Novel Precision Polyolefins from Living Coordinative Chain-Transfer Polymerization

ABSTRACT Title of Document: Novel Precision Polyolefins from Living Coordinative Chain-Transfer Polymerization Rennisha R. Wickham Doctor of Philosophy, 2012 Directed By: Professor Lawrence. R. Sita Department of Chemistry and Biochemistry Polyolefins (POs), especially polyethene (PE) and polypropene (PP), are by far the largest volume synthetic polymers in the plastic industry, with annual global production exceeding 1.4 × 108 metric tons and projected to increase to 200 million tons by the year 2020 according to the 2007 National Petrochemical and Refiners Association Report. This is primarily due to their benign nature, excellent cost performance value, as well as ease of recycling, processing and fabrication. With societal dependence on polyolefins steadily increasing, efforts have been placed on the development of living coordinative chain-transfer polymerization (LCCTP) towards the large scale production of functionalized copolymers and block copolymers from commodity volume monomers, ethene (E) and propene (P) with α-olefins, cyclic and sterically encumbered olefin comonomers that could potentially be used as compatibilizers in polymer mixtures, thermoplastic elastomeric substitutes of EPDM rubber, and macro-initiators in anionic and free radical polymerizations methods. Copolymerizations of E and P with monomers that can be obtained in industrially significant volumes from renewable biomass-derived feedstocks or waste product streams are investigated. The diterpene β-citronellene, represents an ideal target as a potential co-monomer since after incorporation through Ziegler-Natta enchainment of the terminal vinyl group, the remaining tri-substituted double bond is available for further chemical modification or cross-linking. Norbornene is also a desirable comonomer for ethene copolymerization as the resulting polyolefin materials are optically transparent and can be used as replacements for polycarbonates. Another non-conjugated diene, 1,5-hexadiene, has been utilized in conjunction with 1-hexene or 1-octene to produce rod-coil block copolymers that could potentially give way to polyolefins having new end-use properties through microphase separation into various nanostructures. Moreover, post-functionalization of PE and PP materials with I, N3, OH, and PPh3 etc., is investigated as a route towards the production of value-added polymers. Finally, this work utilizes aims to develop new spectroscopic and analytical tools for the structural analysis of hydrocarbons materials, as these properties directly influence the chemical and physical properties. Therefore, the practicality of MALDI-TOF MS as a routine characterization method for the evaluation of new polyolefins was probed. Overall this thesis will discuss the tailored synthesis, functionalization and characterization of ethene and propene based polymers

Miniature pressure transducer for stressed member application

Miniature pressure transducer responds to static or dynamic pressures acting against a structural surface without introducing errors caused by stresses in the structural surface. This is accomplished by a thin stainless steel pressure sensing diaphragm with an attached foil strain gage

Meta‐analysis on pulse disturbances reveals differences in functional and compositional recovery across ecosystems

Most ecosystems are affected by anthropogenic or natural pulse disturbances, which alter the community composition and functioning for a limited period of time. Whether and how quickly communities recover from such pulses is central to our understanding of biodiversity dynamics and ecosystem organisation, but also to nature conservation and management. Here, we present a meta‐analysis of 508 (semi‐)natural field experiments globally distributed across marine, terrestrial and freshwater ecosystems. We found recovery to be significant yet incomplete. At the end of the experiments, disturbed treatments resembled controls again when considering abundance (94%), biomass (82%), and univariate diversity measures (88%). Most disturbed treatments did not further depart from control after the pulse, indicating that few studies showed novel trajectories induced by the pulse. Only multivariate community composition on average showed little recovery: disturbed species composition remained dissimilar to the control throughout most experiments. Still, when experiments revealed a higher compositional stability, they tended to also show higher functional stability. Recovery was more complete when systems had high resistance, whereas resilience and resistance were negatively correlated. The overall results were highly consistent across studies, but significant differences between ecosystems and organism groups appeared. Future research on disturbances should aim to understand these differences, but also fill obvious gaps in the empirical assessments for regions (especially the tropics), ecosystems and organisms. In summary, we provide general evidence that (semi‐)natural communities can recover from pulse disturbances, but compositional aspects are more vulnerable to long‐lasting effects of pulse disturbance than the emergent functions associated to them

