Academic literature on the topic 'Lignite granules'

Adsorption potential of surface modified granule (SM-G) to remove acid brown 75 (AB 75) from aqueous solution was investigated using fixed-bed column mode. To produce SMG, lignite fly ash was agglomerated into porous granules by an extruder at 800°C and surfacemodified with a cationic surfactant, Hexadecyltrimetylammonium Bromide (HDTMABr). The performance of the fixed-bed column was evaluated to assess the effect of various process variables, viz., of bed height, flow rate and initial feed concentration on breakthrough time and adsorption capacity. The bed depth service time (BDST) model was applied to the data for predicting breakthrough curves and to determine the characteristic parameters. The highest experimental and theoretical bed capacities were obtained to be 55.3 mg of AB 75 adsorbed per gram of SM-G. The results indicated that the SM-G is a suitable adsorbent for the removal of AB 75 from aqueous solution.

The article considers the effect of the granulometric composition of pine wood sawdust and granulation modes on the thermal decomposition of biofuel. Mechanical activation and thermal activation of raw materials before pressing were used in the study. Thermal decomposition of granular fuel was carried out by the methods of thermogravimetry and differential thermal analysis. The temperature ranges of dehydration, thermal decomposition of organic and mineral substances, moisture and ash content of the fuel have been determined. The rates of thermal decomposition of organic substances in granular fuel were also determined. The thermal effects of thermal decomposition of the granule samples were compared. It is registered that the equilibrium moisture content of granules obtained after thermal activation of the raw material is lower than that for granules made by cold pressing. This is indirect evidence of their increased density. It has been determined that most of the heat of thermal decomposition of organic substances in granular fuels is released in the high-temperature period at a decomposition rate of 1,12 to 1,37 % dry matter per minute. It was revealed that the thermal effect of thermal decomposition of granules depends on the fractional composition of the ground raw materials. This may be due to the difference in the chemical composition of the fractions. The analysis of obtained results made it possible to determine that the mechanical activation of raw materials increases the average rate of granule decomposition, and thermal activation reduces it. That is, the mechanical activation of raw materials has a positive effect on the thermal decomposition process. Grinding wood sawdust to particles smaller than 0,2 mm can lead to partial destruction of complex macromolecular compounds (hemicellulose, cellulose and lignin). Thus, this leads to a decrease in the degree of intermolecular interaction and intensification of the decomposition process.

Strength properties of mineral materials used in the track operation, which are crushed stone and sand, do not depend on the ambient temperature (up to 500 °C) and humidity, but gradually degrade when its pore space becomes clogged with fines, oil products and plant residues. Polymeric materials used in the construction of railway tracks for damping dynamic loads, when exposed to significant stresses, are gradually destroyed. The main operating conditions that determine the performance of polymer products include the ambient temperature, its humidity, the presence of a chemically aggressive external effect and a stress fields. Cuts or scratches — stress concentrators on polymer products — significantly change the thermal dependence of its mechanical properties. Therefore, hemispherical grooves, cylindrical cuts in the central areas of pads, made to reduce wear in the peripheral areas, lead to a significant narrowing of the temperature range of the effective operation of these products. Granular media have strong non-linear properties, the main causes of which are microcracks, boundaries and areas of contact of the granules a well as physic-mechanical properties of substances that fill the pore space of crushed stone layer. Coefficient of energy absorption in a granular medium is directly proportional to the viscosity of the polymer layer between the granules. Filling the pore space of the crushed stone layer with sand and viscous-plastic medium (polymers, organic binders and materials based on them, solid polyurethane foam, water or oil products) leads to decrease in the strength of crushed stone prism. An increase in the ambient temperature, especially above 30 °C, reduces the elastic properties and structural viscosity of viscousplastic materials that fill the pore space of a crushed stone prism, thereby reducing its strength. But at the same time, the energy absorption coefficient of vibration in a wide frequency range sharply increases and the dynamic loads on the track gauge profile are decreased. Most often, cheap organic-based compositions are used as dynamic load absorbers in the crushed stone layer: synthetic resins, acrylic acid amide polymers, latexes, lignin sulfonates and bitumen. When filling the pore space of crushed stone, an adhesive interaction occurs between the polymer molecules and the surfaces of the granules. Polymer molecules fill not only the pore space, but also penetrate into the contact area of the granules, reduce friction and decrease the angle of internal friction of crushed stone and the adhesion index of the bulk material. However the operation of railways is associated with permanent deformation and destruction of the surface layers of the polymer. Multiple repetition of the deformation process leads to an increase in mechanical hysteresis losses, causing friction and wear of the polymer in contact with the granules. Therefore, one should not expect a long service life when using a polymeric material for hardening the ballast layer.

