The myc family of oncogenic transcription factors, which includes c-myc, N-myc and L-myc, control major cellular processes such as proliferation and differentiation by integrating upstream signals and orchestrating global gene transcription. They do this largely through dimerising with Max, which together bind to enhancer (E)-box elements in DNA. Myc proteins function similarly but differ in potency and tissue distribution. For instance, N-myc is expressed predominantly during development in undifferentiated cells of the nervous system, whereas c-myc is ubiquitously expressed in all proliferating cells. Myc proteins, when deregulated, are major drivers of tumourigenesis. Myc deregulation occurs in up to 70% of all human cancers and is often associated with the most aggressive forms. For example, MYCN, the gene encoding N-myc, is amplified in 20-30% of neuroblastomas, and amplification strongly correlates with advanced stage and poor prognosis. Myc proteins are therefore considered “most wanted” targets for cancer therapy, but have long been considered undruggable mainly due to challenges in nuclear drug delivery and physically targeting myc directly given that it is a largely disordered protein that lacks discernible clefts and pockets for small molecules to inhabit. Furthermore, c-myc is important in normal tissue maintenance so the effect of its inhibition in humans is difficult to predict. However, recent in vivo studies showed that systemic myc inhibition (using the peptide pan myc inhibitor Omomyc) has mild and reversible side effects and induces tumour regression. This has alleviated concerns about the side effects that myc inhibition might have, and reinforced the promise of myc as a powerful drug target. However, the translation of Omomyc into the clinic has been hindered by poor cellular delivery. In fact, no direct myc inhibitor has yet been approved, indicating that novel approaches are needed. Moreover, inhibitors in development tend to inhibit all myc family proteins. An inhibitor that could specifically target N-myc might improve safety through bypassing c-myc inhibition. This could be used for the treatment of N-myc-driven cancers such as MYCN-amplified neuroblastoma. Nanobodies, camelid-derived single-domain antibodies, are a relatively new drug class. Whilst some are already in clinical trials for a wide range of diseases, these are specific for cell-surface or extracellular targets. However, their properties also make them ideal for use as intracellular antibodies or ‘intrabodies’. For example, they are small (just 12-15 kDa) and highly soluble due to naturally occurring hydrophobic to hydrophilic amino acid substitutions. Their small size and convex shape makes them advantageous in capturing structures in intrinsically disordered proteins and allows them to reach hidden epitopes not accessible to conventional antibodies, which could improve biological activity. Importantly, nanobodies retain the high specificities and affinities of conventional antibodies. Their small, single-domain nature also means they can be engineered with ease to modify aspects of their localisation and/or function. For example, they can be coupled to carrier molecules to facilitate cellular entry, and a nuclear localisation signal (NLS) can be added to drive them into the nucleus. Also, it was recently shown that an F-box domain could also be incorporated into nanobodies to recruit degradation machinery to its antigen, which depletes the antigen from cells via the proteasomal degradation pathway. Due to their highly advantageous properties, nanobodies raised against N-myc might overcome the barriers to targeting N-myc, providing potent and specific means of directly inhibiting N-myc therapeutically, which has not yet been achieved. In this thesis, nine unique nanobodies were raised against N-myc. These included three against the basic helix-loop-helix leucine zipper (bHLH-LZ) domain where Max dimerises, and six against the transactivation domain where numerous regulatory and cofactor proteins bind, such as the E3 ubiquitin ligase Skp2. Nanobodies against the transactivation domain were more specific for N-myc and were shown to inhibit its Skp-2-mediated ubiquitylation. This could provide novel means of eradicating tumours based on a study showing that inhibition of ubiquitylation at this domain triggers a transcriptional ‘switch’ that induces a non-canonical target gene Egr1, leading to p53-independent apoptosis. A nanobody against the bHLH-LZ (Nb C2) was shown to bind both N- and c-myc to similar magnitudes. Its affinity for N-myc bHLH-LZ was superior to that of the small molecule myc inhibitor 10058-F4, which prolongs survival in a MYCN-dependent mouse model of high-risk neuroblastoma. Nb C2 spontaneously transduced cell membranes and its coupling to a novel small molecule carrier (SMoC) enhanced its cellular uptake. Furthermore, the addition of a NLS increased its nuclear localisation. Preliminary experiments showed that Nb C2 might slow proliferation and induce apoptosis in cancer cell lines expressing c-myc, suggesting that Nb C2 might also be effective against cancers characterised by deregulated c-myc. Taken together, data generated in this thesis have revealed intriguing findings that provide a basis for the development of these nanobodies for the treatment of N-myc- and c-myc-driven cancers.

No description available.

