Evidence for functional drift of bacterial isolates in response to cyanobacterial microcystin-lr and multiple peptide degradation in paucibacter toxinivorans.

Bacterial bioremediation has been proposed as an efficient, low cost and ecologically safe method to clean vital water reservoirs from cyanobacterial peptide toxins microcystins (MCs). In previous work carried out in 2008 several bacteria were isolated from Scottish freshwaters that effectively degraded MCs. Rhodococcus sp. C1, among the biocatalytic isolates, exhibited particular catabolic capacities as it degraded a range of chemically and structurally diverse prokaryotic and eukaryotic peptides. The work presented here aimed to unravel the universal peptide degradation mechanisms in Rhodococcus sp. C1. However, current biodegradation studies indicated repeated sub-culturing and long-term cryopreservation to have caused changes in the cellular mechanisms involved in MC-LR degradation as MC-LR degradation activity was no longer observed. Therefore, the focus of the study was shifted towards other isolates of the freshwater samples as well as a MC-LR degrading organism of unknown origin. Based on 16S rRNA gene analysis the isolates were identified as Rhodococcus sp., Arthrobacter sp. and Pseudomonas sp., respectively. The different bacterial genera were subjected to MC-LR biodegradation studies including Paucibacter toxinivorans (2007), a MC degrading bacterium from Finnish water previously used as positive control organism. However, it was shown that the three isolates and P. toxinivorans (2007) also lost their MC-LR degradation activity over long-term maintenance under laboratory conditions. This led to the belief that routine maintenance of the bacterial isolates in nutrient rich media such as Luria-Bertani (LB) broth had caused a functional drift that impeded the isolates ability to degrade MC-LR. To assess whether nutrient availability has an impact on the bacterial MC-LR degradation activity a simple and rapid 96-well plate based method was developed for testing MC-LR biodegradation in growth media of different nutrient concentration and composition. In addition to the long-term maintained and repeatedly sub-cultured strain of P. toxinivorans (2007) a new P. toxinivorans strain (2015) from the German Collection of Microorganisms and Cell Cultures was included in the nutrient assay. Comparison studies between the two strains supported the occurrence of a physiological drift in the repeatedly sub-cultured strain as cell morphology, oxidase activity and media tolerance of the strains were found to be different. The nutrient assay showed that the use of different growth media had little effect on MC-LR degradation activity of the long-term preserved bacteria. However, the newly obtained P. toxinivorans (2015) effectively removed MC-LR from all media except LB broth. Furthermore, UPLC-PDA-MS analysis revealed MC-LR intermediates in samples exposed to P. toxinivorans (2015). Two of the degradation products were identified as linearised (acyclo-) MC-LR and one as the side chain Adda. Broader investigation of the organisms catabolic abilities demonstrated P. toxinivorans (2015) is capable of degrading multiple MC variants, nodularin (NOD), anabaenopeptin-type peptides and human peptides. MC variants and NOD were found to be cleaved by hydrolysis indicating a single mechanism to be involved in their degradation. This is the first study to report partial elucidation of the MC and NOD degradation pathway in P. toxinivorans. Further research could include a complete elucidation of the enzymatic degradation pathway in P. toxinivorans (2015) along with studies to determine the genes encoding the enzymes involved

Engaging the Archive and Its Absences: Futures of Digital Scholarship and Teaching

Kelley specializes in nineteenth-century U.S. and Latin American literary studies, Latinx studies, digital humanities, and comparative media studies as an Assistant Professor of English at Pace University. In her research and teaching, she explores the role of media change past and present in enabling and inspiring shifts in the way we tell stories about current affairs. Kelley is also the co-founder and co-director of Babble Lab, a digital humanities center at Pace that seeks to reimagine how we teach the humanities through the use of data, design, and code and through the study of the new media of the present and the past. She is currently completing a book called Electrifying News: A Hemispheric History of the Present in Nineteenth-Century Print Culture

Operations Update DPAA

Copy of a reporthttps://digitalcommons.cwu.edu/sdfrancisco_documents/1046/thumbnail.jp

