PRIMARY AND SECONDARY REACTIONS OF CELLULOSE MELT PYROLYSIS

Fast pyrolysis of biomass is a next-generation biofuels production process that is capable of converting solid lignocellulosic materials (in their raw form) to a transportable liquid (bio-oil) which can be catalytically hydrogenated to fuels and chemicals. Pyrolysis reactors depolymerize solid biomass by heating the feedstock (in the absence of oxygen) up to high temperatures (400 – 600 °C) to produce a short-lived intermediate liquid phase (only a few seconds), which ultimately breaks down to form small (1-6 carbon) oxygenates. These vapor-products can then be condensed at room temperature to produce liquid bio-oil. While biomass fast pyrolysis has enormous potential to produce renewable fuels, an understanding of the fundamental chemistry and transport processes of biomass pyrolysis to produce bio-oil is not available in the literature. This work utilizes co-pyrolysis and isotopic labeling to study the liquid-phase secondary reactions of levoglucosan to form anhydrosugars, pyrans, and light oxygenates. Isotopic labeling studies also reveal that hydrogen exchange is a critical component of levoglucosan deoxygenation. Next, the effects of pyrolysis reaction temperature and sample length scale are discussed. These studies revealed that the yield of total furan rings (i.e., all products containing a five-membered furan ring) does not change significantly with increased reaction temperature compared to other pyrolysis products, such as light oxygenates and anhydrosugars. However, the functional groups bound to the furan ring (e.g., alcohols and aldehydes) are easily cleaved to produce smaller furans. This chemistry was targeted by impregnating cellulose with palladium on carbon to selectively decarbonylate oxygenated furans within liquid intermediate cellulose to form deoxygenated furans resulting in a more stable bio-oil. The last part of this thesis, a new experimental technique, Spatiotemporally-Resolved Diffuse Reflectance in situ Spectroscopy of Particles (STR-DRiSP), which is capable of measuring biomass composition during fast pyrolysis with high spatial (ten micron) and temporal (one millisecond) resolution is developed. Compositional data were compared with a comprehensive two-dimensional single particle model. The STR-DRiSP technique can be used to determine the transport-limited kinetic parameters of biomass decomposition for a wide variety of biomass feedstocks

Putting urban context in the debate. Bibliometric approaches from the meta-analysis of scientific literature

¿Por qué es primordial, en un mundo de múltiples, complementarias y a veces divergentes significaciones, la concepción de “contexto urbano”? Aquel constituye el cuestionamiento central de este artículo que revisa las sucesivas definiciones de dicho concepto, emanadas de publicaciones científicas asociadas a disciplinas como arquitectura, estudios urbanos, entre otros.Se propone una metodología basada en un análisis bibliométrico para examinar la presencia conceptual del contexto en las investigaciones de entre 1977 y 2017. Se constata que la utilización del vocablo, de uso frecuente, ha terminado por oscurecer el potencial de este término. Los resultados sugieren, además, que el contexto urbano ha sido empleado en la producción científica atendiendo a las realidades particulares de cada país, sin llegar a un acuerdo en sus variables. Además, se ha aplicado sin definir esas realidades particulares.Why is the definition of urban context essential, in a world of multiple, complementary and, sometimes, divergent meanings? This is the central question of the article. This work reviews the successive definitions of this concept, that emerge from the scientific databases of publications from areas such as architecture and urban studies, among others. It has been stated that the frequent use of this term has ended up confusing its potential. A methodology based on a bibliometric analysis is proposed to examine the conceptual presence of the context in research between 1977 and 2017. The results suggest that urban context has been used in scientific production to face the particular realities of each country, without reaching an agreement on its variables. In addition, it has been applied without defining these realities

Hospedándose en la ciudad global: patrones de localización de los hoteles de lujo en Santiago de Chile

Chile se está convirtiendo en uno de los destinos más importantes en América Latina, especialmente, con su capital, Santiago. Así, asume un papel fundamental en los atractivos turísticos de familias, turistas urbanos y de negocios. Estos últimos juegan un rol importante dentro de este contexto, ya que las cadenas internacionales han construido numerosos hoteles de lujo dirigidos a ellos, alcanzando los estándares de las ciudades globales. La continua reestructuración económico-urbana de las metrópolis ha producido una distribución policéntrica de los hoteles de lujo; la mayoría de ellos, los más costosos y ostentosos, se ubican en la ciudad moderna. El aeropuerto, los centros de innovación y parques de negocio, al igual que el centro de la ciudad, también han formado parte de este nicho de inversión. En el caso del área de estudio analizada, las localizaciones de los hoteles de lujo muestran patrones que reflejan una nueva producción del espacio por parte de los agentes privados, en su búsqueda de una mejor capitalización de la renta urbana. Ello se refleja en la estructura intraurbana de los precios y la distribución de los hoteles de lujo.Chile, for a long time a backwater of international tourism, is about to turn itself into a top–end destination, with the capital Santiago taking a leading role. In recent decades, international chains have constructed numerous luxury hotels aimed at the requirements of international city and business tourists. The continuing bicentric orientation of the city (core city and ‘modern town’), which has withstood all fragmentation processes, has led to a polycentric distribution of luxury hotels, with the largest, most expensive and most luxurious hotels situated in the ‘modern town’. The airport, the innovation centers and business parks, as well as the city center, have also seen investment. When compared with models of hotel localization in cities, it is evident that Santiago has overcome the traditional model of city tourism under the influence of globalization trends. Today the needs of global travelers, both city and business tourists, transport links and the surroundings of the hotels play an important role. This is reflected in the pricing structure and the distribution of luxury hotels across the city.Chile estáse transformando num dos destinos mais importantes na América Latina, especialmente, com sua capital, Santiago. Desse modo, assume um papel fundamental nos atrativos turísticos de famílias, turistas urbanos e de negócios. Estes últimos têm um papel importante dentro desse contexto, jáque as cadeias internacionais construíram numerosos hotéis de luxo dirigidos a eles, alcançando os padrões das cidades globais. A contínua reestruturação econômico–urbana das metrópoles produziu uma distribuição policêntrica dos hotéis de luxo; a maioria deles, os mais caros e ostentosos, localizase na cidade moderna. O aeroporto, os centros de inovação e parques de negócio, assim como o centro da cidade, também formaram parte desse nicho de investimento. No caso da área de estudo analisada, as localizações dos hotéis de luxo mostram padrões que refletem uma nova produção do espaço por parte dos agentes privados, em sua busca de uma melhor capitalização da renda urbana. Isso se reflete na estrutura intraurbana dos preços e na distribuição dos hotéis de luxo