During the past few years a development of breeding llamas and alpacas took place in Czech Republic. Increasing interest in those animals entails the need to determine how they respond to the conditions of our country. The aim of this thesis is to evaluate the growth ability of crias, some of the physical dimensions (withers height) and bodyweight of adult llamas. The same indicators are to be evaluated for alpacas as well. The results are to be compared with the standard for llamas and alpacas. A total of 104 animals were measured and weighted, namely 44 llamas and 60 alpacas, and 280 pairs of weight and height data were obtained. Weighing and measuring of adult llamas and alpacas took place once a year around the end of August for two years (2009 and 2010). Young llamas were weighed and measured at approximately monthly intervals according to the possibilities of their breeders. Young alpacas were weighed at approximately weekly intervals. The thesis is divided into two parts. The first part evaluates llamas. It was discovered that the average birth weight of llamas in the Czech Republic is 11 kg. Once mature, they reach an average live weight of 130.3 kg and average height of 110.2 cm. Average daily gains were observed as follows: from birth to 7 weeks 0.20 kg per day, from 7 weeks to 24 weeks 0.18 kg per day and from 24 to 72 weeks 0.13 kg per day. The second part of this thesis is devoted to alpacas, for which the same parameters as for the llamas were monitored. It was found that the average birth weight of alpacas in the Czech Republic is 6.5 kg. Once mature, they reach an average live weight of 65.6 kg and average height at 88.4 cm. Average daily gains are at the following levels: from birth to 7 weeks 0.1 kg per day, from 7 weeks to 24 weeks 0.09 kg per day and from 24 weeks to 72 weeks 0.08 kg per day. It was found that these two species reach final physical maturity later in the Czech Republic than stated by literature. Compared to the standard, most of the llamas and alpacas are up to their standards.

Seminario de Título entregado a la Universidad de Chile en cumplimiento parcial de los requisitos para optar al Título de Química Ambiental. / Los suelos se han constituido como el principal sumidero de metales pesados y otros contaminantes producto de causas naturales y actividades antropogénicas. Ejemplo de estas actividades son las mineras que liberan metales pesados, tales como Hg+2, Pb+2, Cu+2 y Zn+2, y las plantas petroquímicas que producen hidrocarburos aromáticos como Benceno, Tolueno, Etilbenceno, y Xilenos (BTEX) a partir de la fracción volátil del petróleo. El objetivo de este seminario de título consiste en validar un método analítico para la cuantificación de benceno en microcosmos conformados por muestras de suelo co-contaminado contenidas en viales, a los cuales se le adiciona una bacteria especializada. De esta forma, se desarrolla una metodología para determinar benceno remanente en suelo, carente de solventes orgánicos, simple y costo-efectiva, mediante un sistema de extracción de espacio de cabeza acoplado a un cromatógrafo de gases junto a un detector de ionización de llama (HS-GC-FID), que permita monitorear la cinética de remoción de benceno en un suelo co-contaminado con Hg (II), durante un proceso de biorremediación bacteriana utilizando la cepa modificada genéticamente Cupriavidus metallidurans MSR33 que es altamente resistente a mercurio. De esta manera, en el presente trabajo se utilizó un suelo contaminado con benceno y mercurio como una aproximación a una situación real de co-contaminación, donde se aplicó una técnica de remediación a través de la utilización de bacterias especializadas capaces de remover benceno en presencia de mercurio. La medición de benceno con la metodología validada permitió monitorear la cinética de biorremediación utilizando la bacteria C. metallidurans MSR33 entregando información rápida y veraz al aplicar directamente en viales con microcosmos de suelo contaminados con Benceno 200 mg×Kg-1 y Hg (II) 2 mg×Kg-1. La determinación de benceno permitió demostrar que este proceso de biorremediación conforma una novedosa tecnología costo-efectiva y amigable con el medioambiente, aplicable a suelos impactados con BTEX en presencia de metales tóxicos. / Soils have been established as the main sink for heavy metals and other pollutants due to natural causes and anthropogenic activities. Examples of these are mining activities which release heavy metals, such as Hg+2, Pb+2, Cu+2 and Zn+2, and petrochemical plants which produce aromatic hydrocarbons such as Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) from volatile fractions of petroleum. The aim of this seminar consists of validate an analytical method for the quantification of benzene in microcosms consisting on vials containing co-contaminated soil samples, which are inoculated with a specially adapted bacterial culture. The methodology was developed in order to measure benzene concentrations remaining in soil in an organic solvent-free, simple and cost-effective manner. This was carried by means of a headspace extraction system coupled to a gas chromatograph with flame ionization detector (HS-GC-FID), that allowed to monitor the kinetics of benzene removal in a soil co-contaminated with Hg (II), during the process of bacterial bioremediation with the genetically modified strain Cupriavidus metallidurans MSR33 that is highly resistant to mercury. Thus, soil samples polluted with benzene and mercury were used on this research as a practical approach to a real co-contamination scenario. A remediation technique was applied by means of bacteria specially adapted to remove benzene from soil in presence of mercury. The measurement of benzene with the validated methodology allowed to monitor the kinetics of bioremediation using the C. metallidurans MSR33 bacterial strain delivering fast and accurate information when applied directly in vials with soil microcosms contaminated with Benzene 200 mg×Kg-1 and Hg (II) 2 mg×Kg-1. The determination of benzene allowed to demonstrate that this process of bioremediation forms a novel, cost-effective and environmental-friendly technology, potentially useful for treatment of soils impacted with BTEX in the presence of toxic metals.

