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<p> Under 248 nm laser flash photolysis, the photodecomposition of 1,3,4-trimethyl-1-phenyl-1-germacyclopent-3-ene (28) in dry, deoxygenated hexane solution at 23 °C leads to the prompt formation of two transient species: phenylmethylgermylene (29) and its Ge=Ge doubly bonded dimer, 1,2-dimethyl-1 ,2-diphenyldigemene (30). The formation of 29 proceeds in high chemical yield as shown by the results of steady state trapping experiments with methanol and isoprene. The transient assigned to 29 exhibits λmax = 490 nm and decays with second-order kinetics (τ ~ 2 μs). The second transient, which is formed from the latter, is assigned to digermene 30 and exhibits λmax = 420 nm and a lifetime, τ ~ 8 μs. The assignments are based on comparisons to the spectra of other simple germylenes, such as dimethyl-, diphenyl and dimesitylgermylene as well as on the pattern of reactivity with trapping reagents in solution at room temperature.</p> <p> Reactions studied include N-H, O-H and Sn-H insertion reactions, the [1+2] addition to isoprene and t-butylacetylene, and halogen atom abstraction from carbon tetrachloride.</p> <p> Absolute rate constants for quenching of 29 with the above mentioned scavengers were obtained by direct measurement of the germylene decay kinetics, over the concentration range where the formation of the digermene was more than 70% quenched. This ensures that the decay of 29 was dominated by the reaction with the trapping reagent.</p> <p> Absolute rate constants for reaction of the same reagents with 30 have also been determined for most of the scavengers studied. However, the digermene was found to be considerably less reactive than phenylmethylgermylene in all cases.</p> <p> The trends in spectroscopic properties and reactivity of simple germylenes in solution are discussed.</p> / Thesis / Master of Science (MSc)

In der perkutanen Strahlentherapie wird seit einiger Zeit am sogenannten FLASH-Effekt geforscht, bei welchem sich durch die Dosisapplikation in sehr kurzer Zeit bei ultrahohen Dosisleistungen verschiedene positive Effekte zeigten. In der Qualitätssicherung sind dafür präzise Dosismessgeräte nötig. Bisher verwendete Ionisationskammern zeigen jedoch bei ultrahohen Dosisleistungen Sättigungseffekte. Als Alternative wird eine faseroptische Sonde aus Berylliumoxid untersucht. Im Berylliumoxid werden durch ionisierende Strahlung über Radiolumineszenz Photonen emittiert. Die Anzahl der Photonen ist dabei proportional zur applizierten Dosis. In Protonenfeldern zeigte sich bei vorigen Messungen mit zunehmendem Massenbremsvermögen eine Dosisunterschätzung. Dieser Effekt ist bekannt und konnte bei konventionellen Bestrahlungsmethoden erfolgreich korrigiert werden. In dieser Arbeit wurden Experimente in Protonenfeldern erhöhter Dosisleistung durchgeführt, um die Verwendung von Berylliumoxid-Sonden bei FLASH-Bestrahlung zu untersuchen. Es stellte sich heraus, dass zusätzlich zum Massenbremsvermögen die Anzahl emittierter Photonen auch durch die Dosisleistung beeinflusst wird. Das erfordert eine zusammenhängende Korrekturfunktion. Außerdem zeigte sich ein weiterer Einflussfaktor, für welchen bisher keine Korrekturfunktion gefunden werden konnte. Bei Experimenten mit Kohlenstoff-Ionen fand sich ein unerwarteter Zusammenhang zwischen der Anzahl emittierter Photonen und der applizierten Dosis, sodass bisher eine Dosisbestimmung für Kohlenstoff-Ionen nicht möglich ist.

