Les biopiles enzymatiques miniatures représentent un potentiel important pour la future génération de dispositifs médicaux implantables, utilisés pour le diagnostic, le pronostic et le traitement. Ces derniers fonctionnent actuellement avec des sources d'énergie externes. Ces biopiles utilisant les molécules présentes dans les fluides biologiques sont des dispositifs médicaux prometteurs. Le glucose, qui est abondamment disponible dans le corps, est à l’étude comme biocarburant permettant de produire de l’énergie. Les enzymes utilisées pour produire l'énergie à partir des produits biochimiques sont immobilisées sur des électrodes en or par des médiateurs redox. Cependant, la faible puissance actuellement disponible et la sensibilité des enzymes à l'environnement limitent leur application in vivo. Malgré des recherches intensives, de nombreux problèmes restent à résoudre, notamment l'amélioration de la puissance, de la stabilité et de la biocompatibilité des biopiles.La réaction à corps étranger et l'isolement du dispositif médical par la formation d'une capsule fibreuse peuvent d'une part dénaturer les enzymes et, d'autre part, entraver la diffusion des analytes et de l'oxygène. Le travail décrit dans cette thèse vise à protéger les biopiles fonctionnant à base de glucose. Afin de résoudre les problèmes mentionnés ci-dessus, les hydrogels, actuellement développés pour diverses applications telles que l'administration de médicaments, l'ingénierie tissulaire et les dispositifs médicaux, offrent des propriétés prometteuses en tant que matériaux de revêtement.La première partie de la thèse est centrée sur l'évaluation de différents hydrogels injectables de faible poids moléculaire, en analysant à la fois la gélification in vitro et in vivo, la cinétique de dégradation, la réaction à corps étranger et l'angiogenèse. Les hydrogels présentent une dégradation lente et une intégration tissulaire optimale. Une angiogenèse accrue a été observée en raison de la libération d'une molécule pro-angiogénique pendant la dégradation de l'hydrogel.Dans la seconde partie de la thèse, l'un des hydrogels étudiés a été utilisé pour recouvrir l'électrode en or : le choix de l'enzyme a été basé sur des études de stabilité in vitro. En parallèle, le processus de revêtement a été optimisé, à la fois pour son uniformité et son épaisseur. Même si un revêtement plus épais présente l’avantage de protéger l’électrode contre la réaction à corps étranger, il est nécessaire de limiter l’épaisseur afin de maintenir une diffusion efficace des analytes et de l’oxygène.Les expériences en cours décrites dans la dernière partie de la thèse sont axées sur l'optimisation de l'implantation chez le rat et la mesure de l'activité des biopiles. De plus, les électrodes ont été connectées à une antenne pour établir une communication sans fil ; en effet, cela permettrait une mesure non invasive de l'activité enzymatique.En conclusion, ces travaux ont permis d'identifier un hydrogel pouvant être utilisé pour revêtir les électrodes de biopiles. Le sous-produit libéré lors de la biodégradation favorise l'angiogenèse au voisinage du matériau. Grâce à ce revêtement, on peut donc s'attendre à un échange accru d'analytes et d'oxygène, préalable indispensable à l'activité enzymatique. / Miniature enzymatic biofuel cells hold great potential to power the future generation of implantable medical devices, which are currently working on external power sources used for diagnosis, prognosis and treatment. Enzymatic biofuel cells appear to be promising in harvesting the energy from biochemicals present in physiological body fluids. Glucose, which is abundantly available in the body, is being explored as a biofuel to harvest energy. The enzymes employed to harvest the energy from the biochemicals are electrically wired on gold electrodes by redox mediators. However, the limitation of insufficient power, and the sensitivity of the enzymes towards host environment restrict their in vivo application. Despite several attempts, numerous challenges remain to be addressed such as improved current density, increased stability, and biocompatibility of enzymatic biofuel cells.Foreign body reaction and isolation of the medical device by formation of a fibrous capsule may firstly denature the enzymes, and secondly hinder the diffusion of analytes and oxygen. The work described in this thesis aims at protecting glucose based biofuel cells. As a strategy for combatting the bottlenecks mentioned above, hydrogels, currently developed for various applications such as drug delivery, tissue engineering, and medical device, offer promising properties as coating materials.The first part of the thesis is focused on evaluating different low molecular weight injectable hydrogels by analysing both in vitro and in vivo gel formation, degradation kinetics, foreign body reaction and angiogenesis. The hydrogels exhibit slow degradation, and optimal tissue integration. Enhanced angiogenesis was observed due to a pro-angiogenic molecule released during hydrogel degradation.In the second part of the thesis, one of the studied hydrogels was used to coat the gold electrode functionalised with enzyme: the selection of the enzyme was based on in vitro stability studies. In parallel, the process of coating was optimised, both for uniformity and thickness. Although a thicker coating should protect the electrode against foreign body reaction, it was necessary to limit the thickness in order to maintain an efficient analyte and oxygen diffusion.Ongoing experiments described in the last part of the thesis are focused on the optimisation of implantation in rat and measurement of the biofuel cell activity. In addition, the electrodes were connected to an antenna for wireless communication; indeed, such a device would allow for a non-invasive measurement of enzyme activity.To conclude, this work allowed for the identification of a hydrogel that can be used to coat the electrodes of biofuel cells. The byproduct released during the biodegradation favours angiogenesis in the vicinity of the material. Thanks to this coating, we can therefore expect an enhanced exchange of analytes and oxygen, which is a prerequisite for enzyme activity.

