TOWARDS SUSTAINABLE PRODUCTION OF CHEMICALS AND FUELS FROM THE FAST PYROLYSIS OF WASTE POLYOLEFIN PLASTICS

The increasing amount of plastic waste (PW) generation has become an important concern due to the leveled-off recycling rates. Therefore, governmental agencies around the world, including state governments in the United States, have proposed initiatives to minimize the amount of PW that is landfilled and encourage recycling or energy recovery. Circular economy is a strategy that attempts on reusing PW to produce new polymers while avoiding its disposal and the use of virgin material. Chemical recycling raises an interesting technology prospect due to the potential reduction of pollutant emissions and the establishment of a circular economy through the production of monomers and fuels. This dissertation initially presents a resource assessment for available MSW in Mexico and concludes that when the organic and polyolefin plastic components are converted to liquid hydrocarbon transportation biofuels through a pyrolysis-based pathway, up to 7% of Mexico’s transportation-fuel consumption could be met. A preliminary carbon footprint analysis (CFA) shows that liquid transportation biofuels from the organic portion of MSW (paper, packaging, wood, yard trimmings) sequesters 9.5 g CO2 eq. per MJ biofuel, with significant pathway credits due to avoiding landfill CH4 emissions. The greenhouse gas (GHG) emissions from the conversion of the polyolefin plastic in the MSW are positive (88 g CO2 eq. per MJ), though still lower than current fossil transportation fuels in Mexico (95.5 g CO2 eq. per MJ). In this Ph.D. research, pyrolysis vapors from waste high density polyethylene (HDPE) were subjected to secondary degradation by varying the temperature and vapor residence time (VRT) in the reaction zone of a newly-designed two-stage micropyrolysis reactor (TSMR). Temperature and VRT variations showed a strong effect on the product distribution, with low temperature (625 ºC) and short VRT (1.4 s) producing a wide range of gases and liquid products and with high temperature (675 ºC) and long VRT (5.6 s) producing mostly hydrocarbon gases (monomers) and mono- and poly-aromatics. The last two chapters of the dissertation present a novel multiproduct/multiprocessing pyrolysis-based refinery design for the conversion of 500 tonnes/day of high-density polyethylene (HDPE) waste. The products obtained from the refinery are chemical grade ethylene and propylene, an aromatics mixture, and low- and high-molecular weight hydrocarbon mixtures (MWHCs). The energy efficiency was 72 and 77% for the base case and the heat integrated (HI) refinery, respectively. The net present values (NPVs) were 367 and 383 million U.S. dollars (MM USD), for the base case and the heat integrated process, respectively. The CFA results show that the GHG emissions of all products; ethylene, propylene, aromatics mixture, low molecular weight (MW) hydrocarbons (HCs), and high MW HCs, are equal to or less than fossil products for the HI scenario assuming US average electricity grid. Finally, the evaluation of regional electricity grids on GHG emissions for all products was conducted for all 50 states in the US. These results suggest energetic, economic, and environmental sustainability of the design and its promising application on an industrial scale. This dissertation ends with overall conclusions and recommendations for future research

College and Career Awareness in Elementary Schools

Greenfield Union School District provides the educational needs of students, K-6, who are economically disadvantaged, English learners, and special education. Data shows that students in the Greenfield Union School District have low academic performance in English, Mathematics, and other subjects. One reason for low academic performance is the lack of student engagement in school. The capstone project attempted to encourage student engagement, by increasing students’ knowledge and awareness about college and careers. Three 5th grade classes participated in the college activities. The capstone project consisted of four college awareness sessions. The sessions included activities which expanded students’ knowledge about career exploration, college terminology, researching skills, college culture, and college tips and skills. Data collected through a pre-survey and post-survey indicated that students gained knowledge and awareness of college and career topics. As a result of the project, students’ knowledge about college terminology increased. Also, there was a noticeable increase in student engagement

Síntesis de estructuras porosas (ZrO2/SiO2) mediante el uso de biomoléculas como plantillas

