Thermomonospora curvata is a thermophilic actinomycete hylogenetically related to Thermobifida fusca that produces extracellular hydrolases capable of degrading synthetic polyesters. Analysis of the genome of T. curvata DSM43183 revealed two genes coding for putative polyester hydrolases Tcur1278 and Tcur0390 sharing 61% sequence identity with the T. fusca enzymes. Mature proteins of Tcur1278 and Tcur0390 were cloned and expressed in Escherichia coli TOP10. Tcur1278 and Tcur0390 exhibited an optimal reaction temperature against p-nitrophenyl butyrate at 60°C and 55°C, respectively. The optimal pH for both enzymes was determined at pH 8.5. Tcur1278 retained more than 80% and Tcur0390 less than 10% of their initial activity following incubation for 60 min at 55°C. Tcur0390 showed a higher hydrolytic activity against poly(ε-caprolactone) and polyethylene terephthalate (PET) nanoparticles compared to Tcur1278 at reaction temperatures up to 50°C. At 55°C and 60°C, hydrolytic activity against PET nanoparticles was only detected with Tcur1278. In silico modeling of the polyester hydrolases and docking with a model substrate composed of two repeating units of PET revealed the typical fold of α/β serine hydrolases with an exposed catalytic triad. Molecular dynamics simulations confirmed the superior thermal stability of Tcur1278 considered as the main reason for its higher hydrolytic activity on PET.:Introduction; Materials and methods; Results; Discussion

Auf Grundlage der beiden Monomere (2,2-Bis(hydroxymethyl)propansäure (1) und 4,4-Bis(4-hydroxyphenyl)valeriansäure (2)) wurden hochverzweigte Polyester synthetisiert. Durch Verwendung von zwei-, drei-, vier- und sechsfunktionalen Kernmolekülen konnte die strukturelle Vielfalt der hochverzweigten Polyester erhöht werden. Abmischungen auf der Grundlage zweier Polyole (Polyether- bzw. Esterdiol) mit verschiedenen hochverzweigten Polyestern wurden hinsichtlich ihrer Mischbarkeit mittels DSC- und DMA-Messungen sowie rheologisch, mittels temperaturabhängiger IR-Spektroskopie, hinsichtlich ihrer Oberflächenspannung und mittels temperaturabhängiger AFM-Messungen bzw. SAXS-Messungen charakterisiert. DSC und DMA-Messungen des Glasübergangszustandes der Abmischungen gaben Hinweise, dass hochverzweigte Polyester unterschiedlicher Strukturen mit den Polyolen auf molekularer Ebene mischbar sind. Die hochverzweigten Polyester P1 und P1-PEG400 verbesserten die Verarbeitungseigenschaften eines geschlossenzelligen PU-Hartschaumstoffes. Durch die Hochfunktionalität der hochverzweigten Polyester erfolgte das Aushärten des Schaumstoffes schneller, wobei überraschenderweise das "Fließen" des Schaumstoffes gleichzeitig verbessert werden konnte. Durch den Zusatz der genannten hochverzweigten Polyester zu dem Polyetherpolyol konnte die Viskosität gesenkt werden, was die Fließeigenschaften des Schaumstoffes verbessert. Die Schaumstoffe zeigen weiterhin verbesserte mechanische Eigenschaften.

Olestra is, a sucrose polyester, a noncaloric fat substitute, made from sucrose and several fatty acid esters. It has been approved by the FDA as a food additive used in preparing low-fat deep-frying foods such as savory snacks. Available literature on olestra was evaluated that had both positive and negative connotations. Clinical trials in numerous species of animals including humans were conducted to determine if olestra would affect the utilization and absorption of macro- and micronutrients; the effects of olestra on growth, reproduction, or its toxicity were also examined. The roles of olestra as a fat substitute, how it could effect on humans and the environment, and the potential impacts from its use in large amounts were assessed. Olestra can be removed from the environment by aerobic bacteria and fungi which may be isolated from activated sludge and soils.

