Dissertations / Theses on the topic 'Biopolymers'
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1
Kane, Aine T. M. "Investigation of biopolymers." Thesis, Queen's University Belfast, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282192.
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Richards, Dawn P. "Electrophoretic separations of biopolymers." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0013/NQ59661.pdf.
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Gray, Robert A. "Flourophore labelling of biopolymers." Thesis, Coventry University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308085.
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Rahman, Alireza. "Control release from biopolymers." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6074/.
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Control release from biopolymer is an important issue for flavour perception following to reduce flavour content such as salt in food formulation without any tangible change in taste. The experiments presented release behaviour from low acyl gellan gum gel. Attempts were focused to find a link between mechanical properties and microstructure of the gel. After conducting the compression tests, a number of parameters were investigated and the consist of the effect of the gellan concentration, salt concentration and cyclic compression on the mechanical properties of the gel. According to the results, mechanical properties of the gellan gels were remarkably affected by the gellan concentration, salt concentration and cyclic compression. It was shown that the gellan concentration, salt concentration and cyclic compression play a main role on the microstructure of the gel. The release experiments were carried out using uniaxial and cyclic compression to investigate the salt and riboflavin release from the gellan gel to identify the parameters which play a role on release from the gellan gel. Release experiments have shown that release profile is affected by the gellan concentration, salt concentration and number of cyclic compression. Results demonstrated that release profile can be affected by molecular weight of the releasable material.
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Catani, Linda. "Development and Characterization of Biopolymers." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20761/.
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Development and characterization of biopolymers was done in AIJU’s laboratories. AIJU, Technological Institute for children’s products and leisure is based in Spain. The work has the aim to study qualities and characteristics of bioplastics’ blends, in order to design where improvements can be executed. Biopolymers represent a sector with great development possibilities because they combine high technical potential and eco-sustainability. Nowadays, plastic pollution has becoming increasingly concerning, particularly in terms of management of waste. Bioplastics provide an alternative for the disposal of products, reducing the volume of waste and enhancing the end of life recovery. Despite the growing interest in biopolymers there is some gaps that need be filled. The main objective on this work, is the optimization of bioplastics mechanical properties, to find suitable substitutes, as similar as possible to conventional plastics. Firstly, investigations on processability of biomaterials has been deepen since the project deals with toy manufacturing’s sector. Thus, starting from laboratory scale the work aspires to expand industrially. By working with traditional machines, it was notable that, with some limited modifications, the equipment can perform the same functions. Therefore, operational processes do not emerge as an obstacle to the production chain.
Secondly, after processing bio-blends, they are characterized by thermal tests (melt flow index, differential scanning calorimetry-DSC, thermogravimetry-TGA) and mechanical tests (traction and flexural tests, Charpy impact, SHORE D hardness and density). While the compatibility does not show relevant results, mechanical improvements has been visualized with addition of more ductile materials. The study was developed by inclusion of sustainable additive VINNEX® to blends. The thesis has highlighted that integration of more flexible materials provides elasticity without compromising bioplastics’ properties.
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Frohberg, Patrick [Verfasser]. "Protein-based biopolymers / Patrick Frohberg." Aachen : Shaker, 2017. http://d-nb.info/1124366040/34.
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Schnauß, Jörg, Tina Händler, and Josef A. Käs. "Semiflexible biopolymers in bundled arrangements." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-207973.
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Bundles and networks of semiflexible biopolymers are key elements in cells, lending them mechanical integrity while also enabling dynamic functions. Networks have been the subject of many studies, revealing a variety of fundamental characteristics often determined via bulk measurements. Although bundles are equally important in biological systems, they have garnered much less scientific attention since they have to be probed on the mesoscopic scale. Here, we review theoretical as well as experimental approaches, which mainly employ the naturally occurring biopolymer actin, to highlight the principles behind these structures on the single bundle level.
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Fiester, Steven E. "Characterization of Optically Active Biopolymers." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1302187683.
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SCARPA, TOMMASO. "BIOPOLYMERS FOR CARTILAGE TISSUE-ENGINEERING." Doctoral thesis, Università degli studi di Trieste, 2007. http://thesis2.sba.units.it/store/handle/item/12302.
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Marenduzzo, Davide. "Phases of Polymers and Biopolymers." Doctoral thesis, SISSA, 2002. http://hdl.handle.net/20.500.11767/4581.
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In this thesis we develop coarse grained models aiming at understanding physical
problems arising from phase transitions which occur at the single molecule level. The
thesis will consist of two parts, grossly related to and motivated by the two subjects
dealt with above. In the first half, we will focus on critical phenomena in stretching
experiments, namely in DNA unzipping and polymer stretching in a bad solvent. In
the second part, we will develop a model of thick polymers, with the goal of understanding the origin of the protein folds and the physics underlying the folding ‘transition’,
as well as with the hope of shedding some light on some of the fundamental
questions highlighted in this Introduction.
In the first part of the thesis we will introduce a simple model of self-avoiding
walks for DNA unzipping. In this way we can map out the phase diagram in the
force vs. temperature plane. This reveals the present of an interesting cold unzipping
transition. We then go on to study the dynamics of this coarse grained model. The
main result which we will discuss is that the unzipping dynamics below the melting
temperature obeys different scaling laws with respect to the opening above thermal
denaturation, which is governed by temperature induced fluctuating bubbles.
Motivated by this and by recent results from other theoretical groups, we move on
to study the relation to DNA unzipping of the stretching of a homopolymer below the
theta point. Though also in this case a cold unzipping is present in the phase diagram,
this situation is richer from the theoretical point of view because the physics depends
crucially on dimension: the underlying phase transition indeed is second order in two
dimensions and first order in three. This is shown to be intimately linked to the failure
of mean field in this phenomena, unlike for DNA unzipping. In particular, the globule
unfolds via a series (hierarchy) of minima. In two dimensions they survive in the thermodynamic
limit whereas if the dimension, d, is greater than 2, there is a crossover
and for very long polymers the intermediate minima disappear. We deem it intriguing
that an intermediate step in this minima hierarchy for polymers of finite length in the
three-dimensional case is a regular mathematical helix, followed by a zig-zag structure.
This is found to be general and almost independent of the interaction potential
details. It suggests that a helix, one of the well-known protein secondary structure, is
a natural choice for the ground state of a hydrophobic protein which has to withstand
an effective pulling force.
In the second part, we will follow the inverse route and ask for a minimal model
which is able to account for the basic aspects of folding. By this, we mean a model
which contains a suitable potential which has as its ground state a protein-like structure
and which can account for the known thermodynamical properties of the folding
transition. The existing potential which are able to do that[32] are usually constructed
‘ad hoc’ from knowledge of the native state. We stress that our procedure here is
completely different and the model which we propose should be built up starting
from minimal assumptions. Our main result is the following. If we throw away the
usual view of a polymer as a sequence of hard spheres tethered together by a chain
(see also Chapter 1) and substitute it with the notion of a flexible tube with a given
thickness, then upon compaction our ’thick polymer’ or ’tube’ will display a rich secondary structure with protein-like helices and sheets, in sharp contrast with the
degenerate and messy crumpled collapsed phase which is found with a conventional
bead-and-link or bead-and-spring homopolymer model. Sheets and helices show up
as the polymer gets thinner and passes from the swollen to the compact phase. In this
sense the most interesting regime is a ‘twilight’ zone which consists of tubes which
are at the edge of the compact phase, and we thus identify them as ‘marginally compact
strucures’. Note the analogy with the result on stretching, in which the helices
were in the same way the ‘last compact’ structures or the ‘first extended’ ones when
the polymer is being unwinded by a force.
After this property of ground states is discussed, we proceed to characterize the
thermodynamics of a flexible thick polymer with attraction. The resulting phase diagram
is shown to have many of the properties which are usually required from protein
effective models, namely for thin polymers there is a second order collapse transition
(O collapse) followed, as the temperature is lowered, by a first order transition
to a semicrystalline phase where the compact phase orders forming long strands all
aligned preferentially along some direction. For thicker polymers the transition to
this latter phase occurs directly from the swollen phase, upon lowering T, through a
first order transition resembling the folding transition of short proteins.
