Experimental investigations and modeling of S(IV)-species in the absorption of SO2 in seawater-like electrolyte solutions

Ziel dieser Arbeit war es, die Absorptionskapazität von Meerwassersole als Waschmittel in der Rauchgasentschwefelung zu untersuchen. Dazu wurden Versuche in unterschiedlichen Elektrolytlösungen durchgeführt, um Parameter des Pitzer-Modells zu bestimmen. Mit dem angepassten thermodynamischen Modell kann die Absorptionsfähigkeit verschiedener Elektrolytlösungen, im speziellen Meerwasser und Meerwassersole, vorhergesagt werden. Anhand der Gleichgewichtsdaten aus Absorptionsmessungen in binären Salzsystemen bei 25 °C wurde der Einfluss der verschiedenen Salze auf die Absorptionskapazität herausgearbeitet. Anschließend an die Versuche in den binären Systemen wurden ausgewählte Wechselwirkungsparameter des Pitzer-Modells angepasst, um die thermodynamische Beschreibung der Absorptionskapazität zu verbessern. Die in den binären Systemen angepassten Parameter wurden zu einem Modell zusammengefasst, mit dem die SO2-Absorptionsversuche in den komplexen Systemen Meerwasser und Meerwassersole bei 25 °C beschrieben wurden. Dabei wurde deutlich, dass die binären Parameter alleine die komplexen Systeme nicht beschreiben konnten. Es wurden daher ausgewählte ternäre Wechselwirkungsparameter angepasst, um eine thermodynamische Beschreibung des Absorptionsgleichgewichts in allen untersuchen Elektrolytlösungen zu erzielen. Da sich in industriellen Absorptionsprozessen zumeist Kühlgrenztemperaturen von 40 - 60 °C einstellen, wurde die Güte des thermodynamischen Modells auch in diesem Temperaturbereich untersucht. Dazu wurden sowohl die binären als auch die komplexen Systeme bei 50 °C vermessen und mit dem angepassten Modell beschrieben. Des Weiteren konnte in dieser Arbeit mittels UV-spektroskopischen Untersuchungen ein Einblick in die Speziesverteilung der Schwefel-(IV)-Spezies in der Flüssigphase gewonnen werden. Weitere Untersuchungen der aufgenommenen Extinktionsspektren ermöglichten eine Ermittlung der Extinktionskoeffizienten aller gelösten Schwefel-(IV)-Spezies in der Flüssigphase. Abschließend wurden Auswertemethoden entwickelt, mit denen die Spezieskonzentrationen in der Flüssigphase UV-spektroskopisch bestimmt werden können, ohne dabei auf eine thermodynamische Berechnung zurückgreifen zu müssen. Mit diesen Verfahren können beispielsweise Oxidations- oder Absorptionskinetiken deutlich genauer untersucht werden.In this work the absorption capacity of seawater brine is systematically investigated and discussed for the use in flue gas purification processes. Therefore, experiments were performed in various electrolyte solutions to optimize parameters of the pitzer model. With the adjusted thermodynamic model the absorption capacity of different electrolyte solutions, in particular seawater and brined, can be predicted. Based on equilibrium data of absorption experiments in binary salt systems at 298 K, the influence of different salts on the absorption capacity had been determined. Following to the experiments in binary-systems, selected parameters of the pitzer model were adjusted to improve the thermodynamic description of the absorption capacity. These parameters were combined into a model to describe the absorption experiments in the complex seawater and brine systems at 25 °C. It became evident that the use of optimized binary parameters only does not provide a sufficiently accurate description of the complex systems. Therefore, selected ternary interaction parameters were adjusted to achieve a more accurate thermodynamic description of the absorption equilibrium in all investigated electrolyte solutions. Industrial absorption processes run at temperatures of 313 – 333 K, so the quality of the thermodynamic model was also tested in this temperature range. The binary and complex systems were measured at 323 K and described with the fitted model. Furthermore, an insight into the distribution of the sulfur (IV) species in the liquid phase could be obtained in this work by uv spectroscopic measurements. Investigations of the recorded absorbance spectra allowed a determination of the extinction coefficients of all dissolved sulfur (IV) species. Finally, evaluation methods have been developed with which the species concentrations can be determined in the liquid phase by uv spectroscopy without needing to resort to a thermodynamic calculation

Nietzsche, Dionysus, and the Ontology of Music

This essay examines Nietzsche’s musical ontology and situates it within the naturalist and anti-metaphysical framework evident throughout his corpus. Nietzsche often associated this position with the figure of Dionysus, which plays a leading role in The Birth of Tragedy, his most sustained consideration of music and musical ontology. The essay returns to The Birth of Tragedy in an effort to recover Nietzsche’s musical ontology and its relationship with ontology more generally. Heeding Nietzsche’s own remarks, I read this text in light of his mature philosophy. My analysis draws on the work of the late twentieth-century Nietzschean, Gilles Deleuze, whose distinction between “the virtual” and “the actual” enables us to see what is really at issue in The Birth of Tragedy

