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1
Sansom, C. E. "Computer modelling studies of some regular biopolymers and their interactions." Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375398.
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Gözke, Gözde [Verfasser], and C. [Akademischer Betreuer] Posten. "Electrofiltration of Biopolymers : Spatially Distributed Process Analysis / Gözde Gözke ; Betreuer: C. Posten." Karlsruhe : KIT Scientific Publishing, 2012. http://d-nb.info/1184493111/34.
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Haley, T. M. "Assessment and application of new mass spectrometric techniques to the analysis of biopolymers." Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637201.
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There have been significant advances in instrumentation concerned with the analysis of biopolymers in the last five years. The recent developments have provided physical methods for determining both purity and molecular weight of biopolymers with greater accuracy than by traditional methods. In the separation sciences, capillary electrophoresis has emerged as an invaluable tool for the biochemical analyst. In the spectroscopic world vast improvements in mass spectrometric instrumentation have provided an order of magnitude improvement in sensitivity. This factor, along with the revival of techniques such as laser irradiation and electrospray, (which along with several important discoveries concerning trivial chemistry during sample preparation in the former and realisation of the effect and importance of multiple charging in the latter) now means that the analysis of biopolymers by mass spectrometry is not only feasible but is becoming almost routine. In this thesis, in chapters 1, 2 and 3 the new techniques are described and applied to everyday analytical problems posed to the biochemical analyst in the pharmaceutical industry. In chapter 4 a comparison is made between an established liquid chromatography-mass spectrometry interface and electrospray, using a standard peptide mixture for reference. The importance of traditional methods of protein digestion by enzymes is highlighted in chapter 5, where novel use of an anomeric specific enzyme is made and the products analysed by two different mass spectrometric techniques. Chapter 6 describes the new role that mass spectrometry has claimed in biopolymer analysis by enabling a new protocol to be established in the search for novel pharmaceutical compounds which are both more efficient and more specific in their action.
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Valba, Olga. "Statistical analysis of networks and biophysical systems of complex architecture." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00919606.
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Complex organization is found in many biological systems. For example, biopolymers could possess very hierarchic structure, which provides their functional peculiarity. Understating such, complex organization allows describing biological phenomena and predicting molecule functions. Besides, we can try to characterize the specific phenomenon by some probabilistic quantities (variances, means, etc), assuming the primary biopolymer structure to be randomly formed according to some statistical distribution. Such a formulation is oriented toward evolutionary problems.Artificially constructed biological network is another common object of statistical physics with rich functional properties. A behavior of cells is a consequence of complex interactions between its numerous components, such as DNA, RNA, proteins and small molecules. Cells use signaling pathways and regulatory mechanisms to coordinate multiple processes, allowing them to respond and to adapt to changing environment. Recent theoretical advances allow us to describe cellular network structure using graph concepts to reveal the principal organizational features shared with numerous non-biological networks.The aim of this thesis is to develop bunch of methods for studying statistical and dynamic objects of complex architecture and, in particular, scale-free structures, which have no characteristic spatial and/or time scale. For such systems, the use of standard mathematical methods, relying on the average behavior of the whole system, is often incorrect or useless, while a detailed many-body description is almost hopeless because of the combinatorial complexity of the problem. Here we focus on two problems.The first part addresses to statistical analysis of random biopolymers. Apart from the evolutionary context, our studies cover more general problems of planar topology appeared in description of various systems, ranging from gauge theory to biophysics. We investigate analytically and numerically a phase transition of a generic planar matching problem, from the regime, where almost all the vertices are paired, to the situation, where a finite fraction of them remains unmatched.The second part of this work focus on statistical properties of networks. We demonstrate the possibility to define co-expression gene clusters within a network context from their specific motif distribution signatures. We also show how a method based on the shortest path function (SPF) can be applied to gene interactions sub-networks of co-expression gene clusters, to efficiently predict novel regulatory transcription factors (TFs). The biological significance of this method by applying it on groups of genes with a shared regulatory locus, found by genetic genomics, is presented. Finally, we discuss formation of stable patters of motifs in networks under selective evolution in context of creation of islands of "superfamilies".
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Choudhury, Udit. "Dynamic Mechanical Properties of Cockroach(Periplaneta americana) Resilin." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/40869.
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Resilin is a cuticular protein found in a variety of insects. It can stretch up to 300% of its natural length without any creep or relaxation. Further, it operates across a wide frequency range from 5 Hz in locomotion to 13 kHz in sound production. Both the protein sequence and composition of natural resilin as well as the dynamic mechanical properties vary substantially across species. This suggests that mechanical properties may be evolutionarily tuned for specific functions within an insect. Here, samples of resilin obtained from the tibia-tarsal joint of the cockroach, Periplaneta americana, were tested using a custom built dynamic mechanical analyzer. The material properties in compression are obtained from the rubbery to glassy domain with time-temperature superposition (-2C to 55C) and time-concentration superposition (0 % to 93% ethanol by volume in water). At low frequency the storage modulus was found to be 1.5 MPa increasing to about 5 MPa in the transition zone. The glass transition frequency at 23C in complete hydration was found to be 200 kHz. The data shows that cockroach resilin is less resilient than dragonfly resilin at low frequencies, returning about 79% of the elastic strain energy at 25 Hz compared to 97% for dragonfly resilin. However, at the glass transition (200 kHz) the material returns about 47% of the elastic strain energy compared to 30% in dragonfly (2MHz ). The resilin pad in cockroach is a composite structure, acting as a compressive spring to passively extend the tibia-tarsal joint during cockroach locomotion. Its mechanical properties are more similar to the composite locust pre-alar arm than to the pure resilin dragonfly tendon, suggesting that macroscopic structural influences may be as important as molecular sequence differences in setting properties.<br>Master of Science
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Lee, Samuel H. "The influence of nitrogen and sludge age change in reactor performance and biopolymer production in activated sludge." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91041.
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This study investigated the influence of nitrogen and sludge age change in reactor performance and biopolymer production in activated sludge systems. The qualitative and quantitative analyses of the naturally occurring biopolymers were performed and the results were correlated to sludge a settling characteristic and effluent quality.
In order to obtain the sludge samples for the analyses, two completely mixed, continuous flow activated sludge systems were maintained during this research. Raw wastewater from the Celanese Fiber Plant located at Narrows, Virginia was utilized as the influent. Nitrogen was added in the feed solution as ammonium sulfate. The sludge age was changed from ten to five days for both systems.
Biopolymers were extracted from the sludge floc matrix using pH-adjustment technique followed by centrifugation. The total biopolymer contents were analyzed for protein and carbohydrate concentrations. High molecular weight biopolymers were also analyzed following gel filtration. The sludge settling characteristics were measured in terms of Sludge Volume Index and effluent quality in terms of effluent turbidity.
The results indicated that the relationship between total biopolymer concentrations and sludge settling characteristics is culture specific. No consistent relationship was observed between total biopolymer concentrations and effluent turbidity and/or SVI.
Additional nitrogen in a reactor system promoted production of high protein content biopolymers. However, no significant improvement in effluent quality of the reactor was noticed by the additional nitrogen. Deficiency of nitrogen in a reactor system promoted the production of high carbohydrate content biopolymers. The high concentration of carbohydrate biopolymers seemed to correspond directly to the high effluent turbidity.<br>M.S.