The goal of the Non-Traditional Agronomic Land (NTAL) Project is to develop sustainable, agronomic, crop growth methods that will allow biofuel feedstock production to occur on marginal or non-traditional plots of land, e.g., roadways, railroads, airports, and military installations. Recent economic feasibility models by Utah State University (USU) indicate these lands could, in theory, produce one billion gallons of economically viable new feedstock annually. Specifically, USU models show that if 60 % (600 pounds/acre) of dry land oilseed can be produced, maintenance costs of these NTALs can be recovered, as well as production of approximately 25 gallons/acre of renewable biodiesel. This feedstock yield would increase U.S. biodiesel production between 100- 200 %, and save federal and state agencies substantial financial resources. Preliminary impact considerations that have been taken into account for production on non-traditional land include: safety, structural integrity, economics, wildlife impacts, ecology/environmental impacts, water quality and grower concerns, soil quality, water use, generation/reduction of hazardous/toxic substances, air emissions, wastewater discharges, and reductions in use of pesticides and fertilizer. Canola and Safflower plots were established in 2007 and 2008 along roadsides in four different regions of the Utah I-15 corridor. Harsh climatic conditions with above average temperatures and below average precipitation existed in both years. Less than 50 % average yields for safflower and 25 % average yields for canola under normal climatic conditions were produced. Roadside plots all yielded under 200 pounds/acre of seed for both crops. In 2008, seeds were placed 2 inches deep during planting to position them closer to moisture, and no measureable yield was observed for any crops in control plots planted on traditional farmland and less than 10 pounds/acre in roadside plots. We found that it was not economical to grow oilseed crops for biodiesel production along Utah roadsides under the climatic conditions experienced during 2007- 2008 while using a Tye Pasture Pleaser No-Till Drill. (98 Pages)

Microalgae are a rich, largely untapped source of lipids. Algae are underutilized, in part, because lipid formation generally is stimulated by stress, such as nutrient deficiency. Nutrient deficiencies reduce growth, resulting in a tradeoff between elevated cellular lipids and abundant cell division. This tradeoff is not well understood. We also have a poor understanding of the physiological drivers for this lipid formation. Here we report on three sets of research: 1) Assessment of species differences in growth and lipid content tradeoffs with high and low level nitrogen deficiency; 2) Investigation of physiological drivers of lipid formation, by mass balance accounting of cellular nitrogen with progressing deficiency; 3) Examination of the effects of sodium chloride and silicon on lipid production in a marine diatom. 1) Nitrogen deficiency typically had disproportionate effects on growth and lipid content, with profound differences among species. Optimally balancing the tradeoff required a wide range in the rate of nitrogen supply to species. Some species grew first and then accumulated lipids, while other species grew and accumulated lipids concurrently--a characteristic that increased lipid productivity. High lipid content generally resulted from a response to minimal stress. 2) Commonalities among species in cellular nitrogen at the initiation of lipid accumulation provided insight into the physiological drivers for lipid accumulation in nitrogen deficient algae. Total nitrogen uptake and retention differed widely among species, but the ratio of minimum retained nitrogen to nitrogen at the initiation of lipid accumulation was consistent among species at 0.5 ± 0.04. This suggests that lipid accumulation was signaled by a common magnitude of nitrogen deficiency. Among the cellular pools of nitrogen at the initiation of lipid accumulation, the concentration of RNA and the protein to RNA ratio were most similar among species with averages of 3.2 ± 0.26 g L-1 (8.2% variation) and 16 ± 1.5 (9.2% variation), respectively. This implicates critical levels of these parameters as potential signals initiating the accumulation of lipids. 3) In a marine diatom, low levels of either sodium chloride or silicon resulted in at least 50% increases in lipid content. The synergy of simultaneous, moderate sodium chloride and silicon stress resulted in lipid content up to 73%. There was a strong sodium chloride/silicon interaction in total and ash-free dry mass densities that arose because low sodium chloride was inhibitory to growth, but the inhibition was overcome with excessive silicon supply. This suggests that low sodium chloride may have affected metabolism of silicon.

