Accurate precipitation-type forecasts are essential in many areas of our modern society andtherefore there is a need to develop proper working methods for this purpose. Focus of thiswork has been to study important physical processes decisive in deciding both the temperatureof the precipitation particles, hence affecting their phase, and the surrounding air. Two majorlatent heating effects have been emphasized, melting effect and cooling byevaporation/sublimation. Melting of the snow flakes subtracts heat from the surroundings andhence acts as a cooling agent. Phase transformation from solid/liquid into the gas phase alsoneeds heat which here results in a cooling tendency. These two mechanisms may sometimeshave a crucial influence for deciding the correct precipitation-type. The melting effect isdiscussed in a paper about a snow event in Tennessee in USA, and another paper describingan event in Japan showing the influence of the evaporation/sublimation process. In the lattercase the wet-bulb temperature, Tiw as a physical correct discriminator between snow and rainis obtained. A numerical weather prediction model (HIRLAM) is being used to study differentcondensation schemes during three weather situations occurring in Sweden. These areRasch/Kristjánsson condensation scheme, Sundqvist original condensation scheme and amodification of the latter scheme. In the modified Sundqvist condensation scheme the Tiw hasbeen implemented as a limit temperature between snow and rain. The results are showingdifferences between the two main schemes concerning the total precipitation (both snow andrain). Comparisons between Sundqvist condensation scheme and this modified version, calledSundqvist scheme with Tiw show that this latter version creates slightly more snow.Differences between them are largest in dryer areas. Differences in the snow accumulationincrease when the forecast length increases. That makes them harder to be compared to snowanalyses from MESAN (mesoscale analysis) because the analyses is partly based ondifferences in the snow depth and this cannot be directly compared to amount of newly fallensnow especially when surface air temperatures are above freezing. Deviations from the dataanalyses are obtained in both Sundqvist and Sundqvist scheme with Tiw but in some regionsthe latter is in better agreement with measurements. Further work is needed in precipitationtypestudies but the physical correct value with Tiw = 0 ºC as melting temperature used inSundqvist with Tiw scheme is an interesting project for the future in the field of precipitationtypeforecasting. / Sammanfattning av ”Regn eller snö? En fråga om våta temperaturen” Noggranna prognoser beträffande nederbördstyp är väldigt viktiga inom många områden isamhället. Det finns därför ett behov att utveckla bra metoder att avgöra om nederbördenfaller som regn eller snö. Viktiga fysikaliska processer är avgörande för nederbördens och denomgivande luftens temperatur; processernas kritiska betydelse för dess fas har satts i fokus.De två största latenta värmeeffekterna, avkylning genom smältning och genomavdunstning/sublimation har betonats. Smältning av snöflingorna extraherar värme frånomgivningen och därmed sänks temperaturen. Avdunstning och sublimation erfordrar värmeför fastransformation vilket även här tas från omgivningen och därmed en kylande effekt somföljd. Dessa två latenta värmeeffekter har ibland kritisk betydelse för nederbördstypen vidmarkytan och detta diskuteras dels i en artikel om en vädersituation från Tennessee (Kain etal., 2000) där smälteffekten fick avgörande betydelse för nederbördsfasen vid markytan, dels istudier från Japan där betydelsen av avdunstning och sublimation på nederbördstypenbetonats (Matsuo and Sasyo, 1981). I det senare fallet tydliggörs isobara våta temperaturenoch dess betydelse som diskriminator mellan regn och snö. En numerisk vädermodell (HIRLAM) har använts för att studera olika typer avkondensationsscheman och deras betydelse för nederbörden under tre olika väderskeenden iSverige. Dessa är Rasch/Kristjánssons kondensationsschema, Sundqvistskondensationsschema samt en något ändrad variant av Sundqvists kondensationsschema dären subrutin för beräknandet av Tiw har implementerats och ersatt den vanliga temperaturen iden del av schemat som beräknar smältning av nederbörd i fast form. Smälttemperaturen harsedan satts till 0ºC. Resultatet visar skillnader mellan Rasch/Kristjánssons schema ochSundqvists schema beträffande total 12 timmars nederbörd (regn och snö). Vissa periodertenderar Sundqvists kondensationsschema att överproducera nederbörden medan under andraperioder är det Rasch/Kristjánssons schema, som överproducerar jämfört mednederbördsobservationer. Jämförelser mellan Sundqvists schema och Sundqvists schema medTiw visar att den senare producerar mer ackumulerad snömängd med de största skillnaderna iområden som avviker mest från mättnad (100 %). Där finner vi också större differensermellan den vanliga temperaturen och Tiw. Skillnaden blir större när vi ökar den totala tiden förackumulerad snömängd men dessa värden blir då också svårare att verifiera med snöanalyserfrån MESAN. Detta då snöanalyserna bygger på skillnader mellan aktuell och föregåendeobserverade snödjup. Detta behöver ej alls vara lika med den verkliga mängden nysnö somfallit, speciellt under mätperioder då det är plusgrader. Avvikelser från snöanalyserna kannoteras i både Sundqvists schema och Sundqvists schema med Tiw. I vissa regioner är docksnöprognosen från den senare något bättre. Det fysikaliskt korrekta värdet av Tiw = 0ºC somsmältgräns mellan regn och snö istället för den vanliga temperaturen, utgör grunden förintressanta framtida studier beträffande nederbörd och nederbördstyp.

