Biological materials : Part A. tuning LCST of raft copolymers and gold/copolymer hybrid nanoparticles and Part B. biobased nanomaterials

The research described in this dissertation is comprised of two major parts. The first part studied the effects of asymmetric amphiphilic end groups on the thermo-response of diblock copolymers of (oligo/di(ethylene glycol) methyl ether (meth)acrylates, OEGA/DEGMA) and the hybrid nanoparticles of these copolymers with a gold nanoparticle core. Placing the more hydrophilic end group on the more hydrophilic block significantly increased the cloud point compared to a similar copolymer composition with the end group placement reversed. For a given composition, the cloud point was shifted by as much as 28 °C depending on the placement of end groups. This is a much stronger effect than either changing the hydrophilic/hydrophobic block ratio or replacing the hydrophilic acrylate monomer with the equivalent methacrylate monomer. The temperature range of the coil-globule transition was also altered. Binding these diblock copolymers to a gold core decreased the cloud point by 5-15 °C and narrowed the temperature range of the coil-globule transition. The effects were more pronounced when the gold core was bound to the less hydrophilic block. Given the limited numbers of monomers that are approved safe for in vivo use, employing amphiphilic end group placement is a useful tool to tune a thermo-response without otherwise changing the copolymer composition. The second part of the dissertation investigated the production of value-added nanomaterials from two biorefinery “wastes”: lignin and peptidoglycan. Different solvents and spinning methods (melt-, wet-, and electro-spinning) were tested to make lignin/cellulose blended and carbonized fibers. Only electro-spinning yielded fibers having a small enough diameter for efficient carbonization ( Peptidoglycan (a bacterial cell wall material) was copolymerized with poly-(3-hydroxybutyrate), a common polyhydroxyalkanoate produced by bacteria with the objective of determining if a useful material could be obtained with a less rigorous work-up on harvesting polyhydroxyalkanoates. The copolyesteramide product having 25 wt.% peptidoglycan from a highly purified peptidoglycan increased thermal stability by 100-200 °C compared to the poly-(3-hydroxybutyrate) control, while a less pure peptidoglycan, harvested from B. megaterium (ATCC 11561), gave a 25-50 °C increase in thermal stability. Both copolymers absorbed more moisture than pure poly-(3-hydroxybutyrate). The results suggest that a less rigorously harvested and purified polyhydroxyalkanoate might be useful for some applications.

Advanced Nanostructured Electro-Catalysts for Electricity Generation and Biorenewable Alcohol Conversion

In my Ph.D research, a wet chemistry-based organic solution phase reduction method was developed, and was successfully applied in the preparation of a series of advanced electro-catalysts, including 0-dimensional (0-D) Pt, Pd, Au, and Pd-Ni nanoparticles (NPs), 1-D Pt-Fe nanowires (NWs) and 2-D Pd-Fe nanoleaves (NLs), with controlled size, shape, and morphology. These nanostructured catalysts have demonstrated unique electro-catalytic functions towards electricity production and biorenewable alcohol conversion. The molecular oxygen reduction reaction (ORR) is a long-standing scientific issue for fuel cells due to its sluggish kinetics and the poor catalyst durability. The activity and durability of an electro-catalyst is strongly related with its composition and structure. Based on this point, Pt-Fe NWs with a diameter of 2 - 3 nm were accurately prepared. They have demonstrated a high durability in sulfuric acid due to its 1-D structure, as well as a high ORR activity attributed to its tuned electronic structure. By substituting Pt with Pd using a similar synthesis route, Pd-Fe NLs were prepared and demonstrated a higher ORR activity than Pt and Pd NPs catalysts in the alkaline electrolyte. Recently, biomass-derived alcohols have attracted enormous attention as promising fuels (to replace H2) for low-temperature fuel cells. From this point of view, Pd-Ni NPs were prepared and demonstrated a high electro-catalytic activity towards ethanol oxidation. Comparing to ethanol, the biodiesel waste glycerol is more promising due to its low price and high reactivity. Glycerol (and crude glycerol) was successfully applied as the fuel in an Au-anode anion-exchange membrane fuel cell (AEMFC). By replacing Au with a more active Pt catalyst, simultaneous generation of both high power-density electricity and value-added chemicals (glycerate, tartronate, and mesoxalate) from glycerol was achieved in an AEMFC. To investigate the production of valuable chemicals from glycerol electro-oxidation, two anion-exchange membrane electro-catalytic reactors were designed. The research shows that the electro-oxidation product distribution is strongly dependent on the anode applied potential. Reaction pathways for the electro-oxidation of glycerol on Au/C catalyst have been elucidated: continuous oxidation of OH groups (to produce tartronate and mesoxalate) is predominant at lower potentials, while C-C cleavage (to produce glycolate) is the dominant reaction path at higher potentials.