Experimental data are presented for the first time in support of a theoretical model of band broadening proposed by Blumberg (1997). This model addresses the effects of the compressibility of the mobile phase in gas chromatography and presents an equation derived from only two mutually independent variables. Solutions of decane and tridecane in hexane were analyzed at pressures ranging from 15 to 150 psi. Six different columns were used that varied in length, internal diameter and film thickness. Theoretical plate heights were obtained from this data and plotted versus the average linear carrier gas velocity (Golay type plots). These plots showed that at high pressures the Blumberg model fit the experimental data statistically significantly better than the earlier model proposed by Golay. The Blumberg model also accurately predicts the relationship between the optimum linear carrier gas velocity and the temperature. The second part of this work explores the scope and limitations of fast temperature programming in the fast GC analyses of various sample types. These samples included polycyclic aromatic hydrocarbons (PAHs), hydrocarbons and food samples. Programming rates of up to 1200° C/min were used. These fast programming rates were obtained by using "flash"â ¢ temperature programming, controlled by resistive heating of a metal tube that enclosed a capillary column. The precision of peak data was found to be good, less than 5% for peak areas and 4% for retention times. However, a slight, but statistically significant decrease in peak areas was seen above programming rates of 240° C/min. Microwave assisted extraction (MAE) was used to extract 2,6-di-(tert-butyl)-4-methylphenol, BHT, from chewing gum and breakfast cereal. The extraction was followed by a fast GC analysis (less than 4 minutes) using "flash"â ¢ temperature programming. MAE reduced the sample preparation time, from hours to minutes, and consequently reduced, the total analysis time. Extraction times longer than 5 minutes gave decreased recoveries of BHT. / Ph. D.

Continuously increasing demand for faster project delivery of emergency and non-emergency projects, project complexity, and pandemic caused price escalations and material shortages requiring real time pricing and use of available equipment are showing that construction industry needs to shift toward creating designs that will be driven by the construction process or construction-driven designs. The construction-driven designs enable faster than fast project delivery or flash tracking by adopting the mindset that construction is the last phase of the design and by integrating the building approach with the design where the means and methods of construction drive the design development process. However, the development of such designs requires the involvement of the key stakeholders such as contractor, major subcontractors and equipment vendors, and operations and maintenance personnel at the appropriate time in the design. This research presents the framework which addresses the key areas needed to develop construction-driven designs such as (1) formalizing the construction-driven design definition; (2) determining construction-driven design characteristics and the preferred level and timing of involvement of the key stakeholders (contractor, major subcontractor, major equipment vendor, and operations and maintenance personnel) in the design development process; (3) determining key stakeholder’s (contractor, designer, and owner) experience requirements for the successful development and execution of construction-driven designs; (4) identifying potential contractual, licensure, and insurance barriers that can affect contractor’s early involvement in the design and providing recommendations to overcome those barriers; (5) ranking project delivery methods based on their effectiveness and suitability to develop and implement construction-driven designs; (6) identifying and ranking the best practices specific to construction-driven designs; and (7) providing a tool that will allow a company or a project team to measure their readiness to develop a construction-driven design for a project. / Ph.D. / Continuously increasing demand for faster project delivery of emergency and non-emergency projects, project complexity, and rising prices and material shortages caused by pandemic require real time pricing and use of available equipment. Moreover, these issues are showing that construction industry needs to shift toward creating designs that are constructible and led by the means and methods of construction or construction-driven designs. The construction-driven designs enable faster than fast project delivery by adopting the mindset that construction is the last phase of the design and by integrating the building approach with the design process where the means and methods of construction influence and guide the design development process. However, the development of such designs requires the involvement of the key stakeholders such as contractor, major subcontractors and equipment vendors, and operations and maintenance personnel at the appropriate time in the design. This research presents the framework which addresses the key areas needed to develop construction-driven designs such as (1) formalizing the construction-driven design definition; (2) determining construction-driven design characteristics and the preferred level and timing of involvement of the key stakeholders (contractor, major subcontractor, major equipment vendor, and operations and maintenance personnel) in the design development process; (3) determining key stakeholder’s (contractor, designer, and owner) experience requirements for the successful development and execution of construction-driven designs; (4) identifying potential contractual, licensure, and insurance barriers that can affect contractor’s early involvement in the design and providing recommendations to overcome those barriers; (5) ranking project delivery methods based on their effectiveness and suitability to develop and implement construction-driven designs; (6) identifying and ranking the best practices specific to construction-driven designs; and (7) providing a tool that will allow a company or a project team to measure their readiness to develop a construction-driven design for a project.

