The use of the ion probe mass spectrometer in the measurement of hydrogen concentration gradients in Monel K 500

The ion probe mass spectrometer was used to measure hydrogen concentration gradients in cathodically charged Monel K 500. Initial work with the ion probe involved the calibration of the instrument and the establishment of a suitable experimental procedure for this application. Samples of Monel K 500 were cathodically charged in a weak sulfuric acid solution. By varying the current density, different levels of hydrogen were introduced into the samples. Hydrogen concentration gradients were taken by ion sputtering on the surface of these samples and monitoring the behavior of the hydrogen mass peak as a function of time. An attempt was made to determine the relative amounts of hydrogen in the bulk and grain boundaries by analyzing a fresh fracture surface with a higher proportion of grain boundary area. It was found that substantially more hydrogen was detected in the grain boundaries than in the bulk, confirming the predictions of previous workers. A sputter rate determination was made in order to establish the rate of erosion

Surface aspects of pitting and stress corrosion cracking

The pitting and stress corrosion cracking of a stable austenitic stainless steel in aqueous chloride environments were investigated using a secondary ion mass spectrometer as the primary experimental technique. The surface concentration of hydrogen, oxygen, the hydroxide, and chloride ion, magnesium or sodium, chromium and nickel were measured as a function of potential in both aqueous sodium chloride and magnesium chloride environments at room temperature and boiling temperatures. It was found that, under anodic conditions, a sharp increase in the chloride concentration was observed to occur for all environmental conditions. The increase may be associated with the formation of an iron chloride complex. Higher localized chloride concentrations at pits and cracks were also detected with an electron microprobe

FGB1 and WSC3 are in planta-induced beta-glucan-binding fungal lectins with different functions

In the root endophyte Serendipita indica, several lectin-like members of the expanded multigene family of WSC proteins are transcriptionally induced in planta and are potentially involved in beta-glucan remodeling at the fungal cell wall. Using biochemical and cytological approaches we show that one of these lectins, SiWSC3 with three WSC domains, is an integral fungal cell wall component that binds to long-chain beta 1-3-glucan but has no affinity for shorter beta 1-3- or beta 1-6-linked glucose oligomers. Comparative analysis with the previously identified beta-glucan-binding lectin SiFGB1 demonstrated that whereas SiWSC3 does not require beta 1-6-linked glucose for efficient binding to branched beta 1-3-glucan, SiFGB1 does. In contrast to SiFGB1, the multivalent SiWSC3 lectin can efficiently agglutinate fungal cells and is additionally induced during fungus-fungus confrontation, suggesting different functions for these two beta-glucan-binding lectins. Our results highlight the importance of the beta-glucan cell wall component in plant-fungus interactions and the potential of beta-glucan-binding lectins as specific detection tools for fungi in vivo

The Structure of RdDddP from Roseobacter denitrificans Reveals That DMSP Lyases in the DddP-Family Are Metalloenzymes

Marine microbes degrade dimethylsulfoniopropionate (DMSP), which is produced in large quantities by marine algae and plants, with DMSP lyases into acrylate and the gas dimethyl sulfide (DMS). Approximately 10% of the DMS vents from the sea into the atmosphere and this emission returns sulfur, which arrives in the sea through rivers and runoff, back to terrestrial systems via clouds and rain. Despite their key role in this sulfur cycle DMSP lyases are poorly understood at the molecular level. Here we report the first X-ray crystal structure of the putative DMSP lyase RdDddP from Roseobacter denitrificans, which belongs to the abundant DddP family. This structure, determined to 2.15 Å resolution, shows that RdDddP is a homodimeric metalloprotein with a binuclear center of two metal ions located 2.7 Å apart in the active site of the enzyme. Consistent with the crystallographic data, inductively coupled plasma mass spectrometry (ICP-MS) and total reflection X-ray fluorescence (TRXF) revealed the bound metal species to be primarily iron. A 3D structure guided analysis of environmental DddP lyase sequences elucidated the critical residues for metal binding are invariant, suggesting all proteins in the DddP family are metalloenzymes

