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1
Stufler, Josef. "Modification-Management". Doctoral thesis, Universitätsbibliothek Chemnitz, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200900596.
Testo completoAbstract (sommario):
Die Produkte von Maschinen- und Anlagenbauunternehmen stellen in der Regel langlebige, kundenspezifische Investitionsgüter dar. Je umfangreicher die Konstruktions- und Montagezeiten des Investitionsgutes, umso frühzeitiger muss der Kunde sich festlegen, welche Leistungsmerkmale gefordert werden und unter welchen Bedingungen die Maschine oder Anlage arbeiten muss. Hierbei kommt es regelmäßig zu Divergenzen zwischen dem Bedarf des Kunden zum Lieferzeitpunkt, der Nachfrage zum Zeitpunkt der Kaufentscheidung und dem Angebot des Anbieters. Um diese Divergenzen ab dem Zeitpunkt des Kaufs zu beheben, sind mehr oder weniger kostenintensive technische Leistungsveränderungen – so genannte Modifications – erforderlich. Die Arbeit zeigt zum einen Erkenntnisse aus der Untersuchung von Modifications. Zum anderen bietet sie ein theoretisch und insbesondere ein empirisch orientiertes, umsetzbares System (Modification- Management), mit dem dieser Problematik nachhaltig begegnet bzw. der Umgang damit optimal gestaltet werden kann.
2
Schorova, Lenka. "Étude des mécanismes de régulation synaptique de la balance sumoylation/désumoylation". Electronic Thesis or Diss., Université Côte d'Azur (ComUE), 2018. http://theses.univ-cotedazur.fr/2018AZUR4021.
Testo completoAbstract (sommario):
La SUMOylation est une modification post-traductionnelle essentielle pour toutes les cellules eucaryotes. C’est un processus enzymatique qui permet la liaison covalente du polypeptide SUMO sur des résidus lysine de protéines cibles. La SUMOylation est un processus réversible sous l’action de désumoylases appelées SENP. Il est critique de maintenir un équilibre entre forme modifiée et non modifiée d’un substrat donné. En effet, la dérégulation de la balance SUMOylation/déSUMOylation a été mise en évidence dans plusieurs pathologies cérébrales. La synapse est le point de contact entre les neurones où s’effectue la communication synaptique. Ce sont des structures très denses où le processus de SUMOylation régule l’interaction et la fonction de multiples protéines. Durant ma thèse, j'ai combiné l’utilisation de l'imagerie en temps réel sur cellules vivantes avec des approches biochimiques et pharmacologiques pour identifier les mécanismes de régulation du transport de SENP1. J'ai ainsi démontré que l'activation neuronale augmente les niveaux synaptiques de SENP1. Cette augmentation synaptique résulte de la modification de la vitesse de diffusion de l’enzyme SENP1 entre les dendrites et les synapses d’une part, et d’autre part, de l’augmentation importante du temps de rétention synaptique de l’enzyme. Je rapporte également que ce mécanisme de régulation dynamique de SENP1 implique l'activation des récepteurs métabotropiques du glutamate. De plus, je suggère la participation du processus de phosphorylation dans cette régulation synapto-dendritique de SENP1 mettant ainsi en lumière un nouveau mécanisme de régulation de la balance neuronale entre SUMOylation et déSUMOylationSumoylation is a vital eukaryotic posttranslational modification. Sumoylation occurs as an enzymatic cycle that conjugates SUMO proteins to target proteins. SUMO proteases (SENP) deconjugate SUMO from modified proteins and thus maintain balanced levels of SUMOylated and un-SUMOylated proteins required for physiological homeostasis. Neuronal synapses are protein-rich structures that underlie synaptic transmission and plasticity. Strong evidence exists that sumoylation occurs in synapses and regulates the function of synaptic proteins. Indeed, distortion of the SUMO balance has been linked to several pathologies of the synapse. Gaining a deeper understanding into the molecular mechanisms regulating the SUMO balance is a prerequisite to envisaging the development of novel therapies. In my PhD work, I used a combination of live-cell confocal imaging, protein biochemistry and pharmacological approaches to identify SENP1 regulatory mechanisms at synapses. I provided evidence that synaptic activation increases SENP1 protein levels at synapses. I showed that the increase in synaptic SENP1 upon synaptic activation is a result of two processes: Although (a) fewer SENP1 proteins enter into spines at low diffusion speed (b) a significant proportion of SENP1 becomes immobile and is retained in spines. I demonstrate that the regulatory mechanisms of SENP1 dynamics involve a direct activation of mGlu1/5 receptors. Moreover, I suggest that phosphorylation may play an important regulatory role in SENP1 synapto-dendritic diffusion. Altogether, I propose a novel mechanism driving for the SUMO balance at synapses
3
Filatov, A. V., e A. E. Pogorelov. "MTJ properties modification". Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20974.
Testo completo
4
Hunter, Paul Carleton University Dissertation Engineering Electrical. "Knowledge base modification". Ottawa, 1991.
Cerca il testo completo
5
Withers, Freddie. "Chemical modification of graphene". Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4081.
Testo completoAbstract (sommario):
In this thesis investigations into chemically modified graphene structures are presented. Chemical functionalization of graphene is the chemical attachment of molecules or atoms to the graphene surface via covalent or Van der Waals bonds, this process offers a unique way to tailor the properties of graphene to make it useful for a wide range of device applications. One type of chemical functionalization presented in this thesis is fluorination of graphene which is the covalent attachment of fluorine to the carbon atoms of graphene and the resultant material is fluorographene which is a wide band-gap semiconductor. For low fluorine coverage the low temperature electron transport is through localized states due to the presence of disorder induced sub-gap states. For high fluorine coverage the electron transport can be explained by a lightly doped semiconductor model where transport is through thermal activation across an energy gap between an impurity and conduction bands. On the other hand, at low temperatures the disorder induced sub-gap density of states dominates the electrical properties, and the conduction takes place via hopping through these localized states. In this thesis it is also shown that electron beam irradiation can be used to tune the coverage of fluorine adatoms and therefore control energy gap between the impurity and conduction bands. Futhermore, electron beam irradiation also offers a valuable way to pattern conductive structures in fluorinated graphene \textit{via} the irradiation-induced dissociation of fluorine from the fluorinated graphene. This technique can be extended to the patterning of semiconducting nano-ribbons in fluorinated graphene where the spatial localization of electrons is just a few nm. The second type of chemical functionalization presented in this thesis is the intercalation of few layer graphene with ferric chloride which greatly enhances the electrical conductivity of few layer graphene materials making them the best known transparent conductors.