Considering the activity of introducing genetic resources with a high potential for yield, and with a wide adaptation range, it is possible to strengthen the cattle production system, through the production of adequate forage in quality, and quantity. Brazilian grass was introduced to Bolivia in 1974 for demonstrating excellent forage characteristics, and great adaptation qualities to the different ecosystems of the Andes. The material was introduced through the Experimental Station of Patacamaya, with their material supplied through the Experimental Station of Obonuco (Colombia). The following study was conducted at the Agropecuary Experimental Center of Condori, located 49 km. north of the city of Oruro, department of Oruro, and 12 km. northeast of the population of Caracollo. Geographically it is located between the parallels 17°31’41’’ latitude south, and 64°14’ 02’’ longitude west to the Greenwich, and at a height of 3830 m.a.s.l during the year of 2005. The study was performed with the objective of determining the apparent digestibility in Lamas feed with Brazilian grass, and with Wheat, for which 4 species between 2 to 3 years and an average weight of 79 were selected for the study. The specimens were selected according to phenotypic characteristics, each of them having their own metabolic cage with its own feeding and drinking station. The design was completely random with no structured treatments; the significant variables were evaluated under contrast test to 0.05 of probability. The obtained results regarding the quantity of food consumed is much related to the quantity of feces excreted without having statistical differences between these two variables, the average consumption being of 2157.8 g/day and the average production of feces of a 789.55 g/day. The consumption of water is statistically different but proportional to the amount of moisture found in the forage, meaning that the greater amount of water supplied through the plan the less the amount of drinking water. The species consuming Brazilian grass presented a water consumption of 244.64 cc/day in relationship to the moisture percentage of 11.51% of the plant, being 2.38% larger in comparison to wheat. The amount of feces produced by the experimental units shows no statistical difference at a 0.05 of probability in relationship to food consumption, meaning that the amount of feces produced is proportional to amount of ingested food. The urine volume registered 1540.32 cc/day in relationship with the consumption of Brazilian grass, and a lesser volume of 671 cc/day in relationship with wheat consumption, observing significance with 99% of reliability. The results of the digestibility of the nutrients in Brazilian grass, and wheat are the following: Protein 78.59% and 48.01%; Ash 72.99% and 52.59%; Fiber 47.70% and 52.51%; Ethereal Extract 62.64% and 53.11%, respectively. We can conclude that the Brazilian grass is an excellent forage specie of good digestible properties, being protein its principal digestible nutrient.

The present work consisted in the use of biochemical and molecular nutrition blocks (BMN) in llamas during the last third of the gestation period, at the Agricultural Experiment Center of Condori (CEAC), located 49 km north of the city of Oruro, and 12 km north of the Caracollo population, in the province of Cercado. For this research work, we used 20 pregnant llamas in the last third of their gestation period, between the ages of 2 and 3 years old, 10 of which belonged to the Khara breed, and 10 to the Thampulli breed. Two corrals of 7 x 7 m., with adobe walls of a height of 1.80 m., a soil floor, and a metallic door, were built for the placement of the animals. The following ingredients were used for the preparation of the BMN blocks: 100 L of molasses, 75 kg of barley flour, 18 kg of alfalfa flour, 12 kg of sorghum flour, 30kg of mineral salt, 30 kg of Urea to the 46%, and 30 kg, of clay. The following variables were considered: Final body weight of the mother (before birth), increment of live weight of the mother by date, body weight of the mother (after birth), body weight of the llama calf, body weight gain of the mother, mother's food consumption, and physical-chemical analysis of the feeding blocks. The variables of the study were analyzed under a completely randomized design test, and for the discrimination of variable averages we used the Duncan test to a 95% of reliability. We came to the following conclusions: The greater increment of live weight was reported by llamas that received the BMV block as a dietary supplement, the gain was of 107.91 Kg/Llama, and the least was reported by those who did not receive the BMV blocks as a dietary supplement with and increment of 102.07 Kg/Llama. For the final live weight of the mothers, the greater number was reported by llamas that received the BMV blocks, reporting 112.0 Kg/Llama, the least was reported by those who did not receive the supplement with an increase of 105.10 Kg/Llama. Post-partum Llamas that received supplementation reported a live weight increase of 97.43 Kg/Llama, whereas those who did not receive the supplement reported an increase of 88.40 Kg/Llama. According to breed the Khara Llama reported an increase of 96.56 Kg/llama, while the Thampulli line reported an increase of 89.10 Kg/Llama. The greater live weight of the calf at birth was reported by those whose mothers were given the BMN supplements; reporting 11.50 Kg/Calf, while those whose mothers did not receive the supplement reported 9.60 Kg/ Calf. Therefore, we recommend the supplementation of the diet with biochemical and molecular nutrition blocks in the feeding of llamas in the last third of the gestation period to obtain calves with higher body weight at birth.

