Dissertations / Theses on the topic 'Lignite Analysis'

In recent years, the risks created by the import of energy on the security of energy supply has encouraged countries to utilize local resources to a greater extend, and for many countries including Turkey coal is at the top of the local resources. However, it is not sufficient for countries to have an energy resource itself. Intens competition in today'
s globalized system requires the resources to be produced and utilized in the most economical manner. The supply of the resources to the market in a competitive way is possible by employing an efficient operation, which is then possible only through the business units producing these resources working efficiently. In this study, the efficiencies of the eight establishments of the Turkish Coal Enterprises (TKI) between 2006 to 2009 were analyzed by using Data Envelopment Analysis (DEA), Super Efficiency (SE) and Malmquist Total Factor Productivity Index (MI) methodologies. For the analyses, three output oriented models were constructed and used: Production Efficiency, Revenue Efficiency and Work Safety Efficiency models. In determining the input and output data used in the analyses, it was benefited from similar studies searched in the literature, knowledge of business and economics and a series of brainstorming of the expert panel consisting of ten high level representatives of the public and private lignite mining companies as well as that of the Turkish Ministry of Energy and Natural Resources. As a part of the analyses, first the production and revenue efficiencies of the establishments were analyzed by using Constant Return to Scale (CRS) and Variable Return to Scale (VRS) methods of DEA. Within this context, efficient and inefficient establishments for the years between 2006 to 2009, and benchmarks for inefficient establishments to move to becoming efficient were determined. Furthermore, for the production and revenue efficiency models, the target values and improvement potentials for the inefficient establishments in CRS analyses to becoming more efficient were calculated by using benchmarks tables and 2009 realized values of inputs and outputs. Second, the efficiency rankings of the efficient establishments among themselves between 2006 to 2009 were determined by using SE methodology. Third, to provide the dynamic analysis of the development of the establishments'
s efficiency levels in time, the changes of production, revenue and work safety efficiencies of the establishments between 2006 to 2009 were analyzed using the Malmquist Index (MI) methodology. MI analyses included the analysis of the efficiencies in four efficiency components (Technical, Technological, Pure and Scale efficiencies) as well as the calculation of the Total Factor Productivity Indexes of the establishments.

This diploma thesis is focused on optimization of sequential chemical fractionation method to humeomics in order to be useful for determination of organic matter content and distribution and also organic elements in soil. Subsequently, the optimized method is used to assess the efect of lignite application as soil support on these soil characteristics. For these purposes, there were three source matrices of organic matter (lignite, soil and annual soil extraction after lignite application) fractionated by sequential chemical analysis. In parallel, these samples were also fractionated by classic alkaline extraction to obtain the so-called extractable fraction of organic matter (NOM). Individual fractions from sequential chemical fractionation as well as NOM samples were characterized by methods of elemental analysis (determination of organic elements), thermogravimetry (contents of ash, organic matter and moisture) and FTIR spektrometry (structural analysis). The results obtained from a large range of data from all humeomics fractions and NOM fractions showed that the method of sequential chemical fractionation gives higher yields of organic matter compared to classic alkaline extraction. Another indisputable advantage is the fact that the obtained fractions divided according to solubility and strenght of binding to soil inorganics can be better characterized by physical-chemical methods, which provides more detailed information about soil organic matter. The results of the work also show that in order for lignite as a support substance to significantly affect soil properties, a longer time, multiple sampling and repetition of individual fractionations would be needed.

Humic acids were extracted from South Moravian lignit. That humic sample was oxidized by either H2O2 or HNO3. In next step, oxidized humic acids were polymerized by formaldehyde in order to obtain cross-linked structures with improved water retention capacity. Affinity to water and water retention capacity of obtained products were studied by thermal analysis (DSC – differential scanning calorimetry and TGA – thermogravimetric analysis). In order to study above-mentioned parameters two different methods were used. First approach represented sorption of water to humic acids from three controlled humidities, for description of those processes TGA measurement was used. Second study was based on the DSC monitoring of water excess sorption. Results obtained from TGA measurements showed an increasing sorption ability with increasing relative humidity of the environment. DSC measurerents in hermetically sealed containers resulted in an increasing content of water bound by humic acids structures. All the modified samples of humic acids (oxidized as well as oxidized and modified by formaldehyde) gave higher retention capacity in comparion with the parental humic sample.

Huminové kyseliny představují hlavní součást půdní organické hmoty. Jedná se o všudypřítomné sloučeniny s komplexní chemickou a fyzikálně-chemickou strukturou. Předkládaná práce shrnuje několik způsobů modifikací huminových kyselin provedených za účelem úpravy jejich vlastností. V první části byl studován vliv vzdušné oxidace lignitu na velikost výtěžku a fyzikálně-chemický charakter produkovaných regenerovaných huminových kyselin. Druhý krok představoval snahu stabilizovat strukturu lignitických huminových kyselin a zlepšit zádrž vody. Bylo provedeno síťování pomocí formaldehydu a karbodiimidů, které předpokládá vznik nových kovalentních vazeb v různých částech struktury huminových kyselin. Produkce zesíťované struktury byla motivována snahou vytvořit systémy podobné hydrogelům, založené na huminových látkách s možností úpravy jejich reaktivity a retence vody. Chemické složení a fyzikálně-chemické vlastnosti připravených vzorků byly studovány různými metodami, mezi nejdůležitější patří DSC a NMR relaxometrie. Chemické složení bylo studováno pomocí FTIR a elementární analýzy za účelem posoudit a porovnat změny s původním neupraveným vzorkem. Stability vzorků byly stanoveny pomocí termogravimetrie. Nejdůležitějším sledovaným parametrem této práce byla změna hydratačních charakteristik. K jejich studiu jsme vyvinuli a aplikovali několik nových termoanalytických a NMR relaxometrických přístupů. Ve snaze napodobit přírodní procesy byla studována sorpce vody huminovými kyselinami z prostředí s kontrolovanou vzdušnou vlhkostí. Byly pozorovány kvalitativní a kvantitativní hlediska sorpce vody. Zesíťování za použití formaldehydu způsobilo snížení sorpční kapacity vlhkosti. Tato změna je připisována separaci funkčních skupin a menší strukturní kompaktnosti. Zesíťované huminové kyseliny dále vykazovaly rychlejší příjem vody a přibližně třikrát větší kapacitu zádrže vody než původní huminové kyseliny. V případě použití karbodiimidu (ve vodě rozpustného N-Ethyl-N-(3-dimethylaminopropyl)karbodiimidu (EDC)) obsahovaly výsledné produkty 14–40 % původních karboxylových skupin. I přesto tyto látky překonaly schopnost sorpce vlhkosti původního nemodifikovaného vzorku o 10–14 % po kondiciaci v prostřední se 100% relativní vzdušnou vlhkostí. Navzdory rigidnější struktuře vykazovaly EDC deriváty rychlejší bobtnání a dosáhly téměř stejné kapacity zádrže vody po 18 dnech jako původní vzorek. Vzorky modifikované karbodiimidy vykazovaly známky degradace již po 3–9 dnech což částečně snižuje jejich využitelnost. Získané výsledky naznačují, že kapacita zádrže vody, kinetika bobtnání a schopnost sorpce vlhkosti huminových kyselin nejsou výhradně určeny koncentrací karboxylových skupin, nebo dalších polárních fragmentů, ale také jejich vzájemným rozmístěním a distribucí velikosti pórů na povrchu a také uvnitř struktury. Získané poznatky této studie mohou sloužit například k produkci půdních kondicionérů založených na huminových kyselinách, tj. remediačních preparátů s požadovanými, ale především nastavitelnými schopnostmi poutat a následně uvolňovat vodu do okolního prostředí. V neposlední řadě přispějí uvedené závěry ke zkvalitnění základního porozumění procesu hydratace v modifikovaných a původní vzorcích, což je přínosné ve vztahu k objasnění hydratace komplexních přírodních systémů a to zejména přírodní organické hmoty.

Die Dissertationsschrift führt im Gegensatz zu bisherigen Ansätzen im Zusammenhang mit der Energiewende einen Perspektivwechsel hin zur gesellschaftlichen Berücksichtigung herbei. Bisherige Szenariostudien richteten ihren Fokus auf die technische Machbarkeit sowie einzelne Kosten- und Umweltaspekte, wie in der Voranalyse gezeigt wird. Die Gesellschaft spielt in diesem Fall eine sekundäre Rolle. Statt einer Berücksichtigung im vorab geschalteten Entscheidungsprozess werden so häufig erst im Anschluss Zeit und Aufwand in die nachgelagerte Überzeugung der Bevölkerung investiert. Der in der Arbeit verfolgte Ansatz setzt konsequent darauf, gesellschaftliche Präferenzen und Barrieren vorab in die Entscheidungsfindung einzubeziehen, damit Entscheidungen selbst nachhaltig Bestand haben. Dazu werden repräsentative Telefonbefragungen genutzt, mit denen einerseits die Präferenzen der Bevölkerung, andererseits die Grenzen der Akzeptanz in Form der Zahlungsbereitschaft ermittelt werden. Erst im Anschluss daran werden Szenariorechnungen durchgeführt, um energiepolitische Handlungsoptionen auch quantitativ bewerten zu können. Bei der anschließenden Gegenüberstellung von gesellschaftlichen Barrieren und Modellergebnissen werden jedoch auch die Grenzen dieses Ansatzes vor Augen geführt: So kann eine aus Bevölkerungsperspektive erwünschte Handlungsoption (hier der Braunkohleausstieg) auch an politischen und rechtlichen Schranken scheitern.

Thesis (PhD) - Faculty of Life and Social Sciences, Swinburne University of Technology, 2008.
Presented for full assessment for the degree of Doctor of Philosophy, Faculty of Life and Social Sciences, Swinburne University of Technology - 2008. Typescript. Bibliography: p. 222-246.

Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010.
Committee Chair: Ragauskas, Arthur; Committee Member: Bunz, Uwe; Committee Member: Deng, Yulin; Committee Member: Singh, Preet; Committee Member: Soper, Jake. Part of the SMARTech Electronic Thesis and Dissertation Collection.

The first part of the thesis presents a study based on the forest biorefinery concept, which involves converting a pulp mill into a multi-purpose biofuels, biomaterials, and biopower production facility in which these products are produced in an environmentally compatible and sustainable manner. A key challenge in this process is the recovery of lignin from process streams such that it can be utilized in a variety of innovative green chemistry processes The first study examines the fundamental chemical structure of LignoBoost derived lignin recovered from Kraft pulping streams using an acid precipitation/washing methodology. Functional group analysis and molecular weight profiles were determined by nuclear magnetic resonance (NMR) and size exclusion chromatography. These findings gave valuable insight into the physical properties and the determining chemical properties of this currently underutilized, renewable bioresource. The second study is based on the future second generation bioethanol production process, where ethanol produced from lignocellulosic materials will bring about the co-production of significant amounts of under-utilized lignin. The study examines the potential of conventional heterogeneous and novel homogeneous catalysts for the selective cleavage of the aryl-O-aryl and aryl-O-aliphatic linkages of ethanol organosolv lignin to convert it from a low grade fuel to potential fuel precursors or other value added chemicals. The experimental data demonstrated that aryl-O-aryl and aryl-O-aliphatic linkages could be cleaved and the hydrogenated lignin had a decrease in oxygen functionality and the formation of products with lower oxygen content. The second part of this thesis reports the development and optimization of a novel qualitative method for the determination of the various types of hydroxyl groups present in biodiesel production streams. In the first study, the use of 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane as a phosphitylation reagent for quantitative ³¹P-NMR analysis of the hydroxyl groups in biodiesel process samples has been developed. Subsequently a characteristic chemical shifts library is developed with model compounds to provide quantitative data on the concentration of biodiesel precursors, intermediates and final product. The last part of this thesis depicts the results of an industrial trial based on the novel biodiesel analytical method developed earlier.

Research concerning lignin has increased during the last years due to its renewability and ready availability in black liquor at pulp mills. Today, the kraft lignin found in black liquor is used as a fuel to gain energy in the recovery boiler at the mill. However, a new isolation concept, LignoBoost®, has enabled isolation of part of the lignin while allowing the use of black liquor as a fuel. This isolated lignin can be utilised as a fuel in, for example, thermal power stations or further upgraded to more value-added products. In this context, the most interesting value-added product is carbon fibre. The demand for carbon fibre has increased, but the biggest obstacle for a more extended use is the high production cost. About half of the production cost is related to the raw material.

In this work, the possibility of using kraft lignin as a precursor for carbon fibre production has been investigated through fundamental studies. Kraft lignins originating from birch, Eucalyptus globulus, softwoods and softwoods from liner production have been studied. By separating the lignin while still in solution in the black liquor, unwanted large particles such as carbohydrates can easily be removed. After isolation according to the LignoBoost process and purification with the use of an ion-exchanger, the lignins have been both chemically and thermally characterised. Identification of the released compounds at different temperatures has been performed because only 40% of carbon relative to original lignin remains, down from theoretical 60% after thermal treatment up to 1000°C. The main released compounds were phenols, as revealed by pyrolysis-GC/MS. Additionally, a pre-oxidation was done in order to try to stabilise the lignins. It was shown that an oxidation prior to the thermal treatment increases the yield by more than 10% and that the main release of compounds takes place between 400°C and 600°C. Fractionated lignin is better qualified as raw material for carbon fibre production because it is purer and its softening temperature can be detected. Fractionated kraft lignins from all investigated wood sources have high possibilities to act as precursors for the manufacture of carbon fibre.

