Zugl.: München, University, Diss., 2008.

Zugl.: München, Techn. Universiẗat, Diss., 2008.

Thesis (doctoral)--Christian-Albrechts-Universität zu Kiel, 2004.

Thesis (Ph. D.)--Montana State University--Bozeman, 2006. / Typescript. Chairperson, Graduate Committee: David M. Dooley. Includes bibliographical references (leaves 204-216).

Th.--Sci.--Bordeaux 1, 1979. N°: 597.

An investigation is made of the interactions between a variety of small molecule phosphates and amines, and in particular of triethylenetetramine with hexametaphosphate, pyrophosphate, tripolyphosphate, ADP and ATP and of cyclic triethylenetriamine with hexametaphosphate. For each phosphate/amine pair, observed changes in the pH dependence of ¹H and ³¹P nmr chemical shift are used to calculate the effect of interaction on the pK_a of the two species present and an association constant is evaluated at one particular pH value. These data are then combined to evaluate association constants for a variety of protonation states of the phosphate and amine. Strength of association is interpreted in terms of electrostatic charge and its spatial distribution, comparison is made with Mg²⁺ and Ca²⁺ complexes and biological relevance is discussed. The interaction of yeast PGK with its substrates is investigated by using the (500MHz and 300MHz) ¹H nmr spectrum of the enzyme and (250MHz) ³¹P nmr spectra of its substrates. On the basis of pH dependence, comparison with the spectrum of horse PGK and T₂ relaxation data,¹H nmr resonances are assigned to surface residues. In particular, resonances are assigned to the three active site histidines (nos. 62,167 and 170), and to the exposed histidine and methionine residues. A series of comparatively well-resolved upfield shifted aromatic peaks, including a relatively exposed tyrosine peak is tentatively assigned to the interdomain hinge region of the protein. The effects of MgADP, MgATP and the non-reacting nucleotide analogue MgAMPPNP on the yeast PGK spectrum are characterised. The line-broadening reagent Gd³⁺is used to distinguish between direct influence and conformational effects. The triose phosphate substrate 3-PG is added to the enzyme as are the anionic probes [Co(CN)₆]<sup3-</sup> , [Cr(CN)₆]<sup3-</sup>and [Fe(CN)₆]<sup3-</sup> I and the nature of anion binding in the active groove of the protein and elsewhere on its surface is investigated. Movement of the two PGK domains is investigated in three models of the ternary complex: (i) with MgAMPPNP and 3-PG, (ii) with the elongated nucleotide A4P, and (iii) with a mutant form of the enzyme (his388 -gln388). The PGK/substrate interaction is interpreted in terms of the phosphate/amine model.

No description available.