At an international level, Bolivia possesses the largest population of llamas followed by Peru. This makes our country a power, in this renewable resource, to create and generate economic development primarily for the quality of llama meat which has nutritional properties superior to other species of animals used for food. The development of the investigation of llamas in our country has not been very far-reaching. In other countries, advances have been made for quite some time, specifically in the area of reproduction, which presents problems in bringing about an intensive repopulation due to the unique characteristics of llama copulation and semen. With the present work, carried out in the Unidad Académica Campesina - Tiahuanaco (Universidad Católica Boliviana), titled: Determination of the Protein Fraction and Presence of Antibodies in the Seminal Fluid of Llamas of 3, 4, and 5 years of age, in Different Dates of Semen Collection, the number of protein fractions, their molecular weights, the presence of antibodies, and the concentrations of the protein fractions was determined. This will lead to determining the possible presence of a component in the seminal fluid which is responsible for the low percentage of births achieved in these animals. In studies conducted in the field, a series of tests were carried out so the male would respond to the artificial collection of the semen, beginning with the puppet technique (Peruvian) and others, all of which did not produce results. The objective was achieved with the mannequin of a llama's hindquarters which was accepted by 80% of the males. Laboratory studies consisted in separating seminal fluid from the semen through centrifugation. An electrophoresis technique was employed in order to examine the protein fractions. This technique allowed determination of the number of protein fractions, their molecular weights, immunoglobulin, and their concentrations. The highest number of protein fractions was found in 4 and 5-year-old animals with 15 to 18 protein fractions. In the weekly collection of semen, the final week returned 18 protein fractions (in the 4-year-old animal), which fractions may possibly play an important role in the nutrition, capacitation, and protection of the spermatozoid. The molecular weights of the proteins found in the seminal fluid vary from one animal to another and in the collection dates. The extremes in the range of molecular weights are from 2,000 to 150,000 Daltons. Animals five years in age presented higher molecular weights compared with younger animals. Regarding immunoglobulin or antibodies, proteins were found with molecular weights from 150,000 to 152,500 Daltons in animals from three to five years of age. Through the radial immunodiffusion technique, immunoglobulin G was found in the llama seminal fluid. The protein fraction concentrations are variable, ranging from 11.65 to 0.03 mg/mL of seminal fluid. These variations are heterogeneous as much in animal age as in dates of collection. There exists a loose superiority in five-year-olds and during the third week of semen collection. The obtained results of the protein fractions and their molecular weights demonstrate the existence of antibodies in the seminal fluid of the llama that play an important role in spermatic viability. Because of this, continued investigation should be carried out to determine the antibodies' specific function and find alternatives to isolate and neutralize them and increase the fertility figures of these animals.

