Добірка наукової літератури з теми "Pompe à carbone"

Palm oil mill effluent (POME) is high strength wastewater derived from processing of palm fruit. It is generated in large quantities in all oil palm producing nations where it is a strong pollutant amenable to microbial degradation being rich in organic carbon, nitrogen, and minerals. Valorization and treatment of POME with seven yeast isolates was studied under scalable conditions by using POME to produce value-added yeast biomass. POME was used as sole source of carbon and nitrogen and the fermentation was carried out at 150 rpm, 28 ± 2°C using an inoculum size of 1 mL of 106 cells. Yeasts were isolated from POME, dump site, and palm wine. The POME had chemical oxygen demand (COD) 114.8 gL−1, total solid 76 gL−1, total suspended solid (TSS) 44 gL−1 and total lipid 35.80 gL−1. Raw POME supported accumulation of 4.42 gL−1 dry yeast with amino acid content comparable or superior to the FAO/WHO standard for feed use SCP. Peak COD reduction (83%) was achieved with highest biomass accumulation in 96 h using Saccharomyces sp L31. POME can be used as carbon source with little or no supplementation to achieve waste-to-value by producing feed grade yeast with reduction in pollution potential.

Pengembangan produksi pertambangan nikel pada PT Z dilakukan untuk meningkatkan performa dari produksinya. Salah satu cara dari pengembangan ini adalah dengan optimasi saluran airnya. Air yang di salurkan ini di pompa menggunakan pompa sentrifugal yang ada pada pabrik proses aglomerasi. Pompa sentrifugal yang digunakan pada kasus ini juga menggunakan standar yang sesuai yaitu standar ASME B.73.1. Dalam menentukan spesifikasi pompa yang optimal untuk dipakai pada plant tersebut perlu dibuat Mechanical Data Sheet untuk mengetahui kebutuhan spesifikasi pompa yang akan dipakai pada industri. Dalam memenuhi datasheet ini perlu dilakukan perhitungan line sizing pipa, laju aliran air, head losses pompa, total dynamic head pompa, juga NPSHa nya dengan menyesuaikan ke standar ASME B73.1. Hasil perhitungan karakteristik pompa yang dihasilkan adalah pompa dengan laju aliran 86,74 gpm dengan total head losses 47,86 ft, total dynamic head sebesar 126,943 ft dan NPSHa 80,12 ft. Tipe Impeller pompa yang dipakai adalah Closed dan Tipe Mounting Foot. Material yang dipakai pada impeller dan casing pompa adalah Carbon Steel. Tipe Baseplate pompa adalah grouted.

Palm oil mill efluent (POME) is the major industrial waste water in Malaysia and Indonesia. The processing of (POME) before discharge is a major challenge to researchers. In this study, the adsorption experiment of zinc ion from (POME) produced from the processed palm oil as primary treatment has been investigated using coconut shell and cow bone activated carbon. Experiments were conducted at a fixed initial concentration, contact time, shaking speed and at different adsorbent dosage to obtain optimum condition for the uptake of zinc ion from POME. The coconut shell carbon exhibited better removal efficiency than the cow bone powder. The results obtained at fixed condition of pH 7, contact time of 105 minutes, shaking speed of 150 rpm showed more than 90% uptake for both adsorbents. The result of the adsorption study was further analyzed using Langmuir and BET model to determine the experimental isotherm. The result showed that equilibrium data fitted better with BET model for coconut shell carbon and better with Langmuir model for cow bone powder. The result of the adsorption experiments showed that heavy metal of zinc can be sufficiently reduced on both coconut shell carbon and the cow bone powder. The morphology of both adsorbents was observed using the scanning electron microscope (SEM), the pore sizes of the adsorbents supported the uptake of zinc ion from the raw POME.

POME is a kind of liquid waste produced by the crude palm oil industry. POME was not treated adequately, resulting in an issue for the environment owing to excessive levels of COD and BOD. Algae is a kind of bio-absorbent that may neutralize contaminants in liquid waste. Microalgae need carbon, nitrogen, and phosphorus-containing ingredients to flourish. These nutrients are necessary for photosynthetic carbon sources to be converted into biomass. POME includes a high concentration of C, N, and P; hence this research aims to investigate the potential of POME as a medium for the development of algae such as Spirulina, Nannochloropsis, and Chlorella. The experiment was carried out by varying the nutrients, water type, and time of nutrient feeding. Urea and sodium bicarbonate were the nutrition. Preparing the medium, culturing the microalgae, assessing biomass, counting the algae cells, and creating a calibration curve were the procedures in the experiment. The findings revealed that POME is the best medium for microalgae, that Spirulina grows better in POME than Chlorella and Nannochloropsis, and that providing nutrients every 2 days was better than introducing nutrients at the beginning and without adding nutrients.

Palm oil mill effluent (POME) contains approximately 6% fiber. The effectiveness of pre-treatment on POME can serve a very good feedstock for hydrogen production in fermentation process. In this research, the effectiveness of pre-treatment methods on POME treated using acid and base were analysed based total carbohydrate and reducing sugar content. By using 1M NaOH with heat treatment, 26.12% carbon source converted to reducing sugar while by using 1M H2SO4 with heat treatment, over 32.09% carbon source converted to reducing sugar. The highest increment of total carbohydrate where from acid-heat treatment with 26.1% increment from initial concentration. At the initial pH (5.5) with fermentation temperature 37°C, the highest hydrogen production rate given by acid-heat treatment was 0.5mL H2/mL POME. Different for initial pH 7.0 with the same temperature, the highest hydrogen produced rate was given by base-heat treatment with 0.59 mL H2/mL POME. The production of hydrogen in 2L bioreactor given much higher hydrogen production compare to production in serum bottle. This fermentation was run in batch mode with initial pH 7 and control at 5.5. The maximum hydrogen produce was 4304 mL H2/ L POME from acid-heat treatment.

