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1
Hecker, Richard. "The characterisation of polyacrylamide flocculants". Thesis, Curtin University, 1998. http://hdl.handle.net/20.500.11937/2010.
Testo completoAbstract (sommario):
Polyacrylamide is widely used as a flocculant but the influence of the molecular mass distribution upon flocculant activity is poorly understood. This thesis outlines the successful characterisation of ultrahigh molecular mass polyacrylamide solutions in terms of discrete solvated polymer coils and coil agglomerates. These features were correlated with the observed flocculation, demonstrating a number of solution state features required to improve flocculation activity.Aqueous solutions of polyacrylamide exhibit time-dependant behaviour affecting viscosity and polymer agglomeration. Improving the solvation of the polymer suppressed the agglomerates, as did manipulation of hydrogen bonding through the presence of salts. Limiting agglomeration through improved solvation apparently lowers a barrier to polymer interaction, such that the coils disperse but become more susceptible to reagglomeration under mild shear. These solvent modifications did not fully suppress the agglomerates.To fractionate polyacrylamide into a molecular mass distribution, flow field-flow fractionation (flow FFF) was chosen, coupled to a multi-angle laser light scattering (MALLS) photometer and a differential refractometer for molecular mass and concentration sensitive detection, respectively. For the first time, the analysis of high molecular mass polyacrylamides in water using the flow FFF-MALLS technique has been reported. However, a number of difficulties needed to be overcome, including shear artefacts, sample agglomeration and polymer-membrane interactions.Both polyacrylamide standards and commercial flocculants were amenable to the technique. Commercial flocculants were found to vary not only with regard to viscosity and mean molecular mass, but also with sub- and supramicron size agglomerates. The flow FFF technique is size-sensitive, which for some low molecular mass samples displayed an unusually wide elution profile, in apparent conflict with the molecular mass sensitive MALLS detector. It was concluded that polyacrylamide in solution exists simultaneously in three states: discrete polymer coils, entanglements of a several coils, and agglomerates with supramicron diameters.This thesis concluded with a comparison between the characterised polyacrylamides and observed flocculation activity on a standard kaolin substrate. Results show polymer with supramicron agglomerates produce the largest and most shear-resistant kaolin aggregates with a definite optimum agitation intensity. Higher molecular mass flocculants with less agglomeration bind fine particles under more gentle conditions but are deficient under increasing stress. Flocculants exhibiting coil entanglements showed poor activity and formed only small aggregates. A modified flocculation mechanism was proposed, in which supramicron polymer agglomerates play a critical role.
2
Smith, David P. "Characterisation of peracids". Thesis, University of Cambridge, 1996. https://www.repository.cam.ac.uk/handle/1810/272276.
Testo completo
3
Hecker, Richard. "The characterisation of polyacrylamide flocculants". Curtin University of Technology, School of Applied Chemistry, 1998. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=10745.
Testo completoAbstract (sommario):
Polyacrylamide is widely used as a flocculant but the influence of the molecular mass distribution upon flocculant activity is poorly understood. This thesis outlines the successful characterisation of ultrahigh molecular mass polyacrylamide solutions in terms of discrete solvated polymer coils and coil agglomerates. These features were correlated with the observed flocculation, demonstrating a number of solution state features required to improve flocculation activity.Aqueous solutions of polyacrylamide exhibit time-dependant behaviour affecting viscosity and polymer agglomeration. Improving the solvation of the polymer suppressed the agglomerates, as did manipulation of hydrogen bonding through the presence of salts. Limiting agglomeration through improved solvation apparently lowers a barrier to polymer interaction, such that the coils disperse but become more susceptible to reagglomeration under mild shear. These solvent modifications did not fully suppress the agglomerates.To fractionate polyacrylamide into a molecular mass distribution, flow field-flow fractionation (flow FFF) was chosen, coupled to a multi-angle laser light scattering (MALLS) photometer and a differential refractometer for molecular mass and concentration sensitive detection, respectively. For the first time, the analysis of high molecular mass polyacrylamides in water using the flow FFF-MALLS technique has been reported. However, a number of difficulties needed to be overcome, including shear artefacts, sample agglomeration and polymer-membrane interactions.Both polyacrylamide standards and commercial flocculants were amenable to the technique. Commercial flocculants were found to vary not only with regard to viscosity and mean molecular mass, but also with sub- and supramicron size agglomerates. The flow FFF technique is size-sensitive, which for some low molecular mass samples displayed an ++unusually wide elution profile, in apparent conflict with the molecular mass sensitive MALLS detector. It was concluded that polyacrylamide in solution exists simultaneously in three states: discrete polymer coils, entanglements of a several coils, and agglomerates with supramicron diameters.This thesis concluded with a comparison between the characterised polyacrylamides and observed flocculation activity on a standard kaolin substrate. Results show polymer with supramicron agglomerates produce the largest and most shear-resistant kaolin aggregates with a definite optimum agitation intensity. Higher molecular mass flocculants with less agglomeration bind fine particles under more gentle conditions but are deficient under increasing stress. Flocculants exhibiting coil entanglements showed poor activity and formed only small aggregates. A modified flocculation mechanism was proposed, in which supramicron polymer agglomerates play a critical role.
4
Anderberg, Cecilia. "Characterisation and function of cylinder liner surfaces". Thesis, Halmstad University, School of Business and Engineering (SET), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-1340.
Testo completoAbstract (sommario):
The demands on decreased environmental impact from vehicles force the automotive industry to develop engines with reduced engine oil and fuel consumption. Engine oil consumption is recognized to be a significant source of pollutant emissions. Unburned or partially burned oil in the exhaust gases contribute directly to hydrocarbon and particulate emissions. Engine oil and fuel consumption are to a great extend controlled by the topography of the cylinder liner surface.
Recent engine tests have shown a promising reduction in oil consumption when using cylinder liners with a smoother finish than the current plateau honing.
One approach to produce smoother liner surfaces is to replace SiC ceramic honing stones with diamond tools. However, event though the diamond honing process results in higher productivity, improved demands of quality control is needed to monitor the degree of cold worked material - “blechmantel” (German), and the resulting risk of increased wear and scuffing.
A number of petrol and diesel engine cylinder liners have been mapped to be able to verify the quality and consequences, in terms of wear and function, of the honing process. A new mapping method, combining SEM images and quantitative image analysis with traditional 2D profilometry has been developed and tested in this study. The liners where tested in a reciprocating rig of 8 mm stroke and with a frequency of 10 Hz, simulating the top-dead center conditions in a running engine.
The tests where carried out in high- and low pressure conditions with smooth respectively rough liner roughnesses against PVD coated piston rings. The developed surface mapping method was employed before and after the test to study effect of running-in wear on the surface, features characterized with the SEM- and the 2D profilometer.
The results show that combining SEM- and profilometric methods gives a good picture of the effects of varying the cylinder liner pressure and roughness. The roughness of the core decreases more for diesel liners than for petrol liners. In average (rough and smooth liners) the diesel core roughness decreases 265% while the petrol liners average on a 60% decrease. Blechmantel- and Irregularities ratio show a high sensitivity to varying conditions and decrease 1180% to 100% for the diesel liners while the parameters increase between 106% to 18% for all the petrol liners. A probable cause is the more severe diesel high pressure run-in conditions are able to effectively “truncate” the plateaux and remove residing plastically deformed un-cut honing residues while the less severe petrol liner conditions not manage to remove the blechmantel and irregularities in an important extent.
5
Campanera, Alsina Josep Maria. "Theoretical characterisation of metallofullerenes". Doctoral thesis, Universitat Rovira i Virgili, 2005. http://hdl.handle.net/10803/9071.
Testo completoAbstract (sommario):
INFORME FINAL"Alguns importants descobriments de la ciència són accidentals. Això fou, certament, el cas del ful·lerè C60. Quan ara fa quatre anys, l'any 2000, vaig iniciar el treball d'investigació sobre els metal·loful·lerens m'havien arribat veus de la importància mediàtica d'aquestes noves estructures però no de la intensa història del seu descobriment. Aquesta m'ha fascinat. Sobretot quan l'any 2003 vaig tenir la possibilitat de fer una estada al grup del professor Kroto de la universitat de Sussex (Gran Bretanya). Llavors els textos, sorprenents però inerts, que havia llegit sobre la història del descobriment dels ful·lerens prenien forma en espais coneguts i personatges propers". Aquest és el prefaci de la meva tesi. Segurament aquesta estada a Sussex al grup d'un dels descobridors dels ful·lerens ha estat el moment més entranyable en aquesta carrera científica per l'estudi dels metal·loful·lerens.