Beyond expectations: the physiological basis of sensory-enhancement of satiety

Background/Objectives: Consumption of high-energy beverages has been implicated as a risk factor for weight gain, yet why nutrients ingested as beverages fail to generate adequate satiety remains unclear. In general consumers do not expect drinks to be satiating, but drinks generate greater satiety when their sensory characteristics imply they may be filling. These findings challenge traditional bottom-up models of how gut-based satiety signals modify behavior to suggest that beliefs at the point of ingestion modify gut-based satiety signaling. Subjects/Methods: Healthy volunteers (n = 23) consumed four different beverages, combining an overt sensory manipulation (thin, Low Sensory, LS, or thicker and more creamy, Enhanced Sensory, ES) and covert nutrient manipulation (low energy, LE, 78kcal; high energy, HE, 267 kcal) on different days. Effects on satiety were assessed through rated appetite and levels of glucose, insulin, pancreatic polypeptide (PP) and cholesystokinin (CCK) recorded periodically over 90 minutes, and through intake at an ad libitum test lunch. Results: Intake at the test lunch and rated appetite were both altered by both the sensory and nutrient manipulations, with lowest intake and greatest suppression of hunger post-drink in the ESHE condition. Insulin increased more after HE than LE drinks, and after ES than LS drinks, while PP levels were higher after ES than LS versions. CCK levels only increased after the ESHE drink. Conclusions: These data confirm acute sensitivity of satiety after consuming a drink both to the sensory characteristics and nutrient content of the drink, and suggest that this may be at least in part due to top-down modulation of release of satiety-related gut hormones

“If You've Got Friends and Neighbours”: Constituency Voting Patterns for the UK Labour Party Leader in 2010

Most attention in British electoral studies has been paid to the pattern of voting for parties, with relatively little to that for individual candidates. In intra-party elections, however, candidates may perform better in some areas than others, illustrating V. O. Key's well-known “friends and neighbours” effect. This paper explores whether that was so at the election for the leader of the UK Labour party in 2010, expecting each of the five candidates to perform better in their own constituency and its environs and also with those constituency parties whose MPs supported their candidature. The results are in line with the expectations, especially for one of the candidates who ran an explicitly geographical campaign

Studies of molecular architecture within solid polymer electrolytes and teichoic acid biopolymers from solid-state nuclear magnetic resonance spectroscopy.

The unsuccessful collection of a 31P CP-MAS spectrum in frozen D2O suggests the presence of liquid water around LTA. 2H SSNMR were used to study the phase of the water environments for LTA dissolved in D2O at -25 and -40° C. This resulted in the presence of a narrow (liquid) and broad (solid) signal at both temperatures, demonstrating that LTA is an anti-freeze agent.There is little structural information for dilute salt systems, thus we have characterize the crystalline microdomains of a 20:1 PEO:LiTf sample using the REDOR SSNMR experiment. Our data clearly demonstrates that the lithium crystalline microdomains are nearly identical to that of the crystalline 3:1 sample.Part II. Teichoic acids important to bacteria since they participate in surface adhesion, metal ion coordination, and survival at subzero temperatures. However, there is very little molecular level information available for the initial adhesion of bacteria to solid surfaces. 31P CP-MAS spectra and T1p data demonstrate that the structure of LTA changes when adhered to cellulose, PGN, or TiO2 (the structure of LTA on TiO2 is heterogeneous). However, when LTA is simultaneously adhered to PGN and TiO2 the observed structure is dependent on the amount of retained water. Our proposed structure for LTA on TiO2 has the alanine adhered to the surface with the glucosamine groups rotated toward the surface. However, simultaneous adhesion uses the glucosamine groups to adhere to PGN allowing water absorption between the LTA backbone and the TiO2 surface. Our NMR studies also demonstrate that WTA properties are very similar to LTA.The proposed Mg2+ binding structure to teichoic acids are monodentate fashion to either one phosphate or bridging between two phosphates. However, we show that Mg2+ binds in a bidentate fashion through compassion of experimental collected 31P CP-MAS spectra to a simulated 31P CPMAS spectra form an energy-minimized model compound.Part I. Understanding and assigning the 13C NMR signals are vital to interpreting the NMR data collected for each phase. Previously for pure PEO, the narrow component has been assigned to the amorphous region and the broad component to the crystalline region. Using a crystalline 3:1 PEO:LiTf sample, we assign the narrow component to the crystalline PEO:LiTf region, which is reversed from the previous pure PEO assignment. Thus, we reexamine the NMR assignments for pure PEO using samples of pure powdered PEO, thermally treated pure powdered PEO, and a thin film PEO cast from an acetonitrile solution. We observed the growth of the narrow peak under conditions that favor crystallization; therefore, we reassigned the narrow peak to the crystalline region and the broad peak to the amorphous region

