The erosion-corrosion behaviour of copper-nickel alloys

The research focuses on an investigation of the erosion-corrosion behaviour of Cu-Ni-base alloys in aqueous environments. The principal objectives of the research were to examine the fundamental mechanisms of the erosion-corrosion attack. The work was focused on a standard Cu-10%Ni alloy that is used extensively in a variety of marine industries and on Marinel alloy, which is a high strength precipitation-hardened copper-nickel alloy. Erosion-corrosion tests were carried out for exposure times up to 72 hours, in a solid free 3.5% NaCl solution impinging at velocities of 2.38-86 m/sec, (Re=4500-86000), at temperatures of 19°C and 35°C. The overall erosion-corrosion behaviour and the direct corrosion component were monitored using gravimetric and electrochemical-monitoring techniques. Contributes from mechanical erosions were assessed by cathodically protecting specimens under impingement conditions. The research also considered the influence of various parameters such as temperature, time, velocity, salinity variations, and impingement angle. The extent and morphology of material deterioration and protective film formation under various environmental conditions were assessed, utilizing surface profiling equipment and light optical and scanning electron microscopy. The work has quantified the complex contributions of corrosion, erosion and synergy to the overall erosion-corrosion material loss. An important finding was the substantial superior erosion-corrosion resistance of Marinel compared to the standard Cu-10%Ni, with interesting effects of impinging velocity and time of exposure being observed. Also this work provided some clear evidence of significant potential benefits in terms of erosion-corrosion resistance, obtained by the exposure of Marinel at the elevated temperature

Superposition Formulas for Darboux Integrable Exterior Differential Systems

In this paper we present a far-reaching generalization of E. Vessiot's analysis of the Darboux integrable partial differential equations in one dependent and two independent variables. Our approach provides new insights into this classical method, uncovers the fundamental geometric invariants of Darboux integrable systems, and provides for systematic, algorithmic integration of such systems. This work is formulated within the general framework of Pfaffian exterior differential systems and, as such, has applications well beyond those currently found in the literature. In particular, our integration method is applicable to systems of hyperbolic PDE such as the Toda lattice equations, 2 dimensional wave maps and systems of overdetermined PDE.Comment: 80 page report. Updated version with some new sections, and major improvements to other

Clinical Assays in Sepsis: Prognosis, Diagnosis, Outcomes, and the Genetic Basis of Sepsis

Sepsis is the most widespread medical disorder of the intensive care unit (ICU) and the most common cause of death in hospitalized patients. Several endothelium-related molecules have been investigated as potential biomarkers for early diagnosis and/or prognosis of sepsis, providing different results depending on study designs. Therefore, it seems that we are still far from the right combination of sepsis markers to be used in clinical practice. It is more probable that a panel of diverse biomarkers will be more efficient in clinical practice. More recently, the potential use of genetic biomarkers for prognostic purposes started emerging for sepsis, in the form of genome-wide association studies. The successful use of modern molecular diagnostics could enable rapid identification of particularly susceptible or less susceptible individuals, leading to tailored therapeutic treatments

Provenance, manufacturing and corrosion behavior of Ancient Hellenistic coins from Egypt

Some copper alloy coins of the Ptolemaic period from a private collection, providing valuable evidence for both archaeometric as well as materials science and corrosion studies, have been investigated. The coins were found in the ancient city of Bubastis, known as Tell Basta, in the Nile Delta, Egypt. The coins have been examined by optical microscopy for their metallurgical structure, analysed by X-ray fluorescence and Electron Dispersion Spectroscopy for their composition, and by X-ray diffraction for the characterisation of their corrosion products. An attempt has been made to remove part of their corrosion products by mild chemical cleaning procedures. In some areas the coins are heavily corroded by chlorides, however most of the inscriptions on the coins themselves are still decipherable. Assumptions are made on the coins provenance, the production period, the manufacturing technique and the burial environmental conditions

Atrial Fibrillation in the Young: A Neurologist’s Nightmare

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia seen in clinical practice with prevalence in excess of 33 million worldwide. Although often asymptomatic and until recently considered a “benign” arrhythmia, it is now appreciated that thromboembolism resulting from AF results in significant morbidity and mortality predominantly due to stroke. Although an arrhythmia more commonly affecting the elderly, AF can also occur in the young. This review focuses on the impact of AF in the younger population and discusses the dilemmas of managing younger patients with AF