This study experimentally evaluated wheat straw slurry pipelines. Tests were conducted to determine the particle properties of the biomass mixed in water over time. The saturated particle density of 1,060kg/m3 was reached after 24 hours, while the saturated moisture contents of 78.5% and 79.5% were later reached for particle sizes of 1/8 and 3/4" respectively. A pipeline loop was redesigned to operate with 1/8, 1/4", and 3/4" straw particle slurries at up to 30% wet basis concentrations. The modifications allowed measurements of pressure loss through a length of pipe. These measurements which show the influences of drag reducing fibre suspension. Straw particles added to water lowered the pressure loss, by suppressing turbulence at lower concentrations or higher velocities. Additional straw further improved the result, until the maximum concentration was reached. High concentrations create plugs, increasing the pressure loss. Longer straw particles can further reduce losses, but have lower maximum concentrations. / Engineering Management

An increasing number of power plants in Scandinavia are beginning to use biofuel instead of coal or oil. The material in the new fuel is a mixture of woodchips, mostly Pine, Spruce and Salix, bark, GROT (tops and branches from felling waste) and sawdust from sawmills. It is heterogeneous, having a moisture content varying from 15% up to 65%. The moisture content affects the combustion of the fuel and therefore its commercial value. The industry is now interested in obtaining a method for measuring the moisture content of biofuel, quickly and reliably; preferably on delivery at the power plant. The measuring technique presented in this thesis is the first reported in the literature capable of measuring the moisture content of a large sample of such an heterogeneous material as biofuel. The equipment is today calibrated for a sample volume of 0.1 m3. A radio frequent signal is supplied from an antenna and penetrates the biofuel. Its reflection is modeled using partial least squares. As part of the work presented in this thesis, a new type of measuring rig and an analysis method for measurement of the moisture content of large samples of heterogeneous material have been developed. A statistical model for moisture content measurements of five different biofuel materials using radio waves has been built, having a root mean square error of prediction of 2.7. The interactions between biofuels and radio frequent signals have been demonstrated, indicating a variation of the reflection with varying types of biofuel material and variation in the reflection and delay of the signal with varying moisture content.

This thesis investigates, describes and understands the extensive process of technology commercialization. What stages there are, important aspects and implications. It is structured as a case analysis of project CHRISGAS development. CHRISGAS is a Swedish project, based in Värnamo, developing the technique of direct gasification of biomass to fuels. The work has its origin in the debate of the imminent climate changes, where society needs to reduce its reliance on fossil fuels. The automotive sector (particularly transport) is significantly reliant. However, current attempts to transition to biofuels have not completely succeeded. New, efficient technologies must be commercialized, and the technology of wood gasification is said to be particularly promising for launching the next generation of biofuels.