6
Thomas, Matthew Rhys. "Polyvinyl alcohol surface modification". Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:279fe53b-7d61-43de-a91a-be658dd01eda.
Testo completoAbstract (sommario):
Poly(vinyl alcohol) (PVA) is a polymer used in numerous applications, principally those in which its high water solubility is a desirable asset. However there are also areas where PVA is limited by its inherent solubility (for example some specific environments in the biomedical field). This work has sought to overcome such limits by manipulating the surface of PVA in order to propose various means by which the surface solvent resistance might be increased while maintaining the bulk properties of the polymer. Both chemical and physical modifications have been tried and in each case progress has been made towards insolubilizing a single surface of the polymer when in film form. Grafting various species onto the surface of PVA was successfully performed. It is believed that such species bonded to the PVA via attachment to the hydroxyl groups (though this has not been proven conclusively). The data contained herein has led to the conclusion that the primary factor in reducing solubility this way is the removal of the hydroxyl groups, and not the attachment of specifically highly hydrophobic molecules. Introducing permanent cross-links into the surface region has been attempted via various routes. The data recorded shows promise however the system is far from optimised. The biggest challenge remaining is to optimise the depth of material cross-linked. Some steps have been made towards understanding and controlling this parameter though there is much scope for further investigation. The methods used have built on those used for bulk cross-linking and as such are new for the case of surface specific treatment. An interesting phenomenon in some semi-crystalline polymers reported in recent years is that of surface specific crystallization. This effect has been successfully induced and observed in PVA to produce what is believed to be a highly crystalline surface layer, and crystalline regions of PVA are generally accepted to be more water resistant than amorphous ones. In summary, in this work several surface-specific treatments for PVA have been trialled, providing options for post-film forming modification to reduce the surface water sensitivity whilst retaining the bulk properties of the polymer.
7
Kirk, Raymond Clarence. "Fear : measurement and modification". Thesis, University of Canterbury. Psychology, 1985. http://hdl.handle.net/10092/5821.
Testo completoAbstract (sommario):
The avoidance and response prevention (RP) literatures are reviewed. This review highlighted a number of persistent issues, revealed a need for the development of sensitive fear assessment measures and showed a number of parameters that enhance response prevention's efficacy in reducing conditioned fear. This thesis examined (i) a number of RP parameters across escape-from-fear and passive avoidance baselines, using in the latter situation, multivariate fear assessment measures; and (ii) the psychopharmacological actions of the benzodiazepine, diazepam, and beta-adrenergic blockers, propranolol and atenolol, across passive avoidance, conditioned suppression of licking and signal detection behavioural baselines.
In experiment one, escape-from-fear behaviour was found to be insensitive to 100 - and 200 - non-reinforced 5 second CS presentations (RP). Massed RP was reported to be superior to distributed RP and protracted RP (2 hr) more efficacious than 1 hr RP in reducing conditioned fear and hastening avoidance extinction in experiment two. Social facilitation of RP (experiment three) enhanced RP effects when assessed by the time fear assessment measure but had less effect on RP when assessed by the approaches and first entry latency measures. This differential sensitivity of the fear assessment measures was also reported for diazepam, propranolol and atenolol - assisted RP (experiments three and four).
Experiment five examined the separate and combined administration of diazepam and propranolol on disinhibiting licking behaviour. Diazepam was more effective than the combined treatment, which in turn was more effective than propranolol alone, with atenolol having little effect in disinhibiting licking behaviour.
Experiment six established a signal detection behavioural baseline which was used to independently assess possible diazepam - and propranolol-induced changes in stimulus discrimination from possible drug-induced changes in response-bias (experiment seven). Both diazepam and, propranolol failed to affect response bias, whereas stimulus discrimination was attenuated by propranolol but unaffected by diazepam administration.
The response prevention results were discussed in terms of a modified two process theory presented in chapter two, which emphasised the relative sensitivity of and the relationship between the fear assessment measures in discriminating RP effects on conditioned fear and avoidance behaviour. The drug results were discussed in terms of the respective modes of anxiolytic action of the benzodiazepines and beta-adrenergic blockers. This signal detection results were discussed in terms of matching model and signal detection analyses of choice behaviour. Implications of these results to avoidance theory and research as well as to the assessment and treatment of fear motivated human neurotic behaviours were discussed with suggestions for future research being presented.
8
Kilic, Suha. "Modification of Huffman Coding". Thesis, Monterey, California. Naval Postgraduate School, 1985. http://hdl.handle.net/10945/21449.
Testo completo
9
Griffiths, Jonathan. "Structural modification of DNA". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315114.
Testo completo
10
Kane, Charles B. "Plasma modification of linen". Thesis, University of Ulster, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274070.
Testo completo
11
Dykes, Graham Mark. "Supramolecular dendritic property modification". Thesis, University of York, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411458.
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12
Holding, Finn Peter. "Chemical modification of streptavidin". Thesis, Open University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384989.
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13
Sheikh, Shehla Altaf. "Modification of mesoporous silicas". Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327599.
Testo completo
14
Cox, Owen. "Chemical modification of polysulfone". Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665375.
Testo completoAbstract (sommario):
The research presented herein is concerned with the chemical modification of polysulfone towards the synthesis of a hollow fibre boronic acid fixed carrier membrane system for saccharide separation. Chapter 1 firstly introduces the area of boronic acids as chemosensors, in particular for detecting saccharides. Secondly, membrane separation techniques are discussed focussing on hollow fibre membranes and their synthesis. Chapter 2 discusses the potential of boronic acid fixed carrier hollow fibre membranes for saccharide separation. Three general routes are highlighted to achieve the desired boronic acid appended polymers: electrophilic aromatic substitution, lithiation and functional monomer polymerisation. Chapter 3 describes the various attempts at achieving the target polymer via electrophilic aromatic substitution methodology. Chapter 4 describes the various attempts at achieving the target polymer via lithiation methodology. Chapter 5 investigates the ability to create functional monomers with which functional polymers can be polymerised from. Chapter 6 describes the synthesis and characterisation of the compounds discussed in chapters 3, 4 and 5.