An attempt is made in the work described in this paper to extend the series started by Hall and Platas by means of a Knoevenagel condensation between 3-hydroxy-1,4-naphtho-quinone-2-(4-methylpyridinium) anhydride and various aromatic aldehydes giving rise to a series of unsaturated substituents on the four position of the pyridine ring.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

São investigadas, utilizando-se a distribuição grande canônica, as modificações introduzidas nas propriedades termodinâmicas e magnéticas de um sistema de bosons confinado por um potencial harmônico cilindricamente e esfericamente simétrico. O sistema apresenta condensação de B.E. somente no limite de confinamento fraco e a causa desta transição é devido a não homogeneidade do sistema, além da dependência da função densidade de estados próximos da energia mínima. Para este limite de confinamento fraco, são analisados ainda os limites de campo magnético forte ou fraco, apresentando comportamentos distintos, podendo ser comparados com o sistema de May ou com o sistema de gás ideal não confinado e com campo magnético nulo (sistema livre). A ordem da transição analisada constatando-se não ser de primeira ordem. O calor específico mostra uma descontinuidade finita na temperatura de transição. Abaixo desta temperatura de transição, o sistema apresenta uma magnetização espontânea, valendo então a lei B-H. / The modifications introduced in the thermodynamic and magnetic properties of a bosons system which is limited by a spherical and cylindrically harmonic potencial are investigated, using the grand canonical distribution. The system presents B.E. condensation only in the weak confinement limit and the cause of this transition is due to the non-homogeneity of the system in addition to the dependence of the density function of states near the minimum energy level. About this weak confinement limit, the limits o£ the strong or weak magnetic field are analysed too. The limit of the strong or weak magnetic field show distinctive behavior and they may be compared with the May\'s system or with the non-confined system of the ideal gas and with the null-magnetic field (free system). The order of this transition is analysed and it is verified as not being of the first order. The specific heat present a finite discontinuity in the transition temperature. Below this transition temperature, the system presents a spontaneous magnetization thus satisfying the B-H law.

Doped electrically conductive polymers are one of the critical materials that have allowed the current technological revolution. Essentially all of today's applications of doped conductive polymers involve vinyl-related polymers. While the application of conductive polymers is rapidly increasing, there is need for additional materials with different electrical behaviors. The current focus is on studying condensation polymers that contain a metal atom and the possibility of undergoing entire chain delocalization of electrons. The different series of organometallic condensation polymers were synthesized by employing interfacial polycondensation technique and characterization of these products were carried out using standard techniques like light scattering photometer, fourier transform infrared spectroscopy (FTIR), matrix assisted laser desorption ionization time of flight mass spectroscopy (MALDI TOF MS) and nuclear magnetic resonance spectroscopy (NMR). The electrical measurements were carried out employing Genrad 1650-B impedance spectroscopy. Prior studies conducted in this area have led to the pathway of looking at two aspects; first, surveying 60 metal-containing polymers that can undergo entire chain delocalization studying the effect of different substituents on their electrical properties and secondly, doping selected candidates employing iodine. The products derived from 2-nitro-1,4-phenylenediamine and N-methyl-1,4- pheneylenediamines with titanocene dichloride exhibited about 10 3 to 10 5 fold magnitude increases in the electrical conductivity on doping with iodine, moving it near conductive region. This increase is dependent on the concentration of the iodine and is cyclic. The results support the starting premise that selected metal-containing condensation polymers can be doped to increase their electrical conductivity. / Further investigation is warranted to see if metal-containing condensation polymers can be important materials in the electronic industry. This research sets the stage for studying not only metal-containing polymeric materials but also to investigate the ability to increase the conductivity of other condensation polymers such as nylons and polyesters through doping. / by Amitabh J. Battin. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

