In the first Chapter, Polyhomologation, a powerful technique to synthesize well-defined, perfectly linear, polyethylenes with controllable molecular weight, topology and low polydispersity, is presented in the first Chapter. In this Chapter is also discussed the combination of polyhomologation with other polymerization techniques such as Ring Opening Polymerization, ROP, Atom Transfer Radical Polymerization, ATRP, as well as with chlorosilane linking chemistry towards well-defined polyethylene-based macromolecular architectures. In the second Chapter, α,ω-dihydroxy-polyethylene was synthesized by the polyhomologation of dimethylsulfoxonium methylide with 9-thexyl-9-BBN (9-BNN: 9-borabicyclo[3.3.1]nonane), a novel difunctional initiator produced from 9-BBN and 2,3-dimethylbut-2-ene with two active and one blocked sites, followed by hydrolysis/oxidation. The terminal hydroxy groups were used either directly as initiators, in the presence of 1-tertbutyl-2,2,4,4,4-pentakis(dimethylamino)-2λ5,4λ5-catenadi(phosphazene) (t-BuP2), for the ring opening polymerization of ε-caprolactone, ε-CL, in order to afford polycaprolactone-b-polyethylene-b-polycaprolactone (PCL-b-PE-b-PCL) or after transformation to ATRP initiating sites in order to polymerize styrene and produce polystyrene-b-polyethylene-b-polystyrene (PSt-b-PE-b-PSt) triblock copolymers. Molecular characterization by 11B, 13C and 1H NMR as well as FTIR, and high-temperature GPC (HT-GPC) confirmed the well-defined nature of the synthesized new difunctional initiator and triblock copolymers. Differential scanning calorimetry was used to determine the melting points and degree of crystallinity of PE and PCL. In the third Chapter, a novel triallylborane initiator was synthesized and used to afford α-allyl-ω-hydroxy-polyethylene by polyhomologation of dimethylsulfoxonium methylide. The α-allyl-ω-hydroxy-polyethylene was then used as a macroinitiator (OH group) for the ROP of ε-CL and LLA to afford well-defined triblock terpolymer of polylactide-b-polyethylene-b-polycaprolactone (PLLA-b-PE-b-PCL). The characterization of all intermediate and final products by 1H NMR, FTIR, and HT-GPC, verified the well-defined nature of the triblock terpolymer. In the fourth Chapter, polyethylene (PE)-based 3- and 4-miktoarm star [PE(PCL)2, PE(PCL)3], as well as H-type [(PCL)2PE(PCL)2] block copolymers (PCL: polycaprolactone), were synthesized by combining polyhomologation, chlorosilane chemistry, and Ring Opening Polymerization (ROP). For the synthesis of miktoarm stars, a hydroxyl-terminated PE-OH, prepared by polyhomologation of dimethylsulfoxonium methylide with a monofunctional boron initiator, reacted with either chloromethyl(methyl)dimethoxysilane or chloromethyltrimethoxysilane. After the hydrolysis of the methoxysilane groups, the produced difunctional or trifunctional macroinitiators were used for the ROP of ε-caprolactone, in the presence of 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2λ5,4λ5-catenadi(phosphazene)(t-BuP2). The H-type block copolymers were synthesized using the same strategy but with a difunctional polyhomologation initiator. All intermediates and final products were characterized by HT-GPC, 1H NMR, and FTIR analysis. The thermal properties of the PE precursors and final products were studied by DSC and TGA. In the fifth Chapter, the self-assembly properties of the amphiphilic linear block copolymer PE-b-PCL and 3-miktoarm star copolymers (PE-b-PCL2) were studied in THF, a selective solvent for PCL, by Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and Atomic Force Microscope (AFM). All the above findings presented in this dissertation emphasize the utility of polyhomologation for the synthesis of well-defined polyethylene-based complex macromolecular architectures, which is practically impossible through another kind of polymerization, including the catalytic polymerization of ethylene. In the sixth Chapter, the summary of the thesis and some consideration on the subjects of future work are given.

No description available.