Ocean Floor Observation and Bathymetry System (OFOBS): A new Towed Camera/Sonar System for Deep-Sea Habitat Surveys

Towed camera systems are commonly used to collect photo and video images of the deep seafloor for a wide variety of purposes, from pure exploratory research to the development of management plans. Ongoing technological developments are increasing the quantity and quality of data collected from the deep seafloor. Despite these improvements, the area of seafloor, which towed systems can survey, optically remains limited by the rapid attenuation of visible wavelengths within water. We present an overview of a new towed camera platform integrating additional acoustical devices: the ocean floor observation and bathymetry system (OFOBS). The towed system maintains continuous direct communication via fiber optic cable with a support vessel, operational at depths up to 6000 m. In addition to collecting seafloor photo and video data, OFOBS gathers sidescan data over a 100-m swath width. OFOBS functionality is further augmented by a forward looking sonar, used to aid in hazard avoidance and real-time course correction. Data collected during the first field deployments of OFOBS, at a range of seamounts on the Langseth Ridge/Gakkel Ridge intersection (86° N, 61° E) in the high Arctic in September 2016, are presented to demonstrate the functionality of the system. Collected from a location with near continuous ice cover, this explanatory data set highlights the advantages of the system for deep-sea survey work in environments currently difficult to access for the majority of subsurface research platforms

The Protection of the Dignity of Laboratory Animals in Switzerland

The article discusses the question whether Swiss law offers an equal level of protection for animals being used in research projects and those being genetically modified and bred for these projects. To answer this question the article argues, first, that animal dignity has a sacrosanct core content which prohibits highly cruel treatments or killing methods, denial of an animal’s essential natural needs as well as exclusive instrumentalization. However, a use that does not infringe the sacrosanct core can be justified by prevailing interests, as is the case within authorisation procedures of animal experimentation. During the approval procedure, the competent authority conducts a harm–benefit assessment to define, rate and evaluate the conflicting interests. Next, the article examines the issue of the breeding of genetically modified laboratory animals being subject to laxer requirements than other animal experiments. The projects are subject to a simplified procedure that does not include a “traditional” harm–benefit assessment. The article argues that the harm–benefit assessment is the key to a sufficient protection of laboratory animals and their dignity. Due to the purely “trailed” assessment as well as potential negligence in regard to reporting obligations regarding strains suffered by the animal, the application of the simplified procedure raises certain doubts as to whether it provides a sufficient protection of animal dignity. Moreover, it is argued that the breeding of genetically modified animals exclusively for test purposes constitutes an excessive instrumentalization of these animals. The article, therefore, weighs the instrumentalization against (human) interests, but holds that even if some prevailing interests are conceivable, the severe infringement of animal dignity cannot be justified

Lattice instabilities of cubic NiTi from first principles

The phonon dispersion relation of NiTi in the simple cubic B2 structure is computed using first-principles density-functional perturbation theory with pseudopotentials and a plane-wave basis set. Lattice instabilities are observed to occur across nearly the entire Brillouin zone, excluding three interpenetrating tubes of stability along the (001) directions and small spheres of stability centered at R. The strongest instability is that of the doubly degenerate M5' mode. The atomic displacements of one of the eigenvectors of this mode generate a good approximation to the observed B19' ground-state structure.Comment: 11 pages, 3 figure

Decentralized Autonomous Agents – Development of a Research Agent Service for the OLAS Protocol