Although Palm Oil Mill Effluent (POME) can be used as a raw material for biodiesel production, the POME contains an excessive amount of Free Fatty Acids (FFA), necessitating a preliminary process and esterification. POME is degummed using phosphate acid and bleached with carbon active. Additionally, this study used KOH-impregnated zeolite to reduce FFA. The purpose of this study is to determine the effect of adding impregnated zeolite on esterification. POME was heated to 600C for 30 minutes, then degumming with 3 % of phosphate acid for 30 minutes, followed by bleaching with carbon active with a comparison ratio of 8:3 at 1000C for 1 hour, and finally, esterification with 3 percent impregnated zeolite from the POME weight at 600C for 4 hours. The analysis was conducted using titration methods to determine the FFA of each esterification. The data will be compared between zeolite and non-zeolite degumming, bleaching, and esterification. The results indicated that the most effective method for reducing FFA was degumming, bleaching, and esterification with zeolite.

This paper presents the effect of different sizes of palm kernel shell (PKS) activated carbon as the carrier material in a micro-bioreactor system to treat the palm oil mill effluent (POME). Three different sizes of PKS activated carbon were used as the carrier material, i.e. 4.750 – 2.360 mm (large), 1.180 – 0.710 mm (average) and 0.425 – 0.300 mm (small). The systems were run for a total of 29 days under hydraulic retention time (HRT) of 24 hours. The performances of several effluent quality parameters of POME regarding the use of PKS activated carbon of different sizes were studied. PKS activated carbon with size 1.180 – 0.710 mm showed the highest removal performances for chemical oxygen demand (COD), ammoniacal-nitrogen (AN), and solids, with 41 %, 84.6 %, and 88 % of removal respectively. The system with PKS activated carbon of size 4.750 - 2.360 mm showed the highest performance in removing TP (45 %), while 1.180 – 0.710 mm size of PKS activated carbon showed the highest performance in removing TN (53 %). The system was also found to effectively reduce the effluent colour. In overall, the PKS activated carbon of size 1.180 – 0.710 mm showed the best results as a carrier material to be used in the micro-bioreactor system in treating POME compared to the other two sizes.

Palm Oill Mill Effluent is biomass produced in mill from processing palm oil mill. In this research, the structure and particle size of nano carbon particle from palm oill mill effluent (POME) have been succesfully using hydrothermal method. The characterization structure and particle size conducted by XRD, PSA, FTIR and UV-Vis, respectively. The single crystal of carbon structures in all peaks and average crystal size of 30.58 nm confirmed from XRD analysis. Then, PSA analysis informed that average particle sizes of nano carbon from palm oill mill effluent of 1.153 nm. Both analysis of structure and particle size have indicating of nano size from carbon particle synthesize from palm oil mill effluent. FTIR spectrum confirming that functional groups indicate that nanocarbons have been found in POME samples with luminescence generated from the surface state. The POME solution has been successfully converted into nanocarbon in the presence of blue fluorescence under UV light and has light absorption in the UV region at a peak of ~300 nm based from UV-Vis results.

Glutaredoxin (Grx) is a small, heat-stable protein acting as a multi-functional glutathione-dependent disulfide oxidoreductase. In this work, a gene encoding the monothiol glutaredoxin Grx4 was cloned from the genomic DNA of the fission yeast Schizosaccharomyces pombe. The determined DNA sequence carries 1706 bp, which is able to encode the putative 244 amino acid sequence of Grx with 27 099 Da. It does not contain an intron, and the sequence CGFS is found in the active site. Grx activity was increased 1.46-fold in S. pombe cells harboring the cloned Grx4 gene, indicating that the Grx4 gene is in vivo functioning. Although aluminum, cadmium, and hydrogen peroxide marginally enhanced the synthesis of β-galactosidase from the Grx4-lacZ fusion gene, NO-generating sodium nitroprusside (0.5 mmol/L and 1.0 mmol/L) and potassium chloride (0.2 mol/L and 0.5 mol/L) significantly enhanced it. The Grx4 mRNA level was also enhanced after the treatment with sodium nitroprusside and potassium chloride. The synthesis of β-galactosidase from the Grx4-lacZ gene was increased by fermentable carbon sources, such as glucose (lower than 2%) and sucrose, but not by nonfermentable carbon sources such as acetate and ethanol. The basal expression of the S. pombe Grx4 gene did not depend on the presence of Pap1. These results imply that the S. pombe monothiol Grx4 gene is genuinely functional and regulated by a variety of stresses.Key words: monothiol glutaredoxin, Pap1, regulation, Schizosaccharomyces pombe, stress response.

POME adalah suspensi koloid yang mengandung 95-96% air, 0,6-0,7% minyak dan 4-5% lemak dan padatan total. Pengolahan limbah POME dilakukan pengembangan dengan metode gabungan adsorpsi dan koagulasi. Penelitian ini bertujuan untuk mengetahui variasi konsentrasi karbon aktif dan koagulan terhadap penyisihan COD dan TSS dari Buangan Air pengolahan POME, merumuskan persamaan empiris hubungan optimasi campuran koagulan dan adsorber terhadap penyisihan COD dan TSS dengan variabel penelitian secara statistik dan menentukan kondisi optimum proses gabungan adsorpsi dan koagulasi terhadap pengurangan konsentrasi COD dan TSS yang dihasilkan. Bahan POME diukur terlebih dahulu nilai pH, TSS dan COD sebelum diberi perlakuan. Treatment POME dengan metode gabungan adsorpsi dan koagulasi dilakukan dengan menambahkan activated carbon (3; 6; 9 mg/L) dan PAC (0,2; 0,55; 0,9 mg/L) pada temperatur ruang (25°C) selama 20 menit untuk proses adsorpsi dan 1 menit untuk proses koagulasi. Waktu kontak berlangsung selama 30 menit, optimasi kondisi proses ditentukan dengan response surface methodology (RSM). Parameter yang diuji meliputi kadar TSS dan COD. Faktor yang paling berpengaruh signifikan terhadap respon COD adalah kadar activated carbon, dan faktor yang paling berpengaruh signifikan terhadap respon TSS adalah PAC. Metode kombinasi adsorpsi dan koagulasi dengan karbon aktif dan PAC mampu menyisihkan konsentrasi COD dan TSS lebih besar daripada menggunakan salah satu metode adsorpsi (karbon aktif) atau koagulasi (PAC) (non-kombinasi). Kondisi proses optimum diperoleh pada kadar activated carbon 9 mg/L dan PAC 0,69 mg/L dengan respon COD 430,272 mg/L dan TSS 297,941 mg/L.

