Statistical Study of the Corrosion Behavior of Al2CuMg Intermetallics in AA2024-T351 by SKPFM

A statistical study combining atomic force microscopy, scanning Kelvin probe force microscopy (SKPFM), and energy-dispersive spectroscopy was carried out on more than 300 Al2CuMg intermetallic particles of AA2024 alloy to determine their corrosion behavior in chloride-containing solutions. The combination of these three techniques allowed the correlation of the dissolution depth of the S-phase particles to their SKPFM potential and their chemical composition. This study also revealed that SKPFM measurements must be carried out with many precautions, but it is a powerful tool for the study of localized corrosion

Combination of AFM, SKPFM, and SIMS to Study the Corrosion Behavior of S-phase particles in AA2024-T351

The dissolution mechanism of S-phase particles in 2024-T351 aluminum alloy at open-circuit potential in chloride-containing sulfate solutions was investigated using atomic force microscopy (AFM), scanning Kelvin probe force microscopy (SKPFM), and secondary ion mass spectroscopy (SIMS). The combination of the three techniques allowed the correlation between SKPFM measurements and the corrosion behavior of AA2024 to be confirmed, leading to a better understanding of the electrochemical behavior of S-phase particles. A three-step mechanism for the dissolution and accompanying processes occurring near S particles was proposed: (i) preferential aluminum and magnesium dissolution, (ii) galvanic coupling between the copper-enriched particles and the surrounding matrix, leading to an increased passivity of the matrix around the particles, and (iii) copper deposition around the corroded particles

Quantity and Quality of Suspended Particulate Organic Matter Upstream and Downstream of a Series of Surface-Release Impoundments on the Upper Mississippi River

Through the continual flow of water in lotic systems, upstream impacts may be observed in downstream reaches. The River Continuum Concept classifies and describes abiotic and biotic processes as a river flows from headwaters to mouth. Disruptions of the theoretical system by impoundments are described by the Serial Discontinuity Concept that predicts, among other things, changes in biotic and abiotic stream processes. This study observed four surface-release impoundments on the Upper Mississippi River and documented impacts on the quantity and quality of fine particulate organic matter (FPOM) and looked for evidence of the Serial Discontinuity Concept. It was hypothesized that there would be an increase in the FPOM downstream of the impoundments, that there would be an impact on the quality of the FPOM, and that there would be evidence to support the Serial Discontinuity Concept. Three scenarios were observed in the quantity of the FPOM. 1) No difference between above and below sampling sites, 2) higher amounts of FPOM above the impoundments, and 3) higher amounts of FPOM below the impoundments. The hypothesis that there would be an increased amount of FPOM was supported by the third scenario. The results did not support the hypothesis that there would be an impact on the quantity of FPOM, there were no significant differences in phosphorus content between sampling sites. Disconnected sections of the river were found in support of the Serial Discontinuity Concept

Density functional theoretical study of Cun, Aln (n = 4–31) and copper doped aluminum clusters: Electronic properties and reactivity with atomic oxygen

A DFT study of the electronic properties of copper doped aluminum clusters and their reactivity with atomic oxygen is reported. Firstly we performed calculations for the pure Cun and Aln (n = 4, 9, 10, 13, 25 and 31) clusters and we determined their atomization energy for some frozen conformations at the B3PW91 level. The calculated work functions and M–M (M = Cu, Al) bond energies of the largest clusters are comparable with experimental data. Secondly, we focused our attention on the change of the electronic properties of the systems upon the substitution of an Al atom by a Cu one. This latter stabilizes the system as the atomization energy of the 31- atoms cluster increases of 0.31 eV when the substitution is done on the surface and of 1.18 eV when it is done inside the cluster. We show that the electronic transfer from the Al cluster to the Cu atom located at the surface is large (equal to 0.7 e) while it is negligible when Cu is inserted in the Aln cluster. Moreover, the DOS of the Al31 and Al30Cu systems are compared. Finally, the chemisorption energies of atomic oxygen in threefold sites of the Al31, Cu31 and Al30Cu clusters are calculated and discussed. We show that the chemisorption energy of O is decreasing on the bimetallic systems compared to the pure aluminum cluster

Conflict Minerals and Crimes Against Humanity in the DRC: How to Hold Individual Corporate Officers Criminally Liable

International criminal law is concerned with holding perpetrators responsible for the gravest crimes committed by humanity. The larger and more heinous the crime, however, the more complicated the prosecution. Identifying the relevant actors, producing sufficient evidence to impose liability, and bringing criminals to justice is a challenging endeavor. This complex process becomes even more daunting when factoring in complicit actors. This Note discusses the different legal mechanisms to hold individual corporate officers criminally liable for complicity in committing crimes against humanity and other human rights atrocities in the Democratic Republic of the Congo (“DRC”) as a result of their participation in the conflict mineral trade. Part I provides an overview of the conflict in the DRC, where rebel groups have profited off the conflict mineral trade for over a decade, committing atrocious crimes against civilians in their wake, and then addresses how corporations have contributed to the ongoing violence. Next, Part II defines the elements of crimes against humanity and analyzes how the atrocities committed in the DRC satisfy them. Then, Part III addresses the three potential mechanisms of liability: accomplice liability, superior responsibility, and joint criminal enterprise: category three (“JCE III”), by looking at each mechanism’s elements and any differences between the different international courts. Finally, Part IV applies each of these legal mechanisms to the actions of individual corporate officers in facilitating these crimes in the DRC by way of financing the conflict mineral trade and analyzes whether or not these actors could be liable for their actions