Performance and characterization of microorganisms in a laboratory-scale anaerobic baffled reactor (ABR) was studied. The ABR was fed continuously at organic loading rate (OLR) of 15.2 g COD/l.d with a substrate containing pre-tested combination of kitchen waste and activated sludge. The HRT (hydraulic retention time), C/N (carbon/nitrogen) and F/M (food/microorganisms) ratios were maintained at 3 d, 31.4 and 0.35 gCOD/gVSS.d, respectively. The amounts of fat, protein, cellulose, hemi-cellulose and lignin which are significant polymers for anaerobic digestion start-up were found to be in appropriate ranges. Results show reduction of pH in front compartments and its boost in successive compartments. This indicates proper placement of acidogens and methanogens in the ABR. Also, significant growth in height of ABR granule bed was observed in the system based on formation and retention of granules. Microorganism characterization reveals large population ofMethanosarcinain front part of the reactor although toward the end the amount forMethanosaetaincreased. WhileMethanobacterium,Methanosprilium,MethanococcusandMethanobrevibacterwere observed in the ABR, higher percentage ofMethanosarcinaandMethanotrixindicates production of methane from acetate conversion.

Recently, microcrystallization technology has gained much interest because of the enhanced dissolution of the target sample and promotion of the sustainable development of agriculture. Phosphorus (P) is one of the most important nutrients for increasing crop yield; the increase in effective P ratio directly from raw phosphate rock (PR) powder by mechanical grinding to increase its microcrystallinity is believed to be the best choice for this purpose. This study reports the improvement in the activation property of PR powder with different lignite ratios (1%, 2%, 3%, and 5%), particularly the relationship between particle-size distribution, specific surface area, granule morphology, and the citric acid-soluble P. It was found that a 3% lignite addition was the optimal treatment for increasing the release of citric acid-soluble P. The maximum total amount of dry matter from rapeseed cultivation and the available P after the test increased by 56.1% and 89.6%, respectively, with direct use of PR and microcrystallized PR powder (PR2), compared with the control test without any addition of phosphate minerals.

This study was conducted to evaluate the capability of sulfonated lignin (S-lignin) to induce the flocculation of anaerobic sludge in upflow wastewater treatment. Two upflow anaerobic sludge bed-filter (UBF) reactors fed with a synthetic sugar waste were operated at a specific loading rate of 0.6 to 1.8 g of chemical oxygen demand (COD) per g of volatile suspended solid (VSS) per day (d). One of these reactors was stepwise supplemented with a spent liquor rich in S-lignin from a neutral sulfite semi-chemical (NSSC) pulping plant to reach an addition rate of 0.17 g S-lignin/g VSS d; 50 % of the S-lignin was adsorbed onto the biomass. This resulted in pre-granulation of the anaerobic sludge: 50 to 60% of the biomass was in particles > 0.3 mm versus 70 to 80% with a size < 75 µm in the control reactor. In addition, the S-lignin supplementation slightly enhanced the specific metabolic activities of the biomass. Calcium ion addition following the S-lignin treatment enhanced the stability and the density of the aggregates.

This thesis deals with various physical-chemical aspects of agricultural and environmental applications of the South Moravian lignite. The main attention was paid to the behavior of lignite in an aqueous environment and the application potential of lignite as a cheap, effective and universal sorbent. In the experimental part of the thesis, aqueous extracts of lignite were characterized in detail (by measurement of pH, conductivity, and by the qualitative and quantitative determination of inorganic constituents). The high sorption affinity towards polar (cationic dyes) and nonpolar compounds (petroleum products) was confirmed experimentally. At last, simple methods of the laboratory preparation of lignite granules was designed and optimized. The main aim of this part was to combine the unusual sorption properties of lignite with an improvement of the end-use properties of the product (user-friendly handling, controlled release of the lignite into the aqueous environment, etc.). The thesis represents a complex compilation of the results of pilot experiments which represent the starting point of detailed future works focused on the non-energetic application of this valuable natural material.