La pompe à carbone biologique (PCB) joue un rôle central dans le cycle global du carbone océanique, en transportant le carbone de la surface vers les profondeurs et en le séquestrant pendant de longues périodes. Ce travail vise à analyser deux acteurs clés de la PCB : le zooplancton et les particules. Pour cela, nous utilisons les données d'imagerie in situ de l'Underwater Vision Profiler (UVP5) pour étudier deux axes principaux : 1) la distribution globale de la biomasse du zooplancton et 2) l'exportation de carbone dans le contexte d'une efflorescence printanière dans l'Atlantique Nord. À l'aide de l'UVP5 et de l'apprentissage automatique par le biais de modèles d'habitat utilisant des arbres de régression boostés, nous étudions la distribution mondiale de la biomasse du zooplancton et ses implications écologiques. Les résultats montrent des valeurs maximales de biomasse autour de 60°N et 55°S et des valeurs minimales au niveau des gyres océaniques, avec une biomasse globale dominée par les crustacés et les rhizaires. En utilisant des techniques d'apprentissage automatique sur des données globalement homogènes, cette étude fournit des informations sur la distribution de 19 grands groupes de zooplancton (1-50 mm de diamètre sphérique équivalent). Ce premier protocole permet d'estimer la biomasse du zooplancton et la composition de la communauté à l'échelle globale à partir d'observations d'imagerie in situ d'organismes individuels. Dans le contexte unique de la campagne EXPORTS 2021, nous analysons les données UVP5 obtenues par le déploiement de trois instruments dans un tourbillon à forte rétention. Après avoir regroupé les 1 720 914 images à l'aide de Morphocluster, un logiciel de classification semi-autonome, nous nous intéressons aux caractéristiques des particules marines, en étudiant leur morphologie à travers un cadre oblique qui suit un panache de particules entre la surface et 800 m. Les résultats montrent que, contrairement aux attentes, les agrégats deviennent de manière inattendue plus grands, plus denses, plus circulaires et plus complexes avec la profondeur. En revanche, l'évolution des pelottes fécales est plus hétérogène et façonnée par l'activité du zooplancton. Ces résultats remettent en question les attentes antérieures et appellent à une réévaluation de notre vision des agrégats et des pelottes fécales. Nous avons également étudié la dynamique des concentrations et des flux de carbone à l'aide d'un cadre 1D plus traditionnel dans lequel nous explorons les trois éléments clés de l'estimation des flux à partir d'imagerie in situ en comparant les estimations de l'UVP5 et des pièges à sédiments: la gamme de tailles couvertes, la vitesse de sédimentation et le contenu en carbone. Selon la littérature, les pièges à sédiments à flottabilité neutre (NBST) et les pièges attachés à la surface (STT) couvrent généralement une gamme de tailles allant de 10 µm à environ 2 mm. Dans notre étude, nous avons constaté qu'en élargissant la gamme de tailles de l'UVP5 à 10 µm et en la limitant à 2 mm, une comparaison plus consistante peut être faite entre le flux issu de l'UVP5 et celui des pièges à sédiments (obtenus par des collègues). Toutefois, il reste une contribution importante du flux au-dessus de ce seuil de taille qui nécessite une étude plus approfondie de ses implications par l'utilisation d'approches complémentaires telles que des pièges à sédiments avec des ouvertures plus grandes. Ce manuscrit ne fait pas seulement progresser nos connaissances, mais il aborde également des défis critiques dans l'estimation de la biomasse du zooplancton et de la dynamique des particules pendant les événements d'export. Les résultats de cette étude ouvrent de nouvelles voies pour la recherche future sur la PCB et approfondissent notre compréhension des écosystèmes marins
The biological carbon pump (BCP) plays a central role in the global ocean carbon cycle, transporting carbon from the surface to the deep ocean and sequestering it for long periods. This work aims to analyse two key players of the BCP: zooplankton and particles. To this end, we use in situ imaging data from the Underwater Vision Profiler (UVP5) to investigate two primary axes: 1) the global distribution of zooplankton biomass and 2) carbon export in the context of a North Atlantic spring bloom. Our objectives includes a quantification of global zooplankton biomass, enhancing our comprehension of the BCP via morphological analysis of particles, and assessing and comparing the gravitational flux of detrital particles during a the North Atlantic spring bloom using high-resolution UVP5 data. With the help of UVP5 imagery and machine learning through habitat models using boosted regression trees, we investigate the global distribution of zooplankton biomass and its ecological implications. The results show maximum zooplankton biomass values around 60°N and 55°S and minimum values within the oceanic gyres, with a global biomass dominated by crustaceans and rhizarians. By employing machine learning techniques on globally homogeneous data, this study provides taxonomical insights into the distribution of 19 large zooplankton groups (1-50 mm equivalent spherical diameter). This first protocol estimates global, spatially resolved zooplankton biomass and community composition from in situ imaging observations of individual organisms. In addition, within the unique context of the EXPORTS 2021 campaign, we analyse UVP5 data obtained by deploying three instruments in a highly retentive eddy. After clustering the 1,720,914 images using Morphocluster, a semi-autonomous classification software, we delve into the characteristics of the marine particles, studying their morphology through an oblique framework that follows a plume of detrital particles between the surface and 800 m depth. The results of the plume following approach show that, contrary to expectations, aggregates become unexpectedly larger, denser, more circular and more complex with depth. In contrast, the evolution of fecal pellets is more heterogeneous and shaped by zooplankton activity. Such results challenge previous expectations and may require a reassessment of our view of sinking aggregates and fecal pellets. We also studied concentration and carbon flux dynamics using a more traditional 1D framework where we explore the three key elements in flux estimation from in situ imaging data by comparing UVP5 and sediment trap flux estimates: size range covered, sinking rate and carbon content. According to the current literature, neutrally buoyant sediment traps (NBST) and surface-tethered traps (STT) usually cover a size range from 10 µm to approximately 2 mm. In our study, we have found that by expanding the UVP size range to 10 µm and limiting it to 2 mm, a more consistent comparison can be made between UVP5-generated flux and sediment trap fluxes (obtained by colleagues). However, it is worth noting that there remains a large flux contribution above this size threshold, necessitating further investigation of its implications through the use of complementary approaches such as the use of sediment traps with larger openings. This manuscript not only advances our knowledge, but also addresses critical challenges in estimating zooplankton biomass and particle dynamics during export events. The findings of this study open up new avenues for future research on the biological carbon pump and deepen our understanding of marine ecosystems

