Dissertationen: „Oligomery“

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Sun, Xiaohua. „Synthesis and properties of monodisperse oligomer-substituted calix[4]arene assemblies and related oligomers“. HKBU Institutional Repository, 2006. http://repository.hkbu.edu.hk/etd_ra/706.

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Fučík, Jan. „Analýza látek uvolněných z kompozitního zubního materiálu“. Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444545.

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This master's thesis deals with a present problem of alternative dental fillings, which should replace amalgam fillings. Although there are health concerns about these alternative materials, especially resin composite fillings raise concerns, because they release potentionally harmful substances into the oral cavity. Accordingly even this medical device subjects various tests before releasing to the commercial market and one of these tests was carried out according to ČSN EN ISO 10993 and available scientific literature in the experimental part of this thesis. The amalgam controversy, substances used for manufacturing of resin dental fillings and analytical methods are described in the theoretical part of the thesis. In the experimental part of the thesis, 30 days long cumulative extraction experiments were carried out into various extraction mediums in order to assess suitability of new dental resin filling from ADM, a.s. by comparison with commercially available dental material from company GC EUROPE N.V. These samples were analysed by LC-MS and the amount of eluted substances from dental composites to extraction medium was quantified.

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Cerf, Emilie. „Unraveling Alzheimer's disease: insight into the influence of apolipoprotein E isoforms on Abeta aggregation“. Doctoral thesis, Universite Libre de Bruxelles, 2011. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209880.

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Nowadays, the emerging role of amyloid-β peptide (Aβ) oligomers in Alzheimer’s disease (AD) is widely accepted, putting aside the old idea that fibrils are the primary entities responsible for the onset of the disease. Recent studies indeed show that the level of soluble Aβ oligomeric forms better correlates with the progression of the disease than the level of fibrillar forms.

Using conditions which yield characteristic Aβ42 oligomers or fibrils, we studied the secondary structure of these species by ATR (attenuated total reflection)-FTIR (Fourier transform infrared) spectroscopy. Whereas fibrillar Aβ was organized in a parallel β-sheet conformation, oligomeric Aβ displayed distinct spectral features attributed to an antiparallel β-sheet structure. Antiparallel β-sheet structure may thus be a structural signature of oligomeric Aβ. Moreover, we noted striking spectral similarities between Aβ oligomers and a bacterial pore-forming protein, OmpF.

Apolipoprotein E (apoE) isoforms are strongly linked to Alzheimer’s disease, with the E4 isoform being the most recognized genetic risk factor so far. Nevertheless, the involvement of apoE4 in AD remains confusing. We evaluated the influence of apoE isoforms on Aβ aggregation in vitro. Comparing Aβ controls with Aβ incubated either with the apoE3 or apoE4 isoform, we observed a sharp reduction of the Aβ fibrillar content, whereas the oligomeric content was increased upon incubation with the pathological isoform apoE4. These data suggest that apoE4 binds and blocks Aβ in its oligomeric conformation, inhibiting further formation of less toxic fibrillar forms of Aβ. The enhanced interaction of apoE4 with Aβ oligomers could arise from its reported unique propensity to form a molten globule state, unlike the other isoforms of apoE. While previous studies mostly correlated E4 with fibrils, our data underline a correlation between apoE4 and Aβ oligomers. Our work reconciles apoE4 with the new amyloid cascade hypothesis and brings support to studies whose therapeutic strategy aims at designing inhibitors of the apoE/Aβ interaction./

Le rôle central des espèces oligomèriques du peptide amyloïde bêta (Aβ) dans la maladie d’Alzheimer est de plus en plus reconnu actuellement, mettant de côté l’ancien concept selon lequel les espèces fibrillaires sont les entités responsables du développement de la maladie. Des études récentes montrent en effet que le taux d’oligomères semble bien mieux corrélé à la progression de la maladie que le taux de fibrilles.

A l’aide de protocoles bien établis permettant de former des oligomères ou des fibrilles d’Aβ42 in vitro, nous avons étudié la structure secondaire de ces espèces par spectroscopie infrarouge en réflexion totale atténuée. Alors que les fibrilles présentaient une conformation en feuillets β parallèles, les oligomères quant à eux, ont révélé des caractéristiques spectrales distinctes, attribuées à du feuillet β antiparallèle. Cette structure en feuillets β antiparallèles pourrait donc représenter une signature structurale typique des espèces oligomèriques d’Aβ. De plus, nous avons observé de frappantes similarités spectrales entre les oligomères d’Aβ et une protéine bactérienne formant des pores, l’OmpF.

Les isoformes de l’apolipoprotéine E (apoE) sont fortement impliquées dans la maladie d’Alzheimer et plus particulièrement, l’isoforme E4 qui est actuellement reconnue comme étant le plus important facteur de risque d’origine génétique. Néanmoins, le rôle précis joué par l’apoE4 dans la maladie est encore mal connu. Nous avons étudié l’influence des isoformes de l’apoE sur l’agrégation du peptide amyloïde in vitro. En comparant des échantillons contrôle d’Aβ avec des échantillons incubés en présence d’apoE3 ou d’apoE4, nous avons observé une nette réduction de la quantité de fibrilles ainsi qu’une augmentation concomitante de la proportion d’oligomères lors de l’incubation avec l’isoforme pathologique E4. Ces résultats suggèrent que l’apoE4 interagit avec Aβ et le bloque dans sa conformation oligomèrique, inhibant ainsi le processus d’agrégation et la formation de fibrilles, espèces moins toxiques. Cette plus forte interaction entre l’apoE4 et les oligomères d’Aβ pourrait s’expliquer par la propriété unique de l’apoE4 à former un état intermédiaire ‘molten globule’, ce qui n’est pas le cas des autres isoformes. Tandis que d’anciennes études ont corrélé l’apoE4 principalement avec les fibrilles, nos résultats mettent en évidence un lien entre l’apoE4 et les oligomères d’Aβ, respectivement l’isoforme pathologique et les espèces les plus toxiques du peptide. Ce travail réconcilie donc l’apoE4 avec la nouvelle hypothèse de la « cascade amyloïde » et soutient les études thérapeutiques visant à mettre au point des inhibiteurs spécifiques de l’interaction apoE/Aβ.

Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished

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Čižas, Paulius. „Beta amiloido sąveika su žiurkės neuroninėmis ir mikroglijos ląstelėmis: eksperimentiniai tyrimai in vitro“. Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120918_151511-32900.