La cellule mastocytaire comporte un système sécrétoire très spécialisé. Elle possède des granules et plus de 80% de leur contenu peuvent être libères dans les quelques minutes suivant la stimulation. Les granules contiennent de nombreux médiateurs inflammatoires qui, secrètes dans le milieu extérieur, sont en grande partie responsables des réactions d'hypersensibilité immédiate. Au cours de ce travail, nous avons caractérisé les protéines contrôlant les fonctions sécrétoires des mastocytes après leur activation via le récepteur de haute affinité pour les IGE (RFCI). Nous avons étudié le rôle des petites proteines g rab3 connues pour etre specifiquement impliquees dans l'exocytose regulee. L'identification de ces gtpases a montré que les iso formes RAB3A et RAB3D étaient exprimées et que seule l'iso forme RAB3D semble intervenir dans le contrôle de la dégranulation induite via le récepteur RFCI, dans les mastocytes. Nous avons ensuite entrepris l'analyse du complexe de fusion membranaire, le complexe snare. Le noyau de ce complexe est compose de trois grandes familles de protéines : les syntaxines, les snap et les vamp. Dans la famille des syntaxines, les isoformes 2, 3, et 4 sont exprimées, alors que les snap ne semblent être représentées que par l'isoforme snap23. Le groupe des vamp quant a lui comprend vamp2, cellubrevine, ti-vamp et vamp8. Nous avons ensuite montre que 1) la syntaxine 4 est un élément central dans la formation des complexes snare et 2) elle est impliquée fonctionnellement dans la degranulation des RBL-2H3. Enfin nous avons pu montrer que vamp8, présente sur les granules sécrétoires, est mobilisée au cours de la stimulation. Tous ces résultats sont en faveur de l'existence d'un complexe de fusion dans les cellules RBL-2H3, compose de la syntaxine 4, de snap23 et de la protéine vamp8.

Une des caractéristiques majeures des carcinomes les plus agressifs issus des tissus stéroïdo-dépendants réside dans la perte de la sensibilité aux stéroïdes associée à la forte expression des protéines responsables de la synthèse (Hyaluronate synthases ou HAS), de la dégradation (Hyaluronidases ou HYAL) et de la liaison membranaire (CD44) de l’acide hyaluronique (AH), glycosaminoglycanne non sulfaté de haut poids moléculaire. Pour évaluer un possible antagonisme fonctionnel entre signalisation oestrogénique et activité du « hyaluronome », l’expression génique de HYAL1 a été modifiée de manière stable par transfection de vecteurs d’expression contenant soit des séquences codant pour des miRNA ciblant les transcrits de HYAL1 soit la séquence codante du gène HYAL1 dans des cellules de carcinome mammaire MCF-7 ERα (+) présentant une faible expression des différents acteurs du « hyaluronome ». Alors que la sous-expression de HYAL1 se traduit essentiellement par une sensibilité oestrogénique accrue en terme de prolifération, la sur-expression de HYAL1 induit principalement une résistance au 4-hydroxytamoxifène et une réduction des capacités transcriptionnelles des ERα. Bien que cette altération de la signalisation oestrogénique soit associée à une augmentation de l’expression génique et protéique de ERβ, décrits comme des perturbateurs de la signalisation médiée par les ERα, la nature des mécanismes impliqués reste à déterminer. Ces effets, observables aussi bien sur les cellules MCF-7 encore « oestrogénisées » que sur les cellules LTED (long term estrogen deprived) montrent que l’augmentation du catabolisme de l’AH, dans les cellules présentant un « hyaluronome » peu actif, induit une répression de la signalisation oestrogénique. Par contre, dans la lignée de granulosa humaine KGN, insensibles aux oestrogènes et présentant de fortes expressions de HAS2 et du CD44 mais une déficience en HYAL1, la sur-expression de HYAL1 n’a pas de conséquence sur la faible expression des ERs. Elle induit toutefois une forte augmentation de la prolifération cellulaire associée à une diminution marquée de la synthèse d’oestradiol stimulable par l’AMP cyclique, consécutive à une répression transcriptionnelle de CYP19A1. Ces effets apparaissent consécutifs à une augmentation de la synthèse d’AH et à la production accrue d’oligosaccharides et impliquent une activation de la voie JNK. Ces résultats mettent en évidence différents rôles de la HYAL1 suivant le niveau cellulaire de synthèse et de liaison de l’AH et désignent l’AH ou ses métabolites comme des régulateurs potentiels de la prolifération et de la signalisation oestrogénique dans certains carcinomes et sans doute dans des phénomènes physiologiques non pathologiques tels que la folliculogénèse
One of the main properties of the most aggressive carcinoma originating from steroid-dependent tissues is the loss of steroid sensitivity, which is associated with the enhanced expression of proteins involved in synthesis (hyaluronan synthases or HAS), catabolism (hyaluronidases or HYAL) and cell binding (CD44) of hyaluronan (HA), a high molecular-weight non-sulfated glycosaminoglycan. To investigate a possible functionnal antagonism between estrogen signaling and “hyaluronome” activity, HYAL1 expression has been stably modified (by transfection of expression vectors containing either coding sequences for HYAL1-targeted miRNA or coding sequence for human HYAL1 gene) in ERα positive breast cancer MCF7 cells, which exhibit low gene expression for members of “hyaluronome”. While HYAL1 underexpression essentially increases estrogen-dependent cell-proliferation, HYAL1 overexpression leads to increased resistance towards 4-hydroxytamoxifen and reduced transcriptional ERα activities. Altered estrogen signaling is associated with enhanced ERβ expression, previously described as ERα signaling disruptor, but the precise mechanisms involved in the attenuation of ERα signaling remains to be resolved. These effects, also observed in the long term estrogen deprived MCF7 cells, point out that, in low “hyaluronome” expressing cells, HYAL1 overexpression could contribute to the loss of estrogen signaling in breast carcinoma cells. On the contrary, in the estrogen-insensitive human granulosa tumor cells KGN, which exhibits high expression of HAS2 and CD44 but low HYAL1 levels, HYAL1 overexpression does not alter their estrogen insensitivity. However, HYAL1 overexpression induces both increase in cell proliferation and decrease in cAMP-stimulated estrogen synthesis through a transcriptional suppression of CYP19A1, coding for aromatase. These effects result from HYAL1-induced increase in both HA synthesis and HA oligosaccharides production and are dependent on c-jun N-terminal kinase activation. All these results highlight different roles of HYAL1 depending on cellular levels of HA binding and HA synthesis. They also point out HA and its oligosaccharides as potential regulators of cell growth and estrogen signaling in cancer but also in non pathological process such as folliculogenesis