15
Huh, Dongsung 1981. "Ca2+ dependant synaptic modification". Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32741.
Testo completoAbstract (sommario):
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics; and, (S.B.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2004.Includes bibliographical references (p. 21-22).
It has been assumed that Ca2+ influx of different duration and amplitude would generate different level of potentiation. The conventional protocols of generating LTP have been 1. tetanic stimulation of presynaptic cell, 2. theta burst stimulation of presynaptic cell, and 3. correlated stimulation of pre- and post-synaptic cells. However, the effects of different Ca2+ influx can not be precisely dissected with the conventional protocols for the following defects: 1. the protocols do not discriminate between pre- and post-synaptic side plasticity, 2. the protocols observe synaptic plasticity between two cells which involve multiple synapses with heterogeneous properties, 3. precise control and measurement of the amount of Ca2+ influx are not possible in the protocols. In the present experiment, we perfused glutamate directly on to a single postsynaptic site, depolarized the postsynaptic intracellular potential to a controlled voltage for a controlled duration of time, thus controlling the opening of postsynaptic NMDA receptors and Ca2+ influx. By using this method, we found 1. that modification of synaptic strength has a bell-shaped dependency to the amount of Ca2+ influx, 2. that weak Ca2+ current through desensitized NMDA receptors sustained for a long period of time (160 ms) generates LTD, 3. evidence that phosphorylation of AMPAR leads to insertion of AMPAR.
by Dongsung Huh.
S.B.
16
Herselman, Trevor Dwayne. "A further modification, elaboration". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86685.
Testo completoAbstract (sommario):
Thesis (MComm)--Stellenbosch University, 2014.ENGLISH ABSTRACT: South African organisations within both the private and public sectors of the economy are investing heavily into their talented employees, in an attempt to derive a sustainable competitive advantage. This competitive advantage is threatened when employees engage in turnover behaviours. This study is directed at understanding those factors that contribute to employees’ intention to quit following employees’ perceptions of training and development initiatives. Empirical support has been found that certain line management talent management competencies would result in the retention of talented employees. This study investigated an existing talent management competency structural model, with a specific focus on two talent management competencies related to employee development, namely: Talent Management Mindset and Develops Others. Furthermore, this study investigated the inclusion of additional latent variables (Organisational Trust, Perceived Organisational Support, and Felt Obligation) that may potentially explain additional variance in various organisational outcome variables (i.e. Job Satisfaction, Affective Commitment, Normative Commitment, and Intention to Quit). Through understanding how line managers’ competence on talent management competencies influence employees’ perceptions of organisational development initiatives and how these employee perceptions are causally related to Intention to Quit, organisations will be in the prime position to effectively address the issue of employee turnover, through structured talent management retention programmes. The results of the current study showed that the original structural model displayed good fit. Based on the modification index values calculated for the G and B matrices, a number of modifications were made to the structural model. Following the modifications to the original model, the fit of the model improved, and support was derived for numerous causal relationships proposed in the model, whist others were not supported.
AFRIKAANSE OPSOMMING: Suid - Afrikaanse organisasies in beide die privaat – en openbare sektor maak beduidende beleggings in hul talentvolle werknemers in ‘n poging om ‘n volhoubare mededingende voordeel te bewerkstellig. Hierdie mededingende voordeel word egter bedreig wanneer werknemers die organisasie verlaat. Die studie het ten doel gehad om die faktore te verstaan wat bydra tot werknemers se diensverlatingsvoorneme gegee hul persepsie van opleiding en ontwikkelings - inisiatiewe. Die empiriese bevindinge toon dat sekere lynbestuur - talentbestuurbevoegdhede lei tot die behoud van talent. Die studie het ‘n bestaande talentbestuur bevoegdheids model ondersoek, met ‘n spesifieke fokus op twee talentbestuur bevoegdhede wat verband hou met werknemer ontwikkeling, naamlik: Talentbestuur – ingesteldheiden Ontwikkeling van Ander. Die studie het voorts ook die insluiting van addisionale latent veranderlikes (Organisatoriese Vertroue, Waargenome Organisatoriese Ondersteuning, en Verpligting Ervaar) ondersoek wat moontlik addisionele variansie in verskeie organisatoriese uitkoms veranderlikes kan verklaar (i.e. Werkstevredenheid, Affektiewe Verbintenis, Normatiewe Verbintenis, en Diensverlatingsvoornemes). Deur te verstaan hoe lynbestuurders se bevoegdheid op talentbestuur bevoegdhede werknemers se persepsies van organisatoriese ontwikkelings-inisiatiewe beïnvloed en hoe hierdie persepsie oorsaaklik verband hou met Diensverlatingsvoorneme, sal organisasies in ‘n gunstige posisie wees om diensverlating op ‘n effektiewe wyse aan te spreek deur middel van gestruktureerde talentbestuur behoud programme. Die resultate van die huidige studie toon dat die oorspronklike strukturele model goeie pasgehalte behaal het. Na aanleiding van die modifikasie–indekswaardes wat bereken is vir die G en B matryse , is ‘n aantal veranderinge aan die strukturele model gemaak. Nadat die veranderinge aan die oorspronklike model aangebring is, het die pasgehalte van die model verbeter en steun is verkry vir verskeie oorsaaklike verwantskappe wat voor gehou is in die model, terwyl ander nie steun verkry het nie.
17
Jin, Li. "Chemical modification of polymers". Thesis, Aston University, 1988. http://publications.aston.ac.uk/9706/.