The Queensland University of Technology (QUT) allows the presentation of a thesis for the Degree of Doctor of Philosophy in the format of published or submitted papers, where such papers have been published, accepted or submitted during the period of candidature. This thesis is composed of Seven published/submitted papers and one poster presentation, of which five have been published and the other two are under review. This project is financially supported by the QUTPRA Grant. The twenty-first century started with the resurrection of lignocellulosic biomass as a potential substitute for petrochemicals. Petrochemicals, which enjoyed the sustainable economic growth during the past century, have begun to reach or have reached their peak. The world energy situation is complicated by political uncertainty and by the environmental impact associated with petrochemical import and usage. In particular, greenhouse gasses and toxic emissions produced by petrochemicals have been implicated as a significant cause of climate changes. Lignocellulosic biomass (e.g. sugarcane biomass and bagasse), which potentially enjoys a more abundant, widely distributed, and cost-effective resource base, can play an indispensible role in the paradigm transition from fossil-based to carbohydrate-based economy. Poly(3-hydroxybutyrate), PHB has attracted much commercial interest as a plastic and biodegradable material because some its physical properties are similar to those of polypropylene (PP), even though the two polymers have quite different chemical structures. PHB exhibits a high degree of crystallinity, has a high melting point of approximately 180°C, and most importantly, unlike PP, PHB is rapidly biodegradable. Two major factors which currently inhibit the widespread use of PHB are its high cost and poor mechanical properties. The production costs of PHB are significantly higher than for plastics produced from petrochemical resources (e.g. PP costs $US1 kg-1, whereas PHB costs $US8 kg-1), and its stiff and brittle nature makes processing difficult and impedes its ability to handle high impact. Lignin, together with cellulose and hemicellulose, are the three main components of every lignocellulosic biomass. It is a natural polymer occurring in the plant cell wall. Lignin, after cellulose, is the most abundant polymer in nature. It is extracted mainly as a by-product in the pulp and paper industry. Although, traditionally lignin is burnt in industry for energy, it has a lot of value-add properties. Lignin, which to date has not been exploited, is an amorphous polymer with hydrophobic behaviour. These make it a good candidate for blending with PHB and technically, blending can be a viable solution for price and reduction and enhance production properties. Theoretically, lignin and PHB affect the physiochemical properties of each other when they become miscible in a composite. A comprehensive study on structural, thermal, rheological and environmental properties of lignin/PHB blends together with neat lignin and PHB is the targeted scope of this thesis. An introduction to this research, including a description of the research problem, a literature review and an account of the research progress linking the research papers is presented in Chapter 1. In this research, lignin was obtained from bagasse through extraction with sodium hydroxide. A novel two-step pH precipitation procedure was used to recover soda lignin with the purity of 96.3 wt% from the black liquor (i.e. the spent sodium hydroxide solution). The precipitation process is presented in Chapter 2. A sequential solvent extraction process was used to fractionate the soda lignin into three fractions. These fractions, together with the soda lignin, were characterised to determine elemental composition, purity, carbohydrate content, molecular weight, and functional group content. The thermal properties of the lignins were also determined. The results are presented and discussed in Chapter 2. On the basis of the type and quantity of functional groups, attempts were made to identify potential applications for each of the individual lignins. As an addendum to the general section on the development of composite materials of lignin, which includes Chapters 1 and 2, studies on the kinetics of bagasse thermal degradation are presented in Appendix 1. The work showed that distinct stages of mass losses depend on residual sucrose. As the development of value-added products from lignin will improve the economics of cellulosic ethanol, a review on lignin applications, which included lignin/PHB composites, is presented in Appendix 2. Chapters 3, 4 and 5 are dedicated to investigations of the properties of soda lignin/PHB composites. Chapter 3 reports on the thermal stability and miscibility of the blends. Although the addition of soda lignin shifts the onset of PHB decomposition to lower temperatures, the lignin/PHB blends are thermally more stable over a wider temperature range. The results from the thermal study also indicated that blends containing up to 40 wt% soda lignin were miscible. The Tg data for these blends fitted nicely to the Gordon-Taylor and Kwei models. Fourier transform infrared spectroscopy (FT-IR) evaluation showed that the miscibility of the blends was because of specific hydrogen bonding (and similar interactions) between reactive phenolic hydroxyl groups of lignin and the carbonyl group of PHB. The thermophysical and rheological properties of soda lignin/PHB blends are presented in Chapter 4. In this chapter, the kinetics of thermal degradation of the blends is studied using thermogravimetric analysis (TGA). This preliminary investigation is limited to the processing temperature of blend manufacturing. Of significance in the study, is the drop in the apparent energy of activation, Ea from 112 kJmol-1 for pure PHB to half that value for blends. This means that the addition of lignin to PHB reduces the thermal stability of PHB, and that the comparative reduced weight loss observed in the TGA data is associated with the slower rate of lignin degradation in the composite. The Tg of PHB, as well as its melting temperature, melting enthalpy, crystallinity and melting point decrease with increase in lignin content. Results from the rheological investigation showed that at low lignin content (.30 wt%), lignin acts as a plasticiser for PHB, while at high lignin content it acts as a filler. Chapter 5 is dedicated to the environmental study of soda lignin/PHB blends. The biodegradability of lignin/PHB blends is compared to that of PHB using the standard soil burial test. To obtain acceptable biodegradation data, samples were buried for 12 months under controlled conditions. Gravimetric analysis, TGA, optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), FT-IR, and X-ray photoelectron spectroscopy (XPS) were used in the study. The results clearly demonstrated that lignin retards the biodegradation of PHB, and that the miscible blends were more resistant to degradation compared to the immiscible blends. To obtain an understanding between the structure of lignin and the properties of the blends, a methanol-soluble lignin, which contains 3× less phenolic hydroxyl group that its parent soda lignin used in preparing blends for the work reported in Chapters 3 and 4, was blended with PHB and the properties of the blends investigated. The results are reported in Chapter 6. At up to 40 wt% methanolsoluble lignin, the experimental data fitted the Gordon-Taylor and Kwei models, similar to the results obtained soda lignin-based blends. However, the values obtained for the interactive parameters for the methanol-soluble lignin blends were slightly lower than the blends obtained with soda lignin indicating weaker association between methanol-soluble lignin and PHB. FT-IR data confirmed that hydrogen bonding is the main interactive force between the reactive functional groups of lignin and the carbonyl group of PHB. In summary, the structural differences existing between the two lignins did not manifest itself in the properties of their blends.

Effective analytical techniques need to be developed to characterize the products of lignin degradation experiments to be able to generate renewable products from lignin. Mass spectrometry is an valuable analytical approach for lignin characterizaion, but it is hindered by lignin’s poor ionization efficiency, especially in the positive ion mode. In this work, we attempt to improve lignin’s ionization by utilizing electrospray and laser desorption mass spectrometry coupled with the addition of cations and chemical derivatives. We confronted the ionization problem from both a top-down and bottom-up analytical approach by analyzing synthesized monomers, dimers, and polymers along with natural lignin extracts from switchgrass. We also utilized tandem mass spectrometry to sequence lignin dimers and determine their bonding motifs from their fragmentation patterns. We believe that resolving the ionization issues with lignin will open the door for easier and more efficient lignin break-down techniques and ultimately more accessible renewable products from lignin.

Thesis (MSc)- Stellenbosch University, 2001.
ENGLISH ABSTRACT: Wood is composed of three main components: cellulose, hemicellulose and lignin. Cellulose is the main structural polymer, whereas the function of lignin in plants is to impart rigidity to the cells, to waterproof the vascular system, and to protect the plant against pathogens. A group of microorganisms, called white-rot fungi, are able to selectively degrade the lignin and hemicellulose from wood leaving the cellulose virtually untouched. The most widely studied fungus of this group is the basidiomycete Phanerochaete chrysosporium, which has become a model organism in studies of lignin degradation. Lignin is a large, heterogenous and water insoluble polymer and therefore the enzymes needed to degrade it have to be extracellular and non-specific. There are a number of enzymes that are involved in the degradation of lignin, including lignin peroxidases, manganese dependent peroxidases and laccases. Laecases are blue copper oxidases that require molecular oxygen to function, whereas lignin peroxidases and manganese peroxidases are heme proteins that require hydrogen peroxide. Phanerochaete chrysosporium has all three of these enzymes, as well as a system for producing the hydrogen peroxide that is necessary for peroxidases to function. For both scientific and industrial purposes, it is important to obtain linkage maps of the positions of genes in the genome of an organism. Most fungi, including P. chrysosporium, lack easily identifiable phenotypical markers that can be used to map the position of genes relative to each other on the genome. Previous methods of mapping genes in P. chrysosporium involved auxotrophic mutants, radioactivity, or the use of hazardous chemicals. Here we describe an automated DNA-sequencing based mapping technique that eliminates many of the problems associated with previous techniques. Portions of the genes to be mapped were amplified from homokaryotic single basidiospore cultures using gene specific primers using the polymerase chain reaction (PCR) technique. The PCR products were sequenced to determine the segregation of alleles. Two previously mapped lignin peroxidases, lipA and lipC, were used to develop this method, and the results obtained corresponded to the known genetic linkage. A newly characterised 13-glucosidase encoding gene from P. chrysosporium was also mapped. Linkage was found between the 13-glucosidase gene and a histone (Hl) encoding gene. In P. chrysosporium the lignin peroxidase isozymes are encoded by a family of at least ten genes. Previous studies with P. chrysosporium BKM-F-1767 in defined media, wood and soil have shown differential expression of the lignin peroxidase isozymes. In this investigation the levels of expression of lignin peroxidases in P. chrysosporium ME446 cultures grown in nitrogen or carbon limited defined liquid media, as well as on aspen wood chips were determined by competitive reverse transcriptase polymerase chain reaction (RT-peR). These results were compared to those previously obtained from P. chrysosporium BKM-F-1767 to evaluate strain specific variation in the expression of lignin peroxidases. The results indicate that, although there were many similarities in the patterns of lignin peroxidase expression, there were also enough differences to conclude that there were strain specific variations in the temporal expression of the lignin peroxidases. To conclude, a fast and cost effective method for mapping genes in P. chrysosporium was developed. Also, we showed that strain specific variation in temporal expression of lignin peroxidases occurs.
AFRIKAANSE OPSOMMING: Hout bestaan uit drie hoof komponente nl. sellulose, hemisellulose en lignien. Sellulose is die hoof strukturele polimeer, terwyl die funksie van lignin in plante is om die selle te versterk, die vaskulêre sisteem waterdig te hou, en die plant teen patogene te beskerm. 'n Groep mikroërganisms, bekend as witvrotswamme, kan lignien en hemisellulose selektief uit die hout verwyder, terwyl die sellulosevesels oorbly. Vanuit hierdie groep swamme is die meeste navorsing op die basidiomiseet Phanerochaete chrysosporium gedoen Lignien is 'n groot, heterogene polimeer en is onoplosbaar in water. Die ensieme wat benodig word om lignien afte breek is daarom nie-spesifiek en kom ekstrasellulêr voor. 'n Aantal ensieme is by die afbraak van lignien betrokke, insluitend lignienperoksidase, mangaanperoksidase en lakkase. Lakkase is 'n blou koperoksidase wat suurstof benodig vir aktiwiteit. Lignienperoksidase en mangaanperoxidase is heemproteïene en benodig waterstofperoksied. Phanerochaete chrysosporium het al drie van hiedie ensieme, sowel as 'n sisteem wat waterstofperoksied produseer. Vir beide wetenskaplike en nywerheidsdoeleindes is koppelingskaarte wat die posisie van gene in die genoom van 'n organisme aandui noodsaaklik. Die meeste swamme, P. chrysosporium ingesluit, het geen fenotipiese merkers wat maklik van mekaar onderskei kan word nie, en dit is dus moeilik om 'n kaart van die ligging van gene op die genoom te bepaal. Vorige metodes om gene in P. chrysosporium te karteer het auksotrofiese mutante, radioaktiwiteit of gevaarlike chemikalieë gebruik. Ons beskryf 'n metode wat van automatiese DNA-volgordebepaling gebruik maak en wat baie van die tekortkominge van die ou metodes oorkom. Dele van die gene is met geen-spesifieke PKR-amplifikasie uit kulture van homokariotiese enkel basidiospore verkry en die DNA-volgorde is bepaal om die segregasie van die allele te ondersoek. Twee gene waarvoor 'n koppelingskaart alreeds uitgewerk is, fipA en lipt), was gebruik om hierdie metode te ontwikkel. Die resultate stem ooreen met die bekende genetiese koppeling tussen hierdie gene. 'n Geen wat onlangs in P. chrysosporium ontdek is, nl. I3-glucosidase, is ook met hierdie metode gekarteer. Koppeling is met 'n histoon (Hl) geen gevind. Die lignienperoksidase isoensieme in P. chrysosporium word deur 'n familie van ten minste tien gene gekodeer. Vorige navorsing met P. chrysosporium BKM-F-1767 in gedefineerde media, hout en grond het getoon dat 'n variasie in die uitdrukking van lignienperoxidase isoensieme voorkom. In hierdie ondersoek is 'n kultuur van P. chrysosporium ME446 in stikstof- of koolstof-beperkende vloeibare media opgegroei, as ook op aspen houtblokkies. Die vlak van uitdrukking van die lignienperoksidases is deur middel van die omgekeerde transkripsie polimerasekettingreaksie (RT-PKR) bepaal. Die resultate vir P. chrysosporium ME446 is vergelyk met vorige resultate van P. chrysosporium BKM-F-1767 om te bepaal of stamspesifieke variasies in die uitdrukking van lignienperoksidases voorkom. Daar is 'n aanduiding dat, alhoewel soortgelyke patrone in die vlakke van lignienperoksidase uitdrukking voorkom, daar ook noemenswaardige verskille is. Hieruit kan afgelui word dat stamverwante variasie van lignienperokisdase uitdrukking voorkom. Ten slotte, ons het 'n vinnige, goedkoop metode om die gene in P. chrysosporium te karteer ontwikkel. Ons het ook bewys dat stam-spesifieke variasie in die uitdrukking van die lignienperoxidase gene voorkom.