A partir de la síntesi de la molècula de C60 en quantitats apreciables la química dels ful·lerens en general, i en particular amb metalls de transició, ha experimentat un increment espectacular. L'objectiu d'aquesta tesi és l'estudi de l'estructura i la reactivitat de diferents derivats organometàl·lics de ful·lerens o metal·loful·lerens. El treball d'investigació usa les eines de la química computacional (Teoria del funcional de la densitat, DFT) per tal de modelar els metal·loful·lerens més interessants apareguts entre el 1999 i el 2005. Tot i que els metal·loful·lerens presenten una varietat d'estructures formidable, podem classificar-los en tres grans famílies des del punt de vista estructural: un primer grup són els metal·loful·lerens exoèdrics on els metalls es situen fora de la caixa, en un segon grup tenim els metal·loful·lerens heteroèdrics o heteroful·lerens on les caixes de carbonis han estat dopades (certes posicions han estat substituïdes) amb altres elements com ara: N, B, Si, Fe i altres metalls i finalment l'últim grup són els metal·loful·lerens endoèdrics on la derivatització metàl·lica es dóna a l'interior de la caixa. Així l'estudi teòric dels compostos més novedosos i novells de cadascuna de les tres famílies de metal·loful·lerens és el puntal de la present tesi doctoral. Per cadascuna de les famílies hem desgranat l'estructura electrònica i geomètrica, hem descrit el tipus d'enllaç metall-ful·lerè, hem avaluat els factors que intervenen en l'estabilitat relativa dels possibles isòmers, hem també predit la reactivitat davant de reaccions d'addició i finalment els hem caracteritzat des d'un punt de vista físic (càlcul del potencial d'ionització i afinitat electrònica). L'estructura electrònica ens ha permès seleccionar quins metal·loful·lerens endoèdrics seran estables avançant-nos als experimentalistes en la seva cerca de nous complexos. La diversitat de tipologies d'enllaç ha sigut tant gran com famílies de metal·loful·lerens. Hem descrit un enllaç iònic pels metal·loful·lerens endoèdrics, un enllaç covalent en el cas dels metal·loful·lerens heteroèdrics i un enllaç coordinatiu pels metal·loful·lerens exoèdrics. Hem aplicat noves metodologies per l'estudi de l'isomerisme. Les tècniques d'anàlisi multivariant de dades ens han permès esbrinar quins factors són importants per l'estabilitat relativa dels isòmers i a la vegada construir models de predicció per altres isòmers. Així doncs, l'acoblament de la química teòrica i la quimiometria ha estat sens dubte l'aportació més rellevant del present treball d'investigació.
Tarragona, 28 de novembre de 2004
Josep Maria Campanera Alsina
FINAL REPORT
The characterisation of the most novel metallofullerenes up to 2004 has been theoretically and systematically discussed in this study. From the structural point of view, metallofullerenes can be divided into three main groups, all of which have been discussed in this study: endohedral, heterohedral and exohedral metallofullerenes. The main families of compounds studied are Sc3-nMnN@Ck (n = 0-3, M = Y, La; k = 68, 78, 80) (endohedral), CxMn (x = 56, 57, 58, 59; M = Pt, Ir, Os; n = 1, 2) (heterohedral) and (-Ck){M(PH3)2}n (k = 60, 70, 84; M = Pt, Pd, Ni; n = 1, 2, 4, 6) (exohedral). The present study is a step forward in our knowledge of each of these families of compounds, and in particular, in our understanding of the metal-carbon bond, isomerism and reactivity. The DFT method proved to be an excellent computational tool for providing good geometries, for solving the intricacies of the different metal-carbon bonds, for producing experimental data (ionization potentials and electron affinities) and also for making predictions about isomerism stability and reactivity. The principal conclusions drawn about the species studied here are:
Different types of structures, different types of metal-carbon bonds. The metal units in each family of compounds are located differently in relation to the fullerene carbon framework: inside the cage, within the carbon framework and outside the cage. The encapsulation of a trimetallic nitride template unit (TNT, Sc3-nMnN; n = 0-3; M = Y, La) inside the carbon cage to produce TNT endohedral metallofullerenes is explained by an ionic pair (cage-metal) model in which the TNT unit formally transfers six electrons to the cage. On the other hand, in heterohedral metallofullerenes, metals establish a covalent metal-carbon bond without causing oxidation to the metal. Finally, the (MPH3)2 metal units situated exohedrally to the fullerene are only coordinated in a mode to the CC bond.
Chemometric tools applied to isomerism studies. The regioisomers of heterohedral metallofullerenes are numerous: for example, the stoichiometry C57Pt2 has 47 distinct regioisomers. Thus, chemometric techniques which can manage considerable amounts of data must be used if we want to understand regioisomerism in heterohedral metallofullerenes. These tools have also been very useful for drawing conclusions from the considerable quantities of data provided by the factors which affect the stability of regioisomers. These tools have been used not only for analysing data but also for predicting the stability of other heterofullerenes.
TNT encapsulation stabilizes fullerene isomers that are not available as free fullerenes. TNT endohedral metallofullerenes are formed by the encapsulation of a metallic nitride template inside the following cages: D3-C68:6140, D3h'-C78:5, D5h-C80:6 and Ih-C80:7. Any of these cages have never been detected experimentally.So, endohedral metallofullerenes can make non-classical fullerene isomers available for study. Furthermore, on the basis of the electronic structure we predicted that no other IPR fullerenes between C60 and C84 will be capable of encapsulating a TNT unit, apart from the fullerene isomers that are already known.
Stability of the carbon skeleton is the principal factor that determines the regioisomer stability of the heterofullerenes. Metal atoms occupy neighbouring positions in the most stable structures of C57Pt2 and C56Pt2. Metal substitution deforms the carbon framework and partially destroys the fullerene aromaticity. This is the key factor in determining the stability of these disubstituted clusters. Indeed, it is much easier to make a big hole that permits the incorporation of two Pt atoms in the carbon cage than two smaller holes in two opposite sites of the fullerene.
Prediction of the exohedral reactivity taking into account the full characterization of the different CC bond types. We first performed a full characterization of all CC bond types of the fullerenes Ih-C60:1, D3-C68:6140, D5h-C70:1, D3h'-C78:5, Ih-C80:7, D2-C84:22 and D2d-C84:23. Each CC bond type is characterized by its topology, length, pyramidalization angle and Mayer bond order. This systematization enabled us to identify which sites were most reactive to a nucleophilic addition to free fullerenes or a [4 + 2] cycloaddition to TNT endohedral metallofullerenes.
Tarragona, 8th Novembre 2004
Josep Maria Campanera Alsina
6
Strasser, Stefan. "Nanotechnological Characterisation of Biomaterials". Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-78763.
Testo completo
7
Hedlund, Joel. "Bioinformatic protein family characterisation". Doctoral thesis, Linköpings universitet, Bioinformatik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-61754.
Testo completoAbstract (sommario):
Biological research is necessary; not only to further our understanding of the processes of life, but also to combat disease, hunger and environmental damage. Bioinformatics is the science of handling biological information. It entails integrating, structuring and analysing the ever-increasing amounts of available biological data. In practise it means using computers to analyse huge amounts of very complicated data taken from a field that is only partially understood, to see the hidden trends and connections, and to draw useful conclusions. My thesis work has mainly concerned the study of protein families, which are groups of evolutionarily related proteins. I have analysed known protein families and created predictive models for them, and developed algorithms for defining new protein families. My principal techniques have been sequence alignments and hidden Markov models (HMM). To aid my work, I have written a lot of software, including MSAView, a visualiser for multiple sequence alignments (MSA). In this thesis, the protein family of inorganic pyrophosphatases (H+-PPases) is studied, as well as the two protein superfamilies BRICHOS and MDR (medium-chain dehydrogenases/reductases). The H+-PPases are tightly membrane bound, proton pumping, dimeric enzymes with ~700-residue subunits and found in bacteria, plants and eukaryotic parasites, and which use pyrophosphate as an alternative to ATP. The BRICHOS superfamily is only present in higher eukaryotes, but encompasses at least 8 protein families with a wide range of functions and disease associations, such as respiratory distress syndrome, dementia and cancer. The sequences are typically ~200 residues with even shorter functional forms. Finally, MDR, is a large and complex protein superfamily; it currently has over 16000 members, it is present in all kingdoms of life, the pairwise sequence identity is typically around 25 %, the chain lengths vary as does the oligomericity, and the members are partaking in a multitude of biological processes. The member families include the classical liver alcohol dehydrogenase (ADH), quinone reductase, leukotriene B4 dehydrogenase, and many more forms. There are at least 25 human MDR genes excluding close homologues. There are HMMs available for detecting MDR superfamily membership, but none for the individual families. For the H+-PPase family, we characterised member sequences found using an HMM of a conserved 57-residue region thought to form part of the active site. This region was found to contain two highly conserved nonapeptides, mainly consisting of the four “very early” residues Gly, Ala, Val and Asp, compatible with an ancient origin of the family. The two patterns have charged amino acid residues at positions 1, 5 and 9, are apparent binding sites for the substrate and parts of the active site, and were shown to be so specific for these enzymes that they can be used for automated annotation of new sequences. For the BRICHOS superfamily, we were able to find three previously unknown member families; group A, which may be ancestral to the ITM2 families (integral membrane protein 2); group B, which is a close relative to the gastrokine families, and group C, which appears to be a truly novel, disjoint BRICHOS family. The C-terminal region of group C has nearly identical sequences in all species ranging from fish to man and is seemingly unique to this family, indicating critical functional or structural properties. For the MDR superfamily, we characterised and built stable HMMs for 17 member families using an empiric approach. From our experiences we were able to develop an algorithm for automated HMM refinement that uses relationships in data to produce stable and reliable classifiers, and we used it to produce HMMs for 86 distinct MDR families. We have made the program freely available and it can be readily applied to other protein families. We also developed a web site (http://mdr–enzymes.org) that makes our findings directly useful also for non-bioinformaticians. In our analyses of the 86 families, we found that MDR forms with 2 Zn2+ ions in general are dehydrogenases, while MDR forms with no Zn2+ in general are reductases. Furthermore, in Bacteria, MDRs without Zn2+ are more frequent than those with Zn2+, while the opposite is true for eukaryotic MDRs, indicating that Zn2+ has been recruited into the MDR superfamily after the initial life kingdom separations. Multiple sequence alignments (MSA) play a central part in most work on protein families, and are integral to many bioinformatic methods. With the ongoing explosive increase of available sequence data, the scales of bioinformatic projects are growing, and efficient and human-friendly data visualisation becomes increasingly challenging, but is still essential for making new interpretations and discovering unexpected properties of the data. Ideally, visualisation should be comprehensive and detailed, and never distract with irrelevant information. It needs to offer natural and responsive ways of exploring the data, as well as provide consistent views in order to facilitate comparisons between datasets. I therefore developed MSAView, which is a fast, modular, configurable and extensible package for analysing and visualising MSAs and sequence features. It has a graphical user interface and a powerful command line client, and can be imported as a package into any Python program. It has a plugin architecture and a user extendable preset library. It can integrate and display data from online sources and launch external viewers for showing additional details. It also includes two new conservation measures; alignment divergences, which indicate atypical residues or deletions, and sequence conformances, which highlight sequences that differ from their siblings at crucial positions. In conclusion, this thesis details my work in analysing two protein superfamilies and one protein family using bioinformatic methods; developing an algorithm for automated generation of stable and reliable HMMs, as well as a new conservation measure, and a software platform for working with aligned sequences.