Testo completoAbstract (sommario):
Based on the knowledge of PVC degradation and stabilisation, chemical modifications were imposed on degraded PVC and raw PVC with the aim of obtaining non-migrating additives. The modifications were carried out mainly in the presence of dibutyl maleate (DBM), and the resulting polymer contained dibutyl maleic residues. Such modifications result in a polymer which contain substantive additives which resist migration under aggressive environments. Previous studies have shown that stable nitroxyl radicals function as stabilisers in polymer during processing (e.g. PP, PVC) by deactivating a large number of kinetic chains via a redox process whereby the concentrations of the nitroxyl and its reduced form, the hydroxylamine, fluctuate reciprocally and rhythmically. In order to understand the major reactions involved in such systems, a simulation method was used which resulted in a mathematical model and some rate constants, explaining the kinetic behaviour exhibited by such system. In the process of forming a suitable model, two nonlinear oscillators were proposed, which could be of interest in the study of nonlinear phenomenon because of their chaotic behaviour.
18
Pei, Xiaoyin. "Acid modification of psyllium". College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8963.
Testo completoAbstract (sommario):
Thesis (M.S.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Nutrition and Food Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
19
Fajtl, Zdeněk. "Study of qualitative parameters of fruit juices and possibilities of their modification via technological modifications". Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-217155.
Testo completoAbstract (sommario):
Ovocné šťávy jsou celosvětově nejoblíbenějšími nealkoholickými nápoji. Kromě vitamínů a minerálů jsou také bohatým zdrojem polyfenolů, které jsou považovány za látky přispívající k celkové antioxidační aktivitě. Zvyšující se požadavky konzumentů na kvalitu a bezpečnost potravin nutí výrobce k zvyšování výrobních a kvalitativních standardů potravin. Nedávné inovace ve výrobě ovocných šťáv vedly k modifikacím výrobních podmínek, které zahrnují změny ve složení šťávy (např. přídavek ovocné dužiny nebo malých ovocných kousků), vylepšování vlastností obalových materiálů a modifikace produkční atmosféry. Cílem diplomové práce bylo pomocí metod EPR a UV-VIS spektroskopie posoudit vliv různých výrobních postupů na vybrané kvalitativní znaky (antioxidační aktivita, změna barvy a koncentrace vybraných fytochemikálií) pomerančových šťáv s dužinou a ananasových šťáv, a charakterizovat jejich změny v průběhu dlouhodobého skladování. Získané výsledky byly zpracovány metodami multivariační statistické analýzy s cílem posoudit vliv původu suroviny, roku produkce a použitých výrobních podmínek na sledované parametry a celkovou kvalitu ovocných džusů. Výsledky jasně prokázaly, že pasterizace ovlivňuje kvalitu výrobku; ačkoli byla použita „šetrná“ pasterizace, byl u těchto vzorků pozorován mírný pokles prakticky všech monitorovaných parametrů v porovnání s čerstvými – nepasterizovanými šťávami. Avšak pokud jde o po-pasterizační změny, byl prokázán významný vliv produkční atmosféry na monitorované kvalitativní parametry šťáv, prokazující, že náhrada kyslíku inertními plyny může výrazně prodloužit trvanlivost šťáv. Kinetické studie změn sledovaných parametrů na době skladování ukazují, že ve většině případů dochází k postupnému zhoršování všech monitorovaných parametrů, a to bez ohledu na technologii zpracování šťávy. Ve vzorcích vyrobených použitím modifikované atmosféry bylo, v závislosti na typu inertního plynu, pozorováno zpomalení poklesu jednotlivých kvalitativních parametrů šťáv jako výsledek aplikace inertní atmosféry. Tento trend byl zřejmý především pro delší skladovací období, zatímco na začátku skladování (6 - 7 týdnů po výrobě dané šťávy) byly pozorované trendy nejednoznačné. Lze proto předpokládat že tento „ochranný“ efekt inertní atmosféry je ovlivňován fyzikálně-chemickými vlastnostmi jednotlivých plynů, zejména jejich rozpustností v kapalném médiu. Výsledky také prokázaly že vlastnosti šťáv jsou ,bez ohledu na druh ovoce, výrazně ovlivňovány také sezónními vlivy a původem surové šťávy. Z výsledků statistické analýzy vyplývá, že rok výroby je silným diskriminačním faktorem. Na základě všech monitorovaných charakteristik, bylo dosaženo absolutní diskriminace vzorků pomocí kanonické diskriminační analýzy. Pokud jde o původ surovin, byla dosažena pouze částečná diferenciace, i když s poměrně vysokým klasifikačním skóre. Pokud jde o technologii výroby, byla dosažena pouze částečná diferenciace vzorků podle typu použitého inertního plynu. Získané poznatky pomohou výrobcům ovocných šťáv s optimalizací výrobních podmínek s cílem získat výrobek s maximem prospěšných vlastností, které by si udržel po celou dobu expirace, jejíž délka může být také optimalizovány na základě prezentovaných výsledků.
20
Schorova, Lenka. "Étude des mécanismes de régulation synaptique de la balance sumoylation/désumoylation". Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4021.