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Tikslas. Ištirti įvairaus oligomerizacijos laipsnio Aβ1-40 ir Aβ1-42 peptidų agregatų poveikį smegenėlių ląstelėms ir išaiškinti toksinio veikimo mechanizmus. Uždaviniai: 1.Įvertinti Aβ1-40 ir Aβ1-42 monomerų, oligomerų ir fibrilių poveikį neuronų-glijos ląstelių kultūros gyvybingumui. 2.Nustatyti ryšį tarp Aβ1-42 oligomerų toksiškumo ir dydžio. 3.Ištirti Aβ1-42 oligomerų poveikį neuronų ir mikroglijos ląstelių plazminės membranos įtampos pokyčiams ir įvertinti, kokią reikšmę Aβ1-42 oligomerų sukeltoje neuronų žūtyje turi išorinio kalcio koncentracija, NMDA receptorių ir endocitozės aktyvumas. 4.Nustatyti Aβ1-42 oligomerų poveikį smegenėlių kultūrai, papildytai J774 makrofagais 5.Nustatyti Aβ1-42 oligomerų poveikį mitochondrijų oksidacinio fosforilinimo sistemai. Mokslinis naujumas Šiame darbe nustatytas ryšys tarp Aβ1-42 oligomerų dydžio ir toksiškumo neuronams. Pirmą kartą parodyta, kad maži (toksiški) Aβ1-42 oligomerai (1–2 nm), koncentracijose, kurios gali susidaryti smegenyse patologinėmis sąlygomis, yra toksiški ląstelių kultūroje esantiems neuronams, tačiau nekeičia kitų, ląstelių kultūroje esančių, ląstelių gyvybingumo (mikroglijos ir astrocitų). Pirmieji išsiaiškinome, kad maži ir dideli Aβ1-42 oligomerai gali sukelti neuronų žūtį skirtingais mechanizmais: maži tiesiogiai veikdami neuronus, o dideli veikdami per glijos ląsteles. Mūsų tyrimai atskleidė iki šiol neaprašytą reiškinį, kad maži Aβ1-42 oligomerai gali sąlygoti ne tik neuroninių ląstelių žūtį, bet ir jų... [toliau žr. visą tekstą]
Objective and tasks. The aim of this study is to investigate the effects of Aβ1-40 and Aβ1-42 peptide aggregates at various degrees of oligomerization on cultivated neurons of brain cells and their toxic mechanisms. 1.To investigate the effect of various Aβ1–40 and Aβ1-42 aggregates on the viability of neuronal-glial cell cultures. 2.To determine the relationship between the toxicity of Aβ1-42 oli-gomers and their size. 3.To analyze the effect of Aβ1-42 oligomers on membrane potential of neuronal and glial cells. To assess the effect of extracellular Ca2+ concentration, NMDA receptors and activity of endocytosis on neu¬ronal death caused by Aβ1-42 oligomers. 4.To determine the effect of Aβ1-42 oligomers (4–6 nm in size) on neurons in CGC cultures with added macrophages J774 cells. 5.To determine the effect of Aβ1-42oligomers on respiration of isolated brain mitochondria. Scientific novelty This study determined the relationship between size of amyloid and its toxicity to neurons. For the first time it was shown that small Aβ1-42 oligomers of the size 1–3 nm were toxic to neurons in cell cultures at the concentrations which occur in brain under pathological conditions. However, they did not affect the viability of other cells (microglia and astrocytes) present in the cell cultures. For the first time it has been shown that small and large Aβ1-42 oligo-mers can cause neuronal death by different mechanisms: small oligomers by affecting neurons directly, and large oligomers... [to full text]

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Wattebled, Laurent. „Oligomeric surfactants as novel type of amphiphiles : structure - property relationships and behaviour with additives“. Phd thesis, Universität Potsdam, 2006. http://opus.kobv.de/ubp/volltexte/2007/1285/.

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The properties of a series of well-defined new surfactant oligomers (dimers to tetramers)were examined. From a molecular point of view, these oligomeric surfactants consist of simple monomeric cationic surfactant fragments coupled via the hydrophilic ammonium chloride head groups by spacer groups (different in nature and length). Properties of these cationic surfactant oligomers in aqueous solution such as solubility, micellization and surface activity, micellar size and aggregation number were discussed with respect to the two new molecular variables introduced, i.e. degree of oligomerization and spacer group, in order to establish structure – property relationships. Thus, increasing the degree of oligomerization results in a pronounced decrease of the critical micellization concentration (CMC). Both reduced spacer length and increased spacer hydrophobicity lead to a decrease of the CMC, but to a lesser extent. For these particular compounds, the formed micelles are relatively small and their aggregation number decreases with increasing the degree of oligomerization, increasing spacer length and sterical hindrance. In addition, pseudo-phase diagrams were established for the dimeric surfactants in more complex systems, namely inverse microemulsions, demonstrating again the important influence of the spacer group on the surfactant behaviour. Furthermore, the influence of additives on the property profile of the dimeric compounds was examined, in order to see if the solution properties can be improved while using less material. Strong synergistic effects were observed by adding special organic salts (e.g. sodium salicylate, sodium vinyl benzoate, etc.) to the surfactant dimers in stoichiometric amounts. For such mixtures, the critical aggregation concentration is strongly shifted to lower concentration, the effect being more pronounced for dimers than for analogous monomers. A sharp decrease of the surface tension can also be attained. Many of the organic anions produce viscoelastic solutions when added to the relatively short-chain dimers in aqueous solution, as evidenced by rheological measurements. This behaviour reflects the formation of entangled wormlike micelles due to strong interactions of the anions with the cationic surfactants, decreasing the curvature of the micellar aggregates. It is found that the associative behaviour is enhanced by dimerization. For a given counterion, the spacer group may also induce a stronger viscosifying effect depending on its length and hydrophobicity. Oppositely charged surfactants were combined with the cationic dimers, too. First, some mixtures with the conventional anionic surfactant SDS revealed vesicular aggregates in solution. Also, in view of these catanionic mixtures, a novel anionic dimeric surfactant based on EDTA was synthesized and studied. The synthesis route is relatively simple and the compound exhibits particularly appealing properties such as low CMC and σCMC values, good solubilization capacity of hydrophobic probes and high tolerance to hard water. Noteworthy, mixtures with particular cationic dimers gave rise to viscous solutions, reflecting the micelle growth.
Die Eigenschaften einer Reihe gut definierter neuer oligomerer Tenside (von Dimeren bis zu Tetrameren) wurden untersucht. Strukturell bestehen diese oligomeren Tenside aus einfachen monomeren kationischen Tensidfragmenten, die über die hydrophile Kopfgruppe (Tetraalkyl-Ammoniumchlorid) durch „Spacer“-Gruppen unterschiedlicher Natur und Länge miteinander verbunden/gekoppelt sind. Die Eigenschaften dieser kationischen oligomeren Tenside in wässriger Lösung wie Löslichkeit, kritische Mizellbildungskonzentration und Oberflächenaktivität, Mizellgröße und Aggregationszahl werden in Bezug auf die zwei neuen molekularen Variabeln (d.h. dem Oligomerisationsgrad und der Spacer-Gruppe) untersucht, um Struktur-Eigenschafts-Beziehungen abzuleiten. Die Erhöhung des Oligomerizationsgrads verringert stark die kritische Mizellbildungskonzentration (CMC). Eine kurze Spacer-Länge oder ein erhöhte Hydrophobie des Spacers erniedrigt die CMC ebenfalls, aber in einem geringeren Umfang. Die gebildeten Mizellen sind relativ klein und ihre Aggregationszahl nimmt mit zunehmendem Oligomerisationsgrad ab, genau wie mit zunehmender Spacerlänge oder sterischer Behinderung. Außerdem wurden Pseudo-Phasendiagramme für die Gemini-Tenside in komplexen Systemen, nämlich in inversen Mikroemulsionen untersucht. Auch hier zeigt die Spacer-Gruppe einen großen Einfluß auf das Tensidverhalten. Weiterhin wurde der Einfluss von Zusätzen auf das Eigenschaftsprofil der dimeren Tenside untersucht. Starke Synergien wurden beobachtet, wenn man spezielle organische Anionen (z.B. Natriumsalicylat, Natriumvinylbenzoat, etc.) zu den dimeren Tensiden in stöchiometrischen Mengen hinzugibt. Für solche Mischungen wird die Mizellbildungskonzentration stark zu niedrigen Konzentrationen verschoben, wobei der Effekt für die Dimere ausgeprägter als für die analogen Monomere ist. Eine Verringerung der Oberflächenspannung wird ebenfalls erreicht. Gemini-Tenside mit geeigneten Spacer-Gruppen bilden nach Zugabe ausgewählter organischer Anionen viskoelastische Lösungen, selbst wenn die dimeren Tenside nur über relativ kurz Alkylketten verfügen. Dies wurde mittels rheologischer Messungen gezeigt. Dieses Verhalten resultiert aus der Bildung langer Zylinder-Mizellen aufgrund der starken Wechselwirkung der Anionen mit den kationischen Tensiden, die die Krümmung der mizellaren Strukturen verringern. Es wurde auch festgestellt, dass das assoziative Verhalten durch die Dimerisation erhöht wird. Für ein gegebenes Gegenion kann die Spacer-Gruppe den verdickenden Effekt verstärken, in Abhängichkeit von seiner Länge und Hydrophobie. Als weitere Zusätze wurden entgegengesetzt geladene Tenside wurden mit den kationischen Dimeren kombiniert. Einige Mischungen mit dem käuflichen anionischen Tensid SDS bilden Vesikel in Lösung. Mit Blick auf diese katanionischen Mischungen wurde ein neues anionisches Gemini-Tensid, das auf EDTA basiert ist, synthetisiert und charakterisiert. Der Syntheseweg ist relativ einfach und das Tensid zeigt interessante Eigenschaften wie niedrige CMC- und scmc-Werte, gute Solubilisierungskapazität von hydrophoben Substanzen und hohe Toleranz gegen hartes Wasser. Mischungen dieses anionischen Tensids mit bestimmten kationischen Dimeren bilden visköse Lösungen, was ein starkes Mizell-Wachstum widerspiegelt.