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Brassett, Anne Judith. "Photoexitations in conjugated polymers and biopolymers." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309049.
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Bonthrone, Karen Margaret. "Physical and biological studies of biopolymers." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309263.
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Abu-Hardan, Madian. "Biopolymers-oil interactions in expanded systems." Thesis, University of Nottingham, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479366.
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Radcliffe, David S. "Ion capture mechanisms of antibiotic biopolymers." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680443.
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Woolnough, Catherine Anne School of Biotechnology & Biomolecular Science UNSW. "Biodegradation, surface rugosities and biofilm coverage of biopolymers." Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Science, 2006. http://handle.unsw.edu.au/1959.4/30426.
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The increasing concern for sustainability and progress of medical research has resulted in the emergence of a wide range of biopolymers. The biodegradability of these alternative biopolymers requires investigation prior to their application in environmental and medical systems. This Thesis describes biodegradation of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(HB-co-HV)), poly(3- hydroxyoctanoate) (PHO), poly-DL-lactide (PDLL), poly-DL-lactide-co-glycolide (PDLLG) and ethyl cellulose (EC). Polymers were buried in garden soil for in vivo biodegradation experiments and a mixed population of microbes from the soil were incubated in laboratory in vitro biodegradation experiments. In both systems the short chain length PHA???s degraded rapidly and the medium chain length PHAs and other biomaterials displayed either slow or negligible weight loss. PHB and P(HB-co-HV) copolymers degraded to T50 6.7 to 9.7 times faster in vitro than in vivo. After 380 days burial in soil PHO had lost 60 % of the original 20 mg weight, PDLL 28 % and PDLLG 35 %. Ethyl cellulose and polystyrene did not biodegrade, Polymer-microbe surface interactions were investigated. The faster degrading polymers PHB and P(HB-co-HV) attracted a higher coverage of biofilm than the slower degrading polymers PHO, PDLL and PDLLG for both the in vitro and in vivo experiments. The non-degradable polymers (EC and polystyrene) attracted no biofilm. In vitro and in vivo experiments demonstrated a positive correlation between biofilm coverage and polymer weight loss. Additionally the rougher air sides of solvent cast films attracted more biofilm than the smoother dish sides. Polymer surface changes were quantified with microscopy. Surface roughness of PHB, P(HB-co-8HV) and PHO increased during biodegradation, primarily due to an increase in the waviness component for both in vitro and in vivo degradation. In vitro methods provided a rapid mechanism for protocol development and sufficiently predicted both surface roughness changes and biofilm-biodegradation relationships in vivo. PHB and P(HB-co-8HV) were blended with the biodegradable antifouling agent 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOI or Sea Nine 211). DCOI leached slowly from the films into the soil delaying biodegradation of the films until a lower residual level of DCOI remained. Biofouling was reduced on PHA films containing DCOI.
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Duval, Antoine. "Contribution à l'étude du gluten comme matériau : apport de lignines de différentes natures." Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENI104.
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Le gluten, un ensemble de protéines contenues dans le grain de blé, peut être utilisé pour formuler des matériaux polymères, le plus souvent en présence de glycérol comme plastifiant. Ces matériaux sont généralement limités par une forte sensibilité à l’eau, ainsi que par des propriétés mécaniques faibles devant celles des polymères synthétiques. L’influence de la teneur en glycérol sur l’absorption d’eau des matériaux, ainsi que sur la répartition des phases et leur relaxation, a été évaluée dans un premier temps.Puis, un second biopolymère, la lignine, issue du bois, a été incorporé dans les matériaux pour en améliorer les propriétés. L’influence de plusieurs lignines, obtenues comme co-produit des industries papetières (lignine Kraft et lignosulfonates), a ainsi été évaluée. La lignine Kraft permet d’améliorer la rigidité et les propriétés thermiques des matériaux, ainsi que de limiter leur sensibilité à l’eau, tandis que l’ajout de lignosulfonates permet de réduire la teneur en glycérol, avec pour conséquence de limiter la sensibilité à l’eau et d’améliorer les propriétés mécaniques.Différente étapes de fractionnement des matières premières ont ensuite permis de mieux interpréter les interactions existant entre le gluten et les lignines, et de les corréler aux propriétés macroscopiques des matériaux. L’influence de la nature des protéines et de la masse molaire des lignines ont ainsi pu être mises en évidenceWheat gluten, a set of proteins from the wheat kernel, is commonly used to process polymeric materials, usually in the presence of glycerol as a plasticizer. Their use is however limited, because of their high sensitivity to water and relatively poor mechanical properties when compared to synthetic polymers. We first evaluated the influence of the glycerol content on the water absorbance, the phase separation and their glass transition.Then, another biopolymer, wood lignin, has been incorporated into the materials in order to enhance their properties. The influence of different types of lignin from the pulp paper industry, Kraft lignin and lignosulfonates, have been investigated. Kraft lignin addition enhances materials rigidity and thermal properties, and reduces the water sensitivity, whereas lignosulfonates allow to decrease the glycerol content, resulting in better mechanical properties and reduced water sensitivity.To gain insights into the interactions between gluten and lignins, several fractionation procedures have then been carried out. The influence of the protein type and lignin molecular mass could be pointed out, and where correlated to the materials macroscopic properties
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Lee, Jae-Ho. "Soft materials based on vesicles and biopolymers." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3364.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Chemical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Li, Sijin. "Hollow / porous carbon spheres derived from biopolymers." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0121.
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Dans ce travail, nous avons proposé pour la première fois de synthétiser des sphères de carbone creuses ou poreuses par traitement hydrothermal et pyrolyse ultérieure de «templates», soit d’origine naturelle tels que des œufs de poisson ou des billes d’alginate, ou synthétiques comme des capsules polymères remplies d’un mélange xylitol-érythritol. Le saccharose, le tanin, la résine résorcinol-formaldéhyde, etc., ont été utilisés comme précurseurs de carbone. L’influence des conditions de réaction pendant le traitement hydrothermal ou la pyrolyse a été étudiée afin de trouver les conditions optimales pour contrôler le diamètre et la structure des matériaux finaux. Les propriétés d’absorption des micro-ondes par une hétérostructure consistant en une monocouche ordonnée de sphères de carbone vitreux, creuses ou poreuses, ont été étudiées dans la bande Ka (gamme de fréquences de 26-37 GHz), des points de vue expérimental et théorique. Des tests préliminaires pour concentrer l’énergie solaire, afin d’augmenter l’évaporation thermique solaire, ont également été réalisés dans cette thèseIn the present work, we proposed for the first time to synthesize hollow / porous carbon spheres by hydrothermal treatment and subsequent pyrolysis of templates, either natural such as fish eggs or alginate beads, or synthetic such as polymer capsules filled with xylitol-erythritol blend. Sucrose, tannin, resorcinol-formaldehyde, etc., were used as carbon precursors. The influence of the reaction conditions during the hydrothermal treatment or the pyrolysis was investigated in order to find the optimal reaction conditions and to tune the diameter and the porosity of the resultant materials. The microwave-absorbing properties of a heterostructure consisting of an ordered monolayer of hollow or porous glassy carbon spheres packed in 2D were experimentally and theoretically investigated in the Ka-band (26–37 GHz) frequency range. The first test of the hollow carbon spheres used for concentrating the solar energy and thus improving solar thermal evaporation was also carried out in this thesis
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Dlamini, Abednego Mfanufikile, of Western Sydney Hawkesbury University, of Science Technology and Agriculture Faculty, and School of Applied and Environmental Sciences. "Microbial biopolymers from whey : production and applications." THESIS_FST_AES_Dlamini_A.xml, 1997. http://handle.uws.edu.au:8081/1959.7/322.
