Domino Reactions Involving Merged Cycloaddition and Cycloreversion Processes Affording Pyridine Products

This thesis explores oxazinone and pyrazinone intermediates in the merged Diels-Alder and retro-Diels-Alder strategies for the synthesis of substituted pyridines. Dihydrooxazinone substrates are prepared and investigated in a domino reaction sequence that comprises an aldol condensation, alkene isomerization, Diels-Alder, and retro-Diels-Alder reaction. Preliminary efforts intended to expand the reaction scope to include aliphatic aldehydes are included and potentially applicable to the synthesis of guaipyridine alkaloids including the rupestines

Investigating the formation and remodelling of myelinated axons in vivo

Myelin is a crucial component of the vertebrate nervous system, both in facilitating rapid conduction of action potentials and in metabolically supporting axons. Recent research has theorised that myelin sheaths play a more intricate role in nervous system function by regulating circuits in response to experience. The number, length, thickness, and distribution of myelin sheaths along an axon all influence its underlying conduction properties. Thus, establishing or changing particular myelin patterns along axons could refine the precise timing of signals to change circuit outputs. Yet, how the myelin patterns along single axons are established, how myelin is remodelled over time, and how neuronal activity affects these processes, is not yet fully understood. I sought to investigate how myelin is formed, remodelled and maintained over time along individual axons in the larval zebrafish central nervous system. I first characterised the formation of myelin patterns along two different subtypes of axon in the larval zebrafish spinal cord. Using transgenic tools and confocal microscopy, I performed live imaging of single axons over a period of time during developmental myelination. Reticulospinal (RS) axons are involved in locomotor circuits, and are myelinated in a synaptic vesicle release-dependent manner; whereas, Commissural Primary Ascending (CoPA) axons are involved in sensory processing circuits, and are myelinated in a synaptic vesicle release-independent manner. I hypothesised that myelin patterns along axons are formed in a circuit-dependent fashion, and, therefore, that axons from different circuits would exhibit different myelin patterns. However, I found that both RS and CoPA axons have very similar myelin patterns, in terms of their myelin sheath number, length, myelin coverage, and nodal gap length, and that these patterns are established within a defined time window after the onset of myelination. I, then, assessed how myelin sheaths are remodelled along RS and CoPA axons over time, and found that myelin sheaths could either grow or shrink in length, or could be fully retracted from the axon itself. I hypothesised that myelin remodelling would occur along axons which use activity-related signals to regulate their myelination, and therefore, that RS axons would exhibit more myelin remodelling than CoPA axons. However, I found that RS and CoPA axons exhibited very similar degrees of myelin remodelling. Finally, I used a chemogenetic tool and live imaging by confocal microscopy to investigate how increasing activity in individual RS axons affects the dynamics of myelin sheath growth and the formation of myelin patterns. I found that increasing neuronal activity promotes the early growth of myelin sheaths within a critical period; after this period, neuronal activity no longer affects myelin sheath dynamics along RS axons. By promoting this early sheath growth, activity can change the myelin pattern established along individual RS axons. Collectively, this research begins to elucidate how individual myelinated axons are formed and maintained during nervous system development, and the cellular mechanisms by which neuronal activity may regulate this process