Polylactides (PLA) are thermoplastic materials known for their biodegradability and biocompatibility, and therefore mostly utilized in biomedical applications. PLA-containing block copolymers further expand their application to include commodity materials and even advanced nanoporous materials. This research part of the thesis focuses on the synthesis and characterization of PLA-containing block copolymers, as well as their corresponding stereocomplexes formed by mixing block copolymers containing PLLA and PDLA segments. This work is divided into three parts. First, by using “living” anionic polymerization of styrene (St) and 2-vinylpyridine (2VP) followed by subsequent ethylene-oxide (EO) termination, well-defined hydroxyl-terminated polystyrene (PS) and poly(2-vinylpyridine) (P2VP) were synthesized. The resulting homopolymers were characterized by 1H nuclear magnetic resonance (NMR), size-exclusion chromatography (SEC), and infrared (IR) spectroscopy. The molecular weights were determined by SEC to be 6,200 and 5,500 g.mol-1 for PS and P2VP, respectively. In the second part, the two homopolymers, PS-OH and P2VP-OH were used as the macroinitiators for the ring-opening polymerization (ROP) of D- and L-lactides (D/L-LA) to obtain PS-b-PDLA and P2VP-b-PLLA, respectively. The targeted molecular weights of PLA blocks were varied to be 5,000, 7,000, and 10,000 g.mol-1 In the final part, quantitative stereocomplex formation was achieved by mixing PS-b-PDLA and P2VP-b-PLLA having equimolar PLAs segments. The physical and chemical properties of the diblockcopolymers and their corresponding stereocomplex, as well as the influence of varying the molecular weights of PLA blocks, were investigated by differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and circular dichroism (CD) spectroscopy.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第18338号 / 農博第2063号 / 新制||農||1023(附属図書館) / 学位論文||H26||N4845(農学部図書室) / 31196 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 大澤 晃, 教授 髙部 圭司, 教授 北山 兼弘 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

No description available.

Cavity ring-down (CRD) spectroscopy has emerged as a sensitive analytical technique. In this method, a laser pulse is injected through one of two highly-reflective mirrors which form a stable optical cavity and the rate that the light leaves the cavity is monitored by a detector placed behind the second mirror. In this research a CRD spectrometer has been designed and constructed. The light exiting the cavity is collected via a fiber optic cable which is then directed toward a photo multiplier tube (PMT) detector. The signal is digitized and averaged by an oscilloscope and the data are transferred by an I 488 interface to a personal computer where the data are analyzed. Instrument command and data acquisition are controlled by a Visual Basic computer program. A short review of several attempts to measure liquid samples using CRD spectroscopy is presented; most discuss the necessity for the incorporation of Brewster’s angle at the liquid interface. This study integrates a 1 cm standard quartz cuvette at normal incidence. It was determined that there are significant losses from scattering and reflection; however, these losses were not so large as to negate the efficacy of the technique. The hypothesis tested here is that the light “lost” as reflections are collected by the cavity mirrors and redirected back into the cavity. Rhodamine 6G was used as the primary model absorber in these studies. Absorbance measurements were extracted from the measured ring-down times and a detection limit was obtained. Four cavity lengths were constructed to determine the effect on the scattering losses with varying cavity lengths. The calculated detection limit for the CRD spectrometer used in this study was found to be in the range of 4-5 nM. It was found that the detection limit of the CRD spectrometer was 36 times lower than that of the commercial instrument. Aligning the cavity mirrors at longer cavity lengths proved to be more difficult; however, there were no significant additional losses observed by incorporating longer cavities.

No description available.

For a sample of collisional ring galaxies, archival Hubble Space Telescope images were used to compare individual star clusters and kpc-sized clumps of star formation to each other in a variety of ways. For each galaxy, instrument, and filter, the magnitude of the brightest cluster in a clump was compared to the magnitude of the entire clump, and the fraction of the flux of the clusters in a clump over the flux of the entire clump was calculated and compared to star formation rates. In addition, a cluster luminosity function for each galaxy was derived. Comparing the brightest cluster in a clump to the magnitude of the entire clump and the flux ratio to the star formation rate did not show any significant patterns. However, the α found for the galaxies tended to be much flatter than what had been found in previous research. The α found seemed to be affected by the size of the bin used in the luminosity function. Using this information, α could be calculated for other incredibly luminous galaxies to see if the trend of flatter α continues.