Yrkesfiskare utsätts dagligen för tufft fysiskt arbete och hårt klimat. Att hålla sig varm och torr är ett stort problem. Samtidigt som det yttre plagget är helt tätt mot de yttre påfrestningarna, släpper plagget inte igenom den ånga och fukt som kroppen skapar vid ett fysiskt krävande arbete. Varför det är av största vikt att den inre beklädnaden skapar en så god komfort som möjligt. Genom ett samarbete med företaget Grundéns, som tillverkar PVC belagda yrkeskläder för olika yrkesgrupper, har denna studies ämnesbakgrund tagits fram. Studien belyser vilka komfortegenskaper och de material som lämpar sig bäst för kroppsnära beklädnad för yrkesfiskare i ett varierat väderklimat. Studien tar upp viktiga egenskaper som att leda bort fukt från kroppen och isolering mot de tuffa yttre påfrestningarna som yrkesfiskare i Alaska utsätts för. Även den upplevda känslan av materialets komfort tas i hänseende. För att få förståelse för materialen har en litteraturstudie gjorts som sedan stärkts med bland annat simulerade tester av materialen. Allt för att hitta en lösning på problemet med att skapa ett så komfortabelt kroppsnära klimat som möjligt för den yrkesaktiva fiskaren. Utifrån målgruppens behov har studien visat att en blandning av 2/3 ull och 1/3 polyester blir den lösnings som uppfyller de krav som ställs på materialets egenskaper. Ullens förmåga att isolera och värma trots en viss mängd fukt i fibern samt polyesterns styrka och förmåga att leda ut den inre vätan är egenskaper som tillsammans skapar det bästa materialet för att lösa problemet. / Program: Textil produktutveckling och entreprenörskap

Snart kan alla göra privata rymdresor. Då detta är en helt ny äventyrsindustri uppstår också helt nya krav på de kläder som kan användas vid träning och genomförande. Syftet med denna uppsats är att undersöka hur material och dess funktion samt estetiska aspekter kan förenas i ett textilt uttryck avsett för dessa extrema förhållanden. Genom intervjuer med äventyraren och kommande resenären Renata Chlumska, Spaceport Swedens VD Karin Nilsdotter och hållbarhetsansvarig Johan Ward från H&M definierades en kravspecifikation som fick ligga till grund för uppsatsen. Kraven för de kläder som ska bäras under själva rymdresan är ej ännu definierade, varför det i slutsatsen endast redovisas kläder som kan komma att användas vid träningen inför resan. Valet av material och dess funktioner är särskilt viktiga för dessa kläder. Genom intervjuer med lärare på Textilhögskolan och via litteraturstudier fann författarna de material som var optimala för att uppfylla de aktuella kraven. Valet föll på merinoull, polyester, elastan och bambuviskos. Det estetiska uttrycket definierades med inspiration från Star Wars och Star Trek. Uppsatsen presenterar sex produkter med optimalt materialval samt inspiration för det estetiska uttrycket. / Program: Textil produktutveckling och entreprenörskap

La thèse s'inscrit dans le cadre d'un programme de recherche global ayant pour objectif de développer des composites à base de polymères biodégradables. L'objectif est de parvenir à contrôler à la fois la durée de vie ainsi que la fragmentation de ces matériaux. Le programme de thèse porte sur plusieurs aspects : <br/>- l'amélioration de la résilience du polylactide (P(L)LA) par incorporation d'agents modifiants au choc ou de biopolymères à faible module d'Young tels que la poly-epsilon-caprolactone (PCL) et le poly-butylène-succinate (PBS). De plus, deux voies de compatibilisation des mélanges ont été testées, par introduction d'agents de polycondensation ou de monomères photo-réticulants. <br/>- l'étude de la résistance à divers vieillissements climatiques (hydrolyse, oxydation thermique et photo-vieillissement) des systèmes présentant une bonne résistance au choc. <br/>- le contrôle de la phase de fragmentation des systèmes les plus performants via l'incorporation de catalyseurs d'oxydation.