Actualmente existen numerosas plantillas para la síntesis de estructuras porosas, las cuales controlan la morfología y el tamaño de poro del material final. Además de la plantilla, diversos parámetros controlan la formación de la red inorgánica que forma las paredes de las estructuras porosas, tales como el medio (acuoso, mezcla de solventes), alcalinidad, reactividad de los precursores, relación molar del tensoactivo (plantilla)/precursor en el que se realiza la síntesis. Por otro lado, el bacteriófago M13 ha sido ampliamente utilizado como plataforma en la síntesis y organización de nanomateriales. Gracias a sus características fisicoquímicas: monodispersidad, carga superficial, tamaño, forma, estabilidad térmica y química, así como a la diversidad de grupos funcionales que posee en la superficie. Otra característica importante es su capacidad de auto-organizarse y ensamblarse en cristales líquidos, convirtiéndolo en una molécula biológica idónea para ser empleada como plantilla o bloque de construcción. En particular el virus M13 ha sido probado como una plantilla eficiente en la síntesis de estructuras mesoporosas de SiO2, el cual se empleó en su forma nativa, y dirigió la forma y tamaño de la red porosa. Incluso este fago fue modificado químicamente en la superficie con grupos tiol para que estos sirvieran como sitios de nucleación en la formación de nanopartículas de oro y simultáneamente en la síntesis de estructuras mesoporosas, dando lugar a mesoporos de SiO2 decorados con nanopartículas de oro. Debido a que el bacteriófago M13 ha servido de plantilla en la síntesis de estructuras mesoporosas, en este trabajo se exploró la posibilidad de emplearlo en la síntesis de estructuras porosas de óxido de zirconio, con el objetivo principal de probar su capacidad como plantilla general en la producción de estructuras porosas. Si bien el alcóxido de zirconio tiene una mayor reactividad en medio acuoso que el alcóxido de silicio, este puede formar estructuras porosas en presencia de fago bajo ciertas condiciones. En este trabajo se presenta una serie de experimentos realizados en la síntesis de óxidos porosos puros y mixtos (ZrO2 y ZrO2/SiO2), en los cuales se optimizó la concentración de fago y se estableció su influencia en la formación de cavidades. Así mismo se estudió el efecto de la relación molar de los precursores (Zr:Si) en la morfología y cristalinidad del sólido final. Los materiales obtenidos se caracterizaron por diferentes técnicas: difracción de rayos X, espectroscopia UV-vis e infrarroja, microscopia electrónica y adsorcióndesorción de Nitrógeno. Se observó que la concentración de fago (6 y 8 mg/mL) no es determinante en la obtención de estructuras porosas ordenadas alrededor del fago, pero su ordenamiento hexagonal y la formación de cúmulos (ramilletes) si influye en la formación de estructuras porosas (30 nm). Se propone que esto es efecto de la cantidad del alcóxido de zirconio empleado en la síntesis, debido a su alta reactividad e instantánea formación de oligómeros

Roles Of A Nuclear Hormone Receptor During C. Elegans Germline Development

Two fundamental problems of developmental biology are the understanding of cell fate specification, and the integration of broader environmental contexts into developmental programs. While cell fate specification is largely achieved by differential gene expression programs, environmental integration relies on cellular receptors. A predominant mechanism to mediate both processes utilizes nuclear hormone receptors (NHRs). However, it remains unclear how diverse the NHR’s modes of action are in regulating gene expression. This thesis utilizes the development of the C. elegans germ line as a model system to study a novel link that integrates cell fate specification and the nutritional environment. In C. elegans, germ cell fate specification is chiefly controlled by posttranscriptional mechanisms. Furthermore, overall germline development is influenced by the animal’s nutritional status. However, it remains unknown whether germline posttranscriptional control mechanisms and germ cell fate decisions are linked to nutrition, and if so, how this link may operate in molecular terms. This thesis reports the characterization of the nuclear hormone receptor nhr-114 and its crucial functions for germline development and fertility. Depending on the tissue of expression, nhr-114 regulates overall germline organization, germ cell proliferation and oogenesis. Importantly, all aspects of nhr-114 function are linked to diet. Feeding nhr-114 mutants with a specific E. coli strain, or a tryptophan-supplemented diet significantly reduces germline development defects and sterility. Based on mutant analysis, nhr-114 was found to have overlapping functions with gld-4 cytoplasmic poly(A) polymerase (cytoPAP). This thesis provides evidence that nhr-114 may function in germ cells in a posttranscriptional manner linked to gld-4 cytoPAP. Further evidence shows that NHR-114 interacts with GLD-4 cytoPAP. Together these findings suggest that NHR-114 may control gene expression by transcriptional and posttranscriptional mechanisms in a tissue-specific manner. This thesis proposes that NHR-114 ensures the input of tryptophan to allow germline development; and that this function integrates nutritional information into the germline gene expression programs according to the environment of the worm. Therefore, NHR-114 potentially provides a direct molecular link to how a developmental program is coordinated with the nutritional status of an animal