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Skirka, Šarūnas. „Trinties porų, modifikuotų fluoro oligomerais, tyrimas kintamos apkrovos sąlygomis“. Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050607_110131-73271.

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In diesem Bericht wurde ein Übersicht über den Einfluss auf die Eigenschaften eines Reibungspaars, das Prüfungsverfahren mit Wechselbelastung, hydraulische Flüssigkeiten, die in den modernen Hydrauliksystemen eingesetzt werden, gemacht. Theoretisch wurde die Bewertungsmethodik des Verschleißes des Schiebers nach dem Volumen des verschlissenen Materials begründet, die Hertzsche Pressung und ihre Verteilung in der Kontaktzone berechnet. Die tribologischen Prüfungen wurden an der Technischen Universität Hamburg- Harburg mit Prüfstand MPH – 3 durchgeführt. Es wurden die Reibungsverluste während des Starts des Prüfstandes, des Einlaufs der Reibungspaare und der langfristigen Prüfungen festgestellt. Nach den Profilogrammen der Oberfläche des Schiebers wurde das Volumen des verschlissenen Materials berechnet. Es wurde die Bewertung der verschlissenen Oberflächen mithilfe der optischen Mikroskopie durchgeführt. Die Ergebnisse zeigten, dass die fluorhaltigen Oligomere auf die Reibungsverluste während des Starts des Prüfstandes keinen wesentlichen Einfluss ausgeübt hatten. Die in der Einlaufphase modifizierten Oberflächen richteten sich nach der Belastungssteigerung. Der Verschleiß der modifizierten Oberflächen war nach dem Volumen des verschlissenen Schiebermaterials 2,3 ÷ 3,8 kleiner als bei Kontrollprüfkörper.

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Baratha, Nesan Krishna Veni. „Phosphorylated Polyurethane film synthesized from Natural Rubber for flame retardant application“. Thesis, Le Mans, 2015. http://www.theses.fr/2015LEMA1001.