Testo completoAbstract (sommario):
La SUMOylation est une modification post-traductionnelle essentielle pour toutes les cellules eucaryotes. C’est un processus enzymatique qui permet la liaison covalente du polypeptide SUMO sur des résidus lysine de protéines cibles. La SUMOylation est un processus réversible sous l’action de désumoylases appelées SENP. Il est critique de maintenir un équilibre entre forme modifiée et non modifiée d’un substrat donné. En effet, la dérégulation de la balance SUMOylation/déSUMOylation a été mise en évidence dans plusieurs pathologies cérébrales. La synapse est le point de contact entre les neurones où s’effectue la communication synaptique. Ce sont des structures très denses où le processus de SUMOylation régule l’interaction et la fonction de multiples protéines. Durant ma thèse, j'ai combiné l’utilisation de l'imagerie en temps réel sur cellules vivantes avec des approches biochimiques et pharmacologiques pour identifier les mécanismes de régulation du transport de SENP1. J'ai ainsi démontré que l'activation neuronale augmente les niveaux synaptiques de SENP1. Cette augmentation synaptique résulte de la modification de la vitesse de diffusion de l’enzyme SENP1 entre les dendrites et les synapses d’une part, et d’autre part, de l’augmentation importante du temps de rétention synaptique de l’enzyme. Je rapporte également que ce mécanisme de régulation dynamique de SENP1 implique l'activation des récepteurs métabotropiques du glutamate. De plus, je suggère la participation du processus de phosphorylation dans cette régulation synapto-dendritique de SENP1 mettant ainsi en lumière un nouveau mécanisme de régulation de la balance neuronale entre SUMOylation et déSUMOylationSumoylation is a vital eukaryotic posttranslational modification. Sumoylation occurs as an enzymatic cycle that conjugates SUMO proteins to target proteins. SUMO proteases (SENP) deconjugate SUMO from modified proteins and thus maintain balanced levels of SUMOylated and un-SUMOylated proteins required for physiological homeostasis. Neuronal synapses are protein-rich structures that underlie synaptic transmission and plasticity. Strong evidence exists that sumoylation occurs in synapses and regulates the function of synaptic proteins. Indeed, distortion of the SUMO balance has been linked to several pathologies of the synapse. Gaining a deeper understanding into the molecular mechanisms regulating the SUMO balance is a prerequisite to envisaging the development of novel therapies. In my PhD work, I used a combination of live-cell confocal imaging, protein biochemistry and pharmacological approaches to identify SENP1 regulatory mechanisms at synapses. I provided evidence that synaptic activation increases SENP1 protein levels at synapses. I showed that the increase in synaptic SENP1 upon synaptic activation is a result of two processes: Although (a) fewer SENP1 proteins enter into spines at low diffusion speed (b) a significant proportion of SENP1 becomes immobile and is retained in spines. I demonstrate that the regulatory mechanisms of SENP1 dynamics involve a direct activation of mGlu1/5 receptors. Moreover, I suggest that phosphorylation may play an important regulatory role in SENP1 synapto-dendritic diffusion. Altogether, I propose a novel mechanism driving for the SUMO balance at synapses
21
Srubiski, Aviva. "Modification of red cell antigenic characteristics via covalent modification with branched poly (ethylene glycol)". Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/32404.
Testo completoAbstract (sommario):
Background: Red Blood Cell (RBC) transfusions are associated with the risk of rejection and
sensitization for the recipient. Covalent modification of human RBC using poly (ethylene
glycol)) (PEG) is currently being investigated as a method to modify the antigenic characteristics
of RBC in order to develop an antigenically silent RBC transfusion product. The focus of this
study is to determine whether a branched PEG, 4PEGss [MW 10,000] can concurrently
camouflage and stabilize the RBC membrane, giving the red cell higher osmotic resistance.
Study Design and Methods: Human blood was collected from consenting donors into EDTA
tubes. RBC were separated, counted, washed and incubated with 4PEGss stock solution for up
to 120 minutes at room temperature (RT). Agglutination assays and flow cytometry were used
to determine polymer-dependent antigen masking while scanning electron microscopy (SEM),
erythrocyte sedimentation rate (ESR) assays, osmotic fragility assays, hemolysis measurements
and generation of hemoglobin oxidation species were used to measure the impact of 4PEGss
treatment on RBC function.
Results: Agglutination assays and flow cytometry showed that 4PEGss treatment significantly
camouflaged RhD and A and B antigens in a dose-dependent manner. However, SEM and ESR
assays indicated 4PEGss treatment may cause cell aggregate formation. Osmotic fragility assays
and hemolysis measurements showed a 4PEGss-mediated increase of hemolysis.
Conclusions: At all concentrations investigated, 4PEGss modification yielded antigenically
camouflaged (both ABO and RhD) yet less stable RBC compared to non-treated controls.Medicine, Faculty of
Pathology and Laboratory Medicine, Department of
Graduate
22
Persson, Per. "Strategies for cellulose fiber modification". Doctoral thesis, KTH, Fibre and Polymer Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3730.
Testo completoAbstract (sommario):
This thesis describes strategies for and examples ofcellulose fiber modification.The ability of an engineered biocatalyst, acellulose-binding module fused to theCandida antarcticalipase B, to catalyze ring-openingpolymerization of e-caprolactone in close proximity tocellulose fiber surfaces was explored. The water content in thesystem was found to regulate the polymer molecular weight,whereas the temperature primarily influenced the reaction rate.The hydrophobicity of the cellulose sample increased as aresult of the presence of surface-deposited polyester.
A two-step enzymatic method was also investigated. Here,Candida antarctica lipase B catalyzed the acylation ofxyloglucan oligosaccharides.The modified carbohydrates werethen incorporated into longer xyloglucan molecules through theaction of a xyloglucan endotransglycosylase. The modifiedxyloglucan chains were finally deposited on a cellulosesubstrate.
The action ofCandida antarcticalipase B was further investigated inthe copolymerization of e-caprolactone and D,L-lactide.Copolymerizations with different e-caprolactone-to-D,L-lactideratios were carried out. Initially, the polymerization wasslowed by the presence of D,L-lactide. During this stage,D,L-lactide was consumed more rapidly than ε-caprolactoneand the incorporation occurred dimer-wise with regard to thelactic acid units.
Morphological studies on wood fibers were conducted using asol-gel mineralization method. The replicas produced werestudied, without additional sample preparation, by electronmicroscopy and nitrogen adsorption. Information concerning thestructure and accessibility of the porous fiber wall wasobtained. Studies of never-dried kraft pulp casts revealedmicro-cavities and cellulose fibrils with mean widths of 4.7(±2) and 3.6 (±1) nm, respectively.
Finally, cationic catalysis by simple carboxylic acids wasstudied. L-Lactic acid was shown to catalyze the ring-openingpolymerization of ε-caprolactone in bulk at 120 °C.The reaction was initiated with methylß-D-glucopyranoside, sucrose or raffinose, which resultedin carbohydrate-functionalized polyesters. The regioselectivityof the acylation was well in agreement with the correspondinglipase-catalyzed reaction. The polymerization was alsoinitiated with a hexahydroxy-functional compound, whichresulted in a dendrimer-like star polymer. The L-lactic acidwas readily recycled, which made consecutive reactions usingthe same catalyst possible.
Keywords:Candida antarcticalipase B, cationic catalysis,cellulose-binding module, dendrimer, enzymatic polymerization,fiber modification, silica-cast replica, sol-gelmineralization, organocatalysis, xyloglucanendotransglycosylase
23
Peltier, Raoul. "Biomimetic modification of crystal growth". Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/7150.