Diese Arbeit behandelt die Entwicklung eines Recherche-Agenten-Service (RAS) auf Grundlage des OLAS-Protokolls, wobei zwei grundlegende Aspekte im Mittelpunkt stehen: Datenspeicherung und -abruf sowie Synchronisation. Konkret untersucht die Arbeit effiziente Datenstrukturen für umfangreiche textbasierte Daten und Techniken zur Erreichung von Strong Eventual Consistency in replizierten Datenbanken in dezentralen und potenziell byzantinischen Umgebungen. Als vorteilhaft wird das Vektor-Indexing-System SPFresh zur schnellen Datenabfrage und -aktualisierung identifiziert, ebenso wie die history-independent Datenstruktur der G+-Bäume zur Aufrechterhaltung global konsistenter Datensätze. Die Arbeit definiert G+-Bäume formal und stellt einen Algorithmus zur Einfügung und Aktualisierung von Baumelementen bereit. Zusätzlich werden Gk-Bäume eingeführt, die Performanceeinbußen bei bösartig konstruierten Datensätzen verringern. Zur Sicherstellung robuster Synchronisation zwischen Speicheragenten adaptiert die Arbeit das Range-Based Set Reconciliation-Verfahren (RBSR) für den Einsatz mit nicht-homomorphen Hash-Funktionen, wodurch im Vergleich zur RBSR mit homomorphen Hash-Funktionen weniger Speicherplatz benötigt wird. Diese theoretischen Beiträge ermöglichen sichere, speichereffiziente und nebenläufige Operationen auf Suchbaumstrukturen. Außerdem untersucht die Arbeit praktische Kompromisse wie Knotengrößen in Merkle-Suchbäumen sowie homomorphes gegenüber nicht-homomorphem Hashing. Über die theoretischen Beiträge hinaus bietet die Arbeit eine praktische Implementierung eines auf dem OLAS-Protokoll basierenden RAS. Diese Implementierung überwacht kontinuierlich Fragen aus Prediction Markets als Quelle für Suchinhalte, nutzt diese als Anfragen, um URLs aus einer Suchmaschine abzurufen, sammelt Daten von Webseiten, verarbeitet deren Vektor-Einbettungen und speichert die resultierenden Daten auf IPFS. Zukünftige Forschungsrichtungen umfassen die Integration eines iterativen Löschalgorithmus für G+-Bäume, die Untersuchung von Sharding-Strategien unter Speicheragenten zu maximaler Skalierbarkeit sowie die Erforschung von Methoden zur Validierung des Wahrheitsgehalts der von Speicheragenten gespeicherten Daten. Durch die vorgeschlagenen Datenstrukturen und Synchronisationsmechanismen, die für autonome Speicheragenten mit begrenzten Ressourcen geeignet sind, bildet diese Arbeit eine Grundlage für einen skalierbaren und dezentralen Recherche-Agenten-Service zur Handhabung umfangreicher textbasierter Daten und liefert Erkenntnisse, die auf breitere Anwendungen in verteilten Systemen und der künstlichen Intelligenz übertragbar sind.This thesis addresses the development of a Research Agent Service (RAS) on the OLAS protocol by focusing on two foundational aspects: data storage and retrieval, and synchronization. Specifically, it explores efficient data structures for large-scale textual data and techniques for strong eventual consistency across replicated databases in decentralized and potentially byzantine environments. The work identifies SPFresh as a vector index for fast retrieval and updates, alongside a history-independent data structure, G+-trees, for maintaining globally consistent datasets. It formally defines G+-trees and provides an algorithm for inserting and updating tree items. Additionally, Gk-trees are introduced that mitigate performance degradation for maliciously crafted datasets. To ensure robust synchronization among self-sovereign Storage Agents, the thesis adapts Range-Based Set Reconciliation (RBSR) to be used with non-homomorphic hash functions, which reduce the storage requirements compared to RBSR with homomorphic hash functions. These theoretical contributions facilitate secure, memory-efficient, and concurrent operations on search tree structures. The thesis also examines practical trade-offs such as node size in Merkle Search Trees, homomorphic versus non-homomorphic hashing. Beyond the theoretical work, it provides a practical implementation of a RAS deployed on the OLAS protocol. This implementation continuously screens prediction market questions as a source of research content, uses them as queries to retrieve URLs from a search engine, collects data from websites, processes their vector embeddings, and stores the resulting data on IPFS. Future research directions include integrating an iterative deletion algorithm for G+-trees, exploring sharding strategies among Storage Agents for efficient query routing, and investigating methods to validate the truthfulness of data to be stored by Storage Agents. By proposing data structures and synchronization mechanisms suitable for autonomous Storage Agents with constrained resources, this thesis constitutes a foundation for a scalable and decentralized Research Agent Service that handle large-scale textual data and provides insights that are applicable to broader applications in distributed systems and artificial intelligence