8
Lavelle, S. P. "Characterisation of bioactive aerosols". Thesis, London South Bank University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618633.
Testo completo
9
Leivers, Shaun. "Characterisation of bacterial exopolysaccharides". Thesis, University of Huddersfield, 2011. http://eprints.hud.ac.uk/id/eprint/12014/.
Testo completoAbstract (sommario):
In this project, the structures of exopolysaccharides (EPS) produced by bacterial strains were characterised. The current techniques utilised for structural elucidation were also investigated. The structure of the novel EPS isolated from the fermentation of the lactic acid bacteria(LAB) strain, Lactobacillus helveticus Rosyjski, has been characterised. The strain of LAB was grown on skimmed milk supplemented with glucose; the subsequent EPS produced was isolated using established protocols. The 1H NMR spectrum identified the presence of five anomeric monosaccharide signals corresponding to the existence of a pentasaccharide repeating unit oligosaccharide. HP-SEC-MALLS analysis revealed the EPS has a weight average molecular weight of less than 1.4 x106 g mol-1. A combination of GC-MS and HPAEC-PAD analysis confirmed that the structure was composed of D-glucose, D-galactose and D-N-acetyl mannosamine in a molar ratio of 2:2:1. Linkage analysis of the EPS, by GCMS and 2D-NMR experiments showed that the repeating unit contains two terminal, one dilinked and two tri-linked monosaccharides. All of the data obtained allowed for the elucidation of the structure of the EPS produced by Lactobacillus helveticus Rosyjski. The current techniques used for the determination of the monomers and linkages present in EPS structures were investigated. Monomer analysis was studied by using the previously characterised EPS, Lactobacillus acidophilus 5e2 as a model. A variety of acids were used to catalyse the hydrolysis of the polysaccharide. The monosaccharides liberated from the EPS were analysed by HPAEC-PAD. It was determined that hydrolysis with TFA was the simplest technique to employ whilst also providing reliable results. Linkage analysis was investigated by the production of a number of disaccharide-derived model linkage standard compounds. This resulted in the creation of a number of terminally and di-linked linkage standards which can be used as model reference compounds when characterising previously unidentified EPS. The bacterial strain Bifidobacterium animalis subsp. lactis A1dOxR produces EPS. Initial inspection of the 1H NMR spectrum however displayed a complex anomeric region with many overlapping signals. Analysis by HP-SEC-MALLS revealed multiple peaks, further adding to the evidence of the presence of more than one EPS in the recovered ‘crude’ sample. The crude sample was subjected to dialysis and a fraction (over 100,000 Da) was recovered and denoted as high molecular weight (HMW) EPS. Examination of the 1H NMR spectrum from HMW EPS indicated a hexasaccharide repeating unit oligosaccharide, whilst HPEAC-PAD and GC-MS analysis confirmed that the structure was composed of Lrhamnose, D-galactose and D-glucose in a molar ratio of 3:2:1. Further analysis determined that one of the galactose monosaccharides was present in the furanose form as appose to the more commonly observed pyranose configuration. Linkage analysis of the EPS, by GCMS and 2D-NMR experiments, showed that the repeating unit contains one terminal, four dilinked and one tri-linked monosaccharide. All of the data obtained allowed for the elucidation of the structure of the HMW EPS from by Bifidobacterium animalis subsp. lactis A1dOxR. Solubilising EPSs has been a constant challenge, however, it was hoped with the advent of ionic liquids (IL) this issue could be solved. Ultimately, dissolution of EPS in ionic liquids though proved to be unsuccessful, so attention was turned to combining derivatisation and dissolution, as a method for solubilising polysaccharides. Derivatisation of a number of model systems of di- and polysaccharides were explored. By studying both 1D- and 2D-NMR coupled with GC-MS analysis it has demonstrated that polysaccharides such as cellulose along with a number of common disaccharides can be successfully dissolved and modified in ionic liquids.
10
Moorwood, Catherine L. "Neuronal characterisation of syncoilin". Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.491501.
Testo completoAbstract (sommario):
Syncoilin is a member of the intermediate filament protein family. It is highly expressed in skeletal and cardiac muscle, where it binds to the dystrophin associated protein complex, via a-dystrobrevin. Syncoilin is increased in the muscles ofpatients with muscular dystrophies. Previous data from this laboratory indicated that syncoilin is also expressed in neurons, but its function in the nervous system is unknown. The aim ofthis thesis was to determine the neuronal function of syncoilin, by the identification of its binding partners. This is an important question because cytoskeletal dynamics are critical in the development and regeneration of neurons, and moreover, mutations in other intermediate filament proteins can cause amyotrophic lateral sclerosis and Charcot-Marie-Tooth disease. In this thesis, a co-immunoprecipitation and mass spectrometry strategy was used to identify binding partners for syncoilin in neurons. Two novel binding partners were identified, namely a-tubulin and the chaperone CCT, and verified using other methods. Additionally, the interaction of syncoilin with the neuronal intermediate filament peripherin was confirmed and investigated further. Finally, three syncoilin gene variants identified in a dHPLC screen ofpatients with motor neuropathies were characterised in terms of their predicted effects on the structure and binding properties ofsyncoilin and their subcellular localisation in the NSC-34 motor neuron cell line. The identification ofnovel binding partners for syncoilin in neurons gives important insights into the architecture and dynamic organisation ofthe neuronal cytoskeleton, and may also contribute to the understanding of syncoilin in skeletal muscle. Furthermore, the identification of syncoilin variants in patients with motor neuropathies suggests that syncoilin may be involved in the pathogenesis of motor neuron disease.
11
Gillespie, Philip David. "Inline blind sensor characterisation". Thesis, Queen's University Belfast, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.726355.
Testo completoAbstract (sommario):
The measurement of rapidly changing temperature fluctuations is a challenging problem due to the inherent limited bandwidth of temperature sensors. This results in a measured signal that is a lagged and attenuated version of the true input signal. Compensation can be performed provided an accurate, parameterised model of the sensor is available. However, the sensor characteristics are strongly dependent on the measurement environment, which is often time-varying and cannot be determined a priori. To account for the changing characteristics, the sensor model must be estimated in-situ, thereby resulting in a blind identification problem. In this study, methods for performing blind characterisation of a two-sensor probe for fast temperature measurement are investigated and developed, with a particular focus on extending existing methods to handle second-order models.
12
Mölling, Paula. "Genetic characterisation of meningococci /". Linköping : Örebro : Univ. ; Örebro Medical Centre Hospital [Universitetssjukhuset], 2001. http://www.bibl.liu.se/liupubl/disp/disp2001/med697s.pdf.
Testo completo
13
Clark, R. A. C. "Characterisation of neural glycoproteins". Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363826.
Testo completo
14
Thoree, Cheetranjan Vinay. "Characterisation of gastrointestinal microparticles". Thesis, King's College London (University of London), 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555927.