Crumbling Crystals: On the Dissolution Mechanism of NaCl in Water

Life on Earth depends upon the dissolution of ionic salts in water, particularly NaCl. However, an atomistic scale understanding of the process remains elusive. Simulations lend themselves conveniently to studying dissolution since they provide the spatio-temporal resolution that can be difficult to obtain experimentally. Nevertheless, the complexity of various inter- and intra-molecular interactions require careful treatment and long time scale simulations, both of which are typically hindered by computational expense. Here, we use advances in machine learning potential methodology to resolve for the first time at an ab initio level of theory the dissolution mechanism of NaCl in water. The picture that emerges is that of a steady ion-wise unwrapping of the crystal preceding its rapid disintegration, reminiscent of crumbling. The onset of crumbling can be explained by a strong increase in the ratio of the surface to volume of the crystal. Overall, dissolution is comprised of a series of highly dynamical microscopic sub-processes, resulting in an inherently stochastic mechanism. These atomistic level insights now pave the way for a general understanding of dissolution mechanisms in other crystals, and the methodology is primed for more complex systems of recent interest such as water/salt interfaces under flow and salt crystals under confinement

Aura Satz in conversation with Christoph Cox, April/May 2017

A conversation between Aura Satz and Christoph Cox, exploring sirens and emergency signals, acoustic ecology, and economies of attention. Aura Satz is a film-maker and sound artist who has performed, exhibited and screened her work nationally and internationally, including at Tate Modern; Oberhausen Short Film Festival (Oberhausen); the Rotterdam Film Festival (Rotterdam); the New York Film Festival (NY); Gallery 44 (Toronto); InterCommunication Centre (Tokyo) and the Sydney Biennale. In 2012, she was shortlisted for the Samsung Art+ Award and the Jarman Award. She teaches at the Royal College of Art, London. She was in conversation with Christoph Cox, a philosopher, critic, and curator who teaches at Hampshire College in Amherst, Massachusetts. He is the author of Sonic Flux: Sound, Art, and Metaphysics (University of Chicago Press, forthcoming) and Nietzsche: Naturalism and Interpretation (University of California Press, 1999), and co-editor of Realism Materialism Art (Sternberg, 2015) and Audio Culture: Readings in Modern Music (Continuum, 2004/Bloomsbury, 2017). Cox is editor-at-large at Cabinet magazine. His writing has appeared in numerous journals including October, Artforum, Journal of the History of Philosophy, Journal of Visual Culture, The Review of Metaphysics. He has curated exhibitions at the Contemporary Arts Museum Houston, The Kitchen, CONTEXT Art Miami and other venues

Discovery Mechanisms for the Sensor Web

This paper addresses the discovery of sensors within the OGC Sensor Web Enablement framework. Whereas services like the OGC Web Map Service or Web Coverage Service are already well supported through catalogue services, the field of sensor networks and the according discovery mechanisms is still a challenge. The focus within this article will be on the use of existing OGC Sensor Web components for realizing a discovery solution. After discussing the requirements for a Sensor Web discovery mechanism, an approach will be presented that was developed within the EU funded project “OSIRIS”. This solution offers mechanisms to search for sensors, exploit basic semantic relationships, harvest sensor metadata and integrate sensor discovery into already existing catalogues

Substrate selectivity of an isolated enoyl reductase catalytic domain from an iterative highly reducing fungal polyketide synthase reveals key components of programming

A cis-acting enoyl reductase (ER) catalytic domain was isolated from a fungal highly reducing iterative polyketide synthase (HR-iPKS) for the first time and studied in vitro. The ER from the squalestatin tetraketide synthase forms a discrete dimeric protein in solution. The ER shows broad substrate selectivity, reducing enoyl species including both natural and unnatural substrates. Pantetheine-bound substrate thiolesters reacted much faster than the corresponding SNAC thiolesters. The unnatural substrates included Z-olefins, 2-ethyl olefins and pentaketides. Methylation of the substrate modifies the activity of the ER such that the 2,4-dimethyl oct-2-enoyl substrate fits into the active site but cannot be reduced. A new NMR-based assay was developed for the direct observation of the stereochemical preferences at the 4′ position of the NADPH cofactor and the C-2 and C-3 positions of the substrates. The assay reveals that the fungal iPKS ER-catalysed reaction is stereochemically identical to that of the vertebrate FAS (vFAS) at the cofactor 4′ position and the substrate 3-position, but the high stereoselectivity displayed by intact SQTKS is lost such that reprotonation at the 2-position is unselective by the isolated ER. A 3D model of ER was consistent with these observations and showed that the ER may sequester its final substrate to prevent further chain extension. The results support a developing model for programming by HR-iPKS in which competition for substrates between restrictive and permissive catalytic domains chaperones the growing polyketide to completion, while allowing for errors and evolution

