The detour effect was found to increase with decreasing crystallinity. The experimental study of the morphology of the polymers showed that the geometrical impedance factor followed the same trend with increasing crystallinity as the data obtained from n-hexane desorption. The changes in phase composition and character upon n-hexane sorption were monitored with Raman spectroscopy, WAXS and NMR spectroscopy. Partial dissolution of the orthorhombic and the interfacial component was observed upon nhexane sorption. Changes in the character of the components were furthermore analyzed: an increase of the density in the crystalline component and a decrease of the density in the amorphous component were observed in the n-hexane-sorbed-samples. Molecular dynamics simulations were used for studying diffusion of n-hexane in fully amorphous poly(ethylene-co-octene)s. The branches in poly(ethylene-co-octene) decreased the density by affecting the packing of the chains in the rubbery state in accordance with experimental data. Diffusion of n-hexane at low penetrant concentration showed unexpectedly that the penetrant diffusivity decreased with increasing degree of branching. Spherulitic growth was mimicked with an algorithm able to generate structures comparable to those observed in polyethylene. The diffusion in the simulated structure was assessed with Monte Carlo simulations of random walks and the geometrical impedance factor of the spherulitic structures was calculated and compared with analytical values according to Fricke’s theory. The linear relationship between geometrical impedance factor and crystallinity in Fricke’s theory was confirmed. Fricke’s theory, however, underestimated the crystal blocking effect. By modelling systems having a distribution of crystal width-to-thickness ratio it was proven that wide crystals had a more pronounced effect on the geometrical impedance factor than is indicated by their number fraction weight. / QC 20100909

Crystal structure, morphology and crystallization kinetics of melt-crystallized polypropylene and poly(propylene-stat-ethylene) fractions with 2.7 to 11.0 mol% of ethylene were studied by differential scanning calorimeter, wide- and small-angle X-ray scattering, polarized light microscopy, transmission electron microscopy and infrared spectroscopy. With increasing ethylene content the poly(propylene-stat-ethylene) fractions showed unchanged crystallinity, increased unit cell volume and constant crystal thickness in combination with a shortened helix length. This indicated that a fraction of ethylene defects were incorporated into the crystal structure. During the isothermal crystallization both α- and γ-crystals could be formed. The γ-crystal fraction increased with increasing ethylene content and increasing crystallization temperature. For samples with α- and γ-crystal contents, multimodal melting was observed and a noticeable γ- to α-crystal conversion was observed on slow heating. The spherulitic structure of the copolymers was coarser than that for the homopolymer. The crystalline lamellae in copolymers exhibited profound curvature in contrast to the straighter cross-hatched α-crystals typical to the homopolymer. Area dependence of electrical breakdown strength was studied for thin polypropylene homopolymer films. The measurements were performed with an automatic measurement system equipped with a scanning electrode arm. Five different electrodes having areas between 0.045 cm2 and 9.3 cm2 were used and typically 40-80 breakdowns per sample and electrode area were collected. All measurements were performed on dry samples in air at room temperature. The data was analyzed statistically and the Weibull function parameters α and β, the first one related to 63% probability for the sample to break down and the second one to the width of the distribution were fitted to the obtained data. Different features concerning the measurement system and conditions, e.g. criteria for the automatic detection of the breakdowns, effect of electrode edge design, partial discharges, DC ramp speed and humidity were critically analyzed. It was concluded that the obtained α-parameter values were stable and repeatable over several years of time. The β-parameter values, however, varied ± 10-30%, more for the large than the small electrodes, and were also sensitive to the changes both in the sample itself and in the measurement conditions. Breakdown strengths of over 50 capacitor grade polypropylene films were analyzed. The obtained α-parameter values were between 450 and 850 V/μm, depending on the film grade and electrode area. In addition to the high breakdown strengths, reflected by the obtained α-values, another, sparse distribution consisting of low breakdown strengths was revealed when the amount of measurement points was high enough. This means that more than one Weibull distribution could be needed to describe the breakdown strength behavior of a polypropylene film. Breakdown values showed