Ce travail concerne l'étude expérimentale et la modélisation d'une pompe à chaleur air/eau fonctionnant au gaz carbonique. L'étude expérimentale est réalisée sur un banc d'essais instrumenté (mesures de températures, pressions, débits, puissance) pour permettre de caractériser le fonctionnement de ces installations en régime statique et dynamique. Le modèle en régime statique est développé pour permettre, après validation, la détermination des conditions optimales de fonctionnement pour différentes sollicitations externes. Une loi simplifiée régissant la variation de la pression optimale de refoulement en fonction des conditions opératoires est déduite des calculs issus de ce modèle. Le modèle dynamique est basé sur les équations de conservation de la masse et de l'énergie. Il prend en compte l'inertie thermique du compresseur, des parois des échangeurs, du CO2 et du fluide caloporteur. La confrontation entre les résultats du calcul et ceux obtenus sur le banc d'essais met en évidence une bonne concordance. Cette modélisation a permis de simuler la variation des paramètres de fonctionnement de l'installation à la suite de sollicitations réalisées sur les variables d'entrée : température des sources, ouverture de la vanne de détente et vitesse de compresseur. En particulier, on note une bonne représentation des démarrages avec passage d'un fonctionnement sous-critique à un cycle transcritique
This work concerns an experimental study and modelling of an air/water beat pump using carbon dioxide as a working fluid. The experimental study is carried out on an instrumented test setup (pressure, temperature, flow end power measurements) to characterize the operation of this type of installation in static and dynamic mode. The static model was developed an validated. It allows to determine the optimal conditions of operation for various external conditions. Thus, a simplified law governing the optimal high pressure according to the gas cooler outlet temperature is deduced from the calculations. The dynamic model is based on the equations of mass and energy conservation. It takes into account the thermal inertia on the compressor, the exchanger' s walls, the refrigerant (carbon dioxide) and the coolant (water). Comparison between modelling results and those obtained with the test stand gives a good agreement. Thanks to this model, it is possible to record the operating variables versus time and space after changing the input parameters such as sources temperatures, expansion valve opening and compressor rotating speed. In particular, we notice a good representation of starting process with a transition from subcritical to transcritical cycle

Cette thèse est consacrée à l'étude des propriétés optiques des nanotubes de carbone mono-paroi.
Dans un premier temps, la spectroscopie d'absorption a été utilisée comme un outil de caractérisation des différents échantillons. En effet, l'énergie de la transition entre la première paire de singularités de Van-Hove étant proportionnelle à l'inverse du diamètre, la spectroscopie d'absorption donne une mesure du diamètre moyen ainsi que de la largeur de la distribution en diamètre.
Nous avons étudié les conditions d'observation d'un signal de photoluminescence au niveau du gap des nanotubes semi-conducteurs. Pour observer ce signal, les nanotubes doivent être isolés, en les mettant convenablement en suspension par exemple. Les expériences de photoluminescence sélective en longueur d'onde ont montré que les structures observées dans les spectres peuvent être attribuées aux différentes chiralités présentes dans l'échantillon. Elles ont également permis d'évaluer la largeur homogène de la transition fondamentale (environ 20 meV). Enfin, la spectroscopie d'excitation de la photoluminescence a permis de déterminer la chiralité des différents nanotubes présents dans nos échantillons.
Dans un deuxième temps, la dynamique des porteurs de charge dans les nanotubes de carbone a été étudiée à l'aide d'expériences de type pompe-sonde. Cette étude réalisée sur des nanotubes déposés sur un substrat et agrégés en corde a montré l'existence d'un couplage tunnel entre les nanotubes semi-conducteurs et les nanotubes métalliques au sein d'une corde. L'existence de ce couplage ainsi que la brièveté des temps de relaxation (picoseconde) expliquent l'absence de signal de photoluminescence sur ce type d'échantillon. La comparaison faite avec les données obtenues sur les échantillons de nanotubes isolés montre une augmentation d'un ordre de grandeur des temps de relaxation, ce qui est en accord avec l'apparition d'un signal de photoluminescence observable sur ces échantillons. L'étude de la réponse non-linéaire hors résonance a mis en évidence la dynamique du plasmon de surface des nanotubes. Elle a également permis d'interpréter le fond d'absorption sur lequel sont superposées les raies dues aux transitions inter-bandes comme la queue basse énergie de la résonance plasmon de surface. Enfin, la susceptibilité non-linéaire d'ordre trois des nanotubes a pu être évaluée. La comparaison entre le facteur de mérite des nanotubes et celui d'autres matériaux étudiés en vue d'une application en optique non-linéaire a montré que les nanotubes de carbone semblent posséder des propriétés intéressantes pour ce type d'applications.