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The main aim of this research was to utilise whey as a fermentation substrate for the production of microbial biopolymers.Of the three commercial biopolymer producers tested for biopolymer production in whey, only Pseudodomonas elodea produced significant apparent viscosities of up to 470cP at 2 s-1 on enriched whey broths. In these broths lactose utilisation was poor (14% w/v). A strain of P. elodea that had improved lactose utilising capacity was selected after six serial transfers on whey and lactose rich broths. After screening more than 60 bacterial isolates, a strain of Klebsiella oxytoca that initially produced a broth apparent viscosity of 36 cP at 12 s-1 in whey was isolated from raw milk. Biopolymer production was optimised in the K. oxytoca isolate.Concentrations of over 16 g/1 and broth apparent viscosities greater than 20,000 cP at 0.6 s-1 were obtained after optimisation. The biopolymer produced by the K. oxytoca isolate was shown to contain rhamnose, glucose and cellobiose, a composition not comparable to any reported polysaccharide. Polymer application studies indicated that it had potential to be used as a thickener, stabiliser, and binder.Doctor of Philosophy (PhD)
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Dlamini, Abednego Mfanufikile. "Microbial biopolymers from whey : production and applications /." View thesis View thesis, 1997. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030514.130601/index.html.
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Thesis (Ph. D.)--University of Western Sydney, Hawkesbury."A thesis submitted to the University of Western Sydney Hawkesbury in fulfillment of the requirement for the degree of Doctor of Philosophy." Includes bibliographical references (leaves 204-224).
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Korehei, Reza. "Encapsulation of T4 bacteriophage in electrospun biopolymers." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44398.
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Packaging foods with antibacterial electrospun fibrous mats, in particular the incorporation of bacteria specific viruses such as bacteriophages may address concerns triggered by recent waves of bacterial food contamination. To this end several methods for incorporating or encapsulating T4 bacteriophage into electrospun fibres were investigated. The incorporation of T4 bacteriophage using simple suspension electrospinning lead to major losses in T4 bacteriophage activity, with more than five-orders of magnitude decrease in activity being observed. Improved T4 bacteriophage viability was obtained using two newly developed electrospinning processes, emulsion and coaxial electrospinning. In emulsion electrospinning, T4 bacteriophage was pre-encapsulated in an alginate reservoir via an emulsification process and subsequently electrospun into fibres. The emulsion electrospun fibres exhibited only two-orders of magnitude decrease in T4 bacteriophage activity. By contrast, complete T4 bacteriophage activity was maintained when coaxial electrospinning was employed. In the coaxial electrospinning process, a core/shell fibre structure was formed where the T4 bacteriophage was allocated to the fibre core, protected by the outer polymer shell. Depending on the polymer system used the rate of T4 bacteriophage release from the coaxial electrospun fibres varied. When hydrophilic poly(ethylene oxide) (PEO) was used as the polymer shell layer, immediate release of T4 bacteriophage was observed upon exposure to buffer. Increasing the PEO molecular weight increased the electrospun fibre diameter and viscosity of the releasing medium, which resulted in relatively slower T4 bacteriophage release pro-files. Similarly, the blending of cellulose diacetate (CDA) with PEO dramatically decreased the release behaviour. Depending on the PEO/CDA ratio, post-release electrospun fibre morphology varied from discontinuous fibres to minimally swollen fibres, consistent with the release profiles.
In the PEO fibres the mechanism of T4 bacteriophage release is likely through solvent activa-tion/polymer dissolution, while in the PEO/CDA blends a more diffusion control mechanism likely prevails. The Encapsulation of T4 bacteriophage within the electrospun fibres also improved T4 bacteriophage storability; full T4 bacteriophage activity was maintained for more than a month at +4 °C, as compared to only hours for non-encapsulated phage. These results are significant in the context of controlling and preventing bacterial infections in perishable foods during refrigerated storage.
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Hartley, Lee Paul. "Hydration of biopolymers to low water content." Thesis, University of Nottingham, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308768.
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Chatterjee, Ashraf Anne Kublawi. "Structure elucidation of biopolymers by mass spectrometry." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/47800.
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Whitelaw, Emma L. "Catalysts for the production of sustainable biopolymers." Thesis, University of Bath, 2011. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577145.
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The development of biodegradable plastics from sustainable sources is at the forefront of chemical research. One such example is the production of polylactide (PLA) via the ring-opening polymerisation (ROP) of the cyclic ester lactide (LA). Current industrial metal initiators utilised for the ROP of LA do not allow control over the stereochemistry of the resulting product. This thesis will investigate various initiators containing a variety of ligand sets for the ROP of rac-LA. Chapter 1 introduces the ROP of rac-LA, the mechanisms utilised and the methods employed for characterisation of PLA. A review of the current literature of recent developments in the production of PLA via various metal initiators is also included. Chapter 2 reports the development of a series of group (IV) complexes containing various amine tris(phenolate) ligands, where the sterics and electronics have been varied. Such complexes were trialled for the ROP of rac-LA as well as the ROP of trimethylene carbonate (TMC). The ability of such initiators to produce copolymers of rac-LA/TMC and rac-LA/isosorbide was also investigated and discussed. Chapter 3 describes the synthesis of a range of group (IV) complexes containing Salalen ligands. The sterics of the ligands have been varied and the ability of the initiators to initiate the ROP of rac-LA in a stereocontrolled fashion has been investigated. Furthermore, the complexes have been trialled for the degradation of PLA into methyl lactate, an important starting material in the production of LA. Chapter 4 investigates the development of Al(III) Salalen complexes for the ROP of rac-LA, where the sterics and electronics of the ligand have been varied. Kinetic investigations have been carried out to aid the understanding of the polymerisation process. Chapter 5 provides details of the reaction procedures for the synthesis of ligands, complexes and polymers. Kinetic procedures are also reported together with details of the analytical techniques employed.
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Ali, Mohd Faizal. "Development of mucoadhesive biopolymers for food formulation." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6171/.
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Development of mucoadhesive biopolymer has received great attention in the pharmaceutical application due to its ability to retain the drug dosage at the specific targeted area. This special property could be applied in food formulation for optimum delivery of the active ingredients in the mouth. This research was carried out to study, correlate and review several in vitro analytical methods that can be used in development process for characterisation of mucoadhesive polymer. Four well known mucoadhesive biopolymers namely, chitosan, pectin, sodium alginate and sodium carboxymethyl cellulose (CMC) were used in this study. A modified rheological characterisation was used to study the interaction between the biopolymers with mucin and the assessment was based on the viscosity synergism. The detachment force characterisation was carried out via pull-off and tensile test using texture analyser and atomic force microscopy (AFM). Kinetic interaction study was done using quartz crystal microbalance with dissipation monitoring (QCMD) and interpretation of data from the modified rheological characterisation. Meanwhile, the removal of biopolymer emulsion after water flushing in a flow cell was observed under a microscope. It was found that mucoadhesion properties of tested biopolymers were affected by the concentration of biopolymer solutions, molecular weight, contact time, ionic strength and pH. Sodium alginate was characterised as the most mucoadhesive material by all the methods while QCMD shows CMC has the highest interaction with mucin layer compared to sodium alginate and pectin.
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Taddei, Lorenzo, F. Ugolini, G. P. Bonino, G. Giacomelli, C. Franceschi, M. Bertoldini, R. Sole, and V. Beghetto. "Biopolymers for a more sustainable leather -154." Verein für Gerberei-Chemie und -Technik e. V, 2019. https://slub.qucosa.de/id/qucosa%3A34185.
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A novel class of bio-based polymers have been developed within the LIFE BIOPOL European project aiming to replace traditional re-tanning and fat-liquoring products reducing environmental impacts and increasing the safety of leather.
The purpose of the project is to enhance the recovery and reuse of different bio-derived by-products from leather and agro-industrial sector to produce eco-friendly and renewable bio-polymers with high re-tanning and fat-liquoring characteristics.
The LIFE BIOPOL project aims to make bio-based polymers in order to reduce the following parameters in re-tanning phase:
- 20-30% COD,
- 50-60% of inorganic salts (Sulphates and Chlorides),
- 90% of Cr (III) salts,
- 20% of water used in the leather process.
Other important goals of the project are:
- reduction 70-90% of hazardous and environmental polluting substances normally found in conventional chemicals,
- reactivity enhancement of 30-40% of the new biopolymers compared to the current leather
- application technology,
- reduction of 70-80% of the Product Environmental Footprint of the new biopolymers related to the state of the art.