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Kajornatiyudh, Sittiporn. "Bacterial extracellular polymers and flocculation of activated sludges." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/52313.
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The extracellular polymers produced by bacteria play an important role in bacterial aggregation or bacterial flocculation in secondary waste treatment. The mechanisms responsible for this floc formation are thought to be polymer induced adsorption and interparticle bridging among bacterial cells or between bacterial cells and inorganic colloids. The efficiency of the processes following flocculation in the treatment line such as sedimentation, sludge thickening, and sludge dewatering depends on the extent of this bacterial flocculation.
In this research, sludge samples from under various substrate conditions were examined for type, molecular weight, physical characteristics„ and quantity of extracellular polymers so that the general characteristics of the various polymers could be established. An attempt was made to determine if a relationship exists between the state of bacterial aggregation and the polymer characteristics. This research also investigated the sludge physical properties. The effect of various parameters such as pH, divalent cation (mixture and concentration), and mixing (period and intensity) on dewatering properties were studied.
A major goal of this study was to develop a flocculation model for activated sludge. This model could be used to determine if plants can increase the efficiency of waste treatment and sludge thickening and sludge dewatering processes.<br>Ph. D.
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Vase, Ajoy. "The effects of material treatments on the surface properties of polymeric biomaterials." Pomona College, 2007. http://ccdl.libraries.claremont.edu/u?/stc,19.
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This work examines the chemical and physical effects of a material treatment process on the biopolymers PEEK, POM-h, POM-c, PTFE and UHMWPE. The polymers are analyzed physically and chemically using atomic force microscopy, profilometry, scanning electron microscopy, optical microscopy, contact angle measurement, FT infra-red spectroscopy and energy dispersive X-ray spectrometry. PEEK is found to be the most suitable polymer and FT Infra-red spectroscopy an informative analytic tool.
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Paluchová, Natálie. "Vliv biodegradace bioplastů na kvalitu půdy." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449334.
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V poslední době se pozornost polečnosti obrátila k mikroplastům. Jsou produkovány různými odvětvími a šíří se napříč prostředím. Po dlouhou dobu byly považovány za inertní, bez dalšího vlivu na rostliny a jiné živé organismy, avšak jak zjistily nedávné studie, mohly by představovat vážnou hrozbu. Několik vědců, včetně nás, se proto začalo soustředit na jejich transport a transformace v životním prostředí. Většina se však zaměřuje pouze na jejich přítomnost v mořských a sladkých vodách, a proto jejich chování ve vzduchu a půdě zůstává nejasné. Kromě toho byla pozornost soustředěna i na bioplasty. Jsou prezentována jako ekologická alternativa, která má vyřešit všechny dosud zmíněné problémy (a další). Avšak často se zapomíná, že jejich hlavní výhoda může být zároveň nevýhodou. Z tohoto důvodu se tato diplomová práce zaměřuje na negativní účinky spojené s přítomností mikroplastů (konkrétně bioplastu poly-(R)-3-hydroxybutyrátu) v půdě jako jejich běžný receptor. Kombinovali jsme respirometrii, elementární analýzu, termogravimetrii a enzymatické testy, abychom zkoumali fyzikálně-chemické změny v půdě vyvolané přítomností bioplastu. Naše výsledky ukázaly negativní vliv na půdní organickou hmotu a zadržování vody v půdě. V tomto smyslu byl zkoumán i tzv. "priming effect", jelikož docházelo k urychlení a také zpomalení rozkladu půdní organické hmoty. Zaznamenali jsme rozdílný vliv vybraných koncentrací biopolymeru na půdu a také vliv půdních vlastností na průběh degradace. V neposlední řadě zvýšení enzymatické aktivity jasně naznačovalo vliv přítomnosti biopolymeru na mikrobiální komunitu. Na základě takových zjištění jsme došli k závěru, že přidání biopolymeru vede k dlouhodobému dopadu na řadu funkcí půdního ekosystému.
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Raicher, Gil. "Análise econômica da produção de polímeros biodegradáveis no contexto de uma biorefinaria a partir de cana-de-açúcar." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-27092011-155657/.
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Polihidroxialcanoatos são polímeros biodegradáveis, sintetizados por bactérias a partir de fontes de carbono renováveis. Este trabalho se concentra na produção de P3HB a partir de xilose no contexto de uma usina padrão de álcool e açúcar que produz energia através de cogeração, utiliza resíduos agrícolas de cana-de-açúcar e passaria a produzir etanol de segunda geração a partir do bagaço. A produção de PHAs a partir de xilose, hoje descartada, poderá viabilizar a geração de etanol de segunda geração. Variou-se a produtividade (0,28 e 1,11 g/L.h), o preço (R$ 4,50 R$ 9,00), o custo do fermentador (três cenários entre US$ 475 - 3.013 mil) e a capacidade produtiva da planta (dez cenários de 1.000 a 35.000 mil t/ano). As visões de resultado oferecem a margem de contribuição, lucratividade líquida da operação, bem como o ponto de breakeven. Recomenda-se redirecionar parte dos esforços de pesquisa voltados a um aumento do teor de P3HB na célula para a melhoria da produtividade do processo, que é o fator-chave para que o processo se torne economicamente mais atrativo.<br>Polyihydroxyalkanoates are biodegradable polymers, synthetized by bacteria from renewable sources of carbon. This thesis focuses on production of P3HB from xylose in the context of a standard sugar and ethanol plant, cogenerates steam and electrical energy utilizing sugarcane bagasse and agricultural residues. PHAs production from xylose, discarded in most mills nowadays, may enable profitability of 2nd generation bioethanol. Productivity varied from 0,28 to 1,11 g/L.h, and PHB price ranged from R$ 4,50 to R$ 9,00 per kilo. Fermentor cost was studied in 3 scenarios from US$ 475 to 3.013 thousand and the production capacity was analyzed in ten different scenarios, from 1,000 to 35,000 thousand tonnes/year. Result reviews offer contribution margin, net operational profit, as well as breakeven point analysis. Recommended is to redirect part of the research efforts from improving P3HB yields to process productivity improvement, which turned out to be the key factor to economic feasibility.
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Le, Cong Anh khanh. "Complexes d'inclusion de l'amylose : morphogenèse, structure cristalline et relargage de molécules bioactives." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAV033/document.