[ES] El proceso de combustión en llamas de difusión de combustible atomizado es un fenómeno multifásico altamente complejo que a día de hoy no se comprende en su totalidad, ya que involucra varios eventos simultáneos, como atomización, vaporización y cinética química. A lo largo de los años, los investigadores han estudiado a fondo la combustión en llamas de combustibles líquidos, con el fin de comprender los procesos fundamentales como clave para reducir las emisiones contaminantes y mejorar la eficiencia de la propulsión de las aeronaves. En los últimos años, la evolución tanto en la tecnología de inyección como en la de combustión ha permitido mejorar el proceso de mezcla por aspersión y la eficiencia del motor y, por tanto, reducir las emisiones contaminantes. Por lo que, diferentes configuraciones de tipo de inyector y distribución de aire dentro de la cámara de combustión han demostrado ser capaces de reducir el consumo de combustible, así como las emisiones de óxidos de nitrógeno y hollín sin afectar el rendimiento del motor. Esta tesis proporciona una metodología experimental para estudiar los efectos de las condiciones de co-flujo, el caudal másico de combustible, el tipo de combustible y el diámetro de salida del quemador sobre la atomización y la combustión de la llama producida en un quemador anular bajo condiciones de operación pobres. La caracterización del chorro sin combustión se realizó mediante dos técnicas ópticas diferentes. Por un lado, se utilizó velocimetría de imagen de partículas para medir los campos de velocidad del espray. Por otro lado, retroiluminación microscópica difusa (MDBI) para medir el tamaño y la velocidad de las gotas. Los resultados mostraron que ambos están controladas principalmente por el tipo de combustible y el caudal másico del mismo. Sin embargo, la variación de la velocidad de co-flujo no mostró un efecto significativo en las características de las gotas (tamaño y velocidad), lo que probablemente se deba a que el campo de visión de la técnica MBDI estaba muy cerca de la punta del inyector. Adicionalmente, al incrementar la temperatura de co-flujo se observó que el diámetro promedio de gota disminuía, lo cual es causado por la evaporación del combustible. Finalmente, las variaciones en los perfiles de tamaño y velocidad de las gotas al variar el diámetro de salida de aire se relacionaron con la variación de la velocidad del co-flow, lo que afectaba la evaporación y el arrastre de las gotas. Para el estudio de la llama en condiciones reactivas, se probó en condiciones de operación que permitan llama estabilizadas, utilizando tres técnicas ópticas diferentes, las cuales se activaron simultáneamente. La extinción de luz difusa se utilizó para determinar el espesor óptico del hollín. Además, se emplearon las técnicas de quimioluminiscencia OH* y MDBI para medir la altura de despegue de la llama y las características de las gotas, respectivamente. Los resultados mostraron que la velocidad y temperatura del co-flujo, y el tipo de combustible influyen fuertemente en la altura de despegue de la llama. Mientras que en la formación hollín los parámetros más influyentes fueron la velocidad del co-flujo y el tipo de combustible. Con respecto a los resultados de la evaporación de las gotas, se observó que el tamaño inicial y las propiedades del combustible controlan su evaporación. El combustible n-Dodecano es el menos volátil y tiene un tamaño de gota inicial más grande y, por lo tanto, las gotas tardaron más en evaporarse, lo que resultó en una mayor longitud de despegue de la llama y una mayor formación de hollín debido a su mayor tendencia a formar hollín. Por el contrario, las gotas de n-Heptano se evaporaron más rápido, lo que resultó en una altura de despegue de la llama más corta y también en una menor formación de hollín. Finalmente, el combustible n-Decano mostró resultados intermedios para la evaporación de gotas, la altura de despegue de la llama y la formación de hollín. / [CA] El procés de combustió en flames de difusió de combustible atomitzat és un fenomen multifásico altament complex que a hores d'ara no es comprén en la seua totalitat, ja que involucra diversos esdeveniments simultanis, com a atomització, vaporització i cinètica química. Al llarg dels anys, els investi- gadors han estudiat a fons la combustió en flames de combustibles líquids, a fi de comprendre els processos fonamentals com a clau per a reduir les emissions contaminants i millorar l'eficiència de la propulsió de les aeronaus. En els últims anys, l'evolució tant en la tecnologia d'injecció com en la de combustió ha permés millorar el procés de mescla per aspersió i l'eficiència del motor i, per tant, reduir les emissions contaminants. Pel que, diferents configuracions de tipus d'injector i distribució d'aire dins de la cambra de combustió, han demostrat ser capaços de reduir el consum de combustible, així com les emissions d'òxids de nitrogen i sutja sense afectar el rendiment del motor. Aquesta tesi proporciona una metodologia experimental per a estudiar els efectes de les condicions de co-flux, el cabal màssic de combustible, el tipus de combustible i el diàmetre d'eixida del cremador sobre l'atomització i la combustió de la flama produïda en un cremador anul·lar sota condicions d'operació pobres. La caracterització del doll sense combustió es va realitzar mitjançant dues tècniques òptiques diferents. D'una banda, es va utilitzar velocimetría d'imatge de partícules per a mesurar els camps de velocitat de l'esprai. D'altra banda, retroil·luminació microscòpica difusa (MDBI) per a mesurar la grandària i la velocitat de les gotes. Els