The vegetal biomasses and the tanned hides by-products were pretreated in order to obtain suitable building blocks for the production of bio-based polymers. Several protocols involving polymerization were
used in order to achieve the synthesis of the biopolymers, which have been carried out at lab scale.
Macromolecular characterization of the biopolymers was performed in order to rationalize the synthetic strategy and practical application of the products giving important parameters such as molecular weight
and chemical composition of the new biopolymers.
Performances of new bio-based polymers have been inspected and compared with traditional chemicals through application on different types of leather. The benefits of the new products within leather making process were evaluated through chemical analyses of re-tanning and fat-liquoring effluents.
The upgrade of the developed chemistry will be performed within a new devised prototype plant specifically designed and built-up for producing the bio-based polymers at industrial scale
Take-Away:
Production of leather making biopolymers from biomasses and industrial by-products through Life Cycle Designed Processes
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Shen, Hang. "Development of functional biopolymers with controlled architecture." Thesis, Saint-Etienne, 2013. http://www.theses.fr/2013STET4027/document.
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Des polyacides lactiques hydroxy téléchélique de masses molaires variées ont été synthétisés par polymérisation par ouverture de cycle du LLA en présence de 1,4 -butane diol. Des polyhydroxybutyrate hydroxy téléchéliques ont été préparés transesterification du PHB et du 1,4-butanediol catalysée par l'acide p-toluène sulfonique .Ces oligomères ont été utilisés pour préparer des polyesters amides fonctionnalisés acrylates ou mercaptans. Dans une approche parallèle, du PCL multi acrylate a été préparé avec succès par copolymérisation par ouverture de cycle de méthacrylate de glycidyle avec du caprolactone. Des copolymères (GMA -co- CL) ayant des masses molaire et de la fonctionnalité variables, ont été préparés en modifiant les paramètres de la réaction tels que le catalyseur, la nature du co-amorceur et le rapport des stœchiométriques des différents réactifs. Les polymères multi acrylates ont été copolymérisés principalement avec l'HEMA sous irradiation UV pour obtenir des réseaux PLA, PHB et PCL segmentés. Les mécanismes de dégradation de ces réseaux ont été étudiés en examinant particulièrement les décompositions des liaisons uréthanes et esters. Des dépolymérisations du PHEMA ont été détectées avec TGA -FTIR à plus haute température (450°C). Pour les réseaux à base de PCL, les propriétés thermo -mécaniques ont été étudiées. Le résultat montre que les phases riches en PCL ont une bonne compatibilité avec le poly HEMA. Les modules caoutchoutiques et l’étendue des températures des zones d’amortissement peuvent être contrôlées en fonction des paramètres réactionnels. Les Polymères multifonctionnels Thiols du PCL, PHA et PLA ont été utilisés pour faire croître des chaines méthacrylates et construire des polymères de type étoileHydroxyl telechelic polylactic acids of various molecular weights were synthesized by ring opening polymerization in the presence of LLA and 1,4-butanediol. Telechelic hydroxy polyhydroxybutyrate were prepared transesterification of PHB and 1,4- butanediol catalyzed by p- toluene sulfonic acid. These oligomers were used to prepare polyesteramides functionalised acrylates or mercaptans. In a parallel approach, the PCL multi acrylate was successfully prepared by ring-opening copolymerization of glycidyl methacrylate with caprolactone. Copolymers (GMA-co-CL) with variable molar masses and functionality were prepared by changing the reaction parameters such as catalyst, the nature of the co-initiator and the ratio of different stoichiometric reagents. Multi-acrylated polymers were copolymerized with HEMA under UV irradiation to obtain PLA, PHB and PCL segmented networks. Degradation mechanisms of these networks have been studied by examining particular decomposition of urethane bonds and esters. Depolymerization of the PHEMA was detected with TGA -FTIR at higher temperature (450°C). For PCL based networks, the thermo- mechanical properties were studied. The result shows that the PCL-rich phases have good compatibility with poly HEMA. The rubber and the working temperature range of the damping zones modules can be controlled as a function of reaction parameters. Multi mercapto functionalized polymers with PCL, PLA and PHA segments were used to grow methacrylate polymer chains and build star type
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LI, KUN. "Development of novel formulations based on biopolymers." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1046199.
Full textAbstract:
Biopolymers, generally prepared from renewable sources, have attracted increasing attention due to their unique properties, such as nontoxicity, biodegradability and biocompatibility. Indeed, the above materials have been widely applied in the biomedical field, in the development of electronic devices as well as in the food packaging. Two of the most extensively studied and exploited biopolymers are poly(lactic acid) (PLA) and polycaprolactone (PCL), which have been the objects of the present work. Despite the significant interest in these polymers, for large-scale exploitation of both PLA and PCL, it is necessary to take into account some specific issues concerning their properties. In this regards, it is relevant to underline that the methods, which can be applied for improving their characteristics or those used for disclosing new features, have to take into account the economic impact and the "bio" nature of the material, which should be maintained in the final formulation. In particular, in the case of PLA, one of the major issues, which reduces its exploitation in durable applications, is its low hydrolytic stability, compared with other similar materials. Moreover, in the applications requiring high gas barrier, the use of PLA is critical and needs a further reduction of its gas permeability. Furthermore, concerning exploitations, where electrical and thermal conductivity is demanded, the insulating nature of the above biopolymers, requires the applications of proper conductive fillers. As such, the main aim of the thesis work main has been the improvement of the two biopolymer properties, developing novel formulations, whose design has taken into account all the mentioned issues.
In the case of PLA, the barrier properties, the resistance to hydrolytic degradation as well as the antistatic features have been improved by modifying the material surface by means of the application of methods based on the chemical grafting or the Layer by Layer deposition and on the use of proper fillers, such as Polyhedral Oligomeric Silsesquioxane (POSS) and graphene oxide (GO). In addition, formulations capable of imparting thermal and electrical conduction to both PLA and PCL have been studied, combining the two biopolymers with graphite nanoplatelets (GNP).
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Bolister, Nina Jane. "The diffusion of beta-lactam antibiotics through biopolymers." Thesis, University of Brighton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328209.
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Zhong, Huijuan. "Capillary electrophoresis and kinetic studies of food biopolymers." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298441.
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Durrani, Matin. "The physical gelation of biopolymers and their mixtures." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260651.
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Bohlén, Martin, and Kristina Laurila. "Biopolymers as protection during transport of construction materials." Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-18670.
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Construction materials are exposed to different conditions along the way from the sawmill, during storage and handling, until the materials are a part of the completed construction. During this time the materials may be exposed to moisture and dirt that can cause an attack by moulds. This, in turn, can give rise to health problems for individuals staying in the building and can also be the cause of a bad smell in the building. It is therefore necessary to protect the materials during this limited period of transport, storage, and handling.In this study two construction materials were used; untreated wood and plasterboard. As a possible protection for the materials coatings based on biopolymers were made. Biopolymers are totally degradable and are relatively cheap raw materials. The biopolymers used in this study were starch from potato, protein from corn, and acetylated mono- and diglyceride. Also, fungicides that function as inhibitors for mould growth were added to the coatings.Samples of wood and plasterboard were covered with the coatings using a paint sprayer. The samples were then exposed to a spore suspension containing spores from four of the most common mould species found attacking building material. The samples were then placed in three different climates differing in temperature and humidity. The conditions were in all three cases favourable for mould growth. The samples were placed in these conditions for a month and analysis of the growth on the samples was made once a week and according to a scale with five grades.The results varied very much between the samples, even between samples treated with the same coating, but an obvious trend gave indications of that it is possible to use biopolymers as protection for construction materials. In this study the coating based on the acetylated monoglyceride showed the best properties.Uppsatsnivå: C
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Hossain, Mohammad Enayet. "Iron Nanoparticles and Biopolymers for Plant Nutrient Fortification." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25910.