Microkinetic Investigation of the Transient Methanation of Carbon Dioxide on Ni Catalysts

Der Power-to-Gas (PtG) Prozess bietet die Chance erneuerbare Energien in Form von synthetischem Erdgas zu speichern. Im PtG-Prozess wird zunächst H2 mittels Wasserelektrolyse erzeugt, welches anschließend mit CO2 an einem Ni-Katalysator zu CH4 umgesetzt wird. Die fluktuierend anfallenden erneuerbaren Energien erzwingen einen dynamischen Betrieb, was die Entwicklung von toleranten Katalysatoren und Reaktoren erfordert, welche effizient unter den Bedingungen arbeiten. Reaktoren für die CO2 -Methanisierung werden mithilfe geeigneter Reaktormodelle ausgelegt, wobei stationäre kinetische Ansätze verwendet werden, bei denen alle Schritte eines Mechanismus in einer analytischen Gleichung zusammengefasst werden. Die Simulation des periodischen Betriebs eines mikrostrukturierten Reaktors auf der Grundlage einer solchen Kinetik zeigt eine starke Variation des Temperaturprofils und der Produktivität. Um die transienten Phänomene auf der Katalysatoroberfläche korrekt zu beschreiben ist es erforderlich Mikrokinetiken zu verwenden, wobei jeder Schritt des Reaktionsmechanismus berücksichtigt wird. Die Entwicklung einer Mikrokinetik für die CO2 -Methanisierung auf Ni-Katalysatoren erfolgt mit einer Kombination aus ab-initio Berechnungen und experimentellen Methoden. Zunächst werden verschiedene Ni/SiO2 und Ni/γ-Al2O3 Katalysatoren hergestellt und in dynamischen Methanisierungsexperimenten auf ihre Aktivität untersucht. CO2 zeigt vielfältige Wechselwirkungen mit den Ni-Katalysatoren, welche durch temperaturprogrammierten Desorptionsexperimenten (TPD) untersucht wurden. Diese TPD-Experimente zeigen, dass das Ni/SiO2 System für weitere kinetische Untersuchungen verwendet werden muss, da CO2 an basischen Zentren auf dem γ-Al2O3 Träger adsorbiert. Die Ni-Kristalle auf dem Katalysator bestehen aus einer Vielzahl an Kristallflächen, wohingegen mikrokinetische Modelle üblicherweise nur für eine einzelne Ebene ermittelt werden. Das Desorptionsspektrum von CO2 wurde mit einem mikrokinetischen Modell, basierend auf ab-initio Parametern und unter Berücksichtigung der Form eines realen Ni-Kristalls, reproduziert. Die Zusammensetzung des Ni-Kristalls aus den vier wichtigsten Ebenen wurde anhand einer Wulff-Konstruktion bestimmt. Kinetischen und thermodynamische Parameter des Models wurden mit Dichtefunktionaltheorie (DFT) Methoden berechnet. Die Unsicherheiten in den ab-initio Parametern werden in einer globalen Unsicherheitsanalyse bis zu den Simulationsergebnissen fortgepflanzt. Kombinationen an Parametern werden identifiziert, welche die Experimente mit guter Genauigkeit wiedergeben können. Diese Untersuchung zeigt, dass sich das TPD-Profil aus den einzelnen Kristallflächen zusammensetzt. Ni(111) trägt signifikant zum Desorptionsprofil bei und wird für die Entwicklung einer Mikrokinetik der CO2 -Methanisierung verwendet. Mikrokinetiken werden nicht von Hand mit DFT-Berechnungen erstellt, sondern mithilfe des "Reaction Mechanism Generator (RMG)", einer Software zur automatischen Konstruktion von Reaktionsnetzwerken. Dadurch werden alle möglichen Reaktionspfade berücksichtigt und der Mechanismus ist frei von den Erwartungen des Forschenden. Aufgrund der beträchtlichen Unsicherheit in den DFT-basierten Parametern wird diese direkt in der Generierung der Mechanismen berücksichtigt. 5000 mögliche Methanisierungsmechanismen werden in dem Bereich der Unsicherheiten generiert und analysiert. Alle erzeugten Mechanismen werden mit dynamischen Experimenten aus einem differentiellen Festbettreaktor und Berty-Reaktor in einem multiskalen Modell verglichen. Es existierten Kombinationen von ab-intio Modellparametern, welche die dynamischen Experimente mit bemerkenswerter Genauigkeit beschreiben können. Die Einbindung von Unsicherheiten in die automatische Generierung von Mechanismen und der multiskalen Modellierung liefert tiefgreifende Einblicke in den Reaktionsmechanismus der CO2 -Methanisierung auf Ni(111).Production