Testo completoAbstract (sommario):
Intestinal Peyer's patches, through their specialized M cell-rich epithelium, can act as a portal of entry for bacteria, viruses, macromolecules and particles. Particles can be further classified as exogenous particles such as those derived from the diet in the form of food additives or endogenous particles which result from calcium and phosphate precipitation in the mid-distal intestinal lumen. Although exogenous dietary particles have been found to accumulate in "pigment cells" at the base of the human Peyer's patch, little is known about calcium phosphate particles. This thesis aimed (i) to investigate and compare the micro-anatomical site of exogenous and endogenous particles within the Peyer's patch, and (ii) to analyse the phenotype of cells involved in their uptake. Following an Introduction chapter (Chapter 1) and Methods chapter (Chapter 2), the focus of chapter 3 was to look for the presence of both calcium phosphate and exogenous particles in human intestinal Peyer's patches using the Von Kossa staining method and dark field microscopy, respectively. The elemental makeup of the endogenous particles was investigated by X-Ray Microanalysis (XRMA). This study revealed a sub-epithelial Peyer's patch dome-associated population of Von Kossapositive particle cells, the majority of which appeared to be calcium-rich, and more especially calcium- and phosphorus- rich. Exogenous particles associated with the usual basal pigment cells could similarly be found in the sub-epithelial dome cells and suggested that the exogenous particles made their way through the patch via intermediary cells. Following work concentrated on the phenotyping of cells responsible for the uptake of exogenous and endogenous particles (Chapters 4 and 5, respectively). Pigment cells of the Peyer's patch base were found to be macrophages, chiefly of a mature phenotype, and appeared metabolically and immunologically of low activation status. In contrast, calcium phosphate particles were found mainly in dendritic cells of the sub epithelial dome region of the Peyer's patch. The cell phenotype (CDIlc+, CDl lb+) was consistent with immune tolerance-inducing dendritic cells reported in the literature - the specific mechanism being induction of regulatory T cells. I have speculated on how the uptake of endogenous particles may influence such process.
15
Ferguson, L. J. "Characterisation of nidovirus primases". Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557407.
Testo completoAbstract (sommario):
SUMMARY (To be printed on this form) Replication of the -30-kb positive-sense RNA genomes of the Coronaviridae and transcription of a set of subgenomic mRNAs is mediated by a large protein complex of nonstructural proteins (nsps) involving two RNA-dependent RNA polymerase activities that, in coronaviruses, are associated with nonstructural proteins (nsp) 8 and 12. To further characterise the RNA polymerase (primase) activity suggested to be associated with coronavirus nsp8, homologs from Human coronavirus 229E (HCoV- 229E) and the bafinivirus White bream virus (WBV), along with a set of mutant proteins containing alanine substitutions of conserved residues, were expressed in E. coli and the polymerase activities of the purified proteins were characterised in vitro. The data revealed robust metal ion-dependent polymerase activities for both HCoV-229E nsp8 and the WBV homologue. The mutant proteins retained varying degrees of activity, with single or double substitutions of three conserved Asn and Lys residues (ppla/ppJab N3672A, N3672A/K37 I lA, K3687A/K371IA) displaying the most detrimental effects on HCo V -229E nsp8 activity. The polymerase activities were further characterised using a range of homopolymeric and virus-specific template RNAs, revealing insight into substrate preferences of the coronavirus primase. HCo V -229E nsp8 substitutions were subsequently studied in the context of HCoV-229E replication in cell culture using a reverse genetics system. The data show that nsp8 activity is essential for coronavirus RNA synthesis, with substitutions of functionally important residues causing lethal phenotypes or defects in viral RNA synthesis and production of infectious virus progeny. The data provides interesting insight into the enzymatic and functional properties of two as yet poorly characterized polymerase/primase activities from distantly related viruses from the Alphacoronavirus and Bafinivirus genera. Furthermore, the study identified a number of WBV main protease cleavage sites, providing information on the substrate specificity of the WBV main protease and the proteolytic processing events used to release the putative WBV primase from larger polyprotein precursors.
16
Iyer, N. G. "Functional characterisation of p300". Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604977.
Testo completoAbstract (sommario):
p300, originally discovered as an adenoviral El A binding protein, is a putative tumour suppressor gene. Mutational analysis done in our laboratory found truncating mutations in a range of cell lines and primary tumours, in some cases associated with loss of the second allele. In order to study the possible pathways leading from p300 loss to cancer, I adopted a somatic cell line knock out strategy to study the gene function in a human epithelial system. Using homologous recombination mediated gene targeting I successfully disrupted p300 in HCT116, by targeting the single expressed, truncated allele. Resultant cells were null for p300 protein. Rescue clones were generated by re-introducing full-length p300 cDNA into the knock-out clones. p300 knock-out (KO) cells were defective in proliferation, with prolonged doubling times and increased S-phase. A fraction of cells were in senescence/quiescence, and included a flat cell phenotype. These changes were reversed in the rescue clones. KO cells also showed a Gl to S-phase transition defect with early S phase entry after serum depletion and nocodazole arrest and release experiments. Rb pathways were deranged, principally by Rb phosphorylation defects, which probably led to the activation of the E2F pathway and early S-phase entry. KO cells also demonstrated abnormalities in p21 response during the cell cycle, which could have contributed to the cell cycle phenotype. In addition, KO cells were found to have reduced cell-cell adhesion, due to a decrease in E-cadherin at tight junctions and total E-cadherin levels. DNA damage experiments suggest that p300 KO cells are especially sensitive to UV mediated DNA damage with increased apoptosis seen 24 h after irradiation. This was due to abnormalities in the p53 pathway- a combination of increased stability of p53, reduced acetylation at lysine 382 and abnormal transactivation of downstream factors. In contrast, long term growth of KO cells after UV and XR irradiation showed increased resistance to DNA damage.
17
Ramirez, Pacheco Carlos. "Radiometric partial discharge characterisation". Thesis, University of Strathclyde, 2007. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21654.
Testo completoAbstract (sommario):
The process of generation, transmission and distribution of electric energy appears to be very simple. However, the continuous flow of power through electric networks is affected by several factors, normally of two kinds: failures caused by ageing of insulating materials and failures caused by defective equipment or design. The energy supplied to small and big consumers can be interrupted for long periods causing disastrous economic losses. The origin of most failures normally is found in electrical insulation, which is an essential component in all electrical systems especially in power equipment such as transformers and circuit breakers, the cost of which is very high. Before the insulation fails, there are manifestations of this condition, called partial discharges (PD) and because of this, PD have been subject of an extensive study and investigation. PD identification relies on the intrinsic characteristics of the generated discharge. This thesis shows the behaviour of radiated discharge through the analysis of the characteristic frequency spectra and pulse distribution to create pattern classification in the laboratory. This research is based on a novel technique that uses wide band, high resolution equipment, composed of an antenna array, that receives the radiated discharge, and a high resolution oscilloscope that accurately measures and samples the propagated signal. The second part of the laboratory setup comprises the characterization of partial discharges using a high voltage transformer and measurement devices that accurately apply a range of voltages to specimens containing insulation defects. The advantages of having accurate PD sources are evident: availability, free of ambiance noise, accurate AC reference and PD location. Results show that pattern recognition to identify PD'S using a non invasive system and point on wave information is possible and reliable.
18
Aarseth, Larsson Kim. "Chemical Characterisation of Nitrocellulose". Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-41416.
Testo completoAbstract (sommario):
Nitrocellulose is the main component in many types of ammunition, propellants and explosives. The principles of production for nitrocellulose have not changed much since the 19th century when it started being industrially produced for this purpose. The character of the nitrocellulose has a large effect on the end products abilities. The aim of this study was to develop a method that would be able to characterise and distinguish between nitrocellulose from different manufacturers to be able to relate the character of the nitrocellulose to the properties of ammunition, propellants and explosives. Samples were dissolved in acetone and analysed by GC/MS and data were then analysed by multivariable statistics. FTIR was also used to characterise the nitrocellulose. Results from both methods showed very small differences when chromatograms and spectra were analysed. This study shows that GC/MS and FTIR are not suitable for this type of characterisation. The differences between the data were not sufficient to be able to separate the samples from each other.Nitrocellulosa är den viktigaste komponenten i många typer av ammunition, drivmedel och sprängämnen. Principerna för produktionen av nitrocellulosa har inte förändrats mycket sedan det börjades produceras industriellt för detta ändamål på 1800 talet. Karaktären av nitrocellulosa har en stor inverkan på slutproduktens egenskaper. Syftet med denna studie var att utveckla en metod som skulle kunna karaktärisera och skilja mellan nitrocellulosa från olika tillverkare för att kunna relatera karaktären av nitrocellulosa till egenskaperna hos ammunition, drivmedel och sprängämnen. Proverna löstes i aceton och analyserades med GC/MS och data analyserades med multivariabel statistik. FTIR användes också för att karakterisera nitrocellulosan. Resultaten för båda proverna visade mycket små skillnader när kromatogram och spektra analyserades. Denna studie visar att GC/MS och FTIR inte är lämpliga för denna typ av karaktärisering. Skillnaderna i data var inte tillräckliga för att kunna skilja proverna från varandra.
19
Bend, Stephen Leonard. "Coal characterisation and combustion". Thesis, University of Newcastle Upon Tyne, 1989. http://hdl.handle.net/10443/361.