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Novel iron (Fe) cross-linked alginate (FCA) beads were used for aqueous phosphate removal. Batch experiments were conducted with the beads using three different concentrations of phosphate (5, 50 and 100 mg PO43--P/L) as well as environmentally relevant (eutrophic lakes) concentration of 100 ?g PO43--P/L. About 80-97% phosphate was removed within 3 h. for lower concentrations of phosphate. The maximum phosphate sorption capacity was found to be 78.7 mg PO43--P/g of beads. Phosphate removal was not affected because of the presence of Cl-, HCO3-, SO42-, NO3- and natural organic matter (NOM). FCA beads were also used with actual lake waters (11-69 ?g PO43--P/L) and 81-100% phosphate removal was observed in 24 h. The FCA beads having a point of zero charge (PZC) of 9.2 make it an ideal candidate for phosphate removal in eutrophic lakes.
Phosphate-laden spent iron cross-linked alginate (FCA) beads were used in hydroponics to evaluate the bioavailability of P and Fe using lettuce (Lactuca sativa) as a test plant. Phosphate-laden spent FCA beads were found to support the plants throughout the growth period. The bioavailability of P and Fe in the spent beads is promising considering the importance of phosphorus and iron in global nutrient security.
Experiments were also conducted with lettuce and spinach (Spinacia oleracea) to evaluate the availability of iron from nanoscale zero-valent iron (NZVI). In both plants, bare NZVI enhanced the uptake of Fe as well as other essential elements. The results indicate that biofortification of spinach and lettuce with Fe is possible. The enhanced uptake of iron and other elements by lettuce and spinach is likely to have implications on global nutrient security.
In another experiment, an iron-regulating gene (LsHA2) in lettuce was investigated to gain insights into the strategy taken by plants for acquisition of Fe from a readily unavailable source, e.g., NZVI. The gene of interest was found to be regulated by the presence or absence of available iron in the solution. This research is likely to give us insights into the mechanism of plant nutrient fortification with nanoparticles.National Science Foundation (NSF)
USDA-NIFA
North Dakota Water Resources Research Institute
North Dakota Department of Commerce
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Kuriabova, Tatiana. "Nanomechanics of biological materials biopolymers, membranes, and shells /." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1621832591&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Mühle, Steffen [Verfasser]. "Nanoscale Brownian Dynamics of Semiflexible Biopolymers / Steffen Mühle." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1214887090/34.
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Oriez, Vincent. "Production of biopolymers and synthons from lignocellulosic wastes." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0016/document.
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Les résidus forestiers et agricoles, également appelés résidus lignocellulosiques, constituent de par leur quantité et leur structure un potentiel unique pour la production d’énergie et de molécules d’origine renouvelable, afin de pallier à la raréfaction des hydrocarbures fossiles ainsi qu’aux problèmes environnementaux liés à l’utilisation de ceux-ci. Les biomasses lignocellulosiques sont constituées principalement de cellulose, hémicelluloses et lignines. Le fractionnement et la purification de ces trois constituants est nécessaire à leur valorisation comme produits de substitution des hydrocarbures fossiles. Cette étude s’est tout d’abord attachée à la description et la compréhension des fractionnements chimiques acides et alcalins de la lignocellulose et aux voies de purification qui leur sont actuellement associées. Les travaux expérimentaux ont été réalisés à partir de deux matières premières : la bagasse de canne à sucre et le tourteau de tournesol. Une caractérisation fine de ces matières premières ainsi que des extraits acides et alcalins obtenus à partir de ces matières a été réalisée. Les étapes de purification se sont focalisées sur l’extrait alcalin de bagasse obtenu en conditions douces. En effet, la bagasse de canne à sucre peut être considérée comme un bon modèle de biomasse lignocellulosique, et la purification d’extraits alcalins lignocellulosiques obtenus en conditions douces a été peu étudiée malgré l’intérêt de ce procédé de fractionnement. La filtration membranaire et la chromatographie d'élution sur résine échangeuse de cation ont été évaluées séparément puis en association, afin de séparer les cinq grandes familles de molécules constitutives de l’extrait : des oligomères de lignines, des oligomères de sucres, des monomères phénoliques, de l’acide acétique et des sels inorganiques. Des essais d’ultrafiltration sur plusieurs membranes en faisant varier divers paramètres de filtration ont permis de déterminer que les oligomères de lignine et de sucres, récupérés dans le rétentat, sont séparés des monomères phénoliques, de l’acide acétique et des sels inorganiques, récupérés dans le perméat. Une membrane en fibres creuses de 10 kDa en polysulfone a présenté les meilleures performances de séparation et a été retenue pour les essais suivant en mode concentration et diafiltration. Des essais de chromatographie d'élution avec de l’eau pour éluant en testant plusieurs résines cationiques fortement acides ont montré qu’une fraction très pure d’oligomères de lignines et de sucres peut être obtenue avec une résine de type macroporeuse, alors qu’une résine de type gel a permis la séparation de monomères phénoliques entre eux en fonction de la présence ou non dans leur structure d’une fonction carboxyle. A partir d’extrait alcalin de bagasse, un procédé intégré de purification a été développé combinant de la filtration membranaire puis de la chromatographie sur le perméat et de la précipitation par ajout d’acide sur le rétentat. Il en a résulté l'obtention de quatre fractions purifiées : les monomères phénoliques avec fonction carboxyle, les sels inorganiques et les monomères phénoliques sans fonction carboxyle, les oligomères de lignine, et les oligomères de sucresAgricultural and forestry residues, also known as lignocellulosic residues, have a unique potential based on their quantity and structure for the production of renewable energy and molecules, inorder to solve the issues raised by the increasing scarcity of fossil hydrocarbons and the environmental disorder caused by their use. Lignocellulosic biomasses are essentially made ofcellulose, hemicelluloses and lignin. Fractionation and purification of these three compounds are necessary for their valorization as substitutes of fossil hydrocarbons. In the first place, this studydescribed the chemical fractionation of lignocellulose under acidic and alkaline conditions, and their related purification pathways. The experimental work was carried out on two raw materials:sugarcane bagasse and sunflower oil cake. A thorough characterization of the raw materials as well as the acid and alkaline extracts produced from these materials was performed. The purification steps focused on the sugarcane bagasse mild alkaline extract. Indeed, sugarcane bagasse can be considered a model lignocellulosic biomass and the purification of lignocellulosicmild alkaline extract has not been widely studied despite the numerous assets of this fractionation process. Membrane filtration and elution chromatography on strong acid cationic exchange resins were assessed individually then combined, for the separation of the five main pools of molecules that constitute the extract: lignin oligomers, sugar oligomers, phenolic monomers, acetic acid and inorganic salts. Ultrafiltration trials run on several membranes under various filtration conditions showed that lignin and sugar oligomers, recovered in the retentate, were separated from phenolicmonomers, acetic acid and inorganic salts, recovered in the permeate. A hollow fiber membrane of 10 kDa in polysulfone exhibited the best separation performance and was selected for further trials in concentration and diafiltration modes. Elution chromatography tests using water as eluent and various strong acid cationic exchange resins resulted in the production of a very pure lignin andsugar oligomers fraction with a macroporous-type resin, whereas a gel-type resin led to the separation of phenolic monomers from each other depending on the presence or absence in their structure of a carboxyl group. From a sugarcane bagasse mild alkaline extract, an integrated purification process was developed combining membrane filtration then chromatography on the permeate and precipitation by acid addition on the retentate. It resulted in the production of four purified fractions: phenolic monomers with a carboxyl group, inorganic salts and phenolicmonomers without carboxyl group, lignin oligomers, and sugar oligomers
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CAMPALANI, CARLOTTA. "Chemical biowaste upgrading: carbon dots, biopolymers and actives." Doctoral thesis, Università degli Studi di Trieste, 2023. https://hdl.handle.net/11368/3041031.