L'hormone anti-Müllérienne (AMH) est impliquée dans la différenciation sexuelle foetale des Mammifères : produite exclusivement par les gonades mâles, elle induit la régression des canaux de Müller, ébauches de l'utérus. L'AMH, dont le gène a été identifié chez plusieurs espèces, est une glycoprotéine de la superfamille des TGFβ. Elle est produite exclusivement par les cellules de Sertoli des testicules chez les mâles prépubères et, plus faiblement, par les cellules de Sertoli testiculaires et les cellules de la granulosa ovarienne chez les individus pubères et adultes. Chez la souris mâle, nous avons trouvé que le taux sérique d' AMH chute parallèlement au taux de ses ARNm, au début de la puberté. En utilisant des souris mutantes insensibles aux androgènes ou dépourvues de cellules germinales méïotiques, nous avons pu suggérer une répression par les androgènes et par la méïose et une stimulation par la FSH de la sécrétion d'AMH chez le mâle postnatal. Par ailleurs, nous avons généré des souris transgéniques pour 3,6 kb 5'-flanquantes du gène de l'AMH humaine, couplées soit à l'oncogène du virus SV40 (souris AT), soit à un minigène de l' AMH humaine. L'analyse de l'expression de ces transgènes suggère que ces 3,6 kb contiennent des régions régulatrices transcriptionnelles activées dans les cellules de Sertoli immatures et dans les cellules de la granulosa de l'adulte. Les souris AT adultes développent des tumeurs testiculaires de Sertoli et des tumeurs ovariennes de la granulosa et nous avons établi des lignées cellulaires à partir de gonades de ces souris. Par northern blot des ARN totaux, de nombreux ARNm caractéristiques des cellules de Sertoli sont détectables dans toutes les lignées testiculaires, alors que ceux de l'AMH ne le sont que dans les lignées prépubères (prétumorales). L'une d'elles (SMATl) a été clonée, a un profil d'expression génique en accord avec un état immature des cellules de Sertoli et, jusqu'à plus de 30 repiquages, sécrète de l'AMH et exprime ses ARNm. Etant le premier modèle cellulaire exprimant stablement le gène endogène de l'AMH en culture in vitro, elle devrait être utile pour étudier les mécanismes cellulaires et moléculaires des régulations de l'expression de cette hormone. Une lignée cellulaire dérivée de tumeurs ovariennes devra être caractérisée davantage pour confirmer sa différenciation de type granulosa. Nos lignées cellulaires gonadiques exprimant les ARNm du récepteur de l'AMH (AMHR-II), elles devraient être utiles pour étudier sa signalisation et les effets autocrines de l'AMH. Nos lignées cellulaires gonadiques et les souris AT servent aussi de modèles pour étudier l'intérêt de l'AMH et de l'AMHR-II comme marqueurs moléculaires des tumeurs de la granulosa de l'ovaire, qui représentent 6 à 10% des tumeurs malignes de l'ovaire chez la femme.

