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21	Contribution of Bulky <&alpha>,<&beta>-Dehydroamino Acids to the Proteolytic Stability andEnhanced Folding of <&beta>-Hairpins and Progress Towards the Total Synthesis of Yaku<'>amide A Jalan, Ankur 01 March 2018 (has links) This dissertation primarily covers the impact of bulky ,-dehydroamino acids on the proteolytic stability and enhanced folding of -hairpins. It partly describes the progress towards the total synthesis of yakuamide A, a potent anticancer peptide with an IC50 value of 14 ng/mL against leukemia cells. Proteins and peptides are a very attractive source of potential medicinal agents as they can target various protein“protein interactions that are implicated in several diseases and disorders. The global sales of peptide drugs in 2013 were estimated to be about $28 billion and are constantly rising at an appreciable rate. However, peptide drugs have a short plasma half-life because of their susceptibility to proteolysis. Multiple approaches have been discovered to overcome this shortcoming, but there is still an urgent need for better peptidomimetics to increase the stream of peptides entering the pharmaceutical market. Here, it has been demonstrated that the incorporation of a bulky ,-dehydroamino acid in the turn regions of -hairpins can substantially increase their proteolytic stability and folding. Insertion of a dehydrovaline (Î”Val) residue at the i+1 position imparted ca. 7-fold increase in proteolytic resistance and ca. 15% increase in folding when compared to the parent peptide. Since the insertion of a bulky ,-dehydroamino acid into the turn regions of -hairpins can promote proteolytic stability without perturbing the secondary structures, it is believed that this novel approach is very promising in stabilizing bioactive turn-containing peptides for therapeutic use.Yakuamide A is a medium-sized peptide that contains several bulky dehydroamino acids, -hydroxyamino acids and unique N- and C-termini. It has an unprecedented anticancer profile, and potent bioactivity, hence it was imperative to accomplish its total synthesis to elicit its unique mode of action and biological target. More efficient methods were developed to synthesize bulky dehydroamino acids and -hydroxyamino acids. A regioselective base-free aminohydroxylation was developed for the synthesis of -hydroxyamino acids. The major focus was the three-step synthesis of the N-terminal acyl group from a known compound by a one-pot indium-catalyzed cross-Claisen condensation/reduction and the synthesis of (2S,3R)--hydroxyisoleucine, and racemic -hydroxyisoleucine, which are the precursors of E- and Z-dehydroisoleucine. bulky <&alpha> <&beta>-dehydroamino acids <&beta>-hairpins proteolytic stability increased folding aminohydroxylation <&beta>-hydroxyamino acids N-terminal acyl group Chemistry Physical Sciences and Mathematics
22	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)
23	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 (has links) Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)
24	SHEAR RHEOMETRY PROTOCOLS TO ADVANCE THE DEVELOPMENT OF MICROSTRUCTURED FLUIDS Eduard Andres Caicedo Casso (6620462) 15 May 2019 (has links) <p></p><p>This doctoral dissertation takes the reader through a journey where applied shear rheology and flow-velocimetry are used to understand the mesoscopic factors that control the flow behavior of three microstructured fluids. Three individual protocols that measure relative physical and mechanical properties of the flow are developed. Each protocol aims to advance the particular transformation of novel soft materials into a commercial product converging in the demonstration of the real the chemical, physical and thermodynamical factors that could potentially drive their successful transformation. </p> <p> </p> <p>First, this dissertation introduces the use of rotational and oscillatory shear rheometry to quantify the solvent evaporation effect on the flow behavior of polymer solutions used to fabricate isoporous asymmetric membranes. Three different A-B-C triblock copolymer were evaluated: polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(4-vinylpyridine) (ISV); polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(<i>N</i>,<i>N</i>-dimethylacrylamide) (ISD); and polyisoprene-<i>b</i>-polystyrene-<i>b</i>-poly(<i>tert</i>-butyl methacrylate) (ISB). The resulting evaporation-induced microstructure showed a solution viscosity and film viscoelasticity strongly dependent on the chemical structure of the triblock copolymer molecules. </p> <p> </p> <p>Furthermore, basic shear rheometry, flow birefringence, and advanced flow-velocimetry are used to deconvolute the flow-microstructure relationships of concentrated surfactant solutions. Sodium laureth sulfate in water (SLE<sub>1</sub>S) was used to replicate spherical, worm-like, and hexagonally packed micelles and lamellar structures. Interesting findings demonstrated that regular features of flow curves, such as power-law shear thinning behavior, resulted from a wide variety of experimental artifacts that appeared when measuring microstructured fluids with shear rheometry.</p> <p> </p> <p>Finally, the successful integration of shear rheometry to calculate essential parameters to be used in a cost-effective visualization technique (still in development) used to calculate the dissolution time of polymers is addressed. The use of oscillatory rheometry successfully quantify the viscoelastic response of polyvinyl alcohol (PVA) solutions and identify formulations changes such as additive addition. The flow behavior of PVA solutions was correlated to dissolution behavior proving that the developed protocol has a high potential as a first screening tool.</p><br><p></p> Rheology Polymers and Plastics Applied Rheology shear rheometry self-assembly block copolymers Water-soluble polymers concentrated surfactants flow-visualization Ultrasonic speckle velocimetry simple-shear flow-instabilities wall-slip plug-flow Flow-Birefringence polymer dissolution polymer swelling shear-induced microstructures SNIPS polymer solutions triblock terpolymers PVA SLE1S bulky side groups spherical micelles worm-like micelles hexagonal phase Lamellar phase poly vinyl alcohol ISV ISD ISB Complex fluids microstructured fluids Flow Behaviors
25	Katedrála / Cathedral Kliment, Jakub January 2016 (has links) The statue called The Cathedral is a natural extension of my work, which deals with organic morphology of the landscape, both the details and grand compositions, which in the countryside vyskytují.Stejně like most authors is my creative work reflection of my surroundings, both personal so near in geographical terms. Integrating these aspects arise impetus to creation. In the case of sculptures entitled The Cathedral is a rendering of the very strong impression of verticality, which dominates the landscape. Regularly clashing with seemingly ordinary natural objects such as trees, soil, hills or reliefs and reliefs such as landscapes, I got into an imaginary dialogue, which I decided to answer this statue and also portray already mentioned impressed. This feeling is for me identically comparable to a situation where the viewer stands in front of the high Gothic building and trying to accommodate the shape of a giant who stands before him. Its peak, it seems so distant, as if no end, and the broad base is a kind of sign of confidence in the form of stability. Parallels between these seemingly different topics I could not miss, so I decided to call the statue Cathedral. In this work, as in previous ones, I try to get into organic sculptures character with the help of the deformation of materials, or basically draping. Compacting elastic materials to try to create the statues of the tension that fascinates me in nature and creates the impression of growth, which is in the countryside of one of the strongest motives. Shape diversity, which is in the landscape, in my inexhaustible source of inspiration and has become lately a space that fills me. When I release the perception of various aspects of your imagination and build imaginary composition, which would then be identical expression perceived impressions.
26	Vysokovklopn lopata devn tÄpky / High tipping shovel for the wood chips ulk, Petr January 2021 (has links) High tipping shovel, wood chips, quick coupler, shovel, high tipping shovel frame, Volvo L60H loader, wheel loader accessories, linear hydraulic motor

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