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Showing 1 to 20 of 58 for “"highly branched"”.
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Combinatorics and Modelling of Highly Branched Polymers
Highly branched polymers such as dendrimers and hyperbranched polymers have a found a variety of chemical applications owing to their unique structural and functional properties, but in many cases are still lacking sufficient theoretical characterization. This thesis takes marginal steps toward …
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Synthesis and Characterization of Multiphase, Highly Branched Polymers
… frequently cited as a key application for hyperbranched polymers. However, the high degree of branching in these polymers restricts entanglement and the resultant mechanical properties suffer. Longer distances between branch points may allow entanglements. Highly branched polymers, where linear …
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SOURCES AND STRUCTURES OF COMMONLY OCCURRING HIGHLY BRANCHED ISOPRENOID ALKENES
Highly branched isoprenoid (HBI) alkenes are ubiquitous lipids which have been identified in numerous geochemical samples, ranging from recent sediments to ancient oils. At the outset of the current investigation, the diatomaceous algae Haslea ostrearia (C25 alkenes) and Rhizosolenia setigera (C25 …
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STRUCTURAL CHARACTERISATION OF HIGHLY BRANCHED ISOPRENOID ALKENES FROM SEDIMENTS AND ALGAE
At least fourteen C25 highly branched isoprenoid (HBI) alkenes have been previously reported in estuarine and coastal sediments from locations worldwide. The parent alkane structure has been proven but only a few of the double bond positions established previously. A wide body of evidence suggests …
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Structural Characterisation and the Diagenetic Pathways of C25 Highly Branched Isoprenoid Hydrocarbons
Highly branched isoprenoid (HBI) hydrocarbons have been widely reported in recent sediments. It is known that two species of diatomaceous algae, the diatoms Haslea ostrearia and Rhizosolenia setigera are able to biosynthesise C25 HBI alkenes. Large scale cultures of H. ostrearia studied previously, …
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Phenylene Vinylene Based Supramolecular Materials: Triblock Rodcoil Molecules and Highly Branched Amphiphiles
This work involved the programming of molecules to spontaneously self organize into supramolecular structures with dimensions in the few to hundred nanometer range. The molecular system investigated is termed a triblock rodcoil system since two of it's blocks are conformationally flexible while the …
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Designing New Pt-Based Catalysts: Dual Manipulation of Highly-Branched Structures and Intermixed Compositions
… nanoparticle (NP) growth; manipulating highly-branched morphologies and also composition. This dual control of properties promises to significantly reduce Pt reliance and synthesis cost and complexity while enhancing catalytic activity The first section explores the combination of Pt …
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Synthesis and Characterization of Branched Macromolecules for High Performance Elastomers, Fibers, and Films
… A2 + B3 polymerization for the synthesis of hyperbranched polymers was altered using oligomeric precursors in place of either one or both of the monomer pairs to synthesize highly branched macromolecules. Unique topologies that are intermediates between long-chain branched and hyperbranched …
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Investigation of the Influence of Selected Variables on the Solid State Structure-Property Behavior of Segmented Copolymers
… of segmented was also investigated by comparing highly branched segmented polyurethaneureas with their linear analogs. These copolymers were based on poly(propylene oxide) or poly(tetramethylene oxide) as the soft segments The highly branched copolymers utilized in this dissertation were able to …
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The effect of field pea (Pisum sativum L.) basal branching on optimal plant density and crop competitiveness
… population without reduced yield or to choose a highly branched cultivar to have reduced risk of yield loss under conditions of poor emergence. The objective of this research was to determine how differences in branching among seven representative pea cultivars affected crop yield at different …
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Organic reactions catalyzed by copper(I) hydride complexes
… modulating the nitrogen-protecting group, either highly branched- or linear-selective addition can be achieved from the same allene. Both reactions exhibit excellent diastereoselectivity and broad functional-group tolerance. Good enantioselectivity can also be achieved in the linear-selective …
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Characterizing the Expression Pattern of miR167-Regulated ZmArf3 and ZmArf30 in Maize Inflorescences
… vegetative and reproductive defects, including highly branched inflorescences. Most miRNAs are moderately reduced in fzt plants compared to normal controls, but some miRNAs are more dramatically affected. One of the most significantly reduced miRNA in fzt plants is miR167d-3p, which is reduced …
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The synthesis, characterization and properties of new organometallic polymers
We have reviewed recent work on highly branched polymers called dendrimers. Two novel block copolymers consisting of organoruthenium dendritic wedges and linear polyethylene glycol blocks have been prepared. These new block copolymers have been characterized by IR, ¹H and ¹³C NMR, microanalysis, as …
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The catalytic conversion of low chain length hydrocarbons to liquid fuels using ion exchange resin
… to liquid fuels has shown that the catalyst is highly active, deactivates at a slow rate and selectively produces mainly dimers. Macropore diffusion resistance strongly influences the overall rate of the reaction. An increase in liquid production rate is obtained with increasing macroporosity, …
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Reconstruction of recent and palaeo sea ice conditions in the Barents Sea
IP25 is a highly branched isoprenoid alkene derived from certain Arctic sea ice diatoms that, when detected in marine sediments, has been used as a proxy for past Arctic sea ice over the last decade. In the current study, the structure of this biomarker was determined following large-scale …
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Interpretable Supervised Learning and Graph-Based Optimization for Glycan-Lectin Binding
… there is particular interest in the design of highly specific glycan binders to critical lectins such as dendritic cell-specific ICAM-grabbing non-integrin (DC-SIGN). However, insufficient knowledge of the binding specificity of lectins, combined with the enormous structural complexity of …
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Sexual dimorphism in the genus Leucadendron : Morphology and plant hydraulics
… of sexual dimorphism. Males are generally more highly ramified (branched) with smaller leaves compared to corresponding females. It has been hypothesised that sexual dimorphism in Leucadendrons is linked to serotiny (a fire-adapted reproductive strategy), where highly serotinous females may …
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Investigation on the Morphology of Charge-Transfer Complexes in Low Density Polyethylene
… temperature, or cooling rate to form needle and highly branched dendritic micro-crystallites. Optical imaging was used visualize the microstructure of the CTC crystallites. Fourier-transform infrared spectroscopy (FTIR) was used to confirm complexation of the TTF-TCNQ via shifts in the aromatic …
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SYNTHETIC AND BIODEGRADATION STUDIES OF SOME SEDIMENTARY ISOPRENOID HYDROCARBONS
… reports of a group of abundant C20, C25 and C30 highly branched acyclic alkanes and alkenes in surface sediments. Synthesis and spectral and chromatographic characterisation of 2,6,10-trimethyl-7-(3-methylbutyl) dodecane (C20), 2,6,10,14-tetramethyl-7-(3-methylpentyl) pentadecane (C25) and …
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Crystallization and Melting Studies of Poly(ε-caprolactone) and Poly(ethylene oxide) using Flash™ Differential Scanning Calorimetry and Preparation and Characterization of Poly(δ-valerolactone) Fractions
… to appear near the glass transition temperature, highly branched solid sheaves grow throughout the homogeneous primary nucleation temperature range, and spherulites grow in the heterogenous primary nucleation range. Poly(δ-valerolactone) was synthesized using microwave-assisted techniques. Narrow …
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