Modelling of Ethanol Production from Red Beet Juice by Saccharomyces cerevisiae under Thermal and Acid Stress Conditions

Utjecaj pH-vrijednosti i temperature na proizvodnju etanola iz soka cikle ispitan je s pomoću sojeva kvasca Saccharomyces cerevisiae ITD00196 i S. cerevisiae ATCC 9763. Logističkom je jednadžbom kvantitativno opisan rast mikroorganizama, dok je Pirtovom jednadžbom opisana potrošnja supstrata, a Luedeking-Piretovom proizvodnja etanola. S pomoću oba soja S. cerevisiae postignuti su visoki prinosi i ostvarena je dobra volumetrijska produktivnost etanola u uvjetima toplinskog stresa u kiseloj sredini. Jednadžbe kojima je modelirana kinetika fermentacije u skladu su s eksperimentalnim podacima, što potvrđuje da je proizvodnja etanola u tim uvjetima ovisila o rastu kvasca. Soj je kvasca S. cerevisiae ITD00196 imao bolja fermentativna svojstva, pa se njegova uporaba može smatrati prikladnijom za razvoj bioprocesa za proizvodnju etanola.In this work the effects of pH and temperature on ethanol production from red beet juice by the strains Saccharomyces cerevisiae ITD00196 and S. cerevisiae ATCC 9763 are studied. Logistic, Pirt, and Luedeking-Piret equations were used to describe quantitatively the microbial growth, substrate consumption, and ethanol production, respectively. The two S. cerevisiae strains used in this study were able to produce ethanol with high yield and volumetric productivity under acid and thermal stress conditions. The equations used to model the fermentation kinetics fit very well with the experimental data, thus establishing that ethanol production was growth associated under the evaluated conditions. The yeast S. cerevisiae ITD00196 had the best fermentative capacity and could be considered as an interesting option to develop bioprocesses for ethanol production

La reforma educativa y la evaluación docente en Guerrero

La Reforma educativa ha sido señalada como una de las prioridades del Gobierno Federal en México. Se ha implementado a partir de la visión sobre el papel de la educación para alcanzar los objetivos de la modernización del país y ha correspondido a la perspectiva del desarrollo nacional desde los sectores que detentan el poder. En las políticas públicas para la educación están presentes la visión de los organismos internacionales como el Banco Mundial y el Banco Interamericano de Desarrollo que han condicionado su financiamiento a la implementación de las llamadas reformas estructurales de acuerdo al modelo de desarrollo neoliberal que ha propiciado una creciente desigualdad e inequidad en la población. El principal objetivo de esta investigación es conocer la repercusión de la Reforma Educativa en las políticas implementadas para la mejorar la calidad educativa en especial relacionada con la evaluación docente ante el grave rezago educativo en el Estado de Guerrero. La Reforma educativa obedece a una política pública desde la óptica del poder y carece de una perspectiva pedagógica; es decir, se trata de una propuesta educativa sin contenidos sustantivos y centrada en la evaluación docente. La reforma Educativa del gobierno Federal tiene una visión reduccionista y administrativa para limitarla al Ingreso, permanencia y promoción del personal docente. Se parte de un diagnóstico equivocado de que son los profesores la principal causa del problema educativo

The MGuard coronary stent: safety, efficacy, and clinical utility

Atheromatous and thrombotic embolization during percutaneous coronary revascularization is a feared complication that may cause impaired myocardial reperfusion even with a patent epicardial vessel. The MGuard stent is a cobalt chromium bare metal stent with a porous net attached to its outer surface that has been designed to prevent thrombus fragmentation and distal embolization during stent implantation. This review summarizes the available evidence supporting the use of the MGuard stent in different scenarios such as lesions with high thrombus burden, saphenous vein graft interventions, coronary perforations, or carotid lesion