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L'amylose est un homopolymère quasi-linéaire d'unités glucosyles liées en α(1,4) qui, extrait de l'amidon natif, possède la propriété remarquable de former des complexes cristallins avec une grande variété de petites molécules organiques. Ces complexes sont regroupés sous le terme générique d'amylose V. Nous avons testé la capacité de 120 composés à induire la cristallisation de l'amylose à partir de solutions aqueuses diluées. La morphologie et la structure des cristaux lamellaires formés ont été caractérisés par microscopie électronique en transmission ainsi que par diffraction des électrons et des rayons X. Les données révèlent que les structures de ces complexes peuvent être classées en 10 familles dont 5 sont décrites pour la première fois. Des spectres de résonnance magnétique nucléaire du solide du 13C montrent clairement que l'hélicité de l'amylose V est corrélée à la résonnance du carbone C1 qui se déplace vers les champs faibles lorsque le nombre d'unités glucosyles par tour augmente. Des modèles géométriques préliminaires ont été proposés pour tous les allomorphes, la structure de cristaux de V1-butanol ayant été analysée en détail en combinant des calculs de conformation et d'énergie d'empilement avec un affinement de structure de polymère cristallin classique. Tous les allomorphes contiennent des simples hélices d'amylose d'ordre 6, 7 ou 8 et les molécules invitées peuvent être localisées dans ces hélices, entre elles ou les deux. Chaque type d'allomorphe peut être obtenu avec différents complexants et la conformation de l'hélice d'amylose dépend de la taille du complexant. De plus, un ligand donné est susceptible d'induire la formation de plusieurs allomorphes. Le polymorphisme cristallin de l'amylose serait donc une caractéristique plus générale que ce qui avait été rapporté auparavant. La propension au polymorphisme dépend non seulement de la nature du complexant mais aussi des conditions de cristallisation. Le degré de polymérisation de l'amylose, sa concentration et celle du complexant, la température de mélange ou de cristallisation et la composition du solvant ont un impact significatif sur la formation de cristaux et la structure de l'amylose V. Par ailleurs, nous avons utilisé des complexes avec l'ibuprofène comme modèle afin d'évaluer le potentiel de l'amylose V comme système de délivrance de principes actifs. Différentes fractions d'ibuprofène, probablement corrélées aux positions possibles de la molécule dans le cristal, sont sélectivement relarguées en variant le pH du milieu de dissolution. Puisque le relargage intervient principalement à pH élevé, ces complexes d'inclusion sont donc potentiellement intéressants pour cibler une libération intestinale et pourraient donc améliorer l'effet thérapeutiques de l'ibuprofène<br>Amylose, a mostly linear homopolymer of α(1,4)-linked glucosyl units extracted from native starch, has the remarkable property to form "V-amylose" crystalline complexes with a variety of small organic molecules. We have tested the ability of 120 compounds to induce the crystallization of amylose from dilute aqueous solutions. The morphology and structure of the resulting lamellar crystals were characterized by transmission electron microscopy as well as electron and X ray diffraction. The data revealed that the structures of the complexes could be classified into 10 families, 5 of which were described for the first time. In addition, 13C solid-state nuclear magnetic resonance spectra clearly showed that the helicity of V-amylose was correlated with the resonance of carbon C1 that was shifted downfield with increasing number of glucosyl units per turn. Tentative geometrical models were proposed for all allomorphs and the structure of V1-butanol was analyzed in more details by combining conformational and packing energy calculations with classical crystalline polymer structure refinement. All allomorphs contained 6-, 7- or 8-fold amylose single helices and the guest molecules could be located inside these helices, in-between, or both. Each allomorph could be obtained with different complexing agents and the helical conformation was found to depend on the size of the complexing agent. In addition, a given ligand could induce the formation of several allomorphs, suggesting that the polymorphism of V-amylose crystals is a more general characteristic than what was previously reported. The propensity for polymorphism is not only related to the nature of the complexing agent but also to the crystallization conditions. The degree of polymerization of amylose, its concentration and that of the complexing agent, the temperature of mixing and crystallization, and the solvent composition have a significant impact on the formation and crystal structure of V-amylose. In addition, crystalline complexes prepared with ibuprofen were used as a model to evaluate the potential of V-amylose as a delivery system of bioactive molecules. Different fractions of ibuprofen, likely correlated with the different locations of the guest in the crystal, were selectively released by varying the pH of the dissolution medium. Since the release mainly occurred at high pH, these inclusion complexes appear to be potentially interesting for intestinal targeting and would thus improve the therapeutic effect of ibuprofen
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WERNER, PATRICIA BORBA. "ANALYSIS OF A BIOPOLYMER FOR DEVELOPMENT OF A TOOTHBRUSH." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2009. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=15334@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>O uso indiscriminado de polímeros derivados do petróleo como matériaprima
tem resultado no acúmulo de resíduos de lenta biodegradabilidade nos
aterros sanitários, pois os plásticos convencionais levam cerca de meio século
para serem degradados. Diante desse cenário, o estudo de polímeros derivados de
fontes renováveis, os biopolímeros, é totalmente relevante e, em muitos casos, os
polímeros derivados do petróleo podem ser substituídos por biopolímeros.
Pesquisas apontam a escova dental como um produto ideal para sofrer esta
mudança, por ser um produto de uso pessoal rapidamente descartado e por ser,
geralmente, produzido a partir do polipropileno (PP), polímero que apresenta lenta
biodegradabilidade. Dessa forma, este trabalho multidisciplinar tem como
objetivo o desenvolvimento de um protótipo de escova dental fabricado em
poliuretano derivado do óleo de mamona, bem como a caracterização desse
material a partir de ensaios de absorção de água e de saliva artificial, análise
térmica dinâmico-mecânica (DMTA) e ensaios mecânicos de tração,
estabelecendo uma comparação com o PP. A partir dos ensaios pode-se concluir
que o PU derivado de mamona apresentou absorção de saliva superior à de água e
esta, por sua vez, superior ao PP. Com relação a tração, o PP superou o PU em
todos os aspectos, mostrando-se um material mais resistente e de maior rigidez.
Contudo, concluiu-se que com algumas alterações no design, uma escova
fabricada em PU derivado do óleo de mamona pode alcançar a mesma carga de
ruptura e rigidez estrutural de uma escova convencional.<br>Indiscriminate use of raw materials by various industries such as polymers
from petroleum has been causing an ever-increasing accumulation of slow
biodegrading residue materials in sanitary pits. Many modern life utensils are
made out of conventional plastic that are estimated to take up to half a century to
decompose. In view of this situation, the study of polymers from renewable
sources, the biopolymers, is key in the search for alternatives that may decrease
the damaging effects on the environment. Petroleum based polymers can in many
instances be replaced by biopolymers. Amongst such products, research has been
indicating that toothbrush manufacturing can make use of alternative materials. A
toothbrush is a personal hygiene device that should be used for relatively short
periods. It is commonly made out of polypropylene (PP), a polymer with slow
biodegrading characteristics. This study uses a multidisciplinary approach and its
objective is the development of a toothbrush handle made out of polyurethane
derived from castor oil. Water and artificial saliva absorption, DMTA and traction
experiments were carried out to compare chemical and mechanical properties of
traditional polypropylene and castor oil polyurethane toothbrushes. From the tests
we can conclude that the derivative of castor oil PU showed absorption of saliva
superior to water and also superior to PP. With respect to traction, the PP over the
PU in all aspects and is a material more resistant and more rigid. However, it was
concluded that with some changes in design, a brush made of PU derivative of
castor oil might reach the same tensile strength and structural rigidity of a
conventional toothbrush.
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Vase, Ajoy. "The effect of materials preparation on polymer surfaces." Pomona College, 2007. http://ccdl.libraries.claremont.edu/u?/stc,25.