The Cassini mission provided wonderful tools to explore Saturn, its satellites and its rings system. The UVIS instrument allowed stellar occultation observations of structures in the rings with the best resolution available (around 10 meters depending on geometry and navigation), bringing our understanding of the physics of the rings to the next level. In particular, we have been able to observe, dissect, model and test the interactions between the satellites and the rings. We first looked at kilometer-wide structures generated by resonances with satellites orbiting outside the main rings. The observation of structures in the C ring and their association with a few new resonances allowed us to estimate some constraints on the physical characteristics of the rings. However, most of our observed structures could not be explained with simple resonances with external satellites and some other mechanism has to be involved. We located four density waves associated with the Mimas 4:1, the Atlas 2:1, the Mimas 6:2 and the Pandora 4:2 Inner Lindblad Resonances and one bending wave excited by the Titan -1:0 Inner Vertical Resonance. We could estimate a range of surface mass density from 0.22 ([plus or minus]0.03) to 1.42 ([plus or minus]0.21) g cm[super-2] and mass extinction coefficient from 0.13 ([plus or minus]0.03) to 0.28 ([plus or minus]0.06) cm[super2] g[super-1]. These mass extinction coefficient values are higher than those found in the A ring (0.01 - 0.02 cm[super2] g[super-1]) and in the Cassini Division (0.07 - 0.12 cm[super2] g[super-1] from Colwell et al. (2009), implying smaller particle sizes in the C ring. We can therefore imagine that the particles composing these different rings have either different origins or that their size distributions are not primordial and have evolved differently.; Using numerical simulations for the propeller formation, we estimate that our observed moonlets belong to a population of bigger particles than the one we thought was composing the rings: Zebker et al. (1985) described the ring particles population as following a power-law size distribution with cumulative index around 1.75 in the Cassini Division and 2.1 in the C ring. We believe propeller boulders follow a power-law with a cumulative index of 0.6 in the C ring and 0.8 in the Cassini Division. The question of whether these boulders are young, ephemeral and accreted inside the Roche limit or long-lived and maybe formed outisde by fragmentation of a larger body before migrating inward in the disk, remains a mystery. Accretion and fragmentation process are not yet well constrained and we can hope that Cassini extended mission will still provide a lot of information about it.; We also estimate the mass of the C ring to be between 3.7 ([plus or minus]0.9) x 10[super16] kg and 7.9 ([plus or minus]2.0) x 10[super16] kg, equivalent to a moon of 28.0 ([plus or minus]2.3) km to 36.2 ([plus or minus]3.0) km radius (a little larger than Pan or Atlas) with a density comparable to the two moons (400 kg m[super-3]). From the wave damping length and the ring viscosity, we also estimate the vertical thickness of the C ring to be between 1.9 ([plus or minus]0.4) m and 5.6 ([plus or minus]1.4) m, which is consistent with the vertical thickness of the Cassini Division (2 - 20 m) from Tiscareno et al. (2007) and Colwell et al. (2009). Conducting similar analysis in the A, B rings and in the Cassini Division, we were able to estimate consistent masses with previous works for the these rings. We then investigated possible interactions between the rings and potential embedded satellites. Looking for satellite footprints, we estimated the possibility that some observed features in the Huygens Ringlet could be wakes of an embedded moon in the Huygens gap. We discredited the idea that these structures could actually be satellite wakes by estimating the possible position of such a satellite. Finally, we observed a whole population of narrow and clear holes in the C ring and the Cassini Division. Modeling these holes as depletion zones opened by the interaction of a moonlet inside the disk material (this signature is called a "propeller"), we could estimate a distribution of the meter-sized to house-sized objects in these rings. Similar objects, though an order of magnitude larger, have been visually identified in the A ring. In the C ring, we have signatures of boulders which sizes are estimated between 1.5 and 14.5 m, whereas similar measures in the Cassini Division provide moonlet sizes between 0.36 and 58.1 m.

The objective of this research was to investigate parameters affecting vortex ring formation and propagation and their application to mixing of fluids. To this end both empirical and numerical simulation experiments were conducted. The empirical experiments involved observations and measurement of the volume, displacement and velocity of vortex rings generated from a 5 cm diameter tube. The results revealed that there is an optimal range of generation injection velocity for various mixing requirements. The numerical simulations were done using a commercial package, FLUENT. Both tube type and plate orifice type vortex ring generators were investigated. Also the affects of a central shaft and various projections on the control of the motion of a vortex ring. All models considered a polar model cylindrical tank with a diameter to height ratio of 3:10. The average injection velocity was in the range of 0.7 m/s to 3 m/s. When simulating the tube type generator various injection velocity profiles and value were investigated, which resulted in a fitted correlations of nondimension displacement versus non-dimension time as a function of infection profile. In order to control the forward motion of vortex rings some obstructions were considered. It was found that the trajectory and energy of a vortex ring can be controlled with shape and geometries of baffles. In the simulations for the orifice plate type generator, a moving mesh technique was used. As expected a pair of vortex rings were produced per half cycle of the plate oscillation, but they did not travel as fast as expected. Recommendations have been made to improve the simulation accuracy. It has also been found that the FLUENT package will not properly simulate turbulent vortex rings. However, this may be because a vortex ring is not truly homogeneously turbulent. The use of a laminar model appears to give quite good agreement with empirical data for tube type vortex ring generator. The results of this research are expected to be useful for the optimization of the design of vortex ring mixing systems. / Thesis / Master of Engineering (ME)