Amidyl Radical-Mediated Polyolefin C–H Functionalization

Polyolefins, polyaromatics, polyesters, and polyethers comprise 63% of plastics worldwide. Their utility in modern society has enabled advancements but consequently has also led to rapid plastic accumulation. Using these waste materials as reactants, recent developments in the field of C–H functionalization as a post-polymerization modification technique of the commodity polymers are discussed. Xanthylation of atactic poly(butene) was possible via the use of a N-xanthylamide reagent. The method was regioselective, chemoselective, and modular to establish this as a platform methodology for the functionalization of polyolefins using blue light irradiation. Hyperbranched polyethylene was thermally xanthylated, trithiocarbonylated, and dithiocarbamylated via an amidyl radical intermediate. The mechanism of C–H functionalization was deduced through kinetic and crossover experiments. The method was translated to semicrystalline polymers and ultimately to reacting within a twin-screw extruder, yielding 10 grams of xanthylated isotactic polypropylene. In this work, we report an approach to aliphatic C–H diversification via radical chain transfer featuring an easily prepared O–alkenylhydroxamate reagent, which upon mild heatingfacilitates a variety of valuable aliphatic C–H functionalizations. This method enabled the functionalization of a range of polyolefins via challenging and previously undeveloped C–H transformations. The simplicity and generality of this strategy constitute an ideal approach for the diversification of unactivated, aliphatic C–H bonds.Doctor of Philosoph

A Merged Aldol Condensation, Alkene Isomerization, Cycloaddition/Cycloreversion Sequence Employing Oxazinone Intermediates for the Synthesis of Substituted Pyridines

A domino reaction sequence has been evaluated that begins with union of novel dihydrooxazinone precursors with 2-alkynyl-substituted benzaldehyde components through aldol condensation. Ensuing operations, including alkene isomerization, Diels-Alder, and retrograde Diels-Alder with loss of CO2 occurs in the same reaction vessel to provide polysubstituted tricyclic pyridine products

Session 5: Banking, Capital Markets, and The Crypto Revolution - A Look Back and Projection of the Future of FinTech

In Session Five of the SITIE 2023 Symposium: Enabling Innovation in Law and Society, Joseph M. Vincent moderated as the four panelists, Joseph R. Cutler, Lawrence Kaplan, Youssef Sneifer, and Jill Williamson, discussed banking, capital markets, and the crypto revolution by looking back and projecting the future of the financial technology (FinTech) industry. The discussion commenced with a conversation on banking deposits, then moved into a discussion on cryptocurrency companies and the challenges they have faced in recent years in the banking industry. The panelists further discussed artificial intelligence (AI) technology’s impact on FinTech, open banking, and challenges facing cryptocurrency (crypto) going forward

Serotypes and Spa types of Erysipelothrix rhusiopathiae isolates from British pigs (1987 to 2015)

'Erysipelothrix' spp. cause a range of clinical signs in pigs and at least 28 different 'Erysipelothrix' spp. serotypes have been identified. In this study, 128 isolates of 'Erysipelothrix' spp. from pigs in Great Britain from 1987 to 2015 were characterised by serotyping and multiplex real time PCR assays targeting the surface protective antigen (Spa) and the main genotypes ('Erysipelothrix rhusiopathiae', 'Erysipelothrix tonsillarum' and 'Erysipelothrix' spp. strain 2). All 128 British isolates were characterised as 'E. rhusiopathiae' and were classified as serotypes 1a (n = 21), 1b (n = 17), 2 (n = 75), 5 (n = 2), 9 (n = 2), 10 (n = 2), 11 (n = 4) and 15 (n = 1), while four isolates were untypeable. All isolates were positive for the spa A gene. Serotypes 1a, 1b and 2 constituted 88.3% of the isolates; current serotype 2 based vaccines should protect against these isolates

Myelin Dynamics Throughout Life:An Ever-Changing Landscape?

Myelin sheaths speed up impulse propagation along the axons of neurons without the need for increasing axon diameter. Subsequently, myelin (which is made by oligodendrocytes in the central nervous system) allows for highly complex yet compact circuitry. Cognitive processes such as learning require central nervous system plasticity throughout life, and much research has focused on the role of neuronal, in particular synaptic, plasticity as a means of altering circuit function. An increasing body of evidence suggests that myelin may also play a role in circuit plasticity and that myelin may be an adaptable structure which could be altered to regulate experience and learning. However, the precise dynamics of myelination throughout life remain unclear – does the production of new myelin require the differentiation of new oligodendrocytes, and/or can existing myelin be remodelled dynamically over time? Here we review recent evidence for both de novo myelination and myelin remodelling from pioneering longitudinal studies of myelin dynamics in vivo, and discuss what remains to be done in order to fully understand how dynamic regulation of myelin affects lifelong circuit function