Pour améliorer la durabilité des voies ferrées, il a été introduit sur la LGV BPL (Bretagne- Pays de Loire), une couche bitumineuse sous ballast, destinée entre autre à diminuer l’amplitude des accélérations produites par le passage des TGV, ce qui est une cause majeure du tassement de ballast. Afin d'étudier les réponses dynamiques des différentes structures, trois sections avec sous couche bitumineuse, et une section avec sous couche granulaire de la voie BPL ont fait l’objet d’une instrumentation, avec suivi à distance des mesures. L’objectif de ce travail de thèse est d’analyser et de modéliser la réponse des sections instrumentées, et de comparer leur comportement durant la phase de montée en vitesse puis durant la phase d’exploitation commerciale. Les résultats ont indiqué un bon comportement des sections bitumineuses. La comparaison des accélérations obtenues sur les différentes sections a confirmé l’effet positif de la couche bitumineuse sur la stabilité de la voie. Sur la base des mesures de la phase de montée en vitesse, des modélisations de la réponse mécanique des sections de la LGV BPL à l’aide du logiciel ViscoRail ont confirmé la fiabilité du logiciel à reproduire le comportement mécanique des structures. Les mesures de température, de teneur en eau, et de tassements verticaux ont également confirmé le bon comportement saisonnier des structures bitumineuses. Enfin, une extension de ViscoRail est mise en place, pour comparer l’effet de différents types de semelles sous rail, linéaire et non linéaire, sur la réponse de la voie
To improve railways durability, it has been introduced on the HSL BPL (Bretagne-Pays de Loire), a bituminous layer under ballast, intended among other things to reduce the amplitude of the accelerations produced by highspeed trains circulations, which is a major cause of ballast settlement. In order to study the dynamic responses of the different structures, three sections with bituminous underlayment, and a section with a granular sub-layer of BPL track were instrumented. Measurements are monitored remotely. The objective of this thesis is to analyze and model the response of the instrumented sections, and to compare their behavior during the speed up phase and during the commercial service phase. The results indicated good behavior of bituminous sections. The comparison of the accelerations obtained on different sections confirmed the positive effect of the asphalt concrete layer on the stability of the track. Based on the speed up phase measurements, modeling the mechanical response of the various HSL sections using ViscoRail has confirmed the software’s reliability to reproduce the mechanical behavior of railway structures. Temperature measurements, water content and vertical settlements have also confirmed the good seasonal behavior of bituminous structures. Finally, an extension of ViscoRail is put in place, to compare the influence of different types of rail pads, linear and nonlinear, on the response of the track

Gasification converts the carbon-containing material into a synthesis gas (syngas) which can be used as a fuel to generate electricity or used as a basic chemical building block for a large number of uses in the petrochemical and refining industries. Based on the mode of conveyance of the fuel and the gasifying medium, gasification can be classified into fixed or moving bed, fluidized bed, and entrained flow reactors. Entrained flow gasifiers normally feature dilute flow with small particle size and can be successfully modeled with the Discrete Phase Method (DPM). For the other types, the Eulerian-Eulerian (E-E) or the so called two-fluid multiphase model is a more appropriate approach. The E-E model treats the solid phase as a distinct interpenetrating granular “fluid” and it is the most general-purposed multi-fluid model. This approach provides transient, three-dimensional, detailed information inside the reactor which would otherwise be unobtainable through experiments due to the large scale, high pressure and/or temperature. In this paper, a transient, three-dimensional model of the Power Systems Development Facility (PSDF) transport gasifier will be presented to illustrate how Computational Fluid Dynamics (CFD) can be used for large-scale complicated geometry with detailed physics and chemistry. In the model, eleven species are included in the gas phase while four pseudo-species are assumed in the solid phase. A total of sixteen reactions, both homogeneous (involving only gas phase species) and heterogeneous (involving species in both gas and solid phases), are used to model the coal gasification chemistry. Computational results have been validated against PSDF experimental data from lignite to bituminous coals under both air and oxygen blown conditions. The PSDF gasifier geometry was meshed with about 70,000, hexahedra-dominated cells. A total of six cases with different coal, feed gas, and/or operation conditions have been performed. The predicted and measured temperature profiles along the gasifier and gas compositions at the outlet agreed fairly well.