Les foraminifères planctoniques (FP) sont des organismes hétérotrophes appartenant au mésozooplancton, abondants dans tous les domaines marins et communément utilisés dans les reconstitutions paléoenvironnementales. Pour quantifier la position des FP dans le cycle du carbone au sein du plancton à des échelles régionales et globales, il est nécessaire de connaitre leur production en biomasse (Corg), jusque là très peu connue car très difficilement mesurable. Dans ce travail, nous avons développé une nouvelle méthode analytique non destructive développée à partir de la méthode bicinchoninic acid (BCA), et mesuré la biomasse individuelle de 952 spécimens de 26 espèces de FP provenant de régions tempérées à subtropicales. Nos résultats indiquent que la biomasse moyenne d'un FP s'élève à 0,845 μg. Le protocole a été calibré sur l'espèce benthique Ammonia tepida, et au cours d'expériences en culture. L'analyse statistique des données ne fait ressortir aucune différence interspécifique, ni des conditions écologiques (niveau trophique, profondeur ou température). En revanche, nous avons démontré que la biomasse des FP est fortement corrélée avec la masse et la taille de leur test calcitique. Grâce à cette corrélation, les biomasses des populations de FP ont été calculées pour 1128 sites et profondeurs d'échantillonnage de l'Atlantique Nord, la mer d'Arabie, la mer Rouge, les Caraïbes, le Japon et l'Oregon. La production actuelle de biomasse par les FP a pu être estimée entre 25 et 100 Tg.C.an−1, en incluant les individus juvéniles. Le ratio carbone organique sur inorganique (Corg : Cinorg) des populations de FP entre la surface et 2500 m de profondeur semble rester constant à ~2/3, tel que montré dans la zone des Açores. Ces résultats prouvent qu'il y a un export de carbone à la fois organique et inorganique, et que les FP contribuent incontestablement à la pompe biologique de carbone. Les résultats obtenus au cours de cette thèse font des FP de potentiels outils pour quantifier la biomasse initiale de paléo-assemblages, et améliorer notre compréhension du cycle du carbone et de la pompe biologique de carbone dans le passé.

L’objectif principal de cette thèse est de mieux comprendre les différents facteurs contrôlant la pompe biologique de carbone en Atlantique Nord et dans l’Océan Austral, à proximité des îles Kerguelen, en utilisant notamment deux approches: le Thorium-234 (234Th) et le baryum biogénique (Baxs).En Atlantique Nord, les flux d’export de carbone organique particulaire (POC) augmentent lorsqu’ils sont associés à des minéraux biogéniques (silice biogénique et carbonate de calcium) et lithogènes, capable de lester les particules. L’efficacité d’export, généralement plus faible que précédemment supposé (< 10%), est inversement corrélée à la production, soulignant un décalage temporel entre production et export. La plus forte efficacité de transfert, i.e. la fraction de POC atteignant 400m, est reliée à des particules lestées par du carbonate de calcium ou des minéraux lithogènes.Les flux de reminéralisation mésopélagique sont similaires ou parfois supérieurs aux flux d’exports et dépendent de l’intensité du développement phytoplanctonique, de la structure en taille, des communautés phytoplanctoniques et des processus physiques (advection verticale).Comme observé pour le POC, l’export des éléments traces est influencé par les particules lithogènes provenant des marges océaniques, mais aussi des différentes espèces phytoplanctoniques.Dans l’Océan Austral, la zone à proximité de l’île de Kerguelen est naturellement fertilisée en fer, augmentant les flux d’export de fer, d’azote et de silice biogénique. Il a été démontré que la variabilité des flux dépendait des communautés phytoplanctoniques dans la zone fertilisée
The main objective of this thesis is to improve our understanding of the different controls that affect the oceanic biological carbon pump. Particulate export and remineralization fluxes were investigated using the thorium-234 (234Th) and biogenic barium (Baxs) proxies.In the North Atlantic, the highest particulate organic carbon (POC) export fluxes were associated to biogenic (biogenic silica or calcium carbonate) and lithogenic minerals, ballasting the particles.Export efficiency was generally low (< 10%) and inversely related to primary production, highlighting a phase lag between production and export. The highest transfer efficiencies, i.e. the fraction of POC that reached 400m, were driven by sinking particles ballasted by calcite or lithogenic minerals.The regional variation of mesopelagic remineralization was attributed to changes in bloom intensity, phytoplankton cell size, community structure and physical forcing (downwelling). Carbon remineralization balanced, or even exceeded, POC export, highlighting the impact of mesopelagic remineralization on the biological pump with a near-zero, deep carbon sequestration for spring 2014.Export of trace metals appeared strongly influenced by lithogenic material advected from the margins. However, at open ocean stations not influenced by lithogenic matter, trace metal export rather depended on phytoplankton activity and biomass.A last part of this work focused on export of biogenic silica, particulate nitrogen and iron near the Kerguelen Island. This area is characterized by a natural iron-fertilization that increases export fluxes. Inside the fertilized area, flux variability is related to phytoplankton community composition