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L’objectif de ce travail a consisté à développer un revêtement polyuréthane (PU) ignifugeant à partir de caoutchouc naturel. Pour ce faire, deux types de diols ont été utilisés. Un oligoisoprène hydroxytéléchélique a été tout d’abord synthétisé et utilisé comme segment souple. Par ailleurs, un second oligomère phosphorylé, dont les groupements phosphonate ou phosphate sont connus pour offrir des propriétés retardatrices de flamme, et possédant une extrémité diol a été réalisé afin de servir d’extenseur de chaine au cours du procédé one shot d’obtention des revêtements. Ces oligophosphonates ou phosphates ont été obtenus quant à eux selon un procédé de polymérisation radicalaire contrôlé de type RAFT à partir de monomères diethyl (acryloyloxymethyl) phosphonate (DEAMP) et 2-acryloyloxyethyldiethylphosphate (ADEP) afin d'accéder à deux gammes de masses strictes (n~13 and n~21 ) et des dispersités étroites (Ð<1.2). Ces polymères ont été entièrementcaractérisés par RMN 1H, 31P, SEC et spectrométrie Maldi TOF et utilisés en synthèse de polyuréthanes selon deux procédés appelés additif et réactif. Les propriétés physicochimiques et mécaniques des matériaux PU synthétisés ont été comparés à ceux de matériaux PU incorporant selon les mêmes approches une petite molécule phosphorylée, afin de traduire les effets spécifiques de ces oligomères. Les revêtements polyuréthane synthétisés ont été caractérisés par FTIR et spectroscopie Raman afin de mesurer la dispersion des oligomères phosphorés au sein de la matrice polymère. En outre, les propriétés physicochimiques et notamment les propriétés ignifugeante ont été évaluées par TGA, DSC et LOI. En complément, les propriétés mécaniques ont été elles aussi évaluées (élongation à rupture, module, dureté et scratch test). Une étude de mapping par spectroscopie Raman a révélé une meilleure dispersion des additifs dans un matériau obtenu selon l’approche réactive, où l’oligomère phosphorylé est lié de manière covalente au squelette du Polyuréthane. De la même façon, cette dispersion apparaîtplus homogène pour l’utilisation d’un oligomère de chaine plus courte (n=13). Les propriétés ignifugeantes ont été démontrées grâce aux caractérisations TGA et DSC où la première étape de décomposition est retardée quels que soient les pourcentages d’oligomères incorporés à la matrice (1, 5 ou 8%). En outre, il s’avère que les mesures LOI démontrent un maximum proche de 30% pour un pourcentage d’oligomère de 8%, valeur très notablement supérieure à celle de l’additif de comparaison. Concernant les propriétés mécaniques, l’incorporation d’oligomères phosphorylés entraîne une augmentation du module et de la dureté et une diminution de la résistance à l’abrasion. Les valeurs d’élongation à rupture sont cependant très similaires, quelles que soient les formulations testées. Néanmoins, ces propriétés apparaissent très supérieures à celles de la matrice standard, démontrant une plus grande efficacité d’oligomères phosphorylés par comparaison avec une petite molécule de type phosphate ou phosphonate. Ces résultats encourageant laissent entrevoir une perspective d’application industrielle de cette méthodologie vers la production de caoutchoucs ignifugeants
The aim of this research was to develop polyurethane (PU) coating from Natural Rubber (NR) presenting Flame Retardant (FR) properties. For this purpose, two kinds of diols were used. Hydroxytelechelic oligoisoprenes were firstly synthesized from Natural Rubber (NR) and used as softsegment. Secondly, diol chain end phosphorylated oligophosphonates or oligophosphates were synthesised that would cater as chain extender during the polyurethane synthesis one shot process. Such Phosphorylated oligomer was synthesized by RAFT polymerization of diethyl (acryloyloxymethyl) phosphonate (DEAMP) and 2-acryloyloxyethyl diethylphosphate (ADEP) monomer. A new trithiocarbonate based RAFT agent was synthesized (2-(dihydroxypropan-2-yloxy)carbonyl trithiocarbonate). This RAFT agent was used to polymerize each monomer with welldefinedmolecular weight and narrow dispersities (Đ<1.2). The polymer was well characterised by 1H, 31PNMR, SEC and Maldi TOF. The oligomers were synthesised with two different chain lengths, n≈13 andn≈21 to be used as additive and reactive FR in polyurethane films. As a reference molecule, a phosphatediol was synthesized to be used as a pendent group in polyurethane synthesis.Polyurethane films were fully characterised using FTIR, Raman spectroscopy, TGA, DSC and LOI.The mechanical properties were furthermore evaluated such as elongation at break, modulus, hardnessand scratch test. Polyurethanes with 1, 5, and 8% w/w of the phosphorylated oligomer were preparedaccording two different pathways so called additive or reactive. The main difference consists in thecovalent attachment of the phosphorylated oligomer to the PU backbone in the reactive pathway whilein the additive process, the oligomers are only physically incorporated in the PU. Raman mappingcharacterizations on the different films reveal a better homogeneous distribution of shortphosphorylated oligomer chains using a reactive pathways compared to the additive pathway as well asthe use of longer chains. Moreover TGA Analysis showed lower decomposition temperature on the firststep and an increased decomposition temperature on the second step of all phosphorylated treatedPUs. This indicates char formation from FR oligomer at lower temperature increases the decompositiontemperature on the second step. LOI measurements showed a maximum of 28.2% with shorterphosphate based oligomers added via reactive pathway at 8%w/w ratio.The mechanical properties of PU with phosphorylated oligomer gave similar elongation at breakbetween additive and reactive pathway. Compared to standard PU, the incorporation of the phosphorylated oligomer showed a decrease in scratch resistance and an increase in modulus and hardness. However, these oligomers (additive and reactive) performed better when compared withsmall molecule added as additive fillers. As a perspective, these phosphorylated oligomers on its own,with low Tg values (≈ -30oC), could be used in dry rubber FR application

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Thamyongkit, Patchanita. „Synthesis and characterization of pyrazine and phthalocyaninatonickel(II) substituted PPV analogous oligomers Synthese und Charakterisierung von Pyrazin- und Phthalocyaninatonickel(II)-substituierten PPV-anologen Oligomeren /“. [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963899929.

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Günter, Roland. „Oligomere und Blockcopolymere auf Fluorenbasis“. [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=971650136.

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Lederer, Kay. „Crystalline assemblies of folded oligomers“. [S.l. : s.n.], 1999. http://ArchiMeD.uni-mainz.de/pub/2000/0036/diss.pdf.

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Doss, Raymond Michael Stoltz Brian M. Dervan Peter B. „Programmable oligomers for DNA recognition /“. Diss., Pasadena, Calif. : California Institute of Technology, 2006. http://resolver.caltech.edu/CaltechETD:etd-09202008-110622.

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Szczypiński, Filip Tomasz. „Ester-based synthetic information oligomers“. Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/289396.

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Wahl, Markus C. „Crystal Structures of RNA Oligomers /“. The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487933245536475.

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Stross, Alexander. „Synthetic H-bonding information oligomers“. Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/12365/.

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The nucleic acids contain chemical information in the form of a sequence of bases. This information content is expressed through sequence selective duplex formation and template directed synthesis. To date, the only programmable artificial information molecules that can truly rival the nucleic acids, in terms of their function, are structurally very similar to the nucleic acids. This thesis describes a synthetic approach to duplex forming hydrogen bonding oligomers that contain information in the form of a sequence of H-bond donor and acceptor groups, in the pursuit of a programmable material that is orthogonal to the nucleic acids. Chapter 1 is a literature review of natural and synthetic information molecules and their applications in nanotechnology, including an overview of the structurally reengineered versions of the nucleic acids, foldamers, template polymerisation and synthetic duplexes. The review highlights the absence of totally synthetic information oligomers, that are orthogonal to the nucleic acids, and Chapter 2 sets out the aims of this thesis, which is to address this gap. Chapter 3 describes the synthesis of oligomers equipped with phenol H-bond donors and phosphine oxide H-bond acceptors. Through cooperative H-bond formation, these oligomers form double stranded complexes, which were characterised by NMR titrations and thermal denaturation experiments. For each additional H-bond there is an order of magnitude increase in association constant. In Chapter 4 it is demonstrated that the modular design for the oligomers in Chapter 3 represents a general strategy to synthetic information oligomers. Two new classes of H-bond acceptor oligomer were synthesised, bearing pyridine and pyridine N-oxide groups. Both these systems also exhibit cooperative duplex formation with H-bond donor oligomers, which were characterised by NMR titration. Chapter 5 examines the ability of mixed sequence 3-mers formed of H-bond donors (phenol) and H-bond acceptors (pyridine N-oxide) to form duplexes in a sequence selective manner. All 8 combinations of donor and acceptor were synthesised, and NMR titrations were used to measure the association constants for each pairwise combination of oligomers. Sequence matched duplexes generally have the highest association constants, but there are some anomalies.

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Anderson, Sally. „Templated synthesis of porphyrin oligomers“. Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/251546.