MCMC Exploration of Supermassive Black Hole Binary Inspirals

The Laser Interferometer Space Antenna will be able to detect the inspiral and merger of Super Massive Black Hole Binaries (SMBHBs) anywhere in the Universe. Standard matched filtering techniques can be used to detect and characterize these systems. Markov Chain Monte Carlo (MCMC) methods are ideally suited to this and other LISA data analysis problems as they are able to efficiently handle models with large dimensions. Here we compare the posterior parameter distributions derived by an MCMC algorithm with the distributions predicted by the Fisher information matrix. We find excellent agreement for the extrinsic parameters, while the Fisher matrix slightly overestimates errors in the intrinsic parameters.Comment: Submitted to CQG as a GWDAW-10 Conference Proceedings, 9 pages, 5 figures, Published Versio

Anaerobic digestion of soft drink beverage waste and sewage sludge

© 2018 Soft drink beverage waste (BW) was evaluated as a potential substrate for anaerobic co-digestion with sewage sludge to increase biogas production. Results from this study show that the increase in biogas production is proportional to the increase in organic loading rate (OLR) rate due to BW addition. The OLR increase of 86 and 171% corresponding to 10 and 20% BW by volume in the feed resulted in 89 and 191% increase in biogas production, respectively. Under a stable condition, anaerobic co-digestion with BW did not lead to any significant impact on digestate quality (in terms of COD removal and biosolids odour) and biogas composition. The results suggest that existing nutrients in sewage sludge can support an increase in OLR by about 2 kg COD/m3/d from a carbon rich substrate such as soft drink BW without inhibition or excessive impact on subsequent handling of the digestate

Recent advancements in monolithic AlGaAs/GaAs solar cells for space applications

High efficiency, two terminal, multijunction AlGaAs/GaAs solar cells were reproducibly made with areas of 0.5 sq cm. The multiple layers in the cells were grown by Organo Metallic Vapor Phase Epitaxy (OMVPE) on GaAs substrates in the n-p configuration. The upper AlGaAs cell has a bandgap of 1.93 eV and is connected in series to the lower GaAs cell (1.4 eV) via a metal interconnect deposited during post-growth processing. A prismatic coverglass is installed on top of the cell to reduce obscuration caused by the gridlines. The best 0.5 sq cm cell has a two terminal efficiency of 23.0 pct. at 1 sun, air mass zero (AM0) and 25 C. To date, over 300 of these cells were grown and processed for a manufacturing demonstration. Yield and efficiency data for this demonstration are presented. As a first step toward the goal of a 30 pct. efficient cell, a mechanical stack of the 0.5 sq cm cells described above, and InGaAsP (0.95 eV) solar cells was made. The best two terminal measurement to date yields an efficiency of 25.2 pct. AM0. This is the highest reported efficiency of any two terminal, 1 sun space solar cell