La caractérisation et l’évaluation des propriétés physiques, chimiques, physico-chimiques et mécaniques sont un point important dans la compréhension du comportement des assemblages collés polymère/substrat. La spectroscopie diélectrique est une méthode de caractérisation efficace permettant d’étudier la dynamique moléculaire, et permettre aussi un suivi in situ de joints collés. La modélisation mathématique de résultats expérimentaux par la méthode de l’analyse par intervalle permet de s’affranchir de nombreux défauts de logiciels utilisés couramment (erreur expérimentale prise en compte dans les calculs du modèle, permet d’accepter ou de rejeter un modèle, …). Il a été démontré qu’en présence d’un substrat métallique, une compétition avait lieu entre la réaction de polymérisation et des réactions entre les monomères et les substrats métalliques, menant à une interphase (i.e. interface d’épaisseur non nulle) ayant des propriétés différentes des propriétés du même polymère en volume. Ces propriétés influent sur l’adhérence entre le polymère époxydeamine et le substrat d’aluminium. L’adhérence sera caractérisée par un test normé et reliée aux propriétés de l’interphase par diverses techniques. Des vieillissements de systèmes DGEBAanime/ aluminium ont été effectués. Durant ces vieillissements, des tests destructifs et non destructifs ont été effectués afin d’avoir un suivi sur les propriétés des interphases et interfaces de ces joints collés. Les résultats obtenus ont été mis en corrélation afin de pouvoir être capable par l’utilisation de tests non destructifs in situ, de pouvoir prévenir une rupture à l’interphase/interface entre l’adhésif et le substrat / Characterization and evaluation of physical, chemical, physico-chemical and mechanical properties are an important point in the comprehension of the behavior of bonded polymer/substrate assemblies. Dielectric spectroscopy is an effective method of characterization to study molecular dynamics, and also allow in situ monitoring of bonded joints. Mathematical modeling of experimental results by the method of interval analysis overcomes many shortcomings of commonly used software (experimental error taken into account, accept or reject a model ...). It has been shown that in the presence of a metal substrate, a competition was held between the polymerization reaction and the reactions between the monomers and metal substrates, leading to an interphase (i.e. non-zero thickness of interface) having properties different than these of the bulk. These properties influence the adhesion between the epoxy-amine polymer and the aluminum substrate. Adhesion will be characterized by a standardized test and related to the properties of the interphase by various techniques. The aging of DGEBA-anime/aluminum system have been done during this study. During the aging, destructive and non-destructive tests were carried out in order to have a follow-up on the properties of interfaces and interphases of these bonded joints. The results were correlated in order to be able to use an in situ non-destructive testing to prevent the rupture at the interphase/interface between the adhesive and the substrate

This thesis presents a study of the preparation and characterisation of microgels (MGs) and microgel-based systems which contain a high proportion of primaryamine groups. This is carried out with the aim of being used as the precursor materials for the development of an enzyme responsive system. The particle preparations discussed in this thesis begin with a particle dispersion prepared by a polymer-polymer interaction between partially oxidised dextran (Dexox) and poly(allylamine)(PA) or poly(vinylamine) (PVAM). The particle dispersions did show good tunability of properties by altering certain variables, such as extent of oxidation which resulted in the largest  -potential change with pH. However, these particles were not viable for further work as the largest swelling ratio by volume, Q value measured was only around 1.25, not sufficient for a pH responsive property swelling change (e.g. fluid-to-gel transition or drug delivery). MG particles were prepared using a non-aqueous dispersion polymerisation of Nvinylformamide (NVF), glycidylmethacrylate (GMA) and a crosslinker, 2-(Nvinylformamido)ethyl ether (NVEE). The PNVFx-GMAy-NVEEz particles were then hydrolysed to expose the primary amine groups in the resulting PVAMx-GMAy-BEVAMEz core-shell MGs. The shell, made up of GMA and NVF prevented hydrolysis taking place on the inside of the MGs, resulting in a PVAM rich shell. These hydrolysed MGs were cationic at low pH and were shown to have polyampholyte behaviour, caused by hydrolysis of some of the GMA groups. The inclusion of the NVEE crosslinker led to increased integration of the GMA and NVF into one homogenous phase in the shell and prevented hydrolytic fragmentation. The final system studied here concerns the macroscopic gel formation between the amine-rich MGs, poly(vinylamine-co-bis(ethyl vinylamine)ether) (PVAMBEVAME)and Dexox. These mixed dispersion gels were prepared and characterised. The MGs were externally crosslinked with the Dexox in order to form an elastically effective network. This was done by forming imine bonds by reaction between the primary amine groups present on the MGs and the aldehyde groups of the Dexox. These networks displayed high storage modulus (G’) and yield strains(*) of up to 140% and the G’ values for the MG-Dexox gels increased with mass ratio (MR) of Dexox to MG. The yield strains determined from rheology remained high (~125%) with increased MR. As the imine bonds formed were not reduced, they became unstable at low pH. This was exploited in order to investigate pH-triggered gel disruption of the network. This work demonstrates that new MG/aldehyde mixtures form ductile and versatile colloidal gels and our new method provides a route to increasing ductility of hydrogels containing MG particles. This research has led to the formation of amine rich MGs, as well as an injectable gel system. These materials are well placed to be developed for enzyme responsive materials in the future.

No description available.