Testo completo
24
Erkilic, Umut. "Biotechnological Modification Of Steroidal Structures". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609258/index.pdf.
Testo completoAbstract (sommario):
Steroids are important biological regulators existing in hormones which are used to
control metabolism of the body. There are widespread applications in the
pharmaceutical industry. Drugs of steroid nature - anti-inflammatory and antiallergic
corticosteroids, diuretics, anabolics, androgens, gestagens, contraceptives,
antitumor medications, etc. - are now widely used in human and veterinary medicine.
Nowadays, biotechnological modifications of steroids are preferred over chemical
modifications as a green chemistry since they are more likely to be natural.
In this work four different Fusarium species were screened for bioconversion of
steroids into pharmaceutically important derivatives of steroids by reduction,
dehydrogenation, side-chain degradation etc. on A and D-rings containing many
active sites.
Fusarium spp. used in this work, namely Fusarium roseum OUT 4019, Fusarium
anguioides OUT 4017, Fusarium bulbigenum OUT 4115 and Fusarium solani OUT
4021 are filamentous fungi, which belong to the class of Deuteromyces. They can
grow using simple carbohydrates and nitrogen sources.
4-androstene-3,17-dione conversion is used as a model system. Under same
environmental conditions it is found that whole cells of Fusarium roseum OUT 4019
can dehydrogenate at C-1 and C-2 producing androsta-1,4-diene-3,17-dione and also
reduce at C-17 in addition to dehydrogenate at C-1 and C-2 producing 17-hydroxyandrosta-
1,4-dien-3-one, Fusarium anguioides OUT 4017 can reduce at C-17
producing 17-hydroxy-androst-4-en-3-one, Fusarium solani OUT 4021 can reduce at
C-3 and C-17 producing androst-4-ene-3,17-diol at 25 C°and 160 rpm with uncontrolled pH. In these conversions, androsta-1,4-diene-3,17-dione, 17-hydroxy-androsta-1,4-dien- 3-one, 17-hydroxy-androst-4-en-3-one, androst-4-ene-3,17-diol were isolated with 54 %, 22 %, 26 %, 90 % yields, respectively. In another study, bioconversion reactions of aromatic methyl ethers by Fusarium roseum OUT 4019 were investigated and for some compounds, cleavage of methyl ether was observed.
25
Cicek, Gulcin. "Synthesis Characterization And Modification Of". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614196/index.pdf.
Testo completoAbstract (sommario):
The constitutive studies of this thesis were achieved and presented in three parts. In the first part, the effects of solid state synthesis process parameters and the impurity content of primary calcium precursor on the cement-type hydration efficiency for the conversion of &alpha-tricalcium phosphate (Ca3(PO4)2 or &alpha
-TCP) into hydroxyapatite (Ca10-xHPO4(PO4)6-x(OH)2-x x = 0&ndash
1, or HAp) have been investigated (at 37°
C). &alpha
-TCP was synthesized by thermal processing of stoichiometric amounts of calcium carbonate (CaCO3) and monetite (CaHPO4) at 1150&ndash
1350°
C for 2 h. Three commercial grade CaCO3 powders of different purity were used as starting materials for the synthesis process and the resultant &alpha
-TCP products for all synthesis routes were compared in terms of the material properties and their reactivities. In the second part of the studies, &alpha
-TCP and chitosan fiber (CF) composites were prepared as injectable bone cement systems which have a potential to degrade in time to be replaced by the natural bone tissue. &alpha
-TCP/CF composites were prepared in different compositions and the effect of CF addition on cement properties were examined by mechanical and injectability tests as well as microstructural and phase analysis studies. In the third part of the studies, metal chelating property of CFs was used on development of controlled zinc release systems that can be applied in local zinc deficiency therapies of bone tissue. For this purpose, CF scaffolds were prepared by wet-spinning technique and appropriate amount of zinc was loaded to these scaffolds in regard to the zinc content of a healthy human bone tissue. Zinc release studies were performed on calcium phosphate (CaP) covered and non-covered CF scaffolds and zinc ion concentrations of the release solutions were determined by ICP-MS.
26
Dalilsafaei, Seif. "Stiffness modification of tensegrity structures". Licentiate thesis, KTH, Strukturmekanik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-34039.
Testo completoAbstract (sommario):
Although the concept of tensegrity structures was invented in the beginning of the twentieth century, the applications of these structures are limited, partially due to their low stiffness. The stiffness of tensegrities comes from topology, configuration, pre-stress and initial axial element stiffnesses. The first part of the present work is concerned with finding the magnitude of pre-stress. Its role in stiffness of tensegrity structures is to postpone the slackening of cables. A high pre-stress could result in instability of the structure due to buckling and yielding of compressive and tension elements, respectively. Tensegrity structures are subjected to various external loads such as self-weight, wind or snow loads which in turn could act in different directions and be of different magnitudes. Flexibility analysis is used to find the critical load combinations. The magnitude of pre-stress, in order to sustain large external loads, is obtained through flexibility figures, and flexibility ellipsoids are employed to ensure enough stiffness of the structure when disturbances are applied to a loaded structure. It has been seen that the most flexible direction is very much sensitive to the pre-stress magnitude and neither analytical methods nor flexibility ellipsoids are able to find the most flexible directions. The flexibility figures from a non-linear analysis are here utilized to find the weak directions. In the second part of the present work, a strategy is developed to compare tensegrity booms of triangular prism and Snelson types with a truss boom. It is found that tensegrity structures are less stiff than a truss boom when a transversal load is applied. An optimization approach is employed to find the placement of the actuators and their minimum length variations. The results show that the bending stiffness can be significantly improved, but still an active tensegrity boom is less stiff than a truss boom. Genetic algorithm shows high accuracy of searching non-structural space.QC 20110524
27
Lecci, Cristina. "Synthesis and modification of paracyclophanes". Thesis, Imperial College London, 2006. http://hdl.handle.net/10044/1/8906.
Testo completo
28
Murphy, Michael Stephen. "Structural modification of zeolite beta". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq23826.pdf.
Testo completo
29
Kutacova, Pavla. "Enzymatic modification of kenaf pulp". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ33973.pdf.