Full textAbstract:
The herein reported thesis finds its roots in the concepts of sustainability and circular economy and has as purpose the valorisation of agro- and fishery-waste for the production of added-value products. In particular, different types of waste biomass were used as starting material for the synthesis of carbon dots (CDs) used as photocatalysts, for the obtainment of biopolymers, namely collagen and chitin, and for the extraction of valuable compounds using supercritical CO2. The investigation started studying the dependence of structure and photocatalytic behaviour of CDs on the carbon source. Six different types of carbon nanoparticles were synthesized and compared from the morphological and optical point of view revealing a strong correlation of their properties with the starting material and the synthetic method. The citric acid-derived CDs were then employed to photoactivate the atom transfer radical polymerization of a methacrylate leading to the obtainment of the polymer in high conversions (89%) and narrow dispersity (1.4). The study on CDs proceeded then with the employment of more complex starting material, namely fish scales. Naturally nitrogen doped carbon dots were successfully synthesized starting from bass scales, fully characterized and employed as photocatalyst for the reduction of methyl viologen. The bass-CDs were compared with classic citric acid-derived CDs resulting in higher initial photoreduction rate (7.5·10−8 M·s−1 vs 4.9·10−8 M·s−1). The fish-derived nanoparticles were then applied as photocatalyst for the continuous flow degradation of azo dyes highlighting a quantitative degradation of five model dyes in only 2 min. This study was conducted during a research period abroad (September 2021-April 2022) in the laboratories of the Université de Liège under the supervision of Prof. Jean-Christophe Monbaliu. The upgrading of fishery waste was then developed more during the second part of this thesis where the possibility to extract biopolymers from fish scales or crab carapaces was explored. After a review study on the production of UV-shields using biopolymers, an investigation on the preparation of UV-blocking films from mullet scales-derived gelatin and bass-CDs was conducted. The obtained materials were fully characterized from the morphological, mechanical and optical point of view; by adding just 5% of CDs the films blocked almost 70% of the UV radiation with negligible change in opacity and in transparency. A further study on the possibility to obtain chitin from crab shells using a one-step protocol using ionic liquids was then conducted. All characterization data confirmed that in the conditions tested, ammonium formate prepared in situ seems to be a promising candidate for one-pot chitin pulping process, allowing quantitative isolation, high purity and a high degree of acetylation (DA > 90%). To have a complete overview on the possibility to exploit waste biomass for the production of added-value products, an investigation on the valorisation of agro-waste was then conducted. In this frame, a supercritical CO2 extraction method was developed to obtain natural preservatives from hops and jimsonweed. scCO2 extracts were compared to ethanolic ones: the supercritical fluid led to the selective extraction of volatile compounds resulting in a better recovery for preservatives. The scCO2 technique was then applied to obtain fatty acids for cosmetic formulations from fruit pomace, resulting again more selective when compared to classical organic solvents.The herein reported thesis finds its roots in the concepts of sustainability and circular economy and has as purpose the valorisation of agro- and fishery-waste for the production of added-value products. In particular, different types of waste biomass were used as starting material for the synthesis of carbon dots (CDs) used as photocatalysts, for the obtainment of biopolymers, namely collagen and chitin, and for the extraction of valuable compounds using supercritical CO2. The investigation started studying the dependence of structure and photocatalytic behaviour of CDs on the carbon source. Six different types of carbon nanoparticles were synthesized and compared from the morphological and optical point of view revealing a strong correlation of their properties with the starting material and the synthetic method. The citric acid-derived CDs were then employed to photoactivate the atom transfer radical polymerization of a methacrylate leading to the obtainment of the polymer in high conversions (89%) and narrow dispersity (1.4). The study on CDs proceeded then with the employment of more complex starting material, namely fish scales. Naturally nitrogen doped carbon dots were successfully synthesized starting from bass scales, fully characterized and employed as photocatalyst for the reduction of methyl viologen. The bass-CDs were compared with classic citric acid-derived CDs resulting in higher initial photoreduction rate (7.5·10−8 M·s−1 vs 4.9·10−8 M·s−1). The fish-derived nanoparticles were then applied as photocatalyst for the continuous flow degradation of azo dyes highlighting a quantitative degradation of five model dyes in only 2 min. This study was conducted during a research period abroad (September 2021-April 2022) in the laboratories of the Université de Liège under the supervision of Prof. Jean-Christophe Monbaliu. The upgrading of fishery waste was then developed more during the second part of this thesis where the possibility to extract biopolymers from fish scales or crab carapaces was explored. After a review study on the production of UV-shields using biopolymers, an investigation on the preparation of UV-blocking films from mullet scales-derived gelatin and bass-CDs was conducted. The obtained materials were fully characterized from the morphological, mechanical and optical point of view; by adding just 5% of CDs the films blocked almost 70% of the UV radiation with negligible change in opacity and in transparency. A further study on the possibility to obtain chitin from crab shells using a one-step protocol using ionic liquids was then conducted. All characterization data confirmed that in the conditions tested, ammonium formate prepared in situ seems to be a promising candidate for one-pot chitin pulping process, allowing quantitative isolation, high purity and a high degree of acetylation (DA > 90%). To have a complete overview on the possibility to exploit waste biomass for the production of added-value products, an investigation on the valorisation of agro-waste was then conducted. In this frame, a supercritical CO2 extraction method was developed to obtain natural preservatives from hops and jimsonweed. scCO2 extracts were compared to ethanolic ones: the supercritical fluid led to the selective extraction of volatile compounds resulting in a better recovery for preservatives. The scCO2 technique was then applied to obtain fatty acids for cosmetic formulations from fruit pomace, resulting again more selective when compared to classical organic solvents.
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Wisman, Acharige Monika Madhavi. "Molecular dynamics studies of liquids and hydrated biopolymers." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/129218/1/Monika%20Madhavi_Wisman%20Acharige_Thesis.pdf.
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This research presents a computational study of the dynamics of molecules in pure liquids, as well as its extension to the dynamics of water molecules associated with biological macromolecules. The results presented in this study advance the fundamental understanding of how molecules in liquids behave. The results presented also provide new insights into Magnetic Resonance Imaging properties of collagenous connective tissues, with applications in experimental and clinical radiology.
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Saithai, Pimchanok. "Synthesis and characterization of bio-based copolymers from soybean oil and methyl methacrylate." Thesis, Montpellier, SupAgro, 2013. http://www.theses.fr/2013NSAM0008.
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L'objectif de ce travail était d'étudier l'impact du mode de préparation et de la formulation de bioplastiques transparents issus d'huile de soja sur leur structure et leurs propriétés thermiques et mécaniques. Nous nous sommes plus particulièrement intéressés à l'huile de soja époxydée (ESO), qui a ensuite été acrylée et co-polymérisée avec méthacrylate de méthyle (MMA) en présence ou non de nano-particules de dioxyde de titane. Deux méthodes de préparation d'ESO ont été comparées. La première a fait appel à une époxydation chimique en présence de peroxyde d'hydrogène et d'acide formique. L'acide sulfurique a été utilisé comme catalyseur pour la production de peracides, ces oxydants forts générant ensuite des époxydes par attaque des doubles liaisons des acides gras de l'huile. La seconde consistait en une époxydation chimio-enzymatique, les peracides étant alors générés dans des conditions douces de pH et de température par catalyse enzymatique en présence d'H2O2 et d'huile. Deux types de lipases ont été utilisées comme biocatalyseurs : la lipase de Candida antarctica (Novozyme 435) et la lipase/acyltransférase de C. parapsilosis. Un contrôle de la réaction a permis d'obtenir des produits à différents degrés d'époxydation (50 et 75 3 %). Les effets du mode d'époxydation, du degré d'acrylation et des teneurs en MMA et TiO2 sur les propriétés des bioplastiques obtenus ont été étudiés par FTIR, RMN 1D et 2D, DMTA, TGA et par mesure des propriétés mécaniques.Mots-clés : Biocomposite, Bioplatique, Nanocomposite, Huile de soja époxydée et acrylée (AESO), Dioxyde de titane (TiO2), Biocatalyse, LipaseThe aim of this research to study the effect the production method and the formulation of transparent soybean oil-based bioplastics on their structure and their thermal and mechanical properties. We focused on epoxidized soybean oil (ESO), that was acrylated and copolymerized methyl methacrylate (MMA) with and without titanium dioxide (TiO2). Two methods of ESO preparation were compared. The first used chemical epoxidation in the presence of H2O2 and formic acid, using sulfuric acid as a catalyst to produce peracids as strong oxydants for the epoxidation. The second one was a chemo-enzymatic method where the peracids were generated in mild conditions by an enzyme in the presence of H2O2. Two types of lipases were selected as biocatalysts for the chemo-enzymatic epoxidation: Novozyme®435 and a non-commercial lipase/acyltransferase (CpLIP2). The reaction was controlled so as to obtain different degrees of epoxidation (DOE), i.e. 50+/-3 mol% and 75+/-3 mol%, from both methods. Acrylated ESO (AESO) was chemically synthesized by acrylation of ESO and acrylic acid. Then AESO was copolymerized with MMA and cured to form a rigid polymer using 1 wt% of benzoyl peroxide as a free radical initiator. A nanocomposite was prepared by blending AESO-co-PMMA with 0.1-0.2 wt% nano-TiO2 (particle size 2-5 nm). The effect of degree of acrylation, MMA content and titanium dioxide content on structural, tensile and thermal properties of the obtained bioplastics were studied using Fourier transform infrared spectrometer (FTIR), 1D and 2D NMR, dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA) and mechanical properties determination
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Svidroňová, Barbora. "Síťování polysacharidových mikrovláken." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2014. http://www.nusl.cz/ntk/nusl-217059.