decreasing area dependence with decreasing electrode area. Breakdown strengths for larger sample areas were predicted from the small area data by area- and Weibull extrapolation. The area extrapolation led to predicted α-values 50% higher than measured at 4 m2 whereas the Weibull extrapolation showed an accuracy of ±15 % when predicted and measured values were compared. Breakdown strengths were also extrapolated for film areas similar to those in impregnated power capacitors. It turned out that the power capacitors, tested at the factory, performed much better than predicted by the extrapolation. However, a few weak spots with very low breakdown values were also found. For the poly(ethyelene terephtalate) dielectric, which is not swelled by the impregnation liquid, the large area breakdown strength was predictable. This indicates that for polypropylene film processing and impregnation led, in addition to the improved large area breakdown performance, also to sparse weak spots with low breakdown probabilities. Different Weibull distributions were responsible for the breakdown strengths for the processed and impregnated polypropylene than for the dry film samples. / QC 20101027

Baggalútar are well-rounded spheroids that typically measures 16-18 mm in size and have a brownreddish appearance. They can be found in the Hvalfjörður bay in SW Iceland. There are manydescriptions in literature and on the internet that Baggalútar are volcanic spherulites formed by quartzor cristobalite spheres growing out of a common centre and there is also a broadly accepted consensusof this theory. However, despite this consensus that Baggalútar are volcanic spherulites there exist nodetailed investigation of their origin. The aim of the thesis is to investigate what Baggalútar is exactlyand how they form. This is achieved by using a combination of petrographic observations with apolarization microscope, mineral chemistry from electron microprobe analysis and measurements oftheir magnetic properties. The results are compared with different geological and anthropological spheroids, spherulites,nodules and concretions. The petrographic observations show that they predominantly consist of finegrained basaltic tephra (groundmass) together with zeolites infilling voids. Analyses of mineralchemistry indicate that the groundmass consists of augitic pyroxene, plagioclase, and two differentoxides where one classifies as titanomagnetite. The magnetic measurements support this by showing aCurie temperature at approximately 460-470 °C which is likely to be titano-magnetite. Although thedifferent geological and anthropological processes that typically results spheroidal shapes have somesimilarities that could explain the formation of baggalútar, most of these can be excluded for differentreasons. The internal textures of baggalútar strongly indicate that the shape is controlled by externalfactors, like weathering or erosion from beach outcrops. This could explain the spherical shape of asingle baggalút, but it fails to explain the spheroidal shapes of individual baggalútar joined together inclusters. / Baggalútar är väl rundade sfäroider som vanligtvis mäter 16–18 mm i storlek och har ett brunt rödaktigtutseende. De hittas i Hvalfjörðurbukten i SW Island. Det finns många beskrivningar i litteraturen ochpå internet som säger att Baggalútar är vulkaniska sfäruliter som bildas av kvarts- eller kristobalitsfärersom växer fram ur ett gemensamt centrum och det finns också en allmänt accepterad konsensus omdenna teori. Men trots denna konsensus om att Baggalútar är vulkaniska sfäruliter finns det ingendetaljerad undersökning av deras ursprung. Syftet med avhandlingen är att undersöka exakt vadBaggalútar är och hur de bildas. Detta uppnås genom att använda en kombination av petrografiskaobservationer med ett polarisationsmikroskop, mineralkemi från elektronmikrosondanalys ochmätningar av deras magnetiska egenskaper. Resultaten jämförs med olika geologiska och antropologiska sfäroider, sfäruliter, noduler ochkonkretioner. De petrografiska observationerna visar att de till övervägande del består av finkornigbasaltisk tefra (grundmassa) tillsammans med zeoliter som fyller ut tomrum. Analyser av mineralkemivisar att grundmassan består av augitisk pyroxen, plagioklas och två olika oxider där den enaklassificeras som titanomagnetit. De magnetiska mätningarna stödjer detta genom att visa en Curietemperatur på cirka 460–470 °C som sannolikt är titanomagnetit. Även om de olika geologiska ochantropologiska processerna som vanligtvis resulterar i sfäroida former har vissa likheter som kanförklara bildandet av baggalútar, kan de flesta av dessa uteslutas av olika anledningar. Baggalútars inretexturer indikerar starkt att formen styrs av yttre faktorer, som väderpåverkan eller erosion frånstrandhällar. Detta kan förklara den sfäriska formen av en enda baggalút, men det misslyckas med attförklara de sfäriska formerna av individuella baggalútar i sammanfogade kluster.