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16

Forrest, Martin J. „Characterisation of vinyl chloride oligomers“. Thesis, Loughborough University, 1988. https://dspace.lboro.ac.uk/2134/27931.

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A low molecular weight fraction was obtained from a mass polymerised PVC resin by using diethyl ether Soxhlet extraction followed by either preparative gel filtration or solvent fractionation. A gas chromatography - mass spectroscopy (GC-MS) analysis of this fraction revealed that, in addition to vinyl chloride (VC) oligomers, it contained a large number of other compounds, in particular a large concentration of phthalates. By using adsorption liquid chromatography it was possible to remove the phthalates, along with other contaminants having a similar or greater polarity, from the low molecular weight PVC fraction.

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17

Chen, Chen. „SINGLE-MOLECULE ANALYSIS OF ALZHEIMER'S β-PEPTIDE OLIGOMER DISASSEMBLY AT PHYSIOLOGICAL CONCENTRATION“. UKnowledge, 2014. http://uknowledge.uky.edu/chemistry_etds/31.

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The diffusible soluble oligomeric amyloid β-peptide (Aβ) has been identified as a toxic agent in Alzheimer’s disease that can cause synaptic dysfunction and memory loss, indicating its role as potential therapeutic targets for AD treatment. Recently an oligomer-specific sandwich biotin-avidin interaction based assay identified the Aβ oligomer dissociation potency of a series of dihydroxybenzoic acid (DHBA) isomers. Because the sandwich assay is an ensemble method providing limited size information, fluorescence correlation spectroscopy (FCS) was employed to provide single molecule resolution of the disassembly mechanism. Using FCS coupled with atomic force microscopy, we investigated the size distribution of fluorescein labeled synthetic Aβ oligomers at physiological concentrations, and monitored in real time the change of size and mole fraction of oligomers in the presence of dissociating agents or conditions. The higher-order dissociation process caused by DHBA isomers produced no transient oligomeric intermediates, a desirable feature for an anti-oligomer therapeutic. Urea and guanidine hydrochloride, in contrast, produced a linear dissociation with a progressive decrease of size and mole fraction of oligomers. FCS allows the facile distinction of small molecule Aβ oligomer dissociators that do not produce stable potentially toxic oligomeric Aβ intermediates.

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18

Haid, Stefan [Verfasser]. „Functionalized selenophene oligomers and co-oligomers and their application in organic solar cells / Stefan Haid“. Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2012. http://d-nb.info/1028055110/34.

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19

Lommatzsch, Martin. „Hydrocarbons as food contaminants:“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233297.

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The contamination of foods with hydrocarbon mixtures migrating from food contact materials (FCM) was first observed for jute and sisal bags treated with batching oil in the 1990s. Since the millennium, the focus has shifted to printing inks and recycled cardboard packaging as most recognized sources for hydrocarbon contamination from FCM. Mineral oil containing printing inks can either release hydrocarbons directly from the printing of folding boxes into food or indirectly entering the recycling chain of cardboard material by printed products, such as newspapers. The contamination of dry foods with mineral oil hydrocarbons (MOH) from recycled fiber packaging has been reported to reach up to 100 mg/kg [1]. Using LC-GC-FID technique the MOH were categorized into mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH). The molecular mass, which is assumed to be toxicological relevant, is derived from the GC retention times of accumulated MOSH in human tissues and is limited to n C16 to n-C35 [2]. MOSH is the most significant contaminant of the human body reaching 1-10 g per person, which is of particular concern since a formation of microgranulomas (causing inflammatory reactions) in the liver was observed in rats fed with saturated hydrocarbons [3]. Furthermore, some MOAH are assumed to be genotoxic analogous to polycyclic aromatic hydrocarbons [3]. In the latest draft of a German ‘Mineral Oil Regulation’ the following limits for the migration of MOH from recycled fiber are proposed: for MOSH C16-20 4.0 mg/kg, MOSH C21-35 2.0 mg/kg and for MOAH 0.5 mg per kg food [4]. Functional barriers reducing the migration of undesirable compounds from recycled cardboards (such as MOH and other contaminants) could be a part of the solution for this issue. Supporting that approach in this study, the boxes of recycled cardboard featuring a barrier layer on the internal surface or an integrated adsorbent available early in 2014 were investigated for their efficiency in reducing migration of mineral oil hydrocarbons into dry food. A practice-oriented one-year storage test was performed with wheat flakes in seven configurations: a box of virgin fibers, two boxes of unprotected recycled cardboard, three cardboards with barrier layers (a flexo-printed polyacrylate layer, a polyvinyl alcohol coating and a multilayer involving polyester) and a cardboard containing activated carbon. The highest migration of MOH (C16-24) was observed in the boxes of unprotected recycled cardboard (MOSH: 11.4 mg/kg, MOAH: 2.4 mg/kg). Of the three investigated barrier layers only two reduced migration of MOH into food below the limits of the 3rd draft of the German mineral oil ordinance (2014) until the end of shelf life. The cardboard box involving active carbon as adsorbent prevented detectable migration of mineral oil hydrocarbons (<0.1 mg/kg). In the case of virgin fiber, which was virtually free of MOH (<1 mg/kg), migration close to the proposed limits was detected (C16-24, MOSH: 1.5 mg/kg, MOAH: 0.4 mg/kg). Therefore, it has been proven that the transport box (corrugated board) substantially contributed to the transfer of MOH into food. Plastic FCM can also release hydrocarbons, such as polyolefin oligomeric hydrocarbons (POH), into food. These POH are of synthetic nature and are formed during the polymerization process of polyolefins (150 – 3000 mg/kg in granulates of homo/hetero polymers involving ethylene and propylene). This group of synthetic contaminants contain also saturated hydrocarbons (POSH) analogous to mineral oils, but contrary no aromatic hydrocarbons. Further, a significant amount (10 – 50%) of monounsaturated hydrocarbons (POMH) was determined in the oligomeric fraction of polyolefins, which are not detectable in mineral oil products. Therefore, these POMH can be used as a marker for POH migration. A method based on two-dimensional high performance liquid chromatography on-line coupled to gas chromatography (on-line HPLC-HPLC-GC) was developed to enable the separate analysis of saturated, monounsaturated and aromatic hydrocarbons in extracts of packaging materials like polyolefins or paperboard and foods, repectively. It is an extension of the HPLC-GC method for MOSH and MOAH [1] using an additional argentation HPLC column, since normal-phase HPLC on silica gel did not preseparate saturated from monounsaturated hydrocarbons. Further, this method and comprehensive two-dimensional GC (GCxGC) was used to investigate the concentration of different oligomer types in polypropylene (PP) and polyethylene (PE) based sealing layers as well as their corresponding granulates. The analyzed sealing layers contained 180-995 mg/kg POSH and 90-435 mg/kg POMH (C16-35). Only in sealing layers involving low-density PE, oxidized polyolefin oligomers as well as cyclic oligomers (alkylated cyclopentanes and hexanes) have been detected. The transfer of POH (C16-35) from the investigated sealing layers into food can be substantial (>50%) and can reach more than 2 mg per kg food. The level of contamination depends on the oligomer content of the sealing layer, the fat content of the food, the processing temperature and the surface-volume ratio. Hot melt adhesives are widely utilized to glue cardboard boxes used as food packaging material. The analysed raw materials of hot melts mainly consisted of paraffinic waxes, hydrocarbon resins and polyolefins. The hydrocarbon resins, functioning as tackifiers, were the predominant source of hydrocarbons of sufficient volatility to migrate via gaseous phase into dry foods. The 18 hydrocarbon resins analyzed contained 8.2-118 g/kg saturated and up to 59 g/kg aromatic hydrocarbons (C16-24). These synthetic tackfier resins, especially the oligomers ≤C24, have been characterized structurally and migration into food was estimated using a food simulant and by the analysis of real food samples. About 0.5-1.5 % of the potentially migrating substances (C16 24) of a hot melt were found to be transferred into food under storage conditions, which can result in a food contamination of approximately 1 mg/kg food in this case. The order of magnitude depends on the absolute amount of potentially migrating substances from the hot melt, the hot melt surface, contact time, amount and type of foods.