<div>Biomass-derived fuels have long been considered as a possible replacement for traditional liquid fuels derived from petroleum. However, biomass as a feedstock requires significant refinement prior to application as a liquid fuel. The H2Bioil process has previously been proposed in which biomass is pyrolyzed and the resulting vapors are passed over a catalyst bed for upgrading to hydrocarbon products in a hydrogen environment [1]. A PtMo catalyst has been developed for the complete hydrodeoxygenation (HDO) of biomass pyrolysis vapors to hydrocarbons [2]. However, the product hydrocarbons contain a large fraction of molecules smaller than C4 which would not be suitable as liquid fuels. In fast hydropyrolysis of poplar followed by hydrodeoxygenation over a PtMo/MWCNT catalyst at 25 bar H2 and 300oC, only 32.1% of carbon is captured in C4 – C8 products; 21.7% of carbon is captured in C1 – C3 hydrocarbons [2]. Here, approaches are examined to increase selectivity of H2Bioil to desired products. Aldol condensation catalysts could be used prior to the HDO catalyst in order to increase the carbon number of products. These products would then be hydrodeoxygenated to hydrocarbons of greater average carbon number than with an HDO catalyst alone. Application of a 2% Cu/TiO2 catalyst to a classic aldehyde model compound, butanal, shows high selectivity towards aldol condensation products at low H2 pressures. In more complex systems which more closely resemble biomass pyrolysis vapors, this catalyst also shows significant yields to aldol condensation products, but substantial carbon losses presumed to be due to coke formation are observed. Both glycolaldehyde, a significant product of biomass pyrolysis, and cellulose, a component polymer of biomass, have been pyrolyzed and passed through aldol condensation followed by hydrodeoxygenation in a pulsed fixed-bed microreactor. Glycolaldehyde aldol condensation resulted in the formation of products in the C2-C¬9 range, while the major aldol condensation products observed from cellulose were C7 and C8 products. Carbon losses in glycolaldehyde aldol condensation were reduced under operation at increased hydrogen partial pressures, supporting the hypothesis that increasing selectivity to hydrogenation products can reduce coke formation from primary aldol condensation products. </div><div>The use of feeds which have undergone genetic modification and/or pretreatment by other catalytic processes may also lead to improvements in overall product selectivity. The influence of genetic modifications to poplar lignin on the pyrolysis plus HDO process are investigated, and it is found that these materials have no effect on the final product distribution. The product distribution from a poplar sample which has had lignin catalytically removed is also examined, with the conclusion that the product distribution strongly resembles that of cellulose, however the lignin-removed sample shows high selectivity towards char which is not seen from cellulose. </div><div><br></div>

Quasicrystals are long-range ordered and yet non-periodic. This interplay results in a wealth of intriguing physical phenomena, such as the inheritance of topological properties from higher dimensions, self-similarity, and the presence of non-trivial structure on all scales. The concept of aperiodic order has been extensively studied in mathematics and geometry, exemplified by the celebrated Penrose tiling. However, the understanding of physical quasicrystals (the vast majority of them are intermetallic compounds) is still incomplete owing to their complexity, regarding both growth processes and stability. Ultracold atoms in optical lattices offer an ideal, yet untested environment for investigating quasicrystals. Optical lattices, i.e. standing waves of light, allow the defect-free formation of a large variety of potential landscapes, including quasiperiodic geometries. In recent years, optical lattices have become one of the most successful tools in the large-scale quantum simulation of condensed-matter problems. This study presents the first experimental realisation of a two-dimensional quasicrystalline potential for ultracold atoms, based on an eightfold symmetric optical lattice. It is aimed at bringing together the fields of ultracold atoms and quasicrystals - and the more general concept of aperiodic order. The first part of this thesis introduces the theoretical aspects of aperiodic order and quasicrystalline structure. The second part comprises a detailed account of the newly designed apparatus that has been used to produce quantum-degenerate gases in quasicrystalline lattices. The third and final part summarises the matter-wave diffraction experiments that have been performed in various lattice geometries. These include one- and two-dimensional simple cubic lattices, one-dimensional quasiperiodic lattices, as well as two-dimensional quasicrystalline lattices. The striking self-similarity of this quasicrystalline structure has been directly observed, in close analogy to Shechtman's very first discovery of quasicrystals using electron diffraction. In addition, an in-depth study of the diffraction dynamics reveals the fundamental differences between periodic and quasicrystalline lattices, in excellent agreement with ab initio theory. The diffraction dynamics on short timescales constitutes a continuous-time quantum walk on a homogeneous four-dimensional tight-binding lattice. On the one hand, these measurements establish a novel experimental platform for investigating quasicrystals proper. On the other hand, ultracold atoms in quasicrystalline optical lattices are worth studying in their own right: Possible avenues include the observation many-body localisation and Bose glasses, as well as the creation of topologically non-trivial systems in higher dimensions.