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This work examines the chemical and physical effects of a material treatment process on the biopolymers PEEK, POM-h, POM-c, PTFE and UHMWPE. The polymers are analyzed physically and chemically using atomic force microscopy, profilometry, scanning electron microscopy, optical microscopy, contact angle measurement, FT infra-red spectroscopy and energy dispersive X-ray spectrometry. PEEK is found to be the most suitable polymer and FT Infra-red spectroscopy an informative analytic tool.
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Zhang, Wei. "Biopolymer Structure Analysis and Saccharification of Glycerol Thermal Processed Biomass." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/71830.
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Glycerol thermal processing (GTP) is studied as a novel biomass pretreatment method in this research with the purposes to facilitate biopolymer fractionation and biomass saccharification. This approach is performed by treating sweet gum particles on polymer processing equipment at high temperatures and short times in the presence of anhydrous glycerol. Nine severity conditions are studied to assess the impact of time and temperature during the processing on biopolymer structure and conversion.
The GTP pretreatment results in the disruption of cell wall networks by increasing the removal of side-chain sugars and lignin-carbohydrate linkages based on severity conditions. After pretreatment, 41% of the lignin and 68% of the xylan is recovered in a dry powdered form by subsequent extractions without additional catalysts, leaving a relatively pure cellulose fraction, 84% glucan, as found in chemical pulps.
Lignin structural analysis indicated GTP processing resulted in extensive degradation of B-aryl ether bonds through the C-y elimination, followed by abundant phenolic hydroxyl liberation. At the same time, condensation occurred in the GTP lignin, providing relatively high molecular weight, near to that of the enzymatic mild acidolysis lignin. Better thermal stability was observed for this GTP lignin. In addition to lignin, xylan was successfully isolated as another polymer stream after GTP pretreatment. The recovered water insoluble xylan (WIX) was predominant alkali soluble fraction with a maximum purity of 84% and comparable molecular weight to xylan isolated from non-pretreated fibers. Additionally, the narrow molecular weight distribution of recovered WIX, was arisen from the pre-extraction of low molecular weight water-soluble xylan.
Additionally, a 20-fold increase of the ultimate enzymatic saccharification for GTP pretreated biomass was observed even with significant amounts of lignin and xylan remaining on the non-extracted fiber. The shear and heat processing caused a disintegrated cell wall structure with formation of biomass debris and release of cellulose fibrils, enhancing surface area and most likely porosity. These structural changes were responsible for the improved biomass digestibility. Additionally, no significant inhibitory compounds for saccharification are produced during GTP processing, even at high temperatures. While lignin extraction did not promote improvement in hydrolysis rates, further xylan extraction greatly increases the initial enzymatic hydrolysis rate and final level of saccharification.
The serial of studies fully demonstrate glycerol thermal processing as a novel pretreatment method to enhance biomass saccharification for biofuel production, as well as facilitate biopolymer fractionation. Moreover, the study shows the impact of thermally introduced structural changes to wood biopolymers when heated in anhydrous environments in the presence of hydrogen bonding solvent.<br>Ph. D.
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Dai, Yuqin. "Development of matrix-assisted laser desorption ionization mass spectrometry for biopolymer analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0003/NQ39519.pdf.
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Fischer, Benjamin [Verfasser]. "Comparative analysis of biopolymer-based scaffolds for therapeutically relevant cells / Benjamin Fischer." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2020. http://d-nb.info/1227925336/34.
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Dagnon, Koffi Leonard D'Souza Nandika Anne. "Thermophysical, interfacial and decomposition analyses of polyhydroxyalkanoates introduced against organic and inorganic surfaces." [Denton, Tex.] : University of North Texas, 2009. http://digital.library.unt.edu/ark:/67531/metadc12111.
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Dagnon, Koffi Leonard. "Thermophysical, Interfacial and Decomposition Analyses of Polyhydroxyalkanoates introduced against Organic and Inorganic Surfaces." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc12111/.
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The development of a "cradle-to-cradle" mindset with both material performance during utilization and end of life disposal is a critical need for both ecological and economic considerations. The main limitation to the use of the biopolymers is their mechanical properties. Reinforcements are therefore a good alternative but disposal concerns then arise. Thus the objective of this dissertation is to investigate a biopolymer nanocomposite where the filler is a synthetically prepared layer double hydroxide (inorganic interface); and a biopolymer paper (organic interface) based coating or laminate. The underlying issues driving performance are the packing density of the biopolymer and the interaction with the reinforcement. Since the polyhydroxyalkanoates or PHAs (the biopolymers used for the manufacture of the nanocomposites and coatings) are semicrystalline materials, the glass transition was investigated using dynamic mechanical analysis (DMA) and dielectric spectroscopy (DES), whereas the melt crystallization, cold crystallization and melting points were investigated using differential scanning calorimetry (DSC). Fourier transform infrared (FTIR) spectroscopy was used to estimate crystallinity in the coated material given the low thermal mass of the PHA in the PHA coating. The significant enhancement of the crystallization rate in the PHA nanocomposite was probed using DSC and polarized optical microscopy (POM) and analyzed using Avrami and Lauritzen-Hoffman models. Both composites showed a significant improvement in the mechanical performance obtained by DMA, tensile and impact testing. The degradation and decomposition of the two composites were investigated in low microbial activity soil for the cellulose paper (to slow down the degradation rate that occurs in compost) and in compost. An in-house system according to the American Society for Testing and Materials ASTM D-98 (2003) was engineered. Soil decomposition showed that PHA coating into and onto the cellulose paper can be considered to be a useful method for the assessment of the degradability of the biopolymer. PHA nanocomposite showed enhanced compostability.
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Patel, Nachiket. "Development and Evaluation of a Biopolymer based Ceftriaxone Sodium Oral Formulation." University of Toledo Health Science Campus / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=mco1404772298.
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Martina, David. "Dynamique de fracture d'un hydrogel thermoréversible de biopolymères." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00329187.
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Nous avons étudié la dynamique de fracture d'hydrogels thermoréversibles de biopolymères : les gels de gélatine. Nous avons montré, par des expériences de fracture en mode 1, quasi-stationnaire et dans un régime subsonique, que, contrairement à la fracture des gels chimiques et des élastomères, la propagation de la fracture dans les gels de gélatine n'implique pas la scission des chaînes : elles sont extraites entièrement à travers le réseau en tête de fracture, la dissipation provenant simplement de leurs frottements dans le solvant. Nous avons pu produire un modèle simple de type <> qui permet de rendre compte des ordres de grandeur mesurés ainsi que de prédire des lois d'échelle vérifiées expérimentalement.<br /><br />En parallèle, nous avons étudié le faciès des surfaces créées par la propagation de la fracture. Nous avons montré qu'il n'existe pas de lois d'échelle comme celles observées dans d'autres matériaux ductiles ou fragiles mais que la micro-rugosité présente une hauteur RMS croissante avec la vitesse de fracture, observation jamais rapportée auparavant. Nous avons mis en évidence une vitesse critique en-dessous de laquelle des défauts macroscopiques apparaissent, défauts précédemment observés par Gent et al. dans les élastomères et décrit exhaustivement par Sekimoto et al. dans les gels de polyacrylamide. Nous avons pu expliquer la hauteur caractéristique de ces défauts en prenant en compte que ces matériaux très déformables présentent le phénomène d'émoussage de la fracture (<>). Nous observons par ailleurs que ces défauts et la micro-rugosité présentent une anisotropie selon un angle <> indépendant de la vitesse de fracture et des caractéristiques du gel de gélatine.