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Všeobecne, cieľom tejto diplomovej práce bola príprava a charakterizácia sieťovaných hyaluronových mikrovláken, ktoré by boli stabilné vo vodnom prostredí s vhodnými mechanickými vlastnosťami. Vlákna pripravené technikou zvlákňovania z roztoku boli sieťované pomocou roztoku so sieťovacím činidlom 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimidom alebo roztoku s dvoma sieťovacími činidlami 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimidom a N-hydroxysuccinimidom, vedúcim k amidácii a tvorbe esterových väzieb. Charakterizácia pripravených vzoriek je hlavným cieľom experimentálnej časti práce. Charakteristiky botnání boli vykonané na určenie stability vláken v troch rôznych roztokoch (s pH 7.4, 3 a 11). Na určenie termickej stability bola využitá termogravimetrická analýza a na stanovenie esterifikácie a amidácie bola použitá infračervená spektroskopia s Fourierovou transformáciou. Mechanické vlastnosti vláken boli študované pomocou testovania závislosti stress-strain. Ďalej boli testované reologické vlastnosti ako aj mikroštruktúra a povrch vláken pomocou skenovacieho elektrónového mikroskopu. Vlákna pred chemickým sieťovaním vykazovali nižšiu stabilitu vo všetkých troch roztokoch, termálna stabilita bola taktiež nižšia ako stabilita zosieťovaných vláken. Pre vlákna chemicky nemodifikované so sieťujúcim činidlom, sa objavil iba jeden typ píku pre esterifikáciu. Infračervené spektrum chemicky zosieťovaných vláken ukázalo prítomnosť dvoch píkov pre esterifikáciu, čo je prejavom efektivity sieťovacieho činidla. Amidácia bola tiež výraznejšia pri zosieťovaných vláknach, špeciálne pre vlákna sieťované dlhú dobu a v roztoku s vyššou koncentráciou sieťujúceho činidla. Kvôli nerovnomerným vláknam, mechanické vlastnosti nevykazovali žiadnu závislosť na sieťovaní. Štúdium reológie ukázalo, že viskozita vlákna rozpusteného vo vode je menej závislá na šmykovej rýchlosti ako prášok hyaluronanu sodného rozpusteného vo vode. Napriek mnohým rôznym metódam charakterizácie vláken, ktoré boli použité v tejto práci, je stále veľa možností pre lepšiu charakterizáciu a bližšie pochopenie tohto biopolymérneho materiálu.
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Astley, Owen Matthew. "Scattering studies of cell wall polymers." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249041.
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Rosa, Angelo. "Statistical Mechanics of Polymer Stretching." Doctoral thesis, SISSA, 2003. http://hdl.handle.net/20.500.11767/4565.
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The interplay between Physics and Biology is certainly one of the most exciting
field in modern Science. In particular, the discovery that proteins, DNA and RNA
have rather peculiar spatial arrangements [1, 2, 3] has convinced biological physicists
that these simple forms may be deduced from an underlying principle. Besides, new
experimental techniques have supplied high-quality data, which can be investigated
and compared to theoretical models.
In particular, in this Thesis, we have focused our attention on the theoretical study
of some elastic and thermodynamic properties of polymers and, in particular, biopolymers
such as proteins, DNA and RNA [4].
This research work is organized as follows:
In Chap. 1, we introduce some basic concept on polymers and biopolymers.
In particular, biopolymers has attracted the attention of many research groups.
Probably, their most appealing property is that they are organized in simple
hierarchical structures [5]. In fact, the primary amino acid sequence of proteins
is disposed in some fascinating forms as alpha-helices and beta-strands, which at an
outer level form compact structures called domains. Moreover, 50 years ago,
Watson and Crick [2] discovered the marvelous double helix of DNA.
Furthemore, polymers seem to display many intriguing features, since they can
not be described in terms of ordinary solids. This is due to the covalent nature of the bonds between consecutive monomers. Due to temperature fluctuations of
these bonds, a polymer can not be viewed as a rigid macromolecule. Since these
fluctuations favor many different spatial conformation, a Statistical Mechanics
approach has revealed very useful [3]. Then, we focus on the important problem
of polymer elasticity and introduce some preliminary concepts as the Kuhn
length and the persistence length [4].
In Chap. 2, we focus our attention about some recent experiments on polymer
stretching.
Firstly, we begin with a brief introduction to some recent experimental techniques.
Mainly, we focus on optical tweezers [6], atomic force microscopes
[7] and soft microneedles [8]. We also give a short explanation about their
technical features, including practical limitations and available force ranges.
Besides, we describe in great details many force driven phase transition which
occur in real polymers. Then, Statistical Mechanics allows for a rigorous approach
to these phenomena. As explained above, we also address the important
problem of elasticity in polymers, introducing the freely jointed chain (FJC)
model and the worm like chain (WLC) model [3].
In Chap. 3, we describe the stretching behaviour of polymers, with the introduction
of some chosen 2d on-lattice models and 3d off-lattice models.
In the framework of a simplified approach on a self-interacting directed selfavoiding
walk (DSAW) [9], we have discussed the importance of some scaling
laws that we think to be of more general validity. Then, we introduce a more
realistic model for a self-interacting SAW [9]. In particular we are able to
describe its phase diagram.
Through the introduction of an off-lattice self-avoiding polymer, we also give
a simple explanation of some recent puzzling experimental results described in
Chap. 2.
In Chap. 4, we shall focus our attention on the stretching behaviour of polymer
in a good solvent [10].
Generalizing the WLC approach of Marko and Siggia [11], we obtain a new
interpolation formula, which perfectly describes some numerical data, obtained
with Monte Carlo simulations. Furthermore, this formula seems to be more
powerful than Marko and Siggia’s one. In fact, it fits well some experimental data taken from literature, that the previous approach was not able to describe correctly.
Finally, we outline final conclusions and perspectives.
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Rice, Aislinn B. "Investigation of human biopolymers by micellar electrokinetic capillary chromatography." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361302.
Full text
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Scanlon, Shane. "Nanostructured porous materials based on designed self-assembling biopolymers." Thesis, University of Leeds, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.434581.
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Ruddick, Andrew. "Separation and mobility modelling of biopolymers by capillary electrophoresis." Thesis, University of York, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338551.
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Eissa-Mohamed, Ahmed Mohamed. "Synthesis and characterisation of novel biopolymers via click chemistry." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/581/.