Upgrades to the International Space Station Urine Processor Assembly

The ISS Urine Processor Assembly (UPA) began operations in November 2008. Though the UPA has successfully generated distillate from crew urine, several modifications and upgrades have been implemented to improve overall system performance throughout the years. Current and future upgrades to the UPA will continue to focus on improved system performance and reliability, focusing primarily on the Distillation Assembly and upgrades to the UPA vacuum pump. Work towards a flight demonstration experiment of a vacuum pump utilizing scroll pump technologies has also continued forward. The following paper discusses progress on these various concepts, including the implementation of a more reliable drive belt, improved methods for managing condensate in the stationary bowl of the Distillation Assembly, installation of improved centrifuge bearings, implementation of a liquid level sensor, and upgrades to the UPA vacuum pump

Reflexiones a partir de un estudio sobre Educación Intercultural y Participación en Comunidades Mapuche en la Novena Región de La Araucanía, Chile.

This analysis focuses on a specific dimension of the "indigenous question" in Chile: that of social participation in educational processes, specifically within the context of the current national education reform. Beginning with new understandings based on the work of the Proyecto de Investigacin Desarrollo, Gestin Participativa en Educacin-Kelluwn, this paper analyzes the possibilities and limits of participation, considering the particular framework of institutional structures inherited from the Military Regime, characteristics of the education reform, and the context of current indigenous conflicts for territorial and political rights. The Proyecto Kelluwn, using methods of action research and based on the principles of Paulo Freire, developed diverse experiences oriented to the augmentation of action, dialogue, critical reflection and elevating the social power of the community as an actor able to confront the local government, the aim being the integration of Mapuche culture, language and cosmovision into the curriculum, pedagogy, organization and culture of local schools. Through the understandings generated in the process of engaged research, we interrogate the real possibilities of increasing effective participation in actual contexts--participation, social engagement aimed at attaining the objectives of the quality and equity sought by the current educational reform as well as the expansion of community rights sought by the Mapuche in Chile.El artículo analiza una dimensión particular de la "cuestión indígena" en Chile: la de la Participación Social en los procesos educacionales, particularmente en el contexto de la Reforma Educacional. A partir de los aprendizajes y descubrimientos del Proyecto de Investigación Desarrollo, Gestión Participativa en Educación-Kelluwün, analiza las posibilidades y límites a la participación, en el marco de la institucionalidad heredada del régimen militar, de las características de la Reforma Educacional, de los contextos de conflicto indígena por territorio y derechos políticos. El Proyecto Kelluwün, según principios de Paulo Freire, desarrolló, a través de Investigaciones Acción Participativas, diversas experiencias orientadas a aumentar la capacidad de acción, de interlocución, de reflexión crítica y el poder social de las comunidades frente al Gobierno Local buscando que su cultura, lengua y cosmovisión se integrara al curriculum, pedagogía, gestión y cultura escolar. A partir de los aprendizajes generados en este proceso se plantean interrogantes frente a la posibilidad real de que en el contexto actual, pueda efectivamente incrementarse la participación para alcanzar los objetivos de calidad y equidad que busca la Reforma Educacional y los de ampliación de derechos culturales que busca el pueblo mapuche

Status of ISS Water Management and Recovery

Water management on ISS is responsible for the provision of water to the crew for drinking water, food preparation, and hygiene, to the Oxygen Generation System (OGS) for oxygen production via electrolysis, to the Waste & Hygiene Compartment (WHC) for flush water, and for experiments on ISS. This paper summarizes water management activities on the ISS US Segment as of May 2018 and provides a status of the performance and issues related to the operation of the Water Processor Assembly (WPA) and Urine Processor Assembly (UPA)