THE POTENTIAL OF INDUSTRIAL WASTE AND AGRICULTURAL FEEDSTOCK TOWARDS SUSTAINABLE BIOFUELS PRODUCTION: TECHNO-ECONOMIC AND ENVIRONMENTAL IMPACT PERSPECTIVES

This Ph.D. research is comprised of three major components; (i) Characterization study to analyze the composition of defatted corn syrup (DCS) from a dry corn mill facility (ii) Hydrolysis experiments to optimize the production of fermentable sugars and amino acid platform using DCS and (iii) Sustainability analyses. Analyses of DCS included total solids, ash content, total protein, amino acids, inorganic elements, starch, total carbohydrates, lignin, organic acids, glycerol, and presence of functional groups. Total solids content was 37.4% (± 0.4%) by weight, and the mass balance closure was 101%. Total carbohydrates [27% (± 5%) wt.] comprised of starch (5.6%), soluble monomer carbohydrates (12%) and non-starch carbohydrates (10%). Hemicellulose components (structural and non-structural) were; xylan (6%), xylose (1%), mannan (1%), mannose (0.4%), arabinan (1%), arabinose (0.4%), galatactan (3%) and galactose (0.4%). Based on the measured physical and chemical components, bio-chemical conversion route and subsequent fermentation to value added products was identified as promising. DCS has potential to serve as an important fermentation feedstock for bio-based chemicals production. In the sugar hydrolysis experiments, reaction parameters such as acid concentration and retention time were analyzed to determine the optimal conditions to maximize monomer sugar yields while keeping the inhibitors at minimum. Total fermentable sugars produced can reach approximately 86% of theoretical yield when subjected to dilute acid pretreatment (DAP). DAP followed by subsequent enzymatic hydrolysis was most effective for 0 wt% acid hydrolysate samples and least efficient towards 1 and 2 wt% acid hydrolysate samples. The best hydrolysis scheme DCS from an industry's point of view is standalone 60 minutes dilute acid hydrolysis at 2 wt% acid concentration. The combined effect of hydrolysis reaction time, temperature and ratio of enzyme to substrate ratio to develop hydrolysis process that optimizes the production of amino acids in DCS were studied. Four key hydrolysis pathways were investigated for the production of amino acids using DCS. The first hydrolysis pathway is the amino acid analysis using DAP. The second pathway is DAP of DCS followed by protein hydrolysis using proteases [Trypsin, Pronase E (Streptomyces griseus) and Protex 6L]. The third hydrolysis pathway investigated a standalone experiment using proteases (Trypsin, Pronase E, Protex 6L, and Alcalase) on the DCS without any pretreatment. The final pathway investigated the use of Accellerase 1500® and Protex 6L to simultaneously produce fermentable sugars and amino acids over a 24 hour hydrolysis reaction time. The 3 key objectives of the techno-economic analysis component of this PhD research included; (i) Development of a process design for the production of both the sugar and amino acid platforms with DAP using DCS (ii) A preliminary cost analysis to estimate the initial capital cost and operating cost of this facility (iii) A greenhouse gas analysis to understand the environmental impact of this facility. Using Aspen Plus®, a conceptual process design has been constructed. Finally, both Aspen Plus Economic Analyzer® and Simapro® sofware were employed to conduct the cost analysis as well as the carbon footprint emissions of this process facility respectively. Another section of my PhD research work focused on the life cycle assessment (LCA) of commonly used dairy feeds in the U.S. Greenhouse gas (GHG) emissions analysis was conducted for cultivation, harvesting, and production of common dairy feeds used for the production of dairy milk in the U.S. The goal was to determine the carbon footprint [grams CO2 equivalents (gCO2e)/kg of dry feed] in the U.S. on a regional basis, identify key inputs, and make recommendations for emissions reduction. The final section of my Ph.D. research work was an LCA of a single dairy feed mill located in Michigan, USA. The primary goal was to conduct a preliminary assessment of dairy feed mill operations and ultimately determine the GHG emissions for 1 kilogram of milled dairy feed.