resultats van mostrar que tots dos estan controlades principalment per la mena de combustible i el cabal màssic d'aquest. No obstant això, la variació de la velocitat de co-flux no va mostrar un efecte significatiu en les característiques de les gotes (grandària i velocitat), la qual cosa probablement es deu al fet que el camp de visió de la tècnica MBDI estava molt prop de la punta de l'injector. Addicionalment, en incrementar la temperatura de co-flux es va observar que el diàmetre mitjà de gota disminuïa, la qual cosa és causat per l'evaporació del combustible. Finalment, les variacions en els perfils de grandària i velocitat de les gotes en variar el diàmetre d'eixida d'aire es van relacionar amb la variació de la velocitat del co-flux, la qual cosa afectava l'evaporació i l'arrossegament de les gotes. Per a l'estudi de la flama en condicions reactives, es va provar en condicions d'operació que permeten flama estabilitzades, utilitzant tres tècniques òptiques diferents, les quals es van activar simultàniament. L'extinció de llum difusa es va utilitzar per a determinar la grossària òptica del sutge. A més, es van emprar les tècniques de quimioluminescència OH* i MDBI per a mesurar l'altura d'enlairament de la flama i les característiques de les gotes, respectivament. Els resultats van mostrar que la velocitat i temperatura del co-flux, i el tipus de combustible influeixen fortament en l'altura d'enlairament de la flama. Mentre que en la formació sutge els paràmetres més influents van ser la velocitat del co-flux i el tipus de combustible. Respecte als resultats de l'evaporació de les gotes, es va observar que la grandària inicial i les propietats del combustible controlen la seua evaporació. El combustible n-Dodecano és el menys volàtil i té una grandària de gota inicial més gran i, per tant, les gotes van tardar més a evaporar-se, la qual cosa va resultar en una major longitud d'enlairament de la flama i una major formació de sutge degut a la seua major tendència a formar sutge. Al contrari, les gotes de n-Heptano es van evaporar més ràpid, la qual cosa va resultar en una altura d'envol de la flama més curta i també en una menor formació de sutja. Finalment, el combustible n-Decano va mostrar resultats intermedis per a l’evaporació de gotes, l’altura d’envol de la flama i la formació de sutja / [EN] The combustion process in spray flames is a highly complex multi-phase phenomenon that is still not completely understood since it involves several simultaneous events, such as atomization, vaporization, and chemical kinetics. Over the years, researchers have studied the combustion in spray flames thoroughly, in order to understand the fundamental processes as key to re- duce pollutant emissions and improve the efficiency of aircraft propulsion. In recent years, the evolution in both injection and combustion technology has allowed to improve the spray mixing process and engine efficiency and hence, reducing pollutant emissions. Therefore, different configurations of injector type and air distribution inside the combustion chamber have proved capable of reducing fuel consumption, as well as emissions of nitrogen oxides and soot without affecting the engine performance. This thesis provides an experimental methodology to study the effects of co-flow conditions, fuel mass flow rate, fuel type and air outlet diameter at the burner exit on the atomization and combustion behavior of the spray flame produced on an annular spray burner under lean conditions. The characterization of the liquid spray without combustion was carried out using two different optical techniques. On the one hand, particle image velocimetry was used to characterize the global velocity fields of the spray. On the other hand, Microscopic diffused back-illumination (MDBI) to measure the size and droplet velocity at a field of view close to the injector tip. The results exhibited that both droplet size and droplet velocity are mainly controlled by the fuel type and fuel mass flow rate. Nevertheless, the variation of the co-flow velocity did not show a significant effect on droplet characteristics (size and velocity), which is likely due to the fact that the field of view of the MDBI technique was located very close to the injector tip. Additionally, by increasing the co-flow temperature, it was observed that the mean droplet size decreased, which is caused by the fuel evaporation process. Finally, the variations in the droplet size and velocity profiles when varying the air outlet diameter were related to the velocity variation when modifying the cross-sectional area at the burner outlet, which affects the evaporation and drag of the drops. On the spray development in reactive conditions, it was investigated in the operating conditions that promote stabilized flames, using three different optical techniques, all of which were triggered simultaneously. The light extinction was used to determine the optical thickness through the soot cloud. In addition, OH* chemiluminescence and the MDBI techniques were employed to measure the flame lift-off height and droplet characteristics, respectively. The results exhibited that the co-flow velocity, co-flow temperature and fuel type strongly influence the flame lift-off height. While in the soot formation the most influential parameters were the co-flow velocity and the type of fuel. Regarding the results of the droplet evaporation, it was observed that the initial droplet sizes and the fuel properties control the droplet evaporation process. n-Dodecane fuel is the least volatile and also exhibited a larger initial droplet size and thus, the droplets took more time to evaporate than the other two fuels, resulting in a longer flame lift-off height and likewise higher soot formation by its greater tendency to form soot. Contrary, n-Heptane droplets evaporated faster, resulting in a shorter flame lift-off height and also less soot formation. Finally, n-Decane showed intermediate results for droplet evaporation, flame lift-off height, and soot formation. / Cardona Vargas, S. (2021). Development of a test rig for the study of the atomization and combustion of a spray flame in an atmospheric annular spray burner at lean conditions [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/179994 / TESIS