Testo completoAbstract (sommario):
There are three related studies within this thesis that examine the relationships between the properties of coals and the characteristics of the chars produced during rapid pyrolysis in a laboratory based Entrained Flow Reactor (EFR) which simulates the rapid rates of heating (104 to 105 °C s-1 ) typical of pulverised fuel boilers. The first study, using a suite of nine coals, investigates the influence of coal rank upon the generation of specific types of char, their respective physical and structural characteristics and their relative combustabilities. The second study, using a suite of twenty-two coals, examines various coal characterisation techniques and the correlations between those techniques and the associated char, and specifically investigates petrographic techniques as a means of characterising coal feedstock. The third study, using freshly mined coals, investigates the effects of oxidation (100°C, air) and weathering (ambient) upon standard analytical techniques and relates such changes to the physical, structural and combustion characteristics of the associated char. There is a common relationship between the elemental oxygen content of the parent coal and the generation of specific types of char for both vitrinite rich coals of differing coal rank and for the oxidised or weathered coals. There is also an inverse relationship (R 2 = 0.97) between the elemental oxygen content of a vitrinite rich coal and the proportion of cenospheres generated by pyrolysis at 1000°C using the EFR. Furthermore, the enhancement of char combustion at 1000°C (in an EFR) is related to the physical and structural characteristics of the char, i.e. the presence or absence of porosity (visible using SEM and TEM), the CO2 surface area and optical texture. A relationship exists (R2 = 0.83) between the morphology of a char (1000°C / N2) and the petrographic composition of the parent coal. The new term microlithotype, is an amalgamation of various vitrinite rich microlithotype classes that simplifies the nomenclature. A combination of calorific value, microlithotype, and coal rank (vitrinite reflectance) illustrates the influence of petrographic composition upon calorific value and also suggests a 'Province' dependency amongst the Cretaceous/Tertiary and Carboniferous coals studied. The coal properties calorific value, microlithotype, and coal rank can be related (R 2 = 0.91) to the proportion of porous chars for the Cretaceous/Tertiary suite of coals, illustrating the use of multivariate analyses when characterising coal feedstock. The effects of oxidation and weathering upon vitrinite fluorescence is also reported. The oxidation of coal at 100°C produces rims of quenched fluorescence which are not apparent within the weathered coals. Furthermore, the intensity of fluorescence at 650 nm (1650) decreases due to progressive oxidation or weathering, but decreases at a rate that is dependent upon the severity (temperature) of the conditions employed. The proposed oxidation quotient (0/Q = I65W%Romax) is a sensitive indicator of the oxidative conditions up to 100°C.
20
Hanboula, Salem Yousef. "Immunological characterisation of dermatophytes". Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243208.
Testo completo
21
Cooper, W. S. "Characterisation of sulpho oils". Thesis, Liverpool John Moores University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375103.
Testo completo
22
Andrew, M. "Chemical characterisation of rapeseed". Thesis, Liverpool John Moores University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381603.
Testo completo
23
Anderson, William John. "Molecular characterisation of rhabdomyosarcoma". Thesis, Institute of Cancer Research (University Of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312950.
Testo completo
24
Thorley, Antony M. "Infrared characterisation of semiconductors". Thesis, University of St Andrews, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278212.
Testo completo
25
McCormick, Damion K. T. "Perilipin : characterisation and translocation". Thesis, University of Newcastle Upon Tyne, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388129.
Testo completo
26
Batty, Michael. "Geometric characterisation of groups". Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300650.
Testo completo
27
Morris, Iestyn L. "Optical characterisation of semiconductors". Thesis, Aberystwyth University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386969.
Testo completo
28
Zhang, Jiancheng. "Characterisation of bacterial NOS". Thesis, University College London (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270425.
Testo completo
29
Ikwueme, Stella Ngozichukwu. "Characterisation of polylactide microspheres". Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407916.
Testo completo
30
Sorensin, Troels Seyffart. "Characterisation of DP-1". Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243913.
Testo completo
31
Heise, Charles T. "Biochemical characterisation of RARI". Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437596.
Testo completo
32
Domann, Roland. "Characterisation of spray unsteadiness". Thesis, University of London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443683.
Testo completo
33
Hirose, Yuta. "Technology venture emergence characterisation". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/273663.
Testo completoAbstract (sommario):
Technology entrepreneurs and managers aim to navigate emerging technology ventures and innovations towards successful commercialisation and business development, often over long periods of time. However, this is challenging due to high uncertainties associated with planning and navigating relevant market and business drivers, technological resources and capabilities, and applications. Failure to understand and manage these uncertainties appropriately can lead to undesired consequences and poor outcomes in the realisation of value creation and capture. This research firstly built a knowledge base of technology ventures by conducting a literature review, enabling the development of a conceptual retrospective roadmapping framework as the basis for characterising the emergence of technology ventures. This leads to an analysis of 13 case studies, characterising phases, transitions, patterns, enablers and barriers associated with the emergence of technology ventures. A conceptual model, the so-called ‘emergence archetypes’, was then developed by conducting an in-depth analysis with a further 19 case studies. The concept provides practical insights regarding how emerging technology ventures can be exposed to different levels of technological and market uncertainties along the journey of technology commercialisation and business development. Finally, a strategy visualisation tool and process have been designed based on the research outputs, and a focus group was then conducted with industrial practitioners to review and evaluate the research outputs for practical use in industry. In total, 32 case studies and a focus group have been conducted in the United Kingdom, The Netherlands, Japan, Australia and the United States. Overall, this research demonstrates that characterising technology venture emergence, by applying roadmapping principles, provides significant implications for both researchers and practitioners of strategy and innovation. Success or failure of emerging technology ventures, in terms of value creation and capture, is not only directly related to products or services, but more broadly to the innovation systems in which the technology ventures operate. By demonstrating the characterisation of technology venture emergence, the conceptualisation of emergence archetypes and the strategy visualisation tool and process development, this research shows that applying roadmapping is an appropriate method to characterise and improve emerging technology venturing practices, supporting value creation and capture.
34
Taylor, William R. M. "Chromatographic characterisation of copolymers". Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/13601.
Testo completoAbstract (sommario):
Copolymers containing hydrophilic and hydrophobic segments find applications as polymeric surfactants in detergent formulations. The properties of such surfactants depend on molecular weight and composition of copolymer chains, and in particular on the heterogeneities in molecular weight distribution and chemical composition distribution within samples. Heterogeneity in copolymer composition may include the presence of a homopolymer which would not be active in a detergent application. In this thesis work is directed to the development of separation methods by reversed phase chromatography to characterise copolymers according to composition. Copolymer systems include acrylic acid/lauryl methacrylate, poly(ethylene oxide)lvinyl acetate, and polyesters based on terephthalic acid, poly( ethylene oxide) and glycerol. The outcome of these separations has been the isolation of poly acrylate and copolymer; poly(ethylene oxide), poly(vinyl acetate) and copolymer from their respective copolymer systems; and the separation of poly( ethylene oxide) and glycerol from the polyester samples. Spectroscopic analysis of the fractions for each copolymer enabled complete characterisation and quantification of the copolymers present.
35
Gonçalves, Carlos Augusto. "Characterisation of formation heterogeneity". Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/35033.
Testo completoAbstract (sommario):
The characterisation of formation heterogeneities requires a multidisciplinary study of data acquired using a large number of numerical geophysical and geological measurements and a rigorous evaluation of the precision and accuracy of the data. Another essential aspect of the appraisal of any measurement is the quality assessment and quality control of the data. In this work multivariate statistical techniques and an Artificial Neural Network (ANN) are used provide lithofacies characterisation and to identify heterogeneities in complex formations as well as to evaluate the boundaries they generate. The precision and accuracy of the data from different sources are very important and are considered here by using sample support in the integration of measurements at different scales. We use examples from two holes of the Ocean Drilling Program and two oilfield holes to show the differences in characterisation obtained with each technique. Multivariate Statistical Analysis are initially used to group the petrophysical, geophysical and geological parameters extracted from the downhole measurements into distinct geologically definable zones. This technique has the advantage of being quasi-independent of any pre-determined ideas we have about the whole dataset, and has proved very reliable in formation characterisation. Thus the result obtained here is used as a basis for comparison with that obtained from the Neural Network. Artificial Neural Network is used to characterise the different lithology sequences present in each well. Neural Networks are relatively new tools and have proved very useful in applications where conventional computing methods are inadequate. Another application is the possibility of determining quantitative petrophysical parameters from well logs and core data in uncored intervals. The results are presented as a comparison between the two techniques. We show that both methods are very encouraging. When comparing the ANN derived petrophysical parameter logs with actual core measurements and other petrophysical parameters prediction techniques we see a good match. Low quality petrophysical measurements can be determined by a mismatch between the responses.
36
Zhou, Jin Chuan. "Biochemical characterisation of KDM2A". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:030faa1d-5d3c-4066-9e9f-a44cd13cf85c.
Testo completoAbstract (sommario):
Mammalian genomes are characterised by unique regions of non-methylated DNA known as CpG islands (CGIs). These genomic elements are characterised by a high density of CpGs and an elevated GC content compared to the surrounding, bulk of the genome. CGIs are prevalently associated with the 5’ end of genes and represent key nucleation sites where specific transcription factors and chromatin modifiers are recruited to impact on gene function. This thesis is focused at understanding the biochemical properties of the recently discovered H3K36-specific histone demethylase, KDM2A. This enzyme is specifically recruited to CGIs but how it interfaces with local chromatin in vivo remains unknown. Using defined chromatin templates in vitro, this study demonstrates that KDM2A binding to DNA relies on a zinc finger CXXC domain that preferentially recognizes non-methylated CpGs. In particular, nucleosomes represent a major barrier to KDM2A binding and chromatin substrates are interpreted by the CXXC domain through specific interaction with CpGs within linker DNAs. Moreover, the adjacent PHD domain does not contribute to KDM2A binding to chromatin. Together these observations suggest that sequence, methylation status and accessibility of DNA define how CGI chromatin is interpreted by CXXC domain proteins. In particular, the precise targeting of KDM2A to CGIs contributes to the creation of a unique chromatin architecture that highlights gene regulatory regions within large and complex mammalian genomes.