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Ndibewu, PP, MB Mgangira, N. Cingo, and RI McCrindle. "Metal and anion composition of two biopolymeric chemical stabilizers and toxicity risk implication for environment." Taylor & Francis, 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001442.
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The objective of this study was to (1) measure the concentration of four anions (Cl-, F-, NO
and SO ) and nine other elements (Al, Ba, Ca, K, Mg, Mn, Fe, Ni, and Si) in two nontraditional
biopolymeric chemical stabilizers (EBCS1 and EBCS2), (2) investigate consequent environmental
toxicity risk implications, and (3) create awareness regarding environmental
health issues associated with metal concentration levels in enzyme-based chemical stabilizers
that are now gaining widespread application in road construction and other concrete materials.
Potential ecotoxicity impacts were studied on aqueous extracts of EBCS1 and EBCS2 using
two thermodynamic properties models: the Pitzer–Mayorga model (calculation of the electrolyte
activity coefficients) and the Millero–Pitzer model (calculation of the ionic activity
coefficients). Results showed not only high concentrations of a variety of metal ions and inorganic
anions, but also a significant variation between two chemical stabilizing mixtures. The
mixture (EBCS2) with the lower pH value was richer in all the cationic and anionic species
than (EBCS1). Sulfate ( ) concentrations were found to be higher in EBCS2 than in
EBCS1. There was no correlation between electrolyte activity and presence of the ionic species,
which may be linked to a possible high ionic environmental activity. The concentrations
of trace metals found (Mn, Fe, and Ni) were low compared to those of earth metals (Ba, Ca,
K, and Mg). The metal concentrations were higher in EBCS1 than in EBCS2. Data suggest that
specific studies are needed to establish “zero” permissible metal ecotoxicity values for elements
and anions in any such strong polyelectrolytic enzyme-based chemical stabilizers.
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Chadha, Avrath. "A dynamic capability perspective to radical innovation : an analysis on the development of biopolymer technology /." [S.l.] : [s.n.], 2009. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18295.
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Renneckar, Scott Harold. "Modification of Wood Fiber with Thermoplastics by Reactive Steam-Explosion." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/11239.
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For the first time, a novel processing method of co-refining wood and polyolefin (PO) by steam-explosion was scientifically explored for wood-thermoplastic composites without a coupling agent. Traditional studies have addressed the improvement of adhesion between components of wood thermoplastic composites through the use of coupling agents such as maleated PO. The objective of this study was to increase adhesion between wood and PO through reactive processing conditions of steam-explosion. PO characteristics, such as type (polyethylene or polypropylene), form (pellet, fiber, or powder) and melt viscosity were studied along with oxygen gas content of the steam-explosion reactor vessel. Modification of co-processed wood fiber was characterized in four studies: microscopy analysis of dispersion of PO with wood fiber, sorption properties of co-processed material, chemical analysis of fractionated components, and morphological investigation of co-processed material. Two additional studies are listed in the appendices that relate to adsorption of amphiphilic polymers to the cellulose fiber surface, which is one hypothesis of fiber surface modification by co-steam-explosion.
Microscopy studies revealed that PO melt viscosity was found to influence the degree of dispersion and uniformity of the steam-exploded material. The hygroscopic nature of the co-processed fiber declined as shown by sorption isotherm data. Furthermore, a water vapor kinetics study found that all co-refined material had increased initial diffusion coefficients compared to the control fiber. Chemical changes in fractionated components were PO-type dependent. Lignin extracted from co-processed wood and polyethylene showed PO enrichment determined from an increase of methylene stretching in the Fourier Transform infrared subtraction spectra, while lignin from co-processed wood and polypropylene did not. Additionally, extracted PO showed indirect signs of oxidation as reflected by fluorescence studies. Solid state nuclear magnetic resonance spectroscopy revealed a number of differences in the co-processed materials such as increased cellulose crystallinity, new covalent linkages and an alternative distribution of components on the nanoscale reflected in the T1Ï relaxation parameter.
Steam-explosion was shown to modify wood fiber through the addition of "non-reactive" polyolefins without the need for coupling agents. In light of these findings, co-refining by steam-explosion should be viewed as a new reactive processing method for wood thermoplastic composites.<br>Ph. D.
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Trater, Allen Martin. "Use of thermal flow analysis and x-ray microtomography to model microstructure evolution in extruded biopolymeric foams /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
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Auduc, Boyer Nathalie. "Elaboration et caractérisation de films Langmuir-Blodgett de polyaminoacides par analyses de surface." Lyon 1, 1994. http://www.theses.fr/1994LYO19009.
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L'objet de ce travail concerne la synthese par la technique de langmuir-blodgett (lb) et la caracterisation par des techniques d'analyse de surface, de monocouches moleculaires ordonees de polyaminoacides synthetiques de conformation alpha helicoidale. Les polyaminoacides etudies sont le poly- l-aspartate de beta benzyle (pab), la poly-l-alanine(p-ala), le poly- l-glutamate de gama benzyle (pgb), la poly-l-methionine (p-met) et la poly-l-leucine (p-leu). Des informations moleculaires ont ete obtenues a partir des spectroscopies ftir (modes reflexion-absorption et transmission), sims-tof, xps et hreels. Les techniques ftir ont permis de determiner la conformation alpha helicoidale et de definir l'orientation de certaines liaisons des chaines laterales et du squelette helicoidal des polyaminoacides dans les films lb. Des informations structurales ont ete obtenues par la microscopie afm a partir de mono et bicouches lb de polyaminoacides, revelant une distribution des helices alpha paralleles entre elles et paralleles au substrat selon des periodicites definies. Enfin, l'epaisseur moyenne d'une monocouche lb de pab, estimee a partir de plusieurs techniques, nous a permis de proposer un modele d'empilement des monocouches lb successives. Parmi les facteurs influencant la conformation d'un polyaminoacide, la temperature a ete particulierement etudiee pour differentes mono et multicouches lb de pab et de pgb et pour des depots de pab et de pgb obtenus par la methode spin coating. La forme gauche de l'helice alpha du pab serait a l'origine des changements de conformation detectes par irras lorsque la temperature augmente
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Cyron, Christian J. [Verfasser], Wolfgang A. [Akademischer Betreuer] Wall, Andreas R. [Akademischer Betreuer] Bausch, and Olleros Ignacio [Akademischer Betreuer] Romero. "Micromechanical Continuum Approach for the Analysis of Biopolymer Networks / Christian Cyron. Gutachter: Andreas R. Bausch ; Ignacio Romero Olleros. Betreuer: Wolfgang A. Wall." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1020057017/34.
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Amirabadi, Seyedshahabaldin. "Characterization of PLA-Talc films using NIR chemical imaging and multivariate image analysis techniques." Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/29853.