L’intégration des communications optiques sur puce offre de vastes promesses en termes de performances et de réduction de la puissance consommée, les canaux optiques ne souffrant pas des nombreuses limitations des canaux métalliques. De plus, l’information codée optiquement permet d’atteindre des débits de données élevés par le biais du multiplexage en longueur d’onde. Afin de conserver la compatibilité avec les composants électroniques, les communications et composants optiques doivent s’intégrer dans la filière silicium. Cependant, ce dernier matériau ne permet pas d’envisager la réalisation de certaines fonctions optiques, en particulier la source laser. D’autres matériaux doivent ainsi être intégrés pour suppléer au silicium. Mes travaux de thèse portent sur l’intégration de nanotubes de carbone sur plate-forme silicium pour la photonique. Dans ces travaux, le potentiel des nanotubes de carbone pour la réalisation de sources optiques intégrées est exploré. Dans un premier temps, je proposerai des pistes de compréhension de l’apparition du gain optique dans les nanotubes de carbone semiconducteurs par analyse des temps de vie des excitons, mesurés en spectroscopie pompe-sonde. Ces temps de vie sont sensiblement rallongés lorsque la centrifugation des nanotubes de carbone, au cours de l’extraction, est poussée à des vélocités et des temps plus longs. Une explication envisagée est la réduction du nombre de défauts à la surface des nanotubes, ces défauts se comportant comme des centres de recombinaison non-radiatifs. D’autre part, une méthode efficace d’intégration des nanotubes de carbone sur guide d’onde silicium a été proposée. Cette méthode robuste et permet d’observer le couplage de la photoluminescence des nanotubes de carbone avec le mode optique du guide d’onde. Afin d’obtenir une interaction exaltée entre mode optique et nanotube de carbone, le couplage entre les nanotubes et différentes cavités photoniques, incluant microdisques, cavités Fabry-Pérot et micro-résonateurs en anneau, a été étudié. L’emploi en particulier de résonateurs en anneau permet d’observer la structuration de la photoluminescence des nanotubes de carbone par les modes de résonance de l’anneau. Différentes configurations ont été étudiées afin de compléter la compréhension des mécanismes de couplage : micro-photoluminescence, photoluminescence guidée et photoluminescence intégrée
On-chip optical communication may increase drastically performances and consumption of communication systems. Indeed, optical channels do not face limitations that metallics interconnects do. Even better would be the achievable data rate due to the multiplexing possibility in optics. In order to keep compatibility with electronic devices, optical components and interconnects should be built in silicon. However, this material is not suitable for some optical function, such as laser sources. Thus, there is a need to integrate alternative materials to compensate for silicon weaknesses. My PhD work focuses on integration of carbon nanotube on silicon for photonics applications. In this work, potential use of carbon nanotube for light emission function is investigated. First, I will propose clue to understand the appearance of optical gain in semiconducting carbon nanotube. Such investigation is done by mean of pump-probe experiments, where the excitons lifetimes are measured. Those lifetimes slightly increase while centrifugation time and speed is increased, during the extraction process. A possible explanation is that defect-free carbon nanotubes are selected by the centrifugation process. In parallel, I worked on designing an efficient method to couple nanotubes photoluminescence with silicon waveguides. This method appears to be quite robust, and allows to observe coupling between the nanotube photoluminescence and the optical mode of the waveguide. In order to obtain a more intense interaction between the optical mode and carbon nanotubes, I investigated the coupling between carbon nanotubes and several photonic cavities, including microdisks, Fabry-Pérot cavities and ring resonators. Specifically, ring resonators allow to measure the photoluminescence of carbon nanotube structured by the resonant modes. Several configurations are studied to understand more in-depth the coupling mechanisms: micro-photoluminescence, guided photoluminescence and integrated photoluminescence

Les nanotubes de carbone dont les deux tiers sont des semi-conducteurs à gap direct, ont des propriétés optiques originales dominées par le caractère undimensionel du confinement quantique imposé aux électrons. Ceci donne naissance à des excitons très fortement liés dont nous avons étudié la structure fine par des techniques de photoluminescence et de diffusion Rayleigh. Par ailleurs, l'étude de la dynamique des excitations élémentaires (à l'échelle sub-pico-seconde), nous a permis de mettre en évidence le rôle prépondérant des interactions avec l'environnement sur les propriétés de ces objets dont tous les atomes sont en surface. Dans une dernière partie, nous montrons comment tirer partie de cette interaction en fonctionnalisant les nanotubes avec des chromophores organiques dans le but de réaliser des dispositifs opto-électroniques de conversion d'énergie lumineuse.

Les cycles océaniques du carbone et des principaux nutriments sont mal connus car ils sont affectés par de nombreux puits et sources physiques, chimiques ou biologiques difficiles à estimer par des mesures directes. Une manière de mieux contraindre ces processus importants est d’utiliser l’information contenue dans des traceurs plus simples : les proxies. Le radium 228 (228Ra), émis par les plateaux continentaux, est utilisé comme proxy des flux d’eau et d’éléments minéraux de la côte vers l’océan ouvert. Il permet en particulier d’estimer les flux d’eau souterraine ou SGDs (Submarine Groundwater Discharge). Le thorium 234(234Th), insoluble, permet quant à lui de contraindre la dynamique des particules par lesquelles il est adsorbé. Il est régulièrement utilisé pour estimer la pompe biologique du carbone (PBC), c’est-à-dire le flux de carbone de la surface vers l’océan profond.Au cours de cette thèse, un modèle numérique à une résolution de 2° a été construit pour chacun de ces deux radio-isotopes, en s’appuyant sur la circulation du modèle NEMO-OPA et les champs de particules du modèle PISCES. Plusieurs paramètres inconnus des modèles ont été contraints par des observations dans le cadre d’une méthode inverse.La modélisation inverse du 228Ra a permis d’estimer les flux de 228Ra venant de 38 régions côtières. En revanche, l’estimation des SGDs est imprécise, car les SGDs sont difficiles à distinguer d’une autre source de 228Ra: la diffusion par les sédiments.La modélisation inverse du 234Th a permis d’estimer les coefficients de partage du 234Th, qui représentent l’affinité de différents types de particules pour cet isotope. Elle a aussi permis d’estimer les erreurs associées à quelques simplifications courantes dans les études de la PBC fondées sur le 234Th
The oceanic cycles of carbon and the main nutrients are poorly known since they are affected by many physical, chemical or biological sources and sinks that are difficult to estimate by direct measurements.One way to better constrain these important processes is to use the information contained in more simple tracers called "proxies". As radium 228 (228Ra) flows from the continental shelves, it is used as a proxy of water and mineral elements fluxes from the coast to the open ocean. In particular, it is often used to estimate the SGD (Submarine Groundwater Discharge). For its part, thorium 234 (234Th), an insoluble radio-isotope, is used to constrain the dynamics of the solid particles onto which it is adsorbed. The carbon flux from the surface to the deep ocean, called "biological carbon pump" (BCP), is often estimated by a 234Th-based method.During this PhD, a numerical model with a resolution of 2°, based on the circulation of the NEMO-OPA model and the particle fields of the PISCES model, was built for each of the two radioisotopes.Several unknown model parameters were constrained by observations using an inverse technique.The inverse modeling of 228Ra was used to constrain 228Ra fluxes from 38 coastal regions.However, the SGD fluxes are poorly constrained by this method, because SGD can be confused with another source of 228Ra: diffusion from sediments.The inverse modeling of 234Th produced estimates of partition coefficients, representing the affinity of different particle types for this isotope. It was also used to estimate the errors associated with some common simplifications made in 234Th-based BCP studies