Thesis (MScAgric (Viticulture and Oenology. Wine Biotechnology))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Necrotrophic fungi infect many economically important crop plants. This results in great losses in the agricultural sector world-wide. Understanding the nature by which plants respond to pathogens is imperative for genetically enhancing disease resistance in plants. Research tools have significantly contributed to our understanding of how the plant responds to pathogen attack, identifying an array of defence mechanisms used by plants upon attack. Many fungal pathogens secrete endopolygalacturonases (endoPGs) when infecting plants. These hydrolytic enzymes are inhibited by polygalacturonase-inhibiting proteins (PGIPs) associated with plant cell walls. PGIPs are well characterised and their current known functions are all linked to endoPG inhibition and the subsequent upregulation of plant defence pathways. Work on grapevine PGIPs have shown that apart from being efficient antifungal proteins, leading to protection of the plant against Botrytis cinerea when overexpressed, PGIPs might also have additional functions linked to cell wall strengthening. This working hypothesis formed the motivation of this study where a cinnamyl alcohol dehydrogenase (CAD) (1.1.1.195) gene was targeted for functional analysis in tobacco (Nicotiana tabacum). Some previous work and genetic resources obtained is relevant to this study, specifically previously characterized transgenic tobacco lines overexpressing the Vitis vinifera pgip1 (Vvpgip1) gene. These lines have confirmed PGIP-specific resistance phenotypes against B. cinerea, as well as increased levels of CAD transcripts in healthy plants. Moreover, preliminary evaluations indicated increased lignin levels as well as differential expression of several other cell wall genes in these overexpressing lines (in the absence of infections). In this study we generated a transgenic tobacco population, overexpressing the native CAD14 gene, via Agrobacterium transformations. The transgene was overexpressed with the Cauliflower Mosaic Virus promoter (CaMV 35Sp). The CAD transgenic population was analyzed for transgene integration and expression and showed active transcription, even from leaves that normally don’t express CAD to high levels. These lines, together with the untransformed control, and a representative transgenic VvPGIP1 tobacco line previously characterized with elevated expression of CAD were used for all further analyses, specifically CAD activity assays of stems and leaves, as well as whole plant infections with B. cinerea. CAD enzyme activity assays were performed on healthy uninfected plant lines, without inducing native CAD expression or resistance phenotypes (i.e. without Botrytis infection). CAD activity was detected in leaves and stems, but a statistically sound separation between the CAD population and the untransformed control was only observed in the stems. The CAD assays also confirmed previous results that indicated that CAD transcription was upregulated in the PGIP line in the absence of infection. Overall, in all plant lines the stems exhibited 10-fold higher levels of CAD activity than the leaves, but the transgenic VvPGIP1 line showed a further 2-3-fold increase in CAD activity in the stems, when compared to the untransformed control and the majority of the CAD overexpressing lines. Disease assessment by whole plant infections with B. cinerea of the CAD transgenic plants revealed reduced disease susceptibility towards this pathogen. A reduction in disease susceptibility of 20 – 40% (based on lesion sizes) was observed for a homologous group of transgenic lines that was statistically clearly separated from the untransformed control plants following infection with Botrytis over an 11-day-period. The VvPGIP1 transgenic line displayed the strongest resistance phenotype, with reduction in susceptibility of 47%. The reduction in plant tissue maceration and lesion expansion was most pronounced in the VvPGIP1 line compared to the CAD transgenic plants, while the CAD transgenic plants showed more reduction than the untransformed control. In combination, the data confirms that CAD upregulation could lead to resistance phenotypes. Relating this data back to the previously observed upregulation of CAD in the VvPGIP1-overexpressing lines, the findings from this study corroborates that increased CAD activity contributes to the observed resistance phenotypes, possibility by strengthening the cell wall. In conclusion, this study yielded a characterized transgenic population overexpressing the CAD14 gene; this overexpression contributed to increased RNA transcription compared to the untransformed control plant, increased CAD activity (most notably in the stems) and a disease resistance phenotype against Botrytis. These findings corroborates the current working hypothesis in our group that PGIPs might have a role in preparing the plant cell for attack by contributing to specific cell wall changes. The exact mechanisms are still currently unknown and under investigation. The transgenic lines generated in this study will be invaluable in the subsequent analyses where these various phenotypes will be subjected to profiling and accurate cell wall analyses.
AFRIKAANSE OPSOMMING: Nekrotrofiese swamme infekteer en beskadig verskeie ekonomies belangrike gewasse. Dit lei wêreldwyd tot groot verliese vir die landbousektor. Dit is noodsaaklik om te verstaan hoe plante reageer teenoor patogene, sodat die siekteweerstand van plante verbeter kan word. Navorsingshulpbronne het beduidend bygedra tot die kennis van plantreaksies tydens patogeniese aanvalle, en het sodoende ‘n reeks van weerstandmeganismes, wat die plant inspan tydens ‘n aanval, geïdentifiseer. Verskeie patogeniese swamme skei endopoligalakturonases (endoPGs) af tydens plantinfeksie. Hierdie hidrolitiese ensieme word geïnhibeer deur poligalakturonase-inhiberende proteïene (PGIPs) wat met die plantselwand geassosieerd is. PGIPs is goed gekarakteriseerd en al hulle huidiglik bekende funksies is gekoppel aan endoPG inhibisie en die daaropvolgende opregulering van plant weerstandspaaie. Navorsing op wingerd PGIPs het gewys dat, afgesien van die feit dat PGIPs goeie antifungiese proteïene is wat lei tot beskerming van die plant teen Botrytis cinerea wanneer dit ooruitgedruk word, PGIPs ook moontlik addisionele funksies verrig wat verwant is aan selwandversterking. Hierdie werkshipotese vorm die motivering vir hierdie studie waarin ‘n sinnamiel alkohol dehidrogenase (SAD) (1.1.1.195) geen geteiken is vir funksionele analise in tabak (Nicotiana tabacum). Vorige navorsing en genetiese hulpbronne daardeur verkry is belangrik vir hierdie studie, spesifiek die gekarakteriseerde transgeniese tabaklyne wat die Vitis vinifera pgip1 (Vvpgip1) geen ooruitdruk. Hierdie lyne besit bevestigde PGIP-spesifieke weerstandsfenotipes teen B. cinerea, sowel as hoër vlakke van SAD transkripte in gesonde plante. Voorlopige analises het ook aangedui dat hierdie ooruitdrukkende lyne hoër lignien vlakke het, asook differensiële uitdrukking van verskeie ander selwandgene (in die afwesigheid van infeksie). In hierdie studie is ‘n transgeniese tabakpopulasie gegenereer wat die natuurlike tabak SAD14 geen ooruitdruk, deur middel van Agrobacterium transformasie. Die transgeen is ooruitgedruk deur die Blomkool Mosaïek Virus promoter (CaMV 35Sp). Die SAD transgeniese populasie is geanaliseer vir transgeen integrasie en uitdrukking en het aktiewe transkriptering getoon, selfs in blare waar daar normaalweg nie hoë vlakke van SAD uitgedruk word nie. Hierdie lyne, die ongetransformeerde wilde-tipe kontrole sowel as ’n verteenwoordigende transgeniese VvPGIP1 tabaklyn wat vooraf gekarakteriseerd was met hoë SAD uitdrukking, is gebruik vir alle verdere analises, spesifiek SAD aktiwiteitstoetse in stingels en blare, asook heelplantinfeksies met B. cinerea. Aktiwiteitsanalises van die SAD ensiem is gedoen op gesonde ongeinfekteerde plantlyne, sonder om natuurlike tabak SAD uitdrukking of weerstandsfenotipes te induseer (dus sonder Botrytis infeksie). SAD aktiwiteit is waargeneem in beide die blare en stingels, maar ‘n statisties betekenisvolle skeiding is slegs gevind tussen die SAD populasie en die ongetransformeerde kontrole in die stingels. Die SAD toetse het ook vorige resultate bevestig wat aangedui het dat SAD transkripsie opgereguleer word in die PGIP lyn in die afwesigheid van infeksie. Die stingels het oor die algemeen ‘n 10-voudige vermeerdering in SAD aktiwiteitsvlakke getoon in vergelyking met die blare, maar die transgeniese VvPGIP1 lyn het ‘n verdere 2-3-voudige verhoging in SAD aktiwiteit gehad in die stingels ,in vergelyking met die ongetransformeerde kontrole en die meerderheid van die SADooruitdrukkende lyne. Siekteweerstand ondersoeke deur middel van heelplantinfeksies met B. cinerea van die SAD transgeniese plante, het verminderde vatbaarheid aangedui ten opsigte van hierdie patogeen. ‘n Afname in siekte-vatbaarheid van 20 – 40% (gebaseer op wondgroottes) is waargeneem vir ‘n homoloë groep transgeniese lyne wat statisties betekenisvol geskei kon word van die ongetransformeerde kontrole plante na infeksie met Botrytis in ‘n infeksietoets wat 11 dae geduur het. Die VvPGIP1 transgeniese lyn het die mees weerstandbiedende fenotipe gehad, met ‘n afname in siekte-vatbaarheid van 47%. Die afname in plantweefselafbreking en wondgrootte was die duidelikste in die VvPGIP1 lyn in vergelyking met die SAD transgeniese plante, terwyl die SAD transgeniese plante ‘n groter afname aangedui het as die ongetransformeerde kontrole. In kombinasie het die data bevestig dat SAD opregulasie kan lei tot weerstandbiedende fenotipes. Hierdie data, in vergelyking met die vorige bevinding van opregulasie van SAD in die VvPGIP1-ooruitdrukkende lyne, bevestig dat hoër SAD aktiwiteit bydra tot die waargenome weerstandbiedende fenotipes, moontlik deur versterking van die plantselwand. Ter afsluiting, hierdie studie het ‘n gekarakteriseerde transgeniese populasie wat die SAD14 geen ooruitdruk gelewer; hierdie ooruitdrukking het bygedra tot hoër RNA transkripsie in vergelyking met die kontrole, verhoogde SAD aktiwiteit (veral in die stingels) en siekteweerstandbiedende fenotipes teenoor Botrytis. Hierdie bevindinge ondersteun die huidige werkshipotese in ons groep dat PGIPs moontlik ‘n rol speel in die voorbereiding van die plantsel teen infeksie deur spesifieke selwandveranderinge te veroorsaak. Die spesifieke meganismes is steeds onbekend en word verder ondersoek. Die transgeniese lyne wat tydens hierdie studie gegenereer is, sal baie belangrik wees in opvolgende analises waar hierdie verskillende fenotipes gebruik kan word om die profiel van selwandkomponente, maar ook die akkurate selwandsamestelling te bestudeer.

La production de vanille (Vanilla planifolia, Orchidaceae) est limitée par la pourriture des racines et des tiges (PRT) provoquée par des champignons telluriques du genre Fusarium contre lesquels la lutte chimique ou prophylactique est inefficace. Ce travail décrit finement l'interaction entre les vanilliers et les Fusarium dans le but de développer la lutte génétique. L'analyse moléculaire (gène EF1α et IGS) et la détermination du pouvoir pathogène de 365 souches de Fusarium isolées de vanilliers à La Réunion et à Madagascar ont démontré que les souches pathogènes sur vanillier appartiennent presque toutes au complexe d'espèce F. oxysporum et ont une origine polyphylétique. Les observations en microscopie à champ large et multi-photons démontrent que la colonisation des racines débute au niveau des poils absorbants puis gagne le cortex, mais que le système vasculaire est épargné. Cela conduit à renommer l'agent pathogène en F. oxysporum f. sp. radicis-vanillae (Forv). Dans les interactions incompatibles (souche pathogène et vanillier résistant), l'épaississement et la lignification des parois de l'hypoderme, constitutive et induite par le champignon, joue un rôle significatif dans le blocage de l'invasion mycélienne. Le rôle important des composés phénoliques dans la résistance des vanilliers a été confirmé par les analyses d'expression différentielle de transcrits obtenus de novo par RNA-seq Illumina. Enfin, un test robuste de détermination in-vitro de la résistance à Forv a été validé et de nouvelles sources de résistance génétique à la PRT ont été identifiées. Nos résultats ouvrent des perspectives prometteuses pour la sélection de variétés améliorées de vanilliers
Vanilla is a high value cash crop that is continuously demanded by the agri-food and cosmetics industries for its incomparable flavor. Most of vanilla comes from the cured fruits of V. planifolia G. Jackson, a hemi-epiphytic climbing orchid cultivated in the humid tropics. In all the countries were it is cultivated, the vanilla vines suffer from a root and stem rot (RSR) caused by the soil borne fungus Fusarium oxysporum which dramatically reduces plant production and the durability of plantations. No efficient control method is currently available for this disease. Sources of genetic resistance to RSR exist in few vanilla relatives, but so far no commercial resistant variety has been produced. The purpose of this thesis was to better describe the diversity and histopathology of the causal agent of RSR and to evaluate the potential sources of genetic resistance that could be used in breeding programs. In a first step, a collection of 377 single-spored Fusarium isolates recovered from rotten roots and stems during surveys conducted in 52 vanilla plots from Reunion Island, Madagascar and French Polynesia were characterised. Representative subsets of isolates were genotyped using the Elongation Factor 1α and Intergenic Spacer gene sequences. Their pathogenicity was assayed by root dip inoculation on the susceptible V. planifolia accession pla0001. Results showed that F. oxysporum was the principal species responsible for the disease in the field, although a few F. solani isolates showing slight pathogenicity were also isolated. Fusarium oxysporum isolates were highly polyphyletic regardless of geographic origin or pathogenicity. Remarkably, their pathogenicity varied in gradient between non- pathogenic (about 42% of isolates) to highly pathogenic (14%). In a second step, 254 vanilla accessions comprising 18 species and six types of hybrids were assessed for resistance to RSR in the field (natural inoculum) and in the lab (in-vitro plants inoculated with Fo072). The strong resistance to RSR of all V. pompona accessions and hybrids of V. planifolia X V. pompona or V. phaeantha, were confirmed, and novel sources of resistance to RSR were added including, V. bahiana, V. costariciensis and V. crenulata. Most of the V. planifolia accessions, V. ×tahitensis and V. odorata were susceptible to RSR. However, three inbreeds of V. planifolia showed a high level of resistance to Forv. To our knowledge this is the first report of resistance to RSR in V. planifolia accessions. For the 26 accessions evaluated in both conditions, a strong correlation was observed between long term (9 years) evaluation in the field and ratings on in-vitro plants at 15dpi. Thirdly, we monitored by wide field and multiphoton microscopy the root infection process and the responses of one susceptible accession (V. planifolia pla0001) and two resistant accessions (V. planifolia pla0020 and V. pompona pom0018) to challenge inoculation with the severe isolate Fo072. In the compatible interaction (Fo072 – pla0001) invasion started from penetration of hyphae emitted from germinated conidia in the hairy region of root rapidly colonizing the cortex but never expanded to the vascular bundles up to the 9th dpi. It was therefore suggested to prefix the forma specialis name of the causal agent of RSR with radicis to point out its non-vascular pathogenicity in vanilla. In the two incompatible interactions, the important role played by hypodermis cells for impeding the invasion of the cortex by Fo072 was demonstrated by specific staining and spectral analysis of lignin precursors. Both constitutive and pathogen induced defense mechanism were described in pla0020 and pom0018. The mechanisms included the deposition of lignin in the hypodermal cell wall, entrapment of hyphae in specific hypodemal cells and polyphenolics secretion in intercellular spaces. Further, a de novo transcriptome analysis was experimentedon 8 pooled samples