Full textAbstract:
The work throughout is the exploitation of copper catalysed Huisgen 1,3-dipolar azide–alkyne cycloaddition, as an efficient Click reaction, for the synthesis of novel biopolymers with a broad range of potential medical/industrial applications. The strategy is to develop a powerful tool for the synthesis of libraries of materials, which will be discussed in separate chapters. Chapter one is a general introduction on biopolymers and Click chemistry with emphasis on the related literature to the present work. Chapter two involves the application of Click chemistry on model compounds; 3-methyl benzyl alcohol and phenol. The resulting products were successfully prepared via Click chemistry. NMR spectroscopy was found to be a good choice for characterisation of the resulting products. Chapter three describes the application of Click chemistry on a disaccharide compound, α,α-D-trehalose. The di-azide functionalised trehalose was synthesised by tosylation followed by acetylation and subsequent reaction with sodium azide. Different functionalities such as ester, acrylate and epoxide groups were successfully introduced via Click chemistry. NMR and FT-IR spectroscopies were found to be efficient characterisation tools to follow up the Click modification reactions. The di-acrylate functionalised trehalose showed a great potential as a cross-linker in the free radical polymerisation of HEMA to generate hydrogels. Chapter four presents the utilisation of Click chemistry to produce trehalose-based glycopolymers which have a wide range of potential applications. Biodegradable glycopolymers containing PCL or PLA were synthesised via combination of ring opening polymerisation (ROP) and Click chemistry. The ROP of lactide and ε-caprolactone, using stannous octoate and propargyl alcohol, was carried out to synthesise alkyne end capped PLA and PCL which were then coupled with di-azide functionalised trehalose by Click reaction. NMR and IR were used to prove the structure of the materials. A new class of temperature responsive glycopolymers was also synthesised via copper wire catalysed Click-polymerisation of di-azide functionalised trehalose with di-alkyne terminated PEG. The cloud point of the aqueous solution of glycopolymer was evaluated and showed an LCST at ~39 oC, known as fever temperature. In addition, the phase transition was shown to be reversible. Chapter five involves the modification of 2-hydroxyethyl cellulose (HEC) via Click chemistry. For the first time, the azide functionalisation reaction of HEC was disclosed using a one pot reaction procedure. Neutral and ionic compositions of HEC were successfully synthesised by introducing different functionalities on HEC. The compositions containing carboxylic acid or 1ry amine functionalities can be treated in basic or acidic media to give polyelectrolytes based on HEC. The compositions containing both functionalities, carboxylic acid and 1ry amine, could produce polyampholytes. Sequential Click reactions were implemented to synthesise polydimethylsiloxane (PDMS) grafted HEC as well as potentially charged functionalities. These compositions are expected to receive a great interest in personal care and cosmetics applications. Mainly, solid state 13C-NMR and FT-IR spectroscopies were used to characterise these materials. Hydrophobically and hydrophilically modified HEC were also prepared by grafting PLA, PCL or PEG onto HEC using Click coupling reaction. AFM analysis showed that some exhibit a brushlike architecture. Chapter six describes the combination of Click chemistry and ROMP to synthesise various graft polymers. Two different grafting techniques; "grafting through" (the macromonomer approach) and "grafting onto" were involved in the synthesis. The "grafting through" method involved the synthesis of oxanorbornenyl di-PEG macromonomer by Click coupling of azide terminated PEG with di-alkyne functionalised oxanorbornene. The macromonomer was then subjected to ROMP to produce PEG grafted polyoxanorbornene. Polynorbornene-g-PCL and polynorbornene-g-PEG were prepared by "grafting onto" process. This was achieved by ROMP of bromide functionalised norbornene followed by reaction with sodium azide and then Click reaction with alkyne terminated PCL and PEG. The surface analysis of these graft polymers were studied using AFM. Random graft copolymer containing PEG and PCL side chains was also prepared by ROMP of a mixture of oxanorbornenyl di-PEG and bromide functionalised norbornene followed by reaction with sodium azide and then Click reaction with alkyne end capped PCL. Chapter seven entails general conclusions and suggestions for future work.
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Morais, Cristiana Carvalho. "Production of bacterial biopolymers from industrial fat-containing wastes." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10922.
Full textAbstract:
Dissertation presented in partial fulfilment of the Requirements for the Degree of Master in BiotechnologyPolyhydroxyalkanoates (PHAs) constitute a group of biobased and biodegradable polymers, which have been recognized as good substitutes for petroleum-based polymers in many applications. The large-scale production of PHAs is limited by the high cost of the most commonly used carbon sources (e.g. glucose, sucrose). However, the food industry generates large amounts of wastes, including fat-containing materials that can be used as low cost carbon sources for microbial cultivation, due their high carbon content. In this study, several bacterial strains (Cupriavidus necator, Comamonas testosteroni, Pseudomonas oleovorans, P. resinovorans, P. stutzeri, and P. citronellolis) were evaluated for their ability to grow and produce PHAs using fat-containing wastes generated by the food industry. The materials used in this study were mainly composed of free fatty acids, namely mystiric, oleic, linoleic and stearic acid. In the preliminary shake flask experiments, C. necator, C. testosteroni, P. oleovorans and P. citronellolis were able to grow and produce PHA polymer on margarine waste with the highest content. Those strains were selected for batch bioreactor experiments, wherein C. necator reached the highest polymer content (56%, wt/wt) and volumetric productivity (0.33 gPHA/L.h), Lower PHA contents were achieved by P. citronellolis and P. oleovorans (7.0 and 8.5%, wt/wt, respectively). However, in contrast with C. necator that synthesized polyhydroxybutyrate [P3(HB)], those strains produced medium chain length polyesters (mcl-PHA) containing monomers of 3-hydroxyoctanoate (HO) and 3-hydroxydecanoate (HD). C. necator was also cultivated in two different fed-batch strategies. The first cultivation achieved 76% (wt/wt) of P(3HB), while high cell densities were obtained in the second cultivation (48 g/L of active biomass concentration). Finally, the P(3HB) and mcl-PHA polymers had a glass transition temperature of 0.5–7.9ºC and -45.6, a melting point of 169.3–173.4ºC and 60.9ºC, and degree of crystallinity of 48.7–56.6% and 0.7%, respectively.
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Martino, Francesca. "Study of the absorption of organic compounds on biopolymers." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/24929/.
Full textAbstract:
This work has been conducted in order to determine the solubility and diffusion coefficients of different aromatic substances in two different grades of polylactic acid (PLA), Amorphous (PDLLA) and Crystalline (PLLA); in particular the focus is on the following terpenes: Linalool, α-Pinene, β-Citronellol and L-Linalool. Moreover, further analyses have been carried out with the aim to verify if the use of neat crystalline PLA, (PLLA), a chiral substrate, may lead to an enantioenrichment of absorbed species in order to use it as membrane in enantioselective processes. The other possible applications of PLA, which has aroused interest in carry out the above-mentioned work, concerns its use in food packaging. Therefore, it is interesting and also very important, to evaluate the barrier properties of PLA, focusing in particular on the transport and absorption of terpenes, by the packaging and, hence, by the PLA. PLA films/slabs of one-millimeter thickness and with square shape, were prepared through the Injection Molding process.
On the resulting PLA films heat pretreatment processes of normalizing were then performed to enhance the properties of the material. In order to evaluate solubility and diffusion coefficient of the different penetrating species, the absorption kinetics of various terpenes, in the two different types of PLA, were determined by gravimetric methods. Subsequently, the absorbed liquid was extracted with methanol (MeOH), non- solvent for PLA, and the extract analyzed by the use of High Performance Liquid Chromatography (HPLC), in order to evaluate its possible enantiomeric excess. Moreover, PLA films used were subjected to differential scanning calorimetry (DSC) which allowed to measure the glass transition temperature (Tg) and to determine the degree of crystallinity of the polymer (Xc).
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Abou, Diwan Charbel. "NOS-based Biopolymers; Towards Novel Thromboresistant No-Release Materials." Cleveland, Ohio : Cleveland State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1246374684.
Full textAbstract:
Thesis ( Ph.D.)--Cleveland State University, 2009.Abstract. Title from PDF t.p. (viewed on July 22, 2009). Includes bibliographical references (p. 159-160). Available online via the OhioLINK ETD Center and also available in print.
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Ramachandran, Asha Latha. "Investigation on bacterial biopolymers and biominerals for soil stabilization." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/84787.
Full textAbstract:
The practice of soil stabilization has become an essential part of present day geotechnical engineering
projects. However, it is a matter of growing concern that popular chemical stabilizers possess high carbon
footprint and adversely affect the eco-system. With the emergence of bio-geotechnology as an
environmentally benign alternative to chemical stabilization, there is a paradigm shift in the field of soil
stabilization. This thesis is a novel attempt to underpin the effect of bacterial biopolymers and
biomineralisation on stabilization of soil.