<p>The production of biodiesel (methyl esters) from vegetable oils represents analternative means of producing liquid fuels from biomass, and one which is growing rapidly in commercial importance and relevance due to increase in petroleum prices and the environmental advantages the process offers. Commercially, biodiesel is produced from vegetable oils, as well as from waste cooking oils and animal fats. These oils are typically composed of C14-C20 fatty acid triglycerides. In order to produce a fuel that is suitable for use in diesel engines, these triglycerides are usually converted into the respective mono alkyl esters by base-catalyzed transesterification with short chain alcohol, usually methanol. In the first part of this study, the transesterification reactions of three different vegetable oils / sunflower (SFO), soybean (SBO) and waste cooking oil (WCO) with methanol was studied using potassium hydroxide as catalyst in a conventional batch process. The production of biodiesel from waste cooking oil was also studied via continuous operation systems (employing the use of low frequency ultrasonic technology and the jet loop reactor). The characterisation of the feedstock used and the methyl ester products were determined by different analytical techniques such as gas chromatography (GC), high performance liquid chromatography (HPLC) and thin layer chromatography (TLC). The effects of different reaction parameters (catalyst amount, methanol to oil ratio, reaction temperature, reaction time) on methyl ester/FAME yield were studied and the optimum reaction conditions of the different process systems were determined. The optimum reaction conditions for production of methyl esters via the batch process with the fresh oil samples (SFO and SBO) were established as follows: a reaction time of 60 min at 60 &ordm / C with a methanol: oil ratio of 6:1 and 1.0 KOH % wt/wt of oil / while the optimum reaction conditions for the used oil (WCO) was observed at a reaction time of 90 min at 60 &ordm / C, methanol: oil ratio of 6:1 and 1.5% KOH wt/wt of oil. The optimum reaction conditions for the transesterification of the WCO via ultrasound technology applied in a continuous system in this study were: a reaction time of 30 min, 30 &ordm / C, 6:1 methanol/oil ratio and a 0.75 wt% (KOH) catalyst concentration. The ultrasound assisted transesterification reactions performed at optimum conditions on the different oil samples led to higher yields of methyl esters (96.8, 98.32 and 97.65 % for WCO, SFO and SBO respectively) compared to methyl esters yields (90, 95 and 96 % for WCO, SFO and SBO respectively) obtained when using conventional batch procedures. A considerable increase in yields of the methyl esters in the ultrasound assisted reaction process were obtained at room temperature, in a remarkably short time span (completed in 30 min) and with a lower amount of catalyst (0.75 wt % KOH) while the results from the continuous jet loop process system showed even better results, at an optimum reaction condition of 25 min of reaction, a methanol: oil ratio of 4:1 and a catalyst amount of 0.5 wt%. This new jet loop process allowed an added advantage of intense agitation for an efficient separation and adequate purification of the methyl esters phase at a reduced time of 30 min. The use of homogeneous catalysts in conventional processes poses many disadvantages / heterogeneous catalysts on the other hand are attractive on the basis that their use could enable the biodiesel production to be more readily performed as a continuous process resulting in low production costs. Consequently, a solid base catalyst (KNO3/FA) prepared from fly ash (obtained from Arnot coal power station, South Africa) and a new zeolite, FA/Na-X synthesized from the same fly ash were used as solid base catalysts in the transesterification reactions in the conversion of a variety of oil feedstock with methanol to methyl esters. Since fly ash is a waste product generated from the combustion of coal for power generation, its utilization in this manner would allow for its beneficiation (as a catalytic support material and raw material for zeolite synthesis) in an environmentally friendly way aimed at making the transesterification process reasonably viable. Arnot fly ash (AFA) was loaded with potassium (using potassium nitrate as precursor) via a wet impregnation method while the synthesized zeolite FA/Na-X was ion exchanged with potassium (using potassium acetate as precursor) to obtain the KNO3/FA and FA/K-X catalysts respectively. Several analytical techniques were applied for characterization purposes. The results of the XRD and XRF showed that the AFA predominantly contained some mineral phases such as quartz, mullite, calcite and lime. The high concentration of CaO in AFA was apparent to be beneficial for the use of fresh fly ash as a support material in the heterogeneous catalysed transesterification reactions. XRD characterisation of KNO3/FA results indicated that the structure of KNO3/FA gradually changed with the increase in KNO3 loading. The catalyst function was retained until the loading of KNO3 was over 10 %. IR spectra showed that the KNO3 was decomposed to K2O on the fly ash support during preparation at a calcination temperature of 500 &ordm / C. The CO2-TPD of the KNO3/FA catalysts showed that two basic catalytic sites were generated which were responsible for high catalytic abilities observed in the transesterification reactions of sunflower oil to methyl esters. On the other hand, XRD results for the as- received zeolite synthesized from AFA showed typical diffraction peaks of zeolite NaX. SEM images of the FA /NaX showed nano platelets unique morphology different from well known pyramidal octahedral shaped crystal formation of faujasite zeolites and the morphology of the FA /KX zeolite did not show any significant difference after ion exchange. The fly ash derived zeolite NaX (FA /NaX) exhibited a high surface area of 320 m2/g. The application of the KNO3/FA catalysts in the conversion reactions to produce methyl esters (biodiesel) via transesterification reactions revealed methyl ester yield of 87.5 % with 10 wt% KNO3 at optimum reaction conditions of methanol: oil ratio of 15:1, 5 h reaction time, catalyst amount of 15 g and reaction temperature 160 &deg / C, while with the use of the zeolite FA/K-X catalyst, a FAME yield of 83.53 % was obtained for 8 h using the ion exchanged Arnot fly ash zeolite NaX catalyst (FA/KX) at reaction conditions of methanol: oil ratio of 6:1, catalyst amount of 3 % wt/wt of oil and reaction temperature of 65 &ordm / C. Several studies have been carried out on the production of biodiesel using different heterogeneous catalysts but this study has been able to uniquely demonstrate the utilization of South African Class F AFA both as a catalyst support and as a raw material for zeolite synthesis / these catalyst materials subsequently applied sucessfully as solid base catalysts in the production of biodiesel.</p>