The Wind Tunnel Simulation and Effect of Turbulent Air flow on Automotive Aerodynamics

This thesis presents the research completed to design, commission and evaluate a turbulence generation system for Durham University’s 2m wind tunnel and the development of a method to simulate on road turbulence and measure its effects on a vehicle. The objective was to develop a test approach for simulating and analysing a vehicle’s response to unsteady airflows. This approach focussed on simulating the overlap of the range of turbulence frequencies which exist both at significant energy in the on road environment and the frequencies at which a significant vehicle response is seen. The frequency range where both conditions exist was seen to be between 1 – 10Hz. Confirmation of this transient frequency range was through the use of an admittance technique developed in this thesis which compares unsteady effects to quasi-steady effects. The technique was also developed to account for the component of unsteady pressure self excitedness that exists, effectively the noise component in an admittance analysis. The approach concluded with the operation of a new turbulence generation system (TGS), which simulates the wind characteristics experienced by vehicles as they move through the on road wind environment. The design was informed both by previous works and an on road investigation of environment and vehicle response. An on road study consisting of 8,800-seconds of on road measurements was completed to record incoming flow velocities and passenger sideglass static pressures (a region noted in studies to show a notable response to yawed flow). The on road environment was shown to have significant energy in the 0.1 10Hz range (reduced frequency K = 0.1 10 for a vehicle driving at highway speeds). Yaw angles ranged between ±20o, but with the vast majority within ±6o. Correspondingly, the turbulence intensity range was 0.5 15%, but with the majority below 8%. The challenges of generating turbulent length scales in the order of size of a vehicle’s length, whilst also at reasonable turbulent intensities were assessed to be beyond the capability of a passive device. Through a series of iterative CFD tests, an active “lift based” TGS was designed, based around two oscillating yaw aerofoils, which also encompassed additional inlet and outlets controlled by shutter panels. These ensured that the jet shear layer did not interact with the test model and helped to achieve higher peak yaw angles and good flow uniformity. A full aerodynamic design of the TGS was completed from the CFD studies, from which a high level mechanical design was specified including target aerofoil displacement and acceleration rates, control system requirements and the linkage design. The construction and installation of the TGS was undertaken by an external contractor. Due to its numerous configurable control parameters, a significant commissioning project was required and completed to determine the system’s optimum configuration. The system is capable of operating up to 10Hz at ±10o flow yaw angle and in a programmed arbitrary mode. The system also has the capability to generate pitch and longitudinal turbulence effects (Cooper et al (1989)). A 40% scaled model of the vehicle studied on the road was placed into the wind tunnel and a range of cases were generated including wind conditions previously recorded on road. The results showed that the technique of using both a roof mounted probe and the TGS system are able to take on road flow conditions and accurately recreate their effects on vehicles in a wind tunnel. Multiple aspects of the work (on road, CFD and wind tunnel) showed that below K = 0.3 pressure fluctuations behaved in a quasi steady manner. Admittance greater than unity was observed near the A pillar, but admittance was generally below unity and reduced progressively for K > 1. Self excitedness was seen to decrease in unsteady tests (in comparison to quasi steady) tests in the A pillar region, but increase between unsteady to quasi steady tests in the mirror wake region

Koreferat zu Kirstein/Schäfer - Erzeugt das Verbrauchsgüterkaufrecht Marktversagen?

Das Referat konzentriert sich auf die Frage, ob das Verbrauchsgüterkaufrecht europäischer Provenienz Marktversagen erzeugt. Dabei kommt es zu einem Ergebnis, welches der bisherigen Einschätzung und Bewertung eher widerspricht: Signalling ist weiterhin möglich, und im Ergebnis wird kein Marktversagen bewirkt. Dieser Befund mag für Ökonomen überraschend sein, denn sie stehen der Verbrauchsgüterkaufrichtlinie im Grundansatz skeptisch gegenüber. Unausgesprochen zugrundegelegt sind solcher Skepsis liberale Vorstellungen vom Marktgeschehen, welche die Privatautonomie über alles stellen und Eingriffe in die Privatautonomie von vornherein mit Misstrauen betrachten. Der Befund ist dagegen aus juristischer Sicht nicht kontraintuitiv. Man konnte mit ihm rechnen. Die Realität ist der beste Beleg: Die Märkte für B2C-Verkäufe sind nicht zusammengebrochen. Sie existieren weiter. Dies ist auch kaum verwunderlich. Denn Konsumenten haben weiterhin Bedarf, und Anbieter bemühen sich weiterhin, diesen Bedarf zu decken.

Modelling the corrosion behaviour of Al2CuMg coarse particles in copper-rich aluminium alloys

The corrosion behaviour of 2024 aluminium alloy in sulphate solutions was studied; attention was focused on the influence of coarse intermetallic Al2CuMg particles on the corrosion resistance of the alloy. Model alloys representative of the aluminium matrix and of Al2CuMg coarse intermetallics were synthesized by magnetron sputtering. Open-circuit potential measurements, current–potential curve plotting and galvanic coupling tests were performed in sulphate solutions with or without chlorides. Further explanations were deduced from the study of the passive films grown on model alloys in sulphate solutions. The results showed that model alloys are a powerful tool to study the corrosion behaviour of aluminium alloys