En las últimas décadas, los procesos redox fotoinducidos mediados por luz visible han recibido gran atención debido a las suaves condiciones de operación en que se llevan a cabo. Como resultado, se han logrado posicionar como una alternativa más dentro de los Procesos de Oxidación Avanzada. Además, se han convertido en una metodología excepcional en síntesis orgánica, que ha abierto la puerta a nuevas rutas químicas con aplicaciones sintéticas. Sin embargo, a pesar del crecimiento del campo, se ha prestado poca atención a los mecanismos por los que operan estos procesos. El principal objetivo de esta tesis fue avanzar en la comprensión de distintos procesos fotoredox llevados a cabo empleando fotocatalizadores orgánicos. Más específicamente, se estudió la viabilidad de distintos fotocatalizadores orgánicos, y además, se realizó un estudio mecanístico detallado basado en técnicas resueltas en el tiempo. A partir de estos resultados, se estableció una metodología para determinar los puntos clave a considerar en un sistema fotoredox. En primer lugar, en la Parte I, se eligieron dos fotocatalizadores basados en sales de pirilio y tiapirilio, que operan mediante transferencia electrónica oxidativa, con distintos objetivos. En el Capítulo 3, se evaluó su aplicabilidad en la fotodegradación de dos contaminantes de la industria del corcho y se estudió el mecanismo por el que se produce dicha fotodegradación. En el Capítulo 4, se demostró la utilidad de la detección directa de todos los intermedios de vida corta derivados del TPP+ implicados en la oxidación fotocatalizada como herramienta para evaluar el nivel de fotodegradación. En el Capítulo 5, se empleó TPTP+ para establecer las mejores características de un fotocatalizador y la influencia de la concentración de las sustancias a oxidar en la eficiencia de los estados excitados, o en general, de los intermedios clave de vida corta. En segundo lugar, en la Parte II, en el Capítulo 6, se evaluó el potencial del Rosa Bengala en la eliminación de dos fármacos. Éste es un fotocatalizador típico en la remediación de aguas residuales conocido por actuar via mecanismo Tipo II. Se incluyó además un segundo fotocatalizador, Perinaftenona, cuyo rendimiento cuántico de oxígeno singlete es incluso mayor a Rosa Bengala. En el Capítulo 7, se llevó a cabo la fotooxidación de tres contaminantes, usando NMQ+, un fotocatalizador inusual, capaz de generar oxígeno singlete desde su estado excitado singlete. En todos los casos se pudo demostrar la mayor contribución del mecanismo Tipo I sobre el mecanismo Tipo II en la fotodegradación de los diferentes contaminantes. Finalmente, en la Parte II, el Capítulo 8 se dedicó a la reducción fotocatalítica de bromuros orgánicos, empleando Riboflavina, un colorante orgánico no metálico, como fotocatalizador. De nuevo, se prestó especial atención a la detección y comportamiento de las especies intermedias, lo que resultó de acuerdo a los datos termodinámicos. / En les últimes dècades, els processos redox fotoinduïts mitjan per llum visible han rebut gran atenció degut a les suaus condicions d'operació en que es donen. Com a resultat, s'han aconseguit col·locar com una alternativa mes dins dels Processos d'Oxidació Avançada. A més, han estat convertint-se en una metodologia excepcional en síntesi orgànica, que ha obert la porta a noves rutes químiques amb aplicacions sintètiques. No obstant això, a pesar del creixement del camp, s'ha prestat poca atenció als mecanismes pels que operen aquests processos. El principal objectiu d'esta tesi va ser avançar en la comprensió de diferents processos fotoredox duts a terme emprant fotocatalitzadors orgànics. Més específicament, es va estudiar la viabilitat de distints fotocatalitzadors orgànics, i a més, es va realitzar un estudi mecanístic al detall basat en tècniques resoltes en el temps. Amb aquests resultats, es va establir una metodologia per a determinar els punts clau a considerar en un sistema fotoredox. En primer lloc, en la Part I, es van elegir dos fotocatalitzadors basats en sals de pirili i tiapirili, els quals operen per mitjà de transferència electrònica oxidativa, amb distints objectius. En el Capítol 3, es va avaluar la seua aplicabilitat en la fotodegradació de dos contaminants de la indústria del suro i es va estudiar el mecanisme pel qual es produeix dita fotodegradació. En el Capítol 4, es va demostrar la utilitat de la detecció directa de tots els intermedis de curt temps de vida derivats del TPP+ implicats en l'oxidació fotocatalitzada com a ferramenta per avaluar el nivell de fotodegradació. En el Capítol 5, es va emprar TPTP+ per a establir les millors característiques d'un fotocatalitzador i l'influencia de la concentració de les substàncies a oxidar en la eficiència dels estats oxidats, o en general, del intermedis claus de vida curta. En segon lloc, en la Part II, en el Capítol 6, es va avaluar el potencial del Rosa Bengala en l'eliminació de dos fàrmacs. Aquest es un fotocatalitzador típic en la remediació d'aigües residuals conegut per actuar via mecanisme Tipus II. Es va incloure a més un segon fotocatalitzador, Perinaftenona, el del qual rendiment quàntic d'oxigen singlet