The risk of food insecurity in the form of higher food prices has prompted policymakers in the United States (US) and European Union (EU) to revise their approach to biofuel development. The US Renewable Fuel Standard (RFS) and EU Directive 2009/28/EC require long term use of renewable energy in transportation, subject to sustainability. This thesis examines the implications of the US RFS and EU Directive 2009/28/EC in a trade context using a partial equilibrium/comparative static framework. The focus is on the effect of the revised biofuels policies on opportunities for developing countries to supply the US and/or EU markets. For the US, the implications when the volume produced and/or required under the RFS is technologically infeasible with imports of ethanol as a potential policy alternative are explored. For the EU, the impact of the sustainability criteria on foreign biodiesel suppliers in terms of compliance cost is examined. In general, the US policy may enhance opportunities for trade while the EU policy will likely inhibit trade. A discussion of the implications of the mandates for developing countries and WTO is included.

Immobilization of photosynthetic cultures has been used to generate biofuels and high value compounds through direct conversion of CO2 and water using sunlight. Compared with suspended cultures, immobilized bacteria can achieve much higher densities resulting in greater areal productivity. Limitations exist however, on the density that can be reached without compromising access to light and other nutrients. In this thesis an optofluidic approach to overcoming the challenge of light delivery to high density cultures of cyanobacteria is described and proof of concept experiments presented. This approach uses optical waveguides to deliver light to cells through bacterial interaction with the evanescent field and is tailored to meet each cell's need for light and nutrients. Experiments presented here demonstrate biofilm proliferation in the presence of evanescent fields. Illumination of surfaces by surface plasmon enhanced evanescent fields is also shown to be an effective and potentially useful technique to grow biofilms within optofluidic architectures.

Botryococcus braunii (Chlorophyta, Botryococcaceae) is a colony-forming green microalga that produces large amounts of liquid hydrocarbons, which can be converted into transportation fuels. While B. braunii has been well studied for the chemistry of the hydrocarbon production, very little is known about the molecular biology of B. braunii. As such, this study developed both apparatus and techniques to culture B. braunii for use in the genetic and biochemical characterization. During genetic studies, the genome size was determined of a representative strain of each of the three races of B. braunii, A, B, and L, that are distinguished based on the type of hydrocarbon each produces. Flow cytometry analysis indicates that the A race, Yamanaka strain, of B. braunii has a genome size of 166.0 +/- 0.4 Mb, which is similar to the B race, Berkeley strain, with a genome size of 166 +/- 2.2 Mb, while the L race, Songkla Nakarin strain, has a substantially larger genome size at 211.3 +/- 1.7 Mb. Phylogenetic analysis with the nuclear small subunit (18S) rRNA and actin genes were used to classify multiple strains of A, B, and L races. These analyses suggest that the evolutionary relationship between B. braunii races is correlated with the type of liquid hydrocarbon they produce. Biochemical studies of B. braunii primarily focused on the B race, because it uniquely produces large amounts of botryococcenes that can be used as a fuel for internal combustion engines. C30 botryococcene is metabolized by methylation to generate intermediates of C31, C32, C33, and C34. Raman spectroscopy was used to characterize the structure of botryococcenes. The spectral region from 1600?1700 cm^-1 showed v(C=C) stretching bands specific for botryococcenes. Distinct botryococcene Raman bands at 1640 and 1647 cm^-1 were assigned to the stretching of the C=C bond in the botryococcene branch and the exomethylene C=C bonds produced by the methylations, respectively. A Raman band at 1670 cm^-1 was assigned to the backbone C=C bond stretching. Finally, confocal Raman microspectroscopy was used to map the presence and location of methylated botryococcenes within a living colony of B. braunii cells.