Nature as an obstacle: critical perspectives of the advancement of social housing and road infrastructure over wetlands in the city of Valdivia, Chile

Discussing under the concepts of a scientific model reports certain difficulties, especially in the development of reflections and ways of thinking the geographical space. The following case presents the progress in the urban expansion in the city of Valdivia, Chile, within the framework to offers an exceptional occupation in certain spaces with relevant natural value, but whose commercial aptitude makes them even more tasty for housing operations and infrastructure. It is observed, from the evidence gathered in the area, that the articulations in the reproduction of capital in space break natural barriers, converting it permanently into anthropized and suitably altered spaces, turning it into a second nature. This new version of the environment abandons its qualities as an obstacle, resulting in exceptional areas for analysis, such as the Guacamayo sector at the city of Valdivia. The bandurria is the excuse to test the conceptual framework that political ecology offers to know about the cross between society and nature

Root Exudates Alter the Expression of Diverse Metabolic, Transport, Regulatory, and Stress Response Genes In Rhizosphere \u3ci\u3ePseudomonas\u3c/i\u3e

Plants live in association with microorganisms that positively influence plant development, vigor, and fitness in response to pathogens and abiotic stressors. The bulk of the plant microbiome is concentrated belowground at the plant root-soil interface. Plant roots secrete carbon-rich rhizodeposits containing primary and secondary low molecular weight metabolites, lysates, and mucilages. These exudates provide nutrients for soil microorganisms and modulate their affinity to host plants, but molecular details of this process are largely unresolved. We addressed this gap by focusing on the molecular dialog between eight well-characterized beneficial strains of the Pseudomonas fluorescens group and Brachypodium distachyon, a model for economically important food, feed, forage, and biomass crops of the grass family. We collected and analyzed root exudates of B. distachyon and demonstrated the presence of multiple carbohydrates, amino acids, organic acids, and phenolic compounds. The subsequent screening of bacteria by Biolog Phenotype MicroArrays revealed that many of these metabolites provide carbon and energy for the Pseudomonas strains. RNA-seq profiling of bacterial cultures amended with root exudates revealed changes in the expression of genes encoding numerous catabolic and anabolic enzymes, transporters, transcriptional regulators, stress response, and conserved hypothetical proteins. Almost half of the differentially expressed genes mapped to the variable part of the strains’ pangenome, reflecting the importance of the variable gene content in the adaptation of P. fluorescens to the rhizosphere lifestyle. Our results collectively reveal the diversity of cellular pathways and physiological responses underlying the establishment of mutualistic interactions between these beneficial rhizobacteria and their plant hosts

Volatiles Loss from Water Bearing Regolith Simulant at Lunar Environments

Permanently shadowed craters at the lunar poles contain water, ~5 wt% according to LCROSS. Interest in water for ISRU applications. Desire to 'ground truth' water using surface prospecting; e.g. Resource Prospector (RP) & RESOLVE. How to access subsurface water resources and accurately measure quantity; Excavation operations and exposure to lunar environment may affect the results A series a ground based dirty thermal vacuum tests are being conducted to better understand the subsurface sampling operations: Sample removal and transfer, Volatiles loss during sampling operations, Concept of operations, Instrumentation. This presentation covers: The capabilities of the VF-13 Thermal Vacuum Chamber (Tvac). The Resource Prospector TVAC hardware. The summary and results of 5 years of RP volatiles tests; 43 viable sample

Investigation of Tc Migration Mechanism During Bulk Vitrification Process Using Re Surrogate

As a part of Bulk vitrification (BV) performance enhancement tasks, Laboratory scoping tests were performed in FY 2004-2005 to explore possible ways to reduce the amount of soluble Tc in the BV waste package. Theses scoping tests helped identify which mechanisms play an important role in the migration of Tc in the BV process (Hrma et al. 2005 and Kim et al. 2005). Based on the results from these scoping tests, additional tests were identified that will improve the understanding of Tc migration and to clearly identify the dominant mechanisms. The additional activities identified from previous studies were evaluated and prioritized for planning for Tasks 29 and 30 conducted in FY2006. Task 29 focused on the improved understanding of Tc migration mechanisms, and Task 30 focused on identifying the potential process changes that might reduce Tc/Re migration into the castable refractory block (CRB). This report summarizes the results from the laboratory- and crucible-scale tests in the lab for improved Tc migration mechanism understanding utilizing Re as a surrogate performed in Task 29