Mehrwertdienst im Lebenszyklus von Sachanlagen in der Logistik

Unter dem General-Thema „Hybride Wertschöpfungsketten“ sind Zukunftsaufgaben subsummiert, die eine maßgebliche Verbesserung der Kooperationsprozesse vieler unterschiedlicher Dienste aus einem Leistungsobjekt verfolgen. Wenn das Leistungsobjekt eine Anlage ist, dann sind Wertschöpfungsketten gemeint, die von einer ersten Nutzungsspezifikation bis zur Verschrottung reichen. Mit Wertschöpfung sind sowohl Leistungen zur Herstellung und Integration dieser Anlagen in Betreiberprozesse bezeichnet, als auch diejenigen, die einen Beitrag dieser Anlage zur Wertschöpfung beim Nutzer leisten. Mit Mehrwertdiensten sind somit alle Leistungen gemeint, die an der Anlage oder für die Anlage während ihres gesamten Anlagenlebenszyklus erbracht werden. Sie dienen zur Nutzenerhöhung beim Betreiber, dem Nutzer und dem Anlagenhersteller. Damit sind Mehrwertdienste in Hybriden Wertschöpfungsketten grundsätzlich kollaborative Dienste, die üblicherweise konfliktäre Ziele mehrerer (oder sogar vieler) Interessen auflösen müssen.

Beitrag einer nutzungsabhängigen Instandhaltung zur Planung von Leistungsverfügbarkeit

Stets darauf bedacht, die Anlagen- und Maschinenverfügbarkeit bei möglichst geringem Ressourceneinsatz zu gewährleisten, wird die Rolle der Instandhaltung als unternehmerischer Wertschöpfungsfaktor immer bedeutsamer. Voraussetzung für eine Nutzbarmachung bestehender Potentiale sind neue Werkzeuge und Ansätze, deren Umsetzung eine effiziente Sicherstellung von Verfügbarkeit ermöglicht. Vor diesem Hintergrund wurde im Teilprojekt C3 des DFG Paketantrags 672 ein Konzept zur nutzungsabhängigen Instandhaltung entwickelt. Auf Grundlage des bestehenden Zusammenhangs von Nutzung und Abnutzung risikobehafteter Bauteile intralogistischer Systeme können damit die durch zukünftige Systemlasten hervorgerufenen Beanspruchungen antizipiert werden. Instandhaltungsmaßnahmen und technische Verfügbarkeiten werden dadurch anforderungsgerecht und ressourcen-optimal planbar.

The end of the corporate life cycle

This paper asks how takeover and failure hazards change as listed firms get older. The hypothesis is that they increase because firms gradually run out of growth opportunities. We find the opposite. Both takeover and failure hazard drop significantly with age. The decline in takeover hazard can be explained with Loderer, Stulz, and Waelchli’s (2013) “buggy whip makers” hypothesis: Because old firms are comparatively well-managed and are affected by limited agency problems, on average, they offer little value added potential to acquirers. Failure hazard drops because to learning. The results are robust to various alternative interpretations and cannot be explained by unobserved heterogeneity. While hazards decline with age, they do not go to zero. This explains why, eventually, all listed firms disappear

The end of the corporate life cycle

This paper asks how takeover and failure hazards change as listed firms get older. The hypothesis is that they increase because firms gradually run out of growth opportunities. We find the opposite. Both takeover and failure hazard drop significantly with age. The decline in takeover hazard can be explained with Loderer, Stulz, and Waelchli’s (2013) “buggy whip makers” hypothesis: Because old firms are comparatively well-managed and are affected by limited agency problems, on average, they offer little value added potential to acquirers. Failure hazard drops because to learning. The results are robust to various alternative interpretations and cannot be explained by unobserved heterogeneity. While hazards decline with age, they do not go to zero. This explains why, eventually, all listed firms disappear

The end of the corporate life cycle

This paper asks how takeover and failure hazards change as listed firms get older. The hypothesis is that they increase because firms gradually run out of growth opportunities. We find the opposite. Both takeover and failure hazard drop significantly with age. The decline in takeover hazard can be explained with Loderer, Stulz, and Waelchli’s (2013) “buggy whip makers” hypothesis: Because old firms are comparatively well-managed and are affected by limited agency problems, on average, they offer little value added potential to acquirers. Failure hazard drops because to learning. The results are robust to various alternative interpretations and cannot be explained by unobserved heterogeneity. While hazards decline with age, they do not go to zero. This explains why, eventually, all listed firms disappear

Commentary on "Alternative Strategies for Identifying High-Performing Charter Schools in Texas"

In the last few years policy makers and practitioners nationally have shown much interest in identifying, recognizing, and replicating successful charter schools, many of which are showing that they can educate low-income and otherwise at-risk students remarkably well. However past efforts to identify high performing schools have been problematic. Using these systematic, rigorous value-added methods, the authors identify 44 Open Enrollment charter schools that merit a “high-performer” rating. Nearly all of those campuses identified serve a disadvantaged student population. The article also finds that most of those high performers are highly cost-effective, earning high ratings on the cost-efficiency measures. The authors argue for more widespread use of value-added modeling in the state accountability system. The approach taken to identifying high-performers is sensible and fair, but any formulaic approach to school labels comes with some limitations.