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Bergman, Anders. "Characterisation of industrial wastes". Licentiate thesis, Luleå tekniska universitet, 1996. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16984.
Testo completo
38
Butler, Paul. "Characterisation of disordered structures". Thesis, University of Kent, 2017. https://kar.kent.ac.uk/62479/.
Testo completoAbstract (sommario):
In this thesis I will look at how large, complex structures can be interpreted and evaluated using an information theoretic approach. The work specifically investigates techniques to understand disordered materials. It explains a novel framework using statistical methods to investigate structural information of very large data sets. This framework facilitates understanding of complex structures through the quantification of information and disorder. Large scale structures including granular media and amorphous atomic systems can also be processed. The need to deal with larger complex structures has been driven by new methods used to characterise amorphous materials, such as atomic scale tomography. In addition, computers are allowing for the creation of larger and larger data sets for researchers to analyse, requiring new techniques for storing and understanding information. As it has become possible to analyse large complex systems there has been a corresponding increase in attempts to scientifically understand these systems. New, man-made, complex systems have emerged such as the stock market and on-line networks. This has boosted interest in their interpretation, with the hopes they can be more easily manipulated or controlled. Crystallography has been applied to great effect in biology, having been used to discover the structure of DNA and develop new drugs (UNESCO,2013). However it only describes crystal structure, which can be a drawback as a large majority of matter is amorphous. As such it is hoped that interpreting and understanding disorder may lead to similar breakthroughs in disordered materials. Entropic measures such as the mutual information and Kullback Leibler Divergence are used to investigate the nature of structural information and its impact on the system. I examine how this information propagates in a system, and how it could quantify the amount of organisation in a system that is structurally disordered. The methodology introduced in this thesis extracts useful information from large data sets to allow for a quantification of disorder. The calculated entropy for amorphous packings is generally less than 1 bit with Mutual information between 0 and 0.1 bits. The results verify direct correlation between Mutual Information and the correlation coefficient using various techniques. The Mutual information shows most information is obtained where sphere density is highest, following a similar trend to that of the Radial distribution function, and generally increasing for higher packing fractions. Evidence of the Random Close Packed (RCP) and Random Loose Packed (RLP) limits in two dimensions is shown, as well as evidence of both phases in time-lapsed 3D packings. The Kullback Leibler Divergence is also explored as a relative measure of disorder. This is achieved by calculating redundant information in packings so that areas of low and high order can be shown. Results present colour maps displaying relative information in random disk packings from which motifs can be identified. For higher packing fractions distinct borders form for areas of low and high information, particularly where crystallisation has occurred. Again, these results show an increase in information for more densely packed structures, as expected, with a Kullback Leibler divergence of between 0 and 1 bits. Finally I introduce the concept of self-referential order which provides a way to quantify structural organisation in non-crystalline materials, by referencing part of the system in a similar way to a unit cell. This allows a step forward in understanding and characterising disorder, helping to develop a framework to encode amorphous structures in an efficient way. These results show increasing information for higher packing fractions as well as further evidence of RLP and RCP limits around packing fractions of 0.54 and 0.64 respectively.
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Miell, Matthew Daniel David. "Characterisation of CenH3 nucleosomes". Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8010.
Testo completoAbstract (sommario):
As a centromere-specific protein complex in direct contact with the DNA, CenH3-containing nucleosomes are generally thought to act as the distinguishing epigenetic mark of active centromere location. Confusingly, seemingly disparate models have been proposed for the structure of CenH3 nucleosomes. The most widely supported model is an octameric structure that, like histone H3 nucleosomes, contains two subunits of each histone. Another more contentious, yet persistent model is the hemisome model proposed for fly and human CenH3 nucleosomes. In this case it is suggested that CenH3 nucleosomes contain only single subunit of each histone. One reason for this lack of consensus is that seemingly contradicting models are often proposed, even with material from the same organism, with little overlap in experimental approaches. For example, the proposed hemisome model for fly and human CenH3 nucleosomes is predominantly based on atomic force microscopy (AFM) imaging where the height of nucleosomes on a surface is measured. These AFM measurements are the main data used by protagonists for the hemisome model. However, data supporting an octameric model for human, and other, CenH3 nucleosomes is largely based on biochemical analysis of nucleosomes prepared in vitro, with little cross-over in the methodology used to generate data to support either model. In order to reach a consensus the same analyses needs to be applied to CenH3 nucleosomes assembled in vitro or extracted from cells. Here, recombinant Schizosaccharomyces pombe CENP-ACnp1 and H3 histones expressed and purified from E. coli have been assembled into nucleosomes. To our knowledge this is the first time that recombinant S. pombe nucleosomes have been produced, allowing the stoichiometry and composition of these nucleosomes to be examined in detail by a variety of biochemical and biophysical assays. The application of AFM has enabled the height of these recombinant nucleosomes to be measured and tests the ability of AFM to infer stoichiometry using defined material. The intriguing conclusion is that octameric CenH3 nucleosomes uniquely behave as tetrameric “hemisomes” as defined by AFM. In recent years the contribution of DNA sequence to directing H3 nucleosome location has received a great deal of interest. Since CENP-ACnp1 nucleosomes wrap DNA differently to H3 nucleosomes their preference for sequences that produce a stable nucleosome is expected to be altered. The development of protocols to assemble recombinant CENP-ACnp1 nucleosomes in vitro has also been used here to assess the contribution of primary DNA sequence to CENP-ACnp1 nucleosome positioning. CENP-ACnp1 and H3 nucleosomes were reconstituted on genomic DNA at low density and the resulting nucleosomal DNA from CENP-ACnp1 and H3 particles compared by Illumina sequencing. The stability of CENP-ACnp1 and H3 nucleosomes on specific ‘H3’ and ‘CENP-ACnp1’ sequences was cross-checked. Comparing these data with in vivo CENP-ACnp1 nucleosome positions has allowed the contribution of primary DNA sequence to CENP-ACnp1 nucleosome positioning to be explored.
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Wikerman, Fredrik. "Characterisation of alpine skis". Thesis, KTH, Lättkonstruktioner, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203338.
Testo completoAbstract (sommario):
Skiing is a fast and competitive sport where skiers must push their performance limit to win medals, the di↵erence can be within hundreds of a second. Therefore, technical improvements are essential for assisting in the skier’s improvement. This thesis project is a joint project between KTH and the Swedish Ski Association and Swedish Ski Team with the purpose of obtaining a better understanding of the structural properties of alpine skis, aiming to improve the individual selection process of skis for the Swedish World Cup Skiers. The goal of the project is to develop and evaluate a method to characterize alpine skis in form of two main structural properties related to the ski characteristics, bending and torsion sti↵ness. An optical measurement device and image post-processing and analysis is used to determine the deflection and twist of skis, which are used to determine the bending and torsional sti↵ness. The method provides, a structural property variation over the whole ski length compared to the existing ISO standard where only a spring coefficient of the skis main parts is determined, which is insufficient for a good over all comparison. The method could be further used in several aspects to help the Swedish World Cup skiers win more medals. It can be used to help in the selection process of new skis for the next season where an objective comparison between models can be done, as oppose to today when the selection process is highly subjective. Skiers usually vary the ski plate constellation and the method could help skiers with their race preparations, like changing the constellation of the ski plate to optimize the sti↵ness for a specific race condition with engineering knowledge rather than just trusting the feeling. The use of this method can reduce the number of ski tests performed by the skier, thus leaving more time for practice. Testing skis in a laboratory environment also increases objectivity in testing and can therefore give the Swedish Ski Association and Swedish skiers a competitive advantage in upcoming competitions.
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Perry, Alexandra L. "Characterisation of propionibacterium acnes". Thesis, Aston University, 2004. http://publications.aston.ac.uk/11015/.
Testo completoAbstract (sommario):
This thesis has sought to investigate the phenotypic, genetic and antigenic properties of P. acnes strains isolated from sciatica patients undergoing microdiscectomy, normal skin, blood cultures, prosthetic hips and acne lesions. Isolates’ phenotype was examined by determining their biotype by analytical profile index, antimicrobial susceptibility, virulence factor expression and serotype. A molecular typing method for P. acnes was developed using random amplification of polymorphic DNA (RAPD). Patent serum was used to screen P. acnes strains for antigens expressed in vivo and the chemical composition determined. The serodiagnostic potential and inflammatory properties of identified antigens were assessed. The optimised and reproducible RAPD protocol classified strains into three major clusters and was found to distinguish between the serotypes I and II for a large number of clinical isolates. Molecular typing by RAPD also enabled the identification of a genotype that did not react with the type I or II monoclonal antibodies and these strains may therefore constitute a previously undiscovered subspecies of P. acnes with a genetic background different from the type I and II serotypes. A major cell-associated antigen produced by all strains as identified and characterised. A serological assay based on the antigen was used to measure IgG and IgM levels in serum from patients with acne, sciatica and controls. No difference in levels of antibodies was detected. Inflammatory properties of the antigen were measured by exposing murine macrophage-like cells and measuring the release of nitric oxide and tumour necrosis factor-alpha (TNF-a). Only TNF-a was elicited in response to the antigen. The phenotypic, genotypic and antigenic properties of this organism may provide a basis for future studies on P. acnes virulence and provide an insight into its mechanisms of pathogenesis.