Avec l’avènement du numérique, il est désormais possible aux chercheurs d’amasser des grandes quantités de données et les plateformes de réseaux sociaux en ligne ne font pas exception à cela. Les sociologues, comme d’autres, se sont emparés de ces nouvelles ressources afin de poursuivre leurs enquêtes sur les modalités de l’interaction entre individus et leur impact sur la structuration de la sociabilité. Suivant cette voie, ce travail de thèse vise à l’analyse d’un grand nombre de comptes Facebook, aussi bien au travers des outils classiques de l’analyse de données que de la théorie des graphes, à laquelle des contributions méthodologiques sont apportées. Deux facteurs principaux encouragent l’étude de l’activité et de la sociabilité en ligne. D’une part, le temps important dédié à cette plateforme par de nombreux internautes justifie l’intérêt porté par les sociologues aux échanges qui s’y construisent. Par ailleurs, et contrairement à ce que l’on peut observer sur d’autre sites de réseaux sociaux en ligne, les liens entre individus sur Facebook sont proches de ceux hors-lignes. Dans un premier temps, la thèse s’évertue à démêler les multiples facettes de ce à quoi ”être sur Facebook” correspond. Distribués autour de pratiques normatives fabulées, les usages de nos enquêtés fluctuent au gré de leur appropriation ou non des composantes de l’importante variété de moyens de communication proposés par la plateforme. Ces usages, comme on le verra, sont ainsi différemment adoptés selon les catégories socioprofessionnelles et influent par ailleurs sur les modalités d’échanges et d’interactions des enquêtés avec leurs amis en ligne. Ces modalités sont également explorées dans ce travail, tout comme le rôle du conjoint et sa place dans la structure relationnelle. La seconde partie de la thèse se propose de construire une typologie de ces structures relationnelles dites égocentrées, c’est-à-dire depuis le point de vue de l’enquêté. Cette typologie des réseaux de sociabilité en ligne se base sur l’énumération de leurs sous-graphes induits, les graphlets, initialement développée par des chercheurs en bioinformatique. Cette approche offre une vision méso (entre micro et macro) des réseaux, propice à souligner des phénomènes inédits de sociologie des réseaux. A fort potentiel pluri-disciplinaire, la méthodologie graphlets elle même est également discutée et explorée
With the digital advent, it is now possible for researchers to collect important amounts of data and online social network platforms are surely part of it. Sociologists, among others, seized those new resources to investigate over interaction modalities between individuals as well as their impact on the structure of sociability. Following this lead, this thesis work aims at analyzing a large number of Facebook accounts, through data analysis and graph theory classical tools, and to bring methodological contributions. Two main factors encourage to study Facebook social activities. On one hand, the importance of time spent on this platform by many Internet users justifies by itself the sociologists interest. On the other, and contrarily to what we observe on other social network websites, ties between individuals are similar to the ones that appear offline. First, the thesis proposes to detangle the multiple meanings that are behind the fact of ”being on Facebook”. The uses of our surveyed are not compacted in fantasized normative practices but vary depending on how they appropriate the different composers of the platform tools. These uses, as we will see it, do not concern all the socioprofessional categories in the same way and they also influence how the respondents interact with their online friends. The manuscript also explores these interactions, as well as the lover role into the relational structure. Second part of the thesis builds a typology of these relational structures. They are said as egocentred, which means that they are taken from the perspective of the respondent. This typology of social networks is based on their graphlet counts, that are the number of times each type of subnetwork appear in them. This approach offers a meso perspective (between micro and macro), that is propitious to underline some new social phenomena. With a high pluri-disciplinary potential, the graphlet methodology is also discussed and explored itself

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O Brasil é líder na produção de cana-de-açúcar e a cada ano o setor vem crescendo e buscando novas formas para diversificar a planta de produção. Tal fato que o nome da indústria evoluiu de sucroalcooleira para sucroenergéticas devido à importância da co-geração de energia a partir da queima do bagaço nas caldeiras. A bioeletricidade de cana-de açúcar caminha a passos constantes e segue com vários projetos pelo país, devido as usinas estarem próximas dos centro e distribuição/consumo. Outra empresa que busca esta diversificação da sua planta são as indústrias de papel e celulose, principalmente dos seus rejeitos (lignina). Este trabalho tem como objetivo extrair lignina diferentes variedades de cana-de-açúcar para identificar a variedade que tem melhor rendimento na extração da lignina e rendimento energético, comparar com o bagaço misto (mistura de várias variedades) e por fim desenvolver imunossensores por meio da reação entre antígenos e anticorpos sobre superfícies condutoras de nanografite a partir da mistura de lignina de bagaço de cana e lignina Kraft. A grande questão é a aplicação eletroquímica com o desenvolvimento de imunossensores devido a alta sensibilidade e principalmente pelo baixo custo e utilização em área clínica. A partir do presente estudo pode-se inferir que a variedade SP83-2847 possui o maior rendimento na extração da lignina, já em relação a perda calorífica a variedade SP84-1431 obteve o maior valor e a RB86-7515 o menor. Após a extração da lignina o bagaço resultante contento celulose e hemicelulose apresentou ser mais estável termicamente. As Técnicas de Raios-x e infravermelho confirmaram a extração da liginina, além de demostrar que existe resquício da fração de celulose e hemicelulose na lignina extraída e que o mesmo ocorre quando extraímos a lignina, uma fração fica na celulose. O eletrodo construído a partir do compósito nonografite-lignina kraft modificado com cobre apresentou atividade eletroquímica, estabilidade mecânica e eletroquímica.
Brazil is a leader in sugarcane production, growing each year and looking for new ways to diversify the plant production. By the way, the industries names evolved from sugar and alcohol to sugar and energy due to its importance in energy cogeneration from bagasse burning in boilers. The cane bioeletricity walks in constant steps and continues with various projects around the country, because the plants are close downtown and distribution and consumption centers. Another company seeking this diversification of the plant are the industries of pulp and paper especially its residues (lignin). This project aims to extract lignin from different varieties of sugarcane to identify the the best performer in the extraction and energy efficiency compared with the mixed bagasse sample (mixture of several varieties) and finally develop immunosensors through the reaction between antigens and antibodies on conductive nanographite surfaces from Kraft lignin and bagasse’s lignin mixture. The great question is the development of immunosensors due to high sensitivity and especially the applicability in the clinical area. From this study it can infer that the SP83-2847 variety has the highest extraction yield of lignin, as compared to loss heat the variety SP84-1431 obtained the highest value and the lowest was the RB86-7515. After lignin extraction, the resulting residue containing cellulose and hemicellulose showed to be more thermally stable. XRD and FTIR results confirmed lignin extraction and demonstrated that there is remnant cellulose and hemicellulose fraction of extracted lignin and the same occurs when we extract lignin, a fraction remains in cellulose. The electrode constructed from the composite kraft lignin-nonographite modified with copper showed electrochemical activity, mechanical stability and electrochemistry. These were applied to investigate uric acid in simulated blood plasma samples. For sure lignin is a byproduct that in near future will be a very promising and profitable raw materials in different industries.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
A model of an international energy matrix, ideally based on renewable and cleaner energy regarded to petrol, is justified because of the increasing awareness on the global warming issue. Moreover, researches on biofuel, as an alternative source of energy, are essential to guarantee the current ranking of the Brazilian energy autonomy, in addition to the interest in production of surplus so to guarantee exportation and generation of foreign exchange. Cellulose is the most abundant renewable biomass in the planet, therefore a good energetic alternative to petrol. Sugarcane has 2/3 of its mass in lingocellulosic material, an abundant energetic resource which is not efficiently used by the current technologies, therefore, representing an enormous potential for the production of lingocellulosic ethanol. Cellulose can be hydrolyzed in glucose residuals by enzymatic treatment as well as base of acids. Technically, there are some barriers associated to acid and /or enzymatic hydrolysis which need to be overcome. Considering enzymatic hydrolyses, the reaction takes place in a non-aggressive medium, however it takes a long waiting time (from 60 to 72 hours) to occur and the lignin compound is one of the main obstacles for the enzyme access to the cellulose. Thus, the present work aimed at obtaining progress for researches on cellulosic ethanol from the bagasse and, potentially, from other sugarcane by-products through selection of clones that shows high potential bioconvertibility fibers. The experiment was made up of 286 clones and 2 witnesses (RB867515 and SP80-1842) in 25 blocks. They were selected from 13 families of half-siblings and they were vegetative propagation first generation clones. Accordingly, it was carried out correlations among desirable biochemical and agronomical traits, evaluating the cause and effect relationship on fibers and lignin of the stem. It was also estimated the possibility on defining characters which have to be used to carry out a recurrent selection program on sugarcane aiming at alcohol production. It was selected 10 clones with highest lignin content and 10 clones with the lowest lignin content in the bagasse. Those 20 clones were evaluated for the possibility in obtaining a higher glucose content after enzymatic hydrolysis process for cellulosic alcohol production. It could be observed that the higher the content of lignin in the bagasse, the lower the content of glucose produced at the end of hydrolyzesprocess. It was also observed that hemicellulose is more efficient on the conversion than saccharification. Hemicellulose functions as a positive factor on fermentable sugar production for fermentation, because it breaks down cellulose structure allowing access of the enzymes and because of its rupture it supplies glucose molecules for fermentation. Therefore, selected clones show a high potential use on sugar cane genetic breeding, even though it is still needed phenotypic and gene expression analysis studies, enzymatic quantification and syntheses of metabolic, correlating them to syntheses of lignin.
Um modelo de matriz energética mundial, idealmente baseado em fontes mais limpas e renováveis de energia em relação ao petróleo, se justifica pela crescente preocupação com a questão do aquecimento global. Além disso, pesquisas em biocombustíveis como fontes alternativas de energia são essenciais para garantir a atual posição de autonomia energética brasileira, além do interesse pela produção de excedentes para garantir a exportação e geração de divisas. Celulose é a biomassa renovável mais abundante na face da terra e por isso, uma boa alternativa energética em relação ao petróleo. Cana de açúcar apresenta na sua massa 2/3 de sua massa em material ligno-celulósico, um recurso energético abundante não utilizado eficientemente por meio das tecnologias atuais, representando portanto, um enorme potencial para a produção de etanol ligno-celulósico. A celulose pode ser hidrolisada em resíduos de glicose tanto por tratamento enzimático ou a base de ácidos. Há inconvenientes associados à hidrólise ácida e/ou enzimática do ponto de vista técnico e que precisam ser superados. No caso da hidrólise enzimática, a reação ocorre em meio não agressivo, porém, requer um longo tempo de espera (60 a 72 horas) e a componente lignina apresenta-se como um dos principais barreiras para o acesso da enzima a celulose. Portanto, o presente trabalho teve como objetivo obter avanços nas pesquisas em etanol celulósico a partir do bagaço e, potencialmente, outros resíduos provenientes do processamento da cana-de-açúcar, por meio da seleção de clones que apresentem fibra com elevado potencial de bioconversibilidade. O experimento foi composto por 286 clones e 2 testemunhas (RB867515 e SP80-1842) em 25 blocos. Tais clones foram selecionados de 13 famílias de meios-irmãos e constituíram clones de primeira geração de propagação vegetativa. Para isso efetuou correlações entre características agronômicas e bioquímicas desejáveis, avaliando a relação causa e efeito sobre o fibras e lignina dos colmos. Também estimou-se a possibilidade de definir os caracteres que deverem ser empregados para conduzir um programa de seleção recorrente em cana-de-açúcar visando à produção de álcool celulósico. Dos clones foram selecionas os 10 que apresentaram maior teor de lignina e os 10 que apresentaram menor teor de lignina no bagaço de cana. Os 20 clones foram avaliados quanta a possibilidade de se obter um maior teor de glicose após o processo de hidrólise enzimática para produção de álcool celulósico. Foi possível observar que quanto maior o teor de lignina no bagaço menor o teor de glicose produzida ao final do processo de hidrólise. Também foi observado que o caráter hemicelulose teve maior correlação com a sacarificação. A hemicelulose funciona como um fator positivo na produção de açúcares fermentáveis para a fermentação, pois abre a estrutura da celulose permitindo acesso enzimático e pela sua quebra fornece moléculas de glicose para a fermentação. Portanto os clones selecionados apresentam potencial para aplicação no melhoramento genético da cana de-açúcar, mesmo que ainda sejam necessários estudos complementares fenotípicos e de análise expressão gênica, quantificação enzimática e síntese de metabólicos, correlacionando-os com a síntese de lignina.