Ces travaux portent sur le rôle du fer dans le contrôle de la pompe biologique de CO2 de l'Océan Austral. Le fer est en effet un micro-nutriment essentiel à la vie et de nombreuses expériences ont montré qu'en raison de ses concentrations subnanomolaires dans la colonne d'eau océanique, il est l'un des éléments limitants de la production primaire dans diverses régions océaniques, dont l'Océan Austral. La thèse a été menée suivant deux approches complémentaires : une approche géochimique et une approche biogéochimique. La partie géochimique a pour but une meilleure compréhension du cycle géochimique du fer dans l'océan. Elle présente des mesures en fer et manganèse dissous réalisées dans le sillage des Iles Kerguelen (Bucciarelli et al. 2001), et des mesures en fer dissous et fer total soluble réalisées dans l'Océan Austral ouvert (Bassin de Crozet). Ces prélèvements ont été effectués au cours des missions océanographiques Antares 3 (sillage des Iles Kerguelen) et Antares 4 (Bassin de Crozet) dans le cadre du programme Antares (France JGOFS). Ces données ont permis d'étudier les sources et les puits de fer dans le secteur Indien de l'Océan Austral considéré. La partie biogéochimique est axée sur les effets de la limitation par le fer sur des communautés phytoplanctoniques naturelles d'une part (Blain et al. 2001, Blain et al. 2002, Sedwick et al. 2002), et sur des cultures monospécifiques de trois diatomées, menées en laboratoire, d'autre part. Un découplage des cycles du carbone, de l'azote et du silicium en conditions de carence en fer a été montré, et quantifié pour des concentrations en fer dans le milieu variant de conditions limitantes à des conditions non limitantes
This work concerns the role played by iron in controlling the CO2 biological pump in the Southern Ocean. Iron, indeed, is a micro-nutrient essential to life and numerous experiments have shown that its subnanomolar concentrations in the water column (co)-limited the primary production in various oceanic areas, e. G. In the Southern Ocean. The thesis is divided in two complementary parts, a geochemical part and a biogeochemical one. The geochemical part aims at a better understanding of the oceanic geochemical cycle of iron. It presents measurements of dissolved iron and manganese in the wake of the Kerguelen Islands (Bucciarelli et al. 2001) and of dissolved and total dissolvable iron in the open Southern Ocean (Crozet basin). The samplings were conducted as part of the Antares program (France JGOFS), during the Antares 3 cruise in the wake of the Kerguelen island, and during the Antares 4 cruise in the Crozet Basin. The data give insigths into the sources and sinks of iron in the Indian sector of the Southern Ocean. The biogeochemical part focuses on the effects of iron stress on natural phytoplanktonic community on one hand (Blain et al. 2001, Blain et al. 2002, Sedwick et al. 2002), and on laboratory monospecific cultures of three species of diatoms on the other hand. A decoupling between the cycles of silicon, carbon and nitrogen has been shown under iron stress conditions. The decoupling is quantified in a range of iron concentrations varying from iron-limiting to iron-sufficient conditions

Much of our present knowledge of the architecture of molecules has been obtained from studies of the diffraction of X rays or neutrons by crystals. X rays are scattered by the electrons of atoms and ions, and the interference between the X rays scattered by the different atoms or ions. in a crystal can result in a diffraction pattern. Similarly, neutrons are scattered by the nuclei of atoms. Measurements on a crystal diffraction pattern can lead to information on the arrangement of atoms or ions within the crystal. This is the experimental technique to be described in this book. X-ray diffraction was first used to establish the three-dimensional arrangement of atoms in a crystal by William Lawrence Bragg in 1913 (Bragg, 1913), shortly after Wilhelm Conrad Röntgen had discovered X rays and Max von Laue had shown in 1912 that these X rays could be diffracted by crystals (Röntgen, 1895; Friedrich et al., 1912). Later, in 1927 and 1936 respectively, it was also shown that electrons and neutrons could be diffracted by crystals (Davisson and Germer, 1927; von Halban and Preiswerk, 1936; Mitchell and Powers, 1936). Bragg found from X-ray diffraction studies that, in crystals of sodium chloride, each sodium is surrounded by six equidistant chlorines and each chlorine by six equidistant sodiums. No discrete molecules of NaCl were found and therefore Bragg surmised that the crystal consisted of sodium ions and chloride ions rather than individual (noncharged) atoms (Bragg, 1913); this had been predicted earlier by William Barlow and William Jackson Pope (Barlow and Pope, 1907), but had not, prior to the research of the Braggs, been demonstrated experimentally. A decade and a half later, in 1928, Kathleen Lonsdale used X-ray diffraction methods to show that the benzene ring is a flat regular hexagon in which all carbon–carbon bonds are equal in length, rather than a ring structure that contains alternating single and double bonds (Lonsdale, 1928).Her experimental result, later confirmed by spectroscopic studies (Stoicheff, 1954), was of great significance in chemistry.