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Robertson, Martin Dennis. "Characterisation of avian reoviruses". Thesis, Robertson, Martin Dennis (1986) Characterisation of avian reoviruses. PhD thesis, Murdoch University, 1986. https://researchrepository.murdoch.edu.au/id/eprint/53691/.
Testo completoAbstract (sommario):
Avian reoviruses have been associated with a wide variety of diseases in poultry, including tenosynovitis and a runting/stunting syndrome. This thesis describes an investigation of outbreaks of tenosynovitis and the runting/stunting syndrome in commercial poultry in Australia, the isolation and characterisation of avian reoviruses from affected chickens, and attempts to reproduce the 2 disease syndromes with the isolated viruses.
The histopathological lesions observed in tenosynovitis-affected chickens were confined to the tendons, tendon sheaths and peritendinous tissues of the hock region and consisted of a marked inflammatory reaction with mononuclear cell and heterophil infiltration of affected tissues. The runting/stunting syndrome of broiler chickens was clinically characterised by marked reduction in growth rates and pathologically by thymic atrophy, and atrophy and degeneration of the pancreas. Avian reoviruses were isolated from affected chickens in the majority of outbreaks of both diseases. Virus was recovered from 13% of tenosynovitis-affected chickens, 62% of runted/stunted chickens, and from 76% of normal chickens of the same age as those examined with the runting/stunting syndrome.
Avian reoviruses isolated from affected and normal chickens antigenically heterogenous but were assigned to 3 antigenic groups based on the results of reciprocal serum were neutralisation tests. It was not possible to associate a particular antigenic type with either tenosynovitis or the runting/stunting syndrome. Studies of the electrophoretic migration profiles of the genomic RNA segments by sodium dodecyl sulphate polyacrylamide gel electrophoresis also revealed extensive heterogeneity of the isolated reoviruses. No specific genome type could be associated with any particular disease syndrome or antigenic type. Extensive variation in the genomic migration patterns was detected in isolates from different flocks of chickens and the existence of more than one genome type within individual flocks was also demonstrated.
The pathogenicity of the isolated viruses for specific pathogen-free (SPF) chickens was low. Foot pad inoculation of SPF chickens with reoviruses isolated from tenosynovitis-affected birds resulted in mild microscopic lesions involving only the inoculated leg. No histopathological changes were observed in chickens inoculated orally. A variation in pathogenicity of reovirus isolates and an age-linked susceptibility of chickens to reovirus infection was demonstrated. No growth retardation or microscopic lesions were produced in SPF chickens inoculated orally with tissue homogenates prepared from runted chickens or with reoviruses isolated from affected chickens.
Serological studies of antibodies to reovirus, adenovirus, infectious bursal disease virus (IBDV) and reticuloendotheliosis virus (REV) in chickens from outbreaks of the disease syndromes were conducted. In the 2 tenosynovitis outbreaks examined, antibodies to avian reovirus were detected in all chickens examined although the serological response differed in the 2 outbreaks. A hypothesis to explain this difference was proposed. There was no serological evidence to suggest that adenoviruses, IBDV, Mycoplasma gallisepticum or M. synoviae were associated with tenosynovitis. In 4 outbreaks of the runting/stunting syndrome, antibodies to reovirus were not detected in the 3-week-old affected chickens which suggested that the chickens were either infected after 2 weeks of age or that antibody production as a result of earlier infection may have been suppressed, perhaps by maternally-derived antibody. There was no serological evidence to suggest that IBDV, REV or adenovirus were involved in the runting/stunting syndrome.
The results obtained were consistent with the hypothesis that some strains of avian reoviruses are a cause of subclinical tenosynovitis lesions in chickens but that the development of clinical tenosynovitis is due to the occurrence of secondary infection by bacteria, particularly Staphylococcus aureus. While reoviruses were commonly isolated from chickens with the runting/stunting syndrome they were also commonly present in normal chicken flocks and there was no evidence to prove that they were causal agents of the runting/stunting syndrome.
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Harrer, Manfred. "Characterisation of steering feel". Thesis, University of Bath, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.601495.
Testo completoAbstract (sommario):
The steering feel and handling characteristics of a vehicle are vital factors in determining the overall driving pleasure. Time-consuming and expensive development is required by the vehicle manufacturer before this quality can be achieved and improved. Due to a lack of reliable links between subjective assessments and vehicle measurements, the tuning process still relies primarily on subjective assessments by test drivers. In order to improve the understanding and enable the prediction of steering feel, a methodology to describe steering feel objectively is required. Therefore the scope of this work lies on the development of such methodology, in order to identify reliable relationships between subjective assessments and objective parameters derived out of vehicle measurements. Twenty-five cars, separated into five vehicle segments were analysed. To attain consistent subjective assessments, a new questionnaire has been formulated and, with the use of experienced test drivers, reliable subjective assessments have been achieved. Furthermore, a brand-typical steering feel was identified. A new transformation method for the subjective assessments has been developed to meet the requirements of the performed regression analyses. Various open-loop vehicle tests were performed, with the help of a steering robot, to attain high quality measurements. Automated analyses algorithms were developed to ensure an efficient and consistent data processing. Therefore, a large number of high-quality, objective parameters were derived from the vehicle measurements. Simple, dummy and multi regression analyses have been carried out to detect valid links between the objective parameters and the subjective assessments. All valid regression results were examined with the help of further statistical tests and a practical knowledge of vehicle handling, which consequently led to the selection of the final results. These results constitute the required relationships between the subjective and objective assessments, from which target areas for objective parameters are drawn. The assessment criteria "Steering wheel torque", "Centre feel", "Steering precision" and "Steering friction" are vehicle segment independent, while the criteria "Steering response" and "Steering wheel angle demand" are vehicle segment dependent. The objective parameters for steering wheel torque gradients and the corresponding vehicle response gradients have been found to be most important in describing oncentre steering feel in an objective way.
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Dai, Shuo. "Mechanical characterisation and numerical modelling of 3D woven composites". Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/16221.
Testo completoAbstract (sommario):
Three-dimensional woven composites were developed to improve the through-thickness properties which conventional two-dimensional laminate composites currently lack. However, these textile composites generally show lower in-plane mechanical properties due to fibre crimping, and also encounter modelling difficulties due to the complex geometries. In this thesis, the static and fatigue mechanical behaviour of several types of 3D woven composites were experimentally characterised, the influence of the weave architecture on the mechanical performance was revealed, and meso/macro scale numerical models with improved failure criteria were developed to simulate the tensile behaviour of the 3D woven composites. The mechanical characterisation was conducted on six woven structures under tension, compression, and flexural loading, and were also carried out on two weaves under open-hole quasi-static tensile and fatigue loading. Digital image correlation and thermoelastic stress analysis were used to characterise the strain and damage development during static and fatigue loading. The testing results showed that the angle-interlock weave W-3 had higher in-plane quasi-static properties, lower notch sensitivity, higher fatigue damage resistance, but lower delamination resistance. The meso-scale model was developed on the unit cell of the woven structure and the macro-scale model (mosaic model) was created on the testing samples. Both un-notched and notched tensile behaviour were modelled for the angle-interlock weave W-3 and a one-by-one orthogonal weave W-1, and the difference between the predicted and experimental results was within 16% for the unit cell models and within 21% for the mosaic models. A modified failure criterion was developed to better simulate the damage behaviour of the notched macro-scale model and improved the predicted notched strength by 10-20%. Whilst further experimental investigation and improvement in the modelling techniques are still required, the data presented in this thesis provided an essential update for the current 3D woven composites research, and the presented models offered the potential to predict the damage behaviour of large 3D woven structures.
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Lajhar, Salma A. Ibsais. "Phenotypic and Genotypic Characterisation of Escherichia coli O26 Strains Isolated from Cattle and Clinical sources in Australia". Thesis, Griffith University, 2017. http://hdl.handle.net/10072/371149.