of CH4 in the Power-to-Gas (PtG) process offers the chance to store renewable energies while producing sustainable natural gas. In the PtG process, the renewable energies are used to produce H2 via water electrolysis, which is subsequently converted with CO2 to CH4 over a Ni catalyst. The fluctuating nature of the renewable energy source imposes a transient operation, requiring the design of tolerant catalysts and reactors that can efficiently function under these conditions. CO2 methanation reactors are designed with reactor models, where closed-form rate expressions are used, which lump all elementary steps of a mechanism into an analytical equation. The simulation of the periodic operation of a microstructured reactor with such kinetics predicts ample variation in the temperature profile and productivity. This highlights the necessity for accurate and predictive kinetic approaches to describe the transient behavior of the methanation catalyst. Transient phenomena on the catalyst surface can only be quantified by detailed microkinetic models, where each elementary step of the methanation mechanism is considered. The investigation of the microkinetics for the CO2 methanation on Ni is accomplished with a combination of ab-initio electronic structure calculations and experimental methods. First, Ni/SiO2 and Ni/γ-Al2O3 catalysts were produced and screened for activity in transient methanation experiments to determine suitable catalysts for the development of the microkinetics. The interaction of CO2 with supported catalysts is challenging and was investigated with temperature-programmed desorption (TPD) experiments. These TPD experiments show that the Ni/SiO2 catalyst needs to be used because CO2 interacts with basic sites on the γ-Al2O3 support, overshadowing the interaction of CO2 with the Ni crystal. The Ni crystals on the support consist of a variety of exposed crystal facets, whereas microkinetic models are usually derived for a single crystal facet. This gap was bridged by comparing CO2 -TPD experiment with a first-principles-based microkinetic model considering the combination of the four most important Ni facets via a Wulff construction of the crystal. Energetic properties of the microkinetic model were derived with state-of-the-art density functional theory (DFT) methods. Propagation of the uncertainty in the DFT-derived parameters to the output of the model in a global uncertainty analysis revealed feasible sets with reasonable agreement with the data. This combination of experiments and multiscale modeling reveals that the multiple desorption peaks can be attributed to desorption from different Ni facets. Ni(111) contributes considerably to the desorption profile and is further considered in the development of a full microkinetic model for the CO2 methanation. Microkinetic models are not created by hand with DFT, but by using the Reaction Mechanism Generator (RMG), a software for the automated construction of reaction networks. Therefore, it is ensured that all the possible methanation chemistry is considered and the discovered reaction mechanism is not biased. Uncertainty quantification is directly included in the mechanism generation procedure because of the considerable uncertainty in DFT-derived parameters. 5,000 possible mechanisms within the uncertainty range were generated and analyzed. All generated microkinetics were compared to transient methanation experiments from a differential fixed-bed and a Berty reactor in a multiscale modeling approach. Feasible sets of ab-initio model parameters exists, which can describe the experiments with remarkable accuracy. This approach identifies the limitations of current DFT methods in elucidating the mechanism. The combination of uncertainty quantification in automated mechanism generation and multiscale modeling provides deep insights into the CO2 methanation mechanism on Ni(111)

Die Integration von Kindertagesbetreuung und Familienbildung in Chemnitz. Ergebnisse einer empirischen Untersuchung