'Introduction'

Realism Materialism Art (RMA) presents a snapshot of the emerging and rapidly changing set of ideas, practices, and challenges proposed by contemporary realisms and materialisms, re ecting their nascent reworking of art, philosophy, culture, theory, and science, among other elds. Further, RMA strives to expand the hori- zons and terms of engagement with realism and materialism beyond the primarily philosophical context in which their recent developments have taken place, often under the title “Speculative Realism” (SR). While it is SR that has most stridently challenged critical orthodoxies (even if, as discussed later in this introduction, the positions convened under the SR banner are often discordant and form no uni ed movement), RMA purposefully looks to extend the purview of realist and materialist thought by presenting recent developments in a number of distinct and heteroge- neous practices and disciplines. Cutting across diverse thematic interests and modes of investigation, the con- tributions to RMA demonstrate the breadth and challenge of realist and materialist approaches to received disciplinary categories and forms of practice. This pluridis- ciplinarity is typical of the third term in our title: art. RMA a rms, as art now does, that there is no privileged area, thematic, or discipline in the investigation or reach of realism and materialism: not philosophy, not science, not even art itself. Art is then not just a eld trans gured by realism and materialism; it is also a method for convening and extending what they are taken to be and do when extended beyond philosophical argument

Urology consultants versus large language models : potentials and hazards for medical advice in urology

Background Current interest surrounding large language models (LLMs) will lead to an increase in their use for medical advice. Although LLMs offer huge potential, they also pose potential misinformation hazards. Objective This study evaluates three LLMs answering urology-themed clinical case-based questions by comparing the quality of answers to those provided by urology consultants. Methods Forty-five case-based questions were answered by consultants and LLMs (ChatGPT 3.5, ChatGPT 4, Bard). Answers were blindly rated using a six-step Likert scale by four consultants in the categories: ‘medical adequacy’, ‘conciseness’, ‘coherence’ and ‘comprehensibility’. Possible misinformation hazards were identified; a modified Turing test was included, and the character count was matched. Results Higher ratings in every category were recorded for the consultants. LLMs' overall performance in language-focused categories (coherence and comprehensibility) was relatively high. Medical adequacy was significantly poorer compared with the consultants. Possible misinformation hazards were identified in 2.8% to 18.9% of answers generated by LLMs compared with <1% of consultant's answers. Poorer conciseness rates and a higher character count were provided by LLMs. Among individual LLMs, ChatGPT 4 performed best in medical accuracy (p < 0.0001) and coherence (p = 0.001), whereas Bard received the lowest scores. Generated responses were accurately associated with their source with 98% accuracy in LLMs and 99% with consultants. Conclusions The quality of consultant answers was superior to LLMs in all categories. High semantic scores for LLM answers were found; however, the lack of medical accuracy led to potential misinformation hazards from LLM ‘consultations’. Further investigations are necessary for new generations.Peer reviewe

From Ideas to Practice, Pilots to Strategy: Practical Solutions and Actionable Insights on How to Do Impact Investing

This report is the second publication in the World Economic Forum's Mainstreaming Impact Investing Initiative. The report takes a deeper look at why and how asset owners began to include impact investing in their portfolios and continue to do so today, and how they overcame operational and cultural constraints affecting capital flow. Given that impact investing expertise is spread among dozens if not hundreds of practitioners and academics, the report is a curation of some -- but certainly not all -- of those leading voices. The 15 articles are meant to provide investors, intermediaries and policy-makers with actionable insights on how to incorporate impact investing into their work.The report's goals are to show how mainstream investors and intermediaries have overcome the challenges in the impact investment sector, and to democratize the insights and expertise for anyone and everyone interested in the field. Divided into four main sections, the report contains lessons learned from practitioner's experience, and showcases best practices, organizational structures and innovative instruments that asset owners, asset managers, financial institutions and impact investors have successfully implemented

Toric Construction of Global F-Theory GUTs

We systematically construct a large number of compact Calabi-Yau fourfolds which are suitable for F-theory model building. These elliptically fibered Calabi-Yaus are complete intersections of two hypersurfaces in a six dimensional ambient space. We first construct three-dimensional base manifolds that are hypersurfaces in a toric ambient space. We search for divisors which can support an F-theory GUT. The fourfolds are obtained as elliptic fibrations over these base manifolds. We find that elementary conditions which are motivated by F-theory GUTs lead to strong constraints on the geometry, which significantly reduce the number of suitable models. The complete database of models is available at http://hep.itp.tuwien.ac.at/f-theory/. We work out several examples in more detail.Comment: 35 pages, references adde