Testo completo
30
Resch, Barbara. "On Prosodic Modification of Speech". Licentiate thesis, Stockholm : Sound and Image Processing Laboratory, School of Electrical Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-621.
Testo completo
31
Josefsson, Peter. "Biochemical modification of wood components". Licentiate thesis, Stockholm : Fibre and Polymer Technology, KTH, the Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4171.
Testo completo
32
Tracy, Daniel P. "Vacuum ultraviolet modification of polymers /". Online version of thesis, 1989. http://hdl.handle.net/1850/10954.
Testo completo
33
Murphy, Michael Stephen. "Structural modification of zeolite beta". Thesis, University of New Brunswick, 1996. http://hdl.handle.net/1882/511.
Testo completo
34
Silverman, H. S. "Post-translational modification of mucins". Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365785.
Testo completo
35
Eyley, Samuel. "Surface modification of cellulose nanocrystals". Thesis, University of Nottingham, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.594860.
Testo completoAbstract (sommario):
Cellulose nanocrystal surface modification is an expanding area in cellulose research and this thesis aims to add knowledge to this growing field. Two esterification techniques new to cellulose nanocrystal research were applied successfully to the formation of esters of (methylthio)acetic add, two pyridinum substituted benzoic acids and rnethacrylic acid. The efficacy of the two methods was compared with each other and with those used in the literature. Two click chemistry reactions were also applied to cellulose nanocrystals. Azidation of chlorinated cellulose nanocrystals allowed application of copper(I) catalysed azidealkyne cydoaddition to the grafting of two irnidazoliurn salts and ferrocene to cellulose nanocrystals. Attachment of a disulfide to cellulose nanocrystais lead to a one-pot disulfide reduction and thiol Michael addition to graft cellulose nanocrystals with pentabromobenzyl acrylate. These different surface modification strategies were used to prepare a variety of surface active nanopartides for further application. Cationic cellulose nanocrystals were produced with higher surface charge density than previously reported in the literature. The cationic nature of the nanocrystals was probed using an anionic dye adsorption methodology. The variation in anion affinity for imidazolium grafted cellulose nanocrystals was determined using a batch mixing methodology with ion chromatography. Cellulose (methylthio)acetate nanocrystals were tested as a potential supported sulfur ylid in the rhodiurn(II) acetate and sulfide co-catalysed conversion of aldehydes to epoxides. This proved unsuccessful with by-products suggesting fa ilure to form supported ylids. Finally, cellulose nanocrystals were modified with a multidentate amine ligand using a diisocyanate and the resulting nanocrystals used to bind palladiurn(II) acetate. These nanocrystals were tested in Sonogashlra reactions for recydability of the palladium catalyst. Significant leaching of the palladium catalyst occurred without the use of a copper co-catalyst and the exact nature of the palladium species present on the surface of the nanocrystals remains unknown
36
Ying, Kong-chau William, e 邢江洲. "Lease modification and urban planning". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1993. http://hub.hku.hk/bib/B31258487.
Testo completo
37
Polwart, Neil. "Modification of diamond (100) surfaces". Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/298.
Testo completo
38
Lowe, V. J. "The modification of electrode surfaces". Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379931.
Testo completo
39
Tearle, Kathryn Mary. "Modification of aluminophosphate molecular sieves". Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295923.
Testo completo
40
Stanton, Tom. "'One', noun structure, and modification". Thesis, Queen Mary, University of London, 2017. http://qmro.qmul.ac.uk/xmlui/handle/123456789/31867.
Testo completoAbstract (sommario):
The present thesis aims to use novel observations as to the behaviour of anaphoric 'one' when under modification in order to explore more acutely the structure of the nominal phrase. There has been decades of disagreement as to the syntactic nature of anaphoric 'one'. This work highlights novel observations about anaphoric 'one' and offers structural analyses for them. Anaphoric 'one' behaves in a markedly distinct way when modified by a prenominal modifier versus when it is modified by a postnominal modifier. Specifically the indefinite article, numerals, and certain quantifiers are able to be introduced into the structure of the noun phrase only when anaphoric 'one' is modified prenominally. In such cases that is modified postnominally the introduction of such material is not possible. Rather than appealing to rich featural specifications on syntactic objects by way of explanation this thesis offers an account based upon the structure of the nominal. An obligatory movement operation in the nominal projection is proposed, the result of which produces a structural configuration which limits extraction from the moved constituent. It is the two of these factors working together that produces the pattern of behaviour to be captured. Finally I present phenomena that can be found in Spanish, Dutch, Turkish, and Slovenian which can be easily captured using the structural analysis offered in this work. The suggestion being that all of these languages exhibit not only the same movement operation in the nominal projection, but the same limit on what may be extracted from the moved constituent.
41
Clarke, Charlotte. "Cognitive bias modification & exercise". Thesis, University of Essex, 2018. http://repository.essex.ac.uk/23593/.
Testo completoAbstract (sommario):
This doctoral thesis investigates the complex relationship between mental well-being, cognitive bias and physical exercise. The introduction of this thesis begins with a perspective of the relationship between cognitive interpretation bias, physical exercise and mental well-being, specifically anxiety. The thesis begins with two studies which measure the effect of physical exercise on typical individual’s interpretation biases and measures of mental well-being. Study three begins to develop an exercise orientated Cognitive Interpretation Bias Modification (CBM-I) training programme that’s positively valanced and incorporating a dual method of CBM-I and exercise training against a rest control group. Study four uses the same methodological paradigm as study three whilst introducing a more robust control condition and recruiting a high anxiety sample. Study four uses a neutral CBM-I training program instead of a rest control condition, along with a positive CBM-I training program and physical exercise and measures the effect of these on interpretation bias and measures of mental well-being. Study five focuses on developing the neutral CBM-I training in direct contrast to the positive CBM-I training over the course of two sessions with a high anxiety sample of participants. Study Six and seven both recruited a high anxiety sample and were the only studies conducted completely online. Study Six consisted of six sessions of positive or neutral CBM-I training over six weeks. Whilst study seven consisted of three sessions of positive CBM-I, positive CBM-I & exercise, exercise or neutral CBM-I training over a three-week period. The results from these seven studies suggest support for positive CBM-I training which is exercise valanced and physical exercise for reducing self-report anxiety and depression. Implications for mental well-being in cases of sub-clinical anxiety are discussed, limitations addressed and future directions are considered.