This dissertation is written in two parts. The first pertains to polycarbonate and polyester synthesis using relatively benign processes. The synthesis of polycarbonates from the coupling of CO2 and epoxides catalyzed by transition metal catalysts has long been studied in the DJD group. The benefits of this process are that it utilizes comparatively benign reagents, can be performed using no extraneous solvent, and is 100% atom efficient. A method potentially useful for achieving more desirable polycarbonate properties is to produce an epoxide A/epoxide B/CO2 terpolymer, thus allowing more fine "tuning" of properties to what one may desire while simultaneously influencing relative epoxide reactivity to potentially increase catalytic turnovers. Specifically, the coupling of propylene oxide and cyclohexene oxide with CO2 to yield a random copolymer with tunable properties has been studied via a Fineman-Ross analysis. Propylene oxide was found to be incorporated into the resultant polymer chain with anywhere from 4-10 times the preference of cylcohexene oxide. Although it has been reported as early as 1969, the copolymerization of epoxides and cyclic anhydrides catalyzed by transition metal complexes to yield polyesters via a chain-growth mechanism has recently gained much attention. This robust method of polyester synthesis can utilize rather inexpensive reagents to synthesize an array of polyester products which have a wide range of Tg values (-30 degrees C ? 90 degreesC), achievable through simple monomer selection. The second part of this dissertation deals with the kinetic study of ligand substitution from manganese carbonyl metal fragments. Some time ago it was postulated that complexes of the (Cp)M(CO)2L variety undergo ligand substitution via a associative mechanism allowed by a haptotropic eta5-eta3 shift in the eta5 ligand. Through kinetic studies and theoretical modeling, an approximate activation energy barrier of ~34 kJ/mol has been calculated for the ring slip of (2,5-dimethylpyrrole)Mn to occur. Additionally, further kinetic studies were performed in which Tp, a ligand electronically similar to Cp, was compared to MnCp complexes.

Oligomers of soft and hard segments of unsaturated polyesters (UPE) were synthesized in two steps of esterification. For the hard segment, isophthalic acid was first reacted with 1,2-propanediol, then maleic anhydride was added for further esterification. For the soft segment, diethylene glycol was used to replace 1,2-propanediol. Oligomers of soft and hard segments were blended in different ratios, and then cured with various amount of styrene. Dynamic mechanical and the stress-strain properties of these cured UPEs were evaluated. The results indicated that both stress and strain were above the criteria of the inhibitors when the amount of hard segment oligomer was 30, 60 or 70 wt% of UPE, and the added styrene was 35 or 45 phr relative to UPE. The formula of 30 wt% hard segment, 70 wt% soft segment, and 45 phr styrene was selected for the following studies. Tetraethyl orthosilicate (TEOS) and poly(dimethyl siloxane) were incorporated into the uncured UPE resins via sol-gel process. Then fillers and 5, 10, 15, 20 or 30 wt% of magnesium hydroxide were blended with UPE resins and cured. Self-extinguished phenomenon was observed in the erosion tests when the amount of magnesium hydroxide was equal or higher than 15 wt% relative to UPE. After 101 days of nitroglycerin migration experiments, the migration rate and amount were significantly reduced for these filled specimens compared with the current formula of inhibitors. In addition, 2.5 or 5 phr of phenyl triethoxysilane (PhTES) relative to UPE was added together with TEOS to study the physical properties of the organic-inorganic hybrid materials. When the amount of PhTES was 2.5 phr, it was found that the miscibility between inorganic and organic components improved, and their stress- strain properties also satisfied the criteria of the inhibitors.

N-Thiolated beta-lactams are a new class of anti-MRSA and anti-Bacillus agents that have recently been reported by our laboratories. From previous studies performed in our laboratories, it is believed that the N-thiolated beta-lactams exert their antimicrobial activity through a unique mode of action that is completely unlike that of classical beta-lactam antibiotics. In the first chapter of this dissertation, a review of previously prepared N-thiolated beta-lactam analogues and their mode of action is presented. In the second chapter, the synthesis of seven different C3-oxygenated derivatives is described. These analogues were tested for antibacterial activity against Staphylococcus aureus, nine different strains of MRSA, and seven different species of Bacillus. The results of the antibacterial testing will be discussed in relation to the differences in the structures of the analogues. In chapter 3, the design and synthesis of two new, functionalized caprolactone monomers are presented. FTSThese monomers were subsequently cooligomerized with epsilon-caprolactone, as described in chapter 4. N-thiolated beta-lactams were attached to the functionalized oligomers. These antibiotic containing oligomers were then screened for activity against MSSA, MRSA, and Bacillus. The results of these biological tests and their implications for future experiments are discussed.

No description available.