In situ observation of intergranular crack nucleation in a grain boundary controlled austenitic stainless steel.

Grain boundary engineering has been proposed to increase the lifetime performance of sensitized austenitic stainless steel in aggressive environments. Increased microstructure resistance is typically associated with higher fractions of twin (Sigma3) grain boundaries, but there is uncertainty about the properties and role of other boundaries. To develop predictive models for stress corrosion crack nucleation, more information is required about how grain boundary crystallography and the orientations of the grain boundary plane and its surrounding grains affect crack development. Digital image correlation combined with electron backscatter diffraction has been used to characterize the microstructure and to observe, in situ, the nucleation and propagation of short stress corrosion cracks in thermo-mechanically processed type 304 stainless steel. The crack path and its growth rate have been determined and are found to be influenced by the microstructure.

Left atrial aneurysm.

Aneurysms of the left atrium are rare abnormalities. They can be congenital or acquired. Whereas a true congenital aneurysm presents as isolated pathology, inflammatory or degenerative processes involving the endocardium are associated with the acquired type. The clinical records of 2 patients with the diagnosis of left atrial aneurysm were reviewed, along with the surgical strategies, current literature, and patient outcomes. Because of the risk of life-threatening complications, surgery is recommended even in asymptomatic cases. Resection and mitral valvuloplasty should be the treatment of choice.

Ectopia cordis and other midline defects.

BACKGROUND: Thoracic ectopia cordis and other midline defects are rare congenital anomalies that often occur with other intracardiac defects. Despite significant improvements in neonatal and infant cardiac surgeries, operations for thoracoabdominal ectopia cordis carry an extremely high mortality with only a few reported survivors of thoracic ectopia cordis. METHODS: The clinical charts of 4 patients with ectopia cordis over a 6-year period were reviewed. Three of the patients showed varying degrees of Cantrell's Pentalogy; thoracic ectopia cordis was found in 1. We have reviewed our surgical strategies and reported the patients' clinical outcomes. RESULTS: All 4 patients are alive at follow-up. Two infants with double-outlet right ventricle have been fully corrected, and extracorporeal membrane oxygenation was necessary in 1 infant for cardiac failure following the cardiac repair. A newborn with thoracoabdominal ectopia cordis underwent primary repair of his diaphragmatic defect, and a silo was used to progressively reduce the omphalocele. He is currently awaiting elective repair of tetralogy of Fallot. Lastly, the patient with thoracic ectopia cordis underwent successful soft tissue coverage, and she is being followed in the clinic with restrictive muscular ventricular septal defects and a left ventricular diverticulum. CONCLUSIONS: Our experience along with other reports in the literature demonstrates that patients with thoracic and thoracoabdominal ectopia cordis can undergo and survive full cardiac, neurologic, and abdominal repair during infancy. Furthermore we advocate different approaches determined by the severity of the presentation and the presence of other complicating factors.

Effects of storage conditions on rat brain ethanolamine glycerophospholipids, cerebrosides, and cholesterol.

The effects of storage on rat brain lipid composition were studied in terms of ethanolamine glycerophospholipid, cerebrosides, and cholesterol. Rat brains were stored at several combinations of temperature and time. Storage conditions were: 2 hr at room temperature, 12 hr of refrigeration, and a sequence of both of these conditions. Two-dimensional thin layer chromatography followed by colorimetric analyses of eluted lipids were used to determine molar ratios of phosphatidylethanolamine, ethanolamine plasmalogen, lysophosphatidylethanolamine, and cerebrosides. Cholesterol was also determined. These studies revealed small but significant increases in lysophosphatidylethanolamine in all three cases. A slight increase was also noted in the apparent molar proportion of cholesterol.