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20

Schneider, Stephen Edward. „Guanidinium linked oligomers : design, synthesis, and applications /“. Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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21

Danzer, Karin. „Die Beteiligung verschiedener alpha-Synuklein Oligomere in der Entstehung der Parkinson Krankheit“. [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-60102.

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22

Al-Aeeb, Ahmed. „The synthesis of 1-butene oligomers with vinyl endgroups and their use in further reactions“. Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/379.

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23

Huang, Da Wei. „Purification and characterization of HP1 oligomers“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0006/MQ44185.pdf.

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24

Conroy, M. „Synthesis of #alpha#, #omega# functionalised oligomers“. Thesis, Lancaster University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240508.

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25

Bewsher, Alan. „New crosslinking methods for functionalised oligomers“. Thesis, Lancaster University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335350.

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26

Li, Junhui. „Studies of hydroxybutyrate oligomers crystalllization behaviour“. Thesis, Open University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417487.

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27

Webb, Simon John. „Mixed metalloporphyrin oligomers as oxidation catalysts“. Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627427.

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28

Swain, Jonathan. „Phenylacetylene oligomers as synthetic information molecules“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/279084.

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Nucleic acids store genetic information in the sequence of nucleobases. Through duplex formation and template directed synthesis, the information stored in nucleic acids determines their three-dimensional structure and function. Nucleic acids are essential molecules for biological processes and have been used in nanotechnology. Modified nucleic acids have been synthesised that still form duplexes and can be tolerated by enzymes, suggesting that it is possible to construct a synthetic system comparable to nucleic acids, orthogonal to nucleic acids. This thesis describes the synthesis of a new class of synthetic information molecule, characterisation of the duplex forming properties, and attempts at templated oligomerisation reactions. The new synthetic information molecule is based on the phenylacetylene oligomer framework developed by Moore and co-workers. Recognition was achieved via a base-pair that is made from a single point high affinity H-bond, with phenol as the H-bond donor (D) and phosphine oxide as the H-bond acceptor (A). The Sonogashira coupling was used to construct the phenylacetylene oligomer backbone. The AA, DD and AD 2-mers were synthesised and complementary 2-mers showed cooperative duplex formation. No intramolecular H-bonding due to folding was observed in the AD mixed 2-mer. Longer oligomers were synthesised using a method of oligomerisation and chromatographic separation by reverse-phase preparatory HPLC. Homo-oligomers up to the 7-mer were isolated and binding studies between complementary all donor, all acceptor homo-oligomers showed increasing duplex stability with each additional recognition unit in the oligomer chain. Oligomers containing both acceptor and donor recognition modules in the same chain were synthesised and NMR dilution studies were used to investigate their ability to fold. Preliminary experiments were carried out to evaluate the ability of these information molecules to template oligomerisation reactions, but when reactions were carried out at concentrations low enough for a significant template effect, no coupling reactions were observed.

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29

Macdonell, Andrew. „Hybrid polyoxometalates : aromatics, asymmetrics and oligomers“. Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6386/.

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This thesis looks at the synthesis of hybrid polyoxometalates (POMs), a family of polyoxometalate compounds grafted to organic moieties. Focussing particularly on the Mn-Anderson hybrid, it looks at new ways of isolating and purifying them and at how the organic component can be used to alter their crystal structure or to link multiple Mn-Anderson cores together to form short oligomer chains. In the first section, two Mn-Anderson hybrids are prepared with large aromatic organic moieties, as a continuation of earlier work looking at how aromatic organic components can influence the structure of Mn-Anderson compounds in the solid state. The two compounds, one based on an anthracene moiety (three fused aromatic rings) and another based on a tetraphenylphthalic moiety (five linked aromatic rings), were both synthesised and crystals were grown of their tetrabutylammonium (TBA) salts. These crystal structures were then analysed and their structure thoroughly described and compared to previous aromatic Mn-Anderson aromatic hybrids. In the second section, a set of methods are presented for the preparation and isolation of asymmetric Mn-Anderson hybrids, where two different organic moieties are linked to the same POM core. These methods use high pressure liquid chromatography (HPLC) and normal liquid chromatography (LC) techniques to separate the mixtures of symmetric and asymmetric products which inevitably result from the synthesis of the asymmetric compounds, formed via both pre- and post-functionalisation techniques, so long as the two organic moieties have sufficiently different hydrophobicity. In order to by-pass the hydrophobicity requirement, a "Universal" asymmetric Mn-Anderson was developed with a free amine and an FMOC-protected amine. This allows for good separation and also gives a product which can be used to form more complex asymmetric compounds via post-functionalisation reaction without further LC purification, and an asymmetric compound with two hydrophilic substituents was synthesised to prove this strategy. All compounds were then fully analysed to confirm the purity of the asymmetric products. Also included is a means to remedy unwanted protonation of TBA Mn-Anderson salts. In the final section, the easy access to asymmetric Mn-Anderson hybrids provided by the previous project is exploited to produce a series of short-chain POM oligomers. A coupling strategy using alkyne and azide Mn-Anderson hybrids was developed, and a series of symmetric and asymmetric building blocks based on these functional groups were synthesised. These were then strategically combined to form a dimer and trimer of Mn-Anderson cores, which could then be further functionalised with alkyne groups and have an additional two Mn-Anderson units added, to give a tetramer and a pentamer. Methods were then developed to successfully purify these oligomers from the excess starting materials used to make them and the compounds analysed to confirm their identity. Size-exclusion HPLC and ion-mobility mass spectrometry (IM-MS) were then performed to gain more information about the structure of these compounds and how they arrange themselves in solution and in the gas-phase.

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30

Cremers, Jonathan. „Electronic communication in heterometallated porphyrin oligomers“. Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:2a9d43e5-1700-4f74-be65-288fdcca1357.