42
Wilkie, Ormond L. "Modification models of conceptual combination". Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/13100.
Testo completo
43
Mir, Remi. "Evaluating style modification in text". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119569.
Testo completoAbstract (sommario):
Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 39-41).
In this thesis, we identify best practices for evaluating style modification, or style transfer, for text. Research of style transfer is bottlenecked by a lack of standard evaluation practices. We define three key aspects of interest (style transfer intensity, content preservation, and naturalness) and show how to obtain more reliable measures of them from human evaluation than in previous work. We also demonstrate stronger correlation between human judgment and a new set of automated metrics: the Wasserstein distance, word mover's distance on texts with style masked out, and adversarial classification for the respective aspects. Lastly, we illustrate aspect tradeoff curves for three state-of-the-art style transfer models to highlight the importance of evaluating style transfer models at specific points on the curves. This can enable direct comparison of the models, facilitating future research in style transfer.
by Remi Mir.
M. Eng.
44
Sumner, Robert Walker 1975. "Mesh modification using deformation gradients". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34025.
Testo completoAbstract (sommario):
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 117-131).
Computer-generated character animation, where human or anthropomorphic characters are animated to tell a story, holds tremendous potential to enrich education, human communication, perception, and entertainment. However, current animation procedures rely on a time consuming and difficult process that requires both artistic talent and technical expertise. Despite the tremendous amount of artistry, skill, and time dedicated to the animation process, there are few techniques to help with reuse. Although individual aspects of animation are well explored, there is little work that extends beyond the boundaries of any one area. As a consequence, the same procedure must be followed for each new character without the opportunity to generalize or reuse technical components. This dissertation describes techniques that ease the animation process by offering opportunities for reuse and a more intuitive animation formulation. A differential specification of arbitrary deformation provides a general representation for adapting deformation to different shapes, computing semantic correspondence between two shapes, and extrapolating natural deformation from a finite set of examples.
(cont.) Deformation transfer adds a general-purpose reuse mechanism to the animation pipeline by transferring any deformation of a source triangle mesh onto a different target mesh. The transfer system uses a correspondence algorithm to build a discrete many-to-many mapping between the source and target triangles that permits transfer between meshes of different topology. Results demonstrate retargeting both kinematic poses and non-rigid deformations, as well as transfer between characters of different topological and anatomical structure. Mesh-based inverse kinematics extends the idea of traditional skeleton-based inverse kinematics to meshes by allowing the user to pose a mesh via direct manipulation. The user indicates the dass of meaningful deformations by supplying examples that can be created automatically with deformation transfer, sculpted, scanned, or produced by any other means. This technique is distinguished from traditional animation methods since it avoids the expensive character setup stage. It is distinguished from existing mesh editing algorithms since the user retains the freedom to specify the class of meaningful deformations. Results demonstrate an intuitive interface for posing meshes that requires only a small amount of user effort.
by Robert Walker Sumner.
Ph.D.
45
Bell, Thomas James. "Cellulose modification using ionic liquids". Thesis, University of Leicester, 2006. http://hdl.handle.net/2381/29976.
Testo completoAbstract (sommario):
The aim of this project was to investigate ways of chemically modifying cellulose using ionic liquids. Cellulose is a readily available, naturally occurring, polymeric carbohydrate which is ideal for chemical modification owing to the high density of its functional groups. However, it is insoluble in all common organic solvents. Therefore, interest has recently turned to the use of a novel class of solvents, ionic liquids, which have been found to dissolve cellulose. Initially, studies were undertaken into the acylation of simple carbohydrates using a Lewis acidic choline based ionic liquid, (ZnCl 2)2ChCl. It was found that the yields obtained were comparable to those achieved when traditional solvents and catalysts have been used. It was also found that when only one equivalent of acylating agent was used, all of the carbohydrate hydroxyl groups were acylated. This was thought to be unique to this ionic liquid system. The acetylation of cellulose was also studied in (ZnCl2)2ChCl. Here, it was discovered that the ionic liquid alters the morphology of cellulose by wetting or dissolution thus enabling a range of acetylated products to be produced. Research into the cationic modification of cellulose in an ionic liquid based on chlorcholine chloride (ClChCl) and urea was also undertaken. In this case, it was found that the ionic liquid could act as both the reagent and solvent. It was shown using this system, that all the available (surface) hydroxyl groups on cellulose were modified and that the material produced was significantly more hydrophilic than unmodified cellulose. Finally, preliminary investigations were untaken into other potential surface modifications of cellulose in ionic liquids.
46
Skingle, Graham William. "Structural modification using experimental data". Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47664.
Testo completo
47
Moizo, Kévin. "La modification unilatérale du contrat". Rouen, 2016. http://www.theses.fr/2016ROUED012.
Testo completo
48
Wang, Ying. "SURFACE MODIFICATION OF SILICATE SUBSTRATES". University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1164641616.
Testo completo
49
Ranjan, Rajesh. "Surface Modification of Silica Nanoparticles". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1206558086.
Testo completo
50
Elliott, Kenny B. "Structural modification utilizing beam elements". Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53876.
Testo completoAbstract (sommario):
This study presents a concept that provides a structural dynamicist the ability to analyze the effects of making sophisticated (beam-type) structural changes to a structural system whose modal database is known. The modification technique combines the Dual Modal Space Modification Method (DMSM) and the Transfer-Matrix Method to institute general beam modifications. The DMSM method is employed to implement the beamtype modification, while the transfer-matrix method is used to formulate the modification element. The use of transfer-matrix methods provides the ability to model virtually any beam modification a designer might consider in terms of the two points being connected without the loss of any dynamic information between the points. The result is a modification scheme which is both flexible and universal.
Two numerical examples are considered. One example demonstrated the performance of the modification scheme in instituting a severe structural change. The second example demonstrated a change to a complex structure. In both cases, continuum beams were used as modification elements. The results of these two examples show that the modification scheme provides very promising results, providing an adequate modal database was used. Modal truncation was determined to be the primary source of error.Ph. D.