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L’emballage joue un rôle important dans l’industrie alimentaire afin de maintenir la qualité des produits le plus longtemps possible. Les films de polymère sont largement utilisés dans l’emballage alimentaire et sont attrayants pour leurs propriétés exceptionnelles. Puisque les polymères à base de pétrole apportent des préoccupations environnementales, les polymères biodégradables tel que le PLA sont étudiés plus intensivement depuis quelques années considérant leurs propriétés écologiques. L’application de films renforcés permet, comparativement aux films simples, d’atteindre des fonctions spécifiques et d’améliorer leurs propriétés tel que l’étanchéité aux gaz. Toutefois, puisque la structure de ces films est plus complexe, le contrôle de qualité de ces derniers est plus difficile. Dans l’industrie, des méthodes hors-ligne sont très souvent utilisées pour effectuer le contrôle de qualité des films produits. Le contrôle est nécessaire puisque la variabilité de la matière première ainsi que le changement des conditions opératoires amènent des modifications qui changent considérablement les propriétés du film. Par conséquent, une inspection en temps réel ainsi qu’un contrôle des films de polymère est nécessaire sur la ligne de production afin d’obtenir un contrôle de qualité s’approchant de l’analyse en temps réel. Un système d’imagerie proche infrarouge (NIR) rapide et non-destructif est proposé pour caractériser les films biodégradables d’acide polylactique contenant du talc produits par extrusion-soufflage et utilisés pour l’emballage. Le but ultime est d’utiliser le système pour faire un contrôle de qualité sur la ligne d’extrusion ainsi qu’après le post-traitement termique, soit le recuit. Un ensemble d’échantillon de film de PLA contenant différentes concentrations en talc ont été fabriqués. Ces derniers ont ensuite été soumis à différentes conditions de recuit. Des images NIR ont été collectées avant la caractérisation des propriétés physiques et mécaniques ainsi que l’étanchéité aux gaz. Des techniques d’imagerie multivariées ont été appliquées aux images hyperspectrales. Celles-ci ont montré que la quantité de talc peut être déterminée et que l’information du spectre NIR permet de prédire les propriétés du film. Dans tous les cas, la méthode proposée permet de déterminer les variations dans les propriétés du film avec une bonne précision.<br>Food packaging plays a great role in the food industry to maintain food products quality as long as possible. Polymer films are widely used in food packaging and also attract attention because of their outstanding advantages. Since petroleum-based polymers are known to cause environmental concerns, biodegradable polymers like PLA were studied more intensively in recent years due to their environmentally friendly properties. The application of reinforced films exceeds simple ones in achieving specific functions and enhancing their properties such as barrier properties. Since the films structures are more complex, quality control is more challenging. In industry, off-line methods are vastly used for quality control of the produced films while variability in raw materials and processing conditions substantially change the film specifications. Consequently, real-time inspection and monitoring of polymer films is needed on the production line to achieve a real-time quality control of the films. A fast and non-invasive near-infrared (NIR) imaging system is proposed to characterize biodegradable polylactic acid (PLA) films containing talc, and produced by extrusion film-blowing for packaging applications. The ultimate goal is to use the system for quality control on the extrusion line, and after a post-processing via thermal treatment (annealing). A set of PLA-talc films with varying talc contents were produced and submitted to annealing under different conditions. NIR images of the films were collected after which the samples were characterized for their physical, mechanical, and gas barrier properties. Multivariate imaging techniques were then applied to the hyperspectral images. It is shown that various talc loadings can be distinguished, and the information contained in the NIR spectra allows predicting the film properties. In all cases, the proposed approach was able to track the variation in film properties with good accuracy
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Guan, Juan. "Investigations on natural silks using dynamic mechanical thermal analysis (DMTA)." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:c16d816c-84e3-4186-8d6d-45071b9a7067.
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This thesis examines the dynamic mechanical properties of natural silk fibres, mainly from silkworm species Bombyx mori (B. mori) and spider species Nephila edulis, using dynamic mechanical thermal analysis, DMTA. The aim is not only to provide novel data on mechanical properties of silk, but also to relate these properties to the structure and morphology of silk. A systematic approach is adopted to evaluate the effect of the three principal factors of stress, temperature and hydration on the properties and structure of silk. The methods developed in this work are then used to examine commercially important aspects of the ‘quality’ of silk. I show that the dynamic storage modulus of silks increases with loading stress in the deformation through yield to failure, whereas the conventional engineering tensile modulus decreases significantly post-yield. Analyses of the effects of temperature and thermal history show a number of important effects: (1) the loss peak at -60 °C is found to be associated the protein-water glass transition; (2) the increase in the dynamic storage modulus of native silks between temperature +25 and 100 °C is due simply to water loss; (3) a number of discrete loss peaks from +150 to +220°C are observed and attributed to the glass transition of different states of disordered structure with different intermolecular hydrogen bonding. Excess environmental humidity results in a lower effective glass transition temperature (Tg) for disordered silk fractions. Also, humidity-dynamic mechanical analysis on Nephila edulis spider dragline silks has shown that the glass transition induces a partial supercontraction, called Tg contraction. This new finding leads to the conclusion of two independent mechanisms for supercontraction in spider dragline silks. Study of three commercial B. mori cocoon silk grades and a variety of processed silks or artificial silks shows that lower grade and poorly processed silks display lower Tg values, and often have a greater loss tangent at Tg due to increased disorder. This suggests that processing contributes significantly to the differences in the structural order among natural or unnatural silks. More importantly, dynamic mechanical thermal analysis is proposed to be a potential tool for quality evaluation and control in silk production and processing. In summary, I demonstrate that DMTA is a valuable analytical tool for understanding the structure and properties of silk, and use a systematic approach to understand quantitatively the important mechanical properties of silk in terms of a generic structural framework in silk proteins.
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Grousseau, Estelle. "Potentialités de production de Poly-Hydroxy-Alcanoates (PHA) chez Cupriavidus necator sur substrats de type acides gras volatifs : études cinétiques et métaboliques." Thesis, Toulouse, INSA, 2012. http://www.theses.fr/2012ISAT0002/document.