Las emisiones contaminantes hacia la atmósfera, en parte debidas a los motores de combustión interna utilizados en el transporte, es una de las mayores preocupaciones de nuestra sociedad. En el caso de los motores diesel, las especies contaminantes son el monóxido de carbono, los hidrocarburos sin quemar y, principalmente, los óxidos de nitrógeno (NOx) y las partículas de hollín. Estas últimas son el producto de un complejo balance entre su formación y su oxidación. Una vía de futuro es conseguir una combustión por difusión de baja temperatura, intrínsecamente de muy baja formación de hollín. Tanto la formación como la oxidación del hollín dependen directamente del proceso de mezcla. En efecto, el parámetro principal que parece controlar el proceso de formación de hollín es la cantidad de oxígeno englobado por el chorro de combustible en la distancia entre el inyector y el inicio de la llama (lift-off). Al acelerar la mezcla aire-combustible aumentando la presión de inyección y reduciendo fuertemente el diámetro de los orificios del inyector se ha visto que se puede conseguir una combustión por difusión rápida y sin formación de hollín. No obstante, se conoce muy poco sobre el comportamiento del lift-off y del resto del proceso de formación de hollín en condición de combustión de baja temperatura, con baja concentración de oxígeno. El objetivo principal del trabajo es profundizar en la comprensión de estos procesos. Para lograrlo, se ha definido cuatro objetivos particulares: * Caracterizar el efecto de la concentración de oxígeno sobre el lift-off. * Caracterizar las consecuencias sobre el proceso de formación de hollín. * Cuantificar el impacto del aumento de la presión de inyección y del uso de orificios de inyección extremadamente pequeños sobre los dos puntos anteriores. * Para ello, se debe desarrollar: o una metodología de medida simultánea del lift-off y de la concentración de hollín en la llama basada en diferentes técnicas de visualización de ............ / Monin, C. (2009). Caracterización del proceso de formación de hollín en una llama de difusión diesel de baja temperatura [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/6161 / Palancia

[ES] El aumento de las emisiones de CO2 en el sector del transporte ha sido continuo en estos últimos años debido principalmente a la carbonización del sector junto al aumento de la flota de vehículos. Este hecho tiene efectos adversos en la calidad medioambiental, siendo este gas uno de los principales constituyentes de los gases de efecto invernadero, contribuyendo así al calentamiento global. Para mitigar las emisiones de CO2, es necesario una política con estrictas regulaciones que conduzcan a la descarbonización del sector del transporte. En este sentido, la electrificación del sector del transporte es la principal vía para conseguir tales objetivos. Lamentablemente, pasar a la electrificación total del sector en un periodo relativamente corto de tiempo presenta ciertas dificultades, como son la alta demanda de electricidad renovable, la baja capacidad de las baterías, y la falta de estaciones de repuesto. Por ello, el uso de combustibles sintéticos obtenidos a partir de fuentes de energía renovables se presenta como una opción complementaria para ayudar a alcanzar los objetivos de reducción de emisiones de CO2, debido a que puede implementarse de forma más rápida. En la presente tesis doctoral se aborda la caracterización de dos combustibles sintéticos, OME1 y OMEX. Primeramente, se realizó un estudio para caracterizar la estructura de alta y baja temperatura de la llama de ambos combustibles bajo condiciones de referencia de la Engine Combustion Network (ECN) en una instalación de alta presión y temperatura. Posteriormente, se realizaron medidas en un motor óptico, evaluando el efecto que tiene la combinación del uso de mezclas de OMEX/diésel junto a geometrías de pistón no convencionales en la formación de hollín dentro del cilindro. El uso de geometrías de pistón no convencionales se usó debido a que en estudios usando diésel se consiguen reducciones de hollín al mejorar el proceso de mezcla aire-combustible. Por ello, se pretende analizar si ese efecto se obtiene igualmente en presencia de un combustible sintético como es el OMEX. Las instalaciones en las que se han realizado los distintos estudios presentan accesos ópticos. A través de ellos se han usado distintas técnicas de visualización, tanto basadas en laser, como en la propia radiación emitida por la llama. Como conclusiones, se podría resumir en que se ha visto que lo ya conocido sobre el proceso de combustión diésel puede ser aplicado a la combustión del OMEX, con el beneficio de que este es un combustible que no presenta estructura de precursores de hollín haciéndolo idóneo para aplicaciones reales de motor. A pesar de las incompatibilidades de este combustible con la infraestructura del motor, esta se soluciona usando mezclas con diésel, que, además, combinándolo con geometrías no convencionales de