Alternative Strategies for Identifying High-Performing Charter Schools in Texas

The Obama administration's recurring policy emphasis on high-performing charter schools begs the obvious question: how do you identify a high-performing charter school? That is a crucially important policy question because any evaluation strategy that incorrectly identifies charter school performance could have negative effects on the economically and/or academically disadvantaged students who frequently attend charter schools. If low-performing schools are mislabeled and allowed to persist or encouraged to expand, then students may be harmed directly. If high-performing schools are driven from the market by misinformation, then students will lose access to programs and services that can make a difference in their lives. Most of the scholarly analysis to date has focused on comparing the performance of students in charter schools to that of similar students in traditional public schools (TPS). By design, that research measures charter school performance only in relative terms. Charter schools that outperform similarly situated, but low performing, TPSs have positive effects, even if the charter schools are mediocre in an absolute sense. This analysis describes strategies for identifying high-performing charter schools by comparing charter schools with one another. We begin by describing salient characteristics of Texas charter schools. We follow that discussion with a look at how other researchers across the country have compared charter school effectiveness with TPS effectiveness. We then present several metrics that can be used to identify high-performing charter schools. Those metrics are not mutually exclusive—one could easily justify using multiple measures to evaluate school effectiveness—but they are also not equally informative. If the goal is to measure the contributions that schools are making to student knowledge and skills, then a value-added approach like the ones highlighted in this report is clearly superior to a levels-based approach like that taken under the current accountability system.

El plan estratégico Argentina Apícola 2017 y su influencia en el sector apícola de la localidad de Tandil

By means of this paper is to critically analyze the current situation of beekeeping in the town of Tandil (Buenos Aires), from the objectives set out in the Strategic Plan Argentina Beekeeping 2017, approved in 2008, whose goal is aimed at that country from becoming a global market leader of value-added bee products, ensuring sustainable development in economic, environmental and social. At first briefly reviews the national bee scene, in which Argentina is known for being the third largest producer of honey, after China and the U.S., while competing with China for the first world exporter, a situation that contrasts with low domestic consumption. Then describes the strategic objectives that promotes the Plan, including: marketing, production, promotion and added value. Then we analyze the main characteristics of the honey industry in the area chosen, the town of Tandil, where the stage is characterized by a large number of small producers who are mostly engaged in the informal sale of honey for direct consumption but whose demand is low, compared to a small number of collectors, packers and exporters that dominate the international market. In general it is observed that, with few exceptions, the honey is exported in bulk, as a commodity, and its main use molasses to improve lower quality of recipient countries. Meanwhile the honey for local consumption, is usually of inferior quality because they generally are not subject to quality controls required by the circuit of export. To overcome the limitations of beekeeping above, highlights the collaborative efforts of government agencies such as the National Institute of Agricultural Technology (INTA) and the Faculty of Veterinary Science, National University Centre of the Province of Buenos Aires. As a preliminary conclusion, it is argued that the Strategic Plan Argentina Beekeeping is still valid as a tool for development of the sector, and is also essential to encourage the development of competitive products in terms of quality and differentiation, through the development of technology and knowledge sharing to ensure growth and sustainability of beekeeping in the town of Tandil

Los cambios en el proceso de producción del algodón en el Chaco en las últimas décadas y sus consecuencias en las condiciones de vida de minifundistas y trabajadores vinculados

En el artículo nos planteamos los cambios que desde los años 1990 ha sufrido la producción de algodón en la Provincia del Chaco -principal referente nacional del cultivo- y cómo estos fueron modificando la estructura de vida de los agentes históricamente vinculados, en especial, los trabajadores y los minifundistas hoy prácticamente excluidos de dicho proceso. Entre los numerosos cambios, los más relevantes son los vinculados al proceso de tecnificación, a la desarticulación en el territorio de cadenas de valor agregado y a la diversificación hacia otros cultivos como las oleaginosas y, notoriamente, al avance del cultivo de soja sobre hectáreas antes destinadas al algodón. Como consecuencia de dichos procesos de cambio, se evidencia la imposibilidad -por parte de los minifundistas- de sostener una producción rentable, la pérdida de numerosas fuentes de trabajo directas e indirectas, el aumento de la pobreza, la emigración hacia los cordones periféricos urbanos (Gran Resistencia, Gran Rosario) y el deterioro de las condiciones laborales de quienes aún permanecen dentro del sistema productivo algodonero. Las políticas públicas, tanto locales como nacionales, también son un punto de interés en el análisis puesto que tienen gran repercusión en el actual estado de la situación