és inclús major a Rosa Bengala. En el Capítol 7, es va dur a terme la fotooxidació de tres contaminants, usant NMQ+, un fotocatalitzador inusual, capaç de generar oxigen singlet des del seu estat excitat singlet. En tots els casos es va poder demostrar la major contribució del mecanisme Tipus I sobre el mecanisme Tipo II en la fotodegradació dels diferents contaminants. Finalment, en la Part II, el Capítol 8 es va dedicar a la reducció fotocatalítica de bromurs orgànics, emprant Riboflavina, un colorant orgànic no metàl·lic, com fotocatalitzador. De nou, es va prestar especial atenció a la detecció i comportament de les espècies intermèdies, el que va resultar d'acord amb les dades termodinàmiques. / In the last decades, photoinduced-redox processes mediated through visible light have obtained great attention due to the generally mild operating conditions that they offer. As a result, they constitute a further alternative within the so-called Advanced Oxidation processes. Besides, they are becoming an outstanding methodology in organic synthesis, which has opened the door to new synthetic and chemical routes. However, despite the growth of the field, little attention has been paid to the mechanisms pathways behind these processes. The main objective of this thesis was to gain deeper understanding of different photoredox processes carried out using organic photocatalysts. More specifically, the viability of several organic photocatalysts was studied, and besides, a careful mechanistic study based on time resolved techniques supported the postulated mechanisms. With this information, a methodology determining the key points to consider in a photoredox system were stablished. Firstly, in Part I, two photocatalysts based on pyrilium and thiapyrilium salts, which operate through an oxidative electron transfer, have been used with different objectives. In Chapter 3, the viability of the photodegradation of two common pollutants from cork industry and the mechanism behind it has been evaluated. In Chapter 4, the direct detection of all the TPP+ derived short-lived intermediates in the photocatalyzed oxidation of a mixture of pollutants using TPP+ was proposed as a methodology to assess the photodegradation extent. In the last chapter of Part I, Chapter 5, TPTP+ is used to stablish the best characteristics of a photocatalyst. Besides, the study claimed the influence of the concentration of the target substances in the efficiency of the excited states or, in general, of the key short-lived intermediates. Secondly, in Part II, in Chapter 6, Rose Bengal, a typical photocatalyst used in wastewater remediation, known for working via Type II mechanism, was evaluated for the removal of two common drugs. In addition, a second one, Perinaphtenone, which exhibits even a higher singlet oxygen quantum yield than Rose Bengal was tested. In Chapter 7, NMQ+, a non-typical photocatalyst able of generate singlet oxygen from its singlet excited state, was used in the photooxidation of three different pollutants. In every case, the major contribution of Type I vs Type II mechanism was demonstrated. Finally, in Part III, Chapter 8 was devoted to the photocatalytic reduction of organic bromides. In this case, Riboflavine, a non-metallic organic dye, was used as a photocatalyst. Analogously, careful attention was paid to the behavoiur of the intermediates, which were in agreement, as well as to the thermodynamics of the steps involved in the photocatalytic cycle. / Martínez Haya, R. (2018). Photoredox catalysis for environmental and chemical applications. A mechanistically-based approach [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/114828

Yes / Multistage Flash (MSF) desalination process is still a dominant process, especially in the Gulf region, to produce high quality freshwater. Although there has been energy price surge in recent years, MSF process will continue to operate in that region for some foreseeable future. The key challenge is how to make such processes still profitable. Understanding the dynamics of any processes under uncertainty and disturbances is very important to make a process operationally feasible and profitable. The main aim of this work is to understand the dynamics of industrial scale MSF process using high fidelity and reliable process model. For this purpose, a detailed dynamic model for the MSF process incorporating key and new features is developed and validated against the actual data of a large-scale seawater desalination plant. The model is then used to study the behaviour of large scale MSF processes for disturbances in steam temperature, feed temperature and the recycle brine flow rate. The simulation results show that the last stage requires a longer time to settle compared to the preceding stages. In addition, steam temperature shows insignificant influence on the performance ratio compared to the inlet seawater temperature and recycle brine flow rate. Furthermore, it is found that the productivity of plant can increase in the winter compared to that in the summer. However, this benefit comes at the expense of increased steam consumption in the winter, resulting in a low performance ratio.