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L’accumulation de biopolymère de réserve (PolyHydroxyAlcanoates ou PHA) par la souche Cupriavidus necator, à partir de substrats de type acides gras volatils (acide butyrique, acide propionique et acide acétique) a été étudiée. Elle est induite par une limitation phosphore. Les performances atteintes lors des cultures se situent parmi les meilleures de la littérature pour ce type de substrat : jusqu’à 66 g.L-1 de biomasse totale avec un pourcentage d’accumulation massique de 88% en PHB –PolyHydroxyButyrate- ou en PHB-co-HV -PolyHydroxyButyrate-co-HydroxyValerate- comportant jusqu’à 52% de motifs d’HV.Pour chaque source carbonée, une caractérisation cinétique et stœchiométrique de la souche a été réalisée en l’absence d’effets inhibiteurs dus aux substrats acides grâce à des cultures de type Fed-Batch avec des apports non limitants et non inhibiteurs en carbone. Il a été dégagé :- un taux de croissance maximal de la souche de 0,33 h-1 pour les trois acides étudiés- une relation entre vitesse spécifique de production de PHA et taux de croissance fixée par la disponibilité et les flux de production de NADPH2 avec un découplage inverse pour les taux de croissance supérieurs à 0,05 h-1 et un couplage partiel pour les taux de croissance inférieurs- un optimum de 0,35 Cmole.Cmole-1.h-1, associé à un taux de croissance de l’ordre de 0,05 h-1.- une amélioration de la production de PHB en termes de vitesses spécifiques mais également en termes de rendements si une faible croissance résiduelle est maintenueLa réponse de la souche à un excès de substrat acide a été caractérisée via l’étude de régimes transitoires induits par des pulses sur des cultures continues préalablement stabilisées en régime permanent. Il a été montré qu’en excès de phosphore, face à un brusque excès de substrat, la souche est incapable d’adapter rapidement son taux de croissance. L’excès est donc dirigé vers la production de PHA dont les voies sont plus rapidement mobilisables. En conditions limitantes de phosphore, le substrat excédentaire est utilisé pour la production de PHA. L’inhibition par les acides se traduit par une diminution des capacités de biosynthèse de la biomasse et des PHA entrainant une réduction de l’assimilation du carbone puis une diminution des rendements de conversion. D’autre part la sensibilité d’un système continu à un excès de substrat dépend du point de fonctionnement choisi : plus il est optimal en termes de vitesse, moins le système est robuste. L’acide propionique est très inhibiteur comparé aux autres acides étudiés (dès 3-4 mM contre 30-40 mM). Il n’agit pas simplement via une accumulation excessive dans le cytoplasme mais il exerce également une inhibition spécifique des voies métaboliques.Un antagonisme entre les substrats (acide acétique et butyrique) a été constaté et expliqué grâce à une analyse des flux métaboliques. L’acide acétique est assimilé préférentiellement pour produire la biomasse, l’énergie et les cofacteurs nécessaires à la production de PHA, alors que l’acide butyrique est utilisé pour la synthèse de PHB. La proportion maximale d’acide acétique admise dans l’alimentation en fonction des conditions fixées en régime permanent est calculée et peut être limitée à 40% du carbone.Enfin il a été déterminé que si une croissance résiduelle est assurée grâce à un apport en phosphore, le pourcentage maximal d’HV dans le polymère dépend du taux d’acide propionique dans l’alimentation et ne peux dépasser 33 ± 5% sur acide propionique pur. Par contre, si aucune croissance résiduelle n’est assurée, il est possible de convertir l’acide propionique en motifs d’HV uniquement<br>Reserve Biopolymer (PolyHydroxyAlkanoates or PHA) accumulation by the strain Cupriavidus necator, from Volatile Fatty Acids (VFA, like butyric acid, propionic acid and acetic acid) was investigated. This production is induced by a phosphorus limitation. For this type of substrates, performances reached during cultures are among the best listed in the literature: up to 66 g.L-1 of total biomass with 88% (w/w) of PHB –PolyHydroxyButyrate- or PHB-co-HV -PolyHydroxyButyrate-co-HydroxyValerate- with a HV content up to 52 Mole%.For each carbon source, kinetic and stoechiometric characterization has been carried out thanks to Fed-Batch cultures with non-limiting and non-inhibitory carbon feed. It has been established:- a maximal growth rate of 0,33 h-1 for the three acid investigated- a relationship between specific PHA production rate and growth rate which is set by the availability and production flux of NADPH2. For growth rate above 0,05 h-1, there is an inverse coupling. For growth rate under 0,05 h-1, there is a partial coupling.- an optimum of 0,35 Cmole.Cmole-1.h-1 is associated with a growth rate of 0,05 h-1.- if a low residual growth rate is maintained, an improvement of PHB production is recorded in terms of specific production rate and yieldsThe response of the strain to an excess of acid substrate was characterized through the investigation of transient state induced by pulsed addition of substrate during continuous cultures stabilized in steady state. It was shown that in excess of phosphorus, when there is a substrate excess, the strain is unable to quickly adapt its growth rate, so the excess is directed to PHA production whose ways seem to be more easily mobilized. Under phosphorus limitation, an excess of substrate is used for PHA production. Acid inhibition results in a decrease in biomass and PHA production capacity which leads to a decrease in carbon assimilation and conversion yields. The sensitivity of a continuous system to an excess of substrate depends on the chosen operating point: the more it is optimal in terms of specific production rate, the less the system is robust. Propionic acid is highly inhibitory compared to the other acids studied (from 3-4 mM versus 30-40 mM). It does not act only via an excessive accumulation in the cytoplasm but also exerts a specific inhibition of metabolic pathways.An antagonism between substrates (acetic and butyric acid) has been established and explained thanks to the Metabolic Flux Analysis. Acetic acid is preferentially used to produce biomass, energy and cofactors for PHA synthesis, whereas butyric acid is used to product PHB. According to the conditions set during steady state, maximal content of acetic acid admitted in the feed can be calculated. It can be limited to 40% of the carbon in the feed.Finally if a growth rate is maintained thanks to a phosphorus supply, the maximal HV content in polymer is function of propionic acid in the feed and cannot exceed 33 ± 5 Mole% on pure propionic acid. Conversely, if there is no residual growth, a total conversion of propionic acid into HV is allowed
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Bright, Joanne. "Morphologies and interactions of biopolymers at surfaces." Phd thesis, 1999. http://hdl.handle.net/1885/147317.
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Keller, Karin Mia. "Biopolymer analysis by electrospray ionization and tandem mass spectrometry." Thesis, 2004. http://hdl.handle.net/2152/1169.
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Keller, Karin Mia Brodbelt Jennifer S. "Biopolymer analysis by electrospray ionization and tandem mass spectrometry." 2004. http://wwwlib.umi.com/cr/utexas/fullcit?p3143282.
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Zhong, Lingxiu. "Dependence of secondary structure of biopolymers on environment : a circular dichroism study of equivocal amino acid sequences in proteins and of left-handed DNA." Thesis, 1992. http://hdl.handle.net/1957/36335.
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Tumarkin, Ethan. "Microfluidic Studies of Biological and Chemical Processes." Thesis, 2012. http://hdl.handle.net/1807/35077.
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This thesis describes the development of microfluidic (MF) platforms for the study of biological and chemical processes. In particular the thesis is divided into two distinct parts: (i) development of a MF methodology to generate tunable cell-laden microenvironments for detailed studies of cell behavior, and (ii) the design and fabrication of MF reactors for studies of chemical reactions.
First, this thesis presented the generation of biopolymer microenvironments for cell studies. In the first project we demonstrated a high-throughput MF system for generating cell-laden agarose microgels with a controllable ratio of two different types of cells. The MF co-encapsulation system was shown to be a robust method for identifying autocrine and/or paracrine dependence of specific cell subpopulations.
In the second project we studied the effect of the mechanical properties on the behavior of acute myeloid leukemia (AML2) cancer cells. Cell-laden macroscopic agarose gels were prepared at varying agarose concentrations. A modest range of the elastic modulus of the agarose gels were achieved, ranging from 0.62 kPa to 20.21 kPa at room temperature. We observed a pronounced decrease in cell proliferation in stiffer gels when compared to the gels with lower elastic moduli.
