A Study of Erosion–Corrosion Behaviour of Friction Stir-Processed Chromium-Reinforced NiAl Bronze Composite

Corrosion is frequently viewed as a catastrophic and unavoidable disaster in marine applications. Every year, a huge cost is incurred on the maintenance and repair of corrosion-affected equipment and machinery. In the marine environment, as-cast nickel–aluminium bronze (NAB) is susceptible to selective phase corrosion. To solve this problem, chromium-reinforced nickel–aluminium bronze was fabricated using the friction stir process (FSP) with improved microstructures and surface properties. A slurry erosion–corrosion test on as-cast and FSPed composites demonstrated that the developed surfaced composite has lower erosion and corrosion rates than the as-cast NAB alloy. The erosion–corrosion rate increased with a decrease in the impact angle from 90° to 30° for both as-cast NAB and prepared composites, exhibiting a shear mode of erosion. The specimens at impact angle 30° experienced more pitting action and higher mass loss compared with those at impact angle 90°. Due to increases in the mechanical properties, the FS-processed composite showed higher erosion resistance than the as-cast NAB alloy. Furthermore, corrosion behaviour was also studied via the static immersion corrosion test and electrochemical measurements under 3.5 wt.% NaCl solution. In a static immersion corrosion test, the FSPed composite outperformed the as-cast NAB composite by a wide margin. The FSPed composite also demonstrated a reduced electrochemical corrosion rate, as revealed by the polarization curve and electrochemical impedance spectroscopic (EIS) data. This reduced rate is attributed to the formation of a Cr oxide film over its surface in the corrosive environment.     

The transition of pemphigus vulgaris into pemphigus foliaceus: a reflection of changing desmoglein 1 and 3 autoantibody levels in pemphigus vulgaris

The transition of pemphigus vulgaris (PV) into pemphigus foliaceus (PF) is rare and the immunological changes underlying this event are not well understood. We report a 44-year-old woman who presented with oral and cutaneous erosions typical of PV. Over a 9-year period, the clinical features evolved into those of PF. To examine whether quantitative changes in desmoglein (Dsg) antibodies were associated with this transition, Dsg1 and Dsg3 antibody levels were measured by enzyme-linked immunosorbent assay in 82 sequential serum samples collected over this period. At presentation, when the phenotype was PV with oral and cutaneous erosions, antibodies to both Dsg1 and Dsg3 were detected. The disappearance of oral involvement was associated with a decline in Dsg3 antibodies, which are now undetectable, while the development of more severe skin involvement was associated with rising Dsg1 antibody levels. These data strongly suggest that the change in clinical features is a reflection of qualitative and quantitative changes in antibody profile. It is not known whether the transition to PF is permanent or whether disease relapses in the future may be associated with the re-emergence of Dsg3 antibodies, oral ulceration and a PV phenotype.     

Platelet glycoprotein IIb/IIIa inhibition using eptifibatide with primary coronary stenting for acute myocardial infarction: a 30-day follow-up study.

The results of primary coronary stenting for acute myocardial infarction (AMI) have been reported to improve significantly with the concomitant administration of platelet glycoprotein IIb/IIIa inhibitor abciximab. There are, however, no data available with the use of eptifibatide, a more cost-effective, small-molecule GP IIb/IIIa blocker with a shorter half-life. In a prospective multicenter feasibility and efficacy study, we assigned 55 consecutive patients with AMI being taken up for primary stenting to receive eptifibatide just before the procedure (two boluses of 180 microg/kg 10 min apart and a 24-hr infusion of 2 microg/kg/min). Clinical outcomes were evaluated at 30 days after the procedure. The angiographic patency of the vessel with TIMI flow rates, TIMI myocardial perfusion (TMP) grade, and corrected TIMI frame counts were assessed at the end of procedure and before hospital discharge. At 30 days, the primary endpoint, a composite of death, myocardial infarction, and urgent target vessel revascularization (TVR) was seen in 12.7% of patients. The TIMI 3 and TMP grade 3 flow, which was seen in 93% and 86% of patient, respectively, at the end of the procedure, declined to 86% and 78%, respectively (P < 0.05) before hospital discharge. Corrected TIMI frame counts also decreased from 25.7 +/- 7.2 to 22.9 +/- 6.8 (P < 0.05). There were five (9.1%) instances of subacute thrombosis (SAT) presenting as AMI, needing urgent TVR in all, within 3-5 days of the primary procedure. No excessive bleeding complication, directly attributable to the use of eptifibatide, was observed. The study was terminated prematurely because of an unacceptable SAT rate. Administration of eptifibatide along with primary stenting for AMI is associated with a high TIMI 3 and TMP grade 3 flow acutely. However, these flows decline significantly before hospital discharge and lead to a high rate of SAT. The dosage and duration of infusion of eptifibatide in this setting needs further evaluation.     

Embolization of a Wiktor stent within a stent: Successful nonsurgical management

A case of embolization of an unexpanded Wiktor stent while attempting to traverse an expanded Wiktor stent is reported. The embolized stent was subjected to longitudinal axial traction, using a balloon catheter to cause stretching and partial unraveling. This partially unraveled stent was deployed across the dissection to scaffold it. The patient had no postprocedure complications. © 1996 Wiley-Liss, Inc.