The growing disparity in data storage and retrieval needs of modern applications is driving the proliferation of a wide variety of storage systems (e.g., key-value stores, cloud storage services, distributed filesystems, and flash cache, etc.). While extant storage systems are designed and tuned for a specific set of applications targeting a range of workload characteristics, they lack the flexibility in adapting to the ever-changing workload behaviors. Moreover, the complexities in implementing modern storage systems and adapting ever-changing storage requirements present unique opportunities and engineering challenges. In this dissertation, we design and develop a series of novel data management and storage systems solutions by applying a simple yet effective rule---workload awareness. We find that simple workload-aware data management strategies are effective in improving the efficiency of modern storage systems, sometimes by an order of magnitude. The first two works tackle the data management and storage space allocation issues at distributed and cloud storage level, while the third work focuses on low-level data management problems in the local storage system, which many high-level storage/data-intensive applications rely on. In the first part of this dissertation (Chapter 3), we propose and develop MBal, a high-performance in-memory object caching framework with adaptive multi-phase load balancing, which supports not only horizontal (scale-out) but vertical (scale-up) scalability as well. MBal is able to make efficient use of available resources in the cloud through its fine-grained, partitioned, lockless design. In the second part of this dissertation (Chapter 4 and Chapter5), we design and build CAST (Chapter 4), a Cloud Analytics Storage Tiering solution that cloud tenants can use to reduce monetary cost and improve performance of analytics workloads. The approach takes the first step towards providing storage tiering support for data analytics in the cloud. Furthermore, we propose a hybrid cloud object storage system (Chapter 5) that could effectively engage both the cloud service providers and cloud tenants via a novel dynamic pricing mechanism. In the third part of this dissertation (Chapter 6), targeting local storage, we explore offline algorithms for flash caching in terms of both hit ratio and flash lifespan. We design and implement a multi-stage heuristic by synthesizing several techniques that manage data at the granularity of a flash erasure unit (which we call a container) to approximate the offline optimal algorithm. In the fourth part of this dissertation (Chapter 7), we are focused on how to enable fast prototyping of efficient distributed key-value stores targeting a proxy-based layered architecture. In this work, we design and build {con}, a framework that significantly reduce the engineering effort required to build a full-fledged distributed key-value store. Our dissertation shows that simple workload-aware data management strategies can bring huge benefit in terms of both efficiency (i.e., performance, monetary cost, etc.) and flexibility (i.e., ease-of-use, ease-of-deployment, programmability, etc.). The principles of leveraging workload dynamicity and storage heterogeneity can be used to guide next-generation storage system software design, especially when being faced with new storage hardware technologies. / Ph. D. / Modern storage systems often manage data without considering the dynamicity of user behaviors. This design approach does not consider the unique features of underlying storage medium either. To this end, this dissertation first studies how the combinational factors of random user workload dynamicity and inherent storage hardware heterogeneity impact the data management efficiency. This dissertation then presents a series of practical and efficient techniques, algorithms, and optimizations to make the storage systems workload-aware. The experimental evaluation demonstrates the effectiveness of our workload-aware design choices and strategies.

Dream Machine is a collection which constructs a body of contemporary mythology, grappling with themes of American paranoia, online identity formation, and bodily alienation. Stories such as "Offerings" and "Pareidolia" explore the digital commodification of the body, following characters who—through Instagram-sourced sugar daddies and nude art modeling, respectively—offer themselves up freely as subjects of voyeurism and surveillance. Other stories, such as "Network Support" and "Dream Machine" involve characters who abandon their physical forms to disappear into the internet, existing as free-floating data and radiant frequencies. "Downstream," "Grass So Green," and "Little White Crosses" engage with the stark landscape of a country starved of its spirituality, where conspiracies, hallucinations, and deathly apparitions seem to possess the same inherent logic as a blue sky. / Master of Fine Arts / Dream Machine is a short story collection.

CONK is a collection that explores the absurdist irony located at the intersection between horror and humor. The events are predicated upon the characters' fundamental misunderstandings of the world around them, their doom arising from their inability to differentiate between the indecipherable and the incorrect ("Bird Kill"). Some are more reflexive, revolving around the difficulty of telling a story at all ("What a Story''), or exploring the dissolution of self that results from the act of artmaking (the eponymous "CONK"), or even indulging in the joy of said dissolution ("Celebration"). Other times, the pieces mix esoteric language and pop culture referents with the goal of defamiliarizing them ("Will That Be All?"). The resulting destabilization, this breakdown of heuristic methodology, creates situations that resist understanding and renders uncanny previously mundane images. / Master of Fine Arts / CONK is a collection of short fiction.