Plant cell walls play a central role in cell growth and morphogenesis. All plant cells have a primary wall. The formation of a secondary cell wall is restricted to particular cell types, such as the xylem cells, highly lignified cells that provide support and transport functions to the plant. The mechanisms regulating secondary cell wall biogenesis remain largely unknown. To identify genes involved in such mechanisms, a genetic screen for mutants with altered xylem development in the primary root of Arabidopsis thaliana has been conducted. Three different classes of mutants were identified. They are characterised by increased number of xylem strands (m"), altered timing of protoxylem differentiation (tpx) and ectopic lignification (eh). Initial characterisation of the mutant phenotypes, establishment of different complementation groups and their map position in the Arabidopsis genome has been determined. Mutations in the EL [I locus have been characterised in further detail. The eli l mutants exhibited ectopic lignification of cells throughout the plant that never normally lignify. Xylem cells in elil were misshapen and failed to differentiate into continuous strands, causing a disorganised xylem. elil mutants also exhibited altered cell expansion resulting in a stunted phenotype. Abnormal distribution of cellulose and lignin was observed in elil cell walls. Ultrastructural analysis of elil cell walls using an anti-lignin antibody has revealed that that the ectopic deposition of lignin-like compounds occurs within an altered secondary wall. Furthermore, other previously described cell expansion mutants, such as lit, rswl (at the conditional temperature) and det3, exhibited lignification patterns reminiscent to that of elil mutants. Analysis of the genetic interactions of elil with the lit mutant revealed that ELlI and LIT genes act in independent pathways to control cell expansion. These results, together with the double mutant analysis of eli l with other cell expansion mutants suggested a link between cell growth and differentiation of secondary thickened walls. Map-based cloning placed the ELJ1 gene in a 140-Kb interval on the top arm of Arabidopsis chromosome V. A candidate gene approach was used that identified a gene encoding a cellulose synthase catalytic subunit (CesA), AthCesA-3 as a candidate. Sequence analysis revealed that the AthCesA-3 gene is mutated in two elil alleles sequenced, both mutations leading to amino acid substitutions. Initial complementation experiments of elil plants with the wild type AthCesA-3 gene appeared to restore the wild type phenotype, suggesting that mutations in the AthCesA-3 gene gave rise to the elil phenotypes. These studies represent an important contribution to our understanding of the molecular mechanism of cellulose deposition during cell expansion and secondary cell wall deposition during plant morphogenesis.

En se basant sur une observation participante et la collecte de données recueillies par d'autres techniques d'observation (statistiques, observation directe), nous avons exploré en profondeur le fonctionnement d'une encyclopédie : l'encyclopédie en ligne libre et ouverte Wikipédia1. Cette observation participante a consisté à contribuer activement au projet open source, à nous impliquer dans son fonctionnement, au point même de tenter d'agir sur certains aspects organisationnels (prises de décision, publication d’articles), tout ceci dans le but d’analyser les méthodes employées. Cependant, rectifions d'emblée, il ne s'agit pas seulement d'un projet open source au sens strict du terme, mais d'un concept très particulier dont l'étendue, le public, les pratiques, la nature juridique, font qu'il se trouve à la croisée de divers milieux : monde scientifique, culture libre, population étudiante, public des forums et du Web 2.0.Au niveau théorique, cette observation présente plusieurs intérêts. Elle permet tout d'abord de démontrer que Wikipédia ne se limite pas à une activité informatique immatérielle. Wikipédia pénètre aujourd'hui toutes les activités culturelles, scientifiques voire juridiques.On peut aussi à travers cette étude tirer des enseignements sur la dynamique, le fonctionnement et le crédit à accorder à une telle entreprise. L'immersion dans le projet nous a, en effet, permis de mieux comprendre les logiques et les dynamiques de Wikipédia. Cette étude peut également servir de référent ou d'élément comparatif dans l'observation et l'analyse d'autres projets similaires ou sous forme papier dont les méthodes de réalisation sont différentes (Encyclopædia Universalis, encyclopédie Larousse en ligne, Encarta...). Et enfin, en phase avec l’ère du numérique, elle offre la perspective de nouvelles voies de régulation et des pistes pour exploiter ces nouveaux outils cognitifs
Based on participant observation and collection of data gathered by other observation techniques (statistics, direct observation), we explored in depth the operation of an encyclopedia: the free and open online encyclopedia Wikipedia. The participant observation consists in actively contributing to the open source project, in getting involved in its operation, even to the point of trying to act on some organizational aspects (decision-making, publication of articles), all this in order to analyze the methods used. However, let’s immediately rectify, this is not only an open source project in the strict sense of the term, but a very particular concept of which extent, public, practices, legal nature, make so that it is located at the crossroads of various backgrounds: scientific world, free culture, students, forums’ public and Web 2.0.On the theoretical level, this observation presents several interests. It first allows to show that Wikipedia is not limited to an immaterial computer activity. Wikipedia now penetrates all cultural, scientific and even legal activities.Through this study, we can also learn on the dynamic, the functioning and the credit to grant to such an undertaking. The immersion in the project has indeed helped us to better understand the logics and dynamics of Wikipedia. This study can also serve as reference or comparative element in the observation and analysis of similar projects or in paper form of which construction methods are different (Encyclopædia Universalis, Larousse online encyclopedia, Encarta ...). And finally, in step with the digital age, it offers the prospect of new regulatory pathways and trails to exploit these new cognitive tools

Thermo-stabilized lignin fibers from pH-fractionated softwood kraft lignin were carbonized to various temperatures during thermomechanical analysis (TMA) under static and increasing load and different rates of heating. The aim was to optimize the carbonization process to obtain suitable carbon fiber material with good mechanical strength potential (high tensile strength and high E-modulus). The carbon fibers were therefore mainly evaluated of mechanical strength in Dia-Stron uniaxial tensile testing. In addition, chemical composition, in terms of functional groups, and elemental (atomic) composition was studied in Fourier transform infrared spectroscopy (FTIR) and in energy-dispersive X-ray spectroscopy (EDS), respectively. The structure of carbon fibers was imaged in scanning electron microscope (SEM) and light microscopy. Thermogravimetrical analysis was performed on thermo-stabilized lignin fibers to evaluate the loss of mass and to calculate the stress-changes and diameter-changes that occur during carbonization. The TMA-analysis of the deformation showed, for thermo-stabilized lignin fibers, a characteristic behavior of contraction during carbonization. Carbonization temperatures above 1000°C seemed most efficient in terms of E-modulus and tensile strength whereas rate of heating did not matter considerably. The E-modulus for the fibers was improved significantly by slowly increasing the load during the carbonization. The tensile strength remained however unchanged. The FTIR-analysis indicated that many functional groups, mainly oxygen containing, dissociate from the lignin polymers during carbonization. The EDS supported this by showing that the oxygen content decreased. Accordingly, the relative carbon content increased passively to around 90% at 1000°C. Aromatic structures in the carbon fibers are thought to contribute to the mechanical strength and are likely formed during the carbonization. However, the FTIR result showed no evident signs that aromatic structures had been formed, possible due to some difficulties with the KBr-method. In the SEM and light microscopy imaging one could observe that porous formations on the surface of the fibers increased as the temperature increased in the carbonization. These formations may have affected the mechanical strength of the carbon fibers, mainly tensile strength. The carbonization process was optimized in the sense that any heating rate can be used. No restriction in production speed exists. The carbonization should be run to at least 1000°C to achieve maximum mechanical strength, both in E-modulus and tensile strength. To improve the E-modulus further, a slowly increasing load can be applied to the lignin fibers during carbonization. The earlier the force is applied, to counteract the lignin fiber contraction that occurs (namely around 300°C), the better. However, in terms of mechanical performance, the lignin carbon fibers are still far from practical use in the industry.

Wood is our most important renewable resource. We need better quality and quantity both according to the wood itself and the processes that are using wood as a raw material. Hence, the understanding of the chemical composition of the wood is of high importance. Improved and new methods for analyzing wood are important to achieve better knowledge about both refining processes and raw material. The combination of NMR and multivariate analyses (MVA) is a powerful method for these analyses but so far it has been limited mainly to 1D NMR. In this project, we have developed methods for combining 2D NMR and MVA in both wood analysis and metabolomics. This combination was used to compare samples from normal wood and tension wood, and also trees with a down regulation of a pectin responsible gene. Dissolving pulp was also examined using the same combination of 2D-NMR and MVA, together with FT-IR and solid state 13C CP-MAS NMR. Here we focused on the difference between wood type (softwood and hardwood), process type (sulfite and sulfate) and viscosity. These methods confirmed and added knowledge about the dissolving pulp. Also reactivity was compared in relation to morphology of the cellulose and pulp composition. Based on the method and software used in the wood analysis projects, a new method called HSQC-STOCSY was developed. This method is especially suited for assignment of substances in complex mixtures. Peaks in 2D NMR spectra that correlate between different samples are plotted in correlation plots resembling regular NMR spectra. These correlation plots have great potential in identifying individual components in complex mixtures as shown here in a metabolic data set. This method could potentially also be used in other areas such as drug/target analyses, protein dynamics and assignment of wood spectra.

D’après « The Pew Internet & American Life Project », 67% des Américains adultes aux Etats-Unis ont effectué un achat de bien en ligne entre mai et juin 2005. Une seconde enquête menée par « The Pew Internet & American Life Project », réalisée entre février et avril 2006, indique que 73% des Américains adultes (i. E. , environ 147 millions d’individus) utilisent Internet. Ces statistiques suggèrent qu’il existe un potentiel de croissance du commerce électronique dans les années à venir. Cependant, il n’existe que peu d’informations concernant les comportements individuels en ligne. Notre thèse a pour objet l’étude de l’incidence du commerce électronique sur les comportements d’achat en ligne des ménages aux Etats-Unis, et a pour objectif de déterminer les facteurs permettant d’expliquer les décisions d’achat en ligne des ménages. Notre analyse empirique porte sur les achats de livres et de CD en ligne effectués au cours d’une période donnée allant du 1er juillet au 31 décembre 2002. Le commerce électronique influence de manière non négligeable les comportements individuels en ligne, avec un impact important sur la dispersion des prix des biens et les coûts de recherche d’informations des acheteurs en ligne, et modifie les prises de décision d’achat de biens en ligne. Lors de son émergence Internet est qualifié « The Great Equalizer » (Brynjolfsson et Smith 2001) selon l’hypothèse qu’une large utilisation d’Internet réduit les coûts de recherche d’informations en ligne des acheteurs, augmente la concurrence entre les vendeurs en ligne, et incite les acheteurs à effectuer davantage une recherche d’informations en ligne. Une des conséquences possibles d’une diminution des coûts de recherche d’informations est un comportement de non loyauté et de non fidélité à la marque des acheteurs en ligne, ainsi qu’une hausse de la sensibilité des acheteurs vis-à-vis des prix des biens. Les acheteurs ayant la capacité de comparer différentes offres en ligne en quelques « clicks » (Shapiro & Varian 1999), Internet est perçu comme un espace « sans frictions » (Brynjolfsson et Smith 2000), et les acheteurs sont davantage enclins à effectuer un transfert entre les différents sites des vendeurs au détail en ligne. Cependant, les études empiriques réalisées jusqu’à présent montrent une dispersion des prix en ligne significative pour un bien homogène, en tenant compte des caractéristiques des vendeurs. Les biens physiques homogènes, tels que les livres ou les CD, sont les biens les plus susceptibles de connaître une concurrence en prix étant donné les caractéristiques du commerce électronique. Or, les analyses empiriques récentes montrent une dispersion des prix en ligne importante et ne rendent pas compte d’une compétition en prix à la Bertrand alors que le bien considéré est homogène. L’objet de notre thèse a pour but d’identifier quels sont les sites de vendeurs au détail en ligne capables de maintenir une forte fidélité à la marque, et de quelle manière les vendeurs incitent les acheteurs en ligne à répéter leurs visites sur un même site. Nous menons deux analyses empiriques à partir de fichiers mis à notre disposition et nous provenant de la base de données Comscore. Ces données comprennent des informations concernant les comportements de recherche d’informations et d’achat en ligne des ménages aux Etats-Unis, au cours d’une période allant du 1er juillet au 31 décembre 2002. Nous soulevons les problématiques suivantes : Quels sont les facteurs venant justifier l’effet de transfert au départ d’un site donné vers un autre site? L’objet de la thèse est de mieux comprendre les déterminants du comportement de loyauté et de fidélité au site d’un vendeur au détail en ligne. Nous suggérons l’existence d’une prolifération des vendeurs au détail en ligne, ainsi que d’une fragmentation du commerce de détail en ligne. Face à cette croissance, la vente au détail en ligne suscite un intérêt pour les économistes et les gestionnaires afin de déterminer de quelle manière maintenir la fidélité ou la loyauté des ménages auprès des sites de vendeurs au détail en ligne. Quels sont les déterminants d’une disposition à payer des ménages pour une prime additionnelle (ou bien « price premium ») en ligne pour des biens homogènes ? Les biens homogènes en ligne viennent soulever la problématique la suivante : quels sont les ménages disposés à payer un « price premium » ? Et sur quel type de sites ces ménages ont-ils une disposition à payer supérieure ? L’objet de notre thèse a pour objet de donner les déterminants d’une disposition à payer des ménages pour un « price premium » en ligne pour des biens homogènes. En focalisant notre analyse sur les biens homogènes (les livres et les CD en ligne), nous cherchons à déterminer ce qui vient affecter l’achat d’un bien homogène en ligne, ainsi que la perception d’un bien homogène auprès de l’acheteur. Notre analyse empirique identifie l’existence d’un comportement de loyauté en ligne auprès des vendeurs au détail en ligne bénéficiant d’un effet de réputation élevé ou bien de type générique. Notre analyse indique les différentes dispositions à payer des ménages pour des biens homogènes, et a pour but de compléter les travaux empiriques précédents (Brynjolfsson et Smith 2001) concernant la disposition à payer des ménages pour des livres homogènes
This dissertation adds to the online household behaviour on switching effect and price premium on the Internet. In particular the analysis looks at the context where households make purchase decisions for books and CD online on different retailers Web site. The approach here combines theory and data to examine how such purchase decision and choices of retailers Web site vary with different factors affecting the online business environment. Part one addresses a theoretical aspect of price dispersion, search costs, and transaction costs on the Internet and in conventional markets. In Part two, I explore two interrelated empirical research questions by using clickstream data in the online retail industry: what retains consumers to a retailer Web site? And, for any particular book/CD and based on household characteristics what make households pay for a price premium? How much is price sensitivity to any particular book/CD? Our results point to a low incidence of switching among retailers with an evidence of consumer loyalty. I also argue that some factors might affect the choice of retailer and the willingness to pay for a price premium. Each retailer can offer a homogeneous product in a sense that the same product is also available at another retailer site. I propose a random utility/discrete choice framework (McFadden 1974) and develop hypotheses about the effect purchasing economies of scope on price premium for homogeneous books/CD, as purchase appears to be driven by economies of scope in shipping costs across a diverse basket of goods. I develop hypotheses about the effect of economies of scope, household characteristics and past behaviour, and bundle characteristics (e. G. , shipping and discount) on the price premium for homogeneous products. The purpose of this research is threefold. First, I apply a discrete choice modeling framework (McFadden 1974) to study different low-cost items and not only one industry. Second, there is no empirical analysis on extending the analysis to the full basket of goods that consumers purchase. Our analysis aims to contribute to the previous empirical literature findings where amazon. Com has a price advantage over generic and brand retailers, i. E. Amazon. Com closest rivals. (i. E. , Brynjolfsson and Smith, 2001). The extant literature has sought to focus on product categories in understanding purchase loyalty rather than focusing on consumers as the unit of analysis. In directing attention at product categories we obtain only a partial picture of how consumers make purchase decisions across product categories. By ignoring the full basket of goods that consumers purchase we run the risk of erroneously inferring the absence of loyalty when consumers may be using systematic rules in making purchase decisions across the basket