Criminal poisonings with lead compounds are noteworthy because of their rarity. Indeed a person intent on poisoning someone would be unlikely to choose lead because of its uncertainty of action. Nevertheless there were murders in which it was used, such as the killing of Thomas Taylor in September 1858, when white lead was the poison, and the murder of Mary Ann Tregillis in 1882, when lead acetate was used. This salt was also the agent in the attempted murder of Honora Turner also in 1858. The lead compound that killed Pope Clement II in 1047 can only be speculated on. The inquest into the death of Thomas Taylor, which was held by the coroner for Gloucestershire on 27 September 1858, was reported in the November issue of the Pharmaceutical Journal because it was an unusual case of death by poisoning with lead carbonate. Thomas lived in Gloucestershire with his wife, Ann, and the child that he had fathered by another woman. He also had a brother, Charles, who had recently been released from prison and who had gone to live with the Taylors. It was not long before quarrels broke out between Thomas and his wife, whom he accused of being too affectionate towards Charles. In fact Ann was more than affectionate; she openly stated that she preferred brother Charles and wished her husband was dead. Her wish was to be granted. In August 1858 Thomas was seized with violent pains in his stomach which lasted for several days and for which he sought medical treatment. The doctor gave him some opium pills to kill the pain and senna water to act as a laxative. When these failed to cure him his doctor prescribed larger doses which he said could be obtained from his surgery. However, the doctor noticed that when his wife Ann went to collect more senna water she brought along a bottle that had contained the original medicine and that the dregs of the first dose were now a different colour and it tasted odd. Thomas died on 4 September, but the doctor was sufficiently suspicious of the cause of death that he refused to issue a death certificate until he and a surgeon friend of his had carried out a post-mortem.

Palm Oil Methyl Ester (POME) is a very promising alternative renewable biofuel. This is because it has a better cetane number and a comparable lower calorific value with respect to its competitors. However, due to difference in molecular composition and hence dissimilar properties, it does not perform proficiently in diesel engine with standard design and operating parameters. Therefore, a study is arranged to realize the effect of compression ratio variation on POME run in diesel engine. The load is varied from ‘no load’ to ‘full load’ with six equal intervals. During this study, standard diesel injection timing is maintained unaffected. The study conveys that at higher compression ratio, POME causes reduction in brake fuel consumption and thereby increases the engine efficiency. The increase in compression ratio also causes smoother combustion, lower ignition delay with early heat release than diesel operation. The detrimental emission quantities in the form of carbon monoxide, oxides of nitrogen and hydrocarbon emissions are also cut down with presence of POME in the diesel engine at high compression ratio. Thus, POME can be regarded as a good alternative fuel for diesel engine for locomotive applications.

Palm oil methyl ester (POME) produced from crude palm oil have some excellent properties which makes it a feasible alternative to diesel fuel. However, its higher oxygen content makes it nitrogen oxide emission prone when burned in diesel engines. This problem can be resolved by emulsifying POME with distilled water in the presence of suitable surfactant. Two phase water in oil emulsion is prepared by using ultrasonic bath sonication. SPAN 80, a lipophilic surfactant is used for 1% by volume to prepare the emulsion. Water quantity in the emulsion is varied by 5% and 10% by volume and stability study is performed. It is found that emulsion with 5% water is more stable. Thereafter, POME emulsion samples are prepared with 5% water and tested in a variable compression ratio diesel engine. The performance and emission characteristics are investigated for a set of loads and compression ratios (CR). The experimental observations show that 5% water in POME produce 3.5% lower brake thermal efficiency and 11% higher brake specific fuel consumption as compared to baseline diesel. Furthermore, the exhaust gas temperature and other emissions like oxides of carbon, oxides of nitrogen and hydrocarbon for the emulsified POME are found to be lower than the baseline diesel.

Abstract Methanogenesis is the conversion of carbon dioxide (CO2) to methane (CH4) using microbes. In the context CO2 utilization, methanogenesis process in the utilizing native microbes from a particular reservoir can be a very slow process without any external intervention. To accelerate the conversion rate and methane yield, this study investigates the use of agriculture by-product such as palm oil mill effluent (POME) as substrates as well as potential microbial isolates that can produce biohydrogen at high temperatures. This paper covers the three laboratory assessments of microbes from anaerobic sludge from a local palm oil mill, use of POME to augment the microbial growth, and physicochemical manipulation to identify key parameters that increases CH4 yield and rate: i) biohydrogen production ii) biomethane production, and iii) syntrophic reactions. All experiments are conducted at 70°C which is considered a hyperthermophilic condition for many microbes. Biohydrogen production achieved with highest H2 production of 66.00 (mL/Lmedium). For biomethane production, the highest production rate achieved was 0.0768 CH4 µmol/mL/day which 10,000X higher than 19.6 pmol/mL/day used as a benchmark. Syntrophic reaction with both types of hydrogen-producing and methanogen in the same reactor, and pure H2 and CO2 supplemented externally was able to achieve the highest methane production of 10.095 µmol/mL and 2.524 µmol/ml/day. Methane production rate is 2.5 times faster than without external gasses being introduced. Introduction of external CO2 to the syntrophic reaction is to mimic actual carbon injection and storage in the reservoir. Our paper shows that stimulation of microbes using POME as substrates and H2/CO2 supplementation are important in accelerating the rate of methane production and yield. Future work will focus on optimizing the gas ratio, pH of growth media, and performing syntrophic reaction in porous media to emulate conditions of a reservoir.

Abstract. The study aims to understand biomass value chains (BVC) in Malaysia, specifically those involving the use oil palm waste such as empty fruit bunch (EFB), palm oil mill effluent (POME) and oil palm trunks (OPT). This particular type of biomass source was selected as it is very abundant and is a major feedstock in existing biomass value chains in the country. The research uses survey methodology to obtain data related to BVCs by surveying relevant stakeholders. From the information obtained in Section 1 and Section 2 of the survey conducted, we were able to assess the enablers and disablers of environment-food-energy-water (EFEW) nexus in biomass value chain, which is the main research objective. Other than that, the raw data from survey is analyzed with SPSS statistical analysis methods to determine the relationship between technology, policies and role of government and private sector with the implementation of sustainable BVCs. Based on this, we found that the R value obtained was 0.759 with an R-square value of 0.575. From the Pearson correlations, we found that X3 (referring to role of private sector) showed the highest correlation and was the only statistically significant variable obtained based on the model. Finally, a comparative study on BVC’s and fossil fuel value chain (FFVC) was also performed. From this comparison, we note that BVCs and FFVCs differ significantly in terms of carbon footprint, economic feasibility, technology, government and private role, policies, infrastructure, and volatility of resource.