Dinámicas del sector agropecuario argentino en el siglo XXI : La distribución del ingreso en regiones pampeanas y extrapampeanas

En este trabajo se analizan una serie de aspectos que resultan centrales para comprender la situación de los trabajadores en el sector agropecuario. En primer lugar, se contrapone la evolución del producto del sector con su capacidad para generar puestos de trabajo. Luego, se da cuenta de las condiciones de empleo poniendo especial énfasis en el estudio del grado de informalidad y de los niveles salariales. Se compara, a continuación, la distribución primaria del ingreso del sector con la de la economía nacional en su conjunto. Este análisis distributivo se complementa con dos estudios de caso que intentan poner de manifiesto las implicancias de los distintos cultivos llevados a cabo en diferentes regiones. El estudio muestra que el salario medio del sector agropecuario sigue estando muy por debajo de la remuneración promedio de la economía y que, además, la participación de los salarios en el valor agregado del sector se ha reducido desde la salida de la Convertibilidad, incluso en un contexto de aumento del salario medio sectorial. Finalmente, sobre la base del análisis de los casos mencionados, se asocia la distribución del ingreso con los distintos cultivos y las regiones donde estos se desarrollan. Al respecto, se discute el rol de las ganancias individuales como guía orientadora del uso de la tierra cultivable

Los cambios en el proceso de producción del algodón en el Chaco en las últimas décadas y sus consecuencias en las condiciones de vida de minifundistas y trabajadores vinculados

En el artículo nos planteamos los cambios que desde los años 1990 ha sufrido la producción de algodón en la Provincia del Chaco -principal referente nacional del cultivo- y cómo estos fueron modificando la estructura de vida de los agentes históricamente vinculados, en especial, los trabajadores y los minifundistas hoy prácticamente excluidos de dicho proceso. Entre los numerosos cambios, los más relevantes son los vinculados al proceso de tecnificación, a la desarticulación en el territorio de cadenas de valor agregado y a la diversificación hacia otros cultivos como las oleaginosas y, notoriamente, al avance del cultivo de soja sobre hectáreas antes destinadas al algodón. Como consecuencia de dichos procesos de cambio, se evidencia la imposibilidad -por parte de los minifundistas- de sostener una producción rentable, la pérdida de numerosas fuentes de trabajo directas e indirectas, el aumento de la pobreza, la emigración hacia los cordones periféricos urbanos (Gran Resistencia, Gran Rosario) y el deterioro de las condiciones laborales de quienes aún permanecen dentro del sistema productivo algodonero. Las políticas públicas, tanto locales como nacionales, también son un punto de interés en el análisis puesto que tienen gran repercusión en el actual estado de la situación

Dinámicas del sector agropecuario argentino en el siglo XXI : La distribución del ingreso en regiones pampeanas y extrapampeanas

En este trabajo se analizan una serie de aspectos que resultan centrales para comprender la situación de los trabajadores en el sector agropecuario. En primer lugar, se contrapone la evolución del producto del sector con su capacidad para generar puestos de trabajo. Luego, se da cuenta de las condiciones de empleo poniendo especial énfasis en el estudio del grado de informalidad y de los niveles salariales. Se compara, a continuación, la distribución primaria del ingreso del sector con la de la economía nacional en su conjunto. Este análisis distributivo se complementa con dos estudios de caso que intentan poner de manifiesto las implicancias de los distintos cultivos llevados a cabo en diferentes regiones. El estudio muestra que el salario medio del sector agropecuario sigue estando muy por debajo de la remuneración promedio de la economía y que, además, la participación de los salarios en el valor agregado del sector se ha reducido desde la salida de la Convertibilidad, incluso en un contexto de aumento del salario medio sectorial. Finalmente, sobre la base del análisis de los casos mencionados, se asocia la distribución del ingreso con los distintos cultivos y las regiones donde estos se desarrollan. Al respecto, se discute el rol de las ganancias individuales como guía orientadora del uso de la tierra cultivable