Der vorliegende Bericht ist das Ergebnis einer in Chemnitz (Sachsen) durchgeführten Untersuchung der Ansprüche und Erwartungen von Eltern an Angebote der Familienbildung sowie der professionellen Perspektive auf die Verbindung von Kindertagesbetreuung, Elternarbeit an Kindertagesstätten und Familienbildung unter einem organisatorischen Dach in Form von Familienzentren. Methodisch wurden verschiedene Erhebungs- und Auswertungsverfahren eingesetzt. Im Rahmen einer schriftlichen Haushaltsbefragung mit Hilfe eines standardisierten Fragebogens wurde versucht, die derzeitige Nutzung von Familienbildungsangeboten und den Bedarf an solchen Angeboten festzustellen, aber auch Faktoren zu identifizieren, die eine Teilnahme verhindern. Weitere Teiluntersuchungen, bei denen mit Verfahren der ethnographischen Beobachtung, mit Gruppendiskussionen, Experteninterviews und biographisch-narrativen Interviews gearbeitet wurde, richteten sich darauf, Handlungsformen, Anforderungen und Perspektiven in Kindertageseinrichtungen und von Familienbildungsangeboten in Chemnitz herauszuarbeiten, um daraus Empfehlungen für die Einrichtung von Familienzentren zu formulieren. Die Untersuchung kommt zum Ergebnis, dass die Lokalisierung von Familienbildungsangeboten in bestehende Betreuungs- und Bildungseinrichtungen von Eltern gewünscht wird und Chancen zur Verbesserung der professionellen Arbeit eröffnet. Die Ansprüche an die Inhalte und die Struktur von Angeboten der Familienbildung verschieben sich mit dem Älterwerden der Kinder, den Lebenslagen der Adressaten und ihre Belastung durch kritische Lebensereignisse. Familienbildung sollte sich daher nicht auf Aspekte wie Schwangerschaft, Geburt und die ersten Lebensjahre des Kindes beschränken. (Autor

Catalytic Nanoparticle Additives in the Combustion of AP/HTPB Composite Solid Propellant

Presented in this thesis is a study of the effects of nano-sized particles used as a catalytic additive in composite solid propellant. This study was done with titanium oxide (titania)-based particles, but much of the findings and theory are applicable to any metal oxide produced by a similar method. The process required for efficiently producing larger batches of nanoparticle additives was seen to have a significant impact on the effectiveness of the additive to modify the burning rate of composite propellant consisting of ammonium perchlorate (AP) and hydroxyl terminated polybutadiene (HTPB). Specifically, titania was seen to be both an effective and ineffective burning rate modifier depending on how the nanoparticle additive was dried and subsequently heat treated. Nanoadditives were produced by various synthesis methods and tested in composite propellant consisting of 80 percent AP. Processability and scale-up effects are examined in selecting ideal synthesis methods of nanoscale titanium oxide for use as a burning rate modifier in composite propellant. Sintering of spray-dried additive agglomerates during the heat-treating process was shown to make the agglomerates difficult to break up during mixing and hinder the dispersion of the additive in the propellant. A link between additive processing, agglomerate dispersion mechanics and ultimately catalytic effect on the burning rate of AP/HTPB propellants has been developed by the theories presented in this thesis. This thesis studies the interaction between additive dispersion and the dispersion of reactions created by using fine AP in multimodal propellants. A limit in dispersion with powder additives was seen to cause the titania catalyst to be less effective in propellants containing fine AP. A new method for incorporating metal oxide nanoadditives into composite propellant with very high dispersion by suspending the additive material in the propellant binder is introduced. This new method has produced increases in burning rate of 50 to 60 percent over baseline propellants. This thesis reviews these studies with a particular focus on the application and scale-up of these nanoparticle additives to implement these additives in actual motor propellants and assesses many of the current problems and difficulties that hinder the nanoadditives’ true potential in composite propellant

Ouachita College Catalogue 1927-1928

https://scholarlycommons.obu.edu/catalogs/1053/thumbnail.jp