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This thesis presents the synthesis and characterisation of a range of heterometallated porphyrin oligomers and other novel 3D π-conjugated porphyrin nanostructures. Subsequently, their physical organic properties were evaluated which revealed some fascinating electronic properties. Chapter 1 summarises some of the work done in the Anderson group on porphyrin nanostructures and reviews the literature regarding heterometallated porphyrin oligomers. In addition it introduces the main concepts and techniques used in the remainder of the thesis. In Chapter 2 the stabilities of a family of four linear porphyrin pentamer complexes are determined by UV-vis-NIR titrations and analysed using chemical double-mutant cycles which reveal that the binding energy of the copper centre to an axial pyridine ligand is -6.2 kJ mol^-1. Subsequently, the Zn-Zn-Cu-Zn-Zn pentamer is used in the synthesis of a heterometallated 10-porphyrin nanoring. Chapter 3 will describe the investigation of quantum interference phenomena in a bis-copper six-porphyrin nanoring by using EPR spectroscopy. We show that the exchange coupling between two spin centres is increased by a factor 4.5 in the ring structure with two parallel coupling pathways as compared to an otherwise identical system with just one coupling path. In Chapter 4 the syntheses of three isomers of the bis-copper 6-porphyrin nanoring are described. DFT calculations have indicated potential destructive interference phenomena in one of the isomers which would allow for the formation of a molecular system with behaviour resembling that of a hypothetical molecular interferometer. Chapter 5 reports on the template-directed synthesis of a π-conjugated 14-porphyrin nanoball. This bicyclic structure consists of two intersecting nanorings of 6 and 10 porphyrin units. Fluorescence up-conversion spectroscopy experiments demonstrate that electronic excitation delocalises over the whole 3D π-system within 0.3 ps if the nanoball is bound to its templates or within 5 ps if the nanoball is empty. In Chapter 6 the synthesis and characterisation of a D_4h symmetric analogue of the porphyrin nanoball is described. The structure consists of ten porphyrin units arranged as two perpendicular 6-porphyrin nanorings intersecting at two porphyrins. In the synthesis, a combination of magnesium and zinc porphyrins are used which allows for the introduction of a selective demetallation method crucial for accessing this novel structure.

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31

Price, David. „Characterisation of oligomers of vinyl polymers“. Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/26866.

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Large scale Soxhlet extraction and fractional precipitation have been utilised to provide low molecular weight extracts from poly(vinyl chloride) (PVC), polystyrene and polyethylene. These extracts were then resolved into their constituent oligomers by high performance gel permeation chromatography and high performance liquid chromatography.

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32

Barnes, Peter Jeremy. „Oligomeric liquid crystals“. Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241159.

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33

Hall, Grace Louise. „A comparison of ultraviolet, thermal, and microwave polymerized acrylamide terminated polydimethylsiloxane“. Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12172008-063727/.

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34

Wegewitz, Uta Elke. „Genetische und metabolische Regulation von Adiponectin : Resultate von in vitro und humanen in vivo Studien“. Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1606/.

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Übergewicht, Diabetes oder Fettstoffwechselstörungen sind mit erniedrigten Adiponectinspiegeln assoziiert. Eine Modulation des Adiponectins kann durch genetische und metabolische Gegebenheiten erfolgen. Das Ziel dieser Arbeit war die Analyse von Faktoren, welche die Adiponectinspiegel beeinflussen können, sowie eine Charakterisierung der Oligomerverteilung unter verschiedenen metabolischen Bedingungen. In der MeSyBePo-Kohorte waren die zirkulierenden Adiponectinspiegel mit den Promotorpolymorphismen ADIPOQ -11377 C/G und ADIPOQ -11391 G/A im Adiponectingen assoziiert. Im Hinblick auf die metabolischen Faktoren korrelierte Adiponectin eng mit Parametern des Glukose- und Fettstoffwechsels sowie dem Übergewicht. Innerhalb von hyperinsulinämischen euglykämischen Clamps führte eine akute Hyperinsulinämie zu einer Abnahme der Adiponectinspiegel. Adiponectin zirkuliert im Serum als hochmolekulare (HMW), mittelmolekulare (MMW) und niedrigmolekulare (LMW) Spezies. Mit zunehmendem Körpergewicht konnte eine Verlagerung von HMW-Spezies hin zu den LMW-Spezies beobachtet werden. Durch eine moderate Gewichtsabnahme erhöhten sich die Anteile an HMW- und MMW-Adiponectin wieder. Während sich in Abhängigkeit vom Glukosemetabolismus keine Unterschiede in den Gesamtspiegeln ergaben, wurden bei Personen mit normaler Glukosetoleranz signifikant höhere Anteile an MMW-Adiponectin detektiert als bei Personen mit einem gestörten Glukosestoffwechsel. Insgesamt scheinen die HMW- und MMW-Spezies gegensätzlich zur LMW-Spezies reguliert zu werden. Die Arbeit unterstreicht die wichtige Rolle des Adiponectins im Glukose- und Fettstoffwechsel sowie bei einer Adipositas in vivo. Dabei waren Änderungen der Adiponectinspiegel bei Vorliegen von Insulinresistenz und Adipositas stets mit einer Umverteilung der Oligomerfraktionen verbunden. Vor allem die HMW- und MMW-Spezies des Adiponectins scheinen von entscheidender Bedeutung zu sein.
Experimental data suggest that a dysregulation of adiponectin might be involved in the development of the metabolic syndrome. Adiponectin circulates as a variety of multimeric forms and its concentration was found to be decreased in obesity, type 2 diabetes mellitus, and dyslipidemia. Polymorphisms within the adiponectin gene, as well as the metabolic status, may modulate the adiponectin level. The aim of this work was to evaluate factors that may modulate total adiponectin levels as well as the distribution of its multimeric complexes under specific metabolic conditions. In the caucasian MeSyBePo population, serum adiponectin concentrations were associated with two promoter polymorphisms, ADIPOQ -11377 C/G and ADIPOQ -11391 G/A, respectively. Mean serum adiponectin levels were related to obesity, glucose metabolism, and lipid metabolism. Additionally, hyperinsulinemic euglycemic clamps acutely lowered serum adiponectin concentration. Adiponectin circulates in serum as low-, medium-, and high-molecular-weight complexes (LMW, MMW, and HMW, respectively). Adiponectin oligomer composition was related to BMI, with decreased HMW and MMW fractions in case of high BMI levels. According to this, HMW and MMW adiponectin increased after moderate weight reduction. While total adiponectin levels were comparable between patients with type 2 diabetes and control subjects, a reduction of MMW oligomers was observed in patients with impaired glucose metabolism. Finally, these studies all suggested a differential regulation of HMW and MMW species compared to the LMW fraction. The data presented underline the important role of adiponectin within the glucose- and lipid metabolism as well as in obesity. We showed that modulation of total adiponectin levels in case of insulin resistance or obesity are always accompanied with changes of adiponectin oligomer composition. Thereby the HMW and MMW species seem to play a crucial role in affecting metabolic changes.