Superhydrophobic (SH) surfaces are super water repellent surfaces on which a droplet of water will bead up like a marble and roll off the surface with minimal tilting of the surface. This is caused by the combination of a hydrophobic coating and a rough surface structure. To achieve thermodynamic stability, surface tension of the water pulls the droplet into this shape to minimize the contact area between the droplet and the surface. This creates a high contact angle (CA) between the droplet and the surface and a low sliding angle (SA) of which the droplet begins to roll off the surface. SH surfaces have a variety of potential applications such as drag reduction, anti-icing, improved heat transfer through condensation, and self-cleaning. Numerous reports have been dedicated to exploring the fluid dynamic behavior of water droplets on SH surfaces. This thesis focuses on exploring the self-cleaning properties of SH surfaces. Surfaces contaminated with salt, tobacco, and pollen are cleaned by rolling water droplets over the surface or condensing water on the surface such that when large enough, these droplets roll away due to gravity. SH surfaces explored here are composed of micro-scale or nano-scale rib and cavity structures and are compared with smooth, hydrophobic surfaces with a similar hydrophobic coating. To determine the self-cleaning efficiency of each surface, the CA and SA were measured before and after each surface was cleaned. In this study, it was observed that the presence of each of the three contaminates considered greatly affects the overall hydrophobicity of the surface, as indicated by the CA and SA. Ideally, as the contaminates are removed from the surface, the hydrophobicity of the surface improves to match the hydrophobicity of a clean surface. This is best seen on surfaces contaminated with salt as the CA and SA match that of a clean surface after only two to three water droplets roll over the surface or after the first condensed water droplets roll off the surface. This implies that all the salt particles are removed from the SH surface. Surfaces contaminated with tobacco showed that the hydrophobicity improves to a limited extent when cleaned with rolling water droplets or condensation but never is capable of matching the hydrophobicity of a clean surface. This suggests that only a portion of the tobacco residue is capable of being removed from the surface by either of the two cleaning methods considered in this thesis. Finally, when water came in contact with pollen on the surfaces, it experienced hydrodynamic osmosis leading to cellular bursting. After cellular bursting, the surface behaves as a hydrophilic surface and selfcleaning properties were never observed on any surface contaminated with pollen. Thus, overall this study shows that rolling water droplets over a contaminated surface and condensing water droplets on a contaminated surface are both viable means of utilizing the self-cleaning properties on SH surfaces. For the contaminates considered in this study, the efficiency of the self-cleaning surfaces is shown to be the same for both micro-structured and nano-structured surfaces.

Being the most abundant protein in the body, by mass, type I collagen provides the building blocks for tissues such as bone, extra-cellular matrix, tendons, cornea, etc[1-3]. The ability of a single protein to create structures with such various mechanical properties is not fully understood. Before one can engineer and assemble a complex tissue, such as cornea, the mechanisms underlying the formation and assembly, mechanical properties, and structure must be investigated and quantified. The work presented herein contains an extensive study of Type I collagen from the molecular to the tissue level. The engineering of collagenous tissues that mimic the mechanical and optical properties of native human cornea have been performed by a number of groups[4-7]. In all of these studies, the corneal-mimicking tissues have been created using a number of methods including repeated flow casting. To date, the ability to create self-assembled corneal tissue has not been achieved. Understanding the mechanisms of formation of native cornea will not only bring us closer to achieving self-assembled transplantable corneal tissue but will also aid in the engineering of all collagenous tissues and other structures comprised of filamentous units. Recently, the study of type I collagen has primarily focused on the tissue, fiber, and fibril scale[2, 8-21]. Grant, et al.[20] measured the elastic modulus of collagen fibrils in various solutions and found that by increasing ion concentration, in the solution around the fibril, the elastic modulus increased. The solution dependent behavior of the elastic modulus of collagen fibrils was measured but the cause of the dependence was unknown. Grant et al. state that due to the complex nature of the interactions between collagen fibrils and aqueous solutions, the exact cause of this effect is difficult to determine. Through work presented herein, not only do we show that this behavior is seen at the molecular level but also quantify the relationship between ionic concentration and molecular stiffness for a variety of ionic species. Studies of collagen mechanics, on the molecular level, are brief[22-26]. The most prominent of these studies in recent years was performed by Sun, et al.