Testo completoAbstract (sommario):
Escherichia coli (E. coli) O26 is the second most common serogroup of enterohaemorrhagic E. coli (EHEC) implicated in foodborne illness globally with outbreaks occasionally linked to the consumption of cattle related food products. This study was performed to gain insights into the phenotypic and genotypic characteristics of E. coli O26 circulating in Australian cattle and those strains from clinical cases. Initial characterisation determined that E. coli O26 are a genetically diverse group that can belong to a range of pathotypes including: EHEC, atypical enteropathogenic E. coli (aEPEC), potential EHEC (pEHEC) and non-toxigenic E. coli (NTEC) and split into two main clusters by pulsed field gel electrophoresis. When the preliminary characterisation data were combined with spatial and temporal data a subset of 40 out of 88 isolates comprising ten human and 30 cattle E. coli O26 isolates were selected for subsequent analysis. The response of E. coli O26 strains in planktonic or biofilm forms to a range of antimicrobials and sanitisers and the possible influence of pathotype or strain source was assessed. The survival of E. coli O26 to disinfectants in a planktonic state varies depending on which stressor is applied. Disinfectants containing quaternary ammonium compounds or peracetic acid inhibited the growth of E. coli O26 whereas hypochlorite and acid anionic based disinfectants were not effective. It was also demonstrated that O26 strains of all pathotypes examined here had elevated MICs (1,024 to 4,096 μg/ml) to acetic, propionic, lactic and citric acids. E. coli O26 in planktonic state did not demonstrate variability in resistance when source or pathotype was considered. To evaluate the survival capability of strains in biofilm state, biofilm formation on different surfaces was investigated. EHEC strains were more likely to form biofilms after 48 hr than aEPEC strains on polystyrene plates. However, biofilm formation was generally enhanced with increasing incubation time and was further enhanced for all pathotypes when stainless steel and glass slides were used as a contact surface. Interestingly, investigating pellicle formation at the air-liquid interface indicated that pellicle formation was primarily produced by EHEC strains and NTEC while it was absent from aEPEC. The study also demonstrated that prophage insertion in mlrA (yehV), mutations in RpoS, lack of motility and failure to produce cellulose and/or curli was associated with reduced biofilm forming capacity. It was also demonstrated that biofilms provided a protective effect to E. coli O26 strains against the three sanitisers, previously shown to successfully control the growth of their planktonic counterparts, regardless of pathotype, source and the amount of biofilm formed. The carriage of stx is a key factor in the ability of E. coli O26 to cause human disease. Stx bacteriophage insertion sites and the ability for stx to be gained or lost were investigated. It was found that Stx phages integrated into wrbA, yehV or near the torS gene, a novel not previously described insertion site. Although these loci were shown to be intact in stx-negative strains, this study was unable to detail the ability or frequency at which Stx phage are acquired by stx-negative O26 strains. The carriage of non Stx phage integrases was also assessed with pathotype specificity observed which likely promotes the differing genetic profiles observed between pathotypes. Comparative analysis of Stx phage induction, toxin production and stx expression (copy number) identified that lysogens were found to produce greater quantities of Stx than their parent counterparts. Overall, stx expression and Stx production were comparable between EHEC regardless of source thereby confirming the pathogenic potential of EHEC cattle strains. Finally, the use of whole genome sequencing (WGS) provides evidence of the continuous evolution and plasticity of the genome of this organism and its ability to undergo genetic rearrangements and further confirmed the relationship between human and cattle strains. This study determined that while pathotypes of E. coli O26 appear to be highly clonal regardless of source, certain pEHEC and aEPEC strains share similar genetic profiles to EHEC strains and could rapidly transition to EHEC via the acquisition of stx. E. coli O26 remains an organism of significance to global public health and cattle processing systems. This study has confirmed that cattle are a potential reservoir of EHEC strains capable of causing human disease and has demonstrated the ability of EHEC strains to survive in the presence of anti-bactericidal substances. Continued implementation of regular and effective sanitisation will assist in controlling the hazard and associated risk caused by this global public health and economically important pathogen to the food industry.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Natural Sciences
Science, Environment, Engineering and Technology
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Upadhyay, Ambika Prasad. "Characterization of photothermal flowering responses in maturity isolines of soyabean (Glycine max)". Thesis, University of Reading, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.331994.
Testo completo
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O'Donnell, Martin. "Finite element modelling of a multi-stage stretch-forming operation using aerospace alloys". Thesis, University of Ulster, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270463.
Testo completo
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Tram, Greg C. "Characterisation of Bacterial Biofilm Formation". Thesis, Griffith University, 2020. http://hdl.handle.net/10072/392378.
Testo completoAbstract (sommario):
Campylobacter jejuni is the largest contributor to bacterial gastroenteritis in the developed world. In addition to intestinal infections, this organism is implicated in the autoimmune neurodegenerative condition known as Guillain–Barré syndrome. C. jejuni is a common commensal organism of warm-blooded animals and avians that is passed to humans through contaminated food products or water. Biofilms are a specialised method of growth seen in many microbes and provide a means for bacteria to remain viable in harsh environmental conditions. The biofilms of C. jejuni have been hypothesised to play an important role in the transmission of infection. Herein, we aimed to investigate factors involved in C. jejuni biofilm formation as well as detailing the development of novel applications to established techniques.
The first chapter of this thesis aimed to evaluate the current understanding of biofilm formation in C. jejuni. We explored factors which play important roles in biofilm formation such as chemotaxis, glycosylation, microbial metabolism, quorum sensing and stress response regulators. These elements revealed that processes which are involved in the biofilm formation of C. jejuni are frequently at odds with those required for virulence and pathogenicity. This is contrary to biofilms of other organisms such a Pseudomonas aeruginosa which require biofilms for infection. We propose that biofilms of C. jejuni play a more important role in the transmission of infection rather than pathogenesis.
We then present a novel improvement to an existing method for quantification of biofilm formation. Currently, methods for quantification of biofilm formation rely on the dissolution of stained biofilm formed in microtiter plates. Solubilisation of the stain provides spectroscopic data which allows for comparisons between the relative levels of biofilm formed. The solvents used in current assays are ineffective at solubilising formed biofilm and give inconsistent results. This second chapter details the development of an alternate solvent which was able to provide complete dissolution of stained biofilm and, thus, improved the accuracy and robustness of plate-based biofilm assays. This new solvent was effective against a range of bacterial species and provides a marked improvement to microtiter plate-based methods for assessing biofilm formation.
The third chapter details a combinatorial approach to expression studies in C. jejuni biofilms focusing on the role of chemotaxis signal transduction. RNA sequencing was used to examine relative differences in transcript levels between planktonic C. jejuni and those contained in a biofilm. This was combined with proteomic data obtained using iTRAQ to provide a complete profile of differential gene expression. Differential expression was observed in approximately 600 genes, with 300 displaying upregulation during biofilm formation (e.g. iron metabolism, glycan production and cell division) and 300 showing downregulation (such as metabolism and amino acid metabolism). Large tracts of the chemotaxis pathway displayed downregulation, which we investigated further using mutant C. jejuni strains deficient in the key chemotactic proteins CheV and CheW. Both of these mutant strains exhibited a significant increase in the ability to form biofilm through increased establishment of microcolonies. The absence of these signal transduction proteins also had a marked effect on motility and autoagglutination. We hypothesized that the diminished motility of the mutant strains allows for an increase in autoagglutination and, thus, more efficient microcolony formation which presents a potential pathway for modulating biofilm formation in C. jejuni.
The next chapter presents a role for N-linked protein glycosylation in C. jejuni biofilm formation. Phenotypic analysis of mutant strains deficient in key enzymes, PglB and PglF, shows that in the absence of protein glycosylation, there is a substantial increase in the ability for C. jejuni to form biofilms. This appeared to be a result of increased autoagglutination leading to an increase in microcolony formation, a mechanism similar to that observed in CheV and CheW. The architecture of the formed biofilms also appears to have been altered; SEM analysis of biofilms shows a filamentous appearance in mutant strains. This may present a further means for regulating biofilm formation in C. jejuni.
The work contained in this thesis identified a number of important factors which play a role in the biofilm formation of C. jejuni. It also demonstrates that coupling transcriptomic and proteomic analysis can provide a comprehensive profile of differential gene expression during biofilm formation.
Many of the approaches and techniques detailed are also novel applications which have seldom been applied to the field of biofilms. These insights aim to improve not only the understanding of bacterial biofilm formation as a whole, but also the methods in which we can study them.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Institute for Glycomics
Griffith Health
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Andersson, Mikael. "Characterisation of Chromatography Media Aimed for Purification of Biomolecules". Doctoral thesis, Uppsala universitet, Analytisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-234743.
Testo completoAbstract (sommario):
Chromatography media (resins) are very important for and widely used by the biopharma industry in large scale production of biopharmaceuticals, e.g. monoclonal antibodies. Today there are several hundred biopharmaceuticals released globally on the healthcare market. This thesis discusses various strategies and methods for the characterisation of chemical and functional stability of chromatography media. In addition, various analytical techniques used in these areas were evaluated and applied. Further, more specific physical and chemical characterisation methods were evaluated and applied to explore different properties of various chromatography media. In Papers I-III, established methodologies for performing chemical and functional stability studies were used. Mainly agarose-based chromatography media were investigated. For fast screening of the chemical stability, the total organic carbon analysis technique was evaluated and applied. This technique that measures the carbon leakage from the chromatography media at different conditions, proved to be very suitable and robust. For detection and/or identification of leakage compounds responsible for or for part of the measured carbon leakage, different methods such as (high performance) liquid chromatography and gas chromatography mass spectrometry were used. In Papers IV-VII, different properties (i.e. functional performance, ligand content and surface chemistry) were evaluated for different agarose-based chromatography media. Standard chromatographic methods (ion exchange chromatography) and spectroscopic methods (e.g. Fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectrometry) were evaluated and applied. Chemometric methods were used for efficient evaluation of data. Information of chemical, functional and leakage data of chromatography media are valuable and important for the biopharmaceutical companies to be able to fulfil the regulatory requirements of biopharmaceuticals. In addition, information of various chemical, functional and physical properties of chromatography media is likewise important during development and set up of new biopharmaceutical processes.
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Sinclair, Derek C. "Electrical characterisation of ferroelectric oxides". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 1989. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59668.
Testo completo