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35

Hormaza, Angelina. „Gekreuzt konjugierte Oligomere aus Benzolringen und Heterocyclen“. [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969278438.

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36

Mohammed, Nor Hussin Bin. „Telechelic natural rubber oligomers via controlled ozonolysis“. Thesis, Lancaster University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306916.

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37

Förtsch, Sebastian [Verfasser]. „Dithienopyrroles: monomers, oligomers, and polymers / Sebastian Förtsch“. Ulm : Universität Ulm, 2018. http://d-nb.info/1173249710/34.

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38

Hania, Majid I. M. „Studies on polyester networks and their oligomers“. Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388094.

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39

Zhu, Zhixue. „Cyclic oligomers in macromolecular and supramolecular chemistry“. Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272293.

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40

Woodward, Alison Francesca. „Laccase-catalysed depolymerisation of lignin model oligomers“. Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/42457/.

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Laccase-catalysed depolymerisation of lignin offers substantial opportunities to form bio-derived aromatic chemicals. Laccase works with exquisite selectivity to oxidise the 5-5’ and β-5’ linkages in lignin and to cleave the β-O-4’ linkages in the presence of 1-hydroxybenzotriazole (1-HBT). However, the laccase/1-HBT system is inefficient when applied to industrial lignin, and the complexity of the product mixtures hinders rapid optimisation. Therefore, I studied laccase-catalysed oxidation of three synthetic lignin model oligomers, which had well-defined structures, yielded analytically tractable product mixtures, and, thus, permitted faster optimisation. Solvent systems were developed to dissolve the lignin model oligomers and retain laccase activity, which aided mass transfer. Models of “hardwood” (S:G 1:1) and “softwood” (G only) lignin containing nonphenolic β-O-4’ linkages (Angewandte Chemie-International Edition, 54, 258) were oxidised quickly by benzylic carbonyl formation ( > 60% in 24 h), or β-O-4’ bond cleavage. Approximately 25% of the linkages in the “hardwood” (S:G 1:1) oligomer were cleaved in 24 h. A more complex model of “softwood” lignin, containing β-5’, β-O-4’ and 5-5’ phenolic linkages (Green Chemistry, 15, 3031), was oxidised just as rapidly, but reaction products in this case were phenolic dimers that repolymerised. Therefore, I conclude that future bio-production of aromatic chemicals from lignin will depend on the development of improved lignin extraction procedures to allow retention of the β-O-4’ linkages, which will produce more efficient enzymatic depolymerisation.

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41

Tomsett, Michael. „Signal transduction in helical oligomers and polymers“. Thesis, University of Bristol, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.742998.

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42

Crase, Jason L. „Synthesis and Characterization of Ortho-Phenylene Oligomers“. Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1282931679.

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43

Yang, Wenwen. „Synthesis of N-alkyl urea peptoid oligomers“. University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1378197097.

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44

Mathew, Sanyo. „Folding of ortho-phenylene oligomers“. Miami University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1406553741.

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45

Hao, Yu. „Synthesis and conformational studies of beta 2,3-cyclic aminoxy peptides“. Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B36363236.

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46

Clarke, Tracey Michelle, und n/a. „An investigation of polaron, bipolaron and exciton structures in oligothiophenes : a resonance raman and theoretical study“. University of Otago. Department of Chemistry, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070420.150451.

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This thesis presents a spectroscopic and computational study of a variety of substituted oligothiophenes. The purpose of this study was to elucidate the structural properties of their neutral, oxidised and excited states. This was accomplished using a number of spectroscopic methods, including electronic absorption, resonance Raman and fluorescence spectroscopy. Analysis of the data provided by these methods was aided by the application of density functional theory (DFT) to the neutral and charged species, allowing conclusions regarding bond length changes and molecular orbitals to be drawn. Advancing the understanding of the structural properties of conductive materials such as oligothiophenes is important due to their potential application in plastic electronic devices (organic solar cells, field effect transistors and light emitting diodes, for instance) and the need to clarify the charge transport mechanism. The compounds examined in this thesis are primarily based on 3� styryl-substituted terthiophene. Substituted derivatives of this molecule include those with groups on the para position of the phenyl ring or methyl α,α� end caps. Larger ethenyl-aryl groups were also investigated, as were analogous thiophenes and sexithiophenes. Indeed, the 3�-substituted sexithiophenes formed an integral part of this investigation since they rapidly form in the head-to-head orientation from the oxidation and consequent [sigma]-dimerisation of the substituted terthiophenes. DFT calculations on the sexithiophene charged species have indicated the presence of a full polaronic or bipolaronic structural defect in the centre of the thiophene backbone, as defined by the reversal of the CC bond length alternation to create a domain of quinoidal bond sequence. However, the structural defect of the styryl sexithiophenes is more strongly localised than that observed for unsubstituted sexithiophene; indeed, the charged defect appears to be confined by the positions of the styryl substituents. This defect confinement along the thiophene backbone is particularly apparent in the styryl sexithiophene dications. Electronic absorption and resonance Raman spectroscopy have been applied to the oxidation products of the styryl terthiophenes. Only sexithiophene charged species are observed when the α termini are unsubstituted; these include sexithiophene radical cations, [pi]-dimers (a stabilising face-to-face interaction between two radical cations) and dications. The resonance Raman spectra of these charged species are characterised by a very intense symmetrical CC stretching mode of the thiophene inter-ring bonds, which is also evident in the theoretical spectra. The extensive differences between the styryl and unsubstituted sexithiophene dication Raman spectra have been attributed to defect confinement: the strongest Raman band of the unsubstituted sexithiophene dication is due to a vibrational mode localised over the entire sexithiophene backbone while that of the styryl sexithiophenes is localised over the central two thiophene rings - the same area occupied by the confined defect. A combined steady-state and picosecond time-resolved emission study on the styryl terthiophenes revealed that by judicious choice of the para R group in styryl terthiophenes it is possible to tune the nature of the first excited singlet state from [pi],[pi]* to charge transfer character. Charge transfer states may offer possible strategies for solar cells in which charge separation is a key step.

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Lim, Christina Go. „Synthesis and characterization of poly(oxazoline) rotaxanes and literature review on separation, detection and identification of cyclic oligomers in poly(ethylene terephthalate) and poly(c̋aprolactam) /“. This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-01202010-020257/.

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48

Mayes, Benjamin A. „Towards polyhydroxylated nylon and cyclopeptide-cyclodextrin analogues“. Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289367.

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49

Lo, Pik Kwan Peggy. „Synthesis and structure-property relationships of novel multi-[pi] conjugated molecular systems“. HKBU Institutional Repository, 2006. http://repository.hkbu.edu.hk/etd_ra/704.

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50

König, Heinrich Josef. „Silsesquioxane mit oligomeren Käfigstrukturen“. [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=967650496.

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Dissertationen zum Thema „Oligomery“

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