The second part of the thesis focuses on the development of MF platforms for studying chemical reactions. In the third project presented in this thesis, we exploited the temperature dependent solubility of CO2 in order to: (i) study the temperature mediated CO2 transfer between the gas and the various liquid phases on short time scales, and (ii) to generate bubbles with a dense layer of colloid particles (armoured bubbles).
The fourth project involved the fabrication of a multi-modal MF device with integrated analytical probes. The MF device comprised a pH, temperature, and ATR-FTIR probes for in-situ analysis of chemical reactions in real-time. Furthermore, the MF reactor featured a temperature controlled feedback system capable of maintaining on-chip temperatures at flow rates up to 50 mL/hr.
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Chen, Xiaoyu. "Mass spectrometry in biopolymer analysis." 2003. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Siegel, Amanda P. "Regulating Lipid Organization and Investigating Membrane Protein Properties in Physisorbed Polymer-tethered Membranes." 2012. http://hdl.handle.net/1805/2890.
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Indiana University-Purdue University Indianapolis (IUPUI)<br>Cell membranes have remarkable properties both at the microscopic level and the molecular level. The current research describes the use of physisorbed polymer-grafted lipids in model membranes to investigate some of these properties on both of these length scales. On the microscopic scale, plasma membranes can be thought of as heterogenous thin films. Cell membranes adhered to elastic substrates are capable of sensing substrate/film mismatches and modulating their membrane stiffness to more closely match the substrate. Membrane/substrate mismatch can be modeled by constructing lipopolymer-enriched lipid monolayers with different bending stiffnesses and physisorbing them to rigid substrates which causes buckling. This report describes the use of atomic force microscopy and epimicroscopy to characterize these buckled structures and to illustrate the use of the buckled structures as diffusion barriers in lipid bilayers. In addition, a series of monolayers with varying bending stiffnesses and thicknesses are constructed on rigid substrates to analyze changes in buckling patterns and relate the experimental results to thin film buckling theory.
On the molecular scale, plasma membranes can also be thought of as heterogeneous mixtures of lipids where the specific lipid environment is a crucial factor affecting membrane protein function. Unfortunately, heterogeneities involving cholesterol, labeled lipid rafts, are small and transient in live cells. To address this difficulty, the present work describes a model platform based on polymer-supported lipid bilayers containing stable raft-mimicking domains into which transmembrane proteins are incorporated (αvβ3, and α5β1integrins). This flexible platform enables the use of confocal fluorescence fluctuation spectroscopy to quantitatively probe the effect of cholesterol concentrations and the binding of native ligands (vitronectin and fibronectin for αvβ3, and α5β1) on protein oligomerization state and on domain-specific protein sequestration. In particular, the report shows significant ligand-induced integrin sequestration with a low level of dimerization. Cholesterol concentration increases rate of dimerization, but only moderately. Ligand addition does not affect rate of dimerization in either system. The combined results strongly suggest that ligands induce changes to integrin conformation and/or dynamics without inducing changes in integrin oligomerization state, and in fact these ligand-induce conformational changes impact protein-lipid interactions.
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Wang, Chen-Kai, and 王振凱. "Preparation and Properties Analysis of Polypropylene/Biopolymer Blends." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/g943tw.
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碩士<br>明志科技大學<br>化學工程系碩士班<br>103<br>This study used 25% starch blend with two type of polypropylene plastic,and the blends were prepared by twin screw extruder. The extruded strands were cut into pellets and injection molded to make test specimens.We examined the use of compatibilizer in influencing the thermal properties, miscibility properties, mechanical properties.These PP/starch blends were further characterized by differential scanning calorimetry(DSC), scanning electron microscope(SEM), thermo gravimetric analysis(TGA),impact test,tensile tests and water absorption tests. It was found that,introduction of starch particles resulted in miscibility and thermal stability are increased and strengthen PP spherulites structure. The scanning electron microscope results indicated that the addition of compatibilizer can increased the allocation of different phases and dispersion and interfacial adhesion of blends. The impact tests and tensile tests results indicated that the addition of starch can decreased the rigidity of PP. Besides,a lower elastic modulus and a higher elongation at break were obtained, which show that the addition of starch would make the rigidity PP to ductile materials. The water absorption tests indicated that the addition of compatibilizer can decreased the water absorption of blends.
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Jeng, Huei-Yau, and 鄭暉耀. "Mechanism analysis of bipolar resistive switching in modified DNA biopolymer devices." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/32hp54.
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Ebeling, Daniel David. "Development of charge reduction electrospray mass spectrometry for biopolymer and synthetic polymer analysis." 2001. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Tanataweethum, Nida. "Mechanical property and biocompatibility of PLLA coated DCPD composite scaffolds." Thesis, 2014. http://hdl.handle.net/1805/4448.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)<br>Dicalcium phosphate dihydrate (DCPD) cements have been used for bone repair due to its excellent biocompatibility and resorbability. However, DCPD cements are typically weak and brittle. To overcome these limitations, the sodium citrate used as a setting regulator and the coating of poly-L-lactide acid (PLLA) technique have been proposed in this study. The first purpose of this thesis is to develop composite PLLA/DCPD scaffolds with enhanced toughness by PLLA coating. The second purpose is to
examine the biocompatibility of the scaffolds. The final purpose is to investigate the degradation behaviors of DCPD and PLLA/DCPD scaffolds. In this experiment, DCPD cements were synthesized from monocalcium phosphate monohydrate (MCPM) and 𝛽-tricalcium phosphate (𝛽 –TCP) by using deionized water and sodium citrate as liquid components. The samples were prepared with powder to liquid ratio (P/L) at 1.00, 1.25 and 1.50. To fabricate the PLLA/DCPD composite samples, DCPD samples were coated with 5 % PLLA. The samples were characterized mechanical properties, such as porosity, diametral tensile strength, and fracture energy. The mechanical properties of DCPD scaffolds with and without PLLA coating after the in vitro static degradation (day 1, week1, 4, and 6) and in vitro dynamic degradation (day 1, week 1, 2, 4, 6, and 8) were investigated by measuring their weight loss, fracture energy, and pH of phosphate buffer
solution. In addition, the dog bone marrow stromal stem cells (dBMSCs) adhesion on
DCPD and PLLA/DCPD composite samples were examined by scanning electron
microscopy. The cell proliferation and differentiation in the medium conditioned with
DCPD and PLLA/DCPD composite samples were studied by XTT (2,3-Bis(2-methoxy-4-
nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt), and alkaline phosphatase (ALP) assay, respectively. The addition of sodium citrate and PLLA coating played a
crucial role in improving the mechanical properties of the samples by increasing the
diametral tensile strength from 0.50 ± 0.15 MPa to 2.70 ± 0.54 MPa and increasing the
fracture energy from 0.76 ± 0.18 N-mm to 12.67 ± 4.97 N-mm. The DCPD and
PLLA/DCPD composite samples were compatible with dBMSCs and the cells were able
to proliferate and differentiate in the conditioned medium. The degradation rate of DCPD
and PLLA/DCPD samples were not significant different (p > 0.05). However, the DCPD
and PLLA/DCPD composite samples those used sodium citrate as a liquid component
was found to degrade faster than the groups that use deionized water as liquid component