Kernthema der Dissertation ist die Weiterentwicklung von Kohle-Online-Messtechniken zur kontinuierlichen Bestimmung, das Brennstoffverhalten in Kraftwerkskesseln beeinflussender anorganischer Kohleinhaltsstoffe im Rheinischen Braunkohlerevier, die geologisch bedingt, natürlichen Schwankungen unterliegen. Im Rahmen dieses Vorhabens wurden die Gammastrahlenabsorptionsverfahren zur Aschegehaltsbestimmung und die Prompte-Gamma-Neutronen-Aktivierungs-Analyse (PGNAA) zur Multielement-Analyse als innovative Messmethoden zur Analyse des gesamten Kohlestroms auf Förderbandanlagen identifiziert, deren Eignung im Rahmen von Voruntersuchungen bestätigt, betrieblich eingeführt und unter Praxisbedingungen optimiert. Dabei wurde die Wechselwirkung zwischen Gamma- und Neutronenstrahlung unterschiedlicher Energien mit Braunkohlen und Fördergurten unterschiedlicher Eigenschaften sowie Einflüsse variierender homogener und inhomogener Elementzusammensetzungen bei verschiedenen Messsystemanordnungen und Förderleistungen auf die Messergebnisse systematisch erfasst und für die Versuchsanlagen in der betrieblichen Praxis umgesetzt. Die Gamma-Absorptionsmethode ist im betrieblichen Einsatz, die Erprobung der PGNAA-Prototypanlage steht bevor.

Glycerol thermal processing (GTP) is studied as a novel biomass pretreatment method in this research with the purposes to facilitate biopolymer fractionation and biomass saccharification. This approach is performed by treating sweet gum particles on polymer processing equipment at high temperatures and short times in the presence of anhydrous glycerol. Nine severity conditions are studied to assess the impact of time and temperature during the processing on biopolymer structure and conversion. The GTP pretreatment results in the disruption of cell wall networks by increasing the removal of side-chain sugars and lignin-carbohydrate linkages based on severity conditions. After pretreatment, 41% of the lignin and 68% of the xylan is recovered in a dry powdered form by subsequent extractions without additional catalysts, leaving a relatively pure cellulose fraction, 84% glucan, as found in chemical pulps. Lignin structural analysis indicated GTP processing resulted in extensive degradation of B-aryl ether bonds through the C-y elimination, followed by abundant phenolic hydroxyl liberation. At the same time, condensation occurred in the GTP lignin, providing relatively high molecular weight, near to that of the enzymatic mild acidolysis lignin. Better thermal stability was observed for this GTP lignin. In addition to lignin, xylan was successfully isolated as another polymer stream after GTP pretreatment. The recovered water insoluble xylan (WIX) was predominant alkali soluble fraction with a maximum purity of 84% and comparable molecular weight to xylan isolated from non-pretreated fibers. Additionally, the narrow molecular weight distribution of recovered WIX, was arisen from the pre-extraction of low molecular weight water-soluble xylan. Additionally, a 20-fold increase of the ultimate enzymatic saccharification for GTP pretreated biomass was observed even with significant amounts of lignin and xylan remaining on the non-extracted fiber. The shear and heat processing caused a disintegrated cell wall structure with formation of biomass debris and release of cellulose fibrils, enhancing surface area and most likely porosity. These structural changes were responsible for the improved biomass digestibility. Additionally, no significant inhibitory compounds for saccharification are produced during GTP processing, even at high temperatures. While lignin extraction did not promote improvement in hydrolysis rates, further xylan extraction greatly increases the initial enzymatic hydrolysis rate and final level of saccharification. The serial of studies fully demonstrate glycerol thermal processing as a novel pretreatment method to enhance biomass saccharification for biofuel production, as well as facilitate biopolymer fractionation. Moreover, the study shows the impact of thermally introduced structural changes to wood biopolymers when heated in anhydrous environments in the presence of hydrogen bonding solvent.
Ph. D.

La personnalisation vise à recueillir les intérêts, les préférences, les usages, les contraintes, le contexte, etc. souvent considérés comme faisant partie de ce que l'on appelle ''profil utilisateur'' pour ensuite les intégrer dans un système et les exploiter afin de permettre à l'utilisateur d'accéder rapidement aux informations les plus pertinentes pour lui. Par ailleurs, au sein d'une organisation, différents acteurs sont amenés à prendre des décisions à différents niveaux de responsabilité et ont donc besoin de réaliser des analyses à partir de l'entrepôt de données pour supporter la prise de décision. Ainsi, dans le contexte de cette communauté d'utilisateurs de l'entrepôt de données, la notion de collaboration émerge. Il est alors intéressant de combiner les concepts de personnalisation et de collaboration pour approcher au mieux les besoins des utilisateurs en leur recommandant des analyses en ligne pertinentes. L'objectif de ce mémoire est de proposer une approche collaborative pour l'OLAP, impliquant plusieurs utilisateurs, dirigée par un processus de personnalisation intégré aux systèmes décisionnels afin de pouvoir aider l'utilisateur final dans son processus d'analyse en ligne. Qu'il s'agisse de personnalisation du modèle d'entrepôt, de recommandation de requêtes décisionnelles ou de recommandation de chemins de navigation au sein des cubes de données, l'utilisateur a besoin d'un système décisionnel efficace qui l'aide dans sa démarche d'analyse en ligne. La finalité est de fournir à l'utilisateur des réponses pertinentes proches de ses besoins pour qu'il puisse mieux appréhender ses prises de décision. Nous nous sommes intéressés dans cette thèse à trois problèmes relevant de la prise en compte de l'utilisateur au sein des entrepôts de données et de l'OLAP. Nos contributions s'appuient sur la combinaison de techniques issues de la fouille de données avec les entrepôts et OLAP. Notre première contribution est une approche qui consiste à personnaliser les hiérarchies de dimensions afin d'obtenir des axes d'analyse nouveaux sémantiquement plus riches pouvant aider l'utilisateur à réaliser de nouvelles analyses non prévues par le modèle de l'entrepôt initial. En effet, nous relâchons la contrainte du modèle fixe de l'entrepôt, ce qui permet à l'utilisateur de créer de nouveaux axes d'analyse pertinents en tenant compte à la fois de ses contraintes et des connaissances enfouies dans les données entreposées. Notre approche repose sur une méthode d'apprentissage non-supervisé, le k-means contraint, capable de créer de nouveaux regroupements intéressants des données entreposées pouvant constituer un nouveau niveau de hiérarchie permettant de réaliser de nouvelles requêtes décisionnelles. L'intérêt est alors de pouvoir exploiter ces nouveaux niveaux de hiérarchie pour que les autres utilisateurs appartenant à la même communauté d'utilisateurs puissent en tirer profit, dans l'esprit d'un système collaboratif dans lequel chacun apporte sa pierre à l'édifice. Notre deuxième contribution est une approche interactive pour aider l'utilisateur à formuler de nouvelles requêtes décisionnelles pour construire des cubes OLAP pertinents en s'appuyant sur ses requêtes décisionnelles passées, ce qui lui permet d'anticiper sur ses besoins d'analyse futurs. Cette approche repose sur l'extraction des motifs fréquents à partir d'une charge de requêtes associée à un ou à un ensemble d'utilisateurs appartenant à la même communauté d'acteurs d'une organisation. Notre intuition est que la pertinence d'une requête décisionnelle est fortement corrélée avec la fréquence d'utilisation par l'utilisateur (ou un ensemble d'utilisateurs) des attributs associés à l'ensemble de ses (leurs) requêtes précédentes. Notre approche de formulation de requêtes (...)
The objective of this thesis is to provide a collaborative approach to the OLAP involving several users, led by an integrated personalization process in decision-making systems in order to help the end user in their analysis process. Whether personalizing the warehouse model, recommending decision queries or recommending navigation paths within the data cubes, the user need an efficient decision-making system that assist him. We were interested in three issues falling within data warehouse and OLAP personalization offering three major contributions. Our contributions are based on a combination of datamining techniques with data warehouses and OLAP technology. Our first contribution is an approach about personalizing dimension hierarchies to obtain new analytical axes semantically richer for the user that can help him to realize new analyzes not provided by the original data warehouse model. Indeed, we relax the constraint of the fixed model of the data warehouse which allows the user to create new relevant analysis axes taking into account both his/her constraints and his/her requirements. Our approach is based on an unsupervised learning method, the constrained k-means. Our goal is then to recommend these new hierarchy levels to other users of the same user community, in the spirit of a collaborative system in which each individual brings his contribution. The second contribution is an interactive approach to help the user to formulate new decision queries to build relevant OLAP cubes based on its past decision queries, allowing it to anticipate its future analysis needs. This approach is based on the extraction of frequent itemsets from a query load associated with one or a set of users belonging to the same actors in a community organization. Our intuition is that the relevance of a decision query is strongly correlated to the usage frequency of the corresponding attributes within a given workload of a user (or group of users). Indeed, our approach of decision queries formulation is a collaborative approach because it allows the user to formulate relevant queries, step by step, from the most commonly used attributes by all actors of the user community. Our third contribution is a navigation paths recommendation approach within OLAP cubes. Users are often left to themselves and are not guided in their navigation process. To overcome this problem, we develop a user-centered approach that suggests the user navigation guidance. Indeed, we guide the user to go to the most interesting facts in OLAP cubes telling him the most relevant navigation paths for him. This approach is based on Markov chains that predict the next analysis query from the only current query. This work is part of a collaborative approach because transition probabilities from one query to another in the cuboids lattice (OLAP cube) is calculated by taking into account all analysis queries of all users belonging to the same community. To validate our proposals, we present a support system user-centered decision which comes in two subsystems: (1) content personalization and (2) recommendation of decision queries and navigation paths. We also conducted experiments that showed the effectiveness of our analysis online user centered approaches using quality measures such as recall and precision

Cette thèse évalue les performances de systèmes de stockage de données sur des réseaux de pairs. Ces systèmes reposent sur trois piliers: la fragmentation des données et leur dissémination chez les pairs, la redondance des données afin de faire face aux éventuelles indisponibilités des pairs et l'existence d'un mécanisme de recouvrement des données perdues ou temporairement indisponibles. Nous modélisons deux mécanismes de recouvrement des données par des chaînes de Markov absorbantes. Plus précisément, nous évaluons la qualité du service rendu aux utilisateurs en terme de longévité et de disponibilité des données de chaque mécanisme. Le premier mécanisme est centralisé et repose sur l'utilisation d'un serveur pour la reconstruction des donnée perdus. Le second est distribué : la reconstruction des fragments perdus met en oeuvre, séquentiellement, plusieurs pairs et s'arrête dès que le niveau de redondance requis est atteint. Les principales hypothèses faites dans nos modèles sont validées soit par des simulations soit par des traces réelles recueillies dans différents environnements distribués. Pour les processus de téléchargement et de recouvrement des données nous proposons un modèle de simulation réaliste qui est capable de prédire avec précision le comportement de ces processus mais le temps de simulation est long pour de grands réseaux. Pour surmonter cette restriction nous proposons et analysons un algorithme efficace au niveau flux. L'algorithme est simple et utilise le concept de (min-max). Il permet de caractériser le temps de réponse des téléchargements en parallèle dans un système de stockage distribué
This thesis characterizes the performance of peer-to-peer storage systems in terms of the delivered data lifetime and data availability. Two schemes for recovering lost data are modeled and analyzed: the first is centralized and relies on a server that recovers multiple losses at once, whereas the second is distributed and recovers one loss at a time. For each scheme, we propose several Markovian models that equally apply to many distributed environments as shown through numerical computations. These allow to assess the impact of each system parameter on the performance. In particular, we provide guidelines on how to tune the system parameters in order to provide desired lifetime and/or availability of data. The key assumptions made in the models are validated through intensive packet-level simulations or real traces collected from different distributed environments. In fact, we propose a realistic simulation model implemented on the Network Simulator (NS-2) for both download and recovery processes. Although this simulator can accurately predict the behaviour of the latter processes while considering the impact of several constraints such as the heterogeneity of peers and the the underlying network topologies, this simulator requires however relatively long time. To overcome this scalability limitation, we propose and analyze an algorithm. The algorithm is efficient in time and quite simple and uses the concept of ``Progressive-Filling'' (or max-min fairness). The validation of this algorithm consists in characterizing the distribution of the response time of parallel downloads in a distributed storage system, through simulations

This thesis presents a comparison analysis between various pyrolysis techniques performed on kraft lignin. Numerous literature studies of pyrolysis techniques performed on kraft lignin are reviewed and analysed where different operation temperatures, catalysts and different heating methods are used to pyrolyze kraft lignin. Based on the collected data from the reviewed literature, calculations are performed to determine energy efficiency of each pyrolysis technique. The energy efficiencies are used to establish a comparison between various pyrolysis techniques. Energy efficiencies of all pyrolysis techniques are determined by using series of equations. Dissimilarities of products composition are investigated between various pyrolysis techniques. Environmental impacts caused by lignin pyrolysis are reviewed and discussed. Uses of products produced from lignin pyrolysis are discussed to highlight the potential of using lignin as an energy resource to produce biooil, biochar and non-condensable gases (NCG). Results show that energy efficiencies differ significantly between various pyrolysis techniques, where microwave-assisted pyrolysis (MAP) shows the highest energy efficiency. Products produced from pyrolysis show a wide range of uses in many industrial applications. Lignin based products have the potential to replace many petroleum-based products which may contribute significantly to decrease pollutants in nature and gas emissions caused by combusting fossil fuels.