pistón se obtienen reducciones importantes de formación de hollín dentro del cilindro. / [CA] L'augment de les emissions de CO¿ en el sector del transport ha sigut continu en aquests últims anys degut principalment a la carbonització del sector al costat de l'augment de la flota de vehicles. Aquest fet té efectes adversos en la qualitat mediambiental, sent aquest gas un dels principals constituents dels gasos d'efecte hivernacle, contribuint així al calfament global. Per a mitigar les emissions de CO¿, és necessari una política amb estrictes regulacions que conduïsquen a la descarbonització del sector del transport. En aquest sentit, l'electrificació del sector del transport és la principal via per a aconseguir tals objectius. Lamentablement, passar a l'electrificació total del sector en un període relativament curt de temps presenta unes certes dificultats, com són l'alta demanda d'electricitat renovable, la baixa capacitat de les bateries, i la falta d'estacions de suministre. Per això, l'ús de combustibles sintètics obtinguts a partir de fonts d'energia renovables es presenta com una opció complementària per a ajudar a aconseguir els objectius de reducció d'emissions de CO¿, pel fet que pot implementar-se de forma més ràpida. En la present tesi doctoral s'aborda la caracterització de dos combustibles sintètics, OME1 i OMEX. Primerament, es va realitzar un estudi per a caracteritzar l'estructura d'alta i baixa temperatura de la flama de tots dos combustibles sota condicions de referència de la Engine Combustion Network (ECN) en una instal·lació d'alta pressió i temperatura. Posteriorment, es van realitzar mesures en un motor òptic, avaluant l'efecte que té la combinació de l'ús de mescles de OMEX/dièsel al costat de geometries de pistó no convencionals en la formació de sutge dins del cilindre. L'ús de geometries de pistó no convencionals es va usar pel fet que en estudis usant dièsel s'aconsegueixen reduccions de sutge en millorar el procés de mescla aïre-combustible. Per això, es pretén analitzar si aqueix efecte s'obté igualment en presència d'un combustible sintètic com és el OMEX. Les instal·lacions en les quals s'han realitzat els diferents estudis presenten accessos òptics. A través d'ells s'han usat diferents tècniques de visualització, tant basades en laser, com en la pròpia radiació emesa per la flama. Com a conclusions, es podria resumir en què s'ha vist que el ja conegut sobre el procés de combustió dièsel pot ser aplicat a la combustió del OMEX, amb el benefici que aquest és un combustible que no presenta estructura de precursors de sutge fent-lo idoni per a aplicacions reals de motor. Malgrat les incompatibilitats d'aquest combustible amb la infraestructura del motor, aquesta se soluciona usant mescles amb dièsel, que, a més, combinant-ho amb geometries no convencionals de pistó s'obtenen reduccions importants de formació de sutge dins del cilindre. / [EN] The increase in CO2 emissions in the transport sector has been continuous in recent years, mainly due to the carbonization of the sector, together with the increase in the vehicle fleet. This fact has adverse effects on environmental quality, being this gas is one of the main constituents of greenhouse gases, thus contributing to global warming. To mitigate CO2 emissions, a policy with strict regulations leading to decarbonizing the transport sector is necessary. In this regard, electrification of the transport sector is the main way to achieve such goals. Unfortunately, moving to full electrification of the sector in a relatively short time presents certain difficulties, such as high demand for renewable electricity, low battery capacity, and lack of refueling stations. Therefore, using synthetic fuels obtained from renewable energy sources is presented as a complementary option to help achieve CO2 emission reduction targets because it can be implemented more quickly. This doctoral thesis deals with characterizing two synthetic fuels, OME1 and OMEX. First, a study was carried out to characterize both fuels high and low temperature flame structures under reference conditions of the Engine Combustion Network (ECN) in a high-pressure and high-temperature installation. Subsequently, measurements were performed on an optical engine, evaluating the effect of combining the use of OMEX/diesel blends and unconventional piston geometries on in-cylinder soot formation. Non-conventional piston geometries were used because, in diesel studies, soot reductions are achieved by improving the air-fuel mixing process. Therefore, it is intended to analyze whether this effect is also obtained in the presence of a synthetic fuel such as OMEX. The facilities where the different studies have been carried out have optical accesses. Through them, different visualization techniques have been used based on laser and the radiation emitted by the flame. In conclusion, it could be summarized that it has been seen that what is already known about the diesel combustion process can be applied to the combustion of OMEX, with the benefit that this is a fuel that does not present a soot precursor structure, making it suitable for real engine applications. Despite the incompatibilities of this fuel with the engine infrastructure, this is solved by using blends with diesel, which, in addition, by combining it with non-conventional piston geometries, significant reductions in in-cylinder soot formation are obtained. / Tejada Magraner, FJ. (2023). Analysis of Fuel Effects on the Diffusive Flame Structure Using Advanced Optical Techniques in a Single Cylinder Optical Engine [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202376