[27] wherein a persistence length of 14.5nm, for human type I procollagen, was measured. The persistence length of the molecule, which is a measure of flexibility, is a highly debated topic with quoted values of 14.5nm[27], 57nm[28], 130nm[29], 175nm[30], 308nm[31], and 544nm[32]. The broad range of values indicates that the flexibility of the collagen molecule is a complex question. It became apparent that the disagreement of the persistence length of molecular collagen in the literature may be due to the use of different ionic solutions. To address this, an initial atomic force microscope, AFM, study of the persistence length of molecular collagen diluted in DI water and two ionic solutions was conducted. This study showed that there is a strong solution dependence to the flexibility of the molecule. The ionic solutions presented molecules with a large persistence length, a straightened configuration, while the DI water dilution resulted in a persistence length that was a factor of 10 smaller. Because two different complex ionic solutions in the initial study showed different persistence lengths, an evaluation of the effect of each individual salt was performed. To elucidate the effects of individual ionic species on the conformations and persistence length of Type I collagen varying concentration of monovalent and divalent salts with different cations and anions were tested. It was found that increasing ionic concentration for all species types resulted in a higher persistence length but the rate of change in persistence length as a function of concentration is unique to each species. In 2002 Leikina, et at.[33] suggested that Type I molecular collagen is unstable at body temperature using differential scanning calorimetry. To examine these results, an AFM study was performed that imaged the collagen molecules after being held at body temperature for varying times. The density of molecules deposited onto mica, above a 200nm length cutoff, was calculated and it shows that the number of molecules above 200nm in length decreases with increasing incubation time. These environmental studies were performed with an aim to understanding the role of environment in creating a corneal mimicking tissue. Currently, the most promising method of collagen membrane fabrication for corneal replacement was developed by Tanaka, et al.[4]. This unique repeated flow casting method allows for the manufacturing of transparent collagen membranes with controllable thickness and fibrillar alignment. Using the repeated flow casting technique, orthogonally oriented collagen membranes were created and their optical properties were measured using the Generalized High Accuracy Universal Polarimeter, G-HAUP. When engineering a tissue for the eye, the optical properties of the tissue are of the utmost importance. Appropriately for corneal tissues, the measurements for linear birefringence and linear dichroism were negligible. It was clear, from the literature, that a fundamental understanding of molecular type I collagen was not available. In this work, the mechanical properties and environmentally sensitive behavior of bovine dermal type I molecular collagen is studied. The exploration into the unique behavior of these systems begins with documenting the rich ionic species and concentration dependent flexibility of molecular type I collagen and the temperature dependence on the stability of the molecule is tested. The study concludes with the construction of corneal mimicking tissues using the repeated flow casting method and measuring the complex optical properties of these tissues.

Atom chips are devices used to magnetically trap and manipulate ultracold atoms and Bose-Einstein condensates near a surface. In particular, permanent magnetic film atom chips can allow very tight confinement and intricate magnetic field designs while circumventing technical current noise. Research described in this thesis is focused on the development of a magnetic film atom chip, the production of Bose-Einstein condensates near the film surface, the characterisation of the associated magnetic potentials using rf spectroscopy of ultracold atoms and the realisation of a precision sensor based on splitting Bose-Einstein condensates in a double-well potential. The atom chip itself combines the edge of a perpendicularly magnetised GdTbFeCo film with a machined silver wire structure. A mirror magneto-optical trap collects up to 5 x 108 87Rb atoms beneath the chip surface. The current-carrying wires are then used to transfer the cloud of atoms to the magnetic film microtrap and radio frequency evaporative cooling is applied to produce Bose-Einstein condensates consisting of 1 x 105 atoms. We have identified small spatial magnetic field variations near the film surface that fragment the ultracold atom cloud. These variations originate from inhomogeneity in the film magnetisation and are characterised using a novel technique based on spatially resolved radio frequency spectroscopy of the atoms to map the magnetic field landscape over a large area. The observations agree with an analytic model for the spatial decay of random magnetic fields from the film surface. Bose-Einstein condensates in our unique potential landscape have been used as a precision sensor for potential gradients. We transfer the atoms to the central region of the chip which produces a double-well potential. A single BEC is formed far from the surface and is then dynamically split in two by moving the trap closer to the surface. After splitting, the population of atoms in each well is extremely sensitive to the asymmetry of the potential and can be used to sense tiny magnetic field gradients or changes in gravity on a small spatial scale.