On suppose que des vecteurs de données de grande dimension arrivant en ligne sont des observations indépendantes d'un vecteur aléatoire. Dans le second chapitre, ce dernier, noté Z, est partitionné en deux vecteurs R et S et les observations sont supposées identiquement distribuées. On définit alors une méthode récursive d'estimation séquentielle des r premiers facteurs de l'ACP projetée de R par rapport à S. On étudie ensuite le cas particulier de l'analyse canonique, puis de l'analyse factorielle discriminante et enfin de l'analyse factorielle des correspondances. Dans chacun de ces cas, on définit plusieurs processus spécifiques à l'analyse envisagée. Dans le troisième chapitre, on suppose que l'espérance θn du vecteur aléatoire Zn dont sont issues les observations varie dans le temps. On note Zn_tilde = Zn − θn et on suppose que les vecteurs Zn_tilde forment un échantillon indépendant et identiquement distribué d'un vecteur aléatoire Z_tilde. On définit plusieurs processus d'approximation stochastique pour estimer des vecteurs directeurs des axes principaux d'une analyse en composantes principales (ACP) partielle de Z_tilde. On applique ensuite ce résultat au cas particulier de l'analyse canonique généralisée (ACG) partielle après avoir défini un processus d'approximation stochastique de type Robbins-Monro de l'inverse d'une matrice de covariance. Dans le quatrième chapitre, on considère le cas où à la fois l'espérance et la matrice de covariance de Zn varient dans le temps. On donne finalement des résultats de simulation dans le chapitre 5.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第22854号
農博第2437号
新制||農||1082(附属図書館)
学位論文||R2||N5314(農学部図書室)
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 本田 与一, 教授 田中 千尋, 准教授 坂本 正弘
学位規則第4条第1項該当

Le monde industriel est sans cesse confronté à des problèmes de choix. Une multitude de critères doit être pris en compte dans la résolution de ces derniers. Face à ces situations, les outils d’aide à la décision prennent tout leur sens. Nous utiliserons ici la méthode Analytic Hierarchic Process dans le domaine de la Production et plus particulièrement dans le cadre de l’ordonnancement d’une ligne de production de prothèses cardiovasculaires. Le paramétrage initial de cette méthode fait appel à l’évaluation d’un expert. Bien que ce dernier ait les connaissances nécessaires pour faire un paramétrage convenable, il n’en reste pas moins humain et introduira, même involontairement, une partie subjective dans ses décisions. L’ordonnancement en résultant ne sera donc pas forcément optimal. La réduction de cette subjectivité passe par l’utilisation d’une méta heuristique, de type algorithme génétique, pour améliorer ce paramétrage par l’exploration de solutions voisines à celles proposées par l’expert
The industrial world is continually faced with problems of choices. Multitude of criterion must be taken into account in resolving them. Faced with these situations, the decision making tools give solutions. We will use the Analytic Hierarchy Process in the production field and especially in the scheduling of a cardio vascular prosthesis production line. The initial parameterization of this method involves the evaluation of an expert. Although he has the required knowledge to make a fitting setup, he is no less human and he will bring even unintentionally a subjective part in his decision. The resulting scheduling will therefore not necessarily be optimal. The reduction of the subjectivity can be done using a metaheuristic method, of genetic algorithm type, to improve this parameterization by exploring neighbouring solutions compared to those proposed by the expert

Cette étude porte sur un dispositif qui pourrait permettre d’analyser la motivation et l’autonomie des étudiants en l’absence de régulation humaine dans un enseignement à distance. En effet dans la littérature, la motivation et l’autonomie ont une implication dans l’abandon des apprenants en situation d’apprentissage en ligne. Pour analyser ces facteurs, certains chercheurs utilisent de manière ponctuelle des questionnaires et d’autres utilisent des traces numériques produites par des EIAH (Environnements informatiques pour l'apprentissage humain). Dans la plupart de ces études l’intervention d’un tuteur pour réguler l’activité d’apprentissage est importante. L’objectif de cette recherche est d’arriver à identifier des étudiants pouvant suivre un enseignant à distance avec les meilleures chances de réussite. Pour ce faire, nous avons conçu un dispositif combinant l’exploitation de questionnaires et de traces numériques d’apprentissage. Ce dispositif contient une plateforme dénommée « Exoline » qui soutient un scénario pédagogique alternant le travail individuel et les activités collaboratives en sept étapes. Les activités collaboratives sont régulées par un système de vote (j’aime/je n’aime pas) de la plateforme et le travail individuel correspond à des phases de contribution éditoriale par chaque apprenant membre d’un groupe. Pour collecter les données relatives à la dynamique de collaboration et d’apprentissage, nous avons organisé une expérimentation avec 794 étudiants de l’Université de Kara avec un taux de participation de 40,55 %. Nous avons ensuite appliqué différentes méthodes statistiques aux données (questionnaires et traces) issues de l’expérimentation afin d’identifier et étudier les relations existantes entre l’apprentissage, la motivation et l’autonomie. Notre étude a mis en évidence, au-delà de la motivation initiale, le rôle de la dynamique de maintien de la motivation tout au long du processus d’apprentissage. Le niveau de progression (nombre d’étapes réalisées) par l’apprenant dans notre dispositif Exoline s’est révélé être un indicateur intéressant de la performance d’apprentissage. En d’autres termes, l’étude montre que la plupart des étudiants qui abandonnent le font plutôt en début de parcours. Sur un plan plus contextuel, notre étude montre aussi comment l’environnement socio-économique influence le parcours pédagogique des étudiants en particulier au Togo
This study concerns a mechanism that could make it possible to analyse students' motivation and autonomy in the absence of human regulation in distance education. Indeed, in the literature, motivation and autonomy have an implication in the drop-out of learners in e-learning situations. To analyze these factors, some researchers use questionnaires on an ad hoc basis and others use digital traces produced by TEL (Technology Enhanced Learning). In most of these studies, the intervention of a tutor to regulate learning activity is important. The objective of this research is to identify students who can follow a teacher from a distance with the best chances of success. To do this, we have designed a system that combines the use of questionnaires and digital learning traces. This system contains a platform called "Exoline" that supports a pedagogical scenario that alternates individual work and collaborative activities in seven steps. Collaborative activities are regulated by a voting system (I like/dislike) of the platform and individual work corresponds to phases of editorial contribution by each learner member of a group. To collect data on collaboration and learning dynamics, we conducted an experiment with 794 students from Kara University with a participation rate of 40.55%. We then applied different statistical methods to the data (questionnaires and traces) from the experiment to identify and study the relationships between learning, motivation and autonomy. Our study highlighted, beyond the initial motivation, the role of the dynamics of maintaining motivation throughout the learning process. The level of progression (number of steps performed) by the learner in our Exoline device has proven to be an interesting indicator of learning performance. In other words, the study shows that most students who drop out do so at the beginning of the course. On a more contextual level, our study also shows how the socioeconomic environment influences the educational path of students, particularly in Togo

Le contrôle des procédés représente un enjeu majeur pour les industries chimiques et pétrochimiques afin de garantir la qualité des produits, le contrôle des coûts, le maintien de la productivité et la maîtrise des risques. L'analyse menée directement au coeur des procédés constitue la voie la plus efficace. Cependant, dans la majorité des applications, les analyses élémentaires sont réalisées essentiellement en laboratoire et très rarement en ligne, par la mise en oeuvre de différentes technologies, le plus souvent lourdes et onéreuses. Ce travail de thèse s'inscrit dans le cadre d'un grand projet d'innovation qui couvre le champ de l'analyse élémentaire en ligne, domaine actuellement peu étudié. La technique d'analyse retenue est la spectrométrie LIBS en raison de sa rapidité et de son application à tout état de la matière sans préparation d'échantillon, ce qui lui offre un fort potentiel pour l'analyse en ligne. Cette technique est investiguée afin de réaliser des analyses en ligne d'éléments présents dans des matrices liquides : saumures, huiles silicone et produits pétroliers. L'optimisation des différents paramètres de mesure est réalisée et une approche d'optimisation s'appuyant sur un plan d'expériences est proposée. Différents modes d'échantillonnage de liquide et plusieurs montages LIBS sont étudiés afin de répondre aux problématiques évoquées. Enfin, une transposition au monde industriel est présentée avec le suivi du soufre en ligne dans des produits pétroliers sur un pilote industriel. Les résultats sont encourageants, mais la stabilité perfectible des mesures dans le temps implique d'explorer de nouvelles pistes d'amélioration
Process control is a major challenge for chemical and petrochemical industries so as to ensure product quality, cost control, sustainable productivity and risk management. To do so, carrying out the analysis directly at the core of the process is the most efficient way. However, for most applications, elemental analyzes are mainly performed in the laboratory and rarely on-line, which requires the implementation of different technologies, usually complex and expensive. This work is part of a large innovative project that covers the field of on-line elemental analysis, a research area still understudied to this day. The analytical technique selected here is the Laser Induced Breakdown Spectroscopy. Indeed, its speed and its capability to analyze all states of matter without sample preparation, gives it a great potential for on-line analysis. This technique is investigated in order to achieve on-line analysis of elements contained in various liquid matrices: brines, silicone oils and petroleum products. The optimization of different measurement parameters is performed, including an experimental design based approach. Different liquid sampling configurations and several LIBS setups are designed in order to tackle the issues encountered. Finally, a transposition to the industrial world is presented through on-line monitoring of sulfur in petroleum products on an industrial pilot process. The results are promising, but improving the stability of measurements over time still requires further research

Orientadores: Rubens Augusto Camargo Lamparelli, Jansle Vieira Rocha
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
Made available in DSpace on 2018-08-21T10:18:28Z (GMT). No. of bitstreams: 1 Silva_AriadinyMonteiroda_M.pdf: 9434848 bytes, checksum: d30404263245bbdf2d47047fdf5f0d26 (MD5) Previous issue date: 2012
Resumo: A palha é um dos principais subprodutos gerado no final do ciclo vegetativo da cana-deaçúcar. Ela tem um significado importante no contexto brasileiro dado que a partir dela podese gerar álcool e energia limpa, beneficiando o meio ambiente e a matriz energética. Assim é imprescindível aprofundar os estudos em torno da palha da cana e estimar a quantidade de resíduos produzidos ao final da colheita com o intuito de otimizar o processo de reaproveitamento desta. A lignina, celulose e hemicelulose, presentes na palha em grandes quantidades, são responsáveis pela estrutura fibrosa da cana-de-açúcar e é a partir deles que são dimensionados os processos de geração de energia (álcool e eletricidade). Neste contexto este trabalho teve o objetivo de utilizar o sensoriamento remoto para identificar estes componentes na cana-de-açúcar para subsidiar futuros levantamentos de estimativa de palha para fins energéticos e ambientais. Foram caracterizadas espectralmente 384 amostras de folhas de cana-de-açúcar, nas condições úmidas e secas, utilizando o espectroradiômetro FieldSpec Pro* com o intuito de identificar possíveis feições de absorções associadas aos componentes lignina, celulose e hemicelulose. Verificou-se que houve melhor discriminação das feições de absorção nas folhas secas, sendo que estas apresentaram valores de CAI e LCA superiores às folhas úmidas, pois 100% das amostras secas apresentaram valores de CAI positivos. O CAI foi o melhor estimador dos componentes se comparado ao LCA. As correlações entre CAI, LCA e NDVI permitiram a segregação/distinção entre as folhas nas condições úmidas e secas. E o CAI das palhas foi significativamente maior que o CAI do restante das folhas. Os resultados mostraram que nas feições visíveis próximo a 1730, 1780, 2100, 2270 e 2330 nm foram encontradas feições ligadas à lignina, hemicelulose e celulose e este estudo estudo permite concluir que as ferramentas do sensoriamento remoto podem ajudar como indicador de teores de lignina e celulose utilizando-se de índices de vegetação apropriados a estas finalidades, neste caso LCA e CAI, à luz dos novos programas espaciais de sensoriamento remoto hiperespectrais
Abstract: The straw is one of the main by-products generated at the end of the sugarcane vegetative cycle. It is significantly important in the Brazilian context, as alcohol and clean energy can be generated, thus benefiting the environment and the energy matrix. It is therefore essential to deepen the studies on the sugarcane straw and to estimate the amount of waste produced at the end of the harvest, in order to optimize its reuse process. Lignin, cellulose and hemicelluloses, present in the straw in large quantities, are responsible for the sugarcane fibrous structure; they enable to dimension the processes of energy generation (alcohol and electricity). The paper aimed to use remote sensing to identify these components in sugarcane in order to give support to future surveys on the use of straw for energy and environmental purposes. 384 samples of sugarcane leaf were characterized spectrally, in both wet and dry conditions, with the use of FieldSpec Pro* spectroradiometer, so as to identify possible absorption features associated with lignin, cellulose and hemicelluloses. There was better discrimination of the absorption features in the dried leaves, which showed higher values of LCA and CAI than the wet leaves, as 100% of the dried samples showed positive values of CAI. CAI was the best estimator of the components when compared to LCA. The correlations between CAI, LCA and NDVI allowed the segregation / distinction between the leaves in wet and dry conditions. The CAI of the straw was significantly higher than the CAI of the other leaves. The results showed that the visible features near 1730, 1780, 2100, 2270 and 2330 nm were found features linked to lignin, hemicellulose and cellulose and this study shows that remote sensing tools can help as an indicator of lignin and cellulose using vegetation index appropriate for these purposes, in which case LCA and CAI, the light of new space programs of hyperspectral remote sensing
Mestrado
Planejamento e Desenvolvimento Rural Sustentável
Mestra em Engenharia Agrícola

Nous avons étudié la rugosité et la dynamique de la ligne de contact d'un liquide visqueux sur un substrat désordonné. Sur des substrats présentant un désordre contrôlé avec une échelle caractéristique de 10 µm, nous avons trouvé que la rugosité de la ligne de contact ne dépend ni de la vitesse de la ligne, ni de la viscosité du liquide. L'exposant de rugosité zeta mesuré vaut 0,52±0,04, en désaccord avec les prédictions théoriques (zeta = 0,39). Nous avons donc testé les hypothèses du modèle. Une étude précise du mouvement de la ligne confirme l'hypothèse d'un mouvement quasi statique. En revanche, la dissipation n'est pas de type visqueux. Une simulation réaliste du problème montre que la non-linéarité en vitesse de la dissipation n'expliquent pas la valeur mesurée de zeta. Expérience et simulation montrent que la dynamique au voisinage du seuil de dépiégeage est contrôlée essentiellement par la dissipation à l'échelle microscopique, qui n'est pas universelle.

Pour faire face aux défis et la forte concurrence d’aujourd’hui, l’enseignement supérieur s’est tourné vers la stratégie de communication sur les réseaux sociaux en vue de fidéliser leur public, améliorer leur réputation et renforcer les relations avec la communauté à travers des niveaux d’engagement plus élevés. L’enjeu de cette thèse est d’appréhender cet engagement de la communauté universitaire sur les réseaux sociaux. La recherche s’intéressera dans un premier temps à l’étude des concepts clés reliés à son objectif, à savoir, l’engagement, la communauté et les médias sociaux. Des études empiriques quantitatives et qualitatives seront mises en œuvre par les méthodes du questionnaire et du data mining. Les résultats statistiques, l’analyse du contenu et la détection des communautés ont permis de comprendre le rôle que joue la stratégie contenu et l’impact du profil communautaire sur les niveaux d’engagement sur les publications créées par les principaux établissements d’enseignement supérieur au Liban
To face the challenges and strong competition of today, higher education has turned to the strategy of communication on social networks in order to retain their audience, improve their reputation and strengthen relations with the community through higher levels of engagement. The aim of this thesis is to understand this engagement of the university community on social networks. The research is initially interested in the study of key concepts related to its objective, namely, engagement, community and social media. Quantitative and qualitative empirical studies will be implemented using questionnaire and data mining methods. Statistical results, content analysis and community detection helped to understand the role of content strategy and the impact of community profile on engagement levels on posts created by major higher education institutions in Lebanon

Les mécanismes régulant la génération des différents types neuronaux du système nerveux pendant le développement des vertébrés sont encore mal connus. Au cours de cette thèse, la composition et l’organisation des clones de neurones générés par des cellules progénitrices rétiniennes (RPC) individuelles ont été étudiées chez le poulet avec la stratégie Brainbow. Celle-ci permet de marquer de façon permanente les RPC avec des combinaisons de couleurs distinctes pour suivre leur lignage. Des approches ont été développées pour : 1) déclencher le marquage Brainbow à différents stades de développement ou dans des RPC spécifiques ; 2) caractériser en 3D l’organisation cellulaire des clones rétiniens et identifier les types cellulaires générés. Une dispersion tangentielle inédite des RPC a été mise en évidence dans le neuroépithélium rétinien avant la phase de neurogenèse, conduisant à l’intercalation uniforme des clones. La composition des clones a été analysée pour comprendre si les RPC précoces pourraient être biaisées à générer certains types neuronaux et contribuer par leur intercalation à leur répartition régulière dans la rétine. Ce travail a permis l'étude des potentialités d’une population de progéniteurs neuraux et l’exploration des liens entre développement précoce et organisation d’un tissu par de nouvelles approches applicables à des problématiques variées
The mechanisms regulating the generation of the different types of neurons of the vertebrate nervous system during development are still poorly understood. In this thesis, the composition and organization of clones of neurons generated by retinal progenitor cells (RPCs) in chicken embryos were characterized with the Brainbow strategy. This technique enables to permanently label RPCs with distinct colour combinations in order to individually track their lineage. New approaches were developed to: 1) trigger Brainbow labels at different stages of development or in genetically identified RPCs; 2) characterize in 3D the organization of retinal clones and identify the neuronal types that they comprise. My results provide evidence for a previously uncharacterized phase of tangential dispersion of RPCs in the retinal neuroepithelium before neurogenesis, leading to uniform intercalation of retinal clones. The composition of these clones was analyzed to understand whether early RPCs could be biased to generate certain neural types and, through intercalation, contribute to their regular distribution in the retina. This study sheds light on the potentialities of a population of neural progenitors and on the possible links between the early development and mature cellular organization of a tissue through new approaches applicable to diverse problematics

Lignin, one of main components in the woody cell walls, is a complex heterogeneous biopolymer, which provides structural support and transportation of water in plants. It is highly recalcitrant to degradation (both chemically and environmentally) and protects cellulose from being degraded/hydrolyzed. Due to the structural complexity of native lignin, complete characterization and elucidation of lignin’s structure remains very challenging. The overarching goal of this work is to develop mass spectrometry based analytical methods to contribute to a better understanding of lignin structures. This dissertation will focus on the development and application of High-Resolution Accurate-Mass (HRAM) Mass Spectrometry (MS) as main analytical technique for studying lignin model compounds, including understanding the ionization behavior, studying corresponding fragmentation patterns and extracting structural information for structural elucidation eventually. Analytical methods were also developed to study the post-pretreatment products of the synthetic trimeric model compound using High-Performance Liquid Chromatography (HPLC) coupled with High-Resolution Accurate Mass (HRAM) Mass Spectrometry (MS). The first project of this dissertation focuses on mass spectral the characterization of lignin models from the in vitro oxidative coupling reactions. Three specific trimeric compounds were isolated and their ionization behaviors were investigated using HRAMMS via electrospray ionization (ESI). The reaction parameters of the in vitro oxidative coupling reaction were critical in alternating the linkage profiles of resulting dehydrogenation polymers (DHPs). Reaction parameters were tuned to obtain desired DHP linkages profile. Upon the isolation of three different trimeric compounds, a systematic comparison of ionization efficiency of three trimeric compounds was carried out using ESI-HRAM-MS under different ionization conditions. The second project was aimed to design a synthetic route for a lignin model compound that will be a good representation for native lignin during the pretreatment process. The model compound of interest has not been obtained previously through chemical synthesis. Due to the reactivity of cinnamyl alcohol, which contains the unsaturated side chain, this new synthesis strategy was developed based on the known aldol-type reaction route. A versatile synthesis procedure for preparation of β-O-4 oligomeric compounds was designed and implemented to include the most important functional groups (phenolic alcohol, aryl glycerol β-aryl ether bond and unsaturated side chain) in the resulting model compound. This new synthesis route also allowed incorporation of different monolignols. In the third project, Fenton chemistry was applied to a synthetic lignin model compound. Due to the non-specificity in the post pretreatment product profile, nontargeted analytical strategy was developed and applied to study the post-pretreatment products of the model compound using HPLC-HRMS. The results from this dissertation showed a significant difference in ionization behavior between three structurally different model compounds and indicated that primary structures of lignin compounds can largely affect corresponding electrospray ionization properties as well as fragmentation pattern. The work in this dissertation provides analytical techniques for non-targeted analysis of complex lignin samples and an insightful understanding of Fenton’s reaction pretreatment upon lignin model compound.

L'objet de cette etude consiste en la mise au point de methodes simples en vue de l'analyse et de la synthese de coupleurs hyperfrequences en technologie finline. Pour cela on propose des formules analytiques simples, destinees a la conception assistee par ordinateur (cao), qui ont ete mises au point a partir de resultats fournis par une methode d'analyse theorique (methode spectrale generalisee). La caracterisation propre a chaque type de coupleur est validee experimentalement et theoriquement lorsque cela est possible. On etudie particulierement: le coupleur en anneau; le coupleur hybride; le coupleur branch-line.

The present study investigates the thermochemical conversion of spruce wood and its extracted components by thermogravimetric analysis. The extracted components are two pulps, three xylan-lignin samples and one lignin sample; they were produced by the kraft cooking method with different cooking times. The study involves characterization of the biomass through proximate analysis and pyrolysis. A qualitative comparison between the thermal behaviours of the extracted components and wood is also performed. The study showed that the thermal behaviour of the biomass was highly influenced by the content of cellulose and lignin in the samples. Compounds rich in cellulose produced large quantities of volatiles and had a higher rate of pyrolysis compared to compounds rich in lignin, which produced more char and had a slower rate of pyrolysis. It was also shown that, the amount of char is not solely depending on the amount of the lignin; the structure of the compound also plays a role. On the other hand, the original wood sample showed some deviations regarding the trends in volatile and char production and these deviations were attributed to component interactions. Both cellulose and lignin rich compounds had an increase in thermal stability with increasing cooking time. For the pulps the increase in thermal stability is believed to be caused by increase in crystallinity, while for the lignin rich samples is believed to be caused by the increase in lignin content and structural changes in the compounds. The results also show that although changes are introduced in the cooking process, the extracted component still retain properties exhibited by the source biomass.

Cette thèse traite de l'identification des paramètres dynamiques des robots, en s'appuyant sur les méthodes d'identification en robotique, qui utilisent le modèle dynamique inverse, ou le modèle de puissance, ou le modèle d'énergie du robot. Ce travail revisite le modèle d'énergie en exploitant le caractère intégral des fonctions modulatrices appliquées au modèle de puissance du robot. En outre, les procédures d'intégration sont analysées dans le domaine fréquentiel, et certains groupes de fonctions modulatrices sont sélectionnés afin d'offrir un bon comportement de filtre passe-bas. Ensuite, l'introduction d'un différentiateur algèbrique récemment développé est proposé, nommé différentiateurs de Jacobi. L'analyse est effectuée dans le domaine temporel, et dans le domaine fréquenciel, ce qui met en évidence la propriété de filtrage passe bande et permet de sélectionner les paramètres des différentiateurs. Puis, ces différentiateurs sont appliqués avec succès à l'identification de robot, ce qui prouve leur bonne performance. Les comparaisons entre les différents modèles d'identification, les différenciateurs, les techniques des moindres carrés sont présentées et des conclusions sont tirées dans le domaine de l'identification de robot
This thesis discusses the identification issues of the robot dynamic parameters. Starting with the well-known inverse dynamic identification model, power and energy identification models for robots, it extends the identification model from an energy point of view, by integrating modulating functions with robot power model. This new identification model avoids the computation of acceleration data. As well, the integration procedures are analyzed in frequency domain so that certain groups of modulating functions are selected in order to offer a good low-pass filtering property. Then, a recently developed high order algebraic differentiator is proposed and studied, named Jacobi differentiators. The analyses are done in both the time domain and in the frequency domain, which gives a clear clue about the differentiator filtering property and about how to select the differentiator parameters. Comparisons among different identification models, differentiators, least square techniques are presented and conclusions are drawn in the robot identification issues

Dans cette thèse, nous proposons et évaluons des algorithmes pour résoudre des problèmes d'ordonnancement en ligne. Pendant des décennies, les études en ordonnancement considèrent des modèles déterministes où toutes les informations nécessaires pour la définition du problème sont supposées connues à l'avance. Cette hypothèse n'est généralement pas réaliste. Ceci a motivé les études sur l'ordonnancement en ligne. Dans un problème d'ordonnancement en ligne, un algorithme doit prendre des décisions sans connaissance du futur. L'analyse compétitive est généralement la méthode utilisée pour évaluer les performances de tels algorithmes. Dans cette analyse, la performance d'un algorithme en ligne est mesurée par le ratio compétitif qui est le ratio dans le pire cas entre la performance de la solution obtenue et celle d'une solution optimale hors ligne. Nous considérons principalement deux paradigmes en ligne: celui où les tâches se présentent dans la liste et celui où les tâches arrivent au fur et à mesure. Sur la base de ces deux paradigmes, nous considérons différents modèles : une seule machine, deux machines identiques parallèles, deux machines uniformes parallèles, batch machines et open shop. Pour chacun des problèmes, nous démontrons une borne inférieure de ratios compétitifs et proposons des algorithmes en ligne. Ensuite, nous évaluons la performance de ces algorithmes à l'aide de l'analyse compétitive. Pour certains problèmes, nous montrons que les algorithmes proposés sont optimaux dans le sens où le ratio compétitif est égal à la borne inférieure.

Cette thèse traite de la problématique de l'analyse automatique de tracés manuscrits réalisés à mains levée, à caractère géométrique et acquis en ligne. Lorsque l'on analyse un tracé en ligne, on peut le faire selon plusieurs angles. Comme pour les tracés hors ligne, on peu s'atteler à reconnaitre la forme produite. Mais le caractère en ligne de l'acquisition permet également d'autres niveaux d'analyse, comme l'analyse de la procédure utilisée par le dessinateur lors de la production de son dessin. Nous avons dans le cadre de ce travail élaboré des outils permettant de telles analyses de la production de tracé. Dans une première partie nous traitons des pré traitements à effectuer sur le tracé afin de pouvoir procéder aux analyses spatio-graphique et procédurale. Ces pré traitements sont le filtrage, la segmentation mixte à base d'arcs de cercles et de segments de droite, la sélection des points d'intérêt ainsi que l'identification de la nature de ces points. La seconde partie concerne l'analyse visuo-spatiale. Nous abordons alors deux aspects: la question de la reconnaissance des formes et celle de l'évaluation automatique de leur qualité. Notre contribution consiste en une méthode de reconnaissance basée sur l'apparence utilisant des descripteurs locaux. La dernière partie traite de l'analyse procédurale. Nous proposons une méthode d'extraction et de modélisation de la procédure mise en œuvre lors du dessin d'une forme. Nous montrons comment en utilisant cette modélisation, nous pouvons non seulement déterminer la procédure favorite d'un utilisateur mais également reconnaitre un dessinateur par l'analyse de sa procédure
This thesis handles the problem of the automatic analysis of online hand drawn geometric sketches. An online sketch can be analysed according to several points of view. As for offline sketching, we can try to recognize the produced shape. However, online sketching allows other levels of analysis. For example the analysis of the behavior of the drawer during the production of the sketch. In this thesis, we have tried to develop tools allowing a multi level analysis, including both shape and behavior analysis. The first part of our work deals with the pre treatments that must be performed on the sketch in order to allow upper level analysis. Those pre treatments are filtering, mixed segmentation and feature points detection and labelisation. In the second part, we approach shape analysis in two aspects: shape recognition and evaluation. We have developed a appearance based method which use local descriptors to allows both recognition and evaluation of the quality of a produced shape compared to the model . in the last part we propose a method for drawer's behavior extraction and modeling. Then we show how we can not